Effect pigments

Abstract

Effect pigments based on Al.sub.2O.sub.3 flakes with high weather resistance and less photoactivity and to their use thereof in paints, industrial coatings, automotive coatings, printing inks, cosmetic formulations. The effect pigments have a ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flake and the amount by weight of the metal oxide(s) of the coating layer(s) in the range of from 27:73 to 83:17 based on the total weight of the effect pigment.

Claims

1. An effect pigment based on an Al.sub.2O.sub.3 flake which comprises an Al.sub.2O.sub.3 flake coated with one or more layers of a metal oxide and/or a metal oxide mixture: wherein the ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flake to the amount by weight of the metal oxide(s) of the coating layer(s) is in the range of from 27:73 to 83:17 based on the total weight of the effect pigment; wherein one or more layers of a metal oxide and/or a metal oxide mixture comprise one or more layers of metal oxides selected of TiO.sub.2, Fe.sub.2O.sub.3, Fe.sub.3O.sub.4, SnO.sub.2, ZrO.sub.2 or Cr.sub.2O.sub.3; wherein the thickness of each metal oxide and/or a metal oxide mixture layer on the Al.sub.2O.sub.3 flakes is 20-400 nm with the exception of any SnO.sub.2 layer, which has a layer thickness of 1-400 nm; wherein the effect pigment contains on the surface a protective layer containing at least one rare earth metal oxide, at least one metal oxide that is silicon, aluminum or zirconium or mixtures thereof, and an organic compound, and wherein the protective layer contains 0.2-2 wt. % of the at least one rare earth metal oxide, 0.2-2 wt. % of SiO2, 0.2-4 wt. % of Al2O3 and/or ZrO2 and 1-10 wt. % of the organic compound.

2. The effect pigment according to claim 1 wherein the Al.sub.2O.sub.3 flake is coated on the surface with one or two metal oxide layers.

3. The effect pigment according to claim 1, wherein the Al.sub.2O.sub.3 flake is doped with TiO.sub.2, ZrO.sub.2, SiO.sub.2, SnO.sub.2, In.sub.2O.sub.3 or ZnO or a combination thereof.

4. The effect pigment according to claim 3, wherein the amount of doping is 0.01-5% by weight based on the Al.sub.2O.sub.3 flake.

5. The effect pigment according to claim 1, wherein the Al.sub.2O.sub.3 flake is doped with TiO.sub.2 or ZnO.

6. The effect pigment according to claim 1, wherein the particle thickness of the Al.sub.2O.sub.3 flake is in the range of 130-500 nm.

7. The effect pigment according to claim 1, wherein the Al.sub.2O.sub.3 flake has a standard deviation of thickness distribution of less than 80.

8. The effect pigment according to claim 1, wherein the Al.sub.2O.sub.3 flake is coated to provide the following layer sequence: Al.sub.2O.sub.3 flake+TiO.sub.2 Al.sub.2O.sub.3 flake+TiO.sub.2/Fe.sub.2O.sub.3 Al.sub.2O.sub.3 flake+Fe.sub.2O.sub.3 Al.sub.2O.sub.3 flake+Fe.sub.3O.sub.4 Al.sub.2O.sub.3 flake+TiO.sub.2+Fe.sub.2O.sub.3 Al.sub.2O.sub.3 flake+TiO.sub.2+Fe.sub.3O.sub.4 Al.sub.2O.sub.3 flake+TiO.sub.2+SiO.sub.2+TiO.sub.2 Al.sub.2O.sub.3 flake+TiO.sub.2+MgO/SiO.sub.2+TiO.sub.2 Al.sub.2O.sub.3 flake+Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2 Al.sub.2O.sub.3 flake+TiO.sub.2/Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2 Al.sub.2O.sub.3 flake+TiO.sub.2+SiO.sub.2+TiO.sub.2/Fe.sub.2O.sub.3 Al.sub.2O.sub.3 flake+TiO.sub.2/Fe.sub.2O.sub.3+SiO.sub.2+TiO.sub.2/Fe.sub.2O.sub.3 Al.sub.2O.sub.3 flake+TiO.sub.2+SiO.sub.2 Al.sub.2O.sub.3 flake+TiO.sub.2+SiO.sub.2/Al.sub.2O.sub.3 Al.sub.2O.sub.3 flake+TiO.sub.2+Al.sub.2O.sub.3 Al.sub.2O.sub.3 flake+SnO.sub.2 Al.sub.2O.sub.3 flake+SnO.sub.2+Fe.sub.2O.sub.3 Al.sub.2O.sub.3 flake+SnO.sub.2+TiO.sub.2 Al.sub.2O.sub.3 flake+ZrO.sub.2 Al.sub.2O.sub.3 flake+TiO.sub.2+Prussian Blue Al.sub.2O.sub.3 flake+TiO.sub.2+Carmine Red, wherein a / mark indicates a mixed oxide.

