Fast-dispersing Pigment Brown 29

Abstract

A chromium and iron oxide based pigment with a color index of Pigment Brown 29 that is dry-milled and can be rapidly dispersed in a variety of solvent and water-based coatings.

Description

[Technical Field]

[0001] The present invention relates to a chromium and iron oxide based pigment, color index Pigment Brown 29, that can be dry-milled and rapidly dispersed in a variety of solvent and water-based coatings. [Background technology]

[0002] Ink and coating formulations are typically prepared by dispersing pigment powder in a solvent- or water-based binder system. Examples of dispersion equipment include ball mills, bead mills, rotor-stator dispersers, three-roll mills, impeller mills, or shakers. The powder dispersion process is very time- and energy-consuming, typically requiring several hours to achieve the desired level of dispersion. During the dispersion process, the pigment undergoes a series of complex, interlocking processes. During the wetting process, adsorbed air is removed from the particle surface, while a solvate layer is formed. Deagglomeration occurs before, during, and after the wetting process. The dispersion process requires external energy to break up the pigment agglomerates and achieve a uniform particle distribution throughout the binder system. The deagglomerated particles then need to be stabilized to prevent flocculation. This can be achieved by applying repulsive forces, i.e., electrostatic or steric forces, between individual particles.

[0003] Inorganic pigment powders are typically produced by solid-state reactions, co-milling reactions, or precipitation reactions. Typically, a heat treatment process is applied at least once during the production of inorganic pigments. This heat treatment can be achieved, for example, in a muffle furnace, rotary kiln, microwave oven, vertical furnace, or electric arc furnace. This heat treatment generates agglomerates of pigment particles, which must be pulverized during the dispersion process. Therefore, a milling process is typically required during the production of printing inks, paints, or coatings. Milling can be achieved, for example, by a ball mill, hammer mill, jet mill, bead mill, or pen mill. In a wet milling process, energy is applied to the pigment particles, resulting in deagglomeration and improved color strength. However, when using a wet milling process, a subsequent drying process is required, which results in the generation of new agglomerates, which must be pulverized again during the dispersion process, increasing processing time. Therefore, it is important to use dry milling techniques, i.e., jet mills, hammer mills, dry ball mills, or pen mills, to avoid the subsequent drying process.

[0004] Some properties of coating systems depend on the degree of dispersion, i.e., color strength or tinting strength, hue, hiding power, viscosity, gloss, and dispersibility. Furthermore, some properties, such as color strength, are strongly dependent on the degree of dispersion, so they can be used to directly determine the degree of dispersibility. Thus, if the color strength is continuously increasing, even if the dispersion time is long, the dispersibility is still quite low. Conversely, if the increase in color strength approaches or reaches its maximum value, the dispersibility is considered high.

[0005] Furthermore, when the pigment is used in thin coatings, the final pigment should exhibit low dispersity to ensure that large particles or agglomerates do not create poor printability, e.g., a rough surface on the applied coating.

[0006] The cited document does not mention the target properties (lightness value, color strength, dispersibility, dispersibility index) nor the use of dry grinding techniques to improve the dispersibility of the resulting pigments.

[0007] All of the literature that mentions improving dispersibility uses additional additives such as surface modifiers or polymer complexes or resins. Furthermore, literature that describes the property of easy dispersibility associates this property with wet to semi-dry pigments. Finally, to bring an easy dispersible pigment into powder form, an additional drying step would be required, which is energy- and time-consuming. Nevertheless, the additional drying step would lead to agglomeration, negating the easy dispersibility property.

[0008] In general, the color of (Fe,Cr)2O3-based pigments depends on their particle size and chromium content. When the particle size Dv(50) is in the range of several hundred nanometers, the pigments are brown. However, when the particle size Dv(50) increases to approximately 1 μm, the pigments become black.

[0009] US 4,643,772 A discloses a method for producing brown (Fe,Cr)2O3-based pigments. The brown color and easy dispersibility are achieved by using transparent alpha-type iron oxide and chromium salts with an orthorhombic bipyramidal crystal structure and a Dv(50) in the range of 0.1 to 0.4 μm as starting materials. This method involves a precipitation process in which chromium salts are dissolved and precipitated as chromium hydroxide in the presence of alkali carbonate and iron oxide. The precipitate is then filtered, dried, and calcined. After calcination, the product is wet-milled in a ball mill, sand mill, or bead mill. The product is then filtered, and the pigment slurry is dried again. Due to the smaller particle size of the repeatedly milled pigment, the resulting pigments of US 4,643,772 A exhibit better dispersibility. However, achieving a black color with a particle size (Dv(50)) greater than 1 μm with good dispersibility from (Fe,Cr)2O3-based pigments remains difficult.

[0010] GB 1530740A discloses a method for obtaining Fe2O3-based pigments using ferrous sulfate as the iron source, which is a waste product from the TiO2 processing cycle. Furthermore, various modifiers are used to adjust the color of the final pigment. The use of chromium as a modifier results in a fairly brown pigment. Fe2O3-based pigments are obtained by a wet-mixing process in which all starting materials are dissolved. After calcination, the resulting pigment is not ground, resulting in a coarse pigment that is difficult to disperse due to numerous agglomerates, which require grinding during the dispersion process, which consumes time and energy. The pigments of the present invention are obtained by dry-mixing the starting components, eliminating the need for an additional drying step before the calcination process. Furthermore, the pigments of the present invention use only iron and chromium elements, resulting in a black pigment without the addition of modifiers required by GB 1530740A.

[0011] Our investigations have shown that dry-milling pigments results in pigments with high dispersibility, with only a slight increase in color strength over time, as well as low dispersibility. We have found that by adjusting the milling parameters, we can increase the dispersibility of the pigment and at the same time leave the color properties unchanged or even improve them. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] US4643772A [Patent Document 2] GB1530740A Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention addresses the drawbacks of high energy and time consumption by providing certain pigments that can be dispersed with reduced time and energy requirements. The pigments provided and the environmentally friendly pigments of the present invention provide performance characteristics similar to or even superior to commercially available pigments, while having the advantages of faster processing times and reduced energy consumption. In one embodiment, the pigments of the present invention exhibit increased color intensity, thus potentially allowing for the use of less pigment.

[0014] Citation or identification of any document in this application is not an admission that it is prior art to the present invention.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows four different particle size distributions. These were measured using water as the dispersion medium. No ultrasound was applied before or during the measurements. The particle size distribution of the described invention is shown by squares. The distributions were measured after 1, 3, and 5 minutes of dispersion. The commercial Pigment Brown 29 and Sicopal Black 0095 after 5 minutes of dispersion are shown by triangles. While the particle size distribution of the present invention exhibits a unimodal Gaussian curve, Sicopal Black 0095 exhibits a bimodal Gaussian curve. Furthermore, the curve bottoms out at a larger particle size, indicating larger particles, resulting in a higher Dv(100) of 9.2 μm and a higher degree of dispersion in the coating system defined herein. The pigment of the present invention exhibits a more defined particle size distribution due to its unimodal Gaussian curve. Furthermore, this distribution does not change over time, confirming the fact that the pigment is already fully dispersed in water after 1 minute. Furthermore, the curve bottoms out at smaller particle sizes, resulting in a Dv(100) of 6 μm and lower dispersion in the coating system.

