WO2005078025A1

WO2005078025A1 - Method for applying integrated pretreatment layers containing a dithiophosphoric acid ester on metal surfaces

Info

Publication number: WO2005078025A1
Application number: PCT/EP2005/001431
Authority: WO
Inventors: Monica Fernandez Gonzalez; Markus Ruckpaul; Frank Hezel; Markus Hickl; Wolfgang Schrepp; Manfred Essig
Original assignee: Basf Aktiengesellschaft
Priority date: 2004-02-16
Filing date: 2005-02-12
Publication date: 2005-08-25
Also published as: DE102004007744A1

Abstract

The invention concerns a method for applying integrated pretreatment layers containing a dithiophosphoric acid ester on metal surfaces by treatment with a composition containing at least one binder, one crosslinking agent, one inorganic filler with fine particles and one dithiophosphoric acid ester. The invention also concerns an integrated pretreatment layer obtained by said method.

Description

Process for applying integrated pretreatment layers comprising dithiophosphoric acid esters on metallic surfaces

The present invention relates to a method for applying integrated pretreatment layers to metallic surfaces, in particular the surfaces of strip metals, by treatment with a composition which contains at least one binder, crosslinking agent, a finely divided inorganic filler and dithiophosphoric acid ester. It also relates to an integrated pretreatment layer which can be obtained by means of the method.

For the production of flat metal workpieces such as automotive parts, body parts, equipment cladding, facade cladding, ceiling cladding or window profiles, suitable metal sheets are formed using suitable techniques such as stamping, drilling, folding, profiling and / or deep drawing. Larger components, such as automobile bodies, may be joined together by welding several individual parts. The raw material for this is usually long metal strips, which are produced by rolling the metal and wound up into rolls (so-called “coils”) for storage and transport.

As a rule, the metallic components mentioned must be protected against corrosion. In the automotive sector in particular, the requirements for corrosion protection are very high. Nowadays, up to 30 years of rust protection are granted for newer car types. Modern automobile bodies are manufactured in multi-stage processes and have a large number of different layers.

An example of a typical layer structure of an automobile body is shown in Figure 1. In a first step, the steel sheet (1) is coated with Zn or a Zn alloy (2). This can be done galvanically or by immersion in liquid zinc, so-called hot-dip galvanizing. A predominantly inorganic pretreatment layer (3) is then applied to improve the corrosion resistance of the zinc layer itself. This can be phosphating and / or chromating with Cr (VI) or Cr (III) compounds. Chromium and phosphate-free pretreatment layers are also known. The pretreatment layer is also called a conversion layer or passivation layer. It is usually very thin (2 - 100 nm). In addition to improving the corrosion resistance of the Zn layer, it is also said to improve the adhesion between metal and subsequent lacquer layers. The pretreatment layer (3) is now coated with an organic primer ("primer") (4). This is followed by the actual paint layers. In the case of automobiles, the body is then usually coated with an electro-dip coating (5) and then with the so-called filler (6). The filler layer is a comparatively thick, soft layer that is intended to prevent stone chips or the like from destroying the layers underneath. Finally, some or more colored lacquer layers (7) and a clear lacquer layer (8) are applied to the filler for protection. Other lacquer layers and / or coating sequences above the base lacquer (4) are also common for other applications.

While in the past the anti-corrosion treatment was mainly carried out on the finished metallic workpiece, for example a welded-together automobile body, in recent times the anti-corrosion treatment has increasingly been carried out on the strip metal itself. At least the pretreatment layer (3) and the organic base coat (4) are already applied to the strip metal. Only then are parts punched out, shaped and, if necessary, welded together. This means increased demands on the applied layers, because they now have to withstand punching, shaping and welding processes without sacrificing quality.

The metal strips are coated with the pretreatment layer (3) and the organic base coat (4) in a two-stage process, which is comparatively complex in terms of the required system technology. There has therefore been no lack of attempts to apply a single integrated pretreatment layer (3 ') instead of the separate application of a pretreatment layer (3) and the organic base lacquer (4), which takes over the functions of both layers. Such a layer structure is shown by way of example and schematically in Figure 2. The production of a coated metal strip is significantly simplified by such a one-step process.

Integrated pretreatment layers are known in principle.

No. 5,322,870 discloses a composition for forming an integrated pretreatment layer which comprises a polymeric coating agent, a crosslinking agent and additionally alkyl or aryl phosphoric acid esters or alkyl or aryl phosphonic acid esters. The composition can optionally also comprise a pigment.

DE-A 19923 084 discloses a chromium-free aqueous coating composition for single-stage coating which contains at least hexafluoro anions of Ti (IV), Si (IV) and / or Zr (IV), a water-soluble or water-dispersible film-forming Contains binders and an organophosphoric acid. The composition can optionally also comprise a pigment and crosslinking agent. WO 02/62907 discloses a composition for a one-step coating, which comprises a binder, a crosslinking agent and a conductive pigment. The binder has phosphoric acid groups.

