MXPA06004138A

MXPA06004138A - Materials useful in making cellulosic acquisition fibers in sheet form

Info

Publication number: MXPA06004138A
Application number: MXPA/A/2006/004138A
Authority: MX
Inventors: J Chmielewski Harry; A Hamed Othman
Original assignee: J Chmielewski Harry; A Hamed Othman
Priority date: 2003-10-14
Filing date: 2006-04-11
Publication date: 2007-04-10

Abstract

Embodiments of the invention relate to a modifying agent for making cellulosic based acquisition fibers in the sheet form, the modifying agent being the reaction product of a polycarboxylic acid compound and a polyfunctional epoxy compound. A method of producing the cellulosic based acquisition fiber in the sheet from using the modifying agent includes treating the cellulosic fibers in the sheet form with the modifying agent, and drying and curing the treated sheet to promote the formation of intra-fiber bonding. The resultant cellulosic based acquisition fiber may be utilized in an acquisition layer and / or an absorbent core of an absorbent article.

Description

Published: For two-letter codes and other abbreviations, refer to the "Guid- - without international search report and to be republished anee Notes on Codes and Abbreviations" appearing at the begin- ning receipt ofthat report no ofeach regular issue of the PCT Gazette.

USEFUL MATERIALS IN THE ELABORATION OF CELLULOSIC FIBERS IN LAMINAR FORM FIELD OF THE INVENTION The embodiments of the present invention concern a modifying agent for making uptake fibers with a cellulosic base in laminar form and a process for making the modifying agent. The modifying agent can be made by reacting a polyfunctional epoxy compound and a polycarboxylic acid compound. The embodiments of the present invention also concern methods of making the cellulose-based uptake fiber in the sheet form using the modifying agent of the invention. The hydrophobic cellulosic fibers of the present invention can be characterized as having an improved centrifugation retention capacity, rate of capture, elasticity, bulk density and absorbency under load. The fibers are especially suitable for use in absorbent articles intended for the handling of body fluids.

BACKGROUND OF THE INVENTION Absorbent articles intended for personal care, such as adult incontinent pads, feminine care products, and children's diapers typically comprise at least one topsheet, a backsheet, an absorbent core disposed between the sheet upper and the backsheet and an optional pick-up layer disposed between the topsheet and the absorbent core. The acquisition layer consists of, for example, pick-up fibers, is usually incorporated into the absorbent articles to provide better liquid distribution, increase the rate of liquid absorption, reduced gel blocker, and improved surface dryness. A wide variety of pickup fibers are known in the art. These include synthetic fibers, a composite of cellulosic fibers and synthetic fibers, and crosslinked cellulosic fibers. Crosslinked cellulosic fiber is preferred because it is abundant, is biodegradable, and is relatively inexpensive. For many years, cross-linked cellulose fibers and the processes to produce them have been described in the literature (see, for example, GC Treasure, Cross-Linking of Cellulosic, in Handbook of Fiber Science and Technology, Vol. II, M. Lewin and SB Seal eds, pp. 1-46, Marcel Dekker, New York (1983)). The crosslinked cellulosic fibers are typically prepared by reacting cellulose with polyfunctional agents that are capable of reacting with hydroxyl groups of the anhydroglucose repeating units of the cellulose either in the same chain, or in neighboring chains simultaneously. Typically, the cellulosic fibers are crosslinked in the spongy form. The processes for making the crosslinked fiber in the spongy form comprises immersing sponged or unfoamed fibers in an aqueous solution of crosslinking agent, and softening. The fiber thus treated is usually crosslinked by heating at elevated temperature in the foamed state, as described in U.S. Pat. No. 3,241,553, or in the collapsed state after defibration in U.S. Pat. No. 3,224,926, and European Patent No. 0,427,361 Bl, the disclosures of which are incorporated herein by reference in their entirety. It is believed that fiber crosslinking improves the physical and chemical properties of fibers in many ways, such as improving elasticity (in the dry and wet state), increasing absorbency, reducing shrinkage, and improving resistance to shrinkage. However, crosslinked cellulosic fibers have not been widely adopted in absorbent products, apparently because of the difficulty of successfully crosslinking the cellulosic fibers in laminar form. More specifically, it was found that the crosslinked fiber in the laminar form tends to make it difficult to defibe without causing substantial problems with the fibers. These problems include severe breakage of the fiber and increase the increasing amounts of knots and points (lumps of hard fiber). These disadvantages make the crosslinked product completely unsuitable for many applications. It is believed that these problems are attributable to two factors: (a) fibers in laminar form in a dry state are in intimate contact with each other; and (b) the presence of residual pulp and bleaches such as lignin and heel cellulose. The mechanical entanglements and the hydrogen bond of the laminar fibers carry fibers in close contact. As a result, when the fibers are treated with a crosslinking agent and heated for curing, the fibers tend to form inter-fiber (between two adjacent fibers) lattices preferably to intra-fiber lattice (chain to chain in a single fiber). Residual pulp and bleach such as lignin and hemicellulose combine with the crosslinking agents under the heated conditions of the crosslinking reaction to form thermoset adhesives. Consequently, these residuals serve to adhesively bond adjacent fibers so that it is very difficult to separate them under any condition without considerable breakage of the fiber. Because the crosslinked fibers tend to be brittle, the fibers themselves will often break, leaving the areas linked between adjacent fibers intact. Many solutions have been proposed to overcome the problems of the crosslinked fiber in the laminar form. An alleged solution to this problem is to minimize the contact between fibers in the dry state. For example, Graef et al., In U.S. Pat. 5,399,240, the disclosure of which is incorporated herein by reference, discloses a method of treating fibers in the sheet form with a crosslinking agent and an unlinker. The fiber, while in laminar form, is then cured at elevated temperatures. The decoupler tends to interfere with the hydrogen bond between fibers and thus minimizes contact between fibers. As a result, fibers with a relatively low content of knots and points are produced. Unfortunately, the hydrophobic long alkane chain tends to have undesirable hydrophobic effects on the fibers, for example, resulting in decreasing absorbency and wettability, rendering it unsuitable for applications such as absorbent articles, where a high absorbency rate and rapid uptake is required. In the U.S. patent 3,434,918, Bernardin et al. Describe a method of treating fibers in laminar form with a crosslinking agent and a catalyst. The treated sheet is then aged with moisture to render the crosslinking agent insoluble. The fibers aged with moisture are re-dispersed before curing, mixed with treated, laminated and then cured fibers. The mixture of crosslinked fibers and untreated fibers is potentially useful for making products such as filter media, fabrics, and wipes where high bulk density and good water absorbency are desired without excessive rigidity in the product. Unfortunately, the presence of untreated fibers makes the fiber produced inadequate as a pick-up layer in hygiene products such as diapers. Other documents describing methods of treating fibers in laminar form include, for example, U.S. Pat. Nos. 4,204,054; 3,844,880; and 3,700,549 (whose descriptions are incorporated herein by reference in their entirety). However, the procedures described above complicate the process of crosslinking the fiber in a laminar form, and make the process slow and expensive. As a result, these processes result in crosslinked fibers with a substantial decrease in fiber results, and a substantial increase in cost. In previous works (US Patent Application Serial No. 10 / 166,254, entitled: "Chemically Cross-linked Cellular Fiber and Method of Making the Same", filed June 11, 2002, and Serial No. 09 / 832,634 , entitled "Cross-linked Pulp and Methods of Making Same", presented on April 10, 2001, and the US Request entitled "Method for Making Chemically Cross-Linked Cellulosic Fiber In The Sheet Form", filed on March 14, 2003 , Proxy Act number 60892.000005) showed that mercerized fibers and a mixture of mercerized and conventional fibers can be successfully crosslinked in laminar form. The cross-linked fiber produced showed similar or better characteristic results than individualized conventional cross-linked cellulose fibers. Also the fiber produced showed less discoloration and reduced amounts of knots and points compared to the conventional individualized crosslinked fiber. Mercerization of the fiber, which is a fiber treatment with an aqueous solution of sodium hydroxide (caustic), is one of the previously known modifications of the fiber. They were invented 150 years ago by John Mercer (see British Patent 1369.1850). The process is generally used in the textile industry to improve the tensile strength of cotton fabrics, colorability, and luster (see, for example, R. Freytag, J.-J-Donze, Chemical Processing of Fibers and Fabrics, Fundamental and Applications , Part A, in Handbook of Fiber Science and Technology Vol. 1 M. Lewis and SB Seal eds, pp. 1-46, Mercell Decker, New York (1983)). The present disclosure of certain advantages and disadvantages of known cellulosic capture fibers, and methods of their preparation, is not intended to limit the scope of the present invention. Indeed, the present invention may include some or all of the methods and chemical reagents described above. without suffering from the same disadvantages.

SUMMARY OF THE INVENTION In view of the difficulties presented by crosslinked cellulosic fibers in the laminar form, there is a need for a relatively low cost, simple modifier agent suitable for making capture fibers in the laminar form without sacrificing the wettability of the fibers, whereby the resulting sheet can be defibrated into individual fibers without serious breaks in the fiber. The resulting fibrous sheet also preferably has low contents of knots and dots. There is a need for a process for making pick-up fibers in the sheet form which provides time and cost savings to both the pick-up fiber manufacturers and the absorbent article manufacturer. The present invention wishes to fill these needs and provide additional related advantages. Accordingly, it is an aspect of one embodiment of the invention to provide a modifying agent with hydrophobic characteristics to be used in preparing cellulose-based capture fibers in the sheet form. It is also an aspect of one embodiment of the present invention to provide a method of making cellulosic based capture fibers in the sheet form using the modifying agent of the present invention. It is yet another aspect of one embodiment of the present invention to provide cellulosic-based capture fibers in a laminar form having improved retention, absorptive capacity, absorbency under load, and bulk density on a dry basis. It is yet another aspect of one embodiment of the present invention to provide a cellulosic based capture fiber in the laminar form with decreasing knots and points., and fine content. In yet another aspect of one embodiment of the present invention, the pick-up fibers can be used as a pick-up layer or in the absorbent core of an absorbent article. In accordance with these and other aspects of embodiments of the invention, there is provided a modifying agent useful in the preparation of cellulose-based uptake fibers in the sheet form which is the reaction product of a polycarboxylic acid compound and a polyfunctional epoxy compound. , preferably in a molar ratio of carboxylic acid to polyfunctional epoxy of from about 2: 1 to about 3: 1. The carboxylic acid preferably comprises another functional group in addition to the carboxyl group, such as a hydroxyl group or an amino. The polyfunctional epoxy preferably comprises a substituent group, such as hydrogen or an alkyl group. The modifying agent may be provided in an aqueous solution, and may additionally comprise other materials, such as a catalyst or a surfactant. In accordance with a further aspect of an embodiment of the present invention, there is provided a method of making cellulosic-based capture fibers that includes applying a solution containing a modifying agent of the present invention to cellulosic fibers to impregnate the fibers, then drying and curing the impregnated cellulose fibers. Another suitable method additionally provides the impregnation of cellulosic fibers in a foamed form with the solution containing a modifying agent, drying the fibers at a temperature below the curing temperature, defibrating the fibers, and then curing them. In accordance with another aspect of an embodiment of the invention, cellulosic based picking fibers produced by means of the method of the present invention are provided, wherein the picking fibers have a centrifugal holding capacity of less than about 0.6 grams of 0.9% by weight of saline per gram of fiber (hereinafter "g / g"). Cellulosic based capture fibers also preferably have desirable properties such as an absorbent capacity of at least 8.0 g / g, a density Apparent on dry basis of at least about 8.0 cm3 / g fiber, absorbency under load greater than about 7.0 g / g, less than about 26% knots, and less than about 9% fines.These properties can be achieved individually, or in various combinations with each other.

