Rapidly dispersed pigment brown 29

Abstract

A chromium and iron oxide-based pigment with pigment brown 29 as the color index, which is dry milled and can be rapidly dispersed in different solvent and aqueous coatings.

Description

[0001] Ink and coating formulations are usually prepared by dispersing pigment powders in solvents or aqueous binder systems. Examples of dispersing equipment include ball mills, bead mills, rotor-stator dispersers, 3-roll mills, impeller mills or vibrators. The powder dispersion process is a very time-consuming and energy-consuming pursuit, usually requiring several hours to obtain the desired degree of dispersion. During the dispersion procedure, the pigment undergoes a series of complex, interrelated processes. A wetting process occurs in which the adsorbed air is removed from the particle surface and a solvate layer is formed. Deagglomeration occurs before, during and after the wetting process. The system requires external energy to break up the pigment agglomerates and achieve uniform particle distribution throughout the binder system during the dispersion process. Subsequently, the deagglomerated particles need to be stabilized to prevent flocculation. This can be achieved by applying a repulsive force, i.e., electrostatic force or steric force, between the individual particles.

[0002] Inorganic pigment powder is usually produced via solid state reaction, co-grinding reaction or precipitation reaction. At least one thermal treatment process is usually applied in the production process of inorganic pigment. This thermal treatment can be realized, for example, in a muffle furnace, a rotary furnace, a microwave oven, a shaft furnace or an electric arc furnace. This thermal treatment produces an agglomerate of pigment particles, which needs to be broken up during the dispersion process. Therefore, a grinding process is usually required in the manufacturing process of printing ink, paint or coating. Grinding can be realized, for example, by a ball mill, a hammer mill, a jet mill, a bead mill or a pen mill. In a wet grinding process, energy is applied to the pigment particles, resulting in deagglomeration and higher color intensity. However, when using a wet grinding process, a drying process is required subsequently, which results in the generation of new agglomerates, which must be broken up again during the dispersion process and result in a long processing time. Therefore, it is important to use dry grinding technology, i.e. a jet mill, a hammer mill, a dry ball mill or a pen mill, to eliminate the demand for subsequent drying processes.

[0003] Some properties of coating systems depend on the degree of dispersion, namely color strength or tinting power, hue, hiding power, viscosity, gloss and fineness of grind. In addition, some properties, such as color strength, depend so strongly on the degree of dispersion that it can be used to directly determine the degree of dispersion. Thus, when the color strength increases continuously even after long dispersion times, the dispersibility is still quite low. In contrast, when the increase in color strength approaches or reaches its maximum value, the dispersibility is considered to be high.

[0004] Furthermore, when the pigment is used in thin coatings, the final pigment should have a low fineness of grind value to ensure that no larger particles or agglomerates create poor printability, such as a rough surface on top of the applied coating.

[0005] The cited references do not deal with the target properties (brightness value, color intensity, grind fineness, dispersibility index). Furthermore, these references do not deal with the use of dry grinding technology to improve the dispersibility of the resulting pigments.

[0006] References that deal with improved dispersibility all use other additives such as surface modifiers or polymer composites or resins. In addition, references that describe easy dispersibility properties combine this property with wet to semi-dry pigments. In order to obtain the final easy dispersible pigment in powder form, an additional energy-consuming and time-consuming drying step would be required. However, an additional drying step would result in agglomeration and would invalidate the easy dispersibility property.

[0007] The color of (Fe,Cr)2O3-based pigments generally depends on their particle size and their chromium content. When the particle size Dv(50) is in the range of a few hundred nanometers, the pigment is brown. However, when the particle size Dv(50) increases to about 1 μm, the pigment becomes black.

[0008] US4643772A discloses a method for brown (Fe, Cr)2O3-based pigments, wherein transparent α-iron oxide and chromium salts having an orthorhombic bipyramidal crystal structure and a Dv(50) in the range of 0.1-0.4 μm are used as raw materials to obtain the brown color and easy dispersibility. The method is a precipitation method, wherein the chromium salt is dissolved and precipitated as chromium hydroxide with an alkali metal carbonate in the presence of iron oxide. The precipitate is then filtered out, 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 small particle size of the repeatedly ground pigment, the resulting pigment of US4643772A shows better dispersibility. However, it is still difficult to achieve a black color of a (Fe, Cr)2O3-based pigment with a particle size (Dv(50)) greater than 1 μm and good dispersibility.

[0009] GB1530740A discloses a method for obtaining Fe2O3-based pigments by using ferrous sulfate of the effluent of TiO2 processing cycle as iron source. In addition, different modifying elements are used to adjust the color of the final pigment. When chromium is used as the modifying element, a quite brown pigment is obtained. The Fe2O3-based pigment is obtained by a wet mixing method in which all raw materials are dissolved. The pigment received is not ground after calcination, so the pigment is rough and difficult to disperse due to many agglomerates, which need to be broken up in the dispersion process, which is time-consuming and energy-consuming. The pigment of the present invention is obtained by dry mixing the starting components to skip the extra drying step before the calcination process. In addition, only iron and chromium elements are used in the pigment of the present invention to obtain black pigments without adding any modifying elements required by GB1530740A.

[0010] Studies have shown that dry-milled pigments show only a slight increase in color intensity over time and low grind fineness values, thus providing a pigment with high dispersibility. We have found that by adjusting the grinding parameters it is possible to increase the dispersibility of this pigment and at the same time not change the color properties or even improve them.

[0011] The present invention solves the disadvantages of high energy consumption and time consumption by providing a specific pigment that can be dispersed with reduced time and energy requirements. The eco-friendly pigment provided by the present invention imparts similar or even superior performance characteristics to commercially available pigments, with the advantages of faster processing time and reduced energy consumption. In one embodiment, the pigment of the present invention has increased color strength and therefore has the possibility of using lower amounts of pigment.

[0012] Citation or identification of any document in this application is not an admission that it represents prior art to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Four different particle size distributions are depicted. These are measured using water as the dispersion medium. No ultrasound is applied before and during the measurement. The particle size distribution of the invention is shown as a square. The distribution is measured after 1 minute, 3 minutes and 5 minutes of dispersion. The commercially available pigment brown 29 Sicopal Black 0095 is shown as a triangle after 5 minutes of dispersion. The particle size distribution of the present invention shows a unimodal Gaussian curve, but Sicopal Black 0095 presents a bimodal Gaussian curve. In addition, it has larger particles because the curve reaches a minimum point at a larger particle size, resulting in a higher Dv (100) of 9.2 μm and a higher grinding fineness value in the coating system as defined herein. The pigment of the present invention shows a clearer particle size distribution due to its unimodal Gaussian curve. In addition, the distribution does not change over time, highlighting the fact that the pigment has been completely dispersed in water after 1 minute. In addition, the curve reaches a minimum point at a smaller particle size, resulting in a Dv (100) of 6 μm and a lower grinding fineness value in the coating system.

