Analysis of basic properties of waterborne ink prepared by waterborne polyurethane

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2023-04-03

Waterborne acrylic resin emulsion was prepared by using butyl acrylate, methyl methacrylate, and methyl acrylate as monomers via emulsion polymerization. Afterwards, it was modified with waterborne polyurethane to produce waterborne polyurethane-acrylic resin emulsion. Two types of water-soluble resins were used as connecting materials, which were each formulated into waterborne inks and printed on the surface of PVC plastic. The difference in lightfastness between the two types of waterborne ink connecting materials in PVC plastic surface printing was compared, and the fundamental reasons were explored from a microscopic perspective.
Waterborne acrylic resin emulsion （referred to as PA emulsion） was prepared. Waterborne polyurethane-acrylic resin emulsion （referred to as PUA emulsion） was prepared by using PA emulsion, waterborne polyurethane, sodium lauryl sulfate, laboratory grade III water, a waterborne ink defoamer, ammonia water and other raw materials. The two types of waterborne inks were formulated according to the two plans in the table below, in which the waterborne ink formulated with PA emulsion as a connecting material was referred to as WPA, and the waterborne ink formulated with PUA emulsion as a connecting material was referred to as WPUA. The final pH of the waterborne ink was adjusted to between 8.0 and 9.0 using ammonia water.

Basic performance tests were carried out on the two types of waterborne inks formulated with different connecting materials, exploring the differences in performance between the two types of waterborne inks in terms of fineness, viscosity, initial drying time, color strength, pH value, adhesion and water resistance. The test results are shown in the figure below. From the figure, it can be seen that the fineness of WPA is between 0.2 and 5.0 μm, viscosity is between 10 and 30s, initial drying time is between 15 and 17mm, color strength is between 45% and 60%, pH value is between 8.0 and 9.0, adhesion is between 70% and 90%, and water resistance is level 4. The fineness, viscosity, initial drying time, color strength, and pH value of WPUA are the same as those of WPA. However, the adhesion of WPUA is between 75% and 95%, and the water resistance is level 5, which is better than that of WPA. This indicates that using WPUA has stronger cohesion and better water resistance when printing on the surface of PVC plastic. The fundamental reason mainly depends on the fact that the molecular chain of waterborne polyurethane contains hydrophilic groups of aminoethyl methacrylate (—NH—COO—), which not only has strong affinity with water, but also captures the hydrogen ions on the surface of PVC plastic molecules through these large molecular groups, making the two types of molecules firmly aggregate. Therefore, using waterborne polyurethane-modified connecting material after acrylic resin will significantly improve the adhesion and water resistance performance.

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