Coated metallic effect pigments, their production method and use - Patents.com

Abstract

Providing coated flake-shaped metallic effect pigments. [Solution] A coated flaky metal effect pigment comprising a metal effect flake as a substrate, the substrate being coated with the following successive coating sequence: (a) optionally a discontinuous or continuous layer of Mo oxide, (b1) an inorganic metal oxide layer mainly comprising SiO2, (c1) a hybrid layer comprising SiO2 modified by diphenylsilane, phenylsilane or mixtures thereof, or (c2) a hybrid layer comprising SiO2 modified by diphenylsilane, phenylsilane or mixtures thereof, (b2) an inorganic metal oxide layer mainly comprising SiO2, and (d) optionally a further topcoat of an organofunctional silane, titanate, aluminate or zirconate.

Description

[Technical Field]

[0001] The present invention relates to coated metallic effect pigments that are suitable for aqueous coating formulations. [Background technology]

[0002] Metal effect pigments, especially aluminum effect pigments, are susceptible to corrosion. In particular, when they are used in aqueous coating formulations, the pigments can react with water under the evolution of hydrogen. Therefore, they need to be passivated before being used in aqueous coating formulations. For non-aggressive aqueous formulations, stabilization with additives such as phosphonic acid or phosphoric acid esters may be sufficient, as is well known.

[0003] Silica-coated metal effect pigments are currently the most accepted metal effect pigments used in the more aggressive water-based coating formulations of automotive or industrial coatings. Products are commercially available, for example, under the trade names Hydrolan™ (Eckart GmbH) or Emeral™ (Toyo Aluminum Kasei). Passivated metal effect pigments of this type currently represent the "gold standard" for gassing-stable aluminum pigments.

[0004] In such passivated metal effect pigments, a dense silica coating provides a passivation layer for gassing stability, and the silica surface can be further modified with suitable organic groups to make it compatible with organic binder systems, thus rendering the pigments stable to the cross-cut test (DIN EN ISO 2409) after the water condensation-constant atmosphere test (DIN EN ISO 50 017). Such tests represent standard test methods for pigments for all exterior applications, particularly the automotive industry. The silica layer is formed by sol-gel synthesis.

[0005] EP1619222A1 disclosed that gassing stability could be further increased by introducing a first layer of molybdenum oxide before the silica coating.

[0006] The silica layer itself may be susceptible to mechanical forces. WO 2007 / 017195 A2 discloses a hybrid inorganic / organic layer that can withstand the mechanical forces that occur, for example, during the processing of coated metal effect pigments in mixers during large-scale production.

[0007] Further increases in gassing stability, as measured by more intensive gassing tests in the presence of such hybrid layer-stabilizing iron oxide, are disclosed in WO 2016 / 120015 A1, where again a hybrid inorganic / organic layer is used in which a silica network is modified with organic oligomers or polymers that are bonded to the silica via a network morphology. Summary of the Invention [Problem to be solved by the invention]

[0008] Currently, customer demands are still increasing regarding gassing stability in very aggressive gassing tests and greater mechanical impact as represented by the intensified Waring Blender test. Such tests are accepted in the art as laboratory tests to simulate the effects of shear forces in automotive circulation lines on flake effect pigments. It is therefore an object of the present invention to provide coated metallic effect pigments that can pass these more intensified tests.

[0009] In particular, it is an object of the present invention that the coated flake-shaped metal effect pigments should have optical properties after the treatment described in the experimental section and the so-called intensified "Waring Blender" test, in which, compared to the unsheared metal effect pigments, ΔL *The value is preferably ≦2.60, more preferably ΔL at any of the measured observation angles of 15°, 25°, 45°, 75°, and 110°. * ≦2.20.

[0010] It is a further object of the present invention to provide a method for producing such metallic effect pigments. [Means for solving the problem]

[0011] The object of the present invention has been solved by providing a coated flaky metal effect pigment comprising metal effect flakes as substrate, said substrate being coated by the following successive coating sequence: (a) optionally, a discontinuous or continuous layer of Mo oxide; (b1) an inorganic metal oxide layer mainly containing SiO2; (c1) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane, or a mixture thereof; or (c2) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane, or a mixture thereof; (b2) an inorganic metal oxide layer containing mainly SiO2; and (d) Optionally, a further topcoat of organofunctional silane, titanate, aluminate or zirconate.

[0012] Further preferred embodiments of this coated flake-shaped metal pigment are disclosed in claims 2-11.

[0013] The object was further solved by providing a method for producing these flaky coated metal pigments comprising the following steps: (a) optionally coating a metal substrate with a discontinuous or continuous layer of Mo oxide; (b1) coating the metal substrate or the substrate obtained in step (a) with an inorganic metal oxide layer comprising mainly SiO2, preferably by a sol-gel method using TEOS as precursor material; (c1) On the layer (b1), a tetraalkoxysilane of formula Si(OR)4(I), Diphenylsilane of formula PhSi(OR')(IIa), a phenylsilane of formula PhSi(OR')3(IIb), or a mixture thereof, forming a hybrid layer by a sol-gel reaction of wherein R is methyl, ethyl, n-propyl or isopropyl, n-butyl or isobutyl, and R' is independently methyl or ethyl; or (c2) treating the metal substrate or the substrate obtained in step (a) a tetraalkoxysilane of formula Si(OR)4(I), Diphenylsilane of formula PhSi(OR')(IIa), a phenylsilane of formula PhSi(OR')3(IIb), or a mixture thereof, Coating with a hybrid layer by sol-gel reaction of (b2) coating the coated substrate (c2) with an inorganic metal oxide layer comprising mainly SiO2 by a sol-gel method, preferably using TEOS as a precursor material; and (d) Optionally, coating the effect pigment obtained in (c1) or (b2) with an organofunctional silane, titanate, aluminate or zirconate.

[0014] Further preferred embodiments of this method for producing coated flake-shaped metallic pigments are disclosed in claims 13 and 14.

[0015] Finally, the object of the present invention is solved by the use of the coated metallic effect pigments according to the invention in coatings, in particular in water-based coatings, printing inks, plastics or powder coatings. [Brief explanation of the drawings]

[0016] (No original text) DETAILED DESCRIPTION OF THE INVENTION

[0017] explanation: Coated flake metallic effect pigments: The coated flake-shaped metal effect pigments of the present invention comprise metal effect flakes as substrates, which are coated by the following successive coating sequence: (a) optionally, a discontinuous or continuous layer of Mo oxide; (b1) an inorganic metal oxide layer mainly containing SiO2; (c1) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane, or a mixture thereof; or (c2) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane, or a mixture thereof; (b2) an inorganic metal oxide layer containing mainly SiO2; and (d) Optionally, a further topcoat of organofunctional silane, titanate, aluminate or zirconate.

[0018] Within the present invention, when an inorganic metal oxide layer (b1) or (b2) or both containing mainly SiO21 is meant, it is usually referred to as layer (b).

[0019] When either or both of the hybrid layers (c1) or (c2) are meant, it is usually referred to as layer (c).

[0020] The flake-shaped metallic effect pigment substrate is preferably selected from aluminum, copper, zinc, zinc alloys, iron, chromium, titanium, zirconium, tin, or mixtures or alloys thereof. Preferred alloys are gold bronze or steel.

[0021] More preferred are aluminum, copper, and gold bronze, and most preferred are aluminum or aluminum alloys. Aluminum effect pigments are the most popular effect pigments in the coatings industry, exhibiting silver metallic tones in various implementations.