[0016] Detailed Description In the present invention, chromium and iron-based oxides having a hematite crystal structure and a pigment index of Pigment Brown 29 are synthesized by a solid-state reaction of one or more chromium sources, such as chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanide, and chromium cyanide, with one or more iron sources, such as iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, and iron cyanide. The raw materials are mixed in a mass ratio of 1:99 to 50:50, 10:90 to 30:70, or 25:75 to 42:58, depending on the chromium content. In one embodiment, the composition can further comprise other transition metal compounds of period 4 elements or rare earth metals from the group of oxides, hydroxides, oxalates, carbonates, sulfates, chlorides, bromides, iodides, nitrates, or thiocyanides. In further embodiments, the other transition metal or rare earth compounds are present at 0-10% by weight, or 0-5% by weight, of the total composition.

[0017] The mixture is then calcined at a high temperature, for example, in a muffle furnace, rotary kiln, microwave furnace, vertical furnace, or electric arc furnace. The temperature can vary and be set at various temperatures during the heat treatment. In one embodiment, the temperature is in the range of 500 to 1300°C, preferably in the range of 550 to 1250°C, and more preferably in the range of 610 to 1170°C. After the heat treatment, the resulting pigment is pre-ground, for example, using a hammer mill or crusher (i.e., a roll crusher, jaw crusher, gyratory crusher, impact crusher, or cone crusher). If the calcined pigment does not exhibit any lumps or large agglomerates, the pre-grinding step can optionally be omitted. Grinding aids such as fumed silica and alkaline earth carbonates are then optionally added to the resulting pigment, for example, in a proportion of 0 to 10% by weight, or 0 to 5% by weight. The resulting mixture is then dry-ground, for example, using a jet mill, hammer mill, dry ball mill, or pen mill. In a specific embodiment, the pigment of the present invention is milled by jet milling, which facilitates the control of the particle size distribution of the final product. During the milling process, the particle size distribution and dispersity are reduced. In one embodiment, the particle size should be Dv(100)≦10 μm and the dispersity≦15 μm.

[0018] By reducing, or more preferably eliminating, agglomerates, the present invention exhibits reduced time and energy consumption when dispersed in a binder system. This system can be, for example, any solvent-based, water-based, or energy-curable system. The absence of agglomerates requires less external energy to disperse the pigment. Therefore, an initial wetting process can be performed, reducing the time required. Furthermore, no additional milling steps are required during dispersion. The dispersion process can be carried out using less complex dispersion tools, such as dissolvers. Time consumption is further reduced because reprocessing steps, such as separating balls from the coating system, are not required. High dispersibility maximizes color strength in a short dispersion time. Furthermore, complete dispersion of the pigment is possible in some coating systems, resulting in improved color strength compared to other commercially available pigments. Because the dry milling process breaks down the agglomerates but leaves the primary particles or aggregates intact, color properties, i.e., hue, saturation, hiding power, gloss, and brightness values, remain constant and exhibit similar properties to commercially available pigments. Color properties depend on the coating system.

[0019] Formula 1:

number

[0020] Equation 1 can be used to derive the dispersibility index (DI) of Pigment Brown 29 of Example 1 of the present invention dispersed in various binder systems versus Comparative Example 1 (representing commercially available Pigment Brown 29 (Pigment Brown 29, Sicopal Black 0095, purchased from BASF in 2022)), with higher DI values ​​indicating easier dispersion and higher blackness. The pigments of Comparative Examples 2 and 3 represent commercially available Dynamix Black pigments (Dynamix Black 30C941 and Dynamix Black 30C940, purchased from Shepherd in 2023) and are not used in determining the dispersibility index (DI) according to the present invention. According to the present invention, FOG represents the fineness of grind.

[0021] In one embodiment, the binder system including the pigment of Example 1 exhibits a dispersibility index (DI) increase of ≧100%, or ≧200%, or ≧250% relative to the comparative example after 30 minutes of treatment using a dissolver dispersion process in a melamine-based solvent-borne binder system or a water-based binder system, where DI is determined by Equation 1.

[0022] In another embodiment, a binder system including the pigment of Example 1 exhibits a dispersibility index (DI) increase of ≧1000%, or ≧2000%, or ≧2500% relative to the comparative example after 30 minutes of treatment using a dissolver dispersion process in a melamine-based solvent-borne binder system or a water-based binder system, where DI is determined by Equation 1.

[0023] In another embodiment, the binder system containing the pigment of Example 1 exhibits a dispersibility index (DI) increase of ≧500%, or ≧600%, or ≧700%, or ≧800%, or ≧900% relative to the comparative example after 30 minutes of treatment using a dissolver dispersion process in a two-component polyurethane solvent-based binder system, where DI is determined by Equation 1.

[0024] In another embodiment, the binder system including the pigment of Example 1 exhibits a dispersibility index (DI) increase of ≧1000%, or ≧2000%, or ≧2500% relative to the comparative example after processing for 30 minutes using a dissolver dispersion process in a polyvinylidene fluoride (PVDF) resin-based binder system, where DI is determined by Equation 1.

[0025] The present invention further relates to a Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, wherein the pigment exhibits a dispersibility index (DI) increase of ≧1000%, or ≧2000%, or ≧2500% relative to a comparative example after treatment for 30 minutes using a dissolver dispersion process in a melamine-based solvent-based binder system or a water-based binder system, wherein the DI is determined by the formula 1:

number

[0026] Because Pigment Brown 29 is described as a very dark brown, almost black pigment, only the lightness value is necessary to describe its color characteristics. In the CIELAB color space, the a and b values ​​reflect the four colors inherent in human vision: red, green, blue, and yellow. Therefore, for very dark brown or black pigments, the a and b values ​​are near zero and are therefore unnecessary. However, the lightness value immediately indicates whether the pigment is white or black. Lightness values ​​define 0 as black and 100 as white. Therefore, the lightness value of black is as close to zero as possible. Furthermore, color intensity, dispersity, and particle size distribution (Dv(100)) are used to define the pigment's dispersibility. If a pigment has higher color intensity than comparable pigments, this equates to better dispersibility. The same is true for dispersibility. If a pigment's agglomerates or coarse particles disaggregate faster than comparable pigments, this equates to better dispersibility. Since color strength and dispersibility depend on the coating system used, Dv(100) is independent of any coating system. Dv(100) represents the largest particle or agglomerate in the pigment. If Dv(100) is already small, there is no need to deagglomerate agglomerates or coarse particles, thus shortening the dispersion time. Equation 1 incorporates all the parameters described to arrive at an index for evaluating the dispersibility of Pigment Brown 29. The higher the value, the better the dispersibility and blackness. This index can be used to compare the dispersibility and applicability of different Pigment Brown 29 compounds. [Means for solving the problem]

[0027] The invention is further described by the following numbered sections:

[0028] 1. A Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, wherein the pigment exhibits a dispersibility index (DI) increase of ≧100%, or ≧200%, or ≧250% relative to a comparative example after 30 minutes of treatment using a dissolver dispersion process in a melamine-based solvent-based binder system or a water-based binder system, wherein the DI satisfies the formula 1:

number

[0029] 2. The pigment composition according to item 1, wherein the color strength in a melamine-based solvent-borne binder system is in the range of 105 to 155, preferably in the range of 115 to 145, and more preferably in the range of 125 to 135.

[0030] 3. The pigment composition according to item 1, wherein the FOG in a melamine-based solvent-based binder system is in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, and more preferably in the range of 7 to 10 μm.

