RU2358035C2 - Procedure for forming thin corrosion inhibiting coating on metal surface - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: procedure consists in contacting metal surface at temperature not above 45°C and at value of pH less 3.5 with water acid phosphating solution or dispersion with ions of alkali metals containing composition of phosphorus containing acid and/or its derivatives similar to complex ethers and salts at total contents of all kinds of acids and all their derivatives similar to complex ethers and salts in total less, than 20 g/l per mole of base of orthophosphate; also contents of phosphorus containing compounds/ions is at least 50% of weight from all such compounds/ions; in addition, ion, chosen from group, consisting of at least one ion of alkali metal and ammonium ion and accelerant on base of guanidine at total amount of 0.01-5 g/l, free fluoride at amount of from 0.01 to 1 g/l or not containing free fluoride, also they do not contain other heavy metals different from those which will be etched off metallic surface, possibly, excluding addition of ions of Fe²⁺. Formed coating contains phosphorus not more, than 8 atomic %, while its weight is from 0.01 to 0.5 g/m².

EFFECT: procedure of phosphating is stable and suits well for industrial implementation for phosphating rolls, items and wires; said procedure is easier and cheaper in comparison with known procedures; further, phosphate coating has supreme exterior view and high corrosion resistance.

20 cl, 7 dwg, 10 tbl, 119 ex

Description

This invention relates to a method for coating the surface of a metal coil, part or wire with an aqueous acidic phosphating solution containing predominantly alkali metal ions and / or ammonium ions, as well as, in many cases, phosphate ions. It also relates to a phosphating solution, which is used in this method to obtain coatings that excellently inhibit corrosion on metal surfaces. In some examples, such a coating can be used for cold forming metal parts. Such solutions are called phosphating solutions with alkali metal ions or, if they are used on iron-enriched surfaces, glandular phosphating solutions.

This invention in particular relates to a coating, respectively a coating by chemical interaction, on aluminum, an aluminum alloy, an iron alloy like steel and stainless steel, a magnesium alloy, zinc or an zinc alloy, as well as a method, concentrate and solution for forming a phosphating coating on surfaces these metallic materials.

Such a coating solution is particularly suitable for generating pretreated coatings on the surfaces of substrates that will be coated in a second stage with at least one organic film, in particular at least one film similar to a thin layer of electrodeposit varnish, a paint layer , a silane enriched layer and / or an adhesive layer. Otherwise, the coating can be used for processing similar to passivation, without being coated with the next coating, similar to a layer of paint.

Methods for the production of coatings by phosphating with alkali metal ions, especially before varnishing, are described in relatively few cases compared to phosphating with zinc or phosphating with manganese, where there are a huge number of publications. Fresh phosphate solutions with alkali metal ions that have not yet been used usually show only a very low content of aluminum, iron and zinc, or even their actual absence. Fresh aqueous acidic phosphating solutions with alkali metal ions contain ions of at least one type of alkali metal ion and / or ammonium ion, as well as phosphate ions. Due to the etching effect of such acidic solutions on metal surfaces, the content of dissolved metal ions such as aluminum, iron and zinc, as well as traces of other components of the alloys of the etched metal materials, will increase as the phosphation process continues in the phosphating solution. As a rule, the main phases of phosphate coating with alkali metal ions are the corresponding phosphates, oxides and / or hydroxides of metals, which are components of the main metal material (s).

Phosphating solutions with alkali metal ions, respectively coatings, are called iron phosphating solutions, respectively coatings, if they are used on surfaces of iron alloys like steel. The same is true for aluminum and aluminum alloys, where such solutions, respectively coatings, are described as aluminum phosphating solutions, respectively coatings. Often the surfaces of very different metallic materials can be coated in the same phosphating bath with alkali metal ions simultaneously or one after the other, whereby the ions of various base metals / alloys will be collected in the bath. Such coatings are - unlike the coatings of the so-called zinc, zinc-manganese or manganese phosphate coatings, mainly or completely amorphous or exclusively fine-grained.

Alkaline metal phosphating processes are described in detail in Werner Rausch: The Phosphating of Metals, ASM International, Finishing Publications Ltd., Teddington, England 1990 (especially pages 94-100, 120-130), and are called " uncoated phosphating "or in other publications," amorphous phosphating ". The term "uncoated phosphating" is misleading since coatings will be generated, although such coatings will be significantly thinner than those created during, for example, zinc phosphating or zinc-manganese phosphating. Very thin coatings with phosphating with alkali metal ions are invisible, poorly visible or - if they are colored or gray - well visible; these coatings can only be visible due to staining caused by physical effects, coatings of this kind look gray and / or matte in appearance. The phosphating solution with alkali metal ions always always contains a certain amount of at least one alkali metal like sodium, potassium and / or ammonium. Phosphate coatings with alkali metal ions usually represent — unlike good and crystalline thickness coatings the so-called “forming phosphate coating” processes — more or less amorphous and usually do not show crystalline forms by scanning electron microscopy.

The phosphate coating with alkali metal ions mainly contains little, almost no or no manganese or zinc if they do not pretreat or treat surfaces enriched with manganese and / or zinc. They usually contain little, almost no or no chromium, cobalt, copper, nickel, tin and / or other heavy metals. Mostly, the phases generated and / or precipitated during glandular phosphating, which is carried out by contacting the iron-rich metal surfaces with a phosphating solution with alkali metal ions, are iron phosphates, iron oxides and iron hydroxides like, for example, vivianite and / or magnetite. The content of ions dissolved from a metal surface and then in a phosphating solution with alkali metal ions, especially aluminum, chromium, copper, iron, magnesium, tin, titanium, or zinc, is relatively low, since such compounds or cations are usually not added to bath, but they are only or almost only present due to the etching effect of an aqueous acid phosphating solution with alkali metal ions on the metal surfaces of parts, sheets, tapes or wires, which orye cover. Such a content will precipitate and generate a coating containing primarily phosphates, oxides and / or hydroxides of the metals contained in the solution, in addition, there may be traces or even a low content of such ions caused by impurities due to etching of the bathtubs and connecting pipes , as well as sequences from the earlier stages of the process.

A significant difference between the phosphating process with alkali metal ions as compared to the phosphating processes in the “coating forming phosphate” is also that the cation (s) necessary for coating formation during phosphating with alkali metal ions are always present ( ute) in a small percentage, mainly or completely dissolved from the surfaces of the substrates of the metal base, whereby during, for example, zinc, zinc-manganese, zinc-nickel or zinc-manganese nickel phosphation there will be a relatively high addition of, for example, zinc, so that zinc is contained mainly in an amount of more than 0.3 g / l, respectively, often more than 1 g / l in a phosphating solution. This high zinc content is often caused by the addition of zinc compounds of at least 40%, mainly more than 60%, often even more than 80% of the total bath content, while only the remaining content is mainly generated by the etching effect on zinc-containing surfaces . Coatings generated by zinc, zinc-manganese, zinc-nickel or zinc-manganese-nickel phosphation typically exhibit zinc and / or manganese-containing phases, usually gureaulite, phosphophyllite, scholzite and / or gopeite in predominantly crystalline forms.

Phosphating coatings with alkali metal ions exhibit substantially different properties than those after zinc-rich phosphating: they have a predominantly coating thickness in the range from 0.1 to 0.8 μm, respectively, only the coating weight in the range from 0.2 to 1.3 g / m ² . Unlike the predominantly matte gray appearance of the coatings enriched with zinc phosphating, the substantially thinner phosphating coatings with alkali metal ions are mainly transparent or exhibit rainbow colors due to their extremely small thickness. Then they show colors of "higher orders" and can be, for example, almost transparent, yellowish, golden, reddish, slightly purple, greenish or often bluish, partially iridescent. Only when phosphate coatings with alkali metal ions should have a higher coating weight, in particular greater than 0.7 and possibly up to about 1.3 g / m ² , can they exhibit a more matte gray appearance. In particular, coatings obtained by aluminum enriched phosphating with alkali metal ions may be silver or silver iridescent.

Phosphating coatings with alkali metal ions can be obtained without any subsequent generation of, for example, at least one paint layer and / or other organic layer similar to a paint. Then this coating process can be called processing. If phosphate coating is to be used to protect against corrosion for a limited time, then the coating may be called passivation. But it can be used under at least one layer of paint and / or another organic layer, like paint, like a primer, varnish, a layer of silane, soil and / or surface coating and / or, respectively, together with an adhesive, and can then be called pretreatment.

