Production of crinkled cellulose ester filaments

Artificial filaments suitable for the manufacture of staple fibres, yarns, fabrics and artificial wool are produced by extruding a solution having a viscosity not exceeding 50 secs. (determined by a falling-ball method) of an organic derivative of cellulose, e.g. esters or ethers, in a volatile solvent through a spinning jet into a cell through which a current of evaporative medium is passed, the spinning temperature being below the boiling point of the solvent. The process is particularly applicable to the manufacture of artificial wool of improved resistance to stretching, by subjecting the filaments produced as above to the action of a hot aqueous medium, e.g. a hot soap solution, wet steam, or hot water. Suitable cellulose derivatives are the acetate, propionate, butyrate, acetate-propionate, acetate-butyrate and the Provisional Specification refers to the use of cellulose ethers, such as ethyl and butyl cellulose. The evaporative medium is a countercurrent or co-current of air, the temperature of which is preferably below the spinning temperature, but may be higher. Expeditious setting of the filaments is accomplished by reducing the speed of spinning, or increasing the length of path of the filaments through the evaporative medium. In the latter case, the filaments may be passed through a second evaporative medium at a higher temperature than that of the primary medium. The filaments may be assembled into yarns, with or without twisting at the time of or after spinning, and the yarns are converted into artificial wool by subjecting them to a hot aqueous treatment in hank form. Staple fibres may be spun into yarn prior to or after treatment by the hot aqueous medium. In an example, a solution of cellulose acetate in acetone of viscosity 25 is spun at a temperature of 42 DEG C. into a current of air at 30-35 DEG C. The filaments are twisted and assembled into yarn, which is then treated for 4 hours at a temperature of 90-100 DEG C. with a 0.5 per cent soap solution, washed and dried. The yarn is finally given an additional twist. Specifications 424,880, 442,073 and 464,981, [all in Group IX], are referred to.