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采用二级扩链技术 ,合成了同时具备阴离子型和非离子型大分子链结构的水性聚氨酯分散液 .以红外光谱技术 ,就预聚反应时间和温度对反应程度的影响进行了表征 ,认为当初始合成温度为 70℃时 ,以丁酮为稀释剂、DMPA为离子型亲水单体、乙二醇为一级扩链剂、三乙胺为中和剂、三乙烯四胺为二级扩链剂 ,控制nNCO/nOH=1.3,预聚反应 5h ,扩链反应 2～ 4h ,可获得具有良好稳定性的水性聚氨酯分散液 .采用XRD、DSC等技术 ,研究了亲水链段PEG分子量对水性聚氨酯浇铸膜结晶性的影响 ,证实了所合成的水性PU结晶形态属于单斜晶系 ,且软链段结晶致密程度随PEG分子量的增大而增加
An aqueous polyurethane dispersion with both anionic and non-ionic macromolecular chains was synthesized by a two-stage chain-extension technique.The effect of prepolymerization reaction time and temperature on the reaction degree was characterized by infrared spectroscopy When initial synthesis temperature was 70 ℃, butanone was used as a diluent, DMPA was an ionic hydrophilic monomer, ethylene glycol was the first chain extender, triethylamine was a neutralizer, and triethylenetetramine was secondary expansion Chain agent, nNCO / nOH = 1.3, prepolymerization reaction for 5h and chain extension reaction for 2 ~ 4h to obtain a water-based polyurethane dispersion with good stability.METHODS The molecular weight of PEG The results show that the crystalline form of aqueous PU synthesized belongs to the monoclinic system and the density of the soft segments increases with the increase of PEG molecular weight