Medium gradation red effect pigment

Abstract

The invention relates to a medium-gradation red effect pigment with high chroma and brightness, which uses a metal as a sheet-like substrate coated with a colored absorbing layer of iron oxide or iron oxyhydroxide.

Description

TECHNICAL FIELD

[0001] The present invention relates to a mid-tone red effect pigment with high chroma and brightness, which uses a metal as flaky substrate, which is coated with a colored absorbing layer of iron oxide or iron oxyhydroxide. BACKGROUND

[0002] Background literature: Wißling et al., Metalleffekt-Pigmente, 2nd edition, 2013, Vincentz Network GmbH; WO2015040537; US20080249209; WO2013175339 Effect pigments are used in many fields, such as automotive coatings, decorative coatings, plastics, paints, printing inks and cosmetics.

[0003] The optical effect is based on the directional reflection of light on metal pigment particles or high refractive index pigment particles which are mainly platelet-shaped, oriented in parallel. Depending on the composition of the pigment platelets, interference, reflection and absorption phenomena can occur which produce angle-dependent color and brightness effects. Details are known to the skilled person and can be found, for example, in Wisssling et al., Metalleffekt-Pigmente, 2nd edition, 2013, Vincentz Network GmbH.

[0004] Metal effect pigments are made from flaky substrates such as aluminum platelets / flakes or metal oxide-coated aluminum platelets / flakes. Iron oxide-coated aluminum platelets are well known and are described, for example, in Wisssling et al., Metalleffekt-Pigmente, 2nd edition, 2013, Vincentz Network GmbH. They belong to the class of effect pigments which are widely used for coloring in coatings, paints, printing inks, plastics, ceramic compositions and glazes, and cosmetic formulations by virtue of their unique color properties.

[0005] The unique optical properties of iron oxide-coated aluminum pigments result from a combination of mirror reflection at the surface of the aluminum platelets, selective light absorption in the iron oxide layer and light interference at the film surface of the iron oxide layer. Light interference produces a color which is mainly determined by the thickness of the iron oxide coating. Thus, the pigment powder exhibits a color range from light yellow, green gold, gold, red gold, red to violet.

[0006] Iron oxide-coated metal flakes, especially aluminum-based flakes, are very bright and opaque; this is the reason why they are widely used in automotive coatings. The pigments commonly used in this field are based on aluminum platelets and exhibit a metallic mirror effect. Iron oxide-coated aluminum pigments are well known for their brilliant colors in the gold to red region.

[0007] The iron oxide layer of effect pigments can be provided on metal substrate particles by vapor-phase decomposition of volatile iron compounds in the presence of oxygen and / or water vapor (so-called chemical vapor deposition) or by wet chemical coating processes (e.g., sol-gel or precipitation processes).

[0008] EP-A-0 033 457 discloses a method for preparing colored effect pigments comprising a metal substrate whose surface is at least partially covered with iron oxide, wherein iron pentacarbonyl is oxidized to iron oxide with oxygen at above 100°C in a fluidized bed of the metal substrate. Effect pigments with bright gold to reddish gold interference colors are obtained. They exhibit, for example, a gold color with high brightness and color purity in alkyd melamine resins.

[0009] In wet chemical preparation methods, the metal oxide layer can be applied by hydrolysis of a suitable metal salt, such as an iron (III) salt like ferric chloride (III), ferric sulfate (III), or ferric nitrate (III), or a hydrolyzable organometallic compound. Details regarding the preparation of metal oxide coatings on metal substrates of effect pigments are provided, for example, in EP-A-0 708 154 or JP-A-54081337.

[0010] WO-A-2013 / 156327 relates to a wet chemical preparation process in which a hydroxyl-containing metal oxide layer initially formed on an aluminum or aluminum alloy substrate is subjected to a liquid post-treatment medium at a temperature of at least 90°C.

[0011] EP-A-1 553 144 relates to a red interference pigment based on Fe2O3 / SnO2 / [Al(P)]) obtained by a wet chemical process. This pigment exhibits higher chromaticity than pigments without a hydrated tin oxide intermediate binder layer.

[0012] WO2015 / 040537 relates to the use of aluminum-doped metal oxide layers, particularly iron oxide layers. Color and magnetic properties can be improved by adding limited amounts of other metal oxides to the metal oxide layer.

[0013] US2008 / 0249209 describes how to surface treat aluminum-based pigments using inorganic layers, mixed (inorganic-organic) layers, and pure surface-functionalized molecules. The goal is to improve the application profile of the pigments; namely, gas evolution stability and compatibility with paint systems.

[0014] Aluminum-based pigments coated with iron oxide present inherent safety challenges due to the aluminothermic reaction. Therefore, various approaches exist to improve the safe handling of this material, such as minimizing the aluminum content when processed in a dry form (US2019 / 0144679), maximizing the aluminum content (US-A-2007 / 0034112), or mixing it with non-reactive materials (WO2013 / 175339).

[0015] Aluminum flakes come in different quality grades, which can be characterized by grain size distribution (e.g., average diameter d50 and width (span) of the grain size profile), color properties (e.g., brightness and opacity), and surface area (BET). Typical values ​​for non-VMP-based aluminum flakes are given in Table 2. The basic principles of aluminum flake characterization and production can be found in Wißling et al., Metalleffekt-Pigmente, 2nd edition, 2013, Vincentz Network GmbH or Metall- und Effektpigmnte für Lacke, Eckart, 1 / January 2020.18 CO, 099113XX0. For example, they can be produced, as described in Wißling et al., Metalleffekt-Pigmente, 2nd edition, 2013, Vincentz Network GmbH, via metal sublimation on foil or via ball milling of particles.

[0016] Aluminum pigments can be characterized by surface area BET, which is measured by gas adsorption and is known to a skilled technician. BET involves the average surface area according to the formula described in US-A-2007 / 0034112 and is derived based on simple mathematical / geometric considerations. The surface area and therefore thickness of ball-milled metal sheets are characterized by their thickness distribution. In contrast, metal sheets produced by VMP have a very narrow thickness distribution. The surface area of ​​these VMP-produced sheets is primarily due to the top and bottom surfaces of the sheet; the contribution from the sides is negligible due to the high aspect ratio.

[0017] The relationship between BET and average thickness can be expressed as follows: Table 1: Theoretical relationship between average substrate thickness and surface area calculated for flakes with particle sizes of 10µm and 20µm. For example, smaller flakes with a particle size of 10µm overlap with 20µm flakes and become only slightly visible to the thicker flakes.

[0018]

[0019] Aluminum pigments produced by ball milling of particles are well known to skilled technicians (Wißling et al., Metalleffekt-Pigmente, 2nd ed., 2013, Vincentz Network GmbH). Here, the choice of aluminum particles, milling parameters, and milling balls are key variables affecting the color, brightness value, and opacity of aluminum pigments.

[0020] However, existing colored pigments have limitations in the mid-tone red region. For example, the chromaticity and / or brightness of existing pigments are insufficient for advanced applications requiring improved color performance, such as those in the automotive coatings industry. New color spaces, along with good performance properties such as hiding power, appearance, and fastness (in terms of weather resistance and moisture resistance), can be achieved with pigments possessing high hiding power, high chromaticity, and / or high brightness. Because of the commercial interest in pigments with higher brightness and hiding power in various applications, especially for coatings, there is a continuous need for improved, particularly more vibrant, red-effect pigments to expand the available color space.

[0021] Therefore, the object of the present invention is to provide a mid-tone red effect pigment with improved color properties, such as chromaticity and brightness, while maintaining good hiding power.

[0022] The brightness of a metallic flake describes its ability to reflect light. For effect pigments, it is important to select a flake that is suitable for the coating substrate and the viewing angle. The application method is also crucial.

[0023] To achieve this goal, those skilled in the art will attempt to find the best-performing aluminum grade on the market; one with very high opacity and light reflectivity (i.e., high brightness value L). Those of 15). This naturally leads to the selection of aluminum sheets with high surface area, such as those prepared by PVD process. However, skilled technicians would rule out vacuum metallized pigments (VMP) because they are difficult to process and not very stable (EP 2 820 089 B1).

