Performance and application of THPC

THPC (Tetrakis(hydroxymethyl)phosphonium Chloride): Performance and Applications

1. Key Properties

Property Specification Significance

Chemical Formula C₄H₁₂ClO₄P Quaternary phosphonium salt structure

Appearance Colorless to pale yellow liquid (50-80% aqueous solution) Easy to handle and dilute

Reactivity Reductive, forms covalent bonds with cellulose/proteins Flame retardancy and durability

Solubility Miscible with water, alcohols; incompatible with h3 oxidizers Broad formulation compatibility

pH Stability Effective in acidic to neutral conditions (pH 3-7) Optimal for textile treatments

2. Primary Applications

A. Flame Retardant (Major Use)

Textiles:

Mechanism: Forms insoluble phosphate polymers in fiber matrices.

Efficacy: Achieves LOI >28% (Limiting Oxygen Index) on cotton.

Process: Pad-dry-cure (180-200°C), often with urea/NH₃ to enhance fixation.

Standards: Meets NFPA 701, EN ISO 15025 for fireproof fabrics.

Wood/Paper:

Impregnation for Class B1 flame resistance (GB 8624-2012).

B. Biocide & Preservative

Water Treatment:

Controls sulfate-reducing bacteria (SRB) in oilfield injection water (50-100 ppm).

Leather Tanning:

Prevents microbial degradation during storage (0.1-0.5% solution).

C. Specialty Chemical

Electroless Plating:

Reducing agent for nickel-phosphorus (Ni-P) coatings on metals.

Adhesives:

Improves wet-strength in paper/corrugated board.

3. Technical Guidelines

Textile Treatment Example:

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THPC (300g/L) + Urea (100g/L) + TMM (Trimethylolmelamine, 50g/L)

→ Pad fabric (70% wet pickup) → Dry (110°C) → Cure (160°C, 3 min)

Safety:

Corrosive: Use PPE (gloves, goggles) due to acidic pH (~2-3).

Formaldehyde Release: Curing emits HCHO; require ventilation.

4. Advantages Over Alternatives

Comparison THPC Ammonium Polyphosphate (APP) DecaBDE

Efficiency High (durable FR) Moderate (needs high loading) Banned in many regions

Durability Wash-resistant (>50 launderings) Leaches under humidity Persistent environmental toxin

Eco-Profile Releases formaldehyde Halogen-free Toxic bioaccumulant

5. Environmental & Regulatory Notes

Challenges:

Formaldehyde emissions require scrubbers in industrial settings.

Banned in eco-certified textiles (e.g., OEKO-TEX® Standard 100).

Alternatives:

THPS (sulfate salt version): Lower toxicity, used in oilfields.

Phytic acid: Bio-based but less effective.

6. Case Studies

Military Uniforms: THPC-treated fabrics pass vertical flame tests (ASTM D6413).

Oilfield Pipelines: 75 ppm THPC reduced SRB-induced corrosion by 90%.

Note: THPC remains dominant in heavy-duty flame retardancy but is being phased out in consumer textiles due to environmental concerns. For new projects, evaluate THPS or nanoclay-based systems as sustainable options.