[0022] In certain embodiments, flake-form metal effect pigment substrates, particularly aluminum substrates, can be produced by PVD (physical vapor deposition) techniques. These metal effect pigments represent the most dazzling pigments available. However, they are currently rarely used in automotive basecoats due to serious application problems. Furthermore, although their prices have fallen over the past decade, they represent the most expensive metal effect pigments (especially aluminum effect pigments). Therefore, it is preferred to use flake-form metal effect pigments, preferably aluminum effect pigments, produced by milling techniques. Milling techniques are well known, and the Hall method (wet milling) is particularly preferred. The aluminum effect pigments can be of the "silver dollar" or "cornflake" type. Furthermore, the aluminum effect pigments can be very thin milled pigments with an average thickness comparable to that of PVD pigments, as described, for example, in EP 1621586 B1, WO 2004 / 087816 A2, or WO 2008 / 077612 A2.

[0023] The flake-shaped metallic effect pigment substrate has a D in the range of 2 to 100 μm, more preferably in the range of 5 to 60 μm, most preferably in the range of 7 to 40 μm. 50 It has a value D 50is the median value of the particle size distribution function. It indicates the size of 50% or less of the particles. These measurements are carried out, for example, by laser granulometry using a particle size analyzer manufactured by Sympatec GmbH (model: Helos / BR). The measurements are carried out according to the data provided by the manufacturer. The particles measured in this way are calculated as volume-averaged equivalent spheres according to the Fraunhofer approximation.

[0024] The thickness is the median value h 50 It can be characterized by a particle size ranging from 15 to 600 nm, preferably from 50 to 400 nm, and more preferably from 80 to 300 nm. In particular, for aluminum pigments obtained by milling techniques, h 50 The value is preferably in the range of 40 to 600 nm, more preferably in the range of 50 to 300 nm.

[0025] Thickness distribution, hence h 50 The value can be determined by AFM (atomic force microscope) or preferably by SEM as described in EP1613702B1 (paragraphs

[0124] to

[0128] ).

[0026] Flake-shaped metallic effect pigment substrates are D 50 / h 50 A metal effect pigment is called "flake-like" if its aspect ratio, defined as , is greater than 5. Preferably, the metal effect pigment has an aspect ratio in the range of 10 to 1,000, more preferably in the range of 20 to 150, and most preferably in the range of 25 to 100.

[0027] The optional layer (a) derived from molybdenum oxide may be a discontinuous or continuous layer of metal oxide.

[0028] The term "continuous layer (a)" means that layer (a) covers the respective metal substrate substantially completely, in particular completely. The term "discontinuous layer (a)" means that layer (a) only partially covers the respective metal substrate. Partial coverage means that the respective metal substrate is not completely coated. Partial coverage or discontinuity may be achieved, for example, with layer (a) in the form of islands on the respective metal substrate.

[0029] According to an embodiment of the present invention, layer (a) comprises or consists of a metal oxide selected from the group consisting of molybdenum oxide, molybdenum hydroxide, molybdenum oxide hydrate, molybdenum peroxide, and mixtures thereof. The molybdenum oxide is usually a mixture of various species, which may include coordination-type species. It can be represented by the following formula: MoOmH2O nH2O or MoO 3-m (O2) m nH2O (III) In the formula, Mo is molybdenum, O is oxygen, and 0≦m≦2 and 1≦n<2.

[0030] In addition, water, 2、 Molybdenum complexes containing various ligands selected from the group consisting of , , and mixtures thereof. All of these species are included within the term "Mo oxides" within the present invention.

[0031] Furthermore, the layers (a) may each contain elemental molybdenum in an amount of 0 to 30 atomic %, preferably 0 to 25 atomic %, most preferably 3 to 20 atomic %, based on the total content of molybdenum forming the metal oxide (a).

[0032] The amount of elemental molybdenum can be determined by XPS.

[0033] Preferably, the molybdenum oxide coat is prepared by first preparing a solution of polymolybdic acid peroxide by dissolving molybdenum oxide or elemental molybdenum in a hydrogen peroxide solution (see, e.g., Solid States Ionics, pp. 507-512, 1992).

[0034] The most important aspect of the present invention is that the metallic pigment is coated with individual layers of an inorganic metal oxide layer primarily containing SiO2, and a hybrid layer in which SiO2 is modified with diphenylsilane, phenylsilane, or a mixture thereof. Surprisingly, such coated metallic effect pigments exhibited improved gassing stability in very strong gassing tests, even after strong mechanical treatment (Waring blender test). Diphenylsilane or phenylsilane is a so-called network modifier, which means that it can covalently bond to silica via hydrolyzed SiOH (silanol) groups but does not form an organic network. The phenyl groups primarily impart hydrophobic properties to the silica network.

[0035] What is "SiO2"? 、 In the present invention, it is meant to include silica typically formed in a sol-gel process, which may contain water and may contain residual amounts of unhydrolyzed alkoxy groups.

[0036] The silica is preferably formed by the well-known sol-gel method, which consists of the steps of hydrolysis and condensation of silicon alkoxides: Hydrolysis: Si(OR)4+H2O→HO-Si(OR)3+ROH→→→"Si(OH) 4」 (IV) Condensation: “Si(OH)4” → SiO2+2H2O (V)

[0037] Species: Si(OH) 4」is used to indicate that although not present in solution, up to four hydrolysis steps are required to ultimately obtain SiO2. R is preferably methyl, ethyl, n-propyl or isopropyl, n-butyl or isobutyl, more preferably methyl or ethyl, and most preferably ethyl.

[0038] The reaction is catalyzed by base or acid. In EP 2510060 A1 it is disclosed that the catalysis can be carried out by a base-catalyzed step and an acid-catalyzed step.

[0039] Residues of such catalysts, especially basic catalysts, may remain in the silica because silica itself is acidic due to its silanol groups.

[0040] The inorganic metal oxide layer (layer b) mainly comprising SiO2 contains SiO2 in an amount ranging from more than 50 to 100% by mass, based on layer (b). Preferably, the amount of SiO2 is in the range of 75 to 100% by mass, more preferably 85 to 100% by mass, and most preferably 90 to 100% by mass, based on layer (b). Other metal oxides may be present in this layer, such as ZrO2, TiO2, Al2O3, Ce oxide, SnO2, etc. In another embodiment, layer (b) consists of SiO2.

[0041] Without being bound by theory, the inventors believe that the single inorganic metal oxide layer (b), primarily containing SiO layers, confers a certain mechanical stability to the metal effect pigment. In a preferred embodiment, this stability is achieved when the silica layer has a certain minimum thickness. Therefore, it is preferred if the average thickness of layer (b) is at least 15 nm. Mechanical stability is not achieved with an average thickness of less than 15 nm. On the other hand, the silica should not exceed a certain thickness, since otherwise the optical properties of the metal effect pigment may be distorted. Therefore, the silica layer (b) preferably has an average thickness in the range of 15 to 40 nm, more preferably in the range of 16 to 30 nm, and most preferably in the range of 17 to 25 nm.

[0042] The two different layers and their thicknesses can best be determined via TEM (transmission electron microscope) analysis of a cross-section of the coated metal effect pigment. The coated effect pigment is embedded in a hard lacquer, such as a cured epoxy binder. From this cross-section, extremely thin lamellae can be prepared using an ultramicrotome. The lamellae can be collected in water and mounted on a TEM grid. The layer thicknesses can be determined using TEM and possibly additionally EDX. For the determination of the average layer thickness, it is best to count at least 10 pigment particles.

[0043] Without being bound by theory, the inventors believe that the hybrid layer primarily improves the gassing stability of the coated metallic effect pigments.

[0044] The incorporation of diphenylsilane or phenylsilane or a mixture thereof into the silica layer (c) can be preferably achieved by using a dialkoxydiphenylsilane or trialkoxyphenylsilane. The reaction step leading to the modified silica is, for example, a transesterification step: SiO(OR)-OH+Si(OR')2Ph2→SiO(OR')-O-Si(OR')Ph2+R'-OH (VIa) or a condensation step of pre-hydrolyzed diphenylsilane: SiO(OR)-OH+Si(OH)(OR')Ph2→SiO(OR)-O-Si(OR')Ph2+H2O (VIb) This can be achieved via:

[0045] R' is independently methyl or ethyl. It is well known that organofunctional silanes modified with Si-C bonds have lower reactivity in sol-gel reactions than tetraalkoxysilanes. Therefore, to compensate for this drawback, it is preferable to form diphenylsilane in the hybrid layer (c) using diphenyldimethoxysilane, because the leaving methoxy group is known to be the most reactive group.

