High yield and enhanced performance fiber

Abstract

A method of wood pulping having a significantly increased yield is disclosed. Wood chips are chemically pulped to a high kappa number, providing a first accepts component and a first rejects component. The first rejects component is subjected to a high consistency pulping process such as a substantially mechanical pulping process to generate a second accepts component and a second rejects component. The first accepts component may be used in the production of saturating kraft paper with excellent saturability and resin pick up. The second accepts may be used as a second fiber source in the production of multiply linerboard and unbleached paperboard with enhanced stiffness, strength, and smoothness. Alternatively, the first accepts component may be blended with the second accepts component to produce fiber blends, which may be used in a production of paper-based products having enhanced strength and stiffness at low basis weight.

Description

[0001]This is a continuation-in-part application of co-pending and commonly assigned International Patent Application No. PCT / US2007 / 070927 filed Jun. 12, 2007, which is incorporated herein by reference.BACKGROUND OF THE DISCLOSURE[0002]Two main processes have been used for wood pulping: mechanical pulping and chemical pulping. Mechanical pulping primarily uses mechanical energy to separate pulp fibers from wood without a substantial removal of lignin. As a result, the yield of mechanical pulping is high, typically in the range of 85-98%. The produced fiber pulps generally have high bulk and stiffness properties. However, mechanical pulping consumes a high level of operational energy, and the mechanical pulps often have poor strength.[0003]In order to reduce the required energy level and improve fiber strength, other process options have been used in a combination with mechanical energy. Thermomechanical pulping (TMP) grinds wood chips under steam at high pressures and temperatures....

AI Technical Summary

Benefits of technology

[0018]The present disclosure relates to a method of wood pulping having a significantly increased yield and providing fiber pulps with enhanced properties such as strength and stiffness. The obtained fiber pulps are suitable for use in the production of paperboard packaging grade and multiply linerboard having improved stiffness and strength, compared to the conventional paperboard at the same basis weight. Additionally, the disclosed fiber pulps provide saturating kraft paper with excellent saturability and resin pick up that would allow converters to reduce the amount of phenolic resin required in producing phenolic laminate structure.

[0019]Wood chips are chemically pulped to a high kappa number, providing a first accepts component and a first rejects component. The first rejects component is subjected to a high consistency, substantially mechanical pulping process, optionally in a presence of caustic and / or bleaching agent, generating a second accepts component and a second rejects component. The first accepts component may be used in the production of saturating kraft paper with excellent saturability and resin pick up that requires a reduced amount of phenolic resin for the laminate construction. The second accepts may be used as a second fiber source in the production of multiply linerboard and unbleached paperboard with enhanced stiffness, strength, and smoothness. Alternatively, the first accepts component may be blended with the second accepts component to produce fiber blends. After being washed, the fiber blends may be subjected to a papermaking process to produce paper or paperboard with enhanced strength and stiffness at low basis weight. The disclosed method of wood pulping has a significantly increased fiber yield and provides fiber with equal, if not enhanced, performance compared to the fiber obtained from the conventional wood pulping process.

Problems solved by technology

However, mechanical pulping consumes a high level of operational energy, and the mechanical pulps often have poor strength.

However, using this prior technology, drawbacks exist from recooking the rejects which include an extremely low fiber yield, a potential increase in the level of pulp dirt, and a decrease in pulp brightness (poorer bleachability).

If a mill experiences cooking difficulties and accidentally undercooks the pulp, the amount of rejects increases exponentially.

Modern bleachable grade kraft pulp screen rooms are not physically designed to process pulps with greater than about 5% by weight of rejects.

However, all other known attempts to achieve a breakthrough of 5-10% yield increase have failed.

Additionally, the modified chemical pulping process often provides fiber pulps with lower tear strength.

However, a single-ply paperboard with an increased basis weight is economically undesirable because of a higher raw material cost and higher shipping cost for the packaging articles made of such board.

Good adhesion between each ply is critical to the performance of multiply board, leading to an additional factor that may deteriorate board properties.

However, a multiply paperboard with an increased basis weight is economically undesirable because of a higher production cost and higher shipping cost for the packaging articles made of such board.

Images