ES342841A1 - Process for the heated drawing and fixation of filaments - Google Patents

Abstract

In a process for the heat treatment of synthetic filaments and threads so that they may be stretched, set, and optionally shrunk in one working step, the filaments are passed over first and second heated rollers rotating at different peripheral speeds, the filament or thread is passed through a heating zone between the first and second heated rollers in such a way that in its passage between the two rollers the filament or thread is always at least at the temperature at which it left the first roller, but below the setting temperature of the filament or thread, the temperature of the second roller being sufficient to heat the filament to its setting temperature. Preferably the filament or thread passes through the heating zone without contact with any part of the apparatus, and the heat treatment on the two rollers and in the interposed heating zone is advantageously effected in the absence of air, an air-suction extractor being provided on the housing if desired. Either or each of the first and second heating rollers may be a stepped roller having steps which can be heated to different temperatures. Preferably the second heating roller is a stepped roller having a first step of larger diameter than the second step, so that a reduction in filament speed occurs as the filament passes from the first step to the second step, thus enabling the filament to shrink. The temperature of the two steps of the roller may also differ. Any convenient heating arrangement may be used in the heating zone, infra-red radiation, electrical induction or resistance heating being mentioned. Preferably the ends of the heating arrangement lie as close as possible to the heating rollers. In operation a filament 30 is drawn off by a creel 2, 4 from a supply position (not shown). The filament passes into the housing (not shown) through a slot (not shown) and travels with slight pre-tension over a heated roller 7 and associated guide roller 8. The filament is heated to its drafting temperature whilst on roller 7 and then passes without any contact over a heating arrangement 14 to a heated roller 9 which is maintained at the setting temperature for the filament. If shrinkage of the filament occurs during setting the filament, after travelling over the step 12 and guide roller 10 is guided on to a step 13 of the heated roller which runs at the same rotational speed as step 12 but is of smaller diameter thus enabling the filament to shrink. The filament loops several times around the step 13 of the heated roller and around guide roller 11 before emerging from the protecting and insulating housing (not shown) through a slot at the bottom (not shown).