Synthesis Of Reactive Phosphorus-nitrogen Flame Retardant And Its Application On Cellulosic Fabrics

Cellulose fabrics had been widely applied in the various areas such as clothing and home textiles due to its excellent properties of air permeability,hydrophilicity and softness.However,the cellulose fabrics had low limiting oxygen index and is flammable,which showed a significant threat to humans and their possessions.At present,the commercial flame retardant widely used in the flame retardant finishing of cellulose fabrics is Pyrovatex CP.The flame retardancy and durability of treated fabrics are very excellent,while flame retardant may release formaldehyde that damage human health and the environment.Therefore,the synthesis of a durable and formaldehyde-free flame retardant has very important practical significance.In this work,a novel reactive flame retardant was synthesized and applied on the cellulose fabrics.The treated fabrics have durable flame retardancy and no formaldehyde is released during the treatment.The research content mainly includes:（1）The reactive phosphorous nitrogen flame retardant was synthesized in two steps by using dimethyl phosphite,acrylamide and cyanuric chloride as raw materials.The structure of intermediate and flame retardant was characterized by FTIR,¹H-NMR,¹³C-NMR and ³¹P-NMR.The best synthesis process of intermediates and flame retardants was studied.The results show that the target flame retardant was successfully synthesized.The optimal synthesis process of intermediates was following:the ratio of 1.1:1,the catalyst dosage of 0.024 mol,the reaction temperature of 80°C,the reaction time of 5 h.Under the optimal conditions,the yield of intermediates was 68.6%.The optimal conditions for the synthesis of flame retardant were the following:the ratio of 2.2:1,triethylamine dosage of0.12 mol,the reaction temperature of 45°C,the reaction time of 4 h.The yield of flame retardant was 83.5%under this conditions.（2）The flame retardant was applied to prepare flame retardant cotton fabric through pad-dry-cure method.The effects of flame retardant concentration,finishing solution pH,reaction temperature and time on the flame retardant properties of finished fabrics were studied through single factor experiments,and the best finishing process was obtained.The results suggested the optimal treatment process was the flame retardant concentration of300 g/L,the finishing solution pH of 10,the reaction temperature of 80°C,the reaction time of 4 min.The treated cotton fabric began to degrade at lower temperature and the char residue was increased.Compared with untreated cotton fabrics,the total heat release rate（THR）and the maximum heat release rate（PHRR）of the treated cotton fabric were lower,and had higher TTI and char residue.The LOI value of treated cotton fabric increased to31.0%.,the afterflame and afterglow time decreased to 0 s.After washing for 10 times,the LOI value of treated cotton fabric was reduced to 27.2%.The treated cotton fabric obtained good washing durability,meanwhile,the tensile strength and whiteness decreased slightly.（3）The flame retardant was applied to prepare flame retardant viscose fabric through pad-dry-cure method.The optimal treatment process,surface morphology,elemental content,thermal stability,flame retardancy,physical properties and washing durability were measured.The results suggested the optimal treatment process was the flame retardant concentration of 400 g/L,the finishing solution pH of 10,the reaction temperature of 80°C,the reaction time of 3 min.Treated viscose fabric had outstanding thermal stability and flame retardancy.The char residue rate in nitrogen and air atmosphere was increased to46.4%and 13.0%The LOI value of treated viscose fabric increased to 31.0%.and reduced to 27.1%after washing for 8 times.Flame treatment had a slight effect on the tensile strength and whiteness.