GB2249108A

GB2249108A - Phosphating compositions containing zinc ions and a polar or non-polar solvent

Info

Publication number: GB2249108A
Application number: GB9119726A
Authority: GB
Inventors: Ichiro Fukushima; Hirokuni Okada
Original assignee: Nippon Dacro Shamrock Co Ltd
Current assignee: Nippon Dacro Shamrock Co Ltd
Priority date: 1990-09-18
Filing date: 1991-09-16
Publication date: 1992-04-29
Anticipated expiration: 2011-09-16
Also published as: GB9119726D0; JPH04128383A; JP3062763B2; FR2666822B1; GB2249108B; FR2666822A1

Description

TITLE: Phosphatizing Compositions DESCRIPTION The invention relates to a phosphatizing composition and to metal articles treated therewith.

Japanese Laid-open Patent Application No. 52-107244 discloses a phosphatizing composition containing an aqueous medium. This comprises nitric acid and chlorine ions in an aqueous solution of acidic zinc phosphate so that the ratio of the nitrate ion and the chlorate ion (NO,)-/C103 is 0.2 to 4.5 and the ratio of the phosphate ion, the chlorate ion and the nitrate ion (PO4-3/ClO3-/NO3-) is 1:0.08 to 0.53:0.08 to 0.53.

However, in order to form a zinc phosphate film using a phosphatizing agent containing water as a medium, it is necessary sequentially to carry out a defatting step, a water rinsing step, a pure water rinsing step, a surface regulating step, a chemical treatment step, a water rinsing step, a pure water rinsing step and a drying step in this order, which steps per se are complicated.

Further, since in these steps a large amount of water is needed, the aforementioned method has the disadvantage of necessitating the provision of facilities for waste water, at substantial cost. Further, in the aforementioned phosphatizing composition the nitrate ion is employed as a catalyst and since the pH decreases as the concentration of the nitrate ion increases, the film cannot in practice be formed.

A composition for forming a zine phosphate film without water as a medium is known from Japanese Patent Publication No. 42-14051, which proposes a phosphatizing composition comprising an oxygen-containing organic solvent, a zinc compound and phosphoric acid. However, in this composition, the zine is hardly dissolved so that sludges and the like are formed in the film obtained so that industrialization is not practicable.

Japanese Patent Publication No. 57-49111 discloses a phosphatizing composition containing a chlorinated hydrocarbon medium. The composition may be used to phosphatize metal surfaces to enhance adhesiveness and moisture proof properties of coatings and so as to form a substantially water insoluble film of iron phosphate. However, while the iron phosphate film exhibits satisfactory performance in certain fields as pre-treatment to painting, it has the disadvantage that corrosion resistance is inferior to that of a zine phosphate film formed with a composition containing water as a medium, as employed in the automobile and electrical household goods industries.

The invention provides a phosphatizing composition comprising (a) 100 parts by weight of a mixed solvent which contains a polar organic solvent and water, the polar organic solvent having a boiling point of not less than 00C/760 mmHg, and constituting at least 50% by weight of the mixed solvent; (b) 0.001 to 7 parts by weight of a phosphoric acid; (c) 0,01 to 5 parts by weight of zinc ions; and (d) 0.01 to 5 parts by weight of a solubilizing agent.

The invention further provides a phosphatizing composition comprising (e) 100 parts by weight of a mixed solvent which contains a nonpolar organic solvent having a boiling point of not less than 00C/760 mmHg, not less than 0.5% by weight relative to the nonpolar solvent of a solubilizing solvent and not more than a homogeneous phase forming limit amount of water; (f) 0.0001 to 7 parts by weight of phosphoric acid; (g) 0.001 to 3.5 parts by weight of zine ion; and (h) 0.01 to 5 parts by weight of a solubilizing agent.

The invention also provides a metal article, the surface of which has been phosphatized by treatment with either of the compositions of the invention.

The phosphatizing composition of the invention is used to modify the surfaces of various metallic objects such as various irons, steels, galvanized iron, alloys of iron, aluminium or magnesium or other metallic materials.

