Flame-proof thermoplastic moulding materials

A thermoplastic molding composition comprising

• A) from 5 to 97% by weight of a thermoplastic polymer selected from the group consisting of polyamides and mixtures of these,
• B) from 1 to 30% by weight of an alkylphosphonic acid compound of the formula I
• where R is alkyl having from 1 to 4 carbon atoms and x is 0 or 1,
• C) from 1 to 30% by weight of a mixture of
• c1) a magnesium calcium carbonate of formula
• MgxCay(CO3)x+y.m H2O,
• where x and y are numbers from 1 to 5 and x/y≧1 and m≧0, and
• c2) a basic magnesium carbonate of formula
• Mgn(CO3)v(OH)2n−2v.w H2O,
• where n is a number from 1 to 6, v is a number greater than 0 and smaller than 6 and n/v>1 and w≧0,
• having a c1):c2) mixing ratio of from 1:1 to 3:1,
• D) from 1 to 50% by weight of a fibrous filler and
• E) from 0 to 40% by weight of other additives and processing aids,
• where the sum of the percentages by weight of components A) to E) is always 100%.