Abstract: A fine cellulose fiber-containing substance that has excellent dispersibility in water and can be manufactured easily. A method is for manufacturing the fine cellulose fiber-containing substance, and a method is for manufacturing a fine cellulose fiber dispersion. A fine cellulose fiber-containing substance contains fine cellulose fibers into which a phosphite containing a cation of an inorganic substance is introduced. The ratio of the cation of the inorganic substance with respect to 1 g of the fine cellulose fibers is 0.14 mmol or more. In manufacturing the fine cellulose fiber-containing substance, a phosphite is introduced into cellulose fibers, and then the cellulose fibers are defibrated to obtain a dispersion containing fine cellulose fibers, during which an alkali metal ion-containing substance is added to the cellulose fibers, and the dispersion is concentrated. In manufacturing a fine cellulose fiber dispersion, the fine cellulose fiber-containing substance is mixed with water.

Abstract: A method is for manufacturing cellulose microfibers in which a problem of yellowing of cellulose microfibers to be obtained was solved, and cellulose microfibers. As to a method for manufacturing cellulose microfibers, cellulose fibers are added with an additive (A) consisting of at least one of a phosphorous acid and a metal phosphite and an additive (B) consisting of at least one of urea and a urea derivative, heated and washed, then fibrillated. Also, as to cellulose microfibers, the fiber width is 1 to 1000 nm, and a part of hydroxy groups of cellulose fibers is substituted with a functional group represented by a predetermined structural formula to introduce an ester of phosphorous acid.

Abstract: Provided are: a fine cellulose fiber that is superior in handling properties and that can suitably be used as a reinforcing material or the like for resin; a production method of the fine cellulose fiber; and a slurry and a composite comprising the fine cellulose fibers. The present invention pertains to fine cellulose fibers comprising a carbamate group. The degree of substitution with the carbamate group with respect to hydroxy groups in the fine cellulose fibers is preferably no less than 0.05 and no greater than 0.5. The present invention pertains to a slurry comprising the fine cellulose fibers, to a composite comprising the fine cellulose fibers and a resin, and to a production method of the fine cellulose fibers, comprising performing a heat treatment on a mixture of a plant raw material and urea or the like, and performing a miniaturization treatment of the plant raw material.

Abstract: Fine cellulose fiber has a dispersion with a very high transparency and viscosity. A method is for producing the fine cellulose fiber. In the cellulose fiber, a part of hydroxy groups of cellulose fiber is substituted with a predetermined functional group to introduce an ester of phosphorus-oxo acid, and substituted with a carbamate group to introduce a carbamate. The method for producing fine cellulose fiber includes adding an additive (A) and an additive (B) including at least one of urea and a urea derivative to cellulose fiber, heating the mixture at 100 to 210° C., washing the mixture, and then fibrillating the mixture, the additive (B) being added in an amount of 0.01 to 100 mol based on 1 mol of the additive (A).

Abstract: A method is for manufacturing cellulose microfibers in which a problem of yellowing of cellulose microfibers to be obtained was solved, and cellulose microfibers. As to a method for manufacturing cellulose microfibers, cellulose fibers are added with an additive (A) consisting of at least one of a phosphorous acid and a metal phosphite and an additive (B) consisting of at least one of urea and a urea derivative, heated and washed, then fibrillated. Also, as to cellulose microfibers, the fiber width is 1 to 1000 nm, and a part of hydroxy groups of cellulose fibers is substituted with a functional group represented by a predetermined structural formula to introduce an ester of phosphorous acid.

Abstract: An object is to establish a technique for producing a resin composite material at low cost. A resin composition contains cellulose fibers, a fibrillation aid, and a resin.