Method of pre-treating woodchips prior to mechanical pulping

• US 7,771,565 B2
• Filed: 02/21/2006
• Issued: 08/10/2010
• Est. Priority Date: 02/21/2006
• Status: Active Grant

• Current Assignee: Packaging Corporation of America
• Original Assignee: Packaging Corporation of America
• Inventors: Sorensen, Bryan L., Sethy, Anil, Kirov, Ventzislav H.
• Primary Examiner(s): Hug; Eric
• Assistant Examiner(s): Calandra; Anthony J
• Application Number:
  US11/358,594
• Publication Number:
  US 20070193706A1
• Time in Patent Office: 1,631 Days
• Field of Search: 162/72, 162/90, 162/23, 162/24, 162/26
• US Class Current: 162/24
• CPC Class Codes: D21B 1/16 in the presence of chemical agents
• CPC Class Codes: D21C 1/02 with water or steam
• CPC Class Codes: D21C 11/0007 Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042
• CPC Class Codes: D21C 3/02 with inorganic bases or alkaline reacting compounds, e.g. sulfate processes

Abstract

A method of making pulp adapted to be used in forming corrugating medium is disclosed. The method comprises cooking woodchips in a first liquor in the absence of an alkali addition. The method further comprises mechanically fiberizing the woodchips to form a pulp. The method further comprises separating hydrolyzate from the pulp. The method further comprises treating the pulp with a second liquor, the second liquor including at least one alkali. The method further comprises refining the pulp.

Claims

1. A method of manufacturing a corrugating medium, the method comprising the acts of:

providing a first liquor that is not acidic or alkaline in nature;

providing woodchips comprising wood fibers;

cooking the woodchips in the first liquor, such that a pH of about 3 to about 4 is obtained after said cooking;

prior to separating hydrolyzate, mechanically fiberizing the woodchips at a pH of about 3 to about 4 to form a pulp;

subsequently adding a dilution liquor to the pulp, the dilution liquor including at least one alkali;

thereafter separating hydrolyzate from the pulp;

treating the pulp with a second liquor, the second liquor including a second at least one alkali;

refining the pulp;

blending the pulp with recycled fibers to form a blended pulp; and

forming the corrugating medium using the blended pulp.

2. The method of claim 1, wherein the recycled fibers include old corrugating containers, double-lined kraft clippings, or combinations thereof.

3. The method of claim 1, wherein the ratio of the first liquor to woodchips is from about 1.5:

1 to about 6;

1.

4. The method of claim 1, wherein the first liquor has a temperature ranging from about 320°

F. to about 370°

F. and the woodchips are cooked in the first liquor for about 5 to about 45 minutes.

5. The method of claim 1, wherein the act of cooking the woodchips in the first liquor is conducted in a batch digester or a continuous digester.

6. The method of claim 1, wherein the act of mechanically fiberizing the woodchips is conducted in a mechanical defibrator at a consistency of from about 25% to about 35%.

7. The method of claim 1, wherein the act of separating hydrolyzate from the pulp is conducted in an extraction press/impress refiner, a screw press, a drum washer, a chemiwasher, or a continuous digester with displacement washing.

8. The method of claim 1, wherein the second at least one alkali in the second liquor includes a hydroxide, a carbonate, or a combination thereof.

9. The method of claim 8, wherein the second at least one alkali in the second liquor includes sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, ammonium hydroxide, or combinations thereof.

10. The method of claim 1, wherein the temperature of the second liquor ranges from about 210°

F. to about 370°

F.

11. The method of claim 1, wherein the act of refining the pulp is conducted at a temperature ranging from about 100°

F. to about 210°

F. and a consistency of about 3% to about 6%.

12. The method of claim 1, wherein the act of refining the pulp includes obtaining a csf (freeness) from about 350 ml to about 500 ml.

13. The method of claim 1 further comprising, prior to the act of cooking the woodchips in the first liquor, presteaming the woodchips.

14. The method of claim 1 further comprising, prior to the act of cooking the woodchips in the first liquor, washing the woodchips.

15. The method of claim 1 further comprising, prior to the act of cooking the woodchips in the first liquor, exposing the woodchips to pressurized impregnation.

16. The method of claim 1, wherein the first liquor is water.

17. The method of claim 16, wherein the first liquor further includes a penetration aid.

18. The method of claim 16, wherein the first liquor further includes a wettability agent.

19. The method of claim 16, wherein the woodchips comprises hard wood fibers.

20. The method of claim 1, wherein the woodchips consist essentially of wood fibers.

21. A method of manufacturing a corrugated board, the method comprising the acts of:

providing a first liquor that is not acidic or alkaline in nature;

providing woodchips comprising wood fibers;

cooking the woodchips in the first liquor, such that a pH of about 3 to about 4 is obtained after said cooking;

prior to separating hydrolyzate, mechanically fiberizing the woodchips at a pH of about 3 to about 4 to form a pulp;

subsequently adding a dilution liquor to the pulp, the dilution liquor including at least one alkali;

thereafter separating hydrolyzate from the pulp;

treating the pulp with a second liquor, the second liquor including a second at least one alkali;

refining the pulp;

blending the pulp with recycled fibers to form a blended pulp;

forming the corrugating medium using the blended pulp; and

coupling the corrugating medium between a first outer ply and a second outer ply of linerboard to form a corrugated board.

