Nonchromate metallic surface-treating agent, nonchromate metallic surface-treating method, and aluminum or aluminum alloy

Abstract

An object of the present invention is to provide a nonchromate metallic surface-treating agent capable of achieving the corrosion resistance and adhesion with a coating film equal to a chromium phosphate surface-treating agent. A nonchromate metallic surface-treating agent comprising a water-soluble zirconium compound and/or a water-soluble titanium compound (1), an organic phosphonic acid compound (2) and a tannin (3), wherein a content of zirconium and/or titanium of said water-soluble zirconium compound and/or the water-soluble titanium compound (1) is 40 to 1000 ppm on a mass basis, a content of said organic phosphonic acid compound (2) is 20 to 500 ppm on a mass basis, a content of said tannin (3) is 200 to 5000 ppm on a mass basis, and a nonchromate metallic surface-treating agent has a pH of 1.6 to 4.0.

Description

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a nonchromate metallic surface-treating agent, nonchromate metallic surface-treating method, and aluminum or an aluminum alloy.

[0002] As surface treatment of aluminum plates, a chromium phosphate surface-treating agent has been used. Since chemical conversion coats formed with the chromium phosphate surf-ace-treating agent are excellent in the corrosion resistance of the coatings alone and in the corrosion resistance and adhesion after applying various resin base coatings, they are adopted in a wide range of uses of aluminum materials for construction materials, an electric home appliance, fin materials, car evaporators, beverage can materials and the like. However, in recent years, there is required a nonchromate metallic surface-treating agent, which can provide the high corrosion resistance and adhesion equal to a chromium phosphate surface-treating agent, from the view point of environmental protection.

[0003] As a nonchromate chemical conversion treating agent, for example, a system where a zirconium or titanium compound is used in conjunction with a phosphoric acid compound for a beverage can material. However, since the chemical conversion coats formed by these systems are of inferior corrosion resistance and adhesion after applying coating in comparison with the coatings formed by the chromium phosphate surface-treating agent, these could not be used for a wide range of uses.

[0004] Japanese Kokai Publication Sho-56-33468 discloses a surface-treating agent for aluminum comprising zirconium and/or titanium, phosphate and fluoride. However, in this technology, it is insufficient in the high adhesion with a coating and the corrosion resistance as a coating material.

[0005] Japanese Kokai Publication Sho-63-30218 discloses a nonchromate metallic surface-treating agent comprising a water-soluble titanium and/or zirconium compound, a tannin and/or a water-soluble or water-dispersant high polymer. However, such a nonchromate surface-treating agent is insufficient in the corrosion resistance as a coated material.

SUMMARY OF THE INVENTION

[0006] In consideration of the circumstances, an object of the present invention is to provide a nonchromate metallic surface-treating agent capable of achieving the corrosion resistance and adhesion with a coating film equal to a chromium phosphate surface-treating agent.

[0007] This invention is a nonchromate metallic surface-treating agent comprising

[0008] a water-soluble zirconium compound and/or a water-soluble titanium compound (1), an organic phosphonic acid compound (2) and a tannin (3),

[0009] wherein a content of zirconium and/or titanium of said water-soluble zirconium compound and/or the water-soluble titanium compound (1) is 40 to 1000 ppm on a mass basis,

[0010] a content of said organic phosphonic acid compound (2) is 20 to 500 ppm on a mass basis,

[0011] a content of said tannin (3) is 200 to 5000 ppm on a mass basis, and

[0012] a nonchromate metallic surface treating-agent has a pH of 1.6 to 4.0.

[0013] Said organic phosphonic acid compound is preferably a compound in which phosphorus atom forming a phosphonic group combines with carbon atom.

[0014] This invention is a nonchromate metallic surface-treating method comprising

[0015] a step (A) of treating a substrate to be treated with said nonchromate metallic surface-treating agent.

[0016] Said nonchromate metallic surface-treating method preferably comprises an acid cleaning step followed by said step (A).

[0017] Preferably, an alkaline cleaning step is performed and then an acid cleaning step is performed before said step (A) is performed.

[0018] This invention is aluminum or an aluminum alloy having a coat obtained by said nonchromate metallic surface-treating method.

[0019] Said coat, after drying, preferably contains said water-soluble zirconium compound and/or the water-soluble titanium compound (1) with zirconium and/or titanium atom of 4.0 to 30 mg/m.sup.2, by mass per one surface, and said-organic phosphonic acid compound (2) with phosphorus atom of 0.05 to 0.3 and said tannin (3) with carbon atom of 0.5 to 3 relative to zirconium and/or titanium atom of said water-soluble zirconium compound and/or said water-soluble titanium compound (1), on a mass basis.

BRIEF DESCRIPTION OF THE DRAWING

[0020] FIG. 1 is a schematic view illustrating the shape of a sample for evaluating corrosion resistance.

EXPLANATION OF THE NUMERICAL SYMBOLS

[0021] 1: Plane portion

[0022] 2: Edge portion

[0023] 3: Side portion

DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereafter, the present invention will be described in detail.

[0025] The nonchromate metallic surface-treating agent of the present invention is a surface-treating agent which can provide the excellent corrosion resistance and adhesion with a coating film after applying coatings and which does not contain chromium. Particularly, it is suitably applicable to aluminum or an aluminum alloy, and can provide the excellent corrosion resistance and adhesion with a coating film, for example, in applying it to aluminum or an aluminum alloy for beverage cans or an electric home appliance.

[0026] The nonchromate metallic surface-treating agent of the present invention contains a water-soluble zirconium compound and/or a water-soluble titanium compound (1). Though the water-soluble zirconium compound is not limited in particular so long as it is a compound containing zirconium, a water-soluble zirconium compound containing fluorine is preferred since it has good stability in an applicable pH range and it is high in the formability of a coat.

[0027] Said water-soluble zirconium compound containing fluorine is not limited in particular, and examples thereof may include H.sub.2ZrF.sub.6, (NH.sub.4).sub.2ZrF.sub.6, K.sub.2ZrF.sub.6, Na.sub.2ZrF6, Li.sub.2ZrF6 and the like. These compounds may be used alone or in combination of two kinds or more.

