制备工艺对DEG系聚己内酯二元醇酸值的影响

Influence of preparation process on acid value of DEG-polycaprolactone-diol

采用本体聚合工艺,以二乙二醇(DEG)引发ε-己内酯开环聚合反应制备DEG系聚己内酯二元醇,分析了产物的微观结构,研究了3种工艺条件对DEG系聚己内酯二元醇酸值的影响。结果表明:经核磁共振氢谱分析,确认产物中的聚合物为DEG系聚己内酯二元醇,ε-己内酯转化率为99.81%,产物中残留ε-己内酯质量分数为0.19%;在“氮气保压”(A工艺)条件下,产物酸值高;在“先氮气保压、后氮气吹扫”(B工艺)条件下,可有效降低产物酸值,但反应时间较长;在“反应前脱水、反应时氮气吹扫、反应后脱挥”(C工艺)条件下,产物酸值(以氢氧化钾计)均低于0.35 mg/g,且反应时间在6 h以内;反应前降低ε-己内酯的含水量、反应时氮气吹扫可有效降低产物的酸值;C工艺更适合DEG系聚己内酯二元醇的规模化生产。

DEG-polycaprolactone diol was prepared using diethylene glycol(DEG)to initiate ring-opening polymerization ofε-caprolactone by bulk polymerization process.The microstructure of the product was analyzed,and the effects of three kinds of preparation processes and their process conditions on the acid value of DEG-polycaprolactone-diol were studied.The results showed that the polymer in the product was identified as DEG-polycaprolactone-diol by nuclear magnetic resonance hydrogen spectrum analysis,the conversion rate ofε-caprolactone was 99.81%,and the residual content ofε-caprolactone was 0.19%by mass fraction in the product;the acid value of the product was high under the conditions of"nitrogen pressure maintenance"(process A);the acid value of the product could be effectively reduced,but the reaction time would be extended under the conditions of"nitrogen pressure maintenance,followed by nitrogen purging"(process B);the acid value of the product(based on potassium hydroxide)was below 0.35 mg/g,and the reaction time was 6 h and below under the conditions of"dehydration before reaction,nitrogen purging during reaction,and devolatilization after reaction"(process C);the acid value of the product could be efficiently reduced by decreasing the water content ofε-caprolactone before reaction and adopting nitrogen purging during reaction;and process C was more suitable for the large-scale production of DEG-polycaprolactone-diol.