METAL COLORING SOLUTION FOR CHEMICAL CONVERSION TREATMENT AND METHOD FOR COLORING METAL

Abstract

Provided is a metal coloring solution for chemical conversion treatment and a method for coloring a metal, which can color a metal surface into a yellowish to brownish color tone with good treatment efficiency. The metal coloring solution for chemical conversion treatment contains: permanganic acid or a salt thereof; one or both of an inorganic acid and a salt thereof; and a condensed phosphate.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a metal coloring solution for chemical conversion treatment and a method for coloring a metal.

BACKGROUND OF THE INVENTION

[0002] Conventionally, in coloring of various metals, in particular aluminum or an aluminum alloy, it is known to adsorb a dye onto an anodized coating or an anodic oxidation coating in order to obtain a yellowish to brownish color tone.

[0003] For example, Patent Literature 1 discloses a method for electrolytically coloring aluminum and an aluminum alloy, comprising forming a coating structure capable of electrolytic coloring, from a colored coating formed on a base surface of aluminum or the aluminum alloy due to electrolytic coloring or spontaneous coloring; and then carrying out electrolytic coloring to superimpose the colors to obtain a coating having a new color tone. It also discloses that according to such a structure, it is possible to provide an electrolytic coloring method that can obtain various color tones including various intermediate colors, which would not otherwise be obtained by the conventional electrolytic coloring method.

CITATION LIST

Patent Literatures

[0004] [Patent Literature 1] Japanese Patent Application Publication No. S60-110895 A

[0005] [Patent Literature 2] Japanese Patent No. 6004217 B

SUMMARY OF THE INVENTION

[0006] However, conventionally, in order to color the metal surface into a yellowish to brownish color tone, it is necessary to use alumite, for example, if the metal to be colored is aluminum or an aluminum alloy. That is, in order to color the metal surface into a yellowish to brownish color tone it is necessary to use a metal having an oxide film on the surface, so that there are many treatment steps. Therefore, there is a need for improvement of treatment efficiency.

[0007] Further, Patent Literature 2 discloses a treatment agent for coloring a surface of aluminum or an aluminum alloy into gold color. However, there are still room for further research and development in order to color a metal surface into a yellowish to brownish color tone by a chemical conversion treatment.

[0008] In view of such problems, an object of the present invention is to provide a metal coloring solution for chemical conversion treatment and a method for coloring a metal, which can color a metal surface into a yellowish to brownish color tone with good treatment efficiency.

[0009] As a result of intensive studies to solve the above problems, the present inventors have found that a metal surface can be colored into a yellowish to brownish color tone with good treatment efficiency by carrying out a treatment with a metal coloring solution for chemical conversion treatment containing permanganic acid or a salt thereof, and one or both of an inorganic acid and a salt thereof, and a condensed phosphate.

[0010] In an aspect, the present invention completed on the basis of the above findings relates to a metal coloring solution for chemical conversion treatment, comprising: permanganic acid or a salt thereof; one or both of an inorganic acid and a salt thereof; and a condensed phosphate.

[0011] In an embodiment of the metal coloring solution for chemical conversion treatment according to the present invention, the permanganic acid or the salt thereof is permanganic acid, sodium permanganate, potassium permanganate, zinc permanganate, magnesium permanganate, calcium permanganate, ammonium permanganate, or a combination thereof.

[0012] In another embodiment of the metal coloring solution for chemical conversion treatment according to the present invention, the inorganic acid and the salt thereof are phosphoric acid, sulfuric acid, nitric acid, carbonic acid, hydrochloric acid, and salts thereof, or combinations thereof.

[0013] In yet another embodiment of the metal coloring for chemical conversion treatment according to the present invention, the condensed phosphate is potassium pyrophosphate, sodium tripolyphosphate, or a combination thereof.

[0014] In still another embodiment, the metal coloring solution for chemical conversion treatment according to the present invention contains 0.5 to 50 g/L of the permanganic acid or the salt thereof.

[0015] In still another embodiment, the metal coloring solution for chemical conversion treatment according to the present invention contains 0.5 to 100 g/L of the inorganic acid and the salt thereof.

[0016] In still another embodiment, the metal coloring solution for chemical conversion treatment according to the present invention contains 1 to 150 g/L of the condensed phosphate.

[0017] In yet another embodiment, the metal coloring solution for chemical conversion treatment according to the present invention further comprises an oxo acid or a salt thereof.

[0018] In still another embodiment of the metal coloring solution for chemical conversion treatment according to the present invention, the oxo acid or the salt thereof is perchloric acid, chloric acid, chlorous acid, hypochlorous acid, bromic acid, boric acid, or a salt thereof, or a combination thereof.

[0019] In still another embodiment, the metal coloring solution for chemical conversion treatment according to the present invention contains 0.5 to 100 g/L of the oxo acid or the salt thereof.

[0020] In yet another embodiment of the metal coloring solution for chemical conversion according to the present invention, the metal to be treated is at least one selected from the group consisting of aluminum, aluminum alloys, copper, copper alloys, iron, iron alloys, zinc, zinc alloys, magnesium, and magnesium alloys.

[0021] In another aspect, the present invention relates to a method for coloring a metal, comprising a step of coloring the metal by a chemical conversion treatment using the metal coloring solution for chemical conversion treatment according to the present invention.

