EP0958402A1

EP0958402A1 - Zinc phosphating with integrated subsequent passivation

Info

Publication number: EP0958402A1
Application number: EP97924957A
Authority: EP
Inventors: Jürgen Geke; Peter Kuhm; Bernd Mayer
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 1996-05-28
Filing date: 1997-05-20
Publication date: 1999-11-24
Also published as: ZA974617B; KR20000016128A; TR199802438T2; WO1997045568A1; US20020011281A1; HUP9903963A2; DE19621184A1; CZ389298A3; BR9709493A; CA2256695A1; SK162698A3; JP2001509840A; AR007310A1; HUP9903963A3; AU3027597A; CN1219982A; AU712640B2; RU2179198C2; PL330013A1; JP3725171B2

Abstract

A process for phosphating the surface of steel, galvanised or alloy-galvanised steel, aluminium and/or aluminium-magnesium alloys, in which the phosphating solution contains 0.2 to 3 g/l zinc ions, 3 to 50 g/l phosphate ions calculated as PO4, 0.001 to 4 g/l manganese ions, 0.001 to 0.5 g/l of one or more polymers selected from among polyethers, polycarboxylates, polymeric phosphonic acids, polymeric phosphino carboxylic acids and nitrogen-containing organic polymers and one or more accelerators. Preferred polymers are amino group-containing poly(vinyl phenol) derivatives.

Description

"Zinc phosphating with integrated post-passivation"

The invention relates to processes for phosphating metal surfaces with aqueous, acidic phosphating solutions which contain zinc, manganese and phosphate ions as well as up to 0.5 g / l of organic polymers. Furthermore, the invention relates to the use of such methods as pretreatment of the metal surfaces for a subsequent coating, in particular an electro-dip coating or a powder coating. The method can be used to treat surfaces made of steel, galvanized or alloy-galvanized steel, aluminum, aluminum-magnesium alloys, aluminized or alloy-aluminized steel and avoids the passivating rinsing that was previously required.

The phosphating of metals pursues the goal of producing metal phosphate layers which are firmly adhered to the metal surface and which in themselves improve the resistance to corrosion and, in conjunction with lacquers or other organic coatings, contribute to a substantial increase in lacquer adhesion and resistance to infiltration Corrosion stress contribute. Such phosphating processes have long been known. The low-zinc phosphating processes, in which the phosphating solutions have comparatively low contents of zinc ions of, for example, 0.5 to 2 g / l, are particularly suitable for the pretreatment before painting, in particular electrocoating. An essential parameter in these low-zinc phosphating baths is the weight ratio nis phosphate ions to zinc ions, which is usually in the range greater than 8 and can assume values up to 30.

It has been shown that by using other polyvalent cations in the zinc phosphating baths, phosphate layers with significantly improved corrosion protection and paint adhesion properties can be formed. For example, find low-zinc processes with the addition of e.g. 0.5 to 1.5 g / 1 manganese and e.g. 0.3 to 2.0 g / l of nickel ions as a so-called trication process for the preparation of metal surfaces for painting, for example for the cathodic electrodeposition of car bodies, widely used.

Since nickel and the alternative cobalt are also classified as critical from a toxicological and wastewater technical point of view, there is a need for phosphating processes which have a similar level of performance to the trication processes, but with significantly lower bath concentrations of nickel and / or cobalt and preferably without these two metals get along.

A phosphating solution is known from DE-A-20 49 350 which contains 3 to 20 g / 1 phosphate ions, 0.5 to 3 g / 1 zinc ions, 0.003 to 0.7 g / 1 cobalt ions or 0.003 to as essential components 0.04 g / 1 copper ions or preferably 0.05 to 3 g / 1 nickel ions, 1 to 8 g / 1 magnesium ions, 0.01 to 0.25 g / 1 nitrite ions and 0.1 to 3 g / 1 fluorine ions and / or contains 2 to 30 g / 1 chlorine ion. This method accordingly describes zinc-magnesium phosphating, the phosphating solution additionally containing one of the ions cobalt, copper or preferably nickel. Such a zinc-magnesium phosphating could not prevail in technology.

EP-B-18 841 describes a chlorate-nitrite-accelerated zinc phosphating solution containing, inter alia, 0.4 to 1 g / 1 zinc ion, 5 to 40 g / 1 phosphate ion and optionally at least 0.2 g / 1, preferably 0.2 to 2 g / 1, of one or more ions selected from nickel, cobalt, calcium and manganese. Accordingly, the optional manganese, nickel or cobalt content is at least 0.2 g / 1. In the exemplary embodiments, nickel contents of 0.53 and 1.33 g / 1 are given.

EP-A-459 541 describes phosphating solutions which are essentially free of nickel and which, in addition to zinc and phosphate, contain 0.2 to 4 g / 1 manganese and 1 to 30 mg / l copper. DE-A-42 10 513 discloses nickel-free phosphating solutions which, in addition to zinc and phosphate, contain 0.5 to 25 mg / l of copper ions and hydroxylamine as an accelerator. These phosphating solutions optionally contain an additional 0.15 to 5 g / l of manganese.

German patent application DE 196 06 017.6 describes a heavy metal-reduced phosphating solution which contains 0.2 to 3 g / 1 zinc ions, 1 to 150 mg / 1 manganese ions and 1 to 30 mg / 1 copper ions. Optionally, this phosphating solution can contain up to 50 mg / 1 nickel ions and up to 100 mg / 1 cobalt ions. Another optional ingredient is lithium ions in amounts between 0.2 and 1.5 g / 1.

