The commercialization of HDPE began when Ziegler-Natta discovered the catalyst system that allowed the manufacture Polyethylene at lower pressures and temperatures, thereby permitting a polymer with fewer short chains. The introduction of the gas phase process by Union Carbide Corporation heralded a decade of new technology developments throughout the 1970�s, which saw the introduction of a number of solution, slurry and gas phase processes. In this period of rapid new developments, there were new bimodal technology introductions, which resulted in improvement of existing technologies, such as Basell�s Hostalen and Mitsui�s CX high density processes. The 1990�s saw the introduction of competing new bimodal technologies including Borealis� BORSTAR, Basell�s SPHERILENE, and Mitsui�s EVOLUE processes, as well as metallocene/single-site catalysts (for LLDPE production). The most recent development since 2000 has been the commercialization of Univation�s bimodal UNIPOL process, producing bimodal HDPE in one reactor.

A small number of technologies dominate the HDPE market. Four technologies (Chevron Phillips, UNIPOL, Mitsui, and Hostalen) accounted for 70% of installed capacity in 2005. With the addition of three more technologies (Solvay, gas phase INNOVENE, and Equistar-Maruzen), 85% of the global capacity is accounted for. The slurry loop and Ziegler slurry processes continue to dominate HDPE production, accounting for 68% of installed capacity. Gas phase plants that predominantly produce HDPE account for an additional 25% of capacity.

A major development thrust for HDPE has been into bimodal grades for high performance film, pressure pipe and to a lesser extent blow molding applications. Pressure pipe producers are now pursuing the next pressure rating standard of PE125, with a number of producers well established in the PE100 category. Currently, most commercial bimodal HDPE is produced in multiple reactor configurations, particularly dual reactor processes, which are optimal for the tailoring of resin structure. There is an increasing trend to bimodal products, where the combination of better processability without the loss of mechanical strength, permits downgauging, a reduction in product profile or thickness. For film, the same area of film can be made with lesser polymer, while for pressure pipes, reduced wall thickness reduces raw material requirements and makes more flexible pipe. However, conventional unimodal HDPE will maintain a significant market share. Bimodal HDPE is expected to maintain some price premium in the market, based upon a genuine performance advantage over unimodal material.
Since the early 1990�s, metallocene/single-site catalyst developments have dominated advances in polyethylene technology, mainly for LLDPE applications. While traditional HDPE applications are not expected to see significant metallocene penetration in the short-term, there are metallocene-based advances in HDPE. The introduction of dual-site catalysts for the production of single reactor bimodal HDPE may become a significant metallocene application, as dual-site catalyst research has typically focused on at least one metallocene component in the catalyst system.

The following are the most prevalent technologies for bimodal PE

		Unipol Prodigy
		Innovene PEs
		Spherilene C
		Borstar
		Hostalen
		Chevron Phillips
		Equistar-Maruzen
		Mitsui CX

The following technologies offer the conventional unimodal HDPE

		Unipol
		Spherilene
		Innovene PEg
		Chevron Phillips
		Advance Sclairtech

Global demand for HDPE in 2005 was 28.2 mln tons and has reached almost 31 mln tons in 2006. Eastern/Central Europe, South America, Asia Pacific, the Middle East and Africa will have growth rates higher than the global average, with Asia Pacific having the highest growth in terms of volume.

HDPE demand by end use applications shows that blow moulding is the largest end use, accounting for 28% of total demand. Film represents the next largest segment with 26% market share. Other significant end uses are injection moulding at 19% and pipe and conduit 13%. This pattern is not expected to change significantly in the near future. HDPE global capacity in 2006 was about 32 mln tpa, with 5.5% growth in capacities projected in the next 5 years. To meet this speculative demand growth, capacity additions will be required to address the supply/demand issues. HDPE production capacity profile will change significantly over the forecast period. North America and Western Europe are forecast to lose share in the global market, while Asia Pacific and the Middle East will increase their shares.