Snia Fibre Spa

Gianfranco Casagrande

Giorgio Cazzaro

Antonino Cavallaro

Gianmarco Del Felice

The invention is concerned with a method of producing in-line dyed fibers, in a gel state, characterized in that it essentially consists of extruding the spinning dope in a coagulum bath, stretching the resulting filaments, scrubbing said filaments to remove residual solvent, passing the resulting filament tow through a dyeing bath at an overall rate in excess of 4 cm.sup.3 bath per second per square centimeter of tow surface area. The overall rate, being preferably in the 4 to 10 cm.sup.3 /sec per cm.sup.2 range, is achieved by means of crossflows to the forward advance direction of said tow, and alternately directed to and from said tow, the tow residence time in the dyeing bath being no longer than 5 seconds. The tow is then subjected to a dye fixing heat treatment, and is then scrubbed, finished, and dried. The method is particularly suitable for use with substantially acrylic and modacrylic fibers.

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Cesano Maderno, Italy

Gianfranco Casagrande