| abstract |
The invention relates to the use of thermoplastic polyester moulding compounds, containing A) 80 to 100 wt. % of a polyalkylene arylate, especially polybutyleneterephthalate, with a half-width of crystallisation heat releases of </=5 DEG C and B) 0 to 20 wt. % of other additives, the weight percentages of constituents A) and B) adding up to 100 %, for producing moulded bodies by blow-moulding, profile extrusion and/or pipe extrusion. A preferred use for the inventive moulding compounds is the production of light guide sheathing. The invention also relates to a 3-stage method for producing the polyesters as follows: a) esterification or re-esterification of an aromatic dicarboxylic acid or its derivative and a glycol; b) precondensation; and c) polycondensation to a viscosity number of at least 158 ml/g. The reaction is carried out in at least 2 temperature zones in stages a) and b). |