In general, a phosphating coating with alkali metal ions is carried out before painting by contact with an aqueous acidic phosphating solution, which usually contains at least one mono- and / or orthophosphate, and subsequent electrodeposition of the phosphated metal surfaces and / or often by powder coating, for example metal parts that are well accessible from the outside, like radiators and car bodies.

As a rule, today phosphating processes with alkali metal ions are carried out with solutions that contain an alkali metal and / or ammonium and at least one type of phosphate, mainly orthophosphate, as well as always at least one accelerator, thereby demonstrating a pH value during the operation, in the range of 4 to 6. These aqueous acidic solutions are in contact with metal surfaces, usually at temperatures in the range of 48 to 72 ° C. Typical coating weights range from 0.3 to 1 g / m ² . Modern coatings are rich in at least one phosphorus compound, exhibit a predominantly bluish or light gray hue and often have a coating weight in the range of 0.5 to 1.5 g / m ² .

The German patent application DE-A1-10006338 describes a typical process of glandular phosphating, where a small amount of copper ions is added to solutions with a pH in the range from 3.5 to 6.5 at a temperature in the range from 30 to 70 ° C and, in particular at a pH of approximately 4.8 at approximately 55 ° C. German patent application DE-A1-1942156 indicates a phosphating process with alkali metal ions using a high pressure spray method to contact metal surfaces with solutions at a temperature of 60 ° C and a pH in the range from 3 to 5.5, in particular with pH 4. German patent application DE-A1-1914052 relates to a phosphating process with alkali metal ions using a coating roller with a solution containing from 5 to 20 g / l of phosphate ions and from 3 to 12.5 g / l chlorate, at a temperature of 54.5 to 60 ° C unusual unconventional pH value in the range from 1 to 3.5 by contact roll at least 30 seconds and removing the moisture using a rubber roller. European application EP-B1-0968320 protects the phosphating process with alkali metal ions for radiators using a solution enriched in a surfactant with a pH in the range from 4 to 6 at a temperature in the range from 35 to 60 ° C and, in particular, at least 50 ° C. French patent application FR-A-1155705 relates to a phosphating process with alkali metal ions using a solution containing ammonium silicon hexafluoride and nitroguanidine, with a pH in the range from 3 to 6 at a temperature in the range from 50 to 76 ° C. GB-A-1388435 discloses a phosphating process with alkali metal ions using a solution containing free fluoride and chlorate, with a pH in the range of 3 to 6 at a temperature in the range of 50 to 80 ° C., in particular using pH in the range from 3.65 to 4.4. US patent 2665231 discloses a phosphating process with alkali metal ions using a solution containing fluoride, with a pH in the range from 3 to 5.8 at a temperature in the range from 60 to 82 ° C, in particular using a pH in the range from 4, 25 to 5.5.

European application EP 0 411 606 A2 describes methods for treating the surface of aluminum or its alloys by applying aqueous compositions containing niobium and / or tantalum together with fluoride and, possibly, titanium and / or zirconium, as well as phosphate. An addition of phosphate in an amount of from 0.01 to 0.5 g / l should be used as a pH adjustment agent. These compositions should help avoid blackening of containers during processing in boiling water.

European patent application EP 0121155 A1 indicates methods for producing iron or steel surfaces for painting by applying phosphating solutions with alkali metal ions containing acid phosphate with two hydrogen atoms and nitrobenzenesulfonate, which exhibit a pH in the range from 4.2 to 6.

German patent application DE 1942156 A1 discloses processes for treating metal surfaces, in particular iron and steel surfaces, by applying solutions containing alkali metal phosphate and, respectively, ammonium phosphate and benzoate, with a pH in the range from 3 to 5.5 at high pressure and at temperatures approximately 60 ° C.

The objective of the invention is to propose a phosphating process with alkali metal ions with very stable bath conditions and with an excellent coating appearance and coating properties using at least one accelerator like nitroguanidine. Further, the challenge is to propose a phosphating process with improved corrosion resistance compared to the typical alkali metal phosphating processes used today. Further, the object of the invention is to propose a phosphating process with alkali metal ions, which is stable, well suited for industrial applications for rolls, parts and wires, as well as lighter and more. cheap compared to the processes actually used.

Surprisingly, a “phosphate” metal surface with an unusually low or even zero phosphate content is possible. Even other acids, other than those containing phosphorus, can be used without loss of quality of the properties of the coatings. However, the term “phosphating” is used here for all kinds of coating processes and coatings, whether they contain phosphorus or not.

In accordance with the present invention, there is provided a method for coating metal surfaces with phosphating coating by contacting metal surfaces at a temperature not exceeding 45 ° C and at pH values less than 3.5 with an aqueous acidic phosphating solution with alkali metal ions or dispersion containing:

at least one compound of at least one phosphorus-containing acid and / or at least one of its derivatives, like esters and salts, with a total content of all types of acids and all their derivatives, like esters and salts together less than 20 g / l, calculated on a molar basis in the form of orthophosphate, where the content of such phosphorus-containing compounds / ions is at least 50% by weight relative to all such compounds / ions and

at least one ion selected from the group consisting of at least one alkali metal ion and ammonium ion,

where the phosphating solution or dispersion does not contain chromates, molybdates, niobates, tantalates and tungstates, where the phosphating coating has a coating composition with a phosphorus content of not more than 8 atomic%, as measured by secondary neutral mass spectroscopy (VNMS) and

where the phosphate coating has a coating weight in the range from 0.01 to 0.5 g / m ² .

In accordance with the present invention, a phosphating coating is provided on a metal surface obtained by contacting metal surfaces with an aqueous acidic phosphating solution with alkali metal ions or a dispersion, having a coating thickness of not more than 0.15 μm and providing good corrosion protection for the protected metal material.

It was found that steel panels treated with a phosphating solution with alkali metal ions of the usual composition, dried and then painted with polyester paint, show a corrosion inhibiting effect, as measured by salt spray testing, which is clearly dependent on the pH of the phosphating solution with alkali metal ions . At a solution pH of about 7, a calculation in salt fog (CT) showed results of about 5, with a pH of about 5, a CT of about 2.5, and with a pH of about 2.5, CT (mm offset from the mark) of about 1 5 or even less. Further details of this are in the examples.

Tests were carried out to identify the phases of various coatings by phosphating with alkali metal ions, but there was no result of X-ray diffraction capable of identifying the phases. Therefore, it is believed that thin coatings are amorphous or nearly amorphous.

Then, the content of the coating elements was analyzed by X-ray photoelectron spectroscopy (ESCA), which can be successfully used as a conventional measurement method for monitoring various coatings, but which is not an accurate measurement method for such coatings to identify the content of the element depending on the height of the coating. Only the upper 8 nm from the surface in depth could be analyzed and, therefore, there is the effect of surface impurities. The content of phosphorus and other elements in the coating was measured by X-ray photoelectron spectroscopy with a 5700 LSci device from Physical Electronics with a monochromatic aluminum X-ray source, source power 350 watts, analysis area 2 × 0.8 mm, exit angle 65 °, charge correction for C - (C, H) in the spectrum of C 1s was 284.8 eV, and the charge was neutralized by an electronic searchlight.

Finally, the content of coating elements was analyzed by secondary neutral mass spectroscopy (VNMS) with electronic gas INA3 - the VNMS Leybold device, which is an accurate measuring method to identify the content of elements depending on the coating height of such thin coatings by phosphating with alkali metal ions. Samples were sprayed with argon ions with an energy of 1040 eV and at a current density of approximately 1.2 mA / cm ² . An area of 5 mm in diameter was sprayed and analyzed. During the measurement, the atoms of the upper surface layer were evaporated, and the atoms of the following layers below were analyzed until the entire coating was removed into the sprayed region during the analysis. After 10 seconds of spraying, approximately 10 nm of the top of the coating was removed. The measurement method could be calibrated only to a certain amount of the composition of the analyzed coatings. The results showed a slight dependence of the surface roughness, which was taken into account in the calculation.

For both analyzes, ESCA and VNMS, the same four samples of cold-rolled steel panels were analyzed:

1) only peeled, but not coated panel,

2) a typical conventional coating with glandular phosphating in accordance with the state of technology, which is produced in today's practice by first cleaning and then contacting the panel with a glandular phosphating solution containing phosphate, sodium and chlorate, at a pH of 4.5 at a temperature of 50 ° C, generating a coating thickness of about 0.16 to 0.22 microns,

3) a very thin yellow coating with glandular phosphating in accordance with the invention, made after cleaning the panel by contacting it with a glandular phosphating solution containing phosphate, sodium and 0.2 g / l nitroguanidine, at a pH of 3.0 with a total acidity of 6 points at a temperature of 37 ° C with a coating thickness of from about 0.02 to 0.1 microns,

4) a thin bluish coating with glandular phosphate in accordance with the invention, produced after cleaning the panel by contacting it with a glandular phosphating solution containing phosphate, sodium and 0.2 g / l nitroguanidine, at a pH of 3.0 at a temperature of 37 ° C coating thickness from about 0.06 to 0.12 microns, but the total acidity dropped below 3 points.

