Synthesis Of Polyurethane/Poly(Methylmethacrylate) Water Dispersion

Presently, with the rapid development of industry, people pay more attention to environment protection. Green Technology has played an important role in science development. On this occasion, waterborne coatings were born and have been the best way to reduce volatile organic compounds (VOC) in coatings. Water-borne acrylic and polyurethane emulsions have been used extensively as waterborne coatings independently. However, both emulsions are inferior to corresponding solvent-based counterparts. One of the approaches to develop water-borne emulsions with superior performances is to produce hybrid emulsion with a multi-phase structure in each emulsion particle. Polyurethane/Poly(methylmethacrylate) (PU/PMMA) water dispersion is studied in this thesis and it can be used for decorating high-grade wooden furniture.The process of emulsion polymerization in situ for PU/PMMA water dispersion has been used in the thesis. In the process , vinyl monomer is added into polyurethane prepolymer during the course of prepolymer neutralization. On the one hand, the monomer is used as organic solvent to decrease viscosity of the prepolymer and on the other hand, it can be mixed intensively with polyurethane prepolymer so that there would be the same urethane and acrylic molecular chains in each emulsion particle and be tangled tightly each other so that products with excellent performances are obtained. Two kinds of organic solvent, which have low boiling point and high boiling point separately, are used for deceasing viscosity of the system in the process. In addition, a small quantity of low-boiling point solvent in the emulsion is favorable to accelerating film drying. Higher reaction temperature may be maintained for the system with high boiling point solvent and reaction duration may be shortened. High boiling point solvent in the dispersion is helpful to enhance glossiness of film. The process has no need of desolventizing so the productive cost is reduced, efficiency is improved and pollution is abated.Polyurethane-monomer (PU-M) dispersions are synthesized by principal raw materials, such as toluene diisocyanate (TDI-80), polyether binary alcohol (N220), trimethylol propane(TMP), dimethylol propionic acid (DMPA) and methylmethacrylate (MMA). Some process factors, which include reaction temperature, raw material dehydration, feed mode, amount of agitation and so on, and some composition factors such as NCO/OH, TMP content, -COOH content, neutralization degree etc have been studied.