Study On Hydrophobic Modification Of Ultrafine Ammonium Polyphosphate

In recent years,the development trend of ammonium phosphate dry powder fire extinguishing agent at home and abroad is to optimize the formulation and the direction of ultra refinement.Ammonium polyphosphate superfine powder posesses lager surfuce,surface activity and fire extinguishing efficiency would be greatly enhanced,but the ammonium polyphosphate superfine powder posesses high surface energy,and reacted with moisture easily to cake,thus affecting the use of fire extinguishing agent,flow,dispersion and storage performance.The reasearch purpose of this thesis is to modificate ammonium polyphosphate ultrafine powder with different particle size to reduce hygroscopicity and caking capatibility,and a detailed study of the change of various factors of the process and mechanism of modification.We selected methyl hydrogen silicone oil as modifier,activated clay,talcum powder,mica powder and hydrophobic silica as accessories,SHR high-speed mixer was for the dry modification technology and hydrophobic modified of ultrafine ammonium polyphosphate.The study results show that the optimal process conditions of ultrafine ammonium polyphosphate(the particle size is 12 ?m)surface modification:when the amount of ultrafine ammonium polyphosphate is 1kg,methyl hydrogen silicone oil to add content is 1.6%,activated clay content is 2.0%,talcum powder 3.0%,mica powder 6.0%,gas phase hydrophobic silica addition is 5.0%,the dispersion temperature is 55? to 60?,the film forming temperature is from 100? to 105? and the stirring rate is 1000 r/min-400 r/min-1200 r/min,the modification time is 130min-150min,which the retention rate of the modified ultrafine ammonium polyphosphate was about 94.5%,liquidity is 4(s/300g),the moisture absorption rate is about 0.65%.By SEM infrared FTIR and XPS analysis showed that:the surface of ultrafine ammonium polyphosphate was coated with methyl hydrogen silicone oil and gas phase hydrophobic silica.The wettability of the modified ultrafine ammonium polyphosphate was measured by the static contact angle,and the contact angle was found to be 140.69°,which was increased by about 120° than that of the unmodified ultrafine ammonium polyphosphate(26.24°),the modification of ultrafine ammonium polyphosphate compared with unmodified ultrafine ammonium polyphosphate has good hydrophobicity;The optimal process conditions of ultrafine ammonium polyphosphate(the particle size is 5?m)surface modification:when the amount of ultrafine ammonium polyphosphate is 1 kg,methyl hydrogen silicone oil to add content is 3.5%,activated clay content is 2.0%,talcum powder 6.0%,mica powder 3.0%,gas phase hydrophobic silica addition is 3.0%,the dispersion temperature is 55? to 60?,the film forming temperature is from 100? 105?m,and the stirring rate is 1000 r/min-400 r/min-1200 r/min,the modification time is 160 min-180 min,which the hydrophobic retention rate of ultrafine ammonium polyphosphate was more than 90%,and liquidity is 7(s/300g),the moisture absorption rate is about 1.88%,and the contact angle is 127.87°.Through the study on the surface modification of ultrafine ammonium polyphosphate with particle size of 12 ?m,it can be divided into two parts:first,the modification of ultrafine ammonium polyphosphate with methyl hydrogen containing silicone oil as the surface chemical modification,when methyl hydrogen containing silicone oil was used to modify ultrafine ammonium polyphosphate,firstly,methyl hydrogen silicone oil is hydrolyzed,and then the hydrolysis of methyl hydrogen-containing silicone oil and superfine ammonium polyphosphate surface hydroxyl polymerization occurs and a small part of the silicone oil for intermolecular polymerization,to be completed after polymerization,in the ultrafine ammonium polyphosphate surface curing to form silicone oil film,improve hydrophobic performance;Two,the modification of ultrafine ammonium polyphosphate with hydrophobic silica as the physical modification,hydrophobic silica was first filled in the gap of ultrafine ammonium polyphosphate,and when filled with a certain amount,the hydrophobic silica will cover the entire surface of the ultrafine ammonium polyphosphate.The modified ultrafine ammonium polyphosphoric(the particle size is 5 ?m)was compared with commercial general extinguishing agent for fire fighting experiments of class A and B fire.The experimental results show that the extinguishing property of modified ultrafine ammonium polyphosphoric is better than that of commercial general extinguishing agent.