改性聚酯涂层的制备及在食品包装材料中的应用

Preparation of Modified Polyester Coating and Its Application in Food Packaging Materials

目的制备改性聚酯涂层,解决纯聚酯涂层与基材润湿性较差,导致涂层出现附着力差、缩孔等问题,获得综合性能优异的镀锡板食品包装用新型涂层材料。方法以二元酸、二元醇为原料,通过缩合聚合方法合成聚酯树脂,用双酚F型环氧树脂化学改性聚酯树脂,制备环氧改性聚酯树脂,并用氨基硅烷作为固化剂构筑硅烷化环氧改性聚酯涂层。通过GPC、FTIR、TGA、OM、WCA、附着力等分析、考察硅烷化环氧改性聚酯树脂涂层与常规氨基树脂固化环氧改性聚酯涂层的性能差异。结果通过性能对比发现,树脂与硅烷固化剂质量比为3∶1时,mEster 1.0和mEster 1.1涂层样品综合性能最佳,涂层在镀锡板基材表面润湿性好,缩孔等缺陷少,耐水煮性好,铅笔硬度为2H,丙酮擦拭50次后表面仍完好,分解温度在250℃以上。结论硅烷化环氧改性聚酯树脂涂层中低表面自由能的Si−O−Si键对其性能提升有关键作用,该涂层可应用于镀锡板等金属基材食品包装保护材料。

The modified polyester coating is prepared to solve the problems of poor adhesion and shrinkage between the pure polyester coating and the substrate due to poor wettability,so as to obtain a new coating material for tinplate food packaging with excellent comprehensive performance.In this work,diacid and dialcohol were used as raw materials to synthesize polyester resin through the condensation polymerization method.Then the bisphenol F epoxy resin was used to modify the synthesis of polyester to prepare epoxy modified polyester resin,which was then cured with amine silane as the curing agent.The performance differences between silylated epoxy modified polyester resin coatings and epoxy mod-ified polyester coatings cured with conventional amino resin were characterized by GPC,FTIR,TGA,OM,WCA and ad-hesion analysis.Through performance comparison,it is found that the dosage ratio of silane curing agent is 3∶1,mEster 1.0 and mEster 1.1 have the best performance.The coatings have good wettability on the tinplate substrate,less shrinkage cavity or other defects,good water boiling resistance,good pencil hardness of 2H,and the surface is still intact after wiped with acetone for 50 times.Meanwhile,the decomposition temperature is above 250℃.The silylated epoxy mod-ified polyester coatings contains Si−O−Si bond,which is conductive to the excellent performance of the coatings.The coatings can be applied in food packaging materials of tinplate or other metal substrates.