RU2214205C2 - Cellulose mass and superabsorbing composite for absorption improvement - Google Patents

Abstract

FIELD: personal hygiene products. SUBSTANCE: expanding absorbing composite containing cellulose mass in amount approximately from 28 to 90 wt.% superabsorbing material in amount approximately from 8 to 70 wt.% and binding fiber in amount approximately from 2 to 20 wt.%, where composite has density approximately from 0.1 to 0.3 g/cu.cm. Such composite is applicable in products of personal hygiene such as diapers, training trousers, absorbing drawers, items used in incontinence of urine in adults, etc. EFFECT: provided comfort for user. 12 cl, 3 dwg, 2 tbl

Description

 The invention relates to absorbent articles, especially to absorbent structures used in personal care products, such as disposable sanitary napkins, diapers or incontinence devices.

 Desired goals when operating absorbent personal care products include little or no leakage from the product, a feeling of dryness for the consumer, and subtlety as a means to provide comfort to the consumer. Modern absorbent products, however, are often unable to meet these goals for a variety of reasons.

 Seepage can occur, for example, due to insufficient absorption rate by layers designed to provide retention or dispersal ability in the absorption or destination zone. Attempts to reduce the leakage occurring by this mechanism are to create absorbent products that include structures that reversibly change the volume of material located above (i.e. towards the consumer) retaining or dispersing materials. US Pat. No. 5,364,382. Latimer discloses nonwoven materials, such as meltblown, fleece glued fabrics, and cellulosic molds that receive and then release fluid into retention aids. Structures of Latimer materials use large denier elastic fibers mixed with wettable small denier fibers to achieve rapid absorption of liquid and rapid release of liquid into the containment material underneath. Additionally, US Pat. No. 5,490,846 to Ellis discloses layered structures for improving the absorption rate of reversibly volume-changing materials.

 Despite such a development of reversibly volume-changing materials, which attempts to achieve rapid absorption and rapid release into the retaining material, the goal remains to satisfactorily achieve fineness. These reversibly volume-changing materials are quite thick, and when placed in the absorption zone of the absorbent article, they can cause an unpleasant sensation in the perineal region of the absorbent article when first worn and can lead to several operational problems. Firstly, the product may leak due to loose contact, which is formed by a thick reversibly volume-changing material. Secondly, the product is inconvenient for the consumer when using a thick material to provide the necessary free volume for absorption. Consequently, there remains a need for materials that will quickly absorb the release to the target area and either accumulate the release or release it for subsequent accumulation and which, therefore, remain relatively thin before the selection.

 The present invention is to create a material for personal care products, which quickly absorbs the selection, which can accumulate it or transfer it to the neighboring material for dispersal or accumulation and which remains relatively thin before such selection. Another objective of the present invention is to create a personal care product, which, prior to isolation, is thin and convenient for the consumer.

 The objectives of the present invention are achieved through materials and products that are designed to be very thin before isolation and to expand rapidly during isolation.

The present invention is an expandable absorbent composite made from a pulp in an amount of from about 30 to about 90 wt.%, A superabsorbent material in an amount of from about 10 to about 70 wt.% And a binder in a sufficient amount, for example, from about 1 to approximately 20 weight. %, where the composite has a density of from about 0.1 g / cm ³ to about 0.3 g / cm ³ .

 Such a composite can be used in personal care products like diapers, sweatpants, absorbent underpants, feminine hygiene items, items used for adult incontinence, and the like.

 FIG. 1, 2 and 3 are graphs of the generation of free volume in various composites of the present invention at saturation.

"Hydrophilic" describes fibers or surfaces of fibers that are wetted by aqueous liquids upon contact with the fibers. The degree of wetting of the materials can, in turn, be described on the basis of contact angles and surface tensions of the liquids and materials in question. Suitable equipment and techniques for measuring the wettability of specific fibrous materials or mixtures of fibrous materials can be provided by the Cahn SFA-222 Surface Force Analyzer System or a substantially equivalent system. When measured by this system, fibers having contact angles of less than 90 ^° are designated as “wettable” or hydrophilic, while fibers having contact angles equal to or greater than 90 ^° are designated as “non-wettable” or hydrophobic.

