MXPA96003472A - Absorbent members that comprise absorbing materials that have absorbing properties - Google Patents

Abstract

The present invention relates to an absorbent member comprising at least one region which comprises an absorbent material, wherein said absorbent material comprises a mixture of a plurality of absorbent gelling particles comprising a water insoluble polymer, capable of swelling with water, and (2) an absorbent property modification polymer reactive with at least one component included in the urine, wherein said plurality of absorbent gelling particles are spontaneously connected through said property modification polymer. absorbent in response to a urine application, and wherein when said absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material under a predetermined load, said layer of swollen absorbent material has a volume Density value of Gel (DVG) below 0.95 g / cm3 in the D test

Description

ABSORBENT MEMBERS COMPRISING ABSORBENT MATERIALS WHICH HAVE IMPROVED ABSORBING PROPERTIES FIELD OF THE INVENTION The present invention relates to absorbent members which, upon contact with liquids such as water or body fluids, swell and imbibe such liquids. More specifically, the present invention relates to absorbent members comprising absorbent materials having at least an improved physical property after swelling The present invention has particular application to absorbent articles such as diapers, ear pads, adult incontinence, sanitary napkins, and the like.

BACKGROUND OF THE INVENTION Water-swellable, water-insoluble hydrogel-forming absorbent polymers are capable of absorbing large amounts of liquids such as water, body fluids (eg, urine, blood, menstrual fluid), industrial fluids and household fluids and they are also capable of retaining such liquids absorbed under improved pressures. The absorption characteristics of such polymer materials make them especially useful for incorporation into absorbent articles such as disposable diapers, incontinence pads and briefs for adults, and catamenial products, such as sanitary napkins, and the like. 5 The development of highly absorbent members in such absorbent articles is the subject of a commercial, substantial interest. A highly desired feature for such products is thinness. For example, thinner diapers are less bulky during use, they adjust better $. ' under the clothes and they notice less. They are also more compact in the package, making diapers easier to carry and store. Also, the compact appearance in the package results in reduced distribution costs for the manufacturer and the distributor, including less storage space 5 required in the store per diaper unit. The ability to provide thinner absorbent articles, such as diapers, has been contingent with respect to the ability to develop relatively thin absorbent cores or structures that can acquire and store large or quantities of discarded body fluids, particularly urine. In this regard, the use of certain absorbent polymers, usually referred to as "hydrogels", "superabsorbents" or "hydrocolloid" material, has been particularly important. See, for example, the patent of 5 E.U.A. 3,699,103 (Harper et al.), Issued June 13, 1972 and patent of E.U.A. 3,770,731 (Harmon) issued June 20, 1972, describing the use of such absorbent polymers (hereinafter "absorbent hydrogel-forming polymers"), in absorbent articles. In fact, the development of thinner diapers has been the direct consequence of thinner absorbent cores that have the ability for these hydrogel-forming absorbent polymers to absorb large amounts of discarded body fluids, typically when used in combination with a fibrous matrix. . See, for example, US patent. 4,673,402 (Weisman et al.), Issued June 16, 1987 and patent of E.U.A. 4,935,022 (Lash et al.), Issued June 19, 1990, which disclose double layer core structures comprising a fibrous matrix and hydrogel-forming absorbent polymers useful for making thin, compact, non-bulky diapers. At present, the above absorbent structures have been composed, in general, of relatively low amounts, (e.g., less than about 50% by weight) of these hydrogel-forming absorbent polymers. See, for example, US patent. 4,834,735 (Alemany et al.) Issued May 30, 1989, (preferably from about 9 to about 50% hydrogel-forming absorbent polymer in the fibrous matrix). There are several reasons for this. The hydrogel-forming absorbent polymers used in previous absorbent structures generally have not had an absorption scale that could allow them to rapidly absorb body fluids, especially in "jet" exit situations. This has necessitated the inclusion of fibers, typically wood pulp fibers, to serve as temporary reservoirs to hold the discarded fluids until they are absorbed by the absorbent hydrogel-forming polymer. Importantly, many of the known hydrogel-forming absorbent polymers exhibited gel blocking when used in absorbent articles in a high concentration. "Gel blocking" occurs when the particles of the hydrogel-forming absorbent polymer are wetted, and they swell to inhibit the transmission of fluid to other regions of the absorbent structure. The wetting of these other regions of the absorbent member, therefore, takes place via a very slow diffusion process. In terms of practice, this means that the acquisition of fluids by the absorbent structure is much slower than the speed at which the fluids are discarded, especially in "jet" situations. The spill of the absorbent article can be presented either before the particles of the hydrogel-forming absorbent polymer in the absorbent member are completely saturated or before the fluid can diffuse or wick beyond the "blocking" particles. towards the rest of the absorbing member. Gel blocking can be a particularly acute problem if the particles of the hydrogel-forming absorbent polymer do not have adequate strength to the gel and deform or stretch under tension once the particles swell with the absorbed fl ow. See, patent of E.U.A. 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 particles of the hydrogel-forming absorbent polymer are dispersed. This fibrous matrix keeps the particles of the hydrogel-forming absorbent polymer separated. This fibrous matrix also provides a capillary structure that allows the fluid to reach the absorbent gel-forming polymer located in regions that are far from the initial fluid discharge point. See patent of E.U.A. 4,834,735 (Alemany et al.) Issued May 30, 1989. However, by dispersing the hydrogel-forming absorbent polymer in a fibrous matrix, at relatively low concentrations, to minimize or avoid gel blocking, it can reduce the ability of total fluid storage of the thinnest absorbent structures. Using lower concentrations of these hydrogel-forming absorbent polymers somewhat limits the real advantage of these materials, mainly their ability to absorb and retain large amounts of body fluids for a given volume. In general, increasing the gel strength of the hydrogel-forming absorbent polymers can reduce the reduction of gel block. Gel resistance refers to the tendency of the hydrogel formed from these polymers to deform or "flow" under use stresses. The resistance to the gel needs to be such that the formed hydrogel does not deform and fill, to an unacceptable degree,. the spaces of the capillary gap in the structure or absorbent article, thus inhibiting the absorbent capacity of the structure / article, as well as the distribution of fluid through the structure / article. The high resistance to the gel is usually obtained by entanglement. It is believed that the interlacing improves the resistance to deformation of the surfaces of the hydrogel-forming absorbent polymer. However, the interlacing has a profound impact on the absorbent capacity of a hydrogel-forming absorbent polymer. In general, the absorbent capacity or "gel volume" has an inverse dependence of energy law on the level of entanglement. That is, a high level of entanglement results in high gel strength but low gel volume. The gel volume is a measure of the amount of water or fluids in the body that a given amount of hydrogel-forming polymer can absorb. The gel volume is required to be sufficiently high so that the hydrogel-forming polymer can absorb significant amounts of the aqueous body fluids found during the use of the absorbent article.

Another important factor that has been considered is the liquid permeability of hydrogel-forming absorbent polymers. It has been found that the permeability or flow conductivity of the gel layer formed by the swelling in the presence of fluids of the. body, it is extremely important when these absorbent polymers are used in cores or absorbent members at a high concentration in localized regions or through them. It should be noted that the lack of liquid permeability or C "flow conductivity of absorbent polymers can directly impact the ability of the resulting gel layers to acquire and distribute body fl uids." Yet another important factor of absorbent polymers hydrogel formers is the level of extractable polymer material present therein. 4,654,039 (Brandt et al.) Issued March 31, 1987, (reissued on April 19, 1988 as Re. 32,649). Many absorbent hydrogel-forming polymers contain significant levels of extractable polymer material. This extractable polymer material can be leached out of the resulting hydrogel by the body fluids (eg, urine) during the period such body fluids remain in contact with the absorbent hydrogel-forming polymer. It is believed that said extracted polymer material can alter both the chemical (eg, osmolarity) and physical (eg, viscosity) characteristics of the body fluid to such an extent that the fluid is more slowly absorbed and more poorly maintained by the hydrogel. The fluid contaminated polymer is also more poorly transported through the absorbent member. Said situation may contribute to an undesirable and premature leakage of the body fluid of the absorbent article. Thus, it is desirable to use hydrogel-forming absorbent polymers with lower levels of extractable polymer material. Another important factor that has to be considered to have a great advantage of the high concentration of hydrogel-forming absorbent polymers in thinner absorbent articles is the moisture integrity of the region or regions in the absorbent member comprising these polymers. The term "good moisture integrity" means that the region or regions in the absorbent member, which has a high concentration of hydrogel-forming absorbent polymer, have sufficient integrity in a partially wet, and / or wet state, so that the physical continuity of the hydrogel formed after swelling in the presence of body fluids, is not substantially interrupted or altered, even when subjected to normal conditions of use. During normal use, the absorbent cores in absorbent articles are typically subjected to tension and torsional forces of varying intensity and direction. These tensional and torsional forces include bulging in the crotch area, stretching and torsional forces as the person using the absorbent article walks, kneels, and the like. If the moisture integrity is inadequate, these tensional and torsional forces can cause a substantial alteration and / or rupture in the physical continuity of the hydrogel. Said alteration can minimize or completely negate any advantageous fluid distribution property (permeability / flow conductivity) of the hydrogel-forming absorbent polymer. Said alteration and / or rupture can also cause the gel to move and bring the hydrogel to the surface of the absorbent article, thus causing the so-called "gel-on-skin" problem. Yet another important factor of the hydrogel-forming absorbent polymers used in thinner absorbent articles is the gelatinous / viscous feel when touching or handling the absorbent article after use. When the hydrogel-forming absorbent polymer is dispersed in the region or regions at a high concentration, the swollen gel, formed by the absorption of fluids from the body, is a layer of gel where the particles move and the gel layer is crushed when subjected to forces such as thrust, compression, etc., when handling the absorbent article after use. This is why absorbent articles that have a high concentration of absorbent gel-forming polymer, provide users or consumers with the sensation of "wet / viscous" when they touch or manipulate them from the outside. Therefore, an object of the present invention is to avoid the gel blocking phenomenon caused in absorbent articles while maintaining the required absorbent capacity. Another object of the present invention is to prevent spillage of swollen absorbent materials from the absorbent articles. Still another object of the present invention is to improve the gelatinous / viscous feel of the absorbent articles after use. A further object of the present invention is to provide thinner absorbent articles. Still another object of the present invention is to provide thin disposable absorbent articles, such as diapers, sanitary napkins, tampons, and the like.

BRIEF DESCRIPTION OF THE INVENTION In summary it is established that, the present invention relates to absorbent members comprising at least one region, which comprises an absorbent material, wherein the absorbent material comprises a mixture of (1) a plurality of absorbent gelling particles comprising a water-insoluble, water-swellable polymer; and (2) an absorbent property modification polymer that reacts with at least one component included in the urine. In one aspect of the invention, when the absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material under a predetermined load, the layer of swollen absorbent material has a value of Gel Volume Density (DVG) per below 0.95 g / cm3 in the DVG test. In another aspect of the invention, when the absorbent material swells by absorbing urine and is formed to a predetermined layer of swollen absorbent material, the layer of the swollen absorbent material has a Saline Flow Conductivity (CFS) value of at least 20. x 10-7 cm3 sec / g in the CFS test. In yet another aspect of the invention, when the absorbent material swells by absorbing urine and is formed to a predetermined layer of swollen absorbent material, the layer of the swollen absorbent material has a Ball Resistance Resistance (RRB) value of at least 30 gf in the RRB test. In another aspect of the invention, when the absorbent material swells by absorbing urine and is formed to a predetermined layer of swollen absorbent material, the layer of the swollen absorbent material has a Compression Recovery (RC) value of at least 15% in the RC test. In yet another aspect of the present invention, the plurality of absorbent gelling particles are spontaneously connected through the absorbent property modification polymer in response to the application of urine.

