EP1499686A1

EP1499686A1 - Mixture for applying a non-corrosive, thin polymer coating which can be shaped in a low-abrasive manner, and method for producing the same

Info

Publication number: EP1499686A1
Application number: EP03720492A
Authority: EP
Inventors: Georg Gros
Original assignee: Chemetall GmbH
Current assignee: Chemetall GmbH
Priority date: 2002-04-20
Filing date: 2003-04-17
Publication date: 2005-01-26
Also published as: ES2292958T3; AU2003229697A1; US20060011893A1; CN1662615B; US20050161641A1; CA2484457A1; CA2482902A1; CN1662616A; WO2003089530A8; MXPA04010224A; US20060058423A1; EP1499665A1; CA2484314A1; US7482040B2; KR20050013538A; AU2003229698B2; DE50308006D1; KR20050009296A; WO2003089529A1; AU2003229697B2

Abstract

The invention relates to a mixture for applying a polymer, non-corrosive, electroconductive coating which can be shaped in a low-abrasive manner, to a base. Said mixture contains at least one substance A in the form of electroconductive hard particles, at least one substance B in the form of very soft or soft, inorganic, sliding, electroconductive or semiconductive particles, and/or at least one substance C in the form of metallic, soft or hard, electroconductive or semiconductive particles and/or soot, and optionally other constituents such as an anticorrosion pigment D, the sum of the parts by weight of the inorganic sliding particles B and the metallic particles and/or soot C amounting to between 0.25 and 99.5% of the parts by weight of the water-insoluble or only slightly water-soluble pigmentation S (A+B+C), and the size of the electroconductive hard particles A amounting to less than 10 ?m in relation to the particle size transfer value d99. The invention also relates to a method for producing a non-corrosive, viscoplastic coating on a base, said coating containing polymer and inorganic particles, and to an electroconductive coating containing polymer and inorganic particles.

Description

Mixture for applying a thin, polymeric, corrosion-resistant, wear-resistant, formable coating and method for producing the same

coating

The present invention relates to a mixture for applying a thin polymeric, corrosion-resistant, low-wear formable and electrically conductive or semiconductive coating to a base, in particular a metallic base such as e.g. a steel sheet, which may have previously been coated with zinc or a zinc-containing alloy and then optionally coated with a pretreatment. The coating is particularly intended to serve as a welding primer.

Today, first-generation welding primers are used in large quantities in automobile construction, which contain chromium for reasons of corrosion protection, because it is still very difficult to use equivalent and environmentally friendly components instead of chromium-containing compounds in corrosion protection. The electrical conductivity of the approximately 2.5 to 9 μm thick polymeric coatings required for electrical welding is acquired through a very high content of powdery metallic zinc embedded in a polymeric matrix. Due to the moisture in every polymer coating, however, metallic zinc tends to oxidize and form white efflorescence (white rust). Due to the oxidation of the zinc powder, however, the corrosion-protective effect and the electrical conductivity of the metallic zinc can gradually be used up with the progressive formation of white rust. The limited corrosion-resistant welding primers of the 1st generation are also subject to only certain requirements with regard to electrical weldability: it is sufficient if an automatic welding machine sets 600 welding points through two steel sheets of approximately 0.5 to 2.0 mm thickness that are coated on both sides before the welding electrodes are reworked or replaced. The structure of the coatings on the steel sheets typically comprises first a layer of zinc or a zinc alloy of approximately 2 to 7.5 μm in thickness, then a pretreatment layer of approximately 0.01 to 1.0 μm in thickness and finally a welding primer layer of a thickness of well below 10 μm in thickness. There are therefore 3 different to apply a total of 2 sheets with 12 layers at each welding point and to create a good weld connection, which is a high requirement.

However, far higher requirements are placed on welding primer coatings of the second generation for use in automotive engineering: 1.) The corrosion resistance of a flange made of two sheets should be about three times higher, despite the fact that it is free of chromium, since here the successful passage of an extremely aggressive corrosion protection alternating test according to VDA 621-415 with 20 instead of only 10 cycles of one week each with salt spray tests, condensation water tests and recondensation without the appearance of red rust. The test has a progressively stronger impact over the test period of 20 weeks. 2.) In the case of electrical welding, the number of welding points that can be achieved with an automatic welding machine should be at least 1200 instead of just 600 before the welding electrodes are replaced or reworked. 3.) For the adhesive technology used increasingly in automotive engineering instead of welding, it is necessary that the requirements for the adhesive strength between the base and zinc-containing coating, between zinc-containing coating and pretreatment layer, between pretreatment layer and welding primer layer and between welding primer layer and The adhesive layer is also at least as high as with the 1st generation of the welding primer, whereby the 1st generation of the welding primer is often applied thinner (2.5 to 3 μm, but then free of electrically conductive, hard particles) than the foreseeable 2. Generation of welding primers due to the high corrosion requirements and with the layer thickness also the adhesive strength requirements grow. 4.) It would also be advantageous if the welding primer would also prove itself in other types of welding instead of resistance welding, since intensive work is also being carried out on alternative welding technology. It is hoped that with the 2nd generation of the welding primer the labor-intensive and expensive cavity sealing and possibly also the seam sealing can be dispensed with.

In addition, it is necessary that sheets coated with welding primer, which are processed in the automotive industry, also to a greater extent without problems can be reshaped. Low-wear flaring, flaring, deep drawing or / and pressing in large presses is particularly necessary here, in which the corresponding tool is not worked too hard and too quickly and the welding primer coating must not be destroyed, removed, torn off or seriously damaged. This applies in particular to the inorganic components in the welding primer that are incorporated in an organic matrix.

The prior art publications on electrically conductive, at least one resin-containing and optionally weldable coatings often describe the use of graphite, carbon black, aluminum, nickel, zinc and / or ferro-alloys such as iron phosphides based on mixtures of FeP, Fe ₂ P and apparently unavoidable impurities. Occidental Chemical Corp. is usually used for the iron phosphides of Ferrophos ^® powders. (= OxyChem, formerly Hooker Chem. And Plastics Corp.), in which the qualities HRS 2132 or HRS 3095 have an average particle size of 3.3 μm or 2.8 μm according to the manufacturer, but contain a significant amount of oversize, which can be recognized by the particle size passage value dgg of 16 μm or 12 μm. Name all known to the applicant publications that iron phosphide as an additive for coating mixtures, go from this Ferrophos from ^® powders. These powder qualities are obviously used unground in all of these publications, because grinding is at best carried out in a mixture of at least three components, with mixing often being in the foreground, but the grain sizes should be reduced little or not at all. As is known, the grinding operations for the production of lacquers and similar coatings are often only mixing processes or comparatively weak grinding processes, especially since they are usually carried out in an organic suspension with a comparatively low iron phosphide content. Since iron phosphides are hard and brittle, they require vigorous grinding without the presence of any or in the presence of as few substances as possible which impair the grinding effect. In addition, the grinding of fine-particle phosphides is not without danger. US 6,008,462 teaches liquid coating compositions for weldable, seawater-resistant primers containing metallic iron particles. The introduction to the description of this patent describes problems which occur when using iron phosphides in primer coatings and which are similarly mentioned in US Pat. No. 5,260,120: These include the extremely abrasive effect of the iron phosphide particles on tools and the high coefficient of friction of such coatings. These problems are solved in these publications by using iron particles instead of iron phosphide particles in the primer coating or by additionally applying a thin polymeric top coat to the coating containing iron phosphide particles, which should not adversely affect the weldability of the sheets coated in this way.

No. 4,889,773 describes electrodes for resistance welding, which have a coating of binder and at least one phosphide, preferably based on iron phosphides. This coating does not meet the high requirements of welding primer coatings.

No. 4,110,117 teaches zinc, aliphatic polyol silicates and partly also coating compositions containing iron phosphide.

No. 4,011,088 protects purely inorganic coatings based on iron phosphide and / or nickel phosphide particles which are embedded in water-soluble silicate binder.

