Waterborne polyurethane dispersion and preparation method thereof

The invention discloses a waterborne polyurethane dispersion and a preparation method thereof. The preparation method of the waterborne polyurethane dispersion comprises the following steps: adding a certain amount of amine chain extender containing two secondary amino groups and/or water in a pre-polymerization stage to form urea bonds, then adding # imgabs0 # end-capping reagent in a chain extension end-capping stage, and finally dispersing to form the waterborne polyurethane dispersion. Compared with the prior art, the waterborne polyurethane dispersion has the advantages that a small amount of urea bonds are inserted in a soft segment and a carbamate chain segment, and the tail end of a molecular chain contains part of amido bonds, so that the viscosity, strength and heat resistance of resin can be greatly improved. 本发明公开一种水性聚氨酯分散体及其制备方法。该水性聚氨酯分散体的制备，是在预聚阶段加入一定量的含有两个仲氨基的胺类扩链剂和/或水以形成脲键，然后在扩链封端阶段加入#imgabs0#封端剂，最后分散形成水性聚氨酯分散体。与现有技术相比，本发明的水性聚氨酯分散体在软段和氨基甲酸酯链段中穿插少量脲键，同时分子链末端含有部分酰胺键，可以大幅度提升树脂的粘性、强度及耐热性。