DE102012109055A1 - Coated ferromagnetic metal pigments, process for their preparation and their use - Google Patents

Abstract

The invention relates to coated metal pigments, the metal pigments comprising a metal core and a coating enveloping the metal core, the metal core consisting of at least 60% by weight of at least one ferromagnetic metal, the coating enveloping the metal core comprising at least one metal oxide coating and at least one chemical coating has non-reactive plastic layer, the content of the at least one metal oxide layer being at least 9% by weight and the content of the at least one plastic layer being at least 0.4% by weight, in each case based on the weight of the uncoated metal pigment, the at least one being the metal core enveloping metal oxide layer is not an oxidation product of the metal core. The invention further relates to a method for producing the metal pigments and their use.

Description

The invention relates to coated magnetic metal pigments and to processes for their preparation. The invention further relates to coating compositions comprising coated magnetic metal pigments and coated articles.

The DE 10114446 A1 describes platelet-shaped iron pigments, which are characterized in that they are prepared from reducing treated carbonyl iron powder. The disclosed iron pigments are ferromagnetic, but uncoated and, for example, susceptible to corrosion. When drying a metal paste containing these iron pigments, there is a great risk that the dry iron pigments lead to spontaneous combustion.

The DE 10114445 A1 discloses platelet-shaped, metal oxide-coated soft iron pigments, which have a certain, but in some applications insufficient corrosion protection. In addition, these pigments showed a very poor application behavior in the powder coating.

In the WO 2007/017195 A2 For example, metallic effect pigments are treated with a coating. The coating is characterized in that it comprises an inorganic / organic mixed layer. The mixed layer contains an inorganic network and at least one organic component, wherein the organic component is an organic oligomer and / or polymer which is at least partially covalently bonded to the inorganic network via one or more organic network formers. However, the production of inorganic / organic mixed layers is technically complex.

From the WO 2005/063897 A2 are also generally known metallic effect pigments with coating. These metallic effect pigments are coated with chemically crosslinkable and / or oligomeric and / or polymeric binders crosslinkable by the action of heat, IR radiation, UV radiation and / or electron beams. This chemically reactive binder coating allows for implementation of the metal pigment with the binder of a paint or a printing ink. Under the binder coating, a pre-coating with SiO _{2 can be} arranged.

The EP 1 541 642 A1 discloses magnetic pigments which are incorporated without coating in a paint. This is followed by curing at 82 ° C. Due to the lack of a protective layer, these pigments are oxidation-unstable and discolor at higher curing temperatures, as are customary, for example, in the powder coating (200 ° C.) and in the coil coating paint (280 ° C.). This discoloration results in non-reproducible hues. Furthermore, it was found that such unprotected pigments are not adequately protected from acid and base attacks despite the surrounding paint.

The DE 198 20 112 A1 discloses effect pigments coated with reactive alignment aids. The subject matter of this application is essentially aluminum effect pigments which may be coated with a coating of metal oxides or polymers. On this coating then orientation aids are arranged, which allow a covalent attachment to the binder of a paint or a paint.

From the DE 40 30 727 A1 are resin-coated metallic effect pigments, in particular aluminum effect pigments known.

From the US 2009/0117281 A1 For example, a double coating of metallic effect pigments of SiO ₂ and a synthetic resin is known. This coating enables the use of the metal pigments in aqueous formulations and brings about improved chemical stability and water resistance of the films applied therewith. US 2009/0117281 A1 relates to the use of aluminum effect pigments and aluminum alloy effect pigments.

Metal effect pigments with improved resistance to chemicals are also used in the WO 2008/095697 A1 described. According to the teaching of WO 2008/095697 A1 The metallic effect pigments are provided with a homogeneous synthetic resin coating.

With the exception of WO 2009/149834 A2 and the WO 2008/095697 A1 In general, the above-mentioned prior art relates to the coating of aluminum effect pigments to provide corrosion-resistant aluminum effect pigments.

The object of the present invention is to provide pigments which can be applied in particular in a powder coating and are suitable for providing a particular optical effect as a result of their orientability. Preferably, such pigments are characterized by good coverage in a powder coating. Furthermore, the pigments should be too glossy and color-stable and have a clear optical effect, for example in the form of a clearly recognizable image after a magnetic alignment.

The object underlying the invention is achieved by providing coated metal pigments according to claim 1 or aspect 1,
wherein the metal pigments comprise a metal core and a coating enveloping the metal core,
wherein the metal core consists of at least 60% by weight of at least one ferromagnetic metal,
wherein the coating enveloping the metal core has at least one enveloping metal oxide layer and at least one enveloping chemically non-reactive plastic layer,
wherein the content of the at least one metal oxide layer is at least 9 wt .-% and the content of the at least one plastic layer is at least 0.4 wt .-%, each based on the weight of the uncoated metal pigment, and
wherein the at least one metal oxide layer enveloping the metal core is not an oxidation product of the metal core.

Preferred developments of the metal pigments according to the invention, preferably metallic effect pigments, are specified in subclaims 2 to 10 or aspects 2 to 18.

Furthermore, the object underlying the invention is achieved by providing a coating agent or cosmetic which contains the metal pigments according to the invention, preferably metallic effect pigments. Preferred developments of the coating compositions according to the invention are given in the subclaim 12 or aspect 20.

In addition, the object underlying the invention is achieved by a coated article which contains or has the metal pigments according to the invention, preferably metallic effect pigments, or which has the coating composition according to the invention.

The object on which the invention is based is also achieved by the use of the metal pigments according to the invention, preferably metallic effect pigments, in a coating agent or cosmetic. Preferred developments of the uses according to the invention are given in the claim 14 or the aspects 24 to 25.

• (1a) Beschichten von ferromagnetischen Metallpigmenten mit mindestens einer umhüllenden Metalloxidschicht,
• (1b) Beschichten der in Schritt (1a) erhaltenen metalloxidbeschichteten ferromagnetischen Metallpigmente mit dem (den) Edukt(en) mindestens einer umhüllenden chemisch nichtreaktiven Kunststoffschicht,
• (1c) Aushärten oder Auspolymerisieren der in Schritt (1b) mit dem (den) Edukt(en) einer umhüllenden chemisch nichtreaktiven Kunststoffschicht beschichteten ferromagnetischen Metallpigmente, oder
• (2a) Beschichten der ferromagnetischen Metallpigmente mit dem (den) Edukt(en) mindestens einer umhüllenden chemisch nichtreaktiven Kunststoffschicht,
• (2b) Aushärten oder Auspolymerisieren der in Schritt (2a) mit dem (den) Edukt(en) einer chemisch nichtreaktiven Kunststoffschicht beschichteten ferromagnetischen Metallpigmente,
• (2c) Beschichten der in Schritt (2b) erhaltenen chemisch nichtreaktiven Kunststoffschicht beschichteten Metallpigmente mit mindestens einer umhüllenden Metalloxidschicht.

The object on which the invention is based is furthermore achieved by providing a process for producing one of the metal pigments according to the invention, which comprises the following steps:

• (1a) coating ferromagnetic metal pigments with at least one enveloping metal oxide layer,
• (1b) coating the metal oxide-coated ferromagnetic metal pigments obtained in step (1a) with the educt (s) of at least one enveloping chemically non-reactive plastic layer,
• (1c) curing or polymerizing the ferromagnetic metal pigments coated in step (1b) with the educt (s) of an enveloping chemically non-reactive plastic layer, or
• (2a) coating the ferromagnetic metal pigments with the educt (s) of at least one enveloping chemically non-reactive plastic layer,
• (2b) curing or polymerizing the ferromagnetic metal pigments coated in step (2a) with the educt (s) of a chemically non-reactive plastic layer,
• (2c) coating of the chemically non-reactive plastic layer obtained in step (2b) coated metal pigments having at least one enveloping metal oxide layer.

In particular, it is preferred that the aforementioned metal pigments are metallic effect pigments, i. platelet-shaped metal pigments, acts. Further preferred developments of the uses according to the invention are given in the aspects 27 to 29.

Ferromagnetic metal pigments are sometimes used in coating compositions, such as printing inks, to cause metallic effects, wherein the orientation of the ferromagnetic metal pigments in an application medium, for example a printing ink, can be selectively influenced by applying a magnetic field. For example, the Ferricon pigments of Eckart GmbH are offered for flexographic, gravure and screen printing. However, the problem is, for example, that at high temperatures, as in coating processes such as powder coating or coil coating coating occur, oxidation of the iron pigments may occur, which may result, inter alia, in color changes of the pigments. Furthermore, for example, iron pigments can release iron ions, which can interact with constituents of a coating agent and, for example, as a catalyst can lead to undesired polymerizations or gellings in paint systems. Furthermore, the uncoated iron pigments surprisingly show poor coverage.

A special feature of the magnetic metal pigments is their alignability in a magnetic field, whereby these pigments can be used to achieve special, especially optical, effects. Since this peculiarity accounts for much of the interest in these pigments, changes in the pigments that affect this property are less desirable. For example, the application of large masses of coatings increases the total mass of the particles, making it difficult or impossible to align these pigments in a magnetic field. The power available to orient the pigments is substantially determined by the amount of magnetic material in the individual pigment and by the strength of the magnetic field. An increase in the strength of the magnetic field is not possible for technical or economic reasons in the rule.

Surprisingly, it has been shown that by a specific combination of coatings and in particular by selecting the proportions of these coatings optimized stability, for example against oxidation, is achieved, while at the same time the individual pigments are still magnetic enough to achieve good alignment in a magnetic field ,

Moreover, it has surprisingly been found that metal pigments with an inventive at least two-layer coating structure having at least one enveloping metal oxide layer and at least one enveloping chemically non-reactive plastic layer are distinguished by a particular stability even against mechanical influences, for example abrasive influences.

Without intending to be construed as limiting the present invention, it is believed that the mechanical stability of, for example, metal pigments of the invention having an external chemically non-reactive plastic layer is due to the fact that the aforementioned chemically unreactive plastic layer has a certain elasticity, i. not brittle. Thus, mechanical forces acting on the metal pigments according to the invention can be cushioned by the outer enveloping chemically non-reactive plastic layer.

The term "metal pigment" for the purposes of the present invention includes spherical and platelet-shaped metal particles, unless otherwise specified. The term "metallic effect pigment" in the sense of the present invention denotes platelet-shaped metal particles.

The platelet-shaped metal pigments of the invention, which are also referred to as metallic effect pigments, have proved to be particularly advantageous. In this case, their platelet shape allows a directed reflection of electromagnetic radiation such as visible light comparable to a mirror. By a deliberately different orientation of corresponding pigments by a magnetic field, it is possible to achieve a clear optical effect. By applying a magnetic field, the metallic effect pigments of the invention are aligned and thus a pattern is produced in the coating. An example of corresponding coated powder coating coated metal sheets can be found in ,

In further embodiments, the metallic effect pigments according to the invention, in particular iron effect pigments, have an aspect ratio in a range from 2000: 1 to 5: 1, more preferably from 1150: 1 to 15: 1, even more preferably up to 850: 1 to 20: 1. The term "aspect ratio" or "size-thickness ratio" in the sense of the invention describes the ratio of size and thickness of these pigments and is calculated according to the aspect ratio = D ₅₀ : h ₅₀ . D ₅₀ is the average diameter and h _{50 is} the average thickness of the metallic effect pigments. In particular, it is preferred in further embodiments that the aspect ratio of the metallic effect pigments according to the invention in a range of 700: 1 to 90: 1, preferably in a range of 670: 1 to 120: 1, and more preferably in a range of 650: 1 to 150 : 1 is.

The metal pigments according to the invention comprise a metal core and a coating enveloping the metal core. The metal core here consists of at least 60 wt .-% of at least one at room temperature (25 ° C) ferromagnetic metal, based on the weight of the uncoated metal pigment. In addition to the ferromagnetic metals, which already exhibit ferromagnetic properties in their pure form, such as iron, cobalt and nickel, it is also possible to use alloys such as AlNiCo, SmCo, Nd ₂ Fe ₁₄ B, Ni ₈₀ Fe ₂₀ and NiFeCo alloys. However, particularly preferred is the use of iron, cobalt and nickel, in particular iron.

In preferred embodiments, the metal core is at least 50 wt%, more preferably at least 60 wt%, of iron, based on the weight of the metal core. In this case, the iron can be present in elemental form or else, for example, as an oxide in the form of a superficial oxide layer. The term "elemental metal" in the sense of the present invention means that the metal in question is in the oxidation state 0, i. that it is neither oxidized nor reduced. Here, the elemental metal may also be present as an alloying constituent. The term "metal core" in the sense of the present invention means the uncoated metal pigment.

Furthermore, it may be preferred that the metal core to at least 90 wt .-%, preferably at least 97 wt .-%, more preferably at least 99 wt .-% and even more preferably at least 99.9 wt .-% of ferromagnetic Metal, in particular iron, consists, in each case based on the weight of the metal core without oxygen. In this case, the iron can be present in elemental form or else, for example, as an oxide in the form of a superficial oxide layer. Due to the high proportion of ferromagnetic metal, it is possible to achieve significant effects even with very weak magnets or extremely high-contrast effects with strong magnets. In particular, it is preferred that the metal core consists entirely of iron, with only trace amounts of other constituents. The term "trace amount" in the sense of the present invention denotes amounts of a total of at most 0.01% by weight.