No. 3,884,705 teaches coatings which, in addition to so-called ferroalloys such as iron phosphide mixtures, contain increased proportions of anti-corrosion pigments and possibly also zinc dust.

WO 96/29372 relates to compositions which, in addition to binder resin, include zinc, graphite and possibly other components such as Contain iron phosphide.

In the scanning electron microscopic examination of welding primer coatings on metallic substrates, in which the welding primer Coating should have a thickness of less than 9 microns, it has been noticed that iron phosphide does not only lead to an inhomogeneous coating, but also forms disruptive peaks that protrude high from the coating and gives rise to excessive wear during forming. The first attempts at forming using unground iron phosphide powder grades showed considerable abrasion and a lack of suitability for forming in series production.

The task was to propose coatings that could be used for low-wear forming, e.g. of steel sheets, such as those processed in the automotive industry, are suitable for series production. Despite the one-sided or even two-sided coating, these coatings should e.g. 1.) with zinc or a zinc-containing alloy, 2.) with a thin pretreatment layer, which provides corrosion protection and a primer for the subsequent primer, and 3.) with a 0.5 to 10 μm thick welding primer coating be conductive to be easy to weld. The applied welding primer coating is intended for heavy forming, such as deep-drawing a sheet of more than 10 cm, in part over narrower radii and more in the pressing direction, as is the case with steel sheets in the automotive industry, e.g. is common for bonnets and other body elements, can survive without damage or as little damage as possible, whereby the welding primer film must neither tear off nor be removed in a larger area. The process for producing the welding primer coating should also be as simple as possible, suitable for series production and inexpensive. The dry coatings should have a layer thickness of 6 μm or even significantly smaller thicknesses, in particular in order to reduce the costs of the coatings.

The object is achieved with a mixture for applying a thin polymeric, corrosion-resistant, low-wear formable and electrically conductive or semiconductive coating on a base, in particular on a metallic base such as a steel sheet, the base optionally having at least one zinc layer and / or one Zinc-containing alloy layer or / and can be precoated with at least one pretreatment layer, the mixture A) having an electrical content Conductive or / and semiconducting elements / connections selected from the group of a) electrically conductive or / and semiconducting particles with a particle size distribution with a dβo passage value <6 μm, measured with a type S Mastersizer from Malvern Instruments, but not only electrically conductive or / and semiconducting substances based only on particles of iron phosphide and / or metallic zinc and optionally up to 5% by weight of graphite and / or molybdenum disulfide are used, from b) electrically conductive and / or semiconducting polymeric compounds such as B. polyanilines or their derivatives and of c) electrically conductive or / and semiconducting amine and / or ammonium-containing compounds and B) at least one binder, optionally including reactive diluent (s) and C) in each case at least one crosslinking agent and / or at least a photoinitiator and D) optionally also at least one component selected from d) post-crosslinking compounds such as isocyanates, blocked isocyanates, isocyanurates, melamine resins or / and their derivatives, e) additives, f) corrosion protection pigments such as phosphates, phosphosilicates and / or silicates, g) corrosion inhibitors not present in particle form and optionally E) organic solvent and / or water, the sum of the proportions by weight of all conductive or / and semiconducting elements / compounds A) being 0.5 to 70% by weight and the content of the electrically conductive or / and semiconducting particles a) thereof with a particle size Enver distribution with a DSO through-value <6 microns 0 to 60 wt .-% each based on the wet paint is based. The basis for this is preferably a preparation of the suspension, as described in the examples and comparative examples.

The subject matter of patent applications DE 102 17 624 and DE 102 56 286 becomes explicit with regard to the information on examples, comparative examples, test techniques, particle-related information such as, for example, type, size, size distributions and properties, and also on the properties and compositions of the mixtures and coatings, as well as on coatings and process steps included in this application. The base can in particular be made of steel, stainless steel, at least one aluminum or / and magnesium alloy, which can be sheets, plates, rods or parts of complicated shape or components already joined. The sheets are preferably made from an aluminum alloy or from a steel.

The coating can be applied to the underlay in any extent, e.g. only on one or both sides e.g. a sheet, possibly including at least one edge or only in a certain width or in a certain pattern, so that e.g. Edge areas can hereby remain uncoated.

The electrically conductive and / or semiconducting particles a) are water-insoluble or poorly water-soluble. Among other things, they serve as barrier particles without having to be particularly corrosion-resistant. Nevertheless, it is preferred that the particles a) are chemically somewhat more stable and / or more corrosion-resistant, especially with respect to water and weakly basic media.

However, the composition according to the invention preferably contains not only electrically conductive and / or semiconducting substances selected from those based on aluminum, iron phosphide, graphite, molybdenum sulfide or / and zinc, but particularly preferably also at least one further such type of particle. The term iron phosphide is used to summarize the various stoichiometrically different Fe-P phases, regardless of their composition.

In the mixture according to the invention, the sum of the parts by weight of all elements of compounds A) can preferably be 0.8 to 66% of the parts by weight based on the solids content in the wet paint, particularly preferably at least 1.5% or at least 4.5%, very particularly preferably at least 8 % or at least 14%, in particular at least 26% or particularly preferably at most 60% or at most 54%, very particularly preferably at most 48% or at most 42%, in particular at most 36%. For coatings, in particular with an average layer thickness in the range from 2 to 4 μm, the sum of the parts by weight of all elements / compounds A) is preferably 0.5 to 56% of the parts by weight based on the solids content in the wet paint, particularly preferably at least 1% or at least 2, 5%, very particularly preferably at least 4% or at least 8%, in particular at least 12% or particularly preferably at most 50% or at most 44%, very particularly preferably at most 38% or at most 32%, in particular at most 26%.

In the mixture according to the invention, the sum of the parts by weight of all particles a) can preferably be 0.5 to 56% of the parts by weight based on solids content in the wet paint, particularly preferably at least 1.5% or at least 4.5%, very particularly preferably at least 8% or at least 14%, in particular at least 26% or particularly preferably at most 50% or at most 44%, very particularly preferably at most 38% or at most 32%, in particular at most 26%. The lower the proportion of hard particles a) in the mixture, the sooner it may be preferred to use better electrically conductive particles a) with a higher electrical conductivity.

On the other hand, with a decreasing layer thickness of the dry film, successively, a smaller proportion can be made more electrically conductive and / or semiconducting

Components or rather to less highly conductive parts such as semiconducting components are passed over. Because with a welding primer

A film thickness of approx. 0.5 μm ensures that it can be welded through even without the content of electrically conductive components, but with this film thickness the corrosion resistance, adhesive strength and resistance to hard are

Forming regardless of possible particle contents and also without

Particle content not guaranteed.

These particles a) can belong to three classes of particles: hard, often highly electrically conductive particles, soft or very soft, often slidable particles,

Metallic particles. In the inventive mixture, the electrically conductive and / or semiconductive particles can on a) substances based on compounds or mixtures of compounds with or of spinels, such as Fe ₃ θ4, Mn ₃ O _4, FeMn ₂ O ₄ and / or other substances Basis of borides, carbides, oxides, phosphates, phosphides, silicates, silicides or electrically conductive coated particles or / and their mixture or their joint connection, and optionally further metallic particles including alloys and / or carbon black containing selected from aluminum, iron, Cobalt, copper, molybdenum, nickel, niobium, silver, tantalum, titanium, vanadium, tungsten, zinc, tin, aluminum, iron, cobalt, copper, molybdenum, nickel, niobium, silver, tantalum Alloys containing titanium, vanadium, tungsten, zinc or / and tin, in particular oxides based essentially on spinels, preferably of aluminum, chromium, iron, cobalt, copper, magnesium, manganese, nickel, vanadium , Titanium or / and zinc or / and essentially based on electrically conductive or / and semiconducting oxides with substoichiometric oxygen content such as or / and in particular phosphides based essentially on aluminum, iron, cobalt, copper, manganese, molybdenum, nickel, niobium, tantalum, titanium, vanadium, tungsten, zinc and / or tin, in particular based on phosphides, preferably based on Iron, manganese, nickel and / or tin-containing phosphides. Particularly suitable as electrically conductive coated particles are those which have an electrical conductivity of at least metallic zinc, in particular particles coated with graphite, carbon black, another type of carbon, electrically conductive metal, iron oxide, antimony and / or tin compound (s).

