Process for producing a pulp suitable for papermaking from nonwood fibrous materials
First Claim
1. A process for producing a pulp suitable for making paper from a nonwood fiber source material, the process comprising:
- (a) providing a nonwood fiber source material;
(b) extracting the nonwood fiber source material with an alkaline pulping solution at at least about atmospheric pressure;
(c) reducing the pH of the nonwood fiber source material pH formed in step (b) to an acidic pH with an acid solution;
(d) treating the nonwood fiber source material having an acidic pH formed in step (c) with ozone; and
(e) treating the nonwood fiber source material of step (d) with a bleaching solution comprising a bleaching agent different from the ozone of step (d) to form a papermaking pulp, wherein the pulp has a freeness level of at least 400 mL CSF or greater and a brightness level of at least 70% ISO.
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Accused Products
Abstract
A process for producing a pulp suitable for papermaking from a nonwood fiber source material. Representative nonwood fiber source materials include corn stover and wheat straw. The process includes the steps of providing a nonwood fiber source material; digesting the nonwood fiber source material with an alkaline pulping solution at at least about atmospheric pressure; reducing the pH of the nonwood fiber source material to an acidic pH with an acid solution; treating the nonwood fiber source material having an acidic pH with ozone; and treating the nonwood fiber source material with a bleaching solution to form a papermaking pulp.
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Citations
64 Claims
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1. A process for producing a pulp suitable for making paper from a nonwood fiber source material, the process comprising:
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(a) providing a nonwood fiber source material;
(b) extracting the nonwood fiber source material with an alkaline pulping solution at at least about atmospheric pressure;
(c) reducing the pH of the nonwood fiber source material pH formed in step (b) to an acidic pH with an acid solution;
(d) treating the nonwood fiber source material having an acidic pH formed in step (c) with ozone; and
(e) treating the nonwood fiber source material of step (d) with a bleaching solution comprising a bleaching agent different from the ozone of step (d) to form a papermaking pulp, wherein the pulp has a freeness level of at least 400 mL CSF or greater and a brightness level of at least 70% ISO. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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27. A process for producing a pulp suitable for making paper from a nonwood fiber source material, the process comprising the sequential steps of:
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(a) providing a nonwood fiber source material;
(b) extracting the nonwood fiber source material with an alkaline pulping solution for about 1 to about 90 minutes at a pressure ranging from about atmospheric pressure to about 30 psig and at a temperature ranging from about ambient temperature to about 150°
C.;
(c) treating the nonwood fiber source material with an acid solution at a temperature ranging from ambient temperature to about 90°
C. and for a time ranging from about 30 to about 60 minutes to reduce the pH to an acidic pH;
(d) dewatering the nonwood fiber source material to a consistency of at least about 35% and then diluting the nonwood fiber source material to a lower consistency ranging from about 1% to about 10%;
(e) treating the nonwood fiber source material having an acidic pH with ozone; and
(f) treating the nonwood fiber source material with a bleaching comprising a bleaching agent different from the ozone of step (e) to form a papermaking pulp having a Kappa value of at least as low as 5, a freeness level of at least 400 mL CSF or greater and a brightness level of at least 70% ISO. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
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51. A process for producing a pulp suitable for making paper from a nonwood fiber source material, the process comprising the sequential steps of:
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(a) providing a nonwood fiber source material;
(b) extracting the nonwood fiber source material with an alkaline hydroxide pulping solution for about 30 to about 60 minutes at a pressure ranging from about atmospheric pressure to about 30 psig and at a temperature ranging from about 80°
C. to about 120°
C., wherein alkaline hydroxide in the alkaline hydroxide pulping solution is present in a dosage of ranging from about 10% weight to about 30% weight on ODF;
(c) reducing the pH of the nonwood fiber source material to a pH ranging from about 1 to about 3 with an acid solution at a temperature ranging from about 50°
C. to about 70°
C. and for a time ranging from about 20 minutes to about 30 minutes;
(d) dewatering the nonwood fiber source material to a consistency of at least about 35% and then diluting the nonwood fiber source material to a lower consistency ranging from about 1% to about 10%;
(e) treating the nonwood fiber source material having an acidic pH with ozone at about ambient temperature for about 5 to about 15 minutes, wherein the ozone is present in a dosage ranging from about 0.4% weight to about 1% weight on ODF;
(f) cleaning the nonwood fiber source material with at least one filtering screen; and
(g) treating the nonwood fiber source material with a bleaching solution comprising a bleaching agent different from the ozone of step (e) at a temperature ranging from about 70°
C. to about 110°
C. to form a papermaking pulp having a Kappa value of at least as low as 5, a freeness level of at least 400 mL CSF or greater and a brightness level of at least 80% ISO.- View Dependent Claims (52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64)
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Specification