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

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.

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.

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.