A first phosphoric acid type composition according to the invention (hereinafter referred to as "the first composition") contains as essential components (a) a specific first mixed solvent, (b) phosphoric acid, (c) zinc ion and (d) a solubilizing agent in the respective specified amounts.

The first mixed solvent (a) in the first composition contains 100 parts by weight of a polar organic solvent having a boiling point of not less than 00C/760 mmHg and not more than 100 parts by weight of water. The polar organic solvent is preferably substantially water soluble. It may be a proton polar organic solvent such as an alcohol having not more than 14 carbon atoms, for example methanol, ethanol, isopropanol, 2-butoxyethanol, n-propanol, n-butanol, s-butanol, t-butanol or trifluoroethanol.It may alternatively be a non-proton polar organic solvent such as a ketone, for example, acetone, methyl ethyl ketone or diethyl ketone; a polyhydric alcohol ester having not more than 10 carbon atoms, for example diethyleneglycol monoacetal, glycerine monoacetal, glycerine diacetal, glycerine monobutryate, ethylene carbonate, propylene carbonate, ethyleneglycol monoformate ethyleneglycol diformate, ethylyeneglycol monoacetate or ethyleneglycol diacetate; a phosphate, for example trimethyl phosphate; a polyhydric alcohol ether having not more than 10 carbon atoms such as glycol ether, e.g. dimethoxy-ethane, diethoxy-ethane, 2-methoxy-ethanol or 2-ethoxy-ethanol, diethyleneglycol ether, e.g. diethyleneglycolmonomethyl ether, diethyleneglycoldimethyl ether or diethyleneglycolmonoethyl ether, glycerine ether, e.g. glycerinemethyl ether, glycerinetrimethyl ether or glycerinedimethyl ether, propylene ether, e.g. 1-methoxy-2-propanol or 1-ethoxy-2-propanol; a polyhydric alcohol monoester monoether having not more than 10 carbon atoms such as ethyleneglycol monoethylether acetate or ethyleneglycol monomethylether acetate; a cyclic ether, for example tetrahydrofuran or dioxane; a nitrogen compound such as acetonitrile or propionitrile; or diacetone alcohol.

Of these, methanol, ethanol, isopropanol and n-propanol are particularly preferred. The polar organic solvents may be used singly or in combination. The water in the first mixed solvent functions as an accelerator upon forming a film and is contained as water of crystallization. The mixing ratio of the water is not more than 100 parts by weight, preferably 30 to 70 parts by weight relative to 100 parts by weight of the polar organic solvent. If the mixing ratio exceeds 100 parts by weight, the solubility of the film becomes high so that a substantially uniform film is not obtained - The phosphoric acid (b) employed in the first composition of the invention may be any oxyacid or acidic oxide of phosphorus. The phosphoric acid may, for example, be orthophosphoric acid, pyrophosphoric acid, or phosphorus pentoxide. Orthophosphoric acid is most preferred.The mixing ratio of the phosphoric acid is 0.0001 to 7 parts by weight., preferably 0.01 to 2 parts by weight and most preferably 0.03 to 0.5 part by weight relative to 100 parts by weight of the first mixed solvent. If the mixing ratio of the phosphoric acid is less than 0.0001 part by weight, it may possibly be difficult stably and continuously to operate and supply the system for forming a desired phosphoric acid type film, whereas if the mixing ratio exceeds 7 parts by weight, the phosphoric acid may not be homogeneously dissolved in the first mixed solvent resulting in a turbid composition or in precipitation of crystallates.

