MXPA04002443A - Composites comprising superabsorbent materials having a bimodal particle size distribution and methods of making the same. - Google Patents

Abstract

The present invention is directed to an absorbent composite containing superabsorbent material. The superabsorbent material is in the form of superabsorbent particles having a bimodal particle size distribution. Use of superabsorbent material having a bimodal particle size distribution in the absorbent structure results in enhanced fluid distribution and fluid intake of the absorbent composite. The absorbent composite of the present invention is useful in disposable personal care products.

Description

wo 03/030955 A2 1 ?? 1? If! Illl! II Hlfll llillf! Lf I?! II! HUI fllfl IIIII HUIllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllllll Declarations under Rule 4.17: - as to the appl icant 's entitlement to claim the priority ofthe - as to applicant 's eniitlemení to apply for and be granted earlier application (Rule 4.17 (iii)) for al! designations a patent (Rule 4.17 (H)) for the following designations AE, AG, AL, AM, AT, AU, Al, BA, BB, BG, BR, BY, BZ, CA, Published: CH, CN, CO, CR, CU, CZ, DE, DK, DM, DZ, EC, EE, ES, - wilhout international search report and to be republished Fl, GB, GD, GE, GH, GM, HR, HU, ID, 1L, IN , Y, JP, KE, upon receipt of that report KG, KP, KR, KZ, LC, LK, LR, LS, LT, LU, LV. MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, OM, PH, PL, PT, RO, RU, SD, SE, SG, SI, SK, SL, TJ, TM, TN, TR, TT, TZ, UA, UG, For two-leUer codes and oiher abbreviations, refer to the "Guid-UZ, VN, YU, ZA, ZM, ZW. AR1PO patent (GH, GM, KE, LS, ance Notes on Codes and Abbreviations "appearing at the beginning - MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW), Eurasian patent no of each regular issue of the PCT Gazette. (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), European patent (AT, BE, CH, CY, DE, DK, ES, Fl, FR, GB, GR, IE, IT, LU , MC, NL, PT, SE, TR), OAP1 patent (BE BJ, CF, CG, CI, CM, GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG) 1 COMPOUNDS THAT COMPRISE SUPERABSORBENT MATERIALS THAT THEY HAVE A DISTRIBUTION OF BIMODAL PARTICLE SIZE AND THE METHODS TO MAKE THEMSELVES Field of the invention The present invention relates to the compounds containing superabsorbent materials and more particularly to the compounds containing superabsorbent materials having a bimodal particle size distribution and exhibiting improved fluid admission and distribution properties.

BACKGROUND OF THE INVENTION The use of water-swollen absorbent materials, generally insoluble in water, commonly known as superabsorbents, are known in disposable absorbent personal care products. Such absorbent materials are generally used in absorbent products such as diapers, training pants, adult incontinence products, and women's care products in order to increase the absorbent capacity of such products, while that reduce their total volume. Absorbent materials are generally present as a composite of the superabsorbent particles (SAP) mixed in a fibrous binder, such as an agglomerate of wood pulp fluff. A wood pulp fluff binder generally has an absorbent capacity of about 6 grams of liquid per gram of fluff. The superabsorbent materials (SAM) generally have an absorbent capacity of at least about 10 grams of liquid per gram of superabsorbent material, desirably less than about 20 grams of liquid per gram of superabsorbent material, and often up to about 40 grams. of liquid per gram of superabsorbent material. Clearly, the incorporation of such absorbent materials in personal care products can reduce the total volume, while increasing the absorbent capacity of such products.

The distribution of capillary driven fluid within the absorbent material is typically hampered due to the presence of the superabsorbent. The fluid distribution can be improved by optimizing various functional and physical superabsorbent attributes; however, such modifications have traditionally reduced the admission performance of pressurized fluid (forced flow) of the absorbent core.

Different sizes of superabsorbent particles have been used to improve different performance attributes of the compound, such as the admission of the compound and the distribution. The larger particles have been used to create large voids when swollen to improve the rate of fluid intake; however, these particles negatively affect the distribution of fluid. The smaller particles have been used to create small voids when swelling to improve capillary action and fluid distribution rate. However, no proposal has been able to improve one of the admission or distribution properties without negatively affecting the other property.

What is needed in the art is a composite material comprising superabsorbent material, wherein the composite material has improved admission, as well as, improved distribution.

Synthesis of the invention The present invention is directed to an absorbent composite that includes a superabsorbent material (SAM), wherein the superabsorbent material (SAM) contains superabsorbent particles having a bimodal particle size distribution. The bimodal particle size distribution includes large particles having an average particle size of mass from about 850 to about 1800 microns, and small particles having an average particle size of mass from about 50 to about 200. microns. The bimodal particle size 4 distribution of the superabsorbent particles in the absorbent structure of the present invention allows the distribution of improved capillary driven fluid, as well as the admission of improved fluid from the absorbent core.

More particularly, the absorbent composition of the present invention contains superabsorbent particles having an average total particle size of about 60 to about 1750 microns. The ratio of the mass of the large particles to the small particles is from about 90:10 to about 50:50, and the absorbent compound can comprise from about 20% to about 100% by weight of superabsorbent material.

The present invention is also directed to an absorbent composite which includes a superabsorbent material having a bimodal particular size distribution, wherein the compound has a third liquid discharge admission time of less than about 100 seconds.

The present invention is further related to an absorbent composite containing superabsorbent material which is uniformly distributed within the compound. The compound has a third discharge time of liquid discharge of less than about 100 seconds, and a third intermittent vertical runoff time of less than about 600 seconds. 5 The absorbent compound is particularly useful in disposable personal care products such as diapers, training shorts, women's pads, panty liners, incontinence products, as well as health products. personnel such as bandages for those followed, and supply systems.

Brief description of the figures Figure 1 is a graph illustrating the ratio of the fraction of the mass against the particle size for the superabsorbent materials used in the present invention.

Figure 2 is a perspective view of a liquid addition device.

Detailed description of the invention In the levels of superabsorbent materials currently used in the absorbent core of the diapers (around 40%), the volume occupied by the superabsorbent material (SAM) while swelling becomes significantly higher than that occupied by the fibrous material. Although fibers continue to play an important role in the movement of capillary-driven fluid in the subsequent 6 fluid discharges, adjusting the packing fraction of the swollen superabsorbent particles to maximize capillary impulse can lead to significantly improved fluid runoff. As used herein, the term "packaging fraction" refers to the ratio of solid volume to total volume of the compound.

The present invention fulfills the need described above by providing an absorbent composite having improved fluid intake and improved absorbent core and improved capillary fluid distribution. The uniform distribution of the superabsorbent material within the absorbent compound is preferred. In an embodiment of the present invention, the improved properties of the absorbent composites of the present invention result from the use of a superabsorbent material having a bimodal distribution of sizes of the superabsorbent particle within the absorbent core.

The following terms are used to describe the absorbent compounds of the present invention. A general definition of each term is given below.

As used herein, the term "bimodal" refers to a superabsorbent material having two precise peaks in the fraction of the mass against the particle size curve for the superabsorbent material. A graph 7 contains the fraction of the mass against the particle size curves for various superabsorbent materials is illustrated in Figure 1.

