JP2005240068A - Agent for forming hexavalent-chromium-free coating onto plated film of zinc or zinc-nickel alloy, and forming method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment liquid which stably forms a protective coating with uniform and adequate appearance and corrosion resistance on a zinc member, a zinc alloy member, a galvanized product or a zinc-alloy-plated product, without using hazardous hexavalent chromium, and to provide a method therefor. <P>SOLUTION: The treatment liquid for forming the hexavalent-chromium-free coating includes trivalent chromium, two or more anions selected from particular anions, three or more metallic ions selected from particular metallic ions, and one or more complexing agents selected from particular complexing agents. The method for forming the hexavalent-chromium-free coating includes contacting a substrate with the treatment liquid once or several times. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an agent and a method for forming a hexavalent chromium-free coating on a zinc member, a zinc alloy member, a galvanized product or a zinc alloy plated product.

  Generally, zinc or zinc-based alloy plating (for example, zinc-iron alloy plating, zinc-nickel alloy plating) is most widely used as a rust prevention method for iron-based materials and parts. However, since zinc is a rust-prone metal and white rust, which is the rust of zinc, is generated immediately when used as it is, it is generally common to form a protective film.

  The chromate film treatment is generally used as a protective film treatment usually applied to zinc plating or zinc alloy plating. The chromate film treatment is further classified into three types: electrolytic chromate treatment, coating chromate treatment, and reactive chromate treatment. The The chromate treatment is applied not only to zinc but also to aluminum, cadmium and magnesium.

  Chromate film treatment is widely used because it is inexpensive and easily obtains practical corrosion resistance. However, since all chromate film treatment uses harmful hexavalent chromium, it elutes not only from the treatment solution but also from the treated product. In recent years, hexavalent chromium has become a serious problem because it has a negative effect on the human body and environment.

  Various inventions have been filed so far for solving the problem of pollution of hexavalent chromium. For example, Japanese Patent Application Laid-Open No. 52-92936, Japanese Patent Application Laid-Open No. 50-1934, and Japanese Patent Application Laid-Open No. 61-587. JP-A-2000-234177, JP-A-61-119677, and the like. Although these inventions can be noted in that no hexavalent chromium is used, practical performance is not satisfactory. For example, in the salt spray test stipulated in JIS Z 2731, the corrosion resistance that is stably exhibited is about 12 to 84 hours, which is only 1/20 to 1/2 or less of commonly used colored chromate and black chromate. Absent.

  As a specific problem, Japanese Patent Application Laid-Open No. 52-92936 treats zinc or a zinc alloy with an aqueous solution containing titanium ions and one or more of phosphoric acid, phytic acid, tannin, and hydrogen peroxide. Although the invention characterized by the above is disclosed, the corrosion resistance in salt spray is as low as about 240 hours even when the coating is baked after being processed on a steel plate, complicated and at a high temperature for a long time.

  JP-A-50-1934 discloses a colorless glossy chromate composition of zinc or a zinc alloy comprising a mineral acid, a compound that generates trivalent chromium ions, a carboxylic acid, and, if necessary, a reducing agent. ing. With this composition, it is possible to obtain a uniform gloss chromate appearance on zinc or a zinc alloy, but the corrosion resistance in salt spray is very low performance of 48 hours or less until the occurrence of white rust. The composition was poor in stability.

  Japanese Patent Application Laid-Open No. 61-587 describes a composition containing trivalent chromium ions, silicates, fluorides and acids. The coating obtained by this composition also has a uniform glossy chromate appearance, but the corrosion resistance is a low performance of 24 hours or less until white rust occurs.

  Japanese Patent Application Laid-Open No. 2000-234177 discloses a chemical conversion treatment for zinc or a zinc alloy comprising an aqueous solution containing a trivalent chromium compound and at least one metal compound selected from a titanium compound, a cobalt compound, a tungsten compound and a silicon compound. The liquid is described. This treatment solution is expected to provide a conversion coating having a relatively high corrosion resistance, but there are large variations for practical use in industry, the treatment conditions are relatively high and long, and the drying temperature is also high. In addition to the high temperature and long time compared to the conventional method, the described treatment liquid has a problem of poor stability and precipitation in a few days. The resulting coating looks like a glossy chromate like the others.

  JP-A-61-119677 discloses trivalent chromium ions, hydrogen ions, additional ions selected from iron, cobalt, nickel, molybdenum, manganese, aluminum, lanthanum, cerium, lanthanides and mixtures thereof; An acidic composition containing nitrate ions is described. In addition, compositions containing halogen ions, organic carboxylic acids or silicates are described. With this composition, it is possible to obtain a uniform gloss chromate appearance on zinc, but the corrosion resistance in salt spray is not sufficient, and it takes about 72 hours until white rust occurs. In particular, a composition using an organic acid has poor liquid stability, and has a problem that the appearance of the treatment and the pH of the liquid change in several days to several weeks.

  The invention described in Japanese Patent Publication No. 63-15991 has environmental problems such as wastewater treatment because it contains fluorine in its components.

  Japanese Patent Application Laid-Open No. 2000-509434 also has an environmental problem because the component contains an organic acid.

  In addition, Japanese Patent Publication No. 3-10714 and Japanese Patent Application Laid-Open No. 2000-54157 have the same problems as described above.

  Recently, Japanese Patent No. 3332373 and Japanese Patent No. 3332374 show a technology in which the molar ratio of trivalent chromium to oxalic acid is limited. However, since oxalic acid acts as a strong chelating agent, chromium, cobalt, zinc In addition to environmental problems such as iron or nickel (dissolved and dissolved from the plating film by the treatment) and forming a water-soluble complex and hindering the formation of a poorly soluble precipitate, the wastewater treatment is hindered. There were also problems such as poor liquid stability and no formation on zinc-nickel alloy plating, which was not satisfactory.

  As described above, the conventional techniques generally have insufficient corrosion resistance, non-formation in alloy plating (especially zinc-nickel alloy plating), non-uniform appearance, insufficient stability, and low cost performance (performance obtained under processing conditions). I had an environmental problem.

