MXPA00006753A - Absorbent polymer compositions that have high sorption capabilities under applied pressure - Google Patents

Abstract

They are disclosed in the present application by absorbent polymer compositions useful in the absorption of body fluids such as urine, menses, and the like. In particular, the invention relates to ion exchange mixed stratum absorbent polymer compositions having excellent absorbency performance properties in terms of the absorbent capacity under a confining pressure of 4.8 kPa and / or 9.6 kPa. The invention also relates to absorbent members comprising the compositions of mixed stratum absorbent polymer, ion exchange, and absorbent articles comprising absorbent members.

Description

ABSORBENT POLYMER COMPOSITIONS THAT HAVE SORCTION CAPACITIES ELEVATED UNDER AN APPLIED PRESSURE FIELD OF THE INVENTION The present application relates to absorbent polymer compositions having high sorption capacities under an applied load. The application also relates to absorbent members comprising the absorbent polymer and absorbent articles comprising these absorbent members.

These absorbent polymer compositions, members and articles are particularly useful for absorbing body fluids such as urine and menstruation.

BACKGROUND OF THE INVENTION The development of highly absorbent members to be used as disposable diapers, pads and incontinence pads for adult and catamenial products such as sanitary napkins are the subject of substantial commercial interest. A highly desired feature for these products is thinness. For example, diapers that are thinner or less bulky when worn, fit better under clothing, and are less noticeable. These are also more compact within the package, making the combs easier to carry and store by the consumer. Packing compaction also results in reduced distribution costs by the manufacturer and distributor including less shelf space required in the warehouse per diaper unit.

The ability to provide thinner absorbent articles such as diapers has been contingent on the ability to develop relatively thin absorbent cores or structures that can acquire and store large quantities of discharged body fluids, particularly urine. In this regard, the use of certain absorbent polymers often referred to as "hydrogels", "superabsorbents", "xerogels" or "hydrocolloid" material, has been particularly important. See, for example, U.S. Patent No. 3,699,103 (Harper et al.), Issued June 13, 1972; and U.S. Patent No. 3,770,731 (Harmon), issued June 20, 1972, disclosing the use of these materials (hereinafter referred to as "absorbent polymers") in absorbent articles. In fact, the development of thinner diapers has been the direct consequence of thinner absorbent cores that take advantage of the ability of these absorbent polymers to absorb large amounts of discharged body fluids, typically when used in combination with a fibrous matrix. . See, for example, U.S. Patent No. 4,673,402 (Weisman et al.), Issued June 16, 1987 and U.S. Patent No. 4,935,022 (Lash et al.), Issued June 19, 1990. , which disclose double layer core structures comprising a fibrous matrix and absorbent polymers useful in making thin, compact, non-bulky diapers. These absorbent polymers are often made by initiating polymerization of unsaturated carboxylic acids or derivatives thereof, such as acrylic acid, alkali metal (eg, sodium and / or potassium), or ammonium salts of acrylic acid, alkyl acrylates and the like , in the presence of relatively small amounts of di- or polyfunctional monomers such as N, N'-methylenebisacrylamide, trimethylolpropane triacrylate, ethylene glycol di (meth) acrylate, or triallylamine. The di- or polyfunctional monomer materials serve to lightly crosslink the chains of the polymer making them insoluble in water, still able to swell in water. These slightly cross-linked absorbent polymers contain a multiplicity of carboxyl groups attached to the polymer structure. These carboxyl groups generate an osmotic driving force for the absorption of bodily fluids through the network of the cross-linked polymer. The absorbent polymers can also be made by polymerizing unsaturated amines or derivatives thereof in the presence of relatively small amounts of di- or poly-functional monomers., in an analogous way. The degree of crosslinking of these absorbent polymers is an important factor in establishing their absorbent capacity and gel strength. Absorbent polymers useful as absorbers within absorbent structures and articles such as disposable diapers need to have adequate sorption capacity as well as adequately high gel strength. The sorption capacity needs to be high enough to allow the absorbent polymer to absorb significant amounts of the aqueous body fluids encountered during the use of the absorbent article. The gel strength is related to the tendency of the swollen polymer particles to deform under an applied stress, and needs to be such that the particles do not deform and do not fill the hollow capillary spaces within the absorbent member or the article to an unacceptable extent, thus inhibiting the fluid uptake regime or fluid distribution in the member / article. In general, the permeability of a zone or layer comprising the swollen absorbent can be increased by increasing the crosslinking density of the polymer gel, thereby increasing the strength of the gel. However, this also typically reduces the absorbent capacity of the gel undesirably. See, for ple, United States Patent No. 4,654,039 (Brandt et al.), Issued March 31, 1987 (reissued on April 19, 1988 as reissued United States Patent No. 32,649) and U.S. Patent No. 4,834,735, issued May 30, 1989.

Many of the known absorbent polymers can exhibit gel blocking under certain conditions. "Gel blocking" occurs when the particles of the absorbent polymer deform to fill the hollow capillary spaces in the absorbent member or article to an unacceptable degree, thus inhibiting the rate of fluid uptake or fluid distribution in the member / article. Once gel blocking occurs, the capture or distribution of additional fluid takes place via a very slow diffusion process.In practical terms, this means that the gel block can substantially prevent the distribution of fluids towards relatively Dryings within the absorbent member or article Leakage of the absorbent article can still take place long before the absorbent polymer particles in the absorbent article are fully saturated or before the fluid can diffuse or transmit by wicking the particles of "blocking" in the rest of the absorbent article, see the patent of the No. 4,834,735 (Alemany et al.), issued May 30, 1989. This phenomenon of gel blocking has typically necessitated the use of a fibrous matrix in which the absorbent polymer particles are dispersed. This fibrous matrix keeps the particles of the absorbent polymer separated from one another and provides a capillary structure that allows the fluid to reach the absorbent polymer located in regions far from the initial point of fluid discharge. See U.S. Patent No. 4,834,735 (Alemay et al.), Issued May 30, 1989. However, the dispersion of the absorbent polymer in a fibrous matrix at relatively low concentrations, in order to reduce or prevent blockage of The gel can significantly increase the volume of the absorbent article or reduce the total fluid storage capacity of the thinner absorbent structures. Using lower concentrations of these absorbent polymers limits a little the real advantage of these materials, ie their ability to absorb and retain large amounts of body fluids per given volume. Absorbent polymers are typically lightly crosslinked polyelectrolytes that swell in aqueous electrolytic solutions primarily as a result of an osmotic driving force. The osmotic driving force to inflate the absorbent polymer results primarily from the polyelectrolyte counterions that dissociate from the polyelectrolyte but are maintained within the swollen polymer due to electroneutrality considerations. Absorbent polymers containing weak acid or weak base groups (eg, carboxylic acid or amine functional groups) in their non-neutralized forms are only lightly dissociated in urine solutions. These absorbent polymers of weak acid or weak base must be at least partially neutralized with a base or acid, respectively, in order to generate substantial concentrations of dissociated counterions. Without any neutralization, these weak acid or weak base absorbent polymers do not swell at their maximum potential gel capacity or absorbent capacity. In contrast, the absorbent capacity of absorbent polymers comprising functional groups of relatively strong acid or relatively strong base (for example, sulfonic acid or quaternary ammonium hydroxide groups), are much less sensitive to the degree of neutralization. However, the use of these strong acid or strong base absorbent polymers in their non-neutralized forms have the potential to divert the pH of the fluid in contact with the polymer to unacceptably low or high values. These also tend to have relatively few functional groups per unit weight of the polymer due to the high molecular weight of the repeating unit. This tends to reduce the osmotic driving force for the absorption of fluids in these materials.

Even after neutralization, the osmotic driving forces to inflate and thus the? Absorbent capacity or gel volume of the polyelectrolyte absorbent polymers are greatly depressed by the dissolved simple electrolytes normally present in body fluids such as the urine. By reducing the concentration of dissolved electrolyte in the urine (for example, by dilution with distilled water) the absorbent capacity of a polyelectrolyte absorbent polymer can be greatly increased. The concentration of dissolved electrolyte in an aqueous solution can be substantially reduced by mixed strand ion exchange techniques. (The ion exchange columns are often used commercially to deionize water). The electrolyte concentration is reduced by the combined effect of the exchange of the dissolved cations (eg, Na +) by the H + ions and the effective exchange of the dissolved anions (eg, CI ") by the OH ions". The H + and OH "ions are effectively combined in the solution to produce H2O The degree to which a mixed ion exchange stratum system can potentially reduce the electrolyte concentration depends on the ion exchange capacity of the system, the concentration of the simple electrolyte dissolved in the aqueous solution, and the ratio of aqueous solution of electrolyte to ion exchange polymer.The ion exchange resins have been used to increase the absorbent capacity of absorbent articles containing absorbent polymers, see, for example, U.S. Patent No. 4,818,598 issued April 4, 1989 to Wong, WO 96/15163 published May 23, 1996 by Palumbo et al., WO 96/151180 published May 23, 1996 by Palumbo et al. , the Japanese Publication Kokai 57045057A published on March 13, 1982, and the Japanese Publication Kokai 57035938A published on February 26, 1982. However, the need to incorporate large quantities of ion exchange resins with the capacity to Relatively low ion exchange has little or no absorbent capacity which generally increases the volume and cost of the absorbent article to an unacceptable degree. A mixture of an absorbent polymer containing unneutralized acid groups and an absorbent polymer containing unneutralized base groups has a potential to function as a mixed ion exchange stratum system and effectively reduces the concentration of the dissolved simple electrolyte in solution. Further, if the absorbent polymer in a mixed strand ion exchange system contains weak acid groups which start in their non-neutralized form, then the resulting exchange of H + by, for example, Na +, results in the conversion of the absorbent polymer from its form not neutralized until the neutralized form. In this way, the osmotic driving force for the swelling (and thus the absorption capacity) of a weak acid absorbent polymer increases as a result of ion exchange in a mixed strand ion exchange absorbent system. Similarly, if the absorbent polymer in a mixed stratum ion exchange system contains weak base groups that start in their non-neutralized form, then the resulting exchange of OH ", by, for example, CI" (or the addition of HCl to a free amino group), results in the conversion of the absorbent polymer from its unneutralized form to the neutralized form. Therefore, the osmotic conduction force for swelling of a weak base absorbent polymer also increases as a result of ion exchange in a mixed strand ion exchange absorbent system. Effective neutralization of all of the weak acid or weak base groups in an absorbent polymer (ie, complete neutralization) does not necessarily occur at neutral pH. Effective neutralization of some fraction of the weak acid or weak base groups (i.e., partial neutralization) is likely to occur in the mixed ion exchange stratum systems comprising these polymers. He The use of mixed exchange absorbent polymers of mixed layer to increase the absorption capacity has been described in PCT applications Nos. WO 96/17681 (Palumbo, published June 13, 1996), WO 96/15162 (Fomasari and others, published May 23, 1996) and in United States Patent No. 5,274,018 (Tanaka, issued December 28, 1993). In an absorbent member (for example, a mixture of absorbent polymers and cellulose fiber), only a part of the total fluid contained in the member is absorbed by the absorbent polymer. The balance of the fluid is typically absorbed by other components (for example, in the pores formed by the fiber structure). However, even when this fluid is not absorbed by the absorbent polymer, the electrolyte dissolved in this fluid can diffuse into the absorbent polymer. Reducing the amount of fiber (or other nonabsorbent polymer components capable of absorbing fluid) minimizes the amount of additional solution and thus the amount of additional salt that must be exchanged in order to achieve a given reduction in the concentration of the electrolyte. In this way, the mixed strand ion exchange absorbent polymer systems provide the majority of the benefit, in terms of maximizing the absorbent capacity, in the absorbent members which contain relatively high concentrations of the absorbent polymer. Although absorbent polymers of mixed ion-exchange stratum in an absorbent member can increase the osmotic combination strength for swelling this has not resulted in early improvement in absorbency performance in terms of the absorbent capacity for confining pressures. of 0.7 psi or greater. Under these confining pressures, the previously disclosed mixed exchange stratum absorbent polymers tend to deform to fill the hollow capillary spaces between the particles, thus inhibiting the fluid uptake regime. As a result, the absorption capacities of the The previously disclosed mixed ionic strand absorbent polymers are not significantly greater than the absorption capacities of a conventional absorbent polymer under confining pressures of 0.7 psi or greater. Accordingly, it would be desirable to provide a composition comprising absorbent polymers capable of absorbing a large amount of synthetic urine solution under confining pressures of 0.7 psi or greater. It is further desired that relatively high capacities are achieved within a period of time that is typically less than the duration of use (e.g. at night) of the articles comprising the present absorbent compositions. In this regard, it is desirable that the absorbent polymers achieve a high capacity within a period of, for example, 2, 4, 8, or 16 hours. It would be further desirable to provide an absorbent polymer system having high porosity and / or permeability, as well as good integrity of a gel bed.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to absorbent materials useful in the containment of body fluids such as urine. In particular, the invention relates to absorbent materials having excellent absorbency performance properties in terms of the absorbent capacity under a confining pressure of 0.7 psi and / or 1.4 psi. In one aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a performance capability under pressure in the synthetic urine solution (hereinafter "PUP" or "PUP capacity") of at least about 30 g / g under a confining pressure of 4.8 kPa after two hours. (The method to measure the capacity of PUP at a given pressure for a given period of time is described in the Test Methods section below). In another aspect, the invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least 36 g / g under a confining pressure of 4.8 kPa after 4 hours. In yet another aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least about 40 g / g under a confining pressure of 4.8 kPa after 8 hours. In still another aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least about 42 g / g under a confining pressure of 4.8 kPa after 16 hours. As used herein, the term "after" means immediately thereafter. In another aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least about 24 g / g under a confining pressure of 9.6 kPa after 2 hours. In still another aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least about 27 g / g under a confining pressure of 9.6 kPa after 4 hours. In still another aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least about 30 g / g under a confining pressure of 9.6 kPa after 8 hours. In still another aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a PUP capacity of at least about 33 g / g under a confining pressure of 9.6 kPa after 16 hours.