As used herein, the term "superabsorbent material" refers to an inorganic or organic material insoluble in water, which swells in water capable, under the most favorable conditions, of absorbing more than 15 times its weight in an aqueous solution containing 0.9% by weight of sodium chloride.

As used herein, the term "uniform distribution" with respect to the superabsorbent material means that the absorbent compound has an equal amount of superabsorbent material located in all three dimensions of the compound.

Desirably, the absorbent composites of the present invention comprise superabsorbent material in combination with a fibrous binder containing one or more types of fibrous materials. A description of the components of the absorbent compound is given below.

Superabsorbent materials Suitable materials for use as a superabsorbent material of the present invention may include materials such as agar, pectin, guar gum, and the like; as well as synthetic materials, such as synthetic hydrogel polymers. Such hydrogel polymers include, but are not limited to, the alkali metal salts of polyacrylic acids, the polyacrylamides, the polyvinyl alcohol, the maleic anhydride copolymers of ethylene, the polyvinyl ethers, the hydroxypropyl cellulose, the polyvinyl morpholinone; and copolymers and copolymers of vinyl sulphonic acid, polyacrylates, polyacrylamides, polyvinyl pyridine, and the like. Other suitable polymers include the hydrolyzed acrylonitrile grafted starch, the acrylic acid grafted starch, and the isobutylene maleic anhydride copolymers and mixtures thereof. The hydrogel polymers are desirably lightly crosslinked to render the material substantially insoluble to water. The crosslinking may, for example, be by irradiation or by hydrogen bonding, van der Waals, ionic, covalent. The superabsorbent materials may be in any form suitable for use in absorbent composites including the particles, flakes, spheres, and the like.

Although a wide variety of superabsorbent materials are known, the present invention relates, in one aspect, to the proper selection of superabsorbent materials to enable the formation of improved absorbent compounds and disposable absorbent garments. The present invention is directed to a method for achieving optimum performance in an absorbent composite due to the discovery that superabsorbent materials having a particular bimodal particle size distribution provide unexpected improvements in the combined properties of the capillary-driven fluid distribution and the admission performance. More specifically, the absorbent compounds of the present invention desirably contain superabsorbent material having a bimodal particle size distribution, wherein the superabsorbent material comprises large particles having an average mass particle size of from about 850 to about 1800. microns and small particles that have a mass average particle size of from about 50 to about 200 microns. Preferably, the superabsorbent material contains large particles having a mass average particle size of about 1000 to about 1600 microns and small particles having a mass average particle size of about 65 to about 150 microns.

Another desirable feature of the present invention is the difference between the average particle size of mass of the large particles and the average particle size of mass of the small particles within the absorbent compounds of the present invention. Desirably, the ratio of the size of the average particle mass of the large particles to the size of the average mass particle of the small particles is about 4: 1 to about 36: 1. More desirably the ratio of the average particle size mass of the large particles to the average mass size of the small particles is about 6: 1 to about 25: 1.

In one embodiment of the present invention, the absorbent composition contains superabsorbent material having a bimodal particle size distribution, wherein the superabsorbent material includes large particles having a mass average particle size of less than about 1200 microns, and small particles that have a mean particle size of mass of less than about 150 microns, where the difference (di / s) between the size of the average particle mass of the large particles and the size of the average particle of mass of the small particles is larger than about 500 microns. In a further embodiment, the absorbent composite contains superabsorbent material having a bimodal particle size distribution, wherein the superabsorbent material includes large particles having an average mass particle size of less than about 1100 microns, and small particles having a mass average particle size of less than about 100 microns, wherein the difference (di / s) between the average particle size 11 of the mass of the large particles and the average particle size of the mass of the particles small is larger than about 900 microns.

While not bound by any particular theory, it is believed that the compounds of the present invention exhibit improved fluid distribution for the following reasons. In compounds having high levels of superabsorbent material (eg, greater than 30% by weight), the volume occupied by the superabsorbent material, while swelling, becomes significantly larger than that occupied by the fibers. If there is a lot of empty space between the particles and the fibers (vacuum space), the capillarity of the composite system becomes too low to effectively drain fluid to higher areas in the composite. However, if the packaging of the swollen superabsorbent particles can be adjusted to minimize the amount of vacuum space between the swollen superabsorbent particles, the capillary impulse within the system can be maintained resulting in improved fluid runoff. Surprisingly, it has been found that the compounds of the present invention can exhibit improved fluid runoff also exhibit improved fluid admission.

Therefore, it is preferred that the superabsorbent material be uniformly distributed within the absorbent composite. However, the superabsorbent material 12 may be distributed through the entire absorbent composite or may be distributed within a small, localized area of the absorbent composite.

Relationships have been identified between the amount of vacuum space in multi-component systems and the proportion of the largest and smallest particles in the system. From these relationships, the maximum packing of particles in a two-component system can be determined. See C.C. Furnis, Chemical and Industrial Engineering, vol. 23, No. 9, 1052 to 1058 (1931). The equation that is used is: F = f + (1 - F?) < Pi = [(1- v · Pi] ÷ [(1 - vi) · Pi + vi * (1 - v2 > · P2] where vi and v2 are the vacuum space in a system of particles 1 (for example, large particles) and particles 2 (for example, small particles), respectively; and Pi and P2 are the true specific gravity of particles 1 (e.g., large particles) and particles 2 (e.g., small particles), respectively. The value of < Pi represents the degree to which the first component, the large particles, is saturated by the second component, the small particles. The weight of the large particles for denser packing may be <Pi and the 13th weight of the smaller particles for denser packaging may be (1-ci).

Each of these quantities divided by F can then give the proportion, by weight, of each component for more dense packing. The ratio of the optimum large particle to the small particle can be calculated based on the maximum packing of the particles at full saturation, since, at this level of saturation, packing within the structure may be primarily determined by the superabsorbent material in instead of the fibers.

Given the calculation described above, it has been determined that the absorbent compounds of the present invention desirably contain superabsorbent material, wherein the mass ratio of the "large" particles (e.g., the sample of particles having an average particle size of larger mass) to the "small" particles (eg, the particle sample having the smallest mass mean particle size) is around 90:10 up to about 50:50. More desirably, the absorbent composites of the present invention contain superabsorbent material, wherein the ratio of the mass of the "large" particles to the "small" particles is from about 90:10 to about 80:20. Even more desirably, the absorbent composites of the present invention contain superabsorbent material, wherein the ratio of the mass of the "large" particles to the "small" particles is about 85:15.

In addition, the absorbent compounds of the present invention desirably contain the above described bimodal particle size distribution and a total mass average particle size of about 10 to about 1750 microns. More desirably, the absorbent compounds of the present invention desirably contain the above-described bimodal particle size distribution and a total mass average particle size of from about 800 to about 1200 microns. Even more desirably, the absorbent compounds of the present invention desirably contain the above described bimodal particle size distribution and a total mass average particle size of from about 900 to about 1100 microns.

In one embodiment of the present invention, the superabsorbent material comprises a sodium salt and a crosslinked polyacrylic acid. Suitable superabsorbent materials are included, but are not limited to Dow AFA-177-140 and Drytech 2035 both available from Dow Chemical Company, Midland, MI, Favor SXM-880 available from Stockhausen, Inc. of Greensboro, NC, Sanwet IM-632 available from Tomen America of New York, NY, and the Hysorb P-7050 15 available from BASF Corporation, Portsmouth, VA.

