The Chemical World This Week
CARBIDE UNVEILS NEW POLYETHYLENE PROCESS The U.S. chemical industry's big priority on process research and development in the past five years is beginning to pay big dividends. For the first time in a long while, completely new processes are emerging from chemical companies. These processes have the types of advances in efficiency and safety reminiscent of the heyday of process development in the 1950's. A month ago, Atlantic Richfield announced a completely new process to make polymeric isocyanates (C&EN, Oct. 10, page 12). Then last week, in a much larger product area, low-density polyethylene, Union Carbide made a sensational disclosure. By coming up with a new catalyst, about which Carbide will say very little, the company's scientists and engineers have done away with the need for extravagant high-pressure technology to make the most widely used U.S. plastic. The result is a vastly simplified low-density polyethylene process with a long string of advantages, capped by a 50% saving in capital cost and a 75% saving in energy cost. Other improvements in the new process over conventional high-pressure polyethylene technology include greatly enhanced safety, a projected 1980 product price 15 to 25% below previous forecasts, elimination of 90% of the space needed for production equipment, and the possibility of a low-pollution classification from the Environmental Protection Agency. Instead of conventional pressures of 30,000 to 50,000 psi, pressures in the new Carbide process range from 100 to 300 psi. The new reaction temperature is less than 100° C. Reaction is gas-phase instead of liquidphase in conventional technology. Essentially, the new process is a dramatic offshoot of Carbide's 12-yearold gas-phase technology for highdensity polyethylene. Work on the current process has been under way for seven years. Featuring points like these, Carbide's new development amounts to the process of the decade thus far for the 1970's. With unrestrained excitement, company chairman William S. Sneath says, "In the face of the continuing capital formation crunch and escalating energy costs, the advantages of the new process are such 6
C&EN Nov. 21, 1977
that it is likely to be the pre-eminent process for future expansion of the polyethylene industry." Carbide will offer the new technology to other producers through licensing agreements. Already the world's top producer of low-density polyethylene, Carbide plans nearly 1 billion lb a year of new capacity based on the new process by 1982. According to Sneath, "The initial phase of this expansion, slated for completion in 1980, calls for the construction of a new 300 million lbper-year facility at our petrochemical complex at Seadrift, Tex. We will follow up on this with the construction of a new 500 million lb-per-year facility somewhere on the Gulf Coast. The installation of an additional 150 million lb per year of new process capacity at Seadrift will bring new process capacity to 950 million lb per year by 1982." In the meantime before these projects come on stream, Carbide says it can fill projected market needs for the new polyethylene through a 250 million lb-per-year unit already operating at Seadrift. Although the new polyethylene can be produced in a wide range of grades with standard and unique properties, Carbide's initial marketing efforts will be concentrated in two areas.
Unit using new process already is operating at Carbide's Seadrift plant
Senior vice president E. E. Tarika says that the first area will be "selected specialty markets where performance advantages of the new product are maximized. Second, to demonstrate the broad range of product properties available from the new process, we'll enter one or two commodity markets in film and injection molding." •
EPA finds some 200 chc nicals in waterways With the heavy national concern over water quality in recent years, a natural question arises: Exactly what substances are in U.S. waters, and how many have simply gone undetected so far? A new study carried out as part of the Environmental Protection Agency's ongoing program to identify organic and inorganic compounds present in surface or recreational waters now has provided some answers. Aimed at major U.S. industrialized river basins and the Great Lakes, the study has identified more than 200 chemicals present in these waters in very minute amounts. Other than substances believed to be of natural origin, the organic compound appearing most frequently in the samples taken was chloroform. Other frequently appearing compounds were certain alkyl phthalate esters,
used widely as plasticizers, and benzene, acetone, and toluene. The study was conducted under contract to EPA by the Institute for Environmental Studies at the University of Illinois, Urbana-Champaign. University researchers collected a total of 204 samples from across the U.S. They came from Chicago; the Illinois, Delaware, Hudson, Ohio, and Tennessee river basins; the Mississippi River basin in Alabama and Texas; the Great Lakes and their tributaries; greater Los Angeles; San Francisco Bay; the Willamette River; and greater Portland and SeattleTacoma. Each sample was analyzed using state-of-the-art techniques for detecting trace contaminants. In these samples, 110 compounds were identified in acid-extractable fractions. The compounds appearing most frequently were methyl palmi-
