Thermally conductive polymer (TCP) resin composition comprising components (X) and (Y): 90 to 99.9% by weight of component (X) which is a composition comprising components (I) and (II): 60 to 85% by volume of at least one matrix polymer (I) as component (I) comprising styrenic polymers (I') selected from the group consisting of: ABS (acrylonitrile-butadiene-styrene) resins, ASA (acrylonitrile-styrene-acrylate) resins, and elastomeric block copolymers of the structure S − B / S n − S , where S is a vinylaromatic block forming a hard phase, (B/S) is a random copolymer block of vinylaromatic monomer and of a conjugated diene forming a soft phase, and n are natural numbers from 1 to 10, wherein the elastomeric block copolymer has a monomer composition comprising from 25 to 60% by weight (based on the elastomeric block copolymer) of diene and from 75 to 40% by weight (based on the elastomeric block copolymer) of vinylaromatic compound, the glass transition temperature Tg of block S is above 25°C and that of block (B/S) is below 25°C, and the proportion of the hard phase in the elastomeric block copolymer is from 5 to 40% by weight and the relative amount of 1,2 linkages of the polydiene, based on the sum of 1,2- and 1,4-cis/trans-linkages, is less than 15%; 15 to 40% by volume of at least one thermally conductive filler material (II) as component (II) having a weight median particle diameter (D 50 ) of from 1 to 200 μm, which consists of at least one ceramic material and/or graphite; wherein the sum of components (I) and (II) totals 100% by volume; 0.1 to 10% by weight of at least one chemical foaming agent as component (Y); wherein the sum of components (X) and (Y) totals 100% by weight; and the thermal conductivity κ is more than 0.4 W/m ·K. 60 to 85% by volume of at least one matrix polymer (I) as component (I) comprising styrenic polymers (I') selected from the group consisting of: ABS (acrylonitrile-butadiene-styrene) resins, ASA (acrylonitrile-styrene-acrylate) resins, and elastomeric block copolymers of the structure S − B / S n − S , where S is a vinylaromatic block forming a hard phase, (B/S) is a random copolymer block of vinylaromatic monomer and of a conjugated diene forming a soft phase, and n are natural numbers from 1 to 10, wherein the elastomeric block copolymer has a monomer composition comprising from 25 to 60% by weight (based on the elastomeric block copolymer) of diene and from 75 to 40% by weight (based on the elastomeric block copolymer) of vinylaromatic compound, the glass transition temperature Tg of block S is above 25°C and that of block (B/S) is below 25°C, and the proportion of the hard phase in the elastomeric block copolymer is from 5 to 40% by weight and the relative amount of 1,2 linkages of the polydiene, based on the sum of 1,2- and 1,4-cis/trans-linkages, is less than 15%; 15 to 40% by volume of at least one thermally conductive filler material (II) as component (II) having a weight median particle diameter (D 50 ) of from 1 to 200 μm, which consists of at least one ceramic material and/or graphite; wherein the sum of components (I) and (II) totals 100% by volume; 0.1 to 10% by weight of at least one chemical foaming agent as component (Y); <EOS>