filaments a large advantage of the method in accordance with the present invention lies in that crystallization and drying of the tacky copolyester which is difficult in actuality can be omitted dulled pet granules of the textile type m760 of ems chemie ag constituted the base polymer this textile standard polyethylene terephthalate has a relative viscosity of 1 60 measured 1 in m cresol at 20 u00b0 c and contains 0 4 weight of tio 2 titanium dioxide as the dulling pigment the granules were distributed on the two dryers respectively of melt extruders of a conventional bi component fiber pilot spinning machine u03b5 caprolactone obtained from solvay interox ltd was metered into the granule inlet connector at the flange between the pipe from the dryer to the extruder of the one extruder by means of a liquid metering pump after the u03b5 caprolactone concentration in respect to crimping properties and amount used had been optimized in prior tests a metered amount of 8 mol corresponds to 4 9 weight in relation to the co pet after modification i e to the amount of throughput of the corresponding component at the spinneret was set in the main run the modified and the unmodified polyester partial streams were supplied at a ratio of 1 1 to the bi component spinning nozzle manifold by means of spinning pumps wherein the residence time of the melt during modification was approximately 15 minutes the same relative viscosity.