RU2242250C2 - Adsorbents designated for applying in treatment of complex liquids - Google Patents

Abstract

FIELD: adsorbents.

SUBSTANCE: invention relates to applying absorbing particles in absorbing structures and in single absorbing articles. Absorbing particles provides effective treatment of complex liquids. Improved effectiveness of particles in absorbing material allows expanding sphere of their applying in absorbing structures and in single absorbing articles.

EFFECT: valuable properties of adsorbents.

31 cl, 3 dwg, 13 tbl, 7 ex

Description

State of the art

The present invention relates to the use of absorbent particles in absorbent structures and to disposable absorbent articles. In particular, the present invention relates to absorbent particles capable of efficiently treating complex liquids.

The use of absorbent particles in disposable absorbent articles is known. The use of such absorbent particles is usually limited to the absorption of odors in disposable absorbent personal care products, such as hygiene products for women and the like. However, however, the wider use of such absorbent particles in absorbent structures and disposable absorbent articles has, to date, to some extent been limited due to the limited effectiveness of absorbent particles in the treatment of complex liquids. Thus, it would be desirable to improve the efficiency of absorbent particles in the treatment of complex liquids, which could potentially lead to an increase in the use of such absorbent particles in absorbent structures and in disposable absorbent articles.

SUMMARY OF THE INVENTION

The present invention is directed to solving the difficulties and problems associated with products of the prior art, and therefore intensive research has been conducted aimed at the development of absorbent particles that are effective in the treatment of complex liquids. In carrying out such studies, the inventors have found that some absorbent materials are effective in treating complex liquids. The effectiveness of these absorbent materials can be improved by appropriately choosing an appropriate pore size distribution. As a result of improved efficiency, absorbent materials in accordance with the present invention expand the scope of use of absorbent particles in absorbent structures and disposable absorbent articles.

In one embodiment of the present invention, absorbent articles include a retention aid and particles of at least one absorbent material. In a retention aid, from about 20 to about 50 percent of the absorbent particles have a pore volume composed of pores larger than about 100 microns in order to absorb complex liquids and distribute complex liquids. From about 80 to about 50 percent of the pore volume of the absorbent particles, there are pores with a size of less than about 100 microns, which are designed to hold complex fluids. The retention aid contains from about 10 to about 100 percent absorbent particles of the total weight of the retention aid and absorbent particles.

In another embodiment of the present invention, the absorbent article includes a retention aid and particles of at least one absorbent material. In a retention aid, from about 10 to about 100 percent of the absorbent particles have a permeability of at least about 1000 K. Absorbent particles are present in the retention aid in an amount of from about 10 to about 100 percent of the total weight of the retention aid and the absorbent particles.

In yet another embodiment of the present invention, the absorbent article includes a retention aid and particles of at least one absorbent material. Absorbent particles in the retention aid have a retention ability of the complex fluid of at least 2 g / g. Absorbent particles are present in the retention agent in an amount of from about 10 to about 100 percent of the total weight of the retention agent and absorbent particles.

In yet another embodiment of the present invention, the absorbent article includes a retention aid and particles of at least one absorbent material. Absorbent particles in the retention aid have a minimum average particle size of at least about 200 microns with a standard deviation of at least about 25 percent of the average particle size. Absorbent particles are present in the retention agent in an amount of from about 10 to about 100 percent of the total weight of the retention agent and absorbent particles.

In yet another embodiment of the present invention, the absorbent article includes retention means and particles of at least one absorbent material. Absorbent particles of the retention agent have a multimodal particle size distribution and are present in the retention agent in an amount of from about 10 to about 100 percent of the total weight of the retention agent and absorbent particles.

Brief Description of the Drawings

These and other properties, aspects and advantages of the present invention will become better understood when considering the following description of the accompanying claims of the accompanying drawings, in which:

Figure 1 depicts a device used to measure the pore size distribution of an absorbent material using a capillary pressure method;

Figure 2 depicts a device used to determine the value of the permeability of the gel layer (ASG) of the absorbent material;

Figure 3 depicts a top view of the piston head of the device depicted in Figure 2.

