Research On Synthesis Of High Isotactic Polybutene-1

In the past ten years,petrochemical industry of China has been prospered greatly.There is a large amount of butene-1 which is a kind of byproduct in the petroleum industry chain,but the effective utilization rate of butene-1 is very low in China,most of butene-1was burned.So the development of butene-1 polymerization technology for PB-1 can not only improve the economic benefits of ethylene plant,but also can solve the problem of the waste of resources that caused the low effective utilization rate of butene-1.In addition,it has an important significance to the construction of environmental protection and sustainable development of society.High isotactic polybutene-1 is of wide concern due to its excellent creep resistance and good performance of environmental stress cracking.At present,the main raw materials of high isotactic polybutene-1(i-PB)products are imported,and there is no large-scale production of i-PB in china.The main reason is the lack of mature polymerization process.The development of the preparation technology of i-PB can get rid of the dependence on foreign technology and meet the demand of our country for the market of i-PB.So far,the Ziegler-Natta catalyst is used in the industrial preparation of i-PB.The butene-1 bulk polymerization experiment is based on self-designed small-scale polymerization unit in Lanzhou Petrochemical Research Center,we use commercial ZieglerNatta catalyst A,external electron donor CHMMS and promoter of AlEt3 to polymerize butene-1 to study the synthesis of isotactic polybutene-1.The purpose is to preparate high isotacticity and high crystallinity polybutylene-1 for hot-water pipe.The effects of catalyst dosage,temperature,the form and rate of stirring,external electron donor dosage and reaction time on polymerization activity and morphology,isotacticity,molecular weight and its distribution and crystallinity of i-PB are researched.We gradually choose the best reaction conditions that the catalyst dosage was 30 mg,stirring rate was 10% at low temperature and30% at high temperature,reaction time was 2 h,Al/Ti molar ratio was 300 and the CHMMS/Ti molar ratio was 30.According to the optimum process conditions,two i-PB samples were prepared with dispersed spherical particles at higher temperature.The differences between the self-made i-PB and commercial PB 4235 and PB 5050 were compared by using the methods of ether extraction,differential scanning calorimetry,polarizing microscope and rotational rheometer.The isotacticity of self-made i-PB reached97.6%,molecular weight is 138.7×104,molecular weight distributions is 4.4 and the crystallinity is 50%,melting point is 121.4℃.The structure and performance of the selfmade i-PB are close to those foreign products’ s,such as PB 4235 and PB 5050.Theformability of i-PB in the polymerizer is also studied,which laid a theoretical foundation for the industrialization of i-PB.