Abstract: The invention relates to a process in which, as essential components, liquid epoxy resins, carboxylic anhydrides, zinc fluoroborate complex compounds, water, tetrahydropyrane and compounds (X) which contain OH groups, COOH groups or both groups together, are reacted. Selective choice of the special quantity ratios results in reaction mixtures which, at low temperature (e.g. at 100.degree. C.), require only short moulding times and have a sufficiently long pot life. As the reaction is only slightly exothermic, the process can be used very advantageously for encapsulating electronic components.

Abstract: The invention relates to a process for the preparation of crosslinked polymers by reacting liquid epoxide compounds and polyisocyanates and, if desired, polyhydroxy compounds. The curing catalysts used are complex compounds of BF.sub.3 with ethers or phosphonium compounds or H.sub.2 O. If desired, a compound of one of the metals Sn, Zn or Fe which is soluble in the reaction mixture is also added.In most cases it is possible to dispense completely with the external supply of heat when carrying out the process according to the invention, since the reaction is sufficiently exothermic. The technical advance lies in the fact that it is largely possible to dispense with heating and insulating equipment when carrying out the reaction industrially. Despite this, astonishingly high glass transition temperatures are obtained.