Bismuth vanadate pigments

Abstract

A bismuth vanadate pigment is provided which pigment is doped with a combination of Mg, Al and P and optionally an element E, wherein the molar ratios of the Bi, V, Mg, Al, P and E correspond to a formula
Bi Mg.sub.a Al.sub.b E.sub.c V.sub.d P.sub.e O.sub.f(I)
wherein E is selected from the group consisting of Be, Ca, Sr, Ba, Zr, Mo, Ce and a combination thereof; 0.001a0.2; 0.001b0.2; 0c1.7; 0.5d2.3; 0.001e0.5; and f denotes the number of oxygen atoms for satisfying the valence requirements of the cations. The pigment may be used as colorant in various applications, especially in coloring high molecular weight organic material, for example, coating compositions, paints, printing inks, liquid inks, plastics, films, fibers, or glazes for ceramics or glass.

Claims

1. A bismuth vanadate pigment of formula
Bi Mg.sub.a Al.sub.b E.sub.c V.sub.d P.sub.e O.sub.f(I) wherein E is selected from the group consisting of Ca, Sr, Ba, Zr, Mo, Ce and a combination thereof; 0.001a0.2; 0.001b0.2; 0c1.7; 0.5d2.3; 0.001e0.5; and f denotes the number of oxygen atoms for satisfying the valence requirements of the cations.

2. The bismuth vanadate pigment according to claim 1, wherein 0.001a0.15; 0.001b0.15; 0c1.5; 0.8d2.3; and 0.01e0.4.

3. The bismuth vanadate pigment according to claim 1, wherein E is selected from the group consisting of Ca, Zr, Mo, Ce and a combination thereof; and 0.001c1.5.

4. The bismuth vanadate pigment according to claim 1, wherein E is selected from the group consisting of Ca, Zr, Mo and a combination thereof; 0.001c0.5 and 0.8d1.5.

5. The pigment according to claim 1, wherein E is Ca and/or Zr; and 0.001c0.5.

6. The pigment according to claim 1, wherein E is Ca and/or Zr; and 0.01c0.5.

7. The pigment according to claim 1, wherein E is Zr and Mo; 0.001a0.15; 0.001b0.15; 0.01c0.5; 0.8d1.5; and 0.01e0.4.

8. The pigment according to claim 1, wherein E is Ce or a combination of Zr and Ce or a combination of Ca and Ce; 0.001a0.15; 0.001b0.15; 0.01c1.5; 0.8d2.3; and 0.01e0.4.

9. The pigment according to claim 1, wherein E is a combination of Ca, Zr and Ce; 0.001a0.15; 0.001b0.15; 0.01c1.5; 0.8d2.3; and 0.01e0.4.

10. The pigment according to claim 1, wherein E is a combination of Ca, Zr and Mo; 0.001a0.15; 0.001b0.15; 0.01c0.5; 0.8 5d1.5; and 0.01e0.4.

11. The pigment according to claim 1, wherein c is 0; 0.001a0.15; 0.001b0.15; 0.8d1.5; and 0.01e0.4.

12. The pigment according to claim 1, wherein vanadium is present as V(V) and V(IV) in a molar ratio of from 1:0.01 to 1:0.3.

13. A process of manufacturing the bismuth vanadate pigment of formula (I) as defined in claim 1, which process comprises the steps of a) treating an alkaline vanadate solution with an acidic bismuth salt solution in the presence of soluble salts of Mg, Al, and optionally of E and/or V(IV), and soluble phosphates in a pH range of from 0.1 to 10 to form a precipitate, b) calcining the precipitate, and c) grinding to form pigment particles.

14. A coating composition, a paint, a printing ink, a liquid ink, plastics, a film, a fiber, a glaze for ceramics or glass, which is colored with the pigment as defined in claim 1.

15. A process for coloring a coating compositions, a paint, a printing ink, a liquid ink, plastics, a film, a fiber, a glaze for ceramics or glass, which process comprises adding thereto the pigment as defined in claim 1.

