[Object] The present invention provides a sulfonated fine cellulose fiber having excellent viscosity and the like, as well as a sulfonated fine cellulose fiber production method capable of efficiently producing the sulfonated fine cellulose fibers.

[Method for Achieving the Object] A fine cellulose fiber obtained by fibrillating a cellulose fiber wherein a part of the hydroxyl groups of the fine cellulose fiber is substituted with sulfo groups, and an introduction amount of sulfur attributable to the sulfo groups is higher than 0.42 mmol/g. The fine cellulose fiber comprises a plurality of unit fibers and has an average fiber width of 30 nm or less. A dispersion liquid in which the fine cellulose fiber is dispersed in a water-soluble solvent at a solid concentration of 0.5% by mass has a viscosity of 5,000 mPa.Math.s or more at 25° C. This makes it possible to obtain the desired viscosity when the fine cellulose fibers are dispersed in a dispersion liquid.

The present invention relates to a method for manufacturing an intermediate product that can be stored and transported and efficiently converted into microfibrillated cellulose with limited energy input at the time of conversion. More specifically, the invention involves the use of dewatered carboxymethylcellulose or carboxylated cellulose fiber having a low degree of substitution and a high amount of additives.

Paper products can comprise a first plurality of fibers that are hardwood fibers and a second plurality of fibers that include softwood fibers and surface enhanced pulp fibers (SEPF). The paper product can include one or more first fiber layers that comprise the first fibers, at least one of the first fiber layer(s) defining one of opposing upper and lower surfaces of the paper product, and one or more second fiber layers that comprise the second fibers. When a tissue, by weight, between 50% and 80% of the tissue's fibers can be the first fibers and at least 20% of the tissue's fibers can be the second fibers. The tissue's basis weight can be less than or equal to 21 gsm per ply.

A system and method of producing MFC (micro fibrillated cellulose), which system comprises at least one refiner. The refiner comprises a mechanism for refining the stock in at least two refining stages, advantageously at least two refiners for refining the stock in at least two refining stages, and that the refiners comprise a number of refining bars. The refining bars have width of 0.5-2.0 mm, height less than 7 mm and groove width of 0.5-3 mm. The method comprises at least two refining stages, in which the pulp stock is refined in at least one refining stage in consistency of 3-5%, and the method comprises at least one screening stage in at least one screen in consistency of 0.5-5%.

The present invention refers to the separation of cellulose pulp into distinct fractions with different draining and morphological characteristics, as well as the use of part of these fractions for the production of nanocellulose. The process in reference combines the unitary operations of fiber separation, thickening to a certain consistency, draining and drying of the cellulosic pulp with the high drainage ability and production of nanocellulose from high primary fines content pulp. The process may consider any cellulosic pulp fiber derived from short or long fiber woods such as Eucalyptus, Corymbia, Birch, Aspen, Pinus, recycled fibers, etc., their residues such as bark, sawdust, etc.

An improved market pulp and process for making the same by adding a composite material are described. The composite material includes cellulose nanocrystals, cellulose nanofibers, or another high aspect ratio, high surface area cellulose material (or a starch, or both) and a crosslinking compound that crosslinks a portion of the surface hydroxyl groups to form a 3-D matrix. Adding the composite material to market pulp has been shown to improve the strength of twice-dried paper products, made from such an enhanced market pulp. By crosslinking a portion of the surface hydroxyl groups in the market pulp to form a 3-D matrix, a first drying step may be accomplished without loss of benefits afforded when the market pulp is later re-pulped to make a paper product.

There is provided a method for separation of fibers in for instance recycled textile, starting with a mixture comprising cellulose fibers and non-cellulose fibers and then reducing the cellulose chain length of the cellulose fibers so that the limiting viscosity number determined according to ISO 5351 is in the interval 200-900 ml/g, mechanically breaking agglomerates of fibers into smaller pieces, adjusting the concentration of fibers to 0.1-4 wt %, and subjecting the mixture to flotation to remove the non-cellulose fibers. Non-cellulosic fibers such as synthetic fibers can be removed very specifically without or essentially without removing cellulose fibers in the mixture. This gives a very high degree of removal and simultaneously the yield is kept high because no or only few cellulose fibers are removed.

The present disclosure relates to a resin composition that exhibits satisfactory flow properties and mechanical properties, to a cellulose formulation that is used to produce the resin composition, and to resin pellets and a molded resin formed by the resin composition.

The purpose of the present invention is to provide a method which is for producing pulp fibers for cellulose nanofiberization from pulp fibers of used sanitary products, and which can produce pulp fibers for cellulose nanofiberization that have low lignin content and a low distribution thereof and that have excellent cellulose nanofiberization properties. This method is described below. The method is characterized by involving: a step for supplying, from a mixed solution supply port (32) to a treatment tank (31), a mixed solution (51) which contains superabsorbent polymers and pulp fibers derived from used sanitary products; a step for supplying an ozone-containing gas (53) from an ozone-containing gas supply port (43) to a treatment solution (52) inside of the treatment tank (31); a step in which, by raising the ozone-containing gas (53) while lowering the superabsorbent polymers and pulp fibers in the treatment tank (31), the ozone-containing gas (53) is brought into contact with the superabsorbent polymers and the pulp fibers, and pulp fibers for cellulose nanofiberization are formed from the pulp fibers; and a step for discharging the treatment solution (52) from a treatment solution discharge port (33), wherein the pulp fibers for cellulose nanofiberization have a lignin content of less than or equal to 0.1 mass %.

A fibrous cellulose has an average fiber width of 0.1 .Math.m or more and has a part or all of hydroxyl groups replaced with carbamate groups, in which a replacement ratio with the carbamate group is 1.0 mmol/g or more, and a fine ratio is 30% or more. A fibrous cellulose composite resin contains a fibrous cellulose and a resin, and the above fibrous cellulose In manufacturing fibrous cellulose, a cellulose raw material and urea or the like are subjected to a heat treatment to replace a part or all of hydroxyl groups of the cellulose raw material with carbamate groups, defibration is performed within a range in which an average fiber width is 0.1 .Math.m or more, the heat treatment is performed such that a replacement ratio with the carbamate group is 1.0 mmol/g or more, and the defibration is performed until a fine ratio reaches 30% or more.