Method for the production and stabilization of impact-modified polycarbonate compositions using diluted solutions of acidic compounds

Process for preparing an impact-modified polymer compositions comprising

• A) from 10 to 98 parts by weight, based on the sum of components A+B+C+D+E, of at least one polymer selected from the group of the aromatic polycarbonates, aromatic polyester carbonates and aromatic polyesters, as well as mixtures thereof,
• B) from 0.5 to 50.0 parts by weight, based on the sum of components A+B+C+D+E, of at least one pulverulent rubber-modified vinyl (co)polymer,
• C) from 0 to 80 parts by weight, based on the sum of components A+B+C+D+E, of at least one component selected from rubber-modified vinyl (co)polymers in granulate form and rubber-free vinyl (co)polymers,
• D) from 0.002 to 0.200 part by weight, based on the sum of components A+B+C+D+E, of at least one Brönsted acid,
• E) from 0.1 to 40.0 parts by weight, based on the sum of components A+B+C+D+E, of one or more additives, with the exception of acid according to component D that is conventionally added,
• wherein the sum of the parts by weight of components A+B+C+D+E in the composition is 100,
• comprising:
• (i) preparing a solution of the acidic compound according to D with a concentration of from 0.3 to 30 wt. %,
• (ii) physically blending a solution of the acidic compound D from (i) with the total amount or a partial amount of the graft polymer powder according to component B and optionally with the total amount or a partial amount of one or more further pulverulent components of a polycarbonate-ABS composition,
• (iii) melting, mixing and dispersing in one another a mixture from (ii) with further residual components A-E of the composition, which have optionally likewise been premixed, in a compounding unit, wherein solvent that has been added to the composition by the solution of the acidic compound is removed again in a degassing zone of the compounding unit by application of a low pressure, and polymer melt so prepared is subsequently solidified by cooling and then granulated.