【作者】 刘景芳；

【导师】 李树材；

【作者基本信息】 天津科技大学 ， 材料加工工程， 2004， 硕士

【摘要】 水性聚氨酯是以水为分散介质的二元胶体体系，与溶剂型聚氨酯相比具有无毒、不易燃烧、不污染环境等优点，已被广泛应用于皮革涂饰、汽车涂装、纤维处理、造纸工业助剂、涂料和粘合剂等领域。 本课题采用阴离子自乳化法引入亲水基团DMPA合成了稳定的聚氨酯乳液。在前人研究工作的基础上进一步探讨了水性聚氨酯的物理结构与性能的关系，并对其进行了封闭改性的初步尝试。研究表明：聚氨酯分子链中作为软段的聚合物多元醇结构不同，其乳液粘度、粒径、膜的耐水性、硬度、和拉伸强度也不同。这主要与软段的柔顺性及软段中是否带有侧基有关；提高-NCO／-OH摩尔比、增加DMPA和小分子扩链剂用量均使聚氨酯分子链中硬段含量增加，膜的拉伸强度提高，断裂伸长率降低；通过对未封闭体系动态力学性能的研究发现聚氨酯分子链中硬段含量的提高，导致聚氨酯软段的玻璃化温度(Tg)升高，软硬段相分离程度降低；扩链剂的结构、用量及复配方法对乳液及膜性能有影响，乙二胺扩链比醇类扩链综合性能优良。此外，反离子种类和用量也对聚氨酯乳液粒径、粘度和膜力学性能有影响。 通过对封闭改性体系的研究发现：封闭后的聚氨酯比未封闭的聚氨酯乳液稳定性提高；封闭剂结构不同其解封温度不同(解封温度用DSC法可确定)，而且封闭剂的结构对乳液粒径、外观、稳定性也有影响；封闭固化后的膜在耐水性、硬度等方面均优于未封闭固化的膜。更多还原

【Abstract】 A water-borne polyurethane (WPU) is defined as a binary colloidal system in which PU particles are dispersed in a continuous aqueous medium. In contrast to the solvent-borne polyurethane, the water-borne polyurethane have advantages of being free from toxicity and pollution etc., which thus was steadily expanded its application in textile coatings, sizing and adhesives for numbers of polymeric materials, leather surface etc..In this paper, the stable aqueous polyurethane was prepared based on anionic self-emulsified process, incorporated dimethylol propionic acid (DMPA) into the prepolymer backbone. The structure-property relations of WPU were further discussed and blocking modification was primarily researched. The results showed that firstly, the different structures of polyesterols resulted in different properties of PU, such as particle size, viscosity of emulsions, tensile strength of films. Secondly, the study on the dynamic mechanics properties of unblocked systems showed that the glass transition temperature (Tg) of the soft-segments rose and the phrase compatibility of soft- and hard-segments was improved when the contents of hard-segments increased by elevating the ratio of -NCO/-OH and the dosages of DMPA and extender. Thirdly, the influences of the structure, dosage and mix of chain extenders on the properties of emulsions & films were studied. The results indicated that the emulsion extended with ethylene diamine (EDA) had better properties than that of the emulsion extended with diols. Moreover, the counter-ion worked strong effects on the physical properties of PU.In addition, it was found from the investigation of the blocked system that the storage stability of blocked PU emulsions was improved, different blocking agents resulted in different deblocking temperatures (the deblocking temperatures were determined by Differential Scanning Calorimeter, DSC) and the post-curing films were better than uncured films in both aspects of hardness & water-resistance.更多还原