Process for producing a polyamide based on a dicarboxylic acid and a diamine
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United States of America Patent
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Feb 13, 2001
Grant Date -
N/A
app pub date -
Oct 7, 1997
filing date -
Apr 15, 1995
priority date (Note) -
Expired
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Abstract
A polymer based on a dicarboxylic acid and a diamine is prepared by polycondensation in an extruder, by (a) heating a mixture of a dicarboxylic acid having from 4 to 12 carbon atoms and a diamine having from 4 to 12 carbon atoms, which mixture is solid at room temperature and has a residual moisture content of less than 5% by weight, to a temperature in the range from 150 to 400.degree. C. under autogenous pressure in a contrarotating twin-screw extruder to give a product A, (b) feeding the product A to a corotating twin-screw extruder, with the product A being exposed to a temperature in the range from 150 to 400.degree. C. and residual water present and also water from the polycondensation being removed through the degassing openings, to give a product B, with the proviso that the corotating twin-screw extruder has at least two segments having different pressures.
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