In accordance with another aspect of one embodiment of the invention, an absorbent article is provided that utilizes cellulosic based pickup fibers of the present invention in a pickup layer or absorbent structure. These and other objects, aspects and advantages of the present invention will appear more complete from the following detailed description of the preferred embodiments of the invention, and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The drawings show electron microscopic photographs of cellulosic based capture fibers of the present invention. The photographs were obtained using the Scanning Electron Microscope S360 Leka Cambridge Ltd., Cambridge, England. Figure 1 is a 100X magnification photograph of untreated Raffloc®-J-LD (bog pine Kraft pulp commercially available from Rayonier Performance Fibers Division, Jesup, GA and Fernandina Beach, FL). Figure 2 is a 200X amplification photograph of capture fiber obtained from Pampers Diaper Products by The Procter & Gamble Company ("P &G"). Figures 3A, 3B and 3C are amplification photographs of 100X, 400X, and 1000X, respectively, of hydrophobic cellulosic fibers obtained as shown in Example 5 from the reaction of Rayfloe®-J-LD fibers in laminar form with the modifying agent of the present invention. Figures 4A, 4B, and 4C are amplification photographs of 100X, 500X, and 1000X, respectively, of cellulosic based capture fibers obtained as shown in Example 11 from the Rayfloe®-J-LD fiber reaction. in a sponge form with the modifying agent of the present invention. Figure 5 is a cross-sectional photograph of 1000X amplification of cellulose-based uptake fibers obtained as shown in Example 5 from the reaction of Rayfloc®-J-LD fibers in laminar form with the modifying agent of the present invention. Figure 6 shows the chromatogram by gas chromatography of a solution of 1,4-cyclohexanedimethanol diglycidyl ether in hexane. Figure 7 shows the chromatogram by gas chromatography of the extracts of the modifying agent prepared according to the present invention as shown in Example 1. Figure 8 shows the chromatogram by gas chromatography of the extracts of the capture fibers with cellulosic base made in accordance with the present invention as shown in Example 5.

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to cellulose-based uptake fibers and to a method of making the fibers. The method comprises treating the cellulose fibers in the form of sheets, rolls, foamed with a solution containing a modifying agent obtained by reaction of a polycarboxylic acid compound and a polyfunctional polyepoxy compound in aqueous medium.

As used herein, the terms "absorbent garment", "absorbent article" or simply "article" or "pledge", refer to mechanisms that absorb and contain bodily fluids and other body exudates. More specifically, these terms refer to garments that are placed against or in proximity to the body of a wearer to absorb and contain the various exudates discharged from the body. A non-exhaustive list of examples of absorbent garments includes diapers, diaper covers, disposable diapers, training pants, feminine hygiene products, and adult incontinence products. Such garments may be intended to be discarded or partially discarded after a single use ("disposable" garments). Said garments may essentially comprise a unique inseparable structure ("unitary" garment), or may comprise replaceable inserts or other interchangeable parts. Modes of the present invention can be used with all kinds of absorbent garments mentioned above, without limitation, either disposable or otherwise. Some of the embodiments described herein provide, as an exemplary structure, a diaper for a child, however these were not intended to limit the claimed invention. The invention will be understood to encompass, without limitation, all classes and types of absorbent garments, including those described herein. The term "component" may refer, but not be limited to, designated selected regions, such as edges, corners, sides or the like; structural elements, such as elastic strips, absorbent pads, elastic layers or panels, or the like.

In the course of this description, the term "arranged above", "arranged above", arranged below ", "available below", "available on", "arranged in", "arranged in" and variations thereof is intended to mean that an element may be integral with another element, or that an element may be a separate structure linked to or placed with or placed near another element. Accordingly, a component that is "arranged on" an absorbent garment element may be formed or applied directly or indirectly on a surface of the element, formed or applied between layers of a multilayer element, formed or applied to a substrate that it is placed with or near the element, formed or applied in a layer of the element or other substrate, or other variations of combinations thereof. In the course of this description, the terms "top sheet" and "back sheet" denote the relationship of these materials or layers with respect to the absorbent core. It is understood that additional layers may be present between the absorbent core and the topsheet and the backsheet, and that additional layers and other materials may be present on the side opposite the absorbent core of either the topsheet or the backsheet . In the course of this description, the expression "upper layer", "lower layer", "above" and "below", which refer to the various components included in the absorbent material, are used to describe the spatial relationship between the respective components. The top layer or component "on top of" another component does not always need to remain vertically above the core or component, and the bottom layer or component "below" the other component does not always need to remain vertically below the core or component. Other configurations are contemplated in the context of the present invention. In the course of this description, the term "impregnated" as it concerns a modifying agent impregnated in a fiber, denotes an intimate mixture of modifying agents and cellulosic fibers, with which the modifying agent can be adhered to the fibers, adsorbed on the surface of the fibers, or linked via chemical, hydrogen or other bonds (eg, van der Walls forces) to the fibers. Impregnated, in the context of the present invention does not necessarily mean that the modifying agent is physically disposed below the surface of the fibers. The present invention relates to cellulose-based capture fibers which are useful in absorbent articles, and in particular, which are useful in the formation of absorption layers or absorbent cores in the absorbent article. The particular construction of the absorbent article is not critical to the present invention, and any absorbent article can benefit from this invention. Suitable absorbent garments are described, for example, in U.S. Pat. Nos. 5,281,207 and 6,068,620, the descriptions of which are incorporated in their entirety, including their respective drawings, hereby referred to by reference, Those skilled in the art will be able to utilize the pickup fibers of the present invention in absorbent garments, cores, collection layers, and the like, using the guidelines provided herein.

In accordance with embodiments of the present invention, modifying agents that are useful in making cellulosic uptake fibers in the sheet form are made by reacting approximately stoichiometric amounts of a polycarboxylic acid compound and a polyfunctional epoxy compound. Examples of suitable polycarboxylic acids are those having at least two carboxyl groups such as, for example, 1,2,3,4-butanetetracarboxylic acid, 1,2,3-propanetricarboxylic acid, oxydisuccinic acid, citric acid, itaconic acid, acid maleic, tartaric acid, glutaric acid, and iminodiacetic acid. Other suitable polycarboxylic acids include polymeric polycarboxylic acids such as, for example, those especially prepared from monomers such as acrylic acid, vinyl acetate, maleic acid, maleic anhydride, ethyl carboxy acrylate, itaconic acid, fumaric acid, methacrylic acid, acid crotonic, acrylic acid ester, methacrylic acid ester, acrylic amide, and methacrylic amide, butadiene, styrene, or any combination thereof. Especially polycarboxylic acids are polycarboxylic alkane acids having one or more hydroxyl groups such as citric acid and tartaric acid. A polyfunctional epoxy that can be used in embodiments of the present invention preferably have the following General Formula: Wherein R is an alkyl with 3 or more carbon atoms; and n is an integer from 1 to 4. The alkyl group includes cyclic and acyclic, branched and unbranched, substituted and unsubstituted, saturated, and unsaturated compounds. Typical examples of said polyfunctional epoxides include but are not limited to: diglycidyl 1,4-cyclohexanedimethanol, diglycidyl 1,2-cyclohexanedicarboxylate, diglycidyl 1,2,3,4-tetrahydrophthalate, triglycidyl ether glycerol propoxylate, diglycidyl ether of polypropylene glycol, or any combination thereof. Especially, they prefer polyfunctional epoxies which are: diglycidyl ether of 1,4-cyclohexadimethanol and neopentyl diglycidyl ether. The modifying agent can be prepared by any suitable and convenient method. The functional polycarboxylic and epoxy acids are generally reacted in a molar ratio of polycarboxylic acid to polyfunctional epoxy of from about 2.0: 1 to about 3.0: 1. The reaction can be carried out in the temperature range until reflux. Preferably, the reaction is carried out at room temperature for about 6 hours, more preferably for about 10 hours and more preferably for about 16 hours. The product of the reaction is soluble in water, and can be diluted in water at any desirable concentration. In the case in which diglycidyl ether of 1,4-cyclohexanedimethanol is used as an epoxy functional the diluted solution produced is slightly cloudy, and the addition of surfactants clarifies the solution. Suitable surfactants include nonionic, anionic, or cationic surfactants, or mixtures and combinations of surfactants that are compatible with each other. Preferably the surfactant is selected from: Triton X-100 (Rohm and Haas), Triton X405 (Rohm &Haas), sodium lauryl sulfate, lauryl bromoethyl ammonium chloride, ethoxylated nonylphenols, and polyoxyethylene alkyl ethers. Preferably, the surfactant is added in an amount of less than 0.1% by weight based on the total weight of the solution. Optionally, a catalyst can be added to the solution to accelerate the reaction between the polycarboxylic acid and the polyfunctional epoxy. Any catalyst known in the art to accelerate the formation of an ether bond or bond between a hydroxyl group and an epoxy group is suitable for use in embodiments of the present invention. Preferably, the catalyst is a Lewis acid selected from aluminum sulfate, magnesium sulfate, and any Lewis acid containing at least one metal and a halogen, including for example FeCl3, A1C13, and MgCl2. A representative structure of a modifying agent of an embodiment of the invention prepared by reaction of citric acid with diglycidyl ether of 1,4-cyclohexanedimethanol is shown in Reaction Scheme 1.

