苯甲酸甲酯促进茂金属催化剂催化SBS加氢反应研究

以苯甲酸甲酯为促进剂,用茂金属催化剂制备了活性丁苯嵌段共聚物(SBS)的选择性催化加氢产物,讨论了苯甲酸甲酯、SBS的数均分子量等因素在几种实验条件下对产物加氢度的影响.结果表明,每百克干胶使用0.15～0.3mmol Ti催化条件下,苯甲酸甲酯在特定添加方式下能较大程度地提高茂金属催化剂的活性.在不加入苯甲酸甲酯的情况下,Mn=6.5×104和Mn=5.5×104两种SBS基础胶加氢反应180min时加氢度均97.0%;加入酯以后,反应60～120min时,基础胶的加氢度≥98%;与已报道的研究结果相比,将加氢反应时间缩短了60～120min.在每百克干胶使用0.15～0.3mmolTi催化条件下,数均分子量的大小也对SBS基础胶的加氢度有影响,反应30min时,Mn=5.5×104的加氢度≥97%,Mn=6.5×104的加氢度90%;随着反应时间的延长,这种差距在逐渐缩小;反应180min时,两者已无明显差距,此时两种基础胶的加氢度都≥98%.对影响的加氢度的机理进行了解释.

SELECTIVE CATALYTIC HYDROGENATION OF SBS BLOCK COPOLYMER WITH METALLOCENE CATALYST ACCELERATED BY METHYL BENZOATE

The selective catalytic hydrogenation of living styrene-butadiene copolymer (SBS) prepared in the presence of metallocene catalyst modified by methyl benzoate was studied. The effects of factors,such as number-average molecular weight (Mn) of SBS,on the hydrogenation degree of the copolymers under different experimental conditions were discussed. The results show that when the ratio of Ti to 100 g dry copolymer is in the range of 0. 15 ～ 0. 3 mmol,adding methyl benzoate in a special mode can significantly improve the activity of titanocene catalyst. The hydrogenation degree of both SBS basic copolymers with Mn of 6. 5 × 104 and 5. 5 × 104 respectively are < 97. 0% after reaction for 180 min in the case of using metallocene catalyst not modified by methyl benzoate. On the other hand,the hydrogenation degree of the same SBS samples is ≥ 98. 0% after reaction for 60 ～ 120 min under the condition of using the modified metallocene catalyst. In contrast with the similar researches reported before,our experiments could shorten the hydrogenation time by 60 ～ 120 min. When the ratio of Ti to 100g dry copolymer falls in the range of 0. 15 ～ 0. 3 mmol,the hydrogenation degree of the SBS basic copolymer is affected by magnitude of the Mn. For 30 min after the reaction,the hydrogenation degree of SBS copolymer with Mn of 5. 5 × 104 is ≥97. 0% whereas that of the copolymer with Mn of 6. 5 × 104 is < 90. 0% . The disparity in hydrogenation degree between the two SBS copolymers is gradually diminished as the hydrogenation process proceeds and becomes unobvious after reaction for 180 min. In such a case the hydrogenation degree of both SBS basic copolymers are ≥ 98% . The effect of every influential factor on the hydrogenation degree of the SBS copolymers is elucidated in terms of the hydrogenation mechanism.