Study On Synthesis And Properties Of Temporarily Water-soluble Flame Retardant Used In Viscose Fiber

It is desirable,for many textile purposes to provide viscose fibers and yarns having greatly decreased flammability.Based on the principle of filature,a kind of temporarily water-soluble flame retardant which contains hydroxyl group is designed and synthesized.At first,the water-soluble xanthate of flame retardant as similar as the xanthate of cellulose made from the reaction with CS₂ is dissolved in the alkaline viscose,and then the flame retardant is extruded from acid regeneration bath together with viscose fiber after spinning.The flame retardant can disperse in the viscose fiber as molecule,so high performance of the flame retardancy is accomplished.Three series of phosphate flame retardants are designed and synthesized.(1) Intermediate pentaerylthritol diphosphonate dichloride(PDD)is synthesized from pentaerylthritol and phosphorus oxychloride.Two polycondensation phosphates have been obtained by the reaction of neopentyl glycol and 2,4-dihydroxybenzaldehyde with PDD, respectively.(2)Two flame retardants which contain hydroxyl group are synthesized from PDD and 4-hydroxybenzaldehyde,5,5-dimethyl-2-sulfide-1,3-dioxaphosphonic chloride and 2,4-dihydroxybenzaldehyde in two steps,respectively.(3)At first,two alcohols with the structure of caged bicyclic are synthesized.In the further reaction,four flame retardants which contain hydroxyl group and caged bicyclic structure in one molecule are synthesized.The structures of the above compounds are characterized by NMR and IR.The thermal behaviors studied by TGA and DSC shows that all of the synthesized compounds are decomposed rapidly and release a mass of energy during 200～340℃,which overlaps viscose fiber's decomposition temperature range,and possess good fireproofing compatibility with materials.The physical and chemical properties of the synthesized compounds have been tested. The optimum etiolated and extruded condition of some flame retardants have been found during the etiolated reactions.¹H NMR spectra show that compounds before etiolated reaction and after acid regeneration have the same structure.The properties of the flame retardants are being tested in Dandong Chemical Fiber Co.,Ltd.,now.