Description of the invention

Absorbent materials in accordance with the present invention include absorbent particles and absorbent particles that are treated with a surface modifying agent. The terms "particle", "particles", "particulate", "particulate", etc. mean that the absorbent material is generally made in the form of separate parts. Particles can be granules, dust, powders or spheres. In this case, the particles can have any desired shape, such as, for example, cubic, rod-shaped, polygonal, spherical or hemispherical, rounded or semi-rounded, pointed, irregular, and other shapes having a large ratio of maximum size / minimum size, such as needles, flakes and fibers, which are also contemplated for use in the present invention. The use of the term “particle” or “particulate” may also describe agglomerates containing more than one particle, particulate or the like, which may also contain more than one type of absorbent.

As used herein, the term "nonwoven" refers to a material that has a structure consisting of individual fibers or threads that are mutually interwoven, but without specific repetition.

As used herein, the terms “high-velocity air jet ejection” or “fibers obtained by high-velocity air jet ejection” refer to fibers that are formed by extruding molten thermoplastic material in the form of threads from a variety of thin, usually round capillaries or dies, followed by a sharp reduction in the diameter of the extruded threads.

The term “co-molded” as used herein is intended to describe a mixture of fibers obtained by the aerodynamic method from a melt and cellulose fibers, which is formed using air forming a polymer material obtained by the aerodynamic method from a melt, while blowing cellulose fibers suspended in air into the stream fibers obtained by the aerodynamic method from the melt. The meltblown fibers containing wood fibers are collected on a molding tape on the surface of which a permeable material, such as fabric made by ejection by a high-speed stream of air, can be arranged.

As used herein, “meltblown fibers” refers to fibers formed by extruding molten thermoplastic material through a plurality of thin, typically steep capillary dies in the form of molten filaments or fibers, into a stream of high-speed, usually heated gas (eg, air) that draws fibers from molten thermoplastic material so that their diameter is reduced. After that, the fibers obtained by the aerodynamic method from the melt are transferred by a high-speed gas flow and are deposited on the collecting surface so that thin-sheet material is formed from randomly distributed fibers obtained by the aerodynamic method from the melt.

As used herein, the term “complex fluid” describes a fluid that is typically characterized as a viscoelastic fluid containing many components having uneven physical and / or chemical properties. These uneven properties of many components are a problem for increasing the efficiency of the absorbent material in the treatment of complex liquids. Unlike complex fluids, fluids of a simple composition, such as, for example, urine, physiological saline, water, and the like, are usually characterized as liquids with a relatively low viscosity, and usually contain one or more components having uniform physical and / or chemical properties. As a result of the uniform properties, one or more components of liquids of simple composition have essentially the same behavior when absorbed or surface absorbed.

Although the complex fluid is generally characterized here as including certain components having heterogeneous properties, each specific component of the complex fluid generally has uniform properties. For example, consider a hypothetical complex fluid that has three specific components: red blood cells, blood protein molecules, and water molecules. In the study, a person skilled in the art will be able to fairly easily distinguish each of these three specific components by their generally uniform properties. In addition, when examining a specific component, such as a red blood cell component, one of ordinary skill in the art can easily determine the generally uniform properties of red blood cells.

The term "surface", also used in the plural, usually refers here to the outer or uppermost boundary of an object, material, structure, particle, or the like.

As used herein, the phrase “absorbent article” refers to devices that absorb and contain body fluids, and in particular, devices that are located directly next to the skin to absorb and contain various fluids released from the body. The term “disposable” is used herein to describe absorbent articles that are not intended to be washed or otherwise reconstituted or reused by the absorbent article after a single use. Examples of such disposable absorbent articles include, but are not limited to: patient care products, including surgical sheets, gowns, sterile dressings; absorbent personal care products such as feminine hygiene products (e.g., sanitary napkins, panty liners, etc.), diapers, training pants, products for patients with incontinence, and the like; as well as handkerchiefs.

Disposable absorbent articles, such as, for example, many types of absorbent personal care products, typically contain a liquid permeable top sheet, a liquid permeable back sheet attached to the top sheet, and an absorbent core located between the top sheet and the back sheet. Disposable absorbent articles and their components, including a top sheet, a back sheet, an absorbent inner part and any individual of these components, comprise a surface facing the body and a surface facing clothing. As used herein, the term “body-facing surface” means the surface of an article or component that is designed to be positioned in close proximity to the wearer's body when worn, while “clothing-facing surface” is the opposite side and is designed so that when worn, it is rotated or located in the immediate vicinity of the user's underwear when a disposable absorbent article is worn on the body.

