Dyeing synthetic fibres - solid dyestuff extracted from a deposit by hot solvent dye liquor circulated through dye bath,

摘要

For dyeing with water insoluble dyestuff, the solid dyestuff is placed in a receptacle as a filter (cellulosic, glass fibre etc.) at atmospheric pressure, hot solvent is dropped on to it from an upper, heated container. When a sufficient quantity is in the lower part of the receptacle (heated or kept hot by a heat exchanger) it is admitted to the dyebath and circulated through a small circuit including the bath by a pump. Fresh dyestuff may be added from time to time from the receptacle. The liquor concentration may be increased by distillation from the receptacle. The liquor concentration may be thus increased from 1:20 to 1:5-1:3.