Sinterable semi-crystalline powder and near-fully dense article formed therewith

摘要

A laser-sinterable powder product has been prepared having unique properties which allow the powder to be sintered in a selective laser sintering (SLS) machine to form a sintered part which is near-fully dense. For most purposes, the sintered part is indistinguishable from another part having the same dimensions made by isotropically molding the powder. In addition to being freely flowable at a temperature near its softening temperature, the powder has a two-tier distribution in which substantially no primary particles has an average diameter greater than 180 mu m, provided further that the number average ratio of particles smaller than 53 mu m is greater than 80%, the remaining larger particles being in the size range from 53 mu m to 180 mu m. When the powder is a semicrystalline synthetic resin having a number average molecular weight in the range from about 30,000 to 500,000; a molecular weight distribution Mw/Mn in the range from 1 to 5; and, provides a window of sinterability in the temperature range from near the powder's softening temperature Ts to its caking temperature Tc, it is sintered layer-upon layer to form a near-fully dense part of arbitrary shape.