Summary of Modified PP Technology
1. Metallocene PP
In the 1990s, the advent of metallocene catalysts injected new life into the polyolefin industry. Metallocene PP resins have also been commercialized. Tatgor has launched the first metallocene PP in Europe under the trade name Metocene X50081, which has the rigidity of PP homopolymer and the transparency of PP random copolymer. It is widely used in injection molding, especially for transparent thin-wall packaging materials. Production.
Japan's halogen metallocene PP homopolymer has good heat resistance, heat distortion temperature of 133 ° C, and has high flexural modulus, hardness and tensile strength, suitable for automotive bumpers and instrument panels. .
At present, the application of metallocene PP has been extended to injection molded articles, films and fibrous products. According to reports, global metallocene PP consumption will increase by 65% ​​annually. There are currently only three companies that produce metallocene PP industrially or semi-industrially, and at least 16 companies are developing the technology. According to information, in 2001, the world's metallocene PP accounted for 10%-20% of the total market supply, and will reach 60%-70% by 2010.
2. PP/POE blend system
Polyolefin Thermoplastic Elastomer (POE) is a (ethylene/octene) copolymer of metallocene technology using a limited geometry under the trade name Engage. The content of the comonomer octene is 20%-30%. At present, there are 18 kinds of Kngage products produced by American Road-DuPont United Company. The outstanding advantages are: POE modified PP has better impact resistance than EPR and EPDM modified PP, both excellent physical properties and very good Good processing properties and improved optical transparency of PP. Beijing University of Chemical Technology uses the company's POE as an impact modifier for PP to produce modified PP materials with excellent comprehensive properties. The PP/POE bumper special materials developed by Jiangsu Jiangdu Engineering Plastics Factory have been mass-produced, and the localization of Wantong and CaBSTaR bumper materials has been realized.
3. High melt strength PP
High Melt Strength PP was developed and developed by Belell, Belgium in 1994 under the trade name Paofax PF814 resin, which has a melt strength nine times that of conventional homopolymer PP. This high melt strength PP has great appeal in foam extrusion. Borealis has been working on the development of this technology, and it is possible to produce foam PP with very low density using its technology.
4. PP alloy / whisker composite
Whisker is used as a plastic reinforcement material. Its development and application began in the 1960s. However, due to the complicated production process, the output is small and the price is expensive, which greatly limits its wide application. In the 1980s, Japan reported an inexpensive, high-potassium titanate whisker that allowed it to be used in plastics.
Beijing University of Chemical Technology and other researches have developed a PP/EPDM/calcium sulfate whisker composite with a good interfacial layer by surface activation treatment of calcium sulfate whiskers. The results show that calcium sulfate whiskers can increase the tensile strength and flexural strength of PP/EPDM, and the impact strength is balanced. Xi'an Jiaotong University combined the calcium carbonate whiskers treated with the coupling agent with PP, and found that the tensile strength of the system was improved. When the material was impacted, the calcium carbonate whiskers could delay crack development and accelerate energy dissipation. The effect, thus having a toughening effect, while filling the PP with calcium carbonate whiskers, the processing properties are also significantly improved.
5. Nanoscale material modified PP
Nanomaterials are a new structure developed in the mid-1980s and are known as "the most promising materials of the 21st century." The addition of 2%-5% by mass of nano-clay can not only improve the gas barrier properties and heat resistance of plastics, but also greatly improve the mechanical properties and thermal properties, and reduce shrinkage and warpage.
Compared with conventional PP, nano-PP composites have better rigidity, good low-temperature impact, dimensional stability and low coefficient of thermal expansion, as well as excellent surface smoothness. These features make it suitable for the manufacture of automotive body panels, car bumpers and equipment instrumentation components.
Toyota Motor Corporation's central research and development laboratory, using PP oligomers modified with 5% nanoclay and maleic anhydride as compatibilizer to make PP nanocomposites with higher stiffness than PP filled with the same amount of talc or fiberglass. Much more. China has also successfully applied PP modified by nano-silicon oxides, which has improved strength and toughness and improved processing performance, especially the four main performance indexes of resistivity, water absorption, flexing and rigidity. More than Pa6 standard value, can replace Pa6.
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