Application Study Of Phosphorus Containing Flame Retardant In Polyester

Polyethylene terephthalate(PET)has been widely used in fiber,film,engineering plastics and other fields due to its high strength,good heat resistance,solvent resistance,low permeability and high transparency properties.However,its flammability limits its application in some specific fields,so it important to improve the flame retardancy of PET materials.At present,there is a lack of blending flame-retardant polyester materials in the market,which can be melted,good dispersibility,good compatibility,high flame retardant efficiency and low melt viscosity.The purpose of this study is to develop and explore the application technology of a several new high-effective organic phosphoursflame retardants in flame retardant polyester materials in order to solve the problems existing in the blending flame-retardant polyester system.In this study,twin-screw extruder was used to study the method of blending extrusion,high viscosity PET was used as the carrier resin,and 1,2-bis(diphenylphosphinoxy)ethane(EDPO),1,4-bis(diphenylphosphinoxy)butane(BDPO),6,6-(1,2-phenethyl)bis-6H-dibenz[c,e][1,2]oxaphosphorin-6,6-dioxide(HTP-6123),and poly[oxy(phenylphosphinylidene)oxy-1,4-phenyl enesulfonyl-1,4-phenyl ene](PSPPP)were used as flame retardants to prepare flame-retardant polyester masterbatch respectively.The effects of the four different flame retardant and processing temperature on the extrusion performance of flame retardant masterbatch were explored.The optimal extrusion process parameters were investigated.The flame-retardant PET material was prepared by adding three flame retardant powders of EDPO,BDPO and HTP-6123,and the flame retardant properties of the flame-retardant PET were investigated and compared by limit oxygen index(LOI)test and vertical combustion test.The results showed that introduction of the three flame retardants significantly improved the flame retardant performance of PET.When 2%flame retardants were added,the after ignition time of PET/EDPO-2,PET/BDPO-2,PET/HTP-2 samples were shortened to 1.6 s,2.3 s and 2.0 s respectively.Compared with pure PET,the after ignition time was significantly shortened.When the amount of flame retardant is 12 wt%,the vertical combustion tests of PET/EDPO-12,PET/BDPO-12,PET/HTP-12 samples all reached UL 94 V-0 level,and the LOI values were 31.2%,32.7%and 32.4%,respectively.Thermogravimetric analysis(TGA)analysis under nitrogen atmosphere showed that the initial decomposition of PET did not significantly changed when 5800 mg/kg phosphours content was added.The residual carbon increased significantly,and the most high residual carbon was PET/HTP.The combustion behavior and carbon surface morphology of flame-retardant modified PET were studied by means of cone calorimetry test(CCT)and scanning electron microscopy(SEM).The results show that the three flame retardants primarily act through the gas phase flame retardant mechanism,and HTP-6123 also exhibited relatively strong condensed phase mechanism.The effect of flame retardant on melt flowability of flame-retardant PET was tested by melt index method.The results showed that with the increase of the flame retardant content,the melt index of the flame retardant PET increased significantly.The MFR of PET/HTP is the highest,and the MFR of PET/BDPO is the lowest,indicating that BDPO has the least impact on the melt flowability of PET,while HTP-6123 flame retardant has the largest impact on the melt flowability of PET.Flame retardant polyester materials were prepared in the form of flame retardant masterbatch to test the application performance of the prepared flame retardant masterbatch,and the impact of the change in addition mode on the flame retardant performance and melt fluidity was compared and tested.Results showed that,with the same phosphorus content,the flame-retardan PET material prepared using flame-retardant masterbatch showed higher LOI and lower MFR.BDPO flame-retardant polyester exhibited similar melt flowability to flame retardant PET prepared with commercial reactive flame retardant of CEPPA.Three flame retardants EDPO,BDPO and HTP-6123 were used in glass fiber reinforced PET and PBT.The results showed that the introduction of flame retardants can improve the flame retardant performance of glass fiber reinforced PET and PBT.Flame retardant glass fiber reinforced PET showed better flame retardancy than glass fiber reinforced PBT.The main reason for this difference is that the decomposition temperature of the three flame retardants does not match the thermal decomposition temperature of the PBT.According to calculation,the combustion heat of PET and PBT are 21.83kJ/g and 24.77kJ/g,respectively.The combustion heat of PBT is 13.5%higher than that of PET,which is also one of the reasons why PBT is more difficult to achieve flame retardant than PET using the present flame retardants.