PURPOSE: To obtain a low viscosity self-toughening compsn. having good sensitivity to laser beam toughening and useful in rapid prototyping application by using a specified prepolymer mixture, a specified diluent monomer and a specified initiator and imparting a prescribed viscosity. ;CONSTITUTION: The compsn. contains about 50-80 wt.% acrylate functional, prepolymer mixture contg. a 1st prepolymer (e.g. a polyether urethane diacrylate) which is a urethane diacrylate resin having ≥500,000 cPs viscosity at 25°C in 10-40 wt.% of the compsn. and a 2nd diacrylate prepolymer (e.g. polyester urethane diacrylates) having about 500-50,000 cPs viscosity in ≥15 wt.% of the compsn., ≥5 wt.% monoacrylate diluent monomer which is isobornyl acrylate and/or β-carboxyethyl acrylate and an effective amt. of a free radical initiator (e.g. 1-benzoyl cyclohexanol). The compsn. has ≤10,000 cPs viscosity at 25°C.;COPYRIGHT: (C)1994,JPO
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