Abstract: The invention relates to a hydrophobic polymer dispersion and a solvent-free process for the preparation thereof. According to the invention, the dispersion contains starch ester together with dispersion admixtures known as such. According to the process, the polymer is first mixed with a plasticizer in order to obtain a plasticized polymer blend. The plasticized polymer blend is then mixed with dispersion admixtures and water at an elevated temperature so as to form a dispersion. The plasticizing of the polymer and the dispersion of the mixture in water can be performed in an extruder. The obtained dispersion is homogenized in order to improve its stability. The dispersion obtained by the invention can be used to coat paper or board, as a primer or a component in paint or labeling adhesives, and it is also suitable for the production of cast films and as a binder in materials based on cellulose fibers, as well as for coating medicinal preparations.

Abstract: Process for the preparation of a starch ester, in particular a starch acetate, wherein a starch-based feedstock is reacted with an organic carboxylic acid anhydride in the presence of a catalyst. The reaction of the starch-based feedstock and the anhydride is performed at an excess pressure of about 0.1 to 50 bar in an essentially anhydrous medium containing 10% by weight of water at the most. As catalyst, sodium acetate, sodium hydroxide or sulphuric acid is used, and as the reaction medium, acetic acid or excess acetanhydride is used. By means of the invention, the duration of the esterification reaction can be significantly shortened, the separation of the product can be facilitated, and the recirculation of the waste solutions can be rendered more efficient.