随着环保法规的日益严厉及用户对环境适应性产品的青睐，水性聚氨酯乳液的发展成为主流产品，它将溶剂型聚氨酯乳液的高性能和低挥发有机物（VOC）含量相结合，具有不燃、无毒、不污染环境、节省能源等优点。 本文选取可再生、来源广泛、价廉的蓖麻油作为聚氨酯的多元醇组分，采用预聚体法，引入DMPA，通过自身乳化，交联改性合成水性聚氨酯乳液。 首先，通过红外光谱、透射电镜表征合成的乳液。结果表明，原料完全反应并且得到水性聚氨酯乳液，颗粒形貌为近似球形结构，颗粒粒径较小，形成的乳液稳定性好。 其次，研究各种因素对水性聚氨酯乳液的影响。试验发现采用不同的制备方法、预聚温度、反应时间所得乳液性能差异较大；NCO/OH的摩尔比、DMPA含量、扩链剂结构与含量以及中和度的不同，都会对乳液及涂膜性能产生明显的影响，主要表现在乳液的稳定性，乳液的粒径、粘度的变化，胶膜的拉伸强度大小及耐水性能。一系列试验结果表明：采用一步法，反应温度控制在70℃左右，NCO/OH的摩尔比为1.0，DMPA含量达到7%，可以得到稳定的水性聚氨酯乳液。 最后，浅谈水性聚氨酯乳液在纸张涂布方面的应用。结果表明：涂布后的原纸，干抗张强度明显提高，耐水性能改善，满足市场要求的技术标准，为纸张涂布工业化提供了理论依据。

The environment regulation and the increasing concern of people’s environment protection are leading to the replacement of solvent-borne polyurethane. Waterborne polyurethane emulsion are popular because they are non-toxic, non-flammable and do not pollute air or water, at the same time, which can meet very demanding performance requirements. In this paper we choose especial structure, non-pollution and cheap of castor oil as polyol component of polyurethane. Waterborne polyurethane was prepared by the reaction of castor oil, dimethoxypionic(DMPA) and toluene diisocyanate(TDI). Based on the waterborne polyurethane we carried out the modification by cross chain reagent. Firstly, the structure of waterborne polyurethane was characterized by FI-IR and TEM. It’s found waterborne polyurethane was fully formed between castor oil and toluene diisocyanate. It was like ball, smaller particle size and very stable. Secondly, the synthesis techniques was full researched with a series of experiment test. The factors were considered, such as the method of preparation, the pretreatment to the raw materials and the temperature. The ratio of NCO/OH, content of DMPA, sorts and content of chain extender and neutralization content of TEA effect on the stabilities, particle size and viscosity of waterborne polyurethane emulsion, tensile strength and water resistance. Based on the comparison and analysis, we think the castor oil waterborne polyurethane has excellent film-forming property and good water resistance as 70～80℃ of temperature, 1.6 of NCO/OH ratios, 7% of DMPA content and 100% of neutralization content. Finally, we study on application of waterborne polyurethane emulsion to coating paper .It was found that the paper’s physical strength was enhanced, especially the wet strength and tensile strength, when the paper was treated. We obtained the optimal prescription and the reaction condition which provides the theories for paper coating industrialization