[0024] Table 2: Values ​​of surface area BET, grain size distribution, and color performance of non-VMP-based aluminum sheets used in the examples and comparative examples of the invention.

[0025] 1 Ultrasonic measurement at 30% power output

[0026] Table 2 shows typical values ​​for the surface area BET, grain size distribution, and color values ​​(hue, chromaticity, brightness, and hiding power (∑dE)) of non-VMP-based aluminum flakes. Typical brightness values ​​for non-VMP-based aluminum flakes range from 150 to approximately 170 luminance (L). Within 15 points.

[0027] The relationship between average thickness and hiding power can be seen in Table 1. As shown, the hiding power per 1g pigment / m² decreases significantly with increasing average thickness of the sheet. Therefore, based on conventional knowledge, skilled technicians typically use the thinnest available metal sheet with the highest surface area to improve the hiding power of pigments.

[0028] To obtain better effect pigments (including the best hiding power) in the mid-red range, skilled artisans typically use VMP metal flakes as the raw material for novel effect pigments because they exhibit the highest hiding power per g pigment / m², as shown in Table 1. Considering the simple preparation process and the brittleness of untreated or coated flakes, skilled artisans would prefer the less desirable option—very thin aluminum flakes produced by ball milling, which are readily available and mechanically stable in process and application testing. Therefore, skilled artisans would use very thin flakes with high surface area aluminum (e.g., > 6 m² / g) produced by classic ball milling to obtain the desired mid-red range with high brightness factor and hiding power.

[0029] Surprisingly and contrary to common sense, the inventors discovered that good opacity and excellent color performance in the mid-tone red region are possible with aluminum flakes exhibiting a surface area of ​​< 6 m² / g, narrow particle size profile, good opacity, and high brightness when coated with passivation and absorption layers such as Fe2O3.

[0030] Another object of the present invention is to provide a pigment composition comprising mid-tone red effect pigments, which has improved color performance (such as chromaticity and brightness) compared to conventional pigments, while maintaining good hiding power in coating applications, especially in orange to red hue coatings and preferably in automotive coatings.

[0031] Any reference or designation of any document in this application is not an admission that such document represents prior art of the present invention. Detailed Implementation

[0032] This invention relates to a mid-tone red effect pigment with high chromaticity and brightness at a 15° angle, which uses a sheet-like metal substrate coated with a colored absorption layer containing iron oxide and / or iron hydroxyl oxide (this may also include other elements found in the iron oxide layer, such as Mn, Si, Al, Ni, etc.). Optionally, the mid-tone red effect pigment may include a passivation layer between the metal substrate and the colored absorption layer.

[0033] Surprisingly, the lightness factor (BF) was found to be even higher with fairly and very good hiding power, given the thicker aluminum sheet and therefore the higher metal content in the final pigment, which contradicts the conventional thinking of skilled technicians.

[0034] Therefore, the present invention describes a mid-tone red effect pigment, comprising: - h15 is 25°≤h15≤49°, preferably 28°≤h15≤45°.

[0035] - Color distribution range (C Distribution range) ≥ 60.

[0036] - Luminance distribution range (L) Distribution range) ≥90.

[0037] - The luminance factor (BF) is ≥140, more preferably ≥145, and most preferably ≥150. In one embodiment, the BF is 140-165, 145-165, or 150-165.

[0038] - Covering power (∑dE) < 110.

[0039] - The aluminum content calculated in dry pigments and other components calculated as oxides are ≥26% by weight, with an upper limit of 60% by weight.

[0040] - SiO2 content ≤ 10% by weight.

[0041] - Applications of aluminum sheets with the following combinations of properties: o Surface area (BET) ≤ 4m² / g o The width (span) of the particle size curve is ≤1.2 o Covering power ∑dE < 20 o Brightness L 15 > 153.

[0042] Additionally, the present invention relates to a method for manufacturing the mid-tone red effect pigment.

[0043] Furthermore, the present invention relates to the use of the aforementioned mid-tone red effect pigment in coloring compositions such as paints, printing inks, varnishes, plastics, fibers, films, or cosmetic formulations. In another embodiment, the mid-tone red effect pigment can be used to color automotive, architectural, and industrial coating compositions.

[0044] The term "mid-tone red effect pigment" refers to an effect pigment with a reddish-orange color between 25° ≤ h15 ≤ 45°, associated with the scraping method described in the Test Methods section below. The terms "flake" or "plate" refer to substrates with an aspect ratio of 10:1 or higher.

[0045] Color can be described using different color space systems. The color data C used in this article... (chromaticity), h (hue angle), L (brightness), a (red and green axes) and b The (yellow-blue axis) should be understood as defined in the CIELAB color measurement system (as specified by the Commission Internationale de l'Eclairage). For example, regarding point A in the CIELAB color space, it is defined by three coordinates L... a and b Definition. CIELAB coordinates a and b It can also be done using cylindrical coordinates C, as is known to those skilled in the art. And h represents.

[0046] Metal oxide coating pigments are described not only by a single color factor, but also by the range of lightness and chromaticity distributions between the face angle and downflop, the latter two being defined here as: Color distribution range (C Distribution range): C 15 minus C 110.

[0047] Brightness distribution range (L) Distribution range): L 15 minus L 110.

[0048] C 15. C 110, L 15. L The 110 value was measured using a BYK-mac i Sensor 23mm, Illum. D65 10° device, while the color was applied using the scraping method described above.

[0049] The objective of this invention is to provide a high frontal absolute chromaticity (C) 15) High absolute brightness at the front angle (L) 15) Mid-range red pigments with high chromaticity and high brightness distribution ranges. Since both chromaticity and brightness contribute to the optical differentiation of pigments, they can be combined into a single factor called the brightness factor (BF), as shown in the following equation, which is defined as the sum of the chromaticity and brightness distribution ranges: Luminance factor (BF) = Chromaticity distribution range + Luminance distribution range.

[0050] An additional objective of this invention is to maximize the brightness factor (BF).

[0051] Another objective of the present invention is to maintain the hiding power below ∑dE=110, which is preferred in automotive coatings.

[0052] The metal substrate can be a wide range of metals used in the field of effect pigments. The metal substrate is typically in the form of a sheet or flake. The metal substrate can be selected from aluminum, steel, silver, copper, gold bronze (brass), zinc, zirconium, tin, titanium, their alloys, and combinations thereof. The preferred metal substrate is aluminum-based, iron, copper, or gold bronze.

[0053] More preferably, the metal substrate is an aluminum-based substrate. Suitable aluminum-based substrate particles are generally known to those skilled in the art. The aluminum-based substrate particles can be made from an aluminum core or an aluminum alloy core that may be at least partially coated with one or more passivation layers.

[0054] Aluminum or aluminum alloy flakes or sheets can be obtained using conventional atomization and grinding techniques. Suitable aluminum or aluminum alloy flakes are produced, for example, by the Hall process through wet milling in petroleum solvent oil. The raw material is atomized irregular aluminum sand, which is ball-milled into flake particles in petroleum solvent oil in the presence of a lubricant and subsequently classified. Dry milling of aluminum powder is also possible.

[0055] The metal substrate is more preferably aluminum. The aluminum substrate may be of the "cornflake" type, "silver coin" type, or even "platinum coin" type, depending on the quality and shape of the starting particles and the grinding conditions.

[0056] Although the surface area of ​​the product is defined and the description refers to the average thickness of a large number of sheets, the individual thickness of each aluminum sheet can be variable and can be determined by cross-sectional TEM / SEM. The geometric thickness of the metal sheet, especially the aluminum-based sheet, can typically be in the range of 10-1500 nm, preferably 10-1000 nm, more preferably 20-800 nm, and most preferably 20-700 nm.

[0057] The average diameter of the sheet-like material, especially aluminum or aluminum alloy sheets, can range from 3 to 100 µm, preferably 5 to 50 µm. The aspect ratio of the average diameter to the average thickness is typically in the range of 10:1 to 1000:1. The diameter can be determined by laser scattering dimensional analysis.