The zinc ion (c) may be included in the first composition in the form of zinc oxide; an inorganic salt such as zinc carbonate, zinc nitrate, zinc chloride, zinc sulphate, zinc borate or zinc phosphate; or an organic salt such as zinc formate, zine acetate, zinc citrate, zinc tartrate, zinc oxalate or zinc trichloroacetate. Zinc oxide, zinc carbonate, zinc nitrate, zinc borate, zinc phosphate and zinc citrate are most preferred. A portion of the zinc ion may be replaced by nickel ion, calcium ion, manganese ion, sodium ion, mangnesium ion, copper ion or cobalt ion and the like. The mixing ratio of the zinc ion in the composition is 0.01 to 5 parts by weight, preferably 0.01 to 2.0 parts by weight relative to 100 parts by weight of the first mixed solvent.If the mixing ratio of zinc ion is less than 0.01 part by weight, the desired film is not obtained, whereas in excess of 5 parts by weight an excessive solubilizing agent etches metal so much that a substantially uniform film is not obtained. The mixing ratios of the respective ions replaceable as a portion of the zinc ion are preferably up to 2.5 parts by weight for nickel ion, up to 2.5 parts by weight for manganese ion, up to 2.0 parts by weight for calcium ion, up to 3.0 parts by weight for sodium ion, up to 2.0 parts by weight for magnesium ion, up to 2.0 parts by weight for copper ion and up to 2.0 parts by weight for cobalt ion.

The solubilizing agent (d) employed in the first composition of the invention is a component which can simultaneously dissolve both zinc and phosphoric acid into the solvent in the composition, and can promote etching of the metal surface to dissolve metal ions such as iron ion (Fe ) or zinc ion (Zn ) to form a zinc phosphate type crystalline film on the metal surface. The solubilizing agent may be a hydrogen halide such as hydrogen fluoride or hydrogen chloride; an inorganic acid such as nitric acid, hydrochloric acid, sulphuric acid or nitrous acid; or an organic acid such as trichloroaeetate, trifluoroacetate, picric acid, or nitroaniline. These may be used singly or in combination.The solubilizing agent may be used in an amount more than 2 moles relative to 1 mole of zinc ion in the composition if the solubilizing agent is a monobasic acid. If the solubilizing agent is a dibasic acid, it may be used in an amount more than 1 mole.

Hence, for example if zinc nitrate, zinc chloride and the like are added as the aforementioned zinc ion, a smaller amount of the solubilizing agent may be added.

The mixing ratio of the solubilizing agent in the first composition is 0.01 to 5 parts by weight, preferably 0.02 to 3 parts by weight relative to 100 ptts by weight of the first mixed solvent. If the mixing ratio is less than 0.01 part by weight, the solubilizing agent is not dissolved as zinc is combined with phosphoric acid, whereas if the mixing ratio is more than 5 parts, the pH of the system becomes so excessively low as to etch metal too much.

To prepare the first composition of the invention, the aforementioned components are simply mixed homogeneously at ambient temperature under stirring.

A second phosphatizing composition of the invention (hereinafter referred to as "the second composition") contains as essential components (e) a specific second mixed solvent, (f) phosphoric acid, (g) zinc ion and (h) a solubilizing agent in the respective specified amounts.

The second mixed solvent (e) contains 100 parts by weight of a nonpolar organic solvent having a boiling point of not less than 00C/760 mmHg, not less than 0.5 part by weight of a solubilizing solvent and not more than a homogeneous phase forming limit amount of water.

The nonpolar organic solvent is preferably substantially water insoluble. It may be a hydrocarbon solvent having a molecular weight of not more than 200 such as pentane, hexane, toluene or xylene; a halogenated hydrocarbon solvent such as methylene dichloride, trichloroethane, tetrachloroethylene or tric luorotrifluoroethane; an ether having a molecular weight of not more than 200 such as diethyl ether, diisopropyl ether or bis(2,2 -dichloroethyl)ether; an alcohol having not less than 5 carbon atoms such as n-pentanol or hexanol; an aliphatic ketone having not less than 5 carbon atoms; or an ester such as methyl formate or ethyl acetate. To enable the composition to be non-inflammable, methylene dichloride, trichloroethane and trichlorotrifluoroethane are most preferred. These may be used singly or in combination.

