低温固化高流平粉末涂料用超支化改性聚酯树脂的研究

Study on Hyperbranched Modified Polyester Resin for Powder Coatings with Low Temperature Curing and High Leveling Properties

为解决低温固化粉末涂料因固化温度低、树脂流动性差、固化反应不完全导致的涂层流平性和力学性能较差的问题,引入超支化树脂对聚酯树脂结构进行改性,进而提升其综合性能。使用硬脂酸(SA)和苯甲酸(BA)对超支化树脂进行部分封端,合成了具有适宜反应活性的超支化树脂;研究了不同合成工艺对超支化改性聚酯树脂及其粉末涂料性能的影响,并通过调整固化促进剂,进一步提升涂层的综合性能。结果表明:在酯化阶段加入5%超支化树脂,固化促进剂a与固化剂促进剂b复配质量比为5∶2,且总用量为0.14%时,制备的超支化改性聚酯树脂,粉末涂层的倾斜流动性能达到91 mm,50 cm正反冲击均能通过,具有优异的流平性和耐冲击性。

To address the issues of low-temperature curing powder coatings,such as low curing temperature,poor resin fluidity and incomplete curing reaction resulting in weak leveling and mechanical properties of the coating,this paper proposed the use of hyperbranched resin to modify the polyester resin structure for enhanced overall performance.The synthesis of a hyperbranched resin with appropriate reactivity was achieved by partially blocking the hyperbranched resin using stearic acid(SA)and benzoic acid(BA).The impact of different synthesis processes on the properties of modified polyester resin with hyperbranched structure and its powder coatings was investigated,while further enhancement of the comprehensive coatings properties was achieved through adjustment of the curing promoter.The results showed that the addition of 5%hyperbranching resin during the esterification stage resulted in a curing promoter a to curing agent promoter b ratio of 5∶2,with a total dosage of 0.14%.The oblique flow energy of the powder coating reached 91 mm,and all of them could pass the impact test at 50 cm height,which showed excellent leveling and impact resistance.