Abstract: It is an object of the present invention to provide a resin composite comprising ultrafine cellulose fibers, in which deterioration of a resin component is suppressed. The present invention relates to a cellulose fiber-containing resin composition comprising cellulose fibers with a fiber width of 1000 nm or less having phosphoric acid groups or phosphoric acid group-derived substituents, and a resin, wherein the counterions of the phosphoric acid groups or phosphoric acid group-derived substituents are organic onium ions, and the conjugate bases of the organic onium ions have a pKb value of 1.0 or more.

Abstract: It is an object of the present invention to provide ultrafine cellulose fibers capable of exhibiting favorable dispersibility even in an organic solvent. The present invention relates to cellulose fibers having a fiber width of 1000 nm or less and having phosphoric acid groups or phosphoric acid group-derived substituents, wherein the content of the phosphoric acid groups or phosphoric acid group-derived substituents is 0.5 mmol/g or more, and the supernatant yield measured by an measurement method (a) is 70% or less.

Abstract: An object is to optimize a bleaching process in a step of producing phosphorylated cellulose fibers. A pulp comprises cellulose fibers having 0.5 mmol/g or more of phosphoric acid groups or phosphoric acid group-derived substituents, when the pulp is processed into a sheet and four sheets are laminated on one another, the ISO whiteness of the laminate is 82% or more. Moreover, when the pulp is processed into a sheet and four sheets are then laminated on one another, the b* value of the obtained laminate according to the L*a*b* color system is 5.5 or less.

Abstract: It is an object of the present invention to optimize a bleaching process in a step of producing phosphorylated cellulose fibers. The present invention relates to a pulp comprising cellulose fibers having 0.5 mmol/g or more of phosphoric acid groups or phosphoric acid group-derived substituents, wherein when the pulp is processed into a sheet and four sheets are laminated on one another, the ISO whiteness of the laminate is 82% or more. Moreover, when the pulp of the present invention is processed into a sheet and four sheets are then laminated on one another, the b* value of the obtained laminate according to the L*a*b* color system is 5.5 or less.

Abstract: The present invention is intended to provide ultrafine cellulose fibers capable of enhancing the transparency of an ultrafine cellulose fiber-dispersed solution having phosphorous acid groups. The present invention relates to a method for producing cellulose fibers, comprising: mixing a compound having a phosphorous acid group and/or a salt thereof and urea and/or a urea derivative into a cellulose raw material to obtain a phosphorous acid esterified cellulose raw material, and performing a fibrillation treatment on the phosphorous acid esterified cellulose raw material to obtain cellulose fibers having a fiber width of 1000 nm or less and having a phosphorous acid group, wherein, in obtaining the phosphorous acid esterified cellulose raw material, the decomposition percentage of the urea and/or the urea derivative is set to be 90% or less.

Abstract: It is an object of the present invention to provide a fluffed cellulose having totally new properties that have not conventionally existed, and a cellulose fiber-containing material capable of realizing the same. The present invention relates to a cellulose fiber-containing material comprising cellulose fibers having anionic groups, wherein the yield of the cellulose fiber-containing material measured by the following measurement method is 50% by mass or more, the cellulose fiber-containing material has organic onium ions as counterions of the anionic groups, and the organic onium ions satisfy a predetermined condition.

Abstract: It is an object of the present invention to provide an ultrafine cellulose fiber-containing composition, regarding which an ultrafine cellulose fiber-dispersed organic solvent slurry can exhibit high viscosity and high transparency. The present invention relates to a cellulose fiber-containing composition comprising cellulose fibers with a fiber width of 1000 nm or less having anionic groups, and metal ions, wherein the cellulose fiber-containing composition comprising organic onium ions as counterions of the anionic groups, and when a solid in the cellulose fiber-containing composition is converted to an absolute dry solid, the content of the metal ions in the absolute dry solid is 80 ppm or more and 700 ppm or less.

Abstract: It is an object of the present invention to provide a resin composite comprising ultrafine cellulose fibers, in which deterioration of a resin component is suppressed. The present invention relates to a cellulose fiber-containing resin composition comprising cellulose fibers with a fiber width of 1000 nm or less having phosphoric acid groups or phosphoric acid group-derived substituents, and a resin, wherein the counterions of the phosphoric acid groups or phosphoric acid group-derived substituents are organic onium ions, and the conjugate bases of the organic onium ions have a pKb value of 1.0 or more.

Abstract: The present invention is intended to provide a resin composition capable of suppressing separation between ultrafine cellulose fibers and a resin, and also capable of forming a film having excellent adhesiveness to a base material. The present invention relates to a method for producing a cellulose fiber-containing film, comprising: mixing cellulose fibers having a fiber width of 1000 nm or less with organic onium; mixing the cellulose fiber mixture obtained in the mixing step, an organic solvent and a resin to obtain a resin composition; and applying the resin composition onto a base material, wherein the cellulose fibers have anionic groups, and the content of the anionic groups is 0.50 mmol/g or more, and the content of the cellulose fibers in the resin composition is 1% by mass or more.

Abstract: It is an object of the present invention to optimize a bleaching process in a step of producing phosphorylated cellulose fibers. The present invention relates to a pulp comprising cellulose fibers having 0.5 mmol/g or more of phosphoric acid groups or phosphoric acid group-derived substituents, wherein when the pulp is processed into a sheet and four sheets are laminated on one another, the ISO whiteness of the laminate is 82% or more. Moreover, when the pulp of the present invention is processed into a sheet and four sheets are then laminated on one another, the b* value of the obtained laminate according to the L*a*b* color system is 5.5 or less.

Abstract: It is an object of the present invention to provide ultrafine cellulose fibers capable of exhibiting favorable dispersibility even in an organic solvent. The present invention relates to cellulose fibers having a fiber width of 1000 nm or less and having phosphoric acid groups or phosphoric acid group-derived substituents, wherein the content of the phosphoric acid groups or phosphoric acid group-derived substituents is 0.5 mmol/g or more, and the supernatant yield measured by an measurement method (a) is 70% or less.

Abstract: A composition provides a high-bulk cellulose fiber-containing sheet, in which the water-retaining ability of the cellulose fibers is sufficiently high, and the water-absorbing rate is large. The composition contains cellulose fibers having phosphoric acid groups or phosphoric acid group-derived substituents. In at least a part of the cellulose fibers, the phosphoric acid groups or the phosphoric acid group-derived substituents are crosslinked. The number of crosslinking points in the cellulose fibers, which is calculated according to the following Equation (1), is 0.20 mmol/g or more, and the water content is 50% by mass or less, with respect to the total mass of the composition: Number of crosslinking points=(amount of strongly acidic groups contained in cellulose fibers?amount of weakly acidic groups contained in cellulose fibers)/2 . . . Equation (1).