JP-A-52-92936 Japanese Patent Laid-Open No. 50-1934 Japanese Patent Laid-Open No. 61-587 JP 2000-234177 A JP-A-61-119677 Japanese Patent Publication No. 63-15991 JP 2000-509434 A Japanese Patent Publication No. 3-10714 JP 2000-54157 A Japanese Patent No. 3332373 Japanese Patent No. 3332374

  The object of the present invention is to provide a uniform and good appearance and corrosion resistance without using harmful hexavalent chromium in forming a protective film on the surface of metal, particularly zinc, zinc alloy, galvanized product or zinc alloy plated product. An object of the present invention is to provide a treatment liquid and a method for stably producing a combined film. In particular, it is to obtain excellent corrosion resistance, design properties, cost performance, and stability, which are obstacles to the practical application of alternative technologies that have been invented so far.

  As a result of intensive studies conducted by the present inventors to solve the problems in the prior art, it is possible to avoid the use of a large amount of fluorine, organic acid, chelating agent, and phosphorus compounds that cause environmental problems in the prior art. A film having a uniform and excellent appearance can be obtained. Moreover, it discovered that the further external appearance improvement and the improvement of corrosion resistance can be aimed at by processing with a specific liquid composition after film formation.

  The present invention includes (A) trivalent chromium; (B) two or more kinds of anions selected from the group consisting of sulfate ion, nitrate ion, chlorine ion, chlorine oxyacid ion and boron oxyacid ion; C) Three or more metal ions selected from the group consisting of alkali metals, alkaline earth metals, titanium, zirconium, vanadium, molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, tin, and aluminum And (D) selected from the group consisting of tartaric acid, citric acid, malic acid, lactic acid, succinic acid, butyric acid, gluconic acid, glutamic acid, glycolic acid, diglycolic acid, ascorbic acid, ammonia, amine compounds and salts thereof A hexavalent chromium-free chemical coating on a zinc member, zinc alloy member, galvanized product or zinc alloy plated product containing one or more complexing agents It is based on a liquid having a pH of 0.5 to 6 for forming, and further contains a silicon compound and further an oxalate ion and / or a malonate ion for further improving the appearance and corrosion resistance (hereinafter referred to as “No. One treatment solution ”). In particular, tartaric acid, citric acid, malic acid, lactic acid, succinic acid, glycolic acid, diglycolic acid and their salts are preferred as the complexing agent, and the metal ions are alkali metal, alkaline earth metal, titanium, vanadium, manganese, cobalt Preferably, at least three kinds are selected from the group of metal ions consisting of nickel and tin. The alkali metal includes lithium, sodium, potassium, rubidium, cesium, and francium, and the alkaline earth metal includes beryllium, magnesium, calcium, strontium, barium, and radium. Examples of oxyacid ions of chlorine include chlorate ions, chlorite ions, hypochlorite ions, and perchlorate ions. Examples of oxyacid ions of boron include borate ions. Examples of the amine compound include methylamine, ethylamine, propyleneamine, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, and polyethyleneimine.

  The pre-treatment liquid before treatment with the first treatment liquid includes trivalent chromium, surfactant, silicon compound, inorganic acid ion, organic acid ion, ammonium ion, amine compound, hydroxide, metal ion and A treatment liquid containing at least one selected from the group consisting of these salts is preferred.

  Moreover, as a 2nd process liquid further processed after processing with this 1st process liquid, the 2nd process liquid containing 1 or more types selected from the group which consists of trivalent chromium, surfactant, a silicon compound, and an olefin resin. And one or more anions selected from the group consisting of sulfate ion, chlorine ion, nitrate ion, chlorine oxyacid ion, phosphorus oxyacid ion, boron oxyacid ion and halogen ion; alkaline earth metal , One or more metal ions selected from the group consisting of titanium, zirconium, molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, tin and aluminum; and monocarboxylic acids, dicarboxylic acids, tricarboxylic acids One or more selected from the group consisting of acids, hydroxycarboxylic acids, ammonia, amines, aminocarboxylic acids and salts thereof Chelating agents; second treatment solution containing one or more kinds of more preferred.

  As a specific concentration range of the first treatment liquid, trivalent chromium is 0.01 g / L or more and 4.5 g / L or less, preferably 0.05 g / L or more and 3 g / L or less, particularly preferably 0.1 g / L. L to 1 g / L, and the total concentration of anions is 5 g / L to 120 g / L, preferably 10 g / L to 90 g / L, particularly preferably 15 g / L to 80 g / L. Is from 0.1 g / L to 85 g / L, preferably from 1.6 g / L to 70 g / L, particularly preferably from 3 g / L to 60 g / L. Is 0.005 g / L or more and less than 20 g / L, preferably 0.05 g / L or more and less than 10 g / L, particularly preferably 0.1 g / L or more and less than 3 g / L, and the total concentration of silicon compounds is 0 as silicon. .05g / Above 10 g / L or less, preferably 0.1 g / L or more 5 g / L or less, particularly preferably not more than 0.2 g / L or more 2 g / L. When the complexing agent is tartaric acid, citric acid, malic acid, lactic acid, succinic acid and salts thereof, the total concentration of these complexing agent ions is 0.05 g / L or more and less than 3 g / L, preferably 0. .1 g / L or more and less than 2.5 g / L, particularly preferably 0.3 g / L or more and less than 2 g / L. When oxalate ions and / or malonate ions are contained, the total concentration thereof is 0.1 g / L or more and 40 g / L or less, preferably 0.2 g / L or more and 30 g / L or less, particularly preferably 0.5 g / L. It is 25 g / L or less. The "complexing agent ion" means that when the complexing agent is tartaric acid, citric acid, malic acid, lactic acid, succinic acid, butyric acid, gluconic acid, glutamic acid, glycolic acid, diglycolic acid, or ascorbic acid. It refers to an acid ion, ammonia refers to an ammonium ion, and amine compounds refer to its cation.

