GB580764A - Improvements in or relating to the manufacture of composite artificial filaments - Google Patents

Abstract

Crimped composite artificial filaments are obtained by forming composite filaments having at least two eccentrically arranged components of different shrinkage characteristics, stretching the filaments beyond the elastic limit of at least one of the components, relaxing the filaments while in an at least partially softened condition obtained by softening before, during or after stretching, and bringing the filaments into unsoftened condition while retaining them in relaxed condition. The composite filaments may be obtained by extruding two or more different spinning compositions through adjacent orifices or extruding them in separate or only partially intermingled phases through a common orifice or a plurality thereof into a gaseous or liquid setting medium as described in Specification 579,081, and the setting medium may function by either a cooling, precipitating or evaporative effect. Any filament-forming materials or solutions which differ in composition, origin or characteristics such as differing solutions of viscose, proteins such as casein or soya bean protein, cellulose derivatives such as cellulose acetate or ethyl cellulose, and resins such as nylon, vinyl resins such as the copolymers of vinyl chloride and vinyl acetate and the vinylidene halides, may be employed. Alternatively, two or more materials of different classes may be combined such as a protein with a viscose, a protein with a cellulose acetate or a cellulose acetate with a vinyl resin. One or more of the filament components is softened with, e.g. hot or cold water, or heat or swelling agents, before or after stretching, and the stretched filaments are cooled or dried in a relaxed state to set the crimp. If two thermoplastic components having different shrinkage characteristics at a given temperature are combined, the after-stretched composite filaments may be crimped by subjecting them in relaxed condition to the given temperature. Stretching may be effected on the composite filaments as they come from any stage of the liquid after-treatment process to which they are usually subjected, and when a stretch is applied to the filaments during their production, the amount of after-stretch is reduced accordingly.