German patent application DE 195 38 778.3 describes the control of the layer weight of phosphate layers by using hydroxylamine as an accelerator. The use of hydroxylamine and / or its compounds to influence the shape of the phosphate crystals is known from a number of published documents. EP-A-315 059 specifies the special effect of the use of hydroxylamine in phosphating baths in the fact that the phosphate crystals still form in steel in a desired columnar or knot-like form when the zinc concentration in the phosphating bath Zinc process exceeds the usual range. This makes it possible to operate the phosphating baths with zinc concentrations of up to 2 g / 1 and with weight ratios of phosphate to zinc down to 3.7. About advantageous No cate combinations of these phosphating baths are given, but nickel is used in all cases in the patent examples. Nitrates and nitric acid are also used in the patent examples, even if the description does not recommend the presence of nitrate in large amounts. The required hydroxylamine concentration is given as 0.5 to 50 g / 1, preferably 1 to 10 g / 1. The maximum concentration of hydroxylammonium sulfate in the patent examples is 5 g / 1, from which a content of hydroxylamine of 2.08 g / 1 is calculated. (Hydroxylammonium sulfate contains 41.5% by weight hydroxylamine). The phosphating solution is sprayed onto the steel surfaces. The document does not mention the problems with immersion processes, which lead to phosphate layers with significantly higher layer weights, which are undesirable as a basis for subsequent painting.

WO 93/03198 teaches the use of hydroxylamine as an accelerator in trication phosphating baths with zinc contents between 0.5 and 2 g / 1 and nickel and manganese contents of 0.2 to 1.5 g / 1 each, with certain Ge weight ratios between zinc and the other divalent cations are to be observed. Furthermore, these baths contain 1 to 2.5 g / 1 of a "hydroxylamine accelerator", which according to the description means salts of hydroxylamine, preferably hydroxylammonium sulfate. If this information is converted to free hydroxylamine, hydroxyl lamin contents between 0.42 and 1.04 g / 1 are provided.

In order to improve the corrosion protection provided by the phosphate layer, a so-called passivating rinsing, also called post-passivation, is generally carried out in technology. Treatment baths containing chromic acid are still widely used for this purpose. For reasons of work and environmental protection, however, there is a tendency to replace these chromium-containing passivation baths with chromium-free treatment baths. For this purpose, for example, organic-reactive bathroom solutions with com- known plexifying substituted poly (vinylphenols). For example, such compounds are described in DE-C-31 46 265. Particularly effective polymers of this type contain amine substituents and can be obtained by a Mannich reaction of poly (vinylphenols) with aldehydes and organic amines. Such polymers are described, for example, in EP-B-91 166, EP-B-319 016 and EP-B-319 017. Polymers of this type are also used in the context of the present invention, so that the content of the above-mentioned four documents expressly states The content of the disclosure of the present patent request is made. Furthermore, the passivating rinsing solutions can contain polymers containing amino groups in which the amine group is bonded directly to the polymer chain without the interposition of an aromatic ring. Such polymers, which can also be used in the context of the present invention, are described in DE-A-44 09 306.

In conjunction with a passivating rinse, the currently low-zinc phosphating baths meet the corrosion protection requirements that are made in automobile construction. However, this sequence of processes has the disadvantage that the passivating rinsing represents a separate treatment stage, which extends the production time and which increases the space requirement of the pretreatment line.

The invention has for its object to provide a phosphating solution that meets the corrosion protection requirements of the automotive industry and in which the passivating rinsing can be omitted. This reduces the space requirement of the pretreatment line and possibly the production time.

It is already known from the literature to add phosphating solutions to polyacrylic acids. Examples include the article by JI Wragg, JE Chamberlain, L. Chann, HW White, T. Sugama, and S. Manalis: "Characterization of Polyacrylic Acid Modified Zinc Phosphate Crystal Conversion Coatings", Journal of Applied Polymer Science, Vol. 50, 917-928 (1993). Here, however, model-like zinc phosphating solutions were investigated which differ significantly from those currently used in practice: they contain higher levels of zinc, on the other hand, the widely used manganese and, as a rule, the accelerators currently used are missing. They are therefore not a model for the low-zinc phosphating solutions used in the context of the present invention.

The object is achieved by a method for phosphating metal surfaces made of steel, galvanized or galvanized alloy steel and / or aluminum, in which the metal surfaces are sprayed or dipped for a time between 3 seconds and 8 minutes with a zinc-containing phosphating solution brings into contact, characterized in that the phosphating solution

0.2 to 3 g / 1 zinc ions

3 to 50 g / 1 phosphate ions, calculated as P0 ₄ , 0.001 to 4 g / 1 manganese ions,

0.001 to 0.5 g / 1 of one or more polymers selected from polyethers, polycarbonate, polymeric phosphonic acids, polymeric phosphinocarboxylic acids and nitrogen-containing organic polymers and one or more accelerators selected from

0.3 to 4 g / 1 chlorate ions,

0.01 to 0.2 g / 1 nitrite ion,

0.05 to 2 g / 1 m-nitrobenzenesulfonate ions,

0.05 to 2 g / 1 m nitrobenzoate ions,

0.05 to 2 g / 1 p-nitrophenol,

0.005 to 0.15 g / 1 hydrogen peroxide in free or bound form,

0.1 to 10 g / 1 hydroxylamine in free or bound form, Contains 0.1 to 10 g / 1 of a reducing sugar.

The zinc concentration is preferably in the range between about 0.3 and about 2 g / 1 and in particular between about 0.8 and about 1.6 g / 1. Zinc levels above 1.6 g / 1, for example between 2 and 3 g / 1, bring only minor advantages for the process, but on the other hand can increase the amount of sludge in the phosphating bath. Such zinc contents can occur in a working phosphating bath if, during the phosphating of galvanized surfaces, additional zinc gets into the phosphating bath as a result of the pickling removal. Nickel and / or cobalt ions in the concentration range from about 1 to about 50 mg / 1 for nickel and about 5 to about 100 mg / 1 for cobalt improve in conjunction with the lowest possible nitrate content of not more than about 0. 5 g / 1 corrosion protection and paint adhesion to phosphating baths which do not contain nickel or cobalt or which have a nitrate content of more than 0.5 g / 1. This achieves a favorable compromise between the performance of the phosphating baths on the one hand and the requirements for the wastewater treatment of the rinsing water on the other hand.

In the case of phosphate baths reduced in heavy metals, the manganese content can be in the range from about 0.001 to about 0.2 g / l. Otherwise, manganese contents of about 0.5 to about 1.5 g / l are common.