[0058] As described above, the aluminum or aluminum alloy core of the aluminum-based substrate particles may be at least partially coated with one or more passivation layers, for example, completely coated with one or more passivation layers. Preferably, the one or more passivation layers completely cover the aluminum substrate sheet, including the sides.

[0059] Suitable passivation layers are generally known to those skilled in the art. The passivation layer is preferably an inorganic layer, such as a metal phosphate layer or an inorganic oxide layer. If the inorganic passivation layer is a metal phosphate layer, the metal can be selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Nb, Mo, Ta, or W. If the inorganic passivation layer is an inorganic oxide layer, the oxide can be selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Nb, Mo, Ta, W, Ge, Si, Sn, and Bi oxides, or any combination thereof.

[0060] Preferably, the passivation layer is a metal phosphate layer, a silicon dioxide layer, an aluminum oxide layer, a hydrated aluminum oxide (AlOOH) layer, or a combination thereof. More preferably, the passivation layer is a silicon dioxide layer and an aluminum oxide layer.

[0061] According to a preferred aspect, the present invention relates to a mid-tone red effect pigment, wherein the effect pigment comprises an aluminum substrate passivated by a layer of metal phosphate, silicon dioxide, aluminum oxide, hydrated aluminum oxide or a combination thereof.

[0062] According to the invention, an iron oxide layer is applied to an optionally passivated sheet metal substrate, preferably an optionally passivated aluminum-based sheet substrate. This iron oxide layer can be produced by a wet chemical method as described below. Typically, a wet chemical coating process is performed until the desired interference color is obtained. Heat treatment converts the hydroxyl-containing iron oxide layer into an Fe2O3-containing layer. After heat treatment, the desired final hue h15 is 25° ≤ h15 ≤ 49°, preferably 28° ≤ h15 ≤ 45°.

[0063] Preferably, the passivated metal sheet substrate is completely encapsulated by the iron oxide layer.

[0064] For example, the geometric thickness of this iron oxide coating, which can be obtained through a wet chemical process, is typically about 120-500 nm, preferably 130-450 nm, and more preferably 150-350 nm. The geometric layer thickness can be determined based on TEM micrographs (cross-section).

[0065] To obtain the desired effect pigment, different layers, such as silicon oxide or iron oxide, can be applied. Preferably, the mid-tone red effect pigment has only one iron oxide layer. More preferably, the mid-tone red effect pigment does not have other metal oxide layers with high refractive indices.

[0066] The iron oxide layer may contain up to 20% by weight of other metals, such as aluminum, silicon, or zirconium, based on the total amount of iron metal atoms in the iron oxide layer. The concentration of doped metals in the iron oxide layer can be determined by TEM combined with EDXS (energy-dispersive X-ray spectroscopy), for example as described in WO-2015 / 040537.

[0067] Preferably, the iron oxide layer may be doped with up to 10% by weight of aluminum, based on the total amount of iron and aluminum atoms in the aluminum-doped iron oxide layer. Preferably, the aluminum-doped iron oxide layer contains 0.05-10% by weight, 0.5-8% by weight, or 0.5-6% by weight of Al, based on the total amount of Fe and Al in the Al-doped iron oxide layer.

[0068] The Al concentration in the adjacent substrate portion of the Al-doped iron oxide layer is typically higher than the Al concentration in the portion of the Al-doped iron oxide layer farther from the substrate.

[0069] In another embodiment, the iron oxide layer may contain other elements besides aluminum, such as silicon. This can be incorporated during the iron hydroxyl oxide coating step or in a later stage. Preferably, the iron oxide layer may be doped with up to 15% by weight of silicon based on the total amount of iron atoms in the iron oxide layer. Preferably, the iron oxide layer contains 0.05-15% by weight, 0.5-10% by weight, or 0.8-8% by weight of Si based on the total amount of Fe and Si atoms in the iron oxide layer.

[0070] In this invention, the iron oxide layer may represent the outermost layer of the mid-tone red effect pigment. Alternatively, one or more additional layers, such as a SiO2 layer, a polymer layer, an organosilane layer, or any combination thereof, may be applied to the iron oxide layer.

[0071] The geometric thickness of the final layer can be from 2 nm to about 50 nm, preferably 2-30 nm, and more preferably 2-20 nm, depending on the type of surface modification.

[0072] In a preferred embodiment, the mid-tone red effect pigment contains a final layer selected from SiO2 layers, polymer layers, organosilane layers, or combinations thereof. The term "final layer" is synonymous with "outermost layer." This surface modification is typically tailored to a specific end use. Using this final layer allows adjustment of the surface polarity of the mid-tone red effect pigment, which in turn improves the bonding of the effect pigment with base systems such as paints or inks.

[0073] Methods for surface modification of effect pigments and suitable surface modifiers, such as silanes with surface-reactive functional groups (e.g., alkoxysilanes), are known to those skilled in the art and can improve the compatibility of the effect pigment with varnishes or paints. Surface modification methods and surface modifiers are described, for example, in EP-A-1682622, EP-A-1904587, WO-A-99 / 57204, EP-A-1812519, or EP-A-0688833.

[0074] This mid-tone red effect pigment can be manufactured by coating an optionally passivated sheet metal substrate with a wet chemical method of hydrolysis and decomposition of iron(III) salts in a liquid medium.

[0075] Therefore, another aspect of the present invention relates to a method for manufacturing a mid-tone red effect pigment as described in any aspect herein, the method comprising: (a) Provides an optional passivated sheet-like metal substrate, and (b) The substrate is coated in a liquid medium containing an iron oxide precursor compound.

[0076] Preferably, the mid-tone red effect pigment obtained by or that can be obtained by the method of the present invention corresponds to the mid-tone red effect pigment described herein.

[0077] Methods for preparing passivation layers on metal substrates such as aluminum sheets are generally known to skilled technicians.

[0078] The term "iron oxide" as used herein specifically refers to α-iron oxide (III). However, the term "iron oxide" also includes α-iron oxide (III) and small amounts of γ-iron oxide (III), magnetite (Fe3O4), hydrated iron oxide, or ferric hydroxide (e.g., FeO(OH), Fe2O3). H2O, Fe2O3 with n ≥ 2 A mixture of (n H2O, Fe(OH)3, Fe(OH)2, or a mixture of two or more of these containing hydroxyl iron oxides). Preferably, the Fe atoms are present as Fe(III). However, in this invention, the Fe atoms may also be present as Fe(II). Preferably, the iron oxide layer comprises Fe2O3.

[0079] As aluminum metal reacts rapidly with air, a thin layer of aluminum oxide is formed. This process is called self-passivation and produces a thin layer of aluminum oxide (Al₂O₃) on the metal.

[0080] The terms “mixtures thereof” or “combinations thereof” refer to any possible physical blends or combinations of two or more components mentioned in the corresponding enumeration of the same or different kinds of components.

[0081] Layer thickness is typically determined by transmission electron microscopy (TEM) or scanning electron microscopy (SEM) performed on cross sections of approximately 10–50 flakes. As described in US 11,292,917 B2, a thin film containing a coating of neatly arranged flakes is cut and analyzed by SEM or TEM, where the geometric thickness values ​​of approximately 10–50 flakes are studied and statistically averaged. It is preferred to measure more than 20 distinct points to obtain an average. Depending on the desired process, different layer thicknesses may be required. Mid-tone red pigments from chemical vapor deposition processes are known to have layers of approximately 120 nm (Ostertag, W. (1994), Effektpigmente. Nachr. Chem. Tech. Lab., 42: 849–854, https: / / doi.org / 10.1002 / nadc.19940420907), while wet chemical layers contain thicker layers to achieve this color space.