Although a wide variety of absorbent materials is known, the present invention relates, in one aspect, to the correct selection of absorbent materials suitable for use in the treatment of complex fluids, such as, for example, blood, menstrual flow, feces and urine, nasal secretions, and the like. Absorbent materials suitable for use with complex liquids are preferably substantially wettable or hydrophilic with respect to complex liquids, thereby allowing complex liquids to be distributed over the surface of the particles of absorbent material. In addition, it is desirable that the absorbent material in accordance with the present invention, was laid out in the form of particles, and would be essentially insoluble in complex liquids. It is further desirable that the absorbent materials in accordance with the present invention are substantially inert and, when absorbed, substantially not soften or substantially not swell. Such suitable absorbent materials preferably have a large surface area with respect to their mass, which is determined using a method such as gas absorption, absorption of acetyltrimethylammonium bromide or mercury porosimetry.

Absorbent materials suitable for use in accordance with the present invention include, but are not limited to, organic materials, inorganic materials, and mixtures thereof. Suitable inorganic materials include, for example, activated carbon, silicates, metal oxides, zeolites, carbonates, phosphates, borates, aerogels and mixtures thereof. Suitable organic materials include, for example, cellulosic materials, starches, chitins, alginates, synthetic polymers and mixtures thereof.

The absorbent material may additionally be treated with a surfactant or other surface modifying agent before being placed in any retention aid. A large number of materials are used for this purpose, for example, sulfonated alkyl and aryl compounds, ethoxylated alcohols and amines, polyamides and their derivatives, polysaccharides and their derivatives, polyethylene glycols and their derivatives, betaines and other zwitterionic compounds, and silyl compounds. Appropriate methods of use are well known to those skilled in the art.

When used in feminine hygiene products, the absorbent materials in accordance with the present invention should have a certain preferred pore size distribution. In a layer of absorbent particles, the pores represent the space between the particles (spaces), as well as the structure of the internal pores of the particles themselves. The gaps are connected so that they form what can be considered as a network of gaps. When a fluid flows into or through a layer of particles, this fluid usually passes through these gaps. These gaps through which the fluid passes can also be considered as intermediate pores.

Since the walls of the intermediate pores are the surfaces of the particles themselves, the shape and size of the intermediate pores are usually determined by the particles themselves. When the particle size changes so that their average sizes or the distribution of their sizes change, the shape and size of the intermediate pores changes. Intermediate pores play a significant role in the rate of absorption and retention of complex liquids by absorbent particles.

Suitable absorbent materials preferably have an acceptable rate of absorption of complex liquids. This acceptable absorption rate can be obtained using an inhomogeneous distribution of pore sizes. As described above, the combination of particle sizes allows you to get the corresponding uneven distribution of pore sizes. The pore size distribution can be measured using capillary pressure methods, mercury porosimetry and, indirectly, using a permeability test, all of these methods are described in this description. The inventors have found that pore sizes range from about 1000 to about 0.2 microns, with pore sizes from about 1000 to about 100 microns that are mostly preferred for the rapid absorption and distribution of complex liquids, and pore sizes from about 100 to about 0 2 microns are preferably used to separate and retain the components of the complex fluid.

Absorbent particles make it possible to retain liquid in the intermediate pores or spaces between the particles, as well as in the internal pores of the individual particles. It is desirable that the pores of the individual particles are accessible from the surface of the particle so that they can absorb liquid. Liquid can pass into the volume of internal pores of individual particles due to capillary forces. The addition of internal pores allows the liquid or part of the complex liquid to be retained by capillary forces within the internal pores. This creates a feeling of dryness in relation to the body and reduces the amount of free fluid in the layer of absorbent particles and, therefore, re-moisturizing. Suitable absorbent particles have a range of internal pore sizes of from about 100 to about 0.2 microns so that they can absorb components with different sizes of the complex liquid and thus minimize re-wetting with the liquid, as measured by the re-wetting and centrifuge retention test methods, which are described in this description.

If the particles have too many small pores, then the liquid component of the complex fluid will be removed too quickly, while the remainder of the complex fluid, mainly the cells in case of menstrual flow, will not be distributed. The inventors have determined that it is desirable that the pore volume with a size of less than 1 micron should be less than 2 percent of the total pore volume.

