DE3650659T2 - Process for phosphating metal surfaces - Google Patents

Abstract

Acidic, aqueous, substantially chlorate-free phosphate solution contains in S/L:- 0.1-1.5 Zn ions; 5-50 phosphate ions; 0.2-4 Mn ions; min 0.05 fluoride ions; less than 0.5 chloride ions; and at least one of the following phosphate accelerators:- 0.01-0.2 nitrite ions; 1-15 nitrate ions; 0.5-5 H2O2 (based on 100% H2O2); 0.05-2 m-nitrobenzene-sulphonate ions; 0.05-2 m-nitrobenzoate ions and 0.05-2 p-nitrophenol.

Description

The present invention relates to a method for phosphating a metal surface using an acidic aqueous phosphate solution. More particularly, it relates to a method for forming a phosphate layer which is particularly suitable for cataphoretic painting and is particularly applicable to metal surfaces which include both an iron-based surface and a zinc-based surface, such as a car body.

Japanese Laid-Open Patent Application No. 107784/1980 (published on August 19, 1980) discloses a method for treating a metal surface by dipping followed by spraying with an acidic aqueous phosphate solution containing 0.5 to 1.5 g/l of zinc ions, 5 to 30 g/l of phosphate ions and 0.01 to 0.2 g/l of nitrite ions and/or 0.05 to 2 g/l of m-nitrobenzenesulfonate ions. The method is reported to be capable of providing a phosphate layer effective for forming a coating by cationic resistance on complicated articles having many pocket parts such as automobile bodies.

Japanese Laid-Open Patent Application No. 145180/1980 (published on November 12, 1980) discloses a method for treating a metal surface by spraying an acidic aqueous phosphate solution containing 0.4 to 1.0 g/l of zinc ions, 5 to 40 g/l of phosphate ions, 2.0 to 5.0 g/l of chlorine ions and 0.01 to 0.2 g/l of nitrite ions. Furthermore, Japanese Patent Application Laid-Open No. 1512183/1980 (published on November 27, 1980) discloses an acidic aqueous phosphate solution containing 0.08 to 0.20 wt% of zinc ions, 0.8 to 3.0 wt% of phosphate ions, 0.05 to 0.35 wt% of chlorate ions, 0.001 to 0.10 wt% of nitrite ions and complex fluoride ions in an amount calculated by the formula 0.4 ≥ y ≥ 0.63 × - 0.042, where z is the concentration of zinc ions in wt% and y is the concentration of complex fluoride ions in wt%. These prior art methods are reported to be able to impart excellent adhesion and corrosion resistance to the coating by cataphoretic painting.

It should also be noted that British published patent application No. GB 2 148 951 A, as relevant, discloses, according to its abstract, that a protective coating can be formed on steel or other metal surfaces at low temperatures, for example below 40°C, by contact with a solution which is generally free of chlorate and chloride and which contains 0.5 to 1.5 parts hexafluorosilicate or tetrafluoroborate, 0.8 to 2.5 parts zinc, 10 to 25 parts phosphate, 1.5 to 10 parts nitrate, 0.1 to 1.2 parts nickel and 0.25 to 2 parts sodium nitrobenzenesulphonate. The composition may also contain 0 to 0.7 parts manganese.

However, a recent development in the automotive industry has been to use steel components plated with zinc or alloyed zinc on one surface only for car bodies, with the aim of further improving corrosion resistance after application of the dry paint. However, it has been recognized that when the above prior art compositions or processes are applied to such materials (i.e., to metal surfaces containing both an iron-based surface and a zinc-based surface), although a phosphate layer suitable as a substrate for coating by cataphoretic painting can be formed on the iron-based surface as desired, the phosphate layer formed on the zinc-based surface is considerably inferior to that formed on the iron-based surface.

A composition and method have been developed to solve the above-mentioned problems encountered on the zinc-based surfaces of components containing both an iron-based surface and a zinc-based surface. This is the invention disclosed in Japanese Laid-Open Publication No. 152472/1982 (published on September 20, 1982). This publication discloses immersing the metal surface in an acidic aqueous phosphate solution containing 0.5 to 1.5 g/l of zinc ions, 5 to 30 g/l of phosphate ions, 0.6 to 3 g/l of manganese ions, and a phosphating accelerator.

