The invention relates to an unsaturated polyester resin mixture which can be cured by applying external pressure and which encompasses at least the following components: a) an unsaturated polyester resin whose weight-average molar mass is from 500 to 5000 g/mol; b) an ethylenically unsaturated monomer; c) a shrinkage-reducing component; d) an inert filler; and e) a reinforcing fibre; and f) from 0.01 to 1% by weight of a block copolymer, based on the total weight of the unsaturated polyester resin mixture comprising reinforcing fibre, where the block copolymer encompasses at least one A block and encompasses at least one B block, where the A block contains at least one amine-containing, ethylenically unsaturated monomer; and the B block contains at least one alkyl- and/or phenyl-containing, ethylenically unsaturated monomer, and is free from amine-containing, ethylenically unsaturated monomers. The present invention further relates to a process for preparation of the polyester resin mixtures and to the use of the block copolymers f) in unsaturated polyester resin mixtures.