The solubilizing solvent employed in the second mixed solvent is a component which dissolved phosphoric acid, zinc, the solubilizing agent and water in the composition. The exemplified compounds described hereinbefore as the polar organic solvent may preferably be enumerated. Methanol, ethanol, isopropanol and n-propanol are most preferred. The solubilizing solvent may be used singly or in combination. The solubilizing solvent is present in an amount of not less than 0.5 part by weight, but preferably 5 to 50 parts by weight and most preferably 10 to 40 parts by weight, relative to 100 parts by weight of the nonpolar organic solvent.

If the solubilizing solvent is present in an amount of less than 0.5 part by weight, phoshoric acid, zinc, the solubilizing agent and water are not dissolved.

The water used in the second mixed solvent functions as a promoter for forming a film and is contained in the film as water of crystallization. The mixing ratio of water is not more than a homogeneous phase forming limit amount, preferably 1.0 part by weight to not more than the homogeneous phase forming limit amount. The homogeneous phase forming limit amount means an amount which forms non-turbid state in the composition itself upon mixing the essential components. If the mixing ratio of water exceeds the homogeneous phase forming limit amount, the solubilizing reaction is too strong to obtain a substantially uniform film.

Phosphoric acid (f) and the solubilizing agent (h) in the second composition may be enumerated by phosphoric acid (b) and the solubilizing agent (d) in the first composition. The mixing ratios of the phosphoric acid (f) and the solubilizing agent (h) in the second composition are the same as those in the first composition.

The zinc ion (g) employed in the second composition may be enumerated by the same aforementioned compounds in the first composition. The zinc ion may similarly be replaced by the other metal ions as set forth above.

The mixing ratio of the zine ion is 0.001 to 3.5 parts by weight, preferably 0.01 to 2.0 parts by weight relative to 100 parts by weight of the second mixed solvent. If the mixing ratio is less than 0.001 part by weight, a desired film is not obtained, whereas in excess of 3.5 parts by weight, it is not dissolved into the second mixed solvent.

To prepare the second composition, the respective components may be mixed homogeneously at ambient temperature under stirring.

To form a film employing the first and second compositions of the invention, immersing treatment, spraying or flow coating methods may be utilized.

For example, the known defatting and phosphatizing chemical treatment system commercially available under the tradename "COOLPHOSB' from NIPPON DACRO SHAMROCK CO., LTD. or a mono- or multi-bath type solvent defatting and rinsing device may be used. The composition of the invention is charged into the device and heated to a temperature between room temperature and the boiling point, preferably between a temperature of 10 C lower than the boiling point and the boiling point, to generate solvent vapour. The metal article to be treated is maintained in the solvent vapour zone preferably for 10 seconds to 1 minute, more preferably for 15 to 30 seconds, to preform defatting treatment.

The metal article is then immersed in the heated composition and maintained therein, preferably for 10 seconds to 30 minutes, more preferably for 1 to 20 minutes, to effect the chemical treatment. The chemically treated article is then washed in the boiling solvents to remove the unreacted materials followed by drying. The conditions for the chemical treatment are not particularly limited and may be freely decided depending on weight and thickness of the films formed by the phosphatizing composition and the concentration of each component.

The phosphatizing composition of the invention enables the formation of a durable zinc phosphate film of excellent corrosion resistance and adhesiveness. In addition, the phosphatizing composition according to the invention is a substantially non-aqueous system so that the zinc phosphate film is easily formed in a short time period on the article to be treated.

The following Examples illustrate the invention.

Example 1 89.7 parts by weight of ethanol, 10.3 parts by weight of water, 0.48 part by weight of zinc borate equivalent to 0.11 part by weight of Zn2+, 0.17 part by weight of pyrophosphoric acid and 1.1 parts by weight of 61 wt% nitric acid were mixed under stirring in a glass beaker at ambient temperature to prepare a homogeneous phosphatizing composition. The composition was then applied to a SPCC-SD steel test piece (0.8 x 70 x 150 mm) using the apparatus described with reference to the accompanying drawing.