The present invention also relates to absorbent articles. In another aspect of the invention, the absorbent article comprises: (a) a liquid permeable topsheet; (b) a back sheet impervious to liquid; (c) an absorbent core positioned between the topsheet and the backsheet, wherein the absorbent core comprises at least one of the absorbent members described above.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view of an apparatus for measuring the value of the Gel Volume Density (DVG) of the absorbent materials. Figure 2 is a schematic view of an apparatus for measuring the value of the Saline Flow Conductivity (CFS) of the absorbent materials. Figure 3 depicts an enlarged sectional view of the piston / cylinder assembly shown in Figure 2.

Figure 4 depicts a plan view of the bottom of the piston head from the piston / cylinder assembly shown in Figure 3. Figure 5 is a schematic view of an apparatus for measuring the value of the Ball Resilience Resistance (FIG. RRB) of the absorbent materials. Figure 6 is a schematic view of an apparatus for preparing a predetermined layer of the swollen absorbent materials. Figure 7 is a schematic view of an apparatus for measuring the value of the Compression Recovery (RC) of the absorbent materials. Figure 8 is a graph showing the relationship between the compression / recovery load and the compression depth in the RC test. Figure 9 is a graph showing an example of the relationship between the compression / recovery load and the compression depth in the RC test. Figure 10 is a graph showing an example comparison of the relationship between the compression / recovery load and the compression depth in the RC test.

DETAILED DESCRIPTION OF THE INVENTION A. Definitions As used herein, the term "body fluids" includes urine, blood, menstruation, and vaginal waste. As used herein, the term "absorbent core" refers to the absorbent article component that is primarily responsible for the fluid handling properties of the article, including, the acquisition, transportation, distribution, and storage of 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 absorbent core components that typically provide one or more fluid handling properties, v. gr. , fluid acquisition, fluid distribution, fluid transportation, fluid storage, etc. The absorbent member may comprise the entire absorbent core or only a portion of the absorbent core, i.e., the absorbent core may comprise one or more absorbent members. As used herein, the term "region" refers to portions or sections of the absorbent member. As used herein, the term "layer" refers to an absorbent member whose primary dimension is X-Y, ie, along its length and width, however, it should be noted that the layer has thickness.

B. Absorbent Members of the Invention The absorbent members of the present invention are capable of absorbing large quantities of liquids, such as water, body fluids, industrial fluids and household fluids, and are capable of retaining said liquids under moderate pressure. In particular, the absorbent materials included in the absorbent members of the present invention will swell, in general, isotropically and rapidly absorb liquids. Briefly, an absorbent member of the present invention comprises at least one region, which comprises an absorbent material. The absorbent material comprises a mixture of (1) a plurality of absorbent gelling particles comprising a water insoluble, water-swellable polymer, and (2) an absorbent property modification polymer that reacts with at least one component included in the urine. In the mixture, the property modification polymer "Absorbent will be on at least a portion of the surface area of the absorbent gelling particles, preferably 70%, most preferably more than 90% of the entire surface area of the absorbent gelling particles. In a preferred embodiment, the absorbent material is at a concentration of at least 40%, most preferably from about 60 to 100% by weight in the region. In a most preferred embodiment, the absorbent member comprises a fibrous matrix, wherein the absorbent material is distributed in the fibrous matrix. In a preferred embodiment, there are fewer covalent bonds between the absorbent property modification polymer and the absorbent gelling particles. In a highly preferred embodiment, there is no covalent bond between the absorbent property modification polymer and the absorbent gelling particles. In such embodiments, the bulk of the absorbent property modification polymer is associated only with the absorbent gelling particles by means of molecular interactions, such as electrostatic interaction, hydrogen bonding interaction, and van der aals interactions. Therefore, the existence of the absorbent property modification polymer on the absorbent gelling particles gives very little effect to the gel volume of the absorbent gelling particles. Preferably, the existence of the absorbent property modification polymer causes a change of less than 10% of the gel volume of the resulting absorbent material. This can also be achieved by means of smaller amounts of chemical and / or physical bonds between the absorbent property modification polymer and the absorbent gelling particles. If there are certain chemical bonds between the absorbent modifying polymer and the absorbent gelling particles, it is preferred that the type and degree of said chemical bonds have little effect on the gel volume of the resulting absorbent material. The reduction in gel volume, due to the association of the absorbent property modification polymer with the absorbent gelling particles, is preferred to be less than 10%. Preferably, almost all of the functional groups of the absorbent property modification polymer are not used to bind the absorbent property modification polymer to the absorbent polymer of the absorbent material. These unused functional groups are preferably used for the bonds between the absorbent gelling particles after the application of urine. Consequently, the absorbent gelling particles can spontaneously connect through the absorbent property modification polymer in response to a urine application. Accordingly, when the absorbent material is provided in the region at a high concentration (e.g., more than 90%), the absorbent material is formed into a porous aggregate of the swollen particles after the application of urine. It should be noted that the unused functional groups of the absorbent property modification polymer 5 of the absorbent material can also react with the extractable components included in the absorbent gel-forming polymers. More specifically, the absorbent property modification polymer is able to trap the extracted components, which can cause a change of H. the characteristics of the body fluid. Therefore, the presence of the absorbent property modification polymer can reduce the level of the extractable components of the absorbent material. The absorbent materials used in this The invention has at least one improved absorbent property. The absorbent property can be improved by changing at least one physical property after the absorbent material swells. The "physical property", used herein, includes (1) porosity, (2) liquid permeability, (3) moisture integrity, and (4) recovery property, when subjected to external forces of an absorbent material after swelling by the absorption of liquids. The porosity of an absorbent material after swelling is evaluated by conducting the Density test.

Volume of Gel (DVG). The liquid permeability of an absorbent material after swelling can be evaluated by conducting the Saline Flow Conductivity (CFS) test. The moisture integrity of an absorbent material after swelling can be evaluated by conducting the Ball Resistance Resistance (RRB) test. The property of recovery of an absorbent material after swelling can be evaluated by conducting the Compression Recovery (RC) test. The test methods to evaluate these properties, as well as the volume of gel and lt components. removable, will be described in detail in the "test methods" section. In one aspect of the present invention, the absorbent material used in the absorbent member has such an improved absorbent property as when the absorbent material is swollen by absorbing urine and is formed to a predetermined layer of the swollen absorbent material under a predetermined load, the layer of the absorbent material having a Gel Volume Density (DVG) value below 0.95 g / cm3 in the DVG test . The DVG is an important physical property after swelling of the absorbent materials used in the present invention. This serves to show its gel volume density when swollen with body fluids, to form a hydrogel zone or layer. This density is defined herein in terms of the DVG value of the absorbent material. The DVG measures the weight per unit volume of a gel layer formed of the swollen absorbent material, including the holes inherent in the gel layer. In other words, the DVG is a measure of the porosity of the swollen absorbent materials. It is anticipated that the DVG value has a relationship with the CFS value described above. The DVG value of the absorbent materials used in the present invention is below about 0.95 g / cm3, preferably below about 0.9 g / cm3, and most preferably below about 0.85 g / cm3. Typically, these DVG values are in the range of about 0.5 to about 0.9 g / cm3, very typically from 0.7 to 0.85 g / cm3, approximately. In another aspect of the present invention, the absorbent material used in the absorbent member has such improved property that when the absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material, the layer of the swollen absorbent material has a value of Saline Flow Conductivity (CFS) of at least 20 x 10 -7 cm3 sec / g in the CFS test.

CFS is another important physical property after swelling of the absorbent materials used in the present invention. This serves to show its liquid permeability or flow conductivity when swollen with body fluids, to form a hydrogel zone or layer.

CFS measures the ability of a swollen absorbent material to transport saline fluids through it. In other words, it shows the ability of a gel layer, formed from the swollen absorbent material, to transport liquids. The CFS value of the absorbent materials after swelling of the present invention is at least about 20 x 10 -7 cm 3 sec / g, preferably at least about 40 x 10 -7 cm 3 sec / g, and most preferably by at least about 100 x 10 -7 cm3 sec / g. Typically, these CFS values are in the range of about 40 to about 300 x 10 -7 cm3 sec / g, very typically about 60 to 150 x 10-7 cm3 sec / g, approximately. It is believed that when an absorbent material is present at a high concentration in an absorbent member and then swells to form a hydrogel under use pressures, the boundaries of the hydrogel are brought into contact, and the interstitial voids in this region of high concentration generally , they are joined by the hydrogel. When this occurs, it is believed that the porosity and / or permeability or flow conductivity properties of this region generally reflect the porosity and / or permeability or flow conductivity properties of a hydrogel zone or layer formed from the material swollen absorbent. It is further believed that increasing the porosity and / or permeability of these high concentration swollen regions levels out said appearance or even exceeded conventional acquisition / distribution materials, such as wood pulp fluff, can provide superior fluid handling properties for the absorbent member and absorbent core 5, thus reducing spill incidents, especially at high fluid loads. (The higher CFS values also reflect the ability of the hydrogel formed to acquire body fluids under normal conditions of use). Yet, in another aspect of the present invention, an absorbent material has said improved absorbent property that when the absorbent material swells by absorbing urine, and is formed to a predetermined layer of the swollen absorbent material, the layer of the swollen absorbent material has a Ball Resistance Resistance (RRB) value of at least 30 gf in the RRB test). The RRB is another important physical property after the absorbent materials used in the present invention swell. This serves to show your peak load of burst when they swell with body fluids to form a hydrogel zone or layer. The RRB measures the force (or peak load) required to rupture a gel layer formed from the swollen absorbent material. The RRB values of the absorbent materials, after swelling, of the present invention, is at least about 30 gf in the RRB test, preferably at least about 50 gf, and most preferably at least about 100 gf. Typically, these RRB values are on the scale of about 50 to 400 gf, and very typically about 100 to about 300 gf. It is believed that when a conventional absorbent polymer is present at high concentrations in an absorbent member and then swells to form a hydrogel, the hydrogel is pushed by the applied pressures applied thereto and can be moved to an edge portion of the member or core. Absorbent, absorbent article. When this occurs, a spill of the hydrogel can be caused from the edge portion of the absorbent article, whereby the problem of "gel-on-skin" is presented, by the use of a conventional absorbent polymer. Since the absorbent materials of the present invention have improved moisture integrity, in other words, the joints between the swollen absorbent particles of the absorbent material are more resistant, and the swollen gel particles do not move, spillage of the absorbent material can be prevented. swollen absorbent materials of absorbent articles. In another aspect of the present invention, an absorbent material has such an improved absorbent property, that when the absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material, the layer of the swollen absorbent material has a recovery value of Compression (RC) of at least 15% in the RC test. RC is another important physical property after the absorbent materials swell, used in the present invention. This serves to show their recovery of compression when they swell with body fluids, to form a zone or layer of hydrogel. The RC measures the ability of the degree to which an absorbent material, in a wet state, has returned to its original form / state when subjected to external forces. The RC values of the materials after swelling, of the present invention, is preferably at least about 20%, and most preferably at least about 30%. Typically, these RC values are in the range of about 20 to about 80%, typically about 30 to 70%. It is believed that when a conventional absorbent polymer is present at a high concentration in an absorbent member and then swells to form a hydrogel, the hydrogel looks and feels gelatinous and viscous. In particular, when a user and / or consumer touches the absorbent article from the outside, the absorbent article gives such an undesirable feeling to the user and / or consumer. Since the absorbent materials of the present invention have such improved RC values, the undesirable feeling (ie, gelatinous / viscous feeling) can be avoided to the user and / or consumer. In a preferred embodiment, an absorbent material used in the present invention can be formed into a porous structure. As used herein, the term "porous structure" means a wall-forming structure that surrounds and defines cellular voids of absorbent polymers when they are substantially dry. In general, a porous structure of absorbent material can provide the porous absorbent material with a low density and / or a high specific surface area. Under microscopic observations, the walls formed in an absorbent material, for example, show a sponge-like appearance and / or a wilted leaf type appearance. Preferred examples of porous structures of absorbent materials and methods for the same are described in the application of E.U.A. copending series No. 197,913, entitled "Absorbent Materials Having Modified Surface Characteristics And Methods For Making The Same", No. of agent JA-80U, filed on February 17, 1994, incorporated herein by reference.

