Flame Retardancy And Water Repellent Finish Of Cotton And Wool Fabric By Phosphorus-doped Silica Sol

Phosphorous-doped silica hydrosol was synthesized by sol-gel method and was applied to cotton and wool fabric to endow fabric with flame retardancy and hydrophobicity.The effect of solution on fabric flame resistance and water repellence was discussed in this paper.Firstly,ammonium dihydrogen phosphate was chosen as a flame retardant added into silica hydrosol which was prepared by methyltrimethoxysilane and tetraethoxysilane as precursors.Then hexadecyltrimethoxysilane was introduced as a long-chain compound to obtain water repellency.The optimal process was determined by investigating the influence of dosage on the limited oxygen index(LOI)and contact angle(CA)of cotton and wool fabric.The LOI and CA value of finished cotton fabric reached 29.2% and 135.2° while wool fabric were up to 29.4% and 129.2°.The thermal stability and smoke suppression of treated fabric were discussed through micro combustion calorimeter(MCC),thermo gravimetric analysis(TG)and smoke density test.The results indicated the good flame resistance of finished cotton and wool fabric.However,this process belongs to a non-durable treatment.Secondly,hexamethylenediamine-N,N,N',N'-tetrakis(HDTMPA)and urea were used as reactants to synthesize a flame retardant named AHDTMPA under suitable condition.Other reactants were same as the above chapter.Then,silica hydrosol was prepared by one-step process with the addition of AHDTMPA and applied to cotton and wool fabric with 1,2,3,4-butanetetrcarboxylic acid(BTCA)as crosslinking agent.Taking wool fabric into consideration,the SEM and EDS test results showed that the surface of finished wool fabric emerged a complete film which still retained integrity to some extent after 10 times washing with 28.2% of LOI value.This result presented the improvement of durable flame resistance of wool fabric.Meanwhile,the CA value of wool fabric remianed 127.7°,only 3.2% decreased compared with non-washed fabric,which presented the treated wool fabric possess durable water repellency.EDS results indicated the exisitance of phosphorous and silicon element on finished fabric,which showed the flame retardant and silica sol were adsorbed onto fabric successfully.On the basis of above chapter,the finished cotton and wool fabric were obtained through padding into flame silica hydrosol and then dipping into hydrophobic solution by two-step treatment method.The optimal process,treatment order and hydrophobic agent were determined via the infulence of LOI and CA value of wool fabric before and after washing.The FT-IR analysis indicated the existence of silicon and phosphorous element on fabric.In addition,the MCC,TG,smoke density and vertical flame test results demonstrated that the heat release ratio was decreased,weight loss residue and smoke suppression were improved,and the flame retardance washing durability of wool fabric was promoted.