16. The pigment according to claim 1, wherein 0.001b0.15.

17. The pigment according to claim 1, wherein 0.005b0.12.

18. The pigment according to claim 1, wherein 0.005a0.12; 0.005b0.12; 0.01c1.5; 0.85d2.2; and 0.01e0.4.

19. The pigment according to claim 1, wherein E is Ca and Zr; and 0.001c0.5.

Description

EXAMPLES

(1) The colorimetric assessment is assessed on coating films prepared as follows. A mixture of 24.6 g of each pigment and 75.4 g of an hydroxyl functional acrylic resin is shaken on a Skandex machine for 120 min with 150 g of glass beads (3 mm in diameter), then hidingly applied to a chromated aluminum sheet, flashed off and heated at 80 C. for 2 hours.

(2) The weather fastnesses are evaluated in the mass tone by means of accelerated weathering for 114 days in a Xenon test 1200 without turnaround run (from Atlas) in accordance with DIN EN ISO 11341. The evaluation is undertaken in accordance with DIN EN 20105-A02 (gray scale for assessing change in color). The assessment scale ranges from 0 (miserable weather fastness) to 5 (excellent weather fastness).

(3) To determine the CIELAB values of hue h [] , chrome C* and lightness L*, the coating films obtained (in masstone) are measured. Evaluation takes place on the data obtained at a measurement angle of 45.

(4) The color strength is determined in white reduction, consisting of 1 part of the instant bismuth vanadate pigment+3 parts of rutile Kronos 2310 using the above-mentioned spectrophotometer. For white reductions the millbase is mixed with a white enamel (TiO.sub.2 20% by weight in acrylic resin) in a ratio of 1 to 5 (pigment/TiO.sub.2), then mixed with a polyisocyanate (75% solution) in a ratio of 1.96 to 1 (resin/isocyanate) and also hidingly applied to a chromated aluminum sheet, flashed off and heated at 80 C. for 2 hours.

(5) The values obtained are shown in Table 1.

Example 1

(6) A mixture of 1000 g of water, 297 g of an aqueous sodium vanadate solution (7 wt. % of V), 16 g of nitric acid (65 wt. % strength) and 7 g of phosphoric acid (85 wt. % strength) is provided with stirring. The temperature of said mixture is kept below 10 C., and the pH is kept above 9 by adding an aqueous solution of sodium carbonate (15 wt. % strength) with stirring within 10 min. 350 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added within 60 min. The pH of the mixture is then adjusted to 4.5 within 1 hour by adding a sodium hydroxide solution (5 wt. % strength) and subsequently nitric acid (65 wt. %).

(7) Solutions of 2 g of Ca(OH).sub.2 (96%) in 33 g of water and 0.4 g of MgO (100%) in 24 g of water are added to the suspension within 15 min while stirring. The pH is increased to above 4 using NaOH (25 wt. %) within 90 min and is then kept above 4.6 using NaOH (5 wt. %). This is followed by adding 4 g of Al(NO.sub.3).sub.3.9H.sub.2 O (98%) in 33 g of water and a solution of 7 g of sodium perborate (97%) in 29 g of water while the pH is kept below 5 using NaOH (5 wt. % strength) and HNO.sub.3(65 wt. %). The resulting suspension is then heated to a temperature of 95 C. while maintaining pH 4.7. After about 40 min, the suspension turns deep yellow, and the pH briskly rises to 7.5. The suspension is stirred at 95 C. to a constant pH. After cooling to room temperature, the product is filtered off, washed salt-free and dried at 110 C. in a through-circulation drying oven. The thus obtained product is wet-milled to a particle size of about 1 m, filtered, washed and dried followed by heat-treating the product at 550 C. for 1 hour, wet-grinding in water to an average particle size of about 0.8 m and drying at 110 C.

Example 2

(8) 295 g of NaVO.sub.3 (7 wt. % of V) are suspended in 840 g of water, and the suspension is stirred for 30 min, followed by adding 16 g of HNO.sub.3 (65 wt. %) with ice cooling to give a pH below 9. 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 5 min at a temperature below 8 C. 350 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added within 60 min while the pH drops to 0.5, and the pH is adjusted to greater than 4 using 150 g of Na.sub.2CO.sub.3 (15 wt. %) within 90 min to obtain a beige suspension.