[0015] Detailed Description

[0016] In the present invention, chromium and iron-based oxides having a pigment index of Pigment Brown 29 and having a hematite crystal structure are synthesized by a solid-state reaction between a chromium source (e.g., one or more of chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanate, and chromium cyanide) and an iron source (e.g., one or more of iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanate, and iron cyanide). The raw materials are mixed in a weight ratio of 1:99-50:50, 10:90-30:70, or 25:75-42:58 related to the chromium content. In one embodiment, the composition may further include other transition metal compounds of period 4 elements or rare earth metals selected from oxides, hydroxides, oxalates, carbonates, sulfates, chlorides, bromides, iodides, nitrates, or thiocyanates. In another embodiment, the other transition metal and rare earth compounds are present in 0-10 wt % or 0-5 wt % of the total composition.

[0017] The mixture is then calcined at elevated temperatures, for example in a muffle furnace, a rotary furnace, a microwave oven, a shaft furnace or an electric arc furnace. The temperature is changed during the heat treatment and set to different temperatures. In one embodiment, the temperature range is 500-1300° C., preferably the temperature range is 550-1250° C., and more preferably the temperature range is 610-1170° C. After the heat treatment, the resulting pigment is pre-ground, for example, on a hammer mill or a crusher (i.e., a roller crusher, a jaw crusher, a gyratory crusher, an impact crusher or a cone crusher). When the calcined pigment does not show any thick blocks or large agglomerates, the pre-grinding step can be optionally omitted. Then, for example, a grinding aid such as fumed silica and alkaline earth metal carbonates are optionally added to the resulting pigment in a ratio of 0-10% by weight or 0-5% by weight. The resulting mixture is then dry-ground, for example, on a jet mill, a hammer mill, a dry ball mill or a pen mill. In a specific embodiment, the pigment of the present invention is ground by a jet mill, which is conducive to adjusting the particle size distribution in the final product. During the grinding process, the particle size distribution and the fineness of grind decrease. In one embodiment, the particle size should be Dv(100)≤10 μm and the fineness of grind≤15 μm.

[0018] Due to the reduction or more preferably elimination of agglomerates, the present invention shows reduced time and energy consumption when it is dispersed in a binder system. The system can be, for example, any solvent, aqueous or energy curing system. Due to the absence of agglomerates, it is necessary to apply less external energy to disperse the pigment. Therefore, a wetting process may occur first and reduce the required time. In addition, no additional grinding step is required during the dispersion process. The dispersion process can be carried out using a less complicated dispersion tool, such as a dissolver. Since no further processing steps are required, the ball is separated from the coating system, further reducing time consumption. Due to its high dispersibility, the color intensity reaches its maximum value only after a short dispersion. In addition, because the pigment can be fully dispersed in some coating systems, it shows that the color intensity increases compared to other commercially available pigments. Although the agglomerates are broken up during the dry grinding step, the main particles or aggregates remain intact and therefore the color performance, i.e., hue, chroma, hiding power, glossiness, brightness values ​​remain unchanged and show performance similar to commercially available pigments. The color performance depends on the coating system.

[0019] Method for determining the Dispersibility Index (DI) of Pigment Brown 29 using Equation 1:

[0020]

[0021] Equation 1 can be used to derive the dispersibility index (DI) of Inventive Example 1 Pigment Brown 29 dispersed in various binder systems relative to Comparative Example 1, where Comparative Example 1 represents commercially available Pigment Brown 29 (Pigment Brown 29, Sicopal Black 0095, BASF, purchased 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, Shepherd, purchased in 2023) and are not used to determine the dispersibility index (DI) of the present invention. According to the present invention, FOG represents fineness of grind.

[0022] In one embodiment, the binder system comprising the pigment of Example 1 has a dispersion index (DI) increase of ≥100% or ≥200% or ≥250% relative to the comparative example after a dispersion process using a disperser in a melamine-based solvent-borne binder system or an aqueous binder system for 30 minutes, and wherein the DI is determined according to Equation 1.

[0023] In another embodiment, the binder system comprising the pigment of Example 1 has a dispersion index (DI) increase of ≥1000% or ≥2000% or ≥2500% relative to the comparative example after a 30-minute dispersion process using a disperser in a melamine-based solvent-borne binder system or an aqueous binder system, and wherein the DI is determined according to Equation 1.

[0024] In another embodiment, the binder system comprising the pigment of Example 1 has a dispersion index (DI) increase of ≥500% or ≥600% or ≥700% or ≥800% or ≥900% relative to the comparative example after 30 minutes of dispersion process using a disperser in a two-component polyurethane solvent-based binder system, and wherein the DI is determined according to Equation 1.

[0025] In another embodiment, the binder system comprising the pigment of Example 1 has a dispersion index (DI) increased by ≥1000% or ≥2000% or ≥2500% relative to the comparative example after 30 minutes of dispersion process using a disperser in a polyvinylidene fluoride (PVDF) resin-based binder system, and wherein the DI is determined according to Equation 1.

[0026] The present invention further relates to a Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥1000% or ≥2000% or ≥2500% relative to a comparative example after 30 minutes using a disperser dispersion process in a melamine-based solvent-borne binder system or an aqueous binder system, and wherein the DI is determined according to Equation 1:

[0027]

[0028] Since Pigment Brown 29 is described as a very dark brown, almost black pigment, only the lightness value is needed to describe its color properties. In the CIELAB color space, the a and b values ​​reflect the four unique colors of human vision: red, green, blue and yellow. Therefore, for very dark brown or black pigments, the a and b values ​​are close to zero and are redundant. However, the lightness value directly indicates whether the pigment is white or black. It defines black as 0 and white as 100. Therefore, the lightness value of black should be as close to zero as possible. In addition, the color intensity, grinding fineness and particle size distribution Dv (100) are used to define the dispersibility of the pigment. If the pigment has a higher color intensity than a comparable pigment, this is equivalent to better dispersibility. The grinding fineness is similar. If the agglomerates or coarse particles of the pigment deagglomerate faster than the comparable pigment, this is equivalent to better dispersibility. Since the color intensity and grinding fineness depend on the coating system used, Dv (100) is not dependent on any coating system. Dv (100) describes the largest particles or agglomerates in the pigment. If Dv(100) is already small, it is not necessary to deagglomerate agglomerates or coarse particles and therefore a reduced dispersion time is necessary. Equation 1 contains all the parameters to obtain an index for evaluating the dispersibility of Pigment Brown 29. The higher the value, the better the dispersibility and the better the jetness. The index can be used to compare the dispersibility and applicability of different Pigment Brown 29 compounds.

