Method of pre-treating woodchips prior to mechanical pulping

• US 7,943,008 B2
• Filed: 07/12/2010
• Issued: 05/17/2011
• Est. Priority Date: 02/21/2006
• Status: Expired due to Fees

• Current Assignee: Packaging Corporation of America
• Original Assignee: Packaging Corporation of America
• Inventors: Sorensen, Bryan L., Sethy, Anil, Kirov, Ventzislav H.
• Primary Examiner(s): Daniels; Matthew J
• Assistant Examiner(s): Calandra; Anthony J
• Application Number:
  US12/834,578
• Publication Number:
  US 20100276092A1
• Time in Patent Office: 309 Days
• Field of Search: 162 23- 26, 162/72, 162/90
• 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 woodchips comprising wood fibers;

cooking the woodchips in a 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;

after adding the dilution liquor to the pulp, 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 pulp.

2. The method of claim 1, wherein the first liquor is not acidic or alkali in nature prior to cooking the woodchips.

3. The method of claim 1, further comprising blending the refined pulp with recycled fibers to form a blended pulp that forms the corrugated medium.

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

cooking woodchips in a first liquor such that an acidic pH is obtained, the woodchips comprising wood fibers;

prior to separating 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;

after adding the dilution liquor to the pulp, 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 pulp.

5. The method of claim 4, wherein the first liquor is not acidic or alkali in nature prior to cooking the woodchips.

6. The method of claim 4, wherein the first liquor is water in the absence of an alkali addition.

7. The method of claim 4, wherein the acidic pH is from about 3 to about 4.

8. The method of claim 7, wherein the act of mechanically fiberizing the woodchips is performed at a pH of about 3 to about 4.

9. The method of claim 4, wherein the act of mechanically fiberizing is performed at an acidic pH.

10. The method of claim 4, wherein the pH of the woodchips is substantially unaltered between the act of cooking the woodchips and the act of mechanically fiberizing the woodchips.

11. The method of claim 4, further comprising blending the refined pulp with recycled fibers to form a blended pulp that forms the corrugated medium.

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

cooking woodchips in a first liquor such that an acidic pH is obtained, the woodchips comprising wood fibers;

prior to separating 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;

after adding the dilution liquor to the pulp, 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 the corrugating medium using the pulp; and

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

13. The method of claim 12, wherein the first liquor is not acidic or alkali in nature prior to cooking the woodchips.

14. The method of claim 12, wherein the first liquor is water in the absence of an alkali addition.

15. The method of claim 12, wherein the acidic pH is from about 3 to about 4.

16. The method of claim 15, wherein the act of mechanically fiberizing the woodchips is performed at a pH of about 3 to about 4.

17. The method of claim 12, wherein the act of mechanically fiberizing is performed at an acidic pH.

18. The method of claim 12, wherein the pH of the woodchips is substantially unaltered between the act of cooking the woodchips and the act of mechanically fiberizing the woodchips.

19. The method of claim 12, further comprising blending the refined pulp with recycled fibers to form a blended pulp that forms the corrugated medium.