PROCESS FOR THE PREPARATION OF VINYLAROMATIC POLYMERS

Continuous mass polymerisation process for the preparation of vinyl aromatic polymers comprising: - continuously feeding at least one vinyl aromatic monomer and at least one radical initiator to a mixing device, obtaining a reaction mixture; - feeding said reaction mixture to a Continuous Stirred Tank Reactor (CSTR), said Continuous Stirred Tank Reactor (CSTR) containing a polymer fraction, in the reaction mixture in liquid phase, between 45% by mass and 60% by mass, preferably between 50% by mass and 58% by mass, with respect to the total mass of said reaction mixture in liquid phase; - feeding the reaction mixture in liquid phase leaving said Continuous Stirred Tank Reactor (CSTR) to at least one Plug Flow Reactor (PFR), said at least one Plug Flow Reactor (PFR) containing a polymer fraction, in the reaction mixture in liquid phase leaving said at least one Plug Flow Reactor (PFR), of at least 65% by mass, preferably between 70% by mass and 80% by mass, with respect to the total mass of said reaction mixture in liquid phase leaving said at least one Plug Flow Reactor (PFR); - recycling, to said mixing device, a fraction of the reaction mixture in liquid phase leaving said at least one Plug Flow Reactor (PFR), said fraction being between 25% by mass and 50% by mass, preferably between 25% by mass and 40% by mass, with respect to the total mass of the reaction mixture in liquid phase leaving said at least one Plug Flow Reactor (PFR); - feeding the remaining fraction of the reaction mixture in liquid phase leaving said at least one Plug Flow Reactor (PFR), to a devolatilisation system; - optionally, feeding the polymer leaving said devolatilisation system to an additive system; - feeding the polymer leaving said devolatilisation system or leaving said additive system, to a granulation system and recovering the polymer. The vinyl aromatic polymers thus obtained can be advantageously used in the production of compact manufactured articles, foams and expandable beads. L'invention concerne un procédé de polymérisation en masse en continu pour la préparation de polymères vinylaromatiques, comprenant : l'introduction en continu d'au moins un monomère vinylaromatique et d'au moins un initiateur de radicaux dans un dispositif de mélange, ce qui permet d'obtenir un mélange réactionnel ; l'introduction dudit mélange réactionnel dans un réacteur à cuve agitée en continu (CSTR), ledit réacteur à cuve agitée en continu (CSTR) contenant une fraction polymère, dans le mél