ES312258A1 - Cold soluble cyanamide derivatives of amylaceous materials - Google Patents

Abstract

Dry cationic amylaceous material is made by reacting amylaceous material with cyanamide or an alkali metal or alkaline earth metal salt thereof in an aqueous medium at pH greater than 9, and then heating an aqueous medium containing the reaction product in order, if the product is not gelatinized, to gelatinize it, and, in any event, to dry the product, the pH of the aqueous medium immediately before the heating being below 4. The amylaceous material may be untreated starch, starch derivatives, e.g. hydrolysed starch, or starch ethers or esters, or amylose or amylopectin. Reaction with cyanamide is suitably carried out below 40 DEG C., and subsequent heating may be effected at atmosphere or under reduced pressure. If the cyanamide-starch reaction product is not in colloidal solution, the product may be gelatinized while being dried, suitably on a steam-heated drum. In one embodiment, the reaction product is removed from the reaction medium and washed before being re-suspended in an acid aqueous medium for heating and drying. Alternatively washing may be omitted. The solubility of the dry cationic product may be improved by the addition, to the aqueous medium before heating, of certain salts which make it possible to increase the pH at which gelatinization is carried out or drying is started. Salts which buffer between pH 2.5 and 4.0 are suitable. Specified salts are monoalkali orthophosphate, dialkalipyrophosphate aluminium sulphate or phosphate, and the chlorides of calcium, magnesium or zinc.