Dithiophosphoric acid esters and their use for corrosion protection are known in principle, for example from WO 97/45503, SU-A 147 31 94, US 3,909,447, US 4,339,349, or WO 99/46338. Their use as a component of integrated pretreatment layers was hitherto unknown.

The object of the invention was to provide an improved method for producing integrated pretreatment layers and improved integrated pretreatment layers.

Accordingly, a method has been found for applying integrated pretreatment layers to metallic surfaces, which comprises at least the following steps:

(1) Treating the metallic surface with a crosslinkable preparation comprising at least

(A) a binder, (B) crosslinkable components, these being crosslinkable groups which are connected to the binder and / or can be at least one additionally used crosslinker, (C) a pigment, (D) a corrosion inhibitor, and (E) optionally a solvent, and

(2) crosslinking the applied layer, wherein

• The amount of binder is 20 to 70% by weight, • The filler is 20 to 70% by weight of at least one inorganic, finely divided filler with an average particle size of less than 10 μm, • The corrosion protection agent is 0 , 25 to 10% by weight of at least one dithiophosphoric ester of the general formula HS ₂ P (OR) (OR ') and / or a salt thereof, where R or R' are, independently of one another, a straight-chain or branched alkyl radical having 1 to 30 carbon atoms, which may also have one or more additional functional groups, and / or non-adjacent carbon atoms may be substituted by O or N, and the percentages by weight refer to the sum of all components Obtain an exception for the solvent.

In a further embodiment of the invention, integrated pretreatment layers, preferably with a thickness of 3 to 15 μm, have been found on metallic surfaces, which can be obtained by the process.

In a further embodiment of the invention, a preparation for carrying out the method has been found.

List of figures

Figure 1: Example of a typical layer sequence of an automobile body with two-stage pretreatment Figure 2: Example of a typical layer sequence of an automobile body with integrated, one-stage pretreatment.

The following is to be explained in detail regarding the invention:

By means of the method according to the invention, it is particularly advantageous to provide flat metallic bodies such as sheets, foil, plates and in particular metal strips with an integrated pretreatment layer. In principle, however, it can of course be any desired metallic surfaces.

In principle, the type of metal can be any metal. In particular, however, these are metals or alloys which are usually used as metallic construction materials and which have to be protected against corrosion.

In particular, these are surfaces of iron, steel, Zn, Zn alloys, Al or Al alloys. These can be the surfaces of bodies consisting entirely of said metals or alloys. However, the bodies can also only be coated with these metals and themselves consist of different types of materials, for example of other metals, alloys, polymers or composite materials. In particular, it can be the surface of galvanized iron or steel. In a preferred embodiment of the method, it is the surface of a Strip metal, especially around electrolytically galvanized or hot-galvanized steel. It can be a one-sided or a two-sided galvanized metal strip.

Zn or Al alloys are known to the person skilled in the art. Depending on the desired application, the person skilled in the art selects the type and amount of alloy components. Typical components of zinc alloys include in particular Al, Pb, Si, Mg, Sn, Cu or Cd. Typical constituents of aluminum alloys include, in particular, Mg, Mn, Si, Zn, Cr, Zr, Cu or Ti. It can also be an Al / Zn alloy in which Al and Zn are present in approximately the same amount. Steel coated with such alloys is commercially available. The steel can contain the usual alloy components known to the person skilled in the art.

The term “integrated pretreatment layer” in the sense of this invention means that the coating according to the invention is applied directly to the metal surface without a corrosion-inhibiting pretreatment such as passivation or phosphating being carried out beforehand. The integrated pretreatment layer combines the passivation layer with the organic primer in a single layer However, the term “applied directly” does not rule out that there may still be a thin layer, in particular a thin oxide skin, on the metal surface, which inevitably forms in the presence of air when the metal is handled normally.

Further lacquer layers, such as cathodic dip lacquers, can advantageously be applied directly to the integrated pretreatment layer without an additional organic primer having to be applied beforehand. Of course, an additional organic primer is possible in special cases, although it is preferred not to do so.

The preparation used according to the invention for the treatment of metal surfaces comprises at least one binder (A) and crosslinkable components (B). The crosslinkable components can be at least one crosslinker which is used in addition to a binder, or it can be groups of crosslinkable groups which are bonded to the binder. Of course, the binder can also have crosslinkable groups and a crosslinker can also be used.

Various possible combinations are conceivable here. For example, binders and crosslinkers can be used separately. The binder then comprises reactive functional groups which can react with complementary, reactive functional groups in the crosslinking agents. Alternatively, you can they are also self-crosslinking binders which comprise reactive functional groups which can undergo crosslinking reactions with groups of their kind (“with themselves”) or with complementary, reactive functional groups on the same polymer. It is also possible that only the crosslinkers react with one another.