Other possible reaction products formed in this reaction include but are not limited to those shown in "Reaction Scheme 2. Fortunately, all byproducts may also react with the cellulosic fibers." Reaction Scheme 1 Reaction Scheme 2 Another aspect of the present invention provides a method for making cellulose-based uptake fibers using the modifying agents described above. The process preferably comprises treating cellulose fibers in laminar, roll or foamed form with an aqueous solution containing the modifying agent, followed by drying and curing at a sufficient temperature and for a period of time sufficient to accelerate the formation of covalent bonds between hydroxyl groups of cellulose fibers and functional groups of the modifying agent. Using the guides provided herein, those skilled in the art are able to determine suitable drying and curing temperatures and times, depending on the reactants and the apparent bond density desired in the fibers. Any of the cellulosic fibers can be used in the invention, provided they provide the physical characteristics of the fibers described above. Suitable cellulosic fibers for use in the formation of cellulose-based uptake fibers of the present invention include those derived primarily from wood pulp. The right wood pulp can be obtained from any of the conventional chemical processes, such as the sulfite process or the Kraft. Preferred fibers are those obtained from various softwood pulps such as Swamp Pine, White Pine, Caribbean Pine, Pacific Tsuga, several firs (for example, Sitka Spruce), Douglas Fir or mixtures and combinations thereof. Fibers obtained from sources of hardwood pulp, such as gum, maple, cedar, eucalyptus, poplar, beech wood, and poplar wood, or mixtures and combinations thereof, may also be used in the invention. Other cellulosic fibers derived from cotton, cotton linters, bagasse, canine hair wool, flax, and grass may also be used in the present invention. The fibers may consist of a mixture of two or more of the aforementioned cellulose pulp products. In particular, the fibers for use in the formation of cellulose-based uptake fibers of the present invention are those derived from wood pulp prepared by means of the Kraft pulp or sulphite formation processes.

The cellulosic fibers may be derived from fibers in any of a variety of ways. For example, one aspect of the present invention contemplates using cellulosic fibers in laminar, roll, or foamed form. In another aspect of the invention, the fibers may be in a support plate of nonwoven material. The fibers in the form of a support plate are not necessarily wound in a roll form, and typically have a lower bulk density than fibers in the sheet form. In yet another aspect of one embodiment of the invention, the fibers may be used in the humerus or dry state. It is preferred that the cellulosic fibers be used in the dry state. The cellulosic fibers that are treated in accordance with the modifying agent with various embodiments of the present invention so long as the sheet form can be any of the fibers of wood pulp or fibers of any other source previously described. In one embodiment of the invention, fibers in the sheet form suitable for use in the present invention include caustically treated fibers. In addition to the previously discussed advantages, the treatment of fibers with caustics adds several different advantages to the fibers. Among these are: (1) fibers treated with caustics have a high content of α-cellulose, since the caustic removes residuals such as lignin and hemicellulose remaining in the fibers from the processes of pulp formation and bleaching .; (2) caustic-treated fibers have a rounded circular shape (preferably to tape-like, flat shape of conventional fibers) which reduces contact and weakens the hydrogen-bond between fibers in the sheet form; and (3) the caustic treatment converts the cellulose chain either from its native structure form, cellulose I, to a more thermodynamically stable and less crystalline form, cellulose II. The cellulose chains in cellulose II were found to have an anti-parallel orientation preferably in a parallel orientation as in cellulose I (see, for example, RH Atalla, Comprehensive Natural Products Chemistry, Carbohydrates and Their Derivatives Including Tannins, Cellulose, and Related Lignins Vol. III, D. Barton and K. Nakanishi eds. P. 529-598, Elsevier Science, Ltd., Oxford, UK (1999)). Without adopting any theory, the aforementioned properties of caustic treated fibers are believed to be the reasons behind the amounts of fines, knots and reduced spots that the inventors have found to exist in the caustic treated fibers according to the present invention. .

A description of the caustic extraction process can be found in Cellulose and Cellulose Derivatives, Vol. V, Part 1, Spurlin, and Grafllin, eds., Interscience Publisher (1954). In summary, the cold caustic treatment is carried out at a temperature of less than about 65 ° C, but preferably at a temperature of less than 50 ° C, and more preferably at temperatures between about 10 ° C to 40 ° C. A preferred alkali metal salt solution is a sodium hydroxide solution either freshly prepared as a by-product solution of the paper or pulp shredding operation, for example, hemicáustico white liquor, oxidized white liquor and the like. Other alkali metals such as ammonium hydroxide and potassium hydroxide and the like can be employed. However, from a cost point of view, the preferred alkali metal salt is sodium hydroxide. The concentration of alkali metal salts in solution is typically in the range of from about 2 to about 25 weight percent of the solution, preferably from about 3 to about 18 weight percent. Commercially available caustically extractive pulps suitable for use in embodiments of the present invention include. For example, Prosanier-J-HP, available from Rayonier Performance Fibers Division (Jesup, GA), and Buckeye's HPZ products, available from Buckeye Technologies (Perry, FL). In one eiment, the modifying agent is applied to the cellulose fibers in an aqueous solution. Preferably, the aqueous solution has a pH of from about 1 to about 5, more preferably from about 2 to about 3.5. Preferably, the modifying agent, after being prepared, is diluted with water to a sufficient concentration to provide from 0.5 to 10.0 weight percent of modifying agent on the fiber, more preferably from about 2 to 7 weight percent, and more preferably from about 3 to 6 percent by weight. By way of example, 7% by weight of modifying agent means 7 grams of modifying agent per 100 grams of dry fiber in the oven. Optionally, the method includes applying a catalyst to accelerate the reaction between cellulose hydroxyl groups and carboxyl groups of the modifying agent of the present invention. Any catalyst known in the art can be used to accelerate the formation of an ester bond between the hydroxyl group and the acid group. Catalysts suitable for use in the present invention include alkali metal phosphorus-containing salts containing acids such as alkali metal hypophosphites, alkali metal phosphites, alkali metal polyphosphonates, alkali metal phosphates, and alkali metal sulfonates. A particularly preferred catalyst is sodium hypophosphite. The catalyst can be applied to the fibers as a mixture with the modifying agent, before the addition of the modifying agent, or after the addition of modifying agent to cellulosic fibers. A suitable ratio of catalyst to modifying agent is, for example, from about 1: 2 to about 1:10, and preferably from about 1: 4 to about 1: 8. Optionally, in addition to the modifying agent, other finishing agents such as softening and wetting agents can be used. Examples of softening agents include fatty alcohols, fatty acid amides, polyglycol ethers, fatty alcohol sulfonates, and N-stearyl-urea compounds. Examples of wetting agents include fatty amines, salts of alkylnaphthalenesulfonic acids, alkali metal salts of dioctyl sulfosuccinate, and the like.

Any method of applying the modifying agent to the fibers can be used. Acceptable methods include, for example, spraying, dipping, impregnation, and the like. Preferably, the fibers are impregnated with an aqueous solution containing the modifying agent. The impregnation typically creates a uniform distribution of modifying agent on the sheet and provides better penetration of modifying agent into the inner part of the fibers. In one embodiment of the invention, a sheet of caustically treated fibers or conventional fibers in the roll form is conducted through a treatment zone where the modifying agent is applied to both surfaces by means of conventional methods such as spraying, with rollers, coating with blades or any other way of impregnation. A preferred method of applying the aqueous solution containing the modifying agent to fibers in the roll form is by pudelage press, calibration press, or knife coater. In one embodiment of the present invention, the fibers in laminar or roll form after being treated with a solution containing the modifying agent are then preferably transported by means of a driving device such as a band or a series of conductive rolls through a two-zone oven for drying and curing. The fibers in the form of a sponge, roll or sheet after treatment with the modifying agent are preferably dried and cured in a two-stage process, and more preferably dried and cured in a one-stage process. Said drying and curing removes the water from the fibers, thus inducing the formation of an ester bond between the hydroxyl groups of the cellulosic fibers and the modifying agent. Any temperature and curing time can be used as long as they produce the desired effects described herein. Using the present description, persons having experience in the art can determine suitable curing temperatures and times, depending on the type of fibers and the type of fiber treatment. Curing is typically carried out in a forced draft furnace preferably from about 130 ° C to about 225 ° C (about 265 ° F to about 435 ° F), and more preferably from about 160 ° C to about 220 ° C. (about 320 ° F to about 430 ° F), and more preferably from about 180 ° C to about 215 ° C (about 350 ° F to about 420 ° F), Curing preferably is carried out for a sufficient period of time to allow the complete drying of the fiber and efficient bond between cellulosic fibers and the modifying agent. Preferably, the fibers are cured from about 5 minutes to about 25 minutes, more preferably from about 7 minutes to about 20 minutes, and more preferably from about 10 minutes to about 15 minutes.

In the case where the modifications are carried out on fibers in the form of a sponge, preferably the fibers are treated initially with the modifying agent while in the laminar form, dried at a temperature lower than the curing temperature, defibrated passing them to through a hammer mill or the like, and then heated to elevated temperatures to promote the formation of the bond between the fibers and the modifying agent. In an alternate embodiment of the present invention, the cellulosic fibers in the sponge form are initially treated with the modifying agent, dried at a lower curing temperature, defibrated, and then cured at an elevated temperature.