C. Absorbent Materials Used in the Invention. 1. Polymers of Modification of Absorbing Property.

The Modification polymers of absorbent properties used in the present invention react with at least one component included in the urine. The term "reacting" used herein, means that a substance (ie compound or ion) has the ability to interact with other substances to cause changes in chemical / physical properties. Therefore, the absorbent property modification polymers used in the present invention have the ability to ! - -, interact with at least one component included in the urine. In a preferred embodiment, the absorbent property modification polymer has the ability to interact with a phosphate ion of the urine through electrostatic interaction. A practical method for determining whether an absorbent property modification polymer is reactive with at least one component included in the urine or not is to mix an aqueous solution of the absorbent property modification polymer with the urine. If the resulting mixing solution When it becomes turbid, the absorbent property modification polymer can be determined as reactive with at least one component included in the urine. The term "urine" used in the present should be understood in a general sense. A typical example of The content of "normal urine" is described in the book entitled "Textbook of Medical Physiology" by Arthur C. Guyton (W.B. Saunders Company, 1991, p.304), which is incorporated herein by reference. It should be noted that Jayco Synthetis Uriñe urine is used for all the measurements described here. In general 5 ', the urine contains an anion having at least two ion charge numbers, such as a phosphate ion, a sulfate ion, and a carbonate ion. In a preferred embodiment, the absorbent property modification polymer can cause the particles of Ir, modification absorbent are spontaneously connected through the absorbent property modification polymer in response to a urine application. The term "connect" used in the present, represents that a plurality of materials has the ability to connect with each other. Therefore, the absorbent gelling particles of the absorbent material can have the ability to connect to each other after urine is applied to the absorbent material. In a more preferred embodiment, the polymer of The modification of the absorbent property is a cationic polymer, which can be reactive with at least one component included in the urine. Preferably, the cationic polymer is capable of having an electrostatic interaction with an acid group, such as a carboxyl group of the absorbent polymer.

Therefore, in a further preferred embodiment, the cationic polymer is capable of binding both the anion included in the urine, and the absorbent polymer. Preferred cationic polymers can include polyamine or polyamine materials, which are reactive with at least one component included in the urine. The polyamine material preferably used in the present invention is selected from the group consisting of (1) polymers having primary amine groups (eg polyvinylamine, polyallylamine); (2) polymers having secondary amine groups (e.g., polyethyleneimine); and (3) polymers having tertiary amine groups (e.g., N, N-dimethylalkylamine).

Practical examples of the cationic polymer are, for example, polyethyleneimine, a modified polyethyleneimine, which is entangled by epihalogen hydrin on a water-soluble scale, polyamine, polyamidoamine modified by the ethyleneimine graft, polyetheramine, polyvinylamine, polyalkylamine, polyamidopolyamine and polyallylamine. . In preferred embodiments, a cationic polymer has an average molecular weight of at least 500, preferably 5,000, most preferably 10,000 or more. Cationic polymers having a weight average molecular weight of 500 or more, used in the present invention, are not limited to polymers that show an individual peak value (peak) in a molecular weight analysis by gel permeation chromatography, and Polymers having a weight average molecular weight of 500 or more can be used even if they exhibit a plural maximum value (peaks). A preferred amount of the cationic polymer is in the range from about 0.05 to 20 parts by weight against 100 parts by weight of the absorbent polymer particle, preferably from about 0.3 to 10 parts by weight, and most preferably from about 0.5 to 5 parts by weight. in weigh. 2. Absorbent Gelification Particles. (1) Chemical Composition The water-swellable, water-insoluble absorbent polymers useful in the present invention are commonly referred to as "hydrogel formers", "hydrocolloids", or "superabsorbent" polymers, and may include polysaccharides, such as carboxymethyl starch, carboxymethyl cellulose and hydroxypropyl cellulose; nonionic types, such as polyvinyl alcohol and polyvinyl ethers; cationic types such as polyvinyl pyridine, polyvinyl morpholinone, and N, N-dimethylaminoethyl or N, N-diethylaminopropyl acrylates and methacrylates, and their respective quaternary salts. Typically, the hydrogel-forming absorbent polymers, useful in the present invention, have a multitude of functional, anionic groups, such as sulfonic acid, and more typically carboxy groups. Examples of polymers suitable for use herein include those which are prepared from acid-containing, polymerizable, unsaturated monomers. Thus, such monomers include olefinically unsaturated acids and anhydrides containing at least one olefinic carbon-to-carbon double bond. More specifically, these monomers can be selected from olefinically unsaturated carboxylic acids and anhydrides, olefinically unsaturated sulfonic acids and mixtures thereof. Some monomers without acid, usually in minor amounts, may also be included to prepare the hydrogel-forming absorbent polymers herein. Such monomers without acid can include, for example, water-dispersible or water-soluble esters of acid-containing monomers, as well as monomers that do not contain carboxylic or sulfonic acid groups. Thus, optional non-acidic monomers may include monomers containing the following types of functional groups: carboxylic acid or sulfonic acid esters, hydroxyl groups, amide groups, amino groups, nitrile groups, quaternary ammonium salt groups, aryl groups (e.g., phenyl groups, such as those derived from styrene monomer). These acid-free monomers are well known materials and are described in greater detail, for example, in the U.S.A. 4,076,663 (Masuda et al.) Issued on February 28, 78, and patent of Jl _ _ E.U.A. 4,062,817 (Westerman) issued December 13, 1977, incorporated herein by reference. The carboxylic acid and olefinically unsaturated carboxylic acid anhydride monomers include the acrylic acids exemplified by the same acrylic acid, methacrylic acid, ethacrylic acid, chloroacrylic acid, a-cyanoacrylic acid, methacrylic acid (crotonic acid), phenylacrylic acid, acryloxypropionic acid, sorbic acid, chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid, sterilacrylic acid, itaconic acid, citroconic acid, mesaconic acid, glutaconic acid, maleic acid, fumaric acid, tricarboxyethylene anhydride and maleic acid . The olefinically unsaturated sulfonic acid monomers include aliphatic or aromatic vinylsulfonic acids, such as vinylsulfonic acid, allylsulfonic acid, vinyltoluenesulfonic acid and styrenesulfonic acid; sulphonic-acrylic and methacrylic acid, such as sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-methacryloxypropyl sulfonic acid and 2-acrylamide-2-methylpropanesulfonic acid. Preferred hydrogel-forming absorbent polymers for use in the present invention contain carboxy groups. These polymers include starch-acrylonitrile graft copolymers, hydrolysates, partially neutralized starch-acrylonitrile copolymers, hydrolysates, starch-acrylic acid graft copolymers, partially neutralized vinyl acetate copolymers of starch-acrylic acid copolymers. saponified acrylic ester, hydrolyzed acrylonitrile or acrylonitrile copolymers, lightly woven network polymers of any of the foregoing copolymers, partially neutralized polyacrylic acid, and lightly crosslinked polymers of partially neutralized polyacrylic acid work network. These polymers can be used either alone or in the form of a mixture of two or more different polymers. Examples of these polymer materials are described in the U.S.A. 3,661,875, U.S. Patent. 4,076,663, U.S. Patent No. 4,093,776, patent of E.U.A. 4,666,983, and US patent. 4,734,478. The highly preferred polymer materials for use in the manufacture of hydrogel-forming absorbent polymers are the lightly cross-linked network polymers of partially neutralized polyacrylic acids and their starch derivatives. Most preferably, the hydrogel-forming absorbent polymers comprise from about 50 to about 95%, preferably about 75%, of neutralized polyacrylic acid, lightly network interlaced (i.e., poly (sodium acrylate / acrylic acid)). The network interlacing makes the polymer substantially insoluble in water and, in part, determines the absorptive capacity and the extractable polymer content characteristics of the hydrogel-forming absorbent polymers. The procedures for interlinking these polymers by network, and the typical network interworking agents are described in greater detail in the U.S. patent. 4,076,663. In addition, hydrogel-forming absorbent polymers on the surface can preferably be used in the present invention. They have a higher level of interlacing near the surface than inside. As used herein, "surface" describes the boundaries of the particle, fiber, etc., that look out. For porous hydrogel-forming absorbent polymers (e.g., porous particles, etc.), exposed internal limits may also be included. A higher level of interlacing at the surface means that the level of functional interlacing for the absorbent polymer Hydrogel former near the surface, is generally higher than the level of functional interlayers for the polymer inside. The gradation in the intertwining of the surface towards the interior may vary, both in depth and in profile. In this way, for example, the depth of the interlacing of the surface can be shallow, with a '. relatively acute transition to a lower level of entanglement. Alternatively, for example, the depth of the surface entanglement can be a significant fraction of the dimensions of the hydrogel-forming absorbent polymer, with a wider transition. Depending on size, shape, porosity, as well as functional considerations, the degree and degree of surface interleaving may vary within a given hydrogel-forming absorbent polymer. For particulate hydrogel-forming absorbent polymers, the surface entanglement may vary with particle size, porosity, etc. Depending on the variations in the surface: volume ratio within the hydrogel-forming absorbent polymer (e.g., between small and large particles), it is not unusual for the total level of entanglement to vary within the material (e.g., be larger for the smaller particles). Surface entanglement is generally achieved after the final limits of the hydrogel-forming absorbent polymer have essentially been established (e.g., by grinding, extruding, foaming, etc.). However, it is also possible to effect surface entanglement concurrently with the creation of final limits. In addition, some additional changes in the boundaries may occur, even after introducing the surface entanglements.