[0022] In one embodiment of the method for coloring the metal according to the present invention, the step of coloring the metal by the chemical conversion treatment comprises immersing the metal in the metal coloring solution for chemical conversion treatment at a temperature of 10.degree. C. to 80.degree. C. for 30 seconds to 20 minutes to color the metal.

[0023] According to the present invention, it is to provide a metal coloring solution for chemical conversion treatment and a method for coloring a metal, which can color a metal surface into a yellowish to brownish color tone with good treatment efficiency.

DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, embodiments of a metal coloring solution for chemical conversion treatment and a method for coloring a metal according to the present invention will be described. However, the present invention is not limited to the embodiments, and various changes, modifications, and improvements may be added without departing from the scope of the present invention, based on knowledge of those skilled in the art.

Metal Coloring Solution for Chemical Conversion Treatment

[0025] A metal coloring solution for chemical conversion treatment according to an embodiment of the present invention contains permanganic acid or a salt thereof, and one or both of an inorganic acid and a salt thereof, and a condensed phosphate. By using the metal coloring solution for chemical conversion treatment containing permanganic acid or the salt thereof, and one or both of the inorganic acid and the salt thereof, and the condensed phosphate, a coating (colored coating) can be formed on the metal surface simply by immersing a metal to be treated in metal coloring solution for chemical conversion treatment, whereby the metal surface can be colored into a yellowish to brownish color tone. Therefore, when the metal surface is colored into the yellowish to brownish color tone, there is no need to form an oxide film on the surface of the metal, and there is no need to color the metal by electrolysis, and an improved treatment efficiency can be achieved. Further, according to the metal coloring solution for chemical conversion treatment according to an embodiment of the present invention, adhesion of the coating (colored coating) formed on the metal surface is also improved.

Metal To Be Treated

[0026] A metal whose surface is to be colored with the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention (a metal to be treated) includes at least one selected from the group consisting of aluminum, aluminum alloys, copper, copper alloys, iron, iron alloys, zinc, zinc alloys, magnesium, and magnesium alloys. The metal to be treated may be the metal itself, or for example, a plating of the metal formed on a surface of a metal substrate such as an iron-based material or an iron-based component.

Permanganic Acid or Salt Thereof

[0027] Examples of permanganic acid or the salt thereof that can be used include permanganic acid, sodium permanganate, potassium permanganate, zinc permanganate, magnesium permanganate, calcium permanganate, ammonium permanganate, or a combination thereof. Further, as the permanganic acid or the salt thereof, sodium permanganate and potassium permanganate are more preferable.

[0028] The content of permanganic acid or the salt thereof in the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention can be, for example, from 0.5 to 50 g/L, although it depends on types of metals to be treated and a degree of a yellowish to brownish color tone. Basically, a lower content of the permanganic acid or the salt thereof can allow the metal surface to be colored into a lighter yellowish to darker yellowish color tone. Further, a higher content of the permanganic acid or the salt thereof can allow the metal surface to be colored into a lighter brownish to darker brownish color tone. The content of permanganic acid or the salt thereof is more preferably from 1 to 30 g/L, and more preferably from 2 to 20 g/L.

[0029] As will be described later, the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention may contain an oxo acid or a salt thereof. However, for a metal coloring solution for chemical conversion treatment that does not contain these components, the surface of the metal such as aluminum or an aluminum alloy can be colored into a yellowish to brownish color tone that can provide further improved aesthetic appearance.

Inorganic Acid and Salt Thereof

[0030] The inorganic acid and the salt thereof in the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention are preferably phosphoric acid, sulfuric acid, nitric acid, carbonic acid, hydrochloric acid, and salts thereof, or combinations thereof. The salts of phosphoric acid, sulfuric acid, nitric acid, carbonic acid, and hydrochloric acid that can be used include metal salts or ammonium salts of those acids. Further, as the inorganic acid and the salt thereof, trisodium phosphate, nitric acid, copper nitrate and zinc chloride are more preferable.

[0031] The content of the inorganic acid and the salt thereof in the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention can be, for example, from 0.5 to 100 g/L, although it depends on types of metals to be treated and a coloring degree of a yellowish to brownish color tone. Basically, a lower content of the inorganic acid and the salt thereof can allow the metal surface to be colored into a lighter yellowish to darker yellowish color tone. Further, a higher content of the inorganic acid and the salt thereof can allow the metal surface to be colored into a lighter brownish to darker brownish color tone. The content of the inorganic acid and the salt thereof is more preferably from 1 to 30 g/L, and more preferably 2 to 20 g/L.

Condensed Phosphate

[0032] The condensed phosphate is preferably potassium pyrophosphate, sodium tripolyphosphate, or a combination thereof. The content of the condensed phosphate can be, for example, from 1 to 150 g/L, although it depends on types of metals to be treated and a coloring degree of a yellowish to brownish color tone. Basically, a lower content of the condensed phosphate can the metal surface to be colored into a lighter yellowish to darker yellowish color tone. Further, a higher content of the condensed phosphate can allow the metal surface to be colored into a lighter brownish to darker brownish color tone. The content of the condensed phosphate is more preferably from 3 to 50 g/L, and more preferably from 4 to 40 g/L.

