Abstract: A fatty acid ester of cellulose having excellent transparency, filterability and spinnability in spite of its high content of mannose and xylose, wherein the total molar content of mannose and xylose accounts for at least 7% of that of glucose, mannose and xylose, and the amount of filtration satisfies a specified requirement. Such a fatty acid ester of cellulose is prepared by using a pulp having a low .alpha.-cellulose content as a raw material and a fatty acid corresponding to the ester as a diluent and adding an organic solvent in an amount of at least 10% by weight based on the diluent in any step during the preparation. In the preparation of cellulose diacetate, which excellent filterability and transparency, by the acetic acid process, the cellulose diacetate obtained by aging is dissolved in a solvent which can dissolve it and the resulting cellulose diacetate is recovered.

Abstract: A process for producing cellulose acetate from a hard, low-grade pulp sheet having a high sheet density on an industrial scale without impairing the acetylation reactivity of the pulp, characterized in that a pulp sheet having a sheet density of at least 0.5 g/cm.sup.3 is used as the cellulose material and the pulp sheet is disintegrated while feeding less than 40 parts by weight, based on 100 parts by weight (in terms of oven-dry weight) of the pulp sheet, of water into the disintegrating section of a disintegrator in the step of disintegrating the material. The present process is economically advantageous because the drying and humidity controlling steps are simplified due to the quantity of water to be fed being small.