From the German patent application with the file number 195 00 927.4 it is known that lithium ions in the quantity range from about 0.2 to about 1.5 g / l improve the corrosion protection which can be achieved with zinc phosphating baths. Lithium contents in the quantity range from 0.2 to about 1.5 g / 1 and in particular from about 0.4 to about 1 g / 1 also have a favorable effect on the corrosion protection achieved in the phosphating process according to the invention with integrated post-passivation. In addition to the cations mentioned above, which are incorporated into the phosphate layer or which at least have a positive effect on the crystal growth of the phosphate layer, the phosphating baths generally contain sodium, potassium and / or ammonium ions to adjust the free acid. The term free acid is familiar to the person skilled in the phosphating field. The method of determining free acid and total acid chosen in this document is given in the example section. Free acid and total acid represent an important control parameter for phosphating baths because they have a great influence on the layer weight. Values of the free acid between 0 and 1.5 points in the case of partial phosphating, in the case of band phosphating up to 2.5 points and the total acid between about 15 and about 30 points are within the industrially customary range and are suitable for the purposes of this invention.

In phosphating baths which are said to be suitable for different substrates, it has become customary to add free and / or complex-bound fluoride in amounts of up to 2.5 g / 1 total fluoride, of which up to 1 g / 1 free fluoride. The presence of such amounts of fluoride is also advantageous for the phosphating baths according to the invention. In the absence of fluoride, the aluminum content of the bath should not exceed 3 mg / 1. In the presence of fluoride, higher Al contents are tolerated as a result of the complex formation, provided the concentration of the non-complexed Al does not exceed 3 mg / 1. The use of fluoride-containing baths is therefore advantageous if the surfaces to be phosphated consist at least partially of aluminum or contain aluminum. In these cases, it is advantageous not to use complex-bound fluoride, but only free fluoride, preferably in concentrations in the range from 0.5 to 1.0 g / l.

For the phosphating of zinc surfaces, it would not be absolutely necessary that the phosphating baths contain so-called accelerators. For the phosphating of steel surfaces, however, it is necessary that the phosphating solution contains one or more accelerators. Such accelerators are known in the prior art as components of zinc phosphating baths. These are understood to mean substances which chemically bind the hydrogen produced by the pickling attack of the acid on the metal surface by reducing them themselves. Oxidizing accelerators also have the effect of oxidizing released iron (II) ions to the trivalent stage by pickling on steel surfaces, so that they can precipitate out as iron (III) phosphate.

The phosphating baths according to the invention can contain one or more of the following components as accelerators:

0.3 to 4 g / 1 chlorate ions,

0.01 to 0.2 g / 1 nitrite ion,

0.05 to 2 g / 1 m-nitrobenzenesulfonate ions,

0.05 to 2 g / 1 m nitrobenzoate ions,

0.05 to 2 g / 1 p-nitrophenol,

0.005 to 0.15 g / 1 hydrogen peroxide in free or bound form,

0.1 to 10 g / 1 hydroxylamine in free or bound form,

0.1 to 10 g / 1 of a reducing sugar

When phosphating galvanized steel, it is necessary that the phosphate solution contains as little nitrate as possible. Nitrate concentrations of 0.5 g / 1 should not be exceeded, since at higher nitrate concentrations there is a risk of so-called "speck formation". This means white, crater-like defects in the phosphate layer. In addition, the paint adhesion on galvanized surfaces is impaired.

The use of nitrite as an accelerator leads to technically satisfactory results, in particular on steel surfaces. For reasons of occupational safety (risk of developing nitrous gases), however, it is Recommended to avoid nitrite as an accelerator. For phosphating galvanized surfaces, this is also advisable for technical reasons, since nitrite can form nitrate, which, as explained above, can lead to the problem of speck formation and to reduced paint adhesion on zinc.

Hydrogen peroxide is preferred for reasons of environmental friendliness, and hydroxylamine is particularly preferred as an accelerator for technical reasons because of the simplified formulation options for replenishing solutions. However, it is not advisable to use these two accelerators together, since hydroxylamine is decomposed by hydrogen peroxide. If hydrogen peroxide in free or bound form is used as an accelerator, concentrations of 0.005 to 0.02 g / l of hydrogen peroxide are particularly preferred. The hydrogen peroxide can be added as such to the phosphating solution. However, it is also possible to use hydrogen peroxide in bound form as compounds which give hydrogen peroxide in the phosphating bath by hydrolysis reactions. Examples of such compounds are persalts such as perborates, percarbonates, peroxosulfates or peroxodisulfates. Ionic peroxides, such as, for example, alkali metal peroxides, are suitable as further sources of hydrogen peroxide. A preferred embodiment of the invention is that a combination of chlorate ions and hydrogen peroxide is used in the phosphating in the immersion process. In this embodiment, the concentration of chlorate can be, for example, in the range from 2 to 4 g / l, the concentration of hydrogen peroxide in the range from 10 to 50 ppm.

The use of reducing sugars as accelerators is known from US-A-5 378 292. In the context of the present invention, they can be used in amounts between about 0.01 and about 10 g / 1, preferably in amounts between about 0.5 and about 2.5 g / 1. Examples of such sugars are galactose, mannose and especially glucose (dextrose). A further preferred embodiment of the invention consists in using hydroxylamine as accelerator. Hydroxylamine can be used as a free base, as a hydroxylamine complex, as an oxime, which is a condensation product of hydroxylamine with a ketone, or in the form of hydroxylammonium salts. If free hydroxylamine is added to the phosphating bath or a phosphating bath concentrate, it will largely exist as a hydroxylammonium cation due to the acidic nature of these solutions. When used as a hydroxylammonium salt, the sulfates and the phosphates are particularly suitable. In the case of the phosphates, the acid salts are preferred because of their better solubility. Hydroxylamine or its compounds are added to the phosphating bath in amounts such that the calculated concentration of the free hydroxylamine is between 0.1 and 10 g / 1, preferably between 0.3 and 5 g / 1. It is preferred that the phosphating baths contain hydroxylamine as the only accelerator, at most together with a maximum of 0.5 g / l of nitrate. Accordingly, in a preferred embodiment, phosphating baths are used which do not contain any of the other known accelerators such as, for example, nitrite, oxo anions of halogens, peroxides or nitrobenzenesulfonate. As a positive side effect, hydroxylamine concentrations above about 1.5 g / l reduce the risk of rust formation at insufficiently flooded areas of the components to be phosphated.

