Akzo N.v.

Angelika Reiche

Michael Diamantoglou

Joachim Behnke

Thomas Rintelen

Gustav Duweg

Edmund Richter

Ralf Tatas

Hans-Dieter Brauer

A process for improving the biocompatibility of cellulosic film membranes is characterized by the fact that the film membranes are coated during or after their preparation with cellulose ethers and/or cellulose esters and/or cellulose carbamates whose structures conform to the formulas ##STR1## wherein Cell is the skeleton of the unmodified cellulose molecule without hydroxyl groups; x conforms to the degree of modification, which is in the range of 0.002 to 3; R is an (optionally substituted) alkyl and/or alkenyl and/or aryl and/or arylalkyl group and the carbon chain of the group R contains 1 to 36 carbon atoms and may be interrupted by hetero atoms such as O, S, N, and contains basic and/or acidic groups such as 13 NR'.sub.2, --COOR', and/or --SO.sub.3 R' or their salts, wherein R'=H or R.

Method for coating cellulosic membranes

In a process for chlorine-free bleaching of cellulose with an .alpha.-cellulose content of more than 90%, preferably from boiled cotton linters, more than 75% whiteness is achieved in a single-stage process using oxygen. The bleaching is conducted using the oxygen obtained by disproportionation of peroxo compounds in the pH range from 6 to 13 and with the bleaching time, depending on the bleaching temperature of 35.degree. C. to 15.degree. C., being between 15 and 150 minutes.

Oxygen bleaching of cotton linters by disproportionation of hydrogen

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Cologne, Germany

Angelika Reiche