When the cellulosic fibers to be treated are in roll or sheet form, it is preferred that after applying the modifying agent, the fibers are dried and then cured, and more preferably dried and cured in a process. In one aspect of an embodiment of the present invention, the fibers in laminar or roll form after having been treated with a solution containing the modifying agent are transported by means of a driving device, such as a band or series of conductive rolls, through a two zone oven for drying and curing, preferably through a one-stage process in an oven of a zone for drying and curing. In another aspect of an embodiment of the present invention, the fibers in sheet form, after being treated with a solution containing the modifying agent, are preferably transported by means of a conveyor device, such as a belt or a series of conveyor rollers. , through a kiln for drying, and then to a hammer mill for defibering. The pulping of the shredding produced by the hammer mill is then preferably transported through a curing oven. In another aspect of an embodiment of the present invention, the defibrated pulp produced by the hammer mill is aerated on a nonwoven support plate, then preferably it is transported through a curing oven. Although not intended to be limited by any theory of operation, the reaction scheme shown below represents one of the possible reactions of fibers with the modifying agent of the present invention. The reaction scheme is provided for purposes of non-limiting illustration, the reaction between the cellulosic fibers and the modifying agent of the present invention. As shown in Reaction Scheme 3, the cellulose reaction with the modifying agent of the present invention results in the formation of ester linkages. The reaction mechanism is expected to be similar to that between cellulose and conventional cross-linking agents such as, for example, alkane polycarboxylic acids. The mechanism of crosslinking cellulose with polycarboxylic acid has been described by Zhou et al., Journal of Applied Polymer Science, Vol. 58, 1523-1524 (1995) and by Lees, MJ. The Journal of Textile Institute Vol. 90 (3) , 42-49 (1999). The mechanism of polycarboxylic acid to cross-link cellulose has been shown to take place via four stages: (1) formation of a 5-or 6-anhydride ring from polycarboxylic acid; (2) reaction of the anhydride with a hydroxyl group of cellulose to form an ester linkage and link the polycarboxylic acid to the cellulose; (3) formation of an anhydride ring of 5- or 6- elements from carboxyl groups suspended from polycarboxylic acids; and (4) reaction of the anhydride with free cellulose hydroxyl groups to form ester crosslinks. Reaction Scheme 3 The stability of the bonds formed in the cellulose-based uptake fibers made in accordance with the present invention was examined by means of an aging process described later in Example 15. The cellulosic-based uptake fibers of the invention showed little or no no change in bulk density and results after heating for approximately 20 hours at 90 ° C. In addition, fibers stored in an environment with 50% humidity at room temperature for more than 3 months exhibited a bulk density that remained unchanged during this period of time. The morphologies of the cellulose-based uptake fibers of the present invention, conventional fibers (Rayfloc®-J-LD), as well as cross-linked fibers of P & G were examined with Scanning Electron Microscopy (SEM). S360 Leica Cambridge Ltd., Cambridge, England = at 15 kV Samples were coated with platinum using a sputter coater (Desk-II, Denton Vacuum Inc.) for 96 seconds with gas pressure of less than about 50 mtorres and a current of approximately 30 mA The SEM picture illustrated in Figure 1 represents conventional fibers (eg Rayfloe®-J-LD) As can be seen from the photograph, conventional fibers have a shape similar to a flat ribbon An SEM of crosslinked P &G fibers obtained from a Pampers diaper, as shown in Figure 2, shows that these fibers have a shape similar to a flat ribbon with twists and curls. SEM photographs illustrated in Figures 3A, 3B, and 3C depict cellulosic based capture fibers of the present invention obtained by reaction of conventional fibers (Rayfloc®-J-LD) in the laminar form with the modifying agent of the present invention . The photographs were taken at amplifications of 100X, 200, and 1000X, respectively. As can be seen from the photographs, the modification caused the Rayfloc®-J-LD fibers to bend along the longitudinal axis, and as a result the fibers become almost round. The photographs illustrated in Figures 4A, 4B and 4C depict cellulosic based capture fibers of the present invention obtained by reaction of conventional fibers (Rayfloe®-J-LD) in a swollen form with the modifying agent of the present invention. The photographs were taken at amplifications of 100X, 200, and 1000X, respectively. As was the case with cellulosic based picking fibers prepared in the laminar form, the modifying agent of one embodiment of the present invention caused the Rayfloc®-J-LD fibers to bend along the longitudinal axis, and as a result , the fibers became almost round (see Figure 5). The SEM analysis revealed that the cellulosic-based uptake fibers of embodiments of the present invention, and crosslinked P &G fibers differed in two ways. It was found that the crosslinked fibers of P &G had a flat ribbon shape with twists and loops (Figure 2). In contrast, it was found that the cellulose-based uptake fibers of the present invention were folded along the longitudinal, circular, hollow axis (Figure 6) and did not contain kinks or twists (Figures 3A, 3B, 3C), with some of the fibers that were slightly curved. The aqueous solution containing the modifying agent of one embodiment of the present invention was analyzed by GC-MS as described in Example 13. The results revealed that the polyfunctional epoxy used in the preparation of the modifying agent was almost completely consumed. As described in Example 13, the GC-MS results revealed that the polyfunctional epoxy is present at a concentration of less than 10 ppm (Figure 7).

