【作者】 郭强；

【导师】 梁国正；

【作者基本信息】 苏州大学 ， 材料工程（专业学位）， 2020， 硕士

【摘要】 Zn0压敏电阻是指一种电阻值随电压而变化的电子元器件,其外包封层使用了环氧粉末涂料,起到防潮、绝缘、阻燃等作用。压敏电阻长期放入湿热环境下,外层的环氧粉末涂料会因吸潮,对压敏电阻的电性能产生很大的影响。因此,制备出防潮性能优异的环氧粉末涂料,在压敏电阻实际应用中意义重大,本课题就是围绕这个主题而展开。首先,我们使用实验室双螺杆挤出机及相关设备,制备了应用于ZnO压敏电阻的环氧粉末涂料,主要测试评估了三种环氧树脂固化体系:酸酐固化体系、酚类固化体系、双氰胺固化体系。通过DSC对制备的配方做了不同升温温度速率(5℃/min、10℃/min、15℃/min、20℃/min)的动态分析,确定了三种环氧固化体系均可以满足ZnO压敏电阻的标准固化要求(150℃/1H)。其次,我们用制得的三种环氧固化体系的粉末涂料涂装在ZnO压敏电阻上,在150℃/1H完成固化,并使用DSC确认了涂膜的固化度固化完全。然后,使用高温高压蒸煮法,评估了三个环氧固化体系应用在ZnO压敏电阻的防潮性能。研究发现,三个环氧固化体系中,酸酐固化体系具有最优异的防潮性能,酚类固化体系次之,双氰胺固化体系最差。酸酐固化体系在蒸煮12H之后,压敏电压和漏电流参数基本没有变化,可满足ZnO压敏电阻的耐湿热要求。而酚类固化体系和双氰胺固化体系蒸煮后压敏电压和漏电流参数变化很大,不能满足ZnO压敏电阻的耐湿热要求。我们通过吸水率、红外、扫描电镜、干/湿附着力测试分析了影响环氧粉末涂料防潮性能的因素,发现涂膜湿态附着力越好其防潮性能越优异,涂膜湿态附着力可能是影响压敏电阻环氧涂膜防潮性的主要原因。更多还原

【Abstract】 ZnO varistor refers to an electronic component whose resistance changes with voltage,which is coated by epoxy powder coating.Epoxy powder coating protects varistor and has some functions as humidity resistance,insulation and flame resistance,etc.Therefore,the preparation of epoxy powder coatings with excellent humidity resistance performance is significantly important for varistor industry,this is the subject of this thesis.Firstly,epoxy powder coatings for ZnO varistor were prepared by laboratory twin-screw extruder and related equipments.Three epoxy resin curing systems were evaluated:anhydride curing system,phenolic curing system,dicyandiamide curing system.Dynamic analysis of the prepared formulas at different heating temperature rates(5℃/min、10℃/min、15℃/min、20℃/min)was measured by DSC.It was determined that all three epoxy curing systems can meet the standard curing requirement of ZnO varistor(150 0 C/1H).Secondly,We coated three curing systems powder coatings on ZnO varistors and cured at 150℃/1H,and confirmed curing degree of films using DSC.Then,the high pressure and temperature cooking test was used to evaluate humidity resistance performance of three epoxy curing systems applied on ZnO varistor.Among them,acid anhydride curing system has the best moisture resistance,phenol curing system is the second,and dicyandiamide curing system is the worst.After 12H high pressure and temperature cooking test,acid anhydride curing system can meet the humidity resistance requirement of the ZnO varistor.However,phenolic curing system and the dicyandiamide curing system can not meet the requirement of humidity resistance performance for varistor.The factors affecting the humidity resistance of epoxy powder were analyzed through water absorption test,IR,SEM,and dry/wet adhesion test.It was found that the better the wet adhesion of the coating film,the better the umidity resistance.The wet adhesion of the coating film may be the main reason affecting the umidity resistance of epoxy coating film on ZnO varistor.更多还原