[0046] As outlined previously, both layers, SiO2 (b) and the hybrid layer SiO2 layer (c), are necessary for the overall coating of the metallic effect pigment. However, it is preferred to use the following variants of the successive layers: (a) optionally, a discontinuous or continuous layer of Mo oxide; (b1) a metal oxide layer containing mainly SiO2, preferably in an amount ranging from 75 to 100% by weight of SiO2 relative to layer (b); (c1) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane or a mixture thereof; (d) Optionally, a further topcoat of organofunctional silane, titanate, aluminate or zirconate.

[0047] This variant has been found to be the most stable and reproducible. Preferably, diphenylsilane is used as the network modifier.

[0048] In the case of the second variant: (a) optionally, a discontinuous or continuous layer of Mo oxide; (c2) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane, or a mixture thereof; (b2) a metal oxide layer containing mainly SiO2, preferably in an amount ranging from 75 to 100% by weight of SiO2 relative to layer (b); (d) optionally a further topcoat of organofunctional silane, titanate, aluminate or zirconate; Coatings (c2) and (b2) are preferably coated in a two-pot synthesis by separating the coated substrate from the reaction mixture after step (c2) and redispersing it in a solvent before carrying out coating step (b2) and optional step (d).

[0049] In particular, the amount of diphenylsilane in the coating relative to the total amount of Si can be measured by solid-state NMR-MAS (nuclear magnetic resonance-magic angle spinning) spectroscopy, as it is well known that it is possible to distinguish various Si species from the chemical shift of the Si atom. 29 Si NMR-MAS is a suitable tool: Q-silanes refer to species in which the Si atom is bonded only to oxygen atoms. Thus, the following species can be distinguished: 2 :O2Si(OH)2;Q 3 :O3Si(OH), and Q 4 :(O4Si). The abbreviation "Q" refers to the sum of all these species. Thus, Q-silanes represent the "SiO 2」 The chemical shifts are in the range of about -120 to -87 ppm. 29 This can be observed in the Si spectrum.

[0050] D-silane refers to a species in which two carbon atoms are bonded to a silicon atom, e.g., diphenylsilane, D 2 :O2SiPh2. These species have chemical shifts in the range of approximately -45 to -40 ppm.

[0051] In the present invention, the integral of D-silane and Q-silane 29 In the case of diphenylsilane, the signal ratio of Si NMR-MAS is preferably in the range of 1.5% to 10.5%, more preferably in the range of 1.8 to 10.0%, and most preferably in the range of 2.0 to 7.0%.

[0052] Within these ranges, an optimum ratio of diphenylsilane to silica was found for the desired properties. Thus, surprisingly, a relatively low amount of diphenylsilane relative to the total amount of silica is required for optimized properties.

[0053] For embodiments in which the optional further topcoat (d) is formed from an organofunctional silane, typically silanes with only one Si-C bond are used. These species are designated in NMR terminology as T-species, and they have a chemical shift of about -70 to -60 ppm.

[0054] In a preferred embodiment using diphenylsilane as a network modifier, such species is used in the topcoat and is a mixture of T-silane and Q-silane. 29 The signal ratio of Si NMR-MAS is in the range of 0 to 3.0%, more preferably in the range of 0.5 to 2.5%.

[0055] These rather low relative amounts of T-silanes are due to the fact that these silanes are typically used as topcoat modifiers and therefore they are only coated on top of the pigment surface and not within the hybrid layer (b).

[0056] In Figure 1, 29 Si-NMR-MAS spectra are shown for examples of the present invention together with fitting curves of the signals and quantitative analysis of the peaks.

[0057] For embodiments using phenylsilane as the network modifier, the T-silane and Q-silane 29The signal ratio of Si NMR-MAS is in the range of 3.5% to 13.5%, more preferably in the range of 4.0 to 13.0%, and most preferably in the range of 5.0 to 10.0%.

[0058] Surprisingly, it was deduced that the hybrid layer (b) does not need to contain oligomerized or polymerized organic materials as described in WO 2007 / 01795 A1 or WO 2016 / 120015 A1. The mere modification of the SiO layer with diphenylsilane appears to be sufficient to confer the desired stability to the coated metal pigment in combination with the two separate layers (b) and (c). Therefore, in a preferred embodiment, the coated metal effect pigment does not contain organic oligomers and / or organic polymers linked via a network former in the SiO layer.

[0059] The chemistry of the organic portion of the coating may further include: 13 C NMR-MAS spectroscopy. In a further embodiment, the coated metal effect pigments, when characterized by this method, exhibit a phenyl moiety attributable to the diphenyl moiety of the D-silane or the phenyl moiety of the T-silane. 13 C NMR-MAS signals attributable to the organic moieties attached to the T-silane, and optionally to the 13 These C NMR-MAS signals are shown. 13 The total amount of C-NMR signals is 13 The C signal is preferably in the range of 80% to 100%, more preferably in the range of 90% to 100%, and most preferably in the range of 95% to 100%. 13 In the range of 125 to 140 ppm of the C-NMR-MAS spectrum, a peak with two maxima at approximately 128 ppm and 134 ppm is formed, which are well known for phenyl groups.

[0060] Typical moieties of T silanes depend on the specific functional groups of these silanes but can be well assigned by one skilled in the art.

[0061] In a further preferred embodiment, the phenyl moiety of the D-silane or the phenyl moiety of the T-silane 13 The C-NMR-MAS signal alone accounts for all observed C-NMR-MAS spectra. 13 It occupies a range of 60 to 100%, more preferably a range of 70 to 100%, and most preferably a range of 75 to 95% of the C signal.

[0062] The amount of organic material in the effect pigment can also be roughly quantified by the carbon content of the whole effect pigment after pyrolysis. In preferred embodiments, the carbon content is in the range of 1.3 to 7.5% by weight; more preferably in the range of 2.0 to 5.0% by weight, each based on the total weight of the coated metal effect pigment.

[0063] In further preferred embodiments, the flake-shaped metallic effect pigments according to the invention have a total amount of SiO2 and diphenylsilane in layers (b) and (c) of at least 90%, 93%, more preferably at least 95%, 96%, 97% by weight, respectively, based on the amount of the total coating.

[0064] In a further preferred embodiment, the total coating of the flake-shaped metallic effect pigment, comprising layers (a), (b), (c), and (d), has an average thickness in the range of 30 to 60 nm, more preferably in the range of 35 to 50 nm, and most preferably in the range of 30 to 45 nm. Thus, although at least two coatings are required, the total coating thickness is rather low.

[0065] Above a total thickness of 60 nm, the optical properties of flake metal effect pigments, such as luster and flip-flop, usually become unacceptable, especially compared to pure silica-coated metal effect pigments. Below a total thickness of 30 nm, the gassing and mechanical stability are too low.

[0066] For the optional topcoat, organofunctional silanes, titanates, aluminates, or zirconates are used. This topcoat modifies the chemistry and polarity of the effect pigment surface, ensuring compatibility with the final coating binder system in terms of adhesion. Most preferred are organofunctional silanes. These organofunctional silanes may have organic moieties such as amino, hydroxy, thiol, (meth)acrylate, vinyl, epoxy, isocyanate, urethane, etc., which can chemically interact or form chemical bonds with corresponding functional groups of the binder. However, organofunctional silanes can also have hydrophobic groups to impart a controlled degree of hydrophobicity to the pigment surface.

