Biopolymers: A brief biography

A decade ago, in a plastics environment dominated by traditional petrochemical-based resins, bioplastics may have seemed like a corny idea. However, producers and compounders of biodegradable polymers have come forward with improved formulations and industry standards that have legitimized the sub-industry in recent years. Combined with the growing interest in environmental responsibility, biodegradable resins have become an emerging force in the plastics business.

For instance, in an attempt to cut down on household waste generated in Toronto, one city councillor took aim at plastic grocery shopping bags. In a province where nearly 2.5 billion plastic bags are in circulation, a move to eradicate or tax bags could have an enormous impact on the blown film sector. Wal-Mart also recently announced the introduction of a supplier scorecard system to ensure the use of less and “greener” packaging.

APPLYING, SETTING STANDARDS

Additionally, stakeholder associations have been working to standardize the bioplastics industry. The Biodegradable Plastics Institution (BPI) in New York has developed a “COMPOSTABLE” label for all products and resins that meet ASTM D6400 “Specifications for Compostable Plastics” or ASTM D6868 “Specification for Biodegradable Coatings on Paper and other Compostable Substrates” compostability standards based on independent testing. Most of the resins profiled below follow these standards, and decompose within the requirements set out by the protocols.

Given these emerging trends and technologies, it is important to know the commercialized product lines of the leaders and major players in the bioresins business.

Cargill’s Minnetonka, Minn.-based NatureWorks LLC has set the standard when it comes to polylactic acid (PLA) polymers, which are made primarily using cornstarch. NatureWorks LLC has 19 commercially available grades of PLA, and the grades have been used for applications in everything from thermoformed packaging to injection and compression molding.

Other resin makers often use NatureWorks LLC’s PLA polymers to create compounded formulations. Processors also have access to a growing range of additives and copolyesters by companies like BASF and DuPont that help improve the flexibility and usability of PLA.

NatureWorks LLC’s facility in Blair, Neb. has a nameplate capacity of 300 million pounds of PLA a year, and the lactic acid plant located next to the polymer plant has a nameplate capacity of 400 million pounds a year.

BIG PLAYERS ENTER THE SCENE

DuPont has also thrown its hat into the ring for bio-based resins. DuPont Engineering Polymers announced the bio-based Sorona polymer and Hytrel made with renewable resources in June last year. Sorona is a unique polymer based on Bio-PDO, which is a replacement for petrochemical-based 1,3-propanediol (PDO) and/or 1,4-butanediol (BDO). Hytrel made with renewable resources will be produced using a new DuPont polyol made with Bio-PDO.

Sorona has exhibited performance and molding characteristics similar to polybutylene terephthalate (PBT), making it a good fit for automotive parts and components, electrical and electronic systems, and industrial and consumer products as well. Meanwhile, preliminary comparisons of Hytrel made with renewable resources to current Hytrel show improvements in properties, such as temperature range and elastic recovery.

Sorona will be available mid-2007, and Hytrel with renewable resources will be available in the fourth quarter of the year.

DuPont Packaging also introduced two grades of Biomax Strong, an additive that improves the performance of bio-based PLA packaging. The petrochemical additive improves the toughness and reduces the brittleness of traditional PLA materials. Biomax Strong 100 was developed fr use in packaging where no regulatory food compliance is necessary, and Biomax Strong 120 was developed to comply with food contact regulatory requirements.

Hawthorne, Calif.-based Cereplast, Inc. got its start as a research & development company, and now specializes in starch-based resins. Unlike polymer creators, Cereplast’s 100 per cent bio-based resin formulations are based on combinations of different polymers. The starting commodities for Cereplast’s resins are starches, mainly derived from wheat, potatoes and corn. The starch is then compounded with polymers like PLA from NatureWorks LLC and other bio-based materials. The unique formulations allow processors to run Cereplast on traditional equipment with ease, and the final products are also less brittle and have higher thermal resistance.

Cereplast resins are competitively priced, and company CEO Frederic Scheer notes that there is a lower likelihood of price fluctuations. Because of the resins’ formulations, Cereplast’s line of resins doesn’t depend on a single renewable resource. Scheer also estimates that Cereplast saves on production costs, because running the product on traditional equipment does not require as much energy or heat as petroleum-based resins.

The company currently has 14 commercially available resins for applications in thermoforming, injection molding, blow molding and extrusion. The major applications of Cereplast’s resins have included thermoforming in food packaging, thermosheets for use in the cosmetic industry and solo thermoforming extrusion coatings for paper coffee cups.