9. The effect pigment according to claim 1, wherein the Al.sub.2O.sub.3 flake is coated with TiO.sub.2 in the rutile or anatase modification.

10. The effect pigment according to claim 1, wherein the Al.sub.2O.sub.3 flake is coated with TiO.sub.2 in the rutile modification.

11. The effect pigment according to claim 1, wherein the organic compound is organic coupling agents, organofunctional silanes, amino compounds or organic phosphorus compounds.

12. The effect pigment according to claim 1, wherein the rare earth metal oxide in the protective layer is cerium oxide.

13. The effect pigment according to claim 1, wherein the amount of the rare earth metal oxide in the effect pigment is ≤1 wt. %.

14. The effect pigment according to claim 1, wherein the protective layer has a thickness of 0.5-10 nm.

15. A formulation which comprises an effect pigment according to claim 1 which formulation is a formulation for: paints; coatings; automobile coatings; automotive finishing; industrial coatings; powder coatings; printing inks; security printing inks; plastics; ceramic materials; cosmetics; glasses; paper; paper coating; toners for electrophotographic printing processes; seeds; greenhouse sheeting or tarpaulins; thermally conductive, self-supporting, electrically insulating, flexible sheets for the insulation of machines or devices; an absorber in the laser marking of paper and plastics; an absorber in the laser welding of plastics; pigment pastes with water; organic and/or aqueous solvents; a pigment preparation; or a dry pigment preparation.

16. A formulation containing one or more effect pigments according to claim 1 in an amount of 0.01-95% by weight, based on the formulation as a whole.

17. A formulation containing one or more effect pigments according to claim 1, which further comprises at least one component selected from the group consisting of: water, polyols, polar and nonpolar oils, fats, waxes, film formers, polymers, copolymers, surfactants, free-radical scavengers, antioxidants, stabilisers, odour enhancers, silicone oils, emulsifiers, solvents, preservatives, thickeners, rheological additives, fragrances, colorants, other effect pigments, UV absorbers, surface-active assistants, cosmetic active compounds, fillers, binders, pearlescent pigments, color pigments and organic dyes.

18. The effect pigment according to claim 1, wherein the interference and/or masstone color of the effect pigment is silver, and the ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flakes to the amount by weight of the metal oxide(s) of the coating layer(s) is in the range of from 60:40 to 80:20 based on the total weight of the effect pigment.

19. The effect pigment according to claim 1, wherein the interference and/or masstone color of the effect pigment is blue, to the ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flakes and the amount by weight of the metal oxide(s) of the coating layer(s) is in the range of from 35:65 to 60:40 based on the total weight of the effect pigment.

20. The effect pigment according to claim 1, wherein the interference and/or masstone color of the effect pigment is red, to the ratio of the amount by weight of Al.sub.2O.sub.3 of the Al.sub.2O.sub.3 flakes and the amount by weight of the metal oxide(s) of the coating layer(s) is in the range of from 35:65 to 65:35 based on the total weight of the effect pigment.

Description

EXAMPLES

Example 1

Production of Al.SUB.2.O.SUB.3 .Flakes

(1) 74.6 g of aluminum sulfate 18-hydrate, 57.1 g of poly aluminum chloride (PAC: Central Glass Co., LTD, 10% solution as Al.sub.2O.sub.3), 57.3 g of anhydrous sodium sulfate, and 46.9 g of potassium sulfate are dissolved in 300 ml of deionized water by heating above 60° C. 3.0 g of 34.4% of a titanyl sulfate solution are added to the solution. The resulting solution is designated as the aqueous solution (a).

