| 摘要 |
PURPOSE:To remove and clean soil such as lubricating oil stuck on surfaces without damaging Sn plating layers by cleaning Sn plated cans in an alkaline cleaning soln. consisting essentially of alkali metallic silicate. CONSTITUTION:The two-piece cans produced by forming Sn-plated steel sheets are stuck with lubricating oil used in the working. In order to remove oil and clean the can surfaces, they are cleaned in an aqueous soln. contg. 1-20g/l metallic silicate such as Na salt or K salt of metasilicic acid or orthosilicic acid. Further, alkali metallic carbonate such as Na2CO3, or K2CO3 or alkali metallic hydrogencarbonate such as sodium hydrogencarbonate is added as an alkali component at <=1.5 times the alkali metallic silicate to the cleaning soln. to control its pH to 10-13.5. Also, a detergent surfactant, a foam-inhibitive surfactant, etc. are added at <=0.4 time the alkali metallic silicate, and the soln. is used at room temp. or 80 deg.C. |
