α-alumina flakes

• US 10,457,812 B2
• Filed: 04/25/2014
• Issued: 10/29/2019
• Est. Priority Date: 04/30/2013
• Status: Active Grant

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Suzuki, Ryuta, Pfaff, Gerhard, Schoen, Sabine, Sasaki, Fumiko, Kobayashi, Satoru, Kunii, Koshiro, Takenaka, Yuji, Nitta, Katsuhisa
• Primary Examiner(s): Patel, Ronak C
• Application Number:
  US14/261,458
• Publication Number:
  US 20140322534A1
• Time in Patent Office: 2,013 Days
• Field of Search: None
• CPC Class Codes: C01F 7/02 Aluminium oxide; Aluminium hydroxide; Aluminates
• CPC Class Codes: C01F 7/34 Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
• CPC Class Codes: C01F 7/441 by calcination
• CPC Class Codes: C01P 2002/52 containing elements as dopants
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C01P 2004/20 extending in two dimensions, e.g. plate-like
• CPC Class Codes: C01P 2004/24 Nanoplates, i.e. plate-like particles with a thickness from 1-100 nanometer
• CPC Class Codes: C01P 2004/51 Particles with a specific particle size distribution
• CPC Class Codes: C01P 2004/54 Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: C09C 1/0018 uncoated and unlayered plate-like particles
• CPC Class Codes: C09C 1/0021 comprising a core coated with only one layer having a high or low refractive index
• CPC Class Codes: C09C 1/0024 comprising a stack of coating layers with alternating high and low refractive indices, wherein the first coating layer on the core surface has the high refractive index
• CPC Class Codes: C09C 1/0039 consisting of at least one coloured inorganic material
• CPC Class Codes: C09C 1/0051 comprising a stack of coating layers with alternating low and high refractive indices, wherein the first coating layer on the core surface has the low refractive index
• CPC Class Codes: C09C 1/0066 consisting of at least one coloured inorganic material
• CPC Class Codes: C09C 1/407 Aluminium oxides or hydroxides
• CPC Class Codes: C09C 2200/1004 the core comprising at least one inorganic oxide, e.g. Al2O3, TiO2 or SiO2
• CPC Class Codes: C09C 2200/301 Thickness of the core
• CPC Class Codes: C09D 7/62 : modified by treatment with other compounds
• CPC Class Codes: C09D 7/70 : characterised by shape, e.g. fibres, flakes or microspheres
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]

Abstract

Alpha-Alumina flakes having a particle thickness of 550-1000 nm, a D₅₀-value of 15-30 μm, a D₉₀-value of 30-45 μm and a D₁₀-value of ≤9.0 μm. Use of the alumina flakes in varnishes, paints, automotive coatings printing inks, masterbatches, plastics and cosmetic formulations. Also, use of the alumina flakes as a substrate for effect pigments and in organic dyes.

Claims

1. Al₂O₃ flakes having a particle thickness of 550-1000 nm, a D₅₀-value of 15-30 μ

m, a D₉₀-value of 30-45 μ

m and a D₁₀-value of ≤

9.0 μ

m and wherein the Al₂O₃ flakes are α

-alumina flakes.

2. The Al₂O₃ flakes according to claim 1, wherein the D₉₀-value is 30-40 μ

m.

3. The Al₂O₃ flakes according to claim 1, which are doped with TiO₂, ZrO₂, SiO₂, SnO₂, In₂O₃, ZnO or a combination thereof.

4. The Al₂O₃ flakes according to claim 3, wherein the amount of doping is 0.01-5% by weight based on the total weight of the Al₂O₃ flake.

5. The Al₂O₃ flakes according to claim 3, which are doped with TiO₂.

6. The Al₂O₃ flakes according to claim 1, which are coated with at least one layer of a metal oxide, a mixture of at least two metal oxides, a metal, a metal sulphide, a titanium suboxide, titanium oxynitride, FeO(OH), a metal alloy or a rare earth compound.

7. The Al₂O₃ flakes according to claim 6, which consist of 40-90 wt. % of Al₂O₃ flakes and 10-60 wt. % of the coating based on the weight of the coated Al₂O₃ flakes.

8. The Al₂O₃ flakes according to claim 1, which are coated with at least one layer of a metal oxide or a mixture of at least two metal oxides.