(2) 0.45 g of sodium tertiary phosphate 12-hydrate and 55.0 g of sodium carbonate are added to 300 ml of deionized water. The resulting solution is designated as the aqueous solution (b).

(3) The aqueous solution (b) is added with stirring to the aqueous solution (a) and kept at about 60° C. Stirring is continued for 1 h. The obtained mixture of solution (a) and solution (b) is a slurry. This slurry is evaporated to dryness and the dried product is heated at 1150° C. for 6 h. Water is added to the heated product to dissolve free sulfate. Insoluble solids are filtered off and washed with water. Finally, the product is dried.

(4) The obtained alumina flake is examined by X-ray diffractometry. The diffraction pattern have only peaks attributed to corundum structure (α-alumina structure).

(5) The obtained Al.sub.2O.sub.3 flakes have a D.sub.50 value of 16.0 μm and D.sub.90 value of 30.8 μm and a thickness of 200 nm.

(6) The thickness distribution of the α-Al.sub.2O.sub.3 flake is 28.

Example 2

Production of Al.SUB.2.O.SUB.3 .Flakes

(7) 74.6 g of aluminum sulfate 18-hydrate, 57.1 g of poly aluminum chloride (PAC: Central Glass Co., LTD, 10% solution as Al.sub.2O.sub.3), 57.3 g of anhydrous sodium sulfate, and 46.9 g of potassium sulfate are dissolved in 300 ml of deionized water by heating above 60° C. 3.0 g of 34.4% of a titanyl sulfate solution and 5.5 g of 5.0% indium chloride(III) solution are added to the solution. The resulting solution is designated as the aqueous solution (a).

(8) 0.45 g of sodium tertiary phosphate 12-hydrate and 55.0 g of sodium carbonate are added to 300 ml of deionized water. The resulting solution is designated as the aqueous solution (b).

(9) The aqueous solution (b) is added with stirring to the aqueous solution (a) and kept at about 60° C. Stirring is continued for 1 h. The obtained mixture of solution (a) and solution (b) is a slurry. This slurry is evaporated to dryness and the dried product is heated at 1200° C. for 4 h. Water is added to the heated product to dissolve free sulfate. Insoluble solids are filtered off and washed with water. Finally, the product is dried.

(10) The obtained alumina flake is examined by X-ray diffractometry. The diffraction pattern have only peaks attributed to corundum structure (α-alumina structure).

(11) The obtained Al.sub.2O.sub.3 flakes have a D.sub.50 value of 19.0 μm and D.sub.90 value of 35.6 μm and a thickness of 250 nm.

(12) The thickness distribution of the α-Al.sub.2O.sub.3 flake is 32.

Example 3

Production of Al.SUB.2.O.SUB.3 .Flakes

(13) 1.3 g of 27% Al.sub.2(SO.sub.4).sub.3 solution, 345 g of Na.sub.2SO.sub.4, 280 g of K.sub.2SO.sub.4 and 6 g of ZnSO.sub.4*7H.sub.2O solution are added to 1,205 ml water and heated at 70° C. An alkali solution is added consisting of 320 g of Na.sub.2CO.sub.3 and 2.7 g of (NaPO.sub.3).sub.6 in 900 ml water at 70° C. The aluminium sulfate mixture solution is titrated with the alkali solution while stirring to pH 6.8. A gel mixture of pseudo-boehmite and flux is obtained. The gel mixture is aged at 90° C. for 20 hours, distilled under vacuum at 60° C. and dried at 110° C. for 20 h. The dried gel mixture is ground to a size less than 5 mm and calcined in a 2 I alumina crucible at 500° C. for 1 h to remove the moisture. The temperature is elevated to 930° C. and maintained for 0.5 h, so that a homogeneous molten salt is formed and flaky crystals are formed by the coagulation of aciculary-alumina particles. Crystallization is performed at 1,150° C. for 5.5 h to obtain a flaky α-alumina crystal by filtering. The flaky α-alumina crystal is suspended in 3,000 I of a 0.5% sulfuric acid solution. The particles are stirred at 60° C. for 48 h for complete dispersion. The mixture is filtered again, washed with water and dried at 100° C. A transparent flaky α-alumina having a thickness of 255 nm and an average particle size of 15.6 μm is obtained.

