One of these days you may be able to have your notebook PC and eat it too.
There’s a dramatic move under way to develop plastics that use plants as feedstocks. Engineering versions of these plastics, at least for now, also contain traditional petrochemical feedstocks in order to maintain stiffness, durability and other properties needed for technical applications. Of course they’re not edible, but they can stand up to the shock of a drop test.
Bioplastics come from plant sources such as hemp oil, soy bean oil and corn starch. They first came into vogue about 15 years ago as a proposed solution to solid waste problems until an “urban archaeologist” named William L. Rathje from the University of Arizona reported that waste does not degrade in a properly designed landfill. In fact, just the opposite is desired to keep toxic materials from leaching into aquifers.
Plastics made from plants are getting a new push today for a variety of reasons:
Growing concern about global warming is triggering interest in products that reduce carbon dioxide emissions. One metric ton of bioplastics generates between 0.8 and 3.2 fewer metric tons of carbon dioxide than one metric ton of petroleum-based plastics.
The price of oil, and consequently the price of oil-, or natural gas-, based plastics has become extremely unstable. The huge spike in plastics prices two years ago ruined many corporate budgets. Costs of plant-based feedstocks are also rising, triggered in part by the ethanol boom, but they are more predictable than oil-based feedstocks.
Brand-new versions of plastics are hybrids of oil- and plant-based feedstocks preserve property benefits of existing polymers such as PBT or nylon, and actually provide some improvements, particularly in surface finish.
The gorilla in the room is still costs. Because these hybrid engineering materials are just moving out of the lab, they are much more expensive to produce than current plastics. Major developers, such as DuPont, are committed to the future of the market and plan to offer hybrid materials at reasonably cost competitive levels until the market matures, when prices could actually be under oil-based materials.
Three are at least three chemical families of bioplastics.
Some bioplastics are made directly from starch and are used for applications such as drug capsules. Organic additives such as sorbitol and glycerine aid processing. Another, polylactic acid (PLA), comes from polymerized lactic acid produced by fermenting starch contained in sweet corn and other plants. PLA is already widely used for biodegradable medical implants and packaging. A third bioplastic poly-3-hydroxybutyrate (PHB) has properties comparable to polypropylene. Booming demand is triggering expanded capacity of both feedstocks and polymer. Sugar producers in South America, also primary sources of material used to make ethanol, announced large capacity increases. One analyst predicts that prices for PHB will drop below 60 cents per pound.
The Greening of Japan
The most exciting developments today are in Japan, where three recently passed laws are fueling development: the Law on Promoting Green Purchasing, the Law for the Promotion of Effective Utilization of Resources, and the Pollutant Release and Transfer Register (PRTR) Law.
One of the leading players is Fujitsu, which is using a PLA hybrid developed by Toray Industries to make the housing for its FMV-BIBLO notebook PC series Introduced two years ago. The Toray material, called Ecodear, is aimed at fibers, textiles, molded parts and films. Fujitsu and Toray first attacked the problem in 2002 with a pure PLA. The material, however, lacked adequate flame retardance and was not moldable because of its low temperature resistance. They decided to combine PLA (50 percent) with a proprietary amorphous oil-based plastic to achieve the required properties.
Toray is now bringing on line a $9-million plant in South Korea to produce PLA. Annual capacity is 5,000 metric tons a year. Korean packaging converter Saehan is a 10 percent investor. Packaging in South Korea is now being rapidly converted to biodegradable PLA, a trend still in its nascent stage in the United States. Toray is also developing nano additives to use in PLA film.
One interesting note: until recently PLA was only used because it is biodegradable. The Fujitsu hybrid material is not biodegradable. In fact, Fujitsu does not want the notebooks placed in landfills, where toxic metals could cause pollution. The goal is to increase recycling of the plastic components.
Just recently, Fujitsu announced another turn.
The company is now developing with French chemical producer Arkema a bioplastic based on castor oil that provides more flexibility than can be achieved with corn-derived plastics. The goal is to expand use of bioplastics in notebook computers. Castor oil is used because it is a source of nylon (polyamide) 11. A Fujitsu spokesman commented: “By weakening the interaction of the chain molecule in PA-11 and relaxing the stereoregularity of their organization, the resulting new material has sufficient flexibility to withstand repeated bending without causing the whitening that often occurs when such materials are strained.”