Fibrous Materials Desirably, the absorbent composites of the present invention contain the above-described superabsorbent materials in combination with a fibrous binder containing one or more types of fibrous materials. The fibrous material forming the absorbent composites of the present invention can be selected from a variety of materials including natural fibers, synthetic fibers, and combinations thereof. An appropriate number of fiber types is described in U.S. Patent No. 5,601,542 assigned to Kimberly-Clark Worldwide, Inc., the entirety of which is incorporated herein by reference.

The selection of fibers depends on, for example, the final use in intention of the finished absorbent composite. For example, suitable fibrous materials may include, but are not limited to natural fibers such as non-woody fibers, which include cotton fibers and cotton, abaca, hemp, sabai grass, flax, cotton, and cotton fibers. esparto grass, straw, hemp jute, fibers, benzene gut, pineapple leaf fibers; woody fibers such as those obtained from coniferous and deciduous trees, which include softwood fibers, such as softwood kraft fibers from the south and north; hardwood fibers, such as eucalyptus, maple, birch, aspen, and the like. The wood fibers can be prepared in low yield or high yield forms and can be pulped by any known method, and include kraft, sulfite, earthwood, thermomechanical pulp (TMP), quimotermomechanical pulp ( CTMP) and the bleached quimotermomecánica pulp (BCTMP). Recycled fibers are also included within the scope of the present invention. Any known bleaching and pulping methods can be used.

Similarly, regenerated cellulosic fibers such as viscose rayon and cupramonium rayon, modified cellulose fibers, such as cellulose acetate, or synthetic fibers such as those derived from polyesters, polyamides, polyacrylates, etc., alone or in combination with each other, they can be used in the same way. The chemically treated natural cellulosic fibers can be used such as mercerized pulps, crosslinked or chemically reinforced fibers, sulfonated fibers, and the like. Suitable papermaking fibers can also include recycled fibers, virgin fibers, or mixtures thereof. Mixtures of one or more of the aforementioned fibers can also be used if desired. 17 Absorbing Compounds As previously described, the absorbent structures according to the present invention desirably include a superabsorbent material and a fibrous binder to contain the superabsorbent material. However, it should be noted that any device capable of containing the above-described superabsorbent material, and in some cases, is capable of being located in a disposable absorbent garment, is suitable for use in the present invention.

Many such containment devices are known to those with skill in the art. For example, the containment device may comprise a fibrous binder such as a wet or air-laid tissue of cellulosic fibers, a blown fabric with synthetic polymer fiber fusion, a spin-linked fabric of synthetic polymer fibers, a coformmed binder that comprises cellulosic fibers and fibers formed from heat-melted fabrics, laid with air, synthetic polymer material of synthetic polymeric materials, open cell foams, and the like.

The containment device is desirably a fibrous binder having a shape such as a fibrous web, which is generally a random plurality of fibers that can optionally be joined together by a binder. The fibrous material may alternatively be in the form of a block of fibrous material of shredded pulp of ground wood, a layer of tissue, a sheet of hydroentangled pulp, a woven sheet, a non-woven sheet, a tow, a sheet of pulp mechanically smoothed Any papermaking fibers, as previously defined, or mixtures thereof can be used to form the fibrous binder.

The absorbent composites of the present invention can be formed from a single layer of absorbent material or multiple layers of absorbent material. In the case of multiple layers, the layers may be placed in a surface-to-surface or side-to-side relationship and all or a portion of the layers may be attached to adjacent layers. In those instances where the absorbent composite includes multiple layers, the entire thickness of the absorbent composite may contain one or more superabsorbent materials or each individual case may separately contain some or no absorbent materials.

In one embodiment of the present invention, the absorbent composite contains superabsorbent material and fibrous material wherein the relative amount of superabsorbent material and fibrous material used to produce the absorbent compound can vary depending on the desired properties of the resulting product, and the application of the resulting product. Desirably, the amount of superabsorbent material in the absorbent composite is from about 20% by weight to about 100% by weight and the amount of fibrous material is from about 80% by weight to about 0% by weight, based on the total weight of the absorbent compound. More desirably with more the amount of superabsorbent material in the absorbent composite is from about 30% by weight to about 90% by weight and the amount of fibrous material is from about 70% by weight to about 10% by weight based in the total weight of the absorbent compound. Even more desirably, the amount of superabsorbent material in the absorbent compound is from about 40% by weight to about 80% by weight and the amount of fibrous material is from about 60% by weight to about 20% by weight, based on the total weight of the absorbent compound.

In another embodiment, the basis weight of the superabsorbent material used to produce the absorbent composites of the present invention may vary depending on the desired properties, such as the thickness of the compound and the total basis weight, on the resulting product, and the application of the resulting product. For example, absorbent compounds for use in infant diapers may have a lower thickness and basis weight compared to an absorbent composite for an incontinence device.

Desirably, the basis weight of the superabsorbent material in the absorbent composite is greater than about 80 grams per square meter (gsm). More desirably, the basis weight of the superabsorbent material in the absorbent composite is from about 80 grams per square meter to about 800 grams per square meter. Even more desirably, the basis weight of the superabsorbent material in the absorbent composite is from about 120 grams per square meter to about 700 grams per square meter. Even more desirably, the basis weight of the superabsorbent material in the absorbent composite is from about 150 grams per square meter to about 600 grams per square meter.

Method for Making Absorbent Compound The absorbent compounds of the present invention can be made by any process known to those of ordinary skill in the art. In an embodiment of the present invention, the method for forming the absorbent compound can include combining superabsorbent material containing superabsorbent particles with a substrate. The superabsorbent particles have a bimodal particle size distribution with large particles having an average mass particle size of from about 850 to about 1800 microns and small particles having a mass-average size of about 50 up to around 200 microns.

Preferably, the large particles have an average mass size of from about 1000 to about 1600 microns, and the small particles have an average mass size of from about 65 to about 150 microns.

Alternatively, the method may include combining superabsorbent material with a substrate wherein the compound has a third liquid discharge admission time of less than about 100 seconds and a third intermittent vertical drip travel time of less than about 600 seconds. . The superabsorbent material is uniformly distributed within the compound.

In a further embodiment of the present invention, the superabsorbent material containing superabsorbent particles is incorporated into an existing substrate. Preferably, the substrate contains fibrous material. Suitable fibrous substrates include, but are not limited to, woven and non-woven fabrics. In many embodiments, particularly personal care products, the preferred substrates are non-woven fabrics. As used herein, the term "non-woven fabric" refers to a fabric having a filament structure of individual fibers arranged randomly in a mat-like manner. Non-woven fabrics can be made from a variety of processes including, but not limited to, air-laid processes, wet-laid processes, 22 hydroentanglement processes, bonding and carding of basic fibers and spinning solution . The superabsorbent material can be incorporated into the fibrous substrate as a solid particle material. The superabsorbent materials may be in any form suitable for use in the absorbent composites which include the particles, flakes, spheres, and the like.