The cellulose-based uptake fibers of the present invention prepared as described in Example 5 were analyzed for any residual polyfunctional epoxy group. A sample of the filtration fibers with cellulose base in laminar form was sponged, and then subjected to extraction by Soxhlet with methylene chloride as described in Example 19. The extract after concentration to near dryness was diluted with hexane and analyzed by GC with mass spectroscopy with dual detectors and Flame Ionization Detectors. . GC-MC results were compared against a standard solution of diglycidyl ether of 1,4-cyclohexanedimethanol in hexane. The resulting chromatograms are shown in Figures 6 and 8. Figure 6 shows the chromatograms of the standard solution of diglycidyl ether of 1,4-cyclohexanedimethanol (20 ppm in hexane). Figure 8 shows the GC results of cellulose-based capture fiber extracts. As shown in the chromatograms in Figures 6 and 8, the fibers are free of any diglycidyl ether of unreacted 1,4-cyclohexanedimethanol. The cellulosic fibers modified according to embodiments of the present invention preferably possess characteristics that are desirable in absorbent articles. For example, the hydrophobic cellulosic fibers preferably have a centrifugal retention capacity of less than about 0.6 grams of synthetic saline solution per gram of fiber (hereinafter "g / g"). Acquisition fibers with cellulosic base also have other desirable properties, such as absorbent capacity of more than about 8.0 g / g, absorbency under load of more than about 7.0 g / g, less than about 9.0 of fines, and a rate of pickup from the third attack (or third penetration attack of the vehicle through the sheet causing a spot on the opposite side) of less than about 11.0 seconds. The particular characteristics of the cellulose-based uptake fibers of the invention are determined in accordance with the procedures described in more detail in the examples. The centrifugal holding capacity measures the ability of the fibers to retain the fluid against a centrifugal force. It is preferred that the fibers of the invention have a centrifugal retention capacity of less than about 0.6 g / g, more preferably, less than about 0.55 g / g, and even more preferably less than 0.5 g / g, the pickup fibers with cellulosic base of the present invention can have a centrifugal holding capacity as low as about 0.37 g / g. Absorbent capacity measures the ability of fibers to absorb fluid without being subjected to confining or containment pressure. The absorbent capacity is preferably determined by means of the pending cell method described herein. It is preferred that the fibers of the invention have an absorbent capacity of more than about 8.0 g / g, more preferably, greater than about 9.0 g / g, even more preferably greater than about 10.0 g / g, and more preferably greater than about 11.0 g / g The cellulose-based uptake fibers of the present invention can have an absorbent capacity as high as about 16.0 g / g. Absorbency under load measures the ability of fibers to absorb fluid against a containment or containment force, for a given period of time. It is preferred that the fibers of the invention have an absorbency under load of more than about 7.0 g / g, more preferably, greater than about 8.5 g /, and more preferably, greater than about 9.0 g / g. The cellulose-based uptake fibers of the present invention can have absorbency under load as high as about 14.0 g / g. The third penetration attack of the vehicle through the sheet causing a spot on the opposite side measures the ability of the fibers to acquire fluid, and is measured in terms of seconds. It is preferred that the fibers of the invention have a third penetration attack of the vehicle through the sheet causing a spot on the opposite side to absorb 9.0 ml of 0.9% saline of less than about 11.0 seconds., more preferably, less than about 10.0 seconds, even more preferably less than 9.5 seconds, and more preferably less than about 9.0 seconds. The cellulose-based uptake fibers of the present invention may have a third penetration attack of the vehicle through the sheet causing a spot on the opposite side as low as about 6.0 seconds. The cellulose-based uptake fibers of the present invention preferably have less than about 26% knots, more preferably less than about 20% knots, and more preferably, less than about 18% knots. The cellulose-based picking fibers of the present invention also preferably have less than about 10.0% fines, preferably less than about 8% d, and more preferably, less than about 7.0% fines. In the present invention, it is also preferred, that the cellulosic based capture fibers have a dry basis bulk density of at least about 8.0 cm3 / g fiber, more preferably at least about 9.0 cm3 / g fiber, even more preferably at least about 10.0 cm3 / g fiber, and more preferably at least about 11.0 cm3 / g fiber. In addition to being more economical, there are several other advantages to make capture fibers in laminar form. Typically, fibers crosslinked in sheet form have been expected to have an increasing potential for inter-fiber crosslinking leading to "knots" and "points" which result in poor performance in some applications. For example, when a standard purity fluff pulp, Rayfloc-J-LD, is crosslinked in laminar form with conventional crosslinking agents such as, for example, citric acid, the content of "knots" increases substantially, indicating harmful inter-fiber bonds. increasing (see Example 12, Table 5). Surprisingly, the inventors have discovered that Rayfloc-J-LD treated with the modifying agent of the present invention is laminar or roll form currently produces few knots and points than commercial picking fibers produced by individualized crosslinked fibers, such as those produced by the Weyerhaeuser Company commonly referred to as HBA (for high bulk density additive), and by Procter &; Gamble (see Example 12, Table 5). Another advantage of using the modifying agent of the present invention to make pi fibers in foamed or laminar form is that the resulting fibers are more stable to color inversion at elevated temperature. Since converting cellulosic fibers requires high temperatures (typically around 195 ° C for 10-15 minutes), which can lead to substantial discoloration with conventional cross-linking agents). Through the use of the modifying agent of the present invention, this discoloration is less likely to occur. Another benefit of the present invention is that the cellulose-based uptake fibers made in accordance with the present invention enjoy the same or better performance characteristics than conventional individualized cross-linked cellulose fibers, but avoid the processing problems associated with fibers. individualized pulsed reticulates. The properties of the cellulose-based uptake fibers according to the present invention make the fibers suitable for use, for example, as a material for loading, in the manufacture of fibers especially of high bulk density that require good absorbency and porosity. The cellulose-based uptake fibers can be used, for example, in sponge, non-woven absorbent products. The fibers may also be used independently, or preferably incorporated into other cellulosic fibers to form blends using conventional techniques, such as air stratification techniques. In an air process, the cellulose-based uptake fibers of the present invention alone or in combination with other fibers are blown onto a forming protector or sketched onto the protector via a vacuum, the wet process can also be used, combining the fibers of cellulose-based uptake of the invention with other cellulosic fibers to form sheets or meshes of blends. The cellulose-based uptake fibers of the present invention can be incorporated into various absorbent articles, preferably intended for handling body wastes such as adult incontinence pads, feminine care products, and children's diapers. The cellulose-based picking fibers can be used as a pick-up layer in the absorbent articles, and can be used in the absorbent core of the absorbent articles. Towels and wipes can also be made with the cellulose-based uptake fibers of the present invention, and other absorbent products such as filters. Accordingly, a further aspect of the present invention is to provide an absorbent article and an absorbent core that includes the cellulose based capture fibers of the present invention. The cellulose-based uptake fibers of the present invention were incorporated in a pi layer of an absorbent article, and the absorbent article was evaluated by the Specific Absorption Rate Test (SART), where the time of Fiber uptake is important. The SART method is described in detail in the Examples section. It was observed that the absorbent article containing the cellulose-based uptake fibers of the present invention provided results comparable to those obtained using commercial crosslinked fibers, especially those crosslinked with carboxylic acids. As is known in the art, absorbent cores are typically prepared using foamed pulp to give wicking effect to the liquid, and an absorbent polymer (sometimes a superabsorbent polymer (SAP)) to store liquid. As previously noted, the cellulosic based picking fibers of the present invention have high elasticity, high free swelling capacity, high absorbent capacity and absorbency under load, and low times of third penetration attack of the vehicle through the blade causing a stain on the opposite side. In addition, the cellulose-based uptake fibers of the present invention are very porous. Accordingly, the cellulose-based uptake fibers of the present invention can be used in combination with SAP and conventional fibers to prepare an absorbent (or core) composite having porosity, bulk density, elasticity, wicking effect, softness, absorber, absorbency under load, low times of third attack of vehicle penetration through the blade causing a stain on the opposite side, centrifugal stopping ability, and the like improved. The absorbent composite could be used as an absorbent core of the absorbent articles provided for the handling of body waste. In the present invention, it is preferred that the cellulosic based capture fibers be present in the absorbent compound in an amount ranging from about 10 to about 80% by weight, based on the total weight of the compound. More preferably, the cellulosic based capture fibers are present in an absorbent composite from about 20 to about 60% by weight. A mixture of conventional cellulosic fibers and cellulosic based picking fibers of the present invention together with SAP can also be used to make the absorbent composite. Preferably, the cellulosic based picking fibers of the present invention are present in the fiber blend in an amount of from about 1 to 70% by weight, based on the total weight of the fiber blend, and more preferably present in a amount from about 10 to about 40% by weight. Any conventional cellulosic fiber can be used in combination with the cellulose-based uptake fibers of the invention. Suitable additional conventional cellulosic fibers include any of the above-mentioned wood fibers, caustically treated fibers, rayon, cotton fibers, and mixtures and combinations thereof Any suitable SAP, or other absorbent material, can be used to form the absorbent core, and absorbent article of the present invention The SAP may be in the form of, for example, fibers, flakes, or granules, and is preferably capable of absorbing several times its weight of saline solution (0.9% NaCl solution). in water) and / or blood Preferably, the SAP is also capable of retaining the liquid when subjected to a load.Non-limiting examples of superabsorbent polymers applicable for use in the present invention include any SAP currently available on the market, including, but not limited to polyacrylate polymers, starch-grafted copolymers, copolymers grafted with cellulose, and deriv of crosslinked carboxymethylcellulose, and mixtures and combinations thereof. An absorbent composite made in accordance with the present invention preferably contains the SAP in an amount of from about 20 to about 60% by weight, based on the total weight of the compound, and more preferably from about 30 to about 60% by weight. The absorbent polymer can be distributed throughout the absorbent composite in the voids in the fibers. In another embodiment, the superabsorbent polymer can be attached to cellulosic based capture fibers via a linking agent that includes, for example, a material capable of binding the SAP to the fibers via hydrogen bonding (see, for example, US Pat. 5,614,570, the disclosure of which is incorporated herein by reference in its entirety). One method of making an absorbent composite may include forming a cellulosic-based collection fiber pad or a mixture of cellulose-based capture fibers, and incorporating superabsorbent polymer particles in the pad. The pad can be wet or air. Preferably the pad is via air. It is also preferred that the SAP and the cellulose-based uptake fibers, or a mixture of cellulose-based uptake fibers and the cellulose fibers are joined via air. An absorbent core containing cellulose based and superabsorbent polymer capture fibers preferably has a dry basis bulk density of between about 0.1 g / cm3 and 0.50 g / cm3, and more preferably from about 0.2 / cm3 to 0.4 g / cm3. The absorbent core can be incorporated into a variety of absorbent articles, preferably those articles intended for the management of body wastes, such as diapers, training pants, adult incontinence products, feminine care products, and towels (wet rubbers and dry). In order that various embodiments of the present invention may be more fully understood, the invention will be illustrated, but not limited, by the following examples. None of the non-specific details contained herein shall be construed as a limitation to the present invention except insofar as they may appear in the appended claims. EXAMPLES The following test methods were used to measure and determine various physical characteristics of the cellulose-based uptake fibers. Test Methods The Absorbency Test Method The absorbency test method was used to determine the absorbency under load, absorbent capacity, and centrifugal holding capacity of cellulose-based uptake fibers of the present invention. The absorbency test was carried out on a one-inch inner diameter plastic cylinder having a 100-mesh metal sieve that adheres to the "cell" at the bottom of the cylinder, which contains a plastic spacer disk having a diameter of 0.995 inches and a weight of approximately 4.4 g. In this test, the weight of the cell containing the spacer disk was determined in the vicinity of 0.001 g, and then the cylinder spacer was removed and approximately 0.35 g (weight on dry basis) of cellulosic based capture fibers were aerated in the cylinder. The spacer disk was then inserted back into the cylinder on the fibers, and the cylinder group was weighed in the vicinity of 0.001 g. The fibers in the cell were compressed with a load of 0.2815 kg / cm2 (4.0 psi) for 60 seconds, the load was then removed and the fiber pad was allowed to equilibrate for 60 seconds. The thickness of the pad was measured, and the result was used to calculate the dry basis density of the cellulosic based capture fibers. A load of 0.0211 kg / cm2 (0.3 psi) was then applied to the fiber pad by placing a weight of 100 g on top of the spacer disk, and the pad was allowed to equilibrate for 60 seconds, after which the thickness of the pad, and the result was used to calculate the dry basis density under load of the cellulose-based uptake fibers. The cell and its contents were then hung in a Petri dish containing a sufficient amount of saline solution (0.9% by weight saline solution) until it touched the bottom of the cell. The cell was allowed to stand on the Petri dish for 10 minutes, and then it was removed and hung on another empty Petri dish and allowed to drip for approximately 30 seconds. Then 100 grams of weight were removed and the weight of the cell and its content were determined. The weight of the saline solution absorbed per gram of fibers was then determined and expressed as the absorbency under load (g / g). The absorbent capacity of the cellulose-based capture fibers was determined in the same manner as the test used to determine the absorbency under the previous load, except that this experiment was carried out using a load of 0.0000704 kg / cm2 (0.001 psi). The results were used to determine the weight of the saline solution absorbed per gram of filter and expressed as the absorbent capacity (g / g). The cell was then centrifuged for 3 minutes at 1400 rpm (Centrifuge Model HN, International Equipment Co., Needham HTS, USA), and weighed. The results obtained were used to calculate the weight of saline retained per gram of filter, and it was expressed as the centrifugal retention capacity (g / g). Filter Quality The filter quality evaluations were carried out in an Op Test Fiber Quality Analyzer (Op Test Equipment Inc., Waterloo, Ontario, Canada) and Fluff Fiberization Measuring Instruments (Model 9010, Johnson Manufaturing, Inc., Appleton, WI, USA). Op Test Fiber Quality Analyzer is an optical instrument that has the ability to measure the average length of fiber, content of twists, curls and fines. The Fluff Fiberization Measuring Instrument was used to measure the content of knots, points and fines of the fibers. In this instrument, a sample of fluffed fibers was continuously dispersed in an air stream. During the dispersion, the lost fibers passed through a sieve of 16 meshes (1.18 mm) and then through a sieve of 42 meshes (0.36 mm). Pulp bunches (knots) that remained in the dispersion chamber and those that were trapped in the 42 mesh sieve were removed and weighed. The trainers are called "knots" and these are "accepted". The combined weight of these two was subtracted from the original weight to determine the weight of fibers that passed through the 0.36 mm sieve. These fibers were mentioned as "fine". Specific Absorption Rate Test (SART) The SART test method evaluates the performance of a pickup layer in an absorbent article. To evaluate the uptake properties, the Uptake Time was measured, which is the time required for a dose of saline solution to be completely absorbed in an absorbent article. In this test, the capture layer of the core sample is replaced with an air-formed cushion from the test fibers of the present invention. The core sample is placed in a test kit (obtained from Portsmouth Tool and Die Corp., Porthsmouth, VA, USA) consisting of a plastic base and a funnel cup. The base is a plastic cylinder that has an internal diameter of 60.0 mm that is used to retain the sample. The funnel cup is a plastic cylinder that has a hole with a star shape. Whose outer diameter is 58 mm. The funnel cup is placed inside the plastic base at the top of the collection layer and the core sample, and a charge of approximately 0.0422 Kg / cm2 (0.6 psi) that has a donut shape is placed on the top of the funnel cup. The equipment and its contents are placed on a level and regulated surface with several successive attacks, each of 9.0 ml of saline solution, (0.9% by weight), the time interval between doses being 20 minutes. The doses were added with a Pump Master Flex (Cole Palmer Instrument, Barrington, IL, USA) to the funnel cup, and recorded the time in seconds required for the saline solution of each dose to disappear from the funnel cup and was expressed as a time of pick-up, or third penetration attack of the vehicle through the sheet causing a spot on the opposite side. The third penetration attack of the vehicle through the sheet was recorded causing a spot on the opposite side. Example 1 The example illustrates a representative method for making a modifying agent of one embodiment of the present invention. Cyclohexanedimethanol diglycidyl ether was added (20.0 g, 76.0 mmol) to a solution of citric acid (35.0 g, 182.0 mmol) in water (35.0 ml). The suspension mixture produced was stirred at room temperature.

After about 30 minutes an exothermic reaction started, stirring was continued until a white, slightly viscous aqueous solution was produced (approximately 30.0 minutes). The solution was stirred for another 18 hours, then diluted with distilled water to approximately 800 ml. When the solution was diluted with water, turbidity developed. The pH was then adjusted to about 2.9 to 3.3 with an aqueous solution of NaOH (8.3 g, 50% by weight). After stirring for a few minutes, sodium hypophosphite (8.25 g, 23% by weight of citric acid) was added., followed by Triton X-100 (0.75 g, 0.0075% by total weight of the solution after dilution). Agitation continued for a few more minutes after which a white aqueous solution with a negligible odor was produced. More water was then added to adjust the concentration of modifying agent to approximately 5.5% (the final weight of the solution is 1.0 Kg). The solution produced was then used to modify the fibers in laminar form. Example 2 This example illustrates a representative method for making a modifying agent of one embodiment of the present invention. Cyclohexanedimethanol diglycidyl ether was added (20.0 g, 76.0 mmol) to a solution of citric acid (35.0 g, 182.0 mmol) in water (35.0 ml). The suspension mixture produced was stirred at room temperature.

After about 30 minutes an exothermic reaction started, stirring was continued until a white, slightly viscous aqueous solution was produced (approximately 30.0 minutes). The solution was then heated to about 100 ° C for 30 minutes, cooled to room temperature and diluted with distilled water to approximately 800 g. When the solution was diluted with water, turbidity developed.

