Although there's no doubt metallocene technology is advancing in the plastics industry, some see it as a waterfall, while others think it's more like a glacier.
Surinder Bahl, project manager for Phillip Townsend Associates Inc., a Houston consulting firm, is in the waterfall camp. In a recently issued study, Bahl claims global metallocene consumption will reach 8.04 billion pounds by 2001. That total is a quantum leap from the 1997 consumption estimate of slightly more than 500 million pounds.
Almost 7.5 billion pounds of the 2001 projection will be in metallocene-based linear low density polyethylene, with the remainder in metallocene-based high density PE, according to Bahl. Geographically, North America will lead consumption with about 4.1 billion pounds. Film uses will dominate the market, consuming almost 6.9 billion pounds, compared with about 770 million pounds for injection molding applications.
Exxon Corp. of Houston and Dow Chemical Co. of Midland, Mich., currently are the top global metallocene resin producers. Exxon's annual output is 150 million to 175 million pounds. Bahl ranks Dow second with annual production of 110 million to 150 million pounds. However, Dow officials said their output is close to 700 million pounds a year.
On the technology side, Exxon and Union Carbide Corp. of Danbury, Conn., have formed Univation Technologies to market their metallocene processes, while Dow and British Petroleum Co. plc have forged a similar alliance.
Other North American companies with metallocene PE in development or production include Mobil Chemical Co. of Edison, N.J.; Phillips Petroleum Co. of Bartlesville, Okla.; Nova Chemicals of Calgary, Alberta; and Chevron Corp. of Houston.
The market will benefit from easier-to-process metallocene grades being developed, as well as from a further move into PE's commodity-based world, according to Bahl.
First-generation metallocenes had narrow molecular weights, causing processing difficulties that prompted processors to use the material in blends with standard LLDPE. New advancements — such as Dow's work with long-chain branching — are creating broader molecular weights that should iron out previous processing difficulties, Bahl said.
Bahl's optimistic outlook is taking shape at Lone Star Plastics in Garland, Texas, a film maker that does 35-40 percent of its business in metallocene-based products.
Lone Star, founded in 1996 as Popst Manufacturing Corp., has added two new lines to meet demand. The company recently was purchased by an investment group headed by Drayton McLane, owner of the Houston Astros baseball team.
Lone Star's customers are downgauging their bag thicknesses 20-25 percent, according to Gene Wailes, executive vice president. Lone Star also is doing more work with metallocene-based HDPE and is developing metallocene films for use in meat packaging.
Other firms using metallocene-based products say the materials still are challenging to use, requiring mechanical adjustments to equipment and marketing adjustments. Such opinions were evident in papers presented by Edward Bullard of Tenneco Packaging and Timothy Weikert of General Films Inc. at SPO '97, a specialty polyolefins forum held in Houston last September.
Metallocenes aren't for everyone, according to Bullard, senior materials scientist at Tenneco Packaging, the Lake Forest, Ill.-based unit of Tenneco Inc. that ranked seventh in Plastics News' 1997 survey of North American film and sheet manufacturers.
Bullard said Tenneco, which uses metallocene materials in 10-20 percent of its stretch film products, has had success with its proprietary MaxPlus stretch film as pallet wrap, but saw poor results when using basic materials for both pallet wrap and waste bags.
In waste bags, the metallocenes improved performance in lifting tests, which simulate picking a product out of a can. But they did not fare as well in load tests, in which a bag is filled with increasing amounts of water.
``We started in metallocenes with boyhood enthusiasm — we thought it was going to be a fantastic material,'' Bullard said in a recent telephone interview. ``We learned you can't take a simplistic approach.''
The basic paradox, according to Bullard, is that standard metallocene uses did not work well in testing for high-end applications where added cost would not make as much of a difference. In low-end applications, standard metallocene uses are not cost-effective since they do not show enough improvement to justify the price, he said.
Weikert, president of Covington, Ohio-based General Films, said his firm has been satisfied, mostly, with its experience in metallocene film. But he added that the materials have processed less-productively than traditional LLDPE, reducing throughputs by as much as 10 percent.
Metallocenes currently go into 15-20 percent of the firm's sales, which are split evenly between industrial and food packaging. Successful metallocene applications have included modified-atmosphere-packaging bags for fresh poultry and bulk liquid bags for water and milk.
But Weikert also cautioned that traveling the metallocene road requires some endurance.
``[Metallocenes] aren't Nirvana,'' Weikert said. ``You really have to spend a lot of time, effort and money to see how [metallocenes] fit in with your customers' needs. I don't think they'll be a true revelation until some of the processing penalties are overcome by the resin companies.''
Weikert added he believes metallocene makers seriously have underestimated the products' ``touch-feel nature.''
``You can put [metallocenes] through the lab and the plant and see how they work, but some of the perception problem with customers is that it feels flimsy,'' he said. ``That runs a flag up a pole in their minds.''
Early emphasis in marketing metallocenes as plastomer and elastomer replacements slowed the material's commercialization in PE, in Bahl's opinion.
``Metallocenes weren't commercialized as quickly because the two companies that put a lot of money into it, Dow and Exxon, didn't go after the commodities market; they went after specialties,'' Bahl said. ``Now commodities are the only way to see that they get return on their investment.''
Officials at Dow and Exxon did not agree completely with Bahl's overview, saying each company always planned to move into commodity uses.
``You need to get into the higher-volume-usage areas to justify your research,'' said Ed Gambrell, business vice president for Dow's Insite technology. ``If you stop at the low-volume usage, you're not maximizing your return on investment.''
``We started with a very defined strategy, going into plastomers and elastomers first,'' Gambrell added. ``Once we got that established, the next step was to take it into linear low.''
Exxon's Joseph DeVet added that expanding metallocenes into traditional polyolefin applications was always a part of his company's game plan as well.
``We really expect metallocene to be the new standard for LLDPE,'' said DeVet, product manager for the company's Exceed-brand metallocene PE.
Blended applications, in which metallocene LLDPE is used in combination with basic LLDPE, will continue to have a large impact, according to both Gambrell and DeVet.
``Some applications will call for blending, but lately we've been seeing more unblended uses,'' Gambrell said. ``The fashion of this industry has always been blending, and metallocenes didn't change that.''
``Our view is that our [metallocene] products attain their greatest value in combinations,'' DeVet said. ``There's no trend away from using combinations to utilize what we bring to the party.''
Dow will unveil new metallocene LLDPE grades with easier processing characteristics for the injection molding market later this year. Exxon is continuing work at its Mont Belvieu, Texas, facility to improve metallocene processing.
Judging from comments made by Exxon PE Vice President Irwin Levowitz at a recent petrochemical conference in Houston, optimism for metallocenes has not receded.
Levowitz described a scenario in which metallocene-based PE films would allow fresh produce to be packaged right in farm fields, allowing it to reach the marketplace without additional handling or the risk of spoiling.
``Metallocenes can open up new markets some of us never dreamed of,'' he said.