[0082] In wet chemical processes, suitable precursor compounds, such as organosilicon and / or aluminum compounds in which organic groups are bonded to metals via oxygen atoms, are typically hydrolyzed in the presence of substrate particles (e.g., aluminum flakes or sheets) and the metal compound in an organic solvent in which they are soluble. Preferably, the metal alkoxide (especially tetraethoxysilane and aluminum triisopropoxide) is hydrolyzed with water in the presence of an alcohol (e.g., ethanol or 2-propanol) and a basic and / or acid catalyst. The basic catalyst is, for example, ammonia and / or amines, and the acid catalyst can be, for example, phosphoric acid or an organic acid such as acetic acid or oxalic acid. This is preferably carried out by first adding the substrate particles, ethanol, water, and ammonia, heating the mixture to 40-90°C with stirring, and continuously adding the metal alkoxide solution in ethanol and water or ammonia. After a subsequent stirring time, typically 1-15 hours, the mixture is cooled to room temperature, and the coating pigment is separated by filtration, washed, and optionally dried. Further details regarding methods for preparing passivation layers on aluminum are provided, for example, in EP-A-0 708 154, DE-A-44 05 492 or WO-A-2011 / 95341.

[0083] This iron oxide layer is typically prepared by wet chemical methods, such as hydrolysis of a suitable iron oxide precursor compound. The coating process is usually carried out until the desired interference color is obtained. Heat treatment converts the hydroxyl-containing iron oxide layer into an Fe₂O₃-containing layer, preferably a hematite layer.

[0084] As shown above, the substrate is coated in a liquid medium containing an iron oxide precursor compound. This liquid medium is typically an aqueous medium, which usually contains water in an amount of 10-100% by weight or 30-100% by weight based on the total liquid volume in the aqueous medium.

[0085] Iron oxide precursor compounds that can be used to provide an iron oxide layer via wet chemical processes are generally known to those skilled in the art. Exemplary iron oxide precursor compounds include iron salts such as iron(III) halides (e.g., FeCl3), iron(III) nitrate, iron(III) sulfate, hydrolyzable iron compounds such as iron alkoxides, iron coordination compounds such as iron acetylacetonate, or any combination or mixture thereof.

[0086] The iron oxide layer can, in principle, be applied to the substrate at either an acidic or alkaline pH. Preferably, the liquid medium has a pH of 5 or less, more preferably 4-2. Preferably, the pH of the aqueous medium is kept constant while the iron oxide layer or the Al-doped iron oxide layer is applied to the substrate. The temperature can vary over a wide range, such as at least 20-100°C.

[0087] Preferably, the resulting pigment is then subjected to a heat treatment step, such as drying the pigment and / or further condensation in the iron oxide layer. This heat treatment step can be carried out by calcination at about 250-450°C, preferably 280-400°C, for at least 5 minutes, for example, calcination for about 10-60 minutes. Alternatively, the resulting effect pigment can be subjected to a medium containing one or more high-boiling-point solvents and heated at a temperature of at least 90°C for at least 0.5 hours.

[0088] High-boiling-point solvents typically have a boiling point of 90-400°C, more preferably 100-300°C. Examples include monohydroxy alcohols, glycols or polyols, glycol ethers, polyethylene glycol ethers, polyethylene glycol monoethyl ethers, polypropylene glycol, aldehydes, esters, carbonates, organic acids, amides, lactams such as NMP, ketones, ethers, alkanes, halogenated alkanes, aromatic compounds, liquid polymers, mineral oils, or mixtures thereof.

[0089] This mid-tone red effect pigment is typically separated by known methods, such as filtration or by heat treatment (and if possible, a combination of both), and used as a paste.

[0090] Therefore, in another aspect, the present invention relates to a mid-tone red effect pigment as defined herein, obtainable by a method comprising: (a) Provides an optional passivated sheet-like metal substrate, and (b) The substrate is coated in a liquid medium containing an iron oxide precursor compound.

[0091] For various applications, this mid-tone red effect pigment can be suitably used in blends with any other pigment, preferably a colored absorbing pigment, and optionally a conventional effect pigment other than the mid-tone red effect pigment of this invention, to provide pigment combinations.

[0092] The pigment composition of the present invention consists of at least two or three components, wherein the effect pigment (a) is a mid-tone red effect pigment as defined herein, the second pigment (b) is at least one colored absorbing pigment, and the optional third pigment (c) is another effect pigment.

[0093] Pigment (b) can typically be at least one non-effect pigment or a white pigment. Pigment (b) can be any pigment of any hue, preferably a pigment with a yellow or red hue or a green hue. This effect can also be achieved by combining it with other colored pigments such as black or brown pigments.

[0094] Preferred colored absorbing pigments (b) are, depending on the application, preferably any transparent colored absorbing pigment with a desired color gradation ranging from green to yellow to purple or even blue for the desired coating. Combinations with other colored pigments such as black or brown pigments, such as transparent carbon black pigments or transparent black perylene pigments, are also possible.

[0095] The term "transparent pigment" as used in this article refers to a pigment that provides a coating that is substantially transparent in the 400-700 nm range, with no significant radiation scattering at these wavelengths.

[0096] Pigment (b) may be an organic pigment, an inorganic pigment, or a mixture thereof. Preferably, pigment (b) has a hue suitable for blending the effect pigments of the present invention, such as a yellow, a red hue, or a green hue.

[0097] Therefore, in a preferred aspect, pigment (b) is at least one transparent pigment, particularly selected from organic pigments, inorganic pigments and mixtures thereof.

[0098] Organic colored absorbent pigments suitable for the pigment compositions of this invention typically comprise organic colored and black pigments. Suitable examples include those selected from monoazo, diazo, diazo condensation, anthraquinone, anthraquinone, anthraquinone, anthraquinone, benzimidazolone, quinacridone, quinoline ketone, diketopyrrolopyrrolo, dithioketonepyrrolopyrrolo, and di... Azides, flavanones, indanone, isoindoline, isoindolineone, isoviolanthrone, metal complexes, violanthone, perylene, phthalocyanine, pinanthrone, pyrazoloquinazolinone, indigo, thioindigo, triarylcarbon Pigments and their mixtures, including their solid solutions or mixed crystals.

[0099] Suitable examples include the following: Monoazo pigments: CI pigment yellow 1, 3, 62, 65, 73, 74, 97, 183 and 191; CI pigment orange 5, 38 and 64; CI pigment red 1, 2, 3, 4, 5, 23, 48:1, 48:2, 48:3, 48:4, 49, 49:1, 51, 51:1, 52:1, 52:2, 53, 53:1, 53:3, 57:1, 58:2, 58:4, 63, 112, 146, 148, 170, 184, 187, 191:1, 210, 245, 247 and 251; Diazo pigments: CI Pigment Yellow 12, 13, 14, 16, 17, 81, 83, 106, 113, 126, 127, 155, 170, 174, 176 and 188; CI Pigment Orange 16, 34 and 44; Diazo condensation pigments: CI pigment yellow 93, 95 and 128; CI pigment red 144, 166, 214, 220, 221, 242 and 262; CI pigment brown 23 and 41; Anthraquinone pigment: CI Pigment Red 168; Anthraquinone pigments: CI pigments Yellow 147 and 199; CI pigment Red 177; Anthraphenidine Pigment: CI Pigment Yellow 108; Benzimidazole pigments: CI pigment yellow 120, 151, 154, 180, 181; CI pigment orange 36 and 72; CI pigment red 175, 185, 208; CI pigment purple 32; CI pigment brown 25; Quinacridone pigments: CI pigments Orange 48 and 49; CI pigments Red 122, 202, 206 and 209; CI pigment Violet 19; Quinoline pigment: CI Pigment Yellow 138; Diketolpyrrolopyrrole pigments: CI Pigment Orange 71, 73 and 81; CI Pigment Red 254, 255, 264, 270 and 272; two Azine pigments: CI pigments Violet 23 and 37; Flavanistone pigment: CI Pigment Yellow 24; Indanthone pigments: CI Pigment Blue 60 and 64; Isoindoline pigments: CI pigment yellow 139 and 185; CI pigment orange 61 and 69; CI pigment red 260; Isoindolinone pigments: Isoindolinone pigments: CI Pigment Yellow 109, 110 and 173; Pigment Orange 61; Isoviolet anthrone pigment: CI pigment violet 31; Metal complex pigments: CI pigment red 257; CI pigment yellows 117, 129, 150, 153 and 177; CI pigment green 8; Violet cyclohexanone pigments: CI pigment orange 43; CI pigment red 194; Perylene pigments: CI pigments Red 123, 149, 178, 179 and 224; CI pigment Violet 29; Phthalocyanine pigments: CI Pigment Blue 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16; CI Pigment Green 7, 36; Piperanthones pigments: CI pigment orange 51; CI pigment red 216; Pyrazoloquinazolinone pigments: CI Pigment Orange 67 and CI Pigment Red 216; Indigo pigment: CI Pigment Red 282; Indigo and sulfur pigments: CI pigments Red 88 and 181; CI pigment Violet 38; Triarylcarbon Pigments: CI Pigment Red 81, 81:1 and 169; CI Pigment Violet 1, 2, 3 and 27; CI Pigment Blue 1, 61 and 62; CI Pigment Green 1; CI Pigment Yellow 101 (Aldazin Yellow); CI Pigment Brown 22.

