An object of the present invention is to provide ultrafine fibrous cellulose capable of exhibiting excellent coating suitability when added to paint. The present invention relates to fibrous cellulose having a fiber width of 1,000 nm or less, in which, when the fibrous cellulose is dispersed in water to form a dispersion liquid having a viscosity of 2,500 mPa.Math.s at 23? C., and the dispersion liquid is stirred under predetermined stirring conditions, a viscosity change rate falls within ?50%, calculated by the following formula: viscosity change rate (%)=(viscosity after stirring?viscosity before stirring)/viscosity before stirring?100.

The present disclosure relates to lignocellulosic materials comprising phosphorylated lignocellulosic fibers having an ionic charge in water of about 4000 to about 7000 mmoles/kg, and processes for the preparation thereof. The process comprises reacting lignocellulosic fibers of a lignocellulosic material with a phosphate ester in the presence of urea. The present disclosure further relates to compositions comprising a phosphate ester and at least one of a defoamer and a viscosity reducer or at least one of a C1-C12 alcohol and an ester of a carboxylic acid.

The present disclosure relates to lignocellulosic materials comprising phosphorylated lignocellulosic fibers having an ionic charge in water of about 4000 to about 7000 mmoles/kg, and processes for the preparation thereof. The process comprises reacting lignocellulosic fibers of a lignocellulosic material with a phosphate ester in the presence of urea. The present disclosure further relates to compositions comprising a phosphate ester and at least one of a defoamer and a viscosity reducer or at least one of a C1-C12 alcohol and an ester of a carboxylic acid.

It is an object of the present invention to provide a method for producing ultrafine fibrous cellulose, which is capable of efficiently obtaining ultrafine fibrous cellulose having phosphoric acid groups with a high yield. The present invention relates to a method for producing fibrous cellulose having a fiber width of 1000 nm or less, comprising: a (A) of introducing phosphoric acid groups into cellulose fibers to form crosslinked structures via the phosphoric acid groups, thereby obtaining crosslinked phosphorylated cellulose fibers, a (B) of breaking some or all of the crosslinked structures to obtain crosslink-broken phosphorylated cellulose fibers, and a (C) of performing a mechanical treatment on the crosslink-broken phosphorylated cellulose fibers to obtain fibrous cellulose having a fiber width of 1000 nm or less, wherein, in the (A), crosslinked structures in an amount of 0.05 mmol/g or more and 2.0 mmol/g or less are formed, and the (B) is a step of performing the hydrolysis of the crosslinked structures in an aqueous solvent with pH 3 or more.

It is an object of the present invention to provide a method for producing ultrafine fibrous cellulose, which is capable of efficiently obtaining ultrafine fibrous cellulose having phosphoric acid groups with a high yield. The present invention relates to a method for producing fibrous cellulose having a fiber width of 1000 nm or less, comprising: a (A) of introducing phosphoric acid groups into cellulose fibers to form crosslinked structures via the phosphoric acid groups, thereby obtaining crosslinked phosphorylated cellulose fibers, a (B) of breaking some or all of the crosslinked structures to obtain crosslink-broken phosphorylated cellulose fibers, and a (C) of performing a mechanical treatment on the crosslink-broken phosphorylated cellulose fibers to obtain fibrous cellulose having a fiber width of 1000 nm or less, wherein, in the (A), crosslinked structures in an amount of 0.05 mmol/g or more and 2.0 mmol/g or less are formed, and the (B) is a step of performing the hydrolysis of the crosslinked structures in an aqueous solvent with pH 3 or more.

An object of the invention is to provide a material or composition comprising ultrafine cellulose fibers having excellent fluidity. The invention relates to a composition comprising a particulate material comprising ultrafine cellulose fibers and water, and (B) a non-cellulose particulate material in which the water content of the composition is 2 to 94% by mass with respect to the total mass of the composition, and the content of (B) the non-cellulose particulate material is 0.1 to 12% by mass with respect to the total mass of the composition. The invention also relates to a method for producing the composition and a method for producing a material comprising ultrafine cellulose fibers.

It is an object of the present invention is to provide a sheet containing ultrafine cellulose fibers, which is excellent in transparency and water resistance. The present invention relates to a sheet including cellulose fibers having a fiber width of 1000 nm or less, and polyamine polyamide epihalohydrin, wherein the haze of the sheet is 6% or less.

A method of modifying a polymer having hydroxyl groups, selected from the group of polysaccharides and lignin, to give a modified polymer comprising the step of contacting said polymer with at least one organic phosphonate salt in order to chemically modify the polymer, said organic phosphonate salt being in a liquid phase. The method of polymer modification provides novel polymers. Modified polymers obtained from a polymer having been treated with at least one organic phosphonate salt are also disclosed. The modified polymers can be used as such or separated and optionally recovered from the solution, optionally being formed into particular materials or shapes.

A method of modifying a polymer having hydroxyl groups, selected from the group of polysaccharides and lignin, to give a modified polymer comprising the step of contacting said polymer with at least one organic phosphonate salt in order to chemically modify the polymer, said organic phosphonate salt being in a liquid phase. The method of polymer modification provides novel polymers. Modified polymers obtained from a polymer having been treated with at least one organic phosphonate salt are also disclosed. The modified polymers can be used as such or separated and optionally recovered from the solution, optionally being formed into particular materials or shapes.

It is an object of the present invention to provide a resin composite that is excellent in water resistance and is capable of exerting sufficient strength even under wet conditions. The present invention relates to a resin composite comprising a resin, fibers having an ionic functional group, and a polyvalent ion. The fibers having an ionic functional group are preferably cellulose fibers having a fiber width of 1000 nm or less.