Rare-earth catalyst for diolefin polymerization and its prepn.

[0024] Under the protection of nitrogen, add 3.0×10 -4 mol of NdCl 3 3 (i-PrOH), 6 mL of 1.0 mol / L isoprene hexane solution, 4.5 mL of 2.0 mol / L MMAO toluene solution, and 9.5 mL of hexane was added. React at 20°C for 0.5 hour to obtain a rare earth catalyst for diolefin polymerization.

[0025] Under the protection of nitrogen, 2560 mL of hexane, 440 mL of isoprene (300 g) and the catalyst prepared above were added to a 5 L dry and deoxygenated autoclave. At this time, the monomer concentration is 10g / 100mL, and the Nd / isoprene ratio is 1.0×10 -6 mol / g. After reacting at 50°C for 4 hours, terminate the polymerization with an ethanol solution containing 1.0% 2,6-di-tert-butyl-p-cresol, then precipitate the polymer in excess ethanol, wash and extrude it with ethanol, and place it at 40°C Drying under reduced pressure for 24 hours yielded 285 g of isoprene polymerization product with a conversion rate of 95%. The cis-1,4 structure content measured by infrared spectrum is 96...

[0027] As in the catalyst preparation method and polymerization conditions in Example 1, only with NdCl 3 3EtOH instead of NdCl 3 • 3(i-PrOH).

[0028] The results of the obtained polyisoprene are as follows: the polymerization product is 240g, the conversion rate is 80%, the cis-1 and 4 structure content is 95.6% as measured by infrared spectroscopy, and the number average molecular weight is 146200 as measured by GPC. is 1.85.

[0030] As in the catalyst preparation method and polymerization conditions in Example 1, only with NdCl 3 ·3CH 3 (CH 2 ) 5 OH instead of NdCl 3 • 3(i-PrOH).

[0031] At this time, the result of using the polyisoprene obtained therefrom is as follows: 270 g of the polymerized product, the conversion rate is 90%, the cis-1, 4 structure content is 96.0% as measured by infrared spectroscopy, and the number average molecular weight as measured by GPC is 189,500. The molecular weight distribution was 1.83.