| 摘要 |
An alkaline degreasing solution containing 0.01 to 3 g/l of alkali silicate calculated as Si concentration, and 0.01 to 10 g/l of a nonionic surfactant having an HLB value (=20xMw/M, where Mw represents the weight of a hydrophilic group part and M represents the molecular weight of the surfactant) of 5 to 11 and a structure being expressed in the following general formula (I), with a pH value of at least 9.5:R-O-(EO)m(AO)nH(I)where R represents alkyl group, EO represents ethylene oxide group, AO represents alkylene oxide group (propylene oxide group and/or butylene oxide group), m represents an addition molar number of EO which is an integer of 3 to 7, n represents an addition molar number of AO which is an integer of 1 to 6, and m and n satisfy the relation of n<m</=3n.
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