Preparation Of Melamine Flame-retardant Fibers By Screening Ionic Liquids With COSMO-RS

Melamine fibers are a high-performance flame-retardant fiber with three-dimensional network cross-linking structure,which are made from melamine,formaldehyde by special spinning process.Because of its excellent flame-retardant properties,it is widely used in firefighting equipment,high temperature filter materials,flame retardant fabrics and other fields.However,as a kind of thermosetting resin with network cross-linking structure,MF resin has poor spinnability and low strength,which limits further development and application of melamine fibers.Domestic researches of melamine fibers are mainly to improve its spinnability by adding fiber-forming polymer into the spinning solution,and most of which are on the blending of PVA and MF.Although the spinnability has been improved obviously,the problems,such as poor stability of spinning solution and poor washing durability of modified fiber,are still unsolved,so it is difficult to realize completely independent industrial production.Therefore,it is very meaningful to systematically develop a melamine fibers preparation technology with independent intellectual property rights.This paper has developed a new technology of melamine fibers preparation,which is based on ILs as solvent,melamine formaldehyde resin prepolymer(pre-MF)as flame-retardant material and cellulose as carrier.This technology is expected to open up a new way for industrialization of melamine fibers.This project adopts the method of combining simulation prediction and experimental exploration.Firstly,the preparation conditions of water-insoluble pre-MF were explored and optimized.Then,the molecular model of pre-MF was optimized by quantum chemistry method(Gaussian09)and the ln ? of 3 optimized pre-MF models in 432 ILs were calculated by COSMO-RS method.According to the prediction results of COSMO-RS,8 ILs with different dissolution for pre-MF were selected,and the solubility of pre-MF in 8 ILs was tested to verify the feasibility of COSMO-RS method in predicting the dissolution ability of ILs to pre-MF.Finally,MF/cellulose composite flame-retardant fiber was prepared by dry spray wet spinning method with ILs as solvent,pre-MF as flame retardant material and cellulose as carrier.The effects of spinning temperature,solid content of cellulose in spinning solution,ratio of pre-MF to cellulose on spinnability and the effects of pre-MF content on fiber properties were investigated in detail.The study found that: the water-insoluble pre-MF could be prepared under the conditions of M : F = 1 : 2.5(molar ratio),p H 8.5 and reaction temperature 80 ?.The solubility of preMF in 8 ILs was consistent with the trend of the ln ? predicted by COSMO-RS,which verified the feasibility of COSMO-RS method in predicting the dissolution ability of ILs to pre-MF.MF/cellulose composite flame-retardant fibers were successfully prepared by dry spray wet spinning method with ILs as solvent,pre-MF as flame retardant material and cellulose as carrier.When the content of pre-MF in the fiber reached 30%,the mechanical properties and flame retardant properties of the composite fibers were significantly improved.The limiting oxygen index(LOI)of MF/cellulose composite flame-retardant fiber prepared in this project is up to37.4%,and it has good mechanical properties.Therefore,MF/cellulose composite flame retardant fiber prepared by ionic liquid method is competitive in the same type of flame retardant fiber materials.