| 摘要 |
Polyesters made from aromatic dicarboxylic and possibly aliphatic dicarboxylic acids with satd. aliphatic, alicyclic or aromatic diols, pref. of 96 mol.% terephthalic acid and 96 mol.% ethylene glycol, butane-1,4-diol or 4-bis-(hydroxymethyl)-cyclohexane, esp. polyethyleneterephthalate, formed into round rectangular or polygonal rods, thich walled tubes or other large profile with a shrink hole free surface and a homogeneous crystallite structure. The polyester compsns., which can contain the usual additives, are first pressed through a heated intermediate calibre, which is insulated thermally from the tool head of the extruder, before it is passed through an unheated or cooled calibrating tube. The calibre is kept at a temp. between the freezing pt. of the polyester and a temp. 110 degrees C, pref. 30 - 70 degrees C, above it. |