However, zinc phosphate treatment of galvanized steel often results in an unusual coating with white spots, each spot having a diameter of 1 mm to 2 mm. This is particularly true for electrogalvanized steel and especially for its dip treatment. These white spots cause craters in subsequent treatment, resulting in inferior coatings. The mechanism by which white spots are formed is believed to be as follows: in a first stage, many pits appear, at the peripheral parts of which the galvanized layer is gradually dissolved in the form of concentric circles by an excessive etching reaction. As the growth of each pit continues, zinc phosphate is precipitated in its central part. At the peripheral parts, however, the iron surface is exposed, forming a galvanic element with the zinc metal, so that the dissolution of the zinc progresses.

As a result, an excess of zinc phosphate crystals are precipitated, which accumulate as "snow" on the peripheral parts of the spots and which can be easily observed with the naked eye.

Unfortunately, no solution to this problem has yet been found to completely prevent the formation of such white spots.

It is the aim of the present invention to provide a method and a solution for phosphating, in particular as Substrate treatment in cataphoretic painting to form excellent phosphate layers capable of imparting excellent adhesion and corrosion resistance, in particular to cataphoretic painting coatings, on a variety of metal surfaces including an iron-based surface, a zinc-based surface and/or an aluminium-based surface, even when treated at low temperature and even on an article possibly having different metal surfaces and/or complicated shapes, such as a car body, and, above all, to provide a process which does not cause white spots, or at least no substantial white spots, on galvanised steel even when dipped in water.

We have found that phosphating compositions which are chlorate-free or at least substantially chlorate-free and which have a chloride ion concentration of less than 0.5 g/l give excellent phosphate coatings on iron, zinc and aluminium based surfaces without the formation of harmful white spots. It is important to the beneficial results of the present invention that the chloride ion concentration is kept consistently below 0.5 g/l, which means that not only the chloride ion itself but also the chlorate ion should not be added to the phosphating compositions since the chlorate ion is reduced to the chloride ion during use of the phosphating composition. These phosphating compositions form the subject of European Patent Application No. 86 306 622.1 (granted as EP 0 228 151) from which the present application is divided.

According to the invention there is provided a method for phosphating a metal surface comprising treating the metal surface with an acidic aqueous phosphate solution in which a concentration of chlorate ions of at most 0.2 g/l is established and maintained and which preferably does not contain chlorate ions, the chloride ion concentration being kept below 0.5 g/l, the solution comprising:

a) 0.1 to 1.5 g/l zinc ions,

b) 5 to 50 g/l phosphate ions,

c) from at least 0.2 to 4 g/l manganese ions,

d) at least 0.05 gil fluoride ions and

e) at least one of the following phosphating accelerators in the following concentrations:

(i) 0.01 to 0.2 g/l nitrite ions,

(ii) 1 to 10 g/l nitrate ions,

iii) 0.5 to 5 g/l hydrogen peroxide (based on 100% H₂O₂),

(iv) 0.05 to 2 g/l m-nitrobenzenesulfonate ions,

v) 0.05 to 2 g/l m-nitrobenzoate ions and

(vi) 0,05 to 2 g/l p-nitrophenol.

As noted above, the metal surface treated according to the present invention includes iron-based surfaces, zinc-based surfaces, aluminum-based surfaces, and surfaces based on their respective alloys. These metal surfaces can be treated either separately or in combination. The advantage of the present invention is most evident when the treatment is carried out on metal surfaces that include both an iron-based surface and a zinc-based surface, such as an automobile body. Examples of zinc-based surfaces are galvanized steel sheet, galvanized/heat-treated steel sheet, electrogalvanized steel sheet, electroplated zinc alloy plated steel sheet, electroplated complex galvanized steel sheet, etc.

If the content of zinc ions in the above acidic phosphate solution is less than about 0.1 g/l, a uniform phosphate layer will not be formed on the iron-based surfaces. If the content of zinc ions exceeds about 1.5 g/l, continuous formation of the phosphate layer will occur on both the iron-based surfaces and the zinc-based surfaces, resulting in accumulation of the layer, with the result that the layer shows a decrease in adhesion and becomes unsuitable as a substrate for cataphoretic painting.

If the content of phosphate ions in the above solution is less than about 5 g/l, an uneven phosphate layer may be formed. If the content of phosphate ions is greater than 50 g/l, no further benefits are obtained and it is therefore economically disadvantageous to use additional amounts of phosphate chemicals.