In further embodiments of the invention, it is preferred to use specific alloys, in particular steel alloys, wherein specific properties are achieved by the selective addition of constituents. For example, by using chromium, the corrosion resistance of iron-containing pigments can be increased. This allows, for example, the reduction or even prevention of oxidation of the pigment before the application of the coating according to the invention. Due to the lower proportion of ferromagnetic metal, however, the contrast strength drops when applied magnetic field with identical magnetic field strength, so that such pigments are particularly suitable, for example, for less contrasting motifs where greater importance is placed on, for example, a particularly strong gloss of the individual pigments. Particularly preferred examples of corresponding alloying pigments are steel pigments.

In other preferred embodiments of the present invention ferrous metal cores are used. Pigments containing iron in the context of the present invention refer to pigments which comprise at least 60% by weight of iron, based on the weight of the metal core without oxygen. It is particularly preferred to use either iron pigments or ferromagnetic steel pigments. The term "iron pigment" in the sense of the present invention means that the metal core consists of at least 90% by weight of iron. In particular, it is preferred that the iron pigments consist of at least 97% by weight, more preferably at least 99% by weight, even more preferably at least 99.5% by weight of iron. The term "steel pigment" in the sense of the present invention means that the metal core consists of at least 70 wt .-% of iron, at least 80 wt .-% of iron, cobalt and nickel and at least 2, preferably at least 3 metals as alloying constituents in addition to iron in a proportion of more than 1 wt .-% comprises. The abovementioned percentages by weight in each case relate to the weight of the metal core without oxygen, which may be present, for example, in the form of a superficial oxidation layer. Examples of metals that can be used as alloying constituents are tungsten, molybdenum, vanadium, cobalt, nickel, niobium, chromium, silicon and manganese.

The term "ferromagnetic" in the sense of the present invention corresponds to the term familiar to the person skilled in the art. Examples of ferromagnetic metals are iron, cobalt and nickel. In such metals form Weissche districts, which exert influence on the magnetic properties of the corresponding substances. They are further characterized by the Curie temperature, which describes the temperature over which the ferromagnetic properties are lost. In particular, it is preferred that the ferromagnetic metals of the invention have a Curie temperature of at least 100 ° C, preferably at least 150 ° C, even more preferably at least 250 ° C, and most preferably at least 400 ° C.

Another feature of ferromagnetic metals is a high relative permeability (μ _r >> 1). The relative permeability is of course dependent on the magnetic field strength used for the measurement, which is why ranges of this value are given. Theoretically, a saturation magnetization is achieved by continuously increasing the applied magnetic field, resulting in an approximation of the relative permeability 1 results. Preferably, the upper limit of the relative permeability μ _r of the relevant metal in> 75, more preferably> 150, even more preferably> 250, and even more preferably> 350, in each case measured at 20 ° C. The measurement of the permeability can take place, for example, by means of the Gouy balance or by means of SQUIDs.

In particular, it is preferred that the metal cores used according to the invention are not nanoparticles. For the purposes of the present invention, the term "nanoparticles" is understood to mean particles in the nanometer range, in particular with an average particle size of less than 200 nm.

In further embodiments, the platelet-shaped metal cores have an aspect ratio in the range of 2000: 1 to 5: 1, more preferably 1150: 1 to 15: 1, even more preferably 850: 1 to 20: 1. The term "aspect ratio" or "size-thickness ratio" in the sense of the invention describes the ratio of size and thickness of corresponding pigments and is calculated in accordance with the aspect ratio = D ₅₀ : h ₅₀ . In particular, in further embodiments, it is preferred that the aspect ratio of the platelet-shaped metal cores be in a range of 700: 1 to 90: 1, preferably in a range of 670: 1 to 120: 1, and more preferably in a range of 650: 1 to 150 : 1 is.

In applications in which high metallic gloss values without serious color changes by oxidation of the metal core are desired, it is preferred that the metal cores according to the invention are for the most part in elemental metal form. In further embodiments, it is therefore preferable that the oxygen content of the metal core is at most 15% by weight, preferably at most 12% by weight, more preferably at most 8% by weight, still more preferably at most 5% by weight, and most preferably at most 3 wt .-%, each based on the weight of the metal core.

However, if a coloring of the iron pigments to achieve specific shades without the use of color pigments or in combination with color pigments specific shades is desired to achieve, by means of a targeted oxidation, a coloring oxide layer can be produced on the surface of the metal cores.

The iron pigments of the invention are characterized by a very high proportion of iron. For example, it is preferred to use very pure iron, which is prepared by the decomposition of vaporous iron pentacarbonyl Fe (CO) ₅ in cavity decomposers. This has an iron content of about 97 wt .-% and still contains about 1.5 wt .-% carbon and about 1 wt .-% oxygen. By further reduction of this corresponding iron powder, the impurities can be further removed, so that an iron content of at least 99.5 wt .-% is achieved. The use of such pigments is particularly preferred since this high-purity iron has a high ductility and can therefore be ground or deformed particularly easily to form particularly high-quality iron effect pigments.

The steel pigments according to the invention are furthermore preferably characterized in that they contain at most 1.8% by weight, more preferably at most 1.5% by weight, of carbon, based on the weight of the metal core without oxygen.

Although the steel pigments according to the invention typically exhibit inferior magnetization than the iron pigments according to the invention, the addition of further alloying constituents makes it possible to tailor desired material properties in order to meet desired requirements.

In particular, it is preferable to use stainless steel alloys in order to achieve increased stability of the metal core. This allows, for example, the simplification of the process, since pure iron is pyrophoric in finely divided form and prone to spontaneous combustion. For these reasons, saturation of the surface, for example in the form of a defined superficial oxidation, is required and / or increased safety requirements must be fulfilled until application of the coating according to the invention. The use of stainless-steel pigments therefore makes it possible, for example, to provide iron-containing pigments with reduced or even superficial oxidation layer considerably simplified in terms of process technology. In particular, it is preferred that the steel pigments of the invention comprise at least 7% by weight, preferably at least 10% by weight, more preferably at least 12% by weight of chromium, in each case based on the weight of the metal core without oxygen.

The metal cores used according to the invention can be present in various forms. For example, spherical or approximately spherical pigments can be used if, in particular, haptic effects are to be achieved and visual effects are negligible or even unwanted. In particular, however, platelet-shaped metal cores are preferred, which offer particularly interesting optical properties due to a directed reflection of the light. The reflection of incident light can be clearly changed by aligning the coated metallic effect pigments of the invention in a magnetic field.

Since the coatings according to the invention are applied uniformly to the surface of the metal cores, the shape of the coated metal pigments according to the invention typically resembles strongly the shape of the metal cores used. Thus, for example, a platelet shape is retained even after application of the coating according to the invention.

The metal pigments according to the invention are characterized by at least one metal oxide layer and at least one chemically non-reactive plastic layer, which surround the metal core. Preferably, both the metal oxide layer and the chemically non-reactive plastic layer are distinct layers, and therefore not mixed layers.

Surprisingly, it has been shown that, for example, the applicability of metal pigments in a powder coating is significantly improved by means of the coating to be applied according to the invention. Furthermore, it has surprisingly been found that by optimizing the weight ratios of metal oxide coating to the chemically non-reactive plastic layer, the coating can be made thinner overall, while a high stability of the corresponding pigments, for example to oxidizing conditions and good application properties, for example as part of a powder coating is given.

In further particularly preferred embodiments, at least one of the enveloping metal oxide layers according to the invention is arranged between the metal core and at least one of the chemically non-reactive plastic layer enveloping according to the invention. Such a layer structure has proved to be particularly effective, for example, with increased resistance to chemicals. Also, a layer structure with an enveloping metal oxide layer, wherein this metal oxide layer is not an oxidation product of the metal core, and a subsequently arranged chemically non-reactive plastic layer prevents the escape of metal ions, for example iron ions from a ferrous metal core, into the surrounding medium, for example a powder coating.

In further embodiments of the invention, at least one chemically non-reactive plastic layer to be applied according to the invention is arranged between the metal core and at least one enveloping metal oxide layer to be applied according to the invention. Metal pigments with such a layer structure are characterized, for example, by a particular hardness.

Pigments with an external hard metal oxide layer may be advantageous if, after application, for example in the form of a powder coating, the metal pigments are arranged on the surface of a coating, for example a lacquer, and exposed to mechanical, for example abrasive, actions. It has surprisingly been found that the pigments of the invention show less, preferably no, abrasion and are therefore resistant to wear.

Of course, color pigments may also be present in a coating composition according to the invention in addition to the metal pigments according to the invention. The color pigments serve for a desired coloring of the coating composition according to the invention.

According to the invention, the coated metal pigments can also be dyed directly in order to achieve desired color effects, for example when used in a coating composition according to the invention. In addition to the abovementioned method of targeted oxidation of the surface of iron pigments, it is also possible, for example, to introduce color pigments into at least one of the layers to be applied according to the invention. Alternatively, for example, a coloring layer may be arranged under the coatings to be applied according to the invention.

On the one hand, this makes it possible to provide a broader spectrum of metal pigments according to the invention and thus a broad color spectrum. On the other hand, however, the formulation of corresponding coating compositions is significantly simplified and there are many other advantages. For example, very fine colorant particles can be used, which otherwise can be formulated worse, for example due to, for example, strong dust formation or tendency to agglomerate due to hygroscopy. Also, no separation of corresponding coating components is feared which would cause an inhomogeneous coating image. Furthermore, corresponding color pigments are shielded by the encapsulating coating, as a result of which they are protected, for example, and / or interactions with constituents of the coating composition are minimized or prevented.

The term "chemically non-reactive plastic layer" is understood according to the invention that the plastic layer is substantially completely, preferably completely, cured. Thus, this cured plastic layer does not react significantly with the binder of a coating agent, such as a paint, such as a powder paint, or a paint. According to a preferred variant, no reaction takes place between the cured plastic layer and the binder of a coating agent.

By no means is it with the "chemically non-reactive plastic layer" is a coating of not yet cured binder, as in the WO 2005/063897 A2 are disclosed. A binder is characterized in that it hardens only later in the application, for example as a resin / hardener system or by radical polymerization. In this case, however, the metal pigments are irreversibly incorporated into the cured powder coating.

The proportion by weight of the plastic layers, based on the weight of the uncoated metal pigment, depends essentially on the specific surface of the uncoated metal pigment. In further preferred embodiments, the weight fraction of the at least one plastic layer is at least 0.9 wt .-%, preferably at least 1.2 wt .-%, more preferably at least 1.5 wt .-% and even more preferably at least 1 , 7 wt .-%, each based on the weight of the metal core.

In particular, it is preferred in further embodiments that the proportion by weight of the at least one plastic layer is in a range of 0.4 to 23 wt .-%, preferably in the range of 0.9 to 21 wt .-%, more preferably in the range of 1, 2 to 18 wt .-%, more preferably in the range of 1.5 to 16 wt .-% and even more preferably in the range of 1.7 to 15 wt .-%, each based on the weight of the metal core is.

According to further preferred embodiments, the at least one chemically non-reactive plastic layer consists essentially of a plastic which consists of the group consisting of polyacrylate, polymethacrylate, polyacrylamide, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, polyamide, polyalkene, polydiene, polyalkyne, polyalkylene glycol, epoxy resin, polyester, polyether , Polyol, polyurethane, polycarbonate, polyethylene terephthalate and mixtures thereof.

According to a preferred embodiment, the at least one plastic layer consists essentially of a plastic selected from the group consisting of polyacrylate, polymethacrylate, polyurethane, polyester and mixtures thereof. Metallic pigments having at least one such plastic layer are distinguished, for example, by increased UV resistance. Increased UV stability is desirable when the metal pigments of the present invention are used in outdoor applications, such as automotive finishes, architectural finishes, etc.

Polyacrylates, polymethacrylates or mixtures thereof, for example, have proved to be particularly suitable plastics for producing plastic layers with increased UV resistance. In further embodiments of the invention, therefore, the at least one plastic layer consists essentially of polyacrylates and / or polymethacrylates.

As monomers for the production of polyacrylates and polymethacrylates are, for example, isoamyl acrylate, lauryl acrylate, stearyl acrylate, butoxyethyl acrylate, ethoxy-diethylene glycol acrylate, methoxy-triethylene glycol acrylate, methoxy polyethylene glycol acrylate, methoxy dipropylene glycol acrylate, phenoxyethyl acrylate, phenoxy polyethylene glycol acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylates, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate , 2-hydroxy-3-phenoxypropyl acrylate, 2-Acryloyloxyethylsuccinsäure, 2-acryloyloxyethylphthalic acid, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, triethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, Dimethyloltricyclodecanediacrylat, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate , 2-hydroxy-3-acryloyloxypropyl methacrylate, isooctyl acrylate, isomyristyl acrylate, isostearyl acrylate, 2-ethylhexyl diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloylox yethylhexahydrophthalic acid, hydroxypivalic acid neopentyl glycol diacrylate, polytetraethylene glycol diacrylate, ditrimethylolpropane tetraacrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, n-lauryl methacrylate, tridecyl methacrylate, n-stearyl methacrylate, methoxydiethylene glycol methacrylate, Methoxypolyethylene glycol methacrylate, cyclohexyl methacrylate, Tetrahydrofurfuralmethacrylat, benzyl methacrylate, phenoxyethyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl, 2-hydroxybutyl methacrylate, 2-Methacryloyloxyethylsuccinsäure, 2-Methacroyloxyethylhexahydrophthalsäure, 2-hydroxypropyl phthalate Methacryloyloxyethyl2-, Ethyleneglycoldimethacrylat, Diethyleneglycoldimethacrylat, 1,4-butanediol dimethacrylate, 1, 3-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, trimethylolpropane trimethacrylate, glycerol dimethacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, t-butyl methacrylate, isostearyl methacrylate, methoxytriethylene glycol methacrylate, n-butoxyethyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, triethylene glycol dimethacrylate, Neopentyl glycol dimethacrylate or mixtures thereof.

