NOVEL PHILLIPS LOOP-SLURRY BASED POLYETHYLENE RESINS USING MODIFIED CHROMIUM OXIDE CATALYSTS FOR HIGH PERFORMANCE PIPE APPLICATIONS

摘要

Novel high density polyethylene resins made in the Phillips Loop-Slurry Process (single-reactor), using a catalyst of chromium on modified aluminophosphate, were developed with unique structural attributes that make them especially suitable for high performance pipe applications. These structural attributes include high molecular weight (MW), very broad molecular weight distributions (MWD), effective levels of short chain branching in polymer chains with MW > 1,000,000 g/mol, and reduced levels of long chain branching (LCB). In particular, pipes made from these ethylene 1-hexene copolymers satisfy the performance requirements of PE100 specifications; in addition, these resins also offer outstanding slump (or sag) resistance for large diameter (> 24 inch) pipe processing. In this paper, a brief description of these catalyst systems is presented along with the unique molecular aspects of the resins. The physical properties of these resins and their fabricated pipe processing/performance properties are compared to several "bimodal" type resins.