WO2004024987A1 - Method of treatment for reducing elution of lead from lead containing copper alloy and waterwork utensils made from lead containing copper alloy - Google Patents

Abstract

A method of treatment for reducing the elution of lead from a lead-containing copper alloy, characterized in that it comprises immersing the lead-containing copper alloy in an acidic solution which is free of chromic acid and contains a phosphoric acid or its derivative, to remove the lead in a surface portion thereof; and waterwork utensils made of a lead-containing copper alloy and treated by the method. The utensils having been treated by the method exhibit satisfactorily effective reduction in the elution of lead, and also are free from significant discoloration and from the reduction of its commercial value due to discoloration since only a little etching takes place owing to an acidic phosphoric acid or its derivative and only a fine phosphate film is formed. Further, sodium chloride may be added, the lead-containing copper alloy may be, in advance, immersed in an alkaline etching fluid, to remove the lead in a surface portion thereof, and the outer surface of the alloy may have been plated with a metal such as nickel-chromium.

Description

Lead elution reduction treatment method for lead-containing copper alloy and lead-containing copper alloy water supply equipment

 The present invention relates to a lead elution reduction treatment method for reducing the elution of lead from a lead-containing copper alloy, and to a lead-containing copper alloy water supply device with reduced lead elution.

 Water supply equipment includes faucet fittings, water meter meters, water heater components, hot water flush toilet seat components, water heaters, water heaters, water coolers, ice makers, Joda water heaters, hot water boilers, vending machines, Includes all equipment that connects to the water supply pipe, such as rutap, low tank, valve, flush valve, heat exchanger, fittings, water supply and hot water supply header, pipe, sink, wash basin, toilet bowl, bathtub, and housing equipment unit. Background art

 Conventionally, water supply appliances such as faucet fittings are generally made or forged of copper or a copper alloy material such as bronze or brass, and are shaped by cutting, polishing, etc., and nickel-chrome plating, painting, It is manufactured through various surface treatments such as ion plating and the final product assembly process. In many cases, lead is added to the above-mentioned copper alloys in order to improve workability such as machinability, so that a small amount of lead is eluted into drinking water. In recent years, there has been a concern that this may have a negative effect on water quality.

The authors, in Patent No. 318,765, focused on the form of lead and its physical properties, and immersed a lead-containing copper alloy in an alkaline etching solution, chromic acid solution, and chromate solution. An invention that significantly reduces the elution of glycerol was announced. '' Among the lead elution reduction methods described in Patent No. 3 182 7 65, among the chromate treatment methods, a lead-containing copper alloy may be immersed in a solution containing both chromic acid and phosphoric acid at the same time. It was announced that lead elution was most effective. However, when the lead-containing copper alloy is immersed in this chromate solution, the appearance of the copper alloy part after immersion has a whitish discolored appearance, which may reduce the commercial value. This This is probably because a colored film is formed on the surface of the copper alloy by the link chromatization treatment comprising chromic acid and phosphoric acid.

 The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for reducing lead elution of a lead-containing copper alloy which does not reduce its commercial value due to discoloration of appearance, and a lead-containing copper alloy water supply. The equipment is provided. Disclosure of the invention

 In order to achieve the above object, Claim 1 is characterized in that a lead-containing copper alloy is immersed in an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution to remove lead on the surface. This is a method for reducing lead elution of a lead-containing copper alloy.

 Therefore, since only a slight etching effect and a minute phosphoric acid film are formed by the acidic phosphoric acid compound, there is no significant discoloration and the commercial value is not reduced. It is also effective enough to reduce lead elution.

 In order to achieve the above object, claim 2 is characterized in that a lead-containing copper alloy is immersed in an acidic solution containing a phosphoric acid compound and sodium chloride without containing chromic acid in the solution. This is a method for reducing lead elution of a copper alloy.

