超支化聚酯改善聚酯粉末涂料表观性能的研究

采用硬脂酸对商业化的超支化聚酯(Blotorn H20)进行端基改性,提高其玻璃化转变温度(T_g),将其作为增大粉末涂膜表面张力和降低熔体黏度的助剂,以期达到减少涂膜表面缩孔和针孔,改善粉末涂料涂膜的表观性能的目的。运用红外光谱仪(FT-IR)、差式扫描量热分析系统(DSC)、旋转流变仪、接触角测量仪等方法进行了表征,研究表明硬脂酸封端Blotorn H20超支化聚酯(SA-HBP)的T_g升高到70℃,满足粉末涂料的贮存要求;与未加入SA-HBP的粉末涂料相比,加入SA-HBP后熔体黏度降低了20%～50%,表面接触角从100°降到80°,橘皮、针孔和缩孔等表面缺陷减少,同时物理机械性能如硬度、耐冲击性、附着力均有所改善。

The Study on Improvement of Appearance of Polyester Powder Coatings Modified with Hyperbranched Polyesters

The commercial hyperbranched polyester(Blotorn H20) was modified terminally with steric acid to increase its T_g,which was used as an additive to increase the surface tension of powder coating’s film and reduce the molten viscosity for elimination of cratering and pinhole and improvent of film appearance. The polyester powder coatings were characterized by FT - IR,DSC,rotational rheometer,and contact angle analysis(OCA).The T_g of the hyperbranched polyesters modified with steric acid was increased to 70℃, satisfying the requirement of storage of powder coatings.Compared to the unmodified powder coatings,incorporation of HBP,the molten viscosity can be reduced by 20%-50%,the contact angle from 100°down to 80°.The surface properties,such as orange,pinhole and cratering were improved.Meanwhile the mechanical properties of hardness,impact and adhesion were also improved.