Chemical conversion agent and metal surface treatment method

Abstract

Provided is a chemical conversion agent that, with respect to an aluminum metal material, etc., contributes to superior corrosion and moisture resistance, contributes to superior adhesion with a laminate film, and contributes to superior hydrofluoric acid and alkali resistance. The chemical conversion agent includes: one or more type of metal element (A) selected from a group comprising of zirconium, titanium, and hafnium; vanadium element (B); and a resin (C). The resin (C) includes a polyvinyl alcohol resin (C1). The ratio (Wa/Wb) of the weight-based total content (Wa) of the metal element (A) relative to the weight-based content (Wb) of vanadium element (B) is 0.1-15, and the ratio ((Wa+Wb)/Wc1) of the weight-based total content (Wa+Wb) of the metal element (A) and the vanadium element (B) relative to the weight-based total content (Wc1) of the polyvinyl alcohol resin (C1) is 0.25-15.

Claims

1. A chemical conversion agent comprising one, or two or more metal element(s) (A) selected from the group consisting of zirconium, titanium, and hafnium, a vanadium element (B), and a resin (C), wherein the chemical coversion agent only includes, as the resin (C), a polyvinyl alcohol-based resin (C1) consisting of at least one of polyvinyl alcohol and a derivative thereof, and one, or two or more metal ion-crosslinkable polymer(s) (C2), wherein a polymerization degree of the polyvinyl alcohol-based resin (C1) is 500 to 1,100, wherein the metal ion-crosslinkable polymer (C2) is one, or two or more polymer(s) selected from the group consisting of polyacrylic acid, phosphoric acid polymer, phosphonic acid polymer, water-soluble or water-dispersible epoxy polymer, water-soluble or water-dispersible urethane-based polymer, and polyester, wherein the value of a ratio (Wa/Wb) of the mass-based total content (Wa) of the metal element (A) to the mass-based content (Wb) of the vanadium element (B) is 0.1-15, wherein the value of a ratio ((Wa+Wb)/Wc1) of the mass-based total content (Wa+Wb) of the metal element (A) and the vanadium element (B) to the mass-based total content (Wc1) of the polyvinyl alcohol-based resin (C1) is 0.25-15, and wherein the value of a ratio (Wc2/(Wc1+Wc2)) of the mass-based total content (Wc2) of the metal ion-crosslinkable polymer (C2) to the mass-based total content (Wc1+Wc2) of the polyvinyl alcohol-based resin (C1) and the metal ion-crosslinkable polymer (C2) is 0.4 or less.

2. The chemical conversion agent according to claim 1, wherein the concentration of the metal element (A) in the chemical conversion agent is 50-100,000 ppm by mass, wherein the concentration of the vanadium element (B) is 50-100,000 ppm by mass, wherein the total concentration of the resin (C) is 50-100,000 ppm by mass, and wherein a pH is 0.5-6.5.

3. The chemical conversion agent according to claim 1, wherein an average saponification degree of the polyvinyl alcohol-based resin (C1) is 80% or more.

4. The chemical conversion agent according to claim 1, which further includes a surfactant.

5. The chemical conversion agent according to claim 1, which is used for a surface treatment of an aluminum-based metal material.

6. A metal surface treatment method for treating a surface of a metal material, which comprises the steps of: applying the chemical conversion agent according to claim 1 on the metal material, and drying the chemical conversion agent applied on the metal material.

Description

EXAMPLES

(1) The present invention will be described in more detail by way of Examples, but the present invention is not limited thereto. Part(s), percentage(s), and ppm(s) are by mass unless otherwise specified.

(2) Pure water, a zirconium-based compound (or a titanium-based compound), a vanadium-based compound, a resin, and a surfactant were mixed so that the mass-based content of each of a metal element (A), a vanadium element (B), a resin (C1), and a resin (C2) become the numerical values as shown in Tables 1-3 to prepare chemical conversion agents of Examples and Comparative Examples. The pH of each chemical conversion agent was adjusted within a range shown in Tables 1-6 using an 25% aqueous ammonia solution or 67.5% nitric acid. Types of zirconium-based compounds, vanadium-based compounds, resins, and surfactants shown in Tables 1-6 are listed below.

