It is an object of the present invention to provide a cellulose-containing composition having excellent coating suitability, a production method thereof, and a film. According to the present invention, provided is a cellulose-containing composition comprising cellulose fibers having a fiber width of 1000 nm or less and protein, wherein the protein includes an enzyme, the content of the protein is 1×10.sup.−3 parts by mass or less with respect to 1 part by mass of the cellulose fibers, and when the cellulose-containing composition having a solid concentration of 0.4% by mass is obtained, the viscosity of the cellulose-containing composition measured under conditions of 25° C. and a rotation number of 3 rpm is 10 mPa.Math.s or more and 11000 mPa.Math.s or less.

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.

A fine cellulose fiber in which when the fine cellulose fiber is formed into a dispersion, the dispersion has very high light transmittance and viscosity, and a method for producing the fine cellulose fiber. The fine cellulose fiber has a fiber width of 1 to 200 nm. A part of hydroxy groups of the cellulose fiber are substituted with a predetermine functional group to introduce an ester of phosphorus-oxo acid, and the introduction amount of the functional group is more than 2.0 mmol per 1 g of the cellulose fiber. For producing the fine cellulose fiber, to cellulose fiber is added a solution having a pH of less than 3.0 and including an additive (A) containing at least one of a phosphorus-oxo acid and a phosphorus-oxo acid metal salt and an additive (B) containing at least one of urea and a urea derivative, and the mixture is heated to perform fibrillation.

A fine cellulose fiber in which when the fine cellulose fiber is formed into a dispersion, the dispersion has very high light transmittance and viscosity, and a method for producing the fine cellulose fiber. The fine cellulose fiber has a fiber width of 1 to 200 nm. A part of hydroxy groups of the cellulose fiber are substituted with a predetermine functional group to introduce an ester of phosphorus-oxo acid, and the introduction amount of the functional group is more than 2.0 mmol per 1 g of the cellulose fiber. For producing the fine cellulose fiber, to cellulose fiber is added a solution having a pH of less than 3.0 and including an additive (A) containing at least one of a phosphorus-oxo acid and a phosphorus-oxo acid metal salt and an additive (B) containing at least one of urea and a urea derivative, and the mixture is heated to perform fibrillation.

The invention relates to cellulose esters, the ester groups of which are at least partially containing phosphorus and are based on unsaturated carboxylic acids and reactive phosphorus components, wherein the latter are preferably phosphorus derivatives of sugar alcohols or of tartaric acid derivatives. The invention also relates to methods for preparing novel phosphorus-containing cellulose esters and to their use as flame retardants for plastics.

The invention relates to cellulose esters, the ester groups of which are at least partially containing phosphorus and are based on unsaturated carboxylic acids and reactive phosphorus components, wherein the latter are preferably phosphorus derivatives of sugar alcohols or of tartaric acid derivatives. The invention also relates to methods for preparing novel phosphorus-containing cellulose esters and to their use as flame retardants for plastics.

It is an object of the present invention to provide a thickener capable of exhibiting excellent light resistance. The present invention relates to a thickener comprising cellulose fibers having a fiber width of 8 nm or less and water, wherein the thickener is a slurry or a gel, and when the thickener is filled in a colorless and transparent glass cell having an inside dimension of 1 cm in depth×4 cm in width×4.5 cm in height and the thickener is then irradiated with ultraviolet rays with a wavelength of 300 nm or more and 400 nm or less, using a xenon lamp, from the side of the maximum area surface of the glass cell, so as to be an irradiance of 180 W/m.sup.2 and an integrated light amount of 500 mJ/m.sup.2, the amount of a change in the yellowness before and after ultraviolet irradiation measured in accordance with JIS K 7373 is 10 or less.

It is an object of the present invention to provide a thickener capable of exhibiting excellent light resistance. The present invention relates to a thickener comprising cellulose fibers having a fiber width of 8 nm or less and water, wherein the thickener is a slurry or a gel, and when the thickener is filled in a colorless and transparent glass cell having an inside dimension of 1 cm in depth×4 cm in width×4.5 cm in height and the thickener is then irradiated with ultraviolet rays with a wavelength of 300 nm or more and 400 nm or less, using a xenon lamp, from the side of the maximum area surface of the glass cell, so as to be an irradiance of 180 W/m.sup.2 and an integrated light amount of 500 mJ/m.sup.2, the amount of a change in the yellowness before and after ultraviolet irradiation measured in accordance with JIS K 7373 is 10 or less.

It is an object of the present invention to provide fine fibrous cellulose capable of enhancing transparency and suppressing coloring, when the fine fibrous cellulose are processed into a dispersed solution or a sheet. The present invention relates to fine fibrous cellulose, in which the amount of substituents introduced is less than 0.5 mmol/g and the fiber width is 1 to 10 nm. Moreover, the present invention relates to a dispersed solution and a sheet, each of which comprises fine fibrous cellulose. Furthermore, the present invention relates to a method for producing fine fibrous cellulose, comprising: (A) removing at least a part of substituents from fine fibrous cellulose with a fiber width of 1000 nm or less having the substituents, and (B) performing a uniform dispersion treatment on the resulting fine fibrous cellulose after completion of the (A).

The present invention relates to microfibrous cellulose capable of exhibiting an excellent dispersibility stability and an excellent coating suitability when added to paint.

To this end, the present invention provides fibrous cellulose having a fiber width of 1,000 nm or less and containing an ionic substituent. An amount of the ionic substituent in the fibrous cellulose is 0.10 mmol/g or more and 1.50 mmol/g or less. A polymerization degree of the fibrous cellulose is 150 or more and 515 or less. When the fibrous cellulose is dispersed in a dispersion solvent containing water and isopropanol to obtain a dispersion fluid having a 7:3 mass ratio of water and isopropanol and a viscosity of 2,500 mPa.Math.s at 23° C., and the dispersion fluid is stirred under predetermined stirring conditions, a viscosity change rate falls within ±50% as calculated by the following formula:

viscosity change rate (%)=(viscosity after stirring−viscosity before stirring)/viscosity before stirring×100