The electrically conductive and / or semiconducting particles a) are selected, in particular, from others based on boride, carbide, oxide, phosphide, phosphate, silicate and / or silicide. They are identified here as "hard" and are preferably such compounds based on aluminum, chromium, iron, calcium, magnesium, manganese, nickel, cobalt, copper, lanthanum, lanthanide, molybdenum, niobium, tantalum, titanium, vanadium, tungsten, Yttrium, zinc, tin and / or zirconium These particles are usually quite hard and often have better electrical conductivity, and their electrical conductivity can possibly be considerably higher are based on a special doping additive and / or content of a further, more electrically conductive or / and semiconducting phase and / or on a more electrically conductive coating. Particularly preferred substances are iron phosphate, manganese phosphate, nickel phosphate, zinc phosphate and / or other phosphates based on aluminum, iron, copper, manganese, nickel, zinc or / and other transition metals, phosphides based on iron, manganese, molybdenum, nickel, titanium, Zirconium or / and optionally further transition metals, borides based on titanium or / and other transition metals, carbides such as boron carbide, silicon carbide and vanadium carbide or silicides such as based on molybdenum, nitrides such as titanium nitride and / or other transition metals.

Oxides of high electrical conductivity, in particular oxides with a structural chemistry based on at least one spinel such as Fe ₃ θ ₄ or (Cu, Fe, Mn, Ni, Ti, Zn) ₃ O ₄ , based on at least one oxide, are particularly preferred with a substoichiometric oxygen content and of comparatively high electrical conductivity such as SnO _2-x or TiO ₂ -χ with x, for example in the range from 0.02 to 0.25 or based on at least one phosphide, in particular by water and dilute acids can be attacked only little or not and has a higher electrical conductivity. The graphite is preferably microcrystalline and in particular has more than 97.0% by weight of C.

The mixture according to the invention can also be characterized in that the mixture of all types of electrically conductive or / and semiconducting, hard particles a) has an average particle size dso in the range from 0.1 to 4.5 μm, in particular in the range from 0. 2 to 3.5 μm.

The proportion of electrically conductive or / and semiconducting, hard particles within the mixture of the electrically conductive or / and semiconducting particles a) is preferably 0 to 90% by weight, particularly preferably at least 20% by weight, very particularly preferably at least 40% by weight .-% or particularly preferably at most 70% by weight, very particularly preferably at most 50% by weight. With a higher proportion of electrically conductive and / or semiconducting, hard particles a) in the mixture is often a harder, stronger, more electrically conductive and mostly also chemically stable coating, while with a low proportion of electrically conductive and / or semiconducting, hard particles a) in the mixture, a softer, less strong, possibly weaker electrically conductive coating is achieved.

In the mixture according to the invention, preferably at least 10% by weight, preferably at least 20% by weight, particularly preferably at least 30% by weight, in particular at least 40% by weight, of the electrically conductive and / or semiconducting particles a) are those of higher electrical conductivity and higher hardness, especially oxides and / or phosphides based essentially on aluminum, iron, cobalt, copper, manganese, molybdenum, nickel, niobium, tantalum, titanium, vanadium, tungsten, zinc and / or tin, including oxo-stoichiometric oxides with increased electrical conductivity, in particular oxides and / or phosphides based on iron, manganese, nickel or / and zinc-containing compounds or mixtures thereof.

The proportion of the electrically conductive or / and semiconducting particles a) based on boride, carbide, phosphate, silicate and silicide is preferably not more than 80% by weight of all electrically conductive or / and semiconducting particles a), particularly preferably not more than 65% by weight, very particularly preferably not more than 50% by weight, in particular not more than 35% by weight. However, it may be preferred to reduce the proportion of iron oxide pigment, in particular as is known in the paint industry, to contents of up to 20% by weight, particularly preferably up to 10% by weight, very particularly preferably up to 5% by weight .-%, especially to no pigment content at all.

In the mixture according to the invention, the proportion of lubricious, very soft or soft particles within the mixture of the electrically conductive and / or semiconducting particles a) can preferably be 10 to 100% by weight, particularly preferably at least 20% by weight, very particularly preferably at least 30% by weight or particularly preferably at most 90% by weight, very particularly preferably at most 80% by weight. The content of sulfides, selenides and tellurides in the mixture is preferably not more than 5% by weight or particularly preferably not more than 3.5% by weight, very particularly preferably not more than 2.5% by weight on the weight of the solid in the wet paint. If substances are selected from the electrically conductive and / or semiconducting particles a) that are less resistant to corrosion, especially in the alkaline range, their content should not be too high or even zero. With a high proportion of lubricious, very soft or soft particles in the mixture, a very well lubricious, flexible, softer coating is often formed, while with a particularly low proportion of lubricious, very soft or soft particles in the mixture, often a harder, firmer and mostly also better electrically conductive coating is set.

The inorganic, lubricious particles selected from the electrically conductive and / or semiconducting particles a) are preferably those with very good sliding properties. They are water-insoluble or hardly water-soluble. They preferably have particles with a substantially flat (platelet) or elongated extension (needles, rulers) and / or essentially corresponding aggregates. In particular, there are those based on graphite and / or chalcogenide such as sulfide, selenide or telluride, in particular graphite, antimony-containing, manganese-containing, molybdenum-containing, bismuth-containing, tungsten-containing and / or tin-containing chalcogenide especially preferred of manganese sulfide, molybdenum disulfide, tungsten disulfide and / or tin sulfide. You can also e.g. be coated with carbon or graphite. In the mixture according to the invention, they can consist predominantly or entirely of graphite, sulfide, selenide and / or telluride, in particular of graphite, antimony-containing sulfide, tin-containing sulfide, molybdenum sulfide and / or tungsten sulfide. However, elements such as copper or alloys e.g. of copper, zinc or other metals can be selected for this.

In many cases, the lubricious, very soft or soft particles look out of the coating to a certain extent if they show large particle diameters in comparison to the dry film thickness and are not subjected to greater mechanical stress until the coating is applied, and can mechanical stress on the coating, such as, for example, when rubbing or shaping, are rapidly comminuted, these particles helping as lubricants alone or in combination with any proportions of oil, such as deep-drawing oil, which may be present. It can therefore be preferred to select the electrically conductive or / and semiconductive particles a) from the lubricious, very soft or soft particles rather larger than the other particles a).

In the mixture according to the invention, the mixture of all types of lubricious, very soft or soft particles when added to the mixture can have an average particle size in the range from 0.1 to 20 μm, preferably in a range up to 18 μm, particularly preferably in a range up to 15 μm, very particularly preferably in a range up to 12 μm or preferably in a range of at least 1 μm, particularly preferably in a range of at least 3 μm, very particularly preferably in a range of at least 5 μm.

In the mixture according to the invention, the mixture of all types of lubricious, very soft or soft particles when added to the mixture can have an average particle size dso in the range from 1 to 25 μm, preferably in a range up to 21 μm, particularly preferably in a range up to 16 μm, very particularly preferably in a range up to 12 μm or preferably in a range of at least 1.5 μm, particularly preferably in a range of at least 3.5 μm, very particularly preferably in a range of at least 5 μm.

