Phosphoric Acid Flame Retardant Grade
Flame retardant grade phosphoric acid is a high-purity orthophosphoric acid used as an acid catalyst and carbon-source activator in intumescent coating systems, wood fire retardant treatments, and cotton textile finishing. It reacts with polyols and nitrogenous compounds at elevated temperatures to form a dense phosphate char that insulates the substrate from heat. Industrial 75–85% concentrations are commonly used for direct treatment of cellulosic materials or as a feedstock for manufacturing ammonium phosphate salts.
Technical Specifications
| appearance | Colorless to pale yellow liquid |
| arsenic (ppm) | <5 |
| heavy metals (ppm) | <10 |
| phosphorus content (%) | 24–28 |
| specific gravity (20°C) | 1.57–1.69 |
| phosphoric acid content (%) | 75–85 |
Applications
- Wood and timber fire-retardant pressure-impregnation treatments
- Cotton and cellulosic textile flame-retardant finishing
- Intermediate for manufacturing MAP, DAP, and APP flame retardants
- Acid source component in intumescent coating formulations
- Paper and cardboard fire-retardant treatment for packaging
Key Features
- High phosphoric acid concentration maximizes phosphorus delivery per unit volume for wood treatment
- Reacts with cellulose and polyols to catalyze char formation and inhibit combustion
- Low-cost and widely available FR raw material for manufacturing downstream phosphate FR salts
- Broad compatibility with nitrogen synergists (urea, melamine) in intumescent coating systems
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