The binders (A) can be the binders customary in the field of coil coating lacquers. Examples of suitable binders include (meth) acrylate (co) polymers, partially saponified polyvinyl esters, polyesters, alkyd resins, polylactones, polycarbonates, polyethers, epoxy resin-amine adducts, polyureas,

Polyamides, polyimides or polyurethanes. Mixtures of different polymers can of course also be used, provided that the mixture does not cause any undesirable effects.

Polyester or epoxy resin-amine adducts are preferably used. The polyesters are particularly suitable for weldable paints and the epoxy-amine adducts are preferred for paints that are not to be welded.

Suitable polyesters are, in particular, condensates of low molecular weight dicarboxylic acids and dialcohols. Examples of suitable dicarboxylic acids include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, aliphatic cycloaliphatic such as dimer fatty acids, i.e. Reaction products of unsaturated fatty acids with each other, cycloaliphatic dicarboxylic acids such as 1, 4- or 1, 3 cyclohexanedicarboxylic acid, tricyclodecanedicarboxylic acid and aromatic dicarboxylic acids such as isophthalic acid, terephthalic acid or phthalic acid. Derivatives of dicarboxylic acids can of course also be used. Anhydrides such as phthalic anhydride, hexahydrophthalic anhydride or tetradehydrophthalic anhydride are particularly suitable.

Examples of suitable dialcohols include aliphatic alcohols such as, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1, 3-butanediol, 1, 3-propanediol, 1, 4-butanediol, neopentyl glycol, 1-methyl-propanediol-1, 3, 2-butyl 2-ethylpropanediol, pentanediols, hexanediols, octanediols, dodecanediol, hydroxypivalic acid, neopentylglycol esters, cycloaliphatic alcohols such as 1, 4- or 1, 3-cyclohexanedimethanol, TCD alcohol and bis (4-hydroxycyclohexyl) methane or propane and dimerdiols (hydrogenated) , Derivatives of alcohols, such as esters, in particular the corresponding methyl or ethyl esters, can of course also be used in a known manner. In addition to linear binders, branched binders can also be used. Suitable monomers for producing branches include tricarboxylic acids or their anhydrides such as trimelitic anhydride or trimesic acid and trial alcohols such as trimethalyolalkanes, for example trimethylolethane or trimethylolpropane.

The polyesters can preferably be reacted in whole or in part to form isocyanate-terminated polyesters by reaction with polyisocyanates. The OH number of the polyesters used is usually about 10 to about 200 mg KOH / g, preferably 15 to 120 mg KOH / g, particularly preferably 20 to 80 mg KOH / g and for example about 50 mg KOH / g. The molecular weights are usually 400 to 10,000 g / mol, preferably 500 to 5000 g / mol and particularly preferably 1000 to 4000 g / mol.

Epoxy-functional polymers can be prepared by the reaction of epoxy-functional monomers such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether or hexanediol diglycidyl ether with phenols such as bisphenol A, bisphenol F and / or alcohols such as ethoxylated or propoxylated bisphenol A. Epoxy-functional polymers are commercially available, for example under the name Epon ^® or Epikote ^®.

Epoxy resin-amine adducts can be obtained by reacting said epoxy-functional components with phenols or aliphatic or cycloaliphatic dicarboxylic acids, acidic polyesters or alcohols, thiols and amines, in particular secondary amines such as, for example, diethanolamine or N-methylbutanolamine.

Emulsion polymers can also be used. These are particularly suitable for water-based formulations. Examples of suitable emulsion polymers or copolymers include acrylate dispersions, obtainable in a customary manner from acrylic acid and / or acrylic acid derivatives, for example acrylic acid esters and / or styrene. Dispersions made of polyurethanes, made from aromatic and / or aliphatic diisocyanates and polyester or aliphatic soft segments, are also suitable.

The preparation used comprises 20 to 70% by weight of the binder. In the following, all percentages by weight relate to the sum of all components of the preparation with the exception of the solvent or the solvent mixture. The amount is preferably 30 to 60% by weight and particularly preferably 40 to 50% by weight.

The crosslinking components (B) can have thermally crosslinking groups or photochemically crosslinking groups. Suitable crosslinkers are, for example, crosslinkers based on epoxides in which two or more epoxy groups are connected to one another by means of a linking group. Examples include low molecular weight compounds with two epoxy groups such as hexanediol diglycidyl ether, phthalic acid diglycidyl ether or cycloaliphatic compounds such as 3 ', 4'-epoxycyclohexylmethyl ester, 3,4-epoxicyclohexane.

Further examples of suitable crosslinking agents include melamine-type crosslinker such as kommzerziell available crosslinking agents of Luwipal ^® - row.

