| 摘要 |
A composition known as methylene urea starch is prepared by suspending starch in an aqueous solution of urea and after allowing the suspension to stand adding aqueous formaldehyde, maleic anhydride, water, and acetone. After reaction first at 40 DEG C. and then at 60 DEG C. the solid product is filtered from the cooled reaction mixture, washed free of formaldehyde with water, the water removed by elution with acetone, and the product then dried. To prepare starch-N-phenyl carbamate undried rice starch is dehydrated with benzene by azeotropic distillation-water-free benzene is added during the process to maintain constant volume. After the drying phenyl isocyanate is added and the mixture refluxed. The product is then filtered off, washed with ethanol, and dried. Specifications 693,112, 836,148, 836,151, 838,245, 851,218, 853,880, 856,770, 860,560, 883,782, 891,043, 964,871, 964,873, 964,875, 964,877, 964,879, 964,884, 974,871 and 988,362 are referred to. |
