Machine Wet anion impurities cause and countermeasures - Paper, anionic impurities - Paper Industry

Machine Wet anion impurities cause and countermeasures - Paper

, anionic impurities - Paper Industry

With the coating damage paper, deinking waste paper, the use of high-yield pulp and paper machine white water loop closure level increases, paper machine wet interference rising concentration of anion impurities on the paper machine wet end operation against an increasingly large number of cationic additives and to become worse. Especially with the alkaline papermaking system to the transformation of aluminum sulfate as the glue fixing agent is no longer added to the slurry, the anion impurities (anionictrash) issues become more prominent. Therefore, understanding the source of the anion impurities, hazards and countermeasures is necessary.

Source anion impurities and its harm

1.1 source anion impurities Anion impurities is the existence of paper machine wet all the dissolved anionic oligomer or polymer and non-ionic general term for the hydrolysis colloid. These anions have different properties and impurity sources:

(1) from the pulp, such as lignin derivatives, hemicellulose, fatty acids.

(2) from the anion additives, such as starch, CMC, organic acids, dyes, fungicides and so on.

(3) from the filler dispersant, such as polyphosphate, polyacrylate, etc..

(4) from the water, such as humic acid, fungicides and so on.

Most harmful impurities from the pulp anion, so here only introduce impurities from the pulp of the anion accumulation. From stock preparation to every aspect of papermaking involve the accumulation of anionic impurities. In stock preparation, experience shows that: the long-term storage of the wood fiber strength and adversely affect the bleaching process, but thus reducing storage time Queshi terpenes and other volatile substances is not isolated; so viscous material, such as the esterification of fatty acids can not be oxidized and saturated, an increase of storage time was shortened pulp anion impurities.

Straw pulp in the shortage of raw materials if the use of the new straw pulp, also as fodder in the pectin, starch and other natural fermentation removed without an increase in the anion impurities straw. In the pulping process, wood and grass materials depends largely on the raw material into pulp lignin, hemicellulose, extractives, etc. dissolution, which dissolved substances that constitute the main papermaking system, the organic anion impurities. The amount of organic anion impurities and pulping and bleaching process conditions, process control, the extent of bleached pulp wash has a close relationship. In general use of high yield pulp and waste paper pulp mills with the maximum amount of anionic impurities from a variety of mechanical pulp and semi-chemical pulp of anion impurities mainly lignin sulfonate, humic acid and anionic forms of plastic material existence of soluble substances.

Anion impurities from waste paper pulp is mainly a large number of lignin derivatives and waste paper and other species of the anion impurities. Including loss of use of coated paper or paper mills but also has the highest volume and most complex ion exchange. Coated paper or paper loss, particularly the use of calcium carbonate and titanium dioxide coated paper or paper damage, the coating contains large amounts of anionic dispersing agent (when using starch as an adhesive to bond than the use of protein needed more time dispersant, rapid increase in the concentration of anionic impurities.

The terms of General Chemistry bleached pulp, straw pulp containing more than anion impurities. Regardless of what kind of paper pulp, paper pulp wash is caused by low plasma concentration of impurities in the anion the most direct reason. Of marking the sheet, the use of calcium carbonate as filler and coating pigment, that is in neutral or alkaline papermaking conditions, because you can not use aluminum sulfate as fixing agent, so get in and anion impurities; addition anion impurities in alkaline pH, the anion will be more ionized groups; and alkaline low molecular weight hemicellulose may also be dissolved out from the fiber cell wall (such substances, including xylose and arabinose, the chitosan-based ); closed under acidic conditions in the fiber cells of some colloidal substances in alkaline swelling because the cell wall may also be released. Therefore alkaline papermaking cause higher concentrations of soluble anion impurities.

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