A number of procedures for introducing surface entanglements are described in the art. These include those where: (i) a di- or polyfunctional reagent (e.g., glycerol, 1,3-dioxolan-2 -one, metal ions polyvalent, polyquaternary amines) capable of reacting with existing functional groups, within the hydrogel-forming absorbent polymer, is applied to the surface of the hydrogel-forming absorbent polymer; (ii) a di- or polyfunctional reagent that is capable of reacting with other reagents (1"additives and functional groups possibly existing within the hydrogel-forming absorbent polymer, so that it increases the level of entanglement on the surface, is applied to the surface (e.g., the addition of the monomer plus the interlayer and the initiation of a second polymerization reaction), (iii) no additional polyfunctional reagent is added, but additional reactions are induced between the components existing within the forming polymer of hydrogel, either during or after the primary polymerization process, to generalize a higher level of 0 entanglement at or near the surface (e.g., heating to induce the formation of anhydride entanglements and / or esters between groups of polymeric acid and / or hydroxyl of existing polymer and suspension polymerization processes, wherein the interleaver is 5 inherently present at higher levels near the surface); and (iv) other materials are added to the surface to induce a higher level of entanglement or otherwise reduce the surface deformability of the resulting hydrogel. Combinations of these surface entanglement procedures may also be employed, either concurrently or in sequence. In addition to the interlacing reagents, other components may be added to the surface to assist / control the interlacing distribution (e.g., the extent and penetration of the surface interlacing reagents). Suitable general methods for carrying out the surface entanglement of the hydrogel-forming absorbent polymers according to the present invention are described in U.S. Pat. 4,541,871 (Obayashi) issued on September 17, 1985; PCT application published W092 / 16565 (Stanley), published on lo. October 1992, published PCT application WO90 / 08789 (Tai), published August 9, 1990; published PCT publication WO93 / 05080 (Stanley), published on March 18, 1993; patent of E.U.A. 4,824,901 (Alexander) issued April 25, 1989; patent of E.U.A. 4,789,861 (Johnson), issued January 17, 1989; patent of E.U.A. 4,587,308 (Makita) issued May 6, 1986; patent of E.U.A. 4,734,478 (Tsubakimoto) issued March 29, 1988; patent of E.U.A. 5,164,459 (Kimura et al.) Issued November 17, 1992; published German patent application 4,020,780 (Dahmen) published on August 29, 1991; and European patent application published 509,708 (Gartner) published on October 21, 1992, and all incorporated herein by reference. Since the hydrogel-forming absorbent polymer is of one type (ie, homogeneous), polymer blends can also be used in the present invention. For example, mixtures of starch-acrylic acid graft copolymers and lightly cross-linked polymers of partially neutralized polyacrylic acid workings can be used in the present invention. (2) Physical Forms The absorbent gelling particles used in the present invention may have a size, shape and / or morphology that varies with respect to a wide scale. The absorbent gelling particles do not have a large ratio of larger dimension to smaller dimension (e.g., granules, flakes, powders, interparticle aggregates, interparticle aggregates, and the like) and may be in the forms fibers, foams, and the like. The hydrogel-forming absorbent polymers can also comprise mixtures with low levels of one or more additives, such as, for example, silica powder, surfactants, gum, binders, and the like. The components in this mixture They can be physically and / or chemically associated in such a way that the hydrogel-forming polymer component and the non-hydrogel-forming polymer additive are not easily physically separable. The hydrogel-forming absorbent polymers can be essentially non-porous or have a substantial internal porosity. For particles as described above, the particle size is defined as the dimension determined by the sieve size analysis. In this way, for example, a particle that is retained on a Normal Test Sieve of E.U.A. with apertures of 710 microns (e.g., Designation of Alternative Sieve Series E.U.A. No. 25) is considered to have a size greater than 710 microns; a particle passing through a sieve with apertures of 710 microns on a sieve with apertures of 500 microns (e.g., Alternative Sieve Designation Series US No. 35) is considered to have a particle size of between 500 and 710 microns; and a particle that passes through a sieve with openings of 500 microns is considered to have a size of less than 500 microns. The average particle size by mass of a given sample of hydrogel-forming absorbent polymer particles is defined as the particle size that divides the sample in half on a mass basis, ie, half the sample by weight it will have a particle size smaller than the average mass size, and half the sample will have a particle size greater than the average mass size. A method for plotting the normal particle size (wherein the percentage of the cumulative weight of the particle sample retained on or passing through a given sieve size aperture is plotted against the sieve size aperture on a paper of probability) is typically used to determine the average particle size in mass, when 50% of the mass value does not correspond to the size opening of a US Normal Test Sieve These methods to determine the particle sizes of the hydrogel-forming absorbent polymer particles, are further described in the patent of E.U.A. 5,061,259 (Goldman et al.) Issued October 29, 1991, which is incorporated herein by reference. For hydrogel-forming absorbent polymer particles useful in the present invention, the particles will generally range in size from about 1 to about 2,000 microns, most preferably from about 20 to 1,000 microns. The average particle size in mass will generally be from about 20 to about 1,500 microns, preferably from about 50 microns to about 1,000 microns, and most preferably from about 100 to 800 microns. Within these size scales, it is preferable to select larger or smaller particles depending on the need for faster or slower absorption kinetics. For example, for non-porous particles, the rate of swelling will generally be reduced with the increase in particle size. It is also preferable to select larger or smaller particles or cuts (fractions) of narrower size from larger or smaller particles from the bulk polymer to improve the permeability of the gel layer (i.e., increase the value of Saline Flow Conductivity (CFS)). For particles of some absorbent, hydrogel-forming polymers, it has been found that narrower scale-size cuts that generally contain larger particle sizes, within the size scales specified above, have higher CFS values without any degradation significant in other properties of the hydrogel-forming absorbent polymer, such as such as the performance under pressure (RBP) and the level of extractable polymer. Thus, for example, it may be useful to use a size cut that has an average mass size on the scale of about 500 to about 710 microns, where only the minimum mass fractions of the particles have sizes that are larger than approximately 710 microns or less than approximately 500 microns. Alternatively, a wider cut may be useful, where the particles generally have a size on the scale of about 150 microns to about 800 microns.

D. Procedure for Making Absorbent Materials In summary, the absorbent materials used in the present invention can be made by mixing an absorbent property modification polymer, reactive with at least one component included in the urine, with a plurality of absorbent gelling particles that they comprise an absorbent polymer insoluble in water, swellable with water. More specifically, the mixing can be done by applying the absorbent property modification polymer on the absorbent gelling particles. As used herein, the term "apply over" means that the absorbent property modification polymer will be on at least a portion of the surface area of the absorbent gelling particles. Preferably, the absorbent property modification polymer is applied over the entire surface of the absorbent gelling particles. In the case where the absorbent property modification polymer is in the form of a small particle or powder, the absorbent property modification polymer can be applied by any technique and apparatus used to apply a material to another material. In another case, wherein the absorbent property modification polymer is in the form of a liquid, the absorbent property modification polymer can be applied by various techniques and apparatuses used to apply a liquid to a material. As a result, the absorbent materials of the present invention can be obtained in the forms of the blends described above. In a preferred embodiment, an absorbent property modification polymer (e.g., a cationic polymer or a polyamine or poly-imine material), which is reactive with at least one component included in the urine, is dissolved in a solvent to make a solution. The polymer of modification of absorbent property can be dissolved in the solvent by various techniques and apparatuses used to dissolve a material to a solvent known in the art. In highly preferred embodiments, an organic solvent is used as the solvent. Preferably, the concentration of the absorbent property modification polymer in the solution by weight is from about 0.05% to 60%, most preferably from 0.5% to 30%. In preferred embodiments, an absorbent property modification polymer, which is insoluble in an organic solvent, can be used. In highly preferred embodiments, a polar organic solvent is used as the solvent. In such embodiments, a solvent mixture of a hydrophilic organic solvent and water is used, as the solvent for the absorbent property modification polymer. Non-limiting examples of the preferred organic solvent include: low molecular weight alcohols such as methanol, ethanol, or propanol; acetone; dimethyl formamide (DMF); dimethyl sulfoxide (DMSO); hexylmethylphosphoric triamide (HMPT); and mixtures thereof. In alternative preferred embodiments, non-polar solvents such as hexane, toluene, xylene and benzene can be used as one of the organic solvents. Preferably, the weight ratio of the organic solvent to water is about at least 50:50, most preferably about 70:30 to 98: 2. After preparing the solution, it is applied to the absorbent gelling particles, thus making an intermittent mixture. More specifically, an amount of the solution is applied to the absorbent gelling particles. The solution can be applied by several techniques and devices used to apply a solution to a Material, including coating, pouring, dripping, spraying, atomizing, condensing, or immersing the liquid mixture in the absorbent gelling particles. Thus, in the intermittent mixture, the solution will be on at least a portion of the surface area of the gelling particles absorbers. Preferably, the solution will be on the entire surface of the absorbent gelling particles. The amount of the absorbent property modification polymer, which is sufficient to effect an improvement in the physical properties of the absorbent material, can vary in a number of factors such as the chemical composition of the absorbent polymer and the physical forms of the gelling particles. absorbents, e.g., the particle size of the absorbent particles, and the chemical composition and molecular weight of the absorbent property modification polymer, as well as in the method of application thereof. In preferred embodiments, the weight ratio of the absorbent property modification polymer to the absorbent gelling particles is from about 0.05: 100 to about 20: 100, most preferably from 0. 5: 100 to 5: 100, approximately. After intermittent mixing, at least a portion of the solvent is removed from it. Preferably, at least about 80%, preferably more than 95%, and most preferably about 100% of the solvent is removed from the intermittent mixture. The removal of the solvent can be done by any technique and apparatus used to separate or remove liquids from liquid-solid mixtures, including evaporation, filtration, washing, or a combination thereof. In a preferred embodiment, the polymer of modification of physical property is applied on the absorbent gelling particles after the treatment of the surface entanglement of the absorbent gelling particles. On the one hand, in another embodiment, the polymer of modification of physical property is applied on the absorbent gelling particles before the treatment of the surface entanglement of the absorbent gelling particles. In addition, in a further embodiment, the application of the polymer for modification of physical property and the treatment of entanglement can be carried out at the same time. It should be noted that, in some embodiments, the polymer of modification of physical property can be used as an entanglement agent. In preferred embodiments, the resulting absorbent materials may have a number of shapes and sizes. For example, the absorbent materials may typically be in the form of particles, sheets, films, cylinders, blocks, fibers, filaments, or other shaped elements. Most preferably, the absorbent material is particulate.

