The invention concerns a process for the manufacture of an acylated polysaccharide which comprises. (a) reacting a polysaccharide with an acylating agent to produce an acylated polysaccharide and (b) washing the acylated polysaccharide with water containing from 0.05 to 15 mg/l Ca.sup.2+-ions (c) recovering the washed acylated polysaccharide and an aqueous phase containing carboxylic acid from step (b).

Disclosed is a process for solubilising cellulose and coagulating the resulting solution to form a cellulose-containing material. The process comprises contacting a cellulose source with a solvent comprising zinc ions and formic acid to provide a solution, coagulating the solution to provide a solid material, treating the solid material, and isolating the solid material after treatment, to provide the cellulose-containing material. The process can further comprise solubilising protein and coagulating the resulting solution to form a cellulose/protein-containing material. The cellulose-containing materials and cellulose/protein-containing materials can be produced, for example, as reconstituted fibres and films.

Disclosed is a process for solubilising cellulose and coagulating the resulting solution to form a cellulose-containing material. The process comprises contacting a cellulose source with a solvent comprising zinc ions and formic acid to provide a solution, coagulating the solution to provide a solid material, treating the solid material, and isolating the solid material after treatment, to provide the cellulose-containing material. The process can further comprise solubilising protein and coagulating the resulting solution to form a cellulose/protein-containing material. The cellulose-containing materials and cellulose/protein-containing materials can be produced, for example, as reconstituted fibres and films.

The purpose of the present invention is to provide cellulose acetate excellent in transparency.

The method for producing cellulose acetate flakes includes the steps of (a) generating a cellulose acetate dope by reacting cellulose with acetic anhydride in a presence of an acid catalyst and an acetic acid solvent; (b) hydrolyzing the generated cellulose acetate to adjust an acetylation degree to 52% or more and 59% or less; (c) precipitating the adjusted cellulose acetate in a presence of water; (d) forming the cellulose acetate obtained by precipitation into a slurry by dispersing the cellulose acetate in a mixed solvent including a solvent having a solubility parameter of 8 to 13 and a solvent having a solubility parameter of 14 or more; and (e) separating the cellulose acetate from the slurry to form the cellulose acetate into flakes, the mixed solvent containing 30% by weight or more and 70% by weight or less of the solvent having a solubility parameter of 8 to 13.

The purpose of the present invention is to provide cellulose acetate excellent in transparency.

The method for producing cellulose acetate flakes includes the steps of (a) generating a cellulose acetate dope by reacting cellulose with acetic anhydride in a presence of an acid catalyst and an acetic acid solvent; (b) hydrolyzing the generated cellulose acetate to adjust an acetylation degree to 52% or more and 59% or less; (c) precipitating the adjusted cellulose acetate in a presence of water; (d) forming the cellulose acetate obtained by precipitation into a slurry by dispersing the cellulose acetate in a mixed solvent including a solvent having a solubility parameter of 8 to 13 and a solvent having a solubility parameter of 14 or more; and (e) separating the cellulose acetate from the slurry to form the cellulose acetate into flakes, the mixed solvent containing 30% by weight or more and 70% by weight or less of the solvent having a solubility parameter of 8 to 13.

A nutrient composition contains a cellulose acetate having a total degree of acetyl substitution of 0.4 to 1.1. The cellulose acetate may have a compositional distribution index (CDI) of 2.0 or less, where the CDI is specified by the formula:

CDI=(Measured value of half height width of chemical composition)/(Theoretical value of half height width of chemical composition)

where the measured value of half height width of chemical composition represents the half height width of chemical composition determined by HPLC analysis of a cellulose acetate propionate prepared by propionylating all residual hydroxy groups of the cellulose acetate (sample); and

[Math. 1]

the theoretical value of half height width of chemical composition

=2. 35482{square root over (3*DPw*(DS/3)*(1DS/3))}/DPw

where DS is the total degree of acetyl substitution; and DPw is a weight-average degree of polymerization determined by a GPC-light scattering method using a cellulose acetate propionate prepared by propionylating all residual hydroxy groups of the cellulose acetate (sample).

Disclosed herein is cellulose acetate that has excellent heat stability under wet conditions and is capable of reducing the occurrence of end-breakage in a spinning process.

Cellulose acetate satisfying the following formula (1):

[Mg/H.sub.2SO.sub.4]>0,[Ca/H.sub.2SO.sub.4]>0, and

2.70?[Mg/H.sub.2SO.sub.4])/1.62?[Ca/H.sub.2SO.sub.4]?(37.7?[Mg/H.sub.2SO.sub.4])/10.3(1), where the formula (1) represents a relationship between a chemical equivalent ratio of calcium content to residual sulfuric acid content [Ca/H.sub.2SO.sub.4] and a chemical equivalent ratio of magnesium content to residual sulfuric acid content [Mg/H.sub.2SO.sub.4].

This invention relates to novel compositions comprising regioselectively substituted cellulose esters. One aspect of the invention relates to processes for preparing regioselectively substituted cellulose esters from cellulose dissolved in ionic liquids. Another aspect of the invention relates to the utility of regioselectively substituted cellulose esters in applications such as protective and compensation films for liquid crystalline displays.

This invention relates to novel compositions comprising regioselectively substituted cellulose esters. One aspect of the invention relates to processes for preparing regioselectively substituted cellulose esters from cellulose dissolved in ionic liquids. Another aspect of the invention relates to the utility of regioselectively substituted cellulose esters in applications such as protective and compensation films for liquid crystalline displays.

An object is to provide a cellulose acetate remarkably good in hue even when a low-quality pulp is used.

A method for producing the cellulose acetate includes a step (1) of crushing a wood pulp, a step (2) of bringing the crushed wood pulp into contact with acetic acid to subject the pulp to pretreat the wood pulp, a step (3) of causing the wood pulp to react with acetic anhydride after the pretreatment to acetylate the pulp, a step (4) of hydrolyzing the cellulose acetate, which is yielded by the acetylation, and a step (5) of precipitating the cellulose acetate, an acetylation degree of which is adjusted by the hydrolysis. In the hydrolyzing step (4), in a hydrolysis reaction system, a concentration of oxygen is set to 3% or less.