[0028] Though said water-soluble titanium compound is not limited in particular so long as it is a compound containing titanium, a water-soluble titanium compound containing fluorine is preferred since it has the good stability in an applicable pH range and it is high in the formability of a coat.

[0029] Said water-soluble titanium compound containing fluorine is not limited in particular, and examples thereof may include H.sub.2TiF.sub.6, (NH.sub.4).sub.2TiF.sub.6, K.sub.2TiF.sub.6, Na.sub.2TiF.sub.6 and the like. These compounds may be used alone or in combination of two kinds or more.

[0030] The content of the water-soluble zirconium compound and/or the water-soluble titanium compound (1) with zirconium and/or titanium has a lower limit of 40 ppm and an upper limit of 1000 ppm on amass basis in the nonchromate metallic surface-treating agent. When the content is less than 40 ppm, there is a possibility that a sufficient amount of zirconium or titanium in coats could be not obtained in a short-time treatment and the adhesion and corrosion resistance could be degraded. When the content exceeds 1000 ppm, there is a possibility that the adhesion with a coating film after applying coatings could be degraded and also a possibility of being relatively expensive since the enhancement of performances and the reduction in treatment time are not recognized. Preferably, the lower limit is 100 ppm and the upper limit is 300 ppm. It is noted that the content of the water-soluble zirconium compound and/or the water-soluble titanium compound is the sum of the masses of zirconium and titanium contained in the nonchromate metallic surface-treating agent.

[0031] The nonchromate metallic surface-treating agent of the present invention contains an organic phosphonic acid compound (2).

[0032] Said organic phosphonic acid compound (2) means an organic compound containing a phosphonic group (--PO.sub.3H.sub.2), and this compound (2) is preferably compound in which the phosphonic group (--PO.sub.3H.sub.2) combines with carbon atom.

[0033] Among said organic phosphonic acid compounds (2), the compound in which the phosphonic group (--PO.sub.3H.sub.2) combines with carbon atom is not limited in particular, and examples thereof may include aminotri(methylenephosphonic acid) represented by the following formula (a), 1-hydroxyethylidene-1,1-diphosphonic acid represented by the following formula (b), 2-phosphobutanone-1,2,4-tricarboxylic acid represented by the following formula (c), and the like.

[0034] Examples of the organic phosphonic acid compounds (2) may also include ethylenediaminetetra(methylenephosphonic acid) represented by the following formula (d), diethylenetriaminepenta(methylenephosphonic acid) represented by the following formula (e), and the like.

[0035] Among the organic phosphonic acid compounds (2), aminotri (methylenephosphonic acid) represented by the formula (a), 1-hydroxyethylidene-1,1-diphosphonic acid represented by the formula (b), and 2-phosphobutanone-1,2,4-tricarboxylic acid represented by the formula (c) are preferred since these are excellent in the precipitability of coats and the corrosion resistance and adhesion with a coating film after applying coatings.

[0036] Preferably, the organic phosphonic acid compounds (2) are water-soluble. When this is a water-soluble compound, the use of an organic solvent is not required and a burden on the environment can be reduced.

[0037] The organic phosphonic acid compounds (2) maybe used alone or in combination of two kinds or more. It is noted that it is not preferred to include salts of organic phosphonic acid compounds, which is obtained by replacing the hydrogen atom contained in a phosphonic group with alkaline metal, ammonium or the like, in the nonchromate metallic surface-treating agent since the corrosion resistance of the formed coat is decreased.

[0038] The content of the organic-phosphonic acid compound (2) has a lower limit of 20 ppm and an upper limit of 500 ppm on a mass basis in the nonchromate metallic surface-treating agent. When the content is less than 20 ppm, there is a possibility that an appropriate amount of phosphorus could be not obtained in the resulting coats to be formed and the adhesion with a coating film after applying coatings could be degraded. Even if the content exceeds 500 ppm, the organic phosphonic acid compound exists just only excessively and does not have an effect of enhancing the adhesion and corrosion resistance, and therefore there is a possibility of being relatively expensive. Preferably, the lower limit is 50 ppm and the upper limit is 200 ppm.

[0039] The nonchromate metallic surface-treating agent of the present invention contains tannin (3). Said tannin (3) is also referred to as tannic acid and is a generic name for aromatic compounds with a complicated structure, which has a number of phenolic hydroxyl groups being widely distributed over the plant kingdom. Said tannin (3) may be hydrolyzable tannin or condensed tannin.

[0040] Examples of the tannin (3) may include hamameli tannin, Japanese persimmon tannin, tea tannin, gallan tannin, gallnut tannin, myrobaran tannin, divi-divi tannin, valonia tannin, catechin tannin and the like. In addition, the tannin (3) may also be decomposed tannins which are formed by decomposing tannins contained in plants by a method such as hydrolysis.

[0041] As the tannin (3), commercial products such as "Tannin Acid Essence A", "B Tannic Acid", "N Tannic Acid", "Industrial Tannic Acid", "Purified Tannic Acid", "Hi Tannic Acid", "F Tannic Acid", "Officinal Tannic Acid" (all manufactured by Dainippon Pharmaceutical Co., Ltd.), "Tannin Acid: AL" (manufactured by Fuji Chemical Industry Co., Ltd.) can also be used. The above-mentioned tannins may be used alone or in combination of two kinds or more.

[0042] Preferably, the tannin (3) has the number-average molecular weight of 200 or more. If decomposition of tannin proceeds too much and the decomposed tannin becomes a compound with low molecular weight less than 200 when a product formed through the decomposition of tannin are used as the tannin (3), there is a possibility that the adhesion with a coating film after applying coatings could not be enhanced for lack of properties as tannin.

[0043] A content of the tannin (3) has a lower limit of 200 ppm and an upper limit of 5000 ppm on a mass basis in the nonchromate metallic surface-treating agent. When the content is less than 200 ppm, there is a possibility that an appropriate amount of carbon could be not obtained in coats to be formed and the corrosion resistance and adhesion with a coating film after applying coatings could be degraded. Even if the content exceeds 5000 ppm, there is a possibility of being relatively expensive since the enhancement of performances such as the corrosion resistance and adhesion with a coating and the reduction in treatment time are not recognized. Preferably, the lower limit is 500 ppm and the upper limit is 2000 ppm.