 A “layer”, when used in the singular, may have the double meaning of a single element or a plurality of elements.

 "Liquid" means a non-gaseous, not divided into parts substance and / or material that flows and can take the internal shape of the vessel into which it is poured or placed.

The term "nonwoven fabric or mesh" means a mesh having a structure of individual fibers or threads that are intertwined, but which cannot be identified as knitted material. Non-woven materials or meshes are obtained in many ways, such as, for example, melt blowing processes, bonding processes during spinning, and processes for producing a glued mesh with a pile. The basis weight of nonwovens is usually expressed in ounces of material per square yard (y / y ² ) or grams per square meter (g / m ² ), and the diameter of the fiber used is usually expressed in microns. (Note: to turn y / ² into g / m ^2, you need to multiply y / ² by 33.91.)
The term "microfibers" means small diameter fibers having an average diameter of not more than about 75 microns, for example, having an average diameter of from about 0.5 microns to about 50 microns, or, more specifically, microfibers can have an average diameter of from about 2 microns to about 40 microns. Another commonly used expression for fiber diameter is denier, which is defined as the number of grams per 9000 meters of fiber and can be calculated as the square of the diameter of the fiber in microns, multiplied by the density in grams / cm ² and multiplied by 0.00707. A lower denier indicates a finer fiber, and a higher denier indicates a thicker or heavier fiber. For example, a fiber diameter of polypropylene, given as 15 microns, can be converted into denier by squaring, multiplying the result by 0.89 g / cm ² and multiplying by 0.00707. Thus, a 15 micron polypropylene fiber has a denier of about 1.42 (15 ² • 0.89 • 0.00707 = 1.415). Outside the United States, the Tex unit, which is defined as the number of grams per kilometer of fiber, is more common. Tex can be calculated as denier / 9.

 The term “fibers obtained by bonding during spinning” refers to fibers of small diameter that are obtained by extruding molten thermoplastic material in the form of filaments from a variety of thin, usually round capillaries of a die with a diameter of extrudable filaments, which are then rapidly reduced, as, for example, in U.S. Pat. No. 4,340,563 to Appel and others; and U.S. Pat. No. 3,692,618 to Dorschner and others; U.S. Pat. No. 3,802,817 to Matsuki and others; U.S. Pat. Nos. 3,338,992 and 3,341,394 to Kinney; U.S. Pat. Hartman) and US patent US 3542615 Dobo (Dobo) and others. The fibers obtained by bonding during spinning are usually not sticky when they are deposited on a collecting surface. The fibers obtained by bonding during spinning are usually solid and have average diameters (from the sample of at least 10 pieces) of more than 7 microns, more precisely, between 10 and 20 microns.

 The term “meltblown fibers” means fibers obtained by extruding molten thermoplastic material through a variety of thin, usually round, stamped capillaries in the form of molten filaments or filaments into high-speed, usually hot gas (eg, air) streams that thin out filaments of molten thermoplastic material to reduce their diameter, which can be brought to the diameter of microfiber. After this, the fibers blown out of the melt are transferred by a high-speed gas stream and deposited on a collecting surface to form a mesh of statistically placed meltblown fibers. Such a process is disclosed, for example, in US Pat. No. 3,849,241. Melt-blown fibers are microfibers that can be continuous or discontinuous, typically of an average diameter of less than 10 microns, and usually sticky when deposited on a collecting surface.

 The term “spinning” means a method in which at least one die head for blowing a melt is located near a drain pipe for transporting fiber through which other materials are added to the mesh during its formation. Such other materials may be, for example, wood pulp, superabsorbent particles, cellulose or staple fibers. The forming processes are shown in the well-known US Pat. Nos. 4,818,464 to Lau and 4,100,324 to Anderson and others. The nets obtained by the molding process are commonly referred to as molded materials.

