Development And Industrialization Of High-Crystallized Polypropylene

With wonderful physical and mechanical properties, chemical stability, processability, polypropylene becomes the most widely used general-purpose plastics. Being a kind of high-powered special resin, high-crystallized polypropylene (HCPP) has lots of strongpoints, such as, high stiffness, high strength, high modulus, high resistance to heat distortion, short confectioning periodic time, high tenacity, high resistance to damage, good fluidity and wonderful endurance to impact. The use of HCPP is much broader than that of common PP. It is widely used in making industrial, motor and household electrical accessories, OPP/CPP thin films, commodities, sheet materials and fibers. Moreover, it is a kind of high value added product which makes large-scale product thinner and lighter. At present, the production of HCPP is nearly zero at home, while, overseas, it is just at the period of study.There are two main ways to gain HCPP, one is to use high active and high performance catalyst system; the other is to improve the crystalline growth velocity and thus change the crystalline form by adding some nucleating agent into PP resin.Due to the bad homogeneity and large nucleator wastage, the second way of getting HCPP results in comparatively higher production costs. While, method one can be applied on existing polyplant by using special catalyst and improving polymerization technology. As a result, a bright future of industrialization and market is foreseeable..This thesis gives a survey on the production of HCPP overseas, choice of catalyst, performance and usage of product. According to the understanding of the development trend of HCPP overseas, firstly, some representative overseas HCPP samples were analyzed and special catalyst system and the polymerization conditions of small-scale were determined; secondly, experiments were carried out with special catalyst, the properties of experimental products were analyzed and polymerization conditions were optimized; thirdly, one conclusion was made that the combination of catalyst X1 and Y-Donor could be used in producing HCPP; finally, ideal HCPP products were obtained after trying industrial processes twice. But the manufacturing techniques to get such kind of products need to be further optimized.The innovation of this thesis is to prepare HCPP directly on the device (40kt/a gas-liquid mass polypropylene equipment) imported from Mitsui Petrochemical Co. of Japan by using new catalyst system and polymerization technology.