| 摘要 |
The present invention relates to a process for preparing by condensation copolymers having polyamide blocks and polyether blocks in which polyamide blocks having dicarboxylic chain ends are mixed with :
a polyether having two OH chain ends (a polyetherdiol), and
a polyol having at least 3 OH functions, optionally in the presence of a catalyst. The polyamide blocks having dicarboxylic chain ends can be prepared by condensation of polyamide precursors in the presence of a chain-limiting dicarboxylic acid. According to an embodiment of the invention the polyamide blocks having dicarboxylic chain ends is prepared simultaneously with the condensation. This process has many advantages. The copolymers have a higher molecular weight, higher mechanical properties (impact, processing, filmification etc), remain linear or only weakly branched. The multifunctionality of the polyol is only used for kinetic aspects. As regards the process, there is a reduction of cycle time, reduced technical requirements on to catalyst and vacuum system and a reduce of degradation which means a better colour stability. The process may be carried out in usual apparatus for polyamide synthesis. The present invention also relates to these copolymers having polyamide blocks and polyether blocks and comprising in its chain the residues of a polyol having at least 3 OH functions. The residues of said polyol are bound to the polyamide blocks through ester links.
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