Table 1
The content of sample elements is from 1) to 4), as measured by the ESCA method, in atomic%: Sample Fe Mn Zn Na TO Mg O N R 1) control 10.8 1,5 1,0 2,3 0.1 0.4 41.8 0.9 0.5 2) ordinary 7.2 0.3 0.3 1.3 0.1 0.1 50,2 1,2 10.8 3) yellow 13.6 0.1 0.7 0.2 but. 0.2 56.3 0.8 1,0 4) bluish 16.1 0.3 0.7 but. but. 0.2 57.2 0.5 1.8

The results of Table 1 demonstrate that there is a significant difference in composition between an uncoated sample 1), a coated sample in accordance with the state of technology 2) and coated samples 3) and 4) in accordance with this invention.

The figures represent the distribution of elements in atomic%, as analyzed by secondary neutral mass spectroscopy (VNMS), depending on the height of the coating, which was analyzed from the surface (left side) to massive steel material (from middle to right) in nm. Figure 1 for a cleaned, but not coated sample 1) shows the influence of impurities in the surface region and then the composition of the material of cold rolled steel. Figure 2 for sample 2) coated with typical glandular phosphating today indicates, through the Fe content, the thickness of the glandular phosphating coating. As shown in the following figures, the oxygen and phosphorus curves in the logarithmic graph are more or less proportional ("parallel"). The level in the upper and middle parts of the coating is approximately 30 atomic% Fe, approximately 50 atomic% O and approximately 9 atomic% R. FIG. 3 and FIG. 4 for coated samples 3) and 4) in accordance with the invention do not show pure levels. The coating of sample 4), which is several percent thicker than the coating of sample 3), indicates a content of approximately 50 atomic% Fe, approximately 35 atomic% O and approximately 6 atomic% P in the upper parts of the coating. Figure 5 presents the results of sample 5), which is comparable to sample 3), but shows higher surface roughness data and, therefore, higher signal output. 6 represents the results of sample 6), which is comparable to sample 4), but shows higher surface roughness data and, therefore, also a higher signal output. 7 represents curves of the P content of samples 1) to 4) in comparison, but now - as a linear graph - clearly showing different phosphorus contents, depending on the depth of the analyzed coating.

Therefore, it is clearly demonstrated that the composition of a conventional glandular phosphate coating is substantially different from the composition of a glandular phosphating coating according to this invention.

The surface roughness of all samples was measured with an NT3300 Wyko white light interferometer, each coated panel in three areas. For the samples 1) to 4) average data W _and ranged between 0.89 and 1.02 microns on the pad, the average data of W _z panel varied between 1.11 and 1.22 microns and average data W _t varied in panel between 6.17 and 7.25 microns. Compared to samples 3) and 4), samples 5) and 6) were coated in the same way and under almost the same conditions, but they showed surface roughness data almost twice as high as samples 3) and 4) average data Ш _а the panel data ranged from about 1.79 μm, the average panel data _{z z} varied around about 11.7 μm, and the average panel data _{t t} ranged from 11.4 to 12.1 μm. Sample 3) must be compared with sample 5) by the difference in surface roughness and content of elements; similarly, sample 4) must be compared with sample 6). Since coarser surfaces make it possible to measure a higher number of neutral parts than flatter surfaces, flatter surfaces will be used for analytical research and evaluation.

Preferably, the P content is less than 8 atomic% at a depth of 0.05 μm below the (initial) surface of the phosphate coating with alkali metal ions, as analyzed by secondary neutral mass spectroscopy (VNMS), or less than 6 or even less than 4 atomic% at a depth of 0.1 μm below the coating surface by phosphating with alkali metal ions or less than 3 or less than 2 atomic% at a depth of 0.1 μm below the coating surface by phosphating with alkali metal ions. Preferably, the phosphate coating according to the invention has a thickness of not more or less than 0.15 microns, more preferably not more than 0.12 microns, much more preferably not more than 0.10 microns.

The method in accordance with the invention can preferably be characterized in that the temperature of the phosphating solution or dispersion can be during the contact of metal surfaces in the range from 10 to 42 ° C or less than 40 ° C and more preferably at least 15 ° C or up 38 or up to 35 ° C. The pH can preferably be selected in the range starting from 1.8, respectively reaching up to 3.3, more preferably from at least 2 or up to 3.1, especially at least 2.5 or up to 2 ,9. The weight of the coating may preferably be selected in the range from 0.03 to 0.4 g / m ² , more preferably at least 0.05 or 0.36 g / m ² , most preferably from at least , 0.1 or up to 0.32 g / m ² .

Most organic and mineral acids, as well as their water-soluble and / or water-dispersible derivatives, in particular salts and / or esters, can be taken as acids for use in a phosphating solution or dispersion, but hydrochloric acid and chlorides are not recommended since they can cause significant crevice corrosion. You can even use a mixture of a) acids, b) at least one acid with at least one of the salts and / or with at least one of the esters or c) at least one of the salts and / or at least one of the esters.

Preferably, at least one acid like phosphoric acid, pyrophosphoric acid, monophosphoric acid, at least one of phosphonic acids, for example, in particular at least one with at least one aliphatic and / or aromatic group each, in particular at least one of diphosphonic acids, phosphonous acid, phosphorous acid, molybdatophosphoric acid, tungsten phosphoric acid and / or at least one of their derivatives, similar to the ester (s) ) and / or salts (s), in particular at least one of the monoesters, diesters and / or triesters containing phosphorus acids, like phosphoric acid, more preferably mixed with at least one phosphorus acid.

At least one sulfur-containing acid and / or at least one of its derivatives like ester (s) and / or salt (s) like sulfuric acid, sulfamic acid are preferably used acid of at least one of sulfonic acids, like nitrosulfonic acid, respectively, at least one of their derivatives, similar to the ester (s) and / or salt (s).

Preferably, at least one nitrogen-containing acid and / or at least one of its derivatives, like ester (s) and / or salt (s), like nitric acid, is used, at least at least one acid having at least one nitro and / or at least one amino group, respectively, at least one of their derivatives, similar to the ester (s) and / or salt (s).

At least one organic acid and / or at least one of its derivatives, like ester (s) and / or salt (s), like at least one, are preferably used. from aromatic organic acids, hydroxycarboxylic acids, oxoacids, peracids and / or oxocarboxylic acids, respectively, at least one of their derivatives, similar to the ester (s) and / or salt (s), in particular can be used like acetic acid, benzoic acid, citric acid, formic acid, glitch new acid, hydroxyacetic acid, lactic acid, malic acid, oxalic acid, succinic acid, tartaric acid and / or their water-soluble and / or water-dispersible derivatives, like ester (s) and / or salt (s).

Any acid, its derivative, a mixture of acids and / or mixtures with at least one of its derivatives, like ester (s) and / or salt (s), can be used, in particular, at least one such or any mixture that is capable of exhibiting a pH value of, for example, approximately 2.4, approximately 2.9, approximately 3.4, approximately 3.9 and / or approximately 4.4, and which is capable of generating at least, together with the cation present - a thin coating, but a high amount of hydrochloric acid and chloride is not desired Flax for use due to their very strong corrosive effect. Of these acids and derivatives, phosphoric acid and dissolved phosphoric esters / salts are particularly preferred. In order to accelerate the phosphating process, reducing and / or oxidizing accelerators may be added, but this is not necessary. Such accelerator (s) may be favorable for enhancing the process, coating quality and / or effect on the oxidizing situation.

In the method according to the invention, the phosphating solution or dispersion contains in many, but not all cases, at least one accelerator similar to that based on chlorate, guanidine, an organic compound with at least one nitro group, similar to nitroguanidine and / or nitrobenzenesulfonic acid and its derivative, hydrogen peroxide, hydroxylamine, nitrate and / or another nitrogen-containing accelerator;

more preferred are nitroguanidine, nitrobenzenesulfonic acid and / or its derivatives, like salts (s). All accelerators together have a content in the range from 0.005 to 10 g / l, preferably in the range from 0.01 to 6 g / l, more preferably in the range from 0.02 to 3 g / l, particularly preferably from at least 0.03 to 1 g / l, most preferably from at least 0.05 to 0.7 g / l.