Platelets are preferred as the particle shape of the lubricious, very soft or soft particles. In the mixture according to the invention, the average particle size dso of the lubricious, very soft or soft particles when added to the mixture can be larger by a factor of 1.5 to 7 than the average particle size d _{50 of} the other types of electrically conductive and / or semiconducting particles a), preferably larger by a factor of 2 to 6, particularly preferably larger by a factor of 3 to 5. The metallic particles as the third sub-group of the electrically conductive and / or semiconducting particles a) are preferably selected from aluminum, iron, cobalt, copper, manganese, molybdenum, nickel, niobium, tantalum, titanium, tungsten, zinc, tin, zirconium or / and At least one alloy containing at least one such metal - intermetallic compounds are basically included in the term alloys within the meaning of this application - such as ferroalloys such as, inter alia, FeCr, FeMn, FeSi or FeTi, steel, bronze or brass. It is particularly advantageous here to select alloys of these elements, which are particularly suitable with regard to corrosion resistance, such as ZnMg alloys, instead of the often corrosion-sensitive metals such as aluminum, copper and zinc. In particular, no or no very high levels of ferroalloys other than those based on iron phosphide are added, especially not more than 80% by weight, not more than 55% by weight or not more than 40% by weight of all elements / Compounds A). Alternatively, the metal particles and / or alloy particles can also be coated, wherein the particle coating can help to improve the corrosion resistance and / or the electrical conductivity. They are water-insoluble or particularly poorly water-soluble. They are advantageously of low hardness and high ductility.

Advantageously, in many configurations, no more than 75% by weight of all types of electrically conductive or / and semiconducting particles a) are selected from metals and alloys, in particular not more than 58% by weight or not more than 46% by weight. %. The proportion of lubricious, very soft or soft particles in the mixture is preferably the same or greater than the proportion of metals or alloys and / or soot.

In the mixture according to the invention, the mixture of all types of metallic particles including alloy particles when added to the mixture can have a particle size passage value d ₈ o in the range from 0.05 to 6 μm, in particular in the range from 0.1 to 5 μm, preferably in a range up to 4.5 μm, particularly preferably in a range up to 4 μm or preferably in a range of at least 0.5 μm, particularly preferably in a range of at least 0.8 μm. Here, higher contents are preferably selected only for softer components. On the other hand, particles of graphite or / and soot when added to the mixture have a particle size passage value dso in the range from 0.01 to 25 μm.

In the mixture according to the invention, the mixture of all types of metallic particles including alloy particles, graphite and / or carbon black when added to the mixture can have an average particle size dso in the range from 0.01 to 10 μm, preferably in a range up to 8 μm, particularly preferably in a range up to 5 μm, very particularly preferably in a range up to 4 μm or preferably in a range of at least 0.1 μm, particularly preferably in a range of at least 0.3 μm, very particularly preferably in a range of at least 0.5 μm. Platelets are also preferred as the particle shape of the metallic particles (including alloys), graphite and / or carbon black. Nanoparticles can also be used here. It is particularly preferred that at least some of these metallic particles consist of alloy particles, preferably at least 20% by weight of all of these metallic particles, particularly preferably at least 40% by weight, very particularly preferably at least 60% by weight, especially entirely consist of alloy particles, the alloys preferably consisting only of aluminum, magnesium, titanium and / or zinc-containing alloys which are significantly more corrosion-resistant than aluminum, magnesium, titanium, zinc or another metal, the main component of this alloy ,

In the mixture according to the invention, the mean particle size dso of the metallic particles including alloy particles, graphite and / or carbon black when added to the mixture can be larger by a factor of 0.1 to 4 than the mean particle size dso of the electrically conductive, hard particles, preferably by the factor 2 to 6 larger, particularly preferably by the factor 3 to 5 larger.

In the mixture according to the invention, the proportion of metallic particles including alloy particles, graphite and / or carbon black in the mixture of all types of electrically conductive and / or semiconducting particles a), in particular 0 to 75% by weight, based on the weight of the solid in the wet paint be. This proportion is preferably at least 0.1% by weight or at most 70% by weight, based on the weight of the solid in the wet paint, particularly preferably at least 1% by weight or at most 65% by weight, very particularly preferably at least 2% by weight or at most 60% by weight.

With a high proportion of metallic particles including alloy particles, graphite or carbon black in the mixture of all types of electrically conductive or / and semiconducting particles a) a softer, often weaker electrically conductive and usually also less chemically stable coating is formed, while with a particularly low proportion of metallic particles or carbon black in the mixture often results in a harder, stronger, mostly electrically conductive and often chemically stable coating.

The at least one substance or at least one of several substances from the category of electrically conductive and / or semiconducting particles a) in the solid state at room temperature preferably has an electrical resistance of at most 1000 mΩ.cm, particularly preferably of at most 500 mΩ.cm. particularly preferably from at most 50 mΩ «cm. In particular, the electrical resistance cannot be lower or, for films less than 5 μm thick, not more than 2 orders of magnitude lower than that of commercially available iron phosphide mixtures based on FeP and Fe ₂ P including impurities.

However, the electrically conductive and / or semiconducting particles a) need not have high-quality sliding properties. At least some of the particle types involved among the electrically conductive or / and semiconducting particles a) preferably have a Moh's hardness measured on large crystals or on compact components of at least 3, preferably at least 4 or at least 4.5, particularly preferably at least 5 , in particular of at least 5.5.

The passage value dso of the mixture of all types of electrically conductive and / or semiconducting particles a) is preferably not more than 5.5 μm, particularly preferably not more than 5 μm, very particularly preferably not more than 4.5 or 4 μm all not more than 3.5 or 3 μm. The passage value d 50 of the electrically conductive and / or semiconducting particles is advantageously a) in the range from 0.5 to 5.8 μm, particularly preferably in the range from at least 1.5 μm or up to 4.5 μm, very particularly preferably in the range from at least 1.8 μm or up to 3.5 μm , especially in the range of at least 2 μm or up to 4 μm.

In the mixture according to the invention, the mixture of all types of electrically conductive or / and semiconducting particles a) can have, in particular, an average particle size dso of not more than 2.6 μm or not more than 2.2 μm; this is preferably in the range from 0.1 to 2.5 μm, very particularly in the range from 0.2 to 2 μm. It is preferably in a range up to 1.8 μm, particularly preferably in a range up to 1.6 μm, very particularly preferably in a range up to 1.4 μm or preferably in a range of at least 0.5 μm. Platelets, linear or / and essentially isometric particles are preferred as the particle shape of the electrically conductive and / or semiconducting particles.

Advantageously, the size of the mixture of all types of electrically conductive or / and semiconducting particles a), based on the passage value dio, is not more than 1.5 μm, in particular not more than 1.2 μm, very particularly preferably not more than 0.8 microns.

In the mixture according to the invention, the mixture of all types of electrically conductive or / and semiconducting particles a) may preferably have a steep particle size distribution in which the passage value dso to the passage value dio is at most a factor of 12. This factor is in particular at most a factor of 11, particularly preferably of at most 10, very particularly preferably of at most 9, especially of at most 8.

For all particle size determinations from 0.3 μm average particle size, distributions measured with a type S Mastersizer from Malvern Instruments can be assumed. The suspension with the particles to be measured was prepared in accordance with the information in the examples and comparative examples. In the case of determinations below 0.3 μm in medium size, measurements or evaluations on photos that are obtained with a scanning electron microscope on particles that are well distributed on a carrier should preferably be used become. In the case of deposits which are more recognizable as agglomerates, the particles should be counted separately as many individual particles and not as individual agglomerates, and at least 400 particles should be taken into account in order to be able to determine approximate distributions.

In the method according to the invention, the electrically conductive and / or semiconducting particles a) are preferably ground on their own. The grinding can be carried out separately for each particle type a) or in partial mixtures or in a total mixture of all types of particles a). In the method according to the invention, the oversize particles can predominantly be comminuted when grinding the electrically conductive and / or semiconducting particles a), so that a narrower particle size distribution is produced. A steep particle size distribution, in particular of the hard powders a), if these account for a high proportion of the pigmentation, contributes significantly to a uniform particle distribution within the finished coating. It is particularly advantageous if a narrower particle size distribution is set by grinding the electrically conductive or / and semiconducting particles a), in particular when the finest particles are scarcely comminuted or when the powder is not ground to dust. In one variant, it is particularly preferred to adjust the particle size distribution to a narrower distribution by grinding only in the case of the particle types of the electrically conductive or / and semiconducting, hard particles a), in which the average particle size is greater than 1 μm, very particularly preferably greater than 2 μm.

