Method for producing a stock solution composition for a coolant and a coolant composition for fuel cell vehicles with improved storage stability

摘要

A method of preparing a stock solution composition for a coolant for a fuel cell vehicle, the stock solution composition comprising at least one ethylene glycol compound selected from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol and used by dilution with a diluent comprising water, and the method comprising the following steps: (a) a step of selecting an ethylene glycol compound from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol and having an ethylene glycol monoformate content of 60 ppm or less as a raw material for the stock solution composition; or (b) a step of selecting an ethylene glycol compound from the group consisting of ethylene glycol, diethylene glycol and triethylene glycol as a raw material for the stock solution composition, wherein a 50% by mass aqueous solution of the ethylene glycol compound has a conductivity of 4.5 µS / cm or less after the aqueous solution was heated at 88 ° C for 24 hours to allow the hydrolysis of the ethylene glycol monoformate to occur.