[0029] The present invention is further described by the following numbered paragraphs:

[0030] 1. A Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥100% or ≥200% or ≥250% relative to a comparative example after a 30-minute dispersion process using a disperser in a melamine-based solvent-based binder system or an aqueous binder system, and wherein the DI is determined according to Equation 1:

[0031]

[0032] 2. The pigment composition of paragraph 1, wherein the color strength in the melamine-based solvent-borne binder system is in the range of 105-155, preferably in the range of 115-145, more preferably in the range of 125-135.

[0033] 3. The pigment composition of paragraph 1, wherein the FOG in the melamine-based solvent-borne binder system is in the range of 5-20 μm, preferably in the range of 6-15 μm, more preferably in the range of 7-10 μm.

[0034] 4. The pigment composition of paragraph 1, wherein the brightness value in the melamine-based solvent-borne binder system is in the range of 6-25, preferably in the range of 7-18, more preferably in the range of 8-12.5.

[0035] 5. The pigment composition of paragraph 1, wherein the color strength in the aqueous binder system is in the range of 90-120, preferably in the range of 95-115, more preferably in the range of 100-110.

[0036] 6. The pigment composition of paragraph 1, wherein the FOG in the aqueous binder system is in the range of 5-25 μm, preferably in the range of 8-20 μm, more preferably in the range of 11-15 μm.

[0037] 7. The pigment composition of paragraph 1, wherein the brightness value in the aqueous binder system is in the range of 3-12, preferably in the range of 4-10, more preferably in the range of 5-8.

[0038] 8. A Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥500% or ≥600% or ≥700% or ≥800% or ≥900% relative to a comparative example after 30 minutes of dispersion using a disperser dispersion process in a two-component polyurethane solvent-based binder system, and wherein the DI is determined according to Equation 1:

[0039]

[0040] 9. The pigment composition of paragraph 8, wherein the color strength is in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120.

[0041] 10. The pigment composition of paragraph 8, wherein the FOG is in the range of 5-20 μm, preferably in the range of 6-15 μm, more preferably in the range of 7-10 μm.

[0042] 11. The pigment composition of paragraph 8, wherein the brightness value is in the range of 6-25, preferably in the range of 7-18, more preferably in the range of 8-11.

[0043] 12. A Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥1000% or ≥2000% or ≥2500% relative to a comparative example after 30 minutes of dispersion using a disperser dispersion process in a polyvinylidene fluoride (PVDF) resin-based binder system, wherein the DI is determined according to Equation 1:

[0044]

[0045] 13. The pigment composition of paragraph 12, wherein the color strength is in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120.

[0046] 14. The pigment composition of paragraph 12, wherein the FOG is in the range of 2-15 μm, preferably in the range of 3-10 μm, more preferably in the range of 4-5 μm.

[0047] 15. The pigment composition of paragraph 12, wherein the brightness value is in the range of 6-25, preferably in the range of 7-18, and more preferably in the range of 8-11.

[0048] 16. The pigment composition of any preceding paragraph, wherein the comparative example is the commercially available Pigment Brown 29 described herein.

[0049] 17. The pigment composition of any preceding paragraph, wherein Dv(100) is in the range of 3-9 μm, preferably in the range of 5-8, more preferably in the range of 5.5-7.5 μm, more preferably in the range of 6-7 μm.

[0050] 18. The pigment composition of any preceding paragraph, wherein the chromium is selected from chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanate, chromium cyanide and mixtures thereof, preferably chromium oxide, chromium hydroxide and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably chromium oxide.

[0051] 19. The pigment composition of any preceding paragraph, 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 thiocyanate, iron cyanide and mixtures thereof, preferably iron oxide, iron hydroxide and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

[0052] 20. The pigment composition of any preceding paragraph, wherein 90-100 wt%, preferably 95-100 wt%, more preferably 98-100 wt%, more preferably 99-100 wt% of the pigment composition comprises chromium and an iron-based oxide.

[0053] 21. The pigment composition of any preceding paragraph, further comprising a grinding aid, preferably the grinding aid is selected from silicon oxides, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonates, preferably the alkaline earth metal carbonates are selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0054] 22. The pigment composition of paragraph 21, wherein based on 100 wt% of the pigment composition, 0.1-8 wt%, preferably 0.2-6 wt%, more preferably 0.25-4 wt%, more preferably 0.5-2 wt% of the pigment composition comprises the grinding aid.

[0055] 23. The pigment composition of any preceding paragraph, wherein the pigment composition does not comprise a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0056] 24. The pigment composition of any preceding paragraph, with the proviso that a pigment composition comprising a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof is excluded.

[0057] 25. The pigment composition of any of paragraphs 1 to 22, further comprising an additional transition metal compound.

[0058] 26. The composition of paragraph 25, wherein the additional transition metal compound is selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0059] 27. The pigment composition of any preceding paragraph, wherein the raw materials are mixed in a ratio of 1:99-50:50, 10:90-30:70 or 25:75-42:58 related to the chromium content.

[0060] 28. An ink, paint or coating comprising the pigment of any one of paragraphs 1 to 27.

[0061] 29. Use of a pigment composition according to any preceding paragraph as a component in an ink, paint or coating.

[0062] 30. A method of preparing one or more of an ink, a paint or a coating comprising using as a component a pigment composition according to any preceding paragraph.

[0063] 31. A method of preparing a Pigment Brown 29 pigment composition comprising a solid state reaction between a mixture of a chromium source and an iron source, wherein the mixture is calcined at an elevated temperature and then dry milled, and wherein the pigment has a dispersibility index (DI) increased by ≥100% or ≥200% or ≥250% relative to a comparative example after a 30 minute dispersion process using a disperser, and wherein the DI is determined according to Equation 1:

[0064]

[0065] 32. The method of paragraph 31, further comprising a step of pre-grinding after calcining.

[0066] 33. The process of paragraph 31 or 32, wherein the mixture is calcined at a temperature in the range of 500-1300°C, preferably in the range of 550-1250°C, more preferably in the range of 610-1170°C.

[0067] 34. The process of any of paragraphs 31-33, wherein the mixture is calcined in a rotating device at a rotation speed in the range of 0.2-10 rpm, preferably in the range of 1-5 rpm.

[0068] 35. The process of any of paragraphs 31 to 34, wherein the mixture is dry ground in a jet mill, preferably a fluidized bed reverse 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 a classifier 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.

[0069] 36. The method of any of paragraphs 31-35, wherein the chromium source and the iron source are mixed in an iron source:chromium source ratio in the range of 74:26-58:42, preferably an iron source:chromium source ratio in the range of 70:30-58:42, more preferably an iron source:chromium source ratio of 67:33.