 Therefore, by adding an appropriate amount of sodium chloride to the acidic phosphoric acid compound, the progress of the reaction is improved, the etching effect and the phosphoric acid film are increased, and a stable appearance can be secured. Product value does not decrease. It is also effective enough to reduce lead solutes. In order to achieve the above object, claim 3 is that a lead-containing copper alloy is immersed in an alkaline etching solution to remove lead on the surface, and then the solution is free of chromic acid and contains a phosphoric acid compound. This is a method for reducing lead elution of a lead-containing copper alloy, characterized by being immersed in a solution.

Therefore, the lead on the surface of the copper alloy can be almost selectively removed by immersion in an etching solution having an alkaline force.Therefore, an acid solution immersion process that does not contain chromic acid but contains a phosphoric acid compound in the solution in the subsequent process Combined with the effect of reducing lead elution, a more sufficient effect on reducing lead elution is recognized. In addition, even after these processes, only a small amount of etching effect and a minute phosphoric acid film are formed by the acidic phosphoric acid compound. . In order to achieve the above object, the scope of claim 4 is to immerse the lead-containing copper alloy in an alkaline etching solution to remove lead on the surface, and then contain a phosphoric acid compound and sodium chloride containing no chromic acid in the solution. A method for reducing lead elution of a lead-containing copper alloy, characterized by immersing the lead-containing copper alloy in an acidic solution containing.

 Therefore, since the lead on the copper alloy surface can be almost selectively removed by immersion in an alkaline etching solution, an acid solution immersion process that does not contain chromic acid but contains a phosphoric acid compound and sodium chloride in the solution in the subsequent process Combined with the effect of reducing lead elution, a more sufficient effect on reducing lead elution is recognized. Even after these steps, by adding an appropriate amount of sodium chloride to the acidic phosphoric acid compound, the progress of the reaction is improved, the etching effect and the phosphoric acid film are increased, and a stable appearance can be secured. Product value does not decrease. It is also effective enough to reduce lead solutes.

 In order to achieve the above object, the scope of claim 5 is characterized in that mainly the outer surface is subjected to a plating treatment, and the lead which is not plated is mainly removed from the inner surface. 3. A method for reducing lead elution of a lead-containing copper alloy according to item 3.

 Therefore, the portion of the outer surface that has been plated is subjected to a dissolution or etching reaction in the above-described immersion step using an alkaline etching solution or the immersion step using an acid solution containing a phosphoric acid compound without containing chromic acid in the solution. Since no discoloration occurs, discoloration does not occur, and the lead elution reduction effect can be achieved mainly only on the inner surface where the lead-containing copper alloy is exposed without being plated. Of course, the inner surface is not accompanied by a large discoloration because only a slight etching effect of the acidic phosphoric acid compound and a minute phosphoric acid film are formed.

 In order to achieve the above object, the scope of claim 6 is characterized in that, mainly, the plating on the outer surface is a plating in which chrome is applied after nickel plating. This is a method for reducing lead elution of a copper alloy.

Water-supply fixtures made of lead-containing copper alloys, such as faucet fittings, are often chrome-plated after nickel plating in order to impart decorativeness, corrosion resistance, abrasion resistance, etc. to the outer surface. This is the plating used. In this case, the immersion step using the alkaline etching solution described above, or the acidic step including a phosphoric acid compound is performed. Since no dissolution reaction or etching reaction occurs in the immersion step with the solution, discoloration does not occur, and a lead elution reduction effect can be achieved mainly only on the inner surface where the lead-containing copper alloy is exposed without being plated. Of course, the inner surface is not accompanied by a large discoloration because only a slight etching effect and a slight phosphoric acid film are formed by the acidic phosphoric acid compound.

 In order to achieve the above object, claim 7 is a lead-containing copper alloy water supply according to claims 1 to 6, characterized in that the tap is immersed in an acidic solution containing a phosphoric acid compound. Equipment.

 Therefore, since only a slight etching effect and a slight phosphoric acid coating are formed by the acidic phosphoric acid compound, the effect of reducing lead elution can be sufficiently reduced without causing significant discoloration of the surface of the lead-containing copper alloy. Therefore, it is possible to provide water supply equipment that does not reduce its commercial value. BRIEF DESCRIPTION OF THE FIGURES

 (FIG. 1) FIG. 1 is a view showing a faucet made of bronze ceramic used in an embodiment of the present invention.