The apparatus 1 comprises a glass reactor 2 which includes a solvent defatting zone A, a chemical treatment zone B and a drying zone C. The reactor 2 is provided with a heater 14 around the chemical treatment zone B. The heater 4 is controlled by a heat controller 5. A water jacket 6 is provided around the drying zone C. To avoid the colling of solvent vapour in the defatting zone A glass wool 3 surrounds the reactor 2 between the heater 4 and the cooling jacket 6. The phosphatizing composition was placed in the chemical treatment zone B and heated by the heater 4 to 14140C (boiling point).A test piece 7, movable upwards and downwards by a stainless steel wire attached to it, was placed in the solvent defatting zone A and solvent defatting treatment was performed for 20 seconds. The vapour evaporating from the composition was cooled by contact with the test piece 7 and the cooling jacket 6.

The solvent defatted test piece 7 was then immersed in the phosphatizing composition, heated to 1140C for 10 minutes. The test piece 7 was then taken out of the reactor 2 and washed using a solvent having solvent components similar to those of the composition.

Afterwards the test piece 7 was placed in the drying zone C and dried for 15 seconds to form a film of zine phosphate on the surface of the test piece.

A second test piece 7 was treated similarly.

On to the film formed onthe surface of the first test piece 7, "MELAMINE No.1, WHITE EXTERIOR USE" (manufactured by NIPPON OIL AND FATS CO., LTD. melamine alkyd type solvent synthetic resin paint, hereinafter abbreviated as "MELAMI NO.1") was baked at 1300C for 20 minutes to form a film thickness of 20 Sm. Likewise onto the film formed on the surface of the second test piece 7, "BELCOAT NO.1 1100 WHITE" (manufactured by NIPPON OIL AND FATS CO., LTD., acrylic solvent synthetic resin paint, hereinafter abbreviated "BELCOAT") was baked at 1500C for 20 minutes to form a film thickness of 20 to 30 Sm.

Saline spraying tests were conducted on each of the baked test pieces. In the test, firstly each baked test piece was diagonally crosscut with an NT cutter "A-300" so that the cutter reached the metal surface through the coating. Then, with respect to each coating on each of the baked test pieces, the test was conducted in accordance with JIS Z2371 for a predetermined time period. Afterwards, the test pieces were washed with water and left for 214 hours. An adhesive tape sold under the tradename "CELLOTAPE" (manufactured by NICHIBAN CO., LTD.) having a width of 18 mm was contacted and attached along the cross-cut lines on each test piece. The tape was peeled at 145 degrees and the maximum width at one side peeled from the cross cut portions of the coating was measured. The measured values are shown in Table 2.Saline spraying time periods in the tests were 48 hours for MELAMI No. 1 and 240 hours for BELCOAT.

Table 1 summarizes the nature of the composition and summarizes the test treatment conditions and results.

Examples 2 to 4 Example 1 was repeated, but using the phosphatizing compositions detailed in Table 1 and the test conditions shown in Table 2. The results of the saline spraying tests are also shown in Table 2.

Comparative Example 1 Using a phosphatizing composition containing 72.6 parts by weight of methylene dichloride, 25.5 parts by weight of methanol, 1.9 parts by weight of water, 0.5 part by weight of phosphoric acid, 3.1 parts by weight of N,N-dimethylformamide and 0.07 part by weight of dinitrotoluene, chemical treatment was carried out under the conditions shown in Table 2 and the test pieces were baked as described in Example 1. The baked test pieces were subjected to the saline spraying test, and the results are shown in Table 2.

Comparative Example 2 Test pieces were prepared without chemical treating and baked. The baked test pieces were subjected to the saline spraying test, with the results shown in Table 2.

Comparative Example 3 72.6 parts by weight of methylene dichloride, 25.5 parts by weight of methanol, 1.9 parts by weight of water, 0.5 part by weight of phosphoric acid, 0.1 part by weight of zinc oxide, 3.1 parts by weight of N,N-dimethylformamide and 0.07 part by weight of dinitrotoluene were mixed and stirred in a glass beaker at ambient temperature. However, the solubilizing agent was not included in the composition, so that zinc phosphate was formed and a homogeneous solution was not obtained. The composition was thus not suitable for chemically treating a metal test piece.