 The term “conjugated fibers” refers to fibers that are obtained from at least two polymer sources extruded from separate extruders, but spun together to form one fiber. Conjugate fibers are also sometimes referred to as multicomponent or bicomponent fibers. Polymers are usually different from each other, although conjugated fibers can be monocomponent fibers. The polymers are mainly located in constantly located different zones across the cross section of the conjugate fibers and stretch continuously along the length of the conjugate fibers. The configuration of such a conjugate fiber may be, for example, a shell / core arrangement where one polymer is surrounded by another, or may be an adjacent arrangement, a pie arrangement, or an “island in the sea” arrangement. Conjugate fibers are, for example, described in US Pat. No. 5,382,400 to Pike and others, and they can be used to produce corrugation in fibers using different expansion and shrink rates of two (or more) polymers. Such fibers may also be splittable. Corrugated fibers can also be obtained by mechanical means and method according to German patent application DE 2513251 A1. For bicomponent fibers, polymers may be present in 75/25, 50/50, 25/75, or any other desired ratios. The fibers may also have shapes as described in US Pat. No. 5,277,976 to Hogle and others, which describes fibers with unusual shapes.

 Methods for producing conjugated fibers are well known and do not require a detailed description here. In order to obtain a conjugated fiber, usually two polymers are extruded separately and fed into a polymer distribution system, where the polymers are introduced into a segmented die plate. The polymers follow separate paths into the fiber spinneret and are joined in a spinneret hole that contains two or more concentric round holes, thereby producing sheath / core fibers, or the round spinneret hole is split along the diameter into two parts to obtain fibers adjacent type. The combined polymeric filament is then cooled, cured and usually drawn on a mechanical roller system to an intermediate diameter of the filament and collected. Then the filament is subjected to "cold drawing" at a temperature below its softening temperature to the desired final fiber diameter, crimped / textured and cut into fibers of the desired length. Conjugate fibers can be cut into relatively short fibers, such as staple fibers, which typically have a length in the range of 25 to 51 millimeters (mm), and shortly cut fibers that are even shorter and typically have a length of less than 18 millimeters. See, for example, US Pat. No. 4,798,592 to Taniguchi and others, and US Pat. No. 5,336,552 to Strack and others, both of which are incorporated herein by reference in their entirety.

 The term "fleece glued mesh" refers to nets that are made of staple fibers that are passed through a comb or carding unit that breaks into pieces and places the staple fibers in the direction of the machine to obtain a typically fibrous nonwoven mesh. Such fibers are usually transported in pressed bales, which are placed in a bobbin machine that separates the fibers in front of the combing unit. After the mesh is molded, then it is glued with one or more of the known gluing methods. One such bonding method is powder bonding, where the powdered adhesive is spread over a grid and then activated, usually by heating the grid and the adhesive with hot air. Another suitable gluing method is pattern bonding, where heated calender rollers or ultrasonic bonding equipment is used to stick the fibers together usually in a localized bonded pattern, although the mesh can be glued across its entire surface, if desired. Another suitable and well-known bonding method, especially when using conjugated staple fibers, is bonding in air.

 "Air overlay" is a well known method by which a fibrous nonwoven layer can be formed. During air deposition, bundles of small fibers, usually of length ranging from about 2 to about 19 millimeters (mm), are separated and placed in the supplied air, and then deposited on the forming screen, usually using a vacuum feed. The statistically deposited fibers are then bonded to each other using, for example, hot air or spraying an adhesive.

 "Personal care product" means diapers, sweatpants, absorbent underpants, feminine hygiene products and items used for adult incontinence.

Test methods
Material gauge (thickness): The material gauge, which is a measure of thickness, is measured at 0.00352 kg / m ^{2 with} a Starret-type thickness tester in centimeters.

Density: The density of the material is calculated by dividing the weight per unit area of a sample in grams per square meter (g / m ²⁾ at the caliber of the sample in millimeters (mm) 0.00352 kg / m ² (68.9 pascals) and multiply the result by 0.001, to convert the value into the number of grams per cubic centimeter (g / cm ² ). Typically, the sum of three samples was calculated and averaged to obtain a density value.