[0100] Preferably, the organic pigment is a yellow to red, green or blue organic pigment, such as yellow, green, blue, red or orange organic pigments, i.e. CI pigment green, CI pigment yellow, CI pigment red or CI pigment orange, selected from anthraquinone, diketopyrrolopyrrole, isoindolineone, metal complex, violet ketone, perylene, phthalocyanine pigment, indigo pigment or any mixture thereof, including solid solutions or mixed crystals.

[0101] Especially preferred are CI pigment yellow 129, pigment yellow 110, pigment red 168, pigment red 177, pigment red 179, pigment red 282 and any diketolpyrrolopyrrole pigment such as pigment orange 71, pigment orange 73, pigment red 254, pigment red 255, pigment red 264, pigment red 272 or pigment red 291.

[0102] Suitable organic pigments, such as those marketed as Irgazin ® Cosmoray Orange L 2950, ​​Irgazin ® Rubine L 4025, Irgazin ® Rubine L 4030, Irgazin ® Orange L2990 HD or D 2905, Irgazin ® Red L 3630, Irgazin ® Yellow L 2040, Irgazin ® Yellow L 0800, Paliogen ® Red L3885,Paliogen Red L 3920,Heliogen ® Blue L 6950 or Heliogen Green L 9361 are available commercially.

[0103] Suitable inorganic pigments can be transparent iron oxide yellow pigment (CI Pigment Yellow 42), transparent iron oxide red pigment (CI Pigment Red 101), or mixtures thereof.

[0104] Suitable inorganic black or brown pigments can be carbon black (CI Pigment Black 7), graphite (CI Pigment Black 10), or ferrochromium oxide (CI Pigment Brown 29).

[0105] Suitable inorganic pigments, such as those branded Sicotrans ® Commercially available.

[0106] The colored absorbing pigment (b) is preferably transparent.

[0107] The effect pigment (c) can be any conventional effect pigment known in the art. The effect pigment (c) can be a metallic pigment such as aluminum flakes or an effect pigment based on a transparent substrate (such as natural mica, synthetic mica, or glass flakes). The transparent substrate is typically coated with one or more layers of metal oxides such as TiO2, TiO2 (doped with SnO2), SiO2, and / or Fe2O3, etc. Pigments that reflect gold to red light due to interference and absorption phenomena of the thin film are preferred. Therefore, the metallic mid-tone red luster of the opaque mid-tone red effect pigment of the present invention can be modified with a particularly translucent pigment of the same color. The color effect is a (two-dimensional) metallic luster enriched in the third dimension, possessing a so-called depth.

[0108] Suitable effect pigments (c) such as those under the trademark Lumina ® or Mearlin ® Commercially available.

[0109] The weight ratio of the mid-tone red effect pigment (a) to the colored absorbing pigment (b) and optional effect pigment (c) can vary over a wide range.

[0110] In another aspect, the present invention relates to a pigment composition comprising: (a) A mid-tone red effect pigment comprising an optionally passivated flake metal substrate and an iron oxide layer, wherein the effect pigment has a hue angle h15 of 25° ≤ h15 ≤ 45°. (b) Colored absorbing pigments, and (c) Optionally, other effect pigments; The weight ratio of the gold effect pigment (a) to pigments (b) and (c) is 95:5-5:95, preferably 80:20-5:95, and more preferably 75:25-20:80.

[0111] The weight ratio of the mid-tone red effect pigment (a) to pigment (b) and optional pigment (c) is, for example, 95:5, meaning that 95% by weight corresponds to the mid-tone red effect pigment and 5% by weight corresponds to the combination of pigments (b) and (c). The weight ratio of pigment (b) to pigment (c) can be 100:0 to 50:50, preferably 75:25 to 60:40.

[0112] The preferred pigment (b) is a transparent pigment, especially selected from organic pigments, inorganic pigments and mixtures thereof.

[0113] The organic pigment is particularly a red-phase organic pigment, such as a red, green, or blue organic pigment, selected from anthraquinone, diketopyrrolopyrrole, isoindolineone, metal complexes, violet ketones, perylene, phthalocyanine, indigo pigments, or any mixture thereof, including solid solutions or mixed crystals.

[0114] The inorganic pigment may be transparent iron oxide yellow pigment (CI pigment yellow 42), transparent iron oxide red pigment (CI pigment red 101), or a mixture thereof.

[0115] Pigment (c) may be an effect pigment selected from metallic pigments, or an effect pigment based on a transparent substrate selected from natural mica, synthetic mica, or glass. Preferably, pigment (c) comprises a flake-like substrate selected from natural mica, synthetic mica, or glass, coated with one or more layers of a metal oxide selected from TiO2, TiO2 (doped with SnO2), SiO2, and / or Fe2O3.

[0116] Metallic pigments can be aluminum-based flakes, preferably aluminum flakes.

[0117] The mid-tone red effect pigment (a) can be incorporated into the application system in a conventional manner, such as as a paste or slurry.

[0118] Therefore, the present invention provides a composition comprising the mid-tone red effect pigment.

[0119] The pigment combination can be incorporated into the application system in a conventional manner. The mid-tone red effect pigment (a) as defined herein, and optional effect pigments (c), can be added as a slurry. Pigment (b) is typically added in a pre-dispersed state.

[0120] The effect pigments or pigment combinations of the present invention are highly suitable for all pigment end applications, especially for coloring organic or inorganic materials of natural and synthetic origin, such as...

[0121] a) Used for large-scale coloring of polymers, such as those in the form of resins, rubbers, or plastics, including films and fibers; b) Used in the preparation of paints, paint systems, and coating compositions, such as in automotive, architectural, and industrial coating compositions. c) Used in inks, printing inks, such as digital printing such as inkjet printing, and toners used in electrophotography, such as those used in laser printers; d) As a coloring agent, such as an additive for pigments and dyes; e) Used in cosmetic formulations; etc.

[0122] The paint is a water-based or solvent-based coating in which the pigment combination of the present invention can be used. The organic film-forming base materials that can be used include all base materials commonly used in the coatings industry. More specifically, examples of base materials that can be colored with gold-effect pigments or pigment combinations as defined herein include: Oil-based materials (based on linseed oil or polyurethane oil), Cellulose-based materials (NC, CAB, CAP), Materials based on chlorinated rubber, Vinyl materials (based on PVC, PVDF, VC copolymers, polyvinyl acetate, polyvinyl ester dispersions, polyvinyl alcohol, polyvinyl acetal, polyvinyl ether, polystyrene, and styrene copolymers), Acrylic materials Alkyd materials, Saturated polyester materials Unsaturated polyester materials Polyurethane materials (single-component, two-component), Epoxy materials Polysiloxane materials.

[0123] These systems are described in detail in D. Stoye, W. Freitag, Paints, Coatings and Solvents, 2nd ed., 1998, Wiley-VCH.

[0124] The medium-tone red effect pigment or the pigment combination of the present invention is preferably used in water-based and solvent-based coating applications, more preferably in decorative coating compositions such as architectural, automotive or industrial coating compositions, for example in any consumer products.

