Spongelike Structure and Powder, As Well As Process for Producing the Same

Abstract

An object of the present invention is to provide a spongelike structure or a powder having fibers three-dimensionally arranged therein with high dispersibility, whose apparent density can be designed depending on the purpose or utility, as well as a process producing them. A fiber dispersion in which fibers having a number mean diameter in a predetermined range are dispersed in a dispersion medium, and this fiber dispersion is dried to remove the dispersion medium, thereby, a spongelike structure and a powder are produced.

1 . A spongelike structure in which a fiber having a number mean diameter of 1 nm to 50 μm is fixed in the dispersed state. 
   
   
       2 . The spongelike structure according to  claim 1 , wherein the fiber comprises a thermoplastic polymer. 
   
   
       3 . The spongelike structure according to  claim 1 , wherein a number mean diameter of the fiber is 1 to 500 nm. 
   
   
       4 . The spongelike structure according to  claim 1 , wherein an apparent density is 0.0001 to 0.5 g/cm 3 . 
   
   
       5 . The spongelike structure according to  claim 1 , wherein a number mean size of a micropore constituted by the fiber is not more than 100 μm. 
   
   
       6 . The spongelike structure according to  claim 1 , wherein the fibers are partially adhered. 
   
   
       7 . A heat insulator comprising the spongelike structure as defined in  claim 1 . 
   
   
       8 . An acoustic material comprising the spongelike structure as defined in  claim 1 . 
   
   
       9 . A cell scaffold material comprising the spongelike structure as defined in  claim 1 . 
   
   
       10 . The cell scaffold material according to  claim 9 , wherein a number mean size of a macropore present in the spongelike structure is 10 μm to 500 μm. 
   
   
       11 . The cell scaffold material according to  claim 9 , wherein a functional material is adsorbed and/or fixed on a surface of the fiber. 
   
   
       12 . The cell scaffold material according to  claim 11 , wherein the functional material is a protein. 
   
   
       13 . A process for producing a spongelike structure, comprising drying a fiber dispersion in which a fiber having a number mean diameter of 1 nm to 50 μm is dispersed in dispersion media, and removing the dispersion media. 
   
   
       14 . The process for producing a spongelike structure according to  claim 13 , wherein a number mean diameter of the fiber is 1 to 500 nm. 
   
   
       15 . The process for producing a spongelike structure according to  claim 14 , wherein a fiber constituent ratio of single fibers having a diameter of more than 500 nm is not more than 3% by weight. 
   
   
       16 . The process for manufacturing a spongelike structure according to  claim 13 , wherein the fiber comprises a thermoplastic polymer. 
   
   
       17 . The process for producing a spongelike structure according to  claim 13 , wherein a cut fiber length of the fiber is 0.2 mm to 30 mm. 
   
   
       18 . The process for producing a spongelike structure according  claim 13 , wherein the drying is freeze drying. 
   
   
       19 . The process for producing a spongelike structure according to  claim 18 , wherein a freezing temperature upon freeze drying is not lower than −80° C. and not higher than −20° C. 
   
   
       20 . The process for producing a spongelike structure according to  claim 13 , wherein pressurized steam treatment is further performed after removal of dispersion media. 
   
   
       21 . A powder comprising a fiber having a number mean diameter of 1 to 500 nm, wherein a number mean size of the powder is 1 to 1000 μm. 
   
   
       22 . The powder according to  claim 21 , wherein the fiber comprises a thermoplastic polymer. 
   
   
       23 . The powder according to  claim 21 , wherein the fibers are partially adhered. 
   
   
       24 . A paint comprising the powder as defined in  claim 21 . 
   
   
       25 . A cosmetic comprising the powder as defined in  claim 21 . 
   
   
       26 . A process for producing a powder, comprising granulating and drying a fiber dispersion in which a fiber having a number mean diameter 1 to 500 nm is dispersed in dispersion media, to remove the dispersion media. 
   
   
       27 . The process for producing a powder according to  claim 26 , wherein the fiber dispersion is granulated and dried by spray drying. 
   
   
       28 . The process for producing a powder according to  claim 26 , wherein the fiber comprises a thermoplastic polymer. 
   
   
       29 . The process for producing a powder according to  claim 26 , wherein the fiber is such that a fiber constituent ratio of single fibers having a diameter more than 500 nm is not more than 3% by weight. 
   
   
       30 . The process for producing a powder according to  claim 26 , wherein pressurized steam treatment is further performed after removal of the dispersion media.