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Pulping processes

a technology which is applied in the field of pulp composition and pulping process, can solve the problems of low pulp strength, insufficient reduction of kappa in existing pulping process, and inability to provide wood pulps having a sufficient reduction in kappa

Inactive Publication Date: 2015-05-14
CARGILL INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Depolymerizing the cellulose weakens the fibers and lowers the strength of the pulp obtained.
A pulp having a higher Kappa number will make ECF or TCF bleaching difficult, requiring oxygen delignification and / or ozone, and / or far more peroxide.
Generally, existing pulping processes do not provide wood pulps having a sufficient reduction in Kappa without the use of multiple delignification processes and / or unacceptable destruction or weakening of the cellulose in the pulp.
Thus, a substantial challenge in reducing nonwood raw materials into fibers for papermaking is to find a pulping method which addresses one or more of the criteria set forth above.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Cleaning of Raw Fibers

[0074]Bagasse was used as an example of raw fibers. Bagasse was first hydrated for 10 minutes with hot clean water (temperature of water was above room temperature, about 40° C., or 60° C.), under moderate agitation, at a consistency of 0.5% to 2.0%. Pith and sand were separated from the fibers in a Trammel Screen, which was a rotating drum that lifted and dropped the material and accepted water and pith through ⅛th inch holes up to ½″ holes. The rejected material was collected and removed from the screen to prevent accumulation, and disposed, and was dried before added into the pulping process. The washing yield was about 80% or higher, or about 85.9%, depending on quality of the bagasse starting material.

example 2

Soda AQ Pulping of Bagasse

[0075]OD bagasse (cleaned as described in Example 1, Kappa number was 89) was treated with sodium hydroxide (20% by weight of the OD bagasse) and AQ (0.3% by weight to the dry weight of OD bagasse) at a liquid to dry fiber ratio of 7 (consistency of about 12.5%), at maximum temperature of about 175° C. for 35 or 40 minutes. Time to the maximum temperature was 60 minutes.

[0076]The target H-factor was 0.1060, as low as 20, and as high as 3000, and the temperature of the pulping reaction was 120° C. to 185° C. The Kappa number of the obtained pulp was 4.5.

example 3

Washing of Pulp

[0077]A pulp obtained from Example 2 was washed in a pressure diffuser washer designed specifically to accomplish all washing with a single unit without introducing undesired modifications to the pulp. The temperature of the wash water was chosen to cool the pulp temperature to about 100° C., 95° C., 90° C., 85° C., 80° C. or lower. The output went to a bleaching step and was cooled to 100° C. or less to prevent flashing.

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Abstract

A pulping process comprises using a high concentration of anthraquinone (AQ). The pulping process is capable of providing a pulp having low Kappa number with unexpectedly high strength. The pulping process can use wood or non-wood fibers (e.g., bagasse and corn stover) to provide pulp having good papermaking quality. The method for pulping a fiber comprising cooking a first mixture comprising the fibers, water, an alkali, and a delignification selectivity enhancing chemical for a cooking time and at a cooking condition sufficient to form a first pulp having a desired Kappa number of about 15 or less, and strength parameters that are sufficient for papermaking, where the starting material prior to cooking has a Kappa number of 60 or greater.

Description

FIELD OF THE INVENTION[0001]The disclosure relates to pulping processes and pulp compositions prepared therefrom.BACKGROUND[0002]“Pulping” generally refers to the reduction of a bulk fiber source material into its component fibers. Wood and other plant materials used to make pulp generally contain three main components (apart from water): cellulose fibers (desired for papermaking), lignin (a three-dimensional polymer that binds the cellulose fibers together) and hemicelluloses (shorter branched carbohydrate polymers). The aim of pulping is to break down the bulk structure of the fiber source, be it chips, stems or other plant parts, into the constituent fibers.[0003]Chemical pulping achieves this by degrading the lignin into small, water-soluble molecules which can be washed away from the cellulose and hemicellulose fibers without depolymerizing them. Depolymerizing the cellulose weakens the fibers and lowers the strength of the pulp obtained. Although lignin in pulp may enhance str...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21H17/00
CPCD21H17/74D21C3/222D21C5/00D21C9/14D21C3/02D21C3/003
Inventor HAWKINS, BRENT A.MARTIN, FRED
Owner CARGILL INC
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