If there is a mixture of different electrically conductive and / or semiconducting particles a), it may be of interest to either grind only the mixture or / and the individual particle qualities separately. The grinding of these particles or this particle mixture a) is preferably particularly strong, especially when using special grinding units. It may be of interest here to select a grinding unit that is normally not used in the paint industry, because in the paint industry it is usually only relatively weak, namely usually only a mixture of soft and / or hard substances or a mixture of polymeric and / or inorganic substances, which are not necessarily in particle form, is ground and the grinding conditions for hard particles are therefore relatively weak. Suitable grinding units and grinding processes are known in particular from powder metallurgy and from technical ceramics.

The optionally present at least one anti-corrosion pigment g) preferably has an average particle size which is also approximately the size of the average particle size dso of pigment a) (d o + 1 μm) or slightly less (up to dso - 1 μm). These properties can also contribute significantly to the setting of a uniform particle distribution within the finished coating.

In contrast to the particles a), the corrosion protection pigments f) can have a limited water solubility and / or water-soluble proportions. In addition, it is preferred that, in particular in the presence of phosphide, at least one inorganic and / or organic corrosion inhibitor g) is also used, but at least one corrosion protection pigment f) may also be sufficient for this instead. A corrosion protection pigment f) based on phosphates such as e.g. Aluminum, alkaline earth or zinc phosphate, and / or based on alkaline earth carbonate, alkaline earth silicate and / or alkaline earth phosphosilicate.

In the mixture according to the invention, the mixture of all types of corrosion protection particles f) when added to the mixture can have a particle size passage value dso in the range from 0.03 to 6 μm, preferably in a range up to 5.5 μm, particularly preferably in a range up to 5 μm, very particularly preferably in a range up to 4.5 μm or preferably in a range of at least 0.1 μm, particularly preferably in a range of at least 0.3 μm, very particularly preferably in a range of at least 0.5 microns. In addition, it is advantageous if the particle size passage value dgg of the corrosion protection particles f) is not greater or not significantly greater than the particle size passage value dgg of the electrically conductive and / or semiconducting particles a). In the mixture according to the invention, the mixture of all types of corrosion protection particles f) when added to the mixture can have an average particle size dso in the range from 0.01 to 5 μm, preferably in a range up to 4 μm, particularly preferably in a range up to 3 μm, very particularly preferably in a range of up to 2 μm or preferably in a range of at least 0.05 μm, particularly preferably in a range of at least 0.1 μm, very particularly preferably in a range of at least 0.3 μm. In addition, it is advantageous if the average grain size of all types of corrosion protection particles f) is just as large or not significantly smaller than the average grain size of the electrically conductive and / or semiconducting, hard particles a). It is preferred to distribute the anti-corrosion particles f) homogeneously in the mixture and the resulting coating. The corrosion protection particles f) can build up a barrier for, for example, hydrogen ions and are not consumed in the same way during the corrosion as sacrificing corrosion agents such as e.g. B. metallic manganese or zinc. Platelets are particularly preferred as the particle shape of the corrosion protection pigment particles f).

Also preferred is the addition of a corrosion inhibitor g) e.g. based on amides, amines, butanoic acid derivatives, imines or / and organic or inorganic titanates or / and zirconates. The anti-corrosion pigments f) and the corrosion inhibitors g) are known in principle.

In particular, the proportion of corrosion protection particles f) to the total content of the water-insoluble or sparingly water-soluble pigmentation from all types of particles a) is 0.4 to 65%, preferably at least 1% or up to 60%, particularly preferably at least 2% or up to 55%.

In this case, it is advantageous if the sum of the parts by weight of the water-insoluble or sparingly water-soluble pigmentation from all types of particles a) to the sum of the total pigmentation Σ (a) + f)) is 30 to 99% by weight. It is preferably 50 to 98% by weight, particularly preferably at least 70% by weight or up to 97% by weight, very particularly preferably at least 90% by weight or up to 96% by weight. A mixture in which the proportion of electrically conductive or / and semiconducting, hard particles is 0 to 68% by weight, the proportion of lubricious, very soft or soft particles 0 to 6% by weight, the proportion of is very particularly preferred metallic, soft or hard, electrically conductive or / and semiconducting particles, graphite and / or carbon black 0 to 16 wt .-% and the proportion of corrosion protection pigment f) is 0.5 to 12 wt .-%, each based on the weight of Solid in the wet paint. A mixture is particularly preferred in which the proportion of electrically conductive, hard particles 52 to 62% by weight, the proportion of lubricious, very soft or soft particles 0 to 4% by weight, the proportion of metallic, soft or hard , electrically conductive or / and semiconducting particles, graphite or / and carbon black 0 to 12 wt .-% and the proportion of anti-corrosion pigment f) is 1 to 8 wt .-%, each based on the weight of the solid in the wet paint. Under certain circumstances, the content of particles made of metallic, soft or hard, electrically conductive or / and semiconducting particles, graphite and / or carbon black is at least 0.1% by weight.

The total pigment content Σ (a) + f)) to the total solid content in the wet lacquer is preferably 10 to 63% by weight, particularly preferably 15 to 57% by weight, very particularly preferably 20 to 51% by weight.

The solids content of the liquid mixture remains practically identical from the wet paint to the dry film to the finished, crosslinked coating produced therefrom. The solids content of the mixture can therefore be regarded as the same as in the finished coating. If carbonate or similar substances with possibly volatile components should be used, this must be taken into account accordingly.

In addition, as an electrically conductive or semiconducting component, alternatively for at least one particle type a) or / and for at least one conductive or semiconducting compound c) or / and in addition thereto at least one electrically conductive or semiconducting polymeric compound b) can also be added, for example at least one conductive polymer such as polyaniline (s), polypyrrole (s), polythiophene (e) and / or their derivative (s). The proportion of the compounds b) can range from 0 to 40% by weight in the mixture, based on the solids content in the Wet lacquers are preferably in the range from 1 to 25% by weight, particularly preferably in the range from 2 to 15% by weight, in particular up to 12% by weight, up to 8% by weight or less than 5% by weight. -%. The use of so-called conductive polymer has the advantages that the coating can be designed to be less wear-resistant or largely wear-free, since, as with the compounds c), a lower proportion of particles can be used without the coating thus produced having a lower electrical conductivity got to. In addition, due to the exchange of some of the particles, which are considerably harder than organic substances, the coating can also be made more elastic and more adherent, since these substances can sometimes be better incorporated into the polymer matrix than particles. This effect can also be achieved by adding the compounds c) as an alternative or in addition to the compounds b) or can be further increased in this way.

In addition, as an electrically conductive or semiconducting component, alternatively for at least one particle type a) or / and for at least one conductive or semiconducting polymeric compound b) or / and in addition thereto, at least one electrically conductive or semiconducting compound c) can also be added, especially an organic compound, e.g. at least one tertiary amine, an ammonium compound and / or their derivatives. The proportion of the compounds c) can be in the range from 0 to 40% by weight in the mixture, based on the solids content in the wet paint, preferably in the range from 1 to 25% by weight, particularly preferably in the range from 2 to 15% by weight , in particular up to 12% by weight or up to 8% by weight.

In the case of the mixture according to the invention, it can be advantageous in certain embodiment variants that an organic lubricant content, for example based on polyethylene wax, ethylene oxide, polypropylene or / and paraffin, is added. The mixture according to the invention will preferably not contain more than 1.5% by weight of wax and / or substances with wax-like properties, in particular not more than 0.6 or 0.2% by weight, based on the dry weight of the wet paint. particularly preferably no wax and no substances with wax-like properties. These substances lead often at levels between 0.1 and 0.5% by weight to impair the adhesion or cohesion with subsequently applied coatings such as further layers of paint or adhesives such as epoxy resin adhesives or adhesives from adhesive films. In particular, if it should not be glued, the proportion of organic lubricant can also be increased.

