HK1102667B - Metal pigments comprising a cross-linkable binding agent coating, coating composition, method for the production of coated metal pigments and use thereof - Google Patents

Description

Metallic pigment with crosslinkable binder coating, coating composition, method for producing coated metallic pigment and use

Technical Field

The present invention relates to coated metallic pigments, coating compositions, a process for the preparation of said coated metallic pigments, and the use thereof.

Background

Metallic pigments are widely used for pigmenting paints, varnishes, powder-based varnishes, printing inks, plastics or cosmetics. The incorporation and wetting of these pigments in binder systems is often problematic, especially in the case of powder-based varnishes.

Unlike organic or inorganic colored pigments, metallic pigments cannot be incorporated into powder-based varnishes by extruding and then comminuting the extrudate, as doing so can result in flake-form pigments fragmenting and losing their optical effect. Instead, a process called dry mixing or bonding is used.

It will be appreciated that the dry-mixing process is a simple mixing process in which the powder-based varnish components, such as binders, additives, etc., and the metallic pigment are dry-mixed with each other. This method has a disadvantage in that the metallic pigment and the binder are separated in the above dry mixture during the application of the powder-based varnish because of the difference in specific gravity and electrostatic charge performance of the metallic pigment and the binder. One of the main advantages of the powder-based varnish system is its recyclability, which is no longer feasible for powder-based varnishes colored with metallic pigments produced by dry-mixing processes.

It is understood that the bonding method is a mixing method of the powder-based varnish and the metal pigment, in which the metal pigment particles are physically combined with the powder-based varnish particles by heating the mixture to the glass transition temperature of the powder-based varnish. Thus, when the bonding method is used, adhesion of the metal pigment to the surface of the powder-based varnish particles can be achieved.

A disadvantage of the dry mixing and bonding method is that the metallic pigment is not encapsulated by the binder and thus the metallic pigment is applied to the substrate without being encapsulated by the binder. During the subsequent curing process (usually a drying process), these pigments are not completely covered by the binder. After curing of the powder-based varnish, the metallic pigment is not completely encapsulated by the binder as a result, and thus the corrosion resistance is less than ideal.

Corrosion resistance is particularly important for metallic pigments on or around the surface of the powder coating. In particular for powder-based varnish applications, there is in fact a certain degree of metallic pigments exhibiting a floating behavior even among metallic pigments which by nature exhibit a non-floating behavior. These pigment particles are exposed to particularly strong environmental corrosive influences and mechanical stresses. In this case, particularly serious results will occur with thin or insufficient coatings with cured binder. The main disadvantage of such deficient coatings is that the desired visual effect is severely impaired. Furthermore, powder-based varnish coatings are mostly single-layer coatings and thus lack protection of the clear varnish. However, especially for outdoor applications, there are high demands on the effect consistency and corrosion resistance of metallic pigments.

In order to improve the technical properties of the application or to prevent the pigments from corroding, the metallic pigments can be improved by various preparation steps before being added to the varnish system. These steps include chemical treatments to form a more or less uniform coating on the pigment surface. For this purpose, organic or inorganic coatings may be used.

US 4,434,009 describes a coating with polymeric metallic pigments. The coating is synthesized by monomers with polymerizable double bonds and epoxy groups.

Another metal pigmented polymer coating is described in JP 56-161470. The coating is formed from styrene, (meth) acrylonitrile or (meth) acrylic monomers.

Polymer-coated pigments are likewise described in german published application DE 2526093.

Metallic pigment coatings of synthetic resins are described in EP 0280749. Initially, these coatings included a binder layer having at least one ethylenically unsaturated double bond. This is followed by a polymeric synthetic resin, which can be synthesized from monomers having at least three ethylenically unsaturated bonds. The chemical variability of the monomers employed in EP 0280749 is greatly limited. The triene bond unsaturated monomer produces a high cross-linked polymer protective layer; however, a varnish cannot be synthesized. Such a polymer layer is too brittle for the synthetic varnish. Monomers capable of triple crosslinking or even higher degrees of crosslinking can be used as crosslinking agents in the varnish in amounts of up to 3% by weight and it is by no means possible for the entire polymer layer to be synthesized therefrom.

Similarly, DE 4030727 or EP 0477433 describe metallic pigment coatings prepared from three-dimensionally crosslinked plastic coatings which are covalently bonded to a silicone layer which is pre-deposited on the pigment. Thus, protected pigments suitable for use in water-based varnishes are obtained. According to the teachings of these two patents, adhesives are inherently applied to the surface of the metal sheet prior to the actual plastic resin coating, otherwise an effective coating would not be obtained.

One common factor known in the art for various polymer coatings is that they are all produced exclusively from monomers. These monomers are mostly polymerized by radical polymerization in the presence of a metal pigment dispersed in a solvent.

Furthermore, the surface modification resulting from the deposition of the surfactant on the pigment improves its wetting and binding to the binder (EP 1084198).

Furthermore, a process is described which can be used for powder-based varnishes in which the surface of the powder-based varnish particles is coated with a coloured or metallic pigment (DE 10058860 a 1). These methods have the disadvantage that the metal pigments adhere to the surface of the powder-based varnish particles as described above and are not encapsulated by or bonded to the powder-based varnish as described above, eventually leading to corrosion of the metal pigments after application.

WO 98/37154 discloses a process for the preparation of powder-based varnishes containing photopigments, which process uses supercritical fluids. This method is very expensive and requires elaborate equipment. In this process, the photopigment particles are dispersed in the powder pigment particles. The disadvantage is that the individual pigments cannot be effectively coated. For metallic pigments, this will cause corrosion problems during storage and after application.

WO 98/46682 discloses a powder-based varnish, the particles of which adhere to the surface of sticky metal pigments. One disadvantage of this method is that the powder-based varnish does not bond effectively and uniformly to the tacky metallic pigment surface. This uneven adhesion of the powder-based varnish particles results in an uneven varnish surface when the varnish is applied. Also, due to the sticky metallic pigment surface, the metallic pigment particles are prone to coagulate and/or aggregate in the powder-based varnish. Moreover, the coating does not effectively coat the metallic pigment. As a result, these metallic pigments are not stable to corrosion.

In the pigment coatings known in the art, the metallic pigments are produced with an inorganic or crosslinked polymeric layer which no longer participates in the crosslinking reaction of the typical powder-based varnish or the typical wetting varnish binder and/or curing agent. Therefore, these metallic pigments cannot be incorporated in a plastic matrix, and the corrosion resistance of the pigments is insufficient.

It is therefore an object of the present invention to provide a metallic pigment which has a high chemical and physical durability imparted by a highly effective coating and which can be easily incorporated into the medium of application. Examples of application areas are critical applications, such as in particular front-side coatings, which are generally exposed to the entire environmental impact without protection and which have to withstand an additionally long use.

Further, there is a need to improve the recyclability of the metallic colored powder-based varnish in the recovery unit of the coating booth.

Furthermore, it is desirable that such metallic pigments be low-dust, free-flowing powders. It is also desirable to ensure the versatility of metallic pigments in different powder-based varnish systems and liquid varnish systems.

It is another object of the present invention to provide a process for preparing such metallic pigments in high yield and at a cost effective rate. The process should be simple and ensure gentle handling of the metallic pigments.