When the phosphating process is used on steel surfaces, iron dissolves in the form of iron (II) ions. If the phosphating baths according to the invention do not contain any substances which have an oxidizing effect on iron (II), the divalent iron only changes to the trivalent state as a result of air oxidation, so that it can precipitate out as iron (III) phosphate. This is the case, for example, when using hydroxylamine. Therefore, iron (II) contents can be built up in the phosphate baths that are significantly higher than the contents that contain baths containing oxidizing agents. In this sense, iron (II) - Concentrations of up to 50 ppm normal, although values of up to 500 ppm can also appear in the production process for a short time. Such iron (II) concentrations are not detrimental to the phosphating process according to the invention. When prepared in hard water, the phosphating baths can also contain the hardness-forming cations Mg (II) and Ca (II) in a total concentration of up to 7 mmol / 1. Mg (II) or Ca (II) can also be added to the phosphating bath in amounts of up to 2.5 g / l.

The weight ratio of phosphate ions to zinc ions in the phosphating baths can vary within a wide range, provided that it is in the range between 3.7 and 30. A weight ratio between 10 and 20 is particularly preferred. For the indication of the phosphate concentration, the total phosphorus content of the phosphating bath is considered to be present in the form of phosphate ions PO ^ ^"

Calculation of the quantity ratio ignores the known fact that at the pH values of the phosphating baths, which are usually in the range from about 3 to about 3.6, only a very small part of the phosphate is actually in the form of the triple negatively charged anions. At these pH values, it is rather to be expected that the phosphate is present primarily as a single negatively charged dihydrogen phosphate anion, together with smaller amounts of undissociated phosphoric acid and double negatively charged hydrogen phosphate anions.

The organic polymers to be used according to the invention preferably have molecular weights (which can be determined, for example, by gel permeation chromatography) in the range from about 500 to about 50,000, in particular from about 800 to about 20,000.

The phosphating baths preferably contain the organic polymers in a concentration between about 0.01 and about 0.1 g / l. At lower concentrations the desired passivating effect occurs less and less. Higher concentrations no longer significantly increase the effect and are therefore becoming increasingly uneconomical.

The polymers which can be used in the sense of the invention can belong to different chemical groups. However, they have in common that they carry oxygen atoms and / or nitrogen atoms either in the polymer chain or in side groups. The simplest polymers of this type are polyalkylene glycols, for example polyethylene or polypropylene glycols, which preferably have a molecular weight in the range from 500 to 10,000. Polymeric carboxylic acids such as, for example, homo- or copolymers of acrylic acid, methacrylic acid and maleic acid are also suitable. Polymeric phosphonic acids or polymeric phosphinocarboxylic acids are also suitable. Examples include a polyphosphinocarboxylic acid which can be regarded as an acrylic acid-sodium hypophosphite copolymer and is commercially available as "Belclene 500" from FMC Corporation, Great Britain.

Furthermore, the organic polymers can be selected from homo- or copolymer compounds containing amino groups

Structural units of the general formula (I)

- CH ₂ - CH -

(D

/ \

R2 C - R ¹

and also contain or consist of their hydrolysis products, where R and R are identical or different from one another and for hydrogen or alkyl having 1 to 6 carbon atoms, for. B. methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, amyl, n-hexyl, isohexyl or diclohexyl. A detailed list of polymers of this type can be found in DE-A-44 09 306, the content of which is hereby expressly made part of this disclosure. Specific examples are hydrolysis products of homo- and copolymers of N-vinylformamide, N-vinyl-N-methylformamide, N-vinylacetamide, N- vinyl-N-methylacetamide, N-vinyl-N-ethylacetamide, N-vinylpropionamide and N- Vinyl-N-methylpropionamide, with N-vinylformamide being preferred as being very easily hydrolyzable. Suitable comonomers are monoethylenically unsaturated carboxylic acids having 3 to 8 carbon atoms and the water-soluble salts of these monomers.

Furthermore, the organic polymers can be selected from poly-4-vinylphenol compounds of the general formula (II),

where n is a number between 5 and 100, x are independently hydrogen and / or CRR, OH groups in which R and R are hydrogen, aliphatic and / or aromatic radicals having 1 to 12 carbon atoms.

These polymers are described as separate rinse solutions in DE-C-31 46 265. According to this teaching, those poly-4-vinylphenol compounds are particularly suitable in which at least 1 x = CH ₂ OH. A method for their production is specified in the document mentioned.

Organic polymers which are selected from homo- or copolymer compounds containing amino groups, comprising at least one polymer selected from the group consisting of a), b), c) or d), in which: a) a polymeric material comprising at least one unit of the formula:

in which: Rι to R _{3 are} independently selected for each of the units from the group consisting of hydrogen, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 18 carbon atoms;

Y 1 to Y _{4 are selected} independently for each of the units from the group consisting of hydrogen, -CRuRjORe, -CH ₂ C1 or an alkyl or aryl group with 1 to 18 carbon atoms or Z:

* 7

R8

However, at least one fraction of the Y _b Y ₂ , Y ₃ or Y _{4 of} the homo- or copolymer compound or material must be Z: R ₅ to R _{12 are selected} independently for each of the units from the group consisting of from hydrogen, an alkyl, ary, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R _I2 can also be -O or -OH;

W] is independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxypropyl; 3-benzyloxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxy-propyl-; 2-hydroxyoctyl; 2-hydroxyalkyl-; 2-hydroxy-2-phenylethyl-; 2-hydroxy-2-alkylphenylethyl-; Benzyl; Methyl-; Ethyl; Propyl; Alkyl; Allyl; Alkylbenzyl; Haloalkyl-; Haloalkenyl; 2-chloropropenyl; Sodium; Potassium; Tetraaryl ammonium; Tetraalkylammonium; Tetraalkylphosphonium; Tetr aarylphosphonium or a condensation product of ethylene oxide, propylene oxide or a mixture or a copolymer thereof; b) comprises: a polymer material with at least one unit of the formula:

wherein:

