Preparation And Properties Of Waterborne Two-component Acrylic Polyurethane,

With water as a carrier, waterborne two-component polyurethane (2k-WPU) provides room cure characteristics as well as low pollution and low energy consumption. It is inevitable for solvent two-component polyurethane to be replaced by 2k-WPU. Although some kinds of 2k-WPU are applied in some field abroad, there is still shortage in the theory research. Many researches need to be worked extensively and steeply in order to give a insight to the effect of composition, preparation and curing condition on properties of 2k-WPU.2k-WPU is composed of polyols and polyisocyanates. Many properties of 2k-WPU are affected by polyols, such as water dispersibility of polyisocyanates, diffusion and curing of molecular chains, and properties of films. There are many kinds of polymer polyols and its preparation method, in which acrylic polyols have the advantage of adjustable molecular weight, Tg and hydroxyl value. By different polymeric technology, acrylic emulsion and acrylic dispersion can be achieved. So, acrylic polyols are suited for us to study on 2k-WPU.The reaction between -NCO and water, dispersion of polyisocyanates in polyols, and complete diffusion among different kinds of molecules are key problems to be solved in 2k-WPU. In this dicsertation, acrylic polyols, including water- soluble acrylic resin (hs-WA), hydroxyl acrylic emulsion and hydroxyl acrylic emulsion with microgel as core (Si-PHA), were prepared first. Then two kinds of 2k-WPU comprised of hs-WA/HDI biuret and Si-PHA/ hydrophilically modified polyisocyanates(2336) were prepared. The factors affecting dispersion and curing were investigated systematically. The structures and properties of emulsion and film of 2k-WPU were also characterized in this thesis.The factors affecting viscosity and water-soluble performance of hs-WA with low acid values were discussed. The effect of solvent polarity and hydroxyl values on phase inversion of hs-WA was investigated. With TEM and particle size analyzer, the particle pattern and the variation of particle size were characterized. The results show that viscosity of hs-WA is affected...