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Polybutylene terephthalate (PBT) resins and polyethylene terephthalate (PET)
engineering resins are high-performance, high-molecular-weight materials that
can be converted into functional components and parts that are in turn used
in a diversified array of assemblies for automotive, electrical/electronic,
appliance and industrial equipment applications. PBT resins and PET engineering
resins share many of the same markets; however, at present PBT is consumed
in much larger volumes than PET for high performance applications.
During the 2001–2002 economic slowdown, which included declines in the
automotive and electrical/electronics markets, PBT and PET still managed to
register 1–3% annual growth except in Japan because of the severe downturn
in the electronics industry. The industry recovered nicely in 2003–2005,
especially in Asia. In Japan, consumption rose as a result of greater use of
PBT in the automotive sector, while in China, consumption increased as a result
of demand growth in the electronics industry. Total global consumption of PBT
polymer was about 625 thousand metric tons in 2005. Growth rates are expected
to remain highest in Asia, with more mature rates in North America and Europe,
as some customer base continues to migrate toward Asia. The overall global
market is expected to grow at an average rate of about 7% per year during the
forecast period. Growth in China is expected to average 10% per year, while
that in other areas of Asia, except Japan, is expected to be about 8% per year.
In Japan, average annual growth is expected to be about 5%.
Globally, the main applications for PBT are in electrical engineering (about
60%, which includes the use of electrical connectors for automotive) and the
automotive industry (around 30%). Automotive applications account for the largest
use in North America, Europe and Japan, while electrical/electronic applications
are most significant in Other Asia. Most (70–80%) PBT is compounded with
glass fiber and other materials to reduce costs and modify properties. About
15% of PBT is consumed in alloys, particularly with polycarbonate (PC) or PET,
although it can also be blended with elastomers. Most PC/PBT applications are
in automotive bumper systems where they are used for fascias and beams.
In recent years, the industry has been researching ways to become more environmentally
friendly as part of the global “green” movement. In mid-2006, DuPont
announced that it was going to make polytrimethylene terephthalate (PTT) engineering
thermoplastic from terephthalic acid (TPA) and propanediol (bio-PDO), which
in turn is made from renewable resources. Intended applications are in automotive,
electrical/electronic and other industrial parts. Also in mid-2006, GE announced
that it has developed a process for converting postconsumer PET bottles into
engineering plastics as replacements for PBT that have improved properties
over standard recycled PET waste. The level of raw material 1,4-butanediol
(BDO) required is less than with standard PBT production; thus emissions of
CO2 and consumption of oil are reduced, as well as disposal of postconsumer
PET bottles in landfills.
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