Patent ID: 7833359

Claim:
A method for cleaning articles to be cleaned by microbubbles, comprising: preparing a detergent comprising a surfactant for microbubble formation; generating microbubbles by feeding the prepared detergent to a microbubble generator to obtain microbubbles having a gas-liquid interface; and cleaning the article by contacting the microbubbles with the article and utilization of the gas-liquid interface of the generated microbubbles; wherein the surfactant for microbubble formation comprises: a (poly)oxyalkylene adduct (A) of an active hydrogen atom-containing compound (a) as represented by formula (1): Z-[(AO) n —H] p (1) wherein Z is a residue of an active hydrogen-containing compound (a) with a valence of P as resulting from removal of the active hydrogen atom or atoms; A is an alkylene group containing 1 to 8 carbon atoms; n is an integer of 1 to 400; and p is an integer of 1 to 100; wherein the microbubble generator is at least one selected from the group consisting of a slit, a porous plate, a fine needle, a membrane and a venturi, a foaming power of a 0.02% by weight aqueous solution of the (poly)oxyalkylene adduct (A) as measured at 20° C. by the Ross Miles test is not higher than 50 mm.