表面膜层对镀锡板表面张力及印铁缩孔的影响

Effect of surface films on surface tension of tinplate and shrinkage hole during printing

针对镀锡板与涂料的表面张力不匹配所导致的缩孔问题,采用达因笔检测镀锡板表面张力,并进行印铁测试,以观察缩孔情况,还通过热重分析与X射线光电子能谱研究了镀锡板表面油膜、钝化膜与氧化膜在印铁环境中的变化。结果表明:油膜对镀锡板表面张力与印铁缩孔有一定影响,当涂油量由2 mg/m^(2)增加至6 mg/m^(2)时,表面张力由29 mN/m降低至27 mN/m,出现印铁缩孔;钝化膜在3~7 mg/m^(2)范围内对镀锡板表面张力与印铁缩孔无直接影响;氧化膜对镀锡板表面张力与印铁缩孔有明显影响,当氧化膜量增加到1.99 mC/cm^(2)时,表面张力降至27 mN/m,出现印铁缩孔。预烘烤可使表面DOS油提前挥发,且能使氧化膜中不稳定的SnO转化为稳定的SnO2,有利于避免印铁缩孔问题。

In order to solve shrinkage hole caused by surface tension mismatch between tinplate and coating,the surface tension of tinplate was tested by Dyne pen and the phenomena of shrinkage hole was observed by printing test.The changes of oil film,passivation film and oxide film on tinplate surface under printing environmental condition were studied by thermogravimetric analysis and X-ray photoelectron spectroscopy(XPS).The results showed that the oil film had effect on the surface tension of the tinplate and shrinkage hole during printing.As the oil content increased from 2 mg/m^(2)to 6 mg/m^(2),the surface tension dropped from 29 mN/m to 27 mN/m and shrinkage hole appeared during printing.The passivation film with the content range between 3 mg/m^(2)and 7 mg/m^(2)has no direct impact on the surface tension and the shrinkage hole during printing.The oxide film has obvious influence on the surface tension and the shrinkage hole during printing.When the oxide film content reached 1.99 mC/cm^(2),the surface tension reduced to 27 mN/m and the shrinkage hole appeared during printing.DOS oil on tinplate surface could be volatilized in advance and unstable SnO be converted into stable SnO2 in oxide film by pre-baking,which is conductive to avoid shrinkage hole during printing.