Abstract: A method for removing vinyl chloride monomer rapidly from a large amount of slurry of vinyl chloride resin to give waste water separated from said slurry, exhaust gas used in the drying of separated resin and resin product which are not objectionable from the environmental sanitation or to produce such a treated slurry which can give waste water separated from said slurry, exhaust gas used in the drying of separated resin and resin product which are not objectionable from the environmental sanitation by the repetition of said method. In said method a slurry of vinyl chloride resin is caused to flow down a plate column in which flow of slurry on the trays in each step of plates is treated with steam in a combination of specified plates and specified conditions of treatment.

Abstract: When vinyl chloride resin slurry containing vinyl chloride monomer is contacted with steam in counterflow manner in a column provided with at least one perforated plate having a downcomer to remove the monomer, the lower surface of the plate is washed by hot water injection, whereby clogging of the small holes of the perforated plate is prevented.

Abstract: A method of suspension polymerization, which is effective to prevent the adhesion of scale-form polymer to the inside wall of polymerization vessel, is provided by adding oxalic acid or its salt to the polymerization system consisting of vinyl chloride suspended in aqueous medium.