Study On The Composites Of Waterborne Polyurethane

Waterborne polyurethane(WPU)with water as dispersion medium has become the focus of many researchers for its advantages of nonflammable, low voc, environmental protected, energy-saving, simple curing process and so on. Waterborne polyurethane materials have been widely used because their flexibility, abrasion resistance, impact resistance and other characteristics are outstanding, while it has some problems such as the low initial stickness, poor water resistance and heat resistance, high-cost. In this article, we successfully prepared high-performance low-cost waterborne polyurethane composites through blending with waterborne epoxy emulsion and acrylate emulsion respectively.The present invention firstly synthesized a kind of polyester polyol in the presence of polyethylene glycol (PEG-1000), methyl hexahydrophthalic anhydride (MHHPA) and catalyst. Then reacted with MDI and synthesized waterborne polyurethane repolymer, finally used phenol as blocking agent and prepared blocked waterborne polyurethane successfully. The molecular structure of blocked waterborne polyurethane was characterized by FTIR spectroscopy. Investigated the effect of curing temperature and curing time on mechanical property of the adhesive in the presence of curing agent XCT-802. The waterborne epoxy resin(WEP) which is used to improve the compatibility with waterborne polyurethane and epoxy resin6002was obtained by using polyethylene glycol(PEG-1000) reacted with epoxy resin6002. WEP is a good surfactant, both hydrophilic and lipophilic, so when mixed with epoxy resin6002and WPU, the blending emulsion shows good stability. Discussed the effect of component content on the viscosity of emulsion, water resistance, solvent resistance of the film and mechanical properties of the adhesive. The result shows that compared with WPU curing system, the WPU/EP composite system has better performance of water resistance and solvent resistance. When WPU:WEP:6002:water is30:10:10:50, and the amount of curing agent XCT-802is30%of total mass, the maximum tensile shear strength reached12.11MPa. The composite has excellent integrated performances, and can be used as a kind of adhesives. In the present research, the waterborne polyurethane was mixed with acrylic emulsion. Discussed the effect of component content on the viscosity of emulsion, water resistance, solvent resistance, hardness, adhesion of the film, mechanical properties of the composite. The result shows that:the water resistance and the solvent resistance of the composite have been improved to some extent. When the content of acrylate emulsion is70parts or50parts, the hardness and the adhesion of the film achieved the best. When WPU:PA is30:70, and the amount of curing agent XCT-802is20%of total mass, the maximum tensile shear strength reached7.05MPa. The waterborne polyurethane composite show comprehensive properties, and have good application prospect especially in water-based paint areas.