耐水性水性聚氨酯的合成与性能研究

发布时间：2018-02-16 17:08

本文关键词： 水性聚氨酯乳化剂内外协同耐水性　出处：《北京化工大学》2016年硕士论文　论文类型：学位论文

【摘要】：水性聚氨酯(WPU)是一种以水作为分散介质的聚氨酯乳液体系,相比于传统的、以有机溶剂作为分散介质的聚氨酯材料,WPU具有绿色无污染、安全可靠的优点,因此具有广阔的发展前景。但是,以水作为分散介质,致使WPU胶膜的耐水性能下降,限制了WPU材料在各领域的应用。因此,明确水性聚氨酯结构与性能的关系,采用切实可行的新工艺、新方法,提高水性聚氨酯的耐水性,有助于拓展水性聚氨酯的应用领域,改善聚氨酯材料生产和应用环境。本文首先用自乳化法制备出IPDI型水性聚氨酯,探究了聚氨酯预聚体合成工艺对WPU的乳液性能及其所制得胶膜的耐水性与力学性能的影响,明确了水性聚氨酯结构及其性能之间的关系。通过预聚体的不同合成工艺研究,发现一步法合成时,制备的聚氨酯预聚体,乳化容易,乳化后可得到性能良好的聚氨酯乳液,同时胶膜的耐水性和力学性能优良。然后通过一步法合成预聚体,研究了软段含量、亲水扩链剂加入量和后扩链剂加入量对乳液和胶膜性能的影响,研究发现,当Ri=2.5-3.5, DMBA加入量为3.5%-4.7%,DETA的加入量为100%时,可制得综合性能优异的IPDI型水性聚氨酯。其次,通过在水性聚氨酯的制备过程中加入高分子乳化剂,利用内外协同效应可以制备耐水性较强的水性聚氨酯,探究了不同的内外乳化剂比例以及乳化时间对胶膜耐水性的影响,研究发现当R1值为2.5,内乳化剂添加量为3.6%,外乳化剂的添加量为0.5%,外乳化剂反应时间为10min,DETA的加入量为100%时,可获得耐水性较好的胶膜,此时吸水率为4.1%,具有优于传统内乳化法同等条件下制备的WPU材料的吸水率(为19.2%)。并对最优耐水性配比下的聚氨酯材料的基本性能进行了表征,发现此时胶膜的的力学性能及热性能较传统内乳化型胶膜的性能基本无变化。最后,探究了内外协同乳化法提高WPU耐水性的机理,原因可能有两方面,一是外乳化剂的加入改善了水性聚氨酯的乳液性能,胶粒的粒径降低,成膜时胶粒融合紧密,成膜后空隙较少,水分子难以侵入胶膜内部,使胶膜耐水性提高；二是外乳化剂在胶膜干燥的过程中,会在表面能的驱使下运动到胶膜表面,对表面亲水基团进行包埋,使胶膜表面与小水珠的接触角增大,降低表面张力。
[Abstract]:Waterborne polyurethane (WPU) is a kind of polyurethane emulsion system with water as the dispersing medium. Compared with the traditional polyurethane material with organic solvent as the dispersing medium, WPU has the advantages of green, pollution-free, safe and reliable. Therefore, there is a broad prospect for development. However, the water resistance of WPU film decreases due to the use of water as dispersing medium, which limits the application of WPU materials in various fields. Therefore, the relationship between the structure and properties of waterborne polyurethane is clarified. It is helpful to expand the application field of waterborne polyurethane by adopting feasible new process and new method to improve the water resistance of waterborne polyurethane. In this paper, IPDI type waterborne polyurethane was prepared by self-emulsifying method. The effects of polyurethane prepolymer synthesis process on the emulsion properties of WPU and the water resistance and mechanical properties of the film were investigated. The relationship between the structure and properties of waterborne polyurethane was clarified. Through the study of the different synthesis process of the prepolymer, it was found that the polyurethane prepolymer prepared by one-step synthesis was easy to emulsify, and the polyurethane emulsion with good properties could be obtained after emulsification. The effects of the content of soft segment, the amount of hydrophilic chain extender and the amount of chain extender on the properties of emulsion and film were studied. When the content of DMBA is 3.5- 4.7DETA and the amount of DMBA is 3.5-4.7DETA, the waterborne polyurethane with excellent comprehensive properties can be prepared. Secondly, by adding polymer emulsifier in the preparation of waterborne polyurethane, Waterborne polyurethane with strong water resistance can be prepared by using internal and external synergistic effect. The effects of different internal and external emulsifier ratio and emulsifying time on the water resistance of the film were investigated. It was found that when the R1 value was 2.5, the amount of internal emulsifier was 3.6, the amount of external emulsifier was 0.5, and the addition of external emulsifier was 100 minutes, the film with better water resistance could be obtained. The water absorbency is 4.1, which is better than that of WPU prepared under the same conditions by traditional internal emulsification (19.2g). The basic properties of polyurethane under the optimum water-resistance ratio are characterized. It was found that the mechanical and thermal properties of the film had no change compared with that of the traditional internal emulsified film. Finally, the mechanism of internal and external synergistic emulsification to improve the water resistance of WPU was explored, which may be due to two reasons. One is that the addition of external emulsifier improves the emulsion performance of waterborne polyurethane, the particle size decreases, the particles are fused tightly, the void after film formation is less, water molecules are difficult to invade the film interior, and the water resistance of the film is improved. The other is that the external emulsifier will move to the surface of the film under the drive of the surface energy during the drying process of the film, and embed the hydrophilic group on the surface, so as to increase the contact angle between the surface of the film and the small water droplets and reduce the surface tension.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O633.14;O648.23

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