PURIFIED TEREPHTHALIC ACID (PTA)

PRODUCT DESCRIPTION

Terephthalic acid (TPA) is a precursor of polyethylene terephthalate, which is used in the production of polyester fibers, polyester films, PET bottle resins, and other polyester thermoplastic resins. The terephthalic acid contains both "purified" and "medium quality or QTA" grades. Purity is typically measured by the concentration of impurities such as 4-carboxybenzaldehyde (4-CBA) and paratoluic acid. High purity TPA typically contains very low concentrations of 4-CBA in the 5-20ppm range. Medium on QTA grades contain 4-CBA concentrations in the 50 - 200+ ppm range.

Physical Properties of PTA

Description                    White crystal or powder
Molecular formula           C6H4(COOH)2
Molecular weight            166.14 g/mol
Boiling point                  sublimes
Melting point                  402 oC, sublimes
Vapor pressure              Pa at  20 oC < 1
Solubility                       Insoluble in water, alcohol and ether. Soluble in other solvents, DMF, alkali

TECHNOLOGY/PROCESS/FEEDSTOCK

Most terephthalic acid is made by the BP (formerly, Amoco) process, Fiber-grade TPA is recovered by crystallization. The yield is 95% of theoretical.
A variation to Amoco’s process was developed by Invista (formerly DuPont-ICI), Dow Inca

(EniChem), Mitsubishi Chemical, Interquisa, and Mitsui. The product purity from these processes is not as high as that produced from the Amoco (now BP) process.
KoSa manufactures terephthalic acid by hydrolyzing DMT manufactured by the Witten process.
Several processes have been developed to produce TPA from toluene, but the processes are very complex and it is unlikely that any will be commercialized.
On an industrial scale, terephthalic acid is produced by oxidation of paraxylene by oxygen from air. Terephthalic acid can be formed in the laboratory by oxidizing para-diderivatives of benzene, or best by oxidizing caraway oil, a mixture of cymene and cuminol, with chromic acid.

The process is explained in brief in the Polyester Chain Report by Yarnsandfibers.com END USE AND DERIVATIVES

All the terephthalic acid is used in producing polyethylene terephthalate (PET), which in turn is used to make polyester fibers, bottle resins, film, and engineering resins. TPA is being increasing used in manufacture of polyester at the expense of DMT. Although terephthalic acid is favored over DMT in the production of certain types of polyester fibers (e.g., staple), no hard evidence has proven that terephthalic acid results in better-quality fibers. DMT is typically used in producing polyester fibers and films.

Other minor terephthalic acid uses include production of aramid fibers, polyacrylate resins, liquid crystal polymers (LCP), and specialty polyesters.

New derivatives and uses for terephthalic TPA include polytrimethylene terephthalate (PTT) Corterra polymers and polybutylene terephthalate (PBT). For PBT manufacturing, Terephthalic acid has become the preferred feedstock over DMT for new plants.

INDUSTRY STRUCTURE

The top 10 largest producers of PTA worldwide account for over 60% of world capacity. The following table lists them in the order of their capacities worldwide: The top two producers BP Group and Samsung together control more than 20% of global ethylene capacity.

The entire Industry Structure with the statistical data about the trade of PTA is covered in the Polyester Chain Report by Yarnsandfibers.com This includes, country-wise production, export, import, consumption with the market share.

Polyester Chain Report by Yarnsandfibers.com is available for online purchase.

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Price Trends of PTA –

The current prices and the trends are published weekly in the YnFx PriceWatch Report, which covers 22 textile products, starting from feedstock till yarn, and tracks the international price movement on a weekly basis.

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