Pulping processes

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...

AI Technical Summary

Benefits of technology

This patent describes a method for making fiber pulp by mixing a fiber source, water, a delignification chemical, and an alkali to create a first mixture. This mixture is then cooked for a specific amount of time at a certain condition to create a second mixture with a specific kappa number, tensile strength, and burst index. The resulting pulp composition has improved properties such as higher tensile strength and better burst index.

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.

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