Flame Retardants
REACH
Tetrakis(hydroxymethyl)phosphonium sulfate
CAS Number
55566-30-8
EC Number
259-709-0
Abbreviation
THPS
What is Tetrakis(hydroxymethyl)phosphonium sulfate?
Tetrakis(hydroxymethyl)phosphonium sulfate (CAS 55566-30-8), commonly known as THPS, is a water-soluble organophosphorus biocide and flame retardant. Also marketed as Retardol S and Pyroset TKO.
Where is Tetrakis(hydroxymethyl)phosphonium sulfate used?
- Water treatment: controls sulfate-reducing bacteria and biofilm in oilfield injection systems, cooling towers, and industrial process water
- Textile and nonwoven: durable flame retardant finish for cotton and cellulosic fabrics, bonding to fiber during curing
- Leather processing: biocide during hide preservation and wet-end operations
- Personal care: preservative active against bacteria and fungi
- It delivers broad-spectrum antimicrobial activity alongside durable flame retardancy in treated substrates.
Commercial specifications
- Aqueous solution, typically 75% active content
- Select grades meet specifications for cosmetic preservation use
- Packaging: drums and intermediate bulk containers (IBCs)
Other Names (Synonyms)
Retardol S|Pyroset TKO|Octakis(hydroxymethyl)phosphonium sulfate|NCI-C55050|Phosphonium, tetrakis(hydroxymethyl)-, sulfate (2:1) (salt)|Phosphonium, tetrakis(hydroxymethyl)-, sulfate (2:1)|THPS
What are the physical properties of Tetrakis(hydroxymethyl)phosphonium sulfate?
Melting Point -35°C
Boiling Point 111°C
Density 1.41 g/cm³ @ Temp: 20 °C
Flash Point 96 °C
Color Colorless to Almost colorless
Form liquid
Water Solubility >=10 g/100 mL at 18 ºC
Vapor Pressure 0Pa at 20℃
Log P -9.8
How is Tetrakis(hydroxymethyl)phosphonium sulfate classified and handled safely? Learn More
Danger
GHS05· Corrosive GHS06· Toxic GHS07· Irritant GHS08· Health Hazard GHS09· Environmental Hazard
Hazard Statements
H301 Toxic if swallowed
H302 Harmful if swallowed
H317 May cause an allergic skin reaction
H318 Causes serious eye damage
Precautionary Statements
P203 Obtain, consult and follow expert instructions for use.
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P264 Wash … thoroughly after handling.
Which trade and regulatory codes apply to Tetrakis(hydroxymethyl)phosphonium sulfate?
HS Code 29319019
UN Number 2922
ADR Class 8
Packing Group III
Storage Class 6.1C - Combustible acute toxic Cat.3
toxic compounds or compounds which causing chronic effects
WGK (Germany) 1