E. Absorbent Articles that use Absorbing Members. The absorbent members according to the present invention can be used for many purposes in many fields of use. For example, absorbent members can be used to pack containers; for drug delivery devices; devices for cleaning wounds; devices for the treatment of burns; ion exchange column materials; construction materials; materials for agriculture or horticulture, such as sheets for seeds or materials to retain water; and industrial uses, such as mud or oil water removal agents, materials to prevent moisture formation, desiccants, and materials for moisture control. Due to the unique properties of the absorbent materials used in the present invention, they are especially suitable for use as absorbent cores in absorbent articles, especially disposable absorbent articles. As used herein, the term "absorbent article" refers to articles that absorb and contain body fluids, and more specifically to articles that are placed against or close to the wearer's body to absorb and contain the various discarded body fluids. . In addition, "disposable" absorbent articles are those that claim to be discarded after a single use (i.e., the original absorbent article in its entirety, do not intend to be washed or otherwise restored or reused as an absorbent article, although certain materials or the entire absorbent article can be recirculated, reused or formed). In general, an absorbent article comprises: (a) a liquid-permeable topsheet, which is located adjacent to the wearer's body; (b) a liquid impermeable backsheet, which is located away from the wearer's body and adjacent to the wearer's clothing; and (c) an absorbent core X positioned between the topsheet and the topsheet. The absorbent core comprises at least one of the absorbent members described above. In a preferred embodiment, the absorbent core is one of the absorbent members described above. Preferably, the absorbent core further comprises a web of substrate, wherein the absorbent material is bonded to the substrate web. Alternatively, the absorbent core further comprises a wrapping band enclosing the absorbent material. In a further alternative embodiment, the absorbent core further comprises two-ply tissue papers wherein the absorbent material is distributed between the two-ply tissue papers. In highly preferred embodiments, the absorbent material in the absorbent core has a basis weight of from about 60 g / m2 to about 1,500 g / m2, preferably from about 100 g / m2 to about 1,000 g / m2, most preferably 150 g / m2. m2 to 500 g / m2, approximately, of the absorbent material. In some preferred embodiments, the absorbent core or absorbent member may further comprise fibers or lint pulp (fibrous or fiber material), more specifically, nonabsorbent gelling fibers. Said fiber material can be used as reinforcing members in the absorbent core, improving the handling of core fluid, as well as a co-absorbent with the absorbent polymers.

Preferably, the core or absorbent member includes from about 40% to about 100% by weight of the absorbent material and from about 60% to about 0% by weight of said non-absorbent gelling fiber material distributed within the absorbent material. Any type of fiber material, which is suitable for use in conventional absorbent products, can be used in the absorbent core or absorbent member herein. Specific examples of said fiber material include cellulose fibers, improved cellulose fibers, rayon, polypropylene, and polyester fibers such as polyethylene terephthalate (DACRON), hydrophilic nylon (HYDROFIL), and the like. Examples of other fiber materials for use in the present invention, in addition to those already discussed are, hydrophobic, hydrophilized fibers, such as thermoplastic fibers treated with a surfactant or treated with silica derived from, for example, polyolefins, such as polyethylene or polypropylene, polyacrylics, polyamides, polystyrenes, polyurethanes and the like. In fact, hydrophobic, hydrophilized fibers, which are in and are in themselves not very absorbent and which, therefore, do not provide bands of sufficient absorbent capacity to be useful in conventional absorbent structures, are suitable for use in the absorbent core by virtue of its good movement properties by wicking effect. This is because, in the absorbent core of the present, the inclination of the movement by wick effect of the fibers is important, but more important than the absorbent capacity of the same fiber material, due to the high speed of consumption of fibers. fluid and the lack of gel blocking properties of the absorbent core. In the present, it is preferred to use synthetic fibers as the fiber component of the absorbent core. Most preferred are polyolefin fibers, preferably polyethylene fibers. Other cellulosic fiber materials that may be useful in certain absorbent cores or absorbent members thereof are chemically hardened cellulosic fibers. Preferred chemically hardened cellulosic fibers are hardened, twisted, crimped cellulosic fibers which can be produced by internal interlacing of cellulose fibers with an entanglement agent. The hardened, twisted, crimped cellulose fibers suitable for use as the hydrophilic fiber material herein are described in greater detail in the U.S.A. 4,888,093 (Dean et al.) Issued December 19, 1989; patent of E.U.A. 4,889,595 (Herrón et al.), Issued December 26, 1989; patent of E.U.A. 4,889,596 (Schoggen et al.) Issued December 26, 1989; patent of E.U.A. 4,889,597 (Bourbon et al.), Issued December 26, 1989; and patent of E.U.A. 4,898,647 (Moore et al.) Issued February 6, 1990, all incorporated herein by reference.

A preferred embodiment of the absorbent article is a diaper. As used herein, the term "diaper" refers to a garment generally worn by infants and incontinent persons, which is worn around the lower torso of the wearer. A preferred diaper configuration for a diaper comprising an absorbent core is generally described in U.S. Pat. 3,860,003 (Buell) issued on January 14, 1975, which is incorporated herein by reference. Alternately preferred configurations for disposable diapers herein are also described in the U.S.A. 4,808,178 (Aziz et al.) Issued February 28, 1989; patent of E.U.A. 4,695,278 (Lawson) issued September 22, 1987; patent of E.U.A. 4,816,025 (Foreman) issued on March 28, 1989; and patent of E.U.A. 5,151,092 (Buell et al.) Issued September 29, 1992, all are incorporated herein by. reference. Another preferred embodiment of the disposable absorbent article is a catamenial product. Preferred catamenial products comprise an open top sheet of formed film, as described in US Pat. 4,285,343 (McNair) issued August 25, 1981; patent of E.U.A. 4,608,047 (Mattingly) issued August 26, 1986; and patent of E.U.A. 4,687,478 (Van Tilburg) issued August 18, 1987, all incorporated herein by reference.

Preferred catamenial products may comprise wings, side flaps and other structures and elements, as described in the application of E.U.A. copendiente, commonly assigned Series No. 984,071, to Yasuko Morita, entitled "Absorbent Article Having Elasticized Side Flaps," No. of attorney JA-09RM, filed on November 30, 1992, incorporated herein by reference. However, it should be understood that the present invention is also applicable to other absorbent articles known commercially by other names, such as incontinent briefs, incontinent adult products, trainers, diaper inserts, facial tissues, paper towels and the like. .

F. Synthetic Urine Test Methods The specific synthetic urine used in the test methods of the present invention is referred to herein as "Synthetic Urine". Synthetic urine is commonly known as Jayco SynUrine or Jayco Synthetis Uriñe and is available from Jayco Pharmaceuticals Company of Camp Hill, Pennsylvania. The formula for Synthetic Urine is: 2.0 g / 1 KCl; 2.0 g / 1 Na2SO4; 0.85 g / 1 of (NH4) H2P04; 0.15 g / 1 (NH4) 2HP04; 0.19 g / 1 CaC12 and 0.23 g / 1 MgCl2. All chemical products are reactive grade. The pH of Synthetic Urine is in the range of 6.0 to 6.4. 1. Gel Volume Density Test (DVG) This test determines the gel volume density (DVG) of an absorbent material that swells in Jayco's synthetic urine. The DVG is the weight per unit volume of a swollen absorbent material, including the gaps inherent in the swollen gel material, as tested. The objective of this test is to analyze the porosity of an absorbent material in the wet state. The DVG of an absorbent material is used as a measure of the gel porosity of an absorbent material after swelling in Jayco's synthetic urine. The gel porosity here means the void fraction in the swollen absorbent material or the volume volume of the gel layer in volume that is not occupied by the gel. An absorbent material having a lower DVG probably has more voids, in other words it has a higher porosity in the wet state. (1) Apparatus Figure 1 shows a suitable apparatus for measuring DVG. This apparatus comprises a cylinder 110, a cup-type piston 140, a weight 130 that fits inside the piston 140, and a flat-bottomed TEFLON tray 120. the cylinder 110 is covered with a transparent bar, LEXAN, (or equivalent, for example acrylic rod), and has an internal diameter of 6.00 cm (area = 28.27 cm2), with a wall thickness of approximately 0.5 cm, and a height of approximately 5.0 cm. The bottom of the cylinder is facing a stainless steel screen 150 of 400 mesh number which is biaxially stretched at a tension, before joining. The piston 140 is in the shape of a TEFLON cup and is machined to fit the cylinder 110 within tension tolerances. The weight 130 of stainless steel is machined to fit within the piston 140. The combined weight of the piston 140 and the weight 130 is 199 g, which corresponds to a pressure of 0.00703 kg / cm2 for an area of 28.27 cm2. The thickness of the gel layer 160 in the cylinder 110 is measured to an accuracy of approximately 0.05 mm. Any method having the requisite accuracy can be used, since the weights are not removed and the gel layer is not further disordered during the thickness measurement. It is acceptable to use a calibrator (e.g., Digimatic Caliper, Mitutoya Corp., Kyoto, or equivalent) to measure the gap between the top of the TEFLON piston 140 and the top of the cylinder 110, relative to this gap, without any absorbent material in the cylinder. The DVG measurement is carried out at room temperature. In this test, Jayco synthetic urine was used. (2) Procedure An aliquot of 0.9 g of absorbent material was added to the cylinder 110 and dispersed evenly over the 150 screen. For most absorbent materials, the moisture content is typically less than 5%. For these, the amount of absorbent material to be added can be determined on a wet weight basis (as such). For an absorbent material having a moisture content greater than about 5%, the weight of the added absorbent material must be corrected for moisture (ie, the added absorbent material should be 0.9 gm on a wet basis). Care must be taken to prevent the absorbent material from adhering to the cylinder walls. The piston 140 is inserted into the cylinder 110 and placed on top of the absorbent material 160. The weight 130 is then placed on the piston 140. The piston / cylinder apparatus with the absorbent material is then transferred to a tray 120 of TEFLON, flat bottom. 18 milliliters of Jayco's synthetic urine is added to tray 120. Time is recorded as soon as Jayco's urine is emptied into tray 120. Jayco's synthetic urine from the tray passes through 150 stainless steel sieve and it is absorbed by the absorbent material 160. As the absorbent material absorbs the fluid, a layer of gel is formed in the cylinder 110. After a period of 30 minutes, the thickness of the gel layer is determined. Consequently, the predetermined layer of the swollen absorbent material has been prepared for the measurement of DVG. The gap between the upper part of the TEFLON piston 140 and the upper part 5 of the cylinder 110 is measured (Ls). It is also measured relative to this gap but without any absorbent material in the cylinder (Lc). This difference between Lc and Ls is the thickness of the gel layer of the absorbent material (Lg). Then the piston / cylinder apparatus with the swollen gel is weighted (Ws). l? "The DVG is calculated according to this equation: DVG = (Ws - Wc) / (28.27 x Lg) where DVG is the value of the gel volume density (g / cm3), Ws is the total weight of the piston / cylinder apparatus with the swollen gel (g), Wc is the weight of the piston / cylinder without the absorbent material (g), and Lg is the thickness of the swollen gel layer (cm). 2. Saline Flow Conductivity Test (CFS) This test determines the Flow Conductivity of Saline (CFS) of the gel layer formed from the hydrogel-forming absorbent polymer that swells in Jayco synthetic urine under confining pressure. The objective of this test is to analyze the ability of the hydrogel layer formed from a hydrogel-forming absorbent polymer, to Acquire and distribute the body fluids when the polymer is present at high concentrations in an absorbent member and is exposed to mechanical pressures of use. Darcy's law and steady-state flow methods are used to determine the conductivity of saline flow. (See, for example, "Absorbency," ed by PK Chatterjee, Elsevier, 1985, pp. 42-43 and "Chemical Ingineering Vol. II," third edition, JM Coulson and JF Richardson, Pergamon Press, 1978, p. 125-127). A predetermined layer of swollen absorbent material used for CFS measurements is formed by swelling an absorbent material in Jayco's synthetic urine over a period of 60 minutes. The hydrogel layer is formed and its flow conductivity is measured under a mechanical confining pressure of approximately 2 kPa. The flow conductivity is measured using a 0.118 M NaCl solution. For a gel-forming absorbent polymer, whose Jayco synthetic urine consumption against time has been substantially leveled, it was found that this concentration of NaCl maintains the thickness of the Hydrogel layer substantially constant during the measurement. For some gel-forming absorbent polymers, small changes in the thickness of the hydrogel layer may occur as a result of swelling of the polymer, deflation of the polymer and / or changes in the porosity of the hydrogel layer. A constant hydrostatic pressure of 4920 dynes / cm2 (5 cm NaCl of 0.118 M) is used for the measurement. The flow rate is determined by measuring the amount of solution flowing through the hydrogel layer as a function of time. The flow velocity may vary with respect to the duration of the measurement. The reasons for the variation of flow velocity include changes in the thickness of the hydrogel layer and changes in the viscosity of the interstitial fluid, since the fl ow initially occurs in the interstitial gaps (which, for example, may contain polymer Removable dissolved) is replaced with a NaCl solution. If the flow rate depends on time, then the initial flow velocity, typically obtained by extrapolating the measured flow rates at a time of zero, is used to calculate the flow conductivity. This saline flow conductivity is calculated from the initial flow velocity, dimensions of the hydrogel layer and hydrostatic pressure. A suitable apparatus 610 for this test is shown in Figure 2. This apparatus includes a constant hydrostatic head reservoir generally indicated with 612, which sits on a laboratory jacket indicated generally with 614. The reservoir 612 has a cap 616 with a capped vent indicated with 618, so that additional fluid can be added to the reservoir 612. An open end tube 620 is inserted through the cap 616 to allow air to enter the reservoir 612 for the purpose of supplying fluid to a reservoir. constant hydrostatic pressure. The lower end of the tube 620 is located in order to maintain the fluid in the cylinder 634 at a height of 5.0 cm above the bottom of the hydrogel layer 668 (see Figure 2). The reservoir 612 is provided with a supply tube 622 generally in the shape of L, which has an inlet 622a which is below the surface of the fluid in the reservoir. The supply of fluid through the tube 622 is controlled by the stopcock 626. The tube 622 supplies fluid from the reservoir 612 to a piston / cylinder assembly generally indicated by 628. Below the assembly 628, there is a support screen (not shown) and a collection tank 630 that sits on a laboratory balance 632. Referring to Figure 2, assembly 628 basically consists of a cylinder 634, a piston generally indicated with 636 and a cover 637 provided with holes for the piston 636 and the supply tube 622. As shown in Figure 7, the outlet 622b of the tube 622 is cocked below the lower end of the tube 620 and thus will also be below of the fluid surface (not shown) in the cylinder 634. As shown in Figure 3, the piston 636 consists of an arrow 638, LEXAN *, generally cylindrical, having a concentric cylindrical hole 640 borne on the longitudinal axis of the cylinder. the arrow. Both ends of arrow 638 are machined to provide ends 642 and 646. A weight indicated at 648 rests on end 642 and has a cylindrical hole 648a carried through its center. Inserted on the other end 646 is a Teflon piston head 650, generally circular, having an annular depression 652 at the bottom thereof. The piston head 650 is dimensioned to move slidably within the cylinder 634. As particularly shown in Figure 4, the piston head 650 is provided with 4 concentric rings of 24 cylindrical holes, each generally indicated with 654, 656, 658 and 660. As can be seen in Figure 4, the concentric rings 654 to 660 fit within the area defined by the depression 652. The holes in each of these concentric rings are brought from the top to the bottom of the Piston head 650. The holes in each ring are separated by approximately 15 degrees and deflected by approximately 7.5 degrees from the holes in the adjacent rings. These holes in each ring have a progressively smaller diameter going inward from ring 654 (diameter 0.51816 cm) to ring 660 (diameter 0.28194 cm). The piston head 650 also has a cylinder bore 662 carried in the center thereof to receive the end 646 of the arrow 638.