[0070] 37. The method of any of paragraphs 31-36, wherein the raw materials are mixed in a ratio related to the chromium content of 1:99-50:50, 10:90-30:70 or 25:75-42:58.

[0071] 38. The method of any of paragraphs 31-37, wherein the composition further comprises an additional transition metal compound.

[0072] 39. The method of paragraph 38, wherein the other transition metal compound does not contain manganese, preferably the other transition metal compound does not contain manganese oxide, manganese trioxide and manganite.

[0073] 40. The method of paragraph 38, wherein the other transition metal compound is selected from manganese oxide, manganese trioxide, manganite or a mixture thereof.

[0074] 41. The method of any one of paragraphs 31-40, wherein the iron-based oxide is selected from iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanate, iron cyanide and mixtures thereof, preferably iron oxide, iron hydroxide and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

[0075] 42. The method of any of paragraphs 31-41, wherein the chromium is selected from chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanate, chromium cyanide and mixtures thereof, preferably chromium oxide, chromium hydroxide and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably chromium oxide.

[0076] 43. The method of any of paragraphs 31-42, further comprising one or more grinding aids.

[0077] 44. The method of paragraph 43, wherein the grinding aid is selected from fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures thereof, preferably the grinding aid is selected from fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0078] 45. The method of paragraph 43 or 44, wherein the grinding aid is added in an amount of 0.1-8 wt%, preferably 0.2-6 wt%, more preferably 0.25-4 wt%, more preferably 0.5-2 wt%, based on 100 wt% of the calcined mixture.

[0079] 46. ​​The method of any of paragraphs 31-45, wherein the particle size when incorporated into an ink, paint or coating system is Dv(100)≤10 μm and the fineness of grind is ≤15 μm.

[0080] 47. The method of any of paragraphs 31-46, wherein ultrasound is not used.

[0081] 48. The method of any of paragraphs 31-47, provided that ultrasound is excluded.

[0082] 49. A pigment composition obtainable or obtained by a process according to any one of paragraphs 31 to 48.

[0083] Furthermore, the present invention relates to a pigment composition comprising a mixed oxide of Fe(III) and Cr(III), wherein the pigment composition has a brightness value in the range of 5-25, and wherein the mixed oxide of Fe(III) and Cr(III):

[0084] -Complies with the chemical formula (Cr,Fe)2O3,

[0085] -Has a hematite structure,

[0086] - have a Dv(100) value in the range of 3-9 μm, and

[0087] -Having a Fe(III):Cr(III) ratio in the range of 74:26-58:42.

[0088] It is preferred that the mixed oxide has a Dv(100) value in the range of 5-8 μm, preferably in the range of 5.5-7.5 μm, more preferably in the range of 6-7 μm.

[0089] It is preferred that the mixed oxide has a Fe(III):Cr(III) ratio in the range of 70:30-58:42, preferably the mixed oxide has a Fe(III):Cr(III) ratio of 67:33.

[0090] It is preferred that the pigment composition has a brightness value in the range of 3-28, preferably in the range of 4-26, more preferably in the range of 5-24.

[0091] It is preferred that the brightness value is determined in a melamine-based solvent-borne adhesive system, a water-borne adhesive system or a two-component polyurethane solvent-borne adhesive system.

[0092] It is preferred that the pigment composition has a color strength (CS):

[0093] - in an aqueous binder system in the range of 90-120, preferably in the range of 95-115, more preferably in the range of 100-110; or

[0094] - in the range of 105-155, preferably in the range of 115-145, more preferably in the range of 125-135 in a melamine-based solvent-borne adhesive system; or

[0095] - in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120 in a two-component polyurethane solvent-based adhesive system.

[0096] It is preferred that the pigment composition has a fineness of grind (FOG):

[0097] - in an aqueous adhesive system in the range of 5-25 μm, preferably in the range of 8-20 μm, more preferably in the range of 11-15 μm; or

[0098] - in a melamine-based solvent-borne adhesive system in the range of 5-20 μm, preferably in the range of 6-15 μm, more preferably in the range of 7-10 μm; or

[0099] In a two-component polyurethane solvent-based adhesive system, in the range of 5-20 μm, preferably in the range of 6-15 μm, more preferably in the range of 7-10 μm.

[0100] It is preferred that the pigment composition does not comprise a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite and mixtures thereof.

[0101] It is preferred to exclude pigment compositions comprising a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite and mixtures thereof.

[0102] It is preferred that 90-100 wt. %, preferably 95-100 wt. %, more preferably 98-100 wt. %, more preferably 99-100 wt. % of the pigment composition comprises a mixed oxide of Fe(III) and Cr(III).

[0103] It is preferred that the pigment composition further comprises a grinding aid, preferably the grinding aid is selected from silicon oxide, alkaline earth metal oxide, alkaline earth metal carbonate and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0104] It is preferred that the silicon oxide is fumed silicon dioxide.

[0105] It is preferred that 0.1-8 wt%, preferably 0.2-6 wt%, more preferably 0.25-4 wt%, more preferably 0.5-2 wt% of the pigment composition contains the grinding aid, based on 100 wt% of the pigment composition.

[0106] The present invention also relates to a method for preparing a pigment composition, preferably a pigment composition according to any one of the specific and preferred embodiments of the present invention, comprising:

[0107] (i) providing a Cr(III) source and a Fe(III) source in a Fe(III):Cr(III) ratio in the range of 74:26-58:42;

[0108] (ii) calcining the Cr(III) source and the Fe(III) source in a rotating device at a temperature in the range of 500-1300° C. and a rotation speed in the range of 0.2-10 rpm, and obtaining a calcined mixture;

[0109] (iii) providing the calcined mixture and optionally a grinding aid;

[0110] (iv) dry grinding the calcined mixture and the optional grinding aid in a jet mill at a pressure in the range of 0.5-5 bar and a classifier wheel speed in the range of 3000-7000 rpm;

[0111] (v) obtaining a pigment composition comprising a mixed oxide of Fe(III) and Cr(III), wherein the pigment composition has a brightness value in the range of 5-25.

[0112] Preferably, before (iv), the method further comprises:

[0113] (iii.1) Grinding the provided calcined mixture and optionally a grinding aid.

[0114] It is preferred that in (i) the Cr(III) source and the Fe(III) source are provided in a Fe(III):Cr(III) ratio in the range of 70:30-58:42, preferably the Cr(III) source and the Fe(III) source are provided in a Fe(III):Cr(III) ratio of 67:33.

[0115] It is preferred that the Fe(III) source is selected from iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanate, iron cyanide and mixtures thereof, preferably iron oxide, iron hydroxide and mixtures thereof, more preferably the iron(III) source comprises iron hydroxide, more preferably iron hydroxide.