[0044] The nonchromate metallic surface-treating agent of the present invention has a pH within a range from a lower limit of 1.6 to an upper limit of 4.0. When the pH is less than 1.6, the coat appearance becomes bad since the etching of the metal surface become excessive, and the corrosion resistance of the obtained coat is degraded. When the pH exceeds 4.0, chemical conversion reaction does not proceed satisfactorily and the chemical conversion coat is hard to be formed. The lower limit is preferably 1.8, more preferably 2.2. The upper limit is preferably 3.4, more preferably 2.8.

[0045] In the nonchromate metallic surface-treating agent of the present invention, an etching assistant agent, a chelating agent and a pH regulator can be further used as required in addition to the above-mentioned components.

[0046] Examples of the etching assistant agent may include hydrofluoric acid, hydrofluoride, fluoboride and the like. Further, when as a source of fluorine ion, zirconium- or titanium complex which has been mentioned as the water-soluble zirconium compound or the water-soluble titanium compound (1) is used, it is preferred to use the fluorine compound in conjunction with this complex since the amount of produced fluorine ion is insufficient.

[0047] Examples of the chelating agents may include acids, which form complexes with aluminum, such as citric acid, tartaric acid and gluconic acid, and metal salts thereof.

[0048] Examples of the pH regulator may include acids or bases, which do not adversely affect surface treatments, such as nitric acid, perchloric acid, sulfuric acid, sodium nitrate, ammonium hydroxide, sodium hydroxide and ammonia.

[0049] A nonchromate metallic surface-treating method of the present invention comprises a step (A) of treating a substrate to be treated with the nonchromate metallic surface-treating agent. By performing the step (A), it is possible to provide the excellent corrosion resistance and adhesion with a coating film after applying coatings to the substrate.

[0050] An example of the substrate to be treated includes metallic base materials, and aluminum or an aluminum alloy is preferred. As the aluminum alloys, an aluminum alloy 5182 material, an aluminum alloy 5021 material, an aluminum alloy 5022 material, an aluminum alloy 5052 material, an aluminum alloy 3004 material, an aluminum alloy 3005 material, an aluminum alloy 1050 material, an aluminum alloy 1100 material and the like are suitably used. Applications of the substance to be treated are not limited in particular, and examples thereof include an electric home appliance, cases for food and beverage, construction materials and the like.

[0051] In the step (A), a method of treating the substrate to be treated is not limited in particular so long as it is a method of allowing the substrate to bring into contact with the nonchromate metallic surface-treating agent, and examples of ordinary methods may include a spray method, a immersion method and the like. Among them, a spray method is preferably used.

[0052] Said step (A) is preferably performed at a temperature range from a lower limit of 30.degree. C. to an upper limit of 80.degree. C. When the temperature is less than 30.degree. C., a reaction rate is lowered and the precipitability of coats is degraded. Therefore, an extension of treatment time is required to obtain a sufficient amount of coats, and productivity is decreased. When the temperature exceeds 80.degree. C., there is a possibility that energy losses become large. More preferably, the lower limit is 50.degree. C. and the upper limit is 70.degree. C.

[0053] In the case where the step (A) is performed with a spray method, a treatment time preferably is within a range from a lower limit of 1 second to an upper limit of 20 seconds. When the treatment time is less than 1 second, the amount of coats formed is insufficient and there is a possibility that the corrosion resistance and adhesion could be degraded. When the treatment time exceeds 20 seconds, there is a possibility that etching proceeds excessively in formation of coatings and the adhesion and corrosion resistance could be degraded. More preferably, the lower limit is 3 seconds and the upper limit is 8 seconds.

[0054] After the step (A), water-washing treatment may be performed as required.

[0055] The water-washing treatment is performed once or more not to adversely affect on the appearances of coating film and the like. In this case, it is appropriate to perform the final water-washing with pure water. In this water-washing treatment, either spray or immersion method may be used, and the combination thereof may also be used.

[0056] The coats obtained through the step (A) are preferably dried after water-washing. As a method of drying the coat, heat drying is preferred, and an example thereof includes oven-drying and/or heat drying through a forced circulation of hot air. These heat drying are generally performed at a temperature of 40 to 120.degree. C. for 6 to 60 seconds.

[0057] In the nonchromate metallic surface-treating method of the present invention, it is preferred that an acid cleaning step is performed before the step (A) is performed. Furthermore, it is preferred that an alkaline cleaning step is performed before the acid cleaning step is performed. The most preferable aspect is a method comprising an alkaline cleaning, a water-washing, an acid cleaning, a water-washing, nonchromate metallic surface treatment, water-washing and drying in this order.

[0058] The alkaline cleaning treatment is not limited in particular, and for example alkaline cleaning which has been adopted in the alkaline cleaning of the metals such as aluminum and aluminum alloys can be performed. In the alkaline cleaning treatment, generally, the alkaline cleaning is performed through the use of an alkaline cleaner. Further, the acid cleaning is performed through the use of an acid cleaner.

[0059] The alkaline cleaner is not limited in particular, and for example an alkaline cleaner used in a usual alkaline cleaning can be adopted. An example of the alkaline cleaner includes "SURF CLEANER 360" manufactured by Nippon Paint Co., Ltd. The acid cleaner is not limited in particular, and examples thereof include inorganic acids such as sulfuric acid, nitric acid and hydrochloric acid, and "SURF CLEANER ST160" manufactured by Nippon Paint Co., Ltd.

[0060] The acid cleaning and alkaline cleaning treatments are generally performed through a spray method. After the acid cleaning or alkaline cleaning treatment is performed, water-washing is performed to remove an acid cleaning agent or an alkaline cleaning agent remaining on the surface of the basis material.