  The concentration of the pretreatment liquid varies depending on the component, and trivalent chromium, metal ions (alkali metal, alkaline earth metal, titanium, zirconium, vanadium, molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, Tin, aluminum, etc.) and silicon compounds (sodium silicate, potassium silicate, lithium silicate, colloidal silica, etc.), each concentration is 0.01 g / L or more and 2 g / L or less (silicon compound is silicon) The surfactant is 0.05 g / L or more and 3 g / L or less, inorganic acid ion (sulfate ion, nitrate ion, chlorine ion, borate ion, etc.), organic acid ion (tartaric acid, citric acid, malic acid, lactic acid, candy Acid, butyric acid, gluconic acid, glutamic acid, ascorbic acid, glycolic acid, diglycolic acid, oxalic acid, malonic acid 0.5 g / L or more and 50 g / L or less in the case of any carboxylate ion), 0.5 g / L in the case of ammonium ion, amine compound (as its cation), or hydroxide (as hydroxide ion), respectively. L to 150 g / L.

  Further, the second treatment liquid to be further treated contains 0.01 to 5 g / L, preferably 0.1 to 2 g / L of trivalent chromium, a surfactant, and a silicon compound. Other components are also thin, and the concentration used in the first treatment liquid is generally 10% to 50%. On the other hand, the total concentration of phosphorus oxyacid ions is 0.01 g / L or more and 30 g / L or less, preferably 0.05 g / L or more and 20 g / L or less, and particularly preferably 0.1 g / L or more and 10 g / L or less. .

If any component is less than these ranges, the effect cannot be obtained. On the other hand, if it is excessive, the effect reaches a peak, and not only is the economic loss large, but in some cases, excessive film formation is not preferable because it causes a decrease in corrosion resistance and a deterioration in appearance.
If further added, one of the anions is preferably chlorine ion or oxyacid ion of chlorine, and among these and other anions, the combination of chlorine ion and nitrate ion is most preferable. The weight ratio of other anions to chlorine ions or chlorine oxyacid ions (the sum of both if included) is 1: 2 to 1: 200, preferably 1: 5 to 1: 100, particularly preferably 1: 10 to 1:60.

  In the first treatment liquid of the present invention, various compounds containing trivalent chromium can be used as a source of trivalent chromium. Specifically, in addition to salts such as chromium nitrate, chromium sulfate, chromium chloride, chromium phosphate, chromium acetate, etc., compounds obtained by reducing hexavalent chromium compounds such as chromic acid and dichromate to trivalent with a reducing agent are used. It is also possible to do. Anion sources such as nitrate ion, sulfate ion, chlorine ion, chlorine oxyacid ion, phosphorus oxyacid ion, boron oxyacid ion can also use their own acids and salts thereof. Supplying it as a metal salt of other components such as trivalent chromium or supplying it with its own acid, sodium salt or magnesium salt is industrially inexpensive and easily available. Conversely, metal ions are generally supplied as these salts. Among these anions, the most important anion is chloride ion and nitrate ion, which is effective in the stability of corrosion resistance. Addition of metal ions such as alkali metal, alkaline earth metal, titanium, zirconium, vanadium, molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, tin, and aluminum improves corrosion resistance and appearance. Among them, alkali metals, alkaline earth metals, titanium, vanadium, manganese, cobalt, nickel, and tin are useful with almost no side effects. These sources are not particularly limited, and various salts can be used as described above. In general, these nitrates, sulfates, chlorides, hydroxides or oxyacid salts are used. The complexing agents tartaric acid, citric acid, malic acid, lactic acid, succinic acid, butyric acid, gluconic acid, glutamic acid, glycolic acid, diglycolic acid, ascorbic acid, ammonia, and amine compounds are also supplied in the form of these or their salts. Is common. Among the complexing agents, tartaric acid, citric acid, malic acid, lactic acid, succinic acid, glycolic acid, and diglycolic acid are effective as complexing agents because they are effective at particularly low concentrations where the impact on wastewater treatment can be ignored. Yes. Oxalic acid and malonic acid are also supplied by themselves or as a salt. As the silicon compound, sodium silicate, potassium silicate, lithium silicate, or colloidal silica having a particle size of 200 nm or less, and more preferably 100 nm or less is preferable.

  The same supply source as the first treatment liquid can be used for the second treatment agent. In addition, as for the surfactant, an appropriate amount of various commercially available surfactants may be used, and it can be used for fine adjustment of the friction coefficient depending on the surfactant type and concentration. As the surfactant, various surfactants can be used, and cationic surfactants are particularly preferable, and aliphatic amine salts, quaternary ammonium salts, and EO-added quaternary ammonium salts are more preferable. Specifically, Farmin, Cotamine, Sanisole (above trade name, Kao Corporation), Duomin, Armac, Arcard, Esocard (above trade name, Lion Corporation), Cation (trade name, Nippon Oil & Fats Co., Ltd.) And Adecamin (trade name, Asahi Denka Co., Ltd.). For olefin resins, Frocene (trade name, Sumitomo Seika Co., Ltd.), PES (trade name, Nippon Unicar Co., Ltd.), Chemipearl (trade name; Mitsui Chemicals, Inc.), Sun Fine (trade name; Asahi Kasei) Co.)). In addition, one or more anions selected from the group consisting of sulfate ion, chlorine ion, chlorine oxyacid ion, nitrate ion, boron oxyacid ion, phosphorus oxyacid ion and halogen ion; alkaline earth metal, titanium , One or more metal ions selected from the group consisting of zirconium, molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, tin and aluminum; and monocarboxylic acids, dicarboxylic acids, tricarboxylic acids One or more chelating agents selected from the group consisting of carboxylic acid, hydroxycarboxylic acid, ammonia, amine, aminocarboxylic acid and their salts; Can be supplied simultaneously with the use of salts.

  For the pretreatment liquid, the supply source can be selected in the same way as described above.

