Courtaulds Plc

Vaillant Gmbh

Richard Burley

Lucjan S Slota

Patrick Roche

Paul Leedham

Paul Mc Gowan

A process for making cellulose acetate from wood pulp takes wet wood pulp and instead of converting it into dry pulp sheet which is the usual feedstock for acetate, dries and mechanically separates the pulp into a cellulose flock using a pin mill through which a hot drying gas is passed. Deactivation of the cellulose is avoided by control of the drying gas exit temperature to 80.degree. C. to 95.degree. C. and of the moisture content of the cellulose flock to 4 to 15% by weight. The flock produced may be acetylated directly without any need for reactivation treatments additional to the normal activation with acetic acid.

Process for the production of cellulose acetate from wood pulp

Cellulosic sheet material is processed in preparation for esterification for example acetylation to produce cellulose acetate, by treating the sheet material with water and then feeding the wetted material into a machine that simultaneously shreds and dries the material. The conditions in the machine are carefully controlled (outlet temperature not in excess of 110.degree. C. and moisture content 4-15% by weight) to ensure that the cellulosic material does not become deactivated towards esterification. The method enables low alpha content cellulosic material supplied in the form of high density sheet to be acetylated to produce high quality cellulose acetate flake.

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Derby, United Kingdom

Richard Burley