Based on the foregoing, absorbent materials suitable for use in the present invention must necessarily have at least the following parameters: they must be wettable, stable against liquid, must have a suitable distribution of the size of the intermediate pores to obtain an acceptable absorption rate and an acceptable size distribution of internal pores for the required degree of retention.

In various embodiments of the present invention, other specific absorbent material parameters may be preferred. For example, when the complex fluid is menstrual flow, and the absorbent material is used in feminine hygiene products, it is desirable that the absorbent materials in accordance with the present invention have particle sizes from about 1000 to about 100; and more preferably, from about 850 to about 150 microns. The inventors have determined that particles of absorbent material with a size exceeding approximately 1000 microns are typically sensed by the user of a retention aid containing absorbent materials in accordance with the present invention, while particles of absorbent material with sizes less than 100 microns have been found to be difficult to hold in the amount of retention aid, which can cause complex fluids to pass through absorbent materials. It is understood that particles of absorbent material falling within the range indicated herein may contain porous particles or may be agglomerated particles containing a large number of smaller particles from one or more absorbent materials.

Another preferred specific parameter is the ability, which is measured as the mass in grams of complex fluid held by the mass in grams of absorbent in the methods for testing the ability to hold the complex fluid. For example, when the complex fluid is menstrual flow and the absorbent material is placed in a feminine care product, it is desirable that the retention capacity of the complex fluid for the absorbent is from about 1 to about 15; alternatively, from about 2 to about 8; and finally, alternatively, from about 2 to about 6 g / g. It is believed that absorbent materials having less retention capacity than 2 g / g will require the use of such large amounts of absorbent material that users may find that a feminine hygiene product is excessively heavy. Evaluation of the retention ability of the complex fluid can be done by summing the pore volume with a size from about 100 to about 0.2 microns in diameter, which is determined, for example, using capillary pressure methods or mercury porosimetry. The ability to retain complex fluid is limited by the strength of the material of the pore walls.

As indicated above, a mixture of particles with different sizes is preferable to improve fluid absorption and retention. Sufficient interstitial pores between the particles are necessary so that menstrual flow can quickly enter the layer of absorbent particles and be distributed between the clocks. This property can be controlled by the particle size distribution of the absorbent material. In general, it is preferred that there is a wide particle size distribution. The term wide particle size distribution is used here to describe a distribution having a standard deviation of more than 25 percent of the mean.

If it is desired that the liquid passes relatively quickly into and through the particle bed, it is preferable to minimize variations in the size of the intermediate pores and the shape along the length of the intermediate pore. Consequently, a relatively wide particle size distribution could form intermediate pores that would allow fluid to pass in and through the particle bed relatively quickly. If the variations in particle size and packing become too large, so that some of the particles actually move in the intermediate pores themselves, the movement of the liquid inside and through the layer will not be relatively fast and, conversely, it may turn out to be relatively slow.

The inventors also found that the combination of pore sizes is effective in absorbing complex liquids. A bimodal or multimodal particle size distribution is particularly preferred to obtain a combination of pore sizes, which is preferred to improve the absorption and retention of the complex fluid. One way to obtain this preferred pore size distribution is to combine absorbent particles with different sizes.

Since the properties of interest in absorbing the liquid are the pore size and distribution, another way to obtain a pore size distribution suitable for quickly absorbing a complex fluid is to use relatively large spherical particles. For example, relatively large spherical particles are usually packed relatively freely. This relatively loose packing of relatively large spherical particles can lead to the formation of relatively large intermediate pores, which allow the complex fluid to quickly pass through the layer of relatively large spherical particles. The test method for the permeability of the gel layer described here, allows you to measure the packing density of the particles in the layer. The inventors believe that permeabilities greater than at least 1000 K for a layer of relatively large spherical particles indicate relatively poor packaging and therefore allow a relatively rapid absorption of the complex fluid to be predicted.

It should be noted that the present invention is not limited to the use of only one absorbent material described herein, but may also include mixtures of two or more absorbent materials. As indicated above, the absorbent material is used in the form of particles, therefore, the use of the phrase "absorbent material" in this description and the attached claims includes a single particle of absorbent material or agglomerate from more than one particle of absorbent material.