  It is also possible to apply a commercially available overcoat agent to these films. There is no particular limitation on the overcoat agent, and there are overcoat agents containing resins such as acrylic resins, epoxy resins, olefin resins, phenol resins, alkyd resins, melamine resins, and silicates as components. Specifically, Cosmar Coat (trade name, Kansai Paint Co., Ltd.), Triner TR-170 (trade name, Nippon Surface Chemistry Co., Ltd.), Finigard (trade name, Coventya) and the like can be used.

  As a method of treating a zinc-based substrate using these treatment liquids, there is a method of bringing the substrate into contact with the treatment liquid once or a plurality of times. In the case of zinc plating, there are a cyan bath, an acid bath, and a zincate bath, and there are an acid bath and a zincate bath in zinc-alloy plating. Any of the baths can be used for plating, but a zincate bath, particularly preferably a zincate bath of a type excellent in throwing power is preferable (for example, Hyper Zincate (trade name): Nippon Surface Chemical Co., Ltd.). Apart from the effect on zinc plating, the application of the present invention is very clearly demonstrated in zinc alloy plating. In particular, the effect when applied to zinc-nickel alloy plating should be noted. Zinc-nickel alloy plating usually has a nickel eutectoid rate of about 4 to 16%. Among them, the nickel eutectoid rate is 4 to 12%, and if further limited, it is applied to zinc-nickel alloy plating of 5 to 10%. Is effective, and its application to zinc-nickel alloy plating with a low nickel eutectoid rate of less than 8%, particularly less than 7%, is unparalleled.

  Application to the zinc member, zinc alloy member, zinc-plated product or zinc alloy-plated product of the present invention is performed by subjecting the substrate to be treated to trivalent chromium, a surfactant, a silicon compound, an inorganic acid, an organic acid, ammonia, an amine compound, After contacting with the pre-processing liquid containing 1 type or more of the group which consists of a hydroxide and a metal ion, it is made to contact with a 1st processing liquid. Appropriate pretreatment conditions include a liquid temperature of 5 to 60 ° C., preferably 20 to 40 ° C., and an immersion time of 1 to 90 seconds, preferably 10 to 45 seconds. The conditions of the first treatment liquid are a liquid temperature of 10 to 70 ° C., preferably 15 to 60 ° C., particularly preferably 20 to 50 ° C., and an immersion time of 10 to 120 seconds, preferably 15 to 90 seconds, and more preferably. Is 20 to 60 seconds, and the pH is 0.5 to 6, preferably 1.0 to 4.5, and more preferably 2 to 4. The conditions of the second treatment liquid are such that the liquid temperature is 5 to 50 ° C., preferably 10 to 40 ° C., more preferably 15 to 35 ° C., and the immersion time is 1 to 60 seconds, preferably 5 to 45 seconds. Preferably, it is 10 to 35 seconds. In the case of trivalent chromium, the pH is 1 to 6, preferably 2 to 5. However, the surfactant and the silicon compound may have any of acidic, neutral and alkaline pH depending on the type. Further, when overcoating these coatings, a method of bringing the substrate into contact with the treatment liquid once or a plurality of times, preferably a method of immersing, is adopted in the same manner as described above, but under the appropriate conditions of each overcoat agent. There is a need. In any step, it is preferable to perform proper liquid agitation and rocking of the processed material.

  The present invention forms a hexavalent chromium-free film on a zinc-based member and exhibits a remarkable effect particularly in zinc-nickel alloy plating. According to the present invention, it is possible to obtain a coating having an excellent corrosion resistance that could not be obtained even when hexavalent chromium was used and a uniform and rich appearance that could not be obtained by conventional techniques while reducing the burden on the environment. It became possible.

  That is, the present invention combines a combination of a plurality of specific anions, a combination of a plurality of specific metal ions, and a specific complexing agent, while suppressing the burden on the environment that could not be achieved by the conventional technology, Since a low-temperature and short-time treatment is possible, it has become possible to provide a coating having an appearance that is rich in design, and a corrosion resistance superior to that of a coating using current hexavalent chromium.

  Specifically, since trivalent chromium has a low concentration, the amount of sludge generated during wastewater treatment is reduced, and loss due to liquid assembly can be suppressed. Further, since fluorine, boron, phosphoric acid and the like are not essential components, the corresponding emission control items can be reduced. In addition, it contains an organic acid, but it is unclear whether the amount is simply small or the complexing effect is weak. However, it is difficult to cause coagulation inhibition, so actual wastewater treatment is easy and practically wastewater treatment. There are many advantages such as no problem in the field and reduction of processing costs compared to the prior art containing them. In addition, it is excellent in stability over time, and there is no change in pH or change in appearance even after standing for 1 month, in order to maintain the performance equivalent to or higher than the coating treatment using hexavalent chromium which is the initial performance, It is possible to provide an extremely durable and practical treatment liquid that can save the trouble of renewing the liquid and can reduce the running cost by extending the life of the liquid. Furthermore, it is possible to obtain high heat and corrosion resistance that could not be obtained with conventional hexavalent chromium coatings.

  Up until now, the harmful effects of hexavalent chromium have been talked about, but it has been difficult to switch. Since many of the conventional problems have been solved by the present invention, it will be used in a wide range of fields in the future, and switching from hexavalent chromium will proceed.

  In the following, the present invention will be described with reference to examples mainly composed of zinc-nickel alloy plating with remarkable effects. In the test, the test piece is subjected to appropriate pretreatment such as degreasing and acid dipping, zinc plating (hyper zincate), zinc alloy plating (Stron Zinc; Nippon Surface Chemical Co., Ltd.), zinc nickel alloy plating (Stron Ni Zinc; Japan) After applying any of Surface Chemistry Co., Ltd., the treatment according to the present invention was performed. The thickness of the plating was 8-10 μm for any plating. The corrosion resistance was evaluated by a salt spray test according to JIS Z2731.

