Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Treating polymer containing material or treating a solid...
Patent
1979-01-08
1983-01-04
Henderson, C. A.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Treating polymer containing material or treating a solid...
422131, 5263442, C08F 616
Patent
active
043673317
ABSTRACT:
In the process for reducing the residual vinyl chloride monomer in an aqueous polyvinylchloride dispersion comprising the steps of depressurizing an aqueous polyvinylchloride dispersion containing emulsifiers and/or protective colloids as obtained from pressure polymerization in a polymerization zone, subjecting the same to a vacuum with heating, passing the gasses and foam of liquid constituents resulting from said depressurizing step and said vacuum treating step to a confined space wherein said gasses are separated from liquid constituents, and recovering an aqueous polyvinylchloride dispersion having a reduced residual vinyl chloride monomer content, the improvement consisting in passing said gasses and foam of liquid constituents to a confined space having a volume of not more than 331/3% of the volume of said polyvinylchloride dispersion and returning said foam of liquid constituents to said polyvinylchloride dispersion in said polymerization zone through an elongated zone of small cross-section below said confined space and at such a rate that said confined space is never completely filled with said foam of liquid constituents. According to the invention, the amount of liquid or foam accumulating in the confined space is pumped back into the degassing (polymerization) autoclave by means of a pump arranged underneath the confined space. The advantages consist in a better utilization of the separating capacity, a better and more uniform degassing of the product, and shorter degassing cycles.
REFERENCES:
patent: 3678021 (1972-07-01), Chatelain
patent: 4015064 (1977-03-01), Feldman
patent: 4029619 (1977-06-01), Tajima
patent: 4031056 (1977-06-01), Patel
patent: 4092471 (1978-05-01), Arai
Derwent Abst., Shinetsu, J51047--080, Apr., 1976.
Derwent Abst., Shinetsu, J5113049, Nov., 1976.
Derwent Abst., Mitsubishi, J52083408, Jul., 1977.
Hager Claus
Wiedholz Rudolf
Henderson C. A.
Wacker-Chemie GmbH
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