Oxo Acid or Salt Thereof

[0033] The metal coloring solution for chemical conversion treatment according to the embodiment of the present invention may further contain an oxo acid or a salt thereof. Even if the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention contains the oxo acid or salt thereof, the surface of the above metal to be treated can be colored into a yellowish to brownish color tone with good treatment efficiency. Further, the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention contains the oxo acid or the salt thereof, so that the surface of metal such as copper, copper alloys, iron, iron alloys, zinc, and zinc alloys can be colored into a yellowish to brownish color tone that can provide more improved aesthetic appearance.

[0034] The oxo acid or the salt thereof may preferably be perchloric acid, chloric acid, chlorous acid, hypochlorous acid, bromic acid, boric acid, or salts thereof, or combinations thereof. The salts of perchloric acid, chloric acid, chlorous acid, hypochlorous acid, bromic acid, and boric acid that can be used include metal salts or ammonium salts of those acids.

[0035] The total content of the oxo acid or salt thereof in the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention can be from 0.5 to 100 g/L. Basically, as the total content of the oxo acid or the salt thereof is lower, the surface of the metal can be colored into a lighter yellowish to darker yellowish color tone. Further, as the total content of the oxo acid or the salt thereof is higher, the surface of the metal can be colored into a lighter brownish to darker brownish color tone. The total content of the oxo acid or the salt thereof is more preferably from 1 to 50 g/L, and even more preferably from 10 to 30 g/L.

Aqueous Medium

[0036] The metal coloring solution for chemical conversion treatment according to the embodiment of the present invention may be a mixture of the various components as described above and an aqueous medium. The aqueous medium refers to a medium containing water as a main component. Examples of the aqueous medium include a medium containing water as a main component and an organic solvent such as an alcohol miscible with water. During the preparation of the metal coloring solution for chemical conversion treatment according to an embodiment of the present invention, during storage of the metal coloring solution for chemical conversion treatment, or after coloring of the surface of the metal, the aqueous medium may optionally contain various components that advantageously act to improve any property of the colored surface of the metal, or various components that do not substantially inhibit the effects of the present invention. Specific examples of these components include pH adjusting agents, storage stabilizers and the like.

Method for Coloring Metal

[0037] Next, a method for coloring a metal according to an embodiment of the present invention will be described in detail. First, a bath is prepared that contains the metal coloring solution for chemical conversion treatment according to the embodiment of the present invention. The metal to be treated is then immersed in the metal coloring solution for chemical conversion treatment while controlling a temperature of the metal coloring solution for chemical conversion treatment in the bath. After a certain period of time, the metal to be treated is pulled up from the bath to obtain a metal having a surface colored into a yellowish to brownish color tone. Thus, according to the method for coloring the metal according to the embodiment of the present invention, only immersion of the metal to be treated in the metal coloring solution for chemical conversion treatment can allow the surface of the metal to be colored into the yellowish to brownish color tone. Therefore, when coloring the surface of the metal, it is not necessary to form an oxide film on the surface of the metal, and it is not necessary to perform coloring by electrolysis, thereby improving the treatment efficiency.

[0038] Further, in the method for coloring the metal according to the embodiment of the present invention, the surface of the metal to be treated may be colored, for example by bringing the metal coloring solution for chemical conversion treatment into contact with the surface of the metal, for example in a spraying step of the metal coloring solution for chemical conversion treatment, in addition to the immersion of the metal to be treated in the metal coloring solution for chemical conversion treatment.

[0039] A treatment temperature with the metal coloring solution for chemical conversion treatment is preferably in a range of from 10 to 80.degree. C., and more preferably in a range of from 10 to 60.degree. C., and even more preferably in a range of from 30 to 60.degree. C. When the treatment temperature is 10.degree. C. or more, a reaction velocity of the surface treatment increases, and when the treatment temperature is 80.degree. C. or less, a decrease in a liquid level of the metal coloring solution for chemical conversion treatment due to evaporation can be suppressed.

[0040] A treatment time with the metal coloring solution for chemical conversion treatment is preferably in a range of from 30 seconds to 20 minutes, and more preferably in a range of from 1 minute to 20 minutes, and even more preferably in a range of from 1 minute to 10 minutes. Basically, as the treatment time is shorter, the surface of the metal can be colored into a lighter yellowish to darker yellowish color tone. Further, as the treatment time is longer, the surface of the metal can be colored into a lighter brownish to darker brownish color tone.

[0041] When carrying out the metal surface treatment, the metal to be treated can be previously degreased, activated, or surface-adjusted to improve the appearance, corrosion resistance of the metal to be treated and reactivity of the metal to be treated with the metal coloring solution for chemical conversion treatment.