Example 4

Coating of Al.SUB.2.O.SUB.3 .Flakes

(14) 20 g alumina flakes of Example 1 are suspended in 250 ml of deionized water. The resulting suspension is adjusted to pH 1.8-1.9 by addition of 10% HCl and is kept throughout the entire procedure at about 75° C. After stirring for 10 min, simultaneously a solution of 0.8 g of SnCl.sub.4 in 15 ml of deionized water and a 32% solution of NaOH are added dropwise while maintaining the pH at 1.8-1.9. After stirring for 30 min, a solution containing 29 g of TiCl.sub.4 in 50 ml of deionized water is added simultaneously with a 10% solution of NaOH while keeping the pH at 1.8-1.9. After stirring for 15 min the pH is adjusted to pH 7.5 by adding 32% sodium hydroxide solution.

(15) After 10 min of stirring, a solution containing 4.8 g of Na.sub.2SiO.sub.3 in 25 ml of deionized water is added to the suspension. Simultaneously a 10% solution of HCl is added to keep the pH at 7.5. After 10 min stirring the pH is adjusted to 1.8 by adding a 10% solution of HCl. The suspension is allowed to settle and the volume is adjusted to ca. 280 ml by partly removing the clear solution on top of the settled particles.

(16) While stirring, an additional layer of SnO.sub.2 is deposited by simultaneous dropwise adding of a solution of 0.8 g of Snack in 15 ml of deionized water and 32% solution of sodium hydroxide while maintaining the pH at 1.8-1.9. After stirring for 30 min, a solution containing 21.9 g of TiCl.sub.4 in 50 ml of deionized water is added simultaneously with a 10% solution of NaOH while maintaining the pH at 1.8-1.9. After 30 min stirring, the pH is adjusted to 5.0-5.3 and filtered. The filter cake is washed with water and dried. Finally, the dried solids are calcined at 850° C. for 30 minutes to give a highly bluish and glossy pearlescent pigment. At the luster angle, a strong bluish color and very high glossy appearance can be seen at a more wider angle.

Example 5

Coating of Al.SUB.2.O.SUB.3 .Flakes

(17) 20 g alumina flakes of Example 2 are suspended in 400 ml of deionized water. To the resulting suspension (kept at about 65° C.) is added a solution containing 125 g of TiCl.sub.4 per liter. Simultaneously a 10% solution of NaOH is added to keep the pH at 2.1. The addition of the TiCl.sub.4 solution is stopped when the resulting product takes on a yellowish color. Then a solution containing 50 g of Na.sub.2SiO.sub.3 per liter is added to the resulted suspension. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Next a solution containing 125 g of TiCl.sub.4 per liter is added to the resulted suspension. Simultaneously a 10% solution of NaOH is added to keep the pH at 2.1. The addition of the TiCl.sub.4 solution is stopped when the resulting product takes on a bluish color. The suspending solids are filtered off, washed with water, and dried. Finally, the dried solids are calcined at 850° C. for 30 minutes to give a highly bluish and glossy pearlescent pigment. At the luster angle, a strong bluish color and very high glossy appearance can be seen at a more wider angle.

Example 6

Coating of Al.SUB.2.O.SUB.3 .Flakes

(18) 20 g alumina flakes of Example 2 are suspended in 250 ml of deionized water. The resulting suspension is adjusted to pH 1.8-1.9 by addition of 10% HCl and is kept throughout the entire procedure at about 75° C. After stirring for 10 min, simultaneously a solution of 0.8 g of SnCl.sub.4 in 15 ml of deionized water and a 32% solution of NaOH are added dropwise while maintaining the pH at 1.8-1.9. After stirring for 30 min, a solution containing 29 g of TiCl.sub.4 in 50 ml of deionized water is added simultaneously with a 10% solution of NaOH while keeping the pH at 1.8-1.9. After stirring for 15 min the pH is adjusted to pH 7.5 by adding 32% sodium hydroxide solution. After 10 min of stirring, a solution containing 4.8 g of Na.sub.2SiO.sub.3 in 25 ml of deionized water is added to the suspension. Simultaneously a 10% solution of HCl is added to keep the pH at 7.5. After 10 min stirring the pH is adjusted to 1.8 by adding a 10% solution of HCl. The suspension is allowed to settle and the volume is adjusted to ca. 280 ml by partly removing the clear solution on top of the settled particles.