The pH was then adjusted to about 2.9 to 3.3 with an aqueous solution of NaOH. After stirring for a few minutes, sodium hypophosphite (8.25 g, 23% by weight of citric acid) was added, followed by Triton X-100. (0.75 g, 0.0075% by total weight of the solution after dilution to 1 kg). Agitation continued for a few more minutes after which a white aqueous solution with a negligible odor was produced. More water was then added to adjust the concentration of modifying agent to approximately 5.5%. The solution produced was then used to modify the fibers in laminar form. Example 3 This example illustrates a representative method for making a modifying agent of one embodiment of the present invention. 1,4-Butanediol diglycidyl ether (15.4 g, 76.0 mmol) was added to a solution of citric acid (35.0 g, 182.0 mmol) in water (20.0 mL). The produced solution was stirred at room temperature. After about 30 minutes an exothermic reaction started, stirring was continued for another 18 hours, then the solution was diluted with distilled water to about 900 ml and the pH was adjusted to about 2.9 to 3.3 with NaOH. After stirring for a few minutes, sodium hypophosphite (8.25 g, 23% by weight citric acid) was added, and then more water was added to adjust the concentration of modifying agent to approximately 5.5%. The solution was stirred for a few more minutes, then used to modify the conventional fibers in laminar form. Example 4 Example 3 was repeated except that, in this experiment, neopentyl diglycidyl ether was reacted with citric acid in the same manner. Example 5 This example illustrates a representative method for making cellulosic based capture fibers of one embodiment of the present invention using the modifying agent prepared in Example 1. Rayfloc®-J-LD, commercially available from the Rayonier factory in Jesup, was obtained. , Georgia, in roll form. A sheet 30.48 cm (12 inches) x 30.48 cm (12 inches), with a basis weight of approximately 680 grams was obtained from the roll. The sheet was immersed in a solution containing the modifying agent prepared in Example 1, then compressed to achieve the desired level of modifying agent (approximately 5.5% by weight). The sheet was then dried and cured. at about 195 ° C. The curing was carried out in a compressed air laboratory oven for approximately 15 minutes. The sheet was then defibrated by feeding it through a hammer mill. The absorbent properties of the cellulose-based uptake fibers produced were then evaluated and the results summarized in Table 1. Example 6 The procedure of Example 5 was repeated, except that in this example a Rayfloe®-J- sheet was used. LD treated with caustic soda at 7% by weight. The sheet was obtained from a jumbo roll made at the Rayonier factory in Jesup, Georgia. The sheet was 30.48 cm (12 inches) x 30.48 cm (12 inches), with a basis weight of approximately 720 grams. The absorbent properties of the cellulose-based uptake fibers were then evaluated and the results summarized in Table 1 Example 7 The procedure for Example 5 was repeated, except that in this example a partially unlinked Rayfloe®-J sheet was used. -MX, commercially available from the Rayonier factory in Georgia. The sheet was obtained from a jumbo roll. The sheet was 30.48 cm (12 inches) x 30.48 cm (12 inches), with a base weight of approximately 720 grams. The absorbent properties of the cellulose-based uptake fibers produced were evaluated and the results are summarized in Table 1. Table 1. Absorbent properties of cellulose-based uptake fibers, using the modifying agent of Example 1: 5.5% modifying agent in weight, dried and cured at 195 ° C for 15 minutes. * (treated with 7% caustic soda) 1 Fluffed modified fibers as described in Example 11 below.

Example 8 This example illustrates the effect of the curing temperature on the absorbent properties of representative cellulosic based collection fibers. Three leaves were obtained [30.48 cm (12 inches) x 30.48 cm (12 inches)] that each weighed approximately 60.0 g (weight on dry basis) of a jumbo roll of Rayfloc®-J-LD made at the Rayonier factory in Jesup, Georgia. The sheets were treated with an aqueous solution containing the modifying agent prepared in Example 1 at room temperature and compressed to provide the desired level of fiber modifying agent of about 5.5% by weight. The treated sheets were then cured at various curing temperatures for approximately 15 minutes. The absorbent properties of modified sheets were evaluated as a function of curing temperature and the results are summarized in Table 2.

Table 2. Absorbent properties of cellulose-based uptake fibers with various curing temperatures.

Example 9 This example illustrates the effect of the variation of the amount and composition of modifying agent on the absorbent properties of cellulose-based uptake fibers formed in accordance with the present invention. In this example, pulp sheets of [30.48 cm (12 inches) x 30.48 cm (12 inches)] of Rayfloc®-J-LD, each weighing approximately 60.0 g (weight on dry basis) obtained from a jumbo roll, were used. as shown in Example 5. The sheets were treated with an aqueous solution containing the modifying agent prepared according to Example 1 at various concentrations and compressed to provide the desired level of modifying agent on the fibers. The sheets were cured at 195 ° C for 15 minutes. The results are summarized in Table 3. Table 3. Absorbent properties of cellulose-based uptake fibers, treated with modifying agent with various compositions EXAMPLE 10 This example illustrates the effect of using various modifying agents prepared using various polyepoxy compounds on the absorbent properties of cellulose-based uptake fibers formed in accordance with the present invention. The modifying agents were prepared in accordance with Examples 1, 3, and 4. Solutions containing modifying agents were then used to modify Rayfloc®-J-LD fibers as shown in Example 5. The absorbent properties of fibers were evaluated. uptake with cellulose base. The results are summarized in Table 4. Table 4. Absorbent properties of cellulose-based uptake fibers using modifying agents prepared from various polyepoxy compounds In Table 4 above, the abbreviations used to describe the modifying agents are as follows: CHDMDGE = diglycidyl ether of 1,4-cyclohexanedimethanol. BDDGE = diglycidyl ether of 1,4-butanediol. NPGDGE = diglycidyl ether of neopentyl glycol. EXAMPLE 11 This example illustrates a representative method for making uptake fibers with a cellulose base in a sponge form. A sample of Rayfloc®-J-LD (never dried, dried fibers can also be used) was obtained as a 33.7% wet solid coating from the Rayonier factory in Jesup, Georgia. A sample of 70.0 g (weight on dry basis) was treated with a 5.5% by weight aqueous solution containing the modifying agent prepared in Example 1 by immersion and compression at approximately 100% absorption, which produced approximately 5.5% by weight of modifying agent on the fibers. The treated fibers were then dried in a laboratory oven at approximately 60 ° C, they were defibrated by feeding them through a hammer mill (Kamas Mili HOl, Kamas Industries AB, Vellinge, Sweden) then they were cured 195 ° C for 8 minutes. The absorbent properties and the density of the fiber were then evaluated. The results are summarized in Table 1 above. EXAMPLE 12 The cellulose-based uptake fibers of the embodiments of the present invention were analyzed for fines, fiber length, kink angle, and knots and points. The results obtained are summarized in Table 5. The results of the analyzes of commercial modified fibers and conventional unmodified fibers are also summarized in Table 5. The data in Table 5 demonstrate that the cellulose-based uptake fibers of the present invention have reduced knot and dot content compared to commercially cross-linked fibers individually. In addition, the current fibers have an angle of kinking almost equal to that of conventional unmodified cellulosic fibers and much lower than those of commercial crosslinked fibers.

Table 5. Fiber quality of capture fibers with cellulose base and commercial fibers Initial Fiber% Method of% Angle Length Preparation Fine Fiber Nodes Fold (m) Rayfloc®-J- D 5.1 6.2 2.47 44.7 P &G (PamperFAL) 1 4.0 29.0 2.11 95.2 Rayfloc®-J- D Example 5 (acid 7.4 58.0 (laminar form) at 3.5% citric was used alone) Rayfloc®-J- D DP60 at 5.5 ° X 8.5 44.4 (laminar form) Rayfloc®-J- Example 5 6.9 27.0 1.96 49.0 LD (lamellar shape) Rayfloc®-J- DE emplo 5.2 2.7 2.28 (foamed shape) Rayf loe® Example 6.2 2.0 1.91 69.2 (caustic treated at 7% cold) Rayf loe®-J-MX Example 6.5 20.7 1.96 39.6 1: Prepared as shown in Example 5 except that Belclene® DP60 was used as a modifying agent (Belclene® DP-60 is a mixture of polymaleic acid terpolymer with predominantly maleic acid monomeric units (molecular weight of about 1000) and citric acid marketed by BioLab Industrial Water Additives Division). Example 13 This example describes the method used to analyze a representative aqueous solution containing the modifying agent made according to one embodiment of the present invention as described in Example 1. Approximately 100.0 g of the modifying agent were placed in a bottom flask round of 0.5 liters together with 200 ml of methylene chloride. The mixture was vigorously stirred for approximately 10 minutes and then transferred to a separatory funnel. The methylene chloride layer was separated, dried with anhydrous Na 2 CO 3, filtered, and evaporated to dryness at room temperature on a Rotavapor. The residue was then diluted with hexane (5.0 g). The diluted residue was then analyzed by GC with Flame Ionization and Mass Spectroscopy detectors. Comparing the results to a calibration curve 'indicates that he reacted more than 95% of the diglycidyl ether of 1,4-cyclohexane. The analysis was carried out in Trace-GC 2000 (Therom Finnigan, Austin TX with MS and FID detectors.