With particular preference, at least one monomer having at least two, more preferably three, reactive double bonds (crosslinkers) is used. The monomer therefore particularly preferably contains or consists of 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, dimethyloltricyclodecanediacrylate, neopentylglycoldimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate or mixtures thereof.

Furthermore, the acrylate / methacrylate-containing plastic layer may additionally comprise acrylic acid and / or methacrylic acid and further free-radically polymerizable unsaturated compounds.

According to a further variant of the invention, the plastic layer is selected from the group consisting of polyamide, polycarbonate, polyvinyl chloride, polyethylene terephthalate and mixtures thereof. Metal pigments with at least one such plastic layer are distinguished, for example, by increased temperature stability.

According to a preferred embodiment of the invention, the plastic is temperature-stable up to a temperature of at least 180 ° C, more preferably of at least 260 ° C, even more preferably up to a temperature of at least 350 ° C. Temperature-stable means that the plastic coating of the platelet-shaped metal pigments does not melt and / or decompose at the aforementioned temperature. The test for a possible melting and / or decomposition at a predetermined temperature can be carried out for example by means of differential scanning calorimetry.

According to a further preferred embodiment, physically bound surface modifiers are applied to the enveloping chemically non-reactive plastic layer.

According to a preferred variant of the invention, the metal oxide layers according to the invention are selected from the group consisting of silicon oxide, aluminum oxide, boron oxide, zirconium oxide, cerium oxide, iron oxide, titanium oxide, chromium oxide, tin oxide, molybdenum oxide, their hydrated oxides, their hydroxides and mixtures thereof. In further preferred embodiments, the at least one metal oxide layer is characterized in that the at least one metal oxide layer consists essentially of silicon oxide.

In the context of this invention, the term "consisting essentially of silicon oxide" means that the layer consists predominantly of silicon oxide, preferably of SiO ₂ , but may also contain up to 20% by weight of water, based on the silicon oxide layer. Further, in a sol-gel synthesis from tetraalkoxysilanes, the silica may contain up to 5% by weight of alkoxy groups which have not been hydrolyzed and condensed.

Preferably, at least one, preferably all, of the at least one enveloping metal oxide layer consists of a silicon oxide layer or silicon oxide layers, preferably an SiO ₂ layer or SiO ₂ layers, and / or aluminum oxide layers or aluminum oxide layers, preferably an Al ₂ O ₃ Layer or Al ₂ O ₃ layers. In further preferred embodiments, at least one, preferably all, of the at least one enveloping metal oxide layer consists of a silicon oxide layer (s), preferably an SiO ₂ layer. In further preferred embodiments, at least one, preferably all, of the at least one enveloping metal oxide layer consists of an aluminum oxide layer or aluminum oxide layers, preferably an Al ₂ O ₃ layer or Al ₂ O ₃ layers. In further particularly preferred embodiments, the at least one enveloping metal oxide layer is a (number: 1) silicon oxide layer, preferably a (number: 1) SiO ₂ layer.

According to a further preferred embodiment of the invention, the proportion by weight of the metal oxide layer is at least 10.2 wt .-%, more preferably at least 10.7 wt .-% and particularly preferably at least 11.3 wt .-%, each based on the Weight of the metal core.

In particular, it is preferred in further embodiments that the weight fraction of the metal oxide layer in a range of 9 to 45 wt .-%, more preferably in a range of 10.2 to 38 wt .-% and particularly preferably in a range of 10.7 to 33 wt .-% and most preferably in a range of 11.3 to 27 wt .-%, each based on the weight of the uncoated metal pigment.

Surprisingly, in the case of the metal pigments according to the invention, preferably metallic effect pigments, a (number: 1) metal oxide layer in combination with a (number: 1) chemically non-reactive plastic layer is enough to protect the metal pigments, preferably metallic effect pigments, from environmental influences on the one hand and prevent them on the other hand in that metal ions, for example iron ions, are released into the environment, for example a lacquer, a paint, a cosmetic, etc.

Without it being to be understood as limiting the invention, it is the view of the inventors that the surprisingly good protective effects of the coating according to the invention are based inter alia on an effective shielding of the metal core from the surrounding medium. It is assumed that corrosive substances, such as H ⁺ or OH ^- ions, are particularly effectively stopped by the combination of the protective effects of at least one metal oxide layer and at least one chemically non-reactive plastic layer. In particular, it is assumed that in this case a strong shielding of large amounts of corrosive substances is achieved by the metal oxide layer (s) to be used according to the invention. On the other hand, the chemically non-reactive plastic layers seem to allow a particularly efficient inclusion of small amounts of corrosive substances or metal ions. In further embodiments, it is therefore preferred that at least one non-chemically reactive plastic layer be present under a metal oxide layer to effectively trap small amounts of corrosive substances passing through the metal oxide layer.

In further very preferred embodiments, there is a metal oxide layer according to the invention, which is not an oxidation product of the metal core, under the chemically non-reactive plastic layer. This seems to be particularly advantageous when, for example, conditions are used in which in particular the escape of metal ions should be prevented. Thus, metal ions released correspondingly from the metal core appear to be captured particularly effectively by the combination of a metal oxide layer as first barrier layer and a chemically non-reactive plastic layer as second barrier layer. Hereby, for example, ions formed as a result of coating preceding the reaction can be effectively included.

In further preferred embodiments, the weight ratio of the at least one metal oxide layer according to the invention to at least one chemically non-reactive plastic layer is preferably at least 1 to 1, more preferably at least 7 to 6, even more preferably at least 6 to 5 and most preferably at least 5 to 4.

In particular, it is preferred in further embodiments that the weight ratio of the at least one metal oxide layer to the at least one chemically non-reactive plastic layer in a range from 1: 1 to 36: 1, preferably in a range from 7: 6 to 30: 1, more preferably in a Range of 6: 5 to 27: 1, more preferably in the range of 5: 4 to 24: 1.

The metal pigments according to the invention are characterized by excellent stability, as required, for example, in the presence of atmospheric oxygen at high temperatures. This proves to be particularly advantageous in application methods such as the powder coating or the coil coating coating in which temperatures of about 200 ° C or about 280 ° C act on the coating during the curing process. Already small amounts of oxidation lead to an undesired discoloration of the coating, which is why ensuring the oxidation stability is important especially for large-scale production. It has surprisingly been found that even a thin metal oxide layer in combination with the chemically non-reactive plastic layer is sufficient to prevent oxidation of the metal pigment. The plastic layer is permeable to oxygen, but gives the product the required chemical stability.

In further embodiments, it is particularly preferred that the sum of the contents of the polymer layer and the metal oxide layer is in a range of 9.4 to 68 wt%, preferably in a range of 11 to 54 wt%, more preferably in a range from 11.7 to 49 wt .-%, even more preferably in a range of 12.3 to 43 wt .-%, each based on the weight of the metal core.

It is inventively preferred to keep the sum of the content of the polymer layer and the metal oxide layer as low as possible. In this way, optimum coverage of the metallic effect pigments is ensured. In addition, it has been found that if the layers are too thick, the metallic effect pigments can tend to agglomerate.

In particular, in further embodiments of the invention ranges are preferred which by a plastic amount of 0.4 wt .-% to 23 wt .-% and a metal oxide of 9 wt .-% to 45 wt .-%, preferably a plastic amount of 0, 9 wt .-% to 21 wt .-% and a metal oxide 10.2 wt .-% to 38 wt .-%, more preferably a plastic amount of 1.2 wt .-% to 18 wt .-% and a metal oxide amount of 10.7% by weight to 33% by weight, even more preferably a plastic amount of 1.7% by weight to 15% by weight and a metal oxide amount of from 11.3% by weight to 27% by weight, are in each case based on the weight of the metal core.

In specific preferred embodiments, the at least one chemically unreactive plastic layer consists essentially of polyacrylate and / or polymethacrylate and the at least one metal oxide layer consists essentially of silicon oxide, preferably SiO ₂ , wherein the weight ratio of the at least one metal oxide layer to at least one chemically non-reactive plastic layer is in a range of 1: 1 to 36: 1 and the sum of the content of the at least one chemically non-reactive plastic layer and the at least one metal oxide layer in a range of 11 to 54 wt .-%, based on the weight of the metal core is.

In further specific preferred embodiments, the at least one chemically non-reactive plastic layer consists essentially of polyacrylate and / or polymethacrylate and the at least one metal oxide layer consists essentially of silicon oxide, preferably SiO ₂ , wherein the weight ratio of the at least one metal oxide layer to at least one chemically non-reactive plastic layer in a range is from 7: 6 to 30: 1 and the sum of the contents of the chemically non-reactive plastic layer and the metal oxide layer is in a range of 11.7 to 49 wt .-%, based on the weight of the metal core. In further of the foregoing specific preferred embodiments, the weight ratio of the at least one metal oxide layer to the at least one plastic layer is in the range of 5: 4 to 24: 1.

Optionally, one or more organofunctional silanes can be applied between the SiO ₂ layer and the plastic layer, which contain at least one free-radically polymerizable double bond, preferably at least one acrylate and / or methacrylate group.

Due to the relatively small thicknesses of the metal oxide layer and the relatively large plastic layer thickness, the metal pigments according to the invention have two significant advantages.

On the one hand, the covering capacity, i. the area covered per unit weight of pigment according to the invention, still very good, compared with the coverage of an uncoated metal pigment. The thicker the applied transparent cladding, the poorer the coverage, since less and less metal particles are present per gram of pigment. The coverage may be further worsened if, with increasing coating thickness, more fines of the metal pigments are incorporated into the coating of larger pigments. However, this fine fraction is largely responsible for good cover assets.

In that regard, it is advantageous if the coating has the lowest possible layer thickness, since then less fines content is incorporated into the coating of larger pigments and this can thus contribute to the coverage by a statistical distribution in the paint as before. To be able to keep the average layer thickness of the coating low, it is a prerequisite that the applied enveloping transparent coating effectively protects the metal pigment against corrosive environmental influences and also prevents metal ions, in particular heavy metal ions, from being released into the environment.

A combination of a thin metal oxide layer with a chemically non-reactive plastic layer allows surprisingly, the ferromagnetic metal pigments by means of processes such as powder coating are well applied and can be achieved using magnets specific patterns. In particular, the coatings according to the invention also appear to permit subsequent orientation during the curing process, which produces particularly pronounced effects. By choosing the strength of the magnet this special effect, such as a particularly strong three-dimensionality or a particularly strong contrast can be achieved. Furthermore, the invention provide Coatings excellent protection against corrosive environmental influences and prevent the escape of metal ions, in particular heavy metal ions, which otherwise can lead to, for example, disruption of the paint system during curing. With regard to the transparent coating with a small layer thickness, the metal pigments according to the invention still have an outstanding covering power.

Between the at least one enveloping metal oxide layer and the at least one enveloping chemically non-reactive plastic layer, one or more further layers may be arranged. This one or more additional layers may, for example, likewise be additional metal oxide layers. In further embodiments, however, it is preferred that any layers between the at least one enveloping metal oxide layer and the at least one enveloping chemically non-reactive plastic layer do not constitute a metal oxide layer or plastic layer in the sense of the present invention.

In a preferred embodiment, the aforementioned further layers comprise, as adhesion promoters and / or further layer components, organofunctional silanes, titanates, aluminates, phosphonic acids (for example VPS: vinylphosphonic acid), phosphoric acid esters and / or zirconates, with organofunctional silanes being particularly preferred. Because of their known hydrolysis and condensation reactions, for example, these compounds can bind particularly well to the metal surface or metal oxide surface. The compounds should have at least one chemically polymerizable group, which is preferably adapted to the plastic layer.

If the plastic layer consists, for example, of polyacrylates and / or polymethacrylates, the organofunctional silane preferably has at least one functional group which can be chemically reacted with an acrylate group and / or methacrylate group of the polyacrylate and / or polymethacrylate. Free-radically polymerizable organic functional groups have proven to be very suitable. Preferably, the at least one functional group is selected from the group consisting of acrylic, methacrylic, vinyl, allyl, ethynyl and other organic groups having unsaturated functions.

Preferably, the organofunctional silane has at least one acrylate and / or methacrylate group, since these can be reacted with the acrylate or methacrylate compounds used to produce the polyacrylate and / or polymethacrylate completely without problems to form a homogeneous plastic layer.

