Stabilization of acrylonitrile fibers to hot-wet creep

Claim 2

A process as defined in claim 1 wherein said acrylonitrile polymer contains up to about 5 percent of another ethylenically unsaturated comonomer copolymerizable with acrylonitrile and wherein said fiber is heated to between 100* C. and about 150* C. with the steam.

Claim 3

A process as defined in claim 3 wherein said acrylonitrile polymer contains about 95 percent acrylonitrile and about 5 percent methyl methacrylate.

Claim 4

In a process for wet spinning acrylonitrile polymer fibers which includes the steps of extruding, coagulating, washing, stretching, and drying the fibers so spun, the improvement comprising (a) using in said wet-spinning process an acrylonitrile polymer containing at least about 95 percent of acrylonitrile and (b) heating such fibers subsequent to drying and while in a substantially tensionless state in the presence of wet steam under pressure to a temperature above 100* C. but below the temperature where substantial shrinkage of said fibers occurs, thereby reducing the tendency of said fibers to creep under hot-wet conditions.

Claim 5

A process as defined in claim 5 wherein said acrylonitrile polymer is a homopolymer of acrylonitrile and wherein said fibers are heated to between 100* C. and about 160* C. with the steam.

Claim 6

A process as defined in claim 5 wherein said acrylonitrile polymer contains up to about 5 percent of another ethylenically unsaturated comonomer copolymerizable with acrylonitrile and wherein said fiber is heated to between 100* C. and about 150* C. with the steam.