Cleaning liquid for aqueous ink comprising an acetylene glycol-based surfactant

A method of cleaning a water-based ink comprising the step of allowing a water-based ink that comprises a pigment and a water-insoluble polymer to come into contact with a cleaning liquid comprising (A) an acetylene glycol having an average molar number of addition of ethyleneoxide of not less than 0 mol and not more than 2 mol, (B) at least one compound selected from the group consisting of (b-1) an acetylene glycol having an average molar number of addition of ethyleneoxide of not less than 4 mol and (b-2) a polyethylene glycol alkyl ether comprising an alkyl group having not less than 8 carbon atoms, (C) a water-soluble organic solvent and water, in which

• the water-soluble organic solvent (C) comprises at least one water-soluble organic solvent having a boiling point of not lower than 90° C.;
• a boiling point of the water-soluble organic solvent (C) is not higher than 250° C. in terms of a weighted mean value of boiling points of respective water-soluble organic solvents therein which are weighted by contents (% by mass) of the respective water-soluble organic solvents;
• and
• a content of the water-soluble organic solvent (C) in the cleaning liquid is not more than 20% by mass.

A process for producing a cleaning liquid for a water-based ink, comprising the step of compounding (A) an acetylene glycol having an average molar number of addition of ethyleneoxide of not less than 0 mol and not more than 2 mol, (B) at least one compound selected from the group consisting of (b-1) an acetylene glycol having an average molar number of addition of ethyleneoxide of not less than 4 mol and (b-2) a polyethylene glycol alkyl ether comprising an alkyl group having not less than 8 carbon atoms, (C) a water-soluble organic solvent and water, in which

• the water-soluble organic solvent (C) comprises at least one water-soluble organic solvent having a boiling point of not lower than 90° C.;
• a boiling point of the water-soluble organic solvent (C) is not higher than 250° C. in terms of a weighted mean value of boiling points of respective water-soluble organic solvents therein which are weighted by contents (% by mass) of the respective water-soluble organic solvents;
• a content of the water-soluble organic solvent (C) in the cleaning liquid is not more than 20% by mass;
• the water-soluble organic solvent (C) is a combination of a polyhydric alcohol and a polyhydric alcohol alkyl ether other than the polyethylene glycol alkyl ether (b-2);
• and
• the cleaning liquid comprises neither a pigment nor a polymer.