R] to R _{2 are} independently selected for each of the units from the group consisting of hydrogen, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 18 carbon atoms;

Y. to Y _{3 are} independently selected for each of the units from the group consisting of hydrogen, -CR ^ OR «;, -CH ₂ C1 or an alkyl or aryl group having 1 to 18 carbon atoms or Z:

but at least one fraction of the Y ,, Y ₂ or Y _{3 of} the final compound must be Z; R ₄ to R _{12 are selected} independently for each of the units from the group consisting of hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R ₁₂ can also be -0 ^(I) or -OH; W _{2 is} independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxypropyl; 3-benzyloxy-2-hydroxy-propyl-; 3-alkylbenzyloxy-2-hydroxypropyl; 3-phenoxy-2-hydroxypropyl; 3-alkylphenoxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxyoctyl; 2-hydroxylalkyl-; 2-hydroxy-2-phenylethyl-; 2-hydroxy-2-alkylphenylethyl-; Benzyl; Methyl-; Ethyl; Propyl; Alkyl; Allyl; Alkylbenzyl; Haloalkyl-; Haloalkenyl; 2-chloropropenyl or a condensation product of ethylene oxide, propylene oxide or a mixture thereof; c) comprises: a copolymer material, wherein at least a portion of the copolymer has the structure

and has at least one fraction of said part with one or more mo is polymerized, which are independently selected for each unit from the group consisting of acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl methyl ketone, isopropenyl methyl ketone, acrylic acid, methacrylic acid, acrylamide, methacrylamide, n-amyl methacrylate, styrene, m-bromostyrene , p-bromostyrene, pyridine, diallyldimethylammonium salts, 1,3-butadiene, n-butyl acrylate, tert-butylaminoethyl methacrylate, n-butyl methacrylate, in part. Butyl methacrylate, n-butyl vinyl ether, tert-butyl vinyl ether, m-chlorostyrene, o-chlorostyrene, p-chlorostyrene, n-decyl methacrylate, N, N-diallymelamine, N, N-di-n-butylacrylamide, di-n-butyl itaconate , Di-n-butyl maleate, diethylaminoethyl methacrylate, diethylene glycol monovinyl ether, diethyl fumarate, diethyl itaconate, diethyl vinyl phosphate, vinyl phosphonic acid, diisobutyl maleate, diisoproyl itaconate, diisopropyl maleate, dimethyl fumarate, dimethyl malacylate malate, diethyl naphthalate, diethyl propyl malateate, dimethyl itaconate fumarate , Di-n-octyl itaconate, di-n-propyl itaconate, N-dodecyl vinyl ether, acid ethyl fumarate, acid ethyl maleate, ethyl acrylate, ethyl cynamate, N-ethyl methacrylamide, ethyl methacrylate, ethyl vinyl ether, 5-ethyl-2-vinyl pyridine, 5-ethyl-2 -vinylpyridine-l-oxide, glycidyl acrylate, glycidyl methacrylate, n-hexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl methacrylate, isobutyl vinyl ether, isoprene, isoproyl methacrylate, isoproyl vinyl ether, itaconic acid, lauryl methacrylate Methacrylamide, methacrylic acid, methacrylonitrile, N-methylolacrylamide, N-methylolmethacrylamide, N- isobutoxymethylacrylamide, N-isobutoxymethylmethacrylamide, N-

Alkyloxymethylacrylamide, N-alkyloxymethylmethacrylamide, N-vinylcaprolactam, methyl acrylate, N-methylmethacrylamide, α-methylstyrene, m-methylstyrene, o-methylstyrene, p-methylstyrene, 2-methyl 1-5 -vinylpyridine, n-propyl methacrylate, sodium-p -styrene sulfonate, stearyl methacrylate, styrene, p-styrene sulfonic acid, p-styrene sulfonamide, vinyl bromide, 9-vinyl carbazole, vinyl chloride, vinylidene chloride, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyridine-N-oxide, 4 Vinyl pyrimidine, N-vinyl pyrrolidone; and W _b Y] -Y ₄ and R] -R _{3 are} as described under a); d) comprises a condensation polymer from the polymeric materials a), b) or c), a condensable form of a), b), c) or a mixture thereof being condensed with a second compound which is selected from the group be¬ consisting of phenols, tannins, novolak resins, lignin compounds, together with aldehydes, ketones or mixtures thereof, in order to produce a condensation resin product, the condensation resin product being added by adding “Z” to at least a part thereof Reaction of the resin product with 1) an aldehyde or ketone 2) a secondary amine then reacts further, with the formation of a final adduct which can react with an acid

Processes for the production of such polymers are described in the already mentioned publications EP-B-319 016 and EP-B-319 017. Polymers of this type are kön¬ nen obtained from Henkel Corporation, Parker amchen Division, USA under the trade names Parcolene ^® 95C, Deoxylyte ^® 90A, 95 A, 95 AT, 100NC and TD-1355-CW.

In particular, those polymers are preferred in which at least one fraction of the groups Z of the organic polymer has a polyhydroxyalkylamine functionality which results from the condensation of an amine or of ammonia with a ketose or aldose which has 3 to 8 carbon atoms. The condensation products can, if desired, have been reduced to the amine.

Further examples of such polymers are condensation products of a polyvinylphenol with formaldehyde or paraformaldehyde and with a secondary organic amine. It is preferable to start from polyvinylphenols with a molecular weight in the range from about 1,000 to about 10,000. Condensation products in which the secondary organic amine is selected from methylethanolamine and N-methylglucamine are particularly preferred. In the specified concentration ranges, the organic polymers in the phosphating baths are stable and do not lead to precipitation. They also do not show any negative effect on the layer formation, for example they do not lead to passivation phenomena on the metal surface which could hinder the growth of the phosphate crystals.

