Gypsum-based modelling material especially for dentistry

摘要

A mineral modelling material based on alpha calcium sulphate hemihydrate, with a light reflection-free surface and more than 50% reflection in the 800-1800 nm range, for optical measurement and scanning of the model by an IR laser, comprises: (i) 70-95% alpha hemihydrate; 0-20% accompanying components (e.g. beta hemihydrate, anhydrate and calcium oxide); (ii) 0.5-2% water-soluble salts (e.g. potassium sulphate, potassium sodium tartrate and sodium citrate); (iii) 0.5-2% calcium sulphate dihydrate; (iv) 0-30% filler (e.g. calcium carbonate or silicon dioxide); (v) 0.2-3% organic component (e.g. melamine resin); and (vi) 2-10% inorganic pigment with a refractive index of at least 2.5 (e.g. titanium dioxide, chromium (III) oxide or iron (III) oxide).