Method for treating dissolving pulp

a technology of dissolving pulp and dissolving liquid, which is applied in the direction of multi-stage pulping process, cellulose treatment using microorganisms/enzymes, and inorganic base pulping, etc., to achieve uniform molecular weight distribution, high cellulose content, and high brightness

Pending Publication Date: 2021-07-08
NOVOZYMES AS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0012]Dissolving pulp: Dissolving pulp is a high-grade cellulose pulp, with low contents of hemicellulose, lignin and resin. This pulp has special properties, such as high level of brightness and uniform molecular weight distribution. It is used to make products that include rayon and acetate textile fibers, cellophane, photographic film and various chemical additives. To a large extent, use of dissolving wood pulp depends on its purity (cellulose content), which depends mainly on the production process. To obtain products of high quality, these so-called “special” pulps must fulfill certain requirements, such as high cellulose content, low hemicellulose content, a uniform molecular weight distribution, and high cellulose reactivity. Most of the commercial dissolving pulps accomplish these demands to a certain extent. Nevertheless, achieving high cellulose accessibility as well as solvent and reagent reactivity is not an easy task due to the compact and complex structure presented by the cellulose. About 77% of all dissolving pulp is used in the manufacture of cellulosic fibers (rayon and acetate).

Problems solved by technology

Commercial dissolving pulp is manufactured for uses that require a high chemical cellulose purity, and particularly low hemicellulose content, since the chemically similar hemicellulose can interfere with subsequent processes.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

LPMO Treatment of Unbleached Hardwood Kraft Dissolving Pulp

[0114]Unbleached hardwood kraft dissolving pulp with a kappa number of 6.8 (TAPPI T 236 procedure), ISO brightness of 51% and an intrinsic viscosity of 1025 mL / g produced by a pre-hydrolysis kraft pulping process and further treated with a cold-caustic extraction stage from a dissolving pulp production process was used. This pulp was treated with several LPMOs in a small-scale assay using 24 mg of oven-dry fiber at 0.4% consistency, 45° C., pH 5.0 (acetate buffer, 50 mM) for 20 hours. The enzyme treatment (denoted as X-stage) was done at a dosage of 5 mg EP (enzyme protein) / g odp (oven-dry pulp).

[0115]The pulp suspension at 0.4% consistency was disintegrated with a magnetic bar in glass test tubes placed in a heating block at 45° C. Ascorbic acid, gallic acid or pyrogallol was added as electron donor to a final concentration of 1 mM in the suspension, followed by the addition of the LPMO enzyme to a final volume of 6 mL. Aft...

example 2

LPMO Treatment of Bleached Hardwood Kraft Dissolving Pulp

[0118]Bleached hardwood kraft never dried pulp of acetate-grade produced by a pre-hydrolysis kraft pulping process having an ISO brightness of 93.7% and an intrinsic viscosity of 684 mL / g was used. This pulp was treated with several LPMOs with three different electron donors using the same conditions and procedures as in Example 1.

[0119]The aspiration pressure results from the mViPr measurements are presented in Table 2 for the bleached dissolving pulps. LPMOs can reduce the average size of the cellulose molecules as expressed by the reduction in the solution (dissolved pulp) viscosity, measured by the reduction in aspiration pressure. Higher reduction in bleached pulp viscosity compared to controls (no enzyme) were achieved when the LPMOs were used together with gallic acic and pyrogallol as compared to the ascorbic acid which also reduces signfificantly viscosity itself. Tt LPMO is a more robust LPMO regarding viscosity redu...

example 3

Effect of LPMO Treatment with / without Endoglucanase at Medium Pulp Consistency on Bleached Dissolving Pulp Viscosity, Reactivity and CHO Content

[0120]Bleached hardwood kraft dissolving pulp produced by a pre-hydrolysis kraft pulping process of viscose-grade was used having an intrinsic viscosity of 512 mL / g. This pulp was treated with several LPMOs using gallic acid (1 mM) as electron donor at 1.5% consistency in Distek vessels (Distek model Symphony 7100) with heating and continuous overhead stirring.

[0121]Once the pulps were disintegrated and at the temperature set-point of 45° C., gallic acid was added and then the enzyme (LPMO and / or endoglucanase). The enzyme treatment of the pulp took 25.5 hour at pH 5.0 (acetate buffer, 50 mM) using 2 mg EP / g odp of LPMO and 1.2 mg EP / kg odp of endoglucanase. After the enzyme treatment, the pulps were filtered and washed in three consecutive steps with 1 L of tap water. Part of the pulp sample was dried before measuring the CHO content and Fo...

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Abstract

The present invention relates to treatment of dissolving pulp with a lytic polysaccharide monooxygenase. The lytic polysaccharide monooxygenase treatment results in reduced viscosity and/or improved viscosity control in the dissolving pulp production process and/or 5 increased reactivity of the dissolving pulp.

Description

REFERENCE TO SEQUENCE LISTING[0001]This application contains a Sequence Listing in computer readable form. The computer readable form is incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates to treatment of dissolving pulp with one or more enzymes. The enzymatic treatment results in reduced viscosity and / or improved viscosity control in the dissolving pulp production process and / or increased reactivity of the final dissolving pulp.BACKGROUND OF THE INVENTION[0003]Commercial dissolving pulp or dissolving-grade pulp is a chemical bleached pulp with a high cellulose content enough to be suitable for the production of regenerated cellulose and cellulose derivatives. Commercial dissolving pulp has special properties, such as a high level of brightness and uniform molecular-weight distribution. Commercial dissolving pulp is manufactured for uses that require a high chemical cellulose purity, and particularly low hemicellulose content, since the chemica...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21C5/00D21C9/10D21C3/02D21C3/26D21C3/00
CPCD21C5/005D21C9/1005D21C3/003D21C3/26D21C3/022D21C3/02D21C9/00D21H11/20D01F2/00D01C1/00
Inventor LOUREIRO, PEDRO EMANUEL GARCIASCHARFF-POULSEN, ANNE MARIETOVBORG, MORTEN
Owner NOVOZYMES AS
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