Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Patent
1996-10-29
1998-07-07
Hampton-Hightower, P.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
528322, 528323, 528324, 528332, 528481, 528495, 528496, 528499, 528502R, C08G 7310, C08G 6908, C08G 6916
Patent
active
057770670
ABSTRACT:
Disclosed are a method for producing a polyamide resin which comprises the steps of extracting with water a polyamide resin obtained by polymerizing caprolactam in the presence of water; condensing the extracted aqueous solution containing unreacted caprolactam and its low polymerized materials; and polymerizing the condensate by adding an additional amount of caprolactam, the improvement wherein
(a) among the low polymerized materials of caprolactam, a cyclic dimer is supplied to a polymerization reactor after subjecting it to ring-opening reaction to give a chain structure material in an amount of 15% by weight or more based on the total amount of the cyclic dimer, or
(a') a condensate obtained by condensing said aqueous solution until reaching a water partial pressure of 10 kg/cm.sup.2 G or more and a temperature of 230.degree. C. or higher is supplied to a polymerization reactor, and then
(b) said additional amount of caprolactam is added to the polymerization reactor,
and the procedures are repeatedly carried out.
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Database WPI, Derwent Publications, AN-79-49798, JP-A-54-064593, May 24, 1979.
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Miyamoto Masaaki
Sato Shin'ichi
Tsuruhara Kenji
Hampton-Hightower P.
Mitsubishi Chemical Corporation
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