9. The Al₂O₃ flakes according to claim 1, which are coated with the following layer sequence:

Al₂O₃ flake+TiO₂

Al₂O₃ flake+TiO₂/Fe₂O₃

Al₂O₃ flake+Fe₂O₃

Al₂O₃ flake+TiO₂+Fe₂O₃

Al₂O₃ flake+TiO₂+Fe₃O₄

Al₂O₃ flake+TiO₂+SiO₂+TiO₂

Al₂O₃ flake+Fe₂O₃+SiO₂+TiO₂

Al₂O₃ flake+TiO₂/Fe₂O₃+SiO₂+TiO₂

Al₂O₃ flake+TiO₂+SiO₂+TiO₂/Fe₂O₃

Al₂O₃ flake+TiO₂+SiO₂

Al₂O₃ flake+TiO₂+SiO₂/Al₂O₃

Al₂O₃ flake+TiO₂+Al₂O₃

Al₂O₃ flake+SnO₂

Al₂O₃ flake+SnO₂+TiO₂

Al₂O₃ flake+SnO₂+Fe₂O₃

Al₂O₃ flake+SiO₂

Al₂O₃ flake+SiO₂+TiO₂

Al₂O₃ flake+SiO₂+TiO₂/Fe₂O₃

Al₂O₃ flake+SiO₂+Fe₂O₃

Al₂O₃ flake+SiO₂+TiO₂+Fe₂O₃

Al₂O₃ flake+SiO₂+TiO₂+Fe₃O₄

Al₂O₃ flake+SiO₂+TiO₂+SiO₂+TiO₂

Al₂O₃ flake+SiO₂+Fe₂O₃+SiO₂+TiO₂

Al₂O₃ flake+SiO₂+TiO₂/Fe₂O₃+SiO₂+TiO₂

Al₂O₃ flake+SiO₂+TiO₂+SiO₂+TiO₂/Fe₂O₃

Al₂O₃ flake+SiO₂+TiO₂+SiO₂

Al₂O₃ flake+SiO₂+TiO₂+SiO₂/Al₂O₃

Al₂O₃ flake+SiO₂+TiO₂+Al₂O₃

Al₂O₃ flake+TiO₂+Prussian Blue or

Al₂O₃ flake+TiO₂+Carmine Red.

10. The Al₂O₃ flakes according to claim 1, which are coated with TiO₂ in the anatase modification.

11. The Al₂O₃ flakes according to claim 1, which are coated with TiO₂ in the rutile modification.

12. The Al₂O₃ flakes according to claim 1, which do not contain zinc.

13. The Al₂O₃ flakes according to claim 1, which have a D₅₀-value of 15-25 μ

m, and a D₉₀-value of 30-40 μ

m.

14. The Al₂O₃ flakes according to claim 1, which have a D₁₀-value of <

9.0 μ

m.

15. The Al₂O₃ flakes according to claim 1, which have a D₁₀-value of 9.0 μ

m.

16. The Al₂O₃ flakes according to claim 1, having a particle thickness of 700 nm.

17. The Al₂O₃ flakes according to claim 1, having a particle thickness of 600-900 nm.

20. A composition comprising the Al₂O₃ flakes according to claim 1, in formulations selected from the areas of effect pigments, 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, flexible sheets for the insulation of machines or devices, absorber in the laser marking of paper or plastics, absorber in the laser welding of plastics, pigment pastes with water, organic and/or aqueous solvents or pigment preparations.

21. A formulation containing the Al₂O₃ flakes according to claim 1 in an amount of 0.01-95% by weight, based on the total weight of the formulation.

22. A formulation containing the Al₂O₃ flakes according to claim 1, and at least one component selected from the group consisting of water, polyols, polar oils, 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, effect pigments, UV absorbers, surface-active assistants, cosmetic active compounds, fillers, binders, pearlescent pigments, color pigments and organic dyes.

23. A process for preparing the Al₂O₃ flakes according to claim 1, comprising

(1) preparing an aqueous solution or a slurry of at least one water-soluble and/or insoluble aluminum salt,

(2) adding an alkali solution to the aluminum salt solution to precipitate aluminum hydroxide particles, and adding a phosphorous compound and optionally at least one dopant to the aqueous solution before, during or after the precipitation,

(3) evaporating the water, followed by drying of the precipitated product of step (2) to form the dried form of alumina containing particle and alkali salt,

(4) calcining the dried form obtained in step (3) to obtain Al₂O₃ flakes in a molten salt,

(5) removing the water soluble part of the calcined material obtained in step (4), and

(6) adjusting the particle size and thickness.

18. An assortment of Al₂O₃ flakes having a particle thickness of 550-1000 nm, a D₅₀-value of 15-30 μ

m, a D₉₀-value of 30-45 μ

m and a D₁₀-value of 9.0 μ

m and wherein the Al₂O₃ flakes are α

-alumina flakes.

19. The Al₂O₃ flakes according to claim 18, having a particle thickness of 600-900 nm.