[0042] After the metal surface treatment, a post-treatment may be carried out with coating agents containing one or more selected from the group consisting of silicon, a resin and a wax. These coating agents are not particularly limited as long as they do not affect the desired color tone on the surface of the metal, and include coating agents containing resins such as acrylic resins, olefin resins, alkyd resins, urea resins, epoxy resins, melamine resins, fluororesins, polyethylene, polyvinyl chloride, polystyrene, polypropylene, methacrylic resins, phenolic resins, polyester resins, polyurethane, polyamide, and polycarbonate, and silicates, colloidal silica or the like. The concentration of those resins is preferably from 0.01 to 800 g/L, although the appropriate concentration varies depending on the type of resins. Specific examples of the coating agents include Cosmer Coat (trade name; from Kansai Paint Co., Ltd.); High Seal 272 (trade name; from NIPPON HYOMEN KAGAKU KABUSHIKI KAISHA); Stron JS Coat (trade name; NIPPON HYOMEN KAGAKU KABUSHIKI KAISHA); Triner TR-170 (trade name; NIPPON HYOMEN KAGAKU KABUSHIKI KAISHA); Finigard (trade name; from Coventya) and the like. Specific examples of acrylic resins include Hirotite (trade name; Hitachi Chemical Co., Ltd.) and Alloset (trade name; Nippon Shokubai Co., Ltd.). Specific examples of the olefin resins include FLO-THENE (trade name; SUMITOMO SEIKA CHEMICALS CO., LTD.); PES (trade name; Nippon Unicar Co., Ltd.); CHEMIPEARL (trade name; Mitsui Chemicals, Inc.); and SUNFINE (trade name; Asahi Kasei Corporation) and the like.

[0043] The metal coloring solution for chemical conversion treatment according to the embodiment of the present invention can be used for the purpose of coloring the metal surface into a desired color, imparting a desired aesthetic appearance, or imparting distinctiveness, or the like. As a form of the metal to be treated, any form can be used, and there is no particular limitation. For example, decorative articles, fastening members such as buttons and fasteners, parts for vehicles, and the like can be used. The shape of the metal to be treated is not limited, and any shape can be used.

EXAMPLES

[0044] Hereinafter, while Examples of the present invention will be described, these Examples are provided for better understanding of the present invention, and are not intended to limit the present invention.

Test Example 1: Coloring Test for Aluminum and Aluminum Alloy

Examples 1 to 83, 90, 91

[0045] JIS A5052 (aluminum-magnesium alloy), A2017 (aluminum-copper alloy) and ADC12 (aluminum die-cast) were prepared as specimens (metal pieces to be treated), and the surfaces of the specimens were degreased and washed with water in this order.

[0046] A bath containing each metal coloring solution for chemical conversion treatment having each solution composition as shown in Tables 1 to 6 and 8 were prepared. Pure water was used as an aqueous medium of the metal coloring solution for chemical conversion treatment.

[0047] Subsequently, each specimen was immersed in the metal coloring solution for chemical conversion treatment while controlling the metal coloring solution for chemical conversion treatment in the bath at each temperature as shown in Tables 1 to 6 and 8. After immersion for each time as shown in Tables 1 to 6 and 8, each specimen was taken out. The surface of each specimen was washed with water and then dried.

[0048] In Examples 90 and 91, each specimen after forming a coating (a colored coating) by immersion were washed with water, subjected to a coating treatment, and dried. For the coating treatment in Example 90, Stron JS Coat (a coating agent from NIPPON HYOMEN KAGAKU KABUSHIKI KAISHA) was used, and for the coating treatment in Example 91, TR-170 (a coating agent from NIPPON HYOMEN KAGAKU KABUSHIKI KAISHA) was used.

Test Example 2: Coloring Test for Copper and Copper Alloy

Examples 84 to 85

[0049] JIS C2600P (brass) and C1100P (pure copper) were prepared as specimens (metal pieces to be treated), and the surfaces of the specimens were degreased and washed with water in this order.

[0050] A bath containing each metal coloring solution for chemical conversion treatment having each solution composition as shown in Table 7 was prepared. Pure water was used as an aqueous medium of the metal coloring solution for chemical conversion treatment.

[0051] Subsequently, each specimen was immersed in the metal coloring solution for chemical conversion treatment while controlling the metal coloring solution for chemical conversion treatment in the bath at each temperature as shown in Table 7. After immersion for each time as shown in Table 7, each specimen was taken out. Subsequently, the surface of each specimen was washed with water and then dried.

Test Example 3: Coloring Test for Zinc and Zinc Alloy

Examples 86 to 87

[0052] JIS ZDC2 (zinc die-cast) and a zinc plating material were prepared as specimens (metal pieces to be treated), and the surfaces of the specimens were degreased and washed with water in this order. The zinc plating material was obtained by forming a zincate zinc plating having a thickness of 8 .mu.m onto a base material of JIS SPCC (rolled steel sheet) as defined in the JIS standard. Further, 9000 ABS from NIPPON HYOMEN KAGAKU KABUSHIKI KAISHA was used as a brightener for the zincate zinc plating.

[0053] A bath was then prepared that contained each metal coloring solution for chemical conversion treatment having each solution composition as shown in Table 7. Pure water was used as an aqueous medium of the metal coloring solution for chemical conversion treatment.

[0054] Subsequently, each specimen was immersed in the metal coloring solution for chemical conversion treatment while controlling the metal coloring solution for chemical conversion treatment in the bath at each temperature as shown in Table 7. After immersion for each time as shown in Table 7, each specimen was taken out. Subsequently, the surface of each specimen was washed with water and then dried.

Test Example 4: Coloring Test for Iron and Iron Alloy

Example 88

[0055] JIS SPCC (rolled steel sheet) was prepared as a specimen (a metal piece to be treated), and the surface of the specimen was sequentially degreased and washed with water.