Examples 5 to 13 Phosphatizing compositions were prepared according to the formulations shown in Table 3. Using these compositions, test pieces were chemically treated under the conditions shown in Table 4 and baked to obtain baked test pieces as described in Example 1. The saline spraying test was carried out on each baked test piece.

The chemical treatment conditions, weight of films and measured results of the saline spraying tests are shown in Table 14.

T a b l e 1

Composition Ex.1 Ex.2 Ex.3 Ex.4 Methanol - 42.1 - Ethanol 89.7 - - Isopropanol - 52.6 - 68.6 t-Butanol - - 76.5 Ethylene Carbonate - - 21.9 Acetonitrile - - - 24.5 Water 10.3 5.3 1.6 6.9 Zinc Borate Zinc Nitrate Zinc Oxide Zinc Nitrate Zn2+ Compound 0.48 1.05 0.1 0.3 (0.11) (0.23) (0.01) (0.064) Nickel Carbonate Nickel Nitrate Ni2+ Compound - - 0.03 0.098 (0.015) (0.02) Sodium Dihydrogen Sodium Carbonate Na+ Compound - - Phosphate 0.098 0.01 (0.0016) (0.02) Orthophosphoric Acid Pyrophosphoric Acid 85% Phosphoric Acid Pyrophosphoric Acid 85% Phosphoric Acid 0.17 0.32 0.05 0.49 Solubilizing Agent 61% Acetic Acid 36% Chloric Acid Trichloroacetic 61% Nitric Acid 1.1 0.53 Acid 0.77 0.98 . The numerals are parts by weight.

. The numerals in the parentheses indicate quantities of ions.

T a b l e 2

Time for Temperature Weight of Film Saline Spraying Test Treatment under Treatment g/m MELAMI NO.1 BELCOAT Ex.1 10 Min. Boiling Point of 44 C 2.5 2mm or less 1mm or less Ex.2 18 Min. Boiling Point of 59 C 3.7 0mm 0mm Ex.3 20 Min. 43 ~ 48 C 1.5 3mm or less 2mm or less Ex.4 5 Min. Boiling Point of 42 C 2.3 1mm or less 1mm or less Comp.Ex.1 2 Min. Boiling Point of 39 C 0.2 8mm 8mm Comp.Ex.2 - - - 8mm or more 8mm or more * The temperature under treatment measured under atmospheric pressure.

* The time for treatment indicates duration of time for contacting with chemical treatment liquid, excluding the time period required before or after the treatment process.

T a b l e 3

Composition Ex.5 Ex.6 Ex.7 Ex.8 Ex.9 Ex.10 Ex.11 Ex.12 Ex.13 Methylene 100 - - 100 100 100 100 100 Chloride Ethyl Ether - - - - - - - - 74.2 Trichloroethane - 100 - - - - - - FURON 13 - - 100 - - - - - Methanol - 31.25 - 46 - - 7.8 - 21.1 Ethanol 23.3 - - - - - - 83 Ethylene - - - - 25 - - - Carbonate Acetonitrile - - - - - 54 - - t-Butanol - - 23.2 - - - - - Water 2.2 1.5 0.21 8 1.6 2.3 0.45 6.7 4.7 Zn2+ Compound Zinc Carbonate Zinc Oxide Zinc Oxide Zinc Carbonate Zinc Chloride Zinc Nitrate Zinc Oxide Zinc Carbonate Zinc Oxide 0.13 0.063 0.026 0.7 0.1 0.7 0.056 1.7 1.0 (0.076) (0.05) (0.02) (0.4) (0.05) (0.15) (0.044) (0.95) (0.1) Ni2+ Compound Nickel Carbonate - - - - Nickel Nitrate Nickel Carbonate Nickel Nickel Carbonate Carbonate 0.13 0.046 0.11 2 0.2 (0.062) (0.009) (0.05) (0.93) (0.11) Ca2+ Compound - Calcium Carbonate - - - - - - 0.03 (0.01) Mn2+ Compound - - Manganese - - - - - Carbonate 0.01 (0.048) Na+ Compound - - - Sodium Carbonate - Sodium Carbonate Sodium Nitrate Sodium Nitrate 0.15 0.3 0.44 4.8 (0.07) (0.14) (0.12) (1.3) Phosphoric Acid 0.11 0.38 0.03 1.5 0.21 0.6 0.28 0.42 0.3 Nitric Acid 0.39 0.38 1.2 2.5 - 0.77 0.11 1.7 0.9 Chloric Acid - - - - 0.53 - - - Others - - - - - - *1 *2 *1 Galvanized sheet ion was treated.

