A molding composition comprising a graft copolymer B, built up from: 15 to 45 wt.-%, preferably 20 to 40 wt.-%, based on graft copolymer B, of a non-cross-linked graft substrate polymer B1 having a glass transition temperature T G below 0°C (determined by DSC based on DIN EN ISO 11357-2:2014-07 (heating rate: 5 K/min)) consisting of polymerized units derived from monomers B11, B12 and optionally B13: from 95 to 99.5 wt.-%, based on the total weight of B11, B12 and B13, of at least one C 1 -C 10 -alkyl acrylate; from 0.5 to 5 wt.-%, based on the total weight of B11, B12 and B13, of at least one bifunctional, crosslinking monomer which contains two copolymerizable double bonds which are not conjugated in 1,3 positions; and from 0 to 4.5 wt.-%, based on the total weight of B11, B12 and B13, of at least one other copolymerizable, monoethylenically unsaturated monomer; and 55 to 85 wt.-%, preferably 60 to 80 wt.-%, based on graft copolymer B, of at least one polymer B2 having a glass transition temperature T G above 50°C (determined by DSC based on DIN EN ISO 11357-2-2014-07 (heating rate: 5 K/min)) grafted from the graft substrate polymer, consisting of polymerized units derived from monomers B21 and optional comonomers B22: from 65 to 100 wt.-% of at least one vinylaromatic monomer; and from 0 to 35 wt.-% of at least one other monofunctional comonomer; • where components B1 and B2 give 100 wt.-% in total, and wherein the graft substrate polymer B1 has a gel content (non-soluble fraction in toluene) below 5 wt.-%, preferably below 3 wt.-%, based on the total amount of B1; the second double bond of the bifunctional, crosslinking monomer B12 is the active site from which polymerized units derived from monomer B21 and optionally comonomer B22 are grafted, • comonomer B22 is maleic anhydride or acrylonitrile, and monomer is styrene and/or α-methyl styrene; and optionally additives and/or auxiliaries C. 15 to 45 wt.-%, preferably 20 to 40 wt.-%, based on graft copolymer B, of a non-cross-linked graft substrate polymer B1 having a glass transition temperature T G below 0°C (determined by DSC based on DIN EN ISO 11357-2:2014-07 (heating rate: 5 K/min)) consisting of polymerized units derived from monomers B11, B12 and optionally B13: from 95 to 99.5 wt.-%, based on the total weight of B11, B12 and B13, of at least one C 1 -C 10 -alkyl acrylate; from 0.5 to 5 wt.-%, based on the total weight of B11, B12 and B13, of at least one bifunctional, crosslinking monomer which contains two copolymerizable double bonds which are not conjugated in 1,3 positions; and from 0 to 4.5 wt.-%, based on the total weight of B11, B12 and B13, of at least one other copolymerizable, monoethylenically unsaturated monomer; and from 95 to 99.5 wt.-%, based on the total weight of B11, B12 and B13, of at least one C 1 -C 10 -alkyl acrylate; from 0.5 to 5 wt.-%, based on the total weight of B11, B12 and B13, of at least one bifunctional, crosslinking monomer which contains two copolymerizable double bonds which are not conjugated in 1,3 positions; and from 0 to 4.5 wt.-%, based on the total weight of B11, B12 and B13, of at least one other copolymerizable, monoethylenically unsaturated monomer; and 55 to 85 wt.-%, preferably 60 to 80 wt.-%, based on graft copolymer B, of at least one polymer B2 having a glass transition temperature T G above 50°C (determined by DSC based on DIN EN ISO 11357-2-2014-07 (heating rate: 5 K/min)) grafted from the graft substrate polymer, consisting of polymerized units derived from monomers B21 and optional comonomers B22: from 65 to 100 wt.-% of at least one vinylaromatic monomer; and from 0 to 35 wt.-% of at least one other monofunctional comonomer; from 65 to 100 wt.-% of at least one vinylaromatic monomer; and from 0 to 35 wt.-% of at least one other monofunctional comonomer; • where components B1 and B2 give 100 wt.-% in total, and wherein the graft substrate polymer B1 has a gel content (non-soluble fraction in toluene) below 5 wt.-%, preferably below 3 wt.-%, based on the total amount of B1; the second double bond of the bifunctional, crosslinking monomer B12 is the active site from which polymerized units derived from monomer B21 and optionally comonomer B22 are grafted, • comonomer B22 is maleic anhydride or acrylonitrile, and monomer is styrene and/or α-methyl styrene; and optionally additives and/or auxiliaries C. monomer is styrene and/or α-methyl styrene; and optionally additives and/or auxiliaries C.