[0031] 4. The pigment composition according to item 1, wherein the brightness value in a melamine-based solvent-based binder system is in the range of 6 to 25, preferably in the range of 7 to 18, and more preferably in the range of 8 to 12.5.

[0032] 5. The pigment composition according to item 1, wherein the color strength in a water-based binder system is in the range of 90 to 120, preferably in the range of 95 to 115, and more preferably in the range of 100 to 110.

[0033] 6. The pigment composition according to item 1, wherein the FOG in a water-based binder system is in the range of 5 to 25 μm, preferably in the range of 8 to 20 μm, and more preferably in the range of 11 to 15 μm.

[0034] 7. The pigment composition according to item 1, having a brightness value in a water-based binder system in the range of 3 to 12, preferably in the range of 4 to 10, and more preferably in the range of 5 to 8.

[0035] 8. A Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, wherein the pigment exhibits a dispersibility index (DI) increase of ≧500%, or ≧600%, or ≧700%, or ≧800%, or ≧900% relative to a comparative example after 30 minutes of treatment using a dissolver dispersion process in a two-component polyurethane solvent-based binder system, wherein the DI is expressed as a function of Formula 1:

number

[0036] 9. The pigment composition according to item 8, having a color strength in the range of 100 to 130, preferably in the range of 105 to 125, and more preferably in the range of 110 to 120.

[0037] 10. The pigment composition according to item 8, wherein FOG is in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, and more preferably in the range of 7 to 10 μm.

[0038] 11. The pigment composition according to item 8, having a brightness value in the range of 6 to 25, preferably in the range of 7 to 18, and more preferably in the range of 8 to 11.

[0039] 12. A Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, which exhibits a dispersibility index (DI) increase of ≧1000%, or ≧2000%, or ≧2500% relative to a comparative example after processing for 30 minutes using a dissolver dispersion process in a polyvinylidene fluoride (PVDF) resin-based binder system, wherein the DI is determined by the following formula:

number

[0040] 13. The pigment composition according to item 12, having a color strength in the range of 100 to 130, preferably in the range of 105 to 125, and more preferably in the range of 110 to 120.

[0041] 14. The pigment composition according to item 12, wherein the FOG is in the range of 2 to 15 μm, preferably in the range of 3 to 10 μm, and more preferably in the range of 4 to 5 μm.

[0042] 15. The pigment composition according to item 12, having a brightness value in the range of 6 to 25, preferably in the range of 7 to 18, and more preferably in the range of 8 to 11.

[0043] 16. A pigment composition according to any preceding paragraph, wherein the comparative example is commercially available Pigment Brown 29 as described herein.

[0044] 17. A pigment composition according to any preceding item, wherein Dv(100) is in the range of 3 to 9 μm, preferably in the range of 5 to 8 μm, more preferably in the range of 5.5 to 7.5 μm, and more preferably in the range of 6 to 7 μm.

[0045] 18. A pigment composition according to any preceding claim, wherein the chromium is selected from the group consisting of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanide, chromium cyanide, and mixtures thereof, preferably from the group consisting of chromium oxide, chromium hydroxide, and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably chromium oxide.

[0046] 19. A pigment composition according to any preceding claim, wherein the iron-based oxide is selected from the group consisting of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, iron cyanide, and mixtures thereof, preferably from the group consisting of iron oxide, iron hydroxide, and mixtures thereof; more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

[0047] 20. A pigment composition according to any of the preceding paragraphs, wherein 90 to 100% by mass of the pigment composition comprises chromium- and iron-based oxides, preferably 95 to 100% by mass, more preferably 98 to 100% by mass, and even more preferably 99 to 100% by mass.

[0048] 21. The pigment composition of any preceding claim, further comprising a grinding aid, preferably selected from the group consisting of silicon oxide, alkaline earth metal oxide, alkaline earth metal carbonate, and mixtures thereof, more preferably the grinding aid comprises an alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0049] 22. The pigment composition according to item 21, wherein the pigment composition contains 0.1 to 8 mass%, preferably 0.2 to 6 mass%, more preferably 0.25 to 4 mass%, and more preferably 0.5 to 2 mass% of the grinding aid, relative to 100 mass% of the pigment composition.

[0050] 23. A pigment composition according to any preceding claim, wherein the pigment composition does not contain a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0051] 24. A pigment composition according to any preceding paragraph, with the proviso that the pigment composition contains a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0052] 25. The pigment composition according to any one of paragraphs 1 to 22, further comprising an additional transition metal compound.

[0053] 26. The composition of claim 25, wherein the additional transition metal compound is selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0054] 27. A pigment composition according to any one of the preceding paragraphs, wherein the raw materials are mixed in a ratio relative to the chromium content of 1:99 to 50:50, 10:90 to 30:70, or 25:75 to 42:58.

[0055] 28. An ink, paint or coating composition comprising the pigment according to any one or more of paragraphs 1 to 27.

[0056] 29. Use of a pigment composition according to any preceding claim as a component in an ink, paint or coating.

[0057] 30. A method for preparing one or more of an ink, paint, or coating, comprising using as an ingredient a pigment composition according to any preceding paragraph.

[0058] 31. A method for preparing Pigment Brown 29 pigment composition, comprising a solid-state reaction between a mixture of a chromium source and an iron source, calcining the mixture at high temperature and then dry-milling, wherein the pigment exhibits a dispersibility index (DI) increase of ≧100%, or ≧200%, or ≧250% relative to a comparative example after treatment for 30 minutes using a dissolver dispersion process, wherein the DI is expressed by Equation 1:

number

[0059] 32. The method according to item 31, further comprising a step of pre-grinding after firing.

[0060] 33. The method according to item 31 or 32, wherein the mixture is fired at a temperature in the range of 500 to 1300°C, preferably in the range of 550 to 1250°C, more preferably in the range of 610 to 1170°C.

[0061] 34. The method according to any one or more of paragraphs 31 to 33, wherein the mixture is fired in a rotating device at a rotation speed in the range of 0.2 to 10 rpm, preferably in the range of 1 to 5 rpm.

[0062] 35. The method of any one or more of paragraphs 31 to 34, wherein the mixture is dry-milled in a jet mill, preferably a fluidized bed counter jet mill, at a pressure in the range of 0.5 to 5 bar, preferably in the range of 1.5 to 3 bar, and at a classifying wheel speed in the range of 3000 to 7000 rpm, preferably in the range of 3500 to 6500 rpm, more preferably in the range of 4000 to 6000 rpm.

[0063] 36. The method of any one or more of paragraphs 31 to 35, wherein the chromium source and the iron source are mixed in an iron source:chromium source ratio ranging from 74:26 to 58:42, preferably in an iron source:chromium source ratio ranging from 70:30 to 58:42, more preferably in an iron source:chromium source ratio of 67:33.

[0064] 37. The method of any one or more of paragraphs 31 to 36, wherein the raw materials are mixed in a ratio relative to their chromium content of 1:99 to 50:50, 10:90 to 30:70, or 25:75 to 42:58.

[0065] 38. The method of any one or more of paragraphs 31 to 37, wherein the composition further comprises an additional transition metal compound.

[0066] 39. The method of claim 38, wherein the additional transition metal compound does not contain manganese, preferably the additional transition metal compound does not contain manganese oxide, manganese trioxide, or manganite.