[0116] Preferably, the Cr(III) source is selected from chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanate, chromium cyanide and mixtures thereof, preferably chromium oxide, chromium hydroxide and mixtures thereof, more preferably the Cr(III) source comprises chromium oxide, more preferably chromium oxide.

[0117] It is preferred to add 0.1-8 wt%, preferably 0.2-6 wt%, more preferably 0.25-4 wt%, more preferably 0.5-2 wt% of the grinding aid in (ii), based on 100 wt% of the calcined mixture.

[0118] Preferably, the grinding aid is selected from fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0119] It is preferred that the Cr(III) source and the Fe(III) source in (ii) are calcined at a temperature in the range of 500-1300°C, preferably in the range of 550-1250°C, more preferably in the range of 610-1170°C.

[0120] It is preferred that in (ii) the rotation speed is in the range of 1-5 rpm.

[0121] It is preferred that in (iv) the jet mill is a fluidised bed reverse jet mill.

[0122] It is preferred that the dry grinding in (iv) is at a classifier wheel speed in the range of 4500-6000 rpm.

[0123] It is preferred that in (v) the pigment composition has a brightness value in the range of 3-28, preferably in the range of 4-26, more preferably in the range of 5-24.

[0124] It is preferred that the brightness value in (v) is determined in a melamine-based solvent-borne adhesive system, a water-borne adhesive system or a two-component polyurethane solvent-borne adhesive system.

[0125] Preferably, ultrasound is not used.

[0126] The present invention also relates to a pigment composition obtainable or obtainable by a process according to any one of the specific and preferred embodiments of the present invention.

[0127] The present invention also relates to an ink, a paint or a coating comprising or consisting of the pigment composition according to any one of the specific and preferred embodiments of the present invention.

[0128] The present invention also relates to the use of the pigment composition according to any of the specific and preferred embodiments of the present invention as a component in inks, paints or coatings.

[0129] The present invention also relates to a method of preparing one or more of an ink, a paint or a coating comprising using as a component the coating composition of any one of the specific and preferred embodiments of the present invention.

[0130] Dispersers are disk agitators used primarily for dispersing in the paint and coatings industry, the chemical industry and the plastics industry. The pigment powder is dispersed in a binder system, wherein the disperser has the function of breaking up agglomerates of primary particles.

[0131] The pigment composition of the present invention corresponds to Pigment Brown 29.

[0132] The invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the indicated dependencies and back-references. It is particularly noted that in each case where a range of embodiments is mentioned, for example with respect to a term such as "a pigment composition according to any one of embodiments 1-4", it is intended to explicitly disclose each embodiment within the range to the skilled person, i.e. the wording of the term should be understood by the skilled person as being synonymous with "a pigment composition according to any one of embodiments 1, 2, 3 and 4". Furthermore, it is expressly noted that the following set of embodiments represents a suitable constituent part of the general description relating to preferred aspects of the invention and therefore appropriately supports, but does not represent, the claims of the invention.

[0133] 1. A pigment composition comprising a mixed oxide of Fe(III) and Cr(III), wherein the pigment composition has a brightness value in the range of 5-25, and wherein the mixed oxide of Fe(III) and Cr(III):

[0134] -Complies with the chemical formula (Cr,Fe)2O3,

[0135] -Has a hematite structure,

[0136] - have a Dv(100) value in the range of 3-9 μm, and

[0137] -Having a Fe(III):Cr(III) ratio in the range of 74:26-58:42.

[0138] 2. The pigment composition of embodiment 1, wherein the mixed oxide has a Dv(100) value in the range of 5-8 μm, preferably in the range of 5.5-7.5 μm, more preferably in the range of 6-7 μm.

[0139] 3. The pigment composition of embodiment 1 or 2, wherein the mixed oxide has a Fe(III):Cr(III) ratio in the range of 70:30-58:42, preferably the mixed oxide has a Fe(III):Cr(III) ratio of 67:33.

[0140] 4. The pigment composition of any one of embodiments 1-3, wherein the pigment composition has a brightness value in the range of 3-28, preferably in the range of 4-26, more preferably in the range of 5-24.

[0141] 5. The pigment composition of any one of embodiments 1 to 4, preferably embodiment 1 or 4, wherein the brightness value is determined in a melamine-based solvent-borne binder system, an aqueous binder system or a two-component polyurethane solvent-borne binder system.

[0142] 6. The pigment composition of any one of embodiments 1 to 5, wherein the pigment composition has a color strength (CS):

[0143] - in an aqueous binder system in the range of 90-120, preferably in the range of 95-115, more preferably in the range of 100-110; or

[0144] - in the range of 105-155, preferably in the range of 115-145, more preferably in the range of 125-135 in a melamine-based solvent-borne adhesive system; or

[0145] - in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120 in a two-component polyurethane solvent-based adhesive system.

[0146] 7. The pigment composition of any one of embodiments 1 to 6, wherein the pigment composition has a fineness of grind (FOG):

[0147] - in an aqueous adhesive system in the range of 5-25 μm, preferably in the range of 8-20 μm, more preferably in the range of 11-15 μm; or

[0148] - in a melamine-based solvent-borne adhesive system in the range of 5-20 μm, preferably in the range of 6-15 μm, more preferably in the range of 7-10 μm; or

[0149] In a two-component polyurethane solvent-based adhesive system, in the range of 5-20 μm, preferably in the range of 6-15 μm, more preferably in the range of 7-10 μm.

[0150] 8. The pigment composition of any one of embodiments 1 to 7, wherein the pigment composition does not comprise a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof.

[0151] 9. The pigment composition of any one of embodiments 1 to 7, with the proviso that a pigment composition comprising a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof is excluded.

[0152] 10. The pigment composition according to any one of embodiments 1 to 9, wherein 90-100% by weight, preferably 95-100% by weight, more preferably 98-100% by weight, more preferably 99-100% by weight of the pigment composition comprises a mixed oxide of Fe(III) and Cr(III).

[0153] 11. The pigment composition of any one of embodiments 1 to 10, wherein the pigment composition further comprises a grinding aid, preferably the grinding aid is selected from silicon oxide, alkaline earth metal oxide, alkaline earth metal carbonate and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0154] 12. The pigment composition of embodiment 11, wherein 0.1-8 wt%, preferably 0.2-6 wt%, more preferably 0.25-4 wt%, more preferably 0.5-2 wt% of the pigment composition comprises the grinding aid, based on 100 wt% of the pigment composition.