 (FIG. 2) FIG. 2 (a) is an enlarged photograph of the surface of a lead-containing copper alloy water supply device before the lead elution reduction treatment of the lead-containing copper alloy according to the present invention, and (b) is a cross-sectional photograph thereof. is there.

 (Fig. 3) Fig. 3 (a) is an enlarged photograph of the surface of a lead-containing copper alloy water supply device after the lead elution reduction treatment of the lead-containing copper alloy according to the present invention, and (b) is a cross-sectional photograph thereof. is there. BEST MODE FOR CARRYING OUT THE INVENTION

By immersion in an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution of the present invention, a small amount of etching effect on the surface of the lead-containing copper alloy and a minute phosphoric acid film are formed. Not only does it have a significant effect on elution reduction, but it does not involve significant discoloration in appearance. This is due to the fact that the mixed coating of chromium and phosphorus is slightly colored, whereas the single coating of phosphoric acid is colorless. By adding an appropriate amount of sodium chloride as an activator to an acidic solution containing a phosphoric acid compound that does not contain chromic acid in the solution of the present invention, the progress of the reaction is improved, thereby achieving an etching effect and a fine phosphoric acid film. May increase, and a stable appearance may be secured. Examples of the activator include sodium chloride, sodium sulfate, sodium fluoride, sodium nitrate, and the like. The addition amount is about 0.1 to 10 g / L, and may be used alone or in combination.

 Phosphoric acid compounds include potassium phosphate, sodium phosphate, calcium phosphate, ammonium phosphate, zinc phosphate, etc., and the amount of addition is about 0.1 to 50 g ZL.Single or several kinds may be added. . Add an inorganic acid such as phosphoric acid, nitric acid, sulfuric acid, or hydrofluoric acid to make the solution containing these components acidic. The addition amount is about 0.1 to 50 g ZL, and it may be added alone or in several kinds. Further, organic acids such as acetic acid, oxalic acid, citric acid, formic acid, butyric acid, and propionic acid may be added. The pH of the solution is preferably 2 or less, more preferably 1 or less. As an additive, a metal compound such as zinc, iron, copper, manganese, and nickel may be appropriately added. Incidentally, chemical conversion treatment solutions of phosphates are widely marketed, and these may be used.

 The processing temperature is from room temperature to about 70 ° C, the processing time is between several seconds and several minutes, and it is appropriately determined according to the shape and size of the object to be processed. In the case of parts with complicated shapes, care should be taken not to create pockets of air when immersing in the solution, and the workpiece may be rocked to increase the processing efficiency. After the treatment, it is desirable to wash quickly, and then wash with hot water and dry with hot air in order to eliminate the bad appearance due to the remaining water droplets and water film.

Before immersion in an acidic solution containing a phosphoric acid compound without chromic acid in the solution, the lead on the lead-containing copper alloy surface can be selectively dissolved and removed by immersion in an alkaline etching solution. Good. Since lead is an amphoteric metal and does not form an alloy in the copper alloy and exists as a simple substance of lead, the base of the copper alloy hardly reacts with the alkali etching solution, and only the lead compound can be selectively dissolved and removed. Therefore, the load in the immersion step of an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution can be reduced. In addition, the degreasing process, which removes dirt such as oil components attached to the lead-containing copper alloy in the previous process, is an extremely efficient process. The main component of the alkaline etching solution is an alkaline solution in which one or several of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium phosphate, sodium tripolyphosphate, sodium metasilicate, sodium orthosilicate, etc. are dissolved. . The concentration is generally several g ZL to several 10 g ZL, and is appropriately determined depending on the combination of components used. The processing temperature is about 60 to 90 ° C., and the processing time is between several minutes to several ten minutes, which is appropriately determined according to the shape and size of the object to be processed. In the case of parts with complicated shapes, be careful not to create air pockets when immersing in the solution, and the workpiece may be swung to increase the processing efficiency. After the treatment, it is good to wash immediately and proceed to the next step.