If the content of manganese ions is less than 0.2 g/l, the manganese content in the phosphate layer formed on zinc-based surfaces is very low; therefore, the adhesion between the substrate and the coating after cataphoretic coating becomes insufficient. If the manganese ions are present in an amount of more than 4 g/l, no further beneficial effects are obtained for the coating and the solution forms excessive precipitates, making it impossible to obtain a stable solution.

The manganese content in the phosphate layer formed on the metal substrates would be in the range of about 1 to about 20 weight percent, based on the weight of the layer, in order to obtain a phosphate layer that meets the quality requirements for cataphoretic painting. The phosphate layer containing the above-specified amount of manganese also forms part of the present invention.

The manganese content in the phosphate layer can be determined by conventional methods. For example, a phosphated specimen [S (m²); W₁ (g)] is immersed in an aqueous solution of 5 wt% chromic acid at 75°C for 5 minutes so that the layer is dissolved, and the weight of the specimen after treatment [W₂ (g)] is measured. The amount of the layer [Wc (g/m²)] is obtained by calculating the formula: [Wc (W₁ - W₂)/S]. Then, the amount of manganese dissolved in the aqueous chromic acid solution [A (1)] is determined by atomic absorption spectroscopy. [M (g/l)] to obtain the total amount of dissolved manganese [WM = A × M/s (g/m²)]. Using the amount thus obtained and the above amount of the layer, the manganese content can be calculated using the formula (WM/WC) × 100%.

If the amount of fluoride ions in the phosphating solution is less than 0.05 g/l, no micronization of the phosphate layer, no improvement in corrosion resistance after coating and no phosphating treatment at reduced temperature can be achieved. The fluoride ion can also be present in an amount of more than 3 g/l, but its use in such amounts does not give greater effects than are obtainable with the phosphating solutions of the invention. Preferably, the fluoride ion is contained in the form of a complex fluoride ion, e.g. a fluoroborate ion or a fluorosilicate ion, although the F- ion itself can also be used.

It has been found that when the chloride ion concentration in the phosphating solution reaches or exceeds 0.5 g/l (500 ppm), an excessive etching reaction occurs, causing undesirable white spots on zinc surfaces. Although the presence of chloride ions themselves may not directly cause the development of white spots, they are gradually converted into chloride ions and accumulate in this form in the bath liquid, causing white spots as mentioned above.

Furthermore, it was found that the combination of manganese and fluoride ions is effective for the preparation of suitable phosphating solutions that do not contain chloride ions.

In the phosphating solutions used in the process of the invention, the weight ratio of zinc ions to phosphate is preferably 1:(10 to 30). At this ratio, a uniform phosphate layer is obtained which meets all the quality requirements for cataphoretic painting. The weight ratio of zinc ions to manganese ions is preferably 1:(0.5 to 2). With this ratio it is possible to obtain economically a phosphate layer which contains the required amount of manganese and which exhibits all the beneficial effects obtained with the present invention.

The phosphating solutions used in the process of the invention desirably have a total acidity of 10 to 50 points, a free acidity of 0.3 to 2.0 points and an acid ratio of 10 to 50. When the total acidity is in the above range, the phosphate layer can be obtained economically, and when the free acidity is in the above range, the phosphate layer can be obtained uniformly without excessive etching of the metal surface. Adjustments of the solution to obtain and maintain the above points and ratios can be achieved using an alkali metal hydroxide or ammonium hydroxide as needed.

The sources of the components of the phosphating solutions used in the process of the invention include the following: for the zinc ions, one can use zinc oxide, zinc carbonate, zinc nitrate, etc.; for the phosphate ions, one can use phosphoric acid, zinc phosphate, zinc monohydrogen phosphate, zinc dihydrogen phosphate, manganese phosphate, manganese monohydrogen phosphate, manganese dihydrogen phosphate, etc.; for the manganese ions, one can use manganese carbonate, manganese nitrate, the above-mentioned manganese phosphate compounds, etc.; for the fluoride ions, one can use hydrofluoric acid, tetrafluoroboric acid, hexafluorosilicic acid, hexafluorotitanic acid and their metal salts (e.g. the zinc salt, nickel salt, etc.; however, the sodium salt is excluded since it does not give the desired effect); and as phosphating accelerators one can use sodium nitrite, ammonium nitrite, sodium m-nitrobenzenesulfonate, sodium m-nitrobenzoate, aqueous hydrogen peroxide, nitric acid, zinc nitrate, manganese nitrate, nickel nitrate, etc.