(19) While stirring, an additional layer of SnO.sub.2 deposited by simultaneous dropwise adding of a solution of 0.8 g of SnCl in 15 ml of deionized water and 32% solution of sodium hydroxide while maintaining the pH at 1.8-1.9. After stirring for 30 min, a solution containing 21.9 g of TiCl.sub.4 in 50 ml of deionized water is added simultaneously with a 10% solution of NaOH while maintaining the pH at 1.8-1.9. After 30 min stirring, the pH is adjusted to 5.0-5.3 and filtered. The filter cake is washed with water and dried. Finally, the dried solids are calcined at 850° C. for 30 minutes to give a highly bluish and glossy pearlescent pigment. At the luster angle, a strong bluish color and very high glossy appearance can be seen at a more wider angle.

Example 7

Coating of Al.SUB.2.O.SUB.3 .Flakes

(20) 20 g alumina flakes of Example 3 are suspended in 400 ml of deionized water. To the resulting suspension (kept at about 65° C.) is added a solution containing 125 g of TiCl.sub.4 per liter. Simultaneously a 10% solution of NaOH is added to keep the pH at 2.1. The addition of the TiCl.sub.4 solution is stopped when the resulting product takes on a yellowish color. Then a solution containing 50 g of Na.sub.2SiO.sub.3 per liter is added to the resulting suspension. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Next a solution containing 125 g of TiCl.sub.4 per liter is added to the resulted suspension. Simultaneously a 10% solution of NaOH is added to keep the pH at 2.1. The addition of the TiCl.sub.4 solution is stopped when the resulting product takes on a bluish color. The suspending solids are filtered off, washed with water, and dried. Finally, the dried solids are calcined at 850° C. for 30 minutes to give a highly bluish and glossy pearlescent pigment. At the luster angle, a strong bluish color and very high glossy appearance can be seen at a more wider angle.

Example 8

Coating of Al.SUB.2.O.SUB.3 .Flakes

(21) 20 g alumina flakes of Example 3 are suspended in 250 ml of deionized water. The resulting suspension is adjusted to pH 1.8-1.9 by addition of 10% HCl and is kept throughout the entire procedure at about 75° C. After stirring for 10 min, simultaneously a solution of 0.8 g of SnCl.sub.4 in 15 ml of deionized water and a 32% solution of NaOH are added dropwise while maintaining the pH at 1.8-1.9. After stirring for 30 min, a solution containing 29 g of TiCl.sub.4 in 50 ml of deionized water is added simultaneously with a 10% solution of NaOH while keeping the pH at 1.8-1.9. After stirring for 15 min the pH is adjusted to pH 7.5 by adding 32% sodium hydroxide solution. After 10 min of stirring, a solution containing 4.8 g of Na.sub.2SiO.sub.3 in 25 ml of deionized water is added to the suspension. Simultaneously a 10% solution of HCl is added to keep the pH at 7.5. After 10 min stirring the pH is adjusted to 1.8 by adding a 10% solution of HCl. The suspension is allowed to settle and the volume is adjusted to ca. 280 ml by partly removing the clear solution on top of the settled particles.

(22) While stirring, an additional layer of SnO.sub.2 deposited by simultaneous dropwise adding of a solution of 0.8 g of SnCl in 15 ml of deionized water and 32% solution of sodium hydroxide while maintaining the pH at 1.8-1.9. After stirring for 30 min, a solution containing 21.9 g of TiCl.sub.4 in 50 ml of deionized water is added simultaneously with a 10% solution of NaOH while maintaining the pH at 1.8-1.9. After 30 min stirring, the pH is adjusted to 5.0-5.3 and filtered. The filter cake is washed with water and dried. Finally, the dried solids are calcined at 850° C. for 30 minutes to give a highly bluish and glossy pearlescent pigment. At the luster angle, a strong bluish color and very high glossy appearance can be seen at a more wider angle.

