Examples of the water soluble organic solvent include alkyl alcohols having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol and sec-butyl alcohol; ketones or ketone alcohols such as acetone or acetone alcohol; ethers such as tetrahydrofuran and dioxane; polyhydric alcohols such as ethylene glycol, propylene