This object is achieved by providing a coated metallic pigment, wherein the coating encapsulates the metallic pigment and comprises one or more crosslinkable oligomeric and/or polymeric binders that are chemically crosslinkable and/or crosslinkable by heat, UV radiation and/or electron radiation, and wherein the coated metallic pigmentPigment having a median particle diameter d₅₀Less than 190 μm and is corrosion stable in powder-based varnishes after curing.

Preferred developments are defined in the appended claims.

The object of the invention is also achieved by providing a masterbatch for powder-based varnishes and wetting varnishes, wherein the masterbatch contains a metallic pigment according to any one of claims 1 to 25.

Preferably, the binder used to encapsulate the metallic pigment is the same as the binder used in the powder-based varnish. The binders of the invention are therefore suitable for use as a masterbatch or concentrate for the production of powder-based varnishes containing metal pigments.

The same binder is used for coating the metallic pigments of the invention and for the powder-based clearcoats which, after application and curing, form a smooth clearcoat layer in which the metallic pigments are chemically bonded. The clearcoat layer has a unique, refined appearance and is corrosion-stable.

The object of the present invention is also achieved by providing a coating composition comprising a metallic pigment according to any of claims 1 to 26, and which is corrosion stable after curing of the coating composition.

Preferred embodiments are given in the appended claims.

Furthermore, the object of the invention can be achieved by providing a coated object coated with a metallic pigment according to any of claims 1 to 26 or with a coating composition according to any of claims 28 to 32.

The coated object is preferably an object which is subjected to corrosive environmental conditions, such as natural weather conditions. The object is assumed to be a facade element such as a tile facade, a window frame, a vehicle body (e.g. a motor vehicle body) or a vehicle frame (e.g. a frame of a bicycle or motorcycle).

The object of the invention is also achieved by the use of a metallic pigment according to any of claims 1 to 25 in paints, varnishes, powder-based varnishes, printing inks, plastics or nail varnishes.

The object of the present invention is also achieved by providing a nail varnish which comprises a metallic pigment according to any of claims 1 to 26.

The metallic pigments according to the invention therefore have an encapsulating coating which consists of a crosslinked binder in the form of oligomeric or polymeric radicals. Depending on their respective chemical nature, the binders may be polymerized under the action of heat, IR, UV and/or electron radiation, or by reaction with a suitable curing agent after encapsulation of the metallic pigments, so that the metallic pigments are embedded in the polymeric film. This complete encapsulation significantly improves the abrasion resistance and chemical stability of the metallic pigment. The weather stability achieved by the present process cannot be achieved with conventional metallic pigments.

In the context of the present invention, "corrosion resistance" is understood to mean that the optical appearance of the metallic pigment is not impaired, or is only slightly impaired, for a long period of time, for example after a few months or years, after the metallic pigment has been incorporated into the powder-based varnish and after the powder-based varnish has been applied and cured. As a measure of the corrosion resistance, mortar tests can be carried out according to GSB [ quality synergy of the lamellar coatings of the structural elements ] specification Gutegemeeinschaft fur die St ü ckbecchcherung von Bautelen e.V, described in the examples. Being able to pass this very stringent corrosion test is a prerequisite for the application of the metallic pigmented powder-based varnish to the front element. As described in further detail below, the ability to pass grinding tests is an indication of corrosion resistance within the scope of the present invention.

The coated metallic pigments of the present invention are preferably low-dusting, free-flowing powders, which may also be made into pastes with solvents such as organic solvents and/or water. The metallic pigments according to the invention are therefore characterized by a high degree of flexibility in application.

Within the scope of the present invention, metallic pigments are to be understood as being in the form of flakesA metal-effective pigment. The shape factor, i.e. the ratio of the longitudinal length to its average thickness, of these pigments is greater than 10, preferably greater than 20, more preferably greater than 50. More preferably, the shape factor is in the range of 50-1000, even more preferably in the range of 100-200. Longitudinal length is understood here to mean the d of the cumulative critical (breakthrough) curve₅₀Values as measured by standard laser granulometry. D of longitudinal length₅₀Values of 2 to 150. mu.m, preferably 3 to 75 μm, more preferably 5 to 60 μm.

Applied with a powder-based varnish, the metallic pigmented powder-based varnish has outstanding recyclability. The portion of the powder-based varnish that is not cured on the substrate in the presence of the metallic pigment of the present invention can be advantageously recycled and sprayed again in the next powder-based varnish application.

Within the scope of the present invention, adhesives are understood to be defined in DIN 55945. That is, the binder includes a film-forming agent as well as non-volatile agents such as plasticizers and drying agents.

Typically, the binder is present as a low molecular weight oligomer and/or polymer. The molecular weight is preferably 200-10000g/mol, more preferably 500-8000 g/mol. The viscosity achievable with the low molecular weight of the oligomers and/or polymers used is a viscosity which cannot be achieved with the dissolved monomer components or with the high molecular weight components (see p. nanetti, Coatings company "lackrohstoffkun", p.17ff., VincentzVerlag 2000). For the sake of simplicity, the oligomeric and/or polymeric binders used according to the invention are referred to below simply as "binders".

The curing agent is typically present in the form of a monomer. The thermoplastic binder, or the binder and possibly the curing agent, are initially reacted with each other under suitable conditions, such as at elevated temperature, to form a thermoset material. If a curing agent is used, polymerization, polycondensation or even polyaddition reactions can then occur.

This distinguishes the coating of the metallic pigments of the invention from polymer coatings known in the art. After the metallic pigment is coated with the binder, the binder remains curable or polymerizable. During the coating process with the solvent evaporation, the binder starts to polymerize slightly, but does not cure completely. On the other hand, synthetic coatings of metallic pigments are known in the art to be formed from monomers which react substantially quantitatively to form a polymeric film on the pigment surface. Most cured polymers are no longer reactive. .

The metallic pigments according to the invention thus have a reactive binder coating after application, in particular capable of reacting with binders such as varnishes or printing inks. After application, the applied coating of the binder-containing metallic pigment can then be cured without crosslinking with the binder of the application medium, such as a varnish or printing ink. This may be due to chemical incompatibility between the binder of the applied medium and the binder-containing coating.

The binder is preferably selected from the group of standard binders used in powder-based varnishes, e.g.

Polyesters containing carboxyl groups, preferably saturated polyesters containing carboxyl groups. They are reactive compounds having an acid number of preferably from 5 to 100mg KOH/g, more preferably from 20 to 70mg KOH/g. These resins can be combined with suitable curing agents to optimize the corrosion resistance required for outdoor applications as well as less important interior applications of the resin. Typical resins are UCB, Belgium,www.ucb.decrylcoat 340 and Crylcoat 632 are provided, or DSM, the netherlands,www.dsm.comthere is provided Uralac P2200,

-a hydroxyl-containing polyester, preferably a hydroxyl-containing saturated polyester. The hydroxyl number is preferably from 120 to 15mg KOH/g, more preferably from 50 to 30mg KOH/g. Typical resins are UCB, crycoat E5169 supplied by Belgium,

-a so-called dual cure resin available under the trade name Uranox from DSM, the Netherlands,

epoxy resins typically used in powder-based varnishes having an epoxy equivalent weight of 175-.

