Product
Phthalic Anhydride
High-purity phthalic anhydride (PA, CAS 85-44-9), produced in Schwechat, Austria. Available as flakes or molten product, with a minimum purity of 99.8%.
Substance Identity
- Chemical name
- Benzene-1,2-dicarboxylic anhydride (1,3-phthalandione, isobenzofuran-1,3-dione)
- CAS number
- 85-44-9
- Molecular formula
- C₈H₄O₃
- Molecular weight
- 148.11 g/mol
- Appearance
- White flakes or transparent melt
- Delivery forms
- Solid flakes (bags / big bags) or molten product (heated tank trucks)
Phthalic anhydride (PA) is a colourless solid at room temperature, occurring as needles or platelets with a monoclinic or rhombic crystalline structure. The compound was first described by Auguste Laurent in 1836 and has been produced commercially since 1872, when BASF started industrial production.
ATMOSA Petrochemie GmbH has produced phthalic anhydride in Schwechat, Austria, since 1995. Our product is supplied either as solid flakes or as a molten (liquid) product delivered in heated tank trucks.
Applications
Phthalic anhydride is a key intermediate for a wide range of industrial products:
Plasticizers (about 50% of demand)
The primary use of phthalic anhydride is as a chemical intermediate in the production of plasticizers for polyvinyl chloride (PVC). Phthalate plasticizers improve the flexibility, transparency, durability and longevity of plastics used in cables, pipes, hoses, footwear and packaging films.
Alkyd Resins (about 22%)
Alkyd resins made from phthalic anhydride are employed in solvent-based surface coatings such as paints and varnishes for architectural, machinery, furniture and fixture applications.
Unsaturated Polyester Resins (about 13%)
Unsaturated polyester resins based on phthalic anhydride are usually blended with glass fibres to produce fibreglass-reinforced plastics. Typical applications are found in the construction, furniture, marine and transportation sectors.
Further Applications (about 15%)
Phthalic anhydride also serves as a raw material for polyester polyols for polyurethane insulation foams, pigments, dyes, pharmaceuticals and flame retardants.
How We Produce Phthalic Anhydride
Our plant in Schwechat converts ortho-xylene into high-purity phthalic anhydride in a continuous process:
- Raw material handling: Ortho-xylene is delivered by rail tank car via the plant railway system of the Borealis industrial complex and stored after laboratory release.
- Catalytic oxidation: The ortho-xylene is oxidised in the vapour phase in catalyst-filled multi-tube reactors. The reaction heat is recovered as high-pressure steam, which significantly reduces our primary energy demand.
- Crystallization: The reaction gases are cooled and the crude PA is deposited in crystal separators.
- Distillation: The crude PA is purified by two-stage distillation. Residues are incinerated internally and never leave the plant as product.
- Filling and packing: Pure PA is either loaded as a melt into heated tank trucks (up to 35 per week) or solidified on cooling rolls, flaked and automatically packed into bags and big bags.
Environment, Safety and Quality
ATMOSA is certified to ISO 14001 and operates under strict Austrian and EU environmental regulations. A catalytic after-burner treats the tail gas to minimise emissions, and continuous emission monitoring is in place for all regulated parameters. The plant operates under ATEX-certified conditions with regularly reviewed process hazard analyses (HAZOP) and functional safety assessments (SIL). Rigorous in-process and final product control ensures consistently high purity and a low colour index. We provide full batch traceability and are open to customer audits.
Quality Specifications
Specification of ATMOSA phthalic anhydride according to our technical data sheet (Revision 29). Download the TDS as PDF.
| Parameter | Specified value | Typical value / range | Testing method |
|---|---|---|---|
| Phthalic anhydride content | min. 99.8 % | 99.85 % | Gas chromatography |
| Solidification point | min. 130.8 °C | 130.90 to 131.00 °C | ASTM D 1493-67 |
| Phthalic acid content | max. 0.05 % | 0.01 to 0.03 % | Acid-alkalimetry |
| Maleic anhydride content | max. 0.05 % | < 0.005 % | Gas chromatography |
| Benzoic acid content | max. 0.05 % | 0.01 to 0.03 % | Gas chromatography |
| Phthalide content | max. 0.05 % | 0.02 to 0.05 % | Gas chromatography |
| Color number (liquid material) | max. 20 Hazen | 10 to 20 Hazen | ASTM D 3366-80 / ISO 1389/II |
| Heat stability (liquid material) | max. 40 Hazen | 20 to 40 Hazen | ASTM D 3366-80 / ISO 1389/III |
Packaging
From 25 kg paper bags to 1000 kg big bags, plus molten PA in heated tank trucks.
MSDS & TDS
Safety data sheets in four languages, exposure scenarios and the technical data sheet.
REACH
Fully registered: No. 01-2119457017-41-0019, band > 1000 t/a, since 2010.
Frequently Asked Questions
What is phthalic anhydride and what is it used for?
Phthalic anhydride (PA, CAS 85-44-9, C8H4O3) is an organic compound that is a colourless solid at room temperature, supplied as flakes or as a molten product. It is primarily used as a chemical intermediate in the production of phthalate plasticizers for PVC, unsaturated polyester resins for fibreglass-reinforced plastics, and alkyd resins for surface coatings. Further applications include polyester polyols, pigments, dyes and flame retardants.
What is the specification of ATMOSA phthalic anhydride?
ATMOSA phthalic anhydride has a minimum purity of 99.8 % (typically 99.85 %) and a solidification point of at least 130.8 °C. The impurities phthalic acid, maleic anhydride, benzoic acid and phthalide are each limited to a maximum of 0.05 %. The colour number of the liquid material is max. 20 Hazen and the heat stability max. 40 Hazen. Full details are available in our technical data sheet (TDS).
In which forms and packaging is phthalic anhydride supplied?
ATMOSA supplies phthalic anhydride as solid flakes or as a molten (liquid) product. Flakes are packed in 25 kg paper bags on CP1 pallets (1000–1625 kg per pallet) or in anti-static big bags of 500 kg and 1000 kg. Molten PA is delivered in heated tank trucks.
Is ATMOSA phthalic anhydride REACH-registered?
Yes. Phthalic anhydride from ATMOSA Petrochemie GmbH is registered under the European REACH regulation (EC) No 1907/2006 with registration number 01-2119457017-41-0019, registered on 26 November 2010 in the highest tonnage band of more than 1000 tonnes per year. The European Chemicals Agency (ECHA) has completed the completeness check pursuant to Article 20(2).
Where is ATMOSA phthalic anhydride produced?
All ATMOSA phthalic anhydride is produced at our plant in Schwechat, Austria (Danubiastrasse 21-25, 2320 Schwechat), directly southeast of Vienna. The plant is located within the Borealis industrial complex and was built in 1968 by Chemie Linz, an affiliate of OMV. The site has produced phthalic anhydride continuously ever since; ATMOSA has operated it since 1995.
Where can I download the MSDS and TDS for phthalic anhydride?
Material safety data sheets (MSDS) for phthalic anhydride flakes and liquid PA are available in English, German, Italian and Polish in the download section of this website, together with the exposure scenarios (ES) and the technical data sheet (TDS). For certificates of analysis or further documentation, please contact office@atmosa.at.
What is the production capacity of ATMOSA?
ATMOSA has an annual production capacity of 50,000 tonnes of phthalic anhydride at its plant in Schwechat, Austria. Roughly 70% is delivered as molten PA in heated tank trucks (up to 35 truck loadings per week) and about 30% as flakes in bags and big bags. The site within the Borealis industrial complex has its own rail connection and direct road access, supporting reliable Europe-wide logistics.