Blocked polyisocyanates are particularly preferably used as crosslinking agents. When blocking, the isocyanate group is reversibly reacted with a blocking agent. The blocking agent is split off again when heated to higher temperatures. Examples of suitable blocking agents are disclosed in DE-A 199 14 896, column 12, line 13 to column 13, line 2. Polyisocyanates blocked with ε-caprolactam are particularly preferably used.

Crosslinkers suitable for photochemical crosslinking are, for example, the Basonat® brands from BASF or oligomeric acrylates.

If a crosslinker is used separately, 0.5 to 10% by weight, preferably 1 to 8% by weight and particularly preferably 2 to 6% by weight are usually used. Mixtures of different crosslinkers can of course also be used, provided that the properties of the layer are not adversely affected thereby.

The preparation used for the method according to the invention further comprises at least one finely divided inorganic filler (C). The filler can also have an additional organic coating, for example for hydrophobing or

Include hydrophilization. The filler should not exceed an average particle size of 10 μm. The average particle size is preferably 10 nm to 9 μm and particularly preferably 100 nm to 5 μm. In the case of round or approximately round particles, this information relates to the diameter, in the case of irregularly shaped particles, such as, for example, in the case of needle-shaped particles, to the longest axis. The particle size means the primary particle size. It is of course known to the person skilled in the art that finely divided solids often agglomerate into larger particles which have to be dispersed intensively in order to be used. The particle size is chosen by the person skilled in the art depending on the desired properties of the layer. For example, it also depends on the desired one Layer thickness. As a rule, the person skilled in the art will choose smaller particles with a small layer thickness.

On the one hand, electrically conductive pigments or fillers are suitable as fillers. Such additives serve to improve the weldability and to improve a subsequent coating with electrocoat materials. Examples of suitable electrically conductive fillers or pigments include phosphides, vanadium carbide, titanium nitride, molybdenum sulfide, graphite, carbon black or doped barium sulfate. Metal phosphides of Zn, Al, Si, Mn, Cr, Fe or Ni are preferably used. Examples of preferred metal phosphides include CrP, MnP, Fe ₃ P, Fe ₂ P, Ni ₂ P, NiP ₂ or NiP ₃ . Iron phosphides are commercially available, for example, under the name Ferrophos ^® .

Non-conductive pigments or fillers can also be used, such as finely divided amorphous silicon, aluminum or titanium oxides, which can also be doped with other elements. For example, amorphous silicon dioxide modified with calcium ions can be used.

Other examples of pigments include anti-corrosion pigments such as zinc phosphate, zinc metaborate or barium metaborate monohydrate.

Mixtures of different pigments can of course also be used. The pigments are used in an amount of 20 to 70% by weight. The exact amount is determined by the person skilled in the art depending on the desired properties of the layer. When using conductivity pigments, the amounts used are usually larger than when using non-conductive fillers. Preferred amounts for conductive pigments and fillers are 40 to 70% by weight, preferred amounts for non-conductive pigments 20 to 50% by weight.

The composition further comprises 0.25 to 10% by weight of at least one dithiophosphoric acid ester (D) of the general formula HS ₂ P (OR) (OR '). A mixture of several different dithiophosphoric esters can of course also be used.

The dithiophosphoric acid esters can be used as free acids or preferably as salts thereof. Particularly suitable counterions are monovalent ions such as Mg ²⁺ , Sr ^{2 *} , Zn ²⁺ , Ca ² \ Ba ²⁺ , Li ⁺ , Na ⁺ , K ⁺ , NH ₄ ⁺ or also alkylammonium ions of the general formulas NHaR '" ^* , NH ₂ R'y, NHR'Y or NR'Y, where R '"represents a straight-chain or branched aliphatic or aromatic radical, preferably C _T to Ce alkyl. R '"can also include functional groups. Examples of suitable ammonium ions include the ammonium ions of amines such as ethanolamine, N- Methylethanolamine, Λ /, Λ / -dimethylethanolamine, diethanolamine, Λ / -methyldiethanolamine, triethanolamine, morpholine, Λ / -methylmorpholine or triethylamine.

The radicals R and R 'in the dithiophosphoric acid ester can be different or preferably the same. R and R 'are each a straight-chain or branched alkyl radical having 1 to 30 C atoms, which may also have one or more additional functional groups, and / or in which the non-adjacent C atoms are represented by O or N. can be substituted.

It is preferably a straight-chain or branched alkyl radical having 2 to 12 carbon atoms, particularly preferably having 3 to 10 carbon atoms. Examples of suitable radicals include ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-hexyl, 2-ethylhexyl or n-octyl radicals.

