Tetrakis(hydroxymethyl)phosphonium chloride

Tetrakis(hydroxymethyl)phosphonium chloride (CAS 124-64-1), commonly sourced as THPC, is a reactive phosphorus-based flame retardant used across textile, leather, and industrial substrate treatments. It functions by chemically bonding into fibrous or polymer matrices during curing, delivering durable flame retardancy rather than surface-level protection for various materials.

In textile finishing, THPC is reacted with nitrogen-containing compounds such as urea or melamine to produce wash-durable flame-retardant finishes on cotton and cellulosic fabrics. This process is widely specified for workwear, military, and protective clothing. Leather processors apply it during wet finishing to meet fire resistance standards required in automotive upholstery.

In pulp and paper manufacturing, it functions as both a flame retardant and a cross-linking agent, improving dimensional stability in treated specialty papers and industrial products. Building and construction applications include flame-retardant treatment of nonwoven materials and insulation substrates where regulatory compliance drives specific material requirements.

THPC is supplied as an aqueous solution, typically at 80% active content, which is the standard commercial concentration for industrial use in most manufacturing sectors. It is available in technical grade, with supply in drums and intermediate bulk containers to suit both formulators and large-scale processors requiring consistent chemical supply.