[0067] Preferably, the top coat comprises an organofunctional silane containing an amino group and an alkyl or aryl group. Examples of aminosilanes are: Aminopropyltrimethoxysilane (Dynasylan AMMO), aminopropyltriethoxysilane (Dynasylan AMEO) or N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (Dynasylan DAMO), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (Dynasylan DAMEO), (N-ethyl gamma-aminoisobutyl)trimethoxysilane (Silquest A-Link15), 4-amino-3,3-dimethylbutyltrimethoxysilane (Silquest Y-11637), N-cyclohexylaminomethylmethyldiethoxysilane (GENIOSIL XL 924), (N-cyclohexylaminomethyl)triethoxysilane (GENIOSIL XL 926), (N-phenylaminomethyl)trimethoxysilane (GENIOSIL XL 973), and mixtures thereof.

[0068] In another preferred embodiment, the pre-condensed organofunctional silane (heteropolysiloxane) described in WO2015 / 086771A1 is used.Examples of such pre-condensed organofunctional silane are commercially available, for example, Dynasylan (trademark) Hydrosil (trademark) 2627, Dynasylan (trademark) Hydrosil (trademark) 2776, Dynasylan (trademark) Hydrosil (trademark) 2909, Dynasylan 1146 and Dynasylan (trademark) Hydrosil (trademark) 2907 (Evonik Industries AG, 45128 Essen, Germany). Preferred are water-based pre-condensed organofunctional silanes such as Dynasylan™ Hydrosil™ 2627, Dynasylan™ Hydrosil™ 2776, Dynasylan™ Hydrosil™ 2907, and Dynasylan™ Hydrosil™ 2909.

[0069] In other embodiments, no further topcoat d) is necessary, in which case it is believed that some phenyl groups of the diphenylsilane are located on the surface of the coated flake effect pigment, thus providing the preferred surface chemistry and surface properties of the effect pigment.

[0070] A highly preferred embodiment of the present invention is a coated flake-shaped metal effect pigment comprising as substrate an aluminum effect pigment obtained by milling, which substrate is coated by the following successive coating sequence: (a) optionally, a discontinuous or continuous layer of Mo oxide; (b1) a metal oxide layer mainly containing SiO2, preferably a layer consisting of SiO2; (c1) a hybrid layer comprising SiO2 modified by diphenylsilane, 29 a hybrid layer having a D / Q ratio in the range of 2.0 to 7.0 as determined by Si-NMR-MAS spectroscopy; and (d) Optionally, a further topcoat of organofunctional silane, titanate, aluminate or zirconate.

[0071] Production of flake-coated metallic effect pigments: A further embodiment of the present invention is a method for producing coated flake metallic effect pigments comprising the following steps: (a) optionally coating a metal substrate with a discontinuous or continuous layer of Mo oxide; (b) coating the metal substrate or the substrate obtained in step (a) with an inorganic metal oxide layer comprising mainly SiO2, preferably by a sol-gel method using TEOS as precursor material; (c) a tetraalkoxysilane of formula Si(OR)(I), Diphenylsilane of formula PhSi(OR')(IIa), a phenylsilane of formula PhSi(OR')3(IIb), or a mixture thereof, forming a hybrid layer by a sol-gel reaction of where R and R' are independently methyl or ethyl; or (c2) treating the metal substrate or the substrate obtained in step (a) a tetraalkoxysilane of formula Si(OR)4(I), Diphenylsilane of formula PhSi(OR')(IaI), a phenylsilane of formula PhSi(OR)3(IIb), or a mixture thereof, Coating with a hybrid layer by sol-gel reaction of (b2) coating the coated substrate (c2) with an inorganic metal oxide layer comprising mainly SiO2, preferably by a sol-gel method using TEOS as a precursor material; and (d) Optionally, coating the effect pigment obtained in (c1) or (b2) with an organofunctional silane, titanate, aluminate or zirconate.

[0072] In a preferred embodiment for step (c), the tetraalkoxysilane is tetraethoxysilane (TEOS) and the diphenylsilane is diphenyldimethoxysilane.

[0073] The reaction is catalyzed by base or acid, or it can be catalyzed by a combination of acids or bases in separate steps, as outlined in EP 2510060 A1.

[0074] Preferably, the sol-gel reaction is catalyzed by a base. Preferably, the basic catalyst is an organic base, more preferably an amine or ammonia. These may be primary, secondary, or tertiary amines.

[0075] In a further preferred embodiment, the amine has 1 to 8, particularly preferably 1 to 6, very particularly preferably 1 to 5 C atoms.

[0076] Amines with more than eight carbon atoms are often too demanding to be used as effective catalysts.

[0077] According to a preferred variant of the invention, the amine is selected from the group consisting of dimethylethanolamine (DMEA), monoethanolamine, diethanolamine, triethanolamine, ethylenediamine (EDA), t-butylamine, monoethanolamine, diethanolamine, monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, pyridine, pyridine derivatives, aniline, aniline derivatives, choline, choline derivatives, urea, urea derivatives, hydrazine derivatives, and mixtures thereof.

[0078] Particularly preferably, the basic amine catalyst used is ethylenediamine, monoethylamine, diethylamine, monomethylamine, dimethylamine, monoethanolamine, diethanolamine, trimethylamine, triethylamine or mixtures thereof.

[0079] In the case of acid catalysts, formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, maleic acid, succinic acid, anhydrides of the aforementioned acids, and mixtures thereof are preferably used, with formic acid, acetic acid or oxalic acid, and mixtures thereof being highly preferred.

[0080] In one embodiment, the method for producing the aluminum pigment of the present invention includes a step of forming a molybdenum coating on the surface of each aluminum particle by stirring a dispersion containing aluminum particles and a molybdenum compound.

[0081] The method for forming a molybdenum coating on the surface of each aluminum particle is not particularly limited, as long as the dispersion containing the aluminum particles and the molybdenum compound can be homogeneously stirred according to this method. More specifically, a method for forming a molybdenum coating on the surface of each aluminum particle can be shown by stirring or kneading a slurry or paste-like dispersion containing the aluminum particles and the molybdenum compound.

[0082] The agitator used in the step of stirring the dispersion containing aluminum particles and a molybdenum compound is not particularly limited, and any well-known agitator capable of efficiently and homogeneously stirring the dispersion containing aluminum particles and a molybdenum compound can be used. More specifically, examples include a kneader, a kneading machine, a rotary vessel agitator, a stirring reactor, a V-type agitator, a double-cone agitator, a screw mixer, a sigma mixer, a flash mixer, an airflow agitator, a ball mill, an edge runner, etc.

[0083] The molybdenum compound used in the present invention is not particularly limited, but is a well-known molybdenum compound that can form a molybdenum coating when added to a dispersion containing aluminum particles and stirred, while specific examples include polymolybdic acid peroxide, ammonium molybdate, and phosphomolybdic acid. The molybdenum compound may be used alone, or at least two of such molybdenum compounds may be mixed with each other.

[0084] Polymolybdic peroxide (generally a compound represented by the following composition formula (I)) can be easily prepared by dissolving metallic molybdenum powder or molybdenum oxide in a hydrogen peroxide solution with a concentration of 5 to 40%.

[0085] Preferably, a hydrophilic solvent is used as the solvent for the dispersion containing aluminum particles and a molybdenum compound. More specifically, methyl alcohol, ethyl alcohol, isopropyl alcohol, n-propyl alcohol, t-butyl alcohol, n-butyl alcohol, or isobutyl alcohol can be used.

[0086] In a preferred embodiment, the molybdenum compound, preferably peroxypolymolybdic acid, is first prepared separately and then added to the flake-form metal pigment used as the substrate, dispersed in a solvent that can be used in the sol-gel process step.

[0087] When forming the silica layer b), the flake-form metal effect pigment is preferably first dispersed in a solvent and optionally water. An alkoxysilane, preferably a tetraalkoxysilane, is added, and the catalyst is preferably added after dispersing the flake-form metal effect pigment in the organic solvent and, optionally, heating the dispersion to the reaction temperature. The water required for hydrolysis may already be contained in the organic solvent or may be added later.

