Waterborne polyurethane emulsion for composite laser coating

Abstract

The invention discloses waterborne polyurethane emulsion for a composite laser coating. The waterborne polyurethane emulsion is prepared by the following steps: performing vacuum dehydration on macromolecular polyhydric alcohol at the temperature of 120-130 DEG C for 1-1.5 hours, reducing the temperature to be 50-60 DEG C, adding diisocyanate and epoxy resin, raising the temperature to be 75-85 DEG C, and reacting for 2.5-3 hours; adding a hydrophilic chain extender and reacting for 1-2 hours; adding an alcohol chain extender and reacting for 2-3 hours, and adding acetone to reduce the viscosity during the period; adding a neutralizer, and carrying out a neutralization reaction at the temperature of 40-50 DEG C for 0.5-1 hour to obtain a neutralization product; adding the neutralization product into water in which an amine chain extender is dissolved, carrying out shearing emulsification at 30-40 DEG C for 0.5-2 hours while controlling the stirring speed to be 2000-4000rpm to obtain primary emulsion, and evaporating to remove acetone under reduced pressure to obtain the emulsion. The emulsion is a self-emulsified system and does not contain small molecular emulsifier, and an emulsifier migration phenomenon is avoided; the waterborne polyurethane emulsion is high in adhesive force with a base material, and interlayer separation is avoided; moreover, the waterborne polyurethane emulsion has high solvent resistance and paint film printability.

Description

technical field [0001] The invention relates to a polyurethane emulsion and a preparation method thereof, in particular to a water-based polyurethane emulsion for a composite laser coating. Background technique [0002] As countries around the world are increasingly concerned about environmental protection and related pollution prevention and control regulations are becoming increasingly stringent, the resin manufacturing industry has undergone revolutionary changes in the past few years, that is, the original high-pollution solvent-based resins have been transformed into low-pollution environmentally friendly resins. . Water-based coatings are coatings made with water as a solvent or dispersion medium. Its biggest feature is that water replaces organic solvents, and the film-forming substances are dispersed or dissolved in water. After drying and solidifying, the paint film has physical properties similar to solvent-based paints. [0003] Laser coating has always occupied...

AI Technical Summary

Problems solved by technology

[0004] Most of the existing composite laser coatings are solvent-based systems, which use a large amount of organic solvents. On the one hand, the high content of volatile organic compounds will cause serious pollution to the production and use environment; threat to the health of

Although some existing patents are aimed at solutions for water-based composite laser coatings, most of them are compounded with acrylic resin or polyurethane resin and need to add defoamers and anti-adhesive additives. The components are more complicated and there will be compatibility with the main resin. Sexuality and long-term placement of additives precipitation and other issues