[0067] 40. The method of claim 38, wherein the further transition metal compound is selected from the group consisting of manganese oxide, manganese trioxide, manganite, or mixtures thereof.

[0068] 41. The method of any one or more of paragraphs 31 to 40, wherein the iron-based oxide is selected from the group consisting of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, iron cyanide, and mixtures thereof, preferably from the group consisting of iron oxide, iron hydroxide, and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

[0069] 42. The method of any one or more of paragraphs 31 to 41, wherein the chromium is selected from the group consisting of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanide, chromium cyanide, and mixtures thereof, preferably from the group consisting of chromium oxide, chromium hydroxide, and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably is chromium oxide; 43. The method of any one or more of paragraphs 31 to 42, further comprising one or more grinding aids.

[0070] 44. The method of claim 43, wherein the grinding aid is selected from the group consisting of fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof; preferably, the grinding aid is selected from the group consisting of fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof; more preferably, the grinding aid comprises an alkaline earth metal carbonate; preferably, the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof; more preferably, the alkaline earth metal carbonate comprises calcium carbonate, more preferably is calcium carbonate.

[0071] 45. The method according to item 43 or 44, wherein the grinding aid is added in an amount of 0.1 to 8 mass%, preferably 0.2 to 6 mass%, more preferably 0.25 to 4 mass%, more preferably 0.5 to 2 mass%, relative to 100 mass% of the calcined mixture.

[0072] 46. ​​The method of any one or more of paragraphs 31 to 45, wherein when incorporated into an ink, paint or coating system, the particle size is Dv(100)≦10 μm and the dispersity is ≦15 μm.

[0073] 47. The method of any one or more of paragraphs 31 to 46, wherein ultrasound is not used.

[0074] 48. The method of any one or more of paragraphs 31 to 47, excluding ultrasound.

[0075] 49. A pigment composition obtainable or obtainable by the method according to any one or more of paragraphs 31 to 48.

[0076] Furthermore, the present invention relates to a pigment composition comprising a mixed oxide of Fe(III) and Cr(III), said pigment composition having a brightness value in the range of 5 to 25; and Mixed oxides of Fe(III) and Cr(III) are: - It has the chemical formula (Cr,Fe)2O3, - has a hematite structure, - has a Dv(100) value in the range of 3 to 9 μm, and - Fe(III):Cr(III) ratio in the range of 74:26 to 58:42.

[0077] The mixed oxide preferably has a Dv(100) value in the range of 5 to 8 μm, preferably in the range of 5.5 to 7.5 μm, more preferably in the range of 6 to 7 μm.

[0078] The mixed oxide has a ratio of Fe(III):Cr(III) in the range of 70:30 to 58:42, preferably the mixed oxide has a ratio of Fe(III):Cr(III) of 67:33.

[0079] The pigment composition preferably has a brightness value in the range of 3-28, preferably in the range of 4-26, and more preferably in the range of 5-24.

[0080] Preferably, the lightness values ​​are determined in a melamine-based solvent-borne binder system, a water-based binder system, or a two-component polyurethane solvent-borne binder system.

[0081] The pigment composition has a color strength (CS): in the range of 90 to 120, preferably in the range of 95 to 115, more preferably in the range of 100 to 110 in a water-based binder system, or in the range of 105 to 155, preferably in the range of 115 to 145, more preferably in the range of 125 to 135 in a melamine-based solvent-borne binder system, or In a two-component polyurethane solvent-based binder system, the range is 100 to 130, preferably 105 to 125, and more preferably 110 to 120. It is preferable that the formula be:

[0082] The pigment composition has a dispersion (FOG): in the range of 5 to 25 μm, preferably in the range of 8 to 20 μm, more preferably in the range of 11 to 15 μm in a water-based binder system, or in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, more preferably in the range of 7 to 10 μm in a melamine-based solvent-borne binder system, or - in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, more preferably in the range of 7 to 10 μm in a two-component polyurethane solvent-based binder system It is preferable that the formula be:

[0083] The pigment composition is preferably free of compounds selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0084] It is preferred to exclude pigment compositions containing compounds selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0085] It is preferred that 90 to 100 mass %, preferably 95 to 100 mass %, more preferably 98 to 100 mass %, more preferably 99 to 100 mass % of the pigment composition contains a mixed oxide of Fe(III) and Cr(III).

[0086] It is preferred that the pigment composition further comprises a grinding aid, preferably the grinding aid is selected from the group consisting of oxides of silicon, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof, more preferably the grinding aid comprises an alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0087] Preferably, the oxide of silicon is fumed silica.

[0088] The pigment composition preferably contains 0.1 to 8 mass %, preferably 0.2 to 6 mass %, more preferably 0.25 to 4 mass %, and more preferably 0.5 to 2 mass % of the grinding aid relative to 100 mass % of the pigment composition.

[0089] The present invention also relates to a method for preparing a pigment composition, preferably a pigment composition according to any one of the specific preferred embodiments of the present invention, comprising the following steps: (i) providing a source of Cr(III) and a source of Fe(III) in a Fe(III):Cr(III) ratio ranging from 74:26 to 58:42; (ii) calcining the Cr(III) source and the Fe(III) source in a rotating device at a temperature in the range of 500 to 1300°C and a rotation speed in the range of 0.2 to 10 rpm to obtain a calcined mixture; (iii) providing a calcination mixture and optionally a grinding aid; (iv) dry-milling the calcined mixture and optional grinding aids in a jet mill at a pressure in the range of 0.5 to 5 bar and a classifying wheel speed in the range of 3000 to 7000 rpm; (v) obtaining a pigment composition comprising a mixed oxide of Fe(III) and Cr(III), the pigment composition having a brightness value in the range of 5 to 25. The present invention relates to a method comprising:

[0090] Prior to (iv), the method further comprises: (iii.1) Milling the provided calcined mixture and any grinding aids. It is preferred that the composition further comprises:

[0091] In (i), the Cr(III) source and the Fe(III) source are preferably provided in an Fe(III):Cr(III) ratio ranging from 70:30 to 58:42, and preferably the Cr(III) source and the Fe(III) source are provided in an Fe(III):Cr(III) ratio of 67:33.

[0092] It is preferred that the iron(III) source is selected from the group consisting of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, iron cyanide, and mixtures thereof, preferably from the group consisting of iron oxide, iron hydroxide, and mixtures thereof, more preferably the iron(III) source comprises iron hydroxide, more preferably iron hydroxide.

[0093] Preferably, the Cr(III) source is selected from the group consisting of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromates, chromium thiocyanide, chromium cyanide, and mixtures thereof, preferably from the group consisting of chromium oxide, chromium hydroxide, and mixtures thereof, more preferably the Cr(III) source comprises chromium oxide, more preferably is chromium oxide.

[0094] In (ii), it is preferable to add 0.1 to 8 mass %, preferably 0.2 to 6 mass %, more preferably 0.25 to 4 mass %, and more preferably 0.5 to 2 mass % of the grinding aid relative to 100 mass % of the fired mixture.

[0095] Preferably, the grinding aid is selected from the group consisting of fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof, more preferably the grinding aid comprises an alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0096] In (ii), the Cr(III) source and the Fe(III) source are preferably calcined at a temperature in the range of 500 to 1300°C, preferably in the range of 550 to 1250°C, and more preferably in the range of 610 to 1170°C.

[0097] In (ii), the rotation speed is preferably in the range of 1 to 5 rpm.

