Patent GB-770763-A (GB)
Title: Improvements in or relating to the production of starch derivatives and conversion products
IPC: C08B30/12
Filed: 1953-03-17
Abstract: In the process for making starch derivatives and their conversion products disclosed in the parent Specification, the etherifying or acetal-forming agent is added continuously or at intervals after at least part of the evaporation of water has been effected and, if thermal treatment is employed, during or after such treatment. Evaporation of water may be interrupted temporarily by reducing the temperature and at the same time partially reducing the vacuum.  In an example, moist starch is impregnated with hydrochloric acid gas, water is evaporated from the mixture in vacuo with gradual raising of the temperature to 100 DEG  C., the vacuum is maintained and the temperature is increased to 165 DEG  C.  Powdered paraformaldehyde is then mixed in and the temperature is maintained until the desired degree of conversion is attained.  The product is then cooled in vacuo.  In another example, moist starch impregnated with sodium carbonate solution is heated up to 70 DEG  C. in vacuo to evaporate some water.  The starch is then mixed with more aqueous sodium hydroxide and ethylene chlorhydrin and heated to 125 DEG  C. in vacuo to evaporate more water.  More aqueous sodium hydroxide and ethylene chlorhydrin are added and a further amount of water is evaporated by heating in vacuo up to 140 DEG  C.  Still more aqueous sodium hydroxide and ethylene chlorhydrin are added and the temperature is maintained until the desired degree of conversion is attained and the product is then cooled in vacuo.  Specification 630,914, [Group V], also is referred to.ALSO:In the process for making starch derivatives and their conversion products disclosed in the parent Specification, the etherifying or acetal-forming agent is added continuously or at intervals after at least part of the evaporation of water has been effected, and, if thermal treatment is employed, during or after such treatment.  Evaporation of water may be interrupted temporarily by reducing the temperature and at the same time partially reducing the vacuum.  In an example, moist starch is impregnated with hydrochloric acid gas, water is evaporated from the mixture in vacuo with gradual raising of the temperature to 100 DEG C., the vacuum is maintained and the temperature is increased to 165 DEG C.  Powdered paraformaldehyde is then mixed in and the temperature is maintained until the desired degree of conversion is attained.  The product is then cooled in vacuo.  In another example, moist starch impregnated with sodium carbonate solution is heated up to 70 DEG C. in vacuo to evaporate some water.  The starch is then mixed with more aqueous sodium hydroxide and ethylene chlorhydrin and heated to 125 DEG C. in vacuo to evaporate more water.  More aqueous sodium hydroxide and ethylene chlorhydrin are added and a further amount of water is evaporated by heating in vacuo up to 140 DEG C.  Still more aqueous sodium hydroxide and ethylene chlorhydrin are added and the temperature is maintained until the desired degree of conversion is attained and the product is then cooled in vacuo.  Specification 630,914 is referred to.