Nearly all purified terephthalic acid (PTA) is consumed in polyester production including polyester fibre, polyethylene terephthalate (PET) bottle resin and polyester film. For most grades of polyester used in textiles and food and beverage containers, it is more economical to use PTA than the alternative dimethyl terephthalate (DMT) intermediate.
The remaining PTA is used in making cyclohexanedimethanol, terephthaloyl chloride, copolyester-ether elastomers, plasticisers and liquid crystal polymers.
In Asia, the growth in PTA consumption has been driven by strong polyester fibre demand, which is the largest segment accounting for nearly two-thirds of global polyester demand. Polyester fibres are used to make fabrics for apparel and home furnishings such as bed sheets, bedspreads, curtains and draperies. They are also spun together with natural fibres such as cotton to produce a cloth with improved properties such as wrinkle resistance.
In North America and Europe, polyester fibre production has been stagnant or even declining as the textile industry has migrated to Asia. Here, the growth has been seen in the PET bottle resin market, which now accounts for just over 30% of global polyester demand.
The growth in PET resin has come mainly from the replacement of glass in soft drink and mineral water bottles. PET bottles have also found applications in more niche markets such as sports drinks, fruit juices and food products such as oils, sauces and dressings. However, beer packaging is largely an untapped market for PET with the main penetration confined to eastern and central Europe, in particular Russia.
Other PTA applications include coatings and composite materials, based on unsaturated polyester resins, and hot-melt adhesives.
Up until 2008, global PTA markets had been growing strongly at rates of around 6-8%/year. However, PTA demand in 2008 was hit by a downturn in polyester fibre and PET resin markets.
According to US-based consultants CMAI, polyester fibre demand was already decreasing in early 2008 as a result of inventory draw down. The economic recession and associated collapse in energy and feedstock prices resulted in a second wave of inventory reduction while retailers were also reducing stock in anticipation of lower consumer demand. In addition, there was increased use in recycled bottle resin as a feedstock in the staple fibre market to avoid the high cost of virgin raw materials.
The PET bottle resin market was also hit by both recessionary and non-recessionary factors. Consumers have switched more to discount retailers resulting in a shift from single serve beverages to lower priced bulk packages such as 2 litre bottles which use less PET per volume of liquid as well as multi-packed cans. There has also been a reduction in bottled water demand of 5% or more as consumers appeared to move back to tap water to reduce spending and their environmental footprint.
Non-recessionary impact on the PET market has been the reduction in the amount of resin used in bottles. CMAI notes that water bottle weights have fallen from 15g to less than 10g for 500ml bottles and this trend will continue into 2010. Consumers are also buying more energy drinks which are typically packaged in cans.
In North America, a combination of PET bottle weight reduction and lost bottled water demand will significantly reduce consumption of PET bottle resin per capita over the next few years. Only economic recovery and the conversion of further food packages to PET will allow per capita consumption to return to 2007 levels by 2013, estimates CMAI.
A major challenge facing the PTA industry is the growing overcapacity caused by huge capacity additions of nearly 9m tonne/year under development, mainly in China. Up to three PTA units could be started up in China by mid-2009 although two of these could face delays. In Europe, two plants are planned for start-up in 2010 – Artenius will commission a 700,000 tonne/year facility in Portugal and Poland’s PKN will start-up a 600,000 tonne/year plant.
Updated: May 2009. Sources: ICB Chemical Profile, 4 May 2009; CMAI 2009 World Petrochemical Conference, 25-26 March 2009, Houston, Texas.