Polymer nanofiber sheet and method of producing the sheet

Abstract

Provided is a polymer nanofiber sheet having high delamination resistance, a high mechanical strength, and a high specific surface area. Specifically, provided is a polymer nanofiber sheet, including polymer nanofibers, the polymer nanofibers being laminated and three-dimensionally entangled with each other, in which: at least part of the polymer nanofibers are crosslinked at a crosslinked part having crosslinking portions and a non-crosslinking portion; and the crosslinked part contains a low-molecular weight epoxy compound having a molecular weight of from 100 to 3,000.

What is claimed is: 
     
         1 . A polymer nanofiber sheet, comprising polymer nanofibers, the polymer nanofibers being laminated and three-dimensionally entangled with each other, wherein:
 at least part of the polymer nanofibers are crosslinked at a crosslinked part having crosslinking portions and a non-crosslinking portion; and   the crosslinked part contains a low-molecular weight epoxy compound having a molecular weight of from 100 to 3,000.   
     
     
         2 . A polymer nanofiber sheet according to  claim 1 , wherein the polymer nanofibers each contain a functional group constituting the low-molecular weight epoxy compound. 
     
     
         3 . A polymer nanofiber sheet according to  claim 2 , wherein the functional group constituting the low-molecular weight epoxy compound comprises a functional group in the non-crosslinking portion. 
     
     
         4 . A polymer nanofiber sheet according to  claim 1 , wherein a repeating structure constituting each of the polymer nanofibers includes an imide structure. 
     
     
         5 . A polymer nanofiber sheet according to  claim 4 , wherein the polymer nanofibers each contain polyamide imide. 
     
     
         6 . A method of producing the polymer nanofiber sheet of  claim 1 , comprising:
 a sheet-forming step of spinning a polymer solution containing a low-molecular weight epoxy compound having a molecular weight of from 100 to 3,000 to form a sheet comprising polymer nanofibers; and   a crosslinking step of crosslinking at least part of the polymer nanofibers constituting the sheet through heating treatment.   
     
     
         7 . A method of producing the polymer nanofiber sheet according to  claim 6 , wherein the polymer solution further contains a latent catalyst. 
     
     
         8 . A method of producing the polymer nanofiber sheet according to  claim 7 , wherein the latent catalyst comprises a thermal cationic polymerization initiator.