[0061] Preferably, the coat obtained by the nonchromate metallic surface-treating method, after drying, contains the water-soluble zirconium compound and/or the water-soluble titanium compound (1) with zirconium and/or titanium atom within a range having a lower limit of 4 mg/m.sup.2 and an upper limit of 30 mg/m.sup.2 by mass per one surface. When the content thereof is less than 4 mg/m.sup.2, there is a possibility that the corrosion resistance after applying coatings could be degraded and when the content thereof exceeds 30 mg/m.sup.2, there is a possibility that the adhesion with a coating after applying coatings could be degraded. More preferably, the lower limit is 10 mg/m.sup.2 and the upper limit is 20 mg/m.sup.2. It is noted that the term mass per one surface, after drying, of the water-soluble zirconium compound and/or the water-soluble titanium compound means the sum of the masses of zirconium and titanium contained in the coat obtained by the nonchromate metallic surface-treating method.

[0062] In the coat obtained by the nonchromate metallic surface-treating method, the amounts of the respective component forming the coat can be obtained in desired amounts by appropriately setting the composition of the nonchromate metallic surface-treating agent, treatment temperature and treatment time.

[0063] Preferably, the coat obtained by the nonchromate metallic surface-treating method contains the organic phosphonic acid compound (2) with phosphorus atom within a range having a lower limit of 0.05 and an upper limit of 0.3 relative to zirconium and/or titanium atom of said water-soluble zirconium compound and/or said water-soluble titanium compound (1), on a mass basis. When this rate is less than 0.05, there is a possibility that the adhesion with a coating film after applying coatings could be degraded and even if this rate exceeds 0.3, the organic phosphonic acid compound exists just only excessively and does not have an effect of enhancing the adhesion, and therefore there is a possibility of being relatively expensive. More preferably, the lower limit is 0.1 and the upper limit is 0.15.

[0064] Preferably, the coat obtained by the nonchromate metallic surface-treating method contains the tannin (3) with carbon atom within a range having a lower limit of 0.5 and an upper limit of 3 relative to zirconium and/or titanium atom-of said water-soluble zirconium compound and/or said water-soluble titanium compound (1), on a mass basis. When this rate is less than 0.5, there is a possibility that the adhesion with a coating after applying coating could be degraded and when this rate exceeds 3, there is a possibility that the corrosion resistance after applying coating could be degraded. More preferably, the lower limit is 1.0 and the upper limit is 1.5.

[0065] The respective amounts of zirconium and titanium of the water-soluble zirconium compound and/or the water-soluble titanium compound (1) and the amount of phosphorus of the organic phosphonic acid compound (2) in the coat obtained by the nonchromate metallic surface-treating method can be measured by a X-ray fluorescence spectrometer, and the amount of the tannin (3) can be determined from the amount of organic carbon measured by a carbon/moisture content phase analyzer.

[0066] Aluminum or aluminum alloy according to the present invention is obtained by the nonchromate metallic surface-treating method. Since thus obtained aluminum or aluminum alloy is excellent in the corrosion resistance and adhesion with a coating film after applying coatings, it can be suitably used for uses such as a case for beverages, an electric home appliance and construction materials.

[0067] The nonchromate metallic surface-treating agent of the present invention comprises a water-soluble zirconium compound and/or a water-soluble titanium compound (1), an organic phosphonic acid compound (2) and a tannin (3), wherein a content of zirconium and/or titanium of the water-soluble zirconium compound and/or the water-soluble titanium compound (1) is 40 to 1000 ppm on a mass basis, a content of the organic phosphonic acid compound (2) is 20 to 500 ppm on a mass basis, a content of the tannin (3) is 200 to 5000 ppm on a mass basis, and the nonchromate metallic surface-treating agent has a pH of 1.6 to 4.0. That is, since the nonchromate metallic surface-treating agent according to the present invention contains not only the water-soluble zirconium compound and/or the water-soluble titanium compound (1) but also the organic phosphonic acid compound (2) and the tannin (3), the corrosion resistance and adhesion with a coating film after applying coatings can be enhanced by using said nonchromate metallic surface-treating agent. Thereby, it is possible to provide the excellent corrosion resistance and adhesion with a coating film after applying coatings to metallic base materials such as aluminum or an aluminum alloy by treating the metallic base materials with the nonchromate metallic surface-treating agent and to suitably use the treated metallic base material for beverage can materials, an electric home appliance, and construction materials.

[0068] Since the nonchromate metallic surface-treating agent, the nonchromate metallic surface-treating method, and aluminum or an aluminum alloy of the present invention comprise the constitutions described above, they can obtain the corrosion resistance and adhesion with a coating film equal to a chromium phosphate surface-treating agent. Thereby, they can be suitably adopted in a wide range of uses of aluminum materials for construction materials, an electric home appliance, fin materials, car evaporators, beverage can materials and the like, particularly uses for an electric home appliance, construction materials, and materials of beverage can cover.

EXAMPLES

[0069] Hereafter, although the present invention will be described more specifically with reference to examples, the present invention is not limited to these examples. Further, in the examples, term "part" means "mass part" unless otherwise specified.

[0070] (Preparation of Nonchromate Metallic Surface-Treating Agent)

Example 1

[0071] 9993 parts of ion-exchanged water was charged into the vessel equipped with an agitation apparatus. "Fluorozirconic acid" (2.3 parts: containing 17.6% of Zr) manufactured by Nippon Light Metal Co., Ltd. was added gradually thereto while agitating at room temperature. While further agitating, 0.7 part of "1-hydroxyethylidene-1,1-diphosphonic acid" manufactured by Morita Chemical Industries Co., Ltd. was added gradually. Next, 4 parts of "Tannic Acid Essence A" (nonvolatile matter 50%) manufactured by Dainippon Pharmaceutical Co., Ltd. was added gradually while agitating. Subsequently, under agitation, hydrofluoric acid was compounded in such a manner that the concentration of free fluorine was 12 ppm to this treating agent and then ammonia was added to adjust pH of the treating agent to 2.6. The agitation was continued for 10 minutes to obtain a slightly brown aqueous solution which contains fluorozirconic acid with zirconium of 40 ppm, 1-hydroxyethylidene-1,1-dip- hosphonic acid with phosphorus of 20 ppm, and tannin of 200 ppm.

