A Study On Properties Of Advanced Thickner System Under The Indusreial Digital Printing Condition

The appearance of digital printing has broken the traditional printing which has the technical limitations of plate making, color performance, etc.Digital printing is the development and extension of the traditional printing, which make production convenient and environment-friendly.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. 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. Therefore excellent digital printing thickener must be developed to suite for carpet digital printing.Most of the digital printing thickener is synthetic thickener and mainly is the polyacrylate thickener. Because compared with the natural thickener,the synthetic thickener has the high viscosity, high-velocity and low soild content. Under the shear stress, the paste become thinner, showing good mobility, and once the shear stress removed, paste viscosity is quickly restored. 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. In order to keep the available of the paste, we should mix the different thickener.First of all, the physical and chemical properties of current carpet printing digital DCS are studied containing the ability of holding water,the sensitivity to dye、electrolyte and temperature. Secondly, through the orthogonal experiment, selecting the best factor in SAK, SC, UK and HTP and the corresponding optimal levels. SAK and UK are polyacrylate synthetic thickener and SC is cationic modified starch thickener. Then Using the optimum levels of the various factors to compound with a new thickener. After that the physical and chemical properties were tested to compared with DCS to find out of room for improvement. Through the surface active agent, crosslinking agent, printing paste, the performance of the composite thickener was improved. 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 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.The experimental results show that only by polyacrylate and cationic modified starch thickener distribution, the system can’t satisfy the carpet digital printing. By adding the surface active agent, crosslinking agent and printing paste to reduce the sensitivity to dye、electrolyte and temperature and have the higher degree of thixotropy.Eventually thickening agent formula is containing1.0%SAK,0.1%SC,0.4%UK,0.1%HT,0.2%PEG,0.3%crosslinking agent,1.0%DY982and96.90%distilled water, then adding0.3%triethanolamine of the whole system to change the pH. 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. So can replace the imported products used in the factory, completely applied in nylon carpet digital printing.