In a preferred embodiment, the invention relates to a composition comprising absorbent cation exchange polymers containing weak acid groups in any non-neutralized form, and absorbent anion exchange polymers containing weak base groups in their non-neutralized form, wherein the mixture exhibits high absorbency of a synthetic urine solution under PUP absorption conditions within a period of time that is shorter than the duration of use (e.g., at night) of the articles comprising the present absorbent compositions. In this respect, the absorbent polymers of mixed ion exchange stratum will exhibit this enhanced absorbency when the PUP capacity is measured for a period of, for example, 2, 4, 8, and / or 16 hours. The invention also relates to absorbent members comprising the absorbent polymer compositions described above, and absorbent articles comprising these absorbent members.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of an apparatus for measuring the performance under pressure (PUP) of absorbent polymers. Figure 2 depicts an enlarged sectional view of the piston / cylinder assembly shown in Figure 1. Figure 3 graphically illustrates the PUP capability data for the absorbent polymer compositions of the present invention and the prior art, in FIG. where the PUP capacity is measured under a confining pressure of 4.8 kPa. Figure 4 graphically illustrates the PUP capacity data for the absorbent polymer compositions of the present invention and the prior art, where the PUP capacity is measured under a confining pressure of 9.6 kPa.

Figure 5 represents a schematic view of an apparatus for preparing a sample of the composition of the absorbent polymer for the measurement of the ball-breaking strength of the composition (BBS). Figure 6 represents a schematic view of an apparatus for measuring the ball-breaking strength (BBS) of an absorbent polymer composition.

DETAILED DESCRIPTION OF THE INVENTION A. Definitions As used herein, the term "body fluids" includes urine, blood, menstruation and vaginal discharges. As used herein, the term "synthetic urine solution" refers to an aqueous solution prepared by dissolving 2.0 g. of KC1, 2.0 g. of Na 2 SO 4, 0.85 of NH 4 H 2 PO 4, 0.15 g. of (NH4) 2HPO4, 0.25 g. of CaCl2.2H2O, and 0.50 g. of MgCl2.6H2O in distilled water to produce one liter of solution. As used herein, the term "ion exchange capacity" refers to the theoretical or calculated ion exchange capacity of the polymer or polymers in milli equivalents per gram assuming that each unneutralized acid or base group becomes neutralized in the exchange process ionic. As used herein, the term "absorbent polymer" refers to a polymer that is capable of absorbing within the polymer at least ten times its weight in deionized water, allowing adjustment of the pH of the system. As used herein, the term "absorbent core" refers to the component of the absorbent article that is primarily responsible for the fluid handling properties of the article, including acquiring, transporting, distributing and store body fluids. As such, the absorbent core typically does not include the topsheet or the backsheet of the absorbent article. As used herein, the term "absorbent member" refers to the components of the absorbent core that typically provide one or more of the fluid handling properties, eg, fluid acquisition, fluid distribution, fluid transportation , the storage of the fluid, etc. The absorbent member may comprise the total absorbent core or only a portion of the absorbent core, ie, the absorbent core may comprise one or more absorbent members. The improved ion exchange mixed strand absorbent polymer compositions described herein are particularly useful in absorbent members whose primary function is the storage of the body's aqueous fluids. Nevertheless, these compositions may also be present in other absorbent members. As used herein, the terms "region (s)" or "zone (s)" refers to parts or sections, in the macroscopic sense of an absorbent member. As used herein, the term "layer" refers to a part of the absorbent article whose main dimensions are along its length and width. It should be understood that the term layer is not necessarily limited to layers or sheets of simple material. In this way, the layer can be composed of laminates or combinations of several sheets or webs of the type of materials required. Accordingly, the term "layer" includes the terms "layers" and "in layers". As used herein, the term "comprising" means that various components, members, steps and the like may be used together in accordance with the present invention. Accordingly, the term "comprising" encompasses the more restrictive terms "consisting essentially of" and "consisting of", these last more restrictive terms that have their standard meaning as understood in the art. All percentages, ratios and proportions used here are by weight unless otherwise specified. All publications and references referred to herein are incorporated by reference, at least up to the point where they consist of the terms and definitions of the present disclosure.

B. Compositions of absorbent polymer of mixed stratum of ionic exchange. The present invention relates, in part, to absorbent polymer compositions of mixed ion exchange stratum which exhibit very high absorbency of the synthetic urine solution under an applied load. These mixed exchange layer absorbent polymer compositions comprise mixtures of anion exchange absorbent polymers and cation exchange absorbent polymers, as described in detail below. 1. Chemical composition a. Anion exchange absorbing polymers The anion exchange absorbing polymer or polymers containing weak base groups include a variety of water insoluble polymers, but capable of swelling in water. These are typically slightly crosslinked polymers containing a multiplicity of functional base groups, such as primary, secondary and / or tertiary amines; or the corresponding phosphines. Examples of polymers suitable for use herein include those which are prepared from polymerizable monomers which contain base groups, or groups which may be converted to base groups after polymerization. In this manner, these monomers include those containing primary, secondary and / or tertiary amines; or the corresponding phosphines. Representative monomers include, but are not limited to, ethylenimine (acyridine), allylamine, diallylamine, 4-aminobutane, alkyl oxazolines, vinylformamide, 5-aminopentene, carbodiimides, formaldazine, melamine and the like, as well as their secondary or tertiary amine derivatives . Some monomers that do not contain base groups, usually in minor amounts, may also be included in preparing the anion exchange absorbent polymers here. The absorbent polymers described herein may be homopolymers, copolymers (including terpolymers and higher order copolymers), or mixtures of different homopolymers or copolymers. The polymers can also be random, grafted or block copolymers, and can have linear or branched architectures. The polymers are made insoluble in water, but capable of swelling in water by a relatively low degree of crosslinking. This can be achieved by including an appropriate amount of a suitable crosslinking monomer during the polymerization reaction. Examples of the crosslinking monomers include N, N'-methylenebisacrylamide, ethylene glycol (meth) acrylate, trimethylolpropane tri (mef) methacrylate, triallylamine, diaciridine compounds, and the like. Alternatively, the polymers can be crosslinked after polymerization by reaction with a suitable crosslinking agent such as the di- or poly-halogenated compounds and / or the di- or poly-epoxy compounds. Examples include diiodo propane, dichloro propane, ethylene glycol diglycidyl ether, and the like. The crosslinks may be homogeneously distributed throughout the gel particle or they may be preferentially concentrated at or near the surface of the particle.

Although the anion exchange absorbing polymer is preferably of one type (ie, homogeneous), it is also possible to use anion exchange polymer blend in the present invention. For example, mixtures of cross-linked polyethylenimine and cross-linked polyaliamamine can be used in the present invention. When used as part of a mixed stratum composition of ion exchange, the anion exchange absorbent polymer part from about 50% to about 100%, preferably from 80% to about 100%, more preferably from about 90% to about 100%, in the unneutralized base form. In order to maximize the ion exchange capacity of the ion exchange mixed strand absorbent polymer composition, it is desirable that the absorbent polymer has a high ion exchange capacity per gram of dry polymer. In this way, it is preferred that the ion exchange capacity of the anion exchange absorbent polymer component be at least about 10 meq / g, more preferably at least about 15 meq / g, and most preferably at least about 20 meq / g, and most preferably at least about 20 meq / g, and most preferably at least about 20 meq / g. meq / g b. Cation Exchange Absorbent Polymer Absorbent polymers useful as the cation exchanger or exchangers typically have a multiplicity of acid functional groups such as the carboxylic acid groups. Examples of the cation exchange polymers suitable for use herein include those which are prepared from polymerizable monomers containing acid, or monomers containing functional groups which can be converted to the acid groups after the polymerization. In this manner, these monomers include olefinically unsaturated carboxylic acids and anhydrides and mixtures thereof. The cation exchange polymers may also comprise polymers that are not prepared from of olefinically unsaturated monomers. Examples of such polymers include polysaccharide-based polymers such as carboxymethyl starch and carboxymethyl cellulose, and poly (amino acid) -based polymers such as poly (aspartic acid). For a description of the poly (amino acid) absorbent polymers, see, for example, U.S. Patent No. 5,247,068, issued September 21, 1993 to Donachy et al., Which is incorporated herein by reference. Some non-acid monomers may also be included, usually in minor amounts, when preparing the absorbent polymers here. These non-acidic monomers can include, for example, monomers containing the following types of functional groups: carboxylate or sulfonate esters, hydroxy groups, amide groups, amino groups, nitrile groups, quaternary ammonium salt groups, and aryl groups, ( for example, phenyl groups, such as those derived from the styrene monomer). Other optional non-acidic monomers include unsaturated hydrocarbons such as ethylene, propylene, 1-butene, butadiene, and isoprene. These non-acidic monomers are well known materials and are described in greater detail, for example, in U.S. Patent No. 4,076,663 (Masuda et al.), Issued February 28, 1978, and in the U.S. Patent. No. 4,062,817 (Westerman), issued December 13, 1977, both of which are incorporated by reference. The olefinically unsaturated carboxylic acid and anhydride monomers include the acrylic acids typified by acrylic acid itself, methacrylic acid, α-chloroacrylic acid, α-cyanoacrylic acid, β-methylacrylic acid (crotonic acid), α-phenylacrylic acid, β-acid -acyloxypropionic, sorbic acid, chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid, β-styrylacrylic acid, itaconic acid, citroconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, tricarboxyethylene, and maleic anhydride.