[0125] The mid-tone red effect pigment or the pigment combination of this invention is typically incorporated into its corresponding application medium in a conventional manner. Articles can then be coated with these thus-colored application media. Such articles may include, for example, vehicle bodies, industrial equipment, architectural finishing components, etc.

[0126] In the case of plastics, the mid-tone red effect pigment or the pigment combination of the present invention can also be incorporated in batches into the application medium for coloring. The article contains the mid-tone red effect pigment or the pigment combination of the present invention.

[0127] Compositions suitable for cosmetic formulations in which the mid-tone red effect pigment can be incorporated are known in the art. The formulation of cosmetics using the mid-tone red effect pigment of the present invention is carried out by means and methods well known to those skilled in the art. The mid-tone red effect pigment or the pigment combination of the present invention can be suitably used, for example, in nail polish.

[0128] In another aspect, the present invention relates to the use of mid-tone red effect pigments or pigment combinations as defined in any aspect herein in the dyeing or coloring of coating compositions such as paints, printing inks, inks, varnishes, plastics, fibers, films or cosmetic formulations, preferably automotive, architectural or industrial coating compositions.

[0129] The coating composition can be any decorative coating composition such as automotive, architectural, or industrial coating compositions or paints. The coating composition, printing ink, ink, or paint can be water-based or solvent-based. Preferably, the mid-tone red effect pigment or the pigment combination of the present invention is used as a colorant in automotive, architectural, or industrial coating compositions, paints, printing inks, inks, or plastics. In particular, the mid-tone red effect pigment or the pigment combination of the present invention is used as a colorant in automotive OEM or refinish coating compositions.

[0130] In another aspect, the present invention relates to a coating composition comprising paint, printing ink, ink, varnish, plastic, fiber, film, or cosmetic preparation, which is stained or colored by a mid-tone red effect pigment or combination of pigments as defined herein.

[0131] In another aspect, the present invention relates to an article coated with a composition comprising a mid-tone red effect pigment or a combination of pigments as defined herein.

[0132] Any material of the article may be coated with a composition comprising the mid-tone red effect pigment or the pigment combination of the present invention, including materials such as glass, ceramics, plastics, smooth surface composites, and metal substrates. The composition is particularly suitable for metal or plastic articles. The article may be on a bare substrate or, in the case of a metal substrate, may be pretreated to impart corrosion resistance, such as by phosphating or electrophoretic coating such as cathodic dip coating, or other similar treatments well known in the art.

[0133] Coatings containing this mid-tone red effect pigment or the pigment combination of the present invention are particularly suitable for multi-layer coatings in the automotive industry. As is known in the art, this mid-tone red effect pigment or the pigment combination of the present invention is typically incorporated into the base coat of an undercoat / clear coat coating system.

[0134] Therefore, the present invention relates to an automotive coating which is stained or colored by a mid-tone red effect pigment or combination of pigments as defined in any aspect herein.

[0135] In another aspect, the present invention relates to a method for dyeing or coloring a coating composition such as paint, printing ink, ink, varnish, plastic, fiber, film or cosmetic formulation, preferably an automotive, architectural or industrial coating composition, the method comprising adding thereto a mid-tone red effect pigment or pigment combination as defined herein.

[0136] The present invention is further illustrated by the following set of embodiments and by combinations of embodiments derived from the indicated dependencies and retrospective references. It is particularly noteworthy that in the various instances where a scope of embodiments is mentioned, for example with the term "method according to any one of embodiments 1-5," it is intended to explicitly disclose to a skilled person each embodiment within that scope, i.e., the wording of the term should be understood by a skilled person as synonymous with "method according to any one of embodiments 1, 2, 3, 4, and 5." Furthermore, it should be clearly noted that the following set of embodiments is not the set of claims defining the scope of protection, but rather represents a suitable component of the specification relating to the general and specific aspects of the invention.

[0137] 1. A mid-tone red effect pigment, comprising: sheet metal core; Contains silicon passivation layer; and An iron oxide layer above the passivation layer; Where h15 is within the range of 25°≤h15≤49°, preferably 28°≤h15≤45°; BF is 140-165, preferably 145-165, and most preferably 150-165; and The covering power is ∑dE < 110.

[0138] 2. The pigment of embodiment 1, wherein the sheet-like metal core comprises aluminum flakes having the following properties: a. Surface area (BET) ≤ 4 m² / g, preferably ≤ 3.8 m² / g, more preferably ≤ 3.5 m² / g; b. Particle size curve width (span) ≤ 1.2, preferably ≤ 1.1; c. Covering power ∑dE < 20, preferably < 15, more preferably < 13; d. Brightness L 15 > 153, preferred > 155.

[0139] 3. The pigment of embodiment 1, wherein the metal content is 25-60% by weight, preferably 25-40% by weight, and most preferably 25-38% by weight.

[0140] 4. The pigment of implementation scheme 1, wherein the chromaticity distribution range is ≥60.

[0141] 5. The pigment of implementation scheme 1, wherein the brightness distribution range is ≥90.

[0142] 6. The pigment of any of the foregoing embodiments, wherein the average particle size d50 ≥ 16µm.

[0143] 7. The pigment of any of the foregoing embodiments, wherein the iron oxide layer contains ≤10% by weight of other metal ions individually.

[0144] 8. The pigment of any of the foregoing embodiments comprises one or more additional layers applied to the iron oxide layer.

[0145] 9. The pigment according to any of the foregoing embodiments, wherein the iron oxide layer has an average thickness of 150-350 nm.

[0146] 10. The pigment of any of the foregoing embodiments, wherein the pigment comprises one or more additional layers on the iron oxide layer, selected from a silica layer, an organosilane layer, a polymer layer, or any combination thereof.

[0147] 11. The pigment of embodiment 10, wherein the additional layer contains SiO2 in an amount of ≤10% by weight.

[0148] 12. A method for preparing a mid-tone red effect pigment according to any one or more of embodiments 1-9, wherein the aluminum sheet is produced by a ball milling process.

[0149] Example

[0150] The invention is further described by the following non-limiting embodiments, which further illustrate the invention and are neither intended nor should be construed as limiting the scope of the invention.

[0151] Measurement test method

[0152] Hiding power ∑dE (A scraping method for achieving good hiding power): Add 0.044 g of dry aluminum substrate or 0.088 g of a dry coating compound, for example, with an iron oxide layer, to 4 g of varnish (87 parts ZM26-3025 Colorclassic + 13 parts ZC15-100E CAB solution adjusted to 36 parts DIN 4 with xylene / butyl acetate (30:70)) to a 25 mL high-speed mixer vial in a Hauschild DAC 150.1 FVZ-K high-speed mixer and mix at 3000 rpm for 1 minute. Immediately apply the mixture to Leneta 14H black and white hiding power test paper at room temperature = 21°C using an Erichsen Knochenrakel Modell 288 125µm 125µm coating machine on an Erichsen Coatmaster 510 at a speed of 18 mm / s. Lock the Leneta hiding power test paper into place on the Erichsen Coatmaster using a vacuum suction plate above it. The test card was dried in a fume hood at 21°C for 2 days, and then measured using a multi-angle color and effect measurement device (BYK-mac I Sensor 23mm, Illum. D65 10°) by measuring five times on each of the black and white sections. Opacity was calculated as ∑dE = dE(15°) + dE(25°) + dE(45°) + dE(75°) + dE(110°).

[0153] BET : Approximately 1.5–2.0 g of dried, solvent-free product was filled into the 9 mm cuvette sample holder of the Quantachrome Nova 4000e surface area analyzer. Accurate sample volume was evaluated by weighing an empty cuvette at room temperature, heating the filled cuvette to 100°C under vacuum and holding for 30 min, and then weighing it again at the same room temperature. Five measurements were then performed on the analytical stage of the Quantachrome apparatus under nitrogen and relative pressures of 0.10 / 0.15 / 0.20 / 0.25 and 0.30 P / Po. The BET value was automatically calculated by the apparatus and given in m² / g.