Example 9

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(23) 100 g of alumina flakes coated according to Example 4 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 7 with 10% HCl, is added 100 ml of a water glass solution containing 3.05 g Na.sub.2SiO.sub.3 during 90 min. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Subsequently 100 ml of a solution containing 6.5 g aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O) is added during 90 min to the suspension while keeping the pH to 7 with 10% NaOH. After raising the pH to 7.5 with 10% NaOH 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(24) The surface-treated effect pigments show a good humidity resistance (humidity cabinet test), moderate weathering resistance due to remaining photoactivity.

Example 10

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(25) A 2 wt. % aqueous solution containing 2.55 g sodium hypophosphite (NaH.sub.2PO.sub.2*H.sub.2O) was added at room temperature with stirring to a 5 wt-% aqueous solution containing 3.90 g zirconium oxychloride (ZrOCl.sub.2*8H.sub.2O) so slowly as not to form any white precipitate. To the clear solution thus obtained was added 4.1 g of a 35 wt. % hydrochloride acid, yielding a mixing solution of zirconium oxychloride and sodium hypophosphite.

(26) 100 g of alumina flakes coated according to Example 4 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 2.5 with 10% HCl, is added 2.95 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O). The solution of zirconium oxychloride and sodium hypophosphite is added during 60 min while keeping the pH at 2.5 with 10% NaOH. Then the pH is raised to 7.0 during 60 min by addition of 10% NaOH. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5), 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8), and 0.5 g n-hexyltrimethoxysilane (CAS No. 3069-19-0) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(27) The surface-treated effect pigments show a good humidity and weathering resistance.

Example 11

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(28) 100 g of alumina flakes coated according to Example 4 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 3.0 with 10% HCl, is added 1.70 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O) and 3.27 g of aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O. The pH is raised to 7.5 during 90 min with 10% NaOH. Then 50 ml of a water glass solution containing 3.03 g Na.sub.2SiO.sub.3 is added during 90 min while keeping the pH to 7.5 with 10% HCl. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.5 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(29) The surface-treated effect pigments according to Example 11 with reduced cerium content show, compared to the Examples 9 and 10, superior humidity properties (very good humidity) and weathering resistance.

Example 12

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(30) 100 g of alumina flakes coated according to Example 5 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 7 with 10% HCl, is added 100 ml of a water glass solution containing 3.05 g Na.sub.2SiO.sub.3 during 90 min. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Subsequently 100 ml of a solution containing 6.5 g aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O) is added during 90 min to the suspension while keeping the pH to 7 with 10% NaOH. After raising the pH to 7.5 with 10% NaOH 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(31) The surface-treated effect pigments show a good humidity resistance (humidity cabinet test), moderate weathering resistance due to remaining photoactivity.

Example 13

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(32) A 2 wt. % aqueous solution containing 2.55 g sodium hypophosphite (NaH.sub.2PO.sub.2*H.sub.2O) was added at room temperature with stirring to a 5 wt-% aqueous solution containing 3.90 g zirconium oxychloride (ZrOCl.sub.2*8H.sub.2O) so slowly as not to form any white precipitate. To the clear solution thus obtained was added 4.1 g of a 35 wt. % hydrochloride acid, yielding a mixing solution of zirconium oxychloride and sodium hypophosphite.

(33) 100 g of alumina flakes coated according to Example 5 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 2.5 with 10% HCl, is added 2.95 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O). The solution of zirconium oxychloride and sodium hypophosphite is added during 60 min while keeping the pH at 2.5 with 10% NaOH. Then the pH is raised to 7.0 during 60 min by addition of 10% NaOH. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5), 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8), and 0.5 g n-hexyltrimethoxysilane (CAS No. 3069-19-0) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(34) The surface-treated effect pigments show a good humidity and weathering resistance.