As organofunctional an acrylate and / or methacrylate-functional silanes, for example, (methacryloxymethyl) can methyldimethoxysilane according to the invention, methacryloxymethyltrimethoxysilane, (methacryloxymethyl) methyldiethoxysilane, methacryloxymethyltriethoxysilane, 2-Acryloxyethylmethyldimethoxysilan, 2-methacryloxyethyltrimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, 2-acryloxyethyltrimethoxysilane, 2-methacryloxyethyltriethoxysilane, 3-acryloxypropyltrimethoxysilane , 3-acryloxypropyltripropoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriacetoxysilane, 3-methacryloxypropymethyldimethoxysilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyldimethoxymethylsilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriacetoxysilane, or mixtures thereof.

Such silanes can act as adhesion promoters between metal oxide layer and plastic layer or between metal oxide layer, preferably silicon oxide layer and plastic layer. In other embodiments, such silanes can at least partially be polymerized into the plastic layer, as in the WO 2008/095697 A1 described, which is hereby incorporated by reference.

In the context of this invention, a chemically non-reactive plastic layer which "consists essentially of polyacrylate and / or polymethacrylate" is understood to mean that such a layer can be modified by acrylates and / or methacrylates containing silanes. A substantially consisting of "polyacrylate and / or methacrylate plastic layer" is understood that the plastic layer consists essentially of acrylate, methacrylate or mixtures of acrylate and methacrylate. The proportion of the acrylate and / or methacrylate-containing silanes used corresponds at most to the proportion of the acrylate and / or methacrylate monomers used. The molar ratio of acrylate- and / or methacrylate-containing silanes to acrylate and / or methacrylate monomers is preferably from 1: 2 to 1:40, preferably from 1: 3 to 1:30.

However, this invention does not cover layers in which the acrylate- and / or methacrylate-containing silanes are incorporated into the at least one metal oxide layer, in particular silicon oxide layer, during a sol-gel process. Such layers are in the EP 1812519 B1 described. It has been found that the technology described there, the layers can not be produced reliably reproducible to give the metal pigments the required stabilities.

One or more further layers can likewise be arranged between the metal cores and the at least one enveloping metal oxide layer and the at least one chemically non-reactive plastic layer. For example, a layer of iron oxide can be arranged between the enveloping metal oxide layer and the metal pigments. This iron oxide layer can be formed, for example, by a superficial oxidation of the pigment in contact with air

According to the invention, the at least one metal oxide layer which synergistically interacts with the at least one chemically non-reactive plastic layer is not the oxidation product of the uncoated metal pigment. Preferably, the metal oxide layer, which synergistically cooperates with the at least one chemically non-reactive plastic layer, is applied in a separate step. The separate step can be, for example, a wet-chemical coating or a gas-phase coating, for example by means of PVD or CVD.

In further very preferred embodiments of the invention, the enveloping metal oxide layer (s) and the enveloping chemically non-reactive plastic layer (s) directly follow each other. In further very preferred embodiments, it is further preferred that the enveloping metal oxide layer or the enveloping chemically non-reactive plastic layer are applied directly on the metal pigment surface or directly on the metal oxide layer such as the iron oxide layer.

In further preferred embodiments, in addition to an optional metal oxide layer, in particular iron oxide layer, the metal pigments have only one (number: 1) enveloping metal oxide layer and only one (number: 1) enveloping chemically non-reactive plastic layer.

The layer thicknesses of the metal oxide layers and the plastic layers on the metal pigments are determined, for example, by means of SEM images on suitable transverse sections. Here, the pigments are applied in a varnish and this cured. It is important to ensure the best possible orientation of the platelets in the application medium. For this purpose, the metallic effect pigments can be previously pretreated by means of suitable additives. Then the hardened lacquer is sanded and, after usual sample preparation, the cross section in the SEM is considered. For counting only particles are selected which have a good orientation. Poorly oriented platelets result in this method a high error due to the unknown viewing angle. The coatings have a very good contrast to the metal core. If it is not possible to distinguish between the layer thicknesses of the metal oxide layer and the plastic layer, locally resolved EDX analyzes can be used before the layer thicknesses are measured. The term "average layer thickness" in the sense of the invention denotes the arithmetic mean of the layer thicknesses of the layers of at least 20 metal pigments. If the coating is uneven, then the arithmetic mean of the thinnest and the thickest part of the coating of the respective particle is formed. Individual serious deviations, which are based for example on the inclusion of already coated fine pigment in the coating, are not taken into account in the calculation of the mean layer thickness.

The content of metal oxide can be carried out via an elemental analysis. Thus, for example, in the case of a SiO ₂ layer, the Si content may be determined in relation to the content of the metal used as the substrate, and based on this, the amount of SiO ₂ can be calculated.

The metallic effect pigments according to the invention preferably have an average pigment diameter (D ₅₀ ) from a range of from 1 μm to 200 μm, preferably from 3 μm to 120 μm, more preferably from 5 μm to 80 μm. Also very suitable pigment diameters from a range of 10 microns to 50 microns, preferably from 15 microns to 40 microns, have proven.

The d ₅₀ values of the length distribution of the pigments (average diameter of the pigment platelets) are preferably in a range from 5 μm to 40 μm, preferably from 6 μm to 30 μm, more preferably from 7 μm to 25 μm and particularly preferably from 7.5 μm to 20 μm.

Preference is furthermore given to fine pigments in the size range with d ₅₀ values of 8 to 18 μm, more preferably 9 to 17 μm and particularly preferably 10 to 16 μm. Such pigments preferably have non-leafing properties, ie the iron effect pigments are predominantly not oriented at or in the vicinity of the surface of an application medium, for example a paint or lacquer film. It does not therefore come to a "floating" of the iron effect pigments. They are ground, for example, with oleic acid as a lubricant and therefore coated with this substance.

On the other hand, in the spherical metallic pigments of the present invention, it is preferable that the average pigment diameter (D ₅₀ ) is in a range of 0.7 to 60 μm, preferably in a range of 0.8 to 40 μm, and still more preferably in a range of 1 to 33 μm is,

The term "D ₅₀ " in the sense of the present invention denotes the particle size at which 50% of the aforementioned volume-average particle size distribution determined by means of laser granulometry is below the stated value. The measurements can be carried out, for example, using the particle size analyzer HELOS from Sympatec GmbH, Clausthal-Zellerfeld, Germany. The dispersion of a dry powder can take place here with a dispersion unit of the Rodos T4.1 type at a primary pressure of, for example, 4 bar. Alternatively, size distribution curve of the particles can be measured, for example, with a device from the company Quantachrome (device: Cilas 1064) according to the manufacturer's instructions. For this purpose, 1.5 g of the powdery coating material are dispersed in about 100 ml of ethanol, treated for 300 seconds in an ultrasonic bath (device: Sonorex IK 52, Fa. Bandelin) and then added by means of a Pasteur pipette in the sample preparation cell of the meter and measured several times. From the individual measurement results, the resulting averages are formed. The evaluation of the scattered light signals is carried out according to the Fraunhofer method.

Furthermore, in further embodiments of the invention it is preferred that the average thickness (h ₅₀ ) of the metallic effect pigments according to the invention is in a range of 24 nm to 500 nm, preferably in a range of 27 nm to 430 nm, more preferably in a range of 31 nm to 380 nm, more preferably in a range of 33 nm to 340 nm.

The metallic effect pigments according to the invention, in particular iron effect pigments, preferably have a thickness distribution determined by scanning electron microscopy (SEM), which in the representation as a total cycle distribution has an h ₅₀ value in a range of 24 nm to 110 nm, preferably in a range of 27 nm to 90 nm, more preferably in a range of 31 nm to 85 nm, and still more preferably in a range of 33 to 77 nm.

Furthermore, the pigments of the invention preferably have a h ₉₀ value within a range of 25 nm to 130 nm, more preferably in a range of 30 nm to 110 nm and even more preferably in a range of 33 nm to 87 nm.

In further preferred embodiments, the iron effect pigments according to the invention have an h ₁₀ value of the thickness distribution in a range from 11 nm to 45 nm, more preferably in a range from 13 nm to 38 nm and particularly preferably in a range from 17 nm to 34 nm.

The term "average thickness" or "h ₅₀ " in the context of the invention refers to the arithmetic mean of the thicknesses of at least 100 metallic effect pigments, preferably 100 metallic effect pigments, by means of scanning electron microscopy (SEM). It is important to ensure the best possible orientation of the platelets in the application medium. For this purpose, the metallic effect pigments can be previously pretreated by means of suitable additives. Then the hardened lacquer is sanded and, after usual sample preparation, the cross section in the SEM is considered. For counting only particles are selected which have a good orientation.

Preferably, the metallic effect pigments are obtained by grinding a suitable semolina, for example iron semolina. In the case of iron semolina, for example, high-purity iron obtained from carbonyl iron powder is used. If necessary, the semolina is classified to obtain a desired size distribution.

The process for producing thin, platelet-shaped iron pigments preferably comprises grinding an iron _semolina having an average particle size D _{semisole, 50} in the range from 0.7 μm to 50 μm, preferably in the range from 0.9 μm to 32 μm, more preferably in the range from 1.1 μm to 21 μm, and more preferably in the range from 1.2 μm to 9 μm, and most preferably in the range from 1.3 to 7.

In particular, in further embodiments it is preferred that the milled iron _{grit has} a particle size distribution of one _{grit, 10} ≤ 4.0 μm, one _{grit, 50} ≤ 7.0 μm and one _{grit, 90} ≤ 11.0 μm. More preferably, the milled iron _semolina has a particle size distribution of one _{grit, 10} ≦ 2.7 μm, one _{grit, 50} ≦ 5.3 μm, and one _{grit, 90} ≦ 7.2 μm.

In further embodiments, it is further preferred that the iron semolina be one according to the following formula Δd _semolina = (d _{semolina, 90} - d _{semolina, 10} ) / d _{semolina, 50} calculated size distribution which is in the range of 0.7 to 0.6, more preferably 0.8 to 1.5 and particularly preferably in the range of 0.9 to 1.4.

Such a semolina is preferably used in dry grinding. The semolina can also be converted into platelet-shaped pigments by wet grinding. After milling, a classification may be required to obtain the desired uncoated flaky metal pigment fraction.

In addition to the ferromagnetic metals such as iron, the metal semolina may also contain other metals such as zinc and / or aluminum. For example, up to 10% by weight, preferably up to 5% by weight, more preferably up to 3% by weight, of further metals which are not ferromagnetic at room temperature, based on the weight of the uncoated metal pigment, may be present.

The metal grit used for grinding can be produced, for example, by means of atomization. In the case of iron semolina, for example, high-purity iron or a steel alloy, preferably high-purity iron, is used. For this purpose, for example, iron and optionally alloying constituents are fused together and sprayed or atomized the molten metal produced to a ferrous semolina. The iron-containing semolina thus obtained may then be classified, for example using a cyclone, to obtain a starting semolina having a desired size distribution.

The metal semolina, preferably iron grits or steel grits, having the desired size distribution is subsequently ground to uncoated flake-form metal pigments.

The grinding of the metal semolina, for example iron or steel grit, takes place predominantly according to the Hametagsche dry grinding process. Here, the metal grit in ball mills in several grinding stages at different grinding conditions, such as mill size, diameter, rotational speed, ball size, grinding time with the addition of lubricant, such as stearic or oleic acid, to prevent cold welding of the metal particles and grinding media, such as , As steel balls, ground. The uncoated platelet-shaped metallic effect pigments are collected after milling and optional classification in different containers and then homogenized or mixed.

In a wet grinding of metal semolina, such as iron or steel grit, this is ground in the presence of lubricants and solvents. Wet grinding is preferred because it is gentler than dry grinding.

In further preferred embodiments, the platelet-shaped metal cores have a h ₅₀ value in a range from 15 to 100 nm, preferably from 20 to 80 nm, particularly preferably from 23 to 75 nm and very particularly preferably from 26, according to a thickness count using scanning electron microscopy (SEM) to 67 nm, up.

Further, the flake-shaped metal cores in other embodiments, a via thickness counting by scanning electron microscopy (SEM) determined thickness distribution with a h ₉₀ value 23-150 nm, preferably 28-130 nm, more preferably 26-100 nm and more preferably from 29 to 83 nm, up.

In a further preferred embodiment of the invention, the platelet-shaped metal cores have an h ₁₀ value of the thickness distribution in the range from 12 to 70 nm and particularly preferably from 15 to 65 nm.

Furthermore, in further preferred embodiments, the platelet-shaped metal cores have a thickness distribution with scanning electron microscopy (SEM) determined relative width of the thickness distribution .DELTA.h, which based on the corresponding cumulative cycle curve of the relative frequency according to the formula Δh = (h ₉₀ -h ₁₀ ) / h ₅₀ is calculated from 0.3 to 0.9, preferably from 0.35 to 0.85 and more preferably from 0.4 to 0.8, on.

Furthermore, in other preferred embodiments, the platelet-shaped metal cores have an aspect ratio of from 2000: 1 to 5: 1. The uncoated metal cores are preferably characterized by an aspect ratio of 1150: 1 to 15: 1, more preferably from 850: 1 to 20: 1 and particularly preferably from 700: 1 to 90: 1.

Further information on a usable grinding method can be found in the WO 2009/152941 A2 , the disclosure of which is hereby incorporated by reference in its entirety.

