扩链剂对水性聚氨酯和聚脲的性能的影响

Influence of Chain Extenders on Performance of Aqueous Polyurethane and Polyurea

聚氨酯和聚脲乳液是以二月桂酸二丁基锡作催化剂 ,由 2 ,4或 2 ,6 -甲苯二异氰酸酯、聚丙二醇、二羟甲基丙酸在 75～ 80℃下反应 3h合成的。用联氨或乙二胺作扩链剂生成聚脲 ,用乙二醇生成聚氨酯。以联氨或乙二胺扩链时 ,预聚物的分散在扩链反应前进行 ;以乙二醇扩链时则相反。丙酮在分散过程中的效果不明显。测定了不同软段和—NCO/—OH比值下 ,膜的力学性能、在木材表面的涂层特性以及附着力。

The title polyurethane and polyurea emulsions have been prepared by reaction of 2,4 or 2,6-toluene diisocyanate (TDI), polypropylene glycol (PPG) and dimethylol propionic acid (DMPA), at 75～80 ℃ for 3 h at the present of catalyst of dibutyltin dilaurate (DBTDL). The chain extender hydrazine (HYD) and ethylene diamine (EDA) are used for polyurea; and ethylene glycol is used for polyurethane. The dispersion of prepolymer should be done before the chain extension reaction when using extenders of HYD or EDA, but on the contrary, when using EG chain extender, the dispersion should be done after chain extension reaction. The acetone shows less influence during the dispersion process. The mechanical properties of the film, coatings features and adhesion on wood substrates at various soft segments, and different NCO/OH ratio are determined.