| 摘要 |
PROBLEM TO BE SOLVED: To easily remove flux from the surface of a steel sheet and to execute hot dip plating of tin-zinc extremely good in plating appearance by coating the surface of a steel sheet with flux having the m.p. lower than the bath temp. of a tin-zinc plating bath by a specified temp. on the surface and thereafter dippinig the steel sheet into the plating bath. SOLUTION: The surface of a steel sheet is coated with flux, which is thereafter dipped into a tin-zinc plating bath to obtain a tin-zinc plated steel sheet. At this time, as the flux, the one having the m.p. lower than the temp. of the tin-zinc plating bath by >=20 deg.C is used. In this way, the flux entangled by the steel sheet into the plating bath is melted, also its viscosity is made low, and it is easily removed from the steel sheet and does not deteriorate the plating appearance by being left. Moreover, as this flux, the compsn. essentially consisting of one or more kinds among ZnCl2, SnCl2, NH4Cl, ZnSO4 and Na2SO4 is preferable since being effective for the activation of the surface of the steel sheet and also obtainable at a relatively low cost.
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