PURPOSE: To obtain a new starch paste which can give a paste solution having a stable viscosity and scarcely discolors even at a high pH by adding thiourea dioxide to an aqueous suspension of starch and heating the mixture to form a paste.
CONSTITUTION: An aqueous suspension of starch is converted into a paste by adding thiourea dioxide to the suspension. The obtained paste contains starch and thiourea dioxide. The amount of the thiourea dioxide added is desirably 0.05-2wt.% based on the solid matter of the starch suspension. When this amount is below 0.05wt.%, the intended effect can hardly be attained. On the contrary, when it is above 2wt.%, this effect reaches a plateau. In the preparation of the starch paste, it is possible to use on additive e.g. a water-soluble polymers such as polyvinyl alcohol or carboxymethylcellulose, an antiseptic, a dye and a pigment. Therefore, this paste is desirable as the one used for surface sizing and coating especially in the papermaking industry as well as common one.
SUNADA YOSHIKAZU
FUKUSHIMA RIKIO
