Epoxy Phosphonate Crosslinkers for Providing Flame Resistance to Cotton Textiles

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Polymers and High Performance Materials


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. H-1 and C-13 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 degrees 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 degrees 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.

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Polymers For Advanced Technologies





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