Preferred cation exchange absorbing polymers contain carboxyl groups. These polymers include graft copolymers of hydrolyzed starch - acrylonitrile, partially neutralized hydrolyzed starch graft copolymers - acrylonitrile, starch graft copolymers - acrylic acid, partially neutralized starch graft copolymers - acrylic acid, hydrolyzed vinyl acetate copolymers - acrylic ester, copolymers of hydrolyzed acrylonitrile or acrylamide, lightly cross-linked copolymers of any of the above copolymers, polyacrylic acid, and polymers slightly crosslinked in the polyacrylic acid network. These polymers can be used either alone or in the form of a mixture of two or more different polymers. Examples of these polymeric materials are disclosed in U.S. Patent No. 3,661,875, U.S. Patent No. 4,076,663, U.S. Patent No. 4,093,776, U.S. Patent No. 4,666,983 and U.S. Pat. U.S. Patent No. 4,734,478. The most preferred polymeric materials for use in making the cationic exchange absorbent polymers are the lightly crosslinked polymers of the polyaryl acids and starch derivatives thereof. Cross-linking in the network makes the polymer substantially insoluble in water and, in part, determines the absorption capacity and characteristics of the extractable polymer content of the absorbent polymers. The processes for network networking these polymers and typical network crosslinking agents are described in greater detail in U.S. Patent No. 4,076,663. Although the cation exchange absorbing polymer is preferably of one type (ie, homogeneous), mixtures of cation exchange polymers can also be used in the present invention. For example, mixtures of starch-acrylic acid graft copolymers and slightly cross-linked polymers in the polyacrylic acid network can be used in the present invention.

