Method for dissolving PPTA in sulfuric acid using a twin screw extruder

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United States of America Patent

PATENT NO 7527841
APP PUB NO 20080085978A1
SERIAL NO

11663980

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Abstract

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Described is a method for dissolving PPTA or copolymers thereof in sulfuric acid using a twin screw extruder having transporting, mixing, and kneading elements with an entering zone, an intermediate zone, a mixing zone, a negative transport zone, a degassing zone, and a pressure build-up zone. The method includes transporting PPTA or copolymer thereof into the entering zone at a transport capacity low enough as to prevent sulfuric acid entering the entering zone; introducing sulfuric acid in the intermediate zone; essentially fully filling the mixing zone to allow sufficient time to mix and dissolve PPTA or copolymer thereof in the sulfuric acid to obtain a PPTA or copolymer-sulfuric acid solution; creating after the mixing zone a negative transport zone to obtain a product lock between the mixing zone and the degassing zone; creating a thin film of the PPTA or copolymer-sulfuric acid solution in the degassing zone to degas the solution; and entering the solution into the output pressure build-up zone to partially fill this zone and to leave the twin screw extruder.

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Patent Owner(s)

Patent OwnerAddress
TEIJIN ARAMID B VVELPERWEG 76 ARNHEM 6824 BM

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Inventor(s)

Inventor Name Address # of filed Patents Total Citations
Koenders, Bernardus Maria Westervoot, NL 8 71

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