Before the end of 2007, Cereplast plans to release a foam grade that is a viable substitute for expanded polystyrene (EPS) foam. The company also hopes to be at a production capacity of 1 billion pounds within five years.

JOINT VENTURES

Cambridge, Mass.-based Metabolix, Inc. has announced plans to build a factory in Clinton, Iowa with their joint venture partner Archer Daniels Midland (ADM). The move will allow Metabolix to put its fermentation-based polyhydroxyalkanoates (PHA) into commercial production. Startup of the new plant is planned for 2008. The resins and join venture busines, which are set to be branded in the second quarter of 2007 are designed for use in packaging, paper coating, and films or bags. The new facility is expected to increase PHA production in the U.S. by 110 million pounds. Startup of the new plant is planned for 2008.

PHA is also particularly of note because it is more easily biodegradable than PLA-based polymers currently available on the market. In addition to hot composting, Natural Plastic will also completely decompose in soil, municipal waste treatment, water, and home and industrial composts. It also has higher temperature resistance.

Novamont N.A., based in Ridgefield, Conn., represents an Italian company that has become a leading provider for starch-based biodegradable resins in the European markets. The company sells various grades of biodegradable resins in granular form under its Mater-Bi trademark. To help keep up with demand for these resins in North America, Novamont has a warehouse in New Jersey and partner companies that process products to supply the current needs.

Area manager Tony Gioffre says the company is mainly focused on plastic bagging and organic source separation in North America.

“The primary objective in North America is to work with producers of bags, to work with municipalities,” said Gioffre. “To have biodegradable packaging and to put it into a landfill makes little sense, biodegradable products should end up in composting so the only way to do this is to establish a system.”

Mater-Bi resins have also been used in cutlery and other injection grade products and mulch film. Additionally, the firm partnered with Goodyear to produce a biofiller for tires that reduces rolling resistance and increases fuel efficiency.

Last November, Novamont also announced the release of Origo-Bi, a polyester that is produced using vegetable oils.

Paris, France-based Arkema Inc.’s Technical Polymers division has produced the Rilsan polyamide 11, a polymer that is produced using renewable castor beans. Rilsan 11 has bee
n offered for over 50 years, and exists in many demanding applications worldwide. Rilsan PA 11 is supplied in powder or pellet form, and Rilsan’s PA resins can be used in injection molding, extrusion, blow molding or rotomolding.

Japan-based electronics company Fujitsu recently qualified the high-performance polymer for use in personal computer and mobile phone components. Rilsan PA 11 is also registered as a bio-based polymer by the Japan Organics Recycling Association (JORA), for specific components that require high resistance to repeated bending and excellent molding performance.

Heritage Plastics, which is based in Picayune, Miss., produces HB956N1 resins for the manufacturing of compostable bags and films. HB956 is a pelletized compound based on a blend of bioresins, including an aliphatic/aromatic co-polyester. These resins are intended for use in applications that require low-density and high molecular weight high-density polyethylene.

BASF has been highly successful with Ecoflex, an aliphatic aromatic copolyester. The petrochemically-based product can be used for compounding or on its own. The ASTM D6400-certified product makes starch- and PLA-based packaging more usable.

“People do look for products with renewable content, and [Ecoflex] also changes some of the characteristics,” said BASF Canada market development manager Robert Armstrong.

Ecoflex can also be used as a mono-application in the area of flexible films, whether it is for extrusion coating or blown film. The product processes very similarly to low-density polyethylene, and has great wet- and tear-resistance.

BASF has also developed Ecovio, a biodegradable plastic that is still in the trial stages. The product is composed of BASF’s Ecoflex and NatureWorks LLC’s PLA in almost equal parts, and allows for additional applications such as blow molding.

With the growing range of bio-based and biodegradable products becoming available on the market and the pressure for change from the supplier segment, bioresins have become an essential consideration for any plastics processor.

REFERENCE LIST

Arkema Canada Inc. (Oakville, Ont.); www.arkema.ca; 905-847-4767

BASF Canada (Mississauga, Ont.); www.basf.com; 1-866-485-2273

Cereplast Inc. (Hawthorne, Calif.); www.cereplast.com; 310-676-5000

E.I. du Pont Canada Company (Mississauga, Ont.); www.plastics.dupont.com; 1-800-387-2122

Heritage Plastics, Inc. (Picayune, Miss.); www.heritage-plastics.com; 1-800-245-4623

Metabolix, Inc. (Cambridge, Mass.); www.metabolix.com; 617-492-0505

NatureWorks LLC (Minnetonka, Minn.); www.natureworksllc.com; 1-877-423-7659

Novamont N.A. (Ridgefield, Conn.); www.novamont.com; 203-438-5904