(9) A solution of 1.8 g of Ca(OH).sub.2 (a 96%) in 24 g of water and a solution of 0.4 g of MgO (100%) in 34 g of water are added to the suspension within 15 min resulting in pH 0.5. The pH is increased to above 4 using 170 g of NaOH (25 wt. %) within 90 min and is then kept above 4.6 using NaOH (5 wt. %).

(10) A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 7 g of sodium perborate (97%) in 29 g of water are then added. The resulting mixture is heated at 95 C. for 80 min to a constant pH and then cooled to room temperature. The product is filtered, washed and wet-milled to a particle size of about 1.5 m, dried at 110 C. for 1 hour and then calcined at 550 C. The product is again wet-milled in water to a final particle size of about 0.7 m.

Example 3

(11) A mixture of 1000 g of water, 295 g of an aqueous sodium vanadate solution (7 wt. % of V), 16 g of nitric acid (65 wt. %) and 4 g of phosphoric acid (85 wt. %) is provided with stirring and cooling. The temperature of said mixture is kept below 10 C. and the pH is kept at 8.7 by adding an aqueous solution of sodium carbonate (15 wt. %) with stirring within 10 min. 352 g of an acidic solution of bismuth nitrate (23.75 wt. % of Bi) are added within 60 min. The pH of the mixture is then adjusted to 4.5 within 1 hour with an aqueous solution of sodium hydroxide (5 wt. %) and nitric acid (65 wt. %). 0.8 g of calcium hydroxide (96%) and 0.2 g of magnesium hydroxide (as aqueous solutions) are added, wherein the pH drops to 0.3. A pH>4 is achieved by adding of 170 g of NaOH (25 wt. %). At almost constant pH, 2 g of aluminum nitrate (in water) and 1.7 g of sodium perborate (97%) (in water) are added while maintaining the pH below 5 using NaOH (5 wt. %).

(12) The resulting suspension is then heated to 95 C. while maintaining pH 4.7. After about 60 min the suspension turns deep yellow, and the pH briskly rises to 7. The suspension is stirred at 95 C. to constant pH for 80 min and then cooled to room temperature. The product is treated in the same way as Example 1.

Example 4

(13) A mixture of 1000 g of water and 297 g of NaVO.sub.3 (7 wt. % of V) is provided with stirring and cooling (8 C.). 21 g of HNO.sub.3 (65 wt. %) and 7g of H.sub.3PO.sub.4 (85 wt. % strength) are added within 5 min. 351 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added to the mixture within 60 min wherein the pH drops to 0.5 and a beige suspension is obtained.

(14) A solution of 1.54 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.4 g of MgO (100%) in 34 g of water are then added within 15 min. The pH is increased to above 4.5 using 170 g of an aqueous NaOH solution (25 wt. %) within 1.5 hours and then maintained at 4.6 using NaOH (5 wt. %).

(15) A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 3 g of sodium perborate (97%) in 29 g of water are added within 5 min. The mixture is heated at 95 C. for 80 min while maintaining a constant pH and then cooled to room temperature. The product is treated in the same way as Example 1.

Example 5

(16) A mixture of 840 g of water, 297 g of aqueous sodium vanadate solution (7 wt. % of V), 16 g of HNO.sub.3 (65 wt. %) and 5 g of H.sub.3PO.sub.4 (85 wt. %) is provided with stirring. The mixture is cooled to 8 C., and the pH decreased to 6.8 after about 5 min. 352 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added to the mixture within 60 min, the pH drops to 0.3 giving a beige suspension. A solution of 0.4 g of MgO (100%) in 34 g of water is added within 15 min. The pH is adjusted to above 4 using 170 g of an aqueous NaOH solution (25 wt. %) within 1.5 hours and then maintained at 4.6 using NaOH (5 wt. %).

