Preparation of vinyl chloride polymers

Abstract

Abstract METHOD AND APPARATUS FOR THE POLYMERIZATION IN MASS OF VINYL CHLORIDE AND MIXTURES THEREOF WITH VINYL ACETATE, WHEREIN THE MONOMER IS PREPOLYMERIZED IN A FIRST AUTOCLAVE, UNDER CONTROLLED TEMPERATURE AND PRESSURE AND AT A RELATIVELY RAPID RATE FOR A RELATIVELY SHORT TIME, UNTIL POLYMERIZATION HAS BEEN COMPLETED TO ABOUT 7 TO 15%. THE FLOWABLE MIXTURE OF MONOMER AND POLYMER IS THEN RAPIDLY TRANSFERRED TO A SECOND AUTOCLAVE WHEREIN POLYMERIZATION TO THE DESIRED DEGREE, SAY 70%, IS COMPLETED AT A SLOWER RATE AND FOR A MORE EXTENDED TIME. THE SECOND AUTOCLAVE IS OF A TYPE HAVING A TANK WITH VERTICAL AXIS OF SYMMETRY AND A HELICAL MIXING BLADE ROTATING ON THE AXIS OF SYMMETRY AND CLOSELY ADJACENT THE WALLS OF THE TANK, BUT RADIALLY SPACED FROM ITS AXIS OF ROTATION. THEREBY A TUBULAR COLUMN OF MIXTURE IS CONTINUOUSLY MOVED VERTICALLY IN CONTACT WITH THE TEMPERATURE-CONTROLLED WALLS OF THE TANK, AND RETURNS IN A CENTRAL GENERALLY CYLINDRICAL COLUMN ALONG THE AXIS OF ROTATION. PRECISE AND UNIFORM TEMPERATURE CONTROL ARE THUS EFFECTED, AND GRANULOMETRY IS IMPROVED.

Inventors

• 👤 Jean Claude Thomas

Bibliographic Details