In a further preferred embodiment, the semolina particles, for example iron particles or steel particles, are ground in two stages. In this case, the semolina particles are pre-formed in the first stage and ground in the second stage until the completely flat deformed metallic effect pigments.

According to a further preferred variant of the invention, it is also possible to use metallic effect pigments obtained by physical vapor deposition, such as iron pigments or steel pigments, preferably iron pigments, which are also referred to below as PVD iron effect pigments or PVD steel effect pigments.

PVD metallic effect pigments have an absolutely flat surface. In this case, a rough surface can not be produced by coating with metal oxide and a chemically non-reactive plastic layer. However, these uncoated flaky metal pigments of the present invention prepared by using PVD methods, after being coated with the two-layered coating of the present invention, exhibit excellent resistance to environmental corrosive influences and prevent metal ions, particularly heavy metal ions, from being released into the environment.

Metallic effect pigments according to the invention which are provided by using PVD metal pigments, in particular PVD iron pigments and PVD steel pigments, are suitable in particular with regard to the smooth surface for use in paints, printing inks, paints and cosmetics.

Furthermore, the invention relates to the use of the metal pigments according to the invention, in particular metal effect pigments, in a coating composition. Examples of coating compositions in which the metal pigments according to the invention can be used are water-based paints, powder coatings, nail varnishes, polymers and coil-coating formulations. The metal pigments according to the invention have proved to be particularly advantageous when used in coating compositions, such as powder coatings, cosmetic formulations, such as nail varnishes and coil coating varnishes. Particularly advantageous is the use in powder coatings considered.

The invention further relates to a coating composition which contains metal pigments according to the invention, preferably iron pigments and steel pigments, in particular iron pigments.

According to a preferred variant of the present invention, the coating agent is a lacquer, such as e.g. a coil coating lacquer, a lacquer concentrate, a printing ink, an ink concentrate, a paint, a color concentrate, a powder coating or a powder coating concentrate.

In the abovementioned coating compositions, it is of great advantage that the metal pigments according to the invention have a good application behavior in processes such as powder coating. Furthermore, for example, no appreciable amounts of metal ions, in particular heavy metal ions, preferably iron ions, will be released to the coating agent. In addition to an undesirable intrinsic coloration, which may arise as a result, naturally also interaction with constituents of the coating agent is a major problem.

The metal pigments according to the invention and / or the coating compositions according to the invention can be used for coating a wide variety of articles. Examples are car bodies, facade elements, printed matter, such as printed films, paper, cardboard, plastic moldings, etc. act.

A particularly preferred application of the pigments of the invention is in the field of powder coating. Powder coatings are used, for example, in industrial series production for coating electrically conductive and temperature-resistant materials. The powder coating to be applied is present as a solid and solvent-free powder. Furthermore, the powder coatings used as a primer or single-coat topcoat are almost completely recyclable. The environmentally friendly and versatile powder coatings contain binders, pigments, fillers and crosslinkers as well as optional additives. Under a binder according to the invention in the DIN 55 945 understood definition. That is, the binder includes both the film former and nonvolatile auxiliaries such as plasticizers and driers. A application of the finely powdered powder coatings is usually electrostatic before they are cured by baking or by radiation energy.

For the pigmentation of the powder coatings it is possible, inter alia, to use metal pigments. In the case of powder coatings produced by mixing processes, however, it can prove problematic that damage or destruction of the pigment platelets can occur due to the shear forces acting on platelet-shaped metal pigments during the extrusion and milling process. As a result, in particular the gloss and thus also the appearance of such pigmented applications can be adversely affected.

For this reason, for example, in the dry-blend process, the metal pigments are added to the base powder coating only after grinding. However, this has the disadvantage that during the paint application a possible separation of pigment and powder coating occurs due to the different charging behavior of the individual paint components. This results in an irregular optical effect in the applied lacquer layer due to accumulation or accumulation of pigment during powder coating application. Furthermore, the separation of pigment and binder leads to an altered composition of the "overspray". Alternatively, the so-called bonding method is used, in which the pigment is fixed with heating to the particles of the basecoat. However, the preparation of such bonding powder coatings is relatively expensive. The currently most cost-effective powder coatings are produced by means of mixing processes. Here, the pigments are mixed together with all other raw materials, extruded and ground.

Since powder coating-coated substrates are exposed to temperatures of 200 ° C after the powder coating application in an oven, it causes the metal pigments are oxidized, which is noticeable by an undesirable color change. It has been shown that even a very thick layer of plastic is not able to prevent the oxidation. However, such a plastic layer causes good chemical stability. Further, it has been found that a metal oxide layer effectively prevents oxidation. However, the chemical stability of such a layer is not sufficient. The application of both layers in conventional proportions, however, leads to a serious deterioration of the optical properties.

Surprisingly, however, it has been found that the desired stabilities are achieved by the coating to be applied according to the invention, while the optical properties of the pigment are virtually or completely retained.

Another preferred application of the pigments of the invention is in the field of coil coating coating. Coil coating is also known as a very environmentally friendly coating process. Coating and drying take place continuously in a closed system, whereby the rinsing of chemical residues is also eliminated in the no-rinse process. Furthermore, by an optimized process management, a contract efficiency of almost 100% can be achieved, while otherwise in most painting, for example, greater losses due to over spraying are available. However, since the paint is baked in the coil coating at temperatures of 240 to 280 ° C, oxidation phenomena in conventional metal pigments are observed here analogous to the powder coating. The problems and observations discussed above with regard to the powder coating therefore also apply to coil coating.

Another preferred application of the pigments of the invention is therefore in the field of coil coating coating. In cosmetic formulations, the metal pigments according to the invention, such as iron pigments and steel pigments, in particular metallic effect pigments, can be used for the particular application suitable raw materials, auxiliaries and active ingredients are combined. The concentration of metal pigments in the formulation may be between 0.001% by weight for rinse-off products and 40.0% by weight for leave-on products.

The metal pigments according to the invention, preferably metallic effect pigments, are particularly suitable for use in cosmetics, e.g. Body powder, face powder, pressed and loose powder, face makeup, powder cream, cream makeup, emulsion makeup, wax makeup, foundation, mousse makeup, cheek rouge, eye makeup such as eye shadow, mascara, eyeliner, liquid eyeliner, eyebrow pencil, lip balm, lipstick, lip gloss, lip liner, hair styling compositions Hair spray, hair mousse, hair gel, hair wax, hair mascara, permanent or semi-permanent hair colors, temporary hair colors, skin care compositions such as lotions, gels, emulsions and nail polish compositions.

To achieve special color effects, it is possible to use in the cosmetic applications, in addition to the metal pigments according to the invention, further colorants and / or conventional effect pigments or mixtures thereof in variable proportions. Examples of conventional effect pigments which may be obtained are commercial pearlescent pigments based on natural mica coated with high-index metal oxides (such as the product group Prestige from Eckart), BiOCl flakes, TiO ₂ flakes, pearlescent pigments based on synthetic mica coated with high refractive index metal oxides or based on glass platelets coated with high-index metal oxides (such as, for example, the product group MIRAGE from Eckart), Al ₂ O ₃ , SiO ₂ or TiO ₂ flakes. In addition, metallic effect pigments, such as, for example, the product group Visionaire from Eckart, can also be added. The colorants may be selected from inorganic or organic pigments.

The pigments according to the invention are particularly suitable for use in cosmetic formulations since, as a result of the coating according to the invention, leakage of metal ions, in particular iron ions, is prevented. As a result, for example, the incorporation of corresponding ferromagnetic pigments in systems such as nail varnishes is made possible, which can easily have a gelation due to the interaction with iron ions. Accordingly, by means of the pigments according to the invention a secure stability of corresponding formulations can be achieved even over longer periods of time. Furthermore, increased safety of the inclusion of metal ions, in particular heavy metal ions, for toxicological reasons or legal requirements is advantageous.

Another preferred application of the pigments of the invention is in the field of polymers. The polymers used here include thermoplastic, thermosetting or elastomeric polymers. Particularly preferred are thermoplastic polymers.

Examples of suitable thermoplastics are: polyoxyalkylenes, polycarbonates (PC), polyesters such as polybutylene terephthalate (PBT) or polyethylene terephthalate (PET), polyolefins such as polyethylene or polypropylene (PP), poly (meth) acrylates, polyamides, vinylaromatic (co) polymers such as polystyrene, impact-modified Polystyrene such as HI-PS, or ASA, ABS or AES polymers, polyarylene ethers such as polyphenylene ether (PPE), polysulfones, polyurethanes, polylactides, halogen-containing polymers, imidgruppenhaltige polymers, cellulose esters, silicone polymers or thermoplastic elastomers. It is also possible to use mixtures of different thermoplastics as materials for the polymer moldings. These mixtures may be single- or multi-phase polymer blends.

In preferred embodiments of the invention, the concentration of the pigments of the invention is at least 0.2% by weight, based on the total weight of the metal pigment-containing polymer. In further embodiments, it is preferred that the concentration of the pigments of the invention is at most 13% by weight, based on the total weight of the metal pigment-containing polymer. Higher. In particular, it is preferred in further embodiments of the present invention that the proportion of the pigments according to the invention in the polymer 0.2 to 13 wt .-%, preferably 0.5 to 11 wt .-%, still more preferably 0.8 to 8 wt. -%, in each case based on the total weight of the metal pigment-containing polymer.

The plastics containing the pigment according to the invention can also be used in laser marking. Upon irradiation, the laser beam heats the struck pigments according to the invention, which then lead to a visible change in the plastic surrounding the pigments.

For the production of laser-markable polymers, in further embodiments it is preferred that at least 0.001% by weight of pigment according to the invention is present in the polymer, based on the total weight of the pigment-containing polymer. On the other hand, it is preferred in further embodiments, that at most 0.7% by weight of pigment is contained, based on the total weight of the polymer containing the pigment. According to further preferred embodiments, the proportion of the pigments according to the invention in the polymer of 0.001 to 0.7 wt .-%, preferably 0.005 to 0.5 wt .-% and still more preferably 0.01 to 0.1 wt .-%, respectively based on the total weight of the pigment-containing polymer.

• (1a) Beschichten von ferromagnetischen Metallpigmenten mit mindestens einer umhüllenden Metalloxidschicht,
• (1b) Beschichten der in Schritt (1a) erhaltenen metalloxidbeschichteten ferromagnetischen Metallpigmente mit dem (den) Edukt(en) einer chemisch nichtreaktiven Kunststoffschicht,
• (1c) Aushärten oder Auspolymerisieren der in Schritt (1b) mit dem (den) Edukt(en) der chemisch nichtreaktiven Kunststoffschicht beschichteten ferromagnetischen Metallpigmente, oder
• (2a) Beschichten der ferromagnetischen Metallpigmente mit dem (den) Edukt(en) mindestens einer chemisch nichtreaktiven Kunststoffschicht,
• (2b) Aushärten oder Auspolymerisieren der in Schritt (2a) mit dem (den) Edukt(en) der chemisch nichtreaktiven Kunststoffschicht beschichteten ferromagnetischen Metallpigmente,
• (2c) Beschichten der in Schritt (2b) erhaltenen chemisch nichtreaktiven Kunststoffschicht beschichteten Metallpigmente mit Metalloxid. Insbesondere ist es bevorzugt, dass es sich bei den vorgenannten Metallpigmenten um Metalleffektpigmente handelt. Eine besonders bevorzugte Gruppe an Metallpigmenten, insbesondere Metalleffektpigmenten, sind eisenhaltige Pigmente mit mindestens 60 Gew.-% Eisen, bezogen auf das Gewicht des Metallkerns ohne Sauerstoff, wie Eisenpigmenten und Stahlpigmente, insbesondere Eisenpigmente.

Furthermore, the object of the invention is achieved by providing a process for producing a pigment according to the invention, the process comprising the following steps:

• (1a) coating ferromagnetic metal pigments with at least one enveloping metal oxide layer,
• (1b) coating the metal oxide-coated ferromagnetic metal pigments obtained in step (1a) with the educt (s) of a chemically non-reactive plastic layer,
• (1c) curing or polymerizing the ferromagnetic metal pigments coated in step (1b) with the educt (s) of the chemically non-reactive plastic layer, or
• (2a) coating the ferromagnetic metal pigments with the educt (s) of at least one chemically non-reactive plastic layer,
• (2b) curing or polymerizing the ferromagnetic metal pigments coated in step (2a) with the educt (s) of the chemically non-reactive plastic layer,
• (2c) Coating the metal pigments with metal oxide coated in the chemically non-reactive plastic layer obtained in step (2b). In particular, it is preferred that the aforementioned metal pigments are metallic effect pigments. A particularly preferred group of metal pigments, in particular metal effect pigments, are iron-containing pigments with at least 60% by weight iron, based on the weight of the metal core without oxygen, such as iron pigments and steel pigments, in particular iron pigments.

In particular, however, it is preferred that a chemically non-reactive plastic layer is applied last as the outermost layer, as described for example in steps (1b) and (1c). This seems to be particularly advantageous for applications such as powder coating.

In further preferred embodiments, the aforementioned coatings with metal oxide and / or the chemically non-reactive plastic layer are repeated or carried out with other metal oxides or educts of a chemically non-reactive plastic layer to provide a coating with multiple metal oxide layers and / or chemically non-reactive plastic layers.