Examples 2 to 12, Comparative Examples 1 to 4

[0072] The nonchromate metallic surface-treating agents of Examples 2 to 12 and Comparative Examples 1 to 4 were prepared in the same manner as Example 1 with the composition shown in Tables 1 and 2.

Example 13

[0073] Ion-exchanged water (9989.1 parts) was charged into the vessel equipped with an agitation apparatus. "Fluorotitanic acid" (1.5 parts: containing 29.3% of Ti) manufactured by Morita Chemical Industries Co., Ltd. was added gradually while agitating at room temperature. While further agitating, 1.4 part of "1-hydroxyethylidene-1,1-diphosphonic acid" manufactured by Morita Chemical Industries Co., Ltd. was added gradually. Next, 8 parts of "Tannic Acid Essence A" (nonvolatile matter 50%) manufactured by Dainippon Pharmaceutical Co., Ltd. was added gradually while agitating. Subsequently, under agitation, hydrofluoric acid was compounded in such a manner that the concentration of free fluorine was 12 ppm to this treating agent and then ammonia was added to adjust pH of the treating agent to 2.6. The agitation was continued for 10 minutes to obtain a slightly brown aqueous solution which contains fluorotitanic acid with titanium of 45 ppm, 1-hydroxyethylidene-1,1-dipho- sphonic acid with phosphorus of 40 ppm, and tannin of 400 ppm.

Examples 14 to 21, Comparative Examples 5 to 8

[0074] The nonchromate metallic surface-treating agents of Examples 14 to 21 and Comparative Examples 5 to 8 were prepared in the same manner as Example 13 with the compositions shown in Tables 1 and 2.

Example 22

[0075] Ion-exchanged water (9987.9 parts) was charged into the vessel equipped with an agitation apparatus. Fluorozirconic acid (1.7 parts) and in succession 1.0 parts of fluorotitanic acid were added gradually to the ion-exchanged water while agitating at room temperature. While further agitating, 1.4 parts of 1-hydroxyethylidene-1,1-diphosphonic acid was added gradually. Next, 8 parts of "Tannic Acid Essence A" (nonvolatile matter 50%) manufactured by Dainippon Pharmaceutical Co., Ltd. was added gradually while agitating. Subsequently, under agitation, hydrofluoric acid was compounded in such a manner that the concentration of free fluorine was 12 ppm to this treating agent and then ammonia was added to adjust pH of the treating agent to 2.6. The agitation was continued for 10 minutes to obtain a slightly brown aqueous solution which contains fluorozirconic acid with zirconium of 30 ppm, fluorotitanic acid with titanium of 30 ppm, 1-hydroxyethylidene-1,1-diphosphonic acid with phosphorus of 40 ppm, and tannin of 400 ppm.

Examples 23 to 25

[0076] The nonchromate metallic surface-treating agents of Examples 23 to 25 were prepared in the same manner as Example 22 with the compositions shown in Table 1.

Examples 26 to 28, Comparative Examples 9 and 10

[0077] The aqueous solution prepared in Example 4 (containing fluorozirconic acid with zirconium of 200 ppm, 1-hydroxyethylidene-1,1-di- phosphonic acid with phosphorus of 120 ppm, and tannin of 1400 ppm) was adjusted to pH of the range of 1.4 to 5 using nitric acid or ammonia to obtain the nonchromate metallic surface-treating agents of Examples 26 to 28 (Example 26: pH=1.6, Example 27: pH=3.0, Example 28: pH=4.0).

[0078] The nonchromate metallic surface-treating agents of Comparative Examples 9 and 10 were obtained in the same manner (Comparative Example 9: pH=1.4, Comparative Example 10: pH=5.0)

[0079] (Preparation of Chemical Conversion Treatment Plate)

[0080] Aluminum alloy 5182 plate materials were degreased (treated at 65.degree. C. for 3 seconds) using a 1% dilute solution of "Surf Cleaner 360" manufactured by Nippon Paint Co., Ltd., washed with water, and in succession cleaned using a 1% dilute solution of sulfuric acid (treated at 50.degree. C. for 3 seconds) and then washed with water. The resulting aluminum materials were treated at 58.degree. C. for 5 seconds with the nonchromate metallic surface-treating agent of the examples and comparative examples using a spraying apparatus, and dried at a material temperature of 80.degree. C. for 30 seconds to obtain surface treated metal plates.

Comparative Examples 11 to 13

[0081] Chemical conversion coats were formed under the same conditions of cleaning and spray treatment as mentioned above except that "Alsurf 4130" (Comparative Example 11: zirconium phosphate treating agent) manufactured by Nippon Paint Co., Ltd., "Alsurf 402" (Comparative Example 12: zirconium treating agent (not containing phosphoric acid compounds)) manufactured by Nippon Paint Co., Ltd., and "Alsurf 401/45" (Comparative Example 13: chromium phosphate treating agent) manufactured by Nippon Paint Co., Ltd. Were used as treating agent.

[0082] (Measurement of Coat Mass)

[0083] Masses of zirconium, titanium, phosphorus and chromium of the dried coats obtained through examples and comparative examples were measured by using X-ray fluorescence spectrometer "XRF-1700" manufactured by Shimadzu Corp. With respect to masses of the tannin of the coats, the mass of carbon atoms derived from tannin were determined by using a carbon/moisture content phase analyzer "RC 412" by LECO Corp. (USA). And, the masses of carbon atoms derived from tannin were determined with the following method.

[0084] Method of Determining Mass of Carbon Atom Derived from Tannin

[0085] (1) First, there was prepared a coat comprising only a water-soluble zirconium compound and/or a water-soluble titanium compound and an organic phosphonic acid compound. The masses of carbon and phosphorus derived from the organic phosphonic acid compound were measured and the mass ratio of carbon and phosphorus derived from the organic phosphonic acid compound was determined to form a linear equation.

[0086] (2) Next, there was prepared a coat comprising a water-soluble zirconium compound and/or a water-soluble titanium compound, an organic phosphonic acid compound and tannin. The masses of carbon and phosphorus of the coat were measured.

[0087] (3) From the linear equation obtained in the step (1), the mass of carbon derived from the organic phosphonic acid compound was determined based on the mass of phosphorus obtained in the step (2).

