健康·安全·环境
第45卷第4期 2015年4月
涂料工业
PAINT & COATINGS INDUSTRY
Vol.45No.4 Apr.2015
基于水性聚氨酯端氨基测定的二次扩链研究刘娜，王武生，，马乃宇，张少朋，彭晓萌（安徽大学化学化工学院，合肥230601）
摘要：在准确测定水性聚氨酯分散体端氨基含量的基础上，采用二异氰酸酯对分散状态下的水性聚氨酯分散体进行二次扩链，研究了不同条件下二次扩链前后分散体端氨基含量、涂膜力学性能以及分散体粒径的变化。研究表明：二次扩链剂可以与水性聚氨酯分散体的端氨基反应：二次扩链可大幅度提高涂膜拉伸强度，面涂膜模量略有上升，说明反应形成扩链面非交联：扩链后分散体粒径略有增加，表明二次扩链不影响分散体稳定性。
关键词：水性聚氨酯：二次扩链：力学性能：平均粒径中图分类号：TQ630.1
文献标识码：A文章编号：0253-4312（2015）04-0042-06
ResearchonSecondaryChainExtensionProcessBasedon DeterminationofAminoEndGroupofAqueousPolyurethane
Liu Na,Wang Wusheng,Ma Naiyu,Zhang Shaopeng,Peng Xiaomeng(School of Chemistry and Chemical Engineering.Anhui Unirersity,Hefei 230601,China)
Abstract:based on the accurate determination of the amino end group of the aqueous poly urethane dispersion, the polyurethane was re-extended by using diisocyanate to increase its molecular weight. The amino end group content, film mechanical properties and particle size of aqueous polyurethane dispersion prepared under different condition were studied. The results showed that the secondary chain extender could react with the amino end group of aqueous pol-yurethane dispersion, moreover, the tensile strength of the cured film was significantly in creased while the film modulus and the particle size of aqueous polyurethane dispersions were slightly affected, indicating that the secondary chain extension process had no effect on the stability of the polyurethane dispersion.
Key Words: aqueous polyurethane; secondary chain extension; mechanical properties; average particle size
水性聚氨酯分散体以水作为分散介质，对环境无污染，符合可持续发展策略，其发展受到各国政府的鼓励。不管是采用丙酮法或预聚体分散法合成水性聚氢酯分散体，其配方中的异氰酸酯通常是过量的，而过量的异氰酸酯在分散后会与水反应，首先形成不稳定的氨基甲酸,不稳定的氨基甲酸分解形成氨基和二氧
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化碳，而后氨基再与另一个异氰酸酯反应形成脲[2 在水性聚氨酯分散过程中，由于加入大量的水，反应平衡被打破，然在第二步中氨基与另一个异氰酸酯反应为快反应，但第一步形成的氨基会受到聚合物分子链形成的“笼效应”限制，难以与另一个同样受“笼效应"限制的异氰酸酯发生碰撞反应[3]。