Process Economics Program Report 227
1,3 Propanediol and Polytrimethylene Terephthalate (PTT)
Published: December 1999
As an engineering thermoplastic, polytrimethylene terephthalate (PTT) combines the rigidity, strength, and heat resistance of the polyethylene terephthalate (PET) resins with the good processability of the polybutylene terephthalate resins. Currently, nylon carpet fiber is known for its resiliency, but it does not accept a wide variety of dyes (limiting the colors that can be provided) and tends to generate static charges. PET carpet fibers can be easily dyed but have neither the extreme wearability nor the resiliency of nylon. PTT fibers, on the other hand, have the dyeability of PET and also are static-resistant. In addition, PTT fibers appear to have resilience and wearability equivalent to that of nylon.
The recent commercial availability of polymerization-grade 1,3-propanediol (PDO) allows commercialization of polypropylene terephthalate (commonly called polytrimethylene terephthalate, or PTT). PTT has recently been introduced in developmental quantities, and full-scale commercial facilities are now on stream with substantial expansions expected in the next few years by both Shell and DuPont. In addition to applications as an engineering molding and extrusion resin, PTT has remarkable properties as a fiber.
This report examines the technology and economics of producing both PDO and PTT.
Currently, DuPont (using Degussa technology) is producing PDO by hydration of acrolein and Shell is producing PDO by hydroformylation of ethylene oxide (EO). In addition, DuPont, in cooperation with Genencor, has a process under development to produce PDO from glucose (corn-based) using biosynthesis (fermentation).