[0155] 13. A method for preparing a pigment composition, preferably a pigment composition according to any one of embodiments 1 to 12, the method comprising:

[0156] (i) providing a Cr(III) source and a Fe(III) source in a Fe(III):Cr(III) ratio in the range of 74:26-58:42;

[0157] (ii) calcining the Cr(III) source and the Fe(III) source in a rotating device at a temperature in the range of 500-1300° C. and a rotation speed in the range of 0.2-10 rpm, and obtaining a calcined mixture;

[0158] (iii) providing the calcined mixture and optionally a grinding aid;

[0159] (iv) dry grinding the calcined mixture and the optional grinding aid in a jet mill at a pressure in the range of 0.5-5 bar and a classifier wheel speed in the range of 3000-7000 rpm;

[0160] (v) obtaining a pigment composition comprising a mixed oxide of Fe(III) and Cr(III), wherein the pigment composition has a brightness value in the range of 5-25.

[0161] 14. The method of embodiment 13, wherein before (iv) the method further comprises:

[0162] (iii.1) Grinding the provided calcined mixture and optionally a grinding aid.

[0163] 15. The method of embodiment 13 or 14, wherein in (i) the Cr(III) source and the Fe(III) source are provided in a Fe(III):Cr(III) ratio in the range of 70:30-58:42, preferably the Cr(III) source and the Fe(III) source are provided in a Fe(III):Cr(III) ratio of 67:33.

[0164] 16. The method of any one of embodiments 13 to 15, wherein the Fe(III) source is selected from iron oxide, iron hydroxide, iron oxalate, iron carbonate, iron sulfate, iron chloride, iron bromide, iron iodide, iron nitrate, iron thiocyanate, iron cyanide and mixtures thereof, preferably iron oxide, iron hydroxide and mixtures thereof, more preferably the iron(III) source comprises iron hydroxide, more preferably iron hydroxide.

[0165] 17. The method of any one of embodiments 13-16, wherein the Cr(III) source is selected from chromium oxide, chromium hydroxide, chromium oxalate, chromium carbonate, chromium sulfate, chromium chloride, chromium bromide, chromium iodide, chromium nitrate, chromic acid, chromium chromate, chromium thiocyanate, chromium cyanide and mixtures thereof, preferably chromium oxide, chromium hydroxide and mixtures thereof, more preferably the Cr(III) source comprises chromium oxide, more preferably chromium oxide.

[0166] 18. The process according to any one of embodiments 13 to 17, wherein 0.1-8 wt. %, preferably 0.2-6 wt. %, more preferably 0.25-4 wt. %, more preferably 0.5-2 wt. % of the grinding aid is added in (ii), based on 100 wt. % of the calcined mixture.

[0167] 19. The method of any one of embodiments 13-18, wherein the grinding aid is selected from fumed silica, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonate, preferably the alkaline earth metal carbonate is selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

[0168] 20. The method according to any one of embodiments 13 to 19, wherein the Cr(III) source and the Fe(III) source are calcined in (ii) at a temperature in the range of 500-1300° C., preferably in the range of 550-1250° C., more preferably in the range of 610-1170° C.

[0169] 21. The method according to any one of embodiments 13 to 20, wherein in (ii) the rotation speed is in the range of 1-5 rpm.

[0170] 22. The process according to any one of embodiments 13 to 21, wherein in (iv) the jet mill is a fluidized bed reverse jet mill.

[0171] 23. The process according to any one of embodiments 13 to 22, wherein the dry grinding in (iv) is at a classifier wheel speed in the range of 4500-6000 rpm.

[0172] 24. The method according to any one of embodiments 13 to 23, wherein in (v) the pigment composition has a brightness value in the range of 3-28, preferably in the range of 4-26, more preferably in the range of 5-24.

[0173] 25. The method according to any one of embodiments 13 to 24, preferably embodiment 13 or 24, wherein in (v) the brightness value is determined in a melamine-based solvent-borne adhesive system, an aqueous adhesive system or a two-component polyurethane solvent-borne adhesive system.

[0174] 26. The method according to any one of embodiments 13 to 25, wherein ultrasound is not used.

[0175] 27. The method according to any one of embodiments 13 to 26, with the proviso that ultrasound is excluded.

[0176] 28. A pigment composition obtainable or obtained by a process according to any one of embodiments 1 to 12.

[0177] 29. An ink, paint or coating comprising or consisting of the pigment composition according to any one of embodiments 1-12 and 28.

[0178] 30. Use of the pigment composition according to any one of embodiments 1 to 12 and 28 as a component in inks, paints or coatings.

[0179] 31. A method of preparing one or more of an ink, a paint or a coating comprising using the pigment composition according to any one of embodiments 1-12 and 28 as a component.

[0180] The invention has been described in detail, including preferred embodiments thereof. However, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the invention that fall within the scope and spirit of the invention. Example

[0181] The present invention is further described by the following non-limiting examples, which further illustrate the invention and are neither intended nor should they be construed as limiting the scope of the invention.

[0182] Test Method

[0183] Method for determining particle size Dv(100) and Dv(50)

[0184] To determine the particle size, dynamic light scattering was used. A Malvern Mastersizer 3000 equipped with a Hydro MV automatic wet dispersion unit was used. The stirrer was set to 2000 rpm. The pigment was then treated with 5 mL of a 5% sodium pyrophosphate solution as a dispersing aid. The pigment was added until a 20% laser obscuration was achieved. No ultrasound was applied before or during the measurement. The Mastersizer uses Fraunhofer diffraction with an additional correction for Mie scattering on small particles to determine the particle size. Dv(100) is defined as the largest particle measured. This value is obtained by selecting the μm channel in which particles are still detected by the analysis device (see Figure 1 ). Because measuring the grind fineness also determines the largest particles in the coating system, determining the Dv(100) of Pigment Brown 29 in water is a well-known method for estimating the grind fineness in many coating systems. The Dv(100) should be less than 10 μm to achieve a grind fineness of ≤ 15 μm in the coating system. The Dv(50) value is determined according to the same method as described for the Dv(100) value.

[0185] Methods for determining fineness of grind (FOG)

[0186] To determine the fineness of grind, a 50 μm grind meter (DIN EN ISO 1524: 2013-06) is used. The coating system in which the final pigment is dispersed using a disperser or vibrator is applied to the grind meter. The coating is then scraped along the flat edge of the groove. The depth at which coarse particles or agglomerates are visible as pinholes or scratches on the surface of the coating system is read from the scale. This value represents the fineness of grind.

[0187] Methods for determining viscosity

[0188] The viscosity was determined in accordance with DIN 53019-1:2008-09 with an MCR 302 rheometer equipped with a 50 mm cone-plate with a cone angle of 2° and a measuring gap of 0.21 mm. The measuring temperature was 23°C.

