Abstract: The invention is directed to cross-linked cellulose fibers wherein cellulose pulp is fluffed, aerated, and exposed to a reaction mixture comprising formaldehyde, hydrochloric acid and formic acid as finely divided droplets or vapors. The thus treated fibers are cured by subjecting the fibers to a hot air stream at a temperature of from about 180.degree.-200.degree. C. for a duration of a few seconds, followed by separation of the fibers from the gaseous effluents. The procedure which lasts less than about one minute provides cellulose fibers cross-linked with formaldehyde wherein the predominant amount of cross-linking occurs at the surface of the fibers rather than at the core of the fibers. The fibers have improved characteristics including flexibility, touch and feel, rendering the fibers highly useful in paper products.

Abstract: Fibrous structures in sheet form having from 10% to 90% by weight of pulp of cellulosic fibers cross-linked with formaldehyde, the predominant cross-linking being at the surface area of said fibers and in an amount sufficient to impart flexibility and softness to said fibers while retaining high water absorptivity, and 90% to 10% by weight of an additional binding product with the amount of the additional binding product being selected to ensure sufficient strength and cohesion to the structure of the sheet. The inclusion of the cellulosic fibers wherein the predominant amount of cross-linking is at the surface area of the fibers imparts excellent water absorptiveness to the fibrous structure and, in addition, provides good flexibility and touch and feel properties to the product.

Abstract: The invention relates to a process for cross-linking cellulose with formaldehyde. The pulp is fluffed, aerated and exposed to a reaction mixture comprising formaldehyde, hydrochloric acid and formic acid as finely divided droplets or vapors. The wetted fibers are then cured in a hot air stream at 180.degree. C during a few seconds and separated from the gaseous effluents. The whole procedure lasts less than 1 minute.