Furthermore, the organic polymers can be selected from substituted polyalkylene derivatives with the structural units

- (CR'R ² ) _X CR '

Y

where R ¹ , R, R ^{3 can} independently be hydrogen or a methyl or ethyl group, x = 1, 2, 3 or 4 and

Y represents a substituent which contains at least one nitrogen atom which is incorporated in an alkylamine group or in a mono- or polynuclear saturated or unsaturated heterocycle.

Polymers in which R ¹ , R ² , R ^{3 are} each hydrogen are preferred. Preferably x = 1. Accordingly, polymers which are substituted polyethylenes are particularly preferred. Organic polymers which contain one or more of the following structural units are particularly preferred:

In a further preferred embodiment, the organic polymers are polymeric sugar derivatives containing amino groups. An example of this are chitosans which can contain, for example, the following structural group:

It applies to all nitrogen-containing organic polymers that at least a part of the nitrogen atoms is protonated at the pH values of the phosphating solution and therefore carries a positive charge.

Phosphating baths are usually sold in the form of aqueous concentrates which are adjusted to the application concentrations on site by adding water. For reasons of stability, these concentrates can contain an excess of free phosphoric acid, so that when diluted to a bath concentration, the value of the free acid is initially too high or the pH is too low. By adding alkalis such as sodium hydroxide, sodium carbonate or ammonia, the value of the free acid is reduced to the desired range. Furthermore, it is known that the free acid content during the use of the phosphating baths due to the consumption of the layer-forming cations and given may increase over time due to decomposition reactions of the accelerator. In these cases it is necessary to adjust the value of the free acid to the desired range from time to time by adding alkalis. This means that the contents of the alkali metal or ammonium ions in the phosphating baths can vary within wide limits and tend to increase over the course of the useful life of the phosphating baths due to the bluntness of the free acid. The weight ratio of alkali metal and / or ammonium ions to zinc ions, for example, can therefore be very low in freshly prepared phosphating baths, for example <0.5 and in extreme cases even 0, while it usually increases over time as a result of bath maintenance measures, so that Ratio> 1 and can assume values up to 10 and larger. Low-zinc phosphate baths generally require the addition of alkali metal or ammonium ions in order to free the acid on the desired weight ratio PO ^ ^" : Zn> 8

Setpoint range. Analogous considerations can also be made regarding the proportions of alkali metal and / or ammonium ions to other bath components, for example phosphate ions.

In the case of lithium-containing phosphating baths, the use of sodium compounds to adjust the free acid is preferably avoided, since the high sodium concentrations suppress the beneficial effect of lithium on the corrosion protection. In this case, basic lithium compounds are preferably used to adjust the free acid. In the alternative, potassium compounds are also suitable.

In principle, it does not matter in what form the layer-forming or layer-influencing cations are introduced into the phosphating baths. However, nitrates should be avoided in order not to exceed the preferred upper limit of the nitrate content. The metal ions are preferably used in the form of those compounds which do not introduce any foreign ions into the phosphating solution. Therefore it is on cheapest to use the metals in the form of their oxides or their carbonates. Lithium can also be used as a sulfate.

Phosphating baths according to the invention are suitable for phosphating surfaces made of steel, galvanized or alloy-galvanized steel, aluminum, aluminized or alloy-aluminized steel and aluminum-magnesium alloys. The term "aluminum" includes the technically customary aluminum alloys such as AlMgO, 5Sil, 4. The materials mentioned - as is becoming increasingly common in automobile construction - can also be present side by side.

Parts of the body can also consist of material that has already been pretreated, such as is produced, for example, by the Bonazink process. The base material is first chromated or phosphated and then coated with an organic resin. The phosphating process according to the invention then leads to phosphating on damaged areas of this pretreatment layer or on untreated rear sides.

The method is suitable for use in immersion, spraying or spray / immersion processes. It can be used in particular in automobile construction, where treatment times between 1 and 8 minutes, in particular 2 to 5 minutes, are common. However, use in strip phosphating in a steel mill, with treatment times between 3 and 12 seconds, is also possible. When used in tape phosphating processes, it is advisable to set the bath concentrations in the upper half of the ranges preferred according to the invention. For example, the zinc content can range from 1.5 to 2.5 g / l and the free acid content can range from 1.5 to 2.5 points. A particularly suitable substrate for the strip phosphating is galvanized steel, in particular electrolytically galvanized steel. As is also common with other phosphating baths of the prior art, the suitable bath temperatures are between 30 and 70 ° C. regardless of the field of application, the temperature range between 45 and 60 ° C. being preferred.

The phosphating process according to the invention is intended in particular for treating the metal surfaces mentioned before painting, for example before cathodic electrocoating, as is customary in automobile construction. It is also suitable as a pretreatment before a powder coating, such as is used for household appliances. The phosphating process is to be seen as a sub-step of the technically usual pretreatment chain. In this chain, the steps of cleaning / degreasing, rinsing and activating are usually preceded by the phosphating, the activation usually being carried out with activating agents containing titanium phosphate.

Execution examples

The phosphating processes and comparative processes according to the invention were checked on steel sheets ST 1405, as are used in automobile construction. The following process, which is common in body production, was carried out as an immersion process:

1. Clean with an alkaline cleaner (Ridoline ^ 1501, Henkel KGaA), approach 2% in city water, 55 ° C, 4 minutes.

2. Rinse with city water, room temperature, 1 minute.

3. Activation with an activating agent containing titanium phosphate (Fixodine ^ 950, Henkel KGaA), approach 0.1% in deionized water, room temperature, 1 minute.

4. Phosphating with phosphating baths with the following composition: 1.0 g / l Zn ^{2+ 1.0} g / l Mn ²⁺

0.1 g / l Fe ²⁺

14 g / 1 PO ₄ ^{3 '}

0.95 g / 1 SiF ₆ ^{2 "}

0.2 g / 1 F

1.7 g / 1 (NH ₃ OH) ₂ SO ₄

Polymer according to the table.

In addition to the cations mentioned, the nitrate-free phosphating baths contained sodium ions to adjust the free acid if necessary.

The score of the free acid betmg 0.9, the total acid 23; the pH 3.35. Under the free acid score, the consumption in ml of 0.1- understood normal sodium hydroxide solution to titrate 10 ml bath solution up to a pH value of 3.6. Similarly, the total acid score indicates consumption in ml up to a pH of 8.2.

