Segmented unsaturated polyester resins

The resins are prepared by first obtaining an unsaturated oligoester by the known reaction of acidic components in the form of diacids or diacid anhydrides, both unsaturated and saturated, with aliphatic or aromatic dialcohols or etherdiols, then condensing the unsaturated oligoester with a reactive oligomer in the form of an oligoether, oligosiloxane, saturated oligoester or oligoamide having terminal hydroxyl, carboxyl or amine groups and then adding a cross-linking monomer, preferably styrene. The crosslinked product comprises a segmented copolymer consisting of cross-linked blocks and linear (non-crosslinked blocks).