The coating of metal pigments with metal oxide can be carried out in a conventional manner. For example, the metal oxides can be applied by hydrolyzing corresponding metal salts, such as metal halides, in particular the metal chlorides.

The metal oxide layer (s) are preferably uncalcined metal oxide layers.

Preferably, the metal oxide layers are applied by means of sol-gel method. Here, the corresponding metal alkoxides are hydrolyzed with the addition of water, and preferably acids or bases as catalysts, wherein the corresponding metal oxides and / or metal oxide on the metal pigments and coat them.

The alkoxy groups are preferably methoxy, ethoxy, propoxy, butoxy and / or pentoxy groups. Most preferably, the alkoxy groups are methoxy and / or ethoxy groups.

The coating with metal oxide by means of sol-gel process is usually carried out in organic solvent in the presence of small amounts of water, such as 1 to 10 vol .-%, preferably 2 to 5 vol .-%, water, based on the total volume of the hydrous organic solvent.

The organic solvents used are preferably alcohols, glycols, esters, ketones and mixtures of these solvents. Particularly suitable is the use of alcohols, glycols or mixtures thereof. Alcohols are particularly preferably used.

The alcohol is preferably selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, t-butanol, n-butanol, isobutyl alcohol, pentanol, hexanol and mixtures thereof. Ethanol and / or isopropanol have proven to be very suitable.

As the glycol, butyl glycol, propyl glycol, ethylene glycol or mixtures thereof are preferably used.

The metal pigments, preferably metallic effect pigments, are dispersed in the organic solvent with the optional addition of water. To this suspension either acid or base is added as catalyst.

Preferably, the dispersion is heated. The water required for the hydrolysis may already be contained in the organic solvent or added at a later time.

The acid may be organic and / or inorganic acid. The organic acid is preferably selected from the group consisting of formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, maleic acid, succinic acid, anhydrides of said acids and mixtures thereof. Preferably, formic acid, acetic acid, oxalic acid or mixtures thereof are used.

The inorganic acid may be selected from the group consisting of nitric acid, sulfuric acid, phosphoric acid, hydrochloric acid, boric acid, hydrofluoric acid and mixtures thereof. Preferably, nitric acid and / or hydrofluoric acid are used.

In a preferred variant, the basic catalyst is an amine. These may be primary, secondary or tertiary amines.

According to a preferred embodiment, the amine is selected from the group consisting of dimethylethanolamine (DMEA), monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), ethylenediamine (EDA), t-butylamine, monomethylamine, dimethylamine, trimethylamine, monoethylamine, Diethylamine, triethylamine, diisopropylethylamine, pyrridine, pyrridine derivatives, aniline, aniline derivatives, choline, choline derivatives, urea, urea derivative, hydrazine derivatives and mixtures thereof.

Ethylenediamine, monoethylamine, diethylamine, monomethylamine, dimethylamine, triethylamine or mixtures thereof have proven to be very suitable as basic amine catalyst.

Of course, inorganic bases such as ammonia, hydrazine, sodium hydroxide, potassium hydroxide, ammonium hydroxide, ammonium carbonate, ammonium hydrogencarbonate, sodium carbonate, sodium hydrogencarbonate, potassium carbonate, sodium bicarbonate or mixtures thereof may also be used. Ammonia and / or hydrazine have proven to be very suitable.

According to an extremely preferred embodiment, the metal alkoxide used is tetraalkoxysilane. As the tetraalkoxysilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane or condensates thereof or mixtures thereof are preferably used. Tetraethoxysilane and / or oligomers of tetraethoxysilane have proven to be very suitable.

Preferably, after application of the metal oxide layer, the metal oxide-coated metal pigments are separated off and the chemically non-reactive plastic layer is applied. The chemically non-reactive plastic layer can be built up by polymerization of suitable monomers. The monomers may have functionalities selected from the group consisting of amino, hydroxy, thiol, epoxy, acrylate, methacrylate, vinyl, allyl, alkenyl, alkynyl, carboxy, carboxylic anhydride, Isocyanate, cyanate, ureido, carbamate, ester groups and mixtures thereof are selected.

As starting materials of the plastic layer, in particular crosslinking monomers, or reactive oligomers or polymers, i. polyfunctional (meth) acrylates suitable. Examples of such compounds are: allyl methacrylate, bisphenol A dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol dimethacrylate, ethylene glycol dimethacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, diethylene glycol dimethacrylate, diurethane dimethacrylate, dipropylene glycol diacrylate, 1,12- dodecanediol dimethacrylate, ethylene glycol dimethacrylate, methacrylic anhydride, N, N-methylene-bis-methacrylamide, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, polyethylene glycol 200 diacrylate, polyethylene glycol 400 diacrylate, polyethylene glycol 400 dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tricyclodecane dimethanol diacrylate, tripropylene glycol diacrylate, triethylene glycol dimethacrylate, pentaerythritol triacrylate, Trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tris (2-hydroxyethyl) isocyanurate triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate or mixtures thereof.

In further embodiments, tri- and higher functional (meth) acrylates, in particular trifunctional (meth) acrylates, are preferred. The term "(meth) acrylate" in the sense of the present invention includes methacrylates and acrylates.

The curing or polymerization of vinyl and / or (meth) acrylate-functional monomers in the production of the chemically non-reactive plastic layer can be carried out thermally in preferred embodiments.

In further preferred embodiments, the curing or polymerization takes place by free-radical polymerization using polymerization initiators, preferably free-radical initiators. These are commercially available, usually organic or inorganic peroxides or diazonium compounds. Examples of such compounds are: acetyl cyclohexane sulfonyl peroxide, bis (2,4-dichlorobenzoyl) peroxide, diisononanyl peroxide, dioctanoyl peroxide, diacetyl and dibenzoyl peroxide; Peroxydicarbonates (eg, diisopropyl peroxydicarbonate, di-n-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, dicyclohexyl peroxydicarbonate), alkyl peresters (eg, cumylperneodecanoate, t-butyl perneodecanoate, t-amyl perpivalate, t-butyl per-2 ethylhexanoate, t-butyl perisobutyrate, t-butyl perbenzoate), dialkyl peroxides (eg, dicumyl peroxide, t-butyl cumyl peroxide, 2,5-dimethylhexane-2,5-di-t-butyl peroxide, di (t-butylperoxyisopropyl) benzene, di-t-butyl peroxide, or 2,5-dimethylhexyne-3-2,5-di-t-butyl peroxide), perketals (eg, 1,1'-bis (t-butylperoxy) -3,3,5-trimethylcyclohexanone peroxide, methyl isobutyl ketone peroxide, methyl ethyl ketone peroxide, acetylacetone peroxide), alkyl hydroperoxides (eg, pinane hydroperoxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide or t-butyl hydroperoxide), azo compounds (eg, 4-4'-azo-bis (4-cyanovaleric acid), 1.1 Azo-bis (cyclohexane-carbonitrile), 1,1'-azo-bis (isobutyric acid amidine) dihydrochloride, 2,2'-azo-bis (iso-butyronitrile), dimethyl 2,2'-azobis (2-methylpropionate) or persulfates such as sodium peroxodisulfate and potassium peroxodisulfate. Preference is given to 2,2'-azo-bis (isobutyronitrile) and dimethyl 2,2'-azobis (2-methylpropionate). These compounds are commercially available at Aldrich Chemie, D-89552, Steinheim or Wako Chemicals GmbH, Fuggerstrasse 12, 41468 Neuss ,

The educts of the plastic layer, for example reactive oligomers and / or polymers, may also be reactive polymers selected from the group consisting of polyacrylates, poly (meth) acrylates, polyethers, polyesters, polyamines, polyamides, polyols, polyurethanes, polyolefins and mixtures thereof are selected.

The metal oxide-coated metal pigments, according to a variant of the invention, are dispersed in a, preferably organic, solvent and the suspension is brought to the reaction temperature. Then, the starting materials of the plastic layer, for example in the form of organic monomers and / or reactive oligo- / polymers, and optionally polymerization initiators are added, for example by dropwise addition, whereby the chemically non-reactive plastic layer (organic polymer layer) is formed on the metal oxide coated metal pigments. Preferably, the dispersion is stirred or agitated during the application of the plastic layer.

Of course, the chemically non-reactive plastic layer can also be applied by spraying the educts of the plastic layer, for example the organic monomers and / or reactive organic oligomers and / or reactive organic polymers, and optionally of polymerization in a fluidized bed in which the metal oxide coated metal pigments are vortexed.

According to a preferred variant of the invention, the coating takes place in a liquid phase.

According to a further variant of the invention, the application of the chemically non-reactive plastic layer takes place in the same solvent in which the metal oxide layer has been applied. In contrast to the two-stage process variant described above, this process variant is one-stage.

After application of the chemically non-reactive plastic layer, these are preferably filtered off from the suspension.

According to a further variant of the invention, the application of at least one chemically non-reactive plastic layer takes place in the form of a thermal polymerization. It has been observed that in this thermal polymerization, which is carried out without addition of an initiator, smooth surfaces result.

According to a further variant of the invention, first at least one chemically non-reactive plastic layer is applied, subsequently at least one metal oxide layer and further below at least one further chemically non-reactive plastic layer. Preferably, the latter plastic layer is the outermost layer of the coating according to the invention.

The metal pigments according to the invention are preferably pelletized, granulated, strand-granulated, extruded, briquetted, tableted and thus present in a substantially low-dust, preferably dust-free, compacted form. In these dosage forms, the metal pigments of the invention can be handled easily and easily incorporated into coating compositions such as paints, inks, printing inks, powder coatings, plastics, cosmetics, etc.

According to a preferred variant, the metal pigments according to the invention are incorporated in powder coating.

According to a preferred variant of the invention, the chemically non-reactive plastic layer of the metal pigments is compatible with the binder or binder system of the powder coating.

According to a further embodiment, the present invention relates to coated metal pigments, preferably coated metallic effect pigments, which have been prepared according to the aforementioned process or one of its variants.

The alignment of the metal pigments of the invention is carried out using a magnetic field, which can be applied for example during the coating process. Additionally or alternatively, however, the magnetic field can also be used for alignment after the coating process, for example during the curing process, such as can be found in the powder coating. As a source for the magnetic field, for example, electromagnets or permanent magnets can be used. Here, for coating processes in which the orientation preferably takes place at least in one process step in which, for example, high temperatures act on the substrate, it has proven advantageous to use temperature-stable magnets. For example, polymer-coated magnets have proven to be very advantageous for effecting reproducible alignment of the pigments under many possible conditions.

The magnets can be attached directly to the back of the coated substrate in order to achieve the strongest possible effect. However, procedural advantages may also prevail, which is why a separating layer, for example a wall between the magnet and the substrate, is arranged. This eliminates, for example, complex forms of the magnet consuming cleaning steps and are replaced by a simple wiping the wall.

In addition, a form can be attached between magnet and substrate which partially shields the magnetic field. Here, for example, a stamped iron sheet can be used. As a result, an alignment of the pigments is limited to the recessed segments of the relevant shape, so that a standardized magnet, for example, an easily replaceable magnetic mat, can be used. In other preferred embodiments, therefore, a mold is inserted between the magnet and the substrate, this mold having an irregular permeability to the magnetic field. In particular, this form has recesses. Preferably, in this case materials are used for the mold, which greatly attenuate the magnetic field.

Furthermore, after the application of the coating agent, the magnet can be arranged on the rear side and / or front side of the coated substrate. By attaching to the front and back overlay patterns can be achieved, however, when mounting on the front must be maintained a certain distance from the applied coating agent. In order to compensate for deviations of the magnetic field strengths, it may be advantageous, in particular in such cases, to apply a spacer on the rear side, so that an identical distance is maintained on the front and rear sides.

In the case of magnetic substrates, the magnetization of the magnets may already be sufficient to allow a fixation. Otherwise, a variety of mounting options are available to the person skilled in the art, such as staples, adhesive, adhesive tape, holders, etc. Furthermore, for example, in the case of a horizontal arrangement, it is also possible to completely dispense with a corresponding attachment.

Continuous process control is also possible, in which, for example, a magnet is guided along a strip of material to be coated during the coating process in order to effect the alignment of the metal pigments. For example, it is possible correspondingly shaped magnets into a roll and / or on a roll over which the material to be coated is guided during the coating process. Furthermore, magnets may for example be mounted on conveyor belts which are passed by the material to be coated or the coated material. Furthermore, magnets can for example be brought to a continuously guided material to be coated or coated material for the purpose of aligning the metal pigments, preferably guided parallel to a defined time at an identical speed and then removed again. In this case, the magnet is preferably attached in an endless loop, for example to different points of the same endlessly guided material.

For the preparation of mass-produced articles, it may be preferable to remove the magnet directly after alignment of the metal pigments according to the invention in order to be able to use it for aligning the next pigments. Care must be taken here that the pattern produced is not adversely affected by, for example, a non-uniform removal of the magnet.

Furthermore, it may be preferable to keep the magnet fixed to the coated material until the curing of the coating agent in order to achieve the best possible alignment and thus the best possible alignment. For example, particularly good contrasts can be achieved even with relatively weak magnets in the Puvlerlackbeschichtung when the magnets are fixed during the curing process on the coated material.

