Claims
- 1. A method for the production of a light-stable, lignocellulosic material comprising reacting the material with a water-soluble, yellowing inhibitor possessing a primary or secondary amino group of the formula A, B, C or D wherein Y is oxyl (O) or hydroxyl (OH) in an aqueous medium, or with a water-soluble hindered amine light stabilizer of the formula A or B wherein Y is hydrogen (H) in an alkaline peroxide bleaching medium or in an aqueous medium with a subsequent bleaching of the reacted material in an alkaline peroxide bleaching medium
- 2. A method according to claim 1 wherein said material is reacted with said yellowing inhibitor in said aqueous medium.
- 3. A method according to claim 1 wherein said material is reacted with said stabilizer in said alkaline peroxide bleaching medium.
- 4. A method according to claim 1 wherein said material is reacted with said stabilizer in an aqueous medium with a subsequent bleaching of the reacted material in said alkaline peroxide bleaching medium.
- 5. A method according to claim 1 wherein said lignocellulosic material is a wood pulp and including steps of
forming a paper from the resulting pulp and coating the paper with an ultraviolet absorber.
- 6. A method according to claim 1, wherein at least one of R1, R2, R3, R4 and R5 is a said alkyl group substituted with an organic ultraviolet absorber derived from 2,4-dihydroxybenzophenone or 2-hydroxybenzophenone.
- 7. A method according to claim 1 wherein X is selected from carbonate, chloride bisulfate, sulfate, formate, acetate, citrate, phosphate and ascorbate.
- 8. A method according to claim 1 wherein the yellowing inhibitor is 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl.
- 9. A method according to claim 1, wherein the hindered amine light stabilizer is 4-amino-2,2,6,6-tetramethylpiperidine.
- 10. A method according to claim 1, wherein the reaction of the lignocellulosic material is conducted with a charge of the yellowing inhibitor or hindered amine light stabilizer of 0.01 to 2.0%, by weight, based on the oven dry weight of the lignocellulosic material.
- 11. A method according to claim 10 wherein said amount is 0.2 to 1.0%, by weight.
- 12. A method according to claim 1 wherein the reaction is conducted at a temperature of 20-120° C., a consistency of 1.5-50%, and a time of 5 minutes to several days.
- 13. A method according to claim 1, wherein the reaction in an aqueous medium is conducted at a pH of 3.5-12.5.
- 14. A method according to claim 1, wherein a reducing agent or an acid is added to the reaction medium.
- 15. A method according to claim 1, wherein the material is a pulp and the resulting pulp is treated with a reducing agent or an acid.
- 16. A method according to claim 1 wherein the reaction and/or bleaching is conducted in the presence or absence of air or oxygen.
- 17. A method according to claim 1, wherein the lignocellulosic material is a mechanical wood pulp and the reaction is carried out in a single-stage or multi-stage in one or more than one refiner, bleach tower, pulp mixer, a storage vessel, or any other reaction vessel suitable for performing the alkaline hydrogen peroxide bleaching of the pulp.
- 18. A method according to claim 1 wherein the lignocellulosic material is wood chips and at least one of said reacting and bleaching is carried out in a single-stage or multi-stage in one or more than one impregnator.
- 19. A method according to claim 18 wherein the impregnation of the wood chips is conducted at a temperature of 40-90° C., a solid content of 30-60%, by weight, and an impregnation time of 5 minutes to 2 hours.
- 20. A light stable lignocellulosic material comprising a lignocellulosic material having a yellowing inhibitor of formula A, B, C or D wherein Y is oxyl (O−) or hydroxyl (OH) covalently linked thereto via a primary or secondary amino group of the inhibitor or stabilizer:
- 21. A material according to claim 20 wherein the lignocellulosic material is a mechanical wood pulp.
- 22. A paper sheet containing a material according to claim 20.
- 23. A paper sheet according to claim 22 containing said pulp in conjunction with a chemical pulp.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is related to U.S. Provisional Application S. No. 60/233,434 filed Sep. 18, 2001 and U.S. Provisional S. No. 60/269,886 filed Feb. 21, 2001, and the benefit under 35 USC 119(e) of such U.S. Provisional Applications is claimed.
Provisional Applications (2)
|
Number |
Date |
Country |
|
60233434 |
Sep 2000 |
US |
|
60269886 |
Feb 2001 |
US |