Cellulose nanofiber powder and method for producing the same

A method for producing a cellulose nanofiber powder comprising:

• applying raw cellulose nanofibers dispersed in a solvent to a surface of a substrate sheet having wettability with respect to the solvent;
• irradiating the substrate sheet coated with the raw cellulose nanofibers with an electron beam when the raw cellulose nanofibers are wet or after the raw cellulose nanofibers are dried, and bringing the raw cellulose nanofibers into contact with a solution or dispersion containing a hydrophobic monomer so that the hydrophobic monomer is graft-polymerized onto the raw cellulose nanofibers, or mixing the raw cellulose nanofibers dispersed in the solvent with a hydrophobic monomer, applying the mixture to the surface of the substrate sheet, and irradiating the substrate sheet coated with the mixture with an electron beam so that the hydrophobic monomer is graft-polymerized onto the raw cellulose nanofibers;
• removing a graft-polymerized coating from the substrate sheet as a recovered material;
• washing an unreacted material from the recovered material;
• and
• drying the recovered material,
• wherein a hydrophobic polymer is chemically bonded to at least some of —OH groups of cellulose nanofibers of the cellulose nanofiber powder, and
• the cellulose nanofiber powder has an ability to be dispersed in water and to return to a powder form again when an aqueous dispersion of the cellulose nanofiber powder is dried.