It was unexpectedly observed that it is possible to use the method in accordance with the invention without the addition of any accelerator. The quality of the accelerator-free phosphating solutions or dispersions, as well as the coating procedures and the quality of the resulting coatings, were the same as with the content of at least one accelerator. This can only happen when the etching rate of a solution or dispersion not containing an accelerator is slightly reduced so that the coating speed is reduced and the contact time should be slightly increased.

In the method according to the invention, the amount of Fe ^{2+ ions} can be added to the phosphating solution or dispersion, preferably in the range of 0.01 to 1 g / l, more preferably in the range of 0.02 to 0.8 g / l, especially preferably in the range from 0.03 to 0.5 g / l, most preferably from at least 0.05 to 0.3 g / l. The additive may be dissolved iron phosphate. This additive helps in some cases, especially for non-ferrous metal surfaces, such as those of hot dip galvanized (HGP) or electrogalvanized materials (EG), giving better corrosion inhibition performance.

In the case of - especially in the absence of an accelerator - coating of steel surfaces, it is advisable to be careful that the phosphating solution or dispersion does not contain more than about 0.5, 1, or 1.5 g / L of Fe ^{2+ ions} , depending on the actual conditions of phosphating; the iron content can then be lowered by the addition of an oxidizing agent, which may in some cases be an accelerator, and / or using cation exchange material, for example a suitable resin.

In preferred embodiments, the phosphating solution or dispersion contains free fluoride, preferably in the range of 0.01 to 1 g / l and / or complex fluoride, in particular aluminum, boron, silicon, titanium and / or zirconium, preferably each in the range of 0 , 01 to 1 g / l. In such cases, it is more preferable that the content of each of the free fluorides, respectively, of each of the complex fluorides lies in the range from 0.02 to 0.8 g / l, particularly preferably in the range from 0.03 to 0.5 g / l, most preferably from at least 0.05 or up to 0.3 g / l. The content of free fluoride and / or at least one complex fluoride enhances the etching effect, especially on galvanized metal surfaces, as well as on aluminum-enriched surfaces, since oxides can be easily removed from the metal surface; further, it improves the characteristics and quality of the inhibition of corrosion and adhesion of the paint of the thus formed coating for all bases of metallic materials.

In the method according to the invention, the amount of PO ₄ ions can be added to the phosphating solution or dispersion, preferably in the range from 0.1 to 18 g / l, more preferably in the range from 0.5 to 15 g / l, particularly preferably from at least 1 and / or up to 12 g / l, most preferably at least 2 g / l and / or up to 9 g / l PO ₄ ions. The phosphate content may provide the necessary acidity for the primary etching effect. It may also help in some cases to remove excess heavy metals like iron from the solution, which may predominantly or completely result from etching. Phosphoric acid can be added as an acid, as a monobasic acid and / or as a salt of a polyacid and an alkali metal and / or ammonium group, or in small quantities as iron phosphate. Instead or partially instead of phosphoric acid, its ester (s) and / or its salt (s), phosphonic acid and / or other phosphorus-containing acid and / or at least at least one phosphoric acid can be added to the solution or dispersion , one of their salts and / or esters, in particular at least one water-soluble phosphoric acid ester.

In the method in accordance with the invention, the phosphating solution or dispersion may contain an amount of SO ₄ ions in the range from 0.1 to 10 or 18 g / l, preferably from at least 0.5 and / or up to 15 g / l, more preferably in the range of 1 to 12 g / l, much more preferably at least 2 g / l and / or up to 9 g / l of SO ₄ ions. The sulfate content may provide the necessary acidity for the primary etching effect. Sulfuric acid can be added as an acid or as an alkali metal sulfate and / or ammonium group, or in small amounts as iron sulfate. In particular, a mixture of at least one phosphorus-containing acid and / or its salt (s) and / or its ester (s) with at least one may be added to the solution or dispersion sulfur-containing acid and / or its salt (s) and / or its ester (s); preferably, the content of such a phosphorus-containing compound should be at least 50% by weight of all such acids, salts and esters.

In the method according to the invention, the phosphating solution or dispersion may contain an amount of NO ₃ ions in the range from 0.1 to 18 or up to 10 g / l, preferably from at least 0.5 and / or up to 15 g / l, more preferably from at least 1 and / or up to 12 g / l, much more preferably at least 2 g / l and / or up to 9 g / l NO ₃ ions. The nitrate content may provide the necessary acidity for the primary etching effect. Nitric acid can be added in the form of an acid, in the form of nitrate of at least one alkali metal and / or ammonium, or in small quantities in the form of iron nitrate. In particular, a mixture of at least one phosphorus-containing acid and / or its salt (s) and / or its ester (s) with at least one containing can be added to the solution or dispersion nitrogen with an acid and / or its salt (s) and / or its ester (s); preferably, the content of such a phosphorus-containing compound should be at least 50% by weight of all such acids, salts and esters.

In the method in accordance with the invention, the phosphating solution or dispersion may contain the number of groups, ions and compounds together of the organic acid (s) and / or its derivative (s) in the range from 0.1 to 10 or 18 g / l, preferably from at least 0.5 and / or up to 15 g / l, more preferably in the range from 1 to 12 g / l, much more preferably at least 2 g / l and / or up to 9 g / l of such groups, ions and compounds.

Further, the phosphating solution or dispersion may contain an amount of nitroguanidine and / or other guanidine-based accelerators like guanidine acetate, aminoguanidine, guanidine carbonate, melaminoguanidine, guanidine nitrate and ureidoguanidine in the range of the total amount from 0.01 to 5 g / l, preferably from 0.015 to 3 g / l, more preferably in the range from 0.01 to 1.2 g / l, much more preferably at least 0.02 g / l and / or up to 0.6 g / l of compound guanidine. Nitroguanidine has demonstrated in several examples that it gives the best results from all proven accelerators. Compared to the use of aminoguanidine, the addition of nitroguanidine in small amounts was more favorable, especially for corrosion inhibition.

In the method according to the invention, the phosphating solution or dispersion may contain at least one surfactant, especially when the cleaning and phosphating is carried out with the same solution or dispersion, then preferably with the amount of all surfactants together in the range of 0.01 to 10 g / l. When using at least one surfactant in a phosphating solution, it is preferable to be careful not to create a foam. In some cases, it may be beneficial to add an antifoam. This total surfactant content may preferably vary in the range of 0.1 to 7 g / l, more preferably in the range of 0.3 to 5 g / l, much more preferably at least 0.5 g / l and / or up to 3 g / l of surfactant (s). Particularly in processes in a single vessel, purification and phosphating can be carried out in the same vessel with the same solution or dispersion so that the first contact of the metal components with the phosphating solution or dispersion, the cleaning and the etching effect of the solution or dispersion can prevail, whereas in the subsequent contact time, the coating process with the formation of phosphate coating could predominate, In general, almost all types of surfactants, respectively mixtures of surfactants stv are suitable to be added to the phosphating solution or dispersion, in particular surfactants, respectively mixtures of surfactants with low foaming or without foaming properties, and with a cloud point in the range from 25 to 40 ° C, as a result of which the mixture surfactants may be free of other constituents other than surfactants.

The phosphating solution preferably does not contain or almost does not contain other heavy metals other than those that will be etched from the metal surface, possibly with the exception of titanium and / or zirconium, in particular in the presence of complex fluoride (s). It preferably does not contain chromates, molybdates and tungstates.

In the method according to the invention, the phosphating solution or dispersion may contain at least one solvent like propylene glycol and / or glycol ether; it may further comprise at least one biocide, at least one stabilizing agent for a surfactant, like a condensed sulfone salt, at least one stabilizing agent for an accelerator, like fine silicate, clay, or a clay-like material, and / or at least one stabilizing agent for a solution or dispersion, per se similar to a biopolymer. A solvent may be preferred to enhance the cleaning effect on the metal surface, especially in combination with at least one surfactant. It is advantageous to use the guanidine compound in the form of a suspension containing a stabilizing agent, especially nitroguanidine.

In the method according to the invention, a phosphating coating is obtained which exhibits a substantially colorless, slightly colored, silvery, golden, yellowish, yellowish-brownish, yellowish-reddish and / or bluish color. If the coating according to the invention is bluish, it often turns out that the phosphorus content in the coating is not as low as usual for such coatings, and it often detects corrosion inhibition results of not so high quality. This coating may in some cases be less intensely colored or may look less bright and / or even dull in appearance, in contrast to conventional coatings. This coating may typically have a coating thickness in the range of up to 1 μm, preferably only up to 0.6 μm, often only up to 0.3 μm.