Functional groups (F) can be networked like the

Binders also react with the crosslinker and improve the stability of the layer. The functional groups are preferably selected from the group of -OH, -NH ₂ , -NHR ", -COOH or-COOR", where R "is a straight-chain or branched alkyl, aralkyl or aryl radical If the radicals R and R 'have functional groups, it is preferably a radical of the general formula - (CH ₂ ) _n -F, where n is a natural number from 1 to 20, preferably 2 to 12 and particularly preferably 2 to 9 stands.

The radicals R and R 'in which non-adjacent C atoms are substituted by O and / or N atoms are preferably radicals of the general formula - (CH ₂ -CH ₂ -0-) mX containing ethylene oxide units. where X is H or methyl and m is a number from 1 to 9, or residues containing up to 9 ethyleneimine units which are straight-chain or branched ethyleneimine units. It is known to the person skilled in the art that the number of bound units is in each case average values. Such residues can improve water solubility or water dispersibility for use in aqueous systems.

R or R 'can also be a radical of the general formula - [(CH ₂ ) _k O] _r (CH ₂ ) _k -F', where k is a natural number from 2 to 10, 1 for a natural number from 1 to 20 and F 'stands for a functional group. F 'can be, for example, functional groups as defined above. The functional group F 'is preferably one selected from the group of -OH, -OR ", -COOH or -COOR", where R "has the meaning given above. The dithiophosphoric acid esters are usually used in an amount of 0.25 to 10% by weight, preferably 0.5 to 8% by weight and particularly preferably 1 to 6% by weight.

As component (E), the preparation generally comprises a suitable solvent in which the components are dissolved and / or dispersed in order to enable uniform application to the surface. In principle, however, it is also possible to formulate the preparation as solvent-free or essentially solvent-free as a powder coating. The use of a solvent is preferred.

Suitable solvents are those which are capable of dissolving, dispersing, suspending or emulsifying the compounds according to the invention. It can be organic solvents or water. Mixtures of various organic solvents or mixtures of organic solvents with water can of course also be used. The person skilled in the art makes a suitable selection from the solvents which are possible in principle, depending on the intended use and the type of compound used according to the invention.

Examples of organic solvents include hydrocarbons such as toluene, xylene or mixtures, e.g. obtained from the refining of crude oil and e.g. are commercially available as petroleum ether, kerosene, Solvesso® or Risella®, ethers such as THF or polyethers such as polyethylene glycol, ether alcohols such as butyl glycol, ether glycol acetates such as butyl glycol acetate, ketones such as acetone, alcohols such as methanol, ethanol or propanol.

Preparations can also be used which comprise water or a predominantly aqueous solvent mixture. This should be understood to mean mixtures which comprise at least 50% by weight, preferably at least 65% by weight and particularly preferably at least 80% by weight of water. Other components are water-miscible solvents. Examples include monoalcohols such as methanol, ethanol or propanol, higher alcohols such as ethylene glycol or polyether polyols and ether alcohols such as butylglycol or methoxypropanol.

The amount of solvent is determined by the person skilled in the art depending on the desired

Properties of the preparation and the desired application method selected. As a rule, the weight ratio of the layer components to the solvent is 10: 1 to 1:10, preferably approximately 2: 1, without the invention being restricted to this. It is of course also possible to first produce a concentrate and to dilute it to the desired concentration only on site. The preparation is produced by intensively mixing the components of the preparation with the solvents. Suitable mixing or dispersing units are known to the person skilled in the art.

In addition to components (A) to (D) and optionally (E), the preparation can also comprise one or more auxiliaries and / or additives (F). Such auxiliaries and / or additives serve to fine-tune the properties of the layer. Their amount generally does not exceed 20% by weight with respect to the buzzer of all components with the exception of the solvents, preferably not 10%.

Examples of suitable additives are coloring and / or effect pigments, reactive thinners for thermal curing or curing with actinic radiation, rheology aids, UV absorbers, light stabilizers, radical scavengers, initiators for radical polymerization, catalysts for thermal crosslinking, photoinitiators and coinitiators , Slip additives, polymerization inhibitors, defoamers, emulsifiers, degassing agents, wetting and diperging agents, adhesion promoters, leveling agents, film-forming aids, rheology-controlling additives (thickeners), flame retardants, siccatives, skin-preventing agents, other corrosion inhibitors, waxes and matting agents, such as those from the by Johan Bieleman, Wiley-VCH, Weinheim, New York, 1998, or German patent application DE 199 14 896 A1, column 13, line 56, to column 15, line 54.

Preferred additives are dibutyltin dilaurate as a catalyst for thermal crosslinking.

To carry out the method according to the invention, the metallic surface is treated with the preparation.