Example 1
The galvanized product is immersed in a room temperature aqueous solution of nitric acid 4 ml / L and hydrochloric acid 0.2 ml / L for 15 seconds and washed with water, then chromium sulfate 3 g / L, chromium nitrate 3 g / L, sodium nitrate 15 g / L, cobalt nitrate 3 g / L The treatment was performed by immersing in a treatment solution containing L, ammonium vanadate 2 g / L, nickel chloride 1 g / L, and citric acid 8 g / L. The liquid temperature was 35 ° C., the immersion time was 45 seconds, and the pH was 2.1 under mild stirring. After lightly washing with water, drying was performed at 60 to 80 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Example 2
Zinc-nickel alloy plated product (nickel eutectoid rate 5%), chromium chloride 0.5g / L, chromium nitrate 0.5g / L, potassium nitrate 2g / L, sodium chloride 40g / L, cobalt chloride 4g / L, vanadic acid The treatment was performed by dipping in a treatment solution containing 0.5 g / L of ammonium, 0.5 g / L of citric acid, 1 g / L of oxalic acid, and 8 g / L of potassium silicate. The liquid temperature was 35 ° C., the immersion time was 35 seconds, and the pH was 2.8. After lightly washing with water, drying was performed at 90 to 100 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Example 3
Zinc nickel alloy plating product (nickel eutectoid rate 6.5%), chromium chloride 0.5g / L, chromium nitrate 1g / L, potassium nitrate 2g / L, sodium chloride 45g / L, cobalt chloride 3g / L, vanadic acid The treatment was performed by dipping in a treatment solution containing 0.5 g / L of ammonium, 0.5 g / L of citric acid, 1 g / L of oxalic acid, and 8 g / L of potassium silicate. The liquid temperature was 30 ° C., the immersion time was 30 seconds, and the pH was 2.8. After lightly washing with water, drying was performed at 70 to 90 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Example 4
Zinc nickel alloy plated product (nickel eutectoid rate 7.8%), chromium chloride 1g / L, chromium nitrate 1g / L, magnesium nitrate 3g / L, nitric acid 0.5g / L, sodium chloride 35g / L, cobalt chloride The treatment was performed by immersion in a treatment solution containing 2 g / L, nickel chloride 3 g / L, citric acid 0.5 g / L, oxalic acid 1 g / L, and sodium silicate 10 g / L. The liquid temperature was 40 ° C., the immersion time was 30 seconds, and the pH was 2.9, under mild stirring. After lightly washing with water, drying was performed at 70 to 90 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Example 5
Zinc-nickel alloy plated product (nickel eutectoid rate 9%), chromium chloride 1g / L, chromium nitrate 1g / L, potassium nitrate 3g / L, nitric acid 0.5g / L, hydrochloric acid 3g / L, cobalt chloride 2g / L, The treatment was performed by immersion in a treatment solution containing 3 g / L of nickel chloride, 0.5 g / L of citric acid, 1 g / L of oxalic acid, and 4 g / L of colloidal silica. The liquid temperature was 40 ° C., the immersion time was 30 seconds, and the pH was 2.9, under mild stirring. After lightly washing with water, drying was performed at 70 to 90 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Example 6
A zinc-nickel alloy plated product (nickel eutectoid rate of 11%) is immersed in a room temperature aqueous solution of sodium hydroxide 5 g / L and sodium silicate 0.01 g / L for 10 seconds, washed with water, then chromium chloride 2 g / L, magnesium nitrate 10 g / L, sodium chloride 50 g / L, cobalt chloride 2 g / L, nickel nitrate 3 g / L, citric acid 1 g / L, oxalic acid 1 g / L, colloidal silica 8 g / L . The liquid temperature was 35 ° C., the immersion time was 50 seconds, and the pH was 2.7. After lightly washing with water, drying was performed at 70 to 90 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Example 7
Zinc-nickel alloy plated product (nickel eutectoid rate: 14%), chromium nitrate 1.5 g / L, potassium nitrate 2 g / L, sodium chloride 45 g / L, cobalt nitrate 3 g / L, ammonium vanadate 0.5 g / L, 琥珀The treatment was performed by immersion in a treatment solution containing 0.5 g / L of acid and 8 g / L of potassium silicate. The liquid temperature was 30 ° C., the immersion time was 30 seconds, and the pH was 2.8. After lightly washing with water, drying was performed at 70 to 90 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Examples 8-11
After performing the treatments of Examples 1, 3, 5, and 7 and washing with water, the samples were further immersed in an aqueous solution of pH 3.8 containing 0.5 g / L of trivalent chromium without drying, and then dried. In this order, Examples 8, 9, 10, and 11 were used.
A glossy and uniform appearance was obtained as in Examples 1, 3, 5, and 7.

Examples 12-14
After carrying out the treatment of Examples 2, 4, and 6 and washing with water, the samples were further immersed in a pH 9 aqueous solution containing 2 g / L of colloidal silica for 20 seconds without drying, and then each of the samples was dried in order. , 14.
Similar to Examples 2, 4, and 6, a glossy and uniform appearance was obtained.

Examples 15-18
After performing the treatment of Examples 1, 3, 5, and 7 and washing with water, without drying, the solution was further adjusted to pH 3.9 containing 2 g / L of potassium silicate, 1.5 g / L of chromium nitrate, and 1 g / L of cobalt nitrate. Each sample was dipped in an aqueous solution for 20 seconds and then dried, and Examples 15, 16, 17, and 18 were sequentially formed. A glossy and uniform appearance was obtained as in Examples 1, 3, 5, and 7.

Examples 19-24
The test pieces of Examples 2, 4, 6, 9, 13, and 18 were further immersed in Cosmer NC (trade name) at 23 ° C. for 20 seconds and then dried, and Examples 19, 20, 21, 22, 23, and 24 were respectively obtained. It was. A very glossy and uniform appearance was obtained.

