In water-based ink, water-based resin, as an important part of water-based ink: ink binder, directly affects the adhesion function, drying speed, anti fouling function and heat resistance of ink. Together, it also affects the gloss and ink transfer function. Therefore, the selection of appropriate water-based resin is the key of water-based ink. It has the functions of good affinity with colorant, high adhesion fastness after printing film, good wear resistance, scratch resistance, heat resistance, high gloss, and good water release and easy cross-linking film formation when printing is dry. Commonly used waterborne resins include waterborne polyurethane resin, acrylic resin, polyvinyl alcohol and epoxy resin.
Waterborne polyurethane resin: by linking hydrophilic groups on polyurethane molecules, it is dispersed in water, and water is used to replace the traditional solvent. Waterborne polyurethane resin has the advantages of simple application, stable function, strong adhesion, excellent gloss and good heat resistance. It can be suitable for various printing methods, especially for screen printing, plastic packaging and composite film. Although waterborne polyurethane has great advantages in reducing VOCs, there is no free NCO - in the system, many functions are prominent and widely used, it has not yet reached the function of solvent polyurethane resin. The main reason is that most waterborne polyurethane is prepared by using polyurethane containing hydrophilic groups as solid components, which can not reach the crosslinking density and high molecular weight that solvent polyurethane can obtain. Therefore, the water resistance, solvent resistance and heat resistance of waterborne polyurethane are poor, which reduces the application function. In order to overcome waterborne polyurethane, modification was carried out to improve its function. The improved methods include crosslinking (i.e. internal crosslinking and external crosslinking), grafting, blocking other polymers and blending to form interpenetrating polymer networks.
蘇州恩敬新材料有限公司
