The Synthesis And Application Of Reactive Flame Retardants For Silk Fabrics

Silk is an kind of elegant and decorative fabric. However, due to its combustibility, flameretardant finishing is very necessary to meet the high-end market’s demand for decorativesecurity. Currently, after flame retardant finishing, it’s often difficult to balance the contradictionbetween handle-feeling of finished fabric and its wash ability. In response to these problems, wesynthesized two types of reactive flame retardant which could be grafted with silk fabric; then,the chemical bonding reaction between the flame retardant and silk fibers was verified; at last,the physical and dyeing properties of the finished silk fabric were investigated.There are two kinds of synthetic product. One is chloro-s-triazine phosphorus flameretardants K-P1. Cyanuric chloride and diethyl (hydroxymethyl) phosphonate were chosed as rawmaterials and anhydrous potassium carbonate as acid-binding agent. In this synthesis reaction,diethyl (hydroxymethyl) phosphonate was continuous feeding and reaction temperature wascontrolled step by step. The other one is vinyl phosphate ester flame retardants. By two steps,phosphorus oxychloride had condensation reactions with hydroxyethyl acrylate and methanol (orethanol) separately with triethylamine as acid-binding agent. Then hydrophilic flame retardant P2and hydrophobic P3were obtained. Furthermore, IR spectroscopy and Nuclear MagneticResonance spectroscopy were used to confirme that the two types of flame retardants had thetarget chemical structure.By way of padding method, silk fabric was treated with chloro-s-triazine phosphorus flameretardant. The bond-forming reaction between K-P1and silk fabric was verified by IRspectroscopy; the limiting oxygen index (LOI) of finished silk could be improved to a maximumof29%with increasing concentration of K-P1and silk fabric had flame resistance. The LOI valueof finished fabric would drop to around26%after30and50times washing respectively.In this paper, research focused on the graft co-polymerization of vinyl phosphate with silk;flame retardant’s structure was demonstrated; flame retardant dosage, initiator concentration, pH,and reaction temperature and other process factors were discussed; after silk was grafted withflame retardant, the relationship between silk grafting rate and flame resistance was explored.When the graft ratio of water-soluble P2onto silk was10%, the LOI value was only about27%;while the hydrophobic P3had higher graft ratio round30%and better flame resistance with LOIvalue up to31%. After30and50times washing test, flame resistance almost unchanged. We also found that the silk fabric grafted with P3had no significant yellowing, but the fabric becamestiffer with the increase of P3dosage and that the reactive dyes K/S value of grafted silk fabricdecreased by more than60%.Next, paper made a further study on the flame retardant efficiency of the complex graftsystem including flame retardant P3and methacrylamide (MAAm). The LOI value of silk fabricgrafted by MAAm was about25%which was approximately equal to that of ungrafted silk(24.8%); while when P3and MAAm consisted of complex graft system, the LOI value increasedwith increasing amounts of MAAm up to34%on the condition of same P3dosage. What’s more,when the LOI value of grafted silk fabric was30%, P3dosage of the complex graft system wasless than P3graft system around50%; whiteness and handle-feeling were superior; wash abilitywas still good. At this point, the dye depth of silk with reactive dyes was higher than that of silkgrafted by P3alone, which could reach more than85%of the dye depth of ungrafted silk fabric.Thus, the complex graft system has high applied prospect.