In an alternate embodiment of the present invention, the fibrous material and superabsorbent material containing superabsorbent particles are simultaneously mixed to form an absorbent composite. Desirably, the composite materials are mixed by an air forming process known to those of ordinary skill in the art. The air formation of the fiber mixture and the superabsorbent material are intended to encompass both the situation where the previously formed fibers are placed by air with the superabsorbent material, as well as, the situation in which the superabsorbent material is mixed with the fibers while the fibers are being formed, such as through a meltblowing process.For example, the following description is intended to be illustrative of an air forming process used to form the compounds of the present invention, and is not intended to be limiting. Various components of the process can be used to make the absorbent compounds 23 of the present invention. These first include a method for fibrillating pulp sheets in fibrillated fluff. These fibers of fibrillated fluff are transported with air in a formation chamber. Then, a method for adding absorbent articles is used to measure and transport superabsorbent particles in the formation chamber. More than one superabsorbent feeder has been found to be useful in controlling the individual amounts of superabsorbent particles of different types to the formation chamber. The forming chamber causes the fibrillated fluff fibers and the superabsorbent particles to become mixed together. A moving shaping screen is located at the bottom of the training chamber. This screen is permeable to air and is typically connected to a vacuum source. This vacuum removes air from the forming chamber and causes the fibrillated fluff fibers and superabsorbent particles to be deposited on the forming screen to form a composite fabric. The tissue can be disentangled in the forming wire such that fibers and particles are placed in the tissue to aid in transportation. The speed of the pulp sheets, the superabsorbent feeders, and the formation screen can all be independently adjusted to control the composition and the basis weight of the resulting compound. The next formation of the composite fabric in the forming wire, a roll can be used to compress the composite to a desired level. At the end of the forming screen the composite fabric is entangled in a continuous roll. 24 Properties of Absorbent Compounds The absorbent composites of the present invention possess improved capillary driven fluid distribution, as well as, improved fluid admission over the life of the station, when compared to known absorbent compounds. A method to measure the distribution of capillary-driven fluid of an absorbent compound is with the Intermittent Vertical Runoff (IV) test. This test measures the rate of runoff of a material or compound during a series of liquid contacts.

The Flashing Vertical Run test consists of contacting a lower edge of a vertically suspended absorbent compound with a solution, and is described in detail below. The fluid distribution profile obtained by the Intermittent Vertical Runoff test can be analyzed in terms of the liquid saturation of the compound at distances that vary from the lower edge of the compound. Preferably, the absorbent compounds of the present invention exhibit a saturation of the liquid at 3 to 3.5 inches from the lower edge of the composite equal to at least 65% of the liquid saturation at 0 to 0.5 inches from the lower edge of the composite. More preferably with more liquid saturation of 4 to 4.5 inches from the lower edge of the absorbent compound which is equal to at least 25% of the liquid saturation of 0 to 0.5 inches from the lower edge of the composite, and still more preferably the liquid saturation of 4.5 to 5.0 inches from the lower edge of the composite is equal to at least 35% of the liquid saturation of 0 to 0.5 inches from the lower edge of the absorbent composite.

Additionally, it is desired that the absorbent composites of the present invention demonstrate a third intermittent vertical runoff collection time of less than about 600 seconds. More desirably, the absorbent composites demonstrate a third intermittent vertical picking time of less than about 300 seconds.

A method to measure the admission of fluid of an absorbent compound is with the Fluid Admission Evaluation Test (FIE), which is described in detail below. This test measures the admission capacity of a material or compound when it is subjected to multiple liquid discharges.

Desirably, an absorbent composition of the present invention has a third liquid discharge admission time of less than about 100 seconds, more desirably less than about 85 seconds, and even more desirably less than about 60 seconds.

Another unique feature of the absorbent composites of the present invention is that the superabsorbent particles contained in the composite have different swelling times due to precise sizes of the particles. The inflation time is defined while the amount of time it takes for the superabsorbent particles to reach 60% liquid capacity, and can be determined using the FAUZ1 staining test which is explained in detail below. Preferably, the inflation time of the small particles used in the absorbent composition of the present invention is from about 15 seconds to about 35 seconds, and the time of swelling of the large particles is from about 300 seconds to about 700. seconds. More preferably, the swelling time of the small particles is from about 20 seconds to about 30 seconds, and the time spent for the large particles is around 400 seconds to about 600 seconds. Additionally, it is desired that the inflation time of the small particles be approximately 20 times shorter than the time of swelling of the large particles.

Methods for using Absorbing Structures In one embodiment of the present invention, a disposable absorbent product is provided, which includes a liquid pervious top sheet, a bottom sheet coupled to the top sheet, and an absorbent composite of the present invention positioned between the top sheet and the sheet. lower. Those with a skill in the art will be able to recognize the appropriate materials for use as a top sheet and a bottom sheet. Exemplary materials suitable for use with a topsheet are liquid-permeable materials, such as polyethylene or spin-linked polypropylene having a basis weight of from about 15 to about 25 grams per square meter. Exemplary materials suitable for use as a bottom sheet are liquid impervious materials, such as polyolefin films, as well as vapor permeable materials, such as microporous polyolefin films.

Disposable absorbent products, according to all aspects of the present invention, are generally subjected during use to multiple discharges of a body fluid. Therefore, the disposable absorbent products are desirably capable of absorbing multiple discharges of body fluids in amounts to which absorbent products and structures may be exposed during use. The discharges are generally separated from one another for a period of time. The absorbent products of the present invention should be present in an effective amount to form a superabsorbent composition 28 effective to resuscitate upon absorption of a desired amount of liquid.

Absorbent compounds according to the present invention are suitable for absorbing many fluids including body fluids such as urine, menstruation, and blood, and are particularly suitable for use in disposable absorbent products such as personal care products. disposable materials that include, but are not limited to, absorbent garments such as diapers, incontinence products, bed pads, and the like; catamenial devices such as sanitary napkins, linings for panties, tampons, and the like; personal health products such as bandages for wounds, and delivery systems; as well as cleaning cloths, bibs, food packaging and the like. Therefore, in another aspect, the present invention relates to a disposable absorbent garment comprising an absorbent composite as previously described. A wide variety of absorbent garments are known to those with a skill in the art. The absorbent composites of the present invention can be incorporated into such known absorbent garments. Exemplary absorbent garments are generally described in U.S. Patent Nos. 4,710,187 issued December 1, 1987, to Boland et al .; 4,762,521 granted on August 9, 1998, to 29 Roessler et al .; 4,770,656 granted on September 13, 1988, to Proxmire and others; the 4,798, 603 grants of January 17, 1989, to Meyer and others; whose references are incorporated herein by reference.

As a general rule, absorbent disposable garments in accordance with the present invention comprise a body side liner adapted to contract the skin of a wearer, an outer covering superimposed in facing relationship with the liner, and an absorbent composite, such as those previously described, superimposed on said outer cover and located between the lining of the body side and the outer cover.

TEST METHODS To Test Superabsorbent Materials: The methods for determining the particle size distribution and the mean particle size of the hub for a given sample of superabsorbent material are described below. Additionally, the method for determining the inflation time and the gel bed vacuum space of the superabsorbent particles is disclosed below. 30 Particle Size Distribution Test Method (PSD) The particle size distribution test method used in the present invention determines the particle size distribution of a superabsorbent material by sieve size analysis. A stack of sieves are used to determine the particle size distribution for a given sample. Therefore, for example, in principle, a particle that is retained in a sieve with openings of 710 microns is considered to have a particle size greater than 710 microns. A particle that passes through a sieve having 710 micron openings and is retained in a sieve having 500 micron openings is considered to have a particle size between 500 and 710 microns. In addition, a particle passing through a sieve having 500 micron openings is considered to have a particle size of less than 500 microns.