Example 25
After immersing the zinc-iron alloy plated product in a room temperature aqueous solution of nitric acid 4 ml / L for 20 seconds, chromium sulfate 3 g / L, chromium nitrate 4 g / L, magnesium nitrate 20 g / L, sodium chloride 1 g / L, cobalt nitrate 6 g / L It was immersed in a treatment solution containing 3 g / L nickel nitrate, 5 g / L citric acid, 1.5 g / L malonic acid, and 8 g / L colloidal silica. The liquid temperature was 45 ° C., the immersion time was 50 seconds, and the pH was 2.2 under mild stirring. After lightly washing with water, drying was performed at 70 to 90 ° C. for 5 minutes. A glossy, thin interference color coating with good appearance was obtained.

Comparative Example 1
Zinc plating was treated with a commercially available colored chromating agent for zinc plating (Rohmate 62 (trade name); 5 ml / L; containing about 1 g / L of hexavalent chromium; Nippon Surface Chemical Co., Ltd.). The liquid temperature was 25 ° C., and the treatment time was 20 seconds under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. A glossy and strong interference color coating was obtained.

Comparative Example 2
Zinc-iron alloy plating was treated with a commercially available colored chromate agent for zinc-iron alloy plating (FC-950 (trade name); 30 ml / L; containing about 1 g / L of hexavalent chromium; Nippon Surface Chemical Co., Ltd.). The liquid temperature was 25 ° C., and the treatment time was 20 seconds under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. A glossy and strong interference color coating was obtained.

Comparative Example 3
Zinc-nickel alloy plating (nickel eutectoid) with commercially available colored chromate agent for zinc-nickel alloy plating (ZNC-980A (trade name); 35 ml / L; containing about 2 g / L of hexavalent chromium; Nippon Surface Chemical Co., Ltd.) Rate 6%). The liquid temperature was 30 ° C., and the treatment time was 40 seconds under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. A glossy and strong interference color coating was obtained.

Comparative Examples 4, 5, 6
Zinc plating (Comparative Example 4), zinc-nickel alloy plating (nickel co-treatment) containing chromium chloride hexahydrate 50 g / L, cobalt nitrate 3 g / L, sodium nitrate 100 g / L, malonic acid 31.2 g / L Analysis rate: 6%: Comparative example 5) was processed. The liquid temperature was 30 ° C., the immersion time was 40 seconds, and the pH was 2.2 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes.
In Comparative Example 4, a film having a weak interference color was obtained, but in Comparative Example 5, no film was formed. Although the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, the formation of zinc-nickel alloy plating was not performed (Comparative Example 6).

Comparative Examples 7, 8, 9
Trivalent chromium 2g / L, nitrate ion 0.4g / L, phosphate ion 12g / L, sulfate ion 2g / L, malonic acid 12g / L, cobalt 1g / L, nickel 0.5g / L, silicon 1g / L Zinc plating (Comparative Example 7) and zinc-nickel alloy plating (Nickel eutectoid rate of 6%: Comparative Example 8) were treated with the treatment solution contained. The liquid temperature was 30 ° C., the immersion time was 60 seconds, and the pH was 2.6 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. In Comparative Example 7, a blackish film exhibiting weak interference that was not good was obtained. Further, in Comparative Example 8, no film was formed, but when the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, a blackish film exhibiting weak interference such as a matte purple color which was not good was obtained ( Comparative Example 9).

Comparative Examples 10 and 11
Trivalent chromium 4.5g / L, nitrate ion 0.6g / L, phosphate ion 12g / L, sulfate ion 10g / L, oxalic acid 15g / L, oxalic acid 10g / L, cobalt 1g / L, nickel 0.3g / L, zinc-nickel alloy plating (nickel eutectoid rate of 6%) was treated with a treatment solution containing 1 g / L of silicon. The liquid temperature was 35 ° C., the immersion time was 60 seconds, and the pH was 2.6 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. No film was formed (Comparative Example 10). When the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, a blackish film exhibiting weak interference such as matte purple, which was not good, was obtained (Comparative Example 11).

Comparative Examples 12, 13, 14
A treatment solution containing trivalent chromium 1 g / L, nitrate ions 5 g / L, oxalic acid 3 g / L, cobalt 0.2 g / L, silicon 2 g / L, zinc plating (Comparative Example 12), zinc-nickel alloy plating ( Nickel eutectoid rate 6%: Comparative Example 13) was processed. The liquid temperature was 30 ° C., the dipping time was 60 seconds, and the pH was 2.0 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. In Comparative Example 12, a film exhibiting weak interference was obtained. In Comparative Example 13, the film was not formed, but when the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, a blackish film exhibiting weak interference such as a matte purple color which was not good was obtained (Comparative Example). 14).

Comparative Examples 15, 16, and 17
A treatment solution containing chromium nitrate 15 g / L, sodium nitrate 10 g / L, and oxalic acid dihydrate 10 g / L, zinc plating (Comparative Example 15), zinc-nickel alloy plating (nickel eutectoid rate 6%: Comparative Example 16) ) Was processed. The liquid temperature was 30 ° C., the immersion time was 40 seconds, and the pH was 2.0, with gentle stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. In Comparative Example 15, a light blue film was obtained. In Comparative Example 16, no film was formed. Although the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, the formation of zinc-nickel alloy plating was not performed (Comparative Example 17).

Comparative Examples 18, 19, and 20
A treatment solution containing chromium nitrate nonahydrate 45 g / L, 62.5% sulfuric acid 2 g / L, titanium sulfate 1 g / L, silica sol 50 g / L, zinc plating (Comparative Example 18), zinc-nickel alloy plating (nickel) The eutectoid rate was 6%: Comparative Example 19) was processed. The liquid temperature was 40 ° C., the dipping time was 60 seconds, and the pH was 2.0 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. In Comparative Example 18, a thin coating film having a weak interference color was obtained. In Comparative Example 19, no film was formed. Although the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, the formation of zinc-nickel alloy plating was not performed (Comparative Example 20).

