Process for preparing rubber reinforced styrenic resins

A process for the continuous production of ABS-type resins which are copolymers of a styrenic compound, acrylonitrile and conjugated diolefinic hydrocarbon compound, which comprises the steps of;

• (a) charging continuously a diolefinic compound and a solution of a copolymeric matrix of styrenic compound and acrylonitrile in an inert saturated hydrocarbon solvent having a boiling point ranging between 120.degree. and 175.degree. C., into a polymerization zone comprising at least a first and second reactor,
• (b) subjecting the mixture thus formed to mass polymerization in said first reactor at a temperature less than about 100.degree. C.,
• (c) thereafter continuously changing subjecting said mixture to mass polymerization in said second reactor at a temperature ranging from about 100.degree. to about 140.degree. C. in the presence of from about 0.02 to about 2.5 weight percent of free radical generating catalyst, based on the total weight of copolymeric matrix and diolefinic compound, whereby there is formed in situ during said mass polymerization in said first and second reactors a rubbery material dispersed in said copolymer matrix,
• (d) withdrawing continuously the reaction mixture from said polymerization zone and subjecting it to a heat treatment to remove the residual diolefinic compound and the solvent, and
• (e) recovering the ABS resin.