Method for the dyeing of leather and dyed leather having a high rubbing fastness

Patent metadata

Field	Value
Publication number	US-12291817-B2
Application number	US-202118013129-A
Country	US
Kind code	B2
Filing date	Jun 28, 2021
Priority date	Jun 30, 2020
Publication date	May 6, 2025
Grant date	May 6, 2025

Abstract

A method for dyeing leather with an organic colorant in a supercritical fluid. The method includes coating a surface of the leather to provide a coated surface of the leather. The method further includes dyeing the coated surface of the leather with the organic colorant in the supercritical fluid.

First claim

The invention claimed is:

1. Method for dyeing leather with an organic colorant in a supercritical fluid, the method comprising:
coating a surface of the leather to provide a coated surface of the leather, wherein the coating comprises an organically based varnish; and
dyeing the coated surface of the leather with the organic colorant in the supercritical fluid.

2. The method according to claim 1 , wherein only the coated surface of the leather is dyed with the organic colorant in the supercritical fluid.

3. The method according to claim 1 , wherein coating the surface of the leather comprises coating in amounts of 2 to 50 g/ft2.

4. The method according to claim 1 , wherein the organic colorant comprises at least one dye.

5. The method according to claim 4 , wherein the at least one dye comprises at least one of suspending agent-free disperse dyes, solvent dyes, food dyes, and pigments.

6. The method according to claim 1 , wherein the supercritical fluid is obtained from supercritical carbon dioxide.

7. The method according to claim 1 , wherein the dyeing of the coated surface of the leather is carried out under the admission of pressure and/or temperature.

8. The method according to claim 1 , wherein the dyeing of the coated surface of the leather is carried out by impregnating the coated surface with the organic colorant.

9. The method according to claim 8 , wherein the coated surface is impregnating with the organic colorant such that a high rub fastness is achieved having a score in a range of 4 or more according to ISO 11640:2012 and ISO 105 A03.

10. The method according to claim 1 , wherein the organic colorant is used in amounts between 0.01 to 0.75 g/ft2 for dyeing the leather.

11. The method according to claim 1 , wherein the organic colorant comprises a solubility in the supercritical fluid in a range of 10-3 to 10-8 M/M based on the molar amount of the supercritical fluid.

12. The method according to claim 1 , wherein the surface of the leather is coated and the coated surface is dyed so as to produce a dyed leather having a rub fastness RFT with a grade in a range of at least 4 determined according to ISO 11640:2012 and ISO 105 A03.

13. A dyed leather having a rub fastness RFT with a score in a range of at least 4 determined according to ISO 11640:2012 and ISO 105 A03, the dyed leather being produced by the method of claim 1 .

14. The dyed leather according to claim 13 , wherein a skin side of the leather is coated.

15. The dyed leather according to claim 13 , wherein the coated surface is impregnated with the organic colorant, the organic colorant comprising at least one of disperse dyes, solvent dyes, food dyes, and pigments.

16. Leather products having a rub fastness RFT with a grade in a range of at least 4 determined according to ISO 11640: 2012 and ISO 105 A03, the leather products being produced by the method of claim 1 .

17. A method for dyeing leather having a coating comprising an organically based varnish on its surface, the method comprising dying the coating with an organic colorant in a supercritical fluid such that the coating of the leather is dyed with a high rub fastness.

18. A method for dyeing a product comprising a leather having a coating wherein the coating comprises an organically based varnish on its surface, the method comprising dying the coating with an organic colorant in a supercritical fluid such that the coating of the product is dyed with a high rub fastness.

Assignees

• Fraunhofer Ges Forschung

Inventors

• Prokein Michael
• Renner Manfred

Classifications

• D06P3/32

  leather {skins} · CPC title

• D06P1/94 Primary

  using dyes dissolved in solvents which are in the supercritical state · CPC title