(3) Compound serving as Supply Source of Metal Element (A)

(4) (a) Zirconium ammonium fluoride

(5) (b) Zirconium acetate

(6) (c) Tetra-n-propoxyzirconium

(7) (d) Titanium ammonium fluoride

(8) Supply Source of Vanadium-Based Compound (Vanadium Element (B))

(9) (a) Vanadyl sulfate

(10) (b) Ammonium metavanadate

(11) (c) Triisopropoxy oxovanadium

(12) Resin (C1)

(13) (a) PVA-110 (polyvinyl alcohol, saponification degree: 98-99%, polymerization degree: 1,000, manufactured by KURARAY CO., LTD.)

(14) (b) PVA-105 (polyvinyl alcohol, saponification degree: 98-99%, polymerization degree: 500, manufactured by KURARAY CO., LTD.)

(15) (c) PVA-405 (polyvinyl alcohol, saponification degree: 80-83%, polymerization degree: 500, manufactured by KURARAY CO., LTD.)

(16) (f) GOHSEFIMER Z-200 (acetoacetyl group-modified vinyl alcohol, saponification degree: 99%, polymerization degree: 1,100, acetoacetyl group modification degree: 4-5 mol %, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)

(17) (h) PVA-505 (polyvinyl alcohol, saponification degree: 72.5-74.5%, polymerization degree: 500, manufactured by KURARAY CO., LTD.)

(18) Resin (C2)

(19) (d) JURYMER AC10L (polyacrylic acid, manufactured by Nihonjunyaku Co.)

(20) (e) Poly-Nass PS-1 (polystyrenesulfonic acid, manufactured by Tosoh Organic Chemical Co., Ltd.)

(21) (g) PEO-1 (polyethylene glycol, manufactured by SUMITOMO SEIKA CHEMICALS CO., LTD.)

(22) (i) Polyvinylsulfonic acid (polyvinylsulfonic acid, manufactured by Sigma-Aldrich)

(23) (j) PAA-15C (polyallylamine, manufactured by NITTOBO MEDICAL CO., LTD.)

(24) Surfactant

(25) (a) Sodium lauryl sulfate (anionic surfactant, manufactured by Wako Pure Chemical Industries, Ltd.)

(26) (b) EMULGEN LS-110 (nonionic surfactant, manufactured by Kao Corporation)

(27) [Fabrication of Specimens]

(28) A chemical conversion treatment was carried out by dipping aluminum material pieces (manufactured by Nippon Testpanel Co., Ltd., material: A1100P, size: 0.870150 mm) in the thus obtained respective chemical conversion agents at 25 C. for 15 seconds. Here, the amount of adhered chemical conversion agent was adjusted so that the amount of the solid component in the chemical conversion coating film becomes 0.2 g/m.sup.2.

(29) The aluminum material pieces with a chemical conversion agent film formed on a surface were dried under the conditions at 150 C. for 30 minutes. As a result of drying, a chemical conversion coating film was formed on a surface of the aluminum material pieces. The aluminum material pieces was air-cooled at room temperature (25 C.) for 30 minutes to obtain specimens of the respective Examples and Comparative Examples.

(30) [Evaluation of Corrosion Resistance (SST Test)]

(31) The thus obtained specimens were left to stand for 240 hours while leaning against a salt water spraying device, taken out, washed with pure water and then dried in a drying furnace at 80 C. for 10 minutes. The area where white rust occurs was visually evaluated according to the below-mentioned evaluation criteria. Corrosion resistance was evaluated by two evaluators based on an average of the evaluation results of two evaluators. The evaluation results are shown in Tables 1-3. As a result of the SST test, score of 7 or more corresponds to a passing grade of corrosion resistance.

(32) (Evaluation Criteria)

(33) 10: No white rust occurs.

(34) 9: Area where white rust occurs is less than 10%.

(35) 8: Area where white rust occurs is 10% or more and less than 20%.

(36) 7: Area where white rust occurs is 20% or more and less than 30%.

(37) 6: Area where white rust occurs is 30% or more and less than 40%.

(38) 5: Area where white rust occurs is 40% or more and less than 50%.

(39) 4: Area where white rust occurs is 50% or more and less than 60%.

(40) 3: Area where white rust occurs is 60% or more and less than 70%.

(41) 2: Area where white rust occurs is 70% or more and less than 80%.

(42) 1: Area where white rust occurs is 80% or more and less than 90%.

(43) 0: Area where white rust occurs is 90% or more.