Prototypes of PC cover components consist of 60-80 percent of the new bioplastic, an unparalleled achievement to date. High-density fillers are added to increase strength. Fujitsu’s goal is to use the materials for notebook covers, and other applications requiring high impact resistance. Fujitsu also hopes to begin using the material in mobile phone covers too. The new material cuts carbon dioxide emissions 42 percent compared to oil-based nylon 6/6, according to Thomas Grimaud, Arkema’s technical polymers business manager.
Arkema’s new Rilsan PA 11 is now approved in fuel lines that carry biofuels in Europe and Brazil. The main driver in this development is performance. The new Rilsan is said to provide improved resistance over time to the aggressive attack of biofuels compared to polyamide 12. Interestingly, Rilsan PA 11 is not a new material. “We’ve been making it for over 50 years,” says Todd Rogers a market development official with Arkema. “We’ve always made it with castor oil because of the enhanced properties castor oil provides.” It’s widely used in oilfield applications as well as automotive brake lines.
Earlier this year, a German-based automotive supplier called Fraenkische announced the launch of enhanced safety fuel lines for fuel pump modules using technology based on Rilsan polyamide 11. The new fuel lines comply with the SAE J1645 automotive standard which is designed to increase passenger safety by inhibiting spark ignition in the fuel system, thus decreasing the risk of accidents. General Motors has already replaced its non-conductive fuel-pump modules for new North American car models. There was no environmental angle – it was the best material for the job. Rogers says. However, that new focus on sustainable resources is creating increased interest in the material. Its high cost, about $6 a pound, will limit its use.
The Japanese push, however, is clearly tied to green goals.
NEC Corp., is using a PLA-based plastic reinforced with kenaf fibers to make the entire case of a mobile phone for NTT DoCoMo, Japan’s largest mobile communications company. The kenaf fiber provides strength, allowing a significantly greater percentage of bioplastic – 90 percent. "About 75 percent of the surface area in this (phone), excluding the areas surrounding the screen and keys, is made of kenaf fiber-reinforced bioplastic," says Yusuke Moriyama, assistant manager of the Product Planning Department in the Mobile Terminals Div., NEC.
The “Eco Mobile” phone uses a textured look to create a “natural” design, says Katsuhiko Hirosawa, who is in charge of Eco Mobile product planning at NTT DoCoMo. The phone was initially targeted at young women and was available only in pink. The plastic in the phone was developed with a Japanese materials development company called Unitika, which produces a PLA plastic trademarked Terramac. Its melting point is 170C. Impact strength (ISO179 ) is 5.6.
Sony is also involved. Hiroyuki Mori, a senior eco-material engineer, says Sony is using several small components based on PLA, but is looking for higher performance. Sony’s studies indicate that a PLA-based polymer could reduce carbon dioxide emissions by 20 percent and non-renewable resource input by 55 percent compared to ABS.
In the U.S., the leading technology developer for engineering applications appears to be DuPont, which announced at NPE 2006 plans to develop plant-based grades of Sorona polytrimethylene terephthalate and Hytrel. elastomer using propanediol (PDO) derived from corn sugar. DuPont says its diol feedstock combined with its polymerization experience allows creation of a polymer with superior physical characteristics than competing bioplastics. The new Sorona will provide good stiffness and strength. Joe Kurian, the technology and business development manager for DuPont’s bio-derived technologies, says the new sorona has better surface appearance and gloss thanPBT polybutylene terephthalate.
Sorona Will Be Cost Competitive
The new Sorona grade will be a hybrid polymer, with about 37-40 percent of the content from renewable resources, such as corn. “I think we can go to 50-60 percent with the technologies that are available to use,” Kurian said in an interview with Design News. Target markets are automotive, appliances and connectors. Customers are testing the materials now. Commercial launch is expected before the end of the year. “Our goal is to provide products at prices that people can afford, not multiples of two or three times,” says Kurian.
No new investment in equipment or tooling will be required to use DuPont’s new Sorona, says Kurian. Sorona was introduced a few years ago as an oil-based material for textile and fiber markets. Feedstocks are being switched to the plant-based materials.
