液滴体积对定量打印有重要意义, 而墨水粘度对液滴体积有重要的影响。首先, 利用层流-水平集方法建立了喷嘴模型。依据实验经验设置模拟所用墨水密度为1.0 g/mL, 表面张力为28 mN/m, 粘度为1～15 mPa·s, 对不同粘度墨水喷射过程进行了演示, 得到了液滴体积与墨水粘度关系为负相关; 然后, 通过水平集函数积分对液滴体积进行量化, 得到了其变化范围为58.10~37.29 pL, 并对液滴体积与墨水粘度关系进行拟合得到二者为负线性关系, 具体线性系数为A=-1.54, 纵截距为B=60.2。其次, 利用相同物理参数下的聚硫醇墨水进行了打印实验, 得到液滴体积变化范围为149.9～92.9 pL, 且拟合得到液滴体积与粘度仍为负线性关系, A′=-4.12, B′=154.71, 证明了模拟结果的正确性。最后, 通过模拟与实验结果的对比发现两者所得线性函数之间存在一系数h=2.5, 通过进一步仿真研究证明该系数与墨水的种类无关, 而是由入口处的压力决定。该线性结果有利于简化任意低粘度墨水的定量打印。

Drop volume is important for quantitative printing, while ink viscosity has an important influence on droplet volume. First, a nozzle model was proposed based on laminar flow-level set method. The ejection processes of droplet with different viscosity at different moments were demonstrated, under the condition that the ink density is 1.0 g/mL, the surface tension is 28 mN/m, and the viscosity is 1-15 mPa·s, and the negative correlation between the droplet volume and viscosity of ink was obtained. Then, the droplet volume was quantified through the integration of the level-set function, and the variation range is 58.10-37.29 pL; and a negative linear relationship between the volume of droplet and the ink viscosity was obtained by linear fitting, specifically, “A=-1.54”, “B=60.2”. Secondly, the printing experiment was carried out by the printing of polythiol ink under the same physical parameters, and the variation range of droplet volume was 149.9-92.9 pL, and the specific fitting relationship between the droplet volume and the ink viscosity was still a negative linear relationship: “A′=-4.12”, “B′=154.71”, which proved the simulation result. And the results of simulation and experiment show that there is a coefficient “h=2.5” between the linear function of them, and coefficient “h” was proven to be independent of the type of ink, but to be determined by the inlet pressure through the further simulation research. This study can help to simplify the quantitative printing process of any type of ink with a lower viscosity.