Research On Printing Suitability And Evaluation Methods Of Uncoated Inkjet Printing Paper

In this paper, to obtain the optimum production process in laboratory conditions, multiple indicators in the orthogonal experiment were used to study the impact of the ratio of the raw materials and process conditions on paper performance and printability. Next, the average permeability and distributions of water-based pigment ink in paper interior were studied through the idea of “layer to layer” combined with the image processing technology and optical microscopy techniques. Meanwhile, the impact of fiber surface conditions and paper porosities on the spreading and penetration of ink and printing quality were studied. To solve the problem of uncoated paper with high average ink permeability and surface absorptivity, the cationic fixing agent and amphoteric sizing agent were used to modify the uncoated paper surface and research their impact on paper properties and printing qualities, making the paper obtain the moderate hydrophobicity and improved printing qualities. Finally, The model of PCA and cluster analysis were used to evaluate the comprehensive properties of uncoated paper with the modified surface and compare with the commercial inkjet paper to get the overall performance ranking.The main findings and conclusions are as follows:(1) With considering the paper surface properties, printability and water resistance, four factors and three levels multi-index orthogonal test were used to evaluate the uncoated inkjet paper quality. The results found that the combination A1B2C3D3 showed the best performance, which meant that when 85: 15 of hardwood pulp to coniferous pulp, 0.1% of AKD, 25% of PCC, 3MPa of calendaring pressure were applied, the paper showed the best performance. So the formulation was choose for further study.(2) To accurately study the ink distributions, the ink penetration depth and ink permeability, the laser scanning confocal microscopy and image analysis technology were used to obtain ink behaviors in paper interior. The experimental results indicated that paper specimens with sizing agent were resistant to the ink, resulting in a slow and shallow ink penetration. Paper containing filler had a more hydrophilic surface and porous structure, leading to a faster and deeper ink penetration. However, the calendaring operation could make the paper structure more compact and reduce the porosity and penetration depth. When an appropriate combination of sizing agent, filler content, and the calendaring process was utilized, a more stable hue could be produced with improvements in optical density, saturation, and color.(3) The SMA1000 with amphoteric groups was used as the sizing agent, which can greatly improve the paper surface water resistance. But it had a limited improvement to printing quality. The addition of cationic fixing agent can both moderate the hydrophobicity and promote the printability. But there was an optimum addition ratio problem with the fixing agent. The physical performance and printability varied as the different ratio of fixing agent in the sizing agent. When the ratio of SMA1000 to PDADMAC was 100 to 5, the comprehensive performance of uncoated paper was optimum.(4) With considering the paper physical parameters and subjective emotional parameters, the principle component analysis and cluster analysis model were used to evaluate the paper overall performance by using the discretely data. The data showed some the uncertain relationship of the different samples. The results found that the modified uncoated ink-jet ranked in the mid-range of the market paper, which could meet production needs.