Process for the preparation of a liquid polyurethane prepolymer, and the conversion thereof into an open-pore polymer concrete

摘要

A liquid polyurethane prepolymer is prepared by reacting a polyol mixture comprising from 70 to 95 parts by weight of a linear epsilon -polycaprolactone having a molecular weight of between 500 and 1000 and from 5 to 30 parts by weight of a linear polyethylene glycol having a molecular weight of between 300 and 3000 with from 1.8 to 1.95 equivalents of tolylene diisocyanate, and diluting the product with from 0.3 to 0.7 equivalent, based on the polyol mixture, of a liquid, crude diphenylmethane diisocyanate. The product can be mixed with a mineral mixture and left to set in the presence of moisture to give an open-pore polymer concrete.