Phosphosilicone/silicate copolymers and their use as corrosion inhibitors and silicate stabilizers in antifreezes

A radiator antifreeze based on glycol, containing from 500 to 5000 ppm, based on the said antifreeze, of an organosilane/silicate copolymer which is obtained by reacting an organic phosphosilicon compound of the formula I ##STR9## where Y is a divalent aliphatic or cycloaliphatic radical of 1 to 10 carbon atoms or a phenylenealkylene group of 7 to 10 carbon atoms and n can be 1 or 2, and when n is 1, X is an OR.sup.3 group in which R.sup.3 is a straight-chain, branched or cyclic alkyl group of 1 to 13 carbon atoms which may be interrupted by oxygen atoms or is acyl of not more than 9 carbon atoms, and R.sup.1 and R.sup.2 are identical or different and are each a straight-chain, branched or cyclic alkyl group of 1 to 13 carbon atoms which may be interrupted by oxygen atoms, or is an aryl or aralkyl group of not more than 20 carbon atoms, and when n is 2, X is oxygen and R.sup.1 is an alkali metal and R.sup.2 has the above meanings, with a silicate of the formula ##STR10## where M is an alkali metal and q is from 0.4 to 4, in a weight ratio of from 1:1 to 1:10.

Method of inhibiting corrosion of aluminum by an aqueous cooling medium containing a radiator antifreeze based on glycol during the cooling of an internal combustion engine, wherein from 500 to 5000 ppm, based on the said antifreeze, of an organosilane/silicate copolymer which is obtained by reacting an organic phosphosilicon compound of the formula I ##STR11## where Y is a divalent aliphatic or cycloaliphatic radical of 1 to 10 carbon atoms or a phenylenealkylene group of 7 to 10 carbon atoms and n can be 1 or 2, and when n is 1, X is an OR.sup.3 group in which R.sup.3 is a straight-chain, branched or cyclic alkyl group of 1 to 13 carbon atoms which may be interrupted by oxygen atoms or is acyl of not more than 9 carbon atoms, and R.sup.1 and R.sup.2 are identical or different and are each a straight-chain, branched or cyclic alkyl group of 1 to 13 carbon atoms which may be interrupted by oxygen atoms, or is an aryl or aralkyl group of not more than 20 carbon atoms, and when n is 2, X is oxygen and R.sup.1 is an alkali metal and R.sup.2 has the above meanings, with a silicate of the formula II ##STR12## where M is an alkali metal and q is from 0.4 to 4, in a weight ratio of from 1:1 to 1:10, is added to the aqueous cooling medium.