PROCESS FOR PRODUCING A FLAME-RESISTANT EPOXY RESIN MOLDING MATERIAL.

摘要

In a process for the production of a flame-resistant, pourable, latently reactive, phenolically curable epoxy resin molding material for the encapsulating of electronic components, a latently reactive prepolymer epoxy resin mixture in powder form which is free of isocyanate groups is produced at reaction temperatures up to 200° C. from a thermally polymerizable, filler-containing reaction resin mixture of polyepoxy resin consisting of a mixture of bi-functional and multi-functional epoxy resins and polyisocyanate resin having a molar ratio of the epoxy groups to the isocyanate groups of >1:1 with a substituted imidazole as reaction accelerator in a concentration of 0.5 to 2.5% by weight, relative to polyepoxy resin, and the prepolymer epoxy resin mixture is mixed with a powdered filler-containing phenolic resin mixture in a molar ratio of the epoxy groups to the phenolic hydroxyl groups of 1:0.4 to 1:1.1.