The phosphating solutions used in the process of the invention may further contain nickel ions as an optional ingredient. The content of nickel ions should be 0.1 to 4 g/l, preferably 0.3 to 2 g/l. When nickel ions are present together with manganese ions, the quality of the resulting phosphate layer is further improved, i.e. the adhesion and corrosion resistance of the coating obtained after cataphoretic coating are further improved. In phosphating solutions containing nickel ions, the weight ratio of zinc ions to the sum of manganese ions and nickel ions is desirably 1:(0.5 to 5.0), preferably 1:(0.8 to 2.5). The source of nickel ions may be, for example, nickel carbonate, nickel nitrate, nickel phosphate, etc.

The phosphate layer formed by the process of the present invention is a zinc phosphate type layer. Such layers formed on iron-based metal surfaces contain about 25 to about 40 weight percent zinc, about 3 to about 11 weight percent iron, about 1 to about 20 weight percent manganese, and 0 to about 4 weight percent nickel.

The process of the present invention for phosphating metal surfaces can be carried out using the phosphating solutions by spraying, dipping or a combination of these treatments. The spraying treatment can usually be carried out by spraying for 5 or more seconds to form a sufficient phosphate layer exhibiting the desired quality characteristics. The spraying treatment can conveniently be carried out using a cycle which first comprises a spraying treatment for about 5 to about 30 seconds, followed by a break in the treatment for about 5 to 30 seconds and then again a spraying treatment for at least 5 seconds, the total spraying treatment time being at least 40 seconds. This cycle can be carried out once, twice or three times.

In the process of the present invention, dipping is usually preferred over spraying. In order to form a sufficient phosphate layer exhibiting the desired quality characteristics, dipping is usually carried out for at least 15 seconds, preferably from about 30 to about 120 seconds. In addition, treatment may also be carried out first by dipping for at least 15 seconds and then by spraying for at least 2 seconds. Alternatively, treatment may also be carried out first by spraying for at least 5 seconds and then dipping for at least 15 seconds. The former combination of dipping first and then spraying is particularly advantageous for articles of complicated shape, such as a car body. For such articles, dipping is preferably carried out first for 30 to 90 seconds and then spraying for 5 to 45 seconds. In this process it is advantageous to carry out the spray treatment for as long as possible within the limitations of the car assembly line in order to remove the sludge that adheres to the object during the dip treatment stage.

In the present process, the treatment temperature may be 30 to 70°C, preferably 35 to 60°C. This temperature range is approximately 10 to 15°C lower than that used in the prior art processes. Treatment temperatures below 30°C should not be used because of an unacceptable increase in the time required to produce an acceptable coating. Conversely, if the treatment temperature is too high, the phosphating accelerator will decompose and excess precipitate will be formed, causing the equilibrium between the components in the solution to be disturbed and making it difficult to obtain satisfactory phosphate coatings.

For spray treatments, a suitable spray pressure is 0.6 to 2 kg/cm² overpressure.

As described above, a preferred type of treatment in the process of the present invention is a dip treatment or a combined treatment using first a dip treatment and then a spray treatment.

An advantageous method for treating metal surfaces using a series of pre-coating treatment processes followed by phosphating according to the method of the present invention is as follows:

A metal surface is first subjected to spraying and/or dipping with an alkaline degreasing agent at a temperature of 50 to 60°C for 2 minutes; then washing with tap water; spraying and/or dipping with a surface etching solution at room temperature for 10 to 30 seconds; dipping with the solution of the present invention at a temperature of about 30 to about 70°C for at least 15 seconds; and washing with tap water and then with deionized water in that order. Thereafter, it is desirable to post-treat with an acidified rinsing solution commonly used in the industry, such as a dilute chromate solution. This post-treatment is preferably carried out even when the present invention is carried out by spraying or by a combined treatment comprising spraying and subsequent dipping. By introducing this post-treatment, a phosphate layer can be obtained which gives a dry paint layer greater corrosion resistance.

