| 摘要 |
1,145,286. Polyamide production. IMPERIAL CHEMICAL INDUSTRIES Ltd. 22 July, 1966 [30 April, 1965; 25 March, 1966], Nos. 18330/65 and 13442/66. Heading C3R. Linear fibre-forming polyamides are prepared by heating an aqueous liquid reaction mixture containing polyamide-forming ingredients under pressure in an apparatus which allows steam to escape, the lower zone of the wall of the reaction vessel below the final liquid level being maintained at a temperature above that of the reaction mixture for at least the latter part of the heating period and at the same time the upper zone of the wall being maintained at a temperature below that of the lower zone. The reaction mixture may be a 45-95% solution of hexamethylene diammonium adipate. The vessel may be one of those illustrated in Figs. 1 and 2 of the Provisional Specifications (not shown), i.e. it may comprise a vertical cylindrical vessel which has openings at the top and bottom but is otherwise completely surrounded by a heating jacket which is divided into 2 or 3 sections by horizontal annular partitions. In the earlier stages of reaction the lower zone only or both the lower and upper zones may be heated. The reaction temperature may be 110-300‹ C. and the pressure must be above atmospheric but not above 20 atmospheres. The temperature difference between the reaction mixture and the lower zone may be 5-250‹ C. and that between the lower and upper zones may be 0-200‹ C. |
