Copolymide nano-fiber non-woven fabric, process for producing the same and the use thereof

Abstract

A copolyimide nano-fiber non-woven fabric, a process for producing the same and the use thereof. The process comprises the following steps: tetracid dianhydride monomer and diamine monomer are polycondensated in the reaction medium of a high polar solvent under mechanical agitation to form a solution of a copolyamic acid; the copolyamic acid solution is electrostatically spinned under a high voltage electric field to give a non-woven fabric of a nano-fiber of the copolyamic acid; and then the non-woven fabric is imidized. The copolyimide nano-fiber non-woven fabric has features of a strong tear resistance, a high porosity, high/low-temperature resistances and excellent mechanical properties, etc., and can be used in battery membrane and capacitor membrane.

1 .- 13 . (canceled) 
     
     
         14 . A copolyimide nano-fiber non-woven fabric, characterized in that the non-woven fabric is formed by the copolymerization of the following four monomers of (I), (II), (III) and (IV) to form a copolyamic acid, then electrostatical spinning and imidization: 
       
         
           
           
               
               
           
         
         said copolyimide nano-fiber is formed by the copolymerization of the above four monomers of (I), (II), (III) and (IV), wherein the molar ratio relationship of the four monomers is [(I)+(II)]:[(III)+(IV)]=1:1; wherein the copolyimide has the following chemical structure formula: 
       
       
         
           
           
               
               
           
         
         n is a natural number between 50-300; m is a natural number between 50-300, R 1  and R 3  are C 4 -C 30  tetracid dianhydride monomer residue structures; R 2  and R 4  are C 6 -C 30  diamine monomer residue structures; the ratio of the total mole number of the tetracid dianhydride monomers to the total mole number of the diamine monomers in the copolymerization reaction is always kept at 1:1; and said copolyimide nano-fiber non-woven fabric has breaking elongation of 20-30%, a porosity of 80-86%, tensile strength of 20-25 MPa, electrical breakdown strength of 1×10 7 -1.5×10 7  V/m, and a thermal decomposition temperature of 510-560° C. 
       
     
     
         15 . The copolyimide nano-fiber non-woven fabric according to  claim 14 , characterized in that R 1  and R 3  are selected from one of the following tetracid dianhydride residue structures, respectively 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         16 . The copolyimide nano-fiber non-woven fabric according to  claim 14 , characterized in that R 2  and R 4  are selected from one of the following diamine residue structures, respectively: 
       
         
           
           
               
               
           
         
         
           
           
               
               
           
         
       
     
     
         17 . A process for producing the copolyimide nano-fiber non-woven fabric according to  claim 14 , characterized in that the process comprises
 (1) purifying the four monomers, adding into a polymerization reaction kettle together with an appropriate amount of a solvent, reacting under agitation for a time period to obtain a solution of a copolyamic acid, electrostatical spinning the copolyamic acid solution in a high voltage electric field, and collecting using a stainless steel roller as a collector to obtain a non-woven fabric of a nano-fiber of the copolyamic acid, wherein said solvent is N,N-dimethyl formamide (DMF) or N,N-dimethyl acetamide (DMAC) in polar solvents; the polymerization reaction temperature of said reaction kettle is 0-30° C.; the reaction time is 1-10 h; and the electric field intensity of the high voltage electric field is 250-300 Kv;   (2) placing the obtained non-woven fabric of a nano-fiber of the copolyamic acid in a high temperature furnace, and heating for imidization; and the temperature rise program of said imidization process includes heating from room temperature to 200-250° C. at a temperature rise rate of 20° C./min, and maintaining at the temperature for 30 min, heating to 330-370° C. at a temperature rise rate of 5° C./min, and maintaining at the temperature for 30 min, and shutting off the power source.