Process for the preparation of polyurethane solutions

摘要

The invention relates to a process for the preparation of polyurethane solutions having a long shelf life which are free from gel particles, in which the molecular weight of the polymer can be controlled precisely. This allows, for a fixed solids content of between 5 and 30%, the viscosity of the solution to be set reproducibly. The process according to the invention allows the concomitant use of polyfunctional hydroxyl compounds in the chain extension phase. It thus advantageously leads to constant viscosity/solids content ratios and to solutions having stable viscosities, these solutions being substantially insensitive to the water content of the solvent and virtually free from gel particles. Polyurethane solutions of this type can be used as the starting material for fibres or as textile coating material. Microporous or dense films can also be produced from these solutions by corresponding technological processes.