[0098] In (iv), the jet mill is preferably a fluidized bed counter jet mill.

[0099] In (iv), the dry milling is preferably carried out at a classifier wheel speed in the range of 4500 to 6000 rpm.

[0100] In (v), the pigment composition preferably has a brightness value in the range of 3-28, preferably in the range of 4-26, and more preferably in the range of 5-24.

[0101] In (v), the brightness value is preferably determined in a melamine-based solvent-borne binder system, a water-based binder system, or a two-component polyurethane solvent-borne binder system.

[0102] It is preferable not to use ultrasound.

[0103] The present invention also relates to a pigment composition obtainable or obtained by the method of any one of the specific preferred embodiments of the present invention.

[0104] The present invention also relates to an ink, paint or coating comprising or consisting of the pigment composition of any one of the specific preferred embodiments of the present invention.

[0105] The present invention also relates to the use of the pigment composition of any one of the specific preferred embodiments of the present invention as a component of an ink, paint or coating.

[0106] The present invention also relates to a method for preparing one or more of an ink, paint, or coating comprising using as an ingredient the pigment composition of any one of the specific preferred embodiments of the present invention.

[0107] Dissolvers are disc agitators used for dispersion, primarily in the paint and coatings, chemical and plastics industries. Pigment powders are dispersed in binder systems, whereby the dissolver functions to break up agglomerates of primary particles.

[0108] The pigment composition of the present invention corresponds to Pigment Brown 29. [Brief explanation of the drawings]

[0109] [Figure 1] Figure 1 shows four different particle size distributions. DETAILED DESCRIPTION OF THE INVENTION

[0110] The present invention is further represented by the following series of embodiments and combinations of embodiments resulting from the indicated dependencies and backward references. In particular, in each instance where a range of embodiments is mentioned, it should be noted that in the context of a term such as "the pigment composition of any one of embodiments 1 to 4," all embodiments within this range are expressly disclosed to those skilled in the art, i.e., this expression would be understood by those skilled in the art to be synonymous with "the pigment composition of any one of embodiments 1, 2, 3, and 4." Furthermore, it should be expressly noted that the following series of embodiments represent a suitably structured part of the general description directed to preferred aspects of the present invention, and thus adequately support, but do not represent, the scope of the claims of the present invention.

[0111] 1. A pigment composition comprising a mixed oxide of Fe(III) and Cr(III), having a brightness value in the range of 5 to 25; and Mixed oxides of Fe(III) and Cr(III) are: - It has the chemical formula (Cr,Fe)2O3, - has a hematite structure, - has a Dv(100) value in the range of 3 to 9 μm, and - A pigment composition having a ratio of Fe(III):Cr(III) in the range of 74:26 to 58:42.

[0112] 2. A pigment composition according to embodiment 1, in which the mixed oxide has a Dv(100) value in the range of 5 to 8 μm, preferably in the range of 5.5 to 7.5 μm, more preferably in the range of 6 to 7 μm.

[0113] 3. The pigment composition according to embodiment 1 or 2, wherein the mixed oxide has a ratio of Fe(III):Cr(III) in the range of 70:30 to 58:42, preferably the mixed oxide has a ratio of Fe(III):Cr(III) of 67:33.

[0114] 4. The pigment composition according to any one of embodiments 1 to 3, wherein the pigment composition has a brightness value in the range of 3 to 28, preferably in the range of 4 to 26, more preferably in the range of 5 to 24.

[0115] 5. The pigment composition according to any one of the preceding embodiments, preferably any one of the preceding embodiments, wherein the lightness value is determined in a melamine-based solvent-borne binder system, a water-based binder system, or a two-component polyurethane solvent-borne binder system.

[0116] 6. The pigment composition has a color strength (CS): in the range of 90 to 120, preferably in the range of 95 to 115, more preferably in the range of 100 to 110 in a water-based binder system, or in the range of 105 to 155, preferably in the range of 115 to 145, more preferably in the range of 125 to 135 in a melamine-based solvent-borne binder system, or In a two-component polyurethane solvent-based binder system, the range is 100 to 130, preferably 105 to 125, and more preferably 110 to 120. 6. The pigment composition of any one of embodiments 1 to 5, having

[0117] 7. The pigment composition has a dispersion index (FOG): in the range of 5 to 25 μm, preferably in the range of 8 to 20 μm, more preferably in the range of 11 to 15 μm in a water-based binder system, or in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, more preferably in the range of 7 to 10 μm in a melamine-based solvent-borne binder system, or - in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, more preferably in the range of 7 to 10 μm in a two-component polyurethane solvent-based binder system 7. The pigment composition of any one of embodiments 1 to 6, having

[0118] 8. The pigment composition of any one of embodiments 1 to 7, wherein the pigment composition does not contain a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0119] 9. The pigment composition of any one of embodiments 1 to 7, with the proviso that the pigment composition includes a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0120] 10. The pigment composition of any one of embodiments 1 to 9, wherein 90 to 100% by weight of the pigment composition comprises a mixed oxide of Fe(III) and Cr(III), preferably 95 to 100% by weight, more preferably 98 to 100% by weight, more preferably 99 to 100% by weight.

[0121] 11. The pigment composition of any one of the preceding embodiments, wherein the pigment composition further comprises a grinding aid, preferably the grinding aid is selected from the group consisting of oxides of silicon, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof, more preferably the grinding aid comprises an alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0122] 12. The pigment composition according to embodiment 11, wherein the pigment composition comprises 0.1 to 8% by mass, preferably 0.2 to 6% by mass, more preferably 0.25 to 4% by mass, and more preferably 0.5 to 2% by mass of the grinding aid, relative to 100% by mass of the pigment composition.

[0123] 13. A method for preparing a pigment composition, preferably the pigment composition according to any one of embodiments 1 to 12, comprising the following steps: (i) providing a source of Cr(III) and a source of Fe(III) in a Fe(III):Cr(III) ratio ranging from 74:26 to 58:42; (ii) calcining the Cr(III) source and the Fe(III) source in a rotating device at a temperature in the range of 500 to 1300°C and a rotation speed in the range of 0.2 to 10 rpm to obtain a calcined mixture; (iii) providing a calcination mixture and optionally a grinding aid; (iv) dry-milling the calcined mixture and optional grinding aids in a jet mill at a pressure in the range of 0.5 to 5 bar and a classifying wheel speed in the range of 3000 to 7000 rpm; (v) obtaining a pigment composition comprising a mixed oxide of Fe(III) and Cr(III), the pigment composition having a brightness value in the range of 5 to 25. A method comprising:

[0124] 14. Prior to (iv), (iii.1) Milling the provided calcined mixture and any grinding aids. 14. The method of embodiment 13, further comprising:

[0125] 15. The method of embodiment 13 or 14, wherein in (i), the Cr(III) source and the Fe(III) source are preferably provided in an Fe(III):Cr(III) ratio ranging from 70:30 to 58:42, and preferably the Cr(III) source and the Fe(III) source are provided in an Fe(III):Cr(III) ratio of 67:33.

[0126] 16. The method of any one of embodiments 13 to 15, wherein the source of iron(III) is selected from the group consisting of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, iron cyanide, and mixtures thereof, preferably from the group consisting of iron oxide, iron hydroxide, and mixtures thereof, more preferably the source of iron(III) comprises iron hydroxide, more preferably iron hydroxide.

