Patent ID: 6187898
Filing Date: 2001-02-13
Classification: C08G

Abstract:
Method for performing polycondensation reactions to form a polycondensation product, wherein, in a first reaction step, a monomeric starting material is produced by an exothermic reaction and the temperature of the monomeric starting material is controlled via cooling before said monomeric starting material is used in a second reaction step in which the polycondensation of the monomeric starting material is performed with external supply of heat in a reactor combination which has at least two stages and is composed of a pre-reactor and a high-viscosity reactor, where low-molecular-weight elimination products produced are removed by evaporation, further wherein reaction product becomes concentrated in the pre-reactor to give a high-viscosity preliminary product and the preliminary product reacts to completion in the high-viscosity reactor with supply of thermal and mechanical energy and with a residence time of from 20 s to 60 min in the high-viscosity reactor to give the polycondensation product.