The screens are placed in order of the size of the openings with the largest openings on top of the stack and the smaller openings at the bottom of the stack. A sample of 25 grams of superabsorbent particles is placed in the sieve with the largest openings. The sieve stack is shaken for 10 minutes with a Ro-Tap Mechanical Sifter Shaker, Model B available from W.S. Tyler from Mentor, Ohio, or with another device shaking a similar one. After the shaking is complete, the retained superabsorbent particles 31 in each sieve are removed and the weight measured and recorded. The percentage of the particles retained in each sieve is calculated by measuring the weights of the particles retained in each sieve by the weight of the initial sample.

Method of Testing the Mean Particle Size of Mass As used herein, the term "average mass particle size" of a given sample of superabsorbent particles is defined as the size of the particle, which divides the sample in half on a mass basis, eg, half of the sample that is why it has a particular size larger than the average particle size of mass and half of the sample per mass has a particle size minus the average particle size of mass. Therefore, for example, the average particle size of mass of a sample of superabsorbent particles is 500 microns if one half of the sample by weight is retained in a sieve with openings of 500 microns.

FAUZL Spotting Test (Absorbency Grown Under Zero Load) The mass of a plunger and a cup of Absorbency Under Load (AUL) is weighed and recorded as "Me". The absorbency rate under load is made one inch inside the diameter of thermoplastic tubing which is slightly turned to obtain concentricity. The absorbance rate 32 under load has a 400 mesh stainless steel screen is adhered to the bottom of the rate by means of an adhesive. Alternatively, the screen can be fused to the bottom of the cylinder by heating the wire screen in a flame to red hot, after which the absorbance rate under load is maintained on the screen until it cools. A soldering iron can be used to retouch the seal if it is not successful or if it breaks. Care should be taken to maintain a smooth bottom, flat, and do not distort the interior of the absorbency rate under load. The plunger is made of 1 inch diameter solid material (eg plexiglass) and turned to tightly fit without joining in the absorbency cup under load. Before placing the superabsorbent on the screen of the absorbency cup under load, the superabsorbent material is sieved to the appropriate size for the test.

Approximately 0.160 grams of superabsorbent material is placed in the absorbency cup under load, where the superabsorbent material is evenly distributed over the bottom of the cup. A plunger weighing 4.0 grams is placed on top of the dry superabsorbent material, yielding a pressure of approximately 0.01 pounds per square inch. The mass of the absorbency cup under load, the plunger and the dry superabsorbent material is weighed and recorded, as "Mo". 0.9% by weight of saline solution is added to a Petri dish (at least 2 inches in diameter) at a depth of 0.5 centimeters. A plastic screen 33 having approximately 16 openings per square inch is placed in the bottom of the Petri dish.

The cup of absorbency under load is placed in the saline for 15 seconds to allow the salt to be absorbed in the superabsorbent material. The bottom of the absorbency cup under load is quickly placed on a paper towel to remove any liquid on the screen or in the interstitial spaces between the superabsorbent particles. The time of removal of the absorbency cup under load of the saline for placement on the paper towel should be 3 seconds or less. The cup is moved to the dry parts of the paper rate until no liquid is observed that is transferred from the cup to the towel. Then, the solvency rate under load, the plunger and the superabsorbent material are weighed and the mass is recorded as "Mt". The total time to remove the liquid from the interstitial spaces, weigh the absorbency rate under load, and place the absorbency cup under load back in the saline should be less than 30 seconds. The cup of absorbency under load is quickly placed back into the salt for an additional 15 seconds to allow the salt to be absorbed by the superabsorbent material. Once again, the bottom of the cup is dried and the Mt is determined. The Mt is obtained by the following cumulative exposure times, where the "exposure time" is defined as the time that the superabsorbent is immersed in the liquid : 0.25, 0.5, 34 0.75, 1.0, 2.0, 2.5, 3.0, 4.0, 5.0, 10, 20, 40 and 60 minutes. The complete test is conducted three times for each superabsorbent material to be examined, and an average of collected for the three replicates is determined for each exposure time.

Analysis of data: The amount of saline collected during each exposure time is determined by the following equation: g saline / g superabsorbent = (Mt-Mo) / (Mo-Me) The value of collected g / g at 60 minutes cumulative exposure time is determined and recorded as g / g (e). The characteristic time to reach 60% of the collected g / g value of 60 minutes is determined by the following equation: Pick-up value characteristic = 0.6 * g / g (e) A table listing the exposure time and the collection value is used to interpolate the characteristic time to collect 60% of the collected value of 60 minutes. 35 Experimental Procedure of the Gel Bed Vacuum Space The Centrifugal Retention Capacity (CRC) of the superabsorbent particles is measured to obtain the full saturation capacity of the gel particles. 2.0 grams of the dried superabsorbent particles are then measured. An amount equal to (2.0 x Centrifugal Holding Capacity) grams of 0.9% by weight of saline is measured in a 20 milliliter beaker. The 2.0 grams of dry superabsorbent particles are added to 0.9% by weight of saline and stirred for 10 seconds to ensure no particle kneaded. The beaker is then capped with paraffin or another suitable cover and the superabsorbent is allowed to swell without altering for at least two hours so that the swelling reaches its equilibrium. After the swollen superabsorbent reaches its equilibrium, the average swelling height is marked inside the beaker by placing a lightweight acrylic plate (<0.02 pounds per square inch) on top of the swollen gel bed and mark the height of the bottom of the dish on the side of the beaker. The contents of the beaker are then emptied. After the beaker is emptied it is filled with water to the mark that designates the height of the swollen gel bed. The beaker is weighed to obtain the total volume of the swollen gel bed using the following equation: Volume = weight (grams) / l .0 grams per cubic centimeter. The vacuum spaces are then determined by subtracting the volume due to the salt and gel with the formula: Voids = Water Volume - [((2.0 Centrifugal Retention Capacity) / (specific gravity 0.9% by weight of saline )) + (2.0 grams of superabsorbent / 1.5 grams per cubic centimeter)].

To Test Absorbent Compounds: The test methods for determining the Saturation Capacity (SC), the Intermittent Vertical Runoff (IV), and the Fluid Admission Evaluation (FIE) of a given absorbent compound are described below.

Saturation Capacity Test (SC) A superabsorbent and lint compound, or only lint, is formed with tissue air at a desired density and basis weight. The samples of the compound are cut to a desired size, in this case, the samples of the compound are cut into rectangles of 3.5 inches (8.89 centimeters) by 10 inches (25.40 centimeters). The weight of each sample of the compound is then measured and recorded. This is the dry weight of the compound. The samples of the compound are then soaked in a 0.9% by weight NaCl solution for 20 minutes. After 20 minutes of soaking, the compound samples are placed under a vacuum pressure of 0.5 pounds 37 per square inch (14"¾0) for 5 minutes.This is the wet weight of the compound.The capacity of each sample of the compound is calculated by subtracting the weight of the dry compounds from the weight of the wet compound for each sample.