[0088] (4) From a difference between the mass of carbon obtained in the step (2) (measured value) and the mass of phosphorus obtained in the step (3) (calculated value), the mass of carbon derived from tannin was determined.

[0089] The mass of zirconium in the zirconium compound, which was obtained through the measurements, was represented as Zr, the mass of titanium in the titanium compound was represented as Ti, the mass of phosphorus derived from the organic phosphonic acid compound was represented as P, and the mass of carbon atom derived from tannin was represented as C, and the respective measurements were shown in Tables 1 and 2. Further the ratios, that is, the sum of Zr and Ti vs. P and the sum of Zr and Ti vs. C, were shown in the tables.

1 TABLE 1 Composition of nonchromate metallic surface- treating agent (ppm) Organic phosphonic Ratio Inorganic acid Tannic acid of respective components components components pH of metallic Coat coat masses (1) (2)* (3)** surface-treating mass (mg/m.sup.2) Zr.Ti Zr.Ti Zr Ti P1 P2 T1 T2 T3 agent Zr Ti P C vs. P vs. P Examples 1 40 -- 20 -- 200 -- -- 2.6 4 -- 0.3 3 1:0.075 1:0.75 2 40 -- 40 -- 400 -- -- 2.6 4 -- 0.6 6 1:0.15 1:1.5 3 200 -- 30 -- 300 -- -- 2.6 10 -- 0.5 5 1:0.05 1:0.5 4 200 -- 120 -- 1400 -- -- 2.6 10 -- 1.5 15 1:0.15 1:1.5 5 200 -- -- 180 1400 -- -- 2.6 10 -- 1.5 15 1:0.15 1:1.5 6 200 -- 120 -- -- 1400 -- 2.6 10 -- 1.5 15 1:0.15 1:1.5 7 200 -- 120 -- -- -- 1400 2.6 10 -- 1.5 15 1:0.15 1:1.5 8 200 -- 270 -- 4000 -- -- 2.6 10 -- 3 30 1:0.3 1:3 9 500 -- 100 -- 1200 -- -- 2.6 20 -- 1 10 1:0.05 1:0.5 10 550 -- 290 -- 3500 -- -- 2.6 20 -- 3 30 1:0.15 1:1.5 11 920 -- 160 -- 1600 -- -- 2.6 30 -- 1.5 15 1:0.05 1:0.5 12 980 -- 440 -- 5000 -- -- 2.6 30 -- 4.5 45 1:0.15 1:1.5 13 -- 45 40 -- 400 -- -- 2.6 -- 4 0.6 6 1:0.15 1:1.5 14 -- 220 30 -- 300 -- -- 2.6 -- 10 0.6 6 1:0.15 1:0.5 15 -- 220 120 -- 1400 -- -- 2.6 -- 10 1.5 15 1:0.15 1:1.5 16 -- 220 -- 180 1400 -- -- 2.6 -- 10 1.5 15 1:0.15 1:1.5 17 -- 220 120 -- -- 1400 -- 2.6 -- 10 1.5 15 1:0.15 1:1.5 18 -- 220 120 -- -- -- 1400 2.6 -- 10 1.5 15 1:0.15 1:1.5 19 -- 220 270 -- 3000 -- -- 2.6 -- 10 3 30 1:0.3 1:3 20 -- 580 290 -- 3000 -- -- 2.6 -- 20 3 30 1:0.15 1:1.5 21 -- 1000 440 -- 5000 -- -- 2.6 -- 30 4.5 45 1:0.15 1:1.5 22 30 30 40 -- 400 -- -- 2.6 2 2 0.6 6 1:0.15 1:1.5 23 110 120 120 -- 1400 -- -- 2.6 5 5 1.5 15 1:0.15 1:1.5 24 220 230 290 -- 3000 -- -- 2.6 10 10 3 30 1:0.15 1:1.5 25 490 500 440 -- 5000 -- -- 2.6 15 15 4.5 45 1:0.15 1:1.5 26 200 -- 120 -- 1400 -- -- 1.6 4 -- 0.6 8 1:0.15 1:2 27 200 -- 120 -- 1400 -- -- 3.0 7 -- 0.9 12 1:0.13 1:1.7 28 200 -- 120 -- 1400 -- -- 4.0 4 -- 0.6 10 1:0.15 1:2.5 *P1: 1-hydroxyethylidene-1,1-diphosphonic acid P2: 2-phosphobutanone-1,2,4-tricarboxylic acid **T1: Tannic Acid Essence A T2: B Tannic Acid T3: Hi Tannic Acid

[0090]

2 TABLE 2 Compositions of nonchromate metallic surface- treating agent (ppm) Organic phosphonic Ratio Inorganic acid Tannic acid of respective components components components pH of metallic Coat coat masses (1) (2)* (3)** surface-treating mass (mg/m.sup.2) Zr--Ti Zr--Ti Zr Ti P1 P2 T1 T2 T3 agent Zr Ti P C vs. P vs. C Comparative 1 20 -- 20 -- 200 -- -- 2.6 2 -- 0.3 3 10.15 1:1.5 examples 2 40 -- 10 -- 200 -- -- 2.6 4 -- 0.12 3 1:0.03 1:0.75 3 40 -- 40 -- 100 -- -- 2.6 4 -- 0.6 1.2 1:0.15 1:0.3 4 1200 -- 600 -- 6500 `3 -- 2.6 36 -- 5.4 54 1:0.15 1:1.5 5 -- 20 20 -- 200 -- -- 2.6 -- 2 0.3 3 1:0.15 1:1.5 6 -- 45 10 -- 200 -- -- 2.6 -- 4 0.12 3 1:0.03 1:0.75 7 -- 45 40 -- 100 -- -- 2.6 -- 4 0.6 1.2 1:0.15 1:0.3 8 -- 1200 560 -- 6000 -- -- 2.6 -- 32 4.8 48 1:0.15 1:1.5 9 200 -- 120 -- 1400 -- -- 1.4 2 -- 0.2 6 1:0.1 1:3 10 200 -- 120 -- 1400 -- -- 5.0 1 -- 0.1 6 1:0.1 1:6 11 ALSURF4130 10 -- 4 0 1:0.4 -- 12 ALSURF402 10 -- 0 0 -- -- 13 ALSURF401/45 Cr:20 10 0 1:0.5 -- *P1: 1-hydroxyethylidene-1,1-diphosphonic acid P2: 2-phosphobutanone-1,2,4-tricarboxylic acid **T1: Tannic acid Essence A T2: B Tannic Acid T3: Hi Tannic Acid