[0056] A bath was then prepared that contained each metal coloring solution for chemical conversion treatment having each solution composition as shown in Table 7. Pure water was used as an aqueous medium of the metal coloring solution for chemical conversion treatment.

[0057] Subsequently, each specimen was immersed in the metal coloring solution for chemical conversion treatment while controlling the metal coloring solution for chemical conversion treatment in the bath at each temperature as shown in Table 7. After immersion for each time as shown in Table 7, each specimen was taken out. Subsequently, the surface of each specimen was washed with water and then dried.

Test Example 5: Coloring Test for Magnesium and Magnesium Alloy

Example 89

[0058] JIS AZ31 (magnesium-zinc alloy) was prepared as a specimen (metal pieces to be treated), and the surface of the specimen was degreased and then washed with water.

[0059] Subsequently, a bath was prepared that contained a metal coloring solution for chemical conversion treatment having a solution composition as shown in Table 7. Pure water was used as an aqueous medium of the metal coloring solution for chemical conversion treatment.

[0060] Subsequently, the specimen was immersed in the metal coloring solution for chemical conversion treatment while controlling the metal coloring solution for chemical conversion treatment in the bath at the temperature as shown in Table 7. After immersion for the time shown in Table 7, the specimen was taken out. Subsequently, the surface of the specimen was washed with water and then dried.

Test Example 6

Comparative Examples 1 to 4

[0061] Metals as shown in Table 9 were prepared as specimens (metal pieces to be treated), and the surfaces of the specimens were sequentially degreased and washed with water.

[0062] A bath was then prepared that contained each metal coloring solution for chemical conversion treatment having each composition as shown in Table 9. Pure water was used as an aqueous medium of the metal coloring solution for chemical conversion treatment.

[0063] Next, each specimen was immersed in the metal coloring solution for chemical conversion treatment while controlling the temperature of the metal coloring solution for chemical conversion treatment in the bath at each temperature as shown in Table 9. After immersion for each time as shown in Table 9, each specimen was taken out. Subsequently, the surface of each specimen was washed with water and then dried.

Various Evaluations

[0064] The specimens prepared in Examples 1 to 91 and Comparative Examples 1 to 4 were evaluated for a color tone and adhesion, as follows:

Color Tone Evaluation

[0065] The color tone of the surface of each specimen was visually evaluated. The evaluation criteria are shown below:

[0066] A: Yellow having uniform and excellent treated appearance;

[0067] B: Yellow darker than A, which has a uniform and excellent treated appearance;

[0068] C: Yellow lighter than A, which has a uniform and excellent treated appearance;

[0069] D: Brown having uniform and excellent treated appearance;

[0070] E: Brown darker than A, which has a uniform and excellent treated appearance;

[0071] F: Brown lighter than A, which has a uniform and excellent treated appearance

[0072] G: Not colored.

Evaluation of Adhesion

[0073] A cutting of 10.times.10 squares (100 squares in total) was created in the surface of each specimen with a cutter, and a number of squares was counted in which the colored coating did not peel off when a cellophane tape (registered trademark) was affixed and released. The size of one square was 1 mm.times.1 mm in length.times.width.

[0074] In each table, the ratio is shown by (a number of squares where the colored coating did not peel off)/100, which indicates that as the number of squares where the colored coating did not peel off is larger, the adhesion of the colored coating is higher.

[0075] Tables 1 to 9 show test conditions and evaluation results for Examples 1 to 91 and Comparative Examples 1 to 4.

TABLE-US-00001 TABLE 1 No Example 1 Example 2 Example 3 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 0.5 g/L K permanganate 1 g/L K permanganate 2 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 3 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 10 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone C C A Adhesion 100/100 100/100 100/100 No Example 4 Example 5 Example 6 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 10 g/L K permanganate 20 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 7 g/L Na phosphate 10 g/L Condensed Phosphoric Acid Na pyrophosphate 20 g/L Na pyrophosphate 9 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone B F B Adhesion 100/100 100/100 100/100 No Example 7 Example 8 Example 9 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 30 g/L K permanganate 50 g/L Na permanganate 7 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 1 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 10 g/L Na pyrophosphate 15 g/L Na pyrophosphate 20 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone E E B Adhesion 100/100 100/100 100/100 No Example 10 Example 11 Example 12 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof Zn permanganate 3 g/L Mg permanganate 11 g/L Ca permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 10 g/L Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 12 g/L Na pyrophosphate 23 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone B B B Adhesion 100/100 100/100 100/100 No Example 13 Example 14 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof Ammonium permanganate 14 g/L Permanganic acid 7 g/L Inorganic Acid and Salt Thereof Na phosphate 15 g/L Na phosphate 3 g/L Condensed Phosphoric Acid Na pyrophosphate 6 g/L Na pyrophosphate 25 g/L and Its Salt Temperature 40 C. 40 C. Time 2 min 2 min pH 11.5 11.5 Color Tone B B Adhesion 100/100 100/100

