| Air filter paper is the core material of air filter in automobile engine intake system,which itself is loose porous flammable material.In practical application,the engine is burned due to engine tempering,inhalation of combustibles and other causes,which serious threat to people's lives and property safety.So the engine manufacturers made a higher demand with flame retardant performance of air filter paper.At present,the air filter paper products with good flame retardant performance in domestic market are all rely on imports.The integrated product performance of domestic products is difficult to meet the customer's requirements.Therefore,the core content of this thesis is to prepare flame retardant air filter paper by using the reinforced resin with flame retardant properties.The main contents and results of this paper are as follows:(1)Preparation of phosphorus modified phenolic resin and its preliminary application in air filter paper: First,prepared the phosphorus-containing monomer(ODOPM)with 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide(DOPO)and paraformaldehyde,optimized effect of solvent system,reaction temperature and reaction time on the conversion.Then prepared phosphorus-containing phenolic resins using ODOPM,the effects of phenolic mole ratio,ODOPM addition process and reaction time on the properties of phosphorus modified phenolic resin were investigated.The flame retardancy was characterized by TGA,limiting oxygen index and horizontal combustion test.The results showed that the residual carbon and LOI of the phosphorus modified phenolic resin increased with the increase of the phosphorus content.When the phosphorus content was 2.5wt%,the carbon residue was up to 61.18%,and when the phosphorus content was 1.89 wt %,the vertical combustion level of the modified resin could reach UL94 V-0(LOI=32.4).The phosphorus modified phenolic resin was applied to air filter paper,and the comprehensive strength,flame retardancy and microstructure of the filter paper were characterized by physical property test,horizontal combustion test and SEM.The results showed that the comprehensive strength of filter paper decreased with the increase of phosphorus content,the flame retardant property was improved and the air permeability and microstructure of filter paper were not changed obviously.(2)Preparation of phosphorus-nitrogen flame retardant modified phenolic resin and its preliminary application in air filter paper: First,prepared nitrogen modified phenolic resin using melamine,through the limited oxygen index,vertical combustion test to characterize its flame retardant properties.The results showed that the LOI of the resin increased with the increase of nitrogen content,and the vertical combustion level of the resin could reach UL-94 V-1(LOI=30.3)when the nitrogen content was 13.3%.Then,phosphorus-nitrogen modified phenolic resin was prepared by using melamine and ODOPM.The flame retardant properties were characterized by limiting oxygen index,vertical combustion test and SEM.The results showed that with the increase of phosphorus and nitrogen content,the limiting oxygen index of resin increased gradually.When the nitrogen content was 6.07wt% and the phosphorus content was 1.14wt%,the vertical flame level of resin could reach UL-94 V-0(LOI=31.2).The phosphorus-nitrogen modified phenolic resin was applied to air filter paper,and the comprehensive strength,flame retardant property and microstructure of the filter paper were characterized by physical property test,horizontal combustion test and SEM.The results showed that when the phosphorus content was the same,the comprehensive strength of the filter paper increased with the increase of nitrogen content in the resin.With the increase of phosphorus and nitrogen content,the flame retardant property of the filter paper increased gradually.The results of air permeability test and SEM showed that the phosphorus-nitrogen modified phenolic resin had no obvious effect on the pore structure of filter paper.(3)Preparation and properties of flame-retardant air filter paper: Introduced phosphate ester and MF resin into the prepared phosphorus-nitrogen modified phenolic resin to further improve the comprehensive performance of flame retardant air filter paper.The effect of phosphate esters kinds,Mixing ratio,MF resin blending ratio and sizing amount of resins to the overall performance of air filter paper were studied.The comprehensive performance of the flame retardant air filter paper was characterized by physical performance test,flame retardant test,hygroscopicity test,washable test,aging resistance test,pore size test and SEM.The results showed that the combined strength and flame retardant property of the filter paper were the best when the phosphorus-nitrogen modified phenolic resin was blended with RDP.When the phosphorus-nitrogen modified phenolic resin was blended with 30wt% RDP and 20wt% MF,and the sizing amount reached 25wt%,the filter paper could be self-extinguished when the flame is removed.When the sizing amount reached 30wt%,the filter paper could reach level of horizontal noncombustible,the vertical flame level was F3,and with low hygroscopicity,good water resistance and good anti-aging properties.It can basically meet the performance requirements of flame-retardant air filter paper. |
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