Process for producing vinyl aromatic (co)polymer incorporating post-consumer and/or post-industrial recycled polystyrene

A process for the production of a vinyl aromatic (co) polymer comprising:

• a) mixing
• a fraction (A) comprising one or more monomers selected from the group consisting of styrene, alpha-methyl styrene, acrylonitrile, methyl (meth)acrylate, (meth)acrylic acid and butadiene with
• a fraction (B) comprising recycled vinyl aromatic (co) polymer comprising post-consumer recycled polystyrene (PCR-PS) and/or post-industrial recycled polystyrene (PIR-PS) comprising halogenated flame retardant, wherein the recycled vinyl aromatic (co) polymer of fraction (B) is characterized by a weight average molecular weight comprised between 100,000 and 400.00 g/mol, wherein fraction (B) comprises bromine containing flame retardant and flame-retardant synergists, and wherein the weight ratio of fraction (B) to fraction (A) is comprised between 0.01/1 and 1/1;
• b) subjecting the resulting mixture to a free-radical polymerization, and polymerizing to a monomer conversion of up to 90%, to obtain a polymerized mixture comprising vinyl aromatic (co) polymer;
• c) vacuum devolatizing the polymerized mixture and recovering vinyl aromatic (co) polymer characterized by a weight average molecular weight comprised between 100,000 and 400,000 g/mol;
• wherein one or more bromine derivative capture agents are added in an amount of from 0.01 to 6 parts for 100 parts of (co) polymer, PCR/PIR-PC, oligomers and/or monomers before and/or during and/or after at least one of the steps a) to b) and before the devolatizing step c);
• and
• wherein 100 parts of one or more bromine derivative capture agents comprises at least 50 parts by weight of hydrotalcite of the formula:
• [Mg1-xAlx(OH)2]x+(CO3)x/2·mH2O
• wherein:
• 0<x≤0.5, and m is a positive number.