Tanning with Tetrakis Hydroxymethyl Phosphonium Chloride

摘要

The experiment was carried out to develop the potential tanning ability of tetrakis hydroxymethyl phosphonium chloride (THPC), in which tanning Ph, temperature, dosage, time et al. were optimized respectively and shrink temperature (Ts) of leather tanned solely by THPC is 83℃. Many retanning agents were then employed to raise the Ts and 96℃ was obtained by retanning with condensed tannin. Furthermore, the contents of THPC and free formaldehyde in THPC sample at Ph=4.0 and Ph=6.0 were determined. The structures of phosphonium compounds in THPC samples at Ph=4.0 and Ph=6.0 were also analyzed by FT-IR and ~(31)P NMR. The Connolly solvent-excluded volume and Wang-Ford charge distributions of three main types of phosphonium compounds were calculated by chemical software. In final analyses, the tanning mechanism was concluded that THPC, tri-hydroxymethyl phosphonium (THP), tri-hydroxymethyl oxide (THPO) and formaldehyde all played different roles in tanning process, and THPO is most reactive phosphonium compound in THPC tanning system. All these results will give tanneries more favorable guides.