Method for dyeing and/or retanning of leather

Patent metadata

Field	Value
Publication number	US-12049676-B2
Application number	US-202017607374-A
Country	US
Kind code	B2
Filing date	Apr 29, 2020
Priority date	Apr 29, 2019
Publication date	Jul 30, 2024
Grant date	Jul 30, 2024

Abstract

A method for dyeing and/or retanning of leather objects includes providing a leather object. The leather object has been processed by at least a tanning process. The leather object is introduced into a process chamber. The leather object is subjected in the process chamber to a pressurized fluid. The pressure of the pressurized fluid is controlled to reach a supercritical state. The leather object is subjected to a dyeing agent and/or a retanning agent, which dyeing or retanning agent is dissolved and/or transported in the pressurized fluid for at least a predefined period of time while the pressurized fluid is in the supercritical state. The pressure is reduced in the process chamber. The leather object is removed from the process chamber. The pressure reduction is controlled over time.

First claim

The invention claimed is:

1. A method for dyeing and/or retanning of leather objects, said method comprising steps of:
providing a leather object, which leather object has been processed by at least a tanning process,
introducing the leather object into a process chamber,
subjecting the leather object in the process chamber to a pressurized fluid,
controlling a pressure of the pressurized fluid to reach a supercritical state,
subjecting the leather object to a dyeing agent and/or a retanning agent, which dyeing or retanning agent is dissolved and/or transported in the pressurized fluid for at least a predefined period of time while the pressurized fluid is in the supercritical state,
reducing the pressure in the process chamber, and
removing the leather object from the process chamber,
wherein the step of reducing the pressure in the process chamber comprises controlling the pressure reduction over time.

2. The method according to claim 1 , wherein the step of reducing the pressure in the process chamber further comprises removing the pressurized fluid from the process chamber.

3. The method according to claim 1 , further comprising the step of removing residue dyeing agent and/or retanning agent from the pressurized fluid during or after the pressurized fluid is removed from the process chamber.

4. The method according to claim 1 , wherein the pressurized fluid that is removed from the process chamber is led to a storage container under storage pressure.

5. The method according to claim 1 , wherein the dyeing agent is a collagen reactive dyeing agent.

6. The method according to claim 1 , wherein an amount of dyeing agent and/or retanning agent is dosed in dependence of a weight, a thickness, and/or a surface area of the leather object.

7. The method according to claim 1 , wherein an amount of dyeing agent and/or retanning agent is dosed in dependence of a type of the leather object.

8. The method according to claim 1 , wherein the leather object is primed with a primer agent prior to being subjected to the pressurized fluid.

9. The method according to claim 1 , further comprising a step of dosing the dyeing agent into the process chamber in an automated manner, based on leather object characteristics.

10. The method according to claim 1 , wherein the step of subjecting the leather object to a dyeing agent and/or retanning agent, which dyeing agent or retanning agent is dissolved and/or transported in the pressurized fluid for at least a predefined period of time while the pressurized fluid is in the supercritical state, further comprises mixing, stirring, or circulation of the pressurized fluid in the supercritical state.

11. The method according claim 1 , wherein the pressure of the pressurized fluid in the supercritical state is at least 70 bar.

12. The method according to claim 1 , wherein a temperature of the pressurized fluid in the supercritical state is between 30 to 120 degrees Celsius.

13. The method according to claim 1 , wherein a predetermined time, during which the leather object is subjected to the dyeing agent and/or the retanning agent in the pressurized fluid in the supercritical state, is at least 1 min.

14. The method according to claim 1 , further comprising a step of providing a leather material, which leather material has been processed by at least a tanning process, whereby the at least one leather object is cut from the leather material prior to being provided and introduced into the process chamber.

15. The method according to claim 1 , wherein a pressure reduction is controlled over time such that a reduction period exceeds 5 min.

16. The method according to claim 1 , wherein a pressure reduction is controlled over time such that the pressure reduction does not exceed a predefined leather pressure reduction gradient of 10 bar/min.

17. The method according to claim 1 , wherein the pressure of the pressurized fluid is controlled to reach the supercritical state such that the time period exceeds a predefined increase period of 5 min.

18. The method according to claim 1 , wherein the pressurizing of the pressurized fluid in the process chamber to reach the supercritical state comprises that an increase of pressure does not exceed a predefined leather pressure increase gradient of 20 bar/min.

Assignees

• Ecco Sko As

Inventors

• Gogsig Thomas
• Coremans Ilona Francisca Maria
• Petrusic Stojanka

Classifications

• D06P3/3286

  using reactive dyes · CPC title

• D06P1/94

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

• C14C3/28

  Multi-step processes · CPC title

• C14C3/30

  using physical means combined with chemical means · CPC title

• D06P3/32 Primary

  leather {skins} · CPC title