Absorption Time Index (VPI): In this test, the absorption capacity of a superabsorbent material is determined relative to up to 200 minutes at low pressure, for example, about 0.007 kg / m ² .

 A cylinder with an inner diameter of one inch (25.4 mm) was used with a solid 100 mesh stainless steel screen at one end to hold 0.16 ± 0.005 grams of dry superabsorbent. This superabsorbent should be carefully placed in the cylinder so that the superabsorbent does not adhere to the walls of the cylinder. The cylinder should be tapped gently to distribute superabsorbent on the screen more evenly. Then, a plastic piston weighing 4.4 grams and a diameter of 0.995 is placed in the cylinder, and the cylinder, piston and superabsorbent in the kit are weighed. The kit is placed in a 3 inch by 3 inch liquid tank (76.4 mm by 76.4 mm) containing 0.875 wt.% NaCl solution to a depth of 1 cm. The cylinder is gently tapped to remove all air trapped underneath , and maintain the salt solution depth of 1 cm throughout the test.

Use a timer capable of counting 200 minutes at intervals of one second. The timer is started and after 5 minutes of being in the solution, the kit is removed and printed on absorbent paper. A preferred paper is a paper table napkins Kleenex ^® Premium from Kimberly-Clark Corp., although it is possible to use any other suitable paper. When printing, press the paper firmly against the cylinder to ensure good contact. The cylinder is touched three times on dry paper, and very little liquid should be removed a third time. Weigh the kit and return the kit to the fluid reservoir. Printing and weighing should take about 5 seconds and the timer should run throughout the test. Take readings in 5, 10, 15, 30, 45, 60, 75, 90, 120, 160 and 200 minutes. Use fresh, dry wipes for each indication.

 After the last reading, the number of grams of liquid absorbed per gram of superabsorbent is counted. The amount of liquid adsorbed at a specific time divided by the amount absorbed in 200 minutes can be delayed relative to time to graphically represent the rate of absorption.

VPI is calculated as follows:
VPI = (t ₁₀ + t ₂₀ + t ₃₀ + t ₄₀ + t ₅₀ + t ₆₀ + t ₇₀ + t ₈₀ + t ₉₀ ) / 9,
where t _n is the time in minutes during which n percent of the absorption capacity is used at 200 minutes, for example, t ₃₀ is the time at which 30 percent of the total capacity is used.

Gravimetric Absorption Test (GAT): This test measures the time that the absorbent composite takes to absorb the discharge. The free volume and mass of the sample are also measured. Place a circle of the test material with a diameter of 6.8 cm on the platform for the sample of the GAT tester assembly with the installation point in the center of the sample. Suitable GAT tester from M / K Systems, Inc. Danvers, MA 01923, model number M / K 241, series number G1048. After zeroing the instrument, a pressure of 4 cm of positive hydrostatic pressure is set. Place weight on the sample to provide a pressure on the sample of 0.0352 kg / m ² (68.9 pascals). Liquid is supplied to the sample, maintaining constant hydrostatic pressure and recording the time required to absorb 10 grams of a NaCl solution with a concentration of 0.875 wt.%. Allow the sample to come to equilibrium in 30 minutes and repeat until the desired number of secretions is achieved. After the last selection, the sample is removed and the mass and thickness are measured at a pressure of 0.0352 kg / m ² .

 The material structures of the present invention are designed to be very thin materials that expand rapidly upon release. Therefore, when a consumer uses an absorbent article, it is very thin and comfortable and fits well. When the structure of the material expands during use, it creates the necessary free volume to receive the incoming fluid, the chances of which leak out, in turn, are reduced.

 There are several embodiments of this invention described below. All are designed to start with a very fine structure, which then expands upon contact with the fluid being released.