Optionally, the surface can be cleaned before treatment. If the treatment according to the invention is carried out immediately after a metallic surface treatment, for example electrolytic galvanizing or hot-dip galvanizing of steel strips, the strips can generally be brought into contact with the treatment solution according to the invention without prior cleaning. However, if the metal strips to be treated have been stored and / or transported before the coating according to the invention, they are usually provided with anti-corrosion oils or at least largely soiled that cleaning before the coating according to the invention is necessary. The cleaning can be carried out according to methods known to the person skilled in the art with customary cleaning agents. In the method according to the invention for applying integrated pretreatment layers, the surface of the metal is treated with the preparation, for example by spraying, dipping or rolling on. After a dipping process, the workpiece can be drained to remove excess treatment solution; With sheet metal, metal foils or the like, excess treatment solution can also be squeezed or doctored off, for example. During the treatment, at least parts of the polymer used and further components of the preparation are chemisorbed from the surface of the metal, so that a firm bond is established between the surface and the components. The treatment with the preparation is generally carried out at room temperature, without the principle that higher temperatures should be excluded.

The treatment can be a so-called "no-rinse" process, in which the treatment solution is dried directly in a drying oven without rinsing immediately after application. However, it is also possible to rinse the surface with a cleaning liquid after the treatment.

In the case of the particularly preferred coating of metal strips, the coating can be carried out on one side or on both sides. The coating is very particularly preferably carried out by means of a continuous process.

The coil coating can be carried out, for example, by means of a continuously operating coil coating system, as described in Römpp Lexikon Lacke und Druckfarben, Georg Thieme Verlag, Stuttgart, New York, 1998, page 55, "coil coating", or in German patent application DE 196 32426 A1 Of course, differently designed systems can also be used.

The speed of the metal strip is selected by a person skilled in the art in accordance with the application and hardening properties of the preparation used. As a rule, speeds of 10 to 150 m / min, preferably 12 to 120 m / min, particularly preferably 14 to 100 m / min, very particularly preferably 16 to 80 and in particular 20 to 70 m / min have proven successful.

The application of the paints according to the invention can in any way, for. B. by spraying, pouring or roller painting. Of these application processes, roller coating is particularly advantageous and is therefore preferably used according to the invention. Each roller coating application step can be carried out with several rollers. Preferably two to four and in particular two rollers are used.

During roller painting, the rotating pick-up roller is immersed in a supply of the paint according to the invention and thus takes over the paint to be applied. This is transferred from the pick-up roller directly or via at least one transfer roller to the rotating application roller. From this, the paint is transferred to the belt by wiping in the same direction or in opposite directions.

However, the lacquer according to the invention can also be pumped directly into a nip between two rollers, which experts also refer to as a nip feed.

According to the invention, the opposite wiping or the reverse roller coating method is advantageous and is therefore used with preference.

During roller coating, the circulation speeds of the take-up roller and the application roller can vary very greatly from coating process to coating process. Preferably, the application roller has an orbital speed which is 110 to 125% of the belt speed, and the take-up roller has an orbital speed which is 20 to 40% of the belt speed.

Following the application of the preparation used according to the invention, any solvent present in the layer is removed and the layer is crosslinked. This can be done in two separate steps, but can also be done simultaneously. To remove the solvent, the layer is preferably heated using a suitable device. Drying can also be done by contacting a gas stream. Both methods can be combined.

The curing method depends on the nature of the crosslinking agent and is usually carried out thermally. However, curing can also take place with actinic radiation or in combination thermally and with actinic radiation. The joint curing with heat and actinic radiation is also referred to as dual-cure by experts. Actinic radiation is understood here and below to mean electromagnetic radiation, such as near infrared, visible light, UV radiation or X-rays, in particular UV radiation, or corpuscular radiation, such as electron beams.

The temperature required for curing depends in particular on the crosslinking agent used. Very reactive crosslinkers can be used at lower temperatures are cured as less reactive crosslinkers. The temperature of the layer for curing is usually between 120 and 250 ° C.

The coating layers according to the invention are preferably heated during thermal curing by convection heat transfer, irradiation with near or far infrared and / or in the case of tapes based on iron by electrical induction.

The heating time, i.e. the duration of the thermal curing varies depending on the paint used according to the invention. It is preferably 10 s to 2 min.

If essentially convection heat transfer is used, at the preferred belt speeds, convection ovens with a length of 30 to 50, in particular 35 to 45 m, are required. The ambient air temperature is preferably 350 ° C.

The thermal curing of the lacquer layers according to the invention can also be supported by irradiation with actinic radiation. However, curing can also be carried out using actinic radiation alone, as is described, for example, in German patent application DE 198 35206 A1.

The method according to the invention makes it possible to obtain an integrated pretreatment layer on a metallic surface, in particular the surface of iron, steel, zinc or zinc alloys, aluminum or aluminum alloys. We do not know the exact structure and composition of the integrated pre-treatment layer. In addition to the reaction products of the polymer and the crosslinker, it also includes the fillers, dithiophosphoric acid esters and optionally other components. In addition, components detached from the metal surface and deposited again, such as customary amorphous oxides of aluminum or zinc and possibly other metals, can also be present. The composition of the passivation layer does not appear to be homogeneous, but rather has concentration gradients.