Comparative Examples 21, 22, and 23
Chromium chloride (CrCl ₃ ) 8 g / L, Sodium silicate (Na ₂ SiO ₃ ) 10 g / L, Ammonium hydrogen fluoride (NH ₄ HF ₂ ) 5 g / L, Nitric acid (HNO ₃ ) 5 g / L, Sulfuric acid (H ₂ Zinc plating (Comparative Example 21) and zinc-nickel alloy plating (Nickel eutectoid rate 6%: Comparative Example 22) were treated with a treatment solution containing 5 g / L of SO ₄ . The liquid temperature was 25 ° C., the immersion time was 15 seconds, and the pH was 1.8 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. In Comparative Example 21, a light blue film was obtained. In Comparative Example 22, the film was not formed, but when the liquid temperature was changed to 60 ° C. and the treatment time was changed to 60 seconds, a blackish film exhibiting weak interference such as a matte purple color which was not good was obtained (Comparison) Example 23).

Comparative Example 24
Trivalent chromium 4.5 g / L, nitrate ion 0.4 g / L, phosphate ion 15 g / L, sulfate ion 2 g / L, oxalic acid 15 g / L, adipic acid 20 g / L, cobalt 1 g / L, silicon 1 g / L The zinc-iron alloy plating was treated with a treatment solution containing The liquid temperature was 40 ° C., the immersion time was 60 seconds, and the pH was 2.5 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. A blackish film was obtained which had a dull, weak interference which was not good.

Comparative Example 25
Trivalent chromium 4.5 g / L, nitrate ion 0.2 g / L, phosphate ion 12 g / L, sulfate ion 15 g / L, oxalic acid 15 g / L, nickel 0.1 g / L, cobalt 1 g / L, silicon 1 g / L Zinc-iron alloy plating was treated with a treatment solution containing L. The liquid temperature was 50 ° C., the immersion time was 60 seconds, and the pH was 2.3 under mild stirring. After lightly washing with water, drying was performed at 80 to 100 ° C. for 10 minutes. A blackish film was obtained which had a dull, weak interference which was not good.

  In Comparative Examples, only Comparative Examples 3, 9, 11, 14, and 23 were formed into zinc-nickel alloy plating.

[Evaluation other than appearance]
In Comparative Examples 5, 6, 8, 10, 13, 16, 17, 19, 20, and 22, no film formation was observed, so the following evaluation was not performed.

[General corrosion resistance (salt spray test)]
The corrosion resistance of the test pieces of Examples 1, 3, 5, 7, 9, 11, 12, 14, 16, 18, 20, 22, 24, 25 and the comparative sample formed as a film was evaluated by a salt spray test.

  It took 240 hours or more for all the test pieces of the examples to generate 5% or more of white rust with respect to the test piece area. In particular, Examples 7, 14, and 18 required 500 hours or more, and Examples 20, 22, and 24 required 700 hours or more.

  Among Comparative Examples, Comparative Examples 1, 2, 3, 4, and 12 required 240 hours or more to generate 5% or more of white rust. Otherwise, Comparative Examples 9, 11, 14, 23, 24, and 25 were 72 hours, Comparative Examples 7 and 15 were 96 hours, and Comparative Example 18 was 144 hours. None of the prior arts that did not use hexavalent chromium required over 300 hours to generate white rust of 5% or more. Moreover, even if the technology using hexavalent chromium was included, there was no technology that required 500 hours or more to generate 5% or more of white rust.

[Heat corrosion resistance]
As in general corrosion resistance, Examples 1, 3, 5, 7, 9, 11, 12, 14, 16, 18, 20, 22, 24, 25 and Comparative Examples 1 and 2, which required 240 hours or more in the general corrosion resistance test, The test pieces of 3, 4, 12 and Comparative Example 18 were heated at 200 ° C. for 2 hours, and then subjected to a salt spray test to obtain a heat corrosion resistance test. It took 120 hours or more for white rust to occur 5% or more in all the test pieces of the examples. In particular, in Examples 3, 5, 7, 9, 11, 12, 14, 16, 18, 20, 22, and 24, no clear performance degradation due to heating was observed.

  Among the comparative examples, the test specimens that required 120 hours or more to generate 5% of white rust were Comparative Examples 3, 4, and 12. In Comparative Examples 1 and 2 using hexavalent chromium, the time was reduced to about 1/5 to 1/10 as compared with that without heating. Comparative Example 18 also decreased to 48 hours.

[Stability]
The treatment agents of Examples 2, 4, and 6, the second treatment liquids of Examples 8 to 11, 12 to 14, and 15 to 18 and the treatment liquids of Comparative Examples were allowed to stand at room temperature for one month. The treatment appearance was evaluated with a test piece of the same plating type as the above-described example after the period, pH, liquid appearance, and after the period. Corrosion resistance was also confirmed if necessary.

  All examples showed no change in pH or change in liquid appearance during the period. Further, in the treatment test after the end of the period, the appearance was as good as before leaving, and the stability was good.

  Among the comparative examples, it was Comparative Examples 1 to 3, 21 and 23 that did not show any problems in the treatment test after the pH, liquid appearance, and period. In Comparative Examples 4, 7, 9, 11, 12, 14, 15, 24, and 25, the pH dropped significantly within a few days, precipitation occurred, and some of the processing appearances became uneven and thin, Corrosion resistance was less than 48 hours until white rust generation of 5% or more occurred. In Comparative Example 18, no pH change was observed, but precipitation occurred on the next day. The treated appearance was dull and the corrosion resistance was less than 48 hours until white rust generation of 5% or more occurred. It was only Comparative Examples 21 and 23 that the corrosion resistance is low (the white rust is not less than 72 hours until the occurrence of 5% or more of the white rust) in the conventional technology that does not use hexavalent chromium.