 The structure of the material consists of a modified fiber of pulp, a modified superabsorbent and a small amount of a binder, preferably a thermally activated binder fiber. The material is initially produced and stabilized at low density. The material is then compressed and fixed at a higher density as part of an absorbent system that meets the requirements of fineness. Upon isolation, the compressed structure recovers a significant part of its produced caliber, reaching a density intermediate between the produced and compressed states. An expandable composite provides maximum benefit when used as part of an absorbent system that moves fluid outside the target zone.

Specific examples include structures containing cellulosic fiber, superabsorbent material and thermoplastic binder fiber, and were produced on a Dan Web airborne system. Composites in the scope of the present invention contained 75% or 55% by weight of a crosslinked pulp fiber of the NHB-416 Weyerhauser Company and 5% by weight of Hoechst-Celanese Company conjugated fibers called Celbond T105. The superabsorbent materials were 20% or 40% by weight of AFA-130-53C Dow Chemical, W77553 Stockhausen or FAV880A Stockhausen. The materials were produced at low density (0.05 g / cm ³ ) and medium density (0.1 g / cm ³ ) and were thermally stabilized online. W77553 Stockhausen is a hydrophobic surface-prepared polymerized bulk polyacrylate. FAV880A Stockhausen is a commercially available NC 27406 from Stockhausen Company of Greensboro and is a super absorbent with a highly crosslinked surface. AFA-130-53C are particles of suspension polymerisation polyacrylate ranging in size from 850 to 1400 microns from the Dow Chemical Company from Midland, Michigan. The composites were compacted to a target absorbent product density of 0.20 g / cm ^{3 by} hot pressing in a wedge-shaped cutting press (1 minute at 80-100 ^° C). This pressing procedure resulted in materials that retained a density of 0.20 g / cm ³ throughout the expansion time. Although other pressing procedures and other commercially available compression procedures can also be used to obtain the desired structures, including continuous online calendering, lower pressing temperatures (<50 ^° C) with or without moisture resulted in materials that quickly re-swelled under normal conditions and did not maintain the long desired thin thickness to fall within the scope of the present invention.

A higher bonding temperature (150 ^{° C.} ) led to samples that were excessively glued and which did not expand rapidly upon wetting and therefore did not result in the required free volume necessary to fall within the scope of the present invention. This contrasts with the sample, which was glued under better conditions (80-100 ^o C) and quickly expands when wetted to a degree above 80% of its thickness when uncompressed and above 90% of its thickness when saturated, if you start with an uncompressed state.

 The preferred material structure, therefore, is a moist, elastic, but very hydrophilic chemically cross-linked cellulose fiber, such as NHB416 Weyerhauser (28 to 90% by weight), a low absorption superabsorbent such as AFA-130-53C Dow or W77553 Stockhausen (8 to 70% by weight) and a binder fiber, such as core-sheath conjugate fibers manufactured by Chisso, Hercules, Danaklon or Hoechst-Celanese, such as Celbond T105 / T255 fibers.

 By "low absorption rate" superabsorbent is meant a superabsorbent having an absorption time index (VPI) of at least 5 minutes, more preferably more than 10 minutes. Note that although superabsorbents with a low absorption rate are preferred, superabsorbents with a high absorption rate or conventional will also work, as discussed below. Superabsorbents with a high absorption rate act so that they bind the liquid quickly, limiting dispersion and plugging and lowering the overall dispersion of the liquid in the absorbent article, but still providing a very good absorption performance.

 The binder must be present in sufficient quantity to hold the structure together. However, lower amounts may be possible; an amount of a binder between about 1 and about 20% by weight is considered sufficient. Conjugated binder fibers are preferred, although any binder known as effective can be used. The binder should fulfill its function when the composite is compressed, and to keep the composite in a state of higher density before liquid release. Upon isolation, the binder should allow the composite to expand to essentially its caliber before compression. If the binder is in the form of a fiber, it is preferred that the fiber is as thin as possible.

