Compositions for the production of fracture-tough dental parts by means of stereolithography

A polymerizable composition comprising

• (a) at least one radically polymerizable oligomer,
• (b) at least one polyfuncational radically polymerizable monomer and
• (c) at least one initiator for the radical polymerization,
• wherein the radically polymerizable oligomer (a) is an aliphatic urethane (meth)acrylate oligomer of structural formula (I)
• in which
• R1 and R5 each are —C(═O)—NH— or —C(═O)—NH—CH2—,
• R3 and R7 each are —NH—C(═O)— or CH2—NH—C(═O)—,
• R2, R4, R6 and R8 each are H or CH3,
• R9 and R10 each are H or CH3,
• wherein,
• if R1 is —C(═O)—NH—, then R2 is H, R3 is —CH2—NH—C(═O)— and R4 is CH3 and,
• if R1 is —C(═O)—NH—CH2—, then R2 is CH3, R3 is —NH—C(═O)— and R4 is H, and
• M is a mid-chain segment which is obtainable by polymerization of ε-caprolactone and 2-(2-hydroxy-ethoxy)ethanol or by polymerization of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane, ε-caprolactone and 2-(2-hydroxyethoxy)ethanol.