The physical properties of the new Hytrel grade will be very comparable to the current oil-based Hytrel. Biomaterials will vary 35 percent to 65 percent of the compound, depending on the grade.
With Tate & Lyle , DuPont has built the world’s largest aerobic fermentation plant in Loudon, TN for the production of bio-PDO. Capacity is 45,000 metric tons a year. Sorona polymer ispolymerizing Bio-PDOwith either terephthalic acid (TPA) or dimethyl terephthalate (DMT)at the DuPont plant in Kinston, NC. DuPont is expanding capacity in Kinston and in a plant in China.
In another development, Procter & Gamble and Kaneka are engaged in a joint development agreement to commercialize a polymer calledNodax H, which is a poly (3-hydroyxbutyrate-co-3-hydroxyhexanoate). P&G declined to comment for this article.
Here’s a Rundown of Other U.S. Players:
NatureWorks LLC (Minnetonka, MN)isa stand-alone company wholly owned by Cargill. Dow Chemical was a partner at one time. NatureWorks LLC says it is the first company to offer a family of commercially available greenhouse-gas-neutral polymers derived from 100 percent annually renewable resources with cost and performance that compete with petroleum-based packaging materials and fibers. The companies uses unique technology to process natural plant sugars into a polylactide polymer. The polymer is said to provide gloss and clarity similar to polystyrene, and exhibits tensile strength and modulus comparable to hydrocarbon-based thermoplastics. Target applications are various types of packaging. The company is in the early stages of establishing a recycling stream for bottles made from PLA. NatureWorks produces PLA at a plant (140,000 tons per year) in Blair, NB., and says it has reduced costs to be competitive with petroleum-based polymers such as polyethylene terephthalate (PET). NatureWorks supplies about 90 percent of the commercial polymer lactic acid market and has distribution agreements with other companies that produce polymers from PLA.
Metabolix(Cambridge, MA) is partnering with Archer Daniels Midland (ADM) to build a plant in Clinton, IA, to produce 110 million pounds of plastic based on polyhydroxybutyric acid (PHA). The Metabolix plasticsare produced from genetically engineered microbes. Much of the core technology isowned by the Massachusetts Institute of Technology and exclusively licensed to Metabolix. The MIT license covers 11 issued U.S. patents, one U.S. application and numerous foreign counterparts. In the future, Metabolix says its plastics will be produced in growing plants, making them cost competitive with plastic such as polyethylene.
Cereplasthas a compounding plant in Hawthorne, CA, with a capacity of 50 million pounds to manufacture PLA-based plastics made from corn and/or potato starch. Capacity is being quadrupled, partly in response to new state laws on the West Coast targeting litter waste. Market development has focused on disposable packaging such as foodware, but the company says its products may be used for mechanical design applications. At this time there are no such applications for the company’s polymers, which are best suited for applications where packaging can be disposed in a composting facility.
Novomer (Ithaca, NY) is working with Kodak to develop commercial plastics based on a technology developed by a Cornell University research team headed by Professor Geoffrey Coates. The company synthesizes aliphatic polycarbonates (APCs) using carbon dioxide as a raw material with either petrochemical epoxides or limonene oxide derived from citrus fruits.The Novomer APCs are biodegradable, biocompatible, are optically clear and provide high oxygen and water barrier. Potential applications include drug delivery, construction of flexible electronic screens using light-emitting devices, polymer-based electrolytes and polyurethane foams that are up to 40 percent by mass carbon dioxide. High-end applications are targeted because of the potential high cost of the polymer.
Medical Implants Often Disappear
Use of plant-based plastics is booming for medical implants, where the materials are often called bioresorbable.
Medical-grade PLA, which can cost around $2,000 a pound are used to make screws and anchors that attach tissue to bones. Use of the PLA avoids a second surgery to remove metal anchors. They are also impervious to X rays, allowing a better look at the healing process. Parts are usually produced by specialist molders such as Mar-Lee Industries in Fitchburg, MA, that leverage tooling know-how into best-possible use of the polymer.
Drug-eluting stents under development now feature use of a biroresorbable coating that disappears after drugs have been internally administered to a healing artery. Visionaries even hope to make the entire stent out of bioresorbable material.