tate, methyl stearate, diethyl hexyl phthalate, C15 terpineol, and methyl myristate. Although, of these compounds, only the phthalate ester is a synthetic, the majority of all the compounds identified were of synthetic origin, and many have been identified as toxic or carcinogenic, EPA notes. In base-extfactable fractions, 89 compounds were identified. Most frequent were diethyl hexyl phthalate, dibutyl phthalate, C15 terpineol, and C10 terpineol. Of these, the two phthalate esters are synthetic organics. Purgeable organic compounds in the samples numbered 81, most of them halogenated hydrocarbons from Ci to C6. Most frequently appearing were chloroform, trichloroethylene, tetrachloroethylene, 1,2-dichloromethane, toluene, and bromodichloromethane. EPA attaches significance to the presence of chloroform and many of the other chlorinated and brominated hydrocarbons in almost every sample, but at levels below 1 ppb. The widespread occurrence of the compounds, suspected carcinogens or known to be toxic, emphasizes the need for further study of their origin and impact, EPA points out. •
data before deciding whether to change xylitol regulation. Xylitol currently is marketed in the U.S. in only one product—Orbit, a chewing gum manufactured by Wrigley. The company does not plan to make any changes in its gum or in the way it is advertised because of these findings. "We don't feel these preliminary feeding tests indicate anything dangerous in xylitol," says assistant vice president David Sloane. He points out that xylitol, a sugar alcohol, is a natural product that is synthesized by many animals, including humans, in the process of carbohydrate metabolism. Humans synthesize from 5 to 15 grams of xylitol a day. The level of xylitol given to the test animals is equivalent to chewing 200,000 sticks of gum a year, Sloane says. A pretty good gum chewer, he adds, might chew several hundred sticks a year. For the moment, Hoffmann-La Roche, too, is making no changes in its plans to market xylitol in the U.S. Xyrofin plans to build a plant at Savanna, 111., to make 10,000 tons a year of xylitol from corncobs. •
Long-chain alcohol boosts crop yields Field trials completed this summer at Michigan State University have verified that sprays containing a tiny amount of a naturally occurring alcohol, triacontanol, can increase the yields of a wide variety of commercial crops up to 24%. The substance thus stands to become an important supplement to increasingly expensive nitrogen fertilizer. Dr. Stanley K. Ries, an MSU horticulturist, last week described his work to science reporters gathered at Rockefeller University for the 15th annual meeting of the Council for the Advancement of Science Writing. Triacontanol, CH3(CH2)28CH2OH, is ubiquitous in the plant world, he explains; it occurs in leaf waxes, in honey and beeswax, and even in potatoes and apples. In fact, it is commonly present in soil. Even so, adding just a tiny bit more triacontanol to a field—at rates of only a few milligrams per acre—causes an immediate spurt in plant growth.
Xylitol causes some cancers in mice Xylitol, a sucrose substitute made from birch trees that has been touted for its tooth decay preventive properties, apparently has caused some cancers in laboratory animals. Preliminary findings from two-year chronic toxicity studies show an increase in urinary bladder stones in male mice fed xylitol in doses of 10% and 20% of their total diet. Some of the mice that developed bladder stones also had bladder inflammation and benign and malignant tumors. Female mice developed no unusual symptoms, and neither did male mice fed xylitol as 2% of their diet. The studies are being conducted by Huntingdon Research Centre in England for Xyrofin, a joint venture formed by Hoffmann-La Roche and Finnish Sugar Co. to produce ond market xylitol. In addition to mice, studies are being conducted on rats and dogs. Neither of these animals shows bladder changes associated with xylitol consumption, but rats fed xylitol as 20% of their diet show an increased incidence of adrenal gland tumors. Hoffmann-La Roche turned the preliminary test data over to the Food & Drug Administration earlier this month. FDA is reviewing the test
Highway test to use sulfur in pavement Asphalt and sulfur here feed into a portable unit to produce binder that will be used in a portion of an Alberta highway. The largest test yet of sulfur-asphalt paving, a 6-mile strip is being put down near Rocky Mountain House. The project is supported primarily by the Sulphur Development Institute of Canada (SUDIC), with a contribution from Gulf Oil Canada Ltd. Two independently developed sulfur/asphalt emulsion pavements will be tested—the Pronk process of R. M. Hardy & Assoc, and that of Gulf Oil Canada. The two processes differ slightly in process but produce essentially the same product. Sulfur is emulsified in asphalt, replacing up to 4 0 % of the asphalt in the binder, the binder then being used with regular aggregate to form the paving material. The Pronk portion of the trial uses a separate, portable unit (above) to produce the binder. SUDIC estimates that material costs for the trial are about 2 5 % less than for a conventional mix. And Alberta is looking for a way to use its large stockpiles of by-product sulfur from natural gas purification.
Nov. 21, 1977C&EN
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