Preparation And Characterization Of Green Waterborne Polyurethane

The polyurethane adhesives that can be found in the market are mostly organic solvent-based product, but the organic solvent used in these traditional polyurethane preparation process are both toxic and flammable, may endanger people’s life and the natural environment. With the development of science and technology, people realized that the traditional solvent-based polyurethane in the future will be subject to severe impact, therefore developed a high-quality, non-polluting,low-cost environmentally friendly aqueous-based polyurethane system has been generally concern.Waterborne polyurethane can dispersed in water instead of solvent. However, during the preparation of the waterborn polyurethane, acetone or other solvents are alse needed to disperse the macromolecular chains of polyurethane. In order to implement green-environmentally polyurethane production process, methyl methacrylate(MMA) are used and substituted acetone as the solvent. Acrylic terminated polyurethane structure is designed to link double bone of MMA in the final stage of polymerization, so as to achieve the requirement of non-solvent production process. we focus on wether the structure of waterborne polyurethane would affect its performance.In the chapter two, polyether polyurethane were firstly prepared by polyether polyols, isophorone diisocyanate, 2,2-dihydroxypropyl acid(DMPA,as hydrophilic chain extender), followed by addition of a small molecule chain extender, and finally acrylation by hydroxyethyl methacrylate(HEMA). After discussion and studies, we found that the polyether waterborne polyurethane emulsion had poor mechanical properties and bad solvent resistance, the emulsion can hardly be dried quickly under a heat with poor film quality.In the chapter three, in order to improve the mechanical properties of waterborne polyurethane, polyester polyol, isophorone diisocyanate, 2,2-hydroxybutyl carboxylic acid(DMBA) were chosed to form a prepolymer, after extending chain of polymer, terminating with HEMA, neutralizing, emulsifying and other steps, a stable waterborn polyester polyurethane was born. Expecially, Glycidyl methacrylate was added into system to strengthen the degree of crosslinking and increase the strength of waterborn polyurethane. Finally the stable aqueous polyurethane emulsion was obtained. A series of characterization and analysis of waterborne polyurethane dispersions were obtained by IR, solid content, hardness, tensile strength of adhesion and film characterizations, when the mole ratio of polyester polyol, IPDI, DMBA, BDO, HEMA was 1: 2.25: 0.5: 0.25: 1, the performance of waterborne polyurethane emulsion was more stable, with solid content of 38.898%, the pencil hardness of H, adhesion of 0, the tensile strength of 2.457 MPa, elongation at break to 595%, water absorption of 6.09%. It was clear that the addition of GMA did improve the polyurethane’s degree of crosslinking, and the hardness and tensile strength of waterborne polyurethane were significantly improved.