Flame Retardant And Anti-dropping Modification Of Polyester Fiber And Fabric

Poly(ethylene terephthalate)(PET)fiber is one of the most important synthetic fibers,and possesses good mechanical property,chemical stability,spinning ability and low cost.It has been widely used in the fields of textile and home decoration.However,PET is flammable and exhibits serious dropping during combustion,which limits its application in decorative textiles fields,especially in the household textile decoration for high buildings or enclosed spaces.In present,flame retardant containing phosphorus-linked main chain is one of the most commonly used flame retardants of polyester fibers.During burning of flame retardant containing phosphorus,the dropping of polyester produce rapidly,thus taking away the heat of combustion to achieve the purpose of flame retardance.However,it is inevitable to produce dropping and toxic smoke,which is more harmful to the safety of human in the enclosed spaces.So in this dissertation,the modification of flame retardant and anti-dropping are the main tasks.Based on the mechanism of polyester combustion and modification of anti-dropping,the flame retarded copolyester with anti-dropping was prepared with pendent linked phosphorus flame retardant and crosslinkable inorganic sol by in-situ polymerization.At the same time,based on the problem of low surface activity of polyester materials,three layers of functional coatings containing flexible polysiloxane/ Phytic acid/ Flexible polysiloxane were deposited on the surface of polyester fabric using flexible polysiloxane sol and phytic acid solution through dipping coated finishing to improve the flammability and anti-dropping properties of polyester fabrics.The main research is as follows:First of all,based on the effective carbonization characteristics of flame retardant for [(6-Oxido-6 H-dibenz [c,e]-[1,2] oxaphosphorin-6-yl)methyl]-butanedioic acid(DDP),Ethylene glycol(EG)was used to improve the thermal stability of the flame retardant DDP by hydroxyl modification.The results of flourier transform infrared spectroscopy(FTIR)and nuclear magnetic resonance(NMR)spectroscopy of DDP-EG indicated that [(6-Oxido-6H-dibenz[c,e]-[1,2] oxaphosphorin-6-yl)methyl]-butanedioic acid bis hydroxyethyl diethyl ester(DDP-EG)was successfully synthesized with DDP and EG by esterification.The thermogravimetric analysis(TGA)and dynamic thermal stability of DDP and DDP-EG show that initial decomposition temperature of DDP is 269 oC,the decomposition temperature of DDP is lower than polyester polymerization temperature.So DDP is difficult to directly apply in polycondensation reaction of polyester.The initial decomposition temperature of DDP-EG increased from 269 oC to 290 oC,the mass residue of DDP-EG was 85.3% at 300 oC treated for 150 min at nitrogen atmosphere,DDP-EG has good thermal stability at the nitrogen atmosphere,which can meet the requirements of polyester polymerization.While the thermal stability of DDP-EG becomes worse at air atmosphere,the mass residue was 62.1 % at 300 oC treated 150 min.Therefore,DDP-EG is easily oxidation degradation at high temperature.The air should be avoided getting into the reaction,leading to degradation of DDP-EG during the polymerization as far as possible.Then,the flame retarded coployesters(PETP)were obtained by esterification and polycondenstion of terephthalic acid(PTA)and ethylene glycol(EG).After esterification process DDP-EG was added.The effect of adding process and adding amount of DDP-EG on the copolymerization process was analyzed.It showed that DDP-EG adding after esterification process decreased its degradation,resulting in improving the quality of PETP.DDP-EG is a kind of side chain type flame retardant,which increases the difficulty of polymerization.With the increase of DDP-EG adding amount,the polymerization time at the same output power is prolonged,which leads more difficult to prepare polyester with high content of DDP-EG.The optimum adding amount of DDP-EG(related to PTA)was 5 mol%,and the content of phosphorus in PETP was 7190 ppm.1H NMR of PETP suggests that DDP-EG is introduced into the PETP chain by copolymerization.DSC of PETP show that the DDP-EG reduces the glass transition temperature(Tg)of PETP,and inhibit crystallization of PETP.TGA of PETP indicates that DDP rises the initial decomposition temperature and the maximum degradation rate of PETP.Combustion behavior of PETP shows that the LOI increases with the increase of phosphorus content.The LOI is 32.4% at the optimum adding amount of DDP-EG,but it still exists the phenomenon of dropping during VFT.The flame retardant grade is V-2.The Ls-Raman results show that the DDP chain enhanced the residual carbon and improved the organized graphitic carbon layer.The thermal stability of PETP and flame retarded copolyester modified with CEPPA were compared with accelerated hydrolysis and thermal oxidation experiments.The results indicated that PETP has excellent stability,the phosphorus content