[0091] Preparation of Coated Plate 1

[0092] Water-borne epoxy-based clear coating "Canliner 100" (nonvolatile matter 28%) manufactured by Nippon Paint Co., Ltd. was applied to the resulting chemical conversion treatment plates so as to form a coat of 25 g/m.sup.2 on a wet mass basis per one surface using a reverse roll coater and this coat was baked at a material temperature of 260.degree. C. for 30 seconds using a conveyer type oven to obtain a coated aluminum material having a coat with the mass of 7 g/m.sup.2 after drying.

[0093] Preparation of Coated Plate 2

[0094] Solvent-borne polyester-based coating "Flekicoat #5000 White" (nonvolatile matter 50%) manufactured by Nippon Fine Coatings Inc., Ltd. was applied to the resulting chemical conversion treatment plates so as to form a coat of 15 g/m.sup.2 on a wet mass basis per one surface using a reverse roll coater and this coat was baked at a material temperature of 230.degree. C. for 60 seconds using a conveyer type oven to obtain a coated aluminum material having a coat with the mass of 7.5 g/m.sup.2 after drying.

[0095] (Evaluation Method)

[0096] The following evaluations were carried out and the results are shown in Tables 3 and 4.

[0097] 1. Stability of Nonchromate Metallic Surface-Treating Agent

[0098] The metallic surface-treating agents prepared in the manners were stored at 40.degree. C. for 30 days, and the appearances of the treating agents were visually tested. In Tables 3 and 4, to the samples which did not exhibit abnormal conditions such as occurrences of a whitish portion, precipitations and coagulating substances and had better appearances, there were put an expression by".smallcircle.", and to the samples which caused abnormal conditions, there were put descriptions of the content of abnormal conditions.

[0099] 2. Coat appearance

[0100] The surfaces of the chemical conversion treatment plates obtained in the manners were visually tested. In Tables 3 and 4, to the samples which did not exhibit abnormal conditions such as occurrences of cissing, unevenness and significant tarnish and had better appearances, there were put an expression by ".smallcircle.", and to the samples which caused abnormal conditions, there were put descriptions of the content of abnormal conditions.

[0101] 3. Adhesion Strength

[0102] Respective coated surfaces of the two same coated plates were mutually bonded by using a hot-melt polyamide film "Diamide Film #7000" manufactured by Daicel Chemical Industries, Co., Ltd. Bonding was performed by fixing two plates to each other by applying pressure at 200.degree. C. and at a pressure of 7 kg/cm.sup.2 for 1 minute with a hot press tester. The resulting bonded plate was cut out in width of 5 mm, and peeled off at a speed of 200 mm/min with a tensilon tester and a force applied then was measured (unit: kgf/5 mm) (Polyester-based coatings cannot be bonded in such a bonding-way and therefore cannot be tested.).

[0103] It was taken as an accepted level to exhibit the value which was equal to or higher than that of the coated plate treated with a chromium phosphate treating agent.

[0104] 4. Adhesion After Water Resistance Test

[0105] The coated aluminum plates were immersed for 60 minutes in boiled water of 100.degree. C. Immediately after the coated aluminum plates were removed out of the boiled water, 100 of cross-hatch were provided with distances of 1 mm, and tape-peeling test were performed with cellophane tapes and the number of peeling were counted. It was taken as an accepted level that there were no peeling portions.

[0106] 5. Corrosion Resistance

[0107] The coated aluminum plates were processed to the cups having the configuration illustrated in FIG. 1 so that the coated surface of the aluminum plates became convex. The resulting cups were immerged in the mixed aqueous solution of 2% citric acid solution and 2% salt water, being kept at 50.degree. C., for 72 hours, and after taking it out, states of corrosion of the respective portions, that is, a plane portion 1, an edge portion 2 and a side portion 3, which are shown in FIG. 1, were rated on a scale of 5 points according the following criteria and the average points of the respective portions were determined.

[0108] 5 points: there was no corrosion.

[0109] 4 points: there was little corrosion (side portion: corrosion portions of 0.5 mm in diameter were 10 points or less, edge portion: corrosion portions of 0.5 mm in diameter were 5 points or less).

[0110] 3 points: there was corrosion (side portion: corrosion portions of 1 mm in diameter were 20 points or less, edge portion: corrosion portions of 1 mm in diameter were 10 points or less)

[0111] 2 points: there was corrosion (side portion: corrosion portions of 3 mm in diameter were-20 points or less, edge portion: corrosion portions of 3 mm in diameter were 10 points or less).

[0112] 1 point: there was corrosion wholly (more than halves of the side portion, and the edge portion were corroded).

[0113] It was taken as an accepted level that an average of the rating points exhibits the value which was equal to or higher than that of the coated aluminum plate treated with a chromium phosphate treating agent.