TABLE-US-00002 TABLE 2 No Example 15 Example 16 Example 17 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 3 g/L K permanganate 7 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 0.5 g/L Na phosphate 1 g/L Na phosphate 3 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone C A A Adhesion 100/100 100/100 100/100 No Example 18 Example 19 Example 20 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 7 g/L K permanganate 5 g/L K permanganate 10 g/L Inorganic Acid and Salt Thereof Na phosphate 10 g/L Na phosphate 20 g/L Na phosphate 30 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone B B F Adhesion 100/100 100/100 100/100 No Example 21 Example 22 Example 23 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 10 g/L K permanganate 8 g/L K permanganate 10 g/L Inorganic Acid and Salt Thereof Na phosphate 60 g/L Na phosphate 100 g/L Na phosphate 100 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40 C. 40 C. 40 C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone D D E Adhesion 100/100 100/100 100/100 No Example 24 Example 25 Example 26 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 40 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na carbonate 10 g/L Na nitrate 20 g/L Nitric Acid 3 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 1 g/L and Its Salt Temperature 60 C. 60 C. 40 C. Time 2 min 2 min 2 min pH 11. 13 1 Color Tone A E A Adhesion 100/100 100/100 100/100 No Example 27 Example 28 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Nitric Acid 1 g/L Nitric Acid 1 g/L Copper Chloride 3 g/L Zinc Sulfate 3 g/L Condensed Phosphoric Acid Na pyrophosphate 1 g/L Na pyrophosphate 1 g/L and Its Salt Temperature 60 C. 60 C. Time 2 min 2 min pH 1 1 Color Tone D D Adhesion 100/100 100/100

TABLE-US-00003 TABLE 3 No Example 29 Example 30 Example 31 Example 32 Colored Sample A5052 A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 10 g/L K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 15 g/L Na phosphate 5 g/L Na phosphate 10 g/L Na phosphate 5 g/L Condensed Phosphoric Acid K pyrophosphate 1 g/L K pyrophosphate 3 g/L K pyrophosphate 10 g/L K pyrophosphate 25 g/L and Its Salt Temperature 40 C. 40 C. 40 C. 40 C. Time 2 min 2 min 2 min 2 min pH 11.5 11.5 11.5 11.5 Color Tone C C A B Adhesion 100/100 100/100 100/100 100/100 No Example 33 Example 34 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 8 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 1 g/L Condensed Phosphoric Acid K pyrophosphate 30 g/L K pyrophosphate 50 g/L and Its Salt Temperature 40 C. 40 C. Time 2 min 2 min pH 11.5 11.5 Color Tone B F Adhesion 100/100 100/100 No Example 35 Example 36 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 7 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate5 g/L Na phosphate2 g/L Condensed Phosphoric Acid K pyrophosphate 85 g/L K pyrophosphate 120 g/L and Its Salt Temperature 40 C. 40 C. Time 2 min 2 min pH 11.5 11.5 Color Tone F D Adhesion 100/100 100/100 No Example 37 Example 38 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 10 g/L Inorganic Acid and Salt Thereof Na phosphate1 g/L Na phosphate5 g/L Condensed Phosphoric Acid K pyrophosphate 150 g/L K pyrophosphate 150 g/L and Its Salt Temperature 40 C. 40 C. Time 2 min 2 min pH 11.5 11.5 Color Tone D E Adhesion 100/100 100/100 No Example 39 Example 40 Example 41 Example 42 Colored Sample A5052 A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 3 g/L Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na tripolyphosphate 1 g/L Na tripolyphosphate 15 g/L Na tripolyphosphate 50 g/L K pyrophosphate 3 g/L and Its Salt -- -- -- Na tripolyphosphate 1 g/L Temperature 40.degree. C. 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min 2 min pH 11.5 11.5 11.5 11.5 Color Tone C A B A Adhesion 100/100 100/100 100/100 100/100 No Example 43 Example 44 Example 45 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 7 g/L K permanganate 10 g/L K permanganate 15 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid K pryophosphate 10 g/L K pyrophosphate 50 g/L K pyrophosphate 50 g/L and Its Salt Na tripolyphosphate 20 g/L Na tripolyphosphate 20 g/L Na tripolyphosphate 50 g/L Temperature 50.degree. C. 40.degree. C. 50.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone B D E Adhesion 100/100 100/100 100/100

TABLE-US-00004 TABLE 4 No Example 46 Example 47 Example 48 Example 40 Colored Sample A5052 A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L K permanganate 7 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 3 g/L Na phosphate 5 g/L Na phosphate 15 g/L Condensed Phosphoric Acid Na pyrophosphate Na pyrophosphate Na pyrophosphate Na pyrophosphate and Its Salt 10 g/L 15 g/L 15 g/L 15 g/L Oxyacid and Salt Thereof Na Perchlorate 0.5 g/L Na Perchlorate 1 g/L Na Perchlorate 10 g/L Na Perchlorate 15 g/L Temperature 40.degree. C. 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min 2 min pH 11.5 11.5 11.5 11.5 Color Tone C B A F Adhesion 100/100 100/100 100/100 100/100 No Example 50 Example 51 Example 52 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 15 g/L K permanganate 10 g/L Inorganic Acid and Salt Thereof Na phosphate 25 g/L Na phosphate 5 g/L Na phosphate 15 g/L Condensed Phosphoric Acid Na pyrophosphate Na pyrophosphate Na pyrophosphate and Its Salt 15 g/L 20 g/L 15 g/L Oxyacid and Salt Thereof Na Perchlorate 30 g/L Na Perchlorate 50 g/L Na Perchlorate 100 g/L Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone F D E Adhesion 100/100 100/100 100/100 No Example 53 Example 54 Example 55 Colored Sample A5052 A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Oxyacid and Salt Thereof Na chlorate 15 g/L Na chlorite 15 g/L Na hypochlorite 15 g/L Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone C B A Adhesion 100/100 100/100 100/100 No Example 56 Example 57 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Oxyacid and Salt Thereof Sodium bromate 15 g/L Na borate 15 g/L Temperature 40.degree. C. 40.degree. C. Time 2 min 2 min pH 11.5 11.5 Color Tone E D Adhesion 100/100 100/100 No Example 58 Example 59 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 10.degree. C. 30.degree. C. Time 2 min 2 min pH 11.5 11.5 Color Tone C A Adhesion 100/100 100/100 No Example 60 Example 61 Colored Sample A5052 A5052 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 60.degree. C. 80.degree. C. Time 2 min 2 min pH 11.5 11.5 Color Tone D E Adhesion 100/100 100/100

