The Greening of an Industry: Suppliers pouring into ‘green’ plastics

Using ethane derived from 100% renewable resources, Brazilian petrochemical firm Braskem has announced the creation of a biobased high-density polyethylene (HDPE), applying sugar-cane ethanol as a feedstock. Braskem is just one of many suppliers to have recently announced Green projects.

Targeting commercial production by 2009, Braskem reports investing $5 million on the project, including the creation of a pilot unit at Braskem’s Technology and Innovation Center that’s already producing unspecified amounts of the material. Braskem’s goal is industrial-scale production with a potential annual capacity of 200,000 tonnes. The company has not decided on the site’s final design or location. According to the Earth Policy institute, sugar-cane derived ethanol accounts for 40% of the fuel sold in Brazil. The country led the world in ethanol production in 2004, distilling 4 billion gallons, followed by the U.S. with 3.5 billion gallons of corn ethanol distilled. That number will likely increase thanks to an emphasis placed on the fuel by U.S. President Bush.

As reported in the First Look section of our September issue, Dow Chemical (Midland, MI) signed an agreement with Crystalsev, one of Brazil’s largest ethanol producers, to produce PE from sugar cane. Under terms of that agreement, the companies will design and build a 350,000-tonnes/yr-capacity solution PE plant set to open in 2011 using ethanol derived from sugar cane rather than naphtha or natural gas liquids to manufacture Dowlex-brand grades.

NatureWorks (Minnetonka, MN), which is fully owned by Cargill, has used corn sugars to create a biobased polylactic acid (PLA) material from a site in Blair, NE, with that material mirroring styrenics in mechanical properties. Biobased competitor Telles, the joint-venture business of Metabolix (Cambridge, MA) and Archers Daniels Midland, launched a line of bioresins a few months ago based on polyhydroxyalkoanate (PHA), with those materials behaving more like polyolefins. The same week Braskem announced its ethanol-based HDPE, Telles introduced three new grades of its PHA Mirel resin, with two for injection molding and one for paper coating.

Biodegradable foam on the way

Almost 10 years ago, Germany’s BASF (Ludwigshafen) launched a biodegradable line of aliphatic-aromatic copolyesters, targeting film products, called Ecoflex. Its Ecovio sister product is based on fully renewable raw materials and is composed of 45% PLA by weight. This month at the K show in Düsseldorf, Germany, BASF officials will be able to discuss one of the supplier’s new projects, Ecovio L Foam, a compound of Ecoflex and PLA with a PLA content of more than 75% by weight. Ecovio L Foam was still in the experimental stage this summer but BASF’s Florian Krückl, marketing and sales manager for biopolymers, said first laboratory samples should be available at the K, with a planned market introduction for the material in mid/late 2008.

Ecovio L is for production of biodegradable foams, making it a potential heir apparent to the polystyrene foam containers formerly so commonplace in fast-food restaurants. It will be marketed as granulate that, with no further additives or mixing, can be directly expanded using extruded polystyrene foam (XPS) processing equipment, and then thermoformed into clamshells or other shapes. XPS processors won’t need to invest in new equipment to process the material, says BASF.

The number of suppliers of PLA is on the rise, with lactic-acid producer Purac saying it now offers compounded PLA that withstands temperatures above 175°C, a key threshold the company says will allow applications in hot-fill bottles, microwaveable trays, and even electronics or automotive components. A division of CSM (Diemen, Netherlands), Purac’s D- and L+ PLA use lactides as a monomer in resin production, which the company says will lower costs and promote PLA growth.

Purac Biomaterials already produces and markets 18 grades of Purasorb PLA materials for bioabsorbable medical devices, and 12 grades for drug-delivery systems. The company began work with lactic acid in 1935, producing the chemical via sugarbeet fermentation. Today, it manufactures most of its basic products by fermenting carbohydrates from sugar cane, sugarbeets, corn, and wheat.

The company says production costs have doubled over the last two years, with the carbohydrate prices up 40-60% on the basis of increasing demand of crops like corn for bio-ethanol. The company is also reportedly investigating investments to meet future demand. The biomaterials unit, which has a dedicated manufacturing site at Gorinchem, Netherlands, opened in 2000, and in 2002, polymer production capacity was doubled.

Also, researchers at the Pacific Northwest National Laboratory (PNNL; Richland, WA) reported in the journal Science a breakthrough in converting common sugars, fructose and glucose, directly into fuel and polyester building blocks. The simplified conversion process, which could apply readily available biomass, generated products with very little residual impurities. Working with the PNNL’s Institute for Interfacial Catalysis, lead researcher Z. Conrad Zhang created hydroxymethylfurfural (HMF) in high yields directly from glucose, which the researcher says is nature’s most abundant sugar, present in plant starch and cellulose.

Past efforts had resulted in a low yield of material, and byproducts like levulinic acid that required expensive purification processes. Working with Haibo Zhao, John Holladay, and Heather Brown, Zhang and his team generated HMF yields of around 70% from glucose and almost 90% from fructose, accompanied by what they described as only trace amounts of acid impurities.

Instead of acidic catalysts, metal-chloride catalysts in a solvent were used, creating an ionic liquid where the metal chlorides converted the sugars to HMF. In an additional benefit, the ionic liquid can be reused. Chromium chloride was the most effective metal, converting sugars at a temperature of 100°C.

Spartech sheet based on renewable resources

Spartech Corp., headquartered in St. Louis, extrudes this family of sheet, dubbed Rejuven8, from NatureWorks-brand polylactic acid. Spartech’s first two materials in this new product family are Rejuven8 and Rejuven8 Plus. The former was specifically developed for thermoforming applications, and offers strength comparable to that of general-purpose acrylic.

Rejuven8 Plus sheet is a strength-modified grade with impact properties similar to polyethylene terephthalate (PET). Typical applications for the white, opaque Rejuven8 Plus include consumer packaging, gift and phone cards, and plant tags. Cards using these materials were commercialized last year in the U.S.

According to Spartech, it has developed a secondary processing step that can raise heat resistance to well over 200ºF, almost double the maximum temperature resistance of standard PLA grades.

Both sheet grades are primarily (99% and 95%, respectively) based on annually renewable materials such as corn, and meet the ASTM D6400 standard for biodegradability of plastics.