Example 14

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(35) 100 g of alumina flakes coated according to Example 5 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 3.0 with 10% HCl, is added 1.70 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O) and 3.27 g of aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O. The pH is raised to 7.5 during 90 min with 10% NaOH. Then 50 ml of a water glass solution containing 3.03 g Na.sub.2SiO.sub.3 is added during 90 min while keeping the pH to 7.5 with 10% HCl. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.5 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(36) The surface-treated effect pigments according to Example 14 with reduced cerium content show, compared to the Examples 12 and 13, superior humidity properties (very good humidity) and weathering resistance.

Example 15

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(37) 100 g of alumina flakes coated according to Example 6 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 7 with 10% HCl, is added 100 ml of a water glass solution containing 3.05 g Na.sub.2SiO.sub.3 during 90 min. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Subsequently 100 ml of a solution containing 6.5 g aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O) is added during 90 min to the suspension while keeping the pH to 7 with 10% NaOH. After raising the pH to 7.5 with 10% NaOH 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(38) The surface-treated effect pigments show a good humidity resistance (humidity cabinet test), moderate weathering resistance due to remaining photoactivity.

Example 16

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(39) A 2 wt. % aqueous solution containing 2.55 g sodium hypophosphite (NaH.sub.2PO.sub.2*H.sub.2O) was added at room temperature with stirring to a 5 wt-% aqueous solution containing 3.90 g zirconium oxychloride (ZrOCl.sub.2*8H.sub.2O) so slowly as not to form any white precipitate. To the clear solution thus obtained was added 4.1 g of a 35 wt. % hydrochloride acid, yielding a mixing solution of zirconium oxychloride and sodium hypophosphite. 100 g of alumina flakes coated according to Example 6 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 2.5 with 10% HCl, is added 2.95 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O). The solution of zirconium oxychloride and sodium hypophosphite is added during 60 min while keeping the pH at 2.5 with 10% NaOH. Then the pH is raised to 7.0 during 60 min by addition of 10% NaOH. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5), 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8), and 0.5 g n-hexyltrimethoxysilane (CAS No. 3069-19-0) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(40) The surface-treated effect pigments show a good humidity and weathering resistance.

Example 17

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(41) 100 g of alumina flakes coated according to Example 6 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 3.0 with 10% HCl, is added 1.70 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O) and 3.27 g of aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O. The pH is raised to 7.5 during 90 min with 10% NaOH. Then 50 ml of a water glass solution containing 3.03 g Na.sub.2SiO.sub.3 is added during 90 min while keeping the pH to 7.5 with 10% HCl. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.5 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(42) The surface-treated effect pigments according to Example 17 with reduced cerium content show, compared to the Examples 15 and 16, superior humidity properties (very good humidity) and weathering resistance.

Example 18

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(43) 100 g of alumina flakes coated according to Example 7 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 7 with 10% HCl, is added 100 ml of a water glass solution containing 3.05 g Na.sub.2SiO.sub.3 during 90 min. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Subsequently 100 ml of a solution containing 6.5 g aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O) is added during 90 min to the suspension while keeping the pH to 7 with 10% NaOH. After raising the pH to 7.5 with 10% NaOH 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(44) The surface-treated effect pigments show a good humidity resistance (humidity cabinet test), moderate weathering resistance due to remaining photoactivity.

Example 19

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(45) A 2 wt. % aqueous solution containing 2.55 g sodium hypophosphite (NaH.sub.2PO.sub.2*H.sub.2O) was added at room temperature with stirring to a 5 wt-% aqueous solution containing 3.90 g zirconium oxychloride (ZrOCl.sub.2*8H.sub.2O) so slowly as not to form any white precipitate. To the clear solution thus obtained was added 4.1 g of a 35 wt. % hydrochloride acid, yielding a mixing solution of zirconium oxychloride and sodium hypophosphite.

(46) 100 g of alumina flakes coated according to Example 7 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 2.5 with 10% HCl, is added 2.95 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O). The solution of zirconium oxychloride and sodium hypophosphite is added during 60 min while keeping the pH at 2.5 with 10% NaOH. Then the pH is raised to 7.0 during 60 min by addition of 10% NaOH. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5), 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8), and 0.5 g n-hexyltrimethoxysilane (CAS No. 3069-19-0) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(47) The surface-treated effect pigments show a good humidity and weathering resistance.