TABLE-US-00005 TABLE 5 No Example 62 Example 63 Example 64 Colored Sample A5052 A5052 A5052 Permanganic acid and Salt Thereof K permanganate 5 g/L K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid K pyrophosphate 15 g/L K pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 30 sec 1 min 10 min pH 11.5 11.5 11.5 Color Tone C A D Adhesion 100/100 100/100 100/100 No Example 05 Example 66 Colored Sample A5052 A5052 Permanganic acid and Salt Thereof K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40.degree. C. 40.degree. C. Time 15 min 20 min pH 11.5 11.5 Color Tone E E Adhesion 100/100 100/100 No Example 67 Example 68 Example 69 Colored Sample A2017 A2017 A2017 Permanganic acid or Salt Thereof K permanganate 0.5 g/L K permanganate 1 g/L K permanganate 2 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 3 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L Na pyrophosphate 10 g/L and Its Salt Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone C C A Adhesion 100/100 100/100 100/100 No Example 70 Example 71 Example 72 Colored Sample A2017 A2017 A2017 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 10 g/L K permanganate 20 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 7 g/L Na phosphate 10 g/L Condensed Phosphoric Acid Na pyrophosphate 20 g/L Na pyrophosphate 9 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 115 Color Tone A B F Adhesion 100/100 100/100 100/100

TABLE-US-00006 TABLE 6 No Example 73 Example 74 Example 75 Colored Sample A2017 A2017 A2017 Permanganic acid or Salt Thereof K permanganate 30 g/L K permanganate 50 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 1 g/L Na phosphate 10 g/L Condensed Phosphoric Acid Na pyrophosphate 10 g/L Na pyrophosphate 15 g/L Na pyrophosphate 15 g/L and Its Salt Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone D E B Adhesion 100/100 100/100 100/100 No Example 76 Example 77 Example 78 Colored Sample A2017 A2017 A2017 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L K permanganate 8 g/L Inorganic Acid and Salt Thereof Na phosphate 40 g/L Na phosphate 15 g/L Na phosphate 5 g/L Condensed Phosphoric Acid Na pyrophosphate 15 g/L K pyrophosphate 1 g/L K pyrophosphate 30 g/L and Its Salt Temperature 40.degree. C. 40.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone D C A Adhesion 100/100 100/100 100/100 No Example 79 Example 80 Example 81 Colored Sample A2017 A2017 A2017 Permanganic acid or Salt Thereof K permanganate 7 g/L K permanganate 10 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5 g/L Na phosphate 15 g/L Condensed Phosphoric Acid K pyrophosphate 10 g/L K pyrophosphate 50 g/L Na pyrophosphate 15 g/L and Its Salt Na tripolyphosphate 20 g/L Na tripolyphosphate 20 g/L Na Perchlorate 15 g/L Temperature 40.degree. C. 50.degree. C. 40.degree. C. Time 2 min 2 min 2 min pH 11.5 11.5 11.5 Color Tone A D B Adhesion 100/100 100/100 100/100 No Example 82 Example 83 Colored Sample A2017 ADC12 Permanganic acid or Salt Thereof K permanganate 15 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 5g/L Condensed Phosphoric Acid Na pyrophosphate 20 g/L K pyrophosphate 30 g/L and Its Salt Na Perchlorate 70 g/L Temperature 40.degree. C. 40.degree. C. Time 2 min 2 min pH 11.5 11.5 Color Tone D D Adhesion 100/100 100/100

TABLE-US-00007 TABLE 7 Example 87 Zinc Plating No Example 84 Example 85 Example 86 (SPCC Upper Film Colored Sample C2600P C1100P ZDC2 Thickness 8 .mu.m) Permanganic acid or Salt Thereof K permanganate 15 g/L K permanganate 5 g/L K permanganate 20 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L Na phosphate 20 g/L Na phosphate 20 g/L Na phosphate 5 g/L Condensed Phosphoric Acid and K pyrophosphate 30 g/L K pyrophosphate 30 g/L K pyrophosphate 30 g/L K pyrophosphate 10 g/L Its Salt Temperature 60.degree. C. 60.degree. C. 60.degree. C. 60.degree. C. Time 5 min 2 min 2 min 2 min pH 11.5 11.5 11.5 11.5 Color Tone D D D D Adhesion 100/100 100/100 100/100 100/100 No Example 88 Example 89 Colored Sample SPCC Plate AZ31 Permanganic acid or Salt Thereof K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 20 g/L Na phosphate 3 g/L Condensed Phosphoric Acid and K pyrophosphate 30 g/L K pyrophosphate 10 g/L Its Salt Temperature 60.degree. C. 40.degree. C. Time 2 min 2 min pH 11.5 11.5 Color Tone D D Adhesion 100/100 100/100