Acrylate resins typically used in powder-based varnishes and functionalized acrylate resins having, for example, hydroxyl functional groups, carboxyl functional groups or epoxy functional groups (e.g., those provided by Mitsui Tuatzo, Japan),

radiation-curable resins, preferably typically used for powder-based varnishes, for example unsaturated acrylates, such as epoxy acrylates, urethane acrylates, polyester acrylates, polyether acrylates and mixtures thereof. One example is UCB, UVECOAT 3001 supplied by Belgium,

silane-based, highly heat-stable binders, such as Silres resins, available from Wacker, Germany,

-functionalized resins, such as epoxy resins, polyester resins, preferably with functional groups of phosphate, phosphonic acid or esters thereof, sulfonate, carboxyl, amino, hydroxyl, carbamate, isocyanate and blocked isocyanate groups.

The curing agent used is preferably a compound having an enantiomer corresponding to the resin-reactive group. Examples of such compounds are:

-a compound selected from the group consisting of: beta-hydroxyalkylamides, e.g. Primid XL 552 supplied by Ems-Primid, Switzerland

Glycidyl-based compounds, such as triglycidyl isocyanurate (known as TGIC), for example Araldit PT 810 or Araldit PT910 from Huntsman, Switzerland

Compounds based on blocked and free isocyanates, e.g. Vestagon BF1540 or Vestagon BF 1530 supplied by Degussa

Epoxy curing agents based on organic salts, such as Vestagon B31 supplied by Degussa, Germany

Curing agents excited by radiation, e.g. IRGACURE 2959 and IRGACURE 819 supplied by Ciba Specialty Chemicals, Switzerland

Resins having groups complementary to the above resins

-amine curing agent

The metallic pigments used are preferably commercially available aluminum, copper, brass (gold bronze), iron, zinc, titanium, nickel and interference pigments with a metal core and/or a metal coating.

The pigments may be uncoated, but may also be primed, i.e. they may have an additional protective layer. These protective layers may be barrier layers such as SiO₂Or a polymeric, highly cross-linked polymer layer. Such primed metallic pigments potentially have even higher corrosion resistance. An example of such a pigment is PCR (SiO)₂Coatings, supplied by Eckart, F ü rth, Germany), PCA polymer coatings (supplied by Eckart) or PCF polymer coatings (supplied by Toyal, Japan).

Furthermore, it is also possible to use metallic pigments having a coloured coating, for example, pigments coated with iron oxide, such as paliocomThe product (supplied by BASF AG, Ludwigshafen, Germany) serves as starting pigment for the production of the pigments according to the invention.

Surprisingly, oxidized metal-effective pigments, such as aluminum pigments oxidized by chemical wetting, can also be used as starting pigments. Chemical wetting oxidation can be used to color aluminum pigments.

At elevated temperatures, copper and brass pigments oxidize in air to form metal oxide coatings that can impart additional attractive hues to the metal pigments.

For example, alumina pigments have been produced by specific chemical wetting methods according to the method described in EP 0848735, which is incorporated herein by reference, to produce attractive gold colored pigments. These golden yellow pigments are available from Eckart GmbH&KG, Furth, Germany under the trade name AloxalAnd (4) selling.

In chemical wet oxidation, a highly hydrated aluminum oxide/hydroxide layer is formed around the aluminum core. Heretofore, such chemically wet-oxidized pigments have not been used in powder-based varnishes because high-quality coatings could not be reproduced by applying a powder-based varnish containing chemically wet-oxidized aluminum pigments to the surface of a substrate. For the metallic pigment of the present invention, the surface of the coated pigment is aligned with the surface of the binder particles in the powder-based varnish. Thus, powder-based varnishes containing the metal pigments based on chemi-wetting oxidized aluminum pigments of the present invention can be applied perfectly to the substrate surface with reproducible quality levels.

The metallic pigments of the present invention may also be interference pigments having a metallic core coated with a low refractive dielectric layer and a high refractive metal oxide or metal layer. Examples of pigments which can be used for this purpose are those known under the trade name Variocrom(BASF AG) or Chromaflair(Flex Products, Inc.).

In the present study, metallic pigments were primed with a substance that improves the adhesion between the metallic pigment surface and the adhesive coating. These primer layers can be functionalized silanes, functionalized polymers, and organophosphorus compounds. These compounds may also be deposited on the supplemental coating.

Functionalized silanes are preferred.

The silanes used for this purpose are preferably those of the general formula (I)

(Y)R_(4-Z)Si(X)z (I)

In the silane compound of the general formula (I), Z is an integer of 1 to 3, R is a substituted or unsubstituted, linear or branched alkyl group having 1 to 12 carbon atoms, Y is a functional group capable of reacting with a corresponding adhesive functional group, and X represents a halogen group and/or an alkoxy group. R may also be bonded to Si in a cyclic form, in which case z is usually 2.

After condensation reaction of the Si (X) group with the OH group on the surface of the metallic pigment, the silane is bonded to the surface of the metallic pigment. On the other hand, the reactive functional group Y may influence the bonding with the subsequently deposited oligomeric and/or polymeric binder. These bonds may be covalent bonds or weaker interactions such as hydrogen bridges. It is important that oligomeric and/or polymeric binders bind to the surface of the metallic pigment with sufficient stability by using silanes as adhesion promoters so that most of the binder remains bound to the metallic pigment in the solvent dispersion prior to spraying. Thus, silanes can be used as adhesion promoters between the surface of the metallic pigment and the oligomeric and/or polymeric binders in the coating.

Isocyanates, epoxy groups, amino groups, hydroxyl groups, carboxyl groups, acrylates or methacrylates are preferred as functional groups Y. These groups react with corresponding chemically compatible counterpart groups of the oligomeric/polymeric binder. However, in this process, the adhesive is not completely cured. In other words, the oligomeric/polymeric binder retains its chemical crosslinkability and curability. The functional groups Y of the silane can react with, for example, functional groups of an oligomeric/polymeric binder that are not involved in, or only partially involved in, the curing of the oligomeric/polymeric binder. For example, the functional group of the oligomeric/polymeric binder may be, for example, in stoichiometric excess with respect to the functional group Y of the silane. On the surface of the metallic pigments primed with at least one silane compound of the general formula (I), the functional groups (Y) are always in a stoichiometric deficiency with respect to the corresponding chemically compatible corresponding functional groups of the subsequently deposited oligomeric and/or polymeric binder.

For example, Y may be an isocyanate and the binder comprises a polyester component having a polyol and a polycarboxy group. At room temperature, the isocyanate and the hydroxyl groups of the binder may react in the presence of a catalyst. Only after the metallic pigment is applied and added to the varnish system can the polyester coating be fully cured during the drying of the varnish system. The group Y is preferably a terminal group, since the terminal group has the lowest steric hindrance and is therefore the most reactive. However, Y may also be a group near the end, with up to 3 carbon atoms between the Y group and the chain end.

The functional groups of the binder that react with Y may be the same as the groups of the synthetic polymer during curing of the binder. As mentioned above, this may be because the oligo/polymeric binder functionality that reacts with Y is always in stoichiometric excess with respect to the Y functionality on the pigment surface, so that after reaction of the reactive group Y with the oligo/polymeric binder, there is still sufficient functionality on the oligo and/or polymeric binder for crosslinking or curing. The oligomeric/polymeric binder functionality reactive with the reactive group Y may optionally be different from the functionality involved in binder curing.