[0189] The fast dispersing pigments of the present invention were tested in different adhesive test systems to evaluate their applications: Melamine-based solvents Adhesive Test System (Adhesive Test System 1)

[0190] To evaluate fast dispersing pigments, a melamine-based solvent-borne adhesive test system was used. This system is a combination of a thermosetting hydroxylated acrylic resin, an OH-functional hyperbranched polyester, and a melamine / formaldehyde resin. The pigment:binder ratio of adhesive system 1 was 50:50. The viscosity was adjusted to 100 s with a 7:3 mixture of xylene and butoxypropanol. -1 The viscosity is about 0.59 Pa·s at a shear rate of . The dispersion is achieved using a disperser dispersion process.

[0191] Two-component polyurethane solvent-based adhesive test system (adhesive test system 2)

[0192] To evaluate the rapid dispersion of pigments, a two-component polyurethane solvent-based adhesive test system was used. The system consisted of a hydroxy-functional acrylic resin for crosslinking with a polyisocyanate. The pigment:binder ratio of Adhesive System 2 was 50:50. The viscosity was adjusted to a 2:1 mixture of xylene and methiopropamine to a viscosity of 100 s -1 The viscosity of the precipitate was about 10.46 Pa·s at a shear rate of . As a curing agent, an aliphatic polyisocyanate was used. Dispersion was achieved using a disperser dispersion process.

[0193] Water-based adhesive test system (adhesive test system 3)

[0194] To evaluate the rapid dispersion of pigments, a water-based adhesive test system was used. This system consisted of polyethylene glycol and water. The pigment:binder ratio of adhesive system 3 was 70:30. The viscosity was adjusted to a viscosity of 100 s with a mixture of polyurethane and water. -1 The viscosity is about 0.05 Pa·s at a shear rate of . The dispersion is achieved using a disperser dispersion process.

[0195] Polyvinylidene fluoride (PVDF) resin-based adhesive test system (Adhesive test system 4)

[0196] To evaluate fast dispersing pigments, a PVDF resin-based adhesive test system was used. The pigment:adhesive ratio of adhesive system 4 was 50:50. The PVDF:acrylate ratio was adjusted to 70:30 to achieve a dispersion of 100 s. -1 The viscosity is 20.49 Pa·s at a shear rate of . Dispersion is achieved using a disperser dispersion process.

[0197] Dispersing method of disperser

[0198] To prepare a coating system containing the fast dispersing pigment or a commercially available pigment, the pigment was dispersed in the adhesive test systems 1 to 4 using a Getzmann Dispermat CA-40 equipped with a double toothed disc. The pigment was dispersed at different intervals. The coating was then used to prepare a primary color palette as well as a white washout palette.

[0199] Preparation of white diluted material

[0200] The white washdown was prepared by combining white paint with the dispersed pigment coating. The pigment preparation may be diluted with the corresponding binder system beforehand to improve processability. The white paint: pigment preparation ratio was 5:1 and 4:1 for binder test system 4. For the white paint, the TiO2 was dispersed in the corresponding binder system in a sealable container using a dispersion medium, such as glass beads with a diameter of 3 mm and a vibrator for 1 hour.

[0201] Preparation of full-tone and white-washed panels

[0202] Dispersed pigment coating and white washdown were used to prepare drawdowns on control panels using a film coater. The film coater was equipped with a 50 μm spiral coater when preparing full-tone panels and a 150 μm spiral coater when preparing white washdown panels. The coater moved at a speed of 12.5 mm / s. The drawdowns were cured at room temperature or elevated temperature. The procedure was repeated when the drawdown was not opaque.

[0203] Evaluation of brightness value (L)

[0204] The term lightness value (L) used herein refers to the lightness in the L*C*H color space (also known as CIELAB) described by the Commission Internationale de l'Eclairage. The chromaticity evaluation is performed according to the spectral method (ISO 18314-1 (2015)) with d / 8° or 8° / d geometry including the specular component and excluding the 4% specular component of the subsequent calculation using the primary color palette. The lightness value is determined according to ISO 11664-4 (2008) with illuminant D65 and a 10° standard observer.

[0205] Evaluation of relative color intensity (CS)

[0206] CS was measured by iterative matching of color depth according to ISO 18314-2 (2015) using a white washdown panel. Relative CS was evaluated against commercial Sicopal Black 0095 after 60 minutes of shaker dispersion for all 4 binder test systems. For shaker dispersion, the binder system and the pigment were combined in a sealable container; the tinting level was set to 20%; a dispersion medium (e.g., glass beads with a diameter of 3 mm) was added at a weight ratio of 1:1.5 pigment coating: dispersion medium and the container was loaded into the shaker. The coating was then used to prepare a white washdown panel.

[0207] Example 1: Pigment of the present invention

[0208] 657 kg Cr2O3 and 1500 kg FeOOH were mixed in a rotary furnace and heated at 610-1170°C. Then 1 wt% fumed silica was added as a grinding aid based on 100 wt% of the obtained (Fe,Cr)2O3. The pigment was then dry ground on an AFG400 jet mill from Hosokawa Alpine at 2.6 bar gas pressure and a classifier speed of 5200 rpm. The Dv(100) value reached 6 μm. The obtained pigment of the present invention was then tested in comparison with the commercially available brown pigment 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) in all adhesive test systems.

[0209] Example 2: Pigment of the present invention

[0210] 506 kg Cr2O3 and 1155 kg FeOOH were mixed in a rotary furnace and heated at 610-1170°C. Then, 1 wt% fumed silica and 0.75 wt% calcium carbonate were added as grinding aids based on 100 wt% of the obtained (Fe,Cr)2O3. The pigment was then dry ground on an AFG400 jet mill from Hosokawa Alpine at 2.5 bar pressure and a classifier speed of 5500 rpm. The Dv(100) value reached 6 μm. The obtained pigment of the present invention was then tested in comparison with the commercially available brown pigment 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) in all adhesive test systems.

[0211] Table 1: Dispersion process of using a disperser in adhesive system 1 in Inventive Example 1 relative to Comparative Examples 1-3

[0212]

[0213] While the commercial pigment Sicopal Black 0095 was not able to achieve a grind fineness of ≤15 μm in binder system 1, the pigment according to the invention achieved this value after 20 minutes. The commercial pigments Dynamix Black 30C941 and 30C940 already achieved this value after 10 minutes, whereas the pigment according to the invention already showed a drastic increase in color intensity after 10 minutes of dispersion.

[0214] Table 2: Dispersion process of using a disperser in adhesive system 2 in Inventive Example 1 relative to Comparative Examples 1-3

[0215]

[0216]

[0217] Table 2 shows the measured values ​​after 30 minutes of dispersing the pigments in the adhesive test system 2. When a disperser is used as a dispersing tool, the pigments according to the invention have a higher color intensity than commercial pigments and a lower grinding fineness than Sicopal Black 0095.

