Photocurable resin composition, method of producing photo-cured shaped object, vacuum casting mold, vacuum casting method and novel urethane acrylate

A photocurable resin composition comprising:

• (A) at least one urethane acrylate selected from the group consisting of (a) a first urethane acrylate represented by the following formula (1):
• ##STR11## wherein R.sup.1 is a hydrogen atom or a methyl group, A.sup.1 is a divalent or trivalent substituted or unsubstituted hydrocarbon group, a is 1 or 2, b is an integer of 3 to 6, c is an integer of 3 to 14, and d is 2 or 3, provided that at least one R.sup.1 is a methyl group when a is 2,
• (b) a second urethane acrylate represented by the following formula (2):
• ##STR12## wherein R.sup.2 and R.sup.3 are independently a hydrogen atom or a methyl group, A.sup.2 is a divalent or trivalent substituted or unsubstituted hydrocarbon group, e is 1 or 2, f is an integer of 4 to 20, and g is 2 or 3, provided that at least one R.sup.2 is a methyl group when e is 2,
• and (c) a third urethane acrylate represented by the following formula (3):
• ##STR13## wherein R.sup.4 and R.sup.5 are each independently a hydrogen atom or a methyl group, A.sup.3 is a divalent or trivalent substituted or unsubstituted hydrocarbon group, h is an integer of 4 to 20, and j is 2 or 3,
• (B) a radical polymerizable compound different from the above urethane acrylate (A), and
• (C) a photopolymerization initiator, the weight ratio of the urethane acrylate (A) to the radical polymerizable compound (B) being 65/35 to 25/75.