[0154] Particle size : The sample was pre-dispersed in isopropanol and then placed in the Hydro MV measuring cell of a Panalytical Malvern Mastersizer 3000. Measurements were performed for aluminum substrates in isopropanol at 30% US for 10 min and for coating compounds, for example, with an iron oxide layer, in isopropanol at 10% US for 2 min. Based on these measurements, the average particle size d50 and the width of the distribution curve can be determined, the latter being described herein as the width (span) of the particle size distribution = (d90 - d10) / d50. Typical values ​​of d50 used are in the range of d50 = 5-50 µm, more preferably 8-30 µm for automotive coatings, and even more preferably 9-25 µm.

[0155] Hue, chroma and lightness (Scraping method used for hue, chroma, and brightness): 0.88 g of dry pigment was added to 4 g of varnish (87 parts ZM26-3025 Colorclassic + 13 parts ZC15-100E CAB solution adjusted to 36 parts DIN 4 with xylene / butyl acetate (30:70)) and mixed at 3000 rpm for 1 min in a 25 mL high-speed mixer vial in a Hauschild DAC 150.1FVZ-K high-speed mixer. The mixture was immediately applied to BYK pure white standard test card paper WH 2828 at 18 mm / s using an Erichsen Knochenrakel Modell 288 125µm coating machine on an Erichsen Coatmaster 510 at room temperature = 21°C. The BYK standard test card paper was then secured in place on the Erichsen Coatmaster using a vacuum suction plate above it. The test card was dried in a fume hood at room temperature (21°C) for 2 days, and then measured at 5 points evenly distributed in the middle of the coating using a multi-angle color and effect measurement device (BYK-mac I Sensor 23mm, illustration. D65 10°).

[0156] Chemical analysis : The amounts of elements Al, Si, Fe, and Sn (g / 100g dry pigment) were determined using an Agilent ICP-OES 5100 instrument. The amounts of oxides SiO2, Fe2O3, and SnO2 were calculated using molar mass M and mass m as follows: m(SiO2) = m(Si) M(SiO2) M(Si) -1 m(Fe₂O₃) = m(Fe) M(Fe2O3) (2 M(Fe))-1 And m(SnO2)=m(Sn) M(SnO2) M(Sn) -1 The weight percentages of Al, SiO2, Fe2O3, and SnO2 are further expressed as m(x). 100 (m(Al) + m(SiO2) + m(Fe2O3) + m(SnO2)) -1 Calculate, where x = Al, SiO2, Fe2O3 or SnO2.

[0157] Table 3 Chemical analysis of red effect pigments based on aluminum flakes

[0158] Table 3 contains the measurement results of the dry pigments according to the methods described in the chemical analysis. The measured values ​​of elements Fe, Si, and Sn were recalculated as results from SiO2, Fe2O3, and SnO2. Aluminum was calculated as metallic aluminum. Finally, the calculated values ​​of Al and oxides were normalized to 100%.

[0159] Table 4. Basic particle size and color properties of pigments in the prior art, invention examples, or comparative examples.

[0160] Table 4 compares the following basic properties of prior art pigments (CQV Stellar Red, Merck Meoxal Victoria Red, Sun Chemical Paliocrom Brilliant Red, Sun Chemical Paliocrom Sparkling Red, Comparative Example 1, Comparative Example 2, Comparative Example 3) with the pigments of the present invention (Examples 1-4): particle size distribution; color performance h15, C. 15, L 15, h110, C 110, L 110; Opacity (∑dE); Chromaticity distribution range (C Distribution range); Brightness distribution range (L) Distribution range); and brightness factor (BF).

[0161] Inventive Example 1

[0162] a) Suspend 140 g of aluminum Al1 (dry powder) as described in Table 2 in 1300-1600 mL of ethanol. SiO2 passivation occurs according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. Filter the resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane and wash with a total of 1500 mL of ethanol. The received paste has a solids concentration of 50-60% and the dry pigment has an Al / SiO2 weight ratio of approximately 4:1 as described in Table 3.

[0163] b) Disperse the SiO2-coated aluminum paste (75-100g dry powder) in 700mL of softened water and heat the slurry to 73-78°C. Set the pH to 3.35 using 10% HNO3 by weight, and add 0.2-0.3g Al2(SO4)3. The solution of 16 H2O in 30 mL of softened water was adjusted to pH 3.1, and the pH was maintained at 2.8 with 25% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color was obtained. Typical feeding times were in the range of 12-25 h, and the final pigment had an Al:SiO2:Fe2O3 content of approximately 4:1:7, as shown in Table 3. The slurry was filtered, washed twice with softened water for small samples or until a conductivity level of, for example, 200 µS was obtained, and then washed with ethanol or isopropanol. For small samples, the filter cake was vacuum dried at room temperature for 2-20 h or kept as an alcohol-containing paste with a solids concentration of 60-80% for use in the next step when preparing larger samples.

[0164] c) Anneal a small sample of the dried pigment at 240°C for 3 hours in a drying chamber. Disperse a larger sample (45-60 g dry powder) of the resulting pigment paste in 730-750 g of isoparaffinic fluid. Heat the reaction mixture to 195-220°C over 10 hours and stir at 195-220°C under a nitrogen atmosphere for 6 hours. Filter the slurry, wash with ethanol, and vacuum dry the filter cake at room temperature for an additional 5 minutes. The received paste has a solids concentration of approximately 60-80%.

[0165] Inventive Example 2

[0166] a) Suspend 145 g of aluminum Al2 (dry powder) as described in Table 2 in 1300-1600 mL of ethanol. SiO2 passivation occurs according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. Filter the resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane and wash with a total of 1500 mL of ethanol. The received paste has a solids concentration of 50-60% and the dry pigment has an Al / SiO2 weight ratio of approximately 4:1.

[0167] b) Disperse the SiO2-coated aluminum paste (75-100g dry powder) in 700mL of softened water and heat the slurry to 73-78°C. Set the pH to 3.35 using 5-10% by weight HNO3, and add 0.2-0.4g Al2(SO4)3. The solution of 16 H2O in 30 mL of softened water was adjusted to pH 3.1, and the pH was maintained at 2.8 with 25 wt% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color was obtained. Typical feeding times are in the range of 12-25 h, and the final pigment has an Al:SiO2:Fe2O3 content of approximately 4:1:7. The slurry was filtered, and for small samples, it was washed twice with softened water or until a conductivity level of, for example, 200 µS was obtained, followed by washing with ethanol or isopropanol. For small samples, the filter cake was vacuum dried at room temperature for 2-20 h or kept as an alcohol-containing paste with a solids concentration of 60-80% for use in the next step when preparing larger samples.

[0168] c) Anneal a small sample of the dried pigment at 240°C for 3 hours in a drying chamber. Disperse a larger sample (60 g dry powder) of the resulting pigment paste in 730-750 g of isoparaffinic fluid. Heat the reaction mixture to 195-220°C over 10 hours and stir at 195-220°C under a nitrogen atmosphere for 6 hours. Filter the slurry, wash with ethanol, and vacuum dry the filter cake at room temperature for an additional 5 minutes. The received paste has a solids concentration of approximately 60-80%.

[0169] Inventive Example 3

[0170] a) The aluminum Al3 (140 g dry powder) as described in Table 2 was suspended in 1300-1600 mL of ethanol. SiO2 passivation occurred according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. The resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane was filtered and washed with a total of 1500 mL of ethanol. The received paste had a solids concentration of 50-60% and the dry pigment had an Al / SiO2 weight ratio of approximately 3:1.

[0171] b) Disperse 100g of SiO2-coated aluminum paste in 700mL of softened water and heat the slurry to 73°C. Set the pH to 3.35 using 5-10% by weight HNO3, and add 0.45g of Al2(SO4)3. The solution of 16 H2O in 30 mL of softened water was adjusted to pH 3.1, and the pH was maintained at 2.8 with 25% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color was obtained. Typical feeding times are in the range of 12-25 h, and the final pigment has an Al:SiO2:Fe2O3 content of approximately 3:1:6.5. The slurry was filtered, washed twice with softened water and then with ethanol or isopropanol for small samples, and the filter cake was vacuum dried at room temperature for 2-20 h for small samples.

