凹版胶印油墨分离产生卫星液滴研究

Satellite Droplets Generation from Ink Transferring in Gravure-Offset

目的研究凹版胶印过程中的第3阶段,即油墨从橡皮布滚筒向承印物转移时,油墨黏度和分离速度对卫星液滴的影响。方法利用Maxwell粘弹性模型,从理论的角度分析油墨黏度和分离速度与卫星液滴产生之间的关系,并模拟凹版胶印中油墨转移的第3个过程,即油墨在两平板间的分离,论证三者之间的关系。结果分离速度v=0.1 m/s、黏度μ=0.25 Pa·s时产生的卫星液滴为4个,且大小几乎相同并集中;分离速度和黏度较小时,所产生的卫星液滴数目越少,但其中一定有1个最大的卫星液滴;分离速度和黏度较大时,所产生的卫星液滴小而多,且分散。结论分离速度v和油墨黏度μ与卫星液滴产生的数目成正相关关系,在印刷速度(分离速度)一定时,减少甚至消除"卫星液滴"应当选择低黏度、高弹性模量的油墨,从而降低油墨的应力松弛时间。

Objective To study the effects of ink viscosity and separation speed on the satellite droplets at the third stage of Gravure-Offset process, namely, during the transferring of ink from blanket to substrates. Methods From theoretical point of view, the relation between viscosity, separation speed and satellite droplets were analyzed using Maxwell viscoelastic model. We then simulated the third stage of Gravure-Offset process, namely, ink transferring between the two separating plates, in order to demonstrate the relation among them. Results When the separation speed v and μ viscosity were 0.1 m/s and 0.25 Pa·s, respective, there were four relatively concentrated satellite droplets with almost the same size.When the speed v and μ viscosity were low, there were few satellite droplets, but there must be a largest satellite droplet among them. When the speed v and μ viscosity were large, there were many dispersive and small satellite droplets.Conclusion The separation speed v and μ ink viscosity were positively correlated with the amount of satellite droplets generated. At a certain printing speed（separation speed）, ink with low viscosity and high elasticity should be chosen to decrease the stress relaxation time of the ink, thus reduce or eliminate satellite droplets.