METHOD FOR COMPOUNDING PLATING STOP-OFF AGENT FOR PLATING ON ONE SIDE

摘要

PURPOSE:To obtain a plating stop-off agent for plating on one side which provides substantially the function thereof and yields an excellent steel sheet plated on one side by dissolving caustic soda, boric acid, water glass in this order or in order of water glass, caustic soda and boric acid in water then adding MgO, TiO2 and Al2O3 thereby compounding a water slurry. CONSTITUTION:Caustic soda, boric acid and water glass are dissolved in water in order mentioned above and thereafter MgO, TiO2 and Al2O3 are added thereto to prepare a water slurry. The prepn. temp. of the water slurry is required to be limited within a 20-60 deg.C range. The stop-off agent consisting of the resulted water slurry is coated on one surface of a thoroughly degreased steel sheet at 5-300g/m2 dry coating weight. The steel sheet formed with the uniform dry coated film of the stop-off agent on one side is subjected to annealing at 600- 900 deg.C and is dipped in a plating bath after cooling down to the temp. approximate to the plating bath temp. The steel sheet pulled from the plating bath is bent while the surface of the coated film is wet with water and the stop-off agent is stripped from the steel sheet. The steel sheet satisfactorily plated on one side is thus obtd.