(44) [Evaluation of Moisture Resistance]

(45) With regard to the specimens obtained in the respective Examples and Comparative Examples, a humidity test was carried out under atmosphere at a temperature of 70 C. and a relative humidity of 98% or more for 500 hours. After the test, area where rust occurs was visually evaluated according to the following evaluation criteria. Moisture resistance was evaluated by two evaluators based on an average of the evaluation results of two evaluators. Since blackening has property that it finally changes into white rust, the area where rust occurs was calculated as the total of the area where blackening occurs and the area where white rust occurs. The evaluation results are shown in Tables 1-3. As a result of the moisture resistance test, score of 7 or more corresponds to a passing grade of moisture resistance.

(46) (Evaluation Criteria)

(47) 10: No rust occurs.

(48) 9: Area where rust occurs is less than 10%.

(49) 8: Area where rust occurs is 10% or more and less than 20%.

(50) 7: Area where rust occurs is 20% or more and less than 30%.

(51) 6: Area where rust occurs is 30% or more and less than 40%.

(52) 5: Area where rust occurs is 40% or more and less than 50%.

(53) 4: Area where rust occurs is 50% or more and less than 60%.

(54) 3: Area where rust occurs is 60% or more and less than 70%.

(55) 2: Area where rust occurs is 70% or more and less than 80%.

(56) 1: Area where rust occurs is 80% or more and less than 90%.

(57) 0: Area where rust occurs is 90% or more.

(58) [Preparation of Adhesion Treating Agent]

(59) Using EPOCROS WS-700 (manufactured by Nippon Shokubai Co., Ltd.) and PAA-15C (manufactured by Nittobo Medical Co., Ltd.), an adhesion treating agent was prepared so that a solid component mass ratio becomes 1:1 and a solid component concentration becomes 3% by mass. A numerical value with regard to EPOCROS WS-700 and PAA-15C in Tables 4-6 is a solid component mass ratio of EPOCROS WS-700 and PAA-15C.

(60) [Fabrication of Aluminum Member Specimens for Secondary Battery]

(61) A chemical conversion treatment was carried out by dipping aluminum material pieces (manufactured by Nippon Testpanel Co., Ltd., material: A3003P, size: 0.870150 mm) in the thus obtained respective chemical conversion agents, in the respective Examples and Comparative Examples, at 50 C. for 60 seconds, and then the above-mentioned adhesion treating agent was applied. Then, aluminum member specimens for secondary battery of the respective Examples and Comparative Examples were fabricated by thermally bonding at 240 C. for 15 seconds under a pressure of 0.4 MPa in a state where a film (PP or PET) is interposed between two aluminum material pieces.

(62) [Laminate Adhesion]

(63) With regard to the aluminum member specimens for secondary battery fabricated in the respective Examples and Comparative Examples, peel strength was measured using a load cell LTS-200N-S100 (manufactured by Minebea Co., Ltd.). A peeling rate during the measurement of the peel strength was set at 20 mm/min. Specimens where the tensile strength is 30 N/5 mm or more were rated pass (P), while specimens where the tensile strength is less than 30 N/5 mm were rated fail (F). The results are shown in Table 4 to Table 6.

(64) [Hydrofluoric Acid Resistance]

(65) The aluminum member specimens for secondary battery fabricated in the respective Examples and Comparative Examples were dipped in an aqueous 1,000 ppm hydrofluoric acid solution (hydrofluoric acid) at 80 C. for 2 weeks. A state of peeling of the film of the results were visually evaluated by the following three-grade criteria. The results are shown in Tables 4-6.

(66) A: 90% or more of a film remained.

(67) B: 70% or more and less than 90% of a film remained.

(68) C: Less than 70% of a film remained.

(69) [Alkali Resistance]

(70) The aluminum member specimens for secondary battery fabricated in the respective Examples and Comparative Examples were dipped in an aqueous 0.5% LiOH solution at 40 C. for 10 seconds. A state of peeling and a state of whitening of a surface of the film of the results were visually evaluated by the following three-grade criteria. The results are shown in Tables 4-6.

(71) A: Surface whitening was not observed, and 80% of more a film remained.

(72) B: Surface whitening was observed, and 80% of more a film remained.

(73) C: Surface whitening was observed, and less than 80% of more a film remained.

