Patent ID: 7029522

Claim:
A rust prevention coating agent comprising a fluorine and zirconium-containing compound and a guanidine compound and/or salt thereof, wherein said guanidine compound and/or salt thereof is a compound, having a weight-average molecular weight of 59 to 1000000, expressed by the following general formula (1) and/or salt thereof; in the formula, Y represents the formula of —C(═NH)—NH—(CH 2 ) m —, —C(═O)—NH—(CH 2 ) m —, or —, —C(═S)—NH—(CH 2 ) m —, m is an integer of 0 to 20, n is a positive integer, k is 0 or 1, X represents hydrogen, an amino group, a hydroxyl group, a methyl group, a phenyl group, a chlorophenyl group or a methylphenyl group (tolyl group), and Z represents hydrogen, an amino group, a hydroxyl group, a methyl group, a phenyl group, a chlorophenyl group, a methylphenyl group (tolyl group) or a polymer, having a weight-average molecular weight of 200 to 1,000,000, being a polymer comprising, as a repeating unit, one of the polymerization groups represented by the following general formula (2); in the formula, p is an integer and wherein the guanidine compound and/or salt thereof has a biguanide structure represented by the following general formula (3) in a molecule thereof;