Antifreeze concentrate with corrosion protection and aqueous coolant composition produced therefrom

摘要

Antifreeze concentrate with corrosion protection which is suitable for coolants and heat transfer fluids and comprises freezing point-lowering liquids and also particular sulfur-comprising organic compounds, inorganic molybdate salts, inorganic phosphate salts and aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acids as corrosion inhibitors. Aqueous coolant compositions which are suitable for cooling an internal combustion engine whose cooling apparatus has been made of aluminum using a soldering process using a fluoroaluminate flux can be obtained therefrom.

主权项

1. An antifreeze concentrate, comprising:
(A) at least one freezing point-lowering liquid selected from the group consisting of a monohydric alcohol, a dihydric alcohol, a trihydric alcohol, a polyhydroxy alcohol, and ethers thereof as a main constituent; (B) at least one sulfur-comprising organic compound selected from the group consisting of (B1) and (B2), and, optionally, a sulfur-comprising organic compound (B3):
(B1) a compound comprising a structural element of the following formula: (B2) a heterocyclic compound having at least one ring sulfur atom, at least one exocyclic sulfur atom and at least one ring nitrogen atom, and(B3) a sulfur-comprising aliphatic carboxylic acid,as a corrosion inhibitor; (C) at least one inorganic molybdate salt as a further corrosion inhibitor; (D) at least one inorganic phosphate salt as a further corrosion inhibitor; (E) at least one aliphatic, cycloaliphatic or aromatic monocarboxylic, dicarboxylic or tricarboxylic acid in the form of an alkali metal, ammonium or substituted ammonium salt thereof having from 3 to 21 carbon atoms in the acid part,
wherein the corrosion inhibitor (B1) or (B2) is at least one 2-thiothiazole of the following formula I: where R1 is a carboxyalkyl radical of the formula —(CmH2m)—COOX, where m is from 1 to 4 and X is hydrogen, an alkali metal cation, an ammonium cation or a substituted ammonium cation, and R2 and R3 are each, independently of one another, hydrogen or a C1-C4-alkyl group, where R2 and R3 together with the two ring carbon atoms of the thiazole ring to which they are attached may also form a five- or six-membered saturated or unsaturated ring.