[Wastewater treatment]
The wastewater treatability was evaluated for the treatment agents of Examples 2, 4, and 6, the second treatment liquids of Examples 8 to 11, 12 to 14, and 15 to 18 and all comparative examples. Since the treatment solution was dissolved in zinc by use, the wastewater treatment property of each solution obtained by dissolving 10 g / L of zinc powder was evaluated as a pseudo running solution.
The evaluation procedure is shown below.
1. Collect 10 ml of the evaluation target liquid and dilute it 100 times with water to make 1 L.
2. Make three of the above solutions.
3. Adjust the three liquids to pH 9, 10 and 11 respectively with sodium hydroxide.
4). Add an appropriate amount of polymer flocculant and stir well.
5. After standing for 15 minutes, the supernatant is analyzed with an atomic absorption spectrometer to measure the concentration of zinc and chromium.
6). Since Comparative Examples 1 to 3 contain hexavalent chromium, the above operation was performed after reducing hexavalent chromium to trivalent chromium with sodium bisulfite in advance.

  All the examples cleared the emission standards (zinc 5 mg / L, total chromium 2 mg / L) according to Article 3 of the Water Pollution Control Law.

  Among Comparative Examples, Comparative Examples 1 to 3, 18, 21, and 23 cleared the standard. The remaining Comparative Examples 4-17, 24, and 25 showed values 5 to 15 times the reference. Moreover, although the comparative examples 21 and 23 cleared the reference | standard, since it has the problem of eroding the glass electrode used for pH adjustment with the fluorine contained in a component, among the prior art which does not use hexavalent chromium, it is a wastewater treatment. Only Comparative Example 18 did not recognize the problem.

Claims (16)

  (A) trivalent chromium; (B) two or more kinds of anions selected from the group consisting of sulfate ion, nitrate ion, chlorine ion, chlorine oxyacid ion and boron oxyacid ion; and (C) alkali metal Three or more metal ions selected from the group consisting of alkaline earth metals, titanium, zirconium, vanadium, molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, tin and aluminum; ) One or more selected from the group consisting of tartaric acid, citric acid, malic acid, lactic acid, succinic acid, butyric acid, gluconic acid, glutamic acid, glycolic acid, diglycolic acid, ascorbic acid, ammonia, amine compounds and salts thereof Forming a hexavalent chromium-free chemical conversion film on a zinc member, zinc alloy member, zinc-plated product or zinc alloy-plated product containing a complexing agent Processing solution of pH0.5~6 of the eye.   Furthermore, the processing liquid of Claim 1 which contains any 1 or more types of a silicon compound, an oxalate ion, and a malonate ion.   The anion contains chlorine ions or chlorine oxyacid ions or both, and the weight ratio of the other anions to chlorine ions or chlorine oxyacid ions (the sum of both if both are included) is from 1: 2 to 1: The treatment liquid according to claim 1, which is 200.   Trivalent chromium is 0.01 g / L or more and 4.5 g / L or less, and / or the total concentration of anions is 5 g / L or more and 120 g / L or less, and / or the total concentration of metal ions is 0.1 g / L or more and 85 g. The processing liquid according to claim 1, wherein the total concentration of ions of / L or less and / or the complexing agent is 0.005 g / L or more and less than 20 g / L.   Contains a silicon compound having a total concentration of 0.05 g / L to 10 g / L as silicon, and one or more oxalate ions and / or malonate ions having a total concentration of 0.1 g / L to 40 g / L The processing liquid according to any one of claims 1 to 4.   The complexing agent is at least one selected from the group consisting of tartaric acid, citric acid, malic acid, lactic acid, succinic acid, glycolic acid, diglycolic acid and salts thereof, and the total concentration of ions of the complexing agent is 0 The treatment liquid according to any one of claims 1 to 4, which is 0.05 g / L or more and less than 3 g / L.   The treatment liquid according to any one of claims 1 to 6, wherein the metal ions are at least three selected from the group consisting of alkali metals, alkaline earth metals, titanium, vanadium, manganese, cobalt, nickel, and tin.   It is a chemical | medical agent for processing before processing with the processing liquid as described in any one of Claims 1-7, Trivalent chromium, surfactant, silicon compound, inorganic acid ion, organic acid ion, ammonium ion A pretreatment liquid comprising at least one selected from the group consisting of amine compounds, hydroxides and metal ions.   A chemical for further treatment after treatment with the treatment liquid according to any one of claims 1 to 7, selected from the group consisting of trivalent chromium, a surfactant, a silicon compound, and an olefin resin. Second treatment liquid containing one or more types.   Further, one or more anions selected from the group consisting of sulfate ion, chlorine ion, nitrate ion, chlorine oxyacid ion, phosphorus oxyacid ion and boron oxyacid ion; alkaline earth metal, titanium, zirconium, vanadium One or more metal ions selected from the group consisting of molybdenum, tungsten, manganese, iron, cobalt, nickel, gold, silver, copper, tin and aluminum; and monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, hydroxycarboxylic acids The second treatment liquid according to claim 9, comprising one or more chelating agents selected from the group consisting of ammonia, amines, aminocarboxylic acids, and salts thereof.   The treatment liquid according to any one of claims 1 to 10, wherein the target substrate is zinc-nickel alloy plating having a nickel eutectoid rate of 4 to 12%.   A hexavalent chromium-free coating film characterized by bringing a zinc member, a zinc alloy member, a zinc-plated product, or a zinc alloy-plated product into contact with the treatment solution according to any one of claims 1 to 7 once or a plurality of times. Forming method.   After making a zinc member, a zinc alloy member, a zinc plating product, or a zinc alloy plating product contact the pre-processing liquid of Claim 8 once or several times, the process as described in any one of Claims 1-7. A method for forming a hexavalent chromium-free coating, characterized by contacting with a solution.   After the hexavalent chromium-free film is formed by the method according to claim 12 or 13, the film is further brought into contact with the second treating agent solution according to claim 9 or 10 once or a plurality of times. A method for forming a hexavalent chromium-free coating.   The processing method which further overcoats on the hexavalent chromium free film formed by the method as described in any one of Claim 12, 13, or 14.   A zinc member, a zinc alloy member, a zinc-plated product, or a zinc alloy-plated product having a hexavalent chromium-free film formed by the method according to any one of claims 12 to 15.