The Intermittent Vertical Transmission Test (IVW) The Intermittent Vertical Transmission Test (IVW) measures the transmission rate and fluid distribution profile of a material or compound during a series of liquid contacts. The test consists of three separate contacts between a bottom edge of a vertically suspended absorbent composite sample and a saltwater solution. Each separate contact or liquid discharge to the compound represents 15% of the saturation capacity of the absorbent compound as measured in the SC test described above. Each separate liquid discharge in the intermittent vertical transmission test is equal to (0.15) x (mtotai) so that the compound has a desired degree of absorption capacity during each discharge. The absorbent composite sample is allowed to transmit the liquid as described below.

A superabsorbent and lint compound is formed by air on the tissue at a desired basis weight and density. The composite samples are cut to a desired size, in this case, the composite samples are cut into a rectangle of 8.89 cm by 25.40 cm. The saturation capacity of the sample (mtotai) is determined as written above. An amount equal to (0.15) x (mtotai) is calculated.

A separate sample is suspended vertically so that the long dimension of the sample is in the vertical direction. The suspended sample is connected to a voltage meter. The sample is then lowered into a reservoir containing 0.9% by weight of NaCl solution. The amount of sample that is in contact with the solution should be a quarter of an inch or less. The amount of liquid collected is measured as a function of time, and it is allowed to continue until 15% of the saturation capacity of this absorbent compound [(0.15) x (mtotai)] is recorded on the voltage meter. The sample is then removed from the NaCl solution, but is kept in a vertical configuration.

After a period of 30 minutes, the sample is again lowered into the solution of 0.9% by weight of NaCl. The amount of liquid collected is measured as a function of time and it is allowed to continue until 15% of the saturation capacity of this absorbent compound [(0.15) x (mtotai)] has been recorded on the voltage meter. The sample is then removed from the NaCl solution, but they are maintained in a vertical configuration.

After a period of 30 minutes, the sample is lowered into the solution of 0.9% by weight of NaCl for a third time. The amount of liquid collected is measured as a function of time, and is allowed to continue until a saturation capacity of 15% of this absorbent compound [(0.15) x (mtotai)] is recorded on the voltage meter. The sample is then removed from the NaCl solution, but is kept in a vertical configuration.

The sample is then subjected to the test methods to determine the fluid distribution profile of the sample. Any test method can be used to determine the fluid distribution profile of the sample. A known method is to cut the absorbent composite into strips having a width of 1.27 cm, and weigh the strips to determine the amount of fluid within a given strip. In the aforementioned sample, 20 strips having a width of 1.27 cm and a length of 8.89 cm are produced from each sample of compound. A fluid distribution profile determined by weighing each strip to determine the amount of fluid in each strip. The amount of fluid is determined for each strip by the following equation: amount of fluid per strip = wet weight of the strip - (dry weight of the complete sample / 20).

The intermittent vertical transmission procedure is repeated with two composite samples cut from the same composite material. An average collection time determined for the first three collections of liquid, the 40 three second collections of liquid, and three third collections of liquid. In addition, the average amount of liquid in each half-inch segment of the three composite samples was determined as described above.

Fluid Testing Evaluation Test (FIE) The fluid intake evaluation test (FIE) measures the taking capacity of a material or compound. The test consists of subjecting an absorbent compound to three discharges of liquid, where each liquid discharge represents 30% of the saturated capacity of the compound as determined by the SC test described above. The three discharges of liquids are spaced and separated by fifteen minute intervals.

A superabsorbent and fluff compound is formed by air in the tissue at a desired basis weight and density. A composite sample is cut to a desired size, in this case, the composite sample cut into a rectangle of 8.89 cm by 12.70 cm. The saturation capacity of the sample (nitotai) was determined as described above. An amount equal to (0.30) x (mtotai) is calculated - A liquid addition device 10, as shown in Figure 2, is placed on top of a sample of separate compound 12 (also cut to a rectangle of 8.89 cm by 12.70 cm) to produce a pressure of about 41 0.13 pounds per square inch (8966 dines / cm) the liquid addition device includes a base 14 and an additional bronze weight 16 to make the total mass of the device 10 equal 1223 grams. The liquid is brought into contact with the sample 12 by introducing the liquid through a tube 18 located in the liquid addition device 10. A first liquid discharge of a solution of 0.9% by weight of NaCl equal to 30% of saturation capacity of the absorbent compound [(0.30) x (mtotai)] r is introduced through the tube 18 and brought into contact with the sample of the compound 12. The amount of time required for the entire first liquid discharge to be soaked in the sample of compound 12 is measured. After 15 minutes from the start of the first discharge, a second liquid discharge of the solution of 0.9% by weight of NaCl equal to 30% of the saturation capacity of the absorbent compound [(0.30) x (mtotai)] r is set in contact with the sample of compound 12. The amount of time required for the entire second discharge of liquids to be soaked in the sample of compound 12 is measured. After an additional 15 minutes from the start of the second discharge, a third discharge of liquid of a solution of 0.9% by weight of NaCl, equal to 30% of the saturation capacity of the absorbent compound [(0.30) x (mtotai)], is contacted with the sample of compound 12. The amount of time required for all the third liquid discharge to be soaked into compound 12. 42 The procedure is repeated with two more composite samples cut from the same composite material. An average take time is calculated for the first three, for the three seconds and for the three third liquid discharges. Additionally, the average take time of the total discharge is calculated as the sum of the average take time of the first, second and third discharges.

Those skilled in the art will readily understand that the superabsorbent materials and absorbent composites of the present invention can be advantageously employed in the preparation of a wide variety of products, including, but not limited to, absorbent personal care products designed to be put on contact with the body fluids. Such products may only comprise a single layer of the absorbent compound or may comprise a combination of elements as described above. While the superabsorbent materials and absorbent composites of the present invention are particularly suitable for personal care items, the superabsorbent materials and absorbent composites can be advantageously employed in a wide variety of products to the consumer.

The present invention is further illustrated by the following examples, which should not be considered in any way as imposing limitations on the scope of the same. On the contrary, it should be clearly understood that several other incorporations, modifications and equivalents thereof must be used which, after reading the description given herein, may be suggested to those experts in the art without departing from the spirit of the present. invention and / or scope of the appended claims.

EXAMPLES In the examples given below, the absorbent composites were produced using the following fibrous materials and superabsorbent materials: Superabsorbent material: AFA-177-9A, AFA-177-9B, AFA-177-140 and Drytech 2035, supplied by Dow Chemical Co. of Midland, MI.

Fibrous Material: Fluffy pulp fibers, CR-1654 supplied by Alliance Forest Products of Coosa Pines, AL. 44 EXAMPLE 1 Determination of the Particle Size Distribution of Superabsorbent Material Samples Two 100 g samples of AFA-177-9A and AFA-177-9B were supplied by Dow Chemical Co. of Midland, MI. The particle size distribution of each sample was measured using the PSD test method described above. The sieves having the following mesh sizes were used for the AFA-177-9A samples: 1680 micras, 1190 micras, 1000 micras and 850 micras. The screens having the following mesh sizes were used for the sample AFA-177-9B: 150 microns, 105 microns, and 63 microns.

The particle size distributions of samples AFA-177-9A and AFA-177-9B are given below in Tables 1 and 2.

