Method of production of preparations of starch blowing cold, the solutions give, after drying of the layers resistant to water, and of solutions of these preparations of the starch, and products resulting therefrom

摘要

Starch products capable of dissolving in cold water to form solutions which when dried by heating on a substratum in the presence of a substance which promotes condensation of starch with an aldehyde produce water-insoluble layers are made by heating a mixture of starch or a starch derivative with a proportion of water not greater than twice the weight of the starch or starch derivative and with an aldehyde, especially formaldehyde, or a substance yielding an aldehyde by decomposition, on a rotary drum while pressing mechanically to form a thin layer which dries simultaneously or immediately afterwards, more than 10 per cent of aldehyde, calculated on the weight of dry starch or starch derivative being employed and the heating on the drum being, at a temperature below 140 deg. C., and the Ph of the mixture so heated being preferably 5-7. Specifications 494,927 and 632,789 are referred to. The Specification as open to inspection under Sect. 91 comprises also making cold swelling starch in the presence of more than 10 per cent of aldehyde at a temperature below 140 degrees C. without restriction otherwise on the mode of procedure, and the production of water insoluble layers from solutions of such cold-swelling starch merely by drying. This subject-matter does not appear in the Specification as accepted.