When used as part of a mixed ion-exchange stratum composition, the cation exchange absorbent polymer ranges from about 50% to about 100%, preferably about 80% to about 100%, more preferably from about 90% to about 100%, in the form of non-neutralized acid. In order to maximize the ion exchange capacity of the ion exchange mixed strand absorbent polymer composition it is desirable that the cation exchange absorbent polymer has a high ion exchange capacity per gram of dry polymer. Thus, it is preferred that the ion exchange capacity of the cation exchange absorbent polymer component be at least about 4 meq / g, more preferably at least about 8 meq / g, even more preferably at least about 10. meq / g, and most preferably at least about 13 meq / g. c. Composition and common properties of the material The equivalents of the anionic and cation exchange capacity can be the same or different in the absorbent polymer composition of the mixed stratum of ionic exchange. For example, it may be desirable to have little more equivalent ion exchange, anionic or cationic absorbing polymer, for example, to compensate for the differences in pK, to compensate for the differences in neutralization, to alter the pH of the (eg, acidify) the urine exchanged ionically, etc. The compositions of absorbent polymer of mixed ion-exchange stratum in high concentration absorbent cores can not adhere to solution flow, stirring, etc., to help transport the ions and accelerate the rate of ion exchange. In this way it is desirable to have suitable particle morphologies to promote rapid ion exchange kinetics. Desirable morphologies include (i) aggregates of mixed stratum of particles with high surface area (by example, and / or porous) with a broad or narrow particle size distribution, (i) particles of, for example, the anion exchange absorbing polymer containing within smaller discontinuity domains of, for example, the absorbent polymer of cation exchange, and (iii) particles containing bicontinuous domains of both of the absorbent polymers of anionic and cationic exchange. The absorbent polymers may also comprise mixtures with low levels of one or more additives such as, for example, silica powder, surfactants, glues, binders and the like. The components in this mixture can be physically and / or chemically associated in a form such that the component of the absorbent polymer and the additive of the non-absorbent polymer are not easily separable physically. The absorbent polymers can be essentially non-porous (ie, have no internal porosity) or have substantial internal porosity. In the mixed layer absorbent polymer composition, the absorbent polymer of one type may have a higher crosslink density than the absorbent polymer of the other type. For the particles of the absorbent polymers useful in the present invention, the particles will generally vary in size from about 1 to about 2000 microns, more preferably from about 20 to about 1000 microns. The mass average particle size will generally be from about 20 to about 1500 microns, more preferably from about 50 microns to about 1000 microns, and even more preferably from about 100 microns to about 800 microns. An important characteristic of absorbent polymers is the level of extractables present in the polymer itself. See U.S. Patent No. 4,654,039 (Brandt et al.), Issued March 31, 1987 (reissued on April 19, 1987). 1988 as reissued patent of the United States No. 32,649), the disclosure of the which is incorporated herein by reference. Many absorbent polymers contain significant levels of extractable polymeric material that can be lexibed from the polymer matrix swollen by body fluids (eg, urine) during the period of time that body fluids remain in contact with the absorbent polymer. It is believed that this polymeric material extracted by the body fluid in this manner can alter both the chemical and physical characteristics of the body fluid to the point that the fluid is absorbed more slowly and more poorly retained by the absorbent polymer within the absorbent article. It is also believed that the extractable polymer is particularly harmful in the mixed exchange stratum absorbent polymer systems because the soluble polymer will tend to migrate towards the gel particles composed of oppositely charged polymer. The two polymers will self neutralize, thus reducing the exchange capacity of the system. Because the extractable polymer effectively comprises a polyvalent counter for the oppositely charged polymer, it can also form c crosslinks that exhibit the ability of gel to swell. Accordingly, the exchange absorbent polymers of the present invent it is preferred that the level of the extractable polymer be about 15% or less, more preferably about 10% or less, and most preferably about 7% or less, of the total polymer . 2. Physical properties a. Low Pressure Performance (PUP) The measurement of demand wettability or gravimetric absorbance can provide informatabout the ability of a high concentratzone or layer of the absorbent polymer to absorb body fluids under pressures of use. See, for example, U.S. Patent No. 5,562,646 (Goldman et al.) Issued on October 8, 1996 and the United States patent No. 5,599,335 (Goldman et al.) Issued February 4, 1997, where the wettability of demand or gravimetric absorbance is referred to as performance under pressure (PUP). In a (PUP) measurement, an absorbent polymer compositinitially dry at 100% concentratis placed in a piston / cylinder apparatus (where the bottom of the cylinder is permeable to the solut but impermeable to the absorbent polymer) under a mechanical confining pressure and it is allowed to absorb synthetic urine solutunder condit of demand absorbency in null hydrostatic suctand high mechanical pressure. The "PUP" capacity is defined as the absorptof g / g of the synthetic urine solutby a layer of 0.032 g / cm2 of the absorbent polymer, while being confined under a specific applied pressure for a particular period of time. A high PUP capacity is a critically important property for an absorbent polymer where it is used in high concentrat in an absorbent member. The pressures of use exerted on absorbent polymers include both mechanical pressures (for example, exerted by the weight and movements of the user, binding forces, etc.) and capillary pressures (for example, the capillary desorptpressure of the component or components). of acquisitin the absorbent core that temporarily retains the fluid before it is absorbed by the absorbent polymer). It is believed that a pressure of approximately 4.8 kPa reflects the sum of these pressures on the compositof the mixed stratum absorbent polymer as it absorbs the body fluids under the condit of use. However, both the upper and lower pressures can also be experienced by the absorbent polymer compositunder the condit of use. Thus, it is desirable that the exchange mixed stratum absorbent polymers of the present inventhave high PUP capacity at pressures up to about 9.6 kPa. It is preferred that the PUP capacity values Relatively high values are obtained within a period of time that is less than the duration of use (eg overnight) = of the articles comprising the absorbent compositions present. In this regard, the absorbent polymers of mixed ion exchange layer will exhibit this enhanced absorbency when measuring PUP capacity over a period of, for example, 2, 4, 8, and / or 16 hours. A method for determining the PUP capabilities of these absorbent polymers is described in the Test Methods section below. The method is based on the procedure described in U.S. Patent No. 5,562,646 (Goldman et al.) Issued October 8, 1996 (incorporated herein by reference), and is modified to last for longer periods of time under different pressures of confinements desired in order to simulate the particular conditions of use more closely. (i) PUP capacity at a confining pressure of 4.8 kPa The ion exchange mixed strand absorbent polymer compositions of the present invention are described, in one aspect, in terms of their ability to absorb synthetic urine under a pressure of 4.8 kPa confinement. In this regard, the invention relates to an ion exchange mixed stratum absorbent polymer composition, which has a performance capacity under pressure in the synthetic urine solution of at least about 30 μg under a confining pressure of 4.8 kPa. after 2 hours. Preferably, the polymer composition will have a PUP capacity in the synthetic urine solution of at least about 32 g / g, more preferably at least about 35 g / g and most preferably at least about 38 g / g after 2 hours, under a confining pressure of 4.8 kPa. Typically, the polymer composition will have a PUP capacity of about 30 g / g to about 49 g / g, more typically from about 32 g / g to about 47 g / g, even more typically from about 35 g / g to about 45 g / g, and even more typically from about 38 g / g to about 43 g / g after 2 hours, under a confining pressure of 4.8 Kpa. In a similar aspect, the present invention relates to an ion exchange mixed stratum absorbent polymer composition having a performance capacity under pressure in the synthetic urine solution of at least about 36 g / g under a pressure of 4.8 kPa confinement after 4 hours. Preferably, the polymer composition will have a PUP capacity in the synthetic urine solution of at least about 38 g / g, more preferably at least about 40 g / g and most preferably at least 42 g / g after 4 hours, under a confining pressure of 4.8 kPa. Typically, the polymer composition will have a PUP capacity of about 36 g / g to about 55 g / g, more typically from about 38 g / g to about 52 g / g, even more typically from about 40 g / g to about 50 g / g. g, and even more typically from about 42 g / g to about 48 g / g after 4 hours, under a confining pressure of 4.8 kPa. In a similar aspect, the composition of the ion exchange mixed stratum absorbent polymer will have a PUP capacity in the synthetic urine solution of at least about 40 g / g under a confining pressure of 4.8 kPa after 8 hours . Preferably, the polymer composition will have a PUP capacity of at least 42 g / g, more preferably at least about 44 g / g and most preferably at least about 46 g / g after 8 hours, under a confining pressure of 4.8 kPa. Typically, the polymer composition will have a PUP capacity of about 40 g / g to about 59 g / g, more typically about 42 g / g to about 57 g / g, even more typically from about 44 g / g to about 55 g / g, and even more typically from about 46 g / g to about 52 g / g after 8 hours, under a confining pressure of 4.8 kPa. In another similar aspect, the composition of the ion exchange mixed stratum absorbent polymer will have a PUP capacity of at least about 42 g / g under a confining pressure of 4.8 kPa after 16 hours. Preferably, the polymer composition will have a PUP capacity of at least about 44 g / g, more preferably at least about 46 g / g, and most preferably at least about 48 g / g after 16 hours, under a confining pressure of 4.8 Kpa. Typically, the polymer composition will have a PUP capacity of about 42 g / g to about 61 g / g, more typically from about 44 g / g to about 59 g / g, even more typically from about 46 g / g to about 57 g / g. , and even more typically from about 48 g / g to about 54 g / g after 16 hours, under a confining pressure of 4.8 kPa. (ii) PUP capacity under a confining pressure of 9.6 kPa The ion exchange mixed stratum absorbent polymer compositions are described separately in terms of their ability to absorb synthetic urine under a confining pressure of 9.6 kPa. Of course, it will be recognized that certain absorbent materials will exhibit the absorbency properties described in both 4.8 kPa and 9.6 kPa. In this respect, the invention relates to an ion exchange mixed stratum absorbent polymer composition having a capacity of PUP, after 2 hours, of at least about 24 g / g under a pressure of confinement of 9.6 kPa. Preferably, the polymer composition will have a PUP capacity after 2 hours of at least about 26 g / g, more preferably at least about 28 g / g and most preferably at least about 30 g / g, under a confining pressure. 9.6 kPa. Typically, the polymer composition will have a PUP capacity after 2 hours from about 24 g / g to about 40 g / g, more typically from about 26 g / g to about 38 g / g, even more typically from about 28 g / g. approximately, and even more typically from about 30 g / g to about 35 g / g, under a confining pressure of 9.6 kPa. In a similar aspect, the ion exchange mixed stratum absorbent polymer composition will have a PUP capacity after 4 hours, of at least 27 g / g under a confining pressure of 9.6 kPa. Preferably, the polymer composition will have a PUP capacity after 4 hours of at least about 29 g / g, more preferably at least about 32 g / g and most preferably at least about 35 g / g, under a confining pressure. 9.6 kPa. Typically, the polymer composition will have a PUP capacity after 4 hours from about 27 g / g to about 46 g / g, more typically from about 29 g / g to about 44 g / g, even more typically from about 32 g / g. about 45 g / g, and still more typically from about 35 g / g to about 40 g / g, under a confining pressure of 9.6 kPa. In a similar aspect, the ion exchange mixed stratum absorbent polymer composition will have a PUP capacity, after 8 hours, of at least about 9.6 kPa. Preferably, the polymer composition will have a PUP capacity after 8 hours of at least about 32 g / g, more preferably at least about 35 g / g, and most preferably at least about 37 g / g, under a confining pressure of 9.6 kPa. Typically, the polymer composition will have a PUP capacity after 8 hours from about 30 g / g to about 49 g / g., more typically from about 32 g / g to about 47 g / g, still more typically from about 35 g / g to about 45 g / g, and even more typically from about 37 g / g to about 43 g / g, under a confinement pressure of 9.6 kPa. In another similar aspect, the ion exchange mixed stratum absorbent polymer composition will have a PUP capacity, after 16 hours, of at least about 33 g / g under a confining pressure of 9.6 kPa. Preferably, the polymer composition will have a PUP capacity after 16 hours of at least about 35 g / g, more preferably at least about 38 g / g and most preferably at least about 40 g / g, under a confining pressure. 9.6 kPa. Typically, the polymer composition will have a PUP capacity after 16 hours from about 33 g / g to about 52 g / g, more typically from about 35 g / g to about 50 g / g, even more typically from about 38 g / g. about 48 g / g, and still more typically from about 40 g / g to about 45 g / g, under a confining pressure of 9.6 kPa. b. Permeability of the zone or layer comprising the absorbent polymer. An important property of the zones or layers comprising the absorbent polymers is their permeability to the fluid. In a member or absorbent article, it directly affects the capacity of a material, such that the layer comprising the swollen absorbent polymer transports body fluids away from the body. acquisition region to an acceptable regime. The permeability / flow conductivity can be defined in terms of the saline flow conductivity (SFC), which is a measure of the ability of a material to transport the saline fluid. An absorbent polymer is considered to have the desired permeability properties if its SFC value is about 30 x 10-7 cm3 sec / g. A method for measuring saline flow conductivity is described in U.S. Patent No. 5,562,646 (Goldman et al.) Issued October 8, 1996. This method is modified to account for the deflation of the gel bed during measurement of the mixed layer, ion exchange absorbent polymers, as described in the Test Methods section below. Without being bound by theory, it is believed that during the SFC measurement of the ion exchange, mixed stratum absorbent polymers, the polymer sample continues to exchange ions from the saline solution. Finally, the ion exchange capacity of the absorbent polymer is exceeded, and the ionic strength of the solution surrounding the swollen polymer increases, resulting in some deflation of the gel bed. The amount of the fluid that is expressed from the gel as a result of this deflation is small with the amount of fluid flowing through the gel bed during the measurement of the SFC. Because the final thickness of the gel bed is significantly less than the initial thickness, the final thickness of the gel bed is used to calculate the SFC values. By using the final thickness of the gel bed in the calculation, the minimum SFC obtained during the measurement is provided. Using the initial thickness or an intermediate thickness of the gel bed will provide even higher SFC values. The absorbent polymer compositions of the present invention will preferably, but not necessarily, have an SFC value of at least about 30 x 10-7 cm3 sec / g, more preferably at least about 50 x 10-7 cm3 sec / g , and even more preferably at least approximately 70 x 10-7 cm3 sec / g. Typically, the absorbent polymers of the present invention will have an SFC value of from about 30 to about 100 x 10-7 cm3 sec / g, more typically from about 50 to about 90 x 10-7 cm3 sec / g, and even so more typical from about 70 to about 80 x 10-7cm3sec / g. c. Porosity of the zone or layer comprising the absorbent polymer Another important feature of the ion exchange, mixed stratum absorbent polymers of the present invention is the aperture or porosity of the zone or layer comprising the absorbent polymers when they swell. Polymers in body fluids under confining pressure. It is believed that when the absorbent polymers useful herein are present in high concentrations in an absorbent member or absorbent article and then swell under use pressures, the boundaries of the particles coming into contact, the interstitial voids in this high concentration region generally arrive to be bound by the swollen polymer. When this occurs, it is believed that the opening or porosity properties of this region are generally reflective of the porosity of the zone or layer formed from the swollen absorbent polymer alone. As used herein, the term "porosity" means the fractional volume (without dimension) that is not occupied by the solid material. See J.M. Coulson et al., Chemical Engineering, volume 2, third edition, Pergamon Press, 1978, page 126. Porosity is an effective measure of the capacity of the area or layer comprising the swollen absorbent polymer to remain open to be capable of acquiring and distribute body fluids under pressures of use. It is believed that increasing the porosity of swollen regions of high concentration can provide superior absorption and fluid handling properties for the core. absorber, thus reducing leakage incidents, especially at high fluid loads. Desirably, the porosity of the zone or layer comprising the swollen absorbent polymer approximates or even exceeds the porosity of conventional acquisition / distribution materials such as wood pulp fluff. See, U.S. Patent No. 5,562,646, issued October 8, 1996 to Goldman et al. d. Integrity of the zone or layer comprising the absorbent polymer Another important factor affecting the transport of the fluid in an absorbent member is the integrity of the region or regions comprising these polymers. This region or regions having the high concentration of the absorbent polymer should have sufficient integrity in a partially wet and / or wet state such that physical continuity (and thus the ability to acquire and transport the fluid to and through the contiguous interstitial / capillary voids) of the absorbent member are not substantially interrupted or altered when subjected to normal conditions of use. During normal use, the absorbent cores in the absorbent articles are typically subjected to varying tensile and torsional strengths and direction. These tensile and torsional forces include stacking in the crotch area, stretching and twisting forces as the person wearing the absorbent article walks, bends, bends, and the like. If the wet integrity is inadequate, these tensile and torsional forces can potentially cause a substantial alteration and / or disruption in the physical continuity of the absorbent member in such a way that its ability to acquire and transport fluids into and through the gaps and contiguous capillaries is degraded. The layer comprising the absorbent polymer may be partially separated, be completely separate, have gaps or spaces introduced, have areas that are significantly thin and / or be fractionated into a plurality of segments significantly lower This alteration can minimize or completely negate any of the advantageous porosity and permeability / flow conductivity properties of the absorbent polymer. The good integrity of the zone or layer comprising the absorbent polymer according to the present invention can be obtained by various designs, configurations, compositions, etc., in the absorbent member having the high concentration of the absorbent polymer, the other components in the absorbent core (e.g., fluid acquisition member), the other components in the absorbent article (e.g., top sheet and / or backsheet) or any combination of these components. See U.S. Patent No. 5,562,646, issued October 8, 1996 to Goldman et al. In preferred mixed layer ion exchange systems, the cation exchange component and the anion exchange component tend to adhere to each other. Without being bound by theory it is believed that this is due to the opposite charged poly-ions and / or the acid / base species on the surface of the polymeric particles of the gel which are inherently attracted towards the oppositely charged species in the particles adjacent. This causes a three-dimensional network of adherent polymeric particles that are established in the zone or layer comprising the absorbent polymer, thereby greatly increasing the integrity of this zone or layer. The integrity of the region or regions comprising the polymer compositions of the present invention can be measured using the ball rupture resistance (BBS) test described below. The breaking strength of the ball is the force (grams force) required to break a layer of an absorbent polymer composition that swells in synthetic urine. The absorbent polymer compositions of the present invention preferably, although they will not necessarily have a BBS value of at least about 50 gf, more preferably at least about 100 gf, still more preferably at least about 150 gf and still more preferably at least about 200 gf. Typically, the BBS values will vary from about 50 to about 1000 gf, more typically from about 100 to about 800 gf, even more typically from about 150 to about 400 gf and very typically from about 200 to about 300 gf. 3. Methods for making absorbent polymers. The absorbent polymers useful in the mixed ion exchange stratum compositions of the present invention can be formed by any of the polymerization and / or crosslinking techniques. Typical processes for producing these polymers are described in U.S. Pat. No. 32,649 (Brand et al.), Issued April 19, 1988, U.S. Patent No. 4,666,983 (Tsubakimoto et al.), Issued on 19 May 1987, and in U.S. Patent No. 4,625,001 (Tsubakimoto et al.), issued November 25, 1986, all of which are incorporated by reference. Polymerization methods for preparing the ion exchange polymers useful in the present invention may include free radial, ring opening, condensation, anionic, cationic or irradiation techniques. The polymer can be prepared in a neutralized, partially neutralized or unneutralized form, even when the desired product is not neutralized. The absorbent polymer can be prepared using a homogeneous solution polymerization process, or multi-phase polymerization techniques such as reverse emulsion or suspension polymerization processes.