(74) TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 10 Chemical Metal Concentration (ppm) 2000 2000 2000 2000 400 2865 4500 4500 10000 4000 conversion element Type a d b c a a a a a a treatment (A) agent Vanadium Concentration (ppm) 1500 1500 1500 1500 2300 699 681 480 681 3200 (B) Type a a a a a b b c a a Resin Concentration (ppm) 4000 4000 4000 4000 5000 4100 5000 5000 10000 500 (C1) Type a a a a b c a a b b Resin Concentration (ppm) (C2) Type Surfactant Concentration (ppm) Type Wa/Wb 1.33 1.33 1.33 1.33 0.17 4.10 6.61 9.38 14.68 1.25 (Wa + Wb)/Wc 0.88 0.88 0.88 0.88 0.54 0.87 1.04 1.00 1.07 14.40 Wc2/(Wc1 + Wc2) 0 0 0 0 0 0 0 0 0 0 pH 2.5 2.5 2.5 2.5 2.5 2.5 5 6.5 2.5 2.5 Evaluation SST 10 9 9 9 9 10 10 10 10 10 results Moisture resistance test 10 9 9 9 10 9 9 8 7 7 Example 11 12 13 14 15 16 17 18 19 20 Chemical Metal Concentration (ppm) 3725 1000 930 180 494 663 930 2000 2000 2000 conversion element Type a a a a a a a a a a treatment (A) agent Vanadium Concentration (ppm) 2726 800 681 120 362 484 681 1500 1500 1500 (B) Type a a a a a a a a a a Resin Concentration (ppm) 1200 5000 6000 625 1625 1325 500 4000 4000 4000 (C1) Type c a a a a a a c a f Resin Concentration (ppm) (C2) Type Surfactant Concentration (ppm) Type Wa/Wb 1.37 1.25 1.37 1.50 1.37 1.37 1.37 1.33 1.33 1.33 (Wa + Wb)/Wc 5.38 0.36 0.27 0.48 0.53 0.87 3.22 0.88 0.88 0.88 Wc2/(Wc1 + Wc2) 0 0 0 0 0 0 0 0 0 0 pH 1.5 2.5 3 3 3 3 3 3 7.5 3 Evaluation SST 8 9 9 8 9 10 10 9 7 9 results Moisture resistance test 8 9 8 9 9 10 10 7 7 9

(75) TABLE-US-00002 TABLE 2 Example 21 22 23 24 25 26 27 28 Chemical Metal Concentration(ppm) 2000 2000 663 2000 2000 663 2000 2000 conversion element Type a a a a a a a a treatment (A) agent Vanadium Concentration (ppm) 1500 1500 484 1500 1500 484 1500 1500 (B) Type a a a a a a a a Resin Concentration (ppm) 3600 3600 3600 3200 3200 3200 2400 2400 (C1) Type a a a a a a a a Resin Concentration (ppm) 400 400 400 800 800 800 1600 1600 (C2) Type d i j d i j d i Surfactant Concentration (ppm) Type Wa/Wb 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 (Wa + Wb)/Wc 0.97 0.97 0.32 1.09 1.09 0.36 1.46 1.46 Wc2/(Wc1 + Wc2) 0.10 0.10 0.10 0.20 0.20 0.20 0.40 0.40 pH 3 3 3 3 3 3 3 3 Evaluation SST 10 10 10 8 9 9 7 7 results Moisture resistance test 10 10 10 8 9 9 7 7 Example 29 30 31 32 33 34 35 Chemical Metal Concentration(ppm) 663 2000 2000 2000 4500 4500 2000 conversion element Type a a a a a a b treatment (A) agent Vanadium Concentration (ppm) 484 1500 1500 1500 3200 3200 1500 (B) Type a a b a a a b Resin Concentration (ppm) 2400 3600 3600 4000 10000 10000 4000 (C1) Type a a a h a a h Resin Concentration (ppm) 1600 400 400 (C2) Type j e g Surfactant Concentration (ppm) 350 350 Type a b Wa/Wb 1.33 1.33 1.33 1.33 1.33 1.33 1.33 (Wa + Wb)/Wc 0.48 0.97 0.97 0.88 0.77 0.77 0.88 Wc2/(Wc1 + Wc2) 0.40 0.10 0.10 0 0 0 0 pH 3 3 3 2.5 3 3 3 Evaluation SST 7 7 7 7 10 10 7 results Moisture resistance test 7 7 7 7 10 10 7

(76) TABLE-US-00003 TABLE 3 Comparative Example 1 2 3 4 5 6 7 8 9 10 Chemical Metal Concentration (ppm) 260 300 300 2000 3300 2000 3500 2000 conversion element Type a a b a a a a a treatment (A) agent Vanadium Concentration (ppm) 3240 3500 220 220 1500 200 1500 1500 (B) Type a a a a a a a a Resin Concentration (ppm) 4000 4000 4000 4000 4000 210 4000 4000 (C1) Type a a a a a a b a Resin Concentration (ppm) 4000 (C2) Type d Surfactant Concentration (ppm) Type Wa/Wb 0.08 1.36 1.25 1.33 16.50 1.33 1.33 (Wa + Wb)/Wc 0.88 0.88 0.13 0.13 0.88 16.67 0.88 0.88 Wc2/(Wc1 + Wc2) 0 0 0 0 0 0 0 0 0 1 pH 2.5 2.5 3 3 2.5 2.5 2.5 3 3 2.5 Evaluation SST 6 5 4 3 8 6 8 5 1 5 results Moisture resistance test 6 6 6 4 6 4 6 5 3 6

