Study On Preparation Of Triazine Charring Agent And Its Flame Retardance

Intumescent flame retardant(IFR)is considered as one of the effective ways to realize the greening of flame retardant because of its some advantages such as low smoke,low toxicity and little addition.In spite of this,there are still some problems in the current IFR such as poorer flame retardantcy,great influence on the mechanical properties of polymers,poor thermal stability and hydrolytic stability.Charging agent is one of the key substances that affect the flame retardant effect of IFR.In recent years,the successful use of triazine charring agent has made the flame retardant effect of IFRsignificant improvement,but the charring agents onmarket also have some shortcomingssuch ashigher chlorine content,expensive price and dark color and so on.Therefore,to further improve the charring agenthas important theoretical and practical significance.In order to overcome the disadvantages of the existing triazine charring agents,poly-2-ethanolamino-4,6-ethylenediamino-1,3,5-triazine(CNCE-DA1)was synthesizedthrough condensation with ethanolamine at low temperature,condensation with ethylenediamineat medium temperature,finally polycondensation at high temperature using cyanuric chloride as the raw material and sodium hydroxide as the acid-binding agent,andthe optimization of its structure and the synthesis process conditions was investigated mainly.The results showed that the optimal synthesis conditions were as follows:n(cyanuricchloride):n(ethanolamine):n(ethylenediamine):n(sodium hydroxide)=1:1:1:3,w(cyanuric chloride): w(acetone): w(water)= 1:1.3:1.2,thetemperature oflow temperature condensation being 0-5?,the dropping time oflow temperature condensation being 1h,the time oflow temperature condensation being2h;the temperature ofmedium temperaturecondensationbeing 45-50 ?,the dropping time ofmedium temperaturecondensationbeing 2h,the timeofmedium temperaturecondensationbeing 2h;the temperature of polycondensation being 95-100?,dropping time ofpolycondensationbeing 2h and the polymerization time being 2h.The product synthesized under the above conditions have some shortcomings such as higher chlorine content,easy to change yellow and poorer thermal stability.In order to solve the above problems,the product was modified through a termination with butylamine and aniline(collectively referred to as primary amine)afterthepolycondensation reaction,and poly-2-ethanolamino-4,6-ehylenediamine-1,,3,5-triazine(CNCE-DA2)modified with butylamine and poly2-ethanolamino-4,6-ethylenediamino-1,3,5 triazine(CNCE-DA3)modified with aniline were synthesized.The optimal conditions for termination reaction were as follows: the temperature being 95?the dropping time of the primary amine solution being 0.5 h,the time being 1.5h,n(cyanuric chloride): n(primary amine)=1:1.The chlorine content of the product was reduced significantly,andits whiteness,yield,thermal stability and the char-forming ability was improved obviously by termination,especially with butylamine.The flame retardancy of six IFRs(referred to as IFR-1,IFR-2,IFR-3,IFR-4,IFR-5 and IFR-6)by combination ofammonium polyphosphate(APP)respectively with CNCE-DA1,CNCE-DA2,CNCE-DA3 and three charring agents(CTJ-1,CTJ-2 and CTJ-3)on the market in PP were investigated.The vertical burning test showed that there was no significant difference in the flame retardance of IFR-1,IFR-2,IFR-5 and IFR-6,while IFR-3 was slightly poorer and IFR-4 slightly better.The cone calorimeter test results revealedthat IFR-2 and IFR-5 had the best flame retardant effect,while IFR-4 is slightly poorer.Compared with the charring agents on the market,the flame retardancy of CNCE-DA2 was almost the same,but its chlorine content and synthesis cost were lower.The thermogravimetric analysis results showed that the addition of IFR-2,IFR-4 and IFR-5 all reduced the thermal stability of PP,but IFR-2 only had little effect.The analysis of combustion residues showed that the above IFRs all played a flame retardant effect through condensed phase mechanism.APP was decomposed into polymetaphosphoric acid on heating,which made the charring agent dehydration and carbonization.The melted carbon expands and foams under the inert gas from the decomposition of APP,charring agent and PP to form a dense intumescent layer which resulted in the flame retardant effect by means of the barrier effect on heat and air as well as preventing the volatilisation of the pyrolysis products.