用钛酸丁酯复合钛催化体系引发异戊二烯聚合Ⅰ.聚合条件的影响

摘要

以钛酸丁酯和负载钛(TiCl4/MgCl2)为主催化剂、三乙基铝为助催化剂催化异戊二烯聚合,研究了主催化剂用量、三乙基铝与钛酸丁酯的摩尔比、负载钛催化剂加入时间及温度等对单体转化率和催化效率的影响,并对聚合物的汽油不溶部分和可溶部分的结构进行了核磁共振氢谱表征,用差示扫描量热法测试了汽油不溶部分的结晶度.结果表明,所得聚合产物为1,4-结构摩尔分数67.4%、3,4-结构摩尔分数32.6%的复合异戊橡胶;聚合体系的单体转化率随钛酸丁酯/异戊二烯(摩尔比,下同)的增大而升高,而催化效率则先升高后降低;二者均随三乙基铝/钛酸丁酯的增大先升高后降低,最佳值为9～10;二者均随加入二种催化剂时间间隔的延长先升高后降低,随聚合温度的升高先升高后降低,且在30～35 ℃时达到最高值.%The composite isoprene(Ip) rubber was polymerized with tetra-n-butyl titanate,supported titanium catalyst as main catalyst and triethylaluminium(Al) as cocatalyst. The effects of main catalyst amount, Al/Ti(C4H9O)4(mole ratio, the same below), the adding time of TiCl4/MgCl2 and temperature on the conversion and catalyst efficiency(CE) were investigated.The characterization of structures for gasoline insoluble and soluble parts of the rubber was conducted by proton magnetic resonance and the crystallinity of gasoline insoluble part was determined by differential scanning calorimetry. The results showed that the composite polyisoprene rubber with 67.4% of 1,4-unit and 32.6% of 3,4-unit could be obtained. When Al/Ti(C4H9O)4 was invariable, the conversion of Ip increased, while CE increased at first and then decreased with increasing Ti(C4H9O)4/Ip. Both the conversions of Ip and CE increased at first and then decreased with increasing Al/Ti(C4H9O)4, as well as extending addition interval between the two main catalysts and raising reaction temperature. When reaction temperature was 30-35 ℃, both conversion and CE reached the highest value, and the proper Al/Ti(C4H9O)4 was 9-10.