[0172] c) Anneal small samples of dry pigment at 240°C for 3 hours in a drying chamber.

[0173] Inventive Example 4

[0174] a) Suspend 140 g of aluminum Al₄ (dry powder) as described in Table 2 in 1300-1600 mL of ethanol. SiO₂ passivation occurs according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. Filter the resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane and wash with a total of 1500 mL of ethanol. The received paste has a solids concentration of 50-60% and the dry pigment has an Al / SiO₂ weight ratio of approximately 3:1.

[0175] b) Disperse 100g of SiO2-coated aluminum paste in 700mL of softened water and heat the slurry to 73°C. Set the pH to 3.35 using 5-10% by weight HNO3, and add 0.4g of Al2(SO4)3. The pH of the 16 H2O solution in 30 mL of softened water was adjusted to 3.1, and the pH was maintained at 2.8 with 25% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color was obtained. Typical feeding times are in the range of 12-25 h, and the final pigment has an Al:SiO2:Fe2O3 content of approximately 3:1:7. The slurry was filtered, washed twice with softened water and then with ethanol or isopropanol for small samples, and the filter cake was vacuum dried at room temperature for 2-20 h for small samples.

[0176] c) Anneal small samples of dry pigment at 240°C for 3 hours in a drying chamber.

[0177] Comparative Example 1

[0178] a) The aluminum Al 5 (140 g dry powder) as described in Table 2 was suspended in 1300-1600 mL of ethanol. SiO2 passivation occurred according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. The resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane was filtered and washed with a total of 1500 mL of ethanol. The received paste had a solids concentration of 50-60% and the dry pigment had an Al / SiO2 weight ratio of approximately 3:1.

[0179] b) Disperse the SiO2-coated aluminum paste (75g dry powder) in 700mL of softened water and heat the slurry to 73-78°C. Set the pH to 3.35 using 10% by weight HNO3, and add 0.3-0.45g Al2(SO4)3. The solution of 16 H2O in 30 mL of softened water is adjusted to pH 3.1, and maintained at pH 2.8 with 25 wt% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color is obtained. Typical feeding times are in the range of 12-25 h, and the final pigment has an Al:SiO2:Fe2O3 content of approximately 3:1:6. The slurry is filtered, and for small samples, it is washed twice with softened water or until a conductivity level of, for example, 200 µS is achieved, followed by washing with ethanol or isopropanol. For small samples, the filter cake is vacuum dried at room temperature for 2-20 h or kept as an alcohol-containing paste with a solids concentration of 60-80% for use in the next step when preparing larger samples.

[0180] c) Anneal a small sample of the dry pigment in a drying chamber at 240°C for 3 hours. Disperse a larger sample (60 g dry powder) of the resulting pigment paste in 730-750 g of isoparaffinic fluid. Heat the reaction mixture to 195-220°C over 10 hours and stir at 195-220°C under a nitrogen atmosphere for 6 hours. Filter the slurry, wash with ethanol, and vacuum dry the filter cake at room temperature for an additional 5 minutes. The received paste has a solids concentration of approximately 60-80%.

[0181] Comparative Example 2

[0182] a) 140 g of aluminum Al6 (dry powder) as described in Table 2 was suspended in 1300-1600 mL of ethanol. SiO2 passivation occurred according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. The resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane was filtered and washed with a total of 1500 mL of ethanol. The received paste had a solids concentration of approximately 70% and the dry pigment had an Al / SiO2 weight ratio of approximately 4.5:1.

[0183] b) Disperse the SiO2-coated aluminum paste (75g dry powder) in 700mL of softened water and heat the slurry to 73°C. Set the pH to 3.35 using 10% by weight HNO3, and add 0.3-0.45g Al2(SO4)3. The solution of 16 H2O in 30 mL of softened water was adjusted to pH 3.1, and the pH was maintained at 2.8 with 25% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color was obtained. Typical feeding times are in the range of 12-25 h, and the final pigment has an Al:SiO2:Fe2O3 ratio of approximately 4.5:1:7. The slurry was filtered, washed twice with softened water and then with ethanol or isopropanol for small samples, and the filter cake was vacuum dried at room temperature for 2-20 h for small samples.

[0184] c) Anneal small samples of dry pigment at 240°C for 3 hours in a drying chamber.

[0185] Comparative Example 3

[0186] a) The aluminum Al7 (140 g dry powder) as described in Table 2 was suspended in 1300-1600 mL of ethanol. SiO2 passivation occurred according to the method described in Example 1 of US 5,607,504, EP-A-0708154, or JP-A-54081337. The resulting suspension of passivated aluminum, ethanol, ammonia, water, and unhydrolyzed / partially hydrolyzed tetraethoxysilane was filtered and washed with a total of 1500 mL of ethanol. The received paste had a solids concentration of about 80% and the dry pigment had an Al / SiO2 weight ratio of about 7:1.

[0187] b) Disperse 100g of SiO2-coated aluminum paste in 700mL of softened water and heat the slurry to 73°C. Set the pH to 3.35 using 10% HNO3 by weight, and add 0.1-0.2g of Al2(SO4)3. The solution of 16 H2O in 30 mL of softened water was adjusted to pH 3.1, and the pH was maintained at 2.8 with 25% NaOH during the addition of a Fe(NO3)3 solution with a Fe weight concentration of 6-9% until the desired red color was obtained. Typical feeding times are in the range of 12-25 h, and the final pigment has an Al:SiO2:Fe2O3 ratio of approximately 7:1:9. The slurry was filtered, washed twice with softened water and then with ethanol or isopropanol for small samples, and the filter cake was vacuum dried at room temperature for 2-20 h for small samples.

[0188] c) Anneal small samples of dry pigment at 240°C for 3 hours in a drying chamber.

Claims

1. A mid-tone red effect pigment, comprising: sheet metal core; A silicon-containing passivation layer on top of the sheet-like metal core; and An iron oxide and / or hydroxyl iron oxide layer above the passivation layer; Where h15 is within the range of 25°≤h15≤49°, preferably 28°≤h15≤45°; BF is 140-165, preferably 145-165, and most preferably 150-165; and The covering power is ∑dE < 110.

2. The pigment of claim 1, wherein the sheet-like metal core comprises aluminum flakes having the following properties: a. Surface area (BET) ≤ 4 m² / g, preferably ≤ 3.8 m² / g, more preferably ≤ 3.5 m² / g; b. Particle size curve width (span) ≤ 1.2, preferably ≤ 1.1; c. Covering power ∑dE < 20, preferably < 15, more preferably < 13; d. Brightness L 15 > 153, preferred > 155.

3. The pigment of claim 1 or 2, wherein the metal content is 25-60% by weight, preferably 25-40% by weight, and most preferably 25-38% by weight.

4. The pigment of any one of claims 1-3, wherein the chromaticity distribution range is ≥60.

5. The pigment of any one of claims 1-4, wherein the brightness distribution range is ≥90.

6. The pigment of any one of claims 1-5, wherein the average particle size d50 ≥ 16µm.

7. The pigment of any one of claims 1-6, wherein the iron oxide and / or hydroxy iron oxide layer contains ≤10% by weight of other metal ions and / or metals.

8. The pigment of any one of claims 1-7, wherein the iron oxide and / or iron hydroxy oxide layer has a thickness of 150-350 nm or an average thickness.

9. The pigment of any one of claims 1-8, comprising one or more additional layers applied to the iron oxide and / or hydroxy iron oxide layers.

10. The pigment of claim 9, wherein the pigment comprises one or more additional layers on the iron oxide and / or iron hydroxy oxide layers, selected from a silica layer, an organosilane layer, a polymer layer, or any combination thereof.

11. The pigment of claim 9 or 10, wherein the additional layer comprises SiO2 in an amount of ≤10% by weight.

12. The pigment of any one of claims 1-11, wherein the aluminum flakes are produced by a ball milling process.

13. A method for preparing a mid-tone red effect pigment according to any one of claims 1-12, wherein the aluminum flakes are produced by a ball milling process.

Images