Abstract: A process for continuous production of high molecular polybutyleneterephthalate by direct esterification of terephthalic acid and 1,4 butanediol in the presence of tin- or titanium-containing catalysts at preferred temperatures of 235.degree. to 250.degree. C., and preferred pressures of 0.3 to 0.6 bar during the first stage--with minimal formation of tetrahydrofurane--followed by precondensation and polycondensation at reduced pressure.

Abstract: An improved process and apparatus for the spin-drawing of high-tenacity, technical-grade yarns is disclosed. The process and apparatus are particularly suitable for use with polyamide and polyester. High quality yarns having a low break elongation are obtained by maintaining the feed roll system at a constant temperature T.sub.E =(T.sub.G -20.degree. C.) to (T.sub.G +65.degree. C.), wherein T.sub.G is the temperature of the glass transition point. Filaments are passed over a roll system disposed between the feed roll system and the draw roll system and driven at a peripheral speed between that of the feed roll and draw roll systems. The filaments are passed over the roll system a maximum of three turns.