Chromatography column: CAP RTX-5 Length = 30 cm; gave. = 0.25 mm Control: Flow = 1,000 ml / min; Detention time = 30.00 min. EXAMPLE 14 This example describes the test method used to study the cellulose-based uptake fiber extract of the present invention. The fibers used in this example were produced according to Example 5. Fibers modified after defibration 820.0 g) were subjected to Soxhlet extraction with methylene chloride for approximately 6 hours, the extract was filtered, concentrated by reducing its volume in a Rotavapor at 30 ° C under reduced pressure. The extracts were then subjected to analysis by GC-MS. The results indicated the complete absence of diglycidyl ether of 1,4-cyclohexanedi ethanol. Example 15 This example describes the "aging" test method used to study the strength of representative samples of cellulose-based uptake fibers made according to embodiments of the present invention to transform unmodified fibers. This transformation was observed in traditional reticulated fibers made from fibers crosslinked with alkane carboxylic acids, such as, citric acid. The aging test was carried out on two representative samples of cellulose-based uptake fibers made according to embodiments of the present invention in the laminar form, as described in Example 5 above. Each sample weighed approximately 2,000 g, the samples were aerated in pads each having a diameter of approximately 60.4 mm. One pad served as a target, and the other was aged by heating in an oven with a controlled humidity of 80% to about 85% at 90 ° C for 20 hours. After the setting time, the sample pad was allowed to equilibrate in an environment of 50% humidity at room temperature for about 8 days. The two pads (sample and blank) were then compressed with a load of approximately 0.5348 kg / cm2 (7.6 psi) for 60 seconds, the weights were removed, and the pads were allowed to equilibrate for 1 minute. The thickness of the pads was measured and the bulk density was determined. The absorptive properties of the blank and the sample were determined by the absorbency test method described above. The results are summarized in Table 6 below. Table 6. Absorbing properties of aged cellulose-based uptake fibers The results summarized in Table 6 reveal that the bulk density and centrifugal retention of cellulose-based capture fibers remained unchanged after heating the fibers at elevated temperatures and storing them for a prolonged period of time. These results indicate that the crosslinking in the cellulose-based uptake fibers according to the present invention are stable. EXAMPLE 16 Cellulosic based capture fibers made according to one embodiment of the present invention were tested for liquid capture properties. To evaluate the capture properties, the Capture Time was measured. The Capture Time is the time required for a dose of saline solution to be completely absorbed in the absorbent article. The Capture Time was determined by means of the SART test method, described above. The test was conducted on an absorbent core obtained from a commercially available stage 3 diaper (Huggies®, Kimberley-Clark). A sample core was cut from the center of the diaper, had a circular shape with a diameter of 60.0 mm, and weighed approximately 2.8 g (± 0.2 g). In this test, the capture layer of the sample core was replaced with an air-cushion made from the cellulose-based uptake fibers of one embodiment of the present invention. The fiber pad weighed approximately 0.7 g and was compacted to a thickness of about 3.0 to about 3.4 mm before being used. The core sample that included the capture layer was placed in the test capture equipment. The collection equipment and its contents were placed on a level surface and dosed with three successive attacks, each of 9.0 ml of saline solution (0.9% by weight), the time interval between doses being 20 min. The time in seconds required for the saline solution of each dose to disappear from the cup of the funnel was recorded and expressed as a pick up time, or penetration of the vehicle through the sheet causing a spot on the opposite side. The third penetration attack of the vehicle through the sheet causing a stain on the opposite side is provided in Table 7 below. The data in Table 7 includes the results obtained from test capture layers of commercial crosslinked fibers and conventional uncrosslinked fibers. It can be seen from Table 7 that the uptake times of the modified fibers of the embodiments of the present invention are as gas or better than the uptake times of commercial cross-linked fibers.

Table 7. Time of capture of liquid for absorbent products that contain capture fibers with a cellulose base and representative commercial fibers. 1: Synthetic fiber (weight = 0.72 g, basis weight < = 255 g / m2) 2: Synthetic fiber (weight = 0.36 g, basis weight = 127 g / m2). Example 17 The cellulose-based uptake fibers made in accordance with the present invention were evaluated for uptake and rewet. The tests measured the rate of absorption of multiple fluid attacks to an absorbent product and the amount of fluid that can be detected on the surface of the absorbent structure after saturation with a given amount of saline solution while the structure is under a load of 0.035 Kg / cm2 (0.5 psi). This method is suitable for all types of absorbent materials, especially those intended for urinary application. The uptake and rewetting for the cellulose-based uptake fibers of the present invention as well as for conventional cross-linked fibers were determined using standard procedures known in the art. The fluid capture and rewet test initially recorded the dry weight of a 10 cm x 12 cm (or other desired size) test specimen of the product or absorbent material, aerated fiberglass pickup pad with cellulosic base with dimensions similar to that of the absorbent product was placed on top of the absorbent product. The fiber pad weighed approximately 4.5 g and was compacted to a bulk density of approximately 0.8 g / cm3 before it was used. Then, a fixed volume amount of 100 ml of saline was applied to the test specimen through a column of fluid release to an impact zone of 2.54 cm (1 inch in diameter under a load of 0.00703 Kg / cm2 (0.1 psi) .The time (in seconds) for the complete saline solution of 80 milliliters to be absorbed. recorded as the "acquisition time", and then the test specimen was left undisturbed for a waiting period of 30 minutes.A stack of pre-weighed filter papers eg 15 of Whatman # 4 (70 mm) was placed on The solution, the point of attack on the test sample, and a load of 0.03518 kg / cm2 (0.5 psi) (2.5 kg) is then placed on the stack of filter papers on the test sample for two minutes. wet filter are then withdrawn, and the wet weight is recorded. The difference between the initial dry weight of the filter papers and the final wet weight is recorded as the "rewet" value of the test specimen. This complete test was repeated 2 times on the same wet test specimen and in the same position as before. Each collection time and rewet volume is reported along with the average and standard deviation. The "capture speed" is determined by dividing the volume of 80 ml of the liquid used between the previously recorded collection time. For any specimen having a protruding side is the side initially subjected to the test fluid. Table 8: Uptake and rewetting for absorbent articles containing cellulosic-based collection fibers and representative commercial fibers 1. The core was obtained from the Pamper® level 4 diaper. 2. The bulk density and density of the fibers used in this experiment are approximately equal. 3. Individualized crosslinked fibers produced by Weyerhaeuser. 4. Prepared in accordance with the present invention as shown in Example 5. 5. Prepared in accordance with the present invention as shown in Example 11. Example 18 This example shows the method used to determine the ISO brightness of captapion fibers with cellulosic base of the present invention. The cellulose-based uptake fibers produced in accordance with the present invention in sheet form were defibrated by feeding the sheet through a hammer mill and then aerated as shown in Example 16. The cushion produced was then evaluated for ISO brightness of compliance with the TAPPI test methods T272 and T525. The results are summarized in Table 9 below: Table 9: ISO brightness The results of Table 9 reveal that the cellulose-based uptake fibers made according to the present invention provide better ISO brightness, when compared to conventional cross-linked fibers. Although the invention has been described with reference to particularly preferred embodiments and examples, those skilled in the art will recognize that various modifications may be made.