 In order to improve the penetration and wettability of the alkaline etching solution, a surfactant may be added for the purpose of lowering the surface tension of the solution. As the surfactant, an anionic surfactant or a nonionic surfactant is often used, and these may be used alone or in combination. Examples of anionic surfactants include sodium higher fatty acids, sulfated oils, sodium higher alcohol sulfates, sodium alkylbenzene sulfate, sodium higher alkyl ether sulfates, and sodium alpha-refine sulfate. Examples of nonionic surfactants include alkyl polyoxyethylene ether, alkyl phenyl polyoxyethylene ether, fatty acid ethylene oxide adduct, and polypropylene glycol ethylene oxide adduct (pull nick). The amount of addition is generally from several g / L to several 10 g ZL. In addition, a chelating agent can be added to the alkaline etching solution to prevent lead from becoming a hydroxide and re-adhering, and to promote the dissolution of lead. As the chelating agent, for example, a compound which easily forms a complex with lead, such as EDTA, ethylenediamine, triethanolamine, thiourea, Rossier salt and tartaric acid, is desirable. The amount of addition is generally several g / L to several 10 g / L.

The addition of oxidizing agent to Al force Li of etching solution, lead is oxidized two step reaction which dissolves in alkaline occurs once through lead oxide (P b 0 _2). This reaction is quicker than the one-step reaction in which lead dissolves in the aluminum alloy, thereby accelerating lead removal, increasing removal efficiency and reducing processing time. Examples of the oxidizing agent include sodium metanitrobenzenesulfonate, sodium paranitrobenzoate, and the like. Use inorganic compounds such as organic oxidizing compounds, hypochlorite, bleaching powder, hydrogen peroxide, potassium permanganate, persulfate and perchlorate. The amount of addition is generally several g ZL to several 10 g ZL.

 Water faucet fittings and other water supply appliances are sometimes plated for the purpose of external aesthetics, corrosion resistance, abrasion resistance, and the like. There is no particular limitation for performing certain electroplating, chemical plating, displacement plating or dry plating. Of these, chrome plating after nickel plating using the electroplating method is the most common in terms of quality and cost. In addition, there are gold plating, silver plating, rhodium plating, platinum plating, copper plating, tin plating, tin-cobalt alloy plating, and tin-nickel alloy plating. Dry plating methods include vacuum deposition, ion plating, sputtering, and CVD methods, including titanium nitride, titanium carbide, zirconium nitride, chromium nitride, silicon carbide, diamond, alumina, and titanium carbonitride. In many cases, plating is hardly applied to the inner surface of lead-containing copper alloy water supply equipment such as faucet fittings, so the copper alloy base is exposed in that part. It is. In the present invention, the lead-containing copper alloy is immersed in the above-mentioned aluminum-based etching solution or an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution, so that any plated portion is not formed. It does not change and effectively removes lead from the exposed copper alloy.

 (Example)

 EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto, and it goes without saying that many modifications can be made within the technical idea of the present invention.

 Under the conditions shown below, the lead removal treatment was performed using the bronze ceramic faucet shown in Fig. 1 under various treatment conditions, and the appearance and the effect of reducing lead elution were evaluated (Experiment 1).

The treatment process was performed in the order of treatment with an acidic solution after alkali etching. FIGS. 2 (a) and 2 (b) and FIGS. 3 (a) and 3 (b) are enlarged photographs of the surface before and after the treatment and enlarged photographs of the cross section. If you compare these photos, after processing It can be seen that lead is eluted from 5 to 6 m from the surface.

 The appearance was visually inspected, and the effect of reducing lead elution was analyzed according to JIS-S-3200-7 (2000). Table 1 summarizes the processing conditions, appearance conditions, and lead elution amount. The alkaline etching conditions were the same, using a solution of sodium hydroxide 50 g / L + sodium paranitrobenzoate lg / L, at 80 ° C and 10 minutes.