3 TABLE 3 Evaluation of coating material Solvent-borne Water-borne epoxy-based coating polyester-based coating Adhesion Adhesion Stability of Adhesion after Adhesion after surface-treating Coat Adhesion water resistance Corrosion water resistance Corrosion agent appearance strength test resistance test resistance Examples 1 .largecircle. .largecircle. 1.3 100/100 3.3 100/100 4.3 2 .largecircle. .largecircle. 1.6 100/100 3.3 100/100 4.3 3 .largecircle. .largecircle. 1.9 100/100 4.0 100/100 4.7 4 .largecircle. .largecircle. 2.0 100/100 4.3 100/100 5.0 5 .largecircle. .largecircle. 2.1 100/100 4.3 100/100 4.7 6 .largecircle. .largecircle. 2.2 100/100 4.3 100/100 4.7 7 .largecircle. .largecircle. 2.1 100/100 4.3 100/100 5.0 8 .largecircle. .largecircle. 2.1 100/100 4.3 100/100 4.7 9 .largecircle. .largecircle. 1.7 100/100 4.3 100/100 4.7 10 .largecircle. .largecircle. 1.9 100/100 4.0 100/100 4.7 11 .largecircle. .largecircle. 1.3 100/100 4.3 100/100 4.7 12 .largecircle. .largecircle. 1.2 100/100 4.0 100/100 4.3 13 .largecircle. .largecircle. 1.6 100/100 3.3 100/100 4.3 14 .largecircle. .largecircle. 1.4 100/100 4.0 100/100 4.7 15 .largecircle. .largecircle. 1.8 100/100 4.0 100/100 4.7 16 .largecircle. .largecircle. 2.2 100/100 4.0 100/100 4.7 17 .largecircle. .largecircle. 2.2 100/100 4.0 100/100 4.7 18 .largecircle. .largecircle. 2.3 100/100 4.0 100/100 4.7 19 .largecircle. .largecircle. 2.0 100/100 4.0 100/100 4.7 20 .largecircle. .largecircle. 1.6 100/100 4.0 100/100 4.3 21 .largecircle. .largecircle. 1.2 100/100 4.0 100/100 4.3 22 .largecircle. .largecircle. 1.4 100/100 3.3 100/100 4.3 23 .largecircle. .largecircle. 2.3 100/100 4.0 100/100 4.3 23 .largecircle. .largecircle. 2.3 100/100 4.0 100/100 4.7 24 .largecircle. .largecircle. 1.6 100/100 4.0 100/100 4.3 25 .largecircle. .largecircle. 1.2 100/100 4.0 100/100 4.3 26 .largecircle. .largecircle. 1.4 100/100 3.3 100/100 4.3 27 .largecircle. .largecircle. 1.9 100/100 4.0 100/100 4.7 28 .largecircle. .largecircle. 1.3 100/100 3.3 100/100 4.3

[0114]

4 TABLE 4 Evaluation of coating material Solvent-borne Water-borne epoxy-based coating polyester-based coating Stability of Adhesion Adhesion surface- Adhesion after Adhesion after treating Coat Adhesion water resistance Corrosion water resistance Corrosion agent appearance strength test resistance test resistance Comparative 1 .largecircle. .largecircle. 1.1 100/100 3.0 88/100 3.7 examples 2 .largecircle. .largecircle. 1.2 100/100 3.3 90/100 4.0 3 .largecircle. .largecircle. 1.1 100/100 3.3 93/100 4.0 4 .largecircle. .largecircle. 0.9 100/100 3.7 90/100 4.3 5 .largecircle. .largecircle. 1.3 100/100 2.7 81/100 3.3 6 .largecircle. .largecircle. 1.3 100/100 3.3 83/100 4.3 7 .largecircle. .largecircle. 1.4 100/100 3.0 86/100 4.0 8 .largecircle. .largecircle. 1.2 100/100 3.3 92/100 4.3 9 .largecircle. Whitening 1.0 100/100 2.7 51/100 3.7 10 Whitish liquid Nib 0.8 100/100 2.3 33/100 3.0 11 .largecircle. .largecircle. 1.6 100/100 3.0 89/100 3.7 12 .largecircle. .largecircle. 1.3 100/100 3.7 11/100 4.0 13 .largecircle. .largecircle. 1.0 100/100 3.3 100/100 4.3

[0115] The nonchromate metallic surface-treating agents obtained through examples were high in the stability of liquid and the coats obtained with the treating agents were excellent in the adhesion and corrosion resistance. The coats obtained with the treating agents of Comparative Examples 1 to 8, in which the amounts of water-soluble zirconium compound and/or water-soluble titanium compound (1), organic phosphonic acid compound (2) and tannin (3) were out of the ranges of the present invention, were poor in the adhesion and corrosion resistance. Further, Comparative Examples 9 and 10, in which pHs ranged out of the ranges of the present invention, were not only low in the adhesion and corrosion resistance but also poor in the stability of treating agents, and the obtained coats whitened. Furthermore, the coating films obtained with the nonchromate metallic surface-treating agent of the examples exhibited the adhesion and corrosion resistance which is equal to or higher than that obtained with the treating agents of Comparative Examples 11 to 13.

Claims

1. A nonchromate metallic surface-treating agent comprising a water-soluble zirconium compound and/or a water-soluble titanium compound (1), an organic phosphonic acid compound (2) and a tannin (3), wherein a content of zirconium and/or titanium of said water-soluble zirconium compound and/or the water-soluble titanium compound (1) is 40 to 1000 ppm on a mass basis, a content of said organic phosphonic acid compound (2) is 20 to 500 ppm on a mass basis, a content of said tannin (3) is 200 to 5000 ppm on a mass basis, and a nonchromate metallic surface treating-agent has a pH of 1.6 to 4.0.

2. The nonchromate metallic surface-treating agent according to claim 1, wherein said organic phosphonic acid compound is a compound in which phosphorus atom forming a phosphonic group combines with carbon atom.

3. A nonchromate metallic surface-treating method comprising a step (A) of treating a substrate to be treated with the nonchromate metallic surface-treating agent according to claim 1 or 2.

4. The nonchromate metallic surface-treating method according to claim 3 comprising an acid cleaning step followed by said step (A).

5. The nonchromate metallic surface-treating method according to claim 3, wherein an alkaline cleaning step is performed and then an acid cleaning step is performed before said step (A) is performed.

6. Aluminum or an aluminum alloy having a coat obtained by the nonchromate metallic surface-treating method according to any of claims 3 to 5.

7. The aluminum or aluminum alloy according to claim 6, wherein said coat, after drying, contains said water-soluble zirconium compound and/or the water-soluble titanium compound (1) with zirconium and/or titanium atom of 4.0 to 30 mg/m.sup.2, by mass per one surface, and said organic phosphonic acid compound (2) with phosphorus atom of 0.05 to 0.3 and said tannin (3) with carbon atom of 0.5 to 3 relative to zirconium and/or titanium atom of said water-soluble zirconium compound and/or said water-soluble titanium compound (1), on a mass basis.