*2 Sodium nitrite was dissolved immediately before the iron plate was immersed in the treating liquid.

Numerals are parts by weight.

The numerals in the parenthese indicate quantities of ions.

T a b l e 4

Time for Temperature Weght of Film Saline Spraying Test Treatment under Treatment g/m MELAMI NO.1 BELCOAT Ex.5 15 Min. 55 ~ 60 C 4.5 1mm or less 1mm or less Ex.6 10 Min. Boiling Point of 73 C 3.0 3mm or less 1mm or less Ex.7 20 Min. 65 ~ 70 C 1.2 5mm or less 2mm or less Ex.8 8 Min. Boiling Point of 77 C 1.5 5mm or less 2mm or less Ex.9 5 Min. Boiling Point of 49 C 0.8 3mm or less 2mm or less Ex.10 3.5 Min. Boiling Point of 56 C 0.6 5mm or less 3mm or less Ex.11 2 Min. Boiling Point of 42 C 4.5 2mm or less 1mm or less Ex.12 8 Min. 15 ~ 25 C 1.2 2mm or less 2mm or less * The temperature under treatment measured under atmospheric pressure.

* The time for treatment indicates duration of time for contacting with chemical treatment liquid, excluding the time period required or after the treatment process.

* In Example 11, galvanized sheet ion was treatment.

Claims

CLAIMS:

1. A phosphatizing composition comprising (a) 100 parts by weight of a mixed solvent which contains a polar organic solvent and water, the polar organic solvent having a boiling point of not less than 0 C/760 mmHg and constituting at least 50% by weight of the mixed solvent; (b) 0.0001 to 7 parts by weight of a phosphoric acid; (c) 0.01 to 5 parts by weight of zinc ions; and (d) 0.01 to 5 parts by weight of a solubilizing agent.

2. A composition according to claim 1 further comprising ions of one or more of nickel, manganese, calcium, sodium, magnesium, copper and cobalt, and in which the total of the zinc ions and the said further ions is from 0.01 to 5 parts by weight per 100 parts by weight of the mixed solvent.

3. A metal article, the surface of which has been phosphatized by treatment with a composition according to claim 1 or claim 2.

14. A phosphatizing composition comprising (e) 100 parts by weight of a mixed solvent which contains a nonpolar organic solvent having a boiling point of not less than 00C/760 mmHg, not less than 0.5% by weight relative to the nonpolar organic solvent of a solubilizing solvent and not more than a homogeneous phase forming limit amount of water; (f) 0.0001 to 7 parts by weight of phosphoric acid; (g) 0.001 to 3.5 parts by weight of zinc ion; and (h) 0.01 to 5 parts by weight of a solubilizing agent.

5. A composition according to claim 4 further comprising ions of one or more of nickel, manganese, calcium, sodium, magnesium, copper and cobalt, and in which the total of the zinc ions and the said further ions is from 0.001 to 3.5 parts by weight per 100 parts by weight of the mixed solvent.

6. A metal article, the surface of which has been phosphatized by treatment with a composition according to claim 4 or claim 5.