The thickness of the integrated pretreatment layer is determined by the person skilled in the art depending on the desired properties of the layer. As a rule, there is a thickness of 3 to 15 μm, even if in special cases the thicknesses can still lie outside these ranges. A thickness of 4 to 10 μm is preferred, and 5 to 8 μm is particularly preferred. The thickness results from the amount of the composition applied in each case. Additional layers of paint can be applied to the metallic surface with an integrated pre-treatment layer.

This can be done in the same coil coating system where several application and curing stations are connected in series. Alternatively, however, after the application and curing of the integrated pretreatment, the coated tape and further layers can be applied in other systems. After the coated strips have been produced, the coils can be wound into coated coils and then processed further at another location; however, they can also be processed directly from the coil coating. They can be laminated with plastics or provided with removable protective films.

The tapes provided with the integrated pretreatment layer can also be shredded and processed into molded parts without further painting. Different molded parts can also be joined together by welding. Examples of suitable shaping processing methods are presses and

Thermoforming.

The resulting profile elements and molded parts, such as scratch-resistant, corrosion-resistant, weather-resistant and chemical-stable, can easily be overpainted with a wide variety of paints.

The paint without conductive pigments can be used as a KTL replacement if it is applied in a layer thickness of about 10-15 μm.

The following examples are intended to explain the invention in more detail.

example 1

Basic recipe for a formulation for the production of a conductive integrated pre-treatment layer: The following components were used for the formulation:

The components were mixed in the order given in a suitable stirring vessel and predispersed with a dissolver for ten minutes. The resulting mixture was transferred in a bead mill with a cooling jacket and mixed with 1.8-2.2 mm SAZ glass beads. The millbase was ground to a Hegmann grain size of 10 to 15 μm for 25 minutes. The ground material was then separated from the glass beads.

The millbase was added with stirring in the order given, 3.55 parts by weight of bisphenol-A-epichlorohydrin (Epikote ^® 834 from Shell Resins), 1, 78 parts by weight of a commercial self-crosslinking urethane resin (Desmodur ^® VPLS 2253 from Bayer AG), 0, 1 part by weight of dibutyltin dilaurate and 4.26 parts by weight of Solvesso ^® 150 were added.

Under slow dissolvers the resulting mixture was further added 52.6 parts by weight iron phosphide (Ferrophos® ^® HRS 2132). After a further ten minutes, the desired distribution of the electrically conductive pigments was achieved. Example 2

Basic formulation for a formulation for producing a non-conductive integrated pretreatment layer:

The following components were used for the formulation:

The components were mixed in a suitable stirred vessel in the order given and predispersed with a dissolver for ten minutes. The resulting mixture was transferred in a bead mill with a cooling jacket and mixed with 1.8-2.2 mm SAZ glass beads. The millbase was milled for 1 h 30 'minutes. The ground material was then separated from the glass beads.

The regrind was added with 5.9 parts by weight of a commercially available self-crosslinking urethane resin (Desmodur ¹⁸ VPLS 2253 from Bayer AG) and 0.4 parts by weight of a commercially available crosslinking catalyst (Borchi ^® VP0245 from Bayer AG) with stirring in the order given. Examples 3 and 4

In addition, 3 parts by weight of a dithiophosphoric acid ester were added to the formulation according to Example 1.

Examples 5 to 7 In addition, 3 parts by weight of a dithiophosphoric acid ester were added to the formulation according to Example 2.

Application of the integrated pretreatment layers according to the invention

The formulations obtained were applied to metal surfaces directly using doctor blades. The surfaces have not been passivated beforehand. Either steel plates of type Z (hot-dip galvanized steel manufactured according to the standards DIN EN 10 142 and 01 147) or aluminum plates of type A 6016 were used. The surfaces were degreased before use. For comparative example 2, the steel surface was first provided with a Cr-free passivation layer in a known manner. The passivation layer contains Zr-Ti salts and an organic binder. The integrated pre-treatment layers were then hardened in a continuous dryer. The circulating air temperatures in the dryer, the object temperatures and the resulting dry layer thicknesses are summarized in Table 1.

Table 1: Compilation of the samples produced The corrosion resistance of the samples obtained from examples and comparative examples was assessed using a weathering test. A climate change test according to VDA 621-415 was carried out to test the steel samples. The corrosion tests for aluminum were carried out according to the DIN standard 50021-ESS (according to ASTM B287 test). After weathering, the metal plates were evaluated as follows: • 1-3 → red rust in the scratch, edges and surface, blistering in more than 90% of the surface • 4-5 → red rust in the scratch and / or edges, a lot of white rust on the surface, Blistering in 50% of the surface • 6-7 → No red rust, little white rust on the surface, blistering in -25% of the surface 8-10 → No red rust, very little / no white rust on the surface, blistering in less than 15% of the surface flats of the tests are summarized in Table 2.

