Abstract: The present invention relates to novel flame-retardant phosphorus-containing epoxy resins with an epoxy value of from 0.05 to 1.0 moll 100 g containing structural units which derive from (A) polyepoxy compounds having at least two epoxy groups per molecule, and (B) organic phosphinic acids. The invention further relates to a process for their preparation, and to their use. Besides their flame retardancy, the novel flame-retardant phosphorus-containing epoxy resins have especially good storage stability.

Abstract: The invention relates to flame-retardant thermoset compositions which comprise, as flame retardant, at least one phosphinic and/or a diphosphinic salt of these.

Abstract: The present invention relates to a process for the preparation of phosphinic acid esters, which comprises a) reacting elemental yellow phosphorus with alkylating agents in the presence of a base to give a mixture which comprises, as principal constituents, the (metal) salts of alkylphosphonous, phosphorous and hypophosphorous acids, b) esterifying the principal constituents of the mixture from a) to give an ester mixture, c) isolating the ester of the alkylphosphonous acid from the ester mixture, d) adding the resultant ester of the alkylphosphonous acid onto an olefin containing a functional group. The invention likewise relates to the use of the phosphinic acid esters prepared by this process, inter alia as flame retardants and precursors for further syntheses.