(17) A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water, and a solution of 3 g of sodium perborate (97%) in 29 g of water are then added within 5 min. The mixture is heated at 95 C. for 83 min while maintaining a constant pH and then cooled to room temperature. Any pH changes are adjusted using NaOH (5 wt. %). The yellow product is filtered, washed, dried and the resulting filter cake is processed in two different ways.

(18) (a) A part of the filter cake is wet-milled in water to a particle size of about 1.24 m and dried at 115 C., followed by calcination at 550 C. for 1 hour and wet-milling again to a particle size of about 0.9 m.

(19) (b) The second part is directly calcined at 550 C. for 1 hour, then wet-milled in water to a particle size of about 0.8 m followed by drying at 110 C. in a through air circulation oven.

Example 6

(20) A suspension of 264 g of NaVO.sub.3 (7 wt. % of V) in 1000 g of H.sub.2O is cooled to 8 C. with stirring. A solution of 135 g of zirconium oxynitrate pentahydrate (ZrO(NO.sub.3).sub.2.5H.sub.2O) (27.2 wt. % of Zr) is added within 10 min while stirring, leading to an orange suspension. 16 g of HNO.sub.3 (65 wt. %) and 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 5 min and the resulting mixture is stirred for 30 min. 176 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) and 478 g of an aqueous solution of cerium carbonate (Ce.sub.2(CO.sub.3).sub.3.H.sub.2O) (10 wt. % of Ce) are added within 60 min, while stirring, the pH drops to 0.5, and a yellow suspension is formed after about 30 min.

(21) A solution of 1.5 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.4 g of MgO (100%) in 34 g of water are added within 15 min. The pH is adjusted to 4.7 using 170 g of an aqueous NaOH solution (25 wt. %) within 90 minutes and is then kept at above 4.6 using NaOH (5 wt. %). A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 30 g of water and a solution of 3 g of sodium perborate (97%) in 29 g of water are added within 10 min. The mixture is then heated at 90 C. for 80 min while maintaining a constant pH and then cooled to room temperature. The yellow pigment is treated in the same way as Example 1.

(22) The pigment shows a E of 2.1 after 2374 hours of accelerated weathering.

Example 7

(23) A suspension of 264 g of NaVO.sub.3 (7 wt. % of V) in 1000 g of water is cooled to 8 C. A solution of 135 g of zirconium oxynitrate pentahydrate (27.2 wt. % of Zr) is added within 10 min while stirring. 16 g of HNO.sub.3 (65 wt. %) and 7 g of H.sub.3PO.sub.4 (85 wt. %) are added after 5 min of stirring, the pH drops to 6.5. 316 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) and 102 g of an aqueous solution of vanadium (IV) oxide sulphate pentahydrate (VOSO.sub.4.5H.sub.2O) (10 wt. % of V) are added within 60 min while stirring, the pH drops to 0.3, and a yellow suspension is formed after about 30 min.

(24) A solution of 0.8 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.2 g of MgO (100%) in 34 g of water are added within 15 min. The pH is adjusted to 4.8 using 185 g of an aqueous NaOH solution (25 wt. %) within 90 min and then kept at above 4.6 using NaOH (5 wt. %). A solution of 2 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 1.6 g of sodium perborate (97%) in 29 g of water are added within 10 min. The mixture is heated at 95 C. for 80 min while maintaining a constant pH. Any pH changes are adjusted using NaOH (5 wt. %).

(25) A part of the filter cake (a) is calcined at 550 C. for 1 hour and then wet-milled in water to a particle size of about 0.9 m. The second part (b) is wet-milled in water to a particle size of about 1 m and then dried, followed by calcining at 550 C. for 1 hour, wet-milling in water to a particle size of about 0.9 m and drying at 110 C.