Table 2: Results of weathering tests

The metal plates with integrated pretreatment layers, which contain dithiophosphoric acids, have less surface corrosion and less infiltration at the scratch and the edges than the metal plates with coatings without dithophosphoric acid.

This applies regardless of whether they have only been cleaned or whether passivation has also been carried out.

These coatings also have a high level of corrosion protection when the 3 mm weighed samples have been tested in weathering tests in accordance with the ASTM D 522 standard.

Claims

claims

1. Method for applying integrated pretreatment layers on metallic surfaces at least comprising the steps

(2) crosslinking the applied layer, characterized in that

• The amount of binder is 20 to 70% by weight, • The filler is 20 to 70% by weight of at least one inorganic, finely divided filler with an average particle size of less than 10 μm, • The corrosion protection agent is 0 , 25 to 10% by weight of at least one dithiophosphoric ester of the general formula HS ₂ P (OR) (OR ') and / or a salt thereof, where R or R' are, independently of one another, a straight-chain or branched alkyl radical having 1 to 30 carbon atoms, which may also have one or more additional functional groups, and / or non-adjacent carbon atoms may be substituted by O or N, the% by weight data relating to the sum of all components with the exception of the solvent.

2. The method according to claim 1, characterized in that the metallic surface is cleaned in an additional cleaning step (0) before treatment with the preparation.

3. The method according to claim 1 or 2, characterized in that the metallic surface is the surface of steel, zinc or zinc alloys, aluminum or aluminum alloys.

4. The method according to any one of claims 1 to 3, characterized in that the integrated pretreatment layer has a thickness of 3 to 15 microns.

5. The method according to any one of claims 1 to 4, characterized in that it is R or R 'is a straight-chain or branched alkyl radical having 3 to 10 carbon atoms.

6. The method according to any one of claims 1 to 3, characterized in that R or R 'is a radical of the general formula - (CH ₂ ) _n -F, where n is a natural number from 1 to 20 and F stands for a functional group.

7. The method according to claim 6, characterized in that the functional group F is one selected from the group of -OH, -NH ₂ , - NHR ", -COOH or-COOR", where R " is a straight-chain or branched alkyl, aralkyl or aryl radical.

8. The method according to any one of claims 1 to 3, characterized in that R or R 'is a radical of the general formula - [(CH ₂ ) _k O] _r (CH ₂ ) _k - F', wherein k stands for a natural number from 2 to 10, 1 for a natural number from 1 to 20 and F 'for a functional group.

9. The method according to claim 8, characterized in that it is a functional group F 'selected from the group of -OH, -OR ", - COOH or-COOR", wherein R "has the meaning given above.

10. The method according to any one of claims 1 to 9, characterized in that the treatment is carried out by means of rolling, spraying or dipping processes

11. The method according to claim one of claims 1 to 10, characterized in that the metal surface is the surface of a strip metal

12. The method according to claim 11, characterized in that the strip metal is electrolytically galvanized or hot-galvanized steel

13. The method according to claim 11 or 12, characterized in that one carries out the treatment by means of a continuous process

14. Integrated pretreatment layer on a metallic surface made of steel, zinc or zinc alloys, aluminum or aluminum alloys obtainable by a method according to one of claims 1 to 13.

15. Integrated pretreatment layer according to claim 14, characterized in that the thickness of the layer is 3 to 15 microns.

16. Metallic surface comprising an integrated pretreatment layer according to claim 14 or 15.

17. Metallic surface according to claim 16, characterized in that on the integrated pretreatment layer there are still one or more layers of lacquer applied one above the other.

18. Steel strip metal comprising a coating of Zn or a Zn alloy, which has a surface according to claim 16 or 17.

19. Preparation for applying integrated pretreatment layers on metallic surfaces comprising at least the following components:

(A) a binder, (B) crosslinkable components, these being crosslinkable groups which are connected to the binder and / or can be at least one additionally used crosslinker, (C) a pigment, (D) a corrosion inhibitor, and (E) optionally a solvent, characterized in that

The amount of binder is 20 to 70% by weight,

The filler is 20 to 70% by weight of at least one inorganic finely divided filler with an average particle size of less than 10 μm,

• The corrosion protection agent is 0.25 to 10% by weight of at least one dithiophosphoric ester of the general formula HS ₂ P (OR) (OR ') and / or a salt thereof, where R and R' are independent of one another is a straight-chain or branched alkyl radical having 1 to 30 carbon atoms, which is also one or more additional can have functional groups, and / or non-adjacent C atoms can be substituted by O or N,

the percentages by weight refer to the sum of all components with the exception of the solvent.