Organofunctional silanes suitable for use as surface modifiers with corresponding functional groups are commercially available. An example of such a silane is the Dynasylan trade name from Degussa, RheinfeldenA number of representative products of (1), Silquest by OSi SpecialtiesGENOSIL produced by silane and WackerA silane.

Specific examples include methacryloxypropyltrimethoxysilane (Dynasylan MEMO, Silquest A-174NT), 3-mercaptopropyltris (methoxy) ethoxysilane (Dynasylan MTMO or 3201; Silquest A-189), 3-glycidoxypropyltrimethoxysilane (Dynasylan GLYMO, Silquest A-187), tris (3-trimethoxysilylpropyl) isocyanurate (Silquest Y-11597), gamma-mercaptopropyltrimethoxysilane (Silquest A-189), beta- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane (Silquest A-186), gamma-isocyanatopropyltrimethoxysilane (Silquest A-Link 35, Genosil GF40), (methacryloxymethyl) trimethoxysilane (Genosil XL 33), isocyanatomethyl) trimethoxysilane (Genosil XL 43), Aminopropyltrimethoxysilane (Dynasylan AMMO; Silquest A-1110), aminopropyltriethoxysilane (Dynasylan AMEO) or N- (2-aminoethyl) -3-aminopropyltrimethoxysilane (Dynasylan DAMO, Silquest A-1120) or N- (2-aminoethyl) -3-aminopropyltriethoxysilane, triamino-functionalized trimethoxysilane (Silquest A-1130), bis (gamma-trimethoxysilylpropyl) amine (Silquest A-1170), N-ethyl-gamma-aminoisobutyltrimethoxysilane (Silquest A-Link15), N-phenyl-gamma-aminopropyltrimethoxysilane (Silquest Y-9669), 4-amino-3, 3-dimethylbutyltrimethoxysilane (Silquest Y-11637), (N-cyclohexylaminomethyl) triethoxysilane (Genosil XL 926), (N-phenylaminomethyl) trimethoxysilane (Genosil XL 973) and mixtures thereof.

Silanes, preferably of the general formula (I), can be deposited directly on the metal surface of the metallic pigment. According to a preferred embodiment, the metallic pigment has SiO₂Coating, preferably with SiO₂Coating encapsulation, silane deposition on said SiO₂And (4) coating. Then, an oligomeric and/or polymeric binder is deposited on the metallic pigment to form a primer.

In the present study, organic and inorganic colored pigments and colorants can be present in the coating to obtain colored metallic pigments. In this way, it is particularly useful for the preparation of coloured effect pigments having high corrosion resistance:

(a) coloured pigments

i) Organic colour pigments

Organic colored pigments include commercially available monoazo, disazo, anthraquinone, phthalocyanine blue, phthalocyanine green, perylene, Perinone (Perinone) pigments, indigo, thioindigo, indolinone, isoindolinone pigments, quinacridone, pyrrolopyrrolidinone, dioxazine pigments and metal complex pigments such as copper azomethine yellow, as well as other types and pigments listed in Herbst & Hunger in Industrial grade org.Pigmente, VCHVerlagsgesellschaft mbH, Weinheim, Germany (1987).

ii) inorganic coloured pigments

Inorganic colored pigments include iron oxide pigments, lead chromate pigments, chromium oxide pigments, ultramarine pigments, complex inorganic colored pigments, iron blue pigments, cadmium pigments, bismuth vanadate pigments, cerium sulfide pigments, commercially available titanium dioxide and zinc sulfide white pigments, as well as other types and pigments listed by Hartmut Endriss in "Aktuelle and Buntpigment", Vincentz-Verlag.

(b) Dye material

Examples of suitable migration-stable dyes are heavy metal salts which are complexed with azo ligands, and organometallic compounds which have at least one azo group and/or chromophore group and are soluble in the medium used, such as solvent yellow 79, solvent red 8, solvent blue 45 and solvent black 45 from Clariant, Basel, Switzerland.

In a development of the invention, corrosion inhibitors may also be present in the coating. The corrosion inhibitors may have an anodic or cathodic action, optionally mixed. Corrosion resistant pigments may also be used as corrosion inhibitors. Examples of these are: strontium zinc silicophosphate, zinc aluminum polyphosphate hydrate, zinc calcium aluminum strontium phosphate hydrate, zinc calcium strontium orthophosphate silicate hydrate, strontium aluminum polyphosphate hydrate, calcium aluminum polyphosphate hydrate and sodium and/or calcium and/or zinc molybdate and/or molybdenum phosphate and/or zinc phosphate complexes, or mixtures thereof.

Preferably, the corrosion resistant pigment has an average particle size of 0.1 to 10 μm, preferably 0.15 to 5 μm.

The metal pigments may also be primed with silica, metal oxides, organophosphate compounds, preferably with phosphate and/or phosphonic acid compounds, and/or polymers to impart or improve corrosion resistance.

In a further development of the invention, further standard varnish and powder-based varnish additives may also be present in the coating material, so that the metallic pigments according to the invention have specific application properties in the application medium.

Preferred supplementary ingredients are selected from: additives, fillers, degassing agents, film formers, flame retardants, adhesion promoters, corrosion inhibitors, light stabilizers, flatting agents, photoinitiators, polymerization inhibitors, polymerization initiators, free radical blockers (radicallinateceptors), antiblocking agents, slip agents, radiation curing reaction diluents, thermal crosslinking reaction diluents, UV absorbers, leveling agents, crosslinking catalysts, waxes, and mixtures thereof.

The metallic pigments of the present invention may also be used in combination with other pigments in coating compositions, masterbatches or powder-based varnishes. According to a preferred embodiment, the metallic pigments of the invention can be used in combination with pearlescent pigments. Pearlescent pigments do not corrode and are therefore suitable for coatings that are subjected to corrosive conditions such as natural weathering. The inventive mixtures of metallic pigments and pearlescent pigments are therefore suitable for use in powder-based varnish systems for powder-based varnish coatings for facade elements, car bodies, vehicle frames and the like.

The binder content of the metal pigments of the invention is frequently from 20 to 85% by weight, preferably from 52 to 75% by weight, more preferably from 55 to 60% by weight, based on the total weight of the coated metal pigment.

The binder is preferably non-polymerizable or substantially non-polymerizable during or after application of the metallic pigment. After the metal pigments of the invention are added to the application medium but before the product varnish is dried, the binder around the metal pigments is preferably non-polymerizable. In this case, thermal polymerization occurs.

However, for adhesives which polymerize by free radical polymerization, curing by UV or IR radiation is also possible. In this case, the binder in the varnish and the binder in the coating may be polymerized, and the binder in the varnish is preferably crosslinked with the binder in the coating.

The main advantage of the metallic pigments according to the invention is that the adhesion of the metallic pigments to the binder in the varnish is greatly increased. This effect is particularly pronounced when the binder used to coat the pigment is the same as that used in the application medium.

Due to the lamellar structure of the metallic pigments, the metallic pigments are often likely to damage the varnish coating, thereby reducing the mechanical stability of the coating or varnish film. However, the metallic pigments according to the invention are preferably oriented in the coating layer when the coating is cured, as a result of which the mechanical and chemical stability of the coating is increased.