Table 1. Particle Size Distributions of the sample AFA-177-9A. 45 Table 2. Particle Size Distributions of the sample AFA-177-9B.

As can be seen from tables 1 and 2 given above, the average particle size of the particles in samples AFA-177-9A and AFA-177-9B are around 1100 microns and 100 microns, respectively.

EXAMPLE 2 Preparation of Absorbing Compounds of the Present Invention Absorbent composites were formed using the superabsorbent material AFA-177-140 supplied by Dow Chemical Co. of Midland, MI and pulp fibers, CR-1654, supplied by Alliance Forest Products of Coosa Pines, AL. The superabsorbent material AFA-177-140 had essentially the same chemical composition as the samples AFA-177-9A and AFA-177-9B of example 1. The superabsorbent material AFA-177-140 was milled using the methods known in the art for give two samples, sample 1A and sample IB, which have particle size distributions similar to the samples AFA-177-9A and AFA-177-9B described in example 1. The compounds were formed through a unit of training with conventional air. The mass ratio of sample 1A (large particles) to sample IB (small particles) in the compounds was varied as follows: 50:50, 70:30, 80:20, and 90:10. The compounds had a total target weight basis of 500 grams per square meter, an objective density of 0.2 g per cubic centimeter, and an SAP concentration of 50% by mass.

The average particle size of the particles in samples 1A and IB at a saturation level of 30 gm of 0.9% by weight of the NaCl solution per gm of SAP was determined. In addition, the hollow spaces in the beds of saturated superabsorbent particles and the specific gravity of the particles were determined experimentally using the experimental chamber and gel hollow space procedure. The results are given in table 3 given below.

Table 3. Parameters for the calculation of theoretical particle proportion. Diameter Dry Diameter Hollows Gravity of Saturated Medium @ 30g / g Specific Mass (micras) Mass Medium (v) (P) (micras) Component 1 1100 3930 0.18 1.02 Component 2 105 375 0.07 1.02 47 Using the equations given above together with the values for vx (the hollow space in the sample particle system 1A), v2 (the hollow space in a sample IB particle system), px (the true specific gravity of the sample particles 1A),? 2 (the true specific gravity of the sample particles IB), experimentally determined, the ratio of particular large (particles of sample 1A) to small particle (particles sample IB) theoretical as shown below. < Pi = [0 -.) · Pj] [(1 - v,) · p, + v, · (1 - v2) · p2] = [(1 - 0.18) · 1.02] ÷ [(1 - 0.18) · 1.02 + 0.18 · (1 - 0.07) · 1.02] = 0.83 F = f, + (1-f,) = 0.83 + (1 - 0.83) = 1 The percent by theoretical weight of each component must be: f? / F = percent by weight of the component: Percent by weight of sample 1A (large particles) = (f1 /) x 100 = 83% Percent by weight of sample IB (small particles) = [(1- F?, / F]? 100 = 17% Since both components are presumed to be at the same level of saturation at equilibrium, the percentages of dry weight they will be the same as the saturated weight percentages calculated above.

EXAMPLE 3 Preparation of control sorbent compounds using a conventional particle size distribution An absorbent control composite was made using the same materials as in Example 2, except that the superabsorbent material had a particle size distribution ranging from 0 to 850 microns. This control is mentioned here as control 1. Specifically, control 1 was determined to have a particle distribution as shown below.

Table 4. Distribution of Median Particle Size of Control Mass 1 A second control compound was prepared using 50% of Drytech 2035 supplied by Dow Chemical Co. of 49 Midland, MI and 50% of Blot Alliance CR-1654 supplied by Alliance Forest Products of Coosa Pines, AL. The compound was formed in order to compare the compounds of the present invention with a compound comprising a representative superabsorbent material which is used in commercial products. The control compound containing Drytech 2035 is mentioned herein as control 2. Table 5 establishes the particle size distribution of control 2.

Table 5. Distribution of Median Particle Size of Control Mass 2 EXAMPLE 4 Performance of Transmission of Absorbent Compounds of the Present Invention and of Control Compounds The transmission performance of the compounds of examples 2 and 3 was evaluated using an intermittent vertical transmission (IVW) test described above. The distribution of fluid within each compound was analyzed after the third discharge of the liquid by determining the amount of liquid in each 0.5-inch segment of the compound. The amount of liquid in each section was divided by the amount of liquid for that sample in the 0-0.5-inch segment for that sample. This value was multiplied by 100 to obtain the percentages shown below in Table 6.

Table 6. Average Fluid Distribution after the Third Insult As can be seen from the data in Table 6, a better fluid distribution and transmission was experienced with the compounds containing a bimodal superabsorbent particle size distribution. This is evident by the larger amounts of fluid located in the upper parts of the compounds (> 5").

The fluid distribution of the absorbent compounds of the present invention was improved by the presence of a bimodal particle size distribution as seen by the increased amount of fluid in the upper parts of the compounds. The rate of fluid intake during the IVW test was also found to be improved in some of the bimodal systems as shown in the bimodal systems as shown in Tables 7 and 8 below.

Table 7. Taking of Third Average Discharge Against Time Table 8. Collection of Third Discharge Average Interval of Compound Absorbing Time Amount of Collection of Third Discharge Expressed as (seconds) Percentage of Quantities of Collection of Objective 50:50 70:30 80:20 90:10 Control 1 Control 2 50 34% 42% 62% 42% 44% 40% 100 48% 62% 74% 50% 56% 48% 150 56% 70% 88% 60% 68% 58% 200 64% 82% 98% 66% 71% 63% 250 66% 90% 100% 70% 76% 66% 300 68% 92% 74% 82% 63% 350 78% 94% 80% 87% 67% 52 As can be seen from the data in Tables 7 and 8, the transmission rates were affected by the amount of large and small particles present in the absorbent compound. The collection of fluid from the third average discharge suggests that the presence of too many very small particles or large particles negatively impact the rate of transmission of the compound. It is believed that the tendency of the small particles to cause a gel block in the reduced capillarity caused by the large particles negatively impacts the rate of compound transmission.

In addition to noting that the rate of transmission of an absorbent compound having a bimodal particle distribution and a ratio of 80/20 weight / weight showed improvements over the control compounds having a regular particle distribution.

The above data from Tables 6-8 suggest that the fluid distribution and the rate of transmission can be improved in compounds containing a large particle to small particle ratio suitable in the bimodal superabsorbent particle size distribution. 53 EXAMPLE 5 Performance of Fluid Collection of the Absorbing Compounds of the Present Invention and Control Compounds The intake performance of the compounds of Example 2 and of the control compounds of Example 3 were evaluated using the fluid intake evaluation (FIE) as described in the "Test Method" section above. The results of the fluid intake evaluation are given in Table 9.

Table 9. Fluid Collection Evaluation Results for Absorbent Compounds As seen from the data in Table 9, the composite samples having a weight ratio of superabsorbent material of 80% by weight of sample 1A (large particles) to 20% by weight of sample IB (small particles) gave the average total discharge time plus 54 low, as well as the second and third lowest average discharge time.

EXAMPLE 6 Determination of Swelling Time of Superabsorbent Particles in the Absorbent Compounds of the Present Invention The time of swelling of the large particles of the sample AFA-177-9A and of the small particles of the sample AFA-177-9B was determined using the FAUZL test as described above. The results of the test are provided in Table 10 given below.