(77) TABLE-US-00004 TABLE 4 Example 1 2 3 4 5 6 7 8 9 10 Chemical Metal Concentration (ppm) 2000 2000 2000 2000 400 2865 4500 4500 10000 4000 conversion element Type a d b c a a a a a a treatment (A) agent Vanadium Concentration (ppm) 1500 1500 1500 1500 2300 699 681 480 681 3200 (B) Type a a a a a b b c a a Resin Concentration (ppm) 4000 4000 4000 4000 5000 4100 5000 5000 10000 500 (C1) Type a a a a b c a a b b Resin Concentration (ppm) (C2) Type Surfactant Concentration (ppm) Type Wa/Wb 1.33 1.33 1.33 1.33 0.17 4.10 6.61 9.38 14.68 1.25 (Wa + Wb)/Wc 0.88 0.88 0.88 0.88 0.54 0.87 1.04 1.00 1.07 14.40 Wc2/(Wc1 + Wc2) 0 0 0 0 0 0 0 0 0 0 pH 2.5 2.5 2.5 2.5 2.5 2.5 5 6.5 2.5 2.5 Adhesion EPOCROS WS-700 1 1 1 1 1 1 1 1 1 1 treating PAA15-C 1 1 1 1 1 1 1 1 1 1 agent Laminate film PP PP PP PP PP PET PP PP PP PP Evaluation Laminate adhesion P P P P P P P P P P results Hydrofluoric acid resistance A A A A A A A A A A Alkali resistance A A A A A A A A A A Example 11 12 13 14 15 16 17 18 19 20 Chemical Metal Concentration (ppm) 3725 1000 930 180 494 663 930 2000 2000 2000 conversion element Type a a a a a a a a b a treatment (A) agent Vanadium Concentration (ppm) 2726 800 681 120 362 484 681 1500 1500 1500 (B) Type a a a a a a a a b a Resin Concentration (ppm) 1200 5000 6000 625 1625 1325 500 4000 4000 4000 (C1) Type c a a a a a a c a f Resin Concentration (ppm) (C2) Type Surfactant Concentration (ppm) Type Wa/Wb 1.37 1.25 1.37 1.50 1.37 1.37 1.37 1.33 1.33 1.33 (Wa + Wb)/Wc 5.38 0.36 0.27 0.48 0.53 0.87 3.22 0.88 0.88 0.88 Wc2/(Wc1 + Wc2) 0 0 0 0 0 0 0 0 0 0 pH 1.5 2.5 3 3 3 3 3 3 7.5 3 Adhesion EPOCROS WS-700 1 1 1 1 1 1 1 1 1 1 treating PAA15-C 1 1 1 1 1 1 1 1 1 1 agent Laminate film PP PP PP PP PP PP PP PP PP PP Evaluation Laminate adhesion P P P P P P P P P P results Hydrofluoric acid resistance A A A A A A A A B A Alkali resistance A A A A A A A A B A