5. Rinse with deionized water.

6. Blow dry with compressed air

The mass per unit area ("layer weight") was determined by dissolving in 5% chromic acid solution in accordance with DIN 50942. It is given in the table.

The phosphated test panels were coated with a cathodic dip coating from BASF (FT 85-7042). The corrosion protection effect was tested in an alternating climate test according to VDA 621-415 over 9 rounds. As a result, the paint infiltration at the Ritz (half the Ritz width) is included in the table.

Table: Phosphating baths and phosphating results

'Mannich reaction product of polyvinylphenol (molecular weight 3000, determined by gel permeation chromatography) with paraformaldehyde and glucamine (Parker Amchen, USA) ^**} as above, molecular weight of the polyvinylphenol: 8600.

Claims

Patent claims

1. A process for phosphating metal surfaces made of steel, galvanized or zinc-alloyed steel, aluminum and / or aluminum-magnesium alloys, in which the metal surfaces are sprayed or dipped for a time between 3 seconds and 8 minutes with a zinc-containing phosphating solution brings into contact, characterized in that the phosphating solution

0.2 to 3 g / 1 zinc ions

3 to 50 g / 1 phosphate ions, calculated as PO ₄ , 0.001 to 4 g / 1 manganese ions,

0.001 to 0.5 g / 1 of one or more polymers selected from polyethers, polycarboxylates, polymeric phosphonic acids, polymeric phosphinocarboxylic acids and nitrogen-containing organic polymers and one or more accelerators selected from

0.3 to 4 g / 1 chlorate ions,

0.01 to 0.2 g / 1 nitrite ion,

0.05 to 2 g / 1 m-nitrobenzene, sulfonate ions,

0.05 to 2 g / l m-nitrobenzoate ions,

0.05 to 2 g / 1 p-nitrophenol,

0.005 to 0.15 g / l hydrogen peroxide in free or bound form,

0.1 to 10 g / 1 hydroxylamine in free or bound form,

Contains 0.1 to 10 g / 1 of a reducing sugar.

2. The method according to Anspmch 1, characterized in that the phosphating solution additionally 1 to 50 mg / 1 nickel ions and / or 5 to 100 mg / 1 cobalt ions contains.

3. The method according to one or both of claims 1 and 2, characterized gekenn¬ characterized in that the phosphating solution additionally contains 0.2 to 1.5 g / 1 lithium ions ent.

4. The method according to one or more of claims 1 to 3, characterized gekenn¬ characterized in that the phosphating solution additionally fluoride in amounts of up to 2.5 g / 1 total fluoride, of which up to 1 g / 1 free fluoride, each calculated as F ^" contains.

5. The method according to one or more of claims 1 to 4, characterized gekenn¬ characterized in that the phosphating solution as an accelerator contains 5 to 150 mg / 1 hydrogen peroxide in free or bound form.

6. The method according to one or more of claims 1 to 4, characterized gekenn¬ characterized in that the phosphating solution as accelerator contains 0.1 to 10 g / 1 Hydroxy¬ lamin in free or bound form.

7. The method according to one or more of claims 1 to 6, characterized gekenn¬ characterized in that the phosphating solution contains no more than 0.5 g / 1 nitrate.

8. The method according to one or more of claims 1 to 7, characterized gekenn¬ characterized in that the phosphating solution contains the organic polymers in a concentration between 0.01 and 0.1 g / 1.

9. The method according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the organic polymers polyalkylene glycols with a molecular weight represent in the range of 500 to 10,000.

10. The method according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the organic polymers are selected from amino group-containing homo- or copolymer compounds, the structural units of the general formula (I)

- CH ₂ - CH d)

/ \

R2 C - R ¹

and also contain or consist of their hydrolysis products, where R and R are identical or different from one another and can represent hydrogen or alkyl having 1 to 6 carbon atoms.

1 1. The method according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the organic polymers are selected from poly-4-vinylphenol compounds of the general formula (II),

where n is a number between 5 and 100, x are independently hydrogen and / or CRR, OH groups, in which

R and R, hydrogen, aliphatic and / or aromatic radicals with 1 to 12

Are carbon atoms.

12. The method according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the organic polymers are selected from amino group-containing homo- or copolymer compounds, comprising at least one polymer selected from the group consisting of a) , b), c) or d), wherein: a) comprises a polymer material comprising at least one unit of the formula:

in which:

Rj to R _{3 are} independently selected for each of the units consisting of hydrogen, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 18 carbon atoms;

Yi to Y _{4 are selected} independently for each of the units from the group consisting of hydrogen, -CR, ^ OR ^ -CH ₂ C1 or an alkyl or aryl group with 1 to 18 carbon atoms or Z:

However, at least one fraction of the Y ,, Y ₂ , Y ₃ or Y _{4 of} the homo- or copolymer compound or material must be Z: R ₅ to R _{12 are selected} independently for each of the units from the group consisting of Hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; Rj ₂ can also be -O or -OH;

W _! is independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxypropyl; 3-benzyloxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxyoctyl; 2-hydroxyalkyl-; 2-hydroxy-2-phenylethyl-; 2-hydroxy-2-alkylphenylethyl-; Benzyl; Methyl-; Ethyl; Propyl; Alkyl; Allyl; Alkylbenzyl; Haloalkyl-; Haloalkenyl; 2- chloφropenyl-; Sodium; Potassium; Tetraaryl ammonium; Tetraalkylammonium; Tetraalkylphosphonium; Tetraarylphosphonium or a condensation product of ethylene oxide, propylene oxide or a mixture or a copolymer thereof; b) comprises: a polymer material with at least one unit of the formula:

R2 - C

wherein:

R 1 to R _{2 are} independently selected for each of the units consisting of hydrogen, an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 18 carbon atoms; Yj to Y _{3 are selected} independently for each of the units from the group consisting of hydrogen, -CR ^ OR ^ -CH ₂ C1 or an alkyl or aryl group having 1 to 18 carbon atoms or Z:

is, but must be at least a fraction of Y _b Y ₂ or Y _{3 of} the final compound Z; R to R _{12 are selected} independently for each of the units from the group consisting of hydrogen, an alkyl, aryl, hydroxyalkyl, aminoalkyl, mercaptoalkyl or phosphoalkyl group; R _l2 can also be -O * ^"1 * or be -OH;

