Treated Kraft pulp compositions and methods of making the same

Patent metadata

Field	Value
Publication number	US-11332883-B2
Application number	US-201816236093-A
Country	US
Kind code	B2
Filing date	Dec 28, 2018
Priority date	Dec 31, 2013
Publication date	May 17, 2022
Grant date	May 17, 2022

Abstract

Compositions including treated Kraft pulp, useful for making rayon fibers, having a lower degree of polymerization, a high R18, a low hemicellulose content, and high reactivity, are described. Methods of making the compositions are also described.

First claim

The invention claimed is:

1. A treated Kraft pulp blend, comprising:
a dissolving pulp; and
a treated Kraft pulp, comprising:
a hemicellulose content of 5% or more;
a R 18 value of 88% or more; and
at least one reactivity value selected from:
a standard reactivity of 3.5 mL or more,
a modified reactivity of 30 mL or more,
a filter value Kr of 10,000 or less,
a SEM fiber segment count of 11 or less per 100 μm 2 of a filter when the pulp is subjected to a modified reactivity test, and
a crystallite cross-section of less than 20.6 nm 2 ;

wherein the treated Kraft pulp has less than 8% by weight of cellulose II as determined by x-ray crystallography;
wherein the treated Kraft pulp blend comprises a gamma number of 50% or less; and
wherein the treated Kraft pulp blend comprises at least 20% by weight of the treated Kraft pulp.

2. The treated Kraft pulp blend of claim 1 , wherein the hemicellulose content of the treated Kraft pulp is greater than 7%.

3. The treated Kraft pulp blend of claim 1 , wherein the R18 of the treated Kraft pulp value is from 88% to 92%.

4. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp further comprises one or more of a pentosan content of from 4.6% to 9%, a xylan content of 4% to 8%, and a mannan content of 3% to 8%.

5. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp comprises a standard reactivity of 5 mL or more.

6. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp comprises a modified reactivity of 50 mL or more.

7. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp comprises a filter value Kr of 8,000 or less.

8. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp further comprises a carboxyl content of less than 3.6 meq/100g.

9. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp further has an ASTM degree of polymerization of from 600 to 900.

10. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp further has a copper number of from 0.3 to 1.2.

11. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp has 0% cellulose II as determined by x-ray crystallography.

12. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp has an ageing time of 50 hours or less to reach a target Cuox DP of 340.

13. The treated Kraft pulp blend of claim 1 , wherein the treated Kraft pulp further has a copper number of from 0.2 to 1.6.

14. The treated Kraft pulp blend comprising of claim 1 , wherein:
the dissolving pulp has a R18 of greater than 92%; and
the blend comprises a total xylan and mannan content of 6% or more.

15. The treated Kraft pulp blend of claim 14 , further comprising a surfactant.

16. The treated Kraft pulp blend of claim 14 , wherein the blend further comprises a filter value Kr of 15,000 or less.

17. The treated Kraft pulp blend of claim 14 , wherein the blend further comprises a gamma number of 45.1% or more.

18. The treated Kraft pulp blend of claim 14 , wherein the blend has an ageing time of 50 hours or less to reach a target Cuox DP of 340.

19. A treated Kraft pulp blend, comprising:
a treated Kraft pulp, comprising:
a hemicellulose content of 5% or more;
a R18 value of 88% or more; and
a gamma number of 60% or less; and

a dissolving pulp;
wherein the treated Kraft pulp has less than 8% by weight of cellulose II as determined by x-ray crystallography;
wherein the treated Kraft pulp blend comprises a gamma number of 50% or less; and
wherein the treated Kraft pulp blend comprises at least 20% by weight of the treated Kraft pulp.

Assignees

• Int Paper Co

Inventors

• Luo Mengkui
• Parthasarathy Venketa Ranganathan

Classifications

• D21C9/1026

  Other features in bleaching processes · CPC title

• D21C9/144 Primary

  with ClO2/Cl2 and other bleaching agents in a multistage process · CPC title

• D21H11/16 Primary

  modified by a particular after-treatment · CPC title

• D21C9/123

  with Cl2O · CPC title

• D21H11/04 Primary

  Kraft or sulfate pulp · CPC title