Method of treating lignocellulosic or cellulosic pulp to promote the kinking of pulp fibres and/or to improve paper tear strength

• US 4,227,964 A
• Filed: 03/26/1979
• Issued: 10/14/1980
• Est. Priority Date: 12/01/1976
• Status: Expired due to Term

• Current Assignee: Allan J. Kerr, Robert P. Kibblewhite
• Original Assignee: Allan J. Kerr, Robert P. Kibblewhite
• Inventors: Kibblewhite, Robert P., Kerr, Allan J.
• Primary Examiner(s): Fisher, Richard V.
• Assistant Examiner(s): Alvo, Steve
• Application Number:
  US06/023,768
• Time in Patent Office: 568 Days
• Field of Search: 162/63, 162/65, 162/72, 162/90, 162/9, 162/50, 162/53
• US Class Current: 162/9
• CPC Class Codes: D21C 9/004 inorganic compounds

Abstract

The invention relates to a process comprising the saturation of a lignocellulosic or cellulosic pulp in gaseous ammonia. In one embodiment this is followed by subjection of the saturated pulp to vacuum. The treatment promotes the kinking of pulp fibres and/or improves the tearing strength of paper prepared therefrom.

Claims

1. A method of kinking pulp fibers in order to increase the tear strength of papers made from such fibers, wherein the pulp is a lignocellulosic or cellulosic pulp derived from a chemical, semichemical or chemimechanical pulping process, said method comprising kinking pulp fibers having a consistency of approximately 15 up to approximately 400 weight percent of dried pulp in the total material, water plus pulp, while substantially maintaining pulp yield by treating the pulp with gaseous ammonia at a pressure of at least one atmosphere until at least 9% by weight, based on the weight of oven dried pulp, of gaseous ammonia has been taken up by the moist pulp.

2. The method according to claim 1 wherein said pulp is a softwood pulp.

3. The method according to claim 1 wherein said pulp is derived in a yield of up to 80%.

4. The method according to claim 1 wherein said pulp is a semi-chemical pulp derived in a yield of up to 75%.

5. The method according to claim 1 wherein said pulp is produced by a bisulphite process in a yield of up to 75%.

6. The method according to claim 1 wherein said pulp is a chemical pulp.

7. The method according to claim 1 wherein said pulp has a consistency of up to 30 weight percent of dried pulp in the total material, water plus pulp.

8. The method according to claim 1 wherein said treatment with gaseous ammonia is followed by a pressure release.

9. The method according to claim 8 wherein said treatment with gaseous ammonia is carried out in a cyclical manner with a pressure phase followed by a pressure release.

10. The method according to claim 9 including up to five pressure phases alternating with pressure release phases of up to 1 hour between each phases.

11. The method according to claim 10 wherein each said pressure phase is applied for up to 2 hours.

12. The method according to claim 1 wherein said pulp is refined prior to said treatment with said gaseous ammonia.

13. The method according to claim 1 wherein said pulp is not refined prior to said treatment with gaseous ammonia.

14. The method according to claim 1 wherein said pulp is bleached prior to said treatment with gaseous ammonia.

15. The method according to claim 1 wherein said pulp is bleached following said treatment with gaseous ammonia.

16. The method according to claim 1 wherein said treatment with gaseous ammonia is carried out at a temperature of 0-150°

C.

17. Method according to claim 1 wherein said pulp is a chemical pulp produced by a process selected from the group consisting of Kraft-type processes and soda-oxygen-type processes.

18. Method according to claim 1 wherein said treatment with gaseous ammonia is followed by subjecting said pulp to a vacuum.

19. Method according to claim 18 wherein said treatment with gaseous ammonia is carried out in a cyclical manner with a pressure phase followed by a vacuum phase.

20. Method according to claim 19 including up to 5 pressure phases alternating with vacuum phases of up to one hour between phases.

21. Method according to claim 1 wherein said pressure is up to 15 atmospheres.