Preparation Of New Flame Retardant Of Nitrogen And Phosphorus And Its Application In Cotton And Polyester

The limiting oxygen index(LOI)value of cotton is only 18.0%,which means that cotton is flammable.After burning,the fibres is broken and the fabric surface is damaged.Polyester fabric with an LOI value of about 20.8%is easily softened by heat,which leads to forming molten droplets and producing thick smoke.Therefore,a new type of nitrogen and phosphorus flame retardant was designed and prepared for flame retardant treatment of cotton fabric as well as polyester fabric in this paper to solve the flammability problem of cotton fabric,and the problem of flammability,molten droplets as well as smoke emission of polyester fabric.This paper provides a new choice of flame retardant for modified textiles.Among them:(1)The pentaerythritol phosphate ester was synthesized by using pentaerythritol as carbon source and phosphoric acid as acid source.Then adding phosphorus pentachloride(PCl₅)and ethanolamine to prepare the target nitrogen phosphorus flame retardant.Its structure and elements were characterized by Fourier transform infrared spectroscopy(FTIR)and energy dispersive X-ray spectroscopy(EDS).By testing the ester yield and the residual carbon rate of products compounded under different reaction conditions,the optimal reaction conditions for synthesizing nitrogen and phosphorus flame retardant was found:n_-OH(pentaerythritol):n_-H(phosphoric acid)=1:4.5,esterification reaction time was 2.0 h,esterification reaction temperature was 110?,n(pentaerythritol):n(PCl₅)=1:0.5.The results of synchronous thermal analysis(TG-DSC)and scanning electron microscopy(SEM)showed that the flame retardants of nitrogen and phosphorus had better thermal stability,the residual carbon rate was 48.80%at 500?,and the structure of carbon residue after decomposition was more compact..(2)Polyester fabric was treated with nitrogen and phosphorus flame retardants.And EDS results showed that the flame retardants were successfully treated on polyester fabric.Its flame retardancy was characterized by vertical combustion and limiting oxygen index(LOI).When the additive amount of flame retardant was 100 g/L,the damage length of polyester was only 4.0 cm,and there was no flaming and smoldering time.It burned without smoke,and only one fusing droplet was generated.The LOI of polyester was 30.3%,which was 58.6%higher than that of untreated polyester.Its LOI value was still higher than 30.0%after 50 times of washing.Compared with the commercial ATP flame retardant at the same concentration,the damaged length of polyester treated with nitrogen and phosphorus flame retardant reduced by 28.6%,and the droplet generation decreased significantly.SEM results showed that the addition of flame retardant did not cause damage to polyester fibers.The surface of carbon residue after combustion was compact and smooth,and there were many bubbles on it,which means that flame retardants play a role in the gas phase and condensed phase.TG-DSC and tensile test results showed that the flame retardant polyester had good thermal stability and mechanical properties.(3)The cotton fabrics were treated with nitrogen and phosphorus flame retardants.Two different preparation methods of flame retardant finishing liquid were designed.By testing the flame retardant properties of treated cotton fabric,the optimal finishing liquid formulation was determined as follows:dissolving m₁g flame retardant in distilled water,adjusting p H to 6.0?6.5 with 10%Na OH solution.When the additive amount of flame retardant was 100 g/L,the damaged length of cotton was only 6.8 cm.When the fire source was removed,the cotton went out quickly with no smoke,no afterburning time and short smoldering time.The LOI of cotton reached at 32.0%,which was 77.8%higher than that of untreated cotton.Its LOI value was still higher than untreated cotton after 50times of washing.Compared with the commercial CP flame retardant at the same concentration,the LOI value of the fabric treated with the nitrogen and phosphorus flame retardant increased by 14.0%,and the damage length was from all damage to only 6.8 cm damage.SEM results showed that the fiber fracture of flame retardant cotton was greatly improved after burning,and the residual retained the original structure.TG-DSC and tensile test results showed that flame retardant cotton had better thermal stability and mechanical properties.