Dielectric coatings and articles

• US 10,640,658 B2
• Filed: 11/02/2011
• Issued: 05/05/2020
• Est. Priority Date: 12/01/2010
• Status: Active Grant

• Current Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Rueger, Reinhold, Kuntz, Matthias
• Primary Examiner(s): Shah, Samir
• Application Number:
  US13/990,545
• Publication Number:
  US 20130244022A1
• Time in Patent Office: 3,107 Days
• CPC Class Codes: C08K 3/013 Fillers, pigments or reinforcing additives
• CPC Class Codes: C09D 101/18 Cellulose nitrate
• CPC Class Codes: C09D 5/24 Electrically-conducting paints conductive materials H01B1/00
• CPC Class Codes: C09D 7/41 Organic pigments; Organic dyes
• CPC Class Codes: C09D 7/61 inorganic
• CPC Class Codes: H01B 3/004 with conductive additives or conductive layers
• CPC Class Codes: H01B 3/185 Substances or derivates of cellulose
• CPC Class Codes: Y10T 428/251 Mica
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide

Abstract

The present invention relates to dielectric coatings and articles having high, but precisely defined specific surface resistances.

Claims

1. A dielectric coating or dielectric article comprising:

one or more semiconducting pigments, a dielectric binder and optionally further dielectric additives,

wherein said dielectric coating or dielectric article has a pale color,

wherein said one or more semiconducting pigments are particles containing a substrate, a semiconducting layer and optionally a further layer of TiO₂, SiO₂, ZnO, Cr₂O₃, or Al₂O₃, and selected from the following;

mica flake substrate+SnO₂ doped semiconducting layer,

mica flake substrate+SnO₂ doped semiconducting layer+TiO₂ layer,

mica flake substrate+SnO₂ doped semiconducting layer+SiO₂ layer,

mica flake substrate+SnO₂ doped semiconducting layer+ZnO layer,

mica flake substrate+SnO₂ doped semiconducting layer+Cr₂O₃ layer,

mica flake substrate+SnO₂ doped semiconducting layer+Al₂O₃ layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+TiO₂ layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+SiO₂ layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+ZnO layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+Cr₂O₃ layer, and

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+Al₂O₃ layer,

wherein said SnO₂ doped semiconducting layer has a tin to dopant molar ratio of 99.8;

0.2-99;

1, and

wherein

(a) the pigment volume concentration of the semiconducting pigment in said dielectric coating or dielectric article is 12-20% and the specific surface resistance of the coating or article is 10¹¹ to 10¹³ ohm*cm;

or

(b) wherein the pigment volume concentration of the semiconducting pigment in said dielectric coating or article is 11-20% and the specific surface resistance of the coating is 10⁷ to 10⁹ ohm*cm.

2. The dielectric coating or dielectric article according to claim 1, wherein the specific powder resistance of the semiconducting pigment is ≥

100 kohm cm and less than 1 gigaohm·

cm.

3. The dielectric coating or dielectric article according to claim 1, wherein the specific powder resistance of the semiconducting pigment is greater than 100 kohm·

cm and less than 1 gigaohm·

cm.

4. In a sensor, security application, floorcovering, film, ceramic material, glass, paper laser marking, thermal protection, photosemiconductor, or functional material for high-voltage technology comprising a dielectric coating the improvement wherein the dielectric coating is according to claim 1.

5. The sensor according to claim 4, wherein said sensor is a flat contact sensor.

6. The dielectric coating or dielectric article according to claim 1, wherein the substrate of said semiconducting pigment is mica flakes.

7. The dielectric coating or dielectric article according to claim 1, wherein said semiconducting layer is antimony-doped tin dioxide, fluorine-doped tin dioxide, chlorine-doped tin dioxide, tungsten-doped tin dioxide, molybdenum-doped tin dioxide, antimony- and titanium-doped tin dioxide, antimony- and iron-doped tin dioxide, or antimony- and phosphorus-doped tin dioxide.

8. The dielectric coating or dielectric article according to claim 7, wherein the semiconducting layer is antimony-doped tin oxide.

9. The dielectric coating or dielectric article according to claim 7, wherein the thickness of said semiconducting layer is 20-70 nm.

10. The dielectric coating or dielectric article according to claim 1, wherein the pigment contains 40-80% by weight of said substrate and 20-60% by weight of said semiconducting layer, based on the sum of said substrate and semiconducting layer.

11. The dielectric coating or dielectric article according to claim 1, wherein said substrate is mica flakes and the pigment contains 40-80% by weight of said substrate and 20-60% by weight of said semiconducting layer, based on the sum of said substrate and semiconducting layer.

12. The dielectric coating or dielectric article according to claim 1, wherein the substrate of said semiconducting pigment is mica flakes, having a particle size d₉₀<

15 μ

m, and the amount of said semiconducting layer is 35-60% by weight based on the total weight of the pigment.

13. The dielectric coating or dielectric article according to claim 1, wherein the substrate of said semiconducting pigment is mica flakes, having a particle size d₉₀<

60 μ

m, and the amount of said semiconducting layer is 20-40% by weight based on the total weight of the pigment.

14. The dielectric coating or dielectric article according to claim 1, wherein the specific powder resistance of the semiconducting pigment is ≥

100 kohm·

cm to 100 megaohm·

cm.

15. The dielectric coating or dielectric article according to claim 1, wherein said dielectric coating or dielectric article has a specific surface resistance σ

in the range between 1 and 1000 gigaohm.

16. The dielectric coating or dielectric article according to claim 1, wherein the average thickness of said further layer is 1 to 15 nm.

17. The dielectric coating or dielectric article according to claim 1, wherein the average thickness of said further layer is 5-10 nm.

18. The dielectric coating or dielectric article according to claim 1, wherein the thickness of said further layer is <

0.1 μ

m.

19. The dielectric coating or dielectric article according to claim 1, wherein the amount of said further layer 0.5-5% by weight, based on the amount of the semiconducting layer.

20. The dielectric coating or dielectric article according to claim 1, wherein the substrate of said semiconducting pigment is mica flakes, having a particle size d₉₀ 10 to 60 μ

m, and the amount of said semiconducting layer is 20-40% by weight based on the total weight of the pigment.

21. The dielectric coating according to claim 1, wherein the layer thicknesses of said coating is greater than 10 μ

m.

22. The dielectric coating or dielectric article according to claim 1, wherein the thickness of said semiconducting layer is 10-50 nm.

23. The dielectric coating or dielectric article according to claim 1, wherein said one or more semiconducting pigments are selected from the following:

mica flake substrate+SnO₂ doped semiconducting layer,

mica flake substrate+SnO₂ doped semiconducting layer+TiO₂ layer,

mica flake substrate+SnO₂ doped semiconducting layer+SiO₂ layer,

mica flake substrate+SnO₂ doped semiconducting layer+ZnO layer,

mica flake substrate+SnO₂ doped semiconducting layer+Cr₂O₃ layer, and

mica flake substrate+SnO₂ doped semiconducting layer+Al₂O₃ layer.

24. The dielectric coating or dielectric article according to claim 1, wherein said one or more semiconducting pigments are selected from the following:

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+TiO₂ layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+SiO₂ layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+ZnO layer,

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+Cr₂O₃ layer, and

Al₂O₃ flake substrate+SnO₂ doped semiconducting layer+Al₂O₃ layer.

25. The dielectric coating or dielectric article according to claim 1, wherein the average particle size d₅₀ of the pigment is between 2 and 8 μ

m.

26. The dielectric coating according to claim 1, wherein the pigment volume concentration of the semiconducting pigment in said dielectric coating is 11-18%.