紫外光固化超支化聚酯的合成及性能

Synthesis and Properties of UV-curable Hyperbranched Polyester

以季戊四醇为核,2,2-羟甲基丙酸为臂,采用熔融缩聚法合成并表征了末端含大量羟基的超支化聚酯,其支化度高,黏度低,具有良好的热稳定性.以甲基丙烯酸酐改性超支化聚酯,得到链末端含有C=C的超支化甲基丙烯酸酯,在最佳反应条件下改性反应的转化率可达89%以上.改性后的超支化聚酯表现出更低的黏度,热失重曲线呈现为两段,玻璃态转化温度(Tg)降低.低黏度的超支化甲基丙烯酸酯应用于紫外光固化金属涂料,稀释剂用量少,成膜速率快,固化完全.探讨了含有不同数量C=C的超支化聚酯对光固化膜性能包括凝胶率、附着力、冲击强度、柔韧性、硬度及耐溶剂性能的影响.随C=C含量的提高,凝胶率增大,膜机械性能及耐溶剂性变化明显.实验表明,选择具有不同活性基团数量的超支化聚酯,有利于得到综合性能优异的紫外光固化材料.

Using the molten polycondensation,the second to fourth generation of hyperbranched polyesters with a great number of hydroxyl groups were synthesized and characterized based on the pentaerythritol as core and 2,2-bis（hydroxymethyl） propionic acid as arm.They had high branched degrees,low viscosity and good thermal stability.By methacryloyl anhydride,the hyperbranched polyesters were modified to be the hyperbranched methacrylates with C=C at the chain ends.The percent conversion could be reached above 89% under the optimum reaction conditions.The modified hyperbranched polyesters exhibited lower viscos-ity,two segmental thermogravimetric curve and lower glass transition temperature（Tg）.When the hyper-branched methacrylates with low viscosity were applied in UV-curable coating for metals,it could take less solvent,fast coating speed and complete curing.The effects which the hyperbranched polyesters with dif-ferent C=C contents took on the properties of UV-curable coating such as gel content,adhesive strength,impact strength,flexibility,hardness and the solvent resistances were studied.With the improvement of C=C contents,the gel contents were increased.Also the mechanical properties and solvent resistances of coat-ings were changed significantly.The experiments exhibited that it would help to gain the perfect UV-curable materials by choosing the hyperbranched polyesters with different contents of active groups.