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Using renewable resources to produce unsaturated polyester resins may not be a new idea, but bringing the idea to reality took more scientific effort than what even U.S. automotive innovator Henry Ford could have imagined in 1921 when he dreamed of making every part of a car, except for the chassis and engine, from soybean.
(Published on January - February 2008 – JEC Magazine #38)
SARA FRATTINI, MARKETING TRANSPORTATION ASHLAND INC.
The war drastically shifted research efforts to the more readily available synthetic petrochemical derivatives, but now the focus is back on renewable resources.
Recent improvements in seed genetics, seed oil extraction, new conversion technologies and separation methods are making renewable materials a viable alternative to the limited petrochemical resources. In the late 1990s, Ashland, in cooperation with United Soybean Board and John Deere Corporation, began exploring new uses for soybean. John Deere was seeking to incorporate soybean into the plastics for their farm equipment while reducing productions costs (Figure 1). This resulted in the development of the Envirez® unsaturated polyester resin line, based on the use of renewable resources.
Novel biomass-based furan resins
The Envirez 1807 unsaturated polyester resin is produced using 25 wt.% of grain-derived organic (GDO) raw materials coming from soybean oil and corn-derived ethanol. GDOs are reacted with other materials using Ashland’s “high maleate” process (Figure 2).
This new, innovative patented process uses low reactivity soybean oil to produce a highly reactive resin, resulting in about 89-92% isomerization.
A carboxylic acid with at least two functional groups, or its anhydride containing ethylenic unsaturation, is first reacted with a saturated, monohydric alcohol with a boiling point under 150°C to form a half ester of the carboxylic acid or of the corresponding anhydride.
The half ester is then reacted with a polyol in a condensation reaction (Figure 3). In addition to the polyol, an oil containing unsaturations, such as soybean oil, is introduced at this point. Up to 45% of such oil can be used. This method makes it possible to prepare low-viscosity, low-acid-value resins that are more soluble in styrene than standard UP resins while retaining good performance characteristics. Their higher solubility in styrene reduces the amount of styrene required to prepare a styrene resin solution.
The final result is a polyester resin that behaves like a traditional unsaturated polyester resin. The main features of the Envirez 1807 resin are described in Table 1.
The Envirez resin products were developed for sheet moulding compounds (SMC), bulk moulding compounds (BMC), noncorrosion- resistant filament winding, resin transfer moulding (RTM), infusion and pultrusion applications, thus providing a drop-in replacement for petroleum-based resin products. Table 2 describes a typical SMC formulation and Table 3 draws a comparison between an SMC made with a PGmaleate resin and the Envirez 1807 resin.
The resin has proven to behave effectively with the most commonly-used low profile additives, such as polyvinylacetate, polymethylmetacrylate and saturated polyesters.
* Cold part / cold mold
Growing market acceptance
Envirez 1807 is widely used in the agricultural, construction, marine and transportation industries.
The demand for Envirez resin products has increased substantially over the past two years, especially in the consumer market, which has experienced a growing demand for “green” products. Many factors have contributed to the market acceptance of renewable resource-based resins for composites applications. Research has shown a growing public interest in the future of our environment. Many articles have covered the issue of global warming as related to an increased presence of CO2 and other greenhouse gases in the atmosphere. Lastly, there are increasing concerns regarding the depletion of natural oil reserves and the dependence on oil from politically unstable countries.
Calculations demonstrated that 17,000 kg of Envirez 1807 resin save 10 barrels of crude oil when compared to a standard PGmaleate resin. The saving is based on the net energy consumed in manufacturing as well as farming and processing soybean and corn into oil and ethanol respectively. The same batch of resin is estimated to remove 15,000 kg of carbon dioxide (CO2) from the atmosphere.
As oil becomes more expensive (the price of oil-derived chemicals has increased two fold over the past three years), bio-based products will be the future of the chemical industry. Chemicals derived from biomass currently account for 8% of the chemical industry’s production, but this figure is projected to reach 20% by 2010-2015. The technology involved in the manufacture of bio-based products is developing rapidly. Advancements in bio-catalysis and computer modelling will drive this change, and the bio-products sector is projected to reach $300 billion by 2015-2020.