Complex fibers of cellulose fibers with inorganic particles and processes for preparing them

Abstract

The present invention aims to provide complex fibers comprising a cellulose fiber strongly covered by a lot of inorganic particles on its surface. In the present invention, an excellent complex fiber of a cellulose fiber with inorganic particles can be prepared on the basis of the value of (D50−D10)/D50 calculated from the particle size distribution of (a) or (b) below: (a) the filtrate obtained by filtering an aqueous suspension of the complex fiber at a solids content of 0.1% through a 60-mesh sieve (having an opening of 250 μm); or (b) the fraction corresponding to an effluent volume (L) of 18.51 to 19.50 and an efflux time (sec) of 37.4 to 48.0 when an aqueous suspension of the complex fiber at a solids content of 0.3% is classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L/min, a water temperature of 25±1° C., and a total effluent volume of 22 L.

1 . A process for preparing a complex fiber of a cellulose fiber with inorganic particles, comprising the steps of:
 synthesizing inorganic particles in a solution containing a cellulose fiber to give a complex fiber; and   determining the particle size distribution of (a) or (b) below:
 (a) the filtrate obtained by filtering an aqueous suspension of the complex fiber at a solids content of 0.1% through a 60-mesh sieve (having an opening of 250 μm); or 
 (b) the fraction corresponding to an effluent volume (L) of 18.51 to 19.50 and an efflux time (sec) of 37.4 to 48.0 when an aqueous suspension of the complex fiber at a solids content of 0.3% is classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L/min, a water temperature of 25±1° C., and a total effluent volume of 22 L, 
 thereby calculating (D50−D10)/D50. 
   
     
     
         2 . The process of  claim 1 , wherein the aqueous suspension of the complex fiber is prepared in such a manner that (D50−D10)/D50 is 0.85 or less. 
     
     
         3 . The process of  claim 1 , wherein the complex fiber has an average fiber diameter of 500 nm or more. 
     
     
         4 . The process of  claim 1 , wherein the inorganic particles comprise a metal salt of calcium, magnesium, barium or aluminum, or metal particles containing titanium, copper or zinc, or a silicate. 
     
     
         5 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 1 . 
     
     
         6 . A complex fiber of a cellulose fiber with inorganic particles, wherein the value of (D50−D10)/D50 calculated from the particle size distribution of (a) or (b) below is 0.85 or less:
 (a) the filtrate obtained by filtering an aqueous suspension of the complex fiber at a solids content of 0.1% through a 60-mesh sieve (having an opening of 250 μm); or 
 (b) the fraction corresponding to an effluent volume (L) of 18.51 to 19.50 and an efflux time (sec) of 37.4 to 48.0 when an aqueous suspension of the complex fiber at a solids content of 0.3% is classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L/min, a water temperature of 25±1° C., and a total effluent volume of 22 L. 
 
     
     
         7 . A complex fiber of a cellulose fiber with inorganic particles, passing through a 60-mesh sieve (having an opening of 250 μm) when an aqueous suspension of the complex fiber at a solids content of 0.1% is processed through the sieve, wherein the value of (D50−D10)/D50 calculated from the particle size distribution of the filtrate having passed through the sieve is 0.85 or less. 
     
     
         8 . A complex fiber of a cellulose fiber with inorganic particles, derived from the fraction corresponding to an effluent volume (L) of 18.51 to 19.50 and an efflux time (sec) of 37.4 to 48.0 when an aqueous suspension of the complex fiber at a solids content of 0.3% is classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L/min, a water temperature of 25±1° C., and a total effluent volume of 22 L, wherein the value of (D50−D10)/D50 calculated from the particle size distribution of the fraction is 0.85 or less. 
     
     
         9 . A method for analyzing a complex fiber of a cellulose fiber with inorganic particles, comprising the step of:
 determining the particle size distribution of (a) or (b) below:
 (a) the filtrate obtained by filtering an aqueous suspension of the complex fiber at a solids content of 0.1% through a 60-mesh sieve (having an opening of 250 μm); or 
 (b) the fraction corresponding to an effluent volume (L) of 18.51 to 19.50 and an efflux time (sec) of 37.4 to 48.0 when an aqueous suspension of the complex fiber at a solids content of 0.3% is classified using a fiber classification analyzer under the conditions of a flow rate of 5.7 L/min, a water temperature of 25±1° C., and a total effluent volume of 22 L, 
 thereby calculating (D50−D10)/D50. 
   
     
     
         10 . The process of  claim 2 , wherein the complex fiber has an average fiber diameter of 500 nm or more. 
     
     
         11 . The process of  claim 2 , wherein the inorganic particles comprise a metal salt of calcium, magnesium, barium or aluminum, or metal particles containing titanium, copper or zinc, or a silicate. 
     
     
         12 . The process of  claim 10 , wherein the inorganic particles comprise a metal salt of calcium, magnesium, barium or aluminum, or metal particles containing titanium, copper or zinc, or a silicate. 
     
     
         13 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 2 . 
     
     
         14 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 3 . 
     
     
         15 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 4 . 
     
     
         16 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 10 . 
     
     
         17 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 11 . 
     
     
         18 . A process for preparing a complex fiber sheet, comprising the step of forming a sheet from a complex fiber obtained by the process of  claim 12 .