and intrinsic viscosity were still kept more than 95% after accelerated hydrolysis of 300 h at 80 oC.In the process of oxidative degradation,it has higher stability of PETP than that of copolyester modified with CEPPA.The thermal stability and the effect of the addition process of inorganic sol(alkaline silica sol,aluminum hydroxide sol,magnesium hydroxide sol and acidic silica sol)on the intrinsic viscosity and flame retardant of PETP were analyzed.The continuous crosslinking temperature of the alkaline silica sol is higher than 700 oC,and the decomposition temperature of the aluminum hydroxide sol is lower than 200 oC.So both of them are difficult to be used for the modification of the polyester.The acidic silica sol and magnesium hydroxide sol have continuous crosslinking characterization between 400 and 500 oC.However,the catalytic degradation of magnesium hydroxide sol leads to a significant reduction in the intrinsic viscosity of PETP,and the spinnability of copolyester became worse.Acidic silica sol not only has a continuous crosslinking structure,but also it is inert structure at the polymerization and suitable for copolymerization of polyester.The network structure of acidic Si O2 sol leads to hard segmental motion of PETP,resulting in increasing the melt viscosity.At the same power,the polycondensation time become shortening and the molecular weight of PETP become decreasing.Thermal analysis of PETP-Si results show that the acidic Si O2 sol promotes the crystallization rate of PETP-Si.The acidic Si O2 sol can delay the degradation rate and promote the formation of residual carbon.The combustion behavior and flame retardant mechanism of PETP-Si were analyzed,when the amount of acidic Si O2 sol was 3.0 wt%,the LOI of the PETP-3Si was 34.8%,the UL-94 was V-0,and the dropping decreased significantly during combustion.The SiOH and linear Si-O group of Si O2 residual transform into Si-O-Si crosslinking structure at 400~500 oC,improving anti-dropping property and reducing heat release and flue gas release of the PETP.The acidic Si O2 sol enhanced the density and stability of carbon layer.The mainly pyrolysis form of PETP-Si is not changed,the pyrolysis products are acetaldehyde,benzene,biphenyl,benzoic acid,acetylbenzoic acid and its derivatives or various substituted products.Acidic Si O2 sol can effectively avoid the free radical degradation of PETP-Si and reduce the formation of benzene and biphenyl.The copolyester fiber was prepared by melt spinning process.Relative breaking stress of the copolyester fiber is between 1.5 c N/dtex and 3.0 c N/dtex,and PETP fiber has good flame retardant,the LOI is 31.9%,but the dropping of PETP fiber is serious.PETP-Si has good flame retardant and anti-dropping properties,the LOI is 34.1%,and acidic Si O2 sol can reduce the flue gas during combustion.Finally,the flexible polysiloxane sol was prepared through methyltriethylsilane(MTES)sol modified by hydroxyl terminated silicone oil containing hydroxyl 8.5wt%(PDMS-OH).A kind of three layers of functional coatings were deposited on the surface of polyester fabric using flexible polysiloxane sol and phytic acid solution through dipping coated finishing.The flexible polysiloxane were coated the surfaces of the polyester fibers and that phytic acid was grafted on the surface of the polysiloxane coating.Therefore,the large pores of polyester fabric weave did not be blocked.The degradation and combustion behavior of coated fabrics suggested that flexible polysiloxane had the effect of surface isolation,and decreased the degradation rate of finishing fabric,which leaded to increasing residual carbon of finishing fabric.When the soaking time is 20 min,the LOI of finishing fabric is 31.4%,and there is not droppingt formation during combustion.Cone calorimeter(MCC)analysis shows that three-layer functional coating reduced the heat release rate(HRR)and flue gas release,the maximum heat release rate(pk HRR)decreased by 65%,the total smoke release(TSR)decreased by 72%.As a flame retardant,phytic acid can not only catalyze the residual carbon formation,but also absorbed the reactive free radicals of flexible polysiloxane and polyester fabric during degradation,resulting in increasing the thermostability of polysiloxane and decreasing of the burning rate.The hexamethylcyclotrisiloxane(D3),octamethyl cyclotetrasiloxane(D4),decamethylcyclopentasiloxane(D5),dodecamethylcyclohexasiloxane(D6),octamethyl-POSS and Si O2 were produced during decomposition of flexible polysiloxane.Polysiloxane cyclic compounds have excellent thermostability and can be coated on the surface of polyester fabrics,inhibiting the degradation of polyester.The PETP fabric and PETP-Si fabric were subjected to anti-dropping modification by dipping coated finishing process.Due to PETP and PETP-Si fabric containing DDP as free radical absorbent,it is not necessary to soak phytic acid.Under the shorter soaking time,the flame retardant and anti-dropping reinforcement design of the fabric can be realized.