Further, multiple magnets may be used one upon another or at different times, such as during coating, after coating, and during an optional existing curing process, to produce specific patterns with, for example, different contrast, etc.

Examples of further preferred embodiments are given in the following aspects.

According to one aspect, the present invention relates to coated metal pigments, the metal pigments comprising a metal core and a coating enveloping the metal core, the metal core comprising at least 60% by weight of at least one ferromagnetic metal, the coating enveloping the metal core having at least one enveloping metal oxide layer and at least one enveloping chemically non-reactive plastic layer, wherein the content of the at least one enveloping metal oxide layer at least 9 wt .-% and the content of the at least one enveloping plastic layer at least 0.4 wt .-%, each based on the weight of the uncoated metal pigment, wherein the at least one metal oxide layer enveloping the metal core is not an oxidation product of the metal core.

According to one aspect, the present invention relates to coated metal pigments according to aspect 1, wherein the weight ratio of the at least one enveloping metal oxide layer to the at least one enveloping chemically non-reactive plastic layer is greater than 1: 1.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein the content of the at least one enveloping metal oxide layer is at most 45% by weight and / or the content of the at least one enveloping plastic layer is at most 23% by weight, in each case based on the weight of the uncoated metal pigment is.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein the weight ratio of the at least one enveloping metal oxide layer to the at least one enveloping chemically non-reactive plastic layer in a range of 1: 1 to 36: 1, preferably in a range of 7: 6 to 30: 1, more preferably in the range of 6: 5 to 27: 1, even more preferably in the range of 5: 4 to 24: 1.

According to one aspect, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein the sum of the contents of the at least one enveloping chemically non-reactive plastic layer and the at least one enveloping metal oxide layer in a range from 9.4 to 68 wt .-%, preferably in a range of 11 to 54 wt .-%, more preferably in a range of 11.7 to 49 wt .-%, even more preferably in a range of 12.3 to 43 wt .-%, in each case based on the Weight of the uncoated metal pigment.

According to one aspect, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein the metal pigment is platelet-shaped.

According to one aspect, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein the metal core consists of at least 60% by weight of at least one ferromagnetic metal selected from the group consisting of iron, cobalt and nickel.

According to an aspect 8, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein the metal core consists of at least 60% by weight of iron.

According to an aspect 9, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein the metal core is an iron pigment.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein at least one enveloping metal oxide layer is arranged between the metal core and the at least one plastic encasing layer, wherein the at least one encapsulating metal oxide layer is not an oxidized layer of the metal core.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein at least one chemically non-reactive plastic layer is arranged between the metal core and the at least one enveloping metal oxide layer.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein at least at least one, preferably all, of the coating metal oxide layers of the coating, which are not oxidation products of the metal core, are selected from the group consisting of silicon oxide, aluminum oxide, boron oxide, Zirconium oxide, cerium oxide, iron oxide, titanium oxide, chromium oxide, tin oxide, molybdenum oxide, their hydrated oxides, their hydroxides and mixtures thereof.

According to one aspect, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein at least at least one, preferably all, of the enveloping metal oxide layers of the coating is selected from the group consisting of silicon oxide, its oxide hydrates, its hydroxides and mixtures thereof.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein at least one, preferably all, enveloping chemically non-reactive plastic layers of the coating consists essentially of plastic, which is selected from the group consisting of polyacrylate, polymethacrylate, polyacrylamide, polyacrylonitrile , Polyvinyl chloride, polyvinyl acetate, polyamide, polyalkene, polydiene, polyalkyne, polyalkylene glycol, epoxy resin, polyester, polyether, polyol, polyurethane, polycarbonate, polyethylene terephthalate, and mixtures thereof.

According to one aspect, the present invention relates to coated metal pigments according to any one of the preceding aspects, wherein at least one, preferably all, enveloping chemically non-reactive plastic layers of the coating consist essentially of polyacrylate, polymethacrylate or mixtures thereof.

According to one aspect of the invention, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein the plastic layers contained in the coating consist essentially of polyacrylate, polymethacrylate or mixtures thereof, the coating metal oxide layers contained in the coating essentially of silicon oxide, its oxide hydrates, its oxide Hydroxides and mixtures thereof, and the weight ratio of the at least one enveloping metal oxide layer to the at least one enveloping chemically non-reactive plastic layer in a range of 6: 5: 1 to 27: 1

According to an aspect 17, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein the at least one enveloping chemically non-reactive plastic layer is obtained by thermal polymerization.

According to one aspect, the present invention relates to coated metal pigments according to one of the preceding aspects, wherein the at least one enveloping chemically non-reactive plastic layer is obtained by initiator-induced free-radical polymerization.

According to one aspect 19, the present invention relates to a coating agent containing coated metallic pigments according to any one of the preceding aspects.

According to one aspect, the present invention relates to a coating agent, wherein the coating agent is selected from the group consisting of powder coatings and coil coating coating compositions.

According to an aspect 21, the present invention relates to a coated article comprising metal pigments according to any one of aspects 1 to 18 or a coating agent according to any of aspects 19 to 20.

According to one aspect 22, the present invention relates to a cosmetic, such as a nail varnish, which contains coated metal pigments according to any one of aspects 1 to 18.

According to an aspect 23, the present invention relates to a use of coated metal pigments according to any one of aspects 1 to 18 in a coating agent or cosmetic.

According to an aspect 24, the present invention relates to the use according to aspect 23, wherein the coating agent is a powder coating and coil-coating agent.

According to one aspect, the present invention relates to the use according to any one of aspects 23 to 24, wherein the cosmetic is selected from the group consisting of body powder, face powder, pressed and loose powder, face makeup, powder cream, cream makeup, emulsion makeup, wax makeup, foundation, mousse makeup , Cheek blush, eye makeup such as eye shadow, mascara, eyeliner, liquid eyeliner, eyebrow pencil, lip balm, lipstick, lip gloss, lip liner, hair styling compositions such as hair spray, hair mousse, hair gel, hair wax, hair mascara, permanent or semi-permanent hair colors, temporary hair colors, skin care compositions such as Lotions, gels, emulsions and nail polish compositions. The cosmetic is particularly preferably a nail polish.

• (1a) Beschichten von ferromagnetischen Metallpigmenten mit mindestens einer umhüllenden Metalloxidschicht,
• (1b) Beschichten der in Schritt (1a) erhaltenen metalloxidbeschichteten ferromagnetischen Metallpigmenten mit dem (den) Edukt(en) mindestens einer umhüllenden chemisch nichtreaktiven Kunststoffschicht,
• (1c) Aushärten oder Auspolymerisieren der in Schritt (1b) mit dem (den) Edukt(en) einer umhüllenden chemisch nichtreaktiven Kunststoffschicht beschichteten ferromagnetischen Metallpigmente, oder
• (2a) Beschichten der ferromagnetischen Metallpigmenten mit dem (den) Edukt(en) mindestens einer umhüllenden chemisch nichtreaktiven Kunststoffschicht,
• (2b) Aushärten oder Auspolymerisieren der in Schritt (2a) mit dem (den) Edukt(en) einer umhüllenden chemisch nichtreaktiven Kunststoffschicht beschichteten ferromagnetischen Metallpigmente,
• (2c) Beschichten der in Schritt (2b) erhaltenen umhüllenden chemisch nichtreaktiven Kunststoffschicht beschichteten Metallpigmente mit mindestens einer umhüllenden Metalloxidschicht.

According to one aspect, the present invention relates to a method for producing a coated metal pigment according to one of the aspects 1 to 18, the method comprising the following steps:

• (1a) coating ferromagnetic metal pigments with at least one enveloping metal oxide layer,
• (1b) coating the metal oxide-coated ferromagnetic metal pigments obtained in step (1a) with the educt (s) of at least one enveloping chemically non-reactive plastic layer,
• (1c) curing or polymerizing the ferromagnetic metal pigments coated in step (1b) with the educt (s) of an enveloping chemically non-reactive plastic layer, or
• (2a) coating the ferromagnetic metal pigments with the educt (s) of at least one enveloping chemically non-reactive plastic layer,
• (2b) curing or polymerizing the ferromagnetic metal pigments coated in step (2a) with the educt (s) of an enveloping chemically non-reactive plastic layer,
• (2c) coating of the coated chemically non-reactive plastic layer obtained in step (2b) coated metal pigments having at least one enveloping metal oxide layer.

In particular, it is preferred that the aforementioned metal pigments are metallic effect pigments, i. platelet-shaped metal pigments, acts. Furthermore, the abovementioned metal pigments are preferably iron-containing metal pigments, more preferably iron pigments or steel pigments, in particular iron pigments.

According to an aspect 27, the present invention relates to a method according to aspect 26, wherein educt (s) of the enveloping chemically non-reactive plastic layer vinyl and / or (meth) acrylate-functional monomers are used.

According to one aspect, the present invention relates to a method according to one of the aspects 26 to 27, wherein the at least one enveloping chemically non-reactive plastic layer, preferably all enveloping chemically non-reactive plastic layers, is thermally cured.

According to one aspect 29, the present invention relates to a method according to one of the aspects 26 to 28, wherein at least one enveloping chemically non-reactive plastic layer, preferably all enveloping chemically non-reactive plastic layers, is cured free-radically using a polymerization initiator (are).

shows two powder coated metal sheets. The left was coated with a metal pigment according to the invention according to Comparative Example 1-1. The right sheet was coated with a metal pigment according to the invention according to Example 1-1. It can be seen that the pigments of the invention have a significantly better coverage, which is why the bright base sheet leads to a lighter coating in the left sheet.

The invention is explained in more detail below by means of examples, without being limited thereto.

Examples

Example 1: Coating of Metallic Pigments

Metal oxide layer 1a

In a 1 liter jacketed reactor 387 g of a 71% Ferricon 200 (18 microns) paste (equivalent to 275 g of pigment) from Eckart GmbH were dispersed in 398 g of ethanol. It was then heated to 75 ° C and tetraethoxysilane (TEOS) was added. Thereafter, a mixture consisting of 77 g of water and 42 g of 25% aqueous ammonia solution was added and stirred for 12 h. Thereafter, the product was filtered off and obtained as a paste. The amount of TEOS used can be found in the table below.

Plastic coating 1b

100 g (based on the pigment, without solvent) of the product obtained above (with metal oxide layer) were dispersed with 200 g of ethanol and BYK-C 8000, after which it was heated to a temperature of 75 ° C. Over 2 h, a mixture consisting of trimethylolpropane trimethacrylate (TMPTMA) and azo-bis (isobutyronitrile) (AIBN) (available from Sigma Aldrich), which was made up to 150 ml with ethanol, was metered in. The mixture was stirred for 12 h at 75 ° C and then filtered with suction. Thereafter, the product was dried in a vacuum oven and sieved with 100 microns mesh size. The amounts of MEMO, TMPTMA and AIBN used can be found in the following table.

In the case of Comparative Example 1-10, instead of the metal oxide-coated pigment, 70 g of Ferricon 200 (from Eckart GmbH) were used. Ferricon 200 example Implementation analog BYK-C 8000 [g] TMPTMA [g] AIBN [g] TEOS [g] VB 1-1 1a, 1b 1 4.5 1 68.3 VB 1-2 1a, 1b 1 10 1 68.3 VB 1-3 1a, 1b 1 14 1 68.3 VB 1-4 1a, 1b 1 16.9 1 68.3 VB 1-5 1a, 1b 1 4.5 1 82.5 VB 1-6 1a, 1b 1 10 1 82.5 VB 1-7 1a, 1b 1 14 1 82.5 VB 1-8 1a, 1b 1 16.9 1 82.5 VB 1-9 1a, 1b 82.5 VB 1-10 1a, 1b 14 Example 1-1 1a, 1b 1 4.5 1 117 Example 1-2 1a, 1b 1 4.5 1 148.3 Example 1-3 1a, 1b 1 14 1 148.3 Example 1-4 1a, 1b 1 16.9 1 148.3 Example 1-5 1a, 1b 1 4.5 1 167 Example 1-6 1a, 1b 1 16.9 1 167 Example 1-7 1a, 1b 1 2.8 1 167 Example 1-8 1a, 1b 1 1.2 1 167 Example 1-9 1a, 1b 1 4.5 1 200 Example 1-10 1a, 1b 1 2.8 1 200 Example 1-11 1a, 1b 1 14.0 1 117 Example 1-12 1a, 1b 1 4.6 1 117 Example 1-13 1a, 1b 1 2.9 1 117 Example 1-14 1a, 1b 1 14.0 1 149 Example 1-15 1a, 1b 1 6.7 1 149 Example 1-16 1a, 1b 1 4.7 1 149 Example 1-17 1a, 1b 1 3.0 1 149 Example 1-18 1a, 1b 1 14 1 82.5 Ferricon 120 Implementation analog BYK-C 8000 [g] TMPTMA [g] AIBN [g] TEOS [g] Example 1-19 1a, 1b 1 2.2 1 275 Example 1-20 1a, 1b 1 4.7 1 148.5 Example 1-21 1a, 1b 1 3.0 1 148.5 Example 1-22 1a, 1b 1 6.6 1 117 Example 1-23 1a, 1b 1 2.9 1 117 VB: Comparative Example

Application Example 1: Application Powder Coating

The resulting pastes were dried under vacuum with a slight inert gas at 100 ° C and then sieved with 71 microns mesh size. The respective metallic effect pigment was incorporated together with the powder coating Tiger, company Tiger Coatings GmbH & Co. KG, as well as 0.2% Aeroxide Alu C (Evonik) by means of ThermoMix for 4 minutes at level 4. The pigmentation level was 5.0% by weight, since with higher pigmentation a verifiable application behavior can be achieved. As a result, the powder paint was weighed out to 95.0% by weight. The total amount of powder coating in the mixer was 300 g plus 0.6 g of Aeroxide Alu C. The ThermoMix is a commercial kitchen mixer (Vorwerk). The addition Aeroxide Alu C is Al ₂ O ₃ particles, which in this application assumes the function of a Rieselmittels. The powder coatings were applied with the OptiSelect (ITWGema) in a commercially available powder booth. In order to assess the application properties, spraying was carried out in the powder booth for 20 seconds according to the parameters given in Table 1, then the coating of the substrate was carried out and then the adhesions to the electrodes and to the impact plate were assessed. This method allows a conclusion on the long-term behavior of the pigments during the practice-oriented coating.