Thus, it was found that the cured powder-based varnish containing the inventive metallic pigment has significantly better abrasion resistance than conventional powder-based varnish coatings. Surprisingly, the cured powder-based varnish coatings of the present invention have new attractive effects. The surface of the substrate coated with the powder-based varnish of the present invention gives the viewer a metallic feeling with spatial depth. It is believed that the good adhesion of the metallic pigment to the powder-based varnish coating produces the beneficial properties described above. The content of the metallic pigment exhibiting leafing characteristics in the metallic pigment of the present invention is negligible or not at all.

Surprisingly, it has been found that the pigments encapsulated by the binders of the present invention can also be used as a masterbatch in powder-based varnishes. In a masterbatch, the binder is preferably present in an amount of 50 to 85 wt%, more preferably 55 to 80 wt%, most preferably 60 to 75 wt%.

Masterbatches are commonly used in plastic materials. In this case, the masterbatch is a highly coloured synthetic material added to the plastic material composition in the extruder.

In powder-based varnishes, metallic pigments produced by conventional bonding methods represent a class of masterbatch properties. However, with metallic pigments, the achievable level of coloration is only about 8% at the maximum.

The metallic pigments coated with the invention can achieve significantly higher concentrations of metallic pigment, i.e. in this case indeed can be referred to as masterbatches. This is particularly true for metallic pigments coated with the same binder system (i.e., powder-based clearcoats), where the metallic pigments can also be added and processed subsequently.

In the present invention, it is often most desirable to prepare a masterbatch or coating composition having a metal content of preferably from 0.5 to 15% by weight, more preferably from 1 to 12% by weight, most preferably from 2 to 8% by weight, based on the total weight of the masterbatch or coating composition.

The high level of coloration of the masterbatches and coating compositions achievable by the present invention opens up completely new possibilities. The use of highly coloured or highly concentrated masterbatches is a major advantage, for example, in terms of transport. Since the higher the concentration of the masterbatch, the less masterbatch is needed to achieve the same final powder-based varnish concentration, less masterbatch needs to be transported.

In the coating composition, higher metal pigment concentrations result in better coverage for substrates coated with metal pigments than in conventional powder-based varnish systems.

Furthermore, the present invention provides a process for the preparation of the metallic pigment according to any one of claims 1 to 26. The method comprises the following steps:

a) preparing a solution or dispersion of an oligomeric and/or polymeric binder in an organic solvent,

b) coating a metallic pigment with the binder by:

i) dispersing the metallic pigment in the solution or dispersion prepared in a) and then atomizing, or

ii) spraying the solution or dispersion prepared in a) onto a metallic pigment fluidized in a gas stream,

c) the binder-coated metallic pigment is dried in a turbulent air flow.

It is obvious that alternatively the dispersion of the metal pigment with the binder or binder solution can be made by first dispersing the metal pigment in an organic solvent and then adding the oligomeric and/or polymeric binder in dissolved or undissolved form, and then atomizing the dispersion in step i) of step b).

Preferred embodiments of the method according to the invention are given in the appended claims. The description of the metallic pigment or coating composition of the invention is also useful for explaining the process of the invention.

The metal pigment is insoluble in an organic solvent, and forms a dispersion with the solvent or a compound dissolved in the solvent. The binders and possibly other additives and/or agents such as curing agents which may be used are preferably soluble in organic solvents. However, when they are insoluble in organic solvents, they may be present in the form of a dispersion.

Other additives and/or agents are preferably added to the solution or dispersion of the oligomeric and/or polymeric binder in the solvent before the binder is contacted with the metallic pigment.

The additives and/or reagents preferably used have already been listed above. When the additives and/or agents are added to a solution or dispersion of a polymeric or oligomeric binder, the additives and/or agents are preferably uniformly distributed in the coating applied to the metallic pigment.

Additives and/or agents may include (for example): curing agents, photoinitiators and/or polymerization initiators. Furthermore, the additives and/or agents may include corrosion inhibitors, preferably corrosion resistant pigments. Additives and/or agents have been detailed above.

Water, organic solvents or hydrated organic solvents may be used as the solvent. Preferably, the organic solvent contains less than 2 wt% water, more preferably less than 1 wt%, and most preferably less than 0.5 wt%. The weight percentages given here are based on the total weight of the solvent used.

In another preferred embodiment of the process of the invention, binders having an affinity for the pigment can be used in the coating of the metallic pigment. It is understood that binders having affinity for the pigment have groups that act as adhesion promoters, binding the metallic pigment while it is still in the pigment/binder dispersion. Examples of such agents include epoxy resins, epoxy resin modified phosphates such as Resydrol VAX 5538w/50 WA supplied by UCB Surface Specialities, carboxy functional resins, phosphonate functional resins, phosphate functional resins, and sulfonate functional resins. These resins bond to the surface of the metallic pigment while the metallic pigment is still dispersed in the solvent.

When silanization reagents such as those described above are used, said reagents are preferably deposited on the surface of the metallic pigment in the same organic solvent as used for the preparation of the oligomeric and/or polymeric binder solution or dispersion. Silanization of metallic pigments can be achieved by shaking or stirring at elevated temperature, optionally with addition of water and/or catalyst. Slightly volatile organic bases such as ammonia, slightly volatile amines, etc. are preferred as catalysts.

During the subsequent spraying of the metallic pigment dispersion, less spherical secondary precipitates and the coating quality is improved. It is believed that extensive priming of the metallic pigment with a binder prior to spraying results in an improved coating, with the remainder of the binder not binding to the metallic pigment. Priming of the dispersion with a binder having pigment affinity already results in a nucleation effect that promotes the formation of a higher degree of smooth coating when the dispersion is sprayed.

Removal of the solvent or drying of the coated metallic pigment is preferably achieved by simultaneous or subsequent fluidization of the coated metallic pigment.

Fluidization of the coated metallic pigment is effective to prevent aggregation or agglomeration of the metallic pigment. Since the metallic pigments in the applied clear coat paint act in the manner of many tiny mirrors, agglomeration of the metallic pigments should be avoided so as not to detract from the optical appearance of the coating.

In a first variant of the invention, it is preferred to combine steps (bi) and (c), spraying the coated metallic pigment by spray drying and removing the solvent.

The residual moisture in the dried metallic pigments of the invention is preferably less than 4% by weight, more preferably less than 2% by weight, most preferably less than 1.2% by weight, based on the total weight of the metallic pigment of the invention. Higher residual moisture levels can make the coated pigment surface sticky, presenting defects that cause undesirable aggregation and/or agglomeration.

Spray drying is a cost-effective drying process that can ensure high yields simultaneously. Spray drying can be in batch mode of operation and in continuous mode of operation. The metallic pigments of the invention are preferably prepared using a spray-drying process.

In spray drying, the dispersion is atomized or atomized in the closed space of the apparatus under suitable spray pressure. The injection pressure is adjusted according to external conditions such as solid content, viscosity of the dispersion to be injected, temperature in the reactor, type of solvent, etc., and can be easily determined by those skilled in the art. Atomization in a gas stream such as air or nitrogen is preferred. The droplets formed cause substantial evaporation of the solvent due to the significant increase in surface area, which can be further promoted by increasing the carrier gas temperature. Thus, the temperature is selected so that the reactive coating on the metallic pigment does not substantially polymerize or cure.