[0218] Table 3: Dispersion process of using a disperser in adhesive system 3 in Inventive Example 1 relative to Comparative Examples 1-3

[0219]

[0220] Table 3 shows the measured values ​​after dispersing the pigments for several dispersing times using a disperser in the binder test system 3. Despite showing similar color intensity and brightness values, the pigment according to the invention reaches a grinding fineness value of 15 μm after only 20 minutes, while the comparative pigment only reaches a grinding fineness value of 25 μm even after 60 minutes.

[0221] Table 4: Dispersion process of using a disperser in adhesive system 4 in Example 1 of the invention relative to Comparative Example 1

[0222]

[0223] Table 4 shows the inventive and comparative dispersions in Binder Test System 4. Similar to the other binder test systems, the inventive pigments when dispersed in the disperser system showed superior fineness of grind values ​​compared to commercial pigments.

[0224] References:

[0225] -CN112194928A

[0226] -JP2019183042A

[0227] -US10844184B2

[0228] -CN104559439A

[0229] -US9926415B2

[0230] -US9169399B2

[0231] -US8270064B2

[0232] -US20110219984A1

[0233] -JP5285307B2

[0234] -US8691332B2

[0235] -JP4783549B2

[0236] -US6758894B1

[0237] -KR20020072687A

[0238] -JP2000104006A

[0239] -JP11209558

[0240] -JP05285307

[0241] -US4388118A

[0242] -US4426465A

[0243] -US2811463A

Claims

1. A Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥100% or ≥200% or ≥250% relative to a comparative example after a 30-minute dispersion process using a disperser in a melamine-based solvent-based binder system or an aqueous binder system, and wherein the DI is determined according to Equation 1:

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

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

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

5.

5. The pigment composition of claim 1, wherein the color strength in the aqueous 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. The pigment composition of claim 1, wherein the FOG in the aqueous binder system is in the range of 5-25 μm, preferably in the range of 8-20 μm, more preferably in the range of 11-15 μm.

7. The pigment composition of claim 1, wherein the brightness value in the aqueous binder system is in the range of 3-12, preferably in the range of 4-10, more preferably in the range of 5-8.

8. A Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥500% or ≥600% or ≥700% or ≥800% or ≥900% relative to a comparative example after 30 minutes of dispersion using a disperser dispersion process in a two-component polyurethane solvent-based binder system, and wherein the DI is determined according to Equation 1:

9. The pigment composition of claim 8, wherein the color strength is in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120.

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

11. The pigment composition of claim 8, wherein the brightness value is in the range of 6-25, preferably in the range of 7-18, more preferably in the range of 8-11.

12. A Pigment Brown 29 pigment composition comprising chromium and an iron-based oxide having a hematite structure, wherein the pigment has a dispersion index (DI) increased by ≥1000% or ≥2000% or ≥2500% relative to a comparative example after 30 minutes of dispersion using a disperser dispersion process in a polyvinylidene fluoride (PVDF) resin-based binder system, wherein the DI is determined according to Equation 1:

13. The pigment composition of claim 12, wherein the color intensity is in the range of 100-130, preferably in the range of 105-125, more preferably in the range of 110-120.

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

15. The pigment composition of claim 12, wherein the brightness value is in the range of 6-25, preferably in the range of 7-18, more preferably in the range of 8-11.

16. The pigment composition of any preceding claim, wherein the comparative example is the commercially available Pigment Brown 29 as described herein.

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

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 thiocyanate, chromium cyanide and mixtures thereof, preferably chromium oxide, chromium hydroxide and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably chromium oxide.

19. The pigment composition of 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 thiocyanate, iron cyanide and mixtures thereof, preferably iron oxide, iron hydroxide and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

20. The pigment composition of any preceding claim, wherein 90-100 wt%, preferably 95-100 wt%, more preferably 98-100 wt%, more preferably 99-100 wt% of the pigment composition comprises chromium and iron-based oxides.

21. The pigment composition of any preceding claim, further comprising a grinding aid, preferably the grinding aid is selected from silicon oxides, alkaline earth metal oxides, alkaline earth metal carbonates and mixtures thereof, more preferably the grinding aid comprises alkaline earth metal carbonates, preferably the alkaline earth metal carbonates are selected from magnesium carbonate, calcium carbonate and mixtures thereof, more preferably the alkaline earth metal carbonate comprises calcium carbonate, more preferably calcium carbonate.

22. The pigment composition of claim 21, wherein 0.1-8 wt%, preferably 0.2-6 wt%, more preferably 0.25-4 wt%, more preferably 0.5-2 wt% of the pigment composition comprises the grinding aid, based on 100 wt% of the pigment composition.

23. 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. The pigment composition of any preceding claim, with the proviso that a pigment composition comprising a compound selected from the group consisting of manganese oxide, manganese trioxide, manganite, and mixtures thereof is excluded.

25. The pigment composition of any one of claims 1 to 22, further comprising an additional transition metal compound.

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. A pigment composition according to any preceding claim, wherein the raw materials are mixed in a ratio of 1:99 to 50:50, 10:90 to 30:70 or 25:75 to 42:58 in relation to the chromium content.

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

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

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

31. A method of preparing a Pigment Brown 29 pigment composition comprising a solid state reaction between a mixture of a chromium source and an iron source, wherein the mixture is calcined at an elevated temperature and then dry milled, and wherein the pigment has a dispersibility index (DI) increased by ≥100% or ≥200% or ≥250% relative to a comparative example after a 30 minute dispersion process using a disperser, and wherein the DI is determined according to Equation 1:

32. The method of claim 31 further comprising the step of pre-grinding after calcining.

33. The process of claim 31 or 32, wherein the mixture is calcined at a temperature in the range of 500-1300°C, preferably in the range of 550-1250°C, more preferably in the range of 610-1170°C.

34. The process according to any one of claims 31 to 33, wherein the mixture is calcined 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. The process according to any one of claims 31 to 34, wherein the mixture is dry ground in a jet mill, preferably a fluidized bed reverse 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 a classifier 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. 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 74:26-58:42, preferably in the range of 70:30-58:42, more preferably in the range of 67:

33.

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

58.

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

39. The method of claim 38, wherein the other transition metal compound does not comprise manganese, preferably the other transition metal compound does not comprise manganese oxide, manganese trioxide and manganite.

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

41. The method of 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 thiocyanate, iron cyanide and mixtures thereof, preferably iron oxide, iron hydroxide and mixtures thereof, more preferably the iron-based oxide comprises iron hydroxide, more preferably iron hydroxide.

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 thiocyanate, chromium cyanide and mixtures thereof, preferably chromium oxide, chromium hydroxide and mixtures thereof, more preferably the chromium comprises chromium oxide, more preferably chromium oxide.

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

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

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

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

48. The method of any one of claims 31-47, with the proviso that ultrasound is excluded.

49. A pigment composition obtainable or obtained by a process according to any one of claims 31 to 48.

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