Flame Retardant And Anti-dropping Finishing Of Polyester Fabrics With Intumecent Flame Retanrdants

As one of the most important synthetic fiber,polyester is widely used in clothing and interior decoration.Because of it’s low LOI(only about 21%),PET is very flammable.when heated,due to the temperature difference between the melting point and the ignition point of PET,before cracking it would be softened,shrinking,melting,forming droplets.Most of the flame retardants used in PET were work through increasing the droplets and promoting the rapid drop-off and self-extinguishing.Although it could take away a lot of heat generated by the burning of PET,which can prevent the burning of PET itself,but because of high temperature,it is easy to cause secondary disaster.Therefore,the ideal polyester flame retardants should be able to reduce the droplets,promote the formation of char,endow PET with good flame retardancy and anti dripping properties.The intumescent flame retardant system is mainly composed of an acid source,a carbon source(polyol)and a gas source.When heated,it can form a foamed char layer,this char layer has good heat insulation and oxygen separation property,which can endow the flame retardant material with very good flame retardant and anti dripping effect.In this study,an intumescent flame retardant system(IFR)composed of ammonium polyphosphate(APP),pentaerythritol(PER)and melamine(MEL)was selected for Flame Retardant and Antidropping finishing of polyester fabric,and the ratio of each component was optimized;In order to reduce the water solubility and improve thermal stability of PER,PER was encapsulated with silica gel(MPER).In order to further improve the flame retardant effect,different synergists were used with IFR in flame retardancy of PET fabrics,the appropriate synergist was discussed.The flame retardant finishing of PET fabric was carried out with different content and composition of IFR,and the limiting oxygen index(LOI)and vertical burning performance were determined.The results showed that when the content of IFR was 25%,by optimizing the mass ratio of APP,PER and MEL,ideal flame retardant and anti dripping effect was obtained,LOI of the treated fabric was above 28.5%,the damage length was less than 10 cm,no continued combustion or smoldering,no droplets.The silica gel encapsulated pentaerythritol(MPER)was prepared by sol-gel method using tetraethoxysilane as precursor.The factors which may influence encapsulation,such as p H value,reaction time,reaction temperature,the amount of tetraethoxysilane,the ratio of silicon to water were optimized,respectively.Under alkaline catalytic conditions well encapsulated MPERb was obtained,and acid-catalyze after the first base-catalyze conditions well encapsulated MPERa was obtained.The X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy(SEM)indicated that PER was encapsulated sucessfully,the solubility of MPER was reduced by50% after encapsulating,and the thermogravimetry(TG)analysis showed that the thermal stability of MPER was significantly enhanced.Instead of PER,MPERa was used with APP and MEL for Flame Retardant and Anti-dripping Finishing of PET Fabric,it could enhance the flameretardant effect of treated samples efficiently,LOI increased to 32.1%,increased char residue and more complete and compact char layer was obtained.Ferric chloride、calcium carbonate、zirconium phosphate and titanium dioxide were chosen as synergist used to compound with IFR for the flame retardant finishing of PET fabric.Ferric chloride could improve flame retardant effectively,only by adding 2% of ferric chloride,the LOI of treated samples increased from 32.1% to 36.7%.Finally,when the amount of IFR was 25% and APP:MPERa:MEL=20:4:1(mass ratio),ferric chloride was 2%,the LOI of treated PET fabrics was 37%,the damage length was 7.4cm,no continued combustion or smoldering,no droplets,the flame-retardant and anti dripping effect was excellent.TG results showed that the initial degradation temperature and temperature of maximum weight loss rate of the treated samples were decreased,the maximum weight loss rate also decreased,the amount of char residual increased from 0 to 33.4%,significantly improved the flame retardancy and anti dripping performance of PET fabrics.