In spray drying, atomization can be achieved with a centrifugal atomizer, for example a spray disk or spray wheel with a pressure nozzle, two substance nozzle or a rotating nozzle. The gas flow may be in co-current or counter-current mode through the device. For spray drying in mixed flow mode, the spray nozzles are mounted in the lower part of the drying tower and spray upwards like a fountain. The product from the spray tower is separated from the gas stream and separated by a cyclone and filter.

Furthermore, a combined method involving a so-called fluidized spray dryer may be used to dry the sprayed suspension. The method combines the advantages of fine droplet spray drying with fluidized bed spray drying. Obviously, other spray drying methods may be used, if desired.

According to another preferred embodiment of the invention, the steps (bii) and (c) are combined, coating and drying being carried out with metallic pigments in a fluid or fluidized bed, wherein an oligomeric and/or polymeric binder dissolved or dispersed in a solvent is sprayed, which solvent is removed when fluidization is carried out in the fluid or fluidized bed.

This variant of the method is the same as the fluid bed coating. Thus, the pigment is introduced into a closed spray-drying apparatus and fluidization is achieved by blowing in pressurized air or pressurized nitrogen. The volume of pressurized air or pressurized nitrogen is selected to produce a smooth, non-turbulent surface. The binder solution or dispersion is then sprayed through a nozzle into the agitated fluid bed. The solvent is then removed, for example by heating, as described in the first variant of the process, and the metallic pigment of the invention is then dried.

Pigment/binder/solvent for spray drying, or binder solution or dispersion coatings for fluid beds can be prepared using, for example, the following organic solvents: alcohols, ethers, esters, ketones and aliphatic and aromatic hydrocarbons with boiling points below 130 c can produce pigment/binder/solvent or binder solution or dispersion coatings for spray drying. Acetone and ethyl acetate are particularly preferred. However, mixtures of the above organic solvents may also be used. Water or water-solvent mixtures may also be used.

The dispersion is preferably sufficiently fluid that it can be easily sprayed through a nozzle. The solvent content of the dispersion is from 50 to 97% by weight, preferably from 50 to 85% by weight, more preferably from 50 to 75% by weight, based in each case on the total weight of the dispersion.

The pressure of the pressurized air or nitrogen introduced into the apparatus is preferably 1 to 5bar, more preferably 2 to 4 bar.

The temperature at which the solvent is evaporated depends mainly on the nature of the solvent. The temperature is preferably from 0 to 130 ℃ and particularly preferably from 20 to 80 ℃.

The temperature is preferably chosen so that the solvent is better evaporated and the adhesive coating does not polymerize to any significant extent, preferably not aggregate at all. However, slight polymerization of the binder is not prohibited and may be insignificant as long as the binder still maintains sufficient reactivity.

The metal pigment according to the invention, prepared according to two variants of the above-described process, is a free-flowing, low-dust powder, the d of which₅₀The particle size is less than 190. mu.m, preferably less than 100. mu.m. Preferably d₅₀The particle size is at least 5 μm, and therefore, the metallic pigment is not particulate. The particle size of the particles is typically in the order of millimeters.

After the preparation process, the metallic pigments of the invention can be separated or sieved in order to ensure a specified particle size distribution of the product.

The metal pigment powder of the invention can be prepared as a paste by treating it with a suitable mobile phase, preferably a solvent. The pigment content in the paste is preferably 30-80 wt.%, based on the total weight of the paste.

The solvent used for the preparation of the paste is preferably water or an organic solvent, such as an aliphatic hydrocarbon (white spirit), an aromatic hydrocarbon (solvent naphtha), an alcohol, an ester, a ketone, an aldehyde, an ether or a mixture thereof.

For this purpose, only solvents which do not release the binder from the metallic pigment can be used. Aliphatic and/or aromatic hydrocarbons are preferred.

The coated metallic pigments of the invention are preferably used for the production of paints, varnishes, powder-based varnishes, printing inks, plastics materials and cosmetics.

The invention is illustrated by the following examples and figures, which however do not constitute a limitation of the invention.

Example 1:

125g of a saturated polyester of acid number 70 (Crylcoat 340, supplied by UCB, Belgium) and 125g of an epoxy resin of epoxide equivalent weight 750 (Araldit GT 6063 ES, supplied by Vantico, Switzerland) were dissolved in 1800g of acetone and 250g of Standard Spezial PCR501 (d.g.Standart Spezial PCR501 (r.d.₅₀20 μm) (from Eckart, Fuerth, Germany). 2300g of the dispersion were sprayed into a spray dryer at a rate of 30 g/min in a stream of hot air at a temperature of 55 ℃ and a spray pressure of 2.5 bar. 483g of pigment are obtained.

FIG. 1 shows a scanning electron micrograph of a metallic pigment coated in example 1 of the present invention.

FIG. 2 shows the starting pigment (comparative example 6).

Comparing the two figures shows that the metallic pigment of the present invention is completely encapsulated by the binder coating.

Example 2:

125g of a saturated polyester of acid number 70 (Crylcoat 340, supplied by UCB, Belgium) and 125g of an epoxy resin of epoxide equivalent weight 750 (Araldit GT 6063 ES, supplied by Vantico, Switzerland) were dissolved in 1800g of acetone and 300g of Dorolan Reichbleichgold 10/0 (supplied by Eckart) were added with stirring. 2300g of the dispersion were sprayed into a spray dryer at a rate of 30 g/min in a stream of hot air at a temperature of 55 ℃ at a spray pressure of 2.5 bar. 537g of pigment were obtained.

Example 3:

a saturated polyester of 125 acid number 70 (e.g., Crylcoat 340, supplied by UCB, Belgium) and 125g of an epoxy resin of 750 epoxide equivalent weight (e.g., Araldit GT 6063 ES, supplied by Vantico, Switzerland) were dissolved in 1800g of acetone and 50g of the Standard Spezial PCR501 were added with stirring. 2100g of the dispersion were sprayed into the spray dryer at a rate of 30 g/min in a stream of hot air at a temperature of 55 ℃ and a spray pressure of 2.5 bar. 288g of pigment were obtained.

Example 4:

example 1 was repeated except that Standart 212 (d) was used₅₀50 μm; supplied by Eckart) as an aluminum pigment. The pigment was not primed.

Comparative example 5:

commercially available STANDART aluminum powder Spezial PCR501 (supplied by Eckart).

Comparative example 6:

commercially available STANDART gold brass powder dololan Reichbleichgold 10/0 (supplied by Eckart).

Comparative example 7:

commercially available STANDART PCA 501(d5o ═ 201lm) (supplied by Eckart).

Comparative example 8:

commercial PCF 7130 (d)₅₀20 μm; supplied by Toyal, Japan). This is an aluminum pigment having a three-dimensional cross-linked polymer layer (polymerized from monomers).

Comparative example 9:

commercial Standard aluminum pigment 212 (STAPA)Metallux 212；d₅₀50 μm, supplied by Eckart) in dry form.

Example 10:

example 1 was repeated except that a commercially available Aloxal 3010 (d) was used₅₀18 μm, supplied by Eckart) as a starting material.

Comparative example 11:

commercial Aloxal 3010 (d)₅₀18 μm, supplied by Eckart), was dried, but no additional coating was applied. This application shows a non-uniform spray pattern.

The following suitability test shows that the coated metallic pigments according to the invention have an improved stability in application (single-coat clearcoat, i.e. without a clear clearcoat layer).