 Moisture-sensitive binders are suitable in the form of powder, liquid, or fibers so that they can be activated using heat and / or small amounts of moisture. Binder systems can be adhesives, powders, or polyvinyl alcohol fibers that dissolve in liquids. Some specific examples of polyvinyl alcohols have easily reversible cross-linking, which allows you to change the adhesive properties in contact with the allocation, allowing the elastic structure to expand. Water-sensitive hot melt adhesives that have temporary initiators based on controlled hydrophilicity can also be used, or water-initiated polymers such as base sensitive acrylates can be used. Binders also include polyacrylamides, polyacrylic acid and its copolymers, starch binders, cellulose binders and protein based binders.

 Conjugated binder fibers that can be used in the practice of the present invention can be corrugated. One side of the conjugate fiber may have a water-initiated first component, such as polyethylene oxide, while the other side of the fiber may have an elastic fiber such as polyethylene terephthalate (PET) as the second component. Many polymers are destructible in ordinary plain water, such as tap water, which typically has a pH in the range of from about 6.5 to about 8.5, and can serve as the destructible water portion of the conjugate fiber. For the first component, polymers that are sensitive to changes in pH or become destructible as a result of changes in pH, can be selected that are soluble in the aqueous environment with a change in ion concentration and / or a change in temperature.

 Another mechanism that can be used to initiate the ability to decompose by water is ion sensitivity, where the term "ion" is given in its usual meaning as an atom or in a group of atoms that have acquired or lost one or more electrons and, therefore, have a negative or positive electric charge. Certain polymers contain acid-based components (R-COO-) that are held together by hydrogen bonds. When dry, these polymers remain solid. See, for example, US patent US 4419403 Varone (Varona), which is incorporated herein by reference in full.

Examples of polymers capable of degradation in aqueous mixtures or in eau de toilette are grafted polyvinyl alcohol copolymers available from Nippon Synthetic Chemical Co., Ltd., Osaka, Japan, designated Ecomaty AX2000, AX 10000 and AX-300G. Nippon polymers are soluble in cold water, but slightly slower in dissolution rate than Fuller polymers. Another first polymer component can be a block copolymer of a simple polyester and amide, designated Pebax MX 1074, supplied by Atochem (USA), located in Philadelphia, PA. Pebax MX 1074 polymer is prepared from monomers of epsilon-caprolactam (nylon 12) and tetramethylene glycol. These monomers are polymerized to produce a series of block copolymers of polyether and amide. Pebax polymer is insoluble in water, but capable of swelling in water and, therefore, can also be used in a higher volume of surrounding water. Fuller polymers can be matched to a second polymer component (core) with a softening or melting point at least about 10 ^° C higher, as is the case with polypropylene. Nippon or Atochem polymers can be matched with a second polymer component with a higher melting range, such as polypropylene or polybutylene terephthalate.

More specifically, the expandable adsorbent composite of the present invention may contain a pulp in an amount of from about 30 to about 80 wt.%, A superabsorbent in an amount of from about 10 to about 60 wt.% And a binder in an amount of from about 1 to about 10 wt. % Even more precisely, the expandable adsorbent composite may contain a pulp in an amount of from about 55 to about 75 wt.%, A superabsorbent in an amount of from about 20 to about 40 wt.% And a binder in an amount of from about 3 to about 8 wt.% . Such composites should have a density after compression and before wetting between about 0.1 g / cm ³ and 0.30 g / cm ³ and preferably about 0.20 g / cm ³ .

The attached figures show the generation of free volume as a function of saturation for three structures of materials that fall within the scope of the present invention. In the figures, the free volume is shown on the y-axis in units of cm ³ / g, and saturation is shown on the x-axis in units of g / g.

Example 1
Figure 1 is a graph of the generation of free volume when saturated in a composite containing FAV880 Stockhausen superabsorbent material in an amount of 20 wt.%, Weyerhauser chemically cross-linked cellulose pulp in an amount of 75 wt.% And Celbond T105 from Hoechst-Celanese in the amount of 5 wt.%. The density produced was 0.04 g / cm ³ and the sample consisted of 2 layers with a total weight of a spun base of 400 g. The sample was pressed for 1 minute at 80 ^{° C.} to a final density of 0.2 g / cm ³ . The graph is a free volume generation curve as a function of saturation. This diagram illustrates that the sample begins with a free volume capacity of 6 cm ³ / g and doubles this capacity to approximately 12 cm ³ / g when the sample reaches a saturation of 7 g / g.

