On removing oils and the like such as machine oil, rolling oil, and rust-preventive oil attached to machines, mechanical parts, and the like, or on removing oils and the like generated during fiber-processing stage and attached to facilities, there are used in recent years a water-base cleaner consisting mainly of nonionic and anionic surfactant, and a strong-alkali cleaner combining the water-base cleaner with a strong alkali. In case of conventional cleaners which enhance the increased cleaning power and foamability, however, the water-oil separability in the cleaned waste liquid becomes insufficient to apply heavy load to the wastewater treatment, because oils form stable emulsion in the cleaned waste liquid after cleaning or because oils stably become solubilized in the cleaned waste liquid after cleaning. Current serious concern about the environmental problems raises the requirement of reducing the quantity of waste liquid generated from the water-oil separation treatment and of recycling the cleaner. Thus a cleaner having excellent water-oil separability in the cleaned waste liquid is desired.
As the above cleaners, there is disclosed a cleaner composition containing (A) a polyoxyalkylene additive of alkyl amine or alkyl amide, having hydrocarbon group with the number of carbon atoms from 8 to 22, and (B) at least one compound selected from the group consisting of an alkyldimethylamine oxide having hydrocarbon group with the number of carbon atoms from 8 to 22, an alkyl-di (aminomethyl)glycine having hydrocarbon with the number of carbon atoms from 6 to 22, a straight chain sodium dodecylbenzene sulfonate, and betaine lauryldimethyl aminoacetate. Furthermore, there is a disclosed cleaner prepared by mixing the (A) component with the (B) component at a specific mixing rate intending to improve the cleanability, the foamability, and the water-oil separability after cleaning, (for example, see Patent document 1.)
In addition, there is a disclosure of water-oil separating cleaner containing an N-alkyl-N-(2-hydroxyalkyl)-iminoethylene carbonate, (for example, see Patent document 2.)    [Patent document] Japanese Patent Laid-Open No. 2003-119496    [Patent document] Japanese Patent No. 3430147
Regarding the cleaning composition disclosed in Patent. document 1, however, a cleaner composition which uses a polyoxyethylene additive of alkylamine or alkylamide having a polyoxyethylene chain with oxyethylene units from 2 to 50, particularly preferably oxyethylene units from 10 to 50, as the (A) component becomes emulsion by itself to show water-soluble property. Thus, when that type of composition is used to the machines, the mechanical parts, and the like to which oils such as grease, engine oil, machine oil, and rust-preventive oil, (in particular grease-base oil, naphthene-base mineral oil, paraffin-base mineral oil, poly-α-olefin, polyol ester, and polydimethyl siloxane), are attached, the satisfactory cleanability and the water-oil separability in the cleaned waste liquid cannot be attained at the same time, and further a problem of rust-generation on the parts to be cleaned arises during or after cleaning.
As for the use of cleaner disclosed in Patent document 2, the water-oil separability after cleaning is significantly influenced by the temperature of the cleaning liquid. Since, at low temperatures, separation of oil layer from aqueous one takes a long time, the reduction in load to the wastewater treatment is not sufficient. In addition, cleanability and rust-preventive performance are not sufficient.