As shown in Figure 3, a circular glass disk, fragmented 664, fits within the depression 652. Attached to the lower end of the cylinder 634 is a stainless steel cloth sieve, 666, of mesh No. 400 which it is biaxially stretched to the tension before joining. The hydrogel-forming absorbent polymer sample, indicated with 668, is supported on the 666 sieve. The cylinder 634 is carried from a transparent bar of LEXAN "O equivalent and has an inside diameter of 6.00 cm (area = 28.27 cm2), a thickness of approximately 0.5 cm, and a height of approximately 6.0 cm The piston head 650 is machined from a solid Teflon rod, has a height of 1.58 cm and a diameter that is slightly smaller than the internal diameter of cylinder 634, In this case, the depression 652 has a diameter of 56 mm and a depth of 4 mm The hole 662 in the center of the piston head 650 has a threaded opening 1.58 cm (18 threads / 2.54 cm) for the end 646 of the arrow 638. The fragmented disc 664 is chosen for its high permeability (eg, Chemglass Cat No. CG-201-40, diameter 60 mm; X-Coarse Porositi), and he Element so that it fits snugly within the depression 652 of the piston head 650, with the bottom of the disk coming out with the bottom of the piston head. The arrow 638 is machined from a LEXANR bar and has an external diameter of 2.22 cm and an internal diameter of 0.635 cm. The end 646 has a length of approximately 1.27 cm and is threaded to match the hole 662 in the piston head 650. The end 642 has a length of approximately 2.54 cm and a diameter of 1.58 cm, forming an annular shoulder to support the weight of stainless steel 648. The fluid passing through the hole 640, in the arrow 638, can enter directly to the fragmented disc 664. The weight of annular stainless steel 648 has a diameter of 1.58 cm, so that it slides on the end 642 of the arrow 638 and rests on the annular shoulder formed therein. The combined weight of the fragmented glass disk 664, piston 636, and weight 648 is equal to 596 g, which corresponds to a pressure of 0.02109 kg / cm2 for an area of 28.27 cm2. The cover 637 is machined from LEXANR or its equivalent and is sized to cover the upper part of the cylinder 634. It has an opening of 2.22 cm in the center thereof for the arrow 638 of the piston 636 and a second opening near its rim for supply tube 622. Cylinder 634 rests on a stiff, 16-mesh stainless steel support screen (not shown) or equivalent. This support screen is sufficiently permeable, so as not to impede the flow of fluid to the collection tank 630. The support screen is generally used to support the cylinder 634, when the flow velocity of the salt solution through the assembly 628 is greater than about 0.02 g / sec. For flow rates less than about 0.02 g / sec, it is preferable that there is a continuous fluid path between the cylinder 634 and the collection tank. The 0.118 M NaCl solution is prepared by dissolving 6,896 g of NaCl (Baker Analyzed Reagent reagent, or equivalent, at 1.0 liters with distilled water) An analytical equilibrium 632 with an accuracy of 0.01 g lt ~ (e.g., Mettler PM4000 or equivalent) is typically used to measure the amount of fluid flowing through the hydrogel layer 668, when the flow rate is about 0.02 g / sec or greater.The equilibrium is preferably interfaced to a computer for Inspect the amount of fluid against time. The thickness of hydrogel layer 668 in cylinder 634 is measured to an accuracy of about 0.1 mm. Any method that has the requisite accuracy can be used, as long as the weights are not removed and the hydrogel layer is not also compressed or disordered during the measurement. It is acceptable to use a calibrator (e.g., Manostat 15-100-500 or equivalent) to measure the vertical distance between the bottom of the 648 stainless steel weight and the top of the 637 deck, relative to this distance with none layer of hydrogel 668 in cylinder 634.

The CFS measurement is performed at room temperature (ie, 20 ° -25 ° C) and is carried out as follows: An aliquot of 0.9 g of gel-forming absorbent polymer (corresponding to a basis weight of 0.032) is added. g / cm2) to cylinder 634 and evenly distributed over sieve 666. For most hydrogel-forming absorbent polymers, the moisture content is typically less than 5%. Therefore, the amount of gel-forming absorbent polymer to be added can be determined on a dry weight basis (as such). For hydrogel-forming absorbent polymers having a moisture content of about 5%, the weight of the added polymer must be corrected for moisture (ie, the added polymer should be 0.9 g on a dry weight basis). Care must be taken to prevent the hydrogel-forming absorbent polymer from adhering to the cylinder walls. The piston 636 (minus the weight 648) with the disc 664 placed in the depression 652 of the piston head 650, is inserted into the cylinder 634 and placed on top of the absorbent polymer 668, hydrogel-forming. If necessary, the piston 636 can be turned moderately to more evenly distribute the hydrogel-forming absorbent polymer over the sieve 666. The cylinder 634 is covered by the cover 637 and the weight 648 is then placed over the end 642 of the arrow 638 A fragmented disc (thick or extra-thick), having a larger diameter than that of the cylinder 634, is placed in a flat bottom, wide / shallow vessel, which is filled at the top of the disc fragmented with synthetic urine from Jayco. The piston / cylinder assembly 628 is then placed on top of this fragmented glass disk. Fluid from the container passes through the fragmented disc and is absorbed by the hydrophilic absorbent polymer 668. As the polymer absorbs fluid, the hydrogel layer is formed in the cylinder 634. After a period of 60 minutes, the hydrogel layer is formed. determines the thickness of the hydrogel layer. Care must be taken that the hydrogel layer does not lose fluid or take in air during this procedure. The piston / cylinder assembly 628 is then transferred to the apparatus 610. The support screen (not shown) and any gap between it and the piston / cylinder assembly 628 is presaturated with saline. If the fragmented funnel 718 of the PUP 710 apparatus is used to support the cylinder 634, the surface of the fragmented funnel must be raised, minimally, relative to the height of the fluid in the collection tank, the valves, between the fragmented funnel and the collection tank, being in the open position. (The elevation of the fragmented funnel must be sufficient, so that the fluid passing through the hydrogel layer does not accumulate in the funnel). The CFS measurement is started by adding a NaCl solution through the hole 640 in the arrow 638, to expel the air from the piston head 650 and then return the stopcock 626 to an open position so that the supply pipe 622 supply fluid to the cylinder 634 at a height of 5.0 cm above the bottom of the hydrogel layer 668. Although the measurement is considered to be initiated (t0) at the time when the NaCl solution is first added, the time in which a stable hydrostatic pressure is obtained, which corresponds to 5.0 cm of saline solution and a stable flow velocity (ts). (Time ts should typically be around one minute or less). The amount of fluid that passes through the 668 hydrogel layer against time, it is determined gravimetrically during a period of 10 minutes. After the time has expired, the piston / cylinder assembly 628 is removed and the thickness of the hydrogel layer 668 is measured. Generally, the change in the thickness of the hydrogel layer is less than about 10%. In general, the flow velocity does not need to be constant. The time-dependent flow velocity through the system, Fs (t) is determined, in units of g / sec, by dividing the incremental weight of the fluid passing through the system (in grams) by the incremental time (in seconds) .