Example 8

(26) A suspension of 880 g of water and 294 g of an aqueous NaVO.sub.3 solution (6.95 wt. % of V) is stirred for 30 min. 135 g of an aqueous solution of zirconium oxynitrate pentahydrate (27.2 wt. % of Zr) is added within 10 min while stirring, wherein an orange suspension is formed at pH 9.4. The mixture is cooled with ice cooling and 16 g of HNO.sub.3 (65 wt. %) are added, followed by adding 7 g of H.sub.3PO.sub.4 (85 wt. %) after 5 min at pH of about 6.9. 7 g of an aqueous Na.sub.2CO.sub.3 solution (15 wt. %) and 101 g of HNO.sub.3 (65 wt. %) are used within 20 min to stabilise the pH at 7. 316 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) and 78 g of an aqueous solution of sodium molybdate (Na.sub.2MoO.sub.4O.2H.sub.2O) (10 wt. % Mo) are added within 60 min while stirring, the pH drops to 0.5, and a yellow suspension is formed after 30 min.

(27) A solution of 0.8 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.2 g of MgO (100%) in 34 g of water are added within 15 min. The pH is adjusted to above 4 using 195 g of an aqueous NaOH solution (25 wt. %) within 90 min and then maintained at above 4.5 using NaOH (5 wt. %).

(28) A solution of 2 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 1.6 g of sodium perborate (97%) in 29 g of water are added, and the pH increases to 4.6. The mixture is heated at 95 C. for 80 min while maintaining a constant pH using NaOH (5 wt. %) and then cooled to room temperature. The resulting yellow suspension is filtered, the solid is washed, wet-milled in water to a particle size of about 1 m and dried at 110 C.

(29) A part of the product is calcined at 500 C. (a) and the second part is calcined at 550 C. (b). Each sample is then wet-milled to a particle size of about 0.7 m and dried at 110 C. for 1 hour in a through air circulation oven.

Example 9

(30) A suspension of 880 g of H.sub.2O, and 296 g of an aqueous NaVO.sub.3 solution (6.95 wt. % of V) is stirred for 30 min. 16 g of HNO.sub.3 (65 wt. %) are added under ice cooling giving a pH of 8.9. 14 g of H.sub.3PO.sub.4 (85 wt %) are added within 5 min at a temperature of below 8 C. 352 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added to the mixture within 60 min and the pH drops to 0.5, which is increased to 4.6 using 210 g of Na.sub.2CO.sub.3 (15 wt. %) within 90 min. A solution of 3.1 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.8 g of MgO (100%) in 34 g of water are added within 15 min, giving a pH of 0.5. The pH is increased to 4.7 using 170 g of NaOH (25 wt. %) within 90 min and then maintained at above 4.6 using NaOH (5 wt. %).

(31) A solution of 8 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and 7 g of sodium perborate (97%) in 29 g of water are then added decreasing the pH to 3.9. The mixture is heated at 95 C. for 80 min while maintaining a constant pH and then cooled to room temperature. The product is treated in the same way as Example 1.

Example 10

(32) A suspension of 297 g of an aqueous NaVO.sub.3 solution (7 wt. %) in 880 g of water is stirred for 30 min. 21 g of HNO.sub.3 (65 wt. %) are added under ice cooling. 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 5 min at a temperature of below 8 C. 351 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added to the mixture within 60 min, and the pH drops to 0.3, which is increased to 4.6 using 150 g of Na2CO.sub.3 (15 wt. %) within 90 min.

(33) A solution of 1.5 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.8 g of MgO (100%) in 34 g of water are added within 15 min giving a pH of 0.5. The pH is increased to 4.6 using 180 g of NaOH (25 wt. %) within 90 min and then maintained at above 4.6 using NaOH (5 wt. %).

(34) A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 3.2 g of sodium perborate (97%) in 29 g of water are then added decreasing the pH to 3.9, which is increased to 4.7 using NaOH (5 wt. %). The mixture is heated at 95 C. for 80 min, while maintaining a constant pH and then cooled to room temperature. The resulting yellow product is filtered, washed and wet-milled in water to a particle size of about 1.5 m. The pigment is then dried at 110 C. for 1 hour and then calcined at 550 C. for 1 hour followed by wet-milling in water to a final particle size of about 0.7 m.