When carrying out the dipping treatment or the dipping treatment followed by spraying treatment, which is the preferred treatment method of the present invention, it is advantageous to use an acidic aqueous phosphate solution of the present invention which comprises:

a') 0.5 to 1.5 g/l, preferably 0.7 to 1.2 g/l, zinc ions,

b') up to 30 g/l, preferably 10 to 20 g/l, phosphate ions,

c') 0.8 to 3 g/l, preferably 0.8 to 2 g/l, manganese ions,

d') at least 0.05 g/l, preferably 0.1 to 2 g/l, fluoride ions,

e') less than 0,5 g/l chloride ions and

f') a phosphating accelerator in an amount specified above

(hereinafter referred to as "immersion solution").

When the above dipping solution is used in the process of the invention on a metal surface, particularly a metal surface comprising both an iron-based surface and a zinc-based surface, a fine, uniform and dense phosphate layer is economically formed thereon which imparts excellent adhesion and corrosion resistance to coatings formed by cataphoretic painting and which is substantially free of white spots.

In the practice of the present invention, concentrated aqueous compositions are used to prepare the acidic aqueous phosphate solutions used in the process of the present invention. The acidic aqueous treating solutions are conveniently prepared by diluting an aqueous concentrate containing a number of the solution components in appropriate weight ratios and then adding additional components as needed to prepare the treating solutions.

The concentrates are advantageously prepared so that they contain zinc ions, phosphate ions, manganese ions, fluoride ions and optionally nickel ions in a weight ratio of 0.1 to 2 : 5 to 50 : 0.2 to 4 : at least 0.05 : 0.1 to 4. The concentrates preferably contain a weight ratio of the above components of 0.5 to 1.5 : 10 to 30 : 0.1 to 3 : 0.3 to 2.

The concentrates are preferably prepared to contain at least about 25 g/l, more preferably about 50 g/l to 130 g/l, zinc ions. However, care must be taken when forming the concentrates. For example, if manganese ions and complex fluoride ions are present in a concentrate together with sodium ions, a precipitate will form. In addition, it is not advisable to add a phosphating accelerator to the concentrate, as the accelerators tend to decompose and cause other problems.

As an example of a suitable concentrated aqueous composition, a concentrated composition is prepared comprising 3.0% by weight of zinc oxide, 1.8% by weight of nickel (II) carbonate, 48.2% by weight of 75% phosphoric acid, 10.0% by weight of manganese (II) nitrate hydrate (manganese content 20% by weight), 7.9% by weight of 40% hexafluorosilicic acid and 29.1% by weight of water. This concentrate is then diluted with water to 2.5% by volume and then a 20% aqueous solution of sodium nitrite is added to obtain an acid phosphating solution of the invention.

In order to better understand the invention, it will now be described in more detail in practical and preferred embodiments shown in the following examples and comparative examples for illustration. Of course, the present invention is not limited to these examples.

Examples 1 to 3 and comparative examples 1 to 3

(1) Metal to be treated galvanized steel sheet

(2) Acidic aqueous phosphate solution The compositions shown in Table 1 were used.

(3) Treatment methods:

The surfaces of the above metal were treated simultaneously according to the following procedures:

Degreasing, water washing, surface etching, phosphating, water washing, pure water washing, drying, painting.

(4) Treatment conditions:

(a) Degreasing:

Using an alkaline degreaser (“RIDOLINE SD200” manufactured by Nippon Paint Co., concentration 2 wt%), a spray treatment was carried out at 60ºC for 1 minute, followed by an immersion treatment for 2 minutes.

(b) Washing with water:

Washing was carried out using tap water for 15 seconds at room temperature.

(c) Surface etching:

Using a surface etchant ("FIXODINE 5N-5" manufactured by Nippon Paint Co., concentration 0.1 wt%), an immersion treatment was carried out at room temperature for 15 seconds.

(d) Phosphating:

Using the above acidic aqueous phosphate solution, immersion treatment was carried out at 52ºC for 120 seconds.

(e) Washing with water:

Washing was carried out using tap water for 15 seconds at room temperature.

(f) Washing with pure water:

Using deionized water, an immersion treatment was performed at room temperature for 15 seconds.

(g) Drying was carried out for 10 minutes with a hot air flow of 100ºC.

The appearance of each phosphated sheet thus obtained and the weight of the phosphate layer were determined.

