Abstract: The present invention relates to an expandable styrene polymer which comprises athermanous particles and has been coated with a hydrophobicizing agent, which comprises from 10 to 90% by weight of at least one triester of at least one fatty acid with a polyhydric alcohol, as component A, from 5 to 70% by weight of at least one monoester of a fatty acid with a polyhydric alcohol, as component B, from 5 to 80% by weight of at least one metal salt of a fatty acid, as component C, from 5 to 50% by weight of at least one silicate, as component D, and from 0 to 30% by weight of at least one antistatic agent, as component E, and the entirety of components A to E of the hydrophobicizing agent amounts to 100% by weight, to a process for preparation of expandable styrene polymer, via coating of an expandable styrene polymer, which comprises athermanous particles, with a hydrophobicizing agent, to a foam produced from this expandable styrene polymer, and also to the use of a hydrophobicizing agent for coating of expandab