Table 10. Superabsorbent Particle Swelling Time The examples described above are the preferred embodiments and are not intended to limit the scope of the present invention in any way. Various modifications and other incorporations of uses of superabsorbent polymers evident to those skilled in the art

Claims (43)

R E I V I N D I C A C I O N S

1. An absorbent composite comprising superabsorbent material, wherein the superabsorbent material comprises superabsorbent particles having a bimodal particle size distribution with large particles having a median particle mass size of from about 850 to about 1800 microns and small particles which have a median particle size of mass from about 50 to about 200 microns.

2. The absorbent compound as claimed in clause 1, characterized in that the large particles have a mass median particle size of from about 1000 about 1600 microns.

3. The absorbent compound as claimed in clause 1, characterized in that the large particles have a median particle size of mass of from about 65 about 150 microns.

4. The absorbent compound as claimed in clause 1, characterized in that the superabsorbent particles have a median particle size of overall mass of about 60 of about 1750 microns.

5. The absorbent compound as claimed in clause 1, characterized in that the superabsorbent particles have a median particle size of overall mass of about 800 to about 1200 microns.

6. The absorbent compound as claimed in clause 1, characterized in that the median particle size of the mass of the large particles, the median particle size of the mass of the small particles differs by at least about 500 microns.

7. The absorbent compound as claimed in clause 6, characterized in that the ratio of the medium particle size mass of the large particles to the medium particle size of the mass of the small particles is from about 4: 1 to about 36 :1.

8. The absorbent compound as claimed in clause 6, characterized in that the ratio of the medium particle size mass of the large particles to the medium particle size of the mass of the small particles is from about 6: 1 to about 25 :1.

9. The absorbent compound as claimed in clause 6, characterized in that the medium particle size of the mass of the large particles is from about 1000 to about 1200 microns, and the medium particle size of the small particles is from around 50 to around 150 micras.

10. The absorbent compound as claimed in clause 6, characterized in that the median particle size of the mass of the large particles is from about 1000 to about 1100 microns, and the median particle size of the small particles is from around 50 to around 100 micras.

11. The absorbent compound as claimed in clause 1, characterized in that the mass ratio of the large particles to the small particles is from about 90:10 to about 50:50.

12. The absorbent compound as claimed in clause 1, characterized in that the mass ratio of the large particles to the small particles is from about 90:10 to about 80:20.

13. The absorbent compound as claimed in clause 1, characterized in that the mass ratio of large particles to small particles is about 85:15.

14. The absorbent compound as claimed in clause 1, characterized in that the superabsorbent material is evenly distributed within the composite.

15. The absorbent compound as claimed in clause 1, characterized in that the absorbent compound comprises from about 20% to about 100% by weight of the superabsorbent material.

16. The absorbent compound as claimed in clause 1, characterized in that the absorbent compound comprises from about 30% to about 90% by weight of the superabsorbent material.

17. The absorbent compound as claimed in clause 1, characterized in that it also comprises a containment device.

18. The absorbent compound as claimed in clause 16, characterized in that the containment device is a fibrous matrix.

19. The absorbent compound as claimed in clause 1, characterized in that the absorbent compound has a liquid discharge recess time of less than about 100 seconds.

20. The absorbent compound as claimed in clause 1, characterized in that the absorbent compound has a third liquid discharge time of less than about 85 seconds.

21. The absorbent compound as claimed in clause 1, characterized in that the absorbent compound has a third liquid discharge time of less than about 60 seconds.

22. The absorbent compound as claimed in clause 1, characterized in that the absorbent composite has a third intermittent vertical transmission collection time of less than about 600 seconds.

23. The absorbent compound as claimed in clause 1, characterized in that the absorbent composite has a third intermittent vertical transmission collection time of less than about 300 seconds.

24. The absorbent compound as claimed in clause 1, characterized in that the small particles have a swelling time of from about 15 to about 35 seconds and the large particles have a swelling time of from about 300 to about 700 seconds.

25. The absorbent compound as claimed in clause 24, characterized in that the swelling time of the small particles is about 20 times shorter than the swelling time of the large particles.

26. An absorbent composite comprising a superabsorbent material wherein the superabsorbent material comprises superabsorbent particles having a bimodal particle size distribution, and wherein the absorbent compound has a third liquid discharge intake time of less than about 100 seconds.

27. The absorbent compound as claimed in clause 26, characterized in that the absorbent compound has a third liquid discharge intake time of less than about 85 seconds.

28. The absorbent compound as claimed in clause 26, characterized in that the absorbent compound has a third liquid discharge intake time of less than about 60 seconds.

29. The absorbent composite as claimed in clause 26, characterized in that the absorbent composite has a third intermittent vertical transmission pickup time of less than about 600 seconds.

30. The absorbent composite as claimed in clause 26, characterized in that the absorbent composite has a third intermittent vertical transmission collection time of less than about 300 seconds.

31. The absorbent compound as claimed in clause 26, characterized in that the superabsorbent material is evenly distributed within the composite.

32. The absorbent compound as claimed in clause 26, characterized in that in the superabsorbent particles they comprise small particles having a swelling time of from about 15 about 35 seconds and large particles having a swelling time of from about from 300 to around 700 seconds.

33. The absorbent compound as claimed in clause 32, characterized in that the swelling time of the small particles is about 20 times shorter than the swelling time of the large particles.

34. The absorbent compound as claimed in clause 26, characterized in that the superabsorbent particles comprise large particles having a median particle mass size of from about 850 to about 1800 microns.

35. The absorbent compound as claimed in clause 26, characterized in that the superabsorbent particles comprise small particles having a median particle mass size of from about 50 to about 200 microns.

36. The absorbent compound as claimed in clause 26, characterized in that the absorbent compound comprises from about 30% to about 90% by weight of superabsorbent material.

37. The absorbent compound as claimed in clause 26, characterized in that the mass ratio of large particles to small particles is from about 90:10 to about 50:50.

38. An absorbent composite comprising superabsorbent material, wherein the superabsorbent material is uniformly distributed within the compound, and wherein the compound has a third liquid discharge intake time of less than about 100 seconds and a third vertical transmission collection time. intermittent of less than about 600 seconds.

39. The absorbent compound as claimed in clause 38, characterized in that the compound has a third liquid discharge intake time that is less than about 85 seconds.

40. The absorbent compound as claimed in clause 38, characterized in that the compound has a third liquid discharge intake time that is less than about 60 seconds.

41. The absorbent compound as claimed in clause 38, characterized in that the composite has a third intermittent vertical transmission take-up time of less than about 300 seconds.

42. The absorbent compound as claimed in clause 38, characterized in that the compound comprises from about 20 to about 100% by weight of superabsorbent material.

43. The absorbent compound as claimed in clause 38, characterized in that the compound comprises from about 30% to about 90% by weight of the superabsorbent material. R E S U E N The present invention is directed to an absorbent composite containing superabsorbent material. The superabsorbent material is in the form of superabsorbent particles having a bimodal particle size distribution. The use of the superabsorbent material having a bimodal particle size distribution in the absorbent structure results in an improved fluid distribution and in a fluid intake of the absorbent composite. The absorbent composition of the present invention is useful in disposable personal care products.