Polyurethane has excellent strength, flexibility, heat resistance, cold resistance, wear resistance, organic solvent resistance, and great adhesive force. But the polyurethane emulsion stability and self thickening of the poor, and the solid content is not too high, the film water resistance, alkali resistance and gloss are not ideal, yellowed, high cost. If polyurethane is used to modify acrylic polymer emulsion, it can avoid the shortcomings of the two and have their own advantages. It not only solves the problems of polyacrylic, such as "hot sticky, cold and crisp", but also overcomes the defects such as aging and yellowing of polyurethane. At the same time, it can make stable, high solid content and self thickening of polymer emulsion. Polyurethane modified acrylic polymer emulsion has been widely applied in many fields, such as coatings, adhesives, fabric finishing agents, metal primers, leather finishing agents, biomedicine and many other fields.
The preparation of polyurethane modified acrylic polymer emulsion can be made through four ways: polyurethane emulsion and acrylic polymer emulsion blend. The monomers with double bonds and isocyanic acid are copolymerized with acrylic monomers. Polyurethane emulsion was used as seed to make seed emulsion polymerization. A solvent based carbamate acrylic emulsion copolymer was first prepared, then solvent was removed, then neutralization and emulsification were carried out. In the past ten years, both at home and abroad on the synthesis and application of polyurethane modified polyacrylic emulsion is studied, using the new concept of "particle design", by changing the composition of raw materials, synthesis process and reaction conditions, made with graft structure, core-shell structure and polyurethane interpenetrating network structure modified acrylic polymer emulsion in latex inside, to further improve the performance, broaden the application fields.
TMI can be copolymerized with acrylic monomers, and the isocyanate group on the molecule provides crosslinking points for the copolymers. The copolymer emulsion produced is stable at room temperature, and its drying speed is fast. Compared with the pure acrylic polymer emulsion, the mechanical properties of the coating made by it were increased by nearly 50%, and the wear resistance was increased by 10 times.