Coolant stabilizer

Claim 1

A stabilizer for alkali metal silicate inhibited coolant compositions comprising, in combination: (A) an organic phosphonate compound of the general formula ##STR11## wherein X is H, amine, hydroxy, alkyl of 1 to 5 carbons, or aryl; R 1 is hydrogen, hydroxy, alkyl of 1 to 5 carbons, aryl, or a radical of the formula ##STR12## wherein n is an integer from 0 to 8; R 2 is hydrogen, alkyl of 1 to 5 carbons, aryl, or a radical of one of the formulas ##STR13## wherein any of said alkyl or aryl may be independently substituted with hydroxy, amine, halide, or alkoxy of 1 to 3 carbons; and wherein M is hydrogen or a water-soluble cation such as sodium, potassium, ammonium, and the like; or an organic phosphonate compound of the general formula ##STR14## wherein n is an integer from 1 to 6 and M is as defined above; or an organic phosphonate compound of the general formula ##STR15## wherein M is as defined above and R 3 is a radical of one of the formulas ##STR16## wherein M is as defined above; and (B) an organic silicon compound of the general formula ##STR17## wherein R 4 is alkyl of 1 to 8 carbons, R' is a water-solubilizing group, and R" is hydrogen, alkyl of 1 to 3 carbons, or a water-soluble cation such as sodium, potassium, ammonium, and the like, and wherein R 4 may be substituted with hydroxy, amine, halide or alkoxy of 1 to 3 carbons, wherein the proportions of said organic phosphonate compound to said organic silicon compound are selected to provide from 30 to 200 ppm of said organic phosphonate and from 250 to 2,000 ppm of said organic silicon when said stabilizer is added to an aqeuous coolant composition.