Design And Synthesis Of Temporarily Water-soluble Flame Retardant Used In Viscose Fiber

Viscose fiber, easily burned in air, has very low limiting oxygen index. The performance need to modify through adding flame retardant. A series of the flame retardants have been designed and synthesized in this article based on the characteristic that the molecule has hydroxyl group, and the flame retardant can be formed the xanthate and extruded from acid bath as similar as the cellulose, so the flame retardant can disperse as a molecular level, and it can achieve effective flame-retardant performance.Three series of molecules have been designed and synthesized in this article. First, the important intermediate 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) is synthesized by the reaction of o-phenylphenol and phosporus trichloride, and then seven flame retardants are obtained by the reaction of DOPO and carbonyl compounds. Second, phosphonate is obtained from the reaction of triethyl phosphate and 1,2-dibromoethane employed the Arbuzov reaction, then reduction by lithium aluminium hydride gives 1, 2-bis(phosphino)ethane, the phosphine nucleophilic addition to formaldehyde in situ gains the four hydroxyl group compounds, with high phosphorus content 28.9%. Third, used neopentyl glycol and pentaerythritol as the raw materials, three new flame retardants have been synthesized through three steps, the largest phosphorus content is 13.8%. All the intermediate and target compounds are characterized by NMR and IR spectrum. The thermal behaviors studied by TGA and DSC show that compounds 2,4,5,16,19,22 are decomposed rapidly during 250-400℃, which overlaps viscose fiber's decomposition temperature range and possess good fireproofing compatibility with materials.The temporarily water-soluble and precipitation of the synthesized compounds have been tested, and the results show that the maximum recovery is 94.6%.