Phthalate plasticizers
Process Role: Esterification intermediate Critical Procurement / Engineering Parameters: Purity, water, maleic impurity, colour
TECHNICAL PROCUREMENT INTELLIGENCE
Phthalic Anhydride (PA)
Moisture-Controlled Intermediate Supply for Plasticizers, Alkyd Resins and Polyester Chemistry
Phthalic anhydride is an aromatic cyclic anhydride used as a major intermediate for plasticizers, alkyd resins, unsaturated polyester resins and specialty chemicals. It is supplied as flakes/briquettes or molten product. Moisture control is critical because the anhydride hydrolyses to phthalic acid, changing product condition and reaction stoichiometry.
For GCC and MENA buyers, technical suitability should be confirmed before shipment. OGSCM can coordinate specification review, manufacturer documentation, packaging format, batch traceability, dangerous-goods requirements where applicable, cross-border logistics and receiving-site constraints. Product claims such as food grade, pharmaceutical grade, oilfield grade, REACH/FCC/USP compliance or OEM approval should only be used when documented for the actual offered grade.
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Chemistry, Manufacturing Route & Material Behaviour
Industrial phthalic anhydride is produced mainly by catalytic gas-phase oxidation of o-xylene, historically also naphthalene, over vanadium-based catalysts. The hot reactor effluent is cooled to recover PA, which is then purified and supplied molten or solidified into flakes. Water converts PA to phthalic acid (C₈H₆O₄); although reversible on strong heating/dehydration, moisture ingress is undesirable because it alters handling, assay and downstream esterification/polycondensation behaviour.
Process-Engineering & Grade-Selection Considerations
- For resin/plasticizer manufacture, specify purity, molten colour, maleic anhydride and other oxidation by-products where process sensitive.
- Use dry storage and closed transfer; moisture ingress can create phthalic acid and caking.
- Molten PA service requires heated tanks/lines well above the melting point with suitable insulation and tracing, while avoiding hot spots.
- Solid flake handling should include dust control because PA can irritate/sensitise the respiratory tract.
- Package size should match charging equipment: 25 kg bags support manual/batch charging, while 500–1000 kg FIBC can reduce handling for bulk solids plants.
◎ Technical Specifications
| Property | Value |
|---|---|
| Formula | C₈H₄O₃ |
| CAS | 85-44-9 |
| Molar mass | 148.12 g/mol |
| Appearance | White flakes/solid or clear molten material |
| Melting point | ≈131°C |
| Boiling point | ≈284–295°C; can sublime |
| Solid density | ≈1.53 g/cm³ |
| Molten density | ≈1.20 g/mL around 150°C, representative |
| Transport | UN 2214; Class 8; Packing Group III under standard DG classification |
| Example shelf life | Polynt states 12 months for its product under specified storage conditions |
Values shown are reference/typical values, not a sales specification. Final acceptance must be based on the offered manufacturer grade, test method, COA and buyer specification.
Applications
Alkyd resins
Process Role: Polyesterification raw material Critical Procurement / Engineering Parameters: Purity, colour, anhydride value
Unsaturated polyester resins
Process Role: Aromatic anhydride component Critical Procurement / Engineering Parameters: Moisture, purity, batch consistency
Polyester polyols
Process Role: Intermediate for polyurethane-related polyols Critical Procurement / Engineering Parameters: Purity and functionality
Pigments/dyes/agrochemicals
Process Role: Specialty synthesis intermediate Critical Procurement / Engineering Parameters: Application-specific impurity limits
Storage, Handling, Materials Compatibility & HSE
Keep solid PA dry, sealed, cool and ventilated, protected from moisture and strong oxidisers. For molten storage, use purpose-designed heated systems with temperature control, insulation and appropriate relief. Prevent dust/vapour exposure and follow the current SDS. Because transport is regulated as UN 2214 in standard frameworks, verify package and mode-specific requirements before shipment.
HSE control principle:
Use the current product-specific SDS, local dangerous-goods requirements, receiving-site risk assessment and applicable engineering standards. Website text should never substitute for a supplier SDS or site procedure.
HSE control principle:
Use the current product-specific SDS, local dangerous-goods requirements, receiving-site risk assessment and applicable engineering standards. Website text should never substitute for a supplier SDS or site procedure.
RFQ Specification Checklist
- Solid flakes/FIBC or molten bulk
- Minimum purity and maximum moisture
- Maleic anhydride / colour limits if critical
- Packaging size and liner specification
- Molten storage/unloading temperature if bulk
- Batch COA and analytical methods
- UN 2214 dangerous-goods documentation and route requirements
Quality Control, COA Parameters & Test Methods
A technically meaningful RFQ should define the key quality parameters affecting process performance. Typical COA requirements include purity, anhydride/acid value, maleic anhydride content, molten colour, moisture, solidification point, and ash/residue, measured by suitable methods such as GC, titration, Karl Fischer, APHA/Hazen, ASTM, or supplier-standard methods.
These parameters control assay, reactive content, oxidation-related impurities, resin/product colour, hydrolysis risk, purity, and non-volatile contamination. Final testing requirements should be aligned with the producer specification, customer requirements, and intended application.
Why Choose OGSCM?
Application-Driven Solutions
We match the right grade to your process needs.
Reliable Supply Chain
On-time delivery with strong regional & global logistics.
Quality You Can Trust
Strict quality control and batch consistency.
Expert Support
Technical & commercial support throughout your procurement journey.
Regional Presence
Serving industries across GCC and MENA with local expertise.
Frequently Asked Questions
Water hydrolyses the anhydride to phthalic acid, changing product condition and reaction stoichiometry.
Yes. Industrial producers supply both molten and solid forms; the site must have compatible heated storage and transfer systems.
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