[0127] 17. The method of any one of embodiments 13 to 16, wherein the Cr(III) source is selected from the group consisting of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromates, chromium thiocyanide, chromium cyanide, and mixtures thereof, preferably from the group consisting of chromium oxide, chromium hydroxide, and mixtures thereof; more preferably, the Cr(III) source comprises chromium oxide, more preferably is chromium oxide.

[0128] 18. The method according to any one of embodiments 13 to 17, wherein in (ii), 0.1 to 8% by weight, preferably 0.2 to 6% by weight, more preferably 0.25 to 4% by weight, more preferably 0.5 to 2% by weight of the grinding aid is added, relative to 100% by weight of the calcined mixture.

[0129] 19. The method of any one of embodiments 13 to 18, wherein the grinding aid is selected from the group consisting of fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof; more preferably, the grinding aid comprises an alkaline earth metal carbonate; preferably, the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof; more preferably, the alkaline earth metal carbonate comprises calcium carbonate; more preferably, it is calcium carbonate.

[0130] 20. The method of any one of embodiments 13 to 19, wherein in (ii), the Cr(III) source and the Fe(III) source are calcined at a temperature in the range of 500 to 1300°C, preferably in the range of 550 to 1250°C, and more preferably in the range of 610 to 1170°C.

[0131] 21. A method according to any one of embodiments 13 to 20, wherein in (ii), the rotation speed is in the range of 1 to 5 rpm.

[0132] 22. The method of any one of embodiments 13 to 21, wherein in (iv), the jet mill is a fluidized bed counter jet mill.

[0133] 23. The method of any one of embodiments 13 to 22, wherein in (iv), the dry milling is at a classifier wheel speed in the range of 4500 to 6000 rpm.

[0134] 24. The method of any one of embodiments 13 to 23, wherein in (v), the pigment composition has a brightness value in the range of 3 to 28, preferably in the range of 4 to 26, and more preferably in the range of 5 to 24.

[0135] 25. The method of any one of embodiments 13 to 24, wherein in (v), the lightness value is determined in a melamine-based solvent-borne binder system, a water-based binder system, or a two-component polyurethane solvent-borne binder system.

[0136] 26. A method according to any one of embodiments 13 to 25, which does not use ultrasound.

[0137] 27. The method of any one of embodiments 13 to 26, excluding ultrasound.

[0138] 28. A pigment composition obtainable or obtained by the method of any one of embodiments 1 to 12.

[0139] 29. An ink, paint or coating comprising or consisting of the pigment composition of any one of embodiments 1 to 12 and 28.

[0140] 30. Use of the pigment composition of any one of embodiments 1 to 12 and 28 as a component of an ink, paint or coating.

[0141] 31. A method for preparing one or more of an ink, a paint, or a coating, comprising using as an ingredient the pigment composition of any one of embodiments 1 to 12 and 28.

[0142] Although the present invention has been described in detail, including preferred embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the invention within the scope of the invention. [Example]

[0143] The present invention is further described by the following non-limiting examples which further illustrate the invention and are not intended to, nor should they be construed to, limit the scope of the invention.

[0144] Test Method Measurement method for particle size Dv(100) and Dv(50) Dynamic light scattering was used to measure particle size. A Malvern Mastersizer 3000 equipped with a Hydro MV automated wet dispersion unit was used. The agitator was set to 2000 rpm. Next, the pigment was added along with 5 mL of 5% sodium pyrophosphate solution as a dispersing aid. The pigment was added until 20% obscuration of the laser light was achieved. No ultrasound was applied before or during the measurement. The Mastersizer measured particle size using Fraunhofer diffraction with an additional correction for Mie scattering of small particles. Dv(100) was defined as the largest particle measured. This value was obtained by taking the μm channel in which particles were still detected on the analyzer (see Figure 1). Since measuring dispersity also determines the largest particle in a coating system, determining the Dv(100) of Pigment Brown 29 in water is a well-known method for estimating dispersity in many coating systems. Dv(100) must be less than 10 μm to achieve a dispersity of ≤15 μm in a coating system. The Dv(50) values ​​were determined according to the same method as described for the Dv(100) values.

[0145] Measurement method for degree of dispersion (FOG) To measure the degree of dispersion, a 50 μm grinding gauge (DIN EN ISO 1524:2013-06) was used. The coating system with the final pigment dispersed was applied to the gauge using a dissolver or shaker. The coating was then pulled down along the groove with a flat edge. The depth at which coarse particles or agglomerates became visible as pinholes or scratches on the surface of the coating system was read off the scale. This value represents the degree of dispersion.

[0146] Viscosity measurement method The viscosity was measured according to DIN 53019-1:2008-09 with an MCR302 rheometer equipped with a 50 mm cone-plate with a steepness angle of 2° and a measuring gap of 0.21 mm. The measuring temperature was 23°C.

[0147] The fast dispersing pigments of the present invention were tested in various binder test systems to evaluate their applications.

[0148] Melamine-based solvent-borne binder test system (Binder test system 1) To evaluate fast-dispersing pigments, a melamine-based solvent-borne binder test system was used. This system was a combination of a thermosetting hydroxylated acrylic resin, an OH-functional highly branched polyester, and a melamine-formaldehyde resin. The pigment:binder ratio for binder system 1 was 50:50. The viscosity was measured using a 7:3 mixture of xylol and butoxypropanol at a shear rate of 100 s. -1 The viscosity was adjusted to approximately 0.59 Pa·s using a dissolver dispersion process.

[0149] Two-component polyurethane solvent-based binder test system (binder test system 2) To evaluate fast-dispersing pigments, a two-component polyurethane solvent-borne binder test system was used. This system consisted of a hydroxy-functional acrylic resin for crosslinking with a polyisocyanate. The pigment:binder ratio for binder system 2 was 50:50. Viscosity was measured using a 2:1 mixture of xylol and methiopropamine at a shear rate of 100 s. -1The viscosity was adjusted to approximately 10.46 Pa·s using a dissolver. An aliphatic polyisocyanate was used as the curing agent. Dispersion was achieved using a dissolver dispersion process.

[0150] Water-based binder test system (Binder test system 3) To evaluate fast-dispersing pigments, a water-based test system was used. This system consisted of polyethylene glycol and water. The pigment:binder ratio for binder system 3 was 70:30. Viscosity was measured using a polyurethane / water mixture at a shear rate of 100 s. -1 The viscosity was adjusted to about 0.05 Pa-s with 1000 kJ / ml. Dispersion was achieved using a dissolver dispersion process.

[0151] Polyvinylidene fluoride (PVDF) resin-based binder test system (Binder test system 4) To evaluate fast-dispersing pigments, a PVDF resin-based binder test system was used. The pigment:binder ratio for binder system 4 was 50:50. The PVDF:acrylate ratio was adjusted to 70:30 and the shear rate was 100 s. -1 The viscosity was adjusted to 20.49 Pa·s. Dispersion was achieved using a dissolver dispersion process.

[0152] Dissolver Dispersion Method To prepare coating systems containing fast-dispersing or commercially available pigments, the pigments were dispersed in binder test systems 1-4 using a Getzmann Dispermat CA-40 equipped with a two-tooth disk. The pigments were dispersed at various intervals. The coatings were then used to prepare masstone and white reduction panels.

