Synthesis Of Triazine Reactive Flame Retardants And Application In Cotton Fabrics

Cotton fabrics have been widely used in many fields due to their advantages of vast quantities,softness, comfort, excellent moisture absorption, permeability and durability. However, theirapplication has been restricted by such real obstacles as ease of ignition, burning and thermaldegradation for its low LOI is only18vol%. Therefore, it is of urgent to further develop thetechnology of flame resistance for cotton fabrics since disasters caused by cotton fabricsburning have taken to people a great loss on life and production. The research of low cost, lowsmoke and toxic, environmental-friendly and excellent char forming flame retardants forcotton fabrics is of great theoretical and practical significance.In this paper, a kind of triazine flame retardants with multiple reactive groups have beensynthesized for the first time by using cyanuric chloride, triethyl phosphite, neopentyl glycol,glycerol and pentaerythritol as raw materials, wherein they are named for dioxo(3-triethylphosphite-5-chlorine-1-triazine) neopentyl glycol (DTCTNG), trioxo(3-triethylphosphite-5-chlorine-1-triazine) glycerin (TTCTG), tetroxo(3-triethylphosphite-5-chlorine-1-triazine) pentaerythritol (TTCTPT). The structure ofDTCTNG, TTCTG and TTCTPT have been successfully characterized by FTIR,1H-NMRand31P-NMR spectroscopy. The thermol behavior of the novel flame retardants has beeninvestigated by thermogravimetric analysis (TG) and the results showed that DTCTNG,TTCTG, TTCTPT were all good char forming agents; The optimal reaction conditions forthem have been studied by the effects of reaction solvent, acid-binding reagent, reactiontemperature, raw material ratio and reaction time on the yields of them.The obtained flame retardants have been applied to cotton fabrics by “dips-nips-curing”method. The optimal finishing process condition on cotton fabrics of each flame retardant has been set by the research of the flame retardant’s fire retardancy itself, the type of catalyst,dosage of catalyst and flame retardant. The structure of the treated and untreated cottonfabrics has been characterizated by attenuated total reflection fourier transform infraredspectrometry (ATR-FTIR), demonstrating that the grafted reaction had taken place betweenthe flame retardants and the cotton fabrics. Vertical flammability test and Limiting oxygenindex test （LOI） have been used to study the flame retardancy of each flame retardant,showing that the LOI of the treated samples were more than26vol%and could achieve B1rating of flame retardant textiles in the condition of optimal finishing process. TG analysis hasbeen applied to test the thermostability of treated and untreated cotton fiber samples,demonstrating that the initial decomposition temperature and the maximum decompositiontemperature were reduced, in which the char residue at600C were more than30%comparedto those of the untreated ones. This further indicated that DTCTNG, TTCTG, TTCTPTcould greatly improve the thermostability of cotton fabrics. Scanning electronic microscopy(SEM) was used to characterize the changes in the surface morphology of the untreated andtreated textile, char residues of treated and untreated cotton fiber, indicating that flameretardant-grafted cotton fabrics were bound and infiltrated by flame retardants, wherein rough,firm and intact surface was also observed. All these results demonstrated that DTCTNG,TTCTG and TTCTPT are of excellent flame reatardancy.For water resistance of the finishing cotton fabrics by DTCTNG, three different componentsof flame-retardant finishing liquid were applied to study the effect of different additives on thewater resistance of flame retardant cotton fabrics; meanwhile, the three kinds of finishingliquid contain only DTCTNG, catalyst/DTCTNG, or DTCTNG/catalyst/crosslinking agent.ATR-FTIR has been used to characterize the structure of the treated cotton fabrics afterlaundering for50times, demonstrating that the the grafted reaction had really taken placebetween DTCTNG and the cotton fabrics. TG analysis has been applied to test thethermostability of treated cotton fiber after laundering for50times, the results manifested thatthe initial decomposition temperature, the maximum decomposition temperature, and the charresidue at high temperature were all changed, which further demonstrated that the flame retardant textile after laundering for50times still got good thermostability. LOI test has beenapplied to investigate the flame retardancy of fire retardant cotton fabrics after different timesof laundering. This results gave that (i) the LOI of treated textile after50times launderingwas19.3vol%,(ii) the LOI has improved to20.0vol%after catalyst was added,(iii) it hasenhanced to21.7vol%after cross-linking agent was added. These manifested that catalystcould play a role in improving grafting percent and cross-linking agent could enhance stablenetwork structure formed between the DTCTNG molecule and cotton fiber, which thus thesemight increase the durability of the water resistance of treated cotton. SEM was used tocharacterize the surface morphology of the char residues of treated cotton fabrics afterlaundering for50times, and the result indicated that rough, firm and intact surface wasobserved for the char residue. All these results demonstrated that fire retardant textile gotexcellent flame reatardancy and durable resistance for water.