Fabrication of transparent parts by laser sintering process -Transparentization of laser sintered plastic parts by infiltrating thermosetting epoxy with tuned refractive index-

Abstract

A novel process that can fabricate transparent parts was developed for the purpose of improving mechanical and thermal performances of functional and transparent prototypes which is provided through an additive manufacturing technology. The process starts with plastic laser sintering process, which is widely applied to fabrication of functional prototype or rapid manufacturing, and following infiltration of the sinter, which is opaque after the first process, with thermosetting plastic of which refractive index after cure is tuned to have the same value as that of the sintered powder clearly eliminates opacity from the sinter. Experiments using styrene-methacrylate copolymer as powder material and thermosetting epoxy resin were carried out, and the minimum haze of 20% (at 5mm in thickness) was obtained. In terms of mechanical strength, impact strength (unnotched Izod) reached 3.5kJ/m2 meeting standard of that for transparent grade stereolithography parts. In this paper, requirements both in laser sintering and infiltration, and problems to be solved to improve the mechanical strength are also discussed.