(h) Painting:

A composition for cataphoretic painting ("POWER TOP U-30 Dark Grey", manufactured by Nippon Paint Co.) was applied to a layer thickness of 20 µm (voltage 180 V, current application time 3 minutes), and the surface was baked at 180ºC for 30 minutes. A number of all the resulting electrophoretic painted panels were used for the salt water spray test.

The remaining electrophoretic painted panels not tested were coated with an intermediate coat composition ("ORGA T0778 Grey" manufactured by Nippon Paint Co.) to a thickness of 30 µm and then with a top coat composition ("ORGA T0626 Margaret White" manufactured by Nippon Paint Co.) to a thickness of 40 µm, to obtain painted panels with a total of 3 coatings and 3 baking steps, which were then used for the adhesion test and the staining test.

(5) Test results:

The results are shown in Table 2. Each test procedure is given below.

(a) Salt water spray test (JIS-2-2871):

Cross-cuts were made on the electrophoretically painted sheet, which were then exposed to the light for 500 hours (zinc-plated steel sheet) or 1000 hours (cold-rolled steel sheet) was sprayed with 5% salt solution.

(b) Adhesion test:

The painted sheet was immersed in deionized water at 50ºC for 10 days; then it was provided with grids (100 squares each) made with a sharp knife at 1 mm intervals and 2 mm intervals respectively. Adhesive tape was applied to each surface of the thus treated sheet; then it was peeled off and the number of painted squares remaining on the painted sheet was counted.

(c) White spot test:

The presence of white spots was examined by visual observation.

0 ... no white spots; X ... white spots In addition, a scanning electron microscope image confirmed the presence of white spots from a phosphate layer on galvanized steel sheet. Table 1 Table 2 Table 2 (continued)

As can be seen from Table 2 above, when using solutions composed as in the examples according to the invention, the process produces highly commercially acceptable phosphate coatings, while when using solutions composed as in the comparative examples (and where the chloride ion concentration is greater than 0.5 g/l), commercially unsatisfactory coatings are produced.

It should be noted that although Example 1 contained a small amount of chlorate ions (0.2 g/l) which did not affect the results obtained using the fresh bath, it is not recommended to use the composition of Example 1 commercially since even such a small amount of chlorate in the bath will, with continued use of the bath, eventually lead to the reduction of sufficient chlorate ions so that the amount of chloride ions rises above 0.5 g/l.

The solution used in the process preferably contains no more than about 0.2 g/l of chloride ions. More preferably the solution contains no chlorate.

The present invention is advantageous for preventing white spots, especially on galvanized steel, especially when the phosphating treatment comprises a dipping treatment.

In an advantageous embodiment of the process, the solution contains at least about 1.05 g/l, in particular at least about 1.1 g/l, zinc ions, for example about 1.05 to about 1.5 g/l zinc ions, especially when the phosphating treatment comprises an immersion treatment.

In a further advantageous embodiment of the process, the solution used contains at least about 15 g/l phosphate ions, for example about 15 to about 50 g/l, in particular about 15 to about 30 g/l, phosphate ions.

In a further advantageous embodiment of the process, the solution used contains more than about 4.0 g/l, in particular more than about 5 g/l, nitrate ions. The solution can thus contain about 5 to about 15 g/l, in particular about 5 to about 10 g/l, nitrate ions.

In yet another advantageous embodiment of the process, the solution used contains more than about 0.3 g/l, in particular more than about 0.4 g/l, nickel ions. The solution can thus contain about 0.4 to about 4 g/l, in particular about 0.4 to about 2 g/l, nickel ions.

These advantageous embodiments are particularly advantageous to avoid white spots and to impart further advantageous properties to the phosphate surface.

When it is said here that a solution comprises certain components, in a preferred embodiment it consists essentially of these components.

However fluoride ions are provided, they are measured here in terms of F ions.

Claims (31)