In principle, all types of known binders or binder systems can be used as binders, in particular those which enable good water resistance, resistance to organic solvents (methyl ethyl ketone resistance), alkali resistance, elasticity and adhesive strength to the substrate, in particular binders. Systems with a binder based on acrylate, epoxy, polyester, isocyanate, isocyanurate or melamine resin. For the coating of sheets on high-speed conveyor systems, it is advantageous to use particularly reactive binder systems, if necessary those that can cure largely or completely on the conveyor system at temperatures below 250 ° C PMT or even below 200 ° C PMT. The content of binder (s), including the reactive diluent (s) and / or crosslinker (s) that may be present, can be varied within very wide ranges, in particular in the range from 10 to 90% by weight, based on the solids content in the wet paint, preferably in the range from 12 to 75% by weight, particularly preferably in the range from 14 to 60% by weight, in particular in the range from 16 to 42% by weight. The thinner the dry coating, the lower its particle content can be.

The basically known systems or compounds can be used for partial or complete curing. On the one hand, this can be chemical crosslinking, possibly with the blocking of a capped one Hardener or additionally optionally induced by heat. On the other hand, the crosslinking can take place radically by hard rays such as electron beams or using photoinitiators and high-energy radiation such as UV light. This can optionally be followed by radical curing with the addition of at least one isocyanate and chemical postcrosslinking. For this purpose, at least one selected from, for example, isocyanates, as the at least one post-crosslinking compound d) blocked isocyanates, isocyanurates, melamine resins or / and their derivatives are used. If present, photoinitiator (s) can be present in a mixture in the range from 0.2 to 18% by weight, based on the solids content, in the wet paint, preferably in the range from 0.5 to 8% by weight ,

As further additives e.g. Wetting agents, biocides, effect pigments, color pigments, colorless or white pigments, dyes, defoamers, adhesion promoters, catalysts, corrosion inhibitors, polymerization inhibitors, silanes, siloxanes, suspending agents, surfactants and / or crosslinkers are added. The content of additive (s), including the photoinitiator (s) optionally present, can be varied within wide limits, in particular in the range from 0.1 to 25% by weight, based on the solids content in the wet paint, preferably in the range from 0 , 5 to 15% by weight, particularly preferably in the range from 0.8 to 10% by weight, in particular in the range from 1 to 8% by weight.

On the one hand, water or / and at least one organic solvent can be added to the mixture according to the invention; on the other hand, the proportion of water and / and organic solvent can be partially or completely replaced by monomers as reactive diluents.

The object is also achieved with a method for producing a corrosion-resistant, tough-elastic coating on a base containing polymers and inorganic particles, which is characterized in that a mixture according to the invention is applied to an optionally precoated base, optionally dried and at least partially crosslinked, producing a coating whose average layer thickness in the dry state is no more than 6 μm.

It is preferred that the average layer thickness in the dry

State in the range from 0.2 to 6 μm, particularly preferably in the range from 1 to

5.8 μm, very particularly preferably from at least 1.5 μm or 2 μm or at most from 5.6 or 5.2 μm. In particular, the average Layer thickness in the dry state at about 2.4 μm, at about 2.8 μm, at about 3.2 μm, at about 3.6 μm, at about 3.9 μm, at about 4.2 μm, at about 4, 6 μm, approximately 4.9 μm, approximately 5.2 μm or approximately 5.6 μm.

After drying, all components of the mixture are preferably resistant to water and weak alkaline media in the partially or / and completely cured state.

The mixture according to the invention can be applied in particular by knife coating, rolling on, spraying and / or spraying. Such an application is preferably carried out on a tape, which can be precoated. Spraying is particularly preferred when applied to parts. The application should be applied as evenly as possible and should be of the same thickness as possible.

The mixture can preferably be dried in the temperature range from 20 to 320 ° C., and air drying at room temperatures or only slightly elevated temperatures can also be used. Insofar as the crosslinking at relatively low temperatures ensures a binder mixture for a sufficiently chemically stable coating, baking at a usually high temperature is not absolutely necessary. The baking of a thermally crosslinking polymer system can preferably be carried out in the temperature range from 100 to 320 ° C. Thermal crosslinking can also be combined with radical-initiated crosslinking, which in particular helps to produce particularly high degrees of crosslinking. In particular, thermal post-crosslinking after the radical-initiated crosslinking is advantageous here. The types of crosslinking, their combination and the polymer systems on which they are based are well known to the person skilled in the art.

In the process according to the invention, the lubricious, very soft or soft particles, such as graphite, cannot be ground or only weakly ground before being added to the mixture or in the mixture and / or in a part of the mixture. Because it is advantageous if the particles of graphite and / or the aggregates of many connected or caked individual particles in their size, which is preferably significantly larger than that Electrically conductive, hard particles, to some extent, largely or completely preserved and, if possible, only lose a little in size for mixing. It is advantageous if these particles are also distributed as homogeneously as possible, in particular in the organic binder system. The mixture according to the invention can be applied to strips, sheets, parts and composite components composed of at least two parts which are connected, for example, by clinching, gluing and / or welding. The mixture according to the invention can be applied in particular to the high-speed conveyor systems, such as galvanizing systems and / or coil coating systems, to sheet metal systems or in parts production, in assembly or in the repair area.

In the method according to the invention, the particle size passage value dgg of the electrically conductive and / or semiconducting hard particles a) cannot be significantly larger, not larger or only a little smaller than the average thickness of the coating. Advantageously, the

Particle size passage value dgg of the electrically conductive and / or semiconducting hard particles a) in the range of ± 3 μm, in particular in the range of ± 2 μm, in the range of + 1 μm, around the average thickness of the invention

Welding primer coating, measured microscopically with a cross section. It is particularly preferred that this particle size passage value dgg is somewhat smaller (dgg up to 2.5, 1, 5 or 0.8 μm smaller) than the average thickness of the welding primer coating according to the invention.

It is preferred that with an average thickness of the welding primer coating according to the invention of, for example, 5 μm, the particle size passage value dg _{9 of} the electrically conductive and / or semiconducting, hard particles a) is in the range from 5.5 to 4 μm and, for example, 3 μm thickness of the particle size passage value dgg of the electrically conductive or / and semiconducting, hard particles a) is in the range from 3.5 to 2 μm (dgg + 1 or - 2 μm or dgg + 0.6 or - 1, 2 μm). The particle size passage value dgg of the electrically conductive and / or semiconducting hard particles a) is preferably slightly less than the average thickness of the dry, hardened coating. The electrical resistance of a coating according to the invention is advantageously measured on a steel coated on one side, in which either only the coating according to the invention or a coating sequence consisting of a zinc or zinc alloy layer, a pretreatment layer and a welding primer layer is applied to the steel sheet.

When measuring the volume resistance, the coating according to the invention has a welding primer layer which is provided on one side at least and, if necessary, also with e.g. Zinc or / and a pretreatment coated sheet with a laboratory apparatus according to DVS leaflet 2929 preferably has an electrical resistance of at most 1000 mΩ, particularly preferably of at most 300 mΩ, very particularly preferably of at most 80 mΩ.

The electrically conductive and / or semiconducting particles a) used as the only particles in a polymeric matrix with a content of particles a) of 15% by weight, based on the solids content, in the largely cured state, homogeneously incorporated into a corresponding polymeric base, such as a polymeric one Primer composition preferably an electrical resistance of at most 2 x 10 ⁵ Ω, preferably of at most 2 x 10 ⁴ Ω, measured in accordance with DIN 53596 for use without resistance welding and preferably an electrical resistance of at most 2 x 10 ⁴ Ω, particularly preferably of at most 1 x 10 ⁴ Ω, very particularly preferably of at most 2 x 10 ³ Ω, in particular of at most 2 x 10 ² Ω, for use with resistance welding, the mean layer thickness preferably being kept in the range from 3 to 6 μm.