 The appearance was rated as X, which was severely discolored and had a serious problem on the product, as V was a level with discoloration and had a problem on the product, and as a level was a level with little discoloration and no problem on the product.

 (Table 1) Processing conditions and experimental results of Experiment 1

これらの結果から明らかなとおり、 無水クロム酸とリン酸を両方含む酸性溶 液での処理では外観が変色するが、 各々単独の酸性溶液での処理では外観も問 題なく、 リン酸単独の方が鉛溶出量が少ないことがわかった。

As is evident from these results, the appearance changes when treated with an acidic solution containing both chromic anhydride and phosphoric acid.However, when treated with a single acidic solution, there is no problem with the appearance. It was found that the amount of eluted lead was small.

Next, lead removal treatment was performed with sodium chloride added to evaluate the appearance and the effect of reducing lead elution (Experiment 2). Processing process is alkali etching After that, the treatment was performed in the order of the treatment with the acidic solution. Appearance evaluation method and lead elution reduction effect

JIS-S-3200-7 (2000) The concentration of eluted lead was analyzed in accordance with the "Test Methods for Leaching Performance of Water Supply Appliances". Table 2 summarizes the appearance conditions and the amount of lead dissolved. The alkaline etching conditions were the same, using a solution of sodium hydroxide 50 g / L + sodium paranitrobenzoate 1 g / L, at 60 ° C for 5 minutes.

 The appearance condition is X for a level that is severely discolored and has a serious problem on the product, X indicates a level that has discoloration and a problem on the product, A indicates a level that has little discoloration and has no problem on the product, The level with no was judged as ◎.

 [Table 2] Processing conditions and results of experiment 2

これらの結果から明らかな通り、 塩化ナトリウムとリン酸を両方含む酸性溶 液での処理では外観がさらにおさえられ、 鉛溶出量も問題ないことがわかった 次に、 ニッケルめっき後クロムめつきを施した第 1図の青銅铸物製水栓金具 について、 各種処理条件で鉛除去処理をおこない、 外観の状態と鉛溶出低減効 果を評価した （実験 3) 。 処理工程は、 アルカリエッチングのあと、 酸性溶液 での処理の順で行った。 外観評価方法及び鉛溶出量の評価方法も実験 1と同じ 方法で行い、 外観は目視で、 鉛溶出低減効果は J I S-S-3 2 0 0-7 (2 0 0 0年） 「水道用器具一浸出性能試験方法」 にしたがって、 溶出した鉛濃度を分 祈した。 処理条件、 外観の状態及び鉛溶出量を表 2にまとめた。 尚、 アルカリ エッチングの条件は、 水酸化ナトリウム 50g/L +パラニトロ安息香酸ナトリウム lg/Lの液を使用し、 6 0°C、 5分の条件で統一した。

As is evident from these results, it was found that the treatment with an acidic solution containing both sodium chloride and phosphoric acid further reduced the appearance and had no problem with the amount of lead eluted.Next, chrome plating was performed after nickel plating. The lead faucet made of bronze ceramics shown in Fig. 1 was subjected to lead removal treatment under various treatment conditions, and the appearance and the effect of reducing lead elution were evaluated (Experiment 3). The treatment process was performed in the order of treatment with an acidic solution after alkali etching. Appearance evaluation method and lead elution amount evaluation method were also performed in the same manner as in Experiment 1. The external appearance was visually observed, and the effect of reducing lead elution was JI SS-3 200-7 (2000). According to the “Leaching Performance Test Method”, the concentration of eluted lead was prayed. Table 2 summarizes the processing conditions, appearance conditions, and lead elution amount. In addition, the conditions of the alkaline etching were unified at 60 ° C. for 5 minutes using a solution of 50 g / L of sodium hydroxide + lg / L of sodium paranitrobenzoate.