Absorbent materials in accordance with the present invention may accordingly be contained in a suitable retention aid. Any means capable of holding the described absorbent material so that this means further allows it to be placed in a disposable absorbent article is suitable for use in the present invention. Specialists in the art know a large number of such retention aids. For example, the retention aid may comprise fiber material, such as cellulosic fibers, air-laid or wet-laid materials, melt-synthesized polymer fibers, synthetic polymer fibers, ejected by high-speed air flow, co-molded base containing cellulosic fibers and fibers formed from a synthetic polymer material, aeroformed using heat melting material from synthetic polymeric materials, foamed materials with open cells, etc.

Alternatively, the retention means may comprise two layers of material that are joined together to form at least one pocket or compartment containing absorbent material. In this case, at least one of the layers of this material must be liquid permeable. The second layer of material may be liquid permeable or liquid impermeable. The layers of material may be woven materials or non-woven materials such as fabrics, foamed materials with closed or open cells, perforated films, elastic materials, or may be fiber webs of material. When the retention aid contains layers of material, this material should have a sufficiently small or sufficiently sinuous pore structure so that it can contain a larger amount of absorbent material. The retention means may also comprise a laminate of two layers of material between which absorbent material is placed and held.

In addition, the retention means may comprise a support structure, such as a fiber or polymer film, to which the absorbent material is adhered. The absorbent material may be adhered on one or both sides of the retaining structure, which may be liquid permeable or liquid impermeable.

Absorbent material is placed in a retention aid in an amount of from about 10 to about 100; alternatively, from about 20 to about 100; alternatively, from about 30 to about 100; alternatively, from about 40 to about 100; alternatively, from about 50 to about 100; alternatively, from about 60 to about 100; alternatively, from about 70 to about 100; alternatively, from about to about 100; and finally, alternatively, from about 90 to about 100 weight percent of the total weight of the retention aid and absorbent material.

In one specific embodiment of the present invention, the retention means comprises two layers of material that are connected to form a pocket adapted to contain absorbent material. These two layers are suitably formed from any material that may contain absorbent material, including woven and non-woven materials, such as fibers laid in the air or laid in the wet state, fibers obtained by aerodynamic melt, fibers obtained by ejection by a high-speed stream of air co-formed fibers, binder fibers (such as bicomponent fibers) and the like, and are connected to form a pocket by heat melt, an ultrasound is connected glue, adhesives (such as water-soluble or water-sensitive adhesives, latex based adhesives, hot melt adhesives, or solvent based adhesives) and the like. Obviously, a wide variety of materials can be used to form the two layers and to join the two layers together to form a pocket. Absorbent material is present in said pocket in an amount of from about 10 to about 100; alternatively, about 20 to about 100; alternatively, from about 30 to about 100; alternatively, from about 40 to about 100; alternatively, from about 50 to about 100; alternatively, from about 60 to about 100; alternatively, from about 70 to about 100 weight percent; alternatively, from about 80 to about 100 weight percent; and finally, alternatively, from about 90 to about 100 weight percent of the total mass of absorbent material contained in the pocket and the mass of these two layers forming the pocket. In addition to the absorbent material, the pocket may contain fiber material or other fiber material that does not have an unacceptable effect on the absorbent properties of the absorbent material.

In another embodiment, the containment means comprises a fiber backing. Absorbent material is mixed with base fibers. Absorbent material is present in a mixture of fibers and absorbent material in an amount of from about 20 to about 95; alternatively, from about 30 to about 85 weight percent; and finally, alternatively, from about 50 to about 75 weight percent of the total weight of the mixture.

Any fibers that are capable of containing an absorbent material and form a composite material in combination with an absorbent material are considered suitable for use in accordance with the present invention. It is often preferred that these fibers are hydrophilic. In the present description, fibers are considered as “hydrophilic” when they have a contact angle of water in the air of less than 90 degrees. For the purposes of the present description, the measurement of the contact angle is determined as described in Good and Stromberg, "Surface and Colloid Science" Vol. 11 (Plenum Press, 1979).

Fibers suitable for use in accordance with the present invention include cellulosic fibers such as wood pulp fluff, cotton, cotton fluff, viscose, rayon, cellulose acetate and the like, as well as synthetic polymer fibers. Synthetic polymer fibers can be formed from polymer