The crosslinking can be carried out during the polymerization by the incorporation of suitable crosslinking monomers. Alternatively, the polymers can be crosslinked after polymerization by reaction with a suitable reactive crosslinking agent. Cross-linking on the surface of the initially formed polymers is a preferred process for obtaining absorbent polymers having the capacity of relatively high PUP, porosity and permeability. Without being bound by theory, it is believed that cross-linking on the surface increases the resistance to deformation of the surfaces of the swollen particles of the absorbent polymer, thereby reducing the degree of contact between nearby polymer particles when the particles are deformed. swollen from the polymer under external pressure. Absorbent polymers crosslinked on the surface have a higher level of crosslinking in the vicinity of the surface than in the interior. As used here, "surface" describes the boundaries that give out of the particle. For porous absorbent polymers (eg, porous particles, etc.), the exposed internal limits may also be included. For a higher level of crosslinking at the surface, it is implied that the level of the functional lattices for the absorbent polymer in the vicinity of the surface is generally higher than the level of the functional lattices for the polymer in the interior. The graduation in reticular from the surface to the interior can vary, both in depth and in profile. A number of processes for introducing surface gratings are disclosed in the art. Suitable methods for surface crosslinking include those where (i) a di or poly functional reagent or reagents capable of reacting with the functional groups existing within the absorbent polymer are applied to the surface of the absorbent polymer; (ii) a di or poly functional reagent which is capable of reacting with other added reagents and possibly with the functional groups existing within the absorbent polymer such as to increase in the level of crosslinking towards surface is applied to the surface (for example, the addition of the monomer plus the crosslinker at the initiation of a second polymerization reaction); (iii) no additional poly functional reagents are added, but additional reaction or reactions are induced between the components existing within the absorbent polymer either during or after the primary polymerization process such as to generate a higher level of crosslinking at or near surface (for example, suspension polymerization processes where the crosslinker is inherently present at higher levels near the surface); and (iv) other materials are added to the surface to induce a higher level of crosslinking or otherwise reduce the surface deformability of the resulting swollen polymer. Suitable general methods for carrying out cross-linking on the surface of the absorbent polymers according to the present invention are disclosed in U.S. Patent No. 4,541,871 (Obayashi), issued September 17, 1985; published PCT application WO92 / 16565 (Stanley), published on the 1st. October 1992; published PCT application WO90 / 08789 (Tai), published August 9, 1990; published PCT application WO93 / 05080 (Stanley), published March 18, 1993; U.S. Patent No. 4,824,901 (Alexander), issued April 25, 1989; U.S. Patent No. 4,789,861 (Johnson), issued January 17, 1989; U.S. Patent No. 4,587,308 (Makita), issued May 6, 1986; U.S. Patent No. 4,734,478 (Tsubakimoto), issued March 29, 1988; U.S. Patent No. 5,164,459 (Kimura et al.), issued November 17, 1992; German patent application published 4,020,780 (Dahmen), published on August 29, 1991; and published European patent application 509,708 (Gartner), published October 21, 1992; all of which are incorporated here by reference. For cationic absorbent polymers, suitable di or poly functional crosslinking reagents they include di / poly / haloalkanes, di / poly-epoxides, di / poly-hydrochloric acid, di / poly-tisuk akjabism di / poly-aldheidos, di / poly-acids, and the like.

