Abstract: The present invention relates to a coolant composition for fuel cell coolant, comprised of sulfur containing alcohol or sulfur containing phenol having at least one sulfur atom per molecule, which effectively prevents increase of electric conductivity due to oxidation of its base component for a long time. The coolant composition when diluted with water to a predetermined concentration effectively suppresses increase of electric conductivity of the coolant and maintain fluctuation of electric conductivity within the range from 0 to 10 ?S/cm so that power generation efficiency of the fuel cell may not be lowered.

Abstract: An antifreeze/coolant composition, comprising a) a base material such as water, alcohol, glycol and glycol ether; b) a fluorine compound and c) an inorganic acid.

Abstract: The present invention relates to a coolant composition for fuel cell coolant, comprised of sulfur containing alcohol or sulfur containing phenol having at least one sulfur atom per molecule, which effectively prevents increase of electric conductivity due to oxidation of its base component for a long time. The coolant composition when diluted with water to a predetermined concentration effectively suppresses increase of electric conductivity of the coolant and maintain fluctuation of electric conductivity within the range from 0 to 10 ?S/cm so that power generation efficiency of the fuel cell may not be lowered.

Abstract: An antifreeze/coolant composition, comprising a) a base material such as water, alcohol, glycol and glycol ether; b) a fluorine compound and c) an inorganic acid.

Abstract: The present invention provides a coolant composition which has a glycol as a main ingredient, is excellent in stability in a hard water, and has excellent corrosion preventing properties for aluminum and aluminum alloys, and the coolant composition is characterized by comprising: (a) 0.1-10% by weight of at least one ingredient selected from the group consisting of alkyl benzoic acids, aliphatic dicarboxylic acid or their salts; (b) 0.01-2.0% by weight of phosphate; (c) 0.01-0.5% by weight of 2-phophonobutane-1,2,4-tricarboxylic acid or its salt; and (d) 0.01-0.5% by weight of at least one ingredient selected from the group consisting of C4-C6 polymers and copolymers of unsaturated monoethylene dicarboxylic acid or their salts, polymers and copolymers of C4-C6 unsaturated monoethylene monocarboxylic acid or their salts, and copolymers of the above described C4-C6 unsaturated monoethylene dicarboxylic acid and the above described C4-C6 unsaturated monoethylene monocarboxylic acid.