A chemically modified cellulosic fibre or filament having a moisture content of at least 7% by weight obtained by a process comprising the steps of (i) obtaining cellulosic fibres or filament and chemically modifying the cellulose by substitution to increase its absorbency; (ii) washing the fibres after step (i) in a mixture comprising water and up to 99% by weight of water-miscible organic solvent; (iii) drying the fibres to a moisture content of at least 7% by weight.

A process for forming a fiber tow, involves a wet spinning procedure comprising the steps of: dissolving cellulose pulp N in an alkaline aqueous solvent to form a cellulose spin dope composition, spinning the cellulose spin dope composition in a coagulation having a p H of more than 7.0, preferably a pH of at least 10, to produce a fiber tow, and passing the produced fiber tow through a sequence of consecutive stretching and washing steps in which the formed fiber tow is washed with a washing liquid by a counter-current flow washing procedure.

A process for forming a fiber tow, involves a wet spinning procedure comprising the steps of: dissolving cellulose pulp N in an alkaline aqueous solvent to form a cellulose spin dope composition, spinning the cellulose spin dope composition in a coagulation having a p H of more than 7.0, preferably a pH of at least 10, to produce a fiber tow, and passing the produced fiber tow through a sequence of consecutive stretching and washing steps in which the formed fiber tow is washed with a washing liquid by a counter-current flow washing procedure.

The present invention relates to a process for the treatment of lyocell fibers, comprising the step of contacting the fiber with at least one treatment medium, at least one treatment medium containing an amount of a crosslinking agent, wherein the cross-linking agent is capable of crosslinking cellulose under alkaline conditions and has a solubility in water at 20° C. of 20 g/l or less, and further comprising the step of treating the fiber with the cross-linking agent under alkaline conditions, characterized in that the cross-linking agent is added to the fiber in the form of a suspension or in solid form. The present invention also relates to lyocell fibers obtainable by the process of the present invention.

The present invention relates to a process for the treatment of lyocell fibers, comprising the step of contacting the fiber with at least one treatment medium, at least one treatment medium containing an amount of a crosslinking agent, wherein the cross-linking agent is capable of crosslinking cellulose under alkaline conditions and has a solubility in water at 20° C. of 20 g/l or less, and further comprising the step of treating the fiber with the cross-linking agent under alkaline conditions, characterized in that the cross-linking agent is added to the fiber in the form of a suspension or in solid form. The present invention also relates to lyocell fibers obtainable by the process of the present invention.

Objects of the present invention are to provide a phosphoric acid-esterified fine cellulose fiber of which slurry shows superior transparency, and to provide a method for producing a phosphorylated fine cellulose fiber showing superior transparency with good efficiency and high yield. According to the present invention, there is provided a phosphoric acid-esterified fine cellulose fiber, of which 0.2 mass % aqueous dispersion shows a solution haze of 15% or lower.

Objects of the present invention are to provide a phosphoric acid-esterified fine cellulose fiber of which slurry shows superior transparency, and to provide a method for producing a phosphorylated fine cellulose fiber showing superior transparency with good efficiency and high yield. According to the present invention, there is provided a phosphoric acid-esterified fine cellulose fiber, of which 0.2 mass % aqueous dispersion shows a solution haze of 15% or lower.

An object of the present invention is to provide a salt water thickener that uniformly (favorably) disperses ultrafine cellulose fibers even in a liquid containing a salt (electrolyte). The salt water thickener comprises ultrafine cellulose fibers and a water-soluble polymer and can thereby uniformly disperse the ultrafine cellulose fibers even in a liquid containing a salt. The salt water thickener of the present invention is uniformly dispersed even in a liquid containing a salt and therefore exerts a high viscosity. The salt water thickener of the present invention can also be used as an additive for a fluid. The salt water thickener of the present invention can be used for purposes, for example, subterranean formation processing.

An object of the present invention is to provide a salt water thickener that uniformly (favorably) disperses ultrafine cellulose fibers even in a liquid containing a salt (electrolyte). The salt water thickener comprises ultrafine cellulose fibers and a water-soluble polymer and can thereby uniformly disperse the ultrafine cellulose fibers even in a liquid containing a salt. The salt water thickener of the present invention is uniformly dispersed even in a liquid containing a salt and therefore exerts a high viscosity. The salt water thickener of the present invention can also be used as an additive for a fluid. The salt water thickener of the present invention can be used for purposes, for example, subterranean formation processing.

Objects of the present invention are to provide a phosphoric acid-esterified fine cellulose fiber of which slurry shows superior transparency, and to provide a method for producing a phosphorylated fine cellulose fiber showing superior transparency with good efficiency and high yield. According to the present invention, there is provided a phosphoric acid-esterified fine cellulose fiber, of which 0.2 mass % aqueous dispersion shows a solution haze of 15% or lower.