Example 2
Figure 2 shows comparable data for a layered composite that uses a Dow AFA-130-53C superabsorbent material with a low absorption rate instead of the FAV880 Stockhausen superabsorbent from figure 1, the material was produced with a density of 0.055 g / cm ³ . All other materials and pressing conditions are identical to those in Example 1. As can be seen in FIG. 2, this composition generates a very similar free volume capacity as a function of increased saturation.

Example 3
Another embodiment of the invention is a composite with the same composition and pressing conditions as in Example 2, but the composite had a produced density of 0.11 g / cm ³ . At this initial density, the generation of free volume is only 10 cm ³ / g at a saturation of 7 g / g, but still falls within the scope of the present invention. The free volume generation properties of this composite are illustrated in FIG. 3.

Example 4
This embodiment of the invention is a composite with the same materials and pressing conditions as in Example 1, except that 55 wt.% Pulp and 40 wt.% Superabsorbent were used. This composite had a produced density of 0.05 g / cm ³ and a final density of 0.2 g / cm ³ . There is no figure representing free volume generation in this example.

Example 5
This embodiment of the invention is a composite with the same materials and pressing conditions as in Example 2, except that 55 wt.% Pulp and 40 wt.% Superabsorbent were used. This composite had a produced density of 0.053 g / cm ³ and a final density of 0.2 g / cm ³ . There is no figure representing free volume generation in this example.

Tables 1 and 2 show the data of the gravimetric absorption test (GAT) for five examples, as well as for the Hugges ^® diaper material used in industry. Material diaper Hugges ^® was taken from the holding material by reversibly changing the volume in front of pictures Hugges ^® destination zone diaper Him Ultratrim ^®, size 3. These diapers commercially available from Kimberly-Clark Corporation, Dallas, Texas. These samples had a density of about 0.02 g / cm ³ and contained industrially available superabsorbents, either FAV880 Stockhausen or 2035 Dow, in an amount of about 38 wt.%, And 1654 Coosa pulp obtained from Coosa Mills, Coosa, Alabama, in an amount about 62 wt.%.

Table 1 shows the results of a diaper Hugges ^® units of two samples and the results for each of Examples with two layers as shown. Hugges ^® diaper samples had a base weight of about 800 g, and two-layer examples had a base weight of about 400 g. The results in Table 2 show examples with a base weight of about 800 g.

As can be seen from table 1, all the materials of the examples absorbed 10 ml of precipitates significantly faster than the Hugges ^® diaper in the first and second secretions, although even half of the material was tested. The materials of the examples had about half the thickness (caliber) of the Hugges ^® diaper material. The materials of the examples used the available free volume more efficiently than commercially available material, as can be seen from the free volume data on the right side of Table 1. The examples maintained a high absorption rate even after reaching 70% saturation.

Table 2 shows similar data to Table 1, but here use basis weight and thickness of the starting materials for the examples that are approximately the same as the material of the diaper Hugges ^®. As can be seen from the data of table 2, the material of the examples completely absorb all three allocations with a volume of 10 ml much faster than the diaper material Hugges ^® . Free space utilization has also improved significantly.

The material of the examples, although it is somewhat similar in appearance to the Hugges ^® diaper in composition, provided a distinctly better performance. It is believed that this is due to the generation of free volume, which occurs when the materials of the examples expand upon contact with the liquid. This extension is guided not only normal extension of superabsorbent material as it occurs, e.g., in diaper Hugges ^®, but also the expansion of the fibrous matrix, which contains a superabsorbent. In the composites according to the present invention, therefore, the blocking of the superabsorbent gel and the consequent limitation of liquid absorption are eliminated or reduced. The composites of the present invention, therefore, can be used as reversibly volume-changing materials, as retarding materials with reversible volume changes are higher than in conventional Hugges ^® diapers, or can be used as retention materials without reversible volume changes due to their excellent absorbent properties.