O Test Methods 1. Baio Pressure Performance Capability (PUP) This test is based on the method described in U.S. Patent No. 5,599,335 (Goldman et al.) Issued February 4, 1997. This test determines the amount of the synthetic urine solution absorbed by the absorbent polymer (including mixed strand absorbent polymer compositions, ion exchange) which are laterally confined to a piston / cylinder assembly under a confining pressure for example of 4.8 kPa or 9.6 kPa. The purpose of the test is to evaluate the ability of the absorbent polymer layer to absorb body fluids, over a period of time comparable to the duration of use (e.g., overnight) of the articles comprising the absorbent compositions (eg. example, 1, 2, 4, 8 or 16 hours), when the polymers are present in high concentrations in an absorbent member and exposed to pressures of use. The pressures of use against which an absorbent polymer is required to absorb the fluid include mechanical pressures resulting from the weight and / or movements of the user, mechanical pressures resulting from resilient and clamping systems, and pressures. of hydrostatic desorption of the layers and / or adjacent members. The test fluid for the PUP capacity test is the synthetic urine solution. This fluid is absorbed with the absorbent polymers under conditions of absorption of demand at a hydrostatic pressure close to zero. A convenient apparatus for this test is shown in Figure 1. At one end of this apparatus is a fluid reservoir 712 (such as a Petri dish) which it has a cover 714. The deposit 712 rests on an analytical balance indicated generally as 716. The other end of the apparatus 710 is an agglomerated funnel generally indicated as 718., a piston / cylinder assembly generally indicated as 720 which fits inside the funnel 718, and the cap of the agglomerated plastic cylindrical funnel generally indicated as 722 which fits over the funnel 718 and is open at the bottom and closed at the top, having the upper part a tiny hole. The apparatus 710 has a system for transporting the fluid either in the direction consisting of the sections of the capillary tube of the glass indicated as 724 and 731a, flexible plastic tube (for example Tygon® tube of% inch internal diameter and 3 / 8 inch external diameter) indicated as 731b, 726 and 738 stopcock assemblies and Teflon® 748, 750 and 752 connectors for connecting 724 and 731a glass tubes and 726 and 738 stopcock assemblies. The stopcock assembly 726 consists of a three-way valve 728, glass capillary tube 730 and 734 in the main fluid system, and a glass capillary tube section 732 for refilling the reservoir 712 and ejecting by jet. the agglomerated disc in the agglomerated funnel 718. The stopcock assembly 738 consists of a similar way of a three-way valve 740, glass capillary tubes 742 and 746 in the main fluid line, and a section of glass capillary tube 744 that It acts as a drain for the system. Referring to Figure 1, the assembly 720 consists of a cylinder 744, a cup-shaped piston indicated by 756 and a weight 758 that fits inside the piston 753. Attached to the lower end of the cylinder 754 is a screen 759 that you see the stainless steel mesh no. 400 which is bi-axially extended to extend before attaching. An absorbent polymer composition indicated generally as 760 rests on screen 759. Cylinder 754 is drilled by a transparent LEXAN® rod (or equivalent) and has an internal diameter of 6.00 cm (area = 28.27 cm2), with a wall thickness of approximately 5 mm and a height of approximately 5 cm. The piston 756 is in the form of a cup of Teflon® or Kel-F® and is machined to fit within the cylinder 754 with an annular tolerance between the cylinder and the piston of between 0.114 mm and 0.191 mm. The cylindrical weight of stainless steel 758 is machined to fit snugly within the piston 756 and is adjusted with a handle on top (not shown) for ease of removal. For a confining pressure of 4.8 kPa (0.7 psi), the combined weight of piston 756 and weight 758 is 1390 g, which corresponds to a pressure of 4.8 kPa (0.7 psi) for an area of 28.27 cm2. For a confining pressure of 9.6 kPa (1.4 psi), the combined weight of piston 756 and weight 758 is 2780 g. The components of the apparatus 710 are sized so that the flow velocity of the synthetic urine through the former, under a hydrostatic height of 10 cm, is at least 36 grams per hour per square centimeter of the agglomerated disk in the agglomerated funnel 718. The particularly striking factors in the flow velocity are the permeability of the agglomerated disk in the agglomerated funnel 718 and the internal diameters of the glass tubes 724, 730, 742, 746 and 731a and the valves of the valves 728 and 740. The reservoir 712 is placed on an analytical balance 716 that is accurate to at least 0.01 g with a current of less than 0.1 g / hr. The scale is preferably interfaced to a computer with software that can (i) inspect the weight change on the balance at pre-set time intervals from the initiation of the PUP test and (¡i) be adjusted to auto-start the acquisition of data when a weight change of 0.01-0.05 g occurs, depending on the sensitivity of the balance. The capillary tube 724 that enters the reservoir 712 should not be in contact with either the bottom of the anterior or the cover 714. The fluid volume (not shown) in the reservoir 712 should be sufficient such that the air is not extract in the tubes 724 capillaries during the measurement. The fluid level in reservoir 712, at the start of the measurement, should be approximately 2 mm. below the upper surface of the agglomerated disc in the agglomerated funnel 718. This can be confirmed by placing a small drop of fluid in the agglomerated disc and gravimetrically inspecting the flow of this amount of fluid back to the reservoir 712. This level should not to change significantly when the piston / cylinder assembly 720 is placed inside the funnel 718. The reservoir should have a sufficiently long diameter (eg, approximately 14 cm) for the removal of the approximately 40 ml portions to result in a change in the height of the fluid of less than 3 mm. Prior to the measurement, the assembly is filled with the synthetic urine solution and the agglomerated disk in the agglomerated funnel 718 is jetted out in such a way that it is filled with the fresh synthetic urine solution. To the extent possible, water bubbles are removed from the bottom surface of the agglomerated disc and from the system that connects the funnel to the reservoir. In the following procedures they were carried out by sequential operation of three-way stopcocks: 1.- Excess fluid is removed on the upper surface of the agglomerated disk (for example, emptying) of the agglomerated funnel 718. 2.- The Weight / height of the tank solution 712 is adjusted to its own value / level. 3. The agglomerated funnel 718 is placed at the correct height relative to the tank 712. 4. The agglomerated funnel 718 is then covered with the cover of the agglomerated funnel 722. 5. The deposit 712 and the agglomerated funnel 718 are balanced with the valves 728 and 740 of the keyway assemblies 726 and 738 in the open connection position. 6. - The valves 728 and 740 are then closed. 7.- To the valve 740 then it is rotated in such a way that the funnel is open to drain tube 744. 8.- The system is allowed to equilibrate in this position for 5 minutes. 9. The valve 740 is then returned to its closed position. The steps numbers 7-9 temporarily "dry" the surface of the agglomerated funnel 718 by exposing it to a small hydrostatic suction of approximately 5 cm. This suction is applied if the open end of the tube 744 extends approximately 5 cm below the level of the agglomerated disc in the agglomerated funnel 718 and is filled with synthetic urine. Typically, about 0.2 g of fluid is drained from the system during this procedure. This method prevents the premature absorption of synthetic urine when the piston / cylinder assembly 720 is placed inside the agglomerated funnel 718. The amount of fluid that is drained from the agglomerated funnel in this process (so-called agglomerate funnel correction weight) is measured driving the PUP test (see below) for a period of 15 minutes without the piston / cylinder 720 assembly. Essentially all the fluid drained from the agglomerated funnel by this process is reabsorbed very quickly by the agglomerate when started the proof. Thus, it is necessary to subtract this correction weight from the weights of the fluid removed from the reservoir during the PUP test (see below). The absorbent polymer composition 760 is dried by suitable methods, for example by high vacuum desiccation at an appropriate temperature for a sufficient period of time, to reduce the level of moisture and / or other solvents in the sample as much as possible. The final residual moisture level, as determined by an appropriate technique such as Karl Fischer titration or analysis thermogravimetric, should be less than about 5%, and preferably less than about 3%. Cylinder 754 is added approximately 0.9g (Wap) of absorbent polymer composition 760 (corresponding to a basis weight of 0.032 g / cm2) and evenly distributed over screen 759. If the absorbent polymer composition comprises more than one particle type, the particles are mixed uniformly throughout the composition. Care is taken to prevent the absorbent polymer 760 from adhering to the inner walls of the cylinder 754. The piston 756 travels inside the cylinder 754 and is placed on the surface of the absorbent polymer 760, while ensuring that the piston can slide freely. inside the cylinder. The piston can be rotated smoothly to assist in the distribution of the absorbent polymer. The piston / cylinder assembly 720 is positioned at the top of the agglomerated portion of the funnel 718, the weight 758 is displaced towards the piston 756, and the upper part of the funnel 718 is then covered with the agglomerated funnel cover 722. After that the reading of the balance has been checked for stability, the test is started by opening valves 728 and 740 to connect funnel 718 and reservoir 712. With autoinitiation, the data collection begins immediately, while funnel 718 starts to reabsorb the fluid. The weight of the remaining fluid in reservoir 712 is recorded at frequency intervals for the duration of the test. The capacity of PUP at any given time, t, is calculated as follows: PUP capacity (g / g; t) = (Wr (t = 0) - Wr (t) - Wfc) / Wap where Wr (t = 0 ) is the weight in grams of deposit 712 before initiation. Wr (t) is the weight in grams of the deposit in the elapsed time (for example, 1, 2, 4, 8 or 16 hours), Wfo is the weight correction in grams of the agglomerated funnel (measured separately), and Wapes is the dry weight in grams of the absorbent polymer. 2. Ball rupture resistance test (BBS) This test determines the ball rupture strength (BBS) of an absorbent polymer composition. The BBS is the force (maximum load, in grams force or "gf") required to break a layer of an absorbent polymer composition that swells in the synthetic urine solution, under the procedures specified in the Test Method. The BBS is a measurement of the integrity of a layer of the absorbent polymer composition in the swollen state. An apparatus suitable for the measurement of BBS is shown in Figure 5. This apparatus comprises an internal cylinder 270 which is used to contain an absorbent polymer layer 260, and outer cylinder 230, a flat bottomed tray of Teflon 240, an cylinder inner cover plate 220, and a stainless steel 210 weight. Internal cylinder 270 is drilled from a transparent Lexan® rod or equivalent, and has an internal diameter of 6.00 cm (area equal to 28.27 cm2), with a wall thickness of approximately 0.5 cm, and a height of approximately 1.50 cm. The outer cylinder 230 is drilled from an equivalent Lexan® rod, and has an internal diameter that is slightly larger than the outer diameter of the inner cylinder 270, such that the inner cylinder 270 fits inside the outer cylinder 230 and moves freely . The external cylinder 230 has a wall thickness of approximately 0.5 cm, and a height of approximately 1.00 cm. The lower part of the outer cylinder 230 is covered with a stainless steel mesh screen 250 which is biaxially stretched for attention before fixing. The cover plate of the inner cylinder 220 is made of a glass plate with a thickness of 0.8 cm and a weight of 500 gr. The 210 stainless steel weight has a weight of 1700 gr. The voltage tester with a rupture test load cell (available from the Intelect-II-STD voltage tester, made by Thwing-Albert Instrument Co., Pennsylvania) is used for this test. With reference to Figure 6, this The instrument integrates a force-sensitive load cell 330 equipped with a polished stainless steel ball-shaped probe 290, a mobile cross-piece 320, a fixed cross-piece 310, a circular lower stage 280, a top holding stage 300 which is used to hold the sample 260 pneumatically. The lower clamping plate 280 is mounted on the fixed crossarm 310. Both of the lower clamping plate 280 and the upper clamping plate 300 have a diameter of 115 mm, a thickness of 2.9 mm, and a circular aperture of 18.65 mm. diameter. The polished stainless steel ball-shaped probe 290 has a diameter of 15.84 mm. During the BBS test procedure, the mobile crosshead 320 moves upwards, causing the probe 290 to contact and penetrate the sample 260. When the probe 290 penetrates the sample 260, the complete test is considered, and the Record the appropriate data. Referring to the sampling apparatus illustrated in Figure 5, the inner cylinder 270 is inserted into the outer cylinder 230. A 1.0 g sample is added. from the absorbent polymer composition to the inner cylinder 270 and is evenly dispersed over the 400 250 mesh stainless steel screen. The cylinders assembled with the absorbent polymer are transferred to the flat bottom tray of Teflon® 240, and the plate is placed of inner cylinder cover 220 on inner cylinder 270. An aliquot of 30.0 ml of the synthetic urine solution is emptied into the flat bottom tray of Teflon® 240. The synthetic urine solution passes through the steel screen and it is absorbed by the absorbent polymer composition 260. The steel weight 210 is placed on the cover plate of the inner cylinder 220 five minutes after the addition of the fluid. After an additional 25 minutes, the stainless steel weight 210 and the cover plate of the inner cylinder 220 are removed. For the procedure to be valid, all the synthetic urine solution must be absorbed by the absorbent polymer composition at this point. The internal cylinder 270 with the layer of The swollen absorbent polymer 260 is immediately transferred to the rupture tester for the measurement of the BBS. Referring to the rupture tester illustrated in Figure 6, the inner cylinder 270 with the swollen layer of the absorbent polymer 260 is centrally placed on the lower clamping plate 280 and is fixed pneumatically with the upper clamping plate 300. The measurement a sensitivity to rupture of 10.00 gr. and a test speed of 5 inches per minute. The measurement is started and the crosshead 320 is moved up until the polished stainless steel ball-shaped probe 290 penetrates the gel layer of the absorbent material 260. A breakdown of the sample is then recorded, moving the crosshead 320 back to the your starting position. The BBS is expressed as the maximum load in grams force. The average of three determinations is reported as the BBS for the absorbent polymer composition. D. Absorbent members The absorbent members according to the present invention will comprise the ion-exchange mixed stratum absorbent polymer compositions, described above, with or without other optional components such as fibers, thermoplastic material, etc. Preferred materials are described in detail in column 23, line 13, to column 29, line 16, of U.S. Patent No. 5,562,646 (Goldman et al.). These absorbent members comprising these absorbent polymers can function as fluid storage members in the absorbent core. The main function of these fluid storage members is to absorb the discharged body fluid either directly or from other absorbent members (e.g., fluid acquisition / distribution members) and then retain these fluids, even when subjected to pressures. usually found as a result of the user's movements. However, it must be It should be understood that these absorbent members containing polymer can serve functions other than fluid storage. In a preferred embodiment, the absorbent members according to the present invention will contain one or more regions having relatively high concentrations of these absorbent polymers. In order to provide relatively thin absorbent articles capable of absorbing and retaining large amounts of body fluids, it is desirable to maximize the level of these absorbent polymers and to minimize the level of other components, in particular fibrous components. To use these absorbent polymers in relatively high concentrations, however, it is important that these polymers have a relatively high absorbency capacity under a relatively high confining pressure (ie PUP capacity) and preferably a relatively high permeability under pressure. (that is, SFC). This is in such a way that the polymer, when swollen in the presence of body fluids, provides adequate capability to acquire these discharged fluids in the body and then transport these fluids through the zone or layer with relatively high gel concentration to other regions of the absorbent member and / or the absorbent core and / or then store these body fluids. When measuring the concentration of the mixed strand absorbent polymer composition, ion exchange, in a given region of an absorbent member, the weight percent of the absorbent polymer is used relative to the combined weight of the absorbent polymer and any other components (e.g., fibers, thermoplastic material, etc.) that are present in the region containing the polymer. With this in mind, the concentration of the absorbent polymer composition mixed layer, ion exchange, in a given region of an absorbent member of the present invention will typically be in the range of about 40 to 100%, of about 50 to 100%, about 60 to 100%, about 70 to 100%, about 80 to 100%, about 90% to 100%. Of course, in general, the relative concentration of the upper absorbent polymer, the thinner and less bulky absorbent member. E. Absorbent Cores and Absorbent Articles The mixed-strand, ion-exchange absorbent polymer compositions of the present invention can be used exactly like conventional absorbent polymers in any absorbent core and / or absorbent article used for absorbing body fluids as they are described in U.S. Patent No. 5,562,646 (Goldman et al.). The 5,562,646 patent discloses absorbent cores in detail in column 33, line 7, to column 52, line 24; and describes absorbent articles in detail in column 52, line 25, to column 54, line 9. These articles include diapers, catamenial products and / or adult incontinence products. The substitution of the mixed layer, ion exchange absorbent polymers by the conventional absorbent polymers in the same weight will allow the increased absorbent capacity of the article. Alternatively, absorbent polymers of mixed stratum, ion exchange, can be substituted at a lower weight so as not to increase the absorbent capacity of the article, but allow a lighter, thinner and / or less bulky article. The incorporation of the ion exchange mixed stratum absorbent polymers into any of the previously disclosed absorbent articles is obvious to one skilled in the art. These products include those features, for example, such as breathable backsheets, hook and loop fasteners, two-component fiber matrices, and the like. The absorbent articles that may contain the ion exchange, mixed stratum absorbent polymer compositions described herein are disclosed, for example, in U.S. Patent No. 3,224,926 (Bemardin), issued December 21, 1965; U.S. Patent No. 3,440,135 (Chung), issued April 22, 1969; U.S. Patent No. 3,932,209 (Chatterjee), issued January 13, 1976; and in U.S. Patent No. 4,035,147 (Sangenis et al.), issued July 12, 1977. Most preferred hardened fibers are disclosed in U.S. Patent No. 4,822,453 (Dean et al.), issued in April 18, 1989; U.S. Patent No. 4,888,093 (Dean et al.), issued December 19, 1989; U.S. Patent No. 4,898,642 (Moore et al.), issued February 6, 1990; and in U.S. Patent No. 5,137,537 (Herrow et al.), issued August 11, 1992; U.S. Patent No. 4,818,598 (Wong) issued April 4, 1989; U.S. Patent No. 5,562,646 (Goldman et al.) issued October 8, 1996; U.S. Patent No. 5,217,445 (Young et al.), issued June 8, 1993; U.S. Patent No. 5,360,420, (Cook et al.), issued on the 1st. November 1994; U.S. Patent No. 4,935,022 (Lash et al); U.S. Patent Application Serial No. 08 / 153,739 (Dragoo et al.), filed on November 16, 1993; U.S. Patent Application Serial No. 08 / 164,049 (Dragoo et al.), filed December 8, 1993; U.S. Patent No. 4,260,443 (Lindsay et al); U.S. Patent No. 4,467,012 (Pedersen et al.), issued August 21, 1984; U.S. Patent No. 4,715,918 (Lang), issued December 29, 1987; U.S. Patent No. 4,851,069 (Packard et al.), issued July 25, 1989; U.S. Patent No. 4,950,264 (Osborn), issued August 21, 1990; U.S. Patent No. 4,994,037 (Bemardin), issued February 19, 1991; U.S. Patent No. 5,009,650 (Bernardin), issued April 23, 1991; U.S. Patent No. 5,009,653 (Osborn), issued April 23 of 1991; U.S. Patent No. 5,128,082 (Makoui), July 7, 1992; U.S. Patent No. 5,149,335 (Kellenberger et al.), issued September 22, 1992; and in U.S. Patent No. 5,176,668 (Bernardin), issued January 5, 1993; U.S. Patent Application Serial No. 141, 156 (Richards et al.), filed October 21, 1993; U.S. Patent No. 4,429,001 (Kolpin et al.), issued January 31, 1984; U.S. Patent Application Serial No. 07 / 794,745 (Aziz et al.) filed on November 19, 1991; all of which are incorporated by reference. F. Specific Examples A lightly cross-linked, partially neutralized poii (acrylic acid) absorbent polymer with a high relative PUP capacity (approximately 4.8 kPa to -33 g / g, 60 minutes) is obtained from Chemdal Corporation of Palantine, Illinois ( ASAP-2300, lot No. 426152). (Similar samples of ASAP-2300 are available from The Procter &Gamble Co., Paper Technology Division, Cincinnati, OH). This material serves as a control sample and is referred to herein as "Control Sample". A sample of absorbent polymer that provides increased integrity relative to conventional absorbent polyacrylate polymers is obtained from Nippon Shokubai (lot # TN37408). This is a polyacrylate that is surface treated with polyethyleneimine. 53642. The polymer is described in detail in U.S. Patent No. 5,382,610, filed January 17, 1995. This material is referred to herein as "the ST sample." Example 1: Preparation of the ion exchange absorbent polymers (i) Absorbent cation exchange polymer To prepare the cation exchange absorbent polymer, a portion of the control sample is screened with a standard 50 mesh screen from the United States of America series to remove particles that are larger than about 300 microns in diameter. Approximately 50 grams of the sieved absorbed polymer with particle size of less than about 300 microns is converted to the acid form by suspending the polymer in a dilute hydrochloric acid solution which is prepared by adding about 46.5 g. of concentrated hydrochloric acid (Baker; HCl from 36.5 to 38%) in approximately 900 ml of deionized water. The suspension is shaken gently for about 1.5 hours, after which the absorbent polymer was allowed to settle, and the supernatant fluid was removed by decanting. The decanted liquid is replaced by an equal volume of deionized distilled water, the suspension is gently stirred for about 1 hour, and the absorbent polymer is allowed to settle, and the supernatant fluid is again removed by decanting. This exchange process is repeated (approximately 8 times) with an equal volume of deionized destined water until the pH of the supernatant reaches 5-6. The exchange process is then repeated three times with isopropanol (reagent grade: VWR, West Chester, PA). Three times with acetone (reagent grade; VWR), and once with anhydride ether (reagent grade; EM Science, Gibbstown, NJ). The product is spread gently on a polytetrafluoroethylene sheet and allowed to dry overnight. After gentle manual interruption with a spatula, the product is dried under high vacuum for 96 hours at room temperature to remove any residual solvents. The sample is sifted through a 20 mesh screen of the United States of America to remove any of the large particles or agglomerates. Approximately 30 grams of the ion exchange absorbing polymer of po (i) is obtained acrylic), cross-linked, in acid form, and stored under a dry atmosphere (PAA sample). (ii) Anion exchange absorbing polymer The branched polyetherezine with a nominal weight average molecular weight of 750,000 g / mole is obtained as a 50% aqueous solution from Aldrich Chemical Co., Milwaukee, Wisconsin (catalog number 18,917-8; lot number 12922PQ). A 20-gram sample of this solution is further diluted with 37 grams of distilled water and stirred for 30 minutes in a 250-ml beaker to obtain complete dissolution. Ethylene glycol diglycidyl ether (50% solution), 2.14 grams (Aldrich Chemical Co., catalog number E2.7209-3, lot number 07405DN), is added to the polyethylenimine solution and the mixture is stirred at room temperature. approximately 2 minutes before being placed in a ventilated oven at approximately 65 ° C for three hours. The resulting gel is allowed to cool and then breaks into pieces of approximately 1 to 5 mm in diameter. The mixture is then transferred to a 4000 mL beaker containing two liters of distilled water and stirred gently overnight. The excess water is decanted and the remaining sample is dried under high vacuum for about 96 hours to produce a slightly cross-linked polyethylene imine anion exchange absorbing polymer, which is stored under a dry atmosphere (BPEI sample). (iii) Mixed layer, ion exchange absorbent polymer The cross-linked polyethylenimine anion exchange absorbing polymer (BPEI sample) is cryogenically milled and sieved under an atmosphere of dry nitrogen. A fraction of the particle size that passes through the 25 mesh screen of the standard series of the United States of America is placed, but not through a 70 mesh screen of the standard series of the United States of America (it is say, a fraction with particles on the scale of approximately 200 to 700 microns in diameter). Approximately equal weights of the cross-linked poly (acrylic acid) cation exchange absorbent polymer are mixed together, sieved (PAA sample) and cross-linked polyethylenimine anion exchange absorbent polymer, sieved (BPEI sample) to distribute the particles of each type of polymer uniformly throughout the mixture. This mixture comprises an ion exchange, mixed stratum absorbent polymer composition (sample MB-1) of the present invention. (iv) PUP capacity measurements Approximately 0.9 grams of the ion exchange, mixed stratum absorbent polymer composition (sample MB-1) is transferred to a PUP cylinder (as described in the Test Methods section). above), and spread gently over the total area of the screen that comprises the base of the cylinder. Capacities of PUP are determined in separate samples under confining pressures of 4.8 and 9.6 kPa, with the amount of fluid absorbed measured at frequency intervals over a period of 16 hours. The PUP capacities measured at 4.8 and 9.6 kPa are shown as a function of time in Figures 3 and 4, respectively. The data selected for PUP capacity at 2, 4, 8 and 16 hours are listed in Table 1 below. Table 1 PUP capabilities for mixed stratum absorbent polymer compositions, ion exchange 4. 8 kPa (4.8 kPa 4.8 kPa 9.6 kPa 9.6 kPa 9.6 kPa (4 hrs) (8 hrs) (16 hrs) (2 hrs) (8 hrs) (16 hrs) A comparison of PUP capabilities indicates that the ion exchange, mixed stratum absorbent polymer composition (sample MB-1) exhibits an approximately 100% increase in PUP capacity at a confining pressure of 9.6 kPa, and a increase of approximately 40% in the PUP capacity at a confining pressure of 4.8 kPa after 8 hours, with respect to the capacity of the partially neutralized polyacrylate absorbent polymer under analogous test conditions (control sample). (v) Measurement of Permeability A measurement of permeability and an indication of porosity is provided by the saline flow conductivity of the gel bed as described in U.S. Patent No. 5,562,646, (Goldman et al.) issued on October 8, 1996. This method is modified for mixed strand absorbent polymer systems, ion exchange, as discussed below. Approximately 0.9 grams of the ion exchange mixed stratum absorbent polymer composition (sample MB-1) is transferred to a cylinder designed for the measurement of saline flow conductivity (SFC), and is spread gently over the total area of the screen that comprises the base of the cylinder. The measured values of the saline flow conductivity are listed in Table 2 below.