In the method according to the invention, a clean, cleaned and / or etched metal surface is brought into contact with the solution, respectively, with the dispersion. The metal surface can be brought into contact with the solution, respectively, with dispersion, by immersion, spraying, phosphating in steam, coating by rolling and / or removing moisture with a rubber roller. Often used for coilcoating all the many ways of applying, with the exception of phosphating in pairs. The coated metal surface is dried after it is in contact with the solution, respectively, of the dispersion, or later, after at least one washing step, preferably dried by air, oven drying and / or infrared drying, especially at temperatures in the range 20 to 250 ° C.

You can apply at least two coatings, one after the other, on a metal surface, where at least one of them is applied using a phosphating solution with alkali metal ions, respectively dispersion, and where at least one of the following coating may possibly be applied by chemical reaction of the coating solution, like phosphating with zinc and / or manganese enrichment.

In the method according to the invention, a phosphate coating with alkali metal ions is first generated on a metal surface, and then a coating selected from the group consisting of a coating by chemical interaction similar to phosphating with enrichment with zinc and / or manganese, a stearate coating and an organic coating is applied to it. polymer, in particular by cold forming.

In the method in accordance with the invention, a metal surface consisting mainly of metallic materials of aluminum, chromium, titanium and / or zinc, as well as at least one alloy containing aluminum, chromium, copper, like brass or bronze, iron, magnesium , tin, titanium and / or zinc alloys are coated with a coating of a phosphating solution or dispersion.

The coating obtained by the method in accordance with the invention, can be used for short-term passivation, for pre-treatment before applying at least one subsequent layer of paint, a layer of any other paint material and / or adhesive coating, as a carrier of lubricant or as one of the lubricating coatings before cold forming. The lubricant, respectively, the lubricant carrier can be successfully used for containers, for machining, for drawing wire and / or for lubricating moving chains.

This method can be successfully varied by coating with a thin phosphating coating according to the invention with a final sealing solution or dispersion. Salt spray test results demonstrate that a second, third, and / or fourth coating on a metal surface obtained by contacting the panels phosphated in this way with the final sealing solution or dispersion substantially enhances the corrosion resistance, although such final sealing coatings are very thin. Preferably, such final sealing coatings can be produced using a final sealing solution / dispersion containing at least one rare earth compound like a cerium compound, at least one polymer component like an acrylic acid derivative and / or at least one silane.

The coating obtained by the method in accordance with the invention can be used to inhibit corrosion and / or to lubricate metal surfaces, especially for use in the aerospace industry, automotive industry, rail transport, shipbuilding, metal forming, metal processing, such as machining and / or grinding , in metal containers, and especially in the production of containers, the production of rolls, for the deposition of metal sheets, the production of wire, devices, casings nuts, mechanisms and structures of buildings.

Examples

The following examples illustrate in detail embodiments of the invention. The following examples and comparative examples should help clarify the invention, but they are not intended to limit its scope.

Group 1: comparative examples 1 to 6.

The first tests were carried out in which an aqueous acid solution in the form of a phosphating concentrate A with alkali metal ions accelerated with standard chlorate and sodium methanitrobenzenesulfonate (NBSN) containing

1.3% by weight (about 13 g / l) of phosphoric acid,

11.7% by weight (about 117 g / l) of sodium monophosphate,

1.0% by weight (about 10 g / l) NBSN,

10.0% by weight (about 100 g / l) sodium chloride, and

the rest is demineralized water,

compared with another aqueous acidic solution of a phosphating concentrate B with alkali metal ions, accelerated only with nitroguanidine, containing:

1.3% by weight (about 13 g / l) of phosphoric acid,

11.7% by weight (about 117 g / l) of sodium monophosphate and the rest is demineralized water.

Based on these concentrates, baths with these solutions were obtained at 3% by volume (approximately 30 g / l) for both compositions, which means for solution A 3.58% by weight, respectively, for solution B 3.30% by weight (approximately 33 g / l) concentrate. 0.2 g / L nitroguanidine stabilized with a small amount of clay-like material was further added to solution B. The pH of both phosphate baths was adjusted to 4.5, respectively, to 2.8 by the addition of sodium hydroxide.

Cold rolled steel (HXC) panels were cleaned with Okemclean® at 3% by volume (about 30 g / l) and a temperature of 54.4 ° C for 30 seconds by spraying. The panels were then rinsed and then treated in a phosphating bath A or B for 60 seconds by spraying at various temperatures. After that, they were rinsed and dried with compressed air. At the end, the panels were painted with Dupont TGIC polyester powder and tested in salt spray strictly according to cASTM B 117 for 336 hours to evaluate the corrosion inhibiting properties strictly according to cASTM D 1654 with a rating of 10 for best and 0 for worst.

table 2
The composition of the coatings of various groups Content in g / l
Examples / comparative examples RO ₄ ^3- Na ⁺ ClO ₃ ^- NBS Nitroguanidine Aminoguanidine Carbonate 108, 0.12 0.02 - - 0.02 61.64.67, 0.58 0.12 - - 0.2 - 70.73.73, 0.58 0.12 - - - 0.2 82.84.92, 1.16 0.25 - - 0.02 - 62.65, 68, 1.16 0.25 - - 0.2 - 71.74.77, 1.16 0.25 - - - 0.2 83.85, 95, 1.16 0.25 - - 0.6 - 106, 3.01 0.64 - - 0.5 - 88.91.94.97, 3.01 1.38 2,37 0.90 - - 1-3, 11-14, 19-22, 27-30, 35-38, 51-53, 63, 66, 69, 3.48 0.74 0.2 54-56, 72, 75, 78, 3.48 0.74 - - - 0.2 4-6, 15-18, 23-26, 31-34, 39-42.79, 110, 111 3.78 1,61 2,31 0.32 107, 4.41 0.94 - - 0.8 - 86, 93, 96, 102, 5.80 1.23 - - 0.02 - 101, 5.80 1.23 - - 0.5 - 81, 87, 89, 90, 5.80 1.23 - - 0.6 -

Table 3
Coating weight and XC salt spray test ratings for high pH depending on the temperature of the solutions forming the coating systems of various accelerated phosphating systems with alkali metal ions Comp. Accelerator PH value Temperature Coating weight ASTMD 1654 Salt Fog Test Assessment (° C) (g / m ² ) 550 h 1008 h s.p. one Nitroguanidine 4,5 54,4 0.18 6 6 s.p. 2 " " 65.6 0.24 5 four s.p. 3 " " 82,2 0.34 - 3 s.p. four Chlorate-NBSN 4,5 54,4 0.32 3 0 s.p. 5 " " 65.6 0.52 0 one s.p. 6 " " 82,2 0.46 - one

The higher the rating, in particular after a longer test time, the better the results of corrosion inhibition. As the temperature increases in bath B with the nitroguanidine accelerator, the coatings become more uniform and change from taupe to blue. Lower processing temperatures and lower coating weights correlate with better salt spray stability. System B with a nitroguanidine accelerator demonstrates a better and more uniform appearance of coatings and better corrosion inhibition than system A with a chlorate-NBSN accelerator. The coating for the panels was homogeneous and changed in color from blue to golden when the temperature increased.

Group 2: comparative examples 11 to 42.

The same basic bath compositions were used for the following tests with standard system A accelerated with chlorate-NBSN and with system B accelerated with nitroguanidine, as in group 1. Panels of cold rolled steel (HKS), hot dip galvanized steel (HGP), electro galvanized steel (EG) and aluminum alloy AA 6061 were cleaned with Gardoclean® S 5206, rinsed, treated in phosphating baths A or B and then rinsed and dried with compressed air. Based on the results of group 1, the temperature range to be covered was changed to use lower temperatures. The panels at the end were stained with Morton Corvel Black powder paint and subjected to salt spray testing for 250 hours in accordance with ASTM B 117. Offset from the mark was measured in accordance with grades 0 to 10 in accordance with ASTM D 1654; the higher the CT score, the better the results.