Testing the resistance to various acids and bases

Condensate/constant climate test (according to DIN 50017)

According to GSB (Gutegemeinschaft fur die St ü ckbecchtichtung von Bautelen e.V. (Mass bond of sheet coatings of structural elements), SchwMortar (mortar) test as specified by bisch-Gmnd, D-73525, Germany).

In the resistance tests to various acids and bases, test panels were coated with each of the powder-based varnishes of the examples or comparative examples of the present invention, as shown below, in contact with various concentrations of hydrochloric acid, sulfuric acid and sodium hydroxide droplets. The droplets were allowed to react on each plate for 5 minutes to 3 hours. After rinsing to remove acid or base, the degree of greyscale fading of each drop was evaluated according to the following criteria:

0 min is not corrosive

Corrosion hardly recognizable in 1 ═ m

Clearly identifiable corrosion in 2 ═ m

Complete gray scale fading

The total score for the total 14 drop area was calculated to be 0-42.

GSB (mass bond of structured element flake coatings) mortar tests were performed on test panels with a pigmented front surface coating (powder-based varnish). The specified amount of lime mortar was applied to the test panels as specified by AAMA 603-7-1976 or AAMA 2604-98 (AAMA: American architectural Manual Association). The test panels were then immediately exposed to 100% relative humidity at 40 ℃ for 24 hours.

To pass this test, it is necessary after 24 hours to be able to easily remove the mortar from the coated surface with a wet cloth and to easily remove any residues. Moreover, there was no sign of tack loss by nature in the powder-based clear coat film and no discernible change in surface appearance observed with the naked eye. This test is a particularly stringent chemical test, since the pH in wet mortar is usually from 11 to 12. Typically, in single layer clearcoat coatings containing aluminum pigments, highly undesirable gray scale fading occurs on stressed surfaces. However, the metallic appearance of the varnish coating should be apparent at least close to the undamaged state. Especially for aluminium pigments, this test indicates the stringent requirements that are not met by the commercial systems.

Mortar tests were visually rated according to the system described in DIN 53230 and the degree of greyscale fading of the weathered zones in the examples was evaluated, expressed in 0-5 points. The standard reference is an un-weathered slab or an un-weathered slab.

Scoring device	Critical
		0	Without change
1	Gray scale fading trace
		2	Slight greyscale fading
3	Moderate gray fading (foil still distinguishable)
		4	High gray scale fading (foil hardly distinguishable)
5	Ultra high gray scale fading

For the stress test, the powder-based varnish was applied in a commercial polyester/Primid system (available from DuPont, Essenbach, Germany). The level of pigment deposition in the examples of the invention was initially 5 or 10% by weight of the coated metallic pigment, based on the aluminum content, 2.5 or 5% by weight, respectively. Comparative pigment deposition was only 1 wt%. Generally, such low levels of pigment deposition in stress tests produce better results because in such cases the binder of the coating improves the stability of the metallic pigment.

Table 1: durability test results

Sample (I)	Chemical test scoring	Condensed water/constant climate (DIN 50017)	GSB mortar test
				Example 1	0	Greater than 1000 hours	1
Example 2	3	Greater than 1000 hours	1
				Example 3	0	Greater than 1000 hours	1

Example 4	4	Greater than 1000 hours	2-3
				Comparative example 6	24	72 hours	5
Comparative example 7	31	500 hours	4
				Comparative example 8	15	108 hours	4
Comparative example 9	3	Greater than 1000 hours	3
				Example 10	0	Greater than 1000 hours	1
Comparative example 11	3	Greater than 1000 hours	4

The results show that the pigments coated with the present invention are significantly less damaged by acids and bases than with conventional pigments.

Similarly, in the condensation water/constant climate test, the pigments coated with the invention exhibit a significantly better durability than the conventional metallic pigments.

In the mortar test, all the conventional aluminum pigments tested so far showed a marked change in surface appearance, i.e., gray fading of the surroundings with mortar deposition. The same is true of comparative example 9, which performs well in other stress tests.

In the inventive coated metallic pigments of examples 1 to 3, the change in the surface was hardly recognizable. Thus, the coated aluminum pigments of the present invention pass this test and thus meet the important requirements for powder-based varnish applications for facade systems such as tile facades.

The recycling advantage of the coated metallic pigments of the present invention for powder-based varnish applications is demonstrated after the varnish has been whirled three times. Although the conventional metallic pigment after application of the cyclone (comparative example 6) showed a large color change due to partial delamination of the metallic pigment and the powder-based varnish, no discernible change was found in the application of the coated metallic pigment of the present invention.

In addition to metallic luster, the cured powder-based varnishes containing the metallic pigments of the present invention give the coatings an unusual depth of space as perceived by the observer. Moreover, the cured powder-based varnish of the present invention has unique abrasion resistance. The abrasion resistance can be determined by the so-called "Tesa test" in which the adhesive tape is stuck to the surface of the substrate coated with the varnish and then pulled off. With the cured powder-based varnish of the present invention, no varnish was peeled off.

Another advantage of the coated metallic pigments of the present invention is improved processing characteristics during powder coating. Aggregates are formed in the spray gun due to the difference between the electrostatic charge properties of the metallic pigment and the powder-based varnish binder. This results in the formation of a cake of pigment in the spray application. The formation of the pigment agglomerates was visually assessed according to the following scale given in DIN 53230:

0 minute: formation of pigment-free lumps

1 minute: first visual observation of pigment lump formation

And 2, dividing: low pigment lump formation

And 3, dividing: formation of a moderate pigment lump

And 4, dividing: high pigment lump formation

And 5, dividing: extremely high pigment lump formation

For purposes of comparison, a large number of aluminum pigments, which are generally difficult to bond, were tested. The uncoated aluminum pigment of comparative example 9 was applied as a dry blend and a bonded powder-based varnish. On the other hand, example 4 of the present invention was applied as a simple dry blend.

As a result:

example 4: 0-1

Comparative example 9, dry blend: 3

Comparative example 9, bonded: 1-2

Thus, the coated aluminum pigments of the present invention achieve significantly improved application even as simple dry blend formulations, as compared to bonded aluminum pigments that have not been primed with the binder of the present invention.

For use in the wet varnish system, a gassing test was carried out under the same conditions on a commercially available water-based varnish system from Mischlacksilber (BASF, Wurzburg), and the amount of hydrogen obtained in each case was determined. If less than 22ml of hydrogen is produced after 30 days, the test is considered to be passed.

Example 1: 12ml after 30 days

Comparative example 6: more than 19ml after 2 days

In the case of comparative example 6, the test was terminated after 2 days because the amount of hydrogen generated was too large.

Claims (51)

1. A metallic pigment having a coating encapsulating said metallic pigment, said coating comprising a polymeric binder which is chemically crosslinkable and/or crosslinkable by the action of heat, infrared radiation, ultraviolet radiation and/or electron radiation, said coated metallic pigment being present as a platelet-shaped, metal-effective pigment having a shape factor in the range of from 50 to 1000 and a longitudinal length d₅₀Having a value of 2 to 150 μm, which after curing in a powder-based varnish is corrosion-resistant, said metal being based on the total weight of the coated metal pigmentThe pigment contains 20-85% by weight of a polymeric binder.

2. The metallic pigment of claim 1, wherein said coated metallic pigment has a particle size of 5 to 100 μm.

3. A metallic pigment as in claim 1, wherein said polymeric binder is an oligomeric binder.

4. Metallic pigment according to claim 1, characterized in that the coating contains additives and/or adjuvants in addition to the binder.

