Synthesis And Application Of High Phosphorus Content Leather Flame Retardant

Leather products are used in more and more fields with excellent performance,but leather products are no more harmful than other industries(rubber,plastic,textile),so it is necessary to develop functional leather with good flame retardant properties.Optimizing the leather process and developing high-efficiency,halogen-free,low-toxic phosphorus-based flame retardants are the research hotspots of flame-retardant leather.In this paper,two kinds of flame retardants,high phosphorus content melamine salt(HPPMS)and quaternary phosphonium phosphate melamine salt(THP-PPMS),were synthesized and applied to leather flame retardant.Firstly,high-phosphorus phosphate melamine salt(HPPMS)was synthesized from phosphoric acid(PA),bis(hydroxymethyl)methyl phosphine oxide(BMPO)and pentaerythritol,then it was modified by formaldehyde and sodium bisulfite,and the effect of reaction conditions was studied on the yield.The structure of the synthesized product was characterized by Fourier transform infrared spectroscopy(FT-IR).The thermal stability of the modified HPPMS/leather was studied by thermogravimetric analyzer(TGA).The morphology of residual carbon of modified HPPMS/leather was studied by scanning electron microscopy(SEM).The modified HPPMS/leather also were studied about mechanical properties,flame retardancy,shrinkage temperature and sensory properties.The results showed that the maximum yield of phosphate was 84.3%when molar ratio of PA and BMPO was 2:1;the yield of HPPMS was the largest when the reaction time of melamine was 4h;and the amount of residual formaldehyde was the least when the reaction time of formaldehyde was 1.5h;the addition of modified HPPMS was 6%,LOI of the leather increased from 26.6 to 33.6;the flaming combustion time and flameless combustion time of the leather reached 2.7s and Os respectively;tensile strength of the leather reached 24.5MPa;stretching temperature of the leather reached 111.3?;the elongation at break of leather with 4%modified HPPMS reached 91.6%.The sensory properties of leather with modified HPPMS were not improved significantly.Secondly,the quaternary phosphonium phosphate melamine salt was synthesized from phosphate melamine salt and tetramethylolsulfate(THPS),and study the synthesis route and reaction conditions at the same time.The structure of the THP-PPMS was characterized by Fourier transform infrared spectroscopy(FT-IR).The thermal stability of THP-PPMS/leather system was studied by thermogravimetric analyzer(TGA).The morphology of residual carbon of theTHP-PPMS/leather system was studied by scanning electron microscopy(SEM).The THP-PPMS/leather was studied on mechanical properties,flame retardancy,shrinkage temperature and sensory properties.The results showed that when the pH of the reaction system was 6.0,the yield was 81%;the LOI of leather increased from 26.3 to 35.2 when addition of THP-PPMS was 6%,the flaming and flameless combustion time of leather reached 1.9 s and 0 s respectively when addition of THP-PPMS was 8%;tensile strength of leather reached 25.6MPa;the breaking elongation rate of leather was 82.5%;the expansion temperature of leather reached 112.1??the sensory organs of leather could be improved by adding modified THP-PPMS,but the performance improvement is not obvious.Finally,the leather technology was explored.Flame retardants were added in the fatliquoring stage and compared with the retanning stage to study the comprehensive properties of leather.The results showed that the maximum LOI value of flame retardant leather decreased by 4.9;the flame and flameless combustion time increased by 4.5 s and 50.3 s;and the shrinkage temperature decreased by 3.4 C.The maximum tensile strength of leather decreased by 4.6 MPa,and the maximum elongation at break of leather with 1%flame retardant was 109.1%.The sensory properties of flame retardant leather were also not improved significantly.