Polyurethane-acrylate hybrid emulsion successfully synthesized at Hunan University
Nantong Weizhuo Environmental Protection Equipment Co.,Ltd , https://www.cwznts.com
With the increasing awareness of environmental protection, many countries have legislation that strictly limits organic volatiles (VOCs) in coatings. Environmentally friendly coatings are an inevitable trend in the development of coatings. Waterborne coatings are considered to be the best coatings for VOC reduction and have developed very rapidly in recent years. At present, the waterborne coating base materials on the market mainly include polyacrylate (PA) emulsions and polyurethane (PU) emulsions. Compared with solvent-based products, they have the advantages of safety, non-flammability, non-toxicity, and no environmental pollution, but a single PA emulsion. The film-forming properties, abrasion resistance, chemical resistance, adhesion, and other properties are poor, and the PU emulsion is not satisfactory in terms of stability, self-thickening, solid content, and water resistance. In recent years, many researchers have used the good complementarity of PU emulsion and PA emulsion to copolymerize to prepare polyurethane-acrylate (PUA) composite emulsion. Although the performance of PUA composite emulsion has been greatly improved, as a base material for waterborne wood coatings, there are still disadvantages such as high water absorption and low hardness. Based on previous studies of PUA composite emulsion, epoxy resin was added to synthesize epoxy-modified polyurethane-acrylate (PUEA) composite emulsion, and its performance was tested. Studies have shown that the water absorption of the PUEA composite emulsion coating is significantly reduced, and the hardness and other related properties are also improved.
The steps developed were the preparation of emulsions and coating films. Two kinds of chemical copolymerization and physical blending methods were tested. Experimental materials include toluene diisocyanate (TDI-80), epoxy resin (CYD-012), polyether glycol (PPG-10), dimethylol propionic acid (DMPA), and 1,4-butanediol ( BDO), triethylamine (TEA), ethylenediamine (EDA), and the like. The results show that the addition of epoxy resin has a significant effect on the stability of the prepared PUEA emulsion. It is proved by experiments that the mass fraction of epoxy resin added is 3 to 4%, and the particle size of the PUE/MMA dispersion latex particle is small. With uniform size distribution, the average particle size of PUEA composite latex particles increases and their distribution also becomes larger. The heat resistance of PUEA composite emulsion is better than that of PUE/MMA dispersion; the emulsion prepared by chemical copolymerization has a pencil hardness and luster. Degree, water resistance and chemical resistance are better than those of physical blending methods, so the chemical copolymerization method is better when PUEA emulsion is prepared; PUEA emulsion prepared after adding epoxy resin is purer PUA than without epoxy resin. Many properties of the emulsion increase, especially water resistance, chemical resistance, hardness, and certain mechanical properties are significantly improved.