Process for the manufacture of fibers and filaments of polyethylene terephthalate

Claim 1

A PROCESS FOR MANUFACTURING POLYETHYLENE TEREPHTHALATE FIBROUS STRUCTURES HAVING IMPROVED WEARING PROPERTIES WHICH COMPRISES ADMIXING POLYETHYLENE TEREPHTHALATE HAVING A SPECIFIC VISCOSITY OF ABOUT 0.8 TO ABOUT 0.9 WITH 0.1 TO 5% BY WEIGHT, CALCULATED ON THE WEIGHT OF SAID POLYETHYLENE TEREPHTHALATE, OF A DECOMPOSING AGENT SELECTED FROM THE GROUP CONSISTING OF DIMETHYL TEREPHTHALATE, DIMETHYL ISOPHTHALATE, DIGLYCOL TEREPHTHALATE AND DIGLYCOL ISOPHTHALATE, REACTING SAID MIXTURE TO DECOMPOSE SAID POLYETHYLENE TEREPHTHALATE TO A SPECIFIC VISCOSITY OF ABOUT 0.5 TO ABOUT 0.6, AND SPINNING SAID MIXTURE TO FORM SAID FIBROUS STRUCTURES, SAID SPECIFIC VISCOSITY BEING DETERMINED BY MEASURING THE VISCOSITY OF A 1% SOLUTION OF SAID POLYETHYLENE TEREPHTHALATE IN A MIXTURE OF 60 PARTS PHENOL AND 40 PARTS TETRACHLORETHANE IN A CAPILLARY VISCOSIMETER AT 25*C.