Only the data collected during the times between ts and 10 minutes are used for calculations of the flow velocity. The results of the flow velocity between ts and 10 minutes are used to calculate the value for Fs (t = 0), the initial flow velocity through the hydrogel layer. Fs (t = 0) is calculated by extrapolating the results of a fixation of the last squares of Fs (t) against the time at t = 0. For a layer having a very high permeability (e.g., a flow rate greater than about 2 g / sec), it may not be practical to collect the fluid during the total 10 minute period. For flow rates greater than about 2 g / sec, the collection time can be reduced in proportion to the flow velocity. For some hydrogel-forming absorbent polymers, which have extremely low permeability, the absorption of the fluid by the hydrogel competes with the transport of fluid through the hydrogel layer and whether or not there is no fluid flow through the layer. of hydrogel and to the reservoir or that, possibly, there is a net absorption of fluid outside the PUP reservoir. For these hydrogel layers with extremely low permeability, it is optional to extend the time for the absorption of Jayco SynUrine to longer periods (e.g., 16 hours). In a separate measurement, the flow velocity through the apparatus 610 and the piston / cylinder assembly 628 (F) is measured as described above, except that no hydrogel layer is present. If Fa is much greater than the flow velocity through the system when the hydrogel layer is present, Fs, then no correction is necessary for the flow resistance of the CFS apparatus and the piston / cylinder assembly. In this limit, F = Fs, where F is the contribution of the hydrogel layer to the flow velocity of the system. However, if this requirement is not satisfied, then the following correction is used to calculate the value of F "of the values of Fc and F: Fpg = (FaxFs / '(F3-Fs) The conductivity of saline flow (K) of the hydrogel layer is calculated using the following equation: K = { Fg (t = 0) xL0.}. / { xAxP.}., where Fg (t = 0) is the flow velocity in g / sec determined from the regression analysis of the results of the flow velocity and any correction due to the flow resistance of the assembly / apparatus, L0 is the initial thickness of the hydrogel layer in centimeters, it is the density of the NaCl solution in g / cm2, A is the area of the hydrogel layer in cm2, P is the hydrostatic pressure in dynes / cm2, and the salinity flow conductivity, K, is in units of cm3 sec / g. must report the average of the three determinations. 3. Ball Resistance Resistance Test (RRB) This test determines the ball burst resistance (RRB) of an absorbent material in the wet state. The RRB of an absorbent material is the force (peak load, in grams) required to rupture the gel layer of an absorbent material that swells in Jayco synthetic urine under procedures specified in this test method. The RRB of an absorbent material is used to evaluate the moisture integrity of an absorbent material that swells in Jayco synthetic urine. (1) Sampling Apparatus Figure 5 shows an adequate sampling device for the measurement of RRB. This apparatus comprises an internal cylinder 270, which is used to contain a layer of absorbent material 260, an external cylinder 230, a flat bottom tray 240 of TEFLON, a cover layer 220 internal cylinder, and a weight of 210 stainless steel The inner cylinder 270 is carried from a transparent LEXAN bar (or equivalent, for example an Acrylic bar) and has an internal diameter of 6.00 cm (area = 28.27 cm2), with a thickness of approximately 0.5 cm, and a height of approximately 1.50 cm. The external cylinder 230 is taken from a transparent LEXAN bar (or equivalent), for example Acrylic bar) and has an internal diameter that is slightly larger than the outer diameter of the inner cylinder 270, so that the inner cylinder 270 fits inside the outer cylinder 230 and slides freely. The external cylinder 230 has a wall thickness of approximately 0.5 cm and a height of approximately 1.00 cm. The bottom of the external cylinder 230 is facing the 400 mesh No. 400 stainless steel screen, which is biaxially stretched to the tension before joining. The cover plate 220 of the inner cylinder is made of a glass plate with a thickness of 0.8 cm and a weight of 500 g. The weight 210 of stainless steel has a weight of 1,700 g. (2) Retrieval Tester For this test a voltage tester is used with a burst test load cell (Intelect-II-STD Voltage Tester, made by Thwing-Albert Instrument Co., Pennsylvania). Referring to Figure 5, this apparatus comprises a lower circular sample plate 280 which is mounted on a stationary crosshead 310 provided on top of a double screw instrument, a force sensing load cell 330 equipped with a ball-shaped probe 290, polished stainless steel, a crosshead 320 in motion, and a top-fit plate 300 which is used to hold a sample 260, pneumatically. The lower adjustment plate 280 is mounted on the stationary crosshead 310. The force sensing load cell 330 is equipped with the probe 290. Both the lower adjustment plate 280 and the upper adjustment plate 300 have a diameter of 115 mm, a thickness of 2.9 mm, and a circular opening with a diameter of 18.65 cm. The ball-shaped probe 290, made of polished stainless steel, has a diameter of 15.84 mm. Crosshead 320 in motion moves upward, causing probe 290 to contact and penetrate the sample 260. When probe 290 penetrates sample 260, the test is considered complete, and the test result data is deploy and register.

I r (3) Procedure Referring to Figure 5, the inner cylinder 270 is inserted into the outer cylinder 230. An aliquot of 1.4 g of an absorbent material is added to the inner cylinder 270 and uniformly dispersed on the 400 mesh stainless steel screen of the bottom by means of moderate agitation and / or corking of the assembled cylinders. The cylinders assembled with the absorbent material are transferred to the TEFLON flat bottom pan 240, and the cover plate 220 of the inner cylinder is placed on the inner cylinder 270. To the flat bottom tray 240, of TEFLON, 42.0 milliliters of Jayco synthetic urine is applied. Jayco Synthetic Urine from TEFLON Flat Bottom Tray 240 passes through 250 stainless steel sieve. All applied urine is absorbed by the absorbent material 260 for 5 minutes. Then, the weight of stainless steel 210 is placed on the cover plate 220 of the inner cylinder. After an additional 25 minutes, the weight of stainless steel 210 and cover plate 220 of the inner cylinder are removed. Consequently, the predetermined layer 260 of the swollen absorbent material for the measurement of the DVG has been prepared. The inner cylinder 270 with the gel layer of absorbent material 260 is immediately transferred to the Rescue Tester for the RRB Test. Referring to Figure 6, the inner cylinder 270 with a gel layer of absorbent material 260 is placed on the lower adjustment plate 280 and is pneumatically attached with the upper adjustment plate 300. Using a rupture sensitivity of 10.00 g and a Test speed of 12.70 cm / minute and starting the test by pressing the Test switch. The crosshead 320 in motion moves upward until the polished, stainless steel ball-shaped probe 290 penetrates the gel layer of absorbent material 260. After a test burst is recorded, the crosshead 320 in movement returns to the starting position. The RRB is expressed as grams of peak load. The average of the three determinations must be reported. 4. Compression Recovery Test (RC) This test determines the compression recovery of an absorbent material that has swollen in Jayco synthetic urine. Compression recovery (RC) is the degree to which an absorbent material, in the wet state, has returned to its original shape when subjected to compression under procedures specified in this test method. The RC 5 of an absorbent material is used to evaluate the moisture integrity of an absorbent material that has swollen in Jayco synthetic urine, and is related to the ability of an absorbent material, in a wet state, to resume its original shape after have been subjected to tensional forces l. and torsional intensity and direction variations during normal use. CR is also related to the tension or good adjustment of an absorbent material in the wet state. (1) Sampling Apparatus 15 A suitable sampling apparatus for the measurement of RC is similar to the apparatus used in the RRB test (as shown in Figure 5), but has a higher height than the latter. The apparatus for measuring the RC comprises an internal cylinder 270, which is used to contain a layer of absorbent material 260, an external cylinder 230, a round bottom tray 240 of TEFLON, a cover plate 220 of internal cylinder, and a weight of stainless steel 210. The internal cylinder 270 is carried from a transparent LEXAN bar (or equivalent) , for example an Acrylic bar) and has an internal diameter of 6.00 cm (area = 28.27 cm2), with a thickness of approximately 0.5 cm, and a height of approximately 2.00 cm. The external cylinder 230 is carried from a transparent LEXAN rod (or equivalent, for example Acrylic rod) and has an internal diameter that is slightly larger than the external diameter of the inner cylinder 270, so that the inner cylinder 270 fits within the external cylinder 230 and slides freely. The external cylinder 230 has a wall thickness of approximately 0.5 cm and a height of approximately 1.00 cm. The bottom of the external cylinder 230 is facing the 250 mesh stainless steel screen No. 400, which is biaxially stretched to the tension before joining. The cover plate 220 of the inner cylinder is made of a glass plate with a thickness of 8.00 cm and a weight of 530 g. The weight 210 of stainless steel has a weight of 1.672 g. (2) Compression Tester In this method a Handy Compression Tester (KES-G5, made by Kato Tech Co., LTD., Kyoto) was used. Referring to Figure 7, the mechanical part of this apparatus comprises a compression plate 310, a charge indicator 350 which is connected to the compression plate 310, a drive mechanism 360 and a specimen group 320. A charge indicator 350 is able to show the total load (gf / cm2) carried by the test specimen. A compression plate 310 is circular with an area of 2.00 cm2, a thickness of 0.40 cm. A drive mechanism 360 is capable of imparting to the compression plate 310 a controlled, uniform and fixed compression / recovery rate (cm / sec). (3) Procedure The inner cylinder 270 is inserted into the outer cylinder 230. An aliquot of 2.8 g of an absorbent material is added to the inner cylinder 270 and dispersed uniformly over the 400 mesh stainless steel screen of the bottom 400 via moderate agitation and / or plugging of the assembled cylinders. The cylinders assembled with the absorbent material are transferred to the flat bottom tray 240 of TEFLON, and the cover plate 220 of the internal cylinder is placed on the internal cylinder 270. To the tray 240 of flat bottom, of TEFLON, it is apply 56 milliliters of Jayco synthetic urine. The Jayco synthetic urine from the flat bottom tray of TEFLON 240 passes through the stainless steel sieve 250. All the applied urine is absorbed by the absorbent material 260 for 5 minutes. Then, the weight of stainless steel 210 is placed on the cover plate 220 of the inner cylinder. After an additional 25 minutes, the weight of stainless steel 210 and cover plate 220 of the inner cylinder are removed. Consequently, the predetermined layer 260 of the swollen absorbent material for the measurement of the DVG has been prepared. The inner cylinder 270 with the gel layer of absorbent material 260 is immediately transferred to the Compression Tester for the RC Test. The inner cylinder 270 with the gel layer of absorbent material 260 is immediately placed over the group of 5 specimen 320 of the Handy type compression tester as shown in Figure 7. The compression plate 310 is placed on the gel layer. of absorbent material 330 but without compressing the specimen (load of 0 gf / cm2 at a compression depth of 0 cm). The compression depth is selected on the scale from 0 to 1.00 cm, the compression / recovery speed is selected at 0.01 cm / sec, and the load sensitivity is selected at 10 gf. Start the test by pressing the tester's start switch. The drive 360 drives the compression plate 310 so that compresses a layer of absorbent material gel 330 at a speed of 0.01 cm / sec, until the compression depth alight 1.00 cm, and then the compression plate 310 returns at the same speed as that of compression, to the position original. The load (gf / cm2) and the depth (cm) are recorded using an XY-Recorder. Compression recovery (RC) is expressed as the percentage of recovery work (gfcm / cm2) to the compression work (gfcm / cm2). As shown in Figure 8, the recovery work corresponds to the area (Sr) that is enclosed by the recovery curve, line AB and horizontal axis. The compression work corresponds to the area that is enclosed by the compression curve, the line AB and the horizontal axis, and is equal to the total area of Sc + Sr, where Sc corresponds to the area that is enclosed by the compression curve, and the recovery curve. Therefore, the CR can be calculated from the following equation: RC% = Sr / (Sc + Sr) x 100. The average of the three determinations must be reported. 5. Volume of Gel The gel volume of a hydrogel-forming absorbent polymer is defined as its swelling-free absorbent capacity when swollen in an excess of synthetic urine Jayco. It provides the measurement of the maximum absorbent capacity of the polymer under conditions of use, where pressures on the polymer are relatively low. For most hydrogel-forming absorbent polymers, the gel volume is determined by the method described in the US Pat. re-dispatch of E.U.A. 32,649 (Brandt et al.) Reissued on April 19, 1988 (incorporated herein by reference) but using the Jayco synthetic urine described above. All chemical products are reactive grade. The pH of synthetic urine is in the range of 6.0 to 6.4. The volume of gel is calculated on a dry weight basis. The dry weight used in the calculation of the gel volume is determined by drying the absorbent hydrogel-forming polymer at 105 ° C in a furnace for 3 hours. 6. Removable Component The percentage of the extractable polymer, in hydrogel-forming polymers based on carboxylic acid, is determined by the method of Determination of Removable Polymer Content - Hydrogel Forming Polymers based on Carboxylic Acid, described in the reissuance patent of E.U.A. 32,649 (Brandt et al.) Reissued on April 19, 1988 (incorporated herein by reference), but using 0.9% saline, filtering the supernatant through a 0.7 micron GF / F microfiber filter from Whatman (v. .gr., Catalog # 1825-125 or equivalent), and calculating the extractable polymer on a dry weight basis. It is also observed that in the redirection patent of E.U.A. 32,649, which must refer to the base volume and Vb must refer to the volume of acid G. Examples of Absorbent Materials EXAMPLE OF PRECURSOR PARTICLE An aqueous monomer solution consisting of 4,000 g of partially neutralized acrylic acid having a 75 molar portion thereof neutralized with caustic soda, 3.7 g of N, N'-methylene-bis-acrylamide, and 6,000 g of water was prepared. The aqueous monomer solution was fed to the reaction vessel, which was subsequently purged with nitrogen gas to remove trapped air remaining from the reaction system. Then, the mixture was stirred and heated to about 45 ° C, and a solution of 20 g of 2,2'-azo-bis- (2-amidinopropane) dihydrochloride in 100 g of water was added thereto, as a polymerization initiator. The polymerization started approximately 15 minutes after the addition of the polymerization initiator. With the progress of the polymerization, the aqueous monomer solution gave rise to a gel containing soft water. The internal temperature of the reaction system was maintained at 80-90 ° C for hours to complete the polymerization. An absorbent gelling polymer was formed, swollen. The resulting swollen absorbent gelling polymer thus obtained was spread on a metal gauge of normal size # 50 and dried with hot air at 150 ° C. The dry particles were pulverized with a hammer-type grinder and were sieved with a normal # 20 sieve (850 microns) to obtain particles that pass through the normal # 20 sieve. As a result, dry, white precursor absorbent gelling particles are obtained.

