混合溶剂法合成酯基锡(甲酯)及其对PVC的热稳定性

Synthesis of Ester-tin(methyl acrylate) by Mixing Solvent and its Effect on the Thermal Stability of PVC

采用混合溶剂法和相转移催化剂合成酯基锡(甲酯)。结果表明,反应时间为5～6 h,反应温度为53～58℃,Na2CO3水溶液浓度为20%是最佳合成条件。所合成产物存放120 d以上依然澄清透明,解决了NaHCO3法合成酯基锡(甲酯)放置不超过7 d就出现沉淀和臭味重的问题。用IR、1H-NMR对产物进行结构表征。结果表明,新方法合成产物红外吸收峰归属和主要官能团化学位移与NaHCO3法合成的产物一致。在50～650℃,空气氛围,用TG/DTG研究了酯基锡(甲酯)/PVC复合体系的热降解过程,并与甲基硫醇锡/PVC复合体系进行对比。结果表明,酯基锡(甲酯)对PVC的初期稳定性好于甲基硫醇锡,抑制PVC着色性能不及甲基硫醇锡。当T>300℃时,酯基锡(甲酯)/PVC复合体系的降解速度相对变慢,热失重率更小。用塑炼机和比色测色仪测试两个复合体系的动态热稳定性,从测试结果可见,在180～183℃,塑炼15 min,酯基锡(甲酯)/PVC复合体系的透光率仅从86.76%下降到84.18%,黄度值从7.54上升到8.95。透光率好于甲基硫醇锡/PVC复合体系,黄度值变化相差不大,说明酯基锡(甲酯)能使PVC保持良好的透明性和加工稳定性。研究提出的合成方法解决了酯基锡合成中存在的瓶颈问题,所合成的产品适合应用于制备PVC透明制品。

Ester-tin（methyl acrylate） was synthesized by mixing solvent method with phase transfer catalyst.The results show that the optimal reaction time is 5～6 h,the optimal reaction temperature is 53～58℃ and the concentration of Na2CO3aq.used is 20%.The product synthesized by the proposed above method can still keep clear within 120 days after being synthesized;however,the same ester-tin（methyl acrylate） synthesized by the conventional method of using NaHCO3 will occur precipitation and sand out an odious small within seven days after being synthesized.The ester-tin（methyl acrylate） synthesized by the proposed new method was characterized by IR and 1H-NMR,and the results show that the product characterized has the similar IR spectrum and chemical shift of the main functional group as those of the ester-tin（methyl acrylate） synthesized by the conventional method of using NaHCO3.The thermal degradation of ester-tin（methyl acrylate）/PVC was investigated by TG/DTG in the flowing atmosphere of air at 50～650℃ and was compared with that of methyltin mercaptively/PVC.The results show that the ester-tin（methyl acrylate） exhibits a better primary stability but little poorer initial coloration characteristics than methyltin mercaptide.When temperature is over 300℃,the degradation speed of ester-tin（methyl acrylate）/PVC becomes slower,and the mass loss percentage is lower too.The dynamic thermal stability was tested on a plasticator and Color Quest XE.The transparency of ester-tin（methyl acrylate）/PVC only decreases from 7.54 to 8.95 after processing over 15 min at 180～183℃.These test results indicate that the ester-tin（methyl acrylate） can help the PVC to have not only an excellent transparency but also a good processing stability.The ester-tin（methyl acrylate） synthesis method proposed solves the key problem in ester-tin synthesis and its product can be used to produce transparent PVC goods.