Polypropylene catalyst technology

Since the last edition several new materials have been aimounced. Many of these are based on metallocene catalyst technology. Besides the more obvious materials such as metallocene-catalysed polyethylene and polypropylene these also include syndiotactic polystyrenes, ethylene-styrene copolymers and cycloolefin polymers. Developments also continue with condensation polymers with several new polyester-type materials of interest for bottle-blowing and/or degradable plastics. New phenolic-type resins have also been announced. As with previous editions I have tried to explain the properties of these new materials in terms of their structure and morphology involving the principles laid down in the earlier chapters. 

Plastics Rubber Manufacturing Petrochemicals Catalyst Technology Polypropylene... 

Competition, in the market of polypropylene licensing technologies, has been a driving force to improve the available processes, with the aim of reducing the investment and variable costs obtained by a simplification of the process, reduction of raw materials and utilities consumptions, improving also the environmental impact with lower gas emission and liquid effluents. The evolution of catalysts and technology has allowed the polypropylene properties to be expanded, to fulfill the market demand and to widen its application. 

Additional examples of polymerization processes can be found in a recently published review of fiber-forming polymerization patents by Robinson (27). A detailed comparison of batch and continuous polymerization for nylon 6,6 can be found in a review by Jacobs and Zimmerman (15). In another review Short has summarized the current state of polypropylene polymerization technology and catalyst development (28). 

At the time of this writing a number of metallocene/single-site catalyst technologies are available with which to produce polypropylene (see Table 11). Metallocene-based polypropylenes are commercially available and even catalyst licenses are available (264). 

Here, we review (1) research activities in metallocene catalysts, (2) polymerization performances of metallocene catalysts and other single-site catalyst technologies, with examples for polyethylene (PE), cyclo-olefin copolymer (COC), polypropylene (PP), syndiotactic polystyrene (SPS), and cyclo-olefin polymers, and (3) the computational design of metallocene catalysts. 

There are two methods used to blend polypropylene and EPDM rubber to make a TPO. The original method, still used extensively, is to simply mechanically blend the two polymers together with high shear mixing at an elevated temperature. However, a newer procedure employs new catalyst technology to blend EPDM and PP in the polymer reactor itself. This newer technique lowers the TPO production costs however, this type of TPO can only be obtained from the polymer manufacturers themselves. Reactor-produced TPOs can also be made softer than the mechanically blended TPO types. Some TPOs are also based on polyethylene as well (such as metallocene-catalyzed polyethylene), see Figure 6.7. 

Just recently a new polyolefin wax family had been developed by using metallocene catalyst technology. The family of waxes includes polyethylenes and specialty grades of polypropylenes and copolymers. These low viscosity and low softening point resins have already been successfully used as dispersing aids in the production of master-batches, in adhesives and sealants as well as in fibre glass coatings for composites [2],... 

The next major commodity plastic worth discussing is polypropylene. Polypropylene is a thermoplastic, crystalline resin. Its production technology is based on Ziegler s discovery in 1953 of metal alkyl-transition metal halide olefin polymerization catalysts. These are heterogeneous coordination systems that produce resin by stereo specific polymerization of propylene. Stereoregular polymers characteristically have monomeric units arranged in orderly periodic steric configuration. 

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