5. Metallic pigment according to claim 4, characterized in that the additives and/or adjuvants comprise organic and/or inorganic colored pigments and/or dyes.

6. A metallic pigment according to claim 4, characterized in that the additives and/or adjuvants comprise curing agents, photoinitiators and/or polymerization initiators.

7. A metallic pigment according to claim 4, characterized in that the additive and/or adjuvant further comprises a varnish component.

8. A metallic pigment according to claim 7, characterized in that the clearcoat component is a filler, a degassing agent, a film-forming agent, a flame retardant, a tackifier, a light stabilizer, a flatting agent, a polymerization initiator, a radical blocker, an antiblocking agent, a slip agent, a radiation-hardening reaction diluent, an ultraviolet absorber, a flow-control agent, a crosslinking catalyst and/or a wax.

9. The metallic pigment of claim 1, wherein said metallic pigment is primed with a binder, with an additional crosslinked layer, or with multiple additional crosslinked layers prior to application of said coating.

10. The metallic pigment of claim 9, wherein the metallic pigment is undercoated with silica, a metal oxide, an organophosphoric acid compound, and/or a polymer.

11. The metallic pigment of claim 10, wherein said organic phosphoric acid compound is a phosphate and/or phosphonic acid compound.

12. The metallic pigment of claim 9, wherein the metallic pigment is primed with an adhesion promoter for adhesive coatings.

13. The metallic pigment of claim 12, wherein said adhesion promoter is a functionalized silane, a functionalized polymer, and/or an organophosphorus compound.

14. The metallic pigment of claim 1, wherein said binder is selected from the group consisting of: polyester resins, epoxy resins, acrylates and mixtures thereof.

15. The metallic pigment of claim 14, wherein the polyester resin is a saturated polyester resin containing a carboxyl group and having an acid value of 20 to 70mg KOH/g, and mixtures thereof.

16. The metallic pigment of claim 14, wherein the epoxy resin is selected from the group consisting of: those having an epoxide equivalent weight of 400-2500.

17. A metallic pigment as claimed in claim 1, characterised in that the crosslinking of the binder and any curing agent present is thermally inducible.

18. The metallic pigment of claim 1, wherein the binder-containing coating comprises a corrosion inhibitor.

19. The metallic pigment of claim 18, wherein the corrosion inhibitor is an anodic and/or cathodic corrosion inhibitor.

20. The metallic pigment of claim 18 or 19, wherein the corrosion inhibitor is a corrosion resistant pigment.

21. The metallic pigment of claim 20, wherein said corrosion resistant pigment is strontium zinc silicophosphate, zinc aluminum polyphosphate hydrate, calcium aluminum strontium silicophosphate hydrate, calcium strontium calcium orthophosphate hydrate, strontium aluminum polyphosphate hydrate, calcium aluminum polysilicate hydrate, and sodium and/or calcium and/or zinc molybdate and/or molybdenum phosphate and/or zinc phosphate complexes, and mixtures thereof.

22. The metallic pigment of claim 18 or 19, wherein said corrosion resistant pigment has an average particle size of 0.1 to 10 μm.

23. The metallic pigment of claim 22, wherein said corrosion resistant pigment has an average particle size of 0.15 to 5 μm.

24. The metallic pigment of claim 1, wherein said metallic pigment is selected from the group consisting of aluminum, copper, iron, titanium, nickel, zinc, and brass pigments, and mixtures thereof.

25. The metallic pigment of claim 1, wherein said metallic pigment is an oxidized metallic pigment.

26. The metallic pigment of claim 25, wherein said oxidized metallic pigment is a copper oxide and/or brass pigment.

27. The metal pigment of claim 1, wherein the metal pigment is a chemical wetting oxidized aluminum pigment.

28. The metallic pigment of claim 1, wherein the metallic pigment is a metal-containing interference pigment having a metallic core and/or a metallic coating.

29. The metallic pigment of claim 1, wherein the powder is present as a paste combined with a liquid phase.

30. The metallic pigment of claim 29, wherein the powder is present as a paste combined with an organic solvent.

31. A masterbatch of a powder-based varnish, characterized in that the masterbatch comprises a metallic pigment according to any one of claims 1 to 28.

32. A coating composition comprising the metallic pigment of any one of claims 1-30, wherein the metallic pigment is corrosion resistant after the coating composition is cured.

33. The coating composition of claim 32, wherein the coating composition comprises a powder-based varnish.

34. The coating composition of claim 32 or 33, wherein the coating composition has a metal content of 0.5 to 15 wt.%, based on the total weight of the coating composition.

35. The coating composition of claim 34, wherein the coating composition has a metal content of 1 to 12 wt.%, based on the total weight of the coating composition.

36. The coating composition of claim 34, wherein the coating composition has a metal content of 2 to 8 wt.%.

37. The coating composition of claim 33, wherein the powder-based varnish and metallic pigment coating contain the same binder.

38. A coated object coated with a metallic pigment according to any of claims 1-30 or a coating composition according to any of claims 32-37.

39. The coated object of claim 38, wherein the object is a facade element facade tile, window frame, vehicle body, or vehicle frame.

40. The coated object of claim 39 wherein said facade elements are facade tiles, said vehicle body is an automotive vehicle body, and said vehicle frame is a bicycle or motorcycle frame.

41. A method of preparing the metallic pigment of any one of claims 1-30, the method comprising the steps of:

a) preparing a solution or dispersion of a polymeric binder in an organic solvent,

b) coating a metallic pigment with the binder by:

i) dispersing the metallic pigment in the solution or dispersion prepared in a) and then atomizing, or

ii) atomizing the solution or dispersion prepared in a) onto a metallic pigment fluidized in a gas stream,

c) the binder-coated metallic pigment is dried in a turbulent air flow.

42. The method of preparing a metallic pigment of claim 41, wherein after step c), the binder coated metallic pigment is further sieved.

43. A method according to claim 41 or 42, further comprising adding additives and/or adjuvants to the solution or dispersion of the polymeric binder in the solvent, preferably before contacting them with the metallic pigment.

44. The method of claim 43, wherein the additives and/or adjuvants comprise curing agents, photoinitiators and/or polymerization initiators.

45. The method of claim 43, wherein the additives and/or adjuvants include corrosion inhibitors and corrosion resistant pigments.

46. A process as claimed in claim 41, wherein the solvent used is water, an organic solvent or an aqueous organic solvent.

47. The method of claim 41, wherein steps (bi) and (c) are combined to atomize and remove solvent from the coated metallic pigment by spray drying.

48. A method as claimed in claim 41, wherein steps (bii) and (c) are combined, the polymeric binder dissolved or dispersed in the solvent is sprayed by turbulent mixing in a fluid bed or fluidised bed, and the solvent is removed, thereby coating and drying the metallic pigment in the fluid bed or fluidised bed.

49. Use of a metallic pigment according to any one of claims 1 to 30 in paints, varnishes, powder-based varnishes, printing inks, plastics materials or nail varnishes.

50. Use of a metallic pigment according to any one of claims 1 to 30 in a high-durability powder-based varnish for coating facades.

51. A nail varnish, characterized in that the nail varnish comprises the metallic pigment according to any one of claims 1 to 30.