Table 2 SFC values for mixed-strand absorbent polymer compositions, ion exchange Comparison of the saline flow conductivity values showed that the permeability that the mixed stratum, ion exchange absorbent polymer composition (sample MB-1) is substantially higher than that of the partially neutralized polyacrylate absorbent polymer (control sample) ) under analogous test conditions. It is believed that the sample of the ion exchange mixed stratum absorbent polymer continues to exchange ions from the salt solution during the SFC measurement. Finally, the ion exchange capacity of the absorbent polymer is exceeded, and the ionic strength of the solution surrounding the swollen polymer increases, resulting in some deflation of the gel bed. The amount of fluid that is squeezed out of the gel as a result of this deflation is small compared to the amount of fluid flowing through the gel bed during the SFC measurement. Because the final thickness of the gel bed is significantly less than the initial thickness, the final thickness of the gel bed is used to calculate the SFC values. By using the final thickness of the gel bed in the calculation, the minimum SFC achieved during the measurement is provided. By using the initial thickness or an intermediate of the gel bed, it will even provide higher SFC values. Although SFC is not a direct measurement of porosity, high fluid permeability also generally requires a high degree of porosity in the particulate systems of the absorbent polymer. In this way, the value of relatively high SFC for the ion exchange, mixed stratum absorbent polymer composition also denotes a relatively high level of porosity. (vi) Integrity of the gel bed A measurement of the integrity of the layer of the absorbent polymer composition in the swollen state is provided by the ball rupture resistance (BBS) as described above. The measured values of the ball rupture strength for the MB-1 sample, the ST sample, and the control sample are listed in Table 3 below.

Table 3 BBS values for mixed-strand absorbent polymer compositions, ion exchange A comparison of the values of the ball breaking strength in Table 3 indicates that the ion exchange, mixed stratum absorbent polymer composition (sample MB-1) exhibits a substantial increase in the integrity of the gel layer with ratio to the partially neutralized polyacrylate absorbent polymer (control sample) and the ST sample, under analogous test conditions.

Example 2: Preparation of ion exchange absorbent polymers (i) Cation exchange absorbing polymer The cation exchange absorbing polymer is prepared as described in Example 1, section (i), (sample PAA). (ii) Anion exchange absorbing polymer a) Preparation of the cross-linked polyallylamine The polyallylamine hydrochloride with a nominal weight average molecular weight of 60,000 g / mole is obtained from Polysciences, Inc. Warrington, Pennsylvania (catalog number 18378; lot number 455913). A solution of polyallylamine hydrochloride is prepared by dissolving 16.4 grams of the polymer in 165 ml of distilled water. 15.6 grams of a 50% aqueous sodium hydroxide solution are added dropwise to this solution while stirring. Ethylene glycol diglycidyl ether (50% solution), 2.0 grams (Aldrich Chemical Col, catalog number E2, 720-3, lot number 07405DN), is added to the polyallylamine solution and the mixture is stirred at room temperature for approximately 2 minutes before being placed in a ventilated oven at approximately 65 ° C for three hours. The resulting gel is fragmented into pieces of approximately 5 mm in diameter, and transferred to a 4000 ml flask containing one liter of distilled water. The mixture is stirred gently overnight and the excess water is decanted. The remaining sample was dried under high vacuum at room temperature for about 96 hours to produce a slightly cross-linked polyallylamine anion exchange absorbing polymer which is stored under a dry atmosphere (PAAM sample). b) Methylation of the PAAM sample 21.02 grams of formic acid (96% solution), (Aldrich Chemical Co., catalog number 25.136-4), and 35.56 grams of formaldehyde (37% solution) (Aldrich Chemical Co) are added. ., catalog number 25,254-9, batch number 04717TZ, to 800 grams of distilled water, 10 grams of crosslinked polyamine are added (sample PAAM) to the previous solution and the mixture is placed in an oven at 70 ° C for 24 hours. The gel is recovered by decantation and stirred overnight in 1000 ml of water to remove the extractables. The supernatant solution is decanted and replaced with one liter of 1.7% aqueous sodium hydroxide solution to remove the excess formic acid in the gel. The mixture is allowed to settle for about 24 hours and the polymer is recovered by decanting the supernatant fluid. This process is repeated (approximately three times) with 1 liter of 1.7% aqueous sodium hydroxide solution until its pH reaches 13. The gel is recovered by vacuum filtration and soaked in 3000 ml of water overnight. The excess water is decanted and the remaining sample is dried under high vacuum at room temperature for about 96 hours to produce a lightly cross-linked tertiary polyallylamine anion exchange absorbent polymer which is stored under a dry atmosphere. The NMR spectroscopic analysis of the product indicates that approximately 90% of the amine groups in the polymer are methylated to form the tertiary amine portions (t-PAAM sample). (iii) Mixed layer, ion exchange absorbent polymer The cross-linked tertiary polyallylamine anion exchange absorbent polymer (t-PAAM sample) is cryogenically ground and sieved under an atmosphere of dry nitrogen. A fraction of the particle size is collected which passes through a standard 25 mesh screen of the United States of America series, but not through a 70 mesh screen of the standard series of the United States of America (ie, a fraction with particles in scale of approximately 200 to 700 microns in diameter). Approximately 0.29 grams of the cross-linked poly (acrylic acid) cation exchange absorbing polymer, sieved (sample) are mixed together PAA) and 0.71 grams of the polyallylamine anion exchange absorbing polymer cross-linked, sieved (sample t-PAAM) to distribute the particles of each type of polymer evenly throughout the mixture. This mixture comprises an ion exchange, mixed stratum absorbent polymer composition (sample MB-2) of the present invention). (iv) PUP Capacity Measurements Approximately 0.9 grams of the ion exchange, mixed stratum absorbent polymer compositions (sample MB-2) are transferred to a PUP cylinder (as described in the Test Methods section above). ), and is evenly dispersed over the entire area of the screen comprising the base of the cylinder. The PUP capacities in the separated samples are determined under confining pressures of 4.8 and 9.6 kPa, with the amount of fluid absorbed measured at frequent intervals over a period of 16 hours. The PUP capacity measured at 4.8 and 9.6 kPa is shown as a function of time in Figures 3 and 4, respectively. The data selected for PUP capacity at 2, 4, 8 and 16 hours are listed in Table 4 below. Table 4 PUP Capacities for Mixed Stratum, Ion Exchange Absorbing Polymer Compositions.