Example 11

(35) A mixture of 1000 g of water and 264 g of an aqueous NaVO.sub.3 solution (7 wt. % of V) is cooled to 8 C. with stirring. 135 g of an aqueous solution of zirconium oxynitrate pentahydrate (27.2 wt. % of Zr) is added within 10 min while stirring leading to an orange suspension at pH 9.4. 16 g of HNO.sub.3 (65 wt. %) and 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 10 min wherein the pH decreased to 6.8 after about 5 min. 316 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) and 78 g of an aqueous sodium molybdate solution (10 wt. % of Mo) are added within 60 min while stirring, and the pH drops to 0.5 and a yellow suspension is formed after about 30 min.

(36) A solution of 0.8 g of Ca(OH).sub.2. (96%) in 24 g of water and a solution of 0.2 g of MgO (100%) in 34 g of water are added within 15 min, and the pH is adjusted to above 4.5 using 165 g of an aqueous NaOH (25 wt. %) within 90 min and then maintained at above 4.6 using NaOH (5 wt. %). A solution of 1.9 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water, and a solution of 1.6 g of sodium perborate (97%) in 29 g of water are added. The mixture is heated at 95 C. for 80 min, while maintaining a constant pH (about 4.7) and then cooled to room temperature. The yellow product is filtered, washed and dried at 110 C. in a through air circulation for 1 hour followed by calcining at 550 C. and then wet-milling in water to a particle size of about 0.9 m.

Example 12

(37) A suspension of 1000 g of water and 297 g of an aqueous NaVO.sub.3 solution (7 wt. % of V) is cooled to 8 C. with stirring. 16 g of HNO.sub.3 (65 wt. %) and 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 5 min. 352 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) is added within 60 min and the pH drops to 0.3, which is adjusted to 4.5 using 150 g of Na.sub.2CO.sub.3 (15 wt. %) within 90 min. A solution of 1.5 g of Ca(OH).sub.2(96%) in 24 g of water and a solution of 0.4 g of MgO (100%) in of 34 g of water are added within 15 min giving a pH of 0.5. The pH is adjusted to 4.5 using 170 g of NaOH (25 wt. %) within 90 min and then maintained at above 4.5 using NaOH (5 wt. %).

(38) A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 7 g sodium perborate (97%) in 29 g of water are then added decreasing the pH to 3.9. The mixture is heated at 95 C. for 80 min, while maintaining a constant pH and then cooled to room temperature. The yellow product is filtered, washed, wet-milled in water to a particle size of about 1.5 m, dried at 110 C. in a through-circulation drying oven for 1 hour followed by calcining at 550 C. and wet-milling to a final particle size of about 0.7 m. The pigment shows a E of 1.8 after 4000 hours of accelerated weathering.

Example 13

(39) A suspension of 840 g of water and 296 g of an aqueous NaVO.sub.3 solution (6.95 wt. % of V) is stirred for 30 min with stirring at 8 C. 16 g of HNO.sub.3 (65 wt. %) are added followed by 7 g of H.sub.3PO.sub.4 (85 wt. %) within 5 min. 352 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) is added to the mixture within 60 min, and the pH drops to 0.3. A solution of 1.2 g of MgO (100%) in 34 g of water is added within 15 min. The pH is adjusted to 4.5 using 189 g of NaOH (25 wt. %) within 2 hours and then maintained at above 4.7 using NaOH (5 wt. %).

(40) A solution of 4 g of Al(NO.sub.3)3.9H.sub.2O (98%) in 33 g of water and a solution of 3 g of sodium perborate (97%) in 29 g of water are added within 10 min. The mixture is then heated at 90 C. for 80 min while maintaining a constant pH and then cooled to room temperature. The yellow product is filtered, washed and dried at 110 C. The filter cake is processed in two ways:

(41) A part (a) is calcined at 550 C. and then wet-milled in water to a particle size of about 0.9 m. The second part (b) is first wet-milled in water to a particle size of about 1.6 m, filtered, dried at 110 C. for 1 hour and then calcined at 550 C. followed by wet-milling in water to a final particle size of about 0.7 m.

