Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2006-09-26
2006-09-26
Boykin, Terressa (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C422S131000, C528S271000, C528S480000
Reexamination Certificate
active
07112646
ABSTRACT:
The present invention relates to a process and a device for the continuous manufacture of a polymer of an aromatic alkylene monomer e.g. styrene comprising a bulk polymerisation of the monomer and a devolatilization of the resulting polymer in at least two successive steps so as to separate the polymer from the unreacted monomer and the oligomers formed during the polymerisation. The process comprises conveying a first gas stream resulting from the first step of the devolatilization into a first zone Z1for direct condensation and fractionation, removing a gas stream G1comprising essentially the monomer from the top of Z1, and removing a liquid stream L1rich in oligomers from the bottom of Z1, a portion of L1being taken, cooled and then returned into Z1. It also comprises conveying a second gas stream resulting from the second step of the devolatilization into a second zone Z2for direct condensation and fractionation, this zone being also fed with the other portion of L1, removing a gas stream G2comprising the monomer from the top of Z2, and removing a liquid stream L3comprising essentially the oligomers from the bottom of Z2. The process and the device are particularly suitable for continuously manufacturing a styrene polymer, a styrene copolymer having a high impact strength modified by grafting onto a rubber, an expandable polystyrene or an expanded polystyrene. The invention is useful for improving the separation of the unreacted monomer from the oligomers and the quality of the polymer when the unreacted monomer thus separated is recycled e.g. to the polymerisation.
REFERENCES:
patent: 3536787 (1970-10-01), Street
patent: 3886049 (1975-05-01), Bir et al.
patent: 0 499 599 (1992-08-01), None
patent: WO 96/27634 (1996-09-01), None
Boykin Terressa
BP Chemicals Limited
Finnegan, Henderson Farabow, Garrett and Dunner L.L.P.
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