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Abstract

The invention relates to a method for improving the colour index of cellulose esters especially consisting of cellulose acetate. According to the inventive method, a delignified eucalyptus pulp is subjected to a preliminary treatment in order to remove pigments or chromophoric substances, and the process-modified eucalyptus pulp obtained is converted into cellulose esters in a conventional manner. The inventive method is characterized in that a delignified eucalyptus pulp having a cellulose content of more than approximately 80 wt. % and a pentosan content of more than approximately 1 wt. % is extracted by means of a solvent which dissolves oligomer pentosans but not the pulp of the delignified eucalyptus pulp, especially at a temperature of up to approximately 200 .degree. C. and a pressure of up to approximately 30 bar. The inventive method leads to an improvement in the colour index of cellulose esters or the fibres and filaments produced therefrom, in an economical and technically simple manner.

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First Claim