EXAMPLE 1 A solution consisting of 250 g of a solution of polyallylamine at a concentration of 10% by weight (PAA-C, supplied by Nitto Boseki Co. Ltd., Tokyo), 1600 g of ethanol was prepared. The solution was applied to 2,500 g of the precursor particles according to the Precursor Particle Example in a 20 liter evaporation flask. The precursor particles have a particle size, so that they pass through a normal # 20 sieve (850 microns) and are retained on a normal # 100 sieve (150 micras). The mixture was thoroughly mixed with a spatula until all the precursor particles were wetted with the previous solution. The solvent included in the resulting mixture was evaporated with a rotary evaporator (EYELA type N-ll, available from TOKYO RIKAKIKAI CO., LTD, Tokyo) at 60 ° C. The resulting product was dried under vacuum at 100 ° C for 3 hours. The dry absorbent material was pulverized with a hammer-type crusher and flowed with a normal # 20 sieve (850 microns) to obtain particles passing through the normal # 20 sieve. As a result, dry white particles are obtained from the resulting absorbent material (EJ # 1). In comparison of the properties of the precursor particles and the absorbent material (EJ # 1), the gel volume, the RRB value and the CR value of the precursor particles are 40.0 g / g, 17 gf, and 9% , respectively, while the gel volume, the RRB value and the RC value of the absorbent material (EJ. # 1) are 39.2 g / g, 160 gf, and 62%, respectively.

EXAMPLE 2 The absorbent gelling particles obtained from commercial sources were used in this example. They were placed in a rotary evaporation flask of 20 I *, liters, 2,500 grams of Aqualic CA L761f (lot # 4N22-029) supplied from Nippon Shokubai Co. Ltd., Osaka, Japan. L761f is an absorbent gelling particle intertwined on the surface. A solution consisting of 250 g of a polyallylamine solution with a concentration of 10% by weight (PAA-C, supplied by Nitto Boseki Co. Ltd., Tokyo), 1,600 g of ethanol, was applied to the flask. The mixture was thoroughly mixed with a spatula until all the precursor particles were wetted with the previous solution. The solvent included in the resulting mixture was evaporated with a rotary evaporator (EYELA type N-ll, available from TOKYO RIKAKIKAI CO., LTD, Tokyo) at 60 ° C. The resulting product was dried under vacuum at 100 ° C for 3 hours. The dry absorbent material was pulverized with a hammer-type crusher and harvested with a normal # 20 sieve (850 microns) to obtain particles that pass through the normal # 20 sieve. As a result, dry white particles are obtained from the resulting absorbent material (Example # 2). The RC curve for the absorbent material (EJ # 2) is shown in Figure 9. In contrast, the RC curve for L761f is shown in Figure 10. A comparison chart, to show the properties of these materials, is summary in Table 1, below: TABLE 1 Sample Volume DVG CFS RRB RC Component of Gel (g / cm3) (10-7cm3 (gf) (%) Removable (g / g) sec / g) (%) L761f 37.5 1.09 4 17 7 12.3 Ex. # 2 36.2 0.75 29.8 138 51 8.9 EXAMPLE 3 In this example, absorbent gelling particles obtained from commercial sources were used. Aqualic CA L761f (lot # 4E28-012) supplied from Nippon Shokubai Co. Ltd, Osaka, Japan, was placed in a Kitchen-type mixer. A solution consisting of 10 g of a solution of polyallylamine at a concentration of 10% by weight (PAA-C, supplied from Nitto Boseki Co., Ltd. Osaka) and 20 g of ethanol was prepared. After a portion of the solution was sprayed onto the absorbent gelling particles with a sprinkler (type: 24-182-04, available from Iuchi Seieido Co. Ltd. Osaka), the mixer was operated for a period of about 4 minutes. . Repeat the spraying / mixing procedures until all the solution is sprayed on the absorbent gelling particles. The resulting mixture was dried with a vacuum oven at about 100 ° C for about 3 hours. The dried particles were sprayed with a hammer-type crusher and sieved with a normal # 20 sieve (850 microns) to obtain particles that pass through the normal # 20 sieve. As a result, dried white particles were obtained from the resulting absorbent material. The properties of the resulting absorbent material (EJ. # 3) are shown in Table 2.

TABLE 2 Sample Volume DVG CFS RRB RC Component of Gel (g / cm3) (10-7cm3 (gf) (%) Removable (g / g) sec / g) (%) L761f 36.4 1.07 9 21 8 11.1 Ex. # 3 35.0 0.78 45 124 55 9.0

Claims (8)

NOVELTY OF THE INVENTION CLAIMS

1. - An absorbent member comprising at least one region, which comprises an absorbent material, said absorbent material comprising a mixture of (1) a plurality of absorbent gelling particles comprising a water-insoluble, water-swellable polymer, and (2) an absorbent property modification polymer, preferably a cationic polymer, reactive with at least one component included in the urine, characterized in that when said absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material under a predetermined load, said layer of swollen absorbent material has a value of Gel Volume Density (DVG) below 0.95 g / cm3 in the DVG test.

2. - An absorbent member comprising at least one region, which comprises an absorbent material, said absorbent material comprising a mixture of (1) a plurality of absorbent gelling particles comprising a water insoluble polymer, swellable with water , and (2) a polymer of modification of absorbent property, reactive with at least one component included in the urine, characterized in that when said absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material, said layer of Inflated absorbent material has a Saline Flow Conductivity (CFS) value of at least 20 x 10 -7 cm3 sec / g in the CFD test.

3. - An absorbent member comprising at least one region, which comprises an absorbent material, said absorbent material comprising a mixture of (1) a plurality of absorbent gelling particles comprising a water insoluble polymer, swellable with water , and (2) a polymer of modification of absorbent property, reactive with at least one component included in the urine, characterized in that when said absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material, said layer of Inflated absorbent material has a Ball Resistance Resistance (RRB) value of at least 30 gf in the RRB test.

4. - An absorbent member comprising at least one region, which comprises an absorbent material, said absorbent material comprising a mixture of (1) a plurality of absorbent gelling particles comprising a water-insoluble, water-swellable polymer , and (2) a polymer of modification of absorbent property, reactive with at least one component included in the urine, characterized in that when said absorbent material swells by absorbing urine and is formed to a predetermined layer of the swollen absorbent material, said layer of Inflated absorbent material has a Compression Recovery (RC) value of at least 15% in the RC test.

5. The absorbent member according to any of claims 1 to 4, characterized in that said absorbent material is in a concentration of 60 to 100% by weight in said at least one region.

6. - The absorbent member according to any of claims 1 to 5, characterized in that said component included in the urine is an anion having at least 2 numbers of ionic charge, and said cationic polymer is reactive with said anion in the urine, said anion being preferably a phosphate ion, a sulfate ion, or a carbonate ion, and said cationic polymer is reactive with said phosphate ion, sulfate ion, or carbonate ion in the urine.

7. The absorbent member according to any of claims 6, characterized in that said cationic polymer is a polyamine or poly-imine material, said polyamine is preferably selected from the group consisting of: (a) polymers having amine groups primary; (b) polymers having secondary amine groups; (c) polymers having tertiary amine groups; and (d) mixtures thereof.

8. - An absorbent article comprising: (a) a liquid-permeable topsheet; (b) a back sheet impervious to liquid; and (c) an absorbent core positioned between said top sheet and said back sheet, characterized in that said absorbent core comprises at least one absorbent member of any of claims 1 to 7.