Preparation method of high solid content waterborne polyurethane

Abstract

The invention relates to a preparation method of high solid content waterborne polyurethane. The waterborne polyurethane is higher than common organic solvent in latent heat of evaporation, and water solvent type polyurethane in waterborne polyurethane of the same solid content is slow in solvent evaporation and needs long drying time. The preparation method comprises the steps of mixing polymer polyol with polyisocyanates under the protection of nitrogen, stirring evenly and then adding catalyst for reacting; adding a hydrophilic chain extender for reacting; cooling, adding a solvent and a neutralizer so as to obtain a prepolymer and stirring at high speed so as to disperse in deionized water; adding the chain extender, stirring, reducing pressure and removing the solvent through steaming so as to obtain the waterborne polyurethane emulsion; and preparing the prepolymer of different size distribution, dispersing in the waterborne polyurethane emulsion along with velocity mixing, and stirring for 1-4 hours. The waterborne polyurethane emulsion has wide size distribution and low viscosity, is stable, and can solve the key technical problems of high latent of evaporation, slow volatilization, long drying time, low production efficiency and the like in the field of research of the waterborne polyurethane.

Description

technical field

[0001] The invention relates to a resin, in particular to a preparation method of high-solid-content waterborne polyurethane. Background technique

[0002] Water-based polyurethane (WPU) refers to polyurethane that uses water instead of organic solvents as the dispersion medium, and its dispersion contains no or very small amounts of organic solvents. The coating film has the advantages of being non-flammable, non-toxic, non-polluting, energy-saving, etc., and has the inherent high strength and wear resistance of general polyurethane resins, so it has been widely used. High solid content waterborne polyurethane has low water content, fast drying and film formation, high solid content emulsion also has the advantages of high equipment utilization rate, transportation cost and low energy consumption per unit product, so it has attracted much attention.

[0003] The final state of waterborne polyurethane is a solid film. During the process from the emulsion to...