To provide a composition for forming a rapid demolding type thermosetting polyurethane elastomer having performance of tensile strength, elongation and the like and reduced hardness creep.

There is provided the composition for forming the rapid demolding type urethane elastomer, wherein a mixing ratio α (hydroxyl group (mol)/NCO group (mol)) of an isocyanate group-containing urethane prepolymer (A) and a hydroxyl group-containing curing agent (B) is 0.5 to 0.8, a catalyst (C) includes at least three of a titanium trialcohol aminate catalyst (C1) obtained by reacting a trialcoholamine and a titanium tetraalkoxide, a quaternary ammonium based catalyst (C2) and an aminoalcohol based catalyst (C3), and each content of the catalyst in the whole forming composition is (C1):50 to 500 ppm, (C2):20 to 100 ppm and (C3):50 to 600 ppm.

COPYRIGHT: (C)2010,JPO&INPIT