Table 4
salt spray test results for various metal surfaces depending on the temperature of the solutions for coating various accelerated phosphating systems with alkali metal ions for pH 4.5 Comp. Accelerator Substrate Temperature (° C) Coating Weight (g / m ² ) Salt spray test rating for 250 h s.p. eleven Nitroguanidine Hks 26.7 0.02 7 s.p. 12 " " 43.3 0.14 2 s.p. 13 " " 54,4 0.26 3 s.p. fourteen " " 65.6 0.33 3 s.p. fifteen Chlorate-NBSN Hks 26.7 0.23 one s.p. 16 " " 43.3 0.23 2 s.p. 17 " " 54,4 0.50 3 s.p. eighteen " " 65.6 0.27 2 s.p. 19 Nitroguanidine GGP 26.7 - 3 s.p. twenty " " 43.3 - 2 s.p. 21 " " 54,4 - 3 s.p .: 22 " " 65.6 - one s.p. 23 Chlorate-NBSN GGP 26.7 - 3 s.p. 24 " " 43.3 - 3 s.p. 25 " " 54,4 - 3 s.p. 26 " " 65.6 - four s.p. 27 Nitroguanidine EG 26.7 - 2 s.p. 28 " " 43.3 - 2 s.p. 29th " " 54,4 - 2 s.p. thirty " " 65.6 - 0 s.p. 31 Chlorate-NBSN EG 26.7 - four s.p. 32 " " 43.3 - 3 s.p. 33 " " 54,4 - 2 s.p. 34 " " 65.6 - 0 s.p. 35 Nitroguanidine AA6061 26.7 - 10 s.p. 36 " " 43.3 - 10 s.p. 37 " " 54,4 - 10 s.p. 38 " " 65.6 - 10 s.p. 39 Chlorate-NBSN AA6061 26.7 - 10 s.p. 40 " " 43.3 - 10 s.p. 41 " " 54,4 - 10 s.p. 42 " " 65.6 - 10

The test results in this test series demonstrate that the results are partially better at lower temperatures, but the results are highly dependent on the metal material of the contacting surface. Excellent results could be achieved with all aluminum alloy panels. Nitroguanidine showed good corrosion inhibition results, and it was very unexpected that this could be obtained with such a thin coating.

Again, all panels were homogeneous. For this invention, HCS panels changed from taupe to blue when the temperature was raised. GGP and EG panels showed etched appearance in all cases, but without color. The aluminum panels were shiny with no noticeable visible coating. For chlorate samples, HKS panels changed from blue to golden in color with increasing temperature, HGP and EG panels had a rainbow appearance, and aluminum panels had a transparent appearance of a slightly yellow-brown hue.

Group 3: comparative examples 43 to 44.

Cold rolled steel panels were treated with aqueous acidic phosphating solutions B containing only very small amounts, much less than 1 g / l, of phosphoric acid, only to bring the pH of the prepared mixed solution to 2.5, respectively 4.5, 0.2 g / l nitroguanidine and 0.2 g / l of aminoguanidine bicarbonate. If aminoguanidine was added in all examples, it was added as bicarbonate, although this is not always indicated. The panels were cleaned with Gardoclean® C 5206 and rinsed before the addition of nitro- and aminoguanidine. The panels were brought into contact with a phosphating solution for testing with a pH of 2.5 at room temperature, and for testing with a pH of 4.5 at 49 ° C. Then, the panels were rinsed and dried with compressed air. Such coated panels had a golden appearance and showed a uniform coating. The panels were then stained with Ferro TGIC polyester powder paint. At the end of the panel, paint adhesion was checked by cross-hatching and direct exposure. In these tests, a significant loss of paint was observed, which was unacceptable. The panels were then also subjected to salt spray testing for 250 hours in accordance with ASTM B 117. The panels were rated 0 according to ASTM D 1654 for all cases after 250 hours, which is also a poor result. Since the solutions did not contain either alkali metal ions or ammonium ions, they were not buffered and lacked a significant amount of acid.

Group 4: comparative examples 51 to 56.

Comparative examples illustrate the effect of low and very high pH values of a phosphating solution using 0.2 g / l nitroguanidine and 0.2 g / l aminoguanidine carbonate as accelerators and using a stock solution of bath B from group 1 containing 3% by volume ( about 30 g / l) of a concentrate containing 1.3% by weight (about 13 g / l) of phosphoric acid, 11.7% by weight (about 117 g / l) of sodium monophosphate, and the rest is demineralized water. Panels from HKS cleaned, as in the previous examples. Starting with a very acidic bath, the addition of NaOH brought it to very high pH values. This chemically interacting coating solution was sprayed onto the panel for 60 seconds at 48.9 ° C.

The unpainted panel from each test was placed in a 100% humidity test chamber for water fog testing in accordance with ASTM D 1735 for 72 hours, and then the percentage of surface with red rust was evaluated. The rest of the panels were stained with Ferro TGIC polyester powder and placed in a salt spray test chamber in accordance with ASTM B 117 for 250 hours, and salt spray test with an acetic acid accelerator (MUST) was applied to copper strictly in accordance with standards General Motors Engineering from June 1997 for 72 hours. Salt mist test results and MUST test results were measured in mm of offset from the mark. The panels from tests 3 and 6 did not form any visible coating and, therefore, were not further tested. The nitroguanidine bath was not stable above a pH of approximately 7.

Table 5
Moisture test results, in salt spray and MUST, depending on the pH of the solutions for coating various accelerated phosphating systems with alkali metal ions Comp. Accelerator PH value Humidity in% Salt fog in mm MUST in mm s.p. 51 Nitroguanidine 2,8 10-25 0.1 0.2 s.p. 52 " 7.0 10-25 0.2 0.4 s.p. 53 " 9.0 - - - s.p. 54 Aminoguanidine Carbonate 2,8 one hundred 0.2 0.3 s.p. 55 " 4,5 40 0.1 0.1 s.p. 56 " 6.5 - - -

Corrosion inhibition was good only for specimen sp. 51 with a pH of 2.8, and in other cases of average quality. For this group, the weight of the coatings was not measured. Coatings in all cases were homogeneous. The coatings obtained with both nitro and aminoguanidine showed a golden color at a low pH and were blue at a high pH.

Group 5: examples and comparative examples 61 to 79.

The cold rolled steel panels were cleaned and rinsed as in the previous examples and comparative examples. Phosphating baths were prepared with different amounts of basic bath compositions, starting from Group 1 and changing the concentrations of accelerators from A and B. The chemically interacting coating baths were operated at 26.7 ° C and mainly at pH 4.5 for 60 seconds of spraying. The last comparative example 79 was a standard phosphation with alkali metal ions, accelerated by the chlorate-NBSN system, as emphasized in group 1, but it only worked at a pH of 4.5 and at a temperature of 48.9 ° C for 80 seconds of spraying. The salt spray score was calculated in accordance with ASTM D 1654 after a 500 hour salt spray test in accordance with ASTM B 117.

Table 6
Salt spray test results and coating weight depending on the amount of accelerator from solutions for coating various accelerated phosphating systems with alkali metal ions and pH at a temperature of 26.7 ° C; * bath without accelerator Ex. / Compare. etc. Accelerator Accelerator (g / l) Bath concentration * (g / l) (approx.) The concentration of the bath * vol.% PH value Coating Weight (g / m ² ) 500 h salt spray rating s.p. 61 Nitroguanidine 0.02 5 0.5 4,5 0.06 0 s.p. 62 " " 10 one " 0.14 0 s.p. 63 " " thirty 3 " 0,07 0 s.p. 64 " 0.2 5 0.5 " 0.16 0 s.p. 65 " " 10 one " 0.13 0 s.p. 66 " " thirty 3 " 0.01 0 s.p. 67 " 0.4 5 0.5 " 0.16 0 s.p. 68 " " 10 one " 0.14 0 s.p. 69 " " thirty 3 " 0.11 0 s.p. 70 Aminoguanidine Carbonate 0.2 5 0.5 - 0.11 0 s.p. 71 " " 10 one " 0.30 0 pr 72 " " thirty 3 2,8 0.15 3 s.p. 73 " 0.1 5 0.5 4,5 0,03 2 s.p. 74 " " 10 one " 0.19 0 Ave 75 " " thirty 3 2,8 0.16 3 s.p. 76 " 0.05 5 0.5 4,5 0,03 2 s.p. 77 " " 10 one " 0.10 one Ave 78 " " thirty 3 2,8 0.01 3 s.p. 79 Chlorate-NBSN " thirty 3 4,5 0.45 one

The examples in accordance with the invention, 72, 75 and 78, demonstrate significantly better corrosion results than most other examples. The coatings were even golden in color at low pH and blue at high pH for coatings made with amino, respectively nitroguanidine.

Group 6: examples and comparative examples 81 to 97.

