PLASTIC FROM PLANTS, NOT PETROLEUM

In Business, July-August, 2006, Vol. 28, No. 4, p. 19

Specialized start-ups and major companies are increasing the bioindustry that is using the microbial arena to produce and market green plastics.

Diane Greer

BIOPLASTICS are being produced from renewable resources - engineered to feel and perform like the “olde” petroleum-based output - and then decompose naturally when discarded. Scientists have utilized biotechnology and the processing ingenuity of Mother Nature to generate bioplastics from plants such as corn, potatoes and biomass residuals. The results show up in products like garbage bags, food containers, cutlery and mulch film.
Archer Daniels Midland is teaming with Metabolix to build a manufacturing facility producing bioplastics. Toyota is manufacturing car parts from bioplastic. And Motorola, NEC and Fujitsu are fashioning computer and cell phone cases from bioplastics.
“A confluence of factors - soaring oil prices, worldwide interest in renewable resources, growing concern regarding greenhouse gas emissions and a new emphasis on waste management - has created renewed interest in biopolymers,” said Dr. Donald Rosato, Senior Research Analyst with Frost & Sullivan.

POLYLACTIC ACID (PLA)
NatureWorks LLC, a subsidiary of Cargill, has refined a technique for producing a natural polyester, called polylactic acid (PLA). At a 140,000-ton/year plant in Blair, Nebraska, dextrose is fed to bacteria in a fermentation process producing lactic acid. Lactic acid, a naturally occurring monomer, forms in the cells of animals and microorganisms as the result of glucose metabolism. Lactic acid is then converted into a lactide in a condensation process, purified and polymerized to produce PLA.
“For cold food application, PLA is price competitive and performs equal to or better than some of the petroleum-based resins,” says Joe Selzer, Vice President of Marketing and Sales for Wilkinson Industries, a producer of PLA food containers. But the resin is not appropriate for hot applications, explains Selzer. “You can only go up to 105° to 114°F and then you would have some deformation in the product.”
Products packaged in NatureWorks PLA can be found at over 20,000 retail locations including the produce and deli departments at Wild Oats Markets and the produce section at Sam's Club. Biota is packaging spring water in the first molded bottles made of NatureWorks PLA.
Other companies are also producing PLA. Mitsubishi Plastics is manufacturing plastic film and sheets from PLA. NEC is using a PLA composite with kenaf fibers for laptop computer cases. And Toyota Eco-Plastic combines kenaf with PLA for use in door interiors.

MICROBIAL BIOFACTORIES
In the 1980s, scientists at MIT became intrigued with a peculiar bacteria that could store energy in the form of plastic rather than carbohydrates and lipids, explains Jim Barber, President and CEO of Metabolix. “As they investigated the organism, they discovered ways to harness the machinery of these organisms and improve it to produce plastic materials from renewable resources biologically.”
Based on their findings, Professors Anthony Sinskey and Dr. Oliver Peoples founded Metabolix. Using advanced biotechnology, they genetically enhanced bacteria by incorporating genes from other organisms. Each gene is programmed to carry out a specific step in a multistep process, which produces the building blocks of a natural plastic and assembles those building blocks within the cell, notes Barber.
Their microbial “biofactories” can now code upwards of nine genes from a number of different species to produce polyhydroxyalkanaotes (PHA) during a fermentation process. Sugars and vegetable oils are used in the fermentation feedstock.
Varying the nature and the relative proportion of the building blocks produced and assembled by the microbe can create a variety of PHA copolymers spanning a range of properties from rigid to highly elastic with a range of melting points, explains Barber. “They are suitable for films, fibers, adhesives, coatings, molded goods and a variety of other applications,” points out Rosato. They are also biodegradable and compostable in aerobic and anaerobic conditions and in marine environments.
Rosato believes PHA copolymers have the potential to replace up to 50 percent of the petrochemical based polymers used in packaging. Metabolix recently announced a 50/50 joint venture with Archer Daniels Midland (ADM) to build a 50,000 ton/year PHA manufacturing facility slated for completion in 2008.
Proctor and Gamble Chemicals is also working on commercializing PHA. It has developed Nodax™, composed of several grades of PHA polymers. The company has a licensing agreement with Kaneka, a Japanese company, to produce and commercialize a variety of products and packaging materials.

PLASTICS DERIVED FROM STARCH
The natural material most commonly utilized to create bioplastics is starch. Starch can be derived from agricultural crops including corn, wheat, potatoes, tapioca, rice and soy and is both inexpensive and plentiful.
EarthShell has created a biopolymer made from potato and cornstarch, limestone and water. Vince Truant, Chairman and CEO of EarthShell Corp., likens the manufacturing process to making waffles. The raw materials are mixed into a batter or slurry, poured into a mold and heated. The heated water turns to steam forming and setting the material. The resulting product is then coated with a protective barrier to provide water resistance and added strength. Both the product and the barrier coating are biodegradable in about two months, says Truant.
Although the EarthShell material can be made into a variety of products, the company is concentrating on the $30 billion food service disposable packaging market. Truant sees a growing, worldwide market and projects “environmentally advantaged products” to have a 20 percent market share in five to seven years.
The company has signed a licensing agreement with ReNewable Products, Inc. (RPI) to produce plates and bowls made from the EarthShell composite in a new manufacturing facility in Missouri. Under a similar licensing agreement, EarthShell Hidalgo will produce products for the Mexican market.
The low cost of EarthShell's primary raw materials offers an economic advantage, allowing the product to compete with products made from traditional petrochemical-based plastic, according to Truant. The products will compete in price and quality in the mid-range of the market. “That is where we will be competitive, where the volume is,” Truant concludes.

BIOPLASTIC SYNTHETIC BLENDS
Europe's largest producer of bioplastics is Novamont, which produces Mater-Bi. The company runs a 35,000-ton/year plant located in Italy. Mater-Bi is a blended bioplastics composed of starch (corn, wheat or potato) and synthetic polymers. The synthetic polymers are fully biodegradable despite being produced from nonrenewable resources. Different grades of Mater-Bi, for films/sheets, injection molding and foams, contain between 40 to 95 percent starch content with the remainder composed of various synthetic additives and complexing agents. One company making a range of products with Mater-Bi is BioBag.
BASF also produces a blended polymer called Ecovio, a plastic made from 45 percent NatureWorks PLA and 55 percent Ecoflex, BASF's existing biodegradable plastic derived from fossil resources. The new product was created to meet what the company sees as the growing demand for bioplastics.
Ecovio was developed to achieve new physical properties with biodegradable plastic products by combining two base products. “EcoFlex is a soft material with lower tensile strength and higher elongation,” explains Keith Edwards of BASF Corporation.
Ecovio is being used to make carrier bags (55% Ecoflex/45% PLA), such as grocery store bags, that are 100 percent compostable and 45 percent renewable, says Edwards. Blends of the polymers also can be injection molded (e.g., into plates and cups) and extruded into straws. BASF expects to have the capacity to produce 30 million pounds of EcoFlex in 2006; a new 6,000 ton/year plant is starting up in Germany. The company selected PLA because it is “plentiful, produced in large-scale volumes, has rigid properties and is less expensive than other renewable resins,” adds Edwards.

Diane Greer is a freelance writer and researcher based in New York, specializing in sustainable business, green building and alternative energy.

Copyright 2007, The JG Press, Inc.