(78) TABLE-US-00005 TABLE 5 Example 21 22 23 24 25 26 27 28 Chemical Metal Concentration (ppm) 2000 2000 663 2000 2000 663 2000 2000 conversion element Type a a a a a a a a treatment (A) agent Vanadium Concentration (ppm) 1500 1500 484 1500 1500 484 1500 1500 (B) Type a a a a a a a a Resin Concentration (ppm) 3600 3600 3600 3200 3200 3200 2400 2400 (C1) Type a a a a a a a a Resin Concentration (ppm) 400 400 400 800 800 800 1600 1600 (C2) Type d i j d i j d i Surfactant Concentration (ppm) Type Wa/Wb 1.33 1.33 1.33 1.33 1.33 1.33 1.33 1.33 (Wa + Wb)/Wc 0.97 0.97 0.32 1.09 1.09 0.36 1.46 1.46 Wc2/(Wc1 + Wc2) 0.10 0.10 0.10 0.20 0.20 0.20 0.40 0.40 pH 3 3 3 3 3 3 3 3 Adhesion EPOCROS WS-700 1 1 1 1 1 1 1 1 treating PAA15-C 1 1 1 1 1 1 1 1 agent Laminate film PP PP PP PP PP PP PP PP Evaluation Laminate adhesion P P P P P P P P results Hydrofluoric acid resistance A A A A A A B B Alkali resistance A A A A A A B B Example 29 30 31 32 33 34 35 Chemical Metal Concentration (ppm) 663 500 2000 2000 4500 4500 2000 conversion element Type a a a a a a b treatment (A) agent Vanadium Concentration (ppm) 484 500 1500 1500 3200 3200 1500 (B) Type a a b a a a b Resin Concentration (ppm) 2400 3600 3600 4000 10000 10000 4000 (C1) Type a a a h a a h Resin Concentration (ppm) 1600 400 400 (C2) Type j e g Surfactant Concentration (ppm) 350 350 Type a b Wa/Wb 1.33 1.00 1.33 1.33 1.33 1.33 1.33 (Wa + Wb)/Wc 0.48 0.28 1.09 0.88 0.77 0.77 0.88 Wc2/(Wc1 + Wc2) 0.40 0.10 0.10 0 0 0 0 pH 3 3 3 2.5 3 3 3 Adhesion EPOCROS WS-700 1 1 1 1 1 1 1 treating PAA15-C 1 1 1 1 1 1 1 agent Laminate film PP PP PP PP PP PP PP Evaluation Laminate adhesion P P P P P P P results Hydrofluoric acid resistance B A B B A A B Alkali resistance B A B B A A B

(79) TABLE-US-00006 TABLE 6 Comparative Example 1 2 3 4 5 6 7 8 9 10 Chemical Metal Concentration (ppm) 260 300 300 2000 3300 2000 3500 2000 conversion element Type a a b a a a a a treatment (A) agent Vanadium Concentration (ppm) 3240 3500 220 220 1500 200 1500 1500 (B) Type a a a a a a a a Resin Concentration (ppm) 4000 4000 4000 4000 4000 210 4000 4000 (C1) Type a a a a a a b a Resin Concentration (ppm) 4000 (C2) Type d Surfactant Concentration (ppm) Type Wa/Wb 0.08 1.36 1.25 1.37 16.50 1.33 1.33 (Wa + Wb)/Wc 0.88 0.88 0.13 0.13 0.88 16.67 0.38 0.88 Wc2/(Wc1 + Wc2) 0 0 0 0 0 0 0 0 0 1 pH 2.5 2.5 3 3 2.5 2.5 2.5 3 3 2.5 Adhesion EPOCROS WS-700 1 1 1 1 1 1 1 1 1 1 treating PAA15-C 1 1 1 1 1 1 1 1 1 1 agent Laminate film PP PP PP PP PP PP PP PP PP PP Evaluation Laminate adhesion P P P P F P P P P P results Hydrofluoric acid resistance C C C C C C C C C C Alkali resistance B C C C C C C C C B

(80) The results of Table 1 to Table 6 revealed that, when using a chemical conversion agent including one, or two or more metal element(s) (A) selected from the group consisting of zirconium, titanium, and hafnium; a vanadium element (B); and a resin (C); in which the resin (C) includes a polyvinyl alcohol-based resin (C1) consisting of at least one of polyvinyl alcohol and a derivative thereof; the value of a ratio (Wa/Wb) of the mass-based total content (Wa) of the metal element (A) to the mass-based content (Wb) of the vanadium element (B) is 0.1-15, and the value of a ratio ((Wa+Wb)/Wc1) of the mass-based total content (Wa+Wb) of the metal element (A) and the vanadium element (B) to the mass-based total content (Wc1) of the polyvinyl alcohol-based resin (C1) is 0.25-15; it is possible to provide a chemical conversion coating film with excellent corrosion resistance and moisture resistance, and also to provide a chemical conversion coating film with excellent adhesion to a laminate film, and excellent hydrofluoric acid resistance and alkali resistance.

INDUSTRIAL APPLICABILITY

(81) The chemical conversion agent of the present invention is preferably used for a surface treatment of die castings, heat exchangers, food containers, members for secondary battery and the like since the chemical conversion agent is capable of providing, for example, an aluminum-based metal material with excellent corrosion resistance and moisture resistance, while also providing the aluminum-based metal material with excellent adhesion with a laminate film, excellent hydrofluoric acid resistance and excellent alkali resistance.