Tomomi Hiramoto, Tetsuya Yoshikiyo
Papers # 2014 Chicago
Polyethylene has been used for various pipe applications. In particular the use of PE100 material has been expanding in pressure pipes for gas and water service. In general, PE100 materials have very high molecular weight component in order to improve the performance of durability, so they have high viscosity and their processability are usually poor. Responding to increased demand of PE100 pipes in the market, requirements for the improved production efficiency are growing. To meet those customer needs, we developed a new PE100 grade which has an excellent balance between durability and processability. In PPXIII, we have reported PE100 grade (NOVATECTM HD HE212W, HLMFR=9g/10min) which has extraordinary resistance to slow crack growth (SCG) ; notch pipe test (NPT) >20,000h, using our Advanced Multi-modal Slurry Loop Process (AMSLP), which has 3 cascade reactors, and a high performance catalyst. As a result of further refining on this technology, we have succeeded in developing a new PE100 grade (NOVATECTM HD HE222W) which has the best balance between flowability and SCG resistance. The new PE100 grade whose HLMFR is 18g/10min shows excellent processability, for example, >10% less extrusion load, >20% less injection pressure and better surface finish of injection molded fittings than a conventional one. Moreover, it is possible to mold at lower temperature. Lower processing temperature decreases the risk of processing defects such as burn particles and die drool, it also contributes to energy saving. These features are expected to drastically improve production efficiency of both pipe extrusion and fitting injection. Regarding the durability of the new PE100 grade, it keeps very good SCG resistance level. NPT result of >5,000h determined at our laboratory is far more superior to the specification in ISO 4427 and ISO 4437. We believe that our new PE100 grade can contribute to the further growth of plastic pipe industry.