A comparison of the PUP capabilities indicates that the ion exchange mixed stratum absorbent polymer composition (sample MB-2) absorbs substantially more synthetic urine solution than the partially neutralized poiliacrylate absorbent polymer (control samples) under the test conditions described above. Example 3 Preparation of the ion exchange absorbent polymers (i) Cation exchange absorbent polymer. The cation exchange absorbing polymer is prepared as described in Example 1 section (i); (shows PAA). (ii) Anion exchange absorbent polymer a) Preparation of linear polyethylenimine Poly (2-ethyl-2-oxazoline) with a nominal weight average molecular weight of 500,000 g / mole is obtained from Aldrich Chemical Co., Milwaukee, Wisconsin (catalog number 37,397-4, lot number 17223HG). A 100 gram sample of poly (2-ethyl-2-oxazoline) is dissolved in a hydrochloric acid solution which is prepared by mixing 1000 ml of water and 200 ml of concentrated hydrochloric acid. This solution is refluxed at 100 ° C for 72 hours then allowed to cool to room temperature. The product is precipitated from the reaction solution by adding 256 ml of a 50% solution of sodium hydroxide dropwise by stirring. The precipitated white solid is recovered by vacuum filtration and washed with 5000 ml of water. The product is dried under high vacuum for 48 hours to produce linear polyethylenimine. b) Preparation of the cross-linked linear polyethyleneimine. 5.0 gr. of linear polyethyleneimine, as prepared above, is dissolved in 50 ml of methanol. 0.5 gr added of ethylene glycol diglycidyl ether (50% solution) (Aldrich Chemical Co., catalog number E2.720-3, lot number 07405DN), to the linear polyethyleneimine solution and the mixture is stirred at room temperature for approximately 2 minutes before being placed in a ventilated oven at room temperature. approximately 65 ° C for three hours. The resulting gel is fragmented into particles of approximately 5 ml in diameter, and is gently stirred in 500 ml of methanol overnight. The sample is recovered by decantation, and dried under high vacuum for about 48 hours to produce a lightly crosslinked polyethyleneimine anion exchange absorbing polymer which is stored under a dry atmosphere (sample LPE-1). c) Partial methylation of the cross-linked polyethylenimine 5.37 g. of linear polyethyleneimine, as prepared above, in 45 gr. of methanol. 1.07 gr. of ethylene glycol digiidicidyl ether (50% solution), (Aldrich Chemical Co., catalog number E2-720-3, lot number 07405DN), to the linear polyethylene imine solution and the mixture is stirred at room temperature for approximately 2 hours. minutes before being placed in a ventilated oven at approximately 65 ° C for three hours. The resulting gel is fragmented into particles of approximately 5 ml in diameter, and stirred gently in 500 ml of methanol overnight. The sample is recovered by decantation, and dried under high vacuum for about 48 hours to produce a slightly crosslinked polyethyleneimine anion exchange absorbing polymer which is stored under a dry atmosphere (sample LPEI-2). 48.44 grams (Aldrich Chemical Co., catalog number 25.136-4) of formic acid (96% solution), and 81.17 grams (Aldrich Chemical Co., catalog number 25.254-9) of formaldehyde (37% solution) were added to 370.39 grams of distilled water to produce 500 grams of the supply solution. 46.98 grams of this delivery solution is added to 5.37 grams of the cross-linked linear polyethyleneimine (sample LPEI-2). The mixture is further diluted with 450 ml of distilled water and placed in an oven at 70 ° C for 24 hours. The gel is recovered by decantation, and stirred overnight in 2500 ml of water to remove the extractables. The solution The supernatant is decanted and replaced with 20 ml of the 50% aqueous sodium hydroxide solution to remove the excess formic acid in the gel. The mixture is allowed to remain for about 3 hours and the polymer is recovered by decanting the supernatant fluid. This process is repeated (approximately 3 times) with 20 ml of the 50% aqueous sodium hydroxide solution until a pH of 13 is obtained. The gel is recovered by vacuum filtration and soaked in 100 ml of water overnight . The supernatant fluid is decanted and replaced with 500 ml of tetrahydrofuran. After 24 hours, the tetrahydrofuran is decanted and replaced with 500 ml of anhydrous ether. After 24 hours, the ether is decanted and the gel is dried under high vacuum at room temperature for 48 hours. NMR spectroscopic analysis of the product indicates that about 65% of the amine groups in the polymer are methylated to form the tertiary amine moieties. (Shows NMEI-65). (iii) Mixed Strand Ion Exchange Absorbent Polymer The crosslinked linear polyethylenimine and poly (N-methylethylimine) cross-linked anion exchange polymers (samples LPEI-1 and NMEI-65) are each cryogenically ground separately and sieved under a dry nitrogen atmosphere. A fraction of the particle size that passes through a standard 25 mesh screen of the United States of America series is placed for each material, but not through a 70 mesh screen of the standard series of the United States. (ie, a fraction with particles on the scale of approximately 200 to 700 microns in diameter). Approximately 1 gram of each of the sieved, cross-linked, anion-exchange absorbent polymers (samples LPEI-1 and NMEI-65) are mixed separately with 1 gram of the poii cation exchange absorbing polymer (acrylic acid) cross-linked, sieved portions. (sample PAA) to distribute the particles of each type of polymer uniformly in all mixtures. Each of these mixtures comprises an absorbent polymer composition of mixed stratum, ion exchange (samples MB-3a and MB-3b), respectively) of the present invention. (iv) PUP Capacity Measurements Approximately 0.9 grams of the ion exchange, mixed stratum absorbent polymer compositions (MB-3a, and MB-3b samples) are transferred to separate PUP cylinders (as described in the section). of Test Methods above) and are gently dispersed over the total area of the screen comprising the base of the cylinder. PUP capacities are determined in separate samples under confining pressures of 4.8 and 9.6 kPa, with the amount of fluid absorbed measured at frequent intervals over a period of 16 hours. The PUP capacities measured at 4.8 and 9.6 kPa are shown as a function of time in Figures 3 and 4, respectively. The data selected from the PUP capacity at 4, 8 and 16 hours are listed in Table 5 below. Table 5 PUP Capacities for mixed stratum absorbent polymer compositions, ion exchange Comparisons of the PUP capabilities indicate that the ion exchange, mixed stratum absorbent polymer compositions (samples Mb-3a and MB-3b) absorb substantially more synthetic urine solution than the partially neutralized polyacrylate absorbent polymer (control sample) under the test conditions described above.

Claims (16)

1. CLAIMS 1. An ion exchange, mixed stratum absorbent polymer composition having one or more of the following: (i) a performance under pressure (PUP) capability in the synthetic urine solution under an applied load of 4.8 kPa at minus 30 g / g after 2 hours; (ii) a PUP capacity in the synthetic urine solution under an applied load of 4.8 kPa of at least 40 g / g after 8 hours; or (iii) a PUP capacity in the synthetic urine solution under an applied load of 4.8 kPa of at least 42 g / g after 16 hours. 2. The mixed ion exchange stratum composition according to claim 1, having a PUP capacity in the synthetic urine solution under an applied load of 4.8 kPa of at least 32 g / g, preferably at least 35 g / g, after 2 hours. The mixed layer, ion exchange composition according to claim 1 or 2 having a PUP capacity in the synthetic urine solution under an applied load of 4.8 kPa of at least 42 g / g, preferably at least 44 g / g, after 8 hours. 4. The mixed ion exchange stratum composition according to any of claims 1 to 3 having a PUP capacity in the synthetic urine solution under an applied load of 4.8 kPa of at least 44 g / g, preferably at least 46 g / g, after 16 hours. 5. An ion exchange mixed stratum absorbent polymer composition having one or more of the following: (i) a performance under pressure (PUP) capability in the synthetic urine solution under an applied load of 9.6 kPa at least 27 g / g after 4 hours; (I) a PUP capacity in the synthetic urine solution under an applied load of 9.6 kPa of at least 30 g / g after 8 hours; or (iii) a PUP capacity in the synthetic urine solution under an applied load of 9.6 kPa of at least 33 g / g after 16 hours. 6. The mixed ion exchange stratum composition according to claim 5, having a PUP capacity in the synthetic urine solution under an applied load of 9.6 kPa of at least 32 g / g after 4 hours. The mixed layer, ion exchange composition according to claim 5 6 6, which has a PUP capacity in the synthetic urine solution under an applied load of 9.6 kPa of at least 35 g / g after 8 hours. hours. 8. The mixed layer, ion exchange composition according to any of claims 5 to 7, which has a PUP capacity in the synthetic urine solution under an applied load of 9.6 kPa of at least 38 g / g after 16 hours. 9. The ion-exchange mixed stratum composition according to any of claims 1 to 8, characterized in that the ion exchange capacity of the anion exchange absorbent polymer is at least 15 meq / g and the ion exchange capacity. of the cationic exchange hydrogel-forming polymer is at least 8 meq / g. 10. An ion exchange, mixed stratum absorbent polymer composition comprising (i) an absorbent cation exchange polymer; and an anion exchange absorbent polymer, characterized in that the ion exchange capacity of the anion exchange absorbent polymer is at least 15 meq / g. 11. The composition of mixed layer, ion exchange, according to claim 10, characterized in that the absorbent polymer of Cation exchange is from 80% to 100% in the unneutralized acid form and the anion exchange absorbing polymer is from 80 to 100% in the unneutralized base form. 12. The mixed layer, ion exchange composition according to claim 10 or 11, characterized in that the ion exchange capacity of the anion exchange absorbent polymer is at least 20 meq / g. 13. The mixed layer, ion exchange composition according to claims 10 to 12, characterized in that the composition comprises an anion exchange absorbing polymer having a multiplicity of unneutralized primary, secondary and / or tertiary amine groups.; preferably the composition comprises an anion exchange absorbing polymer prepared from a monomer selected from the group consisting of ethylene imine, allylamine, diallylamine, 4-aminobutene, alkyl oxazolines, vinylformamide, 5-aminopentene, carbodiimides, formaldazine, and melamine; a secondary amine derivative of any of the foregoing; a tertiary amine derivative of any of the foregoing; and mixtures thereof; more preferably the anion exchange absorbing polymer is selected from the group consisting of poly (ethylenimine); poly (allylamine); and mixtures thereof. 14. An absorbent polymer composition having (I) a performance under pressure (PUP) capability in the synthetic urine solution under an applied load of 4.8 kPa of at least 42 g / g after 4 hours; and / or (i) a PUP capacity in the synthetic urine solution under an applied load of 9.6 kPa of at least 32 g / g after 4 hours. 15. An absorbent member for the containment of aqueous body fluids, which comprises at least one region comprising the mixed stratum, ion exchange composition of any one of claims 1 to 14. 16. An absorbent article comprising a top sheet liquid permeable, a backsheet and an absorbent core positioned between the top sheet and the backsheet, characterized in that the absorbent core comprises the absorbent member of claim 15.