Process for preparing rubber reinforced styrenic resins

A process for the continuous production of rubber reinforced styrenic resins of the ABSA-type which are composites of styrenic compound-acrylonitrile copolymers and rubbery polymers of acrylate esters crosslinked by a diolefinic compound, said process comprising the steps of:

• (a) adding a monomer material selected from the group consisting of alkyl ester of acrylic acid, alkyl ester of methacrylic acid and mixtures thereof together with a part of the diolefinic compound to a first solution of a copolymeric matrix of a styrenic compound and acrylonitrile in an inert solvent, whereby there is formed a second solution of said monomer material and said matrix in the inert solvent,
• (b) charging continuously said second solution into a first polymerization reactor and subjecting said second solution to mass polymerization conditions to polymerize a part of said monomer material,
• (c) withdrawing continuously a prepolymer mixture from said first reactor,
• (d) charging continuously said mixture into a second polymerization reactor and subjecting said mixture to a further mass polymerization in the presence of the rest of the diolefinic compound whereby there is formed in situ a crosslinked rubbery material that is dispersed into said copolymer matrix,
• (e) withdrawing continuously a reaction mixture from said second reactor and subjecting said mixture to a heat treatment to remove the solvent and the residual monomers, and
• (f) recovering the ABSA resin.