respectively suitable amounts of binding agent are between 1 5 and 12 wt preferably 2 0 to 9 wt and with even more preference 2 5 to 6 wt when the binding agent is applied as an aqueous solution or dispersion the fiber should be dried after the application of the binding agent for instance over drum dryers air dryers and the like the overlay finish when used is a low intrinsic viscosity oil which reduces the friction of the treated yarn and of the chopped fiber with guide rollers of the cutting unit and metal parts of the transport system to the extruder respectively preferably the overlay finish is an ester oil used in an amount of 0 05 to 3 wt more preferably from 0 1 to 1 wt examples of suitable oils are 2 ethyl hexyl stearate 2 ethyl hexyl palmitate n butyl laurate n octyl caprylate butyl stearate or mixtures thereof preferred ester oil is a mixture of 2 ethyl hexyl stearate and 2 ethyl hexyl palmitate which is available under the trade name lw u00ae 245 the fibers when treated with the binding agent dried and optionally further provided with a finish are chopped in.