Taking Lithography to the Third Dimension

Abstract

Stereolithography is a new technology which allows the rapid building of plastic models directly from CAD data. The photopolymers needed for this process are developed at Ciba's research center in Marly by a project team from the Polymers Division and the corporate Materials Research. The stereolithography process is described as well as the requirements for the photosensitive monomer formulations. Two types of stereolithography resins have been developed so far: acrylate mixtures which polymerize by a radical mechanism and epoxy-based formulations which are cured cationically. The acrylate resins polymerize very rapidly and several formulations with different mechanical properties are available. Cationic resins are a development of the past two years. They are less photosensitive than the acrylates, but have other advantages, such as low viscosity, high green strength and very high dimensional accuracy. With these resins, parts can be built which can be used directly as patterns for the investment casting process.