Epoxy phosphonate crosslinkers for providing flame resistance to cotton textiles

• Published in: Polymers for advanced technologies 2007-08, Vol.18 (8), p.611-619
• Main Authors: Chang, SeChin, Sachinvala, Navzer (Nozar) D., Sawhney, Paul, Parikh, D. V., Jarrett, William, Grimm, Casey
• Format: Article
• Language: English
• Subjects: cotton; epoxy phosphonate crosslinkers; flame resistance; print cloth
• ISSN: 1042-7147; 1099-1581
• DOI: 10.1002/pat.867

Two new monomers (2‐methyl‐oxiranylmethyl)‐phosphonic acid dimethyl ester (3) and [2‐(dimethoxy‐phosphorylmethyl)‐oxyranylmethyl]‐phosphonic acid dimethyl ester (6) were prepared and used with dicyandiamide (7) and citric acid (8) to impart flame resistance to cotton plain weave, twill, and 80:20‐cotton/polyester fleece fabrics. Monomers 3 and 6 were prepared from methallyl chloride (1) and 3‐chloro‐2‐chloromethylpropene (4) respectively via a two‐step phosphorylation epoxidation sequence in 79.3 and 67.5% overall yields. 1H and 13C nuclear magnetic resonance (NMR) and gas chromatographic mass spectrometry (GCMS) data were used to confirm their structures. Decomposition of monomers 3 and 6 in nitrogen by thermogravimetric analysis (TGA) occurred at 110 and 220°C, respectively. The mixtures of 3:7:8 and 6:7:8 (in 2:1:1 ratio) exhibited peak‐curing temperatures by differential scanning calorimeter (DSC) at 125 and 150°C and the temperatures were deemed suitable for curing treated fabrics without marring them. Flame‐retardant treatments were applied by the pad‐dry‐cure methods. All untreated fabrics showed limiting oxygen index (LOI) values of about 18% oxygen in nitrogen. For formulations with monomer 3, LOI values for the three types of treated fabrics were greater than 25.5% when add‐on values for the formulation were 17.4, 12.7, and 21.1%. For formulations comprising monomer 6, LOI values were greater than 28.6% when add‐on values for the formulation were 18.3, 13.1, and 16.7%. With the formulation comprising monomer 3, the three fabrics passed the vertical flame test when add‐on values were 21.6, 12.7, and 23.5%, respectively; and with the formulation comprising monomer 6, they passed the vertical flame test when add‐on values were 13.8, 8.4, and 18.0%. In all cases char lengths of fabrics that passed the vertical flame test were less than 50% of original length and after‐flame time was 0 sec and after‐glow time was less than 2 sec. Published in 2007 by John Wiley & Sons, Ltd.