Fixation of polypropylene fibers impregnated with dyestuffs and other treating agents

Claim 1

A METHOD FOR PREPARING A MELT-SPUN STRUCTURED POLYPROPYLENE FIBER HAVING NUMBERLESS ULTRA-FINE VOIDS DISTRIBUTED THROUGHOUT THE FIBER AND HAVING AN INITIAL SOLVENT ABSORBENCY GREATER THAN 25%, SAID VOIDS BEING SO FINE AND SO DISTRIBUTED THROUGHOUT THE FIBER THAT IT IS DIFFICULT TO DISTINGUISHABLY RECOGNIZE THE INDIVIDUAL VOIDS UNDER OBSERVATION BY AN OPTICAL MICROSCOPE IN BRIGHT FIELD ILLUMINATION, THE WHOLE FIBER HAVING A GLIMMERING ASPECT WHEN OBSERVED BY AN OPTICAL MICROSCOPE UNDER DARK FIELD ILLUMINATION, SAID FIBER CONTAINING IN THE VOIDS AT LEAST ONE SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF DYESTUFFS, THEIR INTERMEDIATES, LIGHT-STABILIZERS, HEATSTABILIZERS, SURFACTANTS, SOFTENERS, FLAME RESISTORS, ANTISTATIC AGENTS, MORDANTING AGENTS, POLYMERIZABLE COMPOUNDS, SOLVENTS AND WATER, WHICH COMPRISES ABSORGING THE SAID SUBSTANCE INTO THE SAID FIBER.