22. The method of claim 21, wherein the recycled fibers include old corrugating containers, double-lined kraft clippings, or combinations thereof.

23. The method of claim 21 further comprising, prior to the act of cooking the woodchips in the first liquor, presteaming the woodchips.

24. The method of claim 21 further comprising prior to the act of cooking the woodchips in the first liquor, washing the woodchips.

25. The method of claim 21 further comprising prior to the act of cooking the woodchips in the first liquor, exposing the woodchips to pressurized impregnation.

26. The method of claim 21, wherein the first liquor is water.

27. The method of claim 26, wherein the first liquor further includes a penetration aid.

28. The method of claim 26, wherein the first liquor further includes a wettability agent.

29. The method of claim 21, wherein the woodchips comprises hard wood fibers.

30. The method of claim 21, wherein the woodchips consist essentially of wood fibers.

31. A method of manufacturing a corrugating medium, the method comprising the acts of:

providing a first liquor, the first liquor being water in the absence of an acidic or alkali addition;

providing woodchips comprising wood fibers;

cooking the woodchips in the first liquor, such that a pH of about 3 to about 4 is obtained after said cooking;

prior to separating hydrolyzate, mechanically fiberizing the woodchips at a pH of about 3 to about 4 to form a pulp;

subsequently adding a dilution liquor to the pulp, the dilution liquor including at least one alkali;

thereafter separating hydrolyzate from the pulp;

treating the pulp with a second liquor, the second liquor including a second at least one alkali;

refining the pulp; and

forming the corrugating medium using the refined pulp.

32. The method of claim 31 further comprising, prior to the act of cooking the woodchips in the first liquor, presteaming the woodchips.

33. The method of claim 31 further comprising prior to the act of cooking the woodchips in the first liquor, washing the woodchips.

34. The method of claim 31, wherein the first liquor further includes a penetration aid.

35. The method of claim 31, wherein the woodchips comprises hard wood fibers.

36. The method of claim 31, wherein the woodchips consist essentially of wood fibers.

37. A method of manufacturing a corrugating board, the method comprising the acts of:

providing a first liquor, the first liquor being water in the absence of an acidic or alkali addition;

providing woodchips comprising wood fibers;

cooking the woodchips in the first liquor, such that a pH of about 3 to about 4 is obtained after said cooking;

prior to separating hydrolyzate, mechanically fiberizing the woodchips at a pH of about 3 to about 4 to form a pulp;

subsequently adding a dilution liquor to the pulp, the dilution liquor including at least one alkali;

therafter separating hydrolyzate from the pulp;

treating the pulp with a second liquor, the second liquor including a second at least one alkali;

refining the pulp;

forming corrugating medium using the refined pulp; and

forming the corrugated board using the corrugating medium.

38. The method of claim 37, wherein the corrugating board further includes linerboard.

39. The method of claim 37, wherein the woodchips consist essentially of wood fibers.

40. A method of forming and treating a hydrolyzate, the method comprising the acts of:

providing a first liquor that is not acidic or alkaline in nature;

providing woodchips comprising wood fibers;

cooking the woodchips in the first liquor;

prior to removing hydrolyzate, mechanically fiberizing the woodchips to form a pulp;

subsequently adding a dilution liquor to the pulp, the dilution liquor including at least one alkali;

thereafter separating the hydrolyzate from the pulp;

treating the hydrolyzate so as to produce acetic acid, ethanol, xylitol, natural polymers, a biogas comprising methane, or combinations thereof; and

forming a corrugating medium with the pulp.

41. The method of claim 40, wherein the first liquor is water.

42. A method of forming and treating a hydrolyzate, the method comprising the acts of:

providing a first liquor, the first liquor being water in the absence of an acidic or alkali addition;

providing woodchips comprising wood fibers;

cooking the woodchips in the first liquor, such that a pH of about 3 to about 4 is obtained after said cooking;

prior to separating hydrolyzate, mechanically fiberizing the woodchips at a pH of about 3 to about 4 to form a pulp;

subsequently adding a dilution liquor to the pulp, the dilution liquor including at least one alkali;

thereafter separating the hydrolyzate from the pulp;

treating the hydrolyzate so as to produce acetic acid, ethanol, xylitol, natural polymers, a biogas comprising methane, or combinations thereof; and

forming a corrugating medium with the pulp.