White pigment reflecting IR radiation, production and use thereof

Patent metadata

Field	Value
Publication number	US-10023746-B2
Application number	US-201514641976-A
Country	US
Kind code	B2
Filing date	Mar 9, 2015
Priority date	Dec 21, 2005
Publication date	Jul 17, 2018
Grant date	Jul 17, 2018

Abstract

The invention relates to a pigment which reflects IR radiation, comprising an IR-reflecting core, the IR-reflecting core being provided with a substantially enveloping coating which is transparent to IR radiation, and in that the IR-reflecting pigment is substantially white. The invention further relates to a process for producing these pigments and also to their use.

First claim

What is claimed is:

1. A process for producing an IR-reflecting pigment, wherein a coating which is substantially transparent to IR radiation is applied, together with white pigments, to an IR-reflecting core, wherein the IR-reflecting core is provided with a substantially enveloping coating which is substantially transparent to IR radiation and in that the IR-reflecting pigment is substantially white, wherein the IR-reflecting core is a platelet-shaped aluminum pigment and wherein the pigment reflecting IR radiation possesses a flop index of 0 to 3, said flop index being determined with the following formula

Flop
⁢

⁢
index

=

2.69
×

(

L

15
⁢
°

*

-

L

110
⁢
°

*

)

1.11

(

L

45
⁢
°

*

)

0.86

wherein the IR-transparent coating is SiO 2 and wherein the white pigments are applied together with SiO 2 to the IR-reflecting core by a wet chemical sol-gel process and wherein at the end of the sol-gel process the platelet-shaped IR-reflecting core coated with the white pigments and SiO 2 is separated from unreacted starting materials and from the solvent, and wherein the IR-reflecting pigment is dried under reduced pressure.

2. The process for producing an IR-reflecting pigment of claim 1 , wherein in, on and/or under the coating that is substantially transparent to IR radiation there are white pigments.

3. The process for producing an IR-reflecting pigment of claim 2 , wherein the white pigments have an average primary particle size of 180 to 400 nm.

4. The process for producing an IR-reflecting pigment of claim 2 , wherein the white pigments are selected from the group consisting of titanium dioxide, zinc oxide, magnesium oxide, zinc sulfide, calcium fluoride, lithium fluoride, sodium fluoride, potassium fluoride, calcium carbonate, lithopones, magnesium carbonate, barium sulfate, barium titanate, barium ferrite, and mixtures thereof.

5. The process for producing an IR-reflecting pigment of claim 2 , wherein the white pigments are TiO 2 , ZnS and/or ZnO.

6. The process for producing an IR-reflecting pigment of claim 1 , wherein the white pigments are present in an amount of 20% to 80% by weight, based on the weight of the total IR-reflecting pigment.

7. The process for producing an IR-reflecting pigment of claim 1 , wherein the white pigments are arranged substantially uniformly around the IR-reflecting core.

8. The process for producing an IR-reflecting pigment of claim 1 , wherein the substantially IR-transparent coating is present in a fraction of 4% to 30% by weight, based on the weight of the total IR-reflecting pigment.

9. The process for producing an IR-reflecting pigment of claim 1 , wherein the platelet-shaped aluminum pigment IR-reflecting core has a size of 5 to 150 μm.

10. The process for producing an IR-reflecting pigment of claim 1 , wherein the platelet-shaped aluminum pigment IR-reflecting core has a size of 5 to 12 μm.

11. The process for producing an IR-reflecting pigment of claim 1 , wherein said pigment is worked into inks, paints, varnishes, printing inks, security-printing inks, or cosmetics.

12. The process for producing an IR-reflecting pigment of claim 11 , wherein said paint is an emulsion paint for the interior and exterior sector.

13. The process of claim 2 , wherein the white pigments have an average primary particle size of 250 to 370 nm.

14. The process of claim 2 , wherein the white pigments are present in an amount of 35% to 70% by weight, based on the weight of the total IR-reflecting pigment.

15. The process of claim 7 , wherein the white pigments are present in an amount of 0.3 to 10 g, per 1 m 2 of the surface area of the IR-reflecting core in the IR-reflecting pigment.

16. The process of claim 7 , wherein the white pigments are present in an amount of 0.5 to 7 g, per 1 m 2 of the surface area of the IR-reflecting core in the IR-reflecting pigment.

17. The process of claim 1 , wherein the white pigment is TiO 2 , ZnS and/or ZnO.

18. The process of claim 1 , wherein the white pigment has an average primary particle size of 250 to 320 nm.

19. The process of claim 1 , wherein the white pigment has an average size of 180 to 400 nm.

20. A process for producing an IR-reflecting pigment wherein a coating which is substantially transparent to IR radiation is applied, together with white pigments, to an IR-reflecting core, said process consisting of the following steps, the IR-reflecting core is provided with a substantially enveloping coating which is substantially transparent to IR radiation such that the IR-reflecting pigment is substantially white, wherein the IR-reflecting core is a platelet-shaped aluminum pigment and wherein the pigment reflecting IR radiation possesses a flop index of 0 to 3, said flop index being determined with the following formula

Flop
⁢

⁢
index

=

2.69
×

(

L

15
⁢
°

*

-

L

110
⁢
°

*

)

1.11

(

L

45
⁢

Assignees

• Eckart Gmbh

Inventors

• Henglein Frank
• Schramm Christian
• Schmidt Ulrich
• Weiss Harald
• Bleisteiner Jasmin
• Grüner Michael

Classifications

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C09C1/642

  treated with inorganic compounds · CPC title

• C09C2200/505

  Inorganic particles, e.g. oxides, nitrides or carbides · CPC title

• C09C3/063

  Coating · CPC title

• C09C2220/10

  Wet methods, e.g. co-precipitation · CPC title