Method of improving impregnation of poly (meta-phenylene isophthalamide) fibers

A process for improving impregnation of poly(meta-phenylene isophthalamide fibers including the following steps

• extruding a solution of poly(meta-phenylene isophthalamide) and a solvent through orifices in a spinneret to form amorphous fibers which together define a fiber structure, such fibers having minute pores therein,
• moving such amorphous fibers into contact with an aqueous extraction bath to remove the solvent during which such fibers become water-swollen,
• contacting such water-swollen fibers with an aqueous mixture containing a water-soluble dye and an organic water-insoluble material which sublimes in steam at a temperature below the glass transition temperature of the fibers,
• heating the water-swollen fibers with steam at a temperature from about 110.degree. C. to 140.degree. C. for a time sufficient to diffuse substantially all of the water-soluble dye into the pores of such fibers throughout the fiber structure,
• heating the water-swollen fibers with steam at a sublimation temperature below the glass transition temperature of the fibers for a time sufficient to sublime the water-insoluble material into the pores of such fibers throughout the fiber structure, and thereafter
• heating the water-swollen fibers with steam at a temperature above the glass transition temperature of the fibers for a time sufficient to collapse the pores and irreversibly lock the dye within the fibers and to stabilize the fibers against progressive laundry shrinkage.

A process for improving impregnation of poly(meta-phenylene isophthalamide fibers including the following steps:

• extruding a solution of poly(meta-phenylene isophthalamide) and a solvent through orifices in a spinneret to form amorphous fibers which together define a fiber structure, such fibers having minute pores therein,
• moving such amorphous fibers into contact with an aqueous extraction bath to remove the solvent during which such fibers become water-swollen,
• contacting such water-swollen fibers with an aqueous solution containing a water-soluble material and heating the water-swollen fibers with steam at a temperature from about 110.degree. C. to 140.degree. C. for a time sufficient to diffuse substantially all of the water-soluble material into the pores of the fibers throughout such fiber structure,
• wherein the water-soluble material is a dye, and
• wherein the water-swollen, dye-containing fibers are then further heated with steam at a temperature above the glass transition temperature of the fibers for a time sufficient to collapse the pores and irreversibly lock the dye within the fibers and to crystallize such fibers and stabilize them against progressive laundry shrinkage.