W _{2 is} independently selected for each of the units from the group consisting of hydrogen, an acyl, an acetyl, a benzoyl group; 3-allyloxy-2-hydroxypropyl; 3-benzyloxy-2-hydroxy-propyl-; 3-alkylbenzyloxy-2-hydroxy-propyl-; 3-phenoxy-2-hydroxypropyl; 3-alkylphenoxy-2-hydroxypropyl; 3-butoxy-2-hydroxypropyl; 3-alkyloxy-2-hydroxypropyl; 2-hydroxyoctyl; 2-hydroxylalkyl; 2-hydroxy-2-phenylethyl-; 2-hydroxy-2-alkyl-phenylethyl-; Benzyl; Methyl-; Ethyl; Propyl; Alkyl; Allyl; Alkylbenzyl; Haloalkyl-; Haloalkenyl; 2-chloropropenyl or a condensation product of ethylene oxide, propylene oxide or a mixture thereof; c) comprises: a copolymer material, wherein at least a part of the copolymer has the structure

and at least one fraction of said part is polymerized with one or more monomers which are independently selected for each unit from the group consisting of acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl methyl ketone, isopropenyl methyl ketone, Acrylic acid, methacrylic acid, acrylamide, methacrylamide, n-amyl methacrylate, styrene, m-bromostyrene, p-bromostyrene, pyridine, diallyldimethylammonium salts, 1,3-butadiene, n-butyl acrylate, tert-butylaminoethyl methacrylate, n-butyl methacrylate, in part. Butyl methacrylate, n-butyl vinyl ether, tert-butyl vinyl ether, m-chlorostyrene, o-chlorostyrene, p-chlorostyrene, n-decyl methacrylate, N, N-diallymelamine, N, N-di-n-butylacrylamide, di-n-butyl itaconate, di -n-butyl maleate, diethylaminoethyl methacrylate, diethylene glycol monovinyl ether, diethyl fumarate, diethyl itaconate, diethyl vinyl phosphate, vinyl phosphonic acid, diisobutyl maleate, diisoproyl itaconate, diisopropyl maleate, dimethyl fumarate, dimethyl itaconate, n-dimethyl malylumate, non-dimethyl malylumate, n-dimethyl malylumate, n-dimethyl malylumate, n-dimethyl malylumate, n-dimethyl malyl n-fumarate, n-dimethyl malyl fumarate -Octyl itaconate, di-n-propyl itaconate, N-dodecyl vinyl ether, acid ethyl fumarate, acid ethyl maleate, ethyl acrylate, ethyl cinnamate, N-ethyl methacrylamide, ethyl methacrylate, ethyl vinyl ether, 5-ethyl-2-vinyl pyridine, 5-ethyl-2-vinyl vinyl oxide, glycidyl acrylate, glycidyl methacrylate, n-hexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, isobutyl methacrylate, isobutyl vinyl ether, isoprene, isoproyl methacrylate, isoproyl vinyl ether, itaconic acid, lauryl methacrylate, Methacrylamide, methacrylic acid, methacrylonitrile, N-methylolacrylamide, N-methylol methacrylamide, N-isobutoxymethylacrylamide, N-isobutoxymethyl methacrylamide, N-alkyloxymethylacrylamide, N-alkyloxymethyl methacrylamide, N-vinyl caprolactam, methyl acrylate, N-methyl methacrylamide, α-methyl methacrylamide, α -Methylstyrene, p-methylstyrene, 2-methyl-5-vinylpyridine, n-propyl methacrylate, sodium p-styrene sulfonate, stearyl methacrylate, styrene, p-styrene sulfonic acid, p-styrene sulfonamide, vinyl bromide, 9-vinyl carbazole, vinyl chloride, vinylidene chloride, 1 Vinylnaphthalene, 2-vinylnaphthalene, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyridine-N-oxide, 4-vinylpyrimidine, N-vinylpyrrolidone; and W _b Y _r Y ₄ and RpR _{3 are} as described under a); d) comprises a condensation polymer from the polymeric materials a), b) or c), wherein a condensable form of a), b), c) or a mixture thereof is condensed with a second compound which is selected from the group consisting of phenols, tannins, novolak resins, lignin compounds, together with aldehydes , Ketones or mixtures thereof to produce a condensation resin product, the condensation resin product being added to at least part of the same by adding “Z”, by reacting the resin product with 1) an aldehyde or ketone 2) a secondary amine then continues to react to form a final adduct which can react with an acid.

13. The method according to Anspmch 12, characterized in that at least one fraction of the groups Z of the organic polymer has a polyhydroxyalkylamine functionality which originates from the condensation of an amine or of ammonia with a ketose or aldose containing 3 to 8 carbon atoms. Has atoms.

14. The method according to Anspmch 12, characterized in that the organic polymer is a condensation product of a polyvinylphenol with a molecular weight in the range from 1000 to 10,000 with formaldehyde or paraformaldehyde and with a secondary organic amine.

15. The method according to Anspmch 14, characterized in that the secondary organic amine is selected from methylethanolamine and N-methyl glucamine.

16. The method according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the organic polymers are selected from substituted polyalkylene derivatives (CR'R ² ) _X - CR ³

Y

where R ¹ , R ² , R ³ independently of one another are hydrogen or a methyl or

Can be ethyl group, x = 1, 2, 3 or 4 and

17. The method according to Anspmch 16, characterized in that R ¹ , R ² , R ³ each represent hydrogen and that x = 1.

18. The method according to Anspmch 16 or 17, characterized in that the organic polymers contain one or more of the following structural units:

19. The method according to one or more of claims 1 to 8, characterized gekenn¬ characterized in that the organic polymers are amino group-containing polymeric sugar derivatives.

20. The method according to Anspmch 19, characterized in that the polymeric sugar derivatives contain the following components: