Research On Inkjet Droplet Spreading And Penetration On Coated Inkjet Paper

Inkjet printing technology with its low-cost, environmentally friendly materials and good features has become an important field of digital printing. The market prospects are very bright. Characteristics of paper and ink, and they mutual adaptation determine the final image quality of the products in ink jet printing systems. Print resolution and accuracy of color reproduction have close relationship to the ink droplets hitting, spreading, penetration and the drying process after it is transferred to the printing substrate.During the interaction of the ink-jet printing ink and substrates, penetration and spread ability are important factors affecting the quality of the final printed product. The paper mainly researched the process of inkjet ink droplets spreading, penetration onto coated inkjet paper from both theoretical and experimental aspects, as well as the effects of ink droplets and paper interaction on printing quality. On theoretical side, droplets spreading and penetration into the porous structure was modeled according to the lubrication approximation theory of fluid mechanics and Darcy flow equation combined with the structural parameters of the structure of porous substrates. On the experimental side, five inkjet paper with different porous coating structure was made by changing the proportion of adhesive in the coating formula. Then its internal structure was measured by mercury intrusion method; Pictures of droplet of distilled water, ethyl ene glycol, aqueous solution of Tween-80 on 5 paper samples obtained in the above experiments were photographed in Is and 3s period of time with dynamic contact angle analyzer in continuous shooting mode, The dynamic process of spreading and penetration were combined with theoretical part in order to analyze the role of law droplet spread and penetration and the factors that affect it; Finally, each paper samples were printed to study the effects of ink droplets interaction on inkjet printing performance.The results are as follows:with the increase in the amount of adhesive, paper coating porosity gradually decreases and the average pore size first increases and then decreases, but on the whole it gradually reduced; paper porosity and the average pore size affect the droplets behavior in the paper. The greater the porosity, the smaller the average pore size, droplet spreading gests weaker and permeability gets stronger; liquid surface tension and viscosity affect droplets spreading and penetration onto the paper. When liquid surface tension is reduced, the initial contact angle of the droplet on the inkjet paper becomes small and dynamic contact angle, droplet height coefficient the droplet spreading coefficient changes rapidly, during the spreading and penetration stage. When increase the viscosity of the liquid droplets in the process of spreading and penetration of the viscous dissipation, dynamic contact droplet contact angle, droplet height coefficient the droplet spreading coefficient change slows during the spreading and penetration stage. Overall, the impacts of porosity of inkjet paper outperform average pore size of that on the printing performance. The printed products achieve the best printing performance when the porosity of the paper is larger while the average pore size is appropriate.