TABLE-US-00008 TABLE 8 No Example 90 Example 91 Step Coloring Coating Coloring Coating Colored Sample A5052 A5052 A5052 A5052 1 K permanganate 2 g/L Stron JS Coat 200 mL/L K permanganate 2 g/L TR-170 200 mL/L 3 Na phosphate 5 g/L -- Na phosphate 5 g/L -- 4 Na pyrophosphate 15 g/L -- Na pyrophosphate 15 g/L -- 5 -- -- -- -- Temperature 40.degree. C. 25.degree. C. 40.degree. C. 25.degree. C. Time 2 min 30 sec 2 min 30 sec pH 11.5 -- 11.5 -- Color Tone A A A A Adhesion 100/100 100/100 100/100 100/100

TABLE-US-00009 TABLE 9 No Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Colored Sample A5052 A5052 A5052 A5052 Permanganic acid or Salt Thereof -- K permanganate 5 g/L K permanganate 5 g/L K permanganate 5 g/L Inorganic Acid and Salt Thereof Na phosphate 5 g/L -- Na phosphate 5 g/L -- Condensed Phosphoric Acid and K pyrophosphate 15 g/L -- -- K pyrophosphate 15 g/L its Salt Temperature 40.degree. C. 40.degree. C. 40.degree. C. 30.degree. C. Time 2 min 5 min 2 min 5 min pH 11.5 7 11.5 9 Color Tone G G G G Adhesion -- -- -- --

[0076] It was confirmed from the above results that according to the metal coloring solution for chemical conversion treatment containing permanganic acid or the salt thereof, and one or both of the inorganic acid and the salt thereof, and condensed phosphate as in Examples 1 to 91, the surface of the metal could be colored into the yellowish to brownish color tone with good treatment efficiency.

[0077] On the other hand, it was confirmed that the metal surface could not be colored into the yellowish to brownish color tone unless the metal coloring solution for chemical conversion treatment contained permanganic acid or the salt thereof, and one or both of the inorganic acid and the salt thereof, and condensed phosphate, as can be seen from Comparative Examples 1 to 4.

Claims

1. A metal coloring solution for chemical conversion treatment, comprising: permanganic acid or a salt thereof; one or both of an inorganic acid and a salt thereof; and a condensed phosphate.

2. The metal coloring solution for chemical conversion treatment according to claim 1, wherein the permanganic acid or the salt thereof is permanganic acid, sodium permanganate, potassium permanganate, zinc permanganate, magnesium permanganate, calcium permanganate, ammonium permanganate, or a combination thereof.

3. The metal coloring solution for chemical conversion treatment according to claim 1, wherein the inorganic acid and the salt thereof are phosphoric acid, sulfuric acid, nitric acid, carbonic acid, hydrochloric acid, and salts thereof, or combinations thereof.

4. The metal coloring for chemical conversion treatment according to claim 1, wherein the condensed phosphate is potassium pyrophosphate, sodium tripolyphosphate, or a combination thereof.

5. The metal coloring solution for chemical conversion treatment according to claim 1, wherein the metal coloring solution for chemical conversion treatment contains 0.5 to 50 g/L of the permanganic acid or the salt thereof.

6. The metal coloring solution for chemical conversion treatment according to claim 1, wherein the metal coloring solution for chemical conversion treatment contains 0.5 to 100 g/L of the inorganic acid and the salt thereof.

7. The metal coloring solution for chemical conversion treatment according to claim 1, wherein the metal coloring solution for chemical conversion treatment contains 1 to 150 g/L of the condensed phosphate.

8. The metal coloring solution for chemical conversion treatment according to claim 1, further comprising an oxo acid or a salt thereof.

9. The metal coloring solution for chemical conversion treatment according to claim 8, wherein the oxo acid or the salt thereof is perchloric acid, chloric acid, chlorous acid, hypochlorous acid, bromic acid, boric acid, or a salt thereof, or a combination thereof.

10. The metal coloring solution for chemical conversion treatment according to claim 8, wherein the metal coloring solution for chemical conversion treatment contains 0.5 to 100 g/L of the oxo acid or the salt thereof.

11. The metal coloring solution for chemical conversion according to claim 1, wherein the metal to be treated is at least one selected from the group consisting of aluminum, aluminum alloys, copper, copper alloys, iron, iron alloys, zinc, zinc alloys, magnesium, and magnesium alloys.

12. A method for coloring a metal, comprising a step of coloring the metal by a chemical conversion treatment using the metal coloring solution for chemical conversion treatment according to claim 1.

13. The method for coloring the metal according to claim 12, wherein the step of coloring the metal by the chemical conversion treatment comprises immersing the metal in the metal coloring solution for chemical conversion treatment at a temperature of 10.degree. C. to 80.degree. C. for 30 seconds to 20 minutes to color the metal.