[0088] To begin the second stage of the process of the present invention, an organic base is then typically introduced as a basic catalyst into the reaction mixture containing the metal effect pigment, the alkoxysilane, preferably a tetraalkoxysilane, and optionally water.

[0089] The silica layer may be formed by an acid-catalyzed process, or by a sol-gel process using first an acid catalyst and then a base catalyst, as described in EP 2510060 A1. Typical acids that can be used include formic acid, acetic acid, propionic acid, oxalic acid, malonic acid, and maleic acid. In another embodiment, when layer a) is formed first from molybdenum oxide, an acidic medium provided by a reagent such as peroxomolybdic acid is used as a catalytic medium for at least the first step of silica formation by the sol-gel process.

[0090] When forming the hybrid layer c), the different rates of SiO2-forming tetraalkoxysilane and diphenylsilane in the sol-gel reaction must be taken into account. Diphenylsilane is usually slower, so it is preferably added first, and the desired amount of tetraalkoxysilane is introduced into the reaction mixture at an appropriate rate to essentially compensate for the different reaction rates of the precursor materials.

[0091] For the second variant: a) optionally a discontinuous or continuous layer of Mo oxide; c2) a hybrid layer comprising SiO2 modified with diphenylsilane, phenylsilane or a mixture thereof; b2) an inorganic metal oxide layer containing mainly SiO2; d) optionally a further topcoat of organofunctional silane, titanate, aluminate or zirconate; Coatings c2) and b2) are preferably coated in a two-pot synthesis by separating the coated substrate from the reaction mixture after step c2) and redispersing it in a solvent before carrying out coating step b2) and optional step d).

[0092] Preferred organic solvents are alcohols, glycols, esters, ketones and mixtures of these solvents. Particular preference is given to using alcohols or glycols or mixtures thereof, very particular preference to using alcohols.

[0093] Suitable alcohols are preferably methanol, ethanol, isopropanol, n-propanol, t-butanol, n-butanol, isobutyl alcohol, pentanol, hexanol or mixtures thereof.

[0094] Particularly preferred is the use of ethanol and / or isopropanol.

[0095] As glycols, butyl glycol, propyl glycol, ethylene glycol or mixtures thereof are preferably used.

[0096] Preferably, the reaction mixture is reacted at a temperature ranging from 20°C to the boiling point of the particular solvent or solvent mixture. Particularly preferred is a reaction temperature ranging from 50°C to a temperature preferably 5°C below the boiling point of the respective solvent or solvent mixture. A preferred reaction temperature range is from 75°C to 82°C.

[0097] The coated flake-shaped metallic effect pigments can be used in coatings, especially water-based coatings, printing inks, plastics or powder coatings.

[0098] Particularly preferred is its use in automotive coatings. The invention further includes formulations such as lacquers, paints, printing inks, etc., containing the coated flake metallic pigments of the invention. Particularly preferred are water-based formulations, most preferably water-based automotive and industrial basecoat formulations. [Example]

[0099] example Example 1: (SiO2-+ hybrid layer) 5.0 g of molybdic acid (MoO3 *HO) was dispersed in 15 g of HO and stirred until a clear solution was obtained (approximately 1 h). In a 1 L double-jacketed reactor equipped with a thermostat, reflux condenser, and static stirrer, 250 g of Stapa™ Metallux 2156 (corresponding to 162.5 g of Al; Silver Dollar aluminum pigment paste, Eckart GmbH) was dispersed in 350 g of isopropanol. The dispersion was heated to 40°C. 0.33 g of peroxomolybdic acid solution was added along with 2.0 g of water, and the dispersion was stirred for 60 minutes. 44.5 g of tetraethoxysilane was added, and the dispersion was heated to 80°C. 6.0 g of ethylenediamine dissolved in 35 g of water was continuously charged to the mixture over 60 minutes, and the mixture was stirred for an additional 3 hours. 14.9 g of diphenyldimethoxysilane dissolved in 100 mL of isopropanol was added, followed by 47.8 g of tetraethoxysilane, which was then charged to the mixture over 1 hour. The dispersion was stirred for an additional 200 minutes, after which the reaction mixture was cooled to 40° C. and the pigment was isolated by filtration through a Buchner funnel.

[0100] Example 2: Same as Example 1, except without the molybdenum oxide pretreatment.

[0101] Comparative Example 1: According to Example 10 of EP1619222A1. 0.5 g of metallic molybdenum was dissolved in 10 g of hydrogen peroxide. 142.5 g of Stapa Metallux 2156 (equivalent to 100 g of pigment), 600.0 g of isopropanol, and the molybdenum solution were dispersed in a 1 L double-jacketed reactor equipped with a thermostat, reflux condenser, and static stirrer and heated to 50°C. The mixture was stirred for 60 minutes. The pH was adjusted to 8.6 with 3.5 g of monoethanolamine, and 30 g of tetraethoxysilane and 10 g of Dynasylan 9265 (phenyltrimethoxysilane) were added. The mixture was allowed to react for 10 hours. The dispersion was cooled to 40°C, and the coated pigment was isolated by filtration through a Buchner funnel.

[0102] Comparative Example 2: 5 g of molybdic acid was dissolved in 15 g of hydrogen peroxide until a clear solution was obtained (duration approximately 1 hour). 250 g of Stapa Metallux 2156 and 400 g of isopropanol were mixed in a double-jacketed reactor equipped with a stirrer operating at 300 rpm, a reflux condenser, and a thermostat. The temperature was maintained at 25°C, and 0.281 g of the above-prepared molybdic acid in HO solution and 30 g of water were added and stirred for 60 minutes. 42.5 g of tetraethoxysilane was added, and the reaction mixture was heated to 80°C. Stirring was continued for another 60 minutes. 13 g of phenyltriethoxysilane (Dynasylan 9265) was added continuously over 3 hours. After 30 minutes, 6.36 g of ethylenediamine in 20 g of isopropanol was added. This was repeated twice. After the final base addition, the mixture was allowed to react for 90 minutes. 8.5 g of Hydrosil 2776 was added and after 60 minutes the dispersion was cooled to 40° C. and the coated pigment was isolated by filtration.

[0103] Comparative Example 3: (No single first SiO2 layer, coating with only one hybrid layer) 5g of molybdic acid (MoO3 * HO) was dispersed in 15 g of HO and stirred until a clear solution was obtained (approximately 1 h). In a 1 L double-jacketed reactor equipped with a thermostat, reflux condenser, and static stirrer, 250 g of Stapa™ Metallux 2156 was dispersed in 350 g of isopropanol. The dispersion was heated to 40°C, and 0.33 g of peroxomolybdic acid solution was added along with 3 g of water, and the dispersion was stirred for 60 minutes. 42.5 g of tetraethoxysilane was added, and the dispersion was heated to 80°C and stirred for 60 minutes. 13.3 g of diphenyldimethoxysilane was added over 180 minutes. 6.0 g of ethylenediamine and 20 g of isopropanol were added, and the mixture was stirred for 30 minutes. The base addition was repeated two more times. After the final addition, the dispersion was stirred for 90 minutes and 8.5g of Hydrosil 2776 was added, after a further 45 minutes the reaction mixture was cooled to 40°C and the pigment was isolated by filtration through a Buchner funnel.

[0104] Comparative Example 4: Commercially available Stapa IL Hydrolan 2156. This product is a SiO2-coated aluminum flake (based on Stapa Metallux 2156) without Mo oxide pretreatment and without diphenylsilane. This product served as an internal standard, especially for hiding power testing.

[0105] Comparative Example 5a: The coating of Example 3 according to WO 2007 / 017195 A2 was applied to Stapa Metallux 2156 as substrate. Three times the amount of TEOS, water, Dynalysan MEMO, TMPTMA, and lauryl methacrylate were used, respectively, for 100 g of metal effect pigment.