[0153] Preparation of White Reduction White reductions were prepared by combining a white lacquer with a dispersed pigment coating. The pigment preparation could be diluted with the respective binder system beforehand to facilitate processing. The ratio of white lacquer to pigment preparation was 5:1, and 4:1 for binder test system 4. For the white lacquer, TiO2 was dispersed in the respective binder system for 1 hour in a sealable container using a dispersing medium, e.g., glass beads with a diameter of 3 mm, and a shaker.

[0154] Preparation of full shade and white reduction panels The dispersed pigment coating and white reduction were used to prepare drawdowns on contrast boards using a film applicator. The film applicator was equipped with a 50 μm spiral applicator when preparing full shade panels and a 150 μm spiral applicator when preparing white reduction panels. The applicator was moved at a speed of 12.5 mm / s. The drawdowns were allowed to cure at room temperature or elevated temperature. Once the drawdowns were opaque, the procedure was repeated.

[0155] Lightness value (L) evaluation The term lightness value (L) used herein refers to lightness in the L*C*H color space (also known as CIELAB) defined by the International Commission on Illumination. Colorimetric evaluations were performed using a masstone panel in d / 8° or 8° / d geometry, including the specular component, according to spectroscopic methods (ISO 18314-1 (2015)), with a subsequently calculated 4% specular component excluded. Lightness values ​​were determined for illuminant D65 and a 10° standard observer according to ISO 11664-4 (2008).

[0156] Relative color strength (CS) evaluation White reduction panels were used to measure color depth by replicate matching according to ISO 18314-2 (2015). Relative color depth was evaluated for all four binder test systems against commercially available Sicopal Black 0095 after 60 minutes of shaker dispersion. For shaker dispersion, the binder system and pigment were placed in a sealable container, the pigment level was set to 20%, dispersing medium (e.g., 3 mm diameter glass beads) was added at a pigment coating:dispersing medium weight ratio of 1:1.5, and the container was loaded onto a shaker. The coatings were then used to prepare white reduction panels.

[0157] Example 1: Pigments of the invention 657 kg of Cr2O3 and 1500 kg of FeOOH were mixed and heated in a rotary kiln at 610-1170 °C. Next, 1% by weight of fumed silica was added as a grinding aid relative to 100% by weight of the resulting (Fe,Cr)2O3. The pigment was then dry-ground in a Hosokawa Alpine AFG400 jet mill at 2.6 bar air pressure and 5200 rpm. The Dv(100) value was 6 μm. The resulting pigment of the present invention was then tested in all binder test systems, compared with commercially available brown pigments Pigment Brown 29 (Sicopal Black 0095, BASF, purchased in 2022, Comparative Example 1), Dynamix Black 30C941 (Shepherd, purchased in 2023, Comparative Example 2), and Dynamix Black 30C940 (Shepherd, purchased in 2023, Comparative Example 3).

[0158] Example 2: Pigments of the invention 506 kg of Cr2O3 and 1155 kg of FeOOH were mixed and heated in a rotary kiln at 610-1170 °C. Next, 1% by weight of fumed silica and 0.75% by weight of calcium carbonate were added as grinding aids to 100% by weight of the resulting (Fe,Cr)2O3. The pigment was then dry-ground in a Hosokawa Alpine AFG400 jet mill at 2.5 bar air pressure and a classifier speed of 5500 rpm. The Dv(100) value was 6 μm. The resulting pigment of the present invention was then tested in all binder test systems in comparison with the commercially available brown pigments Pigment Brown 29 (Sicopal Black 0095, BASF, purchased in 2022, Comparative Example 1), Dynamix Black 30C941 (Shepherd, purchased in 2023, Comparative Example 2) and Dynamix Black 30C940 (Shepherd, purchased in 2023, Comparative Example 3).

[0159] [Table 1]

[0160] The commercial pigment Sicopal Black 0095 did not reach a dispersion of ≦15 μm in binder system 1, whereas the pigments of the invention reached this value after 20 minutes. The commercial pigments Dynamix Black 30C941 and 30C940 reached this value already after 10 minutes, whereas the pigments of the invention showed a significant increase in color strength already after 10 minutes of dispersion.

[0161] [Table 2]

[0162] Table 2 shows the measurements after dispersing the pigment in Binder Test System 2 for 30 minutes. When using a dissolver as the dispersing tool, the inventive pigment exhibited higher color strength compared to the commercial pigment and lower dispersion than Sicopal Black 0095.

[0163] [Table 3]

[0164] Table 3 shows measurements after dispersing the pigments several times with Dissolver in Binder Test System 3. While showing similar color strength and brightness values, the inventive pigment reached a dispersion of 15 μm after only 20 minutes, while the comparative pigment only reached a dispersion of 25 μm after 60 minutes.

[0165] [Table 4]

[0166] Table 4 shows the dispersion of inventive and comparative examples in binder test system 4. As with the other test binder systems, the inventive pigments exhibited superior dispersibility values ​​compared to the commercial pigments when dispersed in the dissolver system.

[0167] References - CN112194928A - JP2019183042A - US10844184B2 - CN104559439A - US9926415B2 - US9169399B2 - US8270064B2 - US20110219984A1 - JP5285307B2 - US8691332B2 - JP4783549B2 - US6758894B1 - KR20020072687A - JP2000104006A - JP11209558 - JP05285307 - US4388118A - US4426465A - US2811463A

Claims

1. 1. A Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, wherein the pigment exhibits a dispersibility index (DI) increase of ≧100%, or ≧200%, or ≧250% relative to a comparative example after treatment for 30 minutes using a dissolver dispersion process in a melamine-based solvent-borne binder system or a water-based binder system, wherein the DI satisfies Formula 1: [Equation 1] The pigment composition is determined by

2. 2. The pigment composition according to claim 1, wherein the color strength in the melamine-based solvent-borne binder system is in the range of 105 to 155, preferably in the range of 115 to 145, more preferably in the range of 125 to 135.

3. 2. The pigment composition according to claim 1, wherein the FOG in the melamine-based solvent-borne binder system is in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, more preferably in the range of 7 to 10 μm.

4. 2. The pigment composition according to claim 1, wherein the color value in the melamine-based solvent-borne binder system is in the range of 6 to 25, preferably in the range of 7 to 18, more preferably in the range of 8 to 12.

5.

5. 2. The pigment composition of claim 1, wherein the color strength in the water-based binder system is in the range of 90-120, preferably in the range of 95-115, more preferably in the range of 100-110.

6. 2. The pigment composition according to claim 1, wherein the FOG in the water-based binder system is in the range of 5 to 25 μm, preferably in the range of 8 to 20 μm, more preferably in the range of 11 to 15 μm.

7. 2. The pigment composition according to claim 1, wherein the color value in the water-based binder system is in the range of 3 to 12, preferably in the range of 4 to 10, more preferably in the range of 5 to 8.

8. 1. A Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, wherein the pigment exhibits a dispersibility index (DI) increase of ≧500%, or ≧600%, or ≧700%, or ≧800%, or ≧900% relative to a comparative example after 30 minutes of treatment using a dissolver dispersion process in a two-component polyurethane solvent-based binder system, wherein the DI satisfies the formula 1: [Equation 2] The pigment composition is determined by

9. 9. The pigment composition according to claim 8, having a color strength in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120.

10. 9. The pigment composition according to claim 8, wherein the FOG is in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, more preferably in the range of 7 to 10 μm.