Example 20

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(48) 100 g of alumina flakes coated according to Example 7 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 3.0 with 10% HCl, is added 1.70 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O) and 3.27 g of aluminium sulfate (Al.sub.2(SO.sub.4).sub.318H.sub.2O. The pH is raised to 7.5 during 90 min with 10% NaOH. Then 50 ml of a water glass solution containing 3.03 g Na.sub.2SiO.sub.3 is added during 90 min while keeping the pH to 7.5 with 10% HCl. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.5 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(49) The surface-treated effect pigments according to Example 20 with reduced cerium content show, compared to the Examples 18 and 19, superior humidity properties (very good humidity) and weathering resistance.

Example 21

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(50) 100 g of alumina flakes coated according to Example 8 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 7 with 10% HCl, is added 100 ml of a water glass solution containing 3.05 g Na.sub.2SiO.sub.3 during 90 min. Simultaneously a 10% solution of HCl is added to keep the pH at 7. Subsequently 100 ml of a solution containing 6.5 g aluminium sulfate (Al.sub.2(SO.sub.4).sub.3*18H.sub.2O) is added during 90 min to the suspension while keeping the pH to 7 with 10% NaOH. After raising the pH to 7.5 with 10% NaOH 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(51) The surface-treated effect pigments show a good humidity resistance (humidity cabinet test), moderate weathering resistance due to remaining photoactivity.

Example 22

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(52) A 2 wt. % aqueous solution containing 2.55 g sodium hypophosphite (NaH.sub.2PO.sub.2*H.sub.2O) was added at room temperature with stirring to a 5 wt-% aqueous solution containing 3.90 g zirconium oxychloride (ZrOCl.sub.2*8H.sub.2O) so slowly as not to form any white precipitate. To the clear solution thus obtained was added 4.1 g of a 35 wt. % hydrochloride acid, yielding a mixing solution of zirconium oxychloride and sodium hypophosphite.

(53) 100 g of alumina flakes coated according to Example 8 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 2.5 with 10% HCl, is added 2.95 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O). The solution of zirconium oxychloride and sodium hypophosphite is added during 60 min while keeping the pH at 2.5 with 10% NaOH. Then the pH is raised to 7.0 during 60 min by addition of 10% NaOH. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5), 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8), and 0.5 g n-hexyltrimethoxysilane (CAS No. 3069-19-0) were added subsequently during 15 min each to the suspension while keeping the pH at 7.0 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(54) The surface-treated effect pigments show a good humidity and weathering resistance.

Example 23

Surface Treatment of Coated Al.SUB.2.O.SUB.3 .Flakes

(55) 100 g of alumina flakes coated according to Example 8 are suspended in 1000 ml of deionized water. To the resulting suspension, kept at about 70° C. and adjusted to pH 3.0 with 10% HCl, is added 1.70 g of cerium(III) chloride (CeCl.sub.3*7H.sub.2O) and 3.27 g of aluminium sulfate (Al.sub.2(SO.sub.4).sub.318H.sub.2O. The pH is raised to 7.5 during 90 min with 10% NaOH. Then 50 ml of a water glass solution containing 3.03 g Na.sub.2SiO.sub.3 is added during 90 min while keeping the pH to 7.5 with 10% HCl. 1.5 g of 3-aminopropyl-trimethoxysilane (CAS No. 13822-56-5) and 1.5 g 3-glycidyloxypropyl-trimethoxysilane (CAS No. 2530-83-8) were added subsequently during 15 min each to the suspension while keeping the pH at 7.5 with 10% HCl or 10% NaOH. The suspending solids are filtered off, washed with water, dried at 140° C. and sieved (325 mesh).

(56) The surface-treated effect pigments according to example 23 with reduced cerium content show, compared to the Examples 21 and 22, superior humidity properties (very good humidity) and weathering resistance.

(57) Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

(58) In the foregoing and in the examples, all temperatures are set forth uncorrected in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

(59) The entire disclosure[s] of all applications, patents and publications, cited herein and of corresponding EP application No. 16156942.1, filed Feb. 23, 2016, is [are] incorporated by reference herein.

(60) The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

(61) From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.