[0106] Comparative Example 5b: (Prepared with reference to WO2016 / 120015A1) In a 1 L double-jacketed reactor equipped with a thermostat, reflux condenser, and static stirrer, 280 g of Stapa Metallux 2156 (corresponding to 182 g of Al pigment) was dispersed in 300 g of isopropanol. The suspension was heated to 70 °C, after which the inorganic / organic hybrid layer components (48.6 g of tetraethyl orthosilicate (TEOS), 0.82 g of Dynasylan MEMO, 3.47 g of TMPTMA, 0.61 g of allyl methacrylate, and 0.26 g of azobis(isobutyronitrile) (AIBN)) were added, followed by 3 g of acetic acid in 17 g of distilled water. After 3 hours, 9.0 g of ethylenediamine in 3.0 g of isopropanol was added. After a further 2 hours, 1.4 g of Dynasylan OCTEO and 1.8 g of Dynasylan DAMO were added, and the reaction mixture was stirred for 1 hour and then cooled. The solid is separated by filtration and collected as a paste. Example and Comparative Example 6: In this series of examples, the recipe of Example 1 was used, but the ratio of diphenylsilane to TEOS was varied while keeping the molar sum of both components constant. The exact parameters can be represented in Table 1.

[0107] [Table 1]

[0108] Example 7: (reverse layer stack, two-pot synthesis): 5.0 g of molybdic acid (MoO3 * HO) was dispersed in 15 g of HO and stirred until a clear solution was obtained (approximately 1 h). In a 1 L double-jacketed reactor equipped with a thermostat, reflux condenser, and static stirrer, 250 g of Stapa™ Metallux 2156 (corresponding to 162.5 g of Al) was dispersed in 350 g of isopropanol. The dispersion was heated to 40 °C. 0.33 g of peroxomolybdic acid solution was added along with 3.0 g of water, and the dispersion was stirred for 60 minutes. 42.5 g of TEOS was added, and the dispersion was heated to 80 °C and stirred for 1 hour. 13.28 g of diphenyldimethoxysilane dissolved in 100 mL of isopropanol was charged to the mixture within 3 hours. 18 g of ethylenediamine dissolved in 27 g of water was then added, and the reaction mixture was further stirred for 3 hours. It was then cooled to about 40° C., separated from the solvent, washed and pasted with isopropanol to a paste with a pigment content of 65% by weight.

[0109] 250 g of the received coated aluminum pigment paste was redispersed in 350 g of isopropanol. 42.5 g of TEOS was added, and the mixture was heated to 80°C with stirring. 5.0 g of water and 4.0 g of ethylenediamine dissolved in 40 g of isopropanol were added, and the mixture was stirred for an additional 5 hours. 8.5 g of Hydrosil was then added, and after 60 minutes, the dispersion was cooled to 40°C, and the coated pigment was isolated by filtration.

[0110] B Test Method: I Mechanical pretreatment: All metal effect pigments were dispersed in isopropanol to give pastes with an effect pigment content of 55% by weight. All inventive and comparative pastes were first treated in a KitchenAid for 10 minutes before further testing.

[0111] This treatment simulates the moderate shear forces typically encountered in mixer agglomerates used in the large-scale production of metallic effect pigments.

[0112] II. Gas generation test - according to WO2016 / 120015, p.72: For the rigorous gassing test, 15 g of metal pigment paste with a solids content of 55% by weight was suspended in 11.0 g of butyl glycol with a stirring time of 5 minutes. This suspension was mixed with 14.4 g of colorless binder (ZK26-6826-402, manufacturer: BASF Coatings) and 0.6 g of a 10% by weight dimethylethanolamine solution (solvent: water) and stirred for 5 minutes.

[0113] 22 g of the suspension was mixed with 195.0 g of a milky white / colorless mixed varnish for effect substance testing (ZW42-6008-0101, manufacturer: BASF Coatings), 75.6 g of a red water-based base coat color paste (ZU560-329, manufacturer: BASF Coatings, containing red iron oxide Fe2O3), and 75.6 g of a black water-based base coat color paste (ZU 425-943, manufacturer: BASF Coatings, containing black iron oxide Fe2O3). * The mixture was stirred and incorporated with 6.0 g of dimethylethanolamine (containing FeO). The pH of the suspension was then adjusted to 9.0 using a 10% by weight solution of dimethylethanolamine (solvent: water).

[0114] 265 g of the above composition was introduced into a gas-generating flask, which was then sealed in a two-chamber gas bubble counter. The gas-washing bottle was conditioned in a water bath at 40°C for 1 hour, hermetically sealed, and tested for up to 41 days. The gas volume generated was read based on the volume of water displaced in the upper chamber of the gas bubble counter. If 10 mL or less of hydrogen was generated after 41 days, the test was considered to have passed. If the sample was not stable over the entire period, the time until the sample released gas was recorded.

[0115] If this first gassing test was not passed, no further testing was performed, as passing this test is a prerequisite for the examples of the present invention.

[0116] III. Concealment: First, hiding power tests were performed to rule out any agglomerated or misoriented metal effect pigment probes.

[0117] For this test, a drawdown was carried out on a Hostaphane film (Melinex O, transparent, 175 μm) using a paste containing an amount of coated aluminum pigment corresponding to 0.65 g of pigment mixed with approximately 3 g of butyl acetate, and this paste was homogenized with the test lacquer system containing yellow iron oxide pigment. The preparation was run down onto foil using a 50 μm wire bar and allowed to dry.

[0118] The hiding power was visually evaluated according to a scoring system against a standard sample represented by Comparative Example 4 (Hydrolan 2156). If the score was at least 4 and no spots were visible, the test was passed. Standard samples usually had a hiding power scored as 3. Some of the comparative examples showed spots when applied to the substrate. These spots were due to strong agglomeration of the metallic pigments. In these cases, the Waring Blender test was marked as "fail" without further evaluation of the optics. In these cases, a second gassing test was also not performed. This is because it is well known that agglomerated metallic pigments can show relatively good gassing tests, and this result could be due to surface reduction alone or otherwise to fatal agglomeration of the pigments.

[0119] In Table 2a, the results are shown under "Hiding Power" and no further results for the Waring Blender were recorded.

[0120] IV. Intensified High Shear Test (Simulation of Circulation Line ("Waring Blender")): The same test composition as in the first gassing test I was prepared in four times the amount. This composition was sheared for 10 minutes at 20,000 revolutions per minute in a dissolver (VMA, model CA-20C, Getzmann) using a 5 cm dissolver disc. The optical properties were then evaluated in comparison with an unsheared probe. This test simulates the typical shear conditions of circulating lines used in the automotive industry. The optical properties were determined using a drawdown of this test composition using a 50 μm wire bar. The lightness L was measured using a Byk-Mac at five different observation angles: 15°, 25°, 45°, 75°, and 110°. * was measured.

[0121] The flop index according to Alman is defined in the relevant literature as follows: Flop Index = 2.69 (L * 15°-L *110°)111 / L * 45°0.86 In the formula, L * 15° is the brightness at a measurement angle close to specular reflection, and L * 45° is the brightness of the measurement angle between the angle close to specular reflection and the angle far from specular reflection, and L * 110° is the luminance at the measurement angle far from the specular reflection.

[0122] For each unsheared sample drawdown, the Δflop and ΔL for each measured angle * was evaluated and recorded in Table 2b. For the delta flop values, the test passed if Δflop was <1.0, which was usually the case.

[0123] When evaluating the optical properties, any ΔL at any of the measured observation angles of 15°, 25°, 45°, 75°, and 110° * The presence of a value >2.60 was indicated as failing the test. The angle indicates a cis configuration with respect to incident light (incident angle: 45°). The highest ΔL * If the values ​​were <2.60 and >2.20, the test was designated as "passed." * If the value was ≦2.20, the test was designated as "passed satisfactorily."

