单组份自交联聚氨酯-聚丙烯酸酯/硅溶胶水基涂料结构设计与成膜性能控制

In-situ mini-emulsion polymerization has become the main method and research hotspot to prepare polyurethane-polyacrylate (PUA) emulsion without volatile organic compounds (VOC). However, certain amount of small molecule emulsifier was indispensable in this system, and the cross-linking degree was too low to guarantee the solvent resistance and scratch resistance of coatings, which was inferior to the properties of solvent-based coating. In this project, vinyl monomers of different characteristics were adopted to replace organic solvent, and high solid content and multi-crosslinking PUA microemulsions without VOC were prepared by in-situ surfactant-free emulsion polymerization with the assistance of reactive surfmer. The stability mechamism and in-situ surfactant-free polymerization mechanism of PUA microemulsions were elucidated. The equilibrium between the surface activity and crosslinking degree was effectively coordinated by controlling the content and distribution of surfmer and reactive groups in the PUA chains. In addition, the grafting and crosslinking mechanisms between polyurethane and polyacrylate were studied, as well as the curing kinetics of PUA system. The compatibility and phase behavior of this multicomponent system were also investigated. Furthermore, the relationships between the microstructure of colloidal particles, interfacial characteristic and interactions among colloidal particles and the properties of the emulsion films were cooperatively controlled. Effects of the connection mode of silica sol in PUA system on the interfacial characteristic and coating performance of PUA nanocomposite coating were explicated. Organic-inorganic three dimensional interpenetrating networks with high strength can be formed among silica sol, polyurethane and polyacrylate chains. The resulting waterborne nanocomposite coatings are able to gain comparable properties with solvent-based coating.

原位乳液聚合法作为制备无VOC聚氨酯-聚丙烯酸酯（PUA）乳液的主导方法和研究热点，需添加适量小分子乳化剂；加之交联度较低，导致其涂层耐溶剂性和耐刻划性仍与溶剂型涂料有差距。本项目以不同特性的乙烯基单体替代有机溶剂，在反应性表面活性单体作用下，采用原位无皂乳液聚合法制备系列多重交联的高固含量PUA微乳液，阐明PUA微乳液的稳定机制及原位无皂乳液聚合机理。通过控制分子链上表面活性单体、反应性基团的含量和分布，有效协调体系的表面活性和交联度。研究聚氨酯与聚丙烯酸酯之间的接枝和交联反应机理、固化动力学；分析多组分体系的相容性和相行为；协调控制乳胶粒微观形态、胶粒间界面特征及相互作用与胶膜性能关系；明确硅溶胶的引入方式和键接方式对PUA纳米复合涂层的相界面特征、涂层性能的控制，硅溶胶可与聚氨酯、聚丙烯酸酯分子链间形成高强度的有机-无机三维互穿网络结构，达到与溶剂型涂料相媲美的性能。

水性木器涂层作为木器涂层行业的新兴产品，最大的特点是以水代替有机溶剂作为溶剂或分散介质，节约了大量的石油化工资源，以水为溶剂，价格低廉，使用方便，大大减少了涂层中有机溶剂挥发对大气的污染和施工过程的火灾危险。由于其本身具有环保、节能、安全三大优势，已经有逐步取代溶剂型涂层的趋势。. 本课题组采用原位无皂乳液聚合法，在不使用有机溶剂、无外加乳化剂的情况下，依靠WPU分子链的自乳化性和反应表面活性单体的作用，制备水基高固含量的交联改性聚氨酯-聚丙烯酸酯（IPUA）。此制备方法能够有效抑制PA在水相中的二次成核，显著提升复合体系的相容性。由此促进聚氨酯（PU）较好的机械性能、优异的抗寒性、温度变化对软硬度影响小、耐有机溶剂等优点与聚丙烯酸酯（PA）的机械强度高、耐老化、耐光不变黄、耐水性好等优点的结合。本课题组从三个方面进行了研究：（1）确立反应性表面活性单体作用下高固含量聚氨酯-聚丙烯酸酯（IPUA）微乳液的原位无皂乳液聚合机理；系统研究了反应性表面活性单体对IPUA微乳液、乳胶膜以及涂层性能的影响。（2）通过化学键接的方式分别于聚氨酯和聚丙烯酸酯分子链上引进含量和分布可控的有机硅氧烷、环氧、酮肼交联等反应性基团，分别制得了有机硅交联改性聚氨酯-聚丙烯酸酯（IPUASi）、有机硅-环氧改性聚氨酯-聚丙烯酸酯（IPUASiE）和有机硅-酮肼交联改性聚氨酯-聚丙烯酸酯（IPUASiKH）；并于体系中引入硅溶胶或改性硅溶胶，制备有机-无机纳米复合涂层。系统反应性基团的含量及分布对IPUA微乳液、乳胶膜和涂层性能的影响。（3）综合平衡产品配方，并通过多次中试、大试试验得到高性价比产品，取得实践应用和理论创新的多项成果，实现产品的产业化，促进其在水性涂层领域的应用，基本解决目前溶剂型聚氨酯涂料所带来的环境污染、成本高等系列问题。从理论和应用两大角度对其进行深入系统的研究，通过理论科学研究推出方向性的科研成果和理念。