Furthermore, the spray pattern was evaluated on the basis of the baked powder coating. The focus was mainly on the cover. Depending on the thickness of the metal oxide and the plastic thickness, sheets with very poor coverage (here the background can still be recognized) up to very good coverage (background no longer visible) were generated. In addition to the course, so the smoothness of the surface structure, as well as on black, microscopic flaws, so-called black spots were thrown. Black spots are areas on the powder coating surface that are caused by an inhomogeneous distribution of the metallic effect pigments. Since these phenomena are in the macroscopic range, a lacquer-technically trained look is required to assess the appearance. Particular preference is very much smooth structures with a very smooth gradient without the appearance of black spots. The application behavior, the presence of black spots and the structure or the course of the powder coatings were assessed visually.

It was found that the pigments according to Comparative Example 1-9, which had only one silicon oxide layer, could not be applied as a powder coating. The corresponding powder coating did not adhere to the substrate.

The magnetic mats were applied according to two variants:

Variant 1: Temperature-sensitive magnetic mat (removal before curing)

The magnetic mat is attached to the aluminum sheet before the powder coating application. This is followed by the powder coating application known to the person skilled in the art. Subsequently, the magnet is removed before the aluminum sheet is transferred to the curing in the oven (oven temperature 200 ° C 12 min).

A single-pole multi-pole magnetic mat (strip structure, Permaflex 928 PE / PVDF single-sided multipolar, Rhine magnet) and an axially magnetized mat (areal structure, Permaflex 928 PE / PVDF axially magnetized, Rhine magnet) each 2 * 2 cm was used. The axially magnetized mat produced a homogeneous square from which in the middle the L-value was measured according to CIE-LAB. Subsequently, the L values of the non-magnetized region were recorded and the difference was determined in accordance with magnetized - not magnetized (in the table Diff Contrast magn / not magn). The sheets, which showed a high difference, also showed optically the best contrast. Values <1 showed e.g. a very poor contrast, plates with 1-2.2 a mediocre contrast and plates with a difference of> 2.2 a very good contrast.

Variant 2: Temperature-stable magnetic mat (when hardened, the magnetic mat remains fixed to the substrate)

The temperature-stable magnetic mat (MAGNETOplast magnetic film 1.0 mm, Haas & Co Magnettechnik GmbH, one-sided multi-pole, and ZG-dimagn 1.0 from OK-Steinl, one-sided multi-pole) is attached to the aluminum sheet before the powder coating application by means of a temperature-stable adhesive tape. This is followed by the powder coating application known to the person skilled in the art. Subsequently, the aluminum sheet is transferred to the oven for curing, wherein the magnetic mat remains fixed to the substrate. After curing, the magnetic mat can be removed again. All experiments according to variant 2 were carried out exclusively with single-sided multi-pole magnetic mats, so that a difference determination between magnetized and non-magnetized regions was not possible because the line width of the strips was too small. Ferricon 200 version 1 Variant 2 example % SiO 2 % Plastic cover Diff Contrast magn / not magn contrast magnetization magnetization VB 1-1 6.9 4.3 0 1.80 medium hot - ++ VB 1-2 6.9 11.7 - 1.50 out of focus, very poor coverage - ++ VB 1-3 7.2 15.8 - 1.64 out of focus, bad coverage - nb VB 1-4 7.2 19.9 - 0.45 blurred - nb VB 1-5 8.8 4.2 - 0.96 medium hot - nb VB 1-6 8.8 11.1 - 0.25 blurred - nb VB 1-7 8.6 15.4 - 0.14 out of focus, bad coverage - nb VB 1-8 8.6 18.7 - -0.73 out of focus, bad coverage - nb Example 1-1 12.1 4.2 ++ 2.73 medium hot ++ +++++ Example 1-2 14.8 4.4 ++ 2.87 medium hot ++ ++++ Example 1-3 14.5 16.4 ++ 1.40 out of focus / medi umsch 0 +++++ Example 1-4 14.5 19.7 + 1.47 blurred 0 nb Example 1-5 16.1 4.3 ++ 2.32 medium hot ++ +++++ Example 1-6 16.1 20.6 + 1.46 blurred 0 +++++ Example 1-7 16.7 1.5 ++ 2.54 sharp +++ nb Example 1-8 15.8 0.9 ++ 2.04 sharp +++ nb Example 1-9 19.8 4.7 ++ 2.72 sharp +++ nb Example 1-10 18.5 1.3 ++ 2.77 sharp +++ nb Example 1-11 11.8 7.5 ++ nb nb nb +++++ Example 1-12 12.1 5.4 ++ nb nb nb +++++ Example 1-13 11.8 4.0 ++ nb nb nb +++++ Example 1-14 13.0 15.2 ++ nb nb nb +++++ Example 1-15 13.0 7.7 ++ nb nb nb +++++ Example 1-16 13.0 5.7 ++ nb nb nb +++++ Example 1-17 13.0 3.7 ++ nb nb nb +++++ nb: not determined
Coverage: (-) very bad, (-) bad, (0) mediocre, (+) good, (++) very good
Magnetization: (-) hardly any contrast, (+) some contrast, (++) satisfying contrast, (+++) good contrast, (++++) very good contrast, (+++++) extremely good contrast Ferricon 120 example % SiO 2 % Plastic cover Diff Contrast magn / not magn contrast magnetization magnetization Example 1-19 25.2 3.5 ++ nb nb nb +++++ Example 1-20 13.1 5.8 ++ nb nb nb +++++ Example 1-21 12.5 4.1 ++ nb nb nb +++++ Example 1-22 10.6 7.5 + nb nb nb ++++ Example 1-23 10.4 4.0 ++ nb nb nb ++++ nb: not determined

Ferricon 200 with only one silicon oxide layer can not be applied as a powder coating. The powder coating does not adhere to the sheet.

Application Example 1-a: Oxidation Test

When Ferricon 200 is provided with a plastic layer, the pigment is powder-coatable, but the pigment changes its color during curing due to oxidation processes, which turn yellow. If both layers are combined, the corresponding products are powder-coatable and resistant to oxidation. coating application oxidation comment Overall VB 1-9 SiO ₂ bad nb In powder coating application no adhesion to the sheet - VB 1-10 Plastic layer Good Oxidation, yellowing oxidation Labil - Example 21 SiO ₂ / polymer Good No oxidation positive + VB: Comparative Example
nb: not determined example L * a * b * .DELTA.L * .DELTA.a * .DELTA.b * comment VB-10 10 min / 200 ° C 51.90 0.17 2.65 60 min / 200 ° C 48.87 0.69 5.66 -3.03 0.52 3.01 yellowish Example 21 10 min / 200 ° C 54.19 0.19 1.34 60 min / 200 ° C 51.42 0.42 2.02 -2.77 0.23 0.68 No yellowing

In the oxidation test, two sheets of VB-10 were prepared as well as Example 21. Each sheet was cured for 10 min at 200 ° C and one for 60 min. Afterwards the Lab values were recorded and the difference (Lab (10 min) - Lab (60 min) was determined.) At VB-10 a clear yellowish tinge was seen, which is expressed in the Δb * value of 3.01.

Application Example 1-b: Chemical Test

The coated test panel was placed in a horizontal position. It was applied 1 drop of 10% HCl with the exposure times 180 min. Furthermore, 1 drop of 1 M NaOH was applied with the reaction times 180 min. Both drops were applied so that they half covered the non-magnetized area and half the magnetized area. Example 1 shows no attack after 180 minutes.

Application Example 2: Nail Polish

The metallic effect pigments according to any one of Examples 1-7, 1-9 and 1-15 were stirred with a pigmentation of 4 wt .-% in the base 359 (by International Lacquers) with a brush and then transferred to commercially available nail polish bottles. Hereafter, the nail polish was stored at RT for a period of 4 weeks. This showed no gelation of the nail polish.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10114446 A1 [0002]
• DE 10114445 A1 [0003]
• WO 2007/017195 A2 [0004]
• WO 2005/063897 A2 [0005, 0054]
• EP 1541642 A1 [0006]
• DE 19820112 A1 [0007]
• DE 4030727 A1 [0008]
• US 2009/0117281 A1 [0009]
• WO 2008/095697 A1 [0010, 0010, 0011, 0092]
• WO 2009/149834 A2 [0011]
• EP 1812519 B1 [0094]
• WO 2009/152941 A2 [0126]

Cited non-patent literature

• DIN 55 945 [0136]
• Aldrich Chemie, D-89552, Steinheim or Wako Chemicals GmbH, Fuggerstrasse 12, 41468 Neuss [0175]

Claims (15)

 Coated metal pigments, wherein the metal pigments comprise a metal core and a coating enveloping the metal core, wherein the metal core consists of at least 60% by weight of at least one ferromagnetic metal, the coating enveloping the metal core has at least one enveloping metal oxide layer and at least one enveloping chemically non-reactive plastic layer, the content of the at least one metal oxide layer being at least 9% by weight and the content of the at least one plastic layer being at least 0.4% by weight, based in each case on the weight of the uncoated metal pigment is, wherein the at least one metal oxide layer enveloping the metal core is not an oxidation product of the metal core.  Coated metal pigments according to claim 1, wherein the weight ratio of the at least one metal oxide layer to the at least one chemical non-reactive plastic layer is greater than 1: 1.  Coated metal pigments according to one of claims 1 to 2, wherein the content of the at least one metal oxide layer is at most 45 wt .-% and the content of the at least one plastic layer at most 23 wt .-%, each based on the weight of the uncoated metal pigment.  Coated metal pigments according to one of the preceding claims, wherein the weight ratio of the at least one metal oxide layer to the at least one chemically non-reactive plastic layer is in a range from 1: 1 to 36: 1.  Coated metal pigments according to one of the preceding claims, wherein the metal pigment is platelet-shaped.  Coated metal pigments according to any one of the preceding claims, wherein the metal core is at least 60% by weight iron, based on the weight of the metal core without oxygen.  Coated metal pigments according to one of the preceding claims, wherein at least one metal oxide layer is arranged between the metal core and the at least one plastic layer, wherein the at least one metal oxide layer is not an oxidized layer of the metal core.  Coated metal pigments according to one of the preceding claims, wherein at least one chemically non-reactive plastic layer is arranged between the metal core and the at least one metal oxide layer.  Coated metal pigments according to one of the preceding claims, wherein at least at least one, preferably all, of the metal oxide layers of the coating are selected from the group consisting of silicon oxide, its oxide hydrates, its hydroxides and mixtures thereof.  Coated metal pigments according to one of the preceding claims, wherein the plastic layers contained in the coating consist essentially of polyacrylate, polymethacrylate or mixtures thereof, the metal oxide layers contained in the coating consisting essentially of silicon oxide, its oxide hydrates, its hydroxides or mixtures thereof, and the weight ratio the at least one metal oxide layers to the at least one chemically non-reactive plastic layers in a range of 6: 5 to 27: 1  Coating composition, wherein the coating composition contains coated metal pigments according to one of the preceding claims.  The coating composition according to claim 11, wherein the coating agent is selected from the group consisting of powder coatings and coil coating coating compositions.  Use of coated metal pigments according to one of claims 1 to 10 in a coating agent or cosmetic.  Use according to claim 13, wherein the coating agent is a powder coating or a coil coating coating agent and / or the cosmetic is a nail polish. Process for the preparation of a coated metal pigment according to one of Claims 1 to 10, comprising the following steps: (1a) coating ferromagnetic metal pigments with at least one enveloping metal oxide layer, (1b) coating the metal oxide-coated ferromagnetic metal pigments obtained in step (1a) with the ( the educt (s) of at least one enveloping chemically non-reactive plastic layer, (1c) curing or polymerizing the ferromagnetic metal pigments coated in step (1b) with the educt (s) of a chemically non-reactive plastic layer, or (2a) coating the ferromagnetic metal pigments (b) hardening or polymerizing the ferromagnetic metal pigments coated in step (2a) with the educt (s) of a chemically non-reactive plastic layer, (2c) coating the in step (2b) erha lenth chemically non-reactive plastic layer-coated metal pigments having at least one enveloping metal oxide layer.

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