Process for crosslinking polysaccharides in a concentrated aqueous-organic medium – detergent formulations comprising same

A process for preparing a crosslinked polysaccharide, the process comprising:

• a) preparing a water-polar solvent mixture, the polar solvent is selected from the group consisting of aliphatic alcohols containing from one to four carbon atoms, ketones containing from three to five carbon atoms, polyols containing two or three hydroxyl groups and from two to six carbon atoms, and combinations thereof, wherein the preparation is carried out by mixing water and the polar solvent in weight proportions such that a weight ratio of the polar solvent to the water is greater than or equal to 0.4 and less than or equal to 19.0;
• b) dispersing at least one polysaccharide in the water-polar solvent mixture prepared in step a) to obtain a reaction medium comprising, per 100% of its weight, a weight proportion of the polysaccharide of greater than 10% by weight and less than or equal to 55% by weight, the polysaccharide is selected from the group consisting of xanthan gum, xanthan grafted with hydrocarbon chains containing from two to twenty-two carbon atoms, and combinations thereof;
• c) adjusting a pH of the reaction medium prepared in step b) to a value greater than or equal to 8.0 and less than or equal to 13.0 by adding a base thereto;
• d) crosslinking the at least one polysaccharide by adding, to the basic reaction medium obtained at the end of step c), a phosphate crosslinking agent selected from the group consisting of sodium trimetaphosphate (STMP), sodium tripolyphosphate (STPP), and combinations thereof to obtain a basic dispersion comprising at least one crosslinked polysaccharide;
• e) adjusting a pH of the basic dispersion obtained at the end of step d), to a value less than or equal to 7.0 to obtain a non-basic dispersion of the at least one crosslinked polysaccharide and
• f) filtering the non-basic dispersion obtained at the end of step e) to recover therefrom the at least one crosslinked polysaccharide, optionally followed by:
• either g) drying the at least one crosslinked polysaccharide to remove traces of residual solvents therefrom,
• or h) atomizing the at least one crosslinked polysaccharide obtained in step f) to obtain a powder therefrom.