Example 14

(42) A suspension of 1000 g of water and 302 g of an aqueous NaVO.sub.3 solution (7 wt. % of V) is stirred at 8 C. while stirring. 16 g of HNO.sub.3 (65 wt. %) and 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 5 min.

(43) 352 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) is added to the mixture within 60 min, and the pH drops to 0.4, which is adjusted to 4.5 using 150 g of Na.sub.2CO.sub.3 (15 wt. %) within 90 min. A solution of 1.5 g of Ca(OH).sub.2 (96%) in 24 g of water and a solution of 0.4 g of MgO (100%) in 34 g of water is added within 15 min giving a pH of 0.5. The pH is adjusted to 4.5 using 185 g of NaOH (25 wt. %) within 90 min and then maintained at above 4.6 using NaOH (5 wt. %).

(44) A solution of 4 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 3 g of sodium perborate (97%) in 29 g of water are added within 10 min. The mixture is then heated at 90 C. for 80 min while maintaining a constant pH and then cooled to room temperature. The yellow product is filtered, washed and dried at 110 C. The filter cake is processed in two ways:

(45) A part (a) is calcined at 500 C. and then wet-milled in water to a particle size of about 0.9 m. The second part (b) is first wet-milled in water to a particle size of about 1.2 m, filtered, dried at 110 C. for 1 hour and then calcined at 550 C. followed by wet-milling in water to a final particle size of about 0.7 m.

(46) Both pigments show a AE of 1.9 after 2374 hours of accelerated weathering.

Example 15

(47) A mixture of 1000 g of water and 296 g of an aqueous NaVO.sub.3 solution (7 wt. % of V) is cooled to 8 C. with stirring. 21 g of HNO.sub.3 (65 wt. %) and 7 g of H.sub.3PO.sub.4 (85 wt. %) are added within 10 min, wherein the pH decreased to 6.5 after about 5 min. 27 g of an aqueous solution of zirconium oxynitrate pentahydrate (27.2 wt. % of Zr) is added within 10 min while stirring leading to an orange suspension at pH 6.9. 281 g of an acidic bismuth nitrate solution (23.75 wt. % of Bi) are added within 60 min while stirring, and the pH drops to 0.4 and a yellow suspension is formed after about 30 min.

(48) A solution of 0.4 g of MgO (100%) in 34 g of water is added within 15 min, and the pH is adjusted to above 4.5 using 144 g of an aqueous NaOH (25 wt. %) within 90 min and then maintained at above 4.6 using NaOH (5 wt. %).

(49) A solution of 3.8 g of Al(NO.sub.3).sub.3.9H.sub.2O (98%) in 33 g of water and a solution of 3.2 g of sodium perborate (97%) in 29 g of water are added. The mixture is heated at 95 C. for 80 min, while maintaining a constant pH and then cooled to room temperature. The yellow product is filtered, washed and dried at 110 C. in a through air circulation for 1 hour followed by calcining at 550 C. and then wet-milling in water to a particle size of about 0.9 m.

(50) TABLE-US-00001 TABLE 1 Color Weathering Ex h C* L* strength* test 1 91.42 106.4 89.51 4-5 2 91.19 105.12 89.33 4-5 3 92.67 105.02 90.61 4-5 4 91.61 105.98 89.74 121.7 4-5 5a 92.57 105.24 87.75 4-5 5b 92.66 105.07 86.67 4-5 6 92.68 104.87 90.08 125.2 4-5 7a 88.06 102.3 83.66 3-4 7b 88.42 101.6 83.74 3-4 8a 92.18 104.2 90.03 4-5 8b 91.75 104.6 89.23 4-5 9 91.3 106.51 88.88 4-5 10 92.16 105.77 88.35 4-5 11 91.96 103.3 87.44 124.7 3-4 12 91.71 104.98 88.55 5 13a 92.74 105.04 88.17 4-5 13b 92.68 105.14 87.84 4-5 14a 92.20 105.62 88.12 5 14b 92.52 105.28 88.03 5 15 91.96 104.3 90.44 126.7 4-5 *Color strength measured related to reference Sicopal L1100 (=100)