In this group, the so-called multimetal composition was used. The bath solution contained fluoride for treating cold rolled steel, hot dipped galvanized steel, electro galvanized steel and aluminum. The basic solution B from group 1 was used with an additional content of free fluoride, where the content of all components of this bath was different at a temperature of 38 ° C.

Many solutions were used and many tests were carried out to obtain data for intensive study with design estimates of the experiments. For these experiments, metal surfaces, fluoride content (50-200 mg / l), added Fe ²⁺ content (0-200 mg / l), sodium phosphate and sodium monophosphate together (1.4-7.2 g / l), the content of nitroguanidine as the sole accelerator (0.02-0.6 g / l), as well as the pH value (2.8-4.5), where only examples in accordance with the invention are listed in Table 7. In comparison with them, an accelerating solution of chlorate-NBSN with a pH value of 4.5 was tested at 49 ° C with comparative examples 88, 91, 94 and 97, while others with Comparative examples belonged strictly to the data set, as shown for the rest of the examples in accordance with the invention. The number of tested examples and comparative examples was reduced for this overview so that typical results are presented here. From these experiments, systematic calculations were performed and areas of excellent, respectively good, respectively stable behavior were selected.

The panels were stained with a Ferro TGIC polyester powder with a thickness of 38 to 51 μm and placed in a salt spray (CT) test chamber according to ASTM B 117 for 250 hours, where the test results were measured in mm offset from the mark. Further, adhesion was tested in accordance with ASTM D 3359, where 5 V means that no delamination occurred in the cross-sectional region, which represents the best possible test result, whereas, for example, 2B means that there is a certain degree of delamination in the transverse region sections.

Table 7
Salt spray test results depending on the chemical composition of the phosphating solutions and the pH value at a temperature of 32 ° C; * bath without accelerator Ex. / Compare. etc. Metal
surface Bath concentration (g / l) Speed up
tel (g / l) Fluoride
(mg / l) Fe ²⁺ (mg / L) PH value Adhesion ASTM 3359 Grade in ST for 240 h Grade in ST for 500 h Ave 81 Hks 7.2 0.6 200 0 2,8 5V one 2.5 Ave 82 " 1.4 0.02 fifty 200 " 5V 0.5 2 Ave 83 " 1.4 0.6 200 200 " 5V 0.5 one Ave 84 " 1.4 0.02 200 0 " 4B one 1,5 s.p. 85 " 1.4 0.6 200 0 4,5 5V 2.5 four pr 86 " 7.2 0.02 200 200 2,8 5V one 1,5 s.p. 87 " 7.2 0.6 200 200 4,5 4B four 9 s.p. 88 " 4.1 4.4 310 0 4,5 2B 4,5 7 pr 89 GGP 7.2 0.6 fifty 200 2,8 3B 3,5 four pr 90 " 7.2 0.6 200 0 " 3B four 5 s.p. 91 " 4.1 4.4 310 0 4,5 2B 10 eighteen Project 92 EG 1.4 0.02 fifty 200 2,8 5V 2 2.5 pr 93 " 7.2 0.02 200 200 " 5V 1,5 3 s.p. 94 " 4.1 4.4 310 0 4,5 2B 3,5 four Ave 95 A 6061 1.4 0.6 fifty 0 2,8 4B 0.5 0.5 Ave 96 " 7.2 0.02 fifty 0 " 4B 0.5 0.5 s.p. 97 " 4.1 4.4 310 0 4,5 4B 0.5 one

Almost all the examples in accordance with the invention showed very good results on the inhibition of corrosion, respectively, for corrosion-sensitive HGP material, even superior results compared with the results of comparative examples. The higher the adhesion test value, the better the results. The coatings were even in all cases. The HKS panels according to the invention were gray, the HGP panels were very slightly golden, the EG panels were gray, and the aluminum panels did not have any noticeable color. For control, the HKS panels were golden, the EG and HGP panels were transparent and rainbow, and the aluminum panels were blue.

Group 7: examples and comparative examples 101 to 111.

Only cold-rolled steel panels were used in this group and various effects were checked, even the effect of bath temperature. The solutions did not contain fluoride and added Fe ²⁺ . All other coating conditions and conditions were the same as in group 6. Further, comparative examples of samples 109 and 110 were coated with Bonderite® 1000 (comparative example 109) to have an additional thin final chromium seal coating phosphate coating, respectively Cryscoat® 547, in order to have an additional thin non-chromium final seal covering the phosphate coating (comparative example 110), and the latter without an additional final seal (comparative example 111), each is coated in the usual manner. These coatings can be used as typical industry standards to provide a comparison of today's typical glandular phosphate coatings.

Table 8
Salt spray test results on three panels of HCS, each depending on the chemical composition of the coating solutions, pH, contact time and temperature; * bath without accelerator Examples / comp. etc. Bath concentration * (g / l) Accelerator (g / l) PH value Contact time (s) Temperature (° C) CT score for 240 h, mm displacement Project 101 7.2 0.5 2,8 thirty 32 one Project 102 7.2 0.02 2,8 105 32 1,1 Project 103 4.3 0.2 3.0 60 37 0.5 Ave 104 0.14 0.02 2,8 180 37 1,2 Project 105 0.14 1,0 2,8 thirty 44 1,0 s.p. 106 3,7 0.5 4.9 105 44 1,6 s.p. 107 5,4 0.8 6.0 68 54 8.1 s.p. 108 0.14 0.02 4.9 180 60 9.3 s.p. 109 - - - - - 0.2, 0.5 s.p. 110 4.6 3.9 4,5 52 60 2 s.p. 111 4.6 3.9 4,5 52 60 5

The examples in accordance with the invention showed very good corrosion inhibition results compared with the results of comparative examples. Comparative examples vary in relation to the quality of corrosion inhibition, depending on whether there is a next sealant or not, and especially if this final sealant is a layer containing chromium. Comparative example 109, showing such an additional chromium-containing layer covering the phosphate layer, should demonstrate the best corrosion inhibiting properties. However, it is unexpected that the best panels in accordance with the invention were able to achieve excellent corrosion inhibiting properties of comparative example 109, which is the best industrial standard iron phosphate-based material known in the technology, which in this case is evenly coated with the following highly corrosion-inhibiting final washed layer.

Coatings were even in all cases. The color changed from golden to blue when either pH or temperature was increased. Contact time, bath concentration and accelerator concentration did not have any noticeable effect on the appearance.

The experimental design results clearly demonstrated a wide range of unusually stable operating conditions for a phosphating solution with alkali metal ions below pH 3.5 and unexpectedly very constant coating properties. Results phosphating of aluminum alloy 6061 were best at a content of F ^-. Less than 200 ppm and the content of Fe ²⁺ of less than 120 parts per million steel (GGP) On galvanized hot dipping, they were best at a content of F ^- of less than 360 parts per million and the Fe ²⁺ content ^is more than 80 ppm, although the results were, as usual in such comparisons with HGP, worse than for other tested metallic materials. On electrogalvanized steel (EG), they were best at a very low content of PO _4, and when the content of F ^-. Less than 200 parts per million on cold rolled steel (CRS), they were best at a content of F ^- of less than 250 parts per million During prolonged. performance studies, it was confirmed that these operating conditions, as well as the properties of the coating can be maintained almost unchanged for the entire time without changing the bath, but with its continuous replenishment.

The appearance of the coatings was at least good with respect to comparison with phosphate coatings with alkali metal ions used on the market. Nitroguanidine was identified as the best accelerator in all of these studies. Further, the phosphating process with alkali metal ions with slightly modified working conditions for the solutions in accordance with the invention is well suited for industrial application on rolls, parts and wire. The use of a phosphating solution at a significantly lower temperature than usual today for contacting metal surfaces helps to significantly reduce heating costs. The phosphating method proposed here is easier than the methods used today, since it is sufficient to control only the content of all and free acid, but not other bath parameters within short time limits, since the bath behavior is very stable.

Finally, this method is better not only because less heating is required and, therefore, it is cheaper than the methods actually used, but also because the consumption of all chemical compounds of the solution is significantly lower than usual.

Group 8: Examples 112 to 119.