[0124] The gassing test described above was repeated on the samples after the reinforced high shear test. The entire reinforced shear test was passed only if the optical requirements were met and the second gassing test was passed. All results are reported in Table 2a, b.

[0125] [Table 2]

[0126] [Table 3]

[0127] The lack of optical results in Table 2 is due to the fact that either the first gassing test was not passed (further evaluation was stopped) or the post-shear gassing test was not passed after a very short period of a few days.

[0128] V 29 Si NMR-MAS measurement: Several samples were prepared for NMR measurements. Because the aluminum core interfered with the measurements due to the metal's diamagnetic properties, these samples were first fully oxidized. Weighted sections of the coated aluminum effect pigments were treated with a 1 M HCl solution at an elevated temperature of approximately 60°C for 48 hours to fully oxidize the aluminum core. The pigments were then separated from the solution, neutralized, washed with water, dried, and homogenized.

[0129] 29 Si NMR-MAS measurements were performed on a 300 MHz Bruker (Avance II Bruker) using a single-pulse mode with a 4.5 μs pulse length and 600 s relaxation time. Measurements were performed until a signal-to-noise ratio of at least 150 was obtained, where signals corresponding to the Q2-Q4 silane resonances in the -85 to -141 ppm region were selected as the signal, and the 40 to 0 ppm region, where no signal was observed, was selected as the noise. Powder samples were measured in 7 mm tubes at a rotation speed of 5,000 Hz, and chemical shifts were recorded relative to TMS (tetramethylsilane) as an internal standard.

[0130] The results are presented in Table 3. The NMR spectrum for Example 6b is shown in Figure 1. The intensities of the various peaks were quantitatively evaluated according to standard fitting and integration procedures for NMR spectroscopy.

[0131] [Table 4]

[0132] VI Results: From Table 2a, it can be inferred that the pigment of Comparative Example 1, which was carried out according to Example 10 of EP 1619222, did not even pass the first gassing test and was therefore not further tested. In this comparative example, phenyltriethoxysilane was used as the organically modified silane agent, but only in a single hybrid coating without a pure SiO2 coating.

[0133] Similar results were obtained for the pigments of Comparative Examples 3, 4 and 5a. Comparative Example 3 was carried out without a SiO layer, thus also showing that a single hybrid layer of SiO modified with diphenylsilane does not allow high gassing stability of aluminum effect pigments, since the moderate shear forces from the treatment with KitchenAid already appear to have damaged the coating.

[0134] This gassing test was already too strong for the standard product of Comparative Example 4 (Stapa IL Hydrolan 2156), as well as for Comparative Example 5a, which was produced according to Example 3 of WO2007 / 017195A2. According to this patent document, the coated product should have a certain gassing stability after moderate shear stress. However, the gassing test used in this disclosure was more severe than that of this patent document. Thus, Example 5b, which was produced with reference to WO2016 / 120015A2, passed the first gassing test. However, the optical properties after the reinforcement shear test were not satisfactory. Because ΔL * 25° was too high and, moreover, did not pass the gas evolution test after intensive shear treatment.

[0135] Both Comparative Examples 5a and 5b were produced according to a technique in which a hybrid layer was coated, which included a methacrylate polymer formed together with SiO2, the methacrylate polymer being bonded to the SiO2 via a methacrylate-functional silane. This technique does not appear to be suitable for enabling coated metal pigments that meet the high demands of the present invention.

[0136] Comparative Examples 2, 6e, and 6f also passed the first gassing test but failed the enhanced shear test, where Comparative Example 2 is a further variation of Comparative Example 1, which even passed the optical criteria of the enhanced shear test but failed the second gassing test.

[0137] The ΔFlop criterion was met by all tested samples, but ΔL * The baseline and secondary gassing tests were found to be more stringent. Inventive Examples 1, 2, and 6a-6d all passed the enhanced shear tests. Surprisingly, Example 7 also passed the enhanced shear tests for optical properties and gassing. In the sample of Example 7, the reverse layer sequence was applied, in which the aluminum substrate was first coated with a hybrid layer (diphenylsilane modified), followed by a SiO2 layer using a two-pot synthesis, and all tests passed.

[0138] Generally, the optical properties results were better for the layer sequence examples (Examples 1, 2, and 6a-6d) of first SiO and then hybrid layer. The best results were obtained for Examples 1, 2, and 6a-6c. Here, ΔE * The values ​​were below 2.2 for all measured angles ("good pass"). In these examples, the ratio of diphenylsilane to SiO2 was in the optimum range. In Comparative Examples 6e and 6f, the ratio of diphenylsilane to SiO2 was clearly too high. The present disclosure also encompasses the following: <Aspect 1> 1. A coated flaky metal effect pigment comprising a metal effect flake as a substrate, said substrate being coated by the following successive coating sequence: (a) optionally, a discontinuous or continuous layer of Mo oxide; (b1) Mainly SiO 2 an inorganic metal oxide layer comprising (c1) SiO modified with diphenylsilane, phenylsilane, or a mixture thereof 2 a hybrid layer comprising: or (c2) SiO modified with diphenylsilane, phenylsilane, or a mixture thereof 2 a hybrid layer comprising: (b2) Mainly SiO 2 an inorganic metal oxide layer comprising and (d) Optionally, a further topcoat of organofunctional silane, titanate, aluminate or zirconate. <Aspect 2> 2. The coated flaky metallic effect pigment according to embodiment 1, wherein the thickness of layer (b1) or (b2) is at least 15 nm. <Aspect 3> The layer (c1) or (c2) is modified with diphenylsilane, and the layer (c1) or (c2) is modified with D-silane and Q-silane. 29 3. The coated flaky metallic effect pigment according to any one of the preceding aspects, wherein the Si NMR-MAS signal ratio is in the range of 1.8% to 10.5%. <Aspect 4> T-silane and Q-silane 29 4. Coated flaky metallic effect pigments according to any one of the above embodiments 1 to 3, wherein the Si NMR-MAS signal ratio is in the range of 0 to 3.0%. <Aspect 5> 13 Characterization by C NMR-MAS spectroscopy revealed signals attributable to the diphenyl moiety of the D-silane and, optionally, to the organic moiety attached to the T-silane. 13 C NMR-MAS signals were obtained, and these 13 The total amount of C-NMR signals is 13 5. The coated flake metal effect pigment according to any one of the above embodiments 1 to 4, wherein the C signal is in the range of 80% to 100%. <Aspect 6> 6. The coated flaky metallic effect pigment according to any one of the preceding embodiments 1 to 5, wherein the diphenylsilane in the hybrid layer (c) is formed with diphenyldimethoxysilane. <Aspect 7> Mainly SiO 2 The inorganic metal oxide layer (said layer (b1) or (b2)) containing SiO in an amount of more than 50 to 100 mass % based on this layer (b1) or (b2). 2 7. The coated, flake-shaped metallic effect pigment according to any one of the preceding embodiments 1 to 6, comprising: <Aspect 8> 8. The coated flaky metallic effect pigment according to any one of the preceding embodiments 1 to 7, wherein the total thickness of the coatings (a), (b), and (c) is in the range of 30 to 60 nm. <Aspect 9> 9. The coated flaky metal effect pigment according to any one of the preceding embodiments 1 to 8, wherein the metal effect flakes are selected from the group consisting of aluminum, copper, zinc, zinc alloys, iron, chromium, titanium, zirconium, tin, or mixtures or alloys thereof. <Aspect 10> 10. The coated flaky metal effect pigment according to embodiment 9, wherein the metal effect flakes are aluminum flakes, preferably aluminum flakes produced by milling techniques. <Aspect 11> The flake-shaped metallic effect pigments comprise at least 95% by weight of SiO 2 in layers (b) and (c), based on the total coating weight. 2 11. The coated flaky metallic effect pigment according to any one of the preceding embodiments 1 to 10, having a total amount of the sum of diphenylsilane and diphenylsilane. <Aspect 12> A method for producing the coated flake metallic effect pigments according to any one of the above embodiments 1 to 11, comprising the steps of: (a) optionally coating a metal substrate with a discontinuous or continuous layer of Mo oxide; (b1) The metal substrate or the substrate obtained in step (a) is subjected to a sol-gel process, preferably using TEOS as a precursor material, to form a SiO 2 coating with an inorganic metal oxide layer comprising (c1) on the layer (b1), Formula Si(OR) 4 (I) tetraalkoxysilane, Formula Ph 2 Si(OR') 2 (IIa) diphenylsilane, Formula PhSi(OR') 3 (IIb) phenylsilane or a mixture thereof, forming a hybrid layer by a sol-gel reaction of wherein R is methyl, ethyl, n-propyl or isopropyl, n-butyl or isobutyl, and R' is independently methyl or ethyl; or (c2) treating the metal substrate or the substrate obtained in step (a) Formula Si(OR) 4 (I) tetraalkoxysilane, Formula Ph 2 Si(OR') 2 (IIa) diphenylsilane, Formula PhSi(OR') 3 (IIb) phenylsilane or a mixture thereof, Coating with a hybrid layer by a sol-gel reaction of (b2) The coated substrate (c2) is then subjected to a sol-gel process, preferably using TEOS as a precursor material, to form a layer of mainly SiO 2 coating with an inorganic metal oxide layer comprising and (d) Optionally, coating the effect pigment obtained in (c1) or (b2) with an organofunctional silane, titanate, aluminate or zirconate. <Aspect 13> 13. The method for producing a coated flaky metal effect according to claim 12, wherein in step (c1) or (c2), the tetraalkoxysilane is tetraethoxysilane (TEOS) and the diphenylsilane is diphenyldimethoxysilane. <Aspect 14> 14. The method for producing coated flaky metal effect according to claim 12 or 13, wherein the coatings (c2) and (b2) are coated in a two-pot synthesis by separating the coated substrate from the reaction mixture after step (c2) and redispersing it in a solvent before carrying out the coating step (b2) and optional step (d). <Aspect 15> 12. Use of coated metal effect pigments according to any of the above aspects 1 to 11 in a coating, in particular in a water-based coating, a printing ink, a plastic or a powder coating.