The appearance condition is X, which is severely discolored and has a major problem on the product, X is the level with discoloration and there is a problem on the product, and the level is that there is almost no discoloration and there is no problem on the product _C determined as 〇

(Table 3) Processing conditions and experimental results of Experiment 3

* E: There are no abnormalities such as discoloration at any of the nickel-chrome-plated parts on the surface. As is evident from these results, the bronze portion on the inner surface of the nickel-chrome-plated product is discolored when treated with an acidic solution containing both chromic anhydride and phosphoric acid. There was no problem, and it was found that the amount of lead eluted was smaller with phosphoric acid alone. Also, no abnormalities such as discoloration were observed in the nickel chrome-plated portion on the surface, and it was confirmed that the lead elution reduction method of the present invention can be used for plated products.

The present invention has the following effects by the above configuration. That is, acidic phosphoric acid compound Since only a slight etching effect and a minute phosphoric acid film are formed by the product, there is no significant discoloration and the commercial value does not decrease. In addition, by adding an appropriate amount of sodium chloride as an activator to an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution of the present invention, the progress of the reaction is improved, and the etching effect and fine phosphoric acid are reduced. The formation of a film increases, a stable appearance can be secured, and the effect of reducing lead elution is sufficiently effective. In addition, since the lead on the surface of the copper alloy can be almost selectively removed by immersion in an alkaline etching solution, the lead leaching effect is reduced in conjunction with the lead leaching effect of the acid solution containing a phosphoric acid compound in the subsequent process. Is more effective. In addition, even after these steps, the lead-containing copper alloy does not undergo significant discoloration and does not decrease its commercial value.

 In the part of the external surface that has been subjected to the plating treatment, a dissolution reaction or an etching reaction occurs in the immersion step using the above alkaline etching liquid or the immersion step using an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution. Since no discoloration occurs, the effect of reducing lead elution can be achieved mainly only on the inner surface where the lead-containing copper alloy is exposed without being plated. Of course, its inner surface does not undergo significant discoloration either.

 In many cases, water faucet fittings such as faucet fittings are made of nickel-chrome and then chrome-plated in order to provide decorativeness, corrosion resistance, abrasion resistance, etc. on the outer surface. This plating has been widely used in the past. In this case, no discoloration reaction or etching reaction occurs in the immersion step using the alkaline etching solution described above or in the immersion step using an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution. The lead elution reduction effect can be achieved mainly only on the inner surface where the lead-containing copper alloy is exposed without being plated. Of course, its inner surface does not undergo significant discoloration.

In the present embodiment, the plating process is performed before the immersion step using the acidic solution containing the phosphoric acid compound, but may be performed after the immersion step. Industrial applicability

 INDUSTRIAL APPLICABILITY The method for reducing lead elution of a lead-containing copper alloy and the lead-containing copper alloy water supply device according to the present invention can be used for various devices connected to a water supply pipe.

Claims

The scope of the claims  1. A method for reducing lead elution of a lead-containing copper alloy, which comprises immersing a lead-containing copper alloy in an acid solution containing a phosphoric acid compound without containing chromic acid in the solution. 2. A method for reducing lead leaching of a lead-containing copper alloy, which comprises immersing the lead-containing copper alloy in an acidic solution containing a phosphoric acid compound and sodium chloride without containing chromic acid in the solution.  3. The lead-containing copper alloy is immersed in an etching solution with a strong force to remove the lead on the surface, and then immersed in an acidic solution containing a phosphoric acid compound without chromic acid in the solution. For reducing lead elution of lead-containing copper alloys. 4. Immerse the lead-containing copper alloy in an etching solution that removes lead from the surface: remove it, and then immerse it in an acidic solution that does not contain chromic acid but contains a phosphate compound and sodium chloride. A method for reducing lead elution of a lead-containing copper alloy, comprising:  5. The method for reducing lead elution of a lead-containing copper alloy according to claim 1, wherein the outer surface is mainly subjected to a plating treatment.  6. The method for reducing lead elution of a lead-containing copper alloy according to claim 5, wherein the plating on the outer surface is performed mainly by applying chrome plating after nickel plating.  7. The lead-containing copper alloy water supply device according to any one of claims 1 to 6, wherein the device is immersed in an acidic solution containing a phosphoric acid compound without containing chromic acid in the solution.