| Waterborne polyurethane paints possess innoxious, odorless, no-harm to the environment and safe characteristic, and now are replacing traditional solvent-based paint. Two-component waterborne polyurethane paint which has almost sane properties with solvent-based paint, has attracted much interest in the world. In this paper, three kinds of hydroxyl component are prepared for two-component waterborne polyurethane paint, that is, acrylic dispersion, acrylic emulsion and silicone-modified acrylic emulsion. The influence of the composites of these dispersion and emulsions on polymerization process, viscosity, particle size and coagulum are investigated, infrared spectroscopy (IR), inductance coupling plasma (ICP), transmission electron microscopy (TEM) and thermogravimetric analysis (TG) are used to characterized their structure, composite, morphology and thermal stability, respectively. Combined with hydrophilically-modified polyisocyanate at proper NCO/OH ratio, two-component waterborne polyurethane paints are prepared from these dispersion and emulsions, the film properties of these paints are studied from varying their composites and ratio, surface morphology and molecular structure of these films are observed with scanning electron microscopy (SEM) and IR spectroscopy. Moreover, nano-scale SiO2 particle is as seed, styrene-acrylate-acrylic acid emulsion polymerization and soapless acrylic emulsion are studied from varying the level of SiO2 particle and reaction temperature, particle size of these emulsions are determined and SiO2 content of participating polymerization is also determined. Kinetic study is carried out in the presence of nano-scale SiO2 particle. From these experiments we may come into these conclusions:(1). When the acrylic resin containing hydroxyl groups is dissolved in water, its behavior has some difference with same resin without hydroxyl groups, that viscosity decrease in early dissolve stage does not exist, when water is added further, there is aincrease peak in viscosity and then decreased sharply. The more hydroxyl-group, the lower in early viscosity, and the higher in final viscosity. An increase in acid value, hydroxyl value and neutralization degree lead to increase in water-solubility.(2). In emulsion polymerization system with more level of hydrophilic monomer, such as hydroxylethyl methacrylate, it is difficult to obtain stable pre-emulsification mixture, so the monomer mixture has to be added directly. Because of its high hydrophilelipophile balance (HLB), emulsifier with more HLB is needed. When the sodium lauryl sulfate (SLS) and p-octyl polyethylene glycol phenyl ether (OP) is used and its level in 3% and 6:4 ratio, the polymerization process has the lowest coagulum and the highest monomer conversion. Higher reaction temperature and more level hydroxyl value lead to more coagulum, the latter also lead to larger particle size. The acid value has larger influence on viscosity and coagulum, there exist a best range. The emulsion particle size is larger for its hydrophilicity, most of its particles are connected together.(3). Optimum reaction condition for silicon-modified acrylic emulsion is determined from matrix experiment according to coagulum, the results are as follows: SLS/OP as mixed emulsifiers, its level at 2% with ratio 4/6, the level of acrylic acid and vinyl trimethoxyl silicane(VTMS) is all 1.5%, and VTMS is added in late stage of polymerization, in this situation the system has the lowest coagulum. When the hydroxyl value of such polymer increases, the coagulum decreases; and solid content of such polymer increases, the coagulum increases greatly, so it is difficult to get higher solid content emulsion. ICP results indicate that almost all of VTMS participated the polymerization. The particle size of silicon-modified acrylic emulsion is smaller than that unmodified emulsion. More level of VTMS increases the thermal temperature of such polymer.(4). The particle size of emulsifier-free emulsion is larger than the emulsion with emulsifier, and has...
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