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利用异佛尔酮二异氰酸酯(IPDI)与聚乙二醇(PEG-6000)反应制备预聚体,以丙三醇和三羟甲基丙烷作为扩链剂,十六醇为封端剂,制备了星型结构的水性聚氨酯缔合型增稠剂(SHEUR)。采用FTIR和GPC对SHEUR分子结构进行了表征;利用黏度计和旋转流变仪对SHEUR水溶液的黏度、SHEUR对乳液增稠后的黏度以及SHEUR水溶液的流变性进行了分析,并与合成的线型结构水性聚氨酯缔合型增稠剂(LHEUR)进行对比,考察了不同结构的增稠剂分子对其增稠性能的影响。结果表明:SHEUR增稠效果比LHEUR好;向丙烯酸乳液中加入增稠剂的质量分数为1%时,以三羟甲基丙烷为扩链剂的SHEUR-a增稠后的黏度为61 440 m Pa·s,而以1,6-己二醇为扩链剂的LHEUR-b增稠后黏度仅为202 m Pa·s;低剪切时,SHEUR黏度维持在较高水平,剪切速率大于100 s-1后,SHEUR出现剪切变稀现象。对SHEUR流变性和乳液增稠后粒径的测定结果表明,所合成的SHEUR具有良好的触变性。
A prepolymer was prepared by the reaction of isophorone diisocyanate (IPDI) and polyethylene glycol (PEG-6000). Using glycerol and trimethylolpropane as chain extenders and cetyl alcohol as a capping agent, Star structure of the water-based polyurethane associative thickener (SHEUR). The molecular structure of SHEUR was characterized by FTIR and GPC. The viscosity of SHEUR aqueous solution, the viscosity of SHEUR after viscosifying SHEUR, and the rheological properties of SHEUR aqueous solution were analyzed by viscometer and rheometer. Structure of water-based polyurethane associative thickener (LHEUR) were compared to investigate the different structure of thickener molecules on the thickening properties. The results showed that the thickening effect of SHEUR was better than that of LHEUR. The viscosity of SHEUR-a thickened with trimethylolpropane as chain extender was 61 440 m when the mass fraction of thickener added to acrylic emulsion was 1% Pa · s, while the viscosity of LHEUR-b with 1,6-hexanediol as chain extender was only 202 mPa · s. At low shear, the SHEUR viscosity was maintained at a high level and the shear rate was greater than SHEUR appears shear thinning after 100 s-1. The SHEUR rheology and emulsion thickening particle size determination results show that the SHEUR synthesized has good thixotropy.