Product Profile: Isophthalic acid



Strong PET growth is the driving force for PIA. However, excess supply continues to undermine the health of the sector and will take some years to be absorbed


Purified isophthalic acid (PIA) is mainly used as an intermediate in the production of unsaturated polyester resins, followed by polyester and alkyd resins (mainly for surface coatings) and inks, reinforced plastics and packaging applications. Its fastest growing application is as a comonomer in the production of polyethylene terephthalate (PET) bottle resins. PIA provides excellent hardness, corrosion and stain resistance, hydrolytic and thermal stability and low resin colour.


Overall global capacity continues to exceed demand significantly and material will be in oversupply for the foreseeable future, notes PCI Xylenes & Polyesters. Producers say Europe is fairly balanced in terms of installed capacity, but the US still has a large overhang of capacity with some excess also in Asia. World capacity stands at about 750 000 tonne/year, while global demand reached nearly 500 000 tonne last year.

Consumption continues to grow, mainly driven by the PET sector. Players say overall demand in Europe was up last year with consumption into PET up by 5-7%, while demand into the polyester and coatings sector stayed largely flat. Europe usually sources around 20 000 tonne/year of imported material, mainly from Asia which has been exporting quite significant volumes helped by the falling dollar.

Restructuring and rationalisation remain on the agenda. BP sold its 50% stake in AG International Chemical to partner Mitsubishi Gas Chemical last November. It also put its PIA business on the market early last year and says it is still actively discussing a sale. The plant in Geel, Belgium, is included but BP says it will continue to own and operate this unit under a toll manufacturing arrangement with the buyer, as the facility is on an integrated site.

Lonza’s plans to sell its polymer intermediates business failed on two successive occasions in 2002, first to PPM Ventures and then Bear Stearns Merchant Fund. Following a slump in profits, Lonza has decided not to sell the business in 2004 as planned.


European prices are around €960-1040/tonne delivered for large buyers. Producers announced an increase of €80/tonne in December and say they have achieved around €40-50/tonne. The US posted a 4 cent/lb rise taking large buyers to 45-51 cent/lb. In Asia, suppliers are reported to have realised a hike of about $80-90/tonne in quarter one after seeking an extra $100/tonne. Sources say margins need to be improved as they have shrunk during the last 12-18 months on the back of substantial rises in raw material costs.


PIA is produced by the catalytic oxidation of metaxylene in aqueous acetic acid. BP (Amoco) was one of the first companies to commercialise PIA technology, which can be used on either a dedicated plant or a ‘swing’ purified terephthalic acid (PTA) unit.

In the BP process, a mixture of acetic acid, water, metaxylene, catalyst and air are fed into a reactor. The resulting isophthalic acid is crystallised in situ to facilitate mechanical separation from the solvent. To further purify the acid, it is mixed with a solvent and preheated and the resulting solution is fed to a reactor. Again, the reactor effluent is crystallised and mechanically separated from the solvent. The purified acid is then dried and sampled for purity.

Lona applied its knowledge in trimellitic anhydride production to the liquid phase oxidation process that is used in its facility in Singapore.

Health and safety

PIA is a colourless, crystalline powder that is insoluble in cold water but soluble in oxygenated solvents and alcohol. It is combustible and finely dispersed particles will form explosive mixtures in air. Inhalation or ingestion can slightly irritate the eyes, skin and respiratory tract.


World demand for PIA is expected to rise at an annual rate of 6-8%, boosted by the fast-growing PET sector. PET demand is tipped to grow at about 8-9%/year in Europe driven by new markets in eastern Europe. The US and South America will also see PET consumption climb by 8-9%/year, while Asia will see growth at double-digit rates.

Demand into coatings and resins will see steady growth of up to 1-2% above GDP depending on the region. Global PIA consumption is forecast by PCI Xylenes & Polyesters to climb to nearly 700 000 tonne by 2009.

The market is expected to move into a more balanced situation in the next couple of years with excess capacity being absorbed in the next five years if strong growth persists.

Asia is the favoured location for a new plant and a swing PTA/PIA facility is planned by Taiwan’s Formosa Chemicals & Fibre. The 150 000 tonne/year PIA unit will be built in Loong-der, Taichung, and is scheduled to start operating in 2005,although it will not produce PIA for more than six months in a year.

Global isophthalic acid capacity, '000 tonne/year
Company Location Capacity
AG International Chemical Mizushima, Japan 120
Beijing Yanshan Petrochemical Beijing, China 36
BP Geel, Belgium 125
Joliet, Illinois, US 200
Eastman Chemical Colombia, South
Carolina, US
Interquisa San Roque, Spain 50
KP Chemical Ulsan, South Korea 60
Lonza Pulau Sakra, Singapore 70
Tuntex Tao-yuan, Taiwan 15