| Along with it's application extensing, flame retarding properties of paper materials havebeen solicitously required, and the flame retarding study on paper materials has become moreand more important. There are mainly three parts in this paper. Firstly, the synthesis ofguanidine phosphate(GP) which was an intumescent flame retardant containing phosphorusand nitrogen was studied, and the flame retarding effects of GP and the compounded systemof GP, boric acid(BA) and sodium tetraborate decahydrate(Borax) were assessed by burningexperiment. Secondly, the application of GP, GBB and their compounded system with starchto kraft paper was conducted. Lastly, the flame retardant mechanism of the flame retardantswere analyzed by Thermal analysis(TA), Fourier transform infrared spectrometry (FTIR) andScanning Electron Microscopes (SEM). The results were shown as follows.1. The synthetic product was obtained at the mol rate 1:1 of dicyandiamide and phosphoricacid was 1:1, the optimal reaction conditions were as following: the heating rate was1℃/min, the holding temperature was 200℃and the holding time was 15min. theclarified liquor of GP could be got via the following step: hot-filtering, stewing-filteringand second stewing-filtering process for getting rid of the solid impurity.2. The burning experiment showed that the damaged length of the filter paper treated by GPcould be accepted by GB/T14656—93 over the dosage of 10.7％. the experiments alsoshowed that there was some synergetic effect between GP and BA, GP+BA+Borax(10:2:2,GBB) system had much better flame retarding effect, for the damaged length of the flameretardant filter paper treated by GBB could be accepted by a lower dosage of 8.1％, andthe liquor of GBB had a neutral pH value between 6 and 8.3. The application experiment showed that the damaged length of the kraft paper treated by GP and GBB could be accepted with a good grace for the dosage of 10.8％and 8.5％respectively. The tensile breaking strength, tearing strength index, burst index and ringcrush compression index of kraft paper treated by GP and GBB were up to the mustard ofGA159—1997, and the moisture absorption rate of GP and GBB were also meet thenecessity, the reduction of the brightness of filter paper treated by GP and GBB at 105℃for 1h was less than 7.0％.4. The experiment showed that the flame retarding effect of the systems GP and GBB withstarch were fallen due to the addion of starch, on the other hand, which could reduce themoisture absorption rate of the compounded systems and improve some physicalproperties of the treated kraft paper.5. The results of TA, FTIR and SEM showed that different flame retardant theories workedtogether when GP and GBB used as flame retardants to filter paper. GPP articipated in thepyrolytic reaction of filter paper, changed the route of the pyrolytic reaction, increased theyield of char, and reduced the yield of volatile and flammable products, which accordedwith the flame retardant theory of char increasing and volatile reducing. At the same time,carbamidine decomposed to incombustibility gases such as NH3, CO2 which diluted theconcentration of O2, so the dilution effect was worked. Including the flame retardingeffect of GP, BA and Borax contained in GBB could give off water vapor which couldalso diluted the concentration of O2, and BA and Borax could form a hard glass cover toprotect the inner materials from burning, so the isolation effect was worked. Furthermore,when GP and GBB compounded with starch, there was intumescent char film coverd onthe surface of the filter paper, the isolation effect was worked again.
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