 Although only a few typical embodiments of the present invention are described in detail above, those skilled in the art will readily appreciate that many modifications are possible in typical embodiments of the invention, without actually separating from the new lessons and advantages of the present invention. In accordance with this, it is understood that all such modifications are included in the scope of the present invention, which is defined in the following claims. It is understood that in the claims, the methods plus the functional claims cover the structures described herein as performing the specified function, and not only structural equivalents, but also equivalent structures. Thus, although the nail and bolt may not be structural equivalents in that the nail has a cylindrical surface in order to attach the wooden parts to each other, while the bolt has a spiral surface surrounded by bonded wooden parts, the nail and bolt may be equivalent structures. .

Claims (12)

1. A method of obtaining an expandable absorbent stabilized composite, comprising the following steps: mixing the pulp in an amount of from 28 to 90 wt.%, Superabsorbent material in an amount of from 8 to 70 wt.% And a binder fiber in an amount of from 1 to 20 wt. % to form a stabilized mesh, compressing the stabilized mesh between two surfaces at a temperature and for a time sufficient to obtain an expandable absorbent stabilized composite having a density between 0.1 and 0.3 g / cm ³ . 2. The method according to claim 1, characterized in that the mesh is heated at a temperature between 80 and 100 ^o C.  3. The method according to p. 1, characterized in that when carrying out the indicated mixing step, from 1 to 10 wt.% Binder fiber is used.  4. The method according to p. 1, characterized in that when carrying out the indicated mixing step, from 3 to 8 wt.% Binder fiber is used.  5. The method according to p. 1, characterized in that when carrying out the indicated mixing step, 30 to 90 wt.% Pulp and 10 to 70 wt.% Superabsorbent material are used.  6. The method according to p. 1, characterized in that said compression step is carried out using a press.  7. The method according to p. 1, characterized in that when carrying out the indicated mixing step, 30 to 80 wt.% Pulp, 10 to 60 wt.% Superabsorbent material and 1 to 10 wt.% Binder fiber are used.  8. The method according to p. 1, characterized in that when carrying out the indicated mixing step, from 55 to 75 wt.% Pulp, from 20 to 40 wt.% Superabsorbent material and from 3 to 8 wt.% Binder fiber are used. 9. The method according to claim 1, characterized in that as a result of the implementation of the indicated mixing step, a stabilized mesh having a density between 0.05 and 0.1 g / cm ³ before the specified compression step is obtained.  10. A expandable absorbent stabilized composite obtained in accordance with the method according to claim 1, characterized in that it has the ability to quickly expand when wet by an amount exceeding 80% of its thickness in an uncompressed state, and by an amount exceeding 90% of its thickness in an uncompressed state when a saturation state is reached. 11. A method of obtaining a expandable absorbent stabilized composite, comprising the following steps: mixing pulp in an amount of from 28 to 90 wt.%, Superabsorbent material in an amount of from 8 to 70 wt.% And a binder fiber in an amount of from 1 to 20 wt. % to form a stabilized mesh, compressing this stabilized mesh between two surfaces at a temperature and for a time sufficient to obtain an expandable absorbent stabilized composite having a density between at 0.1 and 0.3 g / cm ³ in which, as a result of the specified mixing step, a stabilized mesh is obtained having a density between 0.05 and 0.1 g / cm ³ before the specified compression step, and in which the specified mesh is heated at a temperature between 80 and 100 ^{° C.} during the compression step.  12. A expandable absorbent stabilized composite obtained in accordance with the method according to claim 11, characterized in that it is able to rapidly expand when wet by an amount exceeding 80% of its thickness in an uncompressed state, and by an amount exceeding 90% of its thickness in an uncompressed state when a saturation state is reached.

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