In the method according to the invention, the mixture applied to the base can be dried, baked, radically irradiated and / or heated in order to form a well cross-linked, corrosion-resistant, tough-elastic coating. With a content of post-crosslinking compounds, a stronger post-crosslinking can also be achieved hereby due to thermal excitation, in particular if crosslinking with radical radiation, in particular UV radiation, has been initiated beforehand. The pigmentation lies in the polymer matrix well distributed preferably before. In addition, it is preferred if the degree of crosslinking of the polymeric matrix is at least 70%, preferably at least 80%, particularly preferably at least 90%. In the case of thermally curing polymer systems, the degree of crosslinking can also be adjusted in part via the stoving temperature and duration or / and via the content of catalysts.

In addition, it is preferred if the coating according to the invention is so corrosion-resistant on a steel sheet that at least 10, preferably at least 16, particularly preferably at least 20 cycles of a corrosion protection alternating test according to VDA 621-415 can be withstood without the occurrence of red rust.

In the method according to the invention, a coating with an average thickness of less than 6 μm, in particular less than 5 μm, preferably less than 4 μm and particularly preferably less than 3 μm can be produced, measured in the dry state microscopically on a cross section.

In the process of the invention, the mixture can be free or substantially free of organic lubricants such as e.g. based on PTFE, silicone or / and oil, free of inorganic or / and organic acids or / and heavy metals and other cations such as e.g. Arsenic, lead, cadmium, chromium, cobalt, copper and / or nickel. Preferably, all or most of these substances are not added deliberately. Acids could increase the water absorption of the coating. Organic corrosion inhibitors should preferably not be added in overdoses.

In the method according to the invention, the base can consist of at least one metal and / or at least one alloy and can optionally be precoated and in particular consist of a sheet made of aluminum, an aluminum, iron or magnesium alloy or steel, such as automobile steels. In the method according to the invention, the mixture according to the invention can be applied directly to a pretreatment coating. The at least one pretreatment coating can in particular be one based on or containing at least one silicon, titanium and / or zirconium compound, based on a complex fluoride compound such as based on TiFβ, based on phosphating, based on alkaline passivation as with a content of at least one metal oxide such as a passivation based on aluminum, iron, cobalt, manganese, nickel or / and zinc oxide and / or based on a polymer, very fine particles and optionally at least one compound of at least one IIIB / IVB element such as La, Y, lanthanides such as Ce etc., Ti, Zr, Hf and / or phosphate-containing pretreatment coating.

Furthermore, the object is achieved with an electrically conductive or semiconducting coating containing polymers and inorganic particles, produced with a mixture according to the invention and / or produced according to the method according to the invention.

The coating according to the invention can be used as a welding primer, as a protective coating when forming or / and joining, as a corrosion protection of surfaces or in the edge, seam or / and weld seam area, as protection instead of a cavity seal or / and a seam seal, in particular for vehicle construction or aircraft construction , be used.

Examples and comparative examples:

The following examples (B), which are shown in the tables, illustrate preferred embodiments of the mixture, process and coating according to the invention.

The experiments for the examples according to the invention and for the comparative examples were largely carried out with the raw materials, aggregates and process steps customary in the paint industry, if individual pigments and individual grinding processes are not used. In the preparation of the mixtures, all of the binders were initially introduced, diluted with organic solvent and / or water, then the additives and the anti-corrosion pigments were added and the mixture present was ground. Thereafter, the particles a), which had already been ground separately, were added and dispersed thoroughly using a dissolver. In the examples according to the invention, the phosphides were ground separately before they were added to the mixture, so that the passage value dso of the individual particle size distributions of the different particle types to the examples with an average dry layer thickness of about 5 μm in the range from 4.2 to 4.9 μm was, for the examples with an average dry layer thickness of about 3 μm, but in the range from 2.3 to 2.8 μm. With water and / or organic solvent, the viscosity was finally adjusted to a throughput time in the continuous beaker in the range from 30 to 60 s according to ISO / 2431 (5 mm). This mixture was applied using a laboratory coater or squeegee to hot-dip galvanized or electrolytically galvanized, then pretreated sheets of less than 1 mm in thickness. The sheets coated in this way were dried at 80 ° C. and, in the case of thermally crosslinking systems, baked at temperatures of about 160 ° C. PMT in examples 1 to 12 or 240 ° C. PMT in examples 13 to 24. In the case of radiation-curing systems, curing was initiated with UV radiation. The post-crosslinking compound was optionally added immediately before coating and stimulated for further crosslinking by heating to temperatures of approximately 100.degree.

The compositions in Table 1 are calculated based on 100 parts by weight of the solids contents of the various additives, including added water and organic solvent (wet paint). The table shows the variety of compositions with different binder systems and different pigment types and files. Table 2 shows the properties of the coatings produced with the mixtures in Table 1.

The particle size distributions were measured with a Mastersizer Type S from. Malvern Instruments, which has been set particles to be measured and from a small to two drops of surfactant mixture (Pril ^®) to deionized water a suspension with the addition of a sample, said suspension in addition, under the action of ultrasound, the ultrasound source built into the device was dispersed first of about 80% intensity over about 5 s and then of about 30% intensity over about 25 s. A pump setting of approx. 50% and a stirrer setting of approx. 40% were selected for setting the suspension and for measurement, and the measurement was carried out in the "obscuration" setting (approx. 20%).

The experiments show that the optimization of the coating according to the invention between formability, low wear during forming, chemical stability, corrosion resistance and weldability during resistance welding is by no means easy. While the additions of very soft or soft, inorganic, lubricious, electrically conductive or / and semiconducting particles including alloy particles or metallic zinc help to improve the formability, a content of metallic particles such as metallic zinc, graphite and / or soot can improve the corrosion resistance in some cases significantly lower. The respective electrical conductivity and the proportions of the different types of particles a) substantially determine the weldability, the electrical conductivity being of somewhat less importance in the case of particularly thin films. The transition from zinc to alloys or to copper brings significant improvements in corrosion resistance. A (partial) replacement of iron phosphide partially reduces the hardness and possibly also the strength of the coating, but can easily be compensated for in another way with regard to the electrical conductivity and strength of the coating. This shows many alternatives to provide particularly thin coatings for heavy forming.

Table 3 shows mixtures using tungsten powder. Tungsten typically showed an electrical resistance which - with comparable purity - is on the order of at least about 5% lower than that of zinc. In Examples 41 to 52, a tungsten particle quality of technical purity was used, which was ground down even further. It turned out that the tungsten powder was very easy to grind and felt very soft. Contrary to the expected properties, it was found that the combination of tungsten powder with, for example, zinc powder and / or powder is one Aluminum alloy and / or zinc alloy showed an unexpectedly good weldability and good flexibility of the hardened coating. A mixture with electrically conductive particles of zinc and tungsten in a weight ratio of approximately 1: 1 to approximately 1: 2 resulted in a welding suitability similar to that of iron phosphide alone. The added ground tungsten powder had a particle size distribution with an average particle size dso of 2.4 μm, dso of 5.5 μm and dgg of 9.0 μm. The zinc powder added had a particle size distribution with an average particle size dso of 3.7 μm, dso of 5.7 μm and dgg of 10.5 μm. The added powder of the particularly corrosion-resistant magnesium-containing zinc alloy had a particle size distribution with an average particle size dso of 4.2 μm, dso of 5.6 μm and dgg of 9.2 μm. The added powder of the corrosion-resistant aluminum alloy had a particle size distribution with an average particle size dso of 3.9 μm, d ₈ o of 5.6 μm and dgg of 10.2 μm. The added iron phosphide powder had a particle size distribution with an average particle size dso of 3.8 μm, dso of 5.1 μm and dgg of 8.8 μm. Instead of the tungsten powder, powder of molybdenum, tantalum and / or niobium could also be used with similarly good results.

