DuPont Performance Polymers is working on development of whole new families of plastics based on renewable resources as part of an ambitious program to make more than half of its plastics and chemical monomers from renewable resources within the next 13 years.
DuPont, which invented many plastics such as nylon, “is looking at this (biotech plastics) as the next big wave,” said Richard L. Bell, DuPont Performance Polymers development manager, in an interview last week at NPE2015 in Orlando, Florida.
DuPont made its first major foray into bioplastics with the launch of partially corn-based Sorona polytrimethylene terephthalate (PTT) in 2006 using 1,3 propanediol (PDO) made in a production joint venture with Tate & Lyle. Sorona has been widely adopted in carpeting and textile markets because of performance features such as softness and crush resistance. According to biochemist John Craig Venter it is on track to become the first billion dollar biotech product other than a pharmaceutical.
A DuPont Performance Polymers spokesman said the percentage of its plastics currently made from renewable resources is “in the single digits”. Other commercial products include castor-based long chain polyamides (nylon) 6/10 and 10/10 as well as Hytrel RS elastomer.
The ambitious goal to make more than half of its plastics and chemical monomers from renewable resources was announced by DuPont in press conferences leading up to K 2013, the giant global plastics conference held every three years in Düsseldorf, Germany. Then Technology VP Lewis Manring said that the emphasis would be on chemical monomers that could be “dropped-in” as replacements for oil-based chemicals. He did not provide any specifics, citing confidentiality of the DuPont research.
Meanwhile, Bell said that the company will continue to work on drop-in bio-based chemical feedstocks, but they have assumed a lower priority than was the case two years ago. One reason is the collapse of oil prices. “They only make sense if you can lower cost. What they will give us is a supply chain option.” The focus at DuPont now is to develop biobased monomers and polymers that have technical advantages.
Industrial Biosciences is a major business unit at DuPont, and the segment has three primary strategies, according to a recent investors’ presentation. They are development of:
- Bioactives, such as enzymes for applications in laundry detergent, food, animal feed and ethanol production;
- Biomaterials, which includes “driving the scale” of Sorona and capturing “transformative new materials opportunities”; and
- Advanced biofuels.
DuPont’s 2014 Sustainability Report opens with this statement from Ellen Kullman, chair of the board & chief executive officer:
“DuPont is executing a plan to deliver higher growth and higher value for customers and shareholders by enabling greater food security and safety, creating high performance, cost-effective and energy efficient advanced materials across industries, and delivering renewably sourced bio-based materials and fuels.”
DuPont brought on line this year a cellulosic ethanol plant in Nevada, Iowa that uses corn stover as feedstock. Corn stover consists of waste husks, cobs, and other material left over from corn harvesting. The facility has a capacity to make 30 million gallons per year of fuel. It shows the direction that DuPont is moving for feedstocks—use of waste biomaterials rather than products that can be used as a food source.
The primary applications for the engineering versions of DuPont’s currently available bioplastics are in automotive.
Toyota’s hybrid vehicle, “Prius α” (Prius alpha), uses HVAC vent louvers made with Sorona EP, which is said to reduce warpage and improve surface appearance, allowing elimination of a paint step. That’s a cost saver and environmental benefit. Sorona EP contains between 20 and 37 percent renewably sourced material by weight. The difference in surface appearance is particularly noticeable with high glass loadings, which add stiffness.
Sorona was chosen as the material for the ceiling surface skin, sun visor and pillar garnish of Toyota’s new model, SAI, which is currently available in Japan.
The bio-based content of Hytrel RS thermoplastic elastomer can vary from 20 to 60 percent, depending on the grade. The bio portion contributes to softness. JV partner Takata-Petri of Aschaffenburg, Germany is using Hytrel RS for airbags.
Castor-based polyamide, which was originally developed by BASF scientists in the 1940s, boasts good chemical resistance and is often used in fuel lines.
The versions developed by DuPont in recent years have different chemistries and performance profiles. For example, Zytel RS 6/10 is used on an automotive radiator end tank from Denso Corp. The material was developed jointly by Denso and DuPont in a proprietary process. It contains 40 percent renewable content by weight derived from the castor bean plant, and meets requirements for heat resistance, durability and road salt resistance.
The main products in the DuPont Performance Polymers unit include Zytel nylon resins, Delrin acetal resins, Hytrel polyester thermoplastic elastomer resins, Tynex filaments, Vespel parts and shapes, Vamac ethylene acrylic elastomer and Kalrez perfluoroelastomer. Performance Polymers also includes the DuPont Teijin Films joint venture, whose primary products are Mylar and Melinex polyester films.