Flame-retardant thermoplastic molding compounds

The invention concerns thermoplastic moulding materials containing A) 5 to 97 % by weight thermoplastic polymer selected from the group of the polyamides, polyesters, polyphenylene ethers, aromatic vinyl polymers or their mixtures, B) 1 to 30 % by weight alkyl phosphonic acid compound of the formula (I) whereby R is an alkyl residue with 1 to 4 C atoms and x 0 or 1, C) 1 to 30 % by weight synergist for B) selected from the group of inorganic calcium or magnesium compounds or their mixtures, D) 1 to 50 % by weight fibrous filling material, and E) 0 to 40 % by weight further additives and auxiliary products, whereby the weight percentages of the components A) through E) yield 100 % respectively.