Table 1: Composition of the examples according to the invention based on solids contents in the wet paint

Table 2: Properties of the coatings according to the invention when the layer composition is varied, at 160 or 240 ° C. PM

Table 3: Composition of the examples according to the invention based on solids contents in t ^ Jaßlack

Examples B41 B42 B43 B44 B45 B46 B47 B48 B49 B50 B51 B52 thermal binders

Claims

claims

Mixture for applying a thin polymeric, corrosion-resistant, low-wear formable and electrically conductive or semiconductive coating on a base, in particular on a metallic base such as e.g. a steel sheet, the support, e.g. can be precoated with at least one zinc layer or / and a zinc-containing alloy layer or / and with at least one pretreatment layer, the mixture A) containing electrically conductive or / and semiconducting elements / compounds selected from the group of a) electrically conductive or / and semiconducting particles with a particle size distribution with a dβo transmittance value <6 μm, measured with a type S Mastersizer from Malvern Instruments, but not only electrically conductive and / or semiconducting substances based only on particles of iron phosphide or / and metallic zinc and optionally up to 5% by weight of graphite and / or molybdenum disulfide are used, from b) electrically conductive and / or semiconducting polymeric compounds such as, for. B. polyanilines or their derivatives and of c) electrically conductive or / and semiconducting amine and / or ammonium-containing compounds and B) at least one binder, optionally including reactive diluent (s) and C) in each case at least one crosslinker and / or at least a photoinitiator and D) optionally also at least one component selected from d) post-crosslinking compounds such as Isocyanates, blocked isocyanates, isocyanurates, melamine resins or / and their derivatives, e) additives, f) corrosion protection pigments such as e.g. Phosphates, phosphosilicates and / or silicates, g) corrosion inhibitors not in particle form and optionally E) organic solvent and / or water, the sum of the proportions by weight of all conductive and / or semiconducting

ElementΛ / Erbindungen A) is 0.5 to 70 wt .-% and the content of the electrically conductive and / or semiconducting particles a) thereof with a

Particle size distribution with a dso passage value <6 μm is 0 to 60% by weight based on the wet paint.

2. Mixture according to claim 1, characterized in that the sum of the parts by weight of the water-insoluble or sparingly water-soluble pigmentation a) to the sum of the total pigmentation Σ (a) + f)) is 30 to 99% by weight.

3. Mixture according to claim 1 or 2, characterized in that the mixture of all types of electrically conductive or / and semiconducting, hard particles a) has an average particle size dso in the range from 0.1 to 4.5 microns, in particular in the range from 0.2 to 3.5 μm.

4. Mixture according to one of the preceding claims, characterized in that the mixture of all types of lubricious, very soft or soft

Particles when added to the mixture has a particle size passage value dso in the range of 1 to 25 microns.

5. Mixture according to one of the preceding claims, characterized in that the mixture of all types of lubricious, very soft or soft particles when added to the mixture an average particle size dso im

Has a range of 0.1 to 20 microns.

6. Mixture according to one of the preceding claims, characterized in that the metallic particles including alloy particles have a particle size passage value dso in the range of 0.05 to 6 microns when added to the mixture.

7. Mixture according to one of the preceding claims, characterized in that the metallic particles including alloy particles have an average particle size dso in the range of 0.01 to 10 microns when added to the mixture.

8. Mixture according to one of the preceding claims, characterized in that the corrosion protection particles f) have an average particle size dso in the range of 0.01 to 5 microns when added to the mixture.

9. Mixture according to one of the preceding claims, characterized in that the corrosion protection particles f) have the particle size passage value d ₈ o in the range of 0.03 to 6 microns when added to the mixture.

10. Mixture according to one of the preceding claims, characterized in that the electrically conductive or / and semiconducting, hard particles a)

Substances based on compounds or mixtures of compounds with or of spinels such as Fe ₃ O ₄ , Mn ₃ O ₄ , FeMn ₂ O ₄ or / and other substances based on borides, carbides, oxides, phosphates, phosphides, silicates, silicides or electrically conductive coated particles or / and their mixture or their joint connection, and that optionally further metallic particles including alloy particles, graphite and / or carbon black are contained, the metallic particles including alloy particles being selected from aluminum, iron, cobalt, copper , Molybdenum, nickel, niobium, silver, tantalum, titanium, vanadium, tungsten, zinc, tin, aluminum, iron, cobalt, copper, molybdenum, nickel,

Alloys containing niobium, silver, tantalum, titanium, vanadium, tungsten, zinc and / or tin.

1 1. Mixture according to one of the preceding claims, characterized in that at least 10 wt .-% of the electrically conductive or / and semiconducting, hard particles a) oxides and / or phosphides essentially based on

Aluminum, iron, cobalt, copper, manganese, molybdenum, nickel, niobium, tantalum, titanium, vanadium, tungsten, zinc and / or tin.

12. Mixture according to one of the preceding claims, characterized in that the lubricious, very soft or soft particles consist predominantly or entirely of graphite, sulfide, selenide and / or telluride, in particular of graphite, sulfide containing antimony, sulfide containing tin, Molybdenum-containing sulfide and / or tungsten-containing sulfide.

13. Mixture according to one of the preceding claims, characterized in that it is at least one electrically conductive or semiconducting polymer Compound b) contains, for example, at least one conductive polymer such as polyaniline, polypyrrole, polythiophene or / and its / their derivative (s).

14. Mixture according to one of the preceding claims, characterized in that it contains at least one electrically conductive or semiconducting compound c), e.g. at least one tertiary amine, an ammonium compound and / or its derivative (s).

15. Mixture according to one of the preceding claims, characterized in that it contains not more than 1.5 wt .-% of wax and / or substances with wax-like properties.

16. A method for producing a polymer and inorganic particles containing, corrosion-resistant, tough-elastic coating on a base, characterized in that a mixture according to one of claims 1 to 15 is applied to an optionally precoated base, optionally dried and at least partially crosslinked, whereby a Coating is made, its average

Layer thickness in the dry state is not more than 6 μm, measured microscopically on a cross section in the dry state.

17. The method according to claim 16, characterized in that the lubricious very soft or soft particles such as e.g. Before adding to the mixture or in the mixture and / or in a part of the mixture, graphite should not be ground or only ground weakly.

18. The method according to claim 16 or 17, characterized in that the electrically conductive or / and semiconducting, hard particles a) are ground for themselves.

19. The method according to any one of claims 16 to 18, characterized in that the coating is produced with a mixture in which the mixture of all types of particles a) has a particle passage value dso, which is not greater than the layer thickness of the dry thus produced coating.

20. The method according to any one of claims 16 to 19, characterized in that when grinding the electrically conductive or / and semiconducting, hard particles a) predominantly the oversize is crushed, so that a narrower particle size distribution results.

21. The method according to any one of claims 16 to 20, characterized in that the particle size passage value dgg of the electrically conductive or / and semiconducting, hard particles a) is not significantly larger, not larger or only a little smaller than the average thickness of the coating.

22. The method according to any one of claims 16 to 21, characterized in that the mixture applied to the base is dried, baked, radically irradiated and / or heated to form a well cross-linked, corrosion-resistant, tough-elastic coating.

23. The method according to any one of claims 16 to 22, characterized in that a coating with a thickness of less than 10 microns, in particular less than 8 microns, preferably less than 6 microns and particularly preferably less than 4 microns is produced.

24. The method according to any one of claims 16 to 23, characterized in that the mixture is free or substantially free of organic lubricants such as e.g. based on PTFE, silicone or oil, inorganic and / or organic acids or / and heavy metals and other cations such as

Arsenic, lead, cadmium, chromium, cobalt, copper and / or nickel.

25. The method according to any one of claims 16 to 24, characterized in that the base consists of at least one metal and / or at least one alloy and is optionally precoated, in particular from a sheet consisting of aluminum, an aluminum, iron or

Magnesium alloy or steel such as Automotive steels.

26. The method according to any one of claims 16 to 25, characterized in that the mixture according to the invention is applied directly to a pretreatment coating.

27. An electrically conductive coating containing polymers and inorganic particles produced with a mixture according to one of claims 1 to 15 and / or produced by a method according to one of claims 16 to 26.

28. Use of the coating according to claim 27 as a welding primer, as a protective coating when forming or / and joining, as a corrosion protection of surfaces or in the edge, seam and / or weld area, as a repair coating material, as protection instead of a cavity seal and / or a seam seal , especially for vehicle construction or aircraft construction.