For this study, cold rolled steel panels supplied by Q Panel were used as substrates. Table 9 below lists the bath composition for each modification. Examples 117 to 119 were washed with a final sealant instead of washing with distilled water. CrysCoat UltraSeal is a Chemetall Oakite product based on water, silane and alcohol. The pretreated panels were stained using TGIC polyester powder paint supplied by Rohm & Haas. A single panel label was placed in a salt spray test according to ASTM B 117 for 240 hours. The panels were cleaned with a metal spatula and the amount of paint loss from the mark was measured in mm. All variants were subjected to cross-hatching according to ASTM D 3359 and direct and reverse exposure according to ASTM D 2794. In all cases, the cross-hatching adhesion score was 5V (no loss of adhesion), and no cracking or other paint loss was observed for direct and reverse exposure until 160 psi inch (1.84 kg / m ² ). The panels were pre-treated as follows:

1. Gardoclean S 5206, 3% by volume (approximately 30 g / l), 120-125 ° F (49-52 ° C), 60 seconds of spraying.

2. Rinsing with tap water at room temperature, 30 seconds spraying.

3. Chemical Coating, 86-92 ° F (30-33 ° C).

4. Rinsing with tap water at room temperature, 30 seconds spraying.

5. Rinsing with distilled water, 10 seconds or a final sealant at room temperature, 30 seconds spraying.

6. Oven drying, 225 ° F (107 ° C), 5-10 minutes.

Table 9
The chemical composition of examples 112 to 119 in g / l; cerium nitrate, calculated as Ce; CCU = CrysCoat UltraSeal; * end seal bath Etc. H ₃ PO ₄ Lactic acid Glycolic acid Nitroguanidine NaOH Xie Acrylic acid CCU PH value pr 112 2.2 2.0 - 0.2 1,0 - - - 3.0 Ave 113 2.2 - 1.7 0.2 1.8 - - - 3.0 Ave 114 4.6 - - 0.2 2.1 0.4 - - 2.9 Project 115 4.6 - - 0.2 2.1 0.4 2.0 - 3,1 Project 116 4.3 - - 0.2 1.7 - - - 2,8 Ave 117 4.3 - - 0.2 1.7 - - - 2,8 Ave 117 * - - - - - - - 1.6 * 2.85 * Project 118 4.3 - - 0.2 1.7 - - - 2,8 Project 118 * - - - - - 2.0 * - - 4.3 * Project 119 4.3 - - 0.2 1.7 - - - 2,8 Ave. 119 * - - - - - 2.0 * 2.0 * - 2.9 *

Table 10
Salt spray test results, as well as panel appearance and coating weight Examples Further additives CT score for 240 h, mm displacement The appearance of the panels Coating Weight (g / m ² ) pr 112 Lactic acid 1,0 Flat gray yellow brown 0.02 Ave 113 Glycolic acid 1,2 Flat gray yellow brown 0,07 Ave 114 Nitrate Xie 2.0 Smooth tan 0.01 Project 115 Ce nitrate and acrylic acid 1,2 Mostly smooth, deep golden color 0.14 Project 116 1,5 Smooth tan 0.06 Ave 117 -; optional end seal: CCU 0.3 Smooth tan 0.08 Project 118 -; additional final sealant: Ce nitrate 0.3 Smooth light tan 0.01 Project 119 -; additional final sealant: Ce nitrate and acrylic acid 0.3 Spotted gray to tan 0,07

The panels showed excellent thin coatings of a more or less yellow-brown color and good or even excellent corrosion inhibition. In comparison, the best standard for iron phosphate coating coated with a final chrome sealant achieves a salt spray test rating of 240 hours of 0.2 mm displacement. In the field of avoiding toxic chromium compounds, the results are excellent.

Claims (20)

1. A method for coating metal surfaces with a phosphate coating, comprising contacting the metal surfaces at a temperature not exceeding 45 ° C and at a pH of less than 3.5 with an aqueous acidic phosphating solution or dispersion with alkali metal ions containing at least one compound of at least one phosphorus-containing acid and / or at least one of its derivatives, like esters and salts, with a total content of all types of acids and all their derivatives, like esters and salts, together less than 20 g / l based on 1 mol of the base of orthophosphate, while the content of such phosphorus-containing compounds / ions is at least 50% by weight of all such compounds / ions, at least one ion selected from the group consisting of at least one alkali metal ion and ammonium ion, at least one guanidine-based accelerator in a total amount of 0.01-5 g / l, free fluoride in an amount of from 0.01 to 1 g / l or not containing free fluoride, while the phosphating solution or dispersion contains little or no they contain other heavy metals other than those that will be etched from the metal surface, possibly with the exception of adding Fe ^{2+ ions} , and the resulting coating has a phosphorus content of not more than 8 atomic%, as measured by secondary neutral mass spectroscopy, and its weight is from 0.01 to 0.5 g / m ² . 2. The method according to claim 1, in which the phosphating solution or dispersion contains nitroguanidine as at least one accelerator. 3. The method according to claim 1, in which the phosphating solution or dispersion contains an amount of PO ₄ ^3- ions from 0.1 to 10 g / L. 4. The method according to claim 1, in which the phosphating solution or dispersion contains an amount of SO ₄ ^2- ions from 0.1 to 10 g / L. 5. The method of claim 1, whereby the phosphating solution or dispersion contains an amount of ions NO ₃ ^- from 0.1 to 10 g / l. 6. The method according to claim 1, in which the amount of Fe ^{2+ ions is} added to the phosphating solution or dispersion, preferably in the range from 0.01 to 1 g / L. 7. The method according to claim 1, in which the content of free fluoride in the phosphating solution or dispersion is from 0.01 to 0.2 g / L. 8. The method according to claim 1, in which in the phosphating solution or dispersion the content of at least one guanidine-based accelerator is from 0.05 to 3 g / L. 9. The method according to claim 1, in which the phosphating solution or dispersion further comprises at least one surfactant, in particular when cleaning and phosphating is carried out with the same solution or dispersion, preferably with the amount of all surfactants together from 0.01 to 10 g / l. 10. The method according to claim 1, wherein the phosphating solution or dispersion further comprises at least one solvent like propylene glycol and / or glycol ether, at least one biocide, at least one stabilizing agent for surface an active substance, like a condensed sulfonic acid salt, at least one stabilizing agent for an accelerator, like a fine silicate, clay or clay-like material, and / or at least one stabilizing agent for a solution and and the dispersion itself like biopolymer. 11. The method according to claim 1, wherein the phosphatized coating exhibits a colorless, slightly colored silvery, yellowish, golden, tan, yellowish-reddish and / or bluish color. 12. The method according to claim 1, in which a clean, cleaned and / or etched metal surface is subjected to contact with the solution, respectively, of the dispersion. 13. The method according to claim 1, in which the metal surface is brought into contact with the solution, respectively, by dispersion by immersion, spraying, phosphating in steam, coating by rolling and / or removing moisture with a rubber roller. 14. The method according to claim 1, in which the coated metal surface is dried after contact with the solution, respectively, dispersion, or after at least one of the subsequent stages after washing, air drying, drying in an oven and / or infrared drying, in particular at temperatures from 20 to 250 ° C. 15. The method according to claim 1, in which at least two coatings are applied one after another on a metal surface, where at least one of them is applied using a phosphating solution, respectively, of a dispersion, and where at least , one further coating may possibly be applied using a chemically interacting coating solution, like phosphating with zinc and / or manganese enrichment. 16. The method according to claim 1, in which first a phosphate coating with alkali metal ions is created on a metal surface, and then a coating selected from the group consisting of a coating by chemical interaction, such as phosphating, is enriched with zinc and / or manganese, stearate coating and organic polymer coating, especially by cold forming. 17. The method according to claim 1, in which the metal surface, consisting mainly of metal materials from aluminum, chromium, titanium and / or zinc, as well as at least one alloy containing aluminum, chromium, copper, iron, magnesium, tin, titanium and / or zinc alloys are coated with a phosphating solution or dispersion. 18. The method according to any one of claims 1 to 17, in which, after coating with a solution according to claim 1, the metal surface is brought into contact with the final sealing solution or dispersion, in particular with the final sealing solution / dispersion containing at least one compound rare earth element, at least one polymer component and / or at least one silane. 19. The use of a coating obtained by the method according to any one of claims 1 to 18 for short-term passivation, for pretreatment before at least one subsequent process of applying a layer of paint, a layer of any other organic coating and / or adhesive coating, as a lubricant carrier or as one of a lubricating coating, for example, before cold forming. 20. The use of a coating obtained by the method according to any one of claims 1 to 18, for inhibiting corrosion and / or lubrication of metal surfaces, in particular for use in the aerospace industry, automotive industry, rail transport, shipbuilding, metal forming, metal processing - machine processing and grinding, metal containers, and especially in the production of containers, the production of rolls, for the deposition of metal sheets, the production of wire, devices, shells, mechanisms and structures of buildings .

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