A Study On The High Viscous System For Digital Printing

Digital printing is a new and attractive technology which can save plate-making process, reduce costs and store digital printing patterns. However, the paste for digital printing is relatively harsh comparing with the traditional printing. A higher pseudoplastic is required for thickener used in digital printing to ensure good flow characteristics, clear printing pattern contour and unbleeding at the same time.An ideal printing thickener should satisfy the high-velocity and high viscosity at the same time. When the digital printing technology is applied in the carpet industry, especially the hydrophobic fabric, it is more difficult to ensure a clear outline of the pattern and the brightness.Based on the requirements for the digital printing paste and characteristics of thickener, the synthetic thickener is a key material which is mainly applied to the digital printing. The reason is that the synthetic thickener has the high degree of thixotropy compared with the natural thickener. Under the shear stress, the paste become thinner, showing good mobility, and once the shear stress removed, paste viscosity is quickly restored. Therefore, clear outline and smooth fine lines can be obtained with synthetic thickeners. However, the shortcomings of polyacrylate thickener are more sensitive to the electrolyte, also it is high moisture absorption capacity, easily leading to the infiltration of printing patents. Moreover, the printing paste is difficult to be washed from the fabric, leading the poor feeling of the fabric.For the purpose of developing a digital printing thickener, the paper has studied the effects of a variety of modifiers, additives, electrolyte, surfactant, pH, particle size, surface tension, high temperature, shear stress and other factors on the chemical, physical and flow properties of modified polyacrylate thickener based on the given polyacrylate thickener. On the basis of analyzing the testing results, a high-performance thickener system is designed and applied on a digital printing machine to test the the rheology, thixotropy, and viscoelasticity in practice, and the permeability of the print fabric, the pattern contour definition, the printing color yield and optimize the performance of the thickening system has all been evaluated. An ideal high viscosity system for digital printing has been developed and it shows that it is high viscosity, good fluidity and stability. The printing pattern has clear outline, fine lines, and bright full color. The printing effect of above thickening system for digital printing is good and on the leading position in domestic, it can replace the same products which is being imported on industry.