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty, and therefore the content of the following is claimed as property: CLAIMS 1. A modifying agent for making cellulosic uptake fibers in laminar form, characterized in that the modifying agent is the reaction product of a polycarboxylic acid and a polyfunctional epoxy.
2. The modifying agent according to claim 1, characterized in that the polycarboxylic acid comprises at least one hydroxyl functional group.
3. The modifying agent according to claim 1, characterized in that the polycarboxylic acid comprises at least one functional amino group.
4. The modifying agent according to claim 1, characterized in that the polycarboxylic acid is an alkanepolycarboxylic acid.
5. The modifying agent according to claim 4, characterized in that the alkanepolycarboxylic acid is selected from the group consisting of: 1,2,4,4-butanetetracarboxylic acid; 1, 2, 3-propanetricarboxylic acid; oxydisuccinic acid; citric acid; Itaconic acid; maleic acid; tartaric acid; glutaric acid; iminodiacetic acid, and mixtures and combinations thereof. The modifying agent according to claim 1, characterized in that the polyfunctional epoxy comprises a substituent selected from the group consisting of: hydrogen, branched or unbranched alkyl groups, saturated cyclic, unsaturated, unsaturated cyclic; and combinations and mixtures thereof. The modifying agent according to claim 1, characterized in that the polyfunctional epoxy is selected from the group consisting of: diglycidyl ether of 1,4-cyclohexanedimethanol; Diglycidyl 1,2-cyclohexanedicarboxylate; Diglycidyl 1,2,3,4-tetrahydrophthalate; triglycidyl ether glycerol propoxylate; diglycidyl ether of 1,4-butanediol, diglycidyl ether of neopentyl glycol; and combinations and mixtures thereof. 8. A process for making the modifying agent according to claim 1, the process is characterized in that it comprises reacting the polycarboxylic acid compound and the epoxy functional compound in aqueous medium. 9. The process according to claim 8, characterized in that the polycarboxylic acid and the polyfunctional epoxy are mixed in a molar ratio from about 1: 1 to 3: 1. The process according to claim 8, characterized in that the reaction mixture additionally comprises a catalyst for accelerating the formation of an ether bond between a hydroxyl group of the polycarboxylic acid and an epoxy group of the polyfunctional epoxy. 11. The process according to claim 10, characterized in that the catalyst is a Lewis acid selected from the group consisting of: aluminum sulfate, magnesium sulfate, and any Lewis acid containing either metal and a halogen. 12. The process according to claim 8, characterized in that the reaction between the polycarboxylic acid and the polyfunctional epoxy is carried out at a temperature range from about room temperature to reflux temperature. 13. The process according to claim 8, characterized in that the reaction between the polycarboxylic acid and the polyfunctional epoxy is carried out at room temperature for at least about 6 hours. The process according to claim 8, characterized in that the reaction between the polycarboxylic acid and the polyfunctional epoxy is carried out at room temperature for at least about 10 hours. 15. The process in accordance with the. claim 8, characterized in that the reaction between the polycarboxylic acid and the polyfunctional epoxy is carried out at room temperature for at least about 16 hours. 16. A method of making cellulosic based capture fibers characterized in that it comprises: providing a modifying agent solution comprising the modifying agent according to claim 1; provide fiber with cellulosic base; apply the solution of the modifying agent to the cellulose-based fiber to impregnate the cellulose-based fiber with the modifying agent; and drying and curing the fiber with impregnated cellulose base. 17. The method according to claim 16, characterized in that the modifying agent solution additionally comprises a surfactant. The method according to claim 17, characterized in that the surfactant is added in an amount from about 0.001 to about 0.2% by weight based on the total weight of the aqueous mixture. The method according to claim 17, characterized in that the surfactant is selected from the group consisting of: Triton X-100, Triton X-405, Triton GR-5, sodium lauryl sulfate, lauryl bromoethyl ammonium chloride, nonylphenols ethoxylated , and polyethylene alkyl ethers. The method according to claim 16, characterized in that the solution of the modifying agent has a pH from about 1.5 to about 5. The method according to claim 16, characterized in that the solution of the modifying agent has a pH of about 1.5 to about 3.5. 22. The method according to claim 16, characterized by applying the modifying agent solution to the cellulosic based fiber comprises a method selected from the group consisting of: spraying, dipping, rolling or application with a compaction press, press calibration or a blade coater. 23. The method according to claim 16, characterized in that the fiber with cellulosic base is provided in sheet form. 24. The method according to claim 16, characterized in that the fiber with cellulosic base is provided in a spongy form. 25. The method according to claim 16, characterized in that the fiber with cellulosic base is provided in the form of a non-woven supporting plate. The method according to claim 16, characterized in that the modifying agent solution is applied to the cellulose-based fiber to provide about 40% to about 150% by weight of solution on the fiber based on the total weight of the fiber. fiber. 27. The method according to claim 16, characterized in that the concentration of the modifying agent in the solution is in the range from about 2 to about 7% by weight. 28. The method according to claim 16, characterized in that the modifying agent solution is applied to the cellulose-based fiber to provide about 0.8% to 10.5% weight modifying agent, based on the weight of the oven-dried fiber. 29. The method according to claim 16, characterized in that the modifying agent solution is applied to the cellulosic based fiber to provide about 3 to 6% by weight of modifying agent, based on the total weight of the fiber. 30. The method according to claim 16, characterized in that the solution of the modifying agent further comprises a catalyst for accelerating the formation of an ester bond between the hydroxyl groups of the cellulosic based fiber and the carboxyl groups of the modifying agent. The method according to claim 30, characterized in that the catalyst is selected from the group consisting of alkali metal salts of phosphorus-containing acids such as alkali metal hypophosphites, alkali metal phosphites, alkali metal polyphosphonates, phosphates of alkali metal, and alkali metal sulfonates. 32. The method according to claim 30, characterized in that the catalyst is added in an amount from about 0.1 to 0.5% by weight, based on the total weight of the modifying agent. 33. The method according to claim 16, characterized in that the fiber with cellulosic base is provided in a dry state. 34. The method according to claim 16, characterized in that the fiber with cellulosic base is provided in a dry state. 35. The method according to claim 16, characterized in that the cellulose-based fiber is a conventional cellulose fiber. 36. The method according to claim 35, characterized in that the conventional cellulose fiber is wood pulp fiber selected from the group consisting of hard wood cellulose pulp, soft wood cellulose pulp obtained from a process Sulphite chemical or Kraft and combinations or mixtures thereof. 37. The method according to claim 36, characterized in that the hard wood cellulose pulp is selected from the group consisting of gum, maple, cedar, eucalyptus, poplar, beech wood, and poplar wood, or mixtures and combinations thereof. 38. The method according to claim 36, characterized in that the soft cellulose pulp is selected from the group consisting of Swamp Pine, White Pine, Caribbean Pine, Pacific Tsuga, Fir, Douglas Fir and mixtures and combinations thereof. 39. The method according to claim 35, characterized in that the conventional cellulose fiber is derived from one or more components selected from the group consisting of: cotton fibers, cotton linters, bagasse, canine hair wool, flax, grass and combinations and mixtures thereof. 40. The method according to claim 16, characterized in that the fiber with cellulosic base provided is a caustically treated fiber. 41. The method according to claim 40, characterized in that the caustic-treated fiber is prepared by treating a liquid slurry of pulp at a temperature from about 5 ° C to about 85 ° C with an aqueous solution of metal salt alkaline having an alkali metal salt concentration of about 2 weight percent to about 25 weight percent of said solution for a period of time ranging from about 5 minutes to about 60 minutes. 42. The method according to claim 40, characterized in that the fiber with cellulosic base is selected from the group consisting of unbleached, partially bleached and totally bleached cellulosic fibers. 43. The method according to claim 16, characterized in that the drying and curing takes place in a one-stage process. 44. The method according to claim 16, characterized in that drying and curing are conducted at a temperature in the range from about 130 ° C to about 225 ° C. 45. The method according to claim 16, characterized in that drying and curing are conducted for about 3 minutes to about 15 minutes at temperatures in the range of about 130 ° C to 225 ° C. 46. The method according to claim 16, characterized in that drying and curing take place in a two-stage process. 47. The method according to claim 46, characterized in that the drying and curing comprises: first drying the impregnated cellulose fiber, and curing the dry cellulose fiber. 48. The method according to claim 46, characterized in that the drying and curing comprises: drying the impregnated cellulosic fiber at a temperature lower than the curing temperature, and curing the dry impregnated cellulosic fiber for about 1 to 10 minutes at a temperature in the cellulose fiber. range from about 150 ° C to about 225 ° C. 49. The method according to claim 46, characterized in that drying and curing comprises: drying the impregnated cellulosic fiber at a temperature in the range of from about room temperature to about 130 ° C, and curing the impregnated cellulosic fiber by about 0.5. to about 5 minutes at a temperature in the range of about 130 ° C to about 223 ° C. 50. The cellulose-based uptake fiber produced by the method according to claim 16. 51. The fiber according to claim 50, characterized in that the cellulose-based uptake fibers have a centrifugal retention capacity of less than approximately 0.6 grams of a 0.9% by weight saline solution per gram of oven-dried fiber. 52. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have a centrifugal retention capacity of less than about 0.55 grams of saline / gram of oven-dried fiber. 53. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have a centrifugal retention capacity of less than about 0.5 grams of saline / gram of fiber dried in the oven. 54. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have an absorbent capacity of at least about 8.0 g of saline solution / gram of oven-dried fiber. 55. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have an absorbent capacity of at least about 9.0 g of saline solution / gram of oven-dried fiber. 56. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have an absorbent capacity of at least about 10.0 g of saline solution / gram of oven-dried fiber. 57. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have an absorbent capacity of at least about 11.0 g of saline solution / gram of oven-dried fiber. 58. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have an absorbency under load of at least about 7.0 g of saline solution / gram of oven-dried fiber. 59. The fiber according to claim 50, characterized in that the cellulosic-based capture fibers have an absorbency under load of at least about 8.5 g of saline solution / gram of oven-dried fiber. 60. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have an absorbency under load of at least about 9.0 g of saline / gram of oven-dried fiber. 61. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have a dry bulk density of at least about 8.0 cm 3 / gram of oven-dried fiber. 62. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have a dry bulk density of at least about 9. 0 cm 3 / gram of oven-dried fiber. 63. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have a dry bulk density of at least about 10.0 cm3 / gram of oven-dried fiber. 64. The fiber according to claim 50, characterized in that the cellulose-based capture fibers have a dry bulk density of at least about 11.0 cm3 / gram of oven-dried fiber. 65. The fiber according to claim 50, characterized in that the cellulose-based picking fibers after defibration have a knot and dot content of less than about 26%. 66. The fiber according to claim 50, characterized in that the cellulose based picking fibers after defibration have a knot and dot content of less than about 20%. 67. The fiber according to claim 50, characterized in that the cellulose based picking fibers after defibration have a knot and dot content of less than about 18%. 68. The fiber according to claim 50, characterized in that the cellulose-based capture fibers after defibration have a fines content of less than about 10%. 69. The fiber according to claim 50, characterized in that the capture fibers with cellulose base after defibration have a fines content of less than about 9%. 70. The fiber according to claim 50, characterized in that the cellulose-based capture fibers after defibration have a fines content of less than about 8%. 71. The fiber according to claim 50, characterized in that the cellulose-based capture fibers after defibration have a fines content of less than about 7%. 72. The fiber according to claim 50, characterized in that the cellulose based capture fibers have an ISO brightness of more than 70%. 73. The fiber according to claim 50, characterized in that the capture fibers with cellulosic base have a centrifugal retention capacity of less than about 0.55 g of saline solution / gram of oven-dried fiber and an ISO brightness of more than 75% 7 The fiber according to claim 50, characterized in that the cellulosic-based capture fibers after defibration in Kamas provide fibers with more than 75% accepted, wherein the defibrated fibers have a centrifugal retention capacity of less than about 0.55 g. of saline solution / gram of fiber dried in the oven and an ISO brightness of more than 75%. 75. An absorbent article characterized in that it comprises the cellulosic-based collection fibers according to claim 50. The absorbent article according to claim 75, characterized in that the absorbent article is at least one article selected from the group consisting of: of diapers for children, feminine care products, training pants, and funds for adult incontinence. 77. The absorbent article according to claim 75, characterized in that the absorbent article comprises a liquid-penetrable top sheet, an impenetrable backing sheet by the liquid, a pick-up layer, and an absorbent structure, wherein the layer collection is disposed below the top sheet, and the absorbent structure is located between the acquisition layer and the security sheet. 78. The absorbent article according to claim 77, characterized in that the acquisition layer comprises the cellulose based capture fibers. 79. The absorbent article according to claim 77, characterized in that the absorbent structure comprises a superabsorbent polymer composite and cellulose fibers. 80. The absorbent article according to claim 79, characterized in that the superabsorbent polymer is selected from the group consisting of polyacrylate polymers, starch grafted copolymers, copolymer grafted with cellulose, cross-linked carboxymethylcellulose derivatives, and mixtures and combinations thereof. . 81. The absorbent article according to claim 79, characterized in that the superabsorbent polymer is in the form of fiber, flake, or granules. 82. The absorbent article according to claim 79, characterized in that the superabsorbent polymer is present in an amount from about 20 to about 60% by weight, based on the total weight of the absorbent structure. 83. The absorbent article according to claim 79, characterized in that the cellulosic fiber comprises the cellulosic based capture fiber. 84. The absorbent article according to claim 79, characterized in that the cellulosic fiber comprises a mixture of the capture fibers with cellulosic base and cellulosic fiber. 85. The absorbent article according to claim 84, characterized in that the cellulosic fiber is a wood pulp fiber selected from the group consisting of hardwood pulp, soft cellulose pulp obtained from a sulphite or Kraft chemical process. , mercerized, rayon, cotton fibers, and combinations or mixtures thereof. 86. The absorbent article according to claim 83, characterized in that the cellulosic based capture fibers are present in an amount from about 10 to about 80% by weight, based on the total weight of the absorbent structure. 87. The absorbent article according to claim 83, characterized in that the cellulosic based capture fibers are present in an amount from about 20 to about 60% by weight, based on the total weight of the absorbent structure. 88. The absorbent article according to claim 83, characterized in that the cellulose-based capture fibers are present in the fiber mixture in an amount from about 4 to 40% by weight, based on the total weight of the total fiber . 89. The absorbent article according to claim 83, characterized in that the cellulose-based uptake fibers are present in the fiber mixture in an amount from about 10 to about 40% by weight, based on the total weight of the fiber total. 90. The absorbent article according to claim 77, characterized in that the absorbent structure comprises a discrete acquisition layer comprising the capture fiber with a cellulose base, and a lower absorbent structure.; wherein said discrete uptake layer has a basis weight in the range of 40 to 400 grams. 91. The absorbent article according to claim 90, characterized in that the discrete collection layer extends the total extension of the lowest absorbent structure. 92. The absorbent article according to claim 90, characterized in that the discrete acquisition layer has a width of less than 80% of the lowest absorbent structure. 93. The absorbent article according to claim 90, characterized in that the discrete acquisition layer has a length that is 120% to 300% of the length of the lowest absorbent structure. 9. The absorbent article according to claim 79, characterized in that the absorbent structure comprises a single layer absorbent structure having a large surface layer of the cellulose-based picking fiber with a basis weight in the range of 40 to 400 grams. 95. The absorbent article according to claim 79, characterized in that the absorbent article comprises a single-layer absorbent structure having a high surface layer of the cellulose-based collection fibers where more than 70% of the total collection fiber in the absorbent structure it resides at 30% above the absorbent structure. 96. The absorbent article according to claim 94, characterized in that the high surface layer has an area of about 30 to 70% of the area of the absorbent structure.