11. 9. The pigment composition according to claim 8, having a lightness value in the range of 6 to 25, preferably in the range of 7 to 18, more preferably in the range of 8 to 11.

12. 1. A Pigment Brown 29 pigment composition comprising chromium and iron-based oxides having a hematite structure, wherein the pigment exhibits a dispersibility index (DI) increase of ≧1000%, or ≧2000%, or ≧2500% relative to a comparative example after treatment for 30 minutes using a dissolver dispersion process in a polyvinylidene fluoride (PVDF) resin-based binder system, wherein DI is determined by the formula 1: [Equation 3] Pigment Brown 29 pigment composition as determined by

13. 13. The pigment composition according to claim 12, having a colour strength in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120.

14. 13. The pigment composition according to claim 12, wherein the FOG is in the range of 2 to 15 μm, preferably in the range of 3 to 10 μm, more preferably in the range of 4 to 5 μm.

15. 13. The pigment composition according to claim 12, having a lightness value in the range of 6 to 25, preferably in the range of 7 to 18, more preferably in the range of 8 to 11.

16. 10. A pigment composition according to any preceding claim, wherein said comparative example is the commercially available Pigment Brown 29 described herein.

17. 10. A pigment composition according to any preceding claim, wherein Dv(100) is in the range of 3 to 9 μm, preferably in the range of 5 to 8, more preferably in the range of 5.5 to 7.5 μm, more preferably in the range of 6 to 7 μm.

18. 10. A pigment composition according to any preceding claim, wherein the chromium is selected from the group consisting of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanide, chromium cyanide and mixtures thereof, preferably from the group consisting of chromium oxide, chromium hydroxide and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably is chromium oxide.

19. 10. A pigment composition according to any preceding claim, wherein the iron-based oxide is selected from the group consisting of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, iron cyanide, and mixtures thereof, preferably from the group consisting of iron oxide, iron hydroxide, and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

20. 10. A pigment composition according to any of the preceding claims, wherein 90 to 100% by weight of the pigment composition comprises chromium and iron based oxides, preferably 95 to 100% by weight, more preferably 98 to 100% by weight, more preferably 99 to 100% by weight.

21. 10. A pigment composition according to any preceding claim, further comprising a grinding aid, preferably the grinding aid is selected from the group consisting of silicon oxide, alkaline earth metal oxide, alkaline earth metal carbonate, and mixtures thereof, more preferably the grinding aid comprises an alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

22. 22. The pigment composition according to claim 21, wherein 0.1 to 8% by weight, preferably 0.2 to 6% by weight, more preferably 0.25 to 4% by weight, more preferably 0.5 to 2% by weight of the pigment composition comprises the grinding aid, relative to 100% by weight of the pigment composition.

23. 10. The pigment composition of any preceding claim, wherein the pigment composition does not comprise a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

24. 10. A pigment composition according to any preceding claim, with the proviso that the pigment composition excludes a pigment composition comprising a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

25. 23. The pigment composition of claim 1, further comprising an additional transition metal compound.

26. 26. The composition of claim 25, wherein the additional transition metal compound is selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

27. 10. A pigment composition according to any preceding claim, wherein the raw materials are mixed in a ratio relative to their chromium content of from 1:99 to 50:50, from 10:90 to 30:70, or from 25:75 to 42:

58.

28. 28. An ink, paint or coating composition comprising the pigment of any one of claims 1 to 27.

29. 10. Use of a pigment composition according to any preceding claim as an ingredient in an ink, paint or coating.

30. 10. A method of preparing one or more of an ink, paint or coating, comprising using as an ingredient a pigment composition according to any preceding claim.

31. 1. A method for preparing a Pigment Brown 29 pigment composition, comprising a solid-state reaction between a mixture of a chromium source and an iron source, calcining the mixture at high temperature and then dry-milling, wherein the pigment exhibits a dispersibility index (DI) increase of ≧100%, or ≧200%, or ≧250% relative to a comparative example after treatment for 30 minutes using a dissolver dispersion process, wherein the DI satisfies Formula 1: [Equation 4] Determined by,method.

32. 32. The method of claim 31, further comprising pre-grinding after firing.

33. A method according to claim 31 or 32, wherein the mixture is calcined at a temperature in the range of from 500 to 1300°C, preferably in the range of from 550 to 1250°C, more preferably in the range of from 610 to 1170°C.

34. A method according to any of claims 31 to 33, wherein the mixture is fired in a rotating device at a rotation speed in the range of 0.2 to 10 rpm, preferably in the range of 1 to 5 rpm.

35. 35. A method according to any of claims 31 to 34, wherein the mixture is dry-milled in a jet mill, preferably a fluidized bed counter jet mill, at a pressure in the range of 0.5 to 5 bar, preferably in the range of 1.5 to 3 bar, and at a classifying wheel speed in the range of 3000 to 7000 rpm, preferably in the range of 3500 to 6500 rpm, more preferably in the range of 4000 to 6000 rpm.

36. 36. The method of any one of claims 31 to 35, wherein the chromium source and the iron source are mixed in an iron source:chromium source ratio in the range of 74:26 to 58:42, preferably in an iron source:chromium source ratio in the range of 70:30 to 58:42, more preferably in an iron source:chromium source ratio of 67:

33.

37. 37. The method of any one of claims 31 to 36, wherein the raw materials are mixed in a ratio related to their chromium content of from 1:99 to 50:50, from 10:90 to 30:70, or from 25:75 to 42:

58.

38. 38. The method of any of claims 31 to 37, wherein the composition further comprises an additional transition metal compound.

39. 39. The method of claim 38, wherein the further transition metal compounds are free of manganese, preferably the further transition metal compounds are free of manganese oxide, manganese trioxide and manganite.

40. 39. The method of claim 38, wherein the additional transition metal compound is selected from the group consisting of manganese oxide, manganese trioxide, manganite, or mixtures thereof.

41. 41. A method according to any one of claims 31 to 40, wherein the iron-based oxide is selected from the group consisting of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanide, iron cyanide, and mixtures thereof, preferably from the group consisting of iron oxide, iron hydroxide, and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

42. 42. The method of any one of claims 31 to 41, wherein the chromium is selected from the group consisting of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanide, chromium cyanide and mixtures thereof, preferably from the group consisting of chromium oxide, chromium hydroxide and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably is chromium oxide.

43. 43. The method of any of claims 31 to 42, further comprising one or more grinding aids.

44. 44. The method of claim 43, wherein the grinding aid agent is selected from the group consisting of fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof, preferably the grinding aid agent is selected from the group consisting of fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates, and mixtures thereof, more preferably the grinding aid agent comprises an alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from the group consisting of magnesium carbonate, calcium carbonate, and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

45. 45. The method according to claim 43 or 44, wherein the grinding aid is added in an amount of 0.1 to 8% by weight, preferably 0.2 to 6% by weight, more preferably 0.25 to 4% by weight, more preferably 0.5 to 2% by weight, based on 100% by weight of the calcined mixture.

46. 46. ​​The method of any one of claims 31 to 45, wherein when incorporated into an ink, paint or coating system, the particle size is Dv(100) < 10 μm and the dispersity is < 15 μm.

47. 47. The method of any one of claims 31 to 46, wherein ultrasound is not used.

48. 48. The method of any one of claims 31 to 47, conditioned by the exclusion of ultrasound.

49. 49. A pigment composition obtainable by the method of any one of claims 31 to 48.

Images