Claims

1. 1. A coated flake-like metal effect pigment comprising metal effect flakes as a substrate, the substrate is selected from aluminum or an aluminum alloy; The substrate is coated with the following sequential coating sequence: (a) optionally, a discontinuous or continuous layer of Mo oxide; (b1) Mainly SiO ２ an inorganic metal oxide layer comprising (c1) SiO modified with diphenylsilane, phenylsilane, or a mixture thereof ２ a hybrid layer comprising: or (c2) SiO modified with diphenylsilane, phenylsilane, or a mixture thereof ２ a hybrid layer comprising: (b2) Mainly SiO ２ an inorganic metal oxide layer comprising and (d) optionally, a further topcoat of organofunctional silane, titanate, aluminate or zirconate; A coated flaky metal effect pigment, wherein the layer (c1) or (c2) is modified with diphenylsilane, and the 29 Si NMR-MAS signal ratio of D-silane to Q-silane is in the range of 1.8% to 10.5%.

2. 2. Coated flaky metallic effect pigments according to claim 1, wherein the thickness of the layer (b1) or (b2) is at least 15 nm.

3. T-silane and Q-silane ２９ 3. Coated flaky metallic effect pigments according to claim 1 or 2, wherein the Si NMR-MAS signal ratio is in the range of 0 to 3.0%.

4. １３ Characterization by C NMR-MAS spectroscopy revealed signals attributable to the diphenyl moiety of the D-silane and, optionally, signals attributable to the organic moiety attached to the T-silane. １３ C NMR-MAS signals were obtained, and these １３ The total amount of C-NMR signals is １３ 3. The coated flake-shaped metallic effect pigments according to claim 1, wherein the C signal is in the range of 80% to 100%.

5. 3. Coated flaky metallic effect pigments according to claim 1 or 2, wherein the diphenylsilane in the hybrid layer (c) is formed with diphenyldimethoxysilane.

6. Mainly SiO ２ The inorganic metal oxide layer (said layer (b1) or (b2)) containing SiO in an amount ranging from more than 50 to 100 mass % based on this layer (b1) or (b2). ２ 3. The coated flake-shaped metallic effect pigment according to claim 1, comprising:

7. 3. Coated flaky metallic effect pigments according to claim 1 or 2, wherein the total thickness of the coatings (a), (b), and (c) is in the range of 30 to 60 nm.

8. 3. Coated flaky metal effect pigments according to claim 1 or 2, wherein the metal effect flakes are aluminum flakes produced by milling techniques.

9. The flake-form metallic effect pigments comprise at least 95% by weight of SiO 2 in layers (b) and (c), based on the total coating weight. ２ 3. The coated flaky metallic effect pigment according to claim 1, wherein the total amount of the sum of methylsilane and diphenylsilane is 1,2,3,4-trimethylsilane.

10. 3. A method for producing coated flake metallic effect pigments according to claim 1 or 2, comprising the following steps: (a) optionally coating a metal substrate with a discontinuous or continuous layer of Mo oxide; (b1) The metal substrate or the substrate obtained in the step (a) is subjected to a sol-gel method to form a film mainly containing SiO ２ coating with an inorganic metal oxide layer comprising (c1) on the layer (b1), Formula Si(OR) ４ (I) a tetraalkoxysilane; Formula Ph ２ Si(OR') ２ (IIa) diphenylsilane, Formula PhSi(OR') ３ (IIb) phenylsilane or a mixture thereof, forming a hybrid layer by a sol-gel reaction of wherein R is methyl, ethyl, n-propyl or isopropyl, n-butyl or isobutyl, and R' is independently methyl or ethyl; or (c2) treating the metal substrate or the substrate obtained in step (a) Formula Si(OR) ４ (I) a tetraalkoxysilane; Formula Ph ２ Si(OR') ２ (IIa) diphenylsilane, Formula PhSi(OR') ３ (IIb) phenylsilane or a mixture thereof, Coating with a hybrid layer by a sol-gel reaction of (b2) The coated substrate (c2) is treated with a sol-gel method to form a film mainly containing SiO ２ coating with an inorganic metal oxide layer comprising and (d) Optionally, coating the effect pigment obtained in (c1) or (b2) with an organofunctional silane, titanate, aluminate or zirconate.

11. 11. The method for producing coated flaky metal effects according to claim 10, wherein in step (c1) or (c2), the tetraalkoxysilane is tetraethoxysilane (TEOS) and the diphenylsilane is diphenyldimethoxysilane.

12. The steps of: (a) optionally coating a metal substrate with a discontinuous or continuous layer of Mo oxide; (c2) treating the metal substrate or the substrate obtained in step (a) a tetraalkoxysilane of formula Si(OR) 4 (I) diphenylsilane of formula Ph 2 Si(OR′) 2 (IIa), a phenylsilane of formula PhSi(OR') 3 (IIb), or a mixture thereof, Coating with a hybrid layer by a sol-gel reaction of (b2) coating the coated substrate (c2) with an inorganic metal oxide layer comprising mainly SiO2 by a sol-gel method; and (d) optionally coating the effect pigment obtained in (b2) with an organofunctional silane, titanate, aluminate or zirconate.

3. A method for producing coated flake metallic effect pigments according to claim 1 or 2, comprising: A method for producing coated flaky metal effects, wherein the coatings (c2) and (b2) are coated in a two-pot synthesis by separating the coated substrate from the reaction mixture after step (c2) and redispersing it in a solvent before carrying out the coating step (b2) and optional step (d).

13. 3. Use of the coated metal effect pigments according to claim 1 or 2 in coatings, in particular in water-based coatings, printing inks, plastics or powder coatings.

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