1. A method for phosphating a metal surface, comprising treating the metal surface with an acidic aqueous phosphate solution having a concentration of chlorine ions of at most 0.2 g/l, which preferably does not contain chlorine ions, the chloride ion concentration being kept below 0.5 g/l, the solution comprising: a) 0.1 to 1.5 g/l zinc ions, b) 5 to 50 g/l phosphate ions, c) from at least 0.2 to 4 g/l manganese ions, (d) at least 0.05 g/l fluoride ions and e) at least one of the following phosphating accelerators in the following concentrations: (i) 0.01 to 0.2 g/l nitrite ions, (ii) 1 to 15 g/l nitrate ions, iii) 0.5 to 5 g/l hydrogen peroxide (based on 100% H₂O₂), (iv) 0.05 to 2 g/l m-nitrobenzenesulfonate ions, v) 0.05 to 2 g/l m-nitrobenzoate ions and (vi) 0,05 to 2 g/l p-nitrophenol, the metal surface after treatment being substantially free of white spots. 2. A process according to claim 1, wherein the solution comprises a little chloride ions and optionally a little chlorate ions. 3. Process according to claim 1 or 2, wherein the solution used comprises 0.5 to 1.4 g/l zinc ions. 4. Process according to claim 3, wherein the solution used comprises 0.7 to 1.2 g/l zinc ions. 5. Process according to one of the preceding claims, wherein the solution used comprises 5 to 30 g/l phosphate ions. 6. Process according to claim 5, wherein the solution used comprises at least 10 g/l phosphate ions. 7. Process according to claim 6, wherein the solution used comprises 10 to 20 g/l of phosphate ions. 8. Process according to one of claims 1 to 4, wherein the solution used comprises 15 to 50 g/l phosphate ions. 9. Process according to one of the preceding claims, wherein the solution used comprises 0.6 to 3 g/l manganese ions. 10. The method according to claim 9, wherein the solution used comprises at least 0.8 g/l manganese ions. 11. The method according to claim 10, wherein the solution used comprises 0.8 to 2 g/l manganese ions. 12. A process according to any one of the preceding claims, wherein the solution used comprises 0.1 to 3 g/l fluoride ions. 13. The method according to claim 12, wherein the solution used comprises 0.1 to 2 g/l fluoride ions. 14. Process according to one of the preceding claims, wherein the solution used comprises 1 to 10 g/l of nitrate ions. 15. A process according to any one of the preceding claims, wherein the solution used comprises one or more of the following accelerators in the following amounts: (i) 0,04 to 0,15 g/l nitrite ions, (ii) 2 to 8 g/l nitrate ions, iii) 1 to 1.5 g/l hydrogen peroxide (based on 100% H₂O₂) (iv) 0.1 to 1.5 g/l m-nitrobenzenesulfonate ions, v) 0.1 to 1.5 g/l m-nitrobenzoate ions and (vi) 0.1 to 1.5 g/l p-nitrophenol. 16. Method according to one of the preceding claims, wherein the solution used comprises: a) 0.7 to 1.2 g/l zinc ions, b) 10 to 20 g/l phosphate ions, c) 0.8 to 2 g/l manganese ions, and d) 0.1 to 2 g/l fluoride ions. 17. A process according to any one of the preceding claims, wherein the solution used comprises 0.4 to 4 g/l of nickel ions. 18. A method according to any preceding claim, wherein an article is treated having an iron-based surface, a zinc-based surface or an aluminium-based surface or a combination of such surfaces. 19. The method of claim 18, wherein the treated article has a surface comprising electrolytically galvanized steel. 20. A process according to any preceding claim, wherein the treatment is carried out at a temperature in the range of 30 to 70°C. 21. A process according to any preceding claim, wherein the chloride concentration is maintained below 0.5 g/l by discarding part of the solution when the chloride content approaches 0.5 g/l and treating the solution as required with one or several of the solution components which are essentially free of chloride ions. 22. The method of claim 21, wherein the coating weight after treatment of the metal surface is at least 2 g/m². 23. A method according to claim 21 or 22, wherein the metal surface after the treatment is substantially free of excess zinc phosphate precipitate. 24. A method according to any preceding claim, wherein at least the last step in the treatment is carried out by spraying. 25. A method according to any preceding claim, wherein at least one step in the treatment is carried out by immersion. 26. A method according to claim 24 and 25, wherein the treatment is carried out by immersion for at least 15 seconds and subsequent spraying for at least 2 seconds. 27. A metal surface phosphated by a process according to any one of the preceding claims. 28. The metal surface according to claim 27, wherein the phosphate film formed on the metal surface has a manganese content in the range of 1 to 20 wt.% based on the weight of the film. 29. A metal surface according to claim 27 or 28, wherein the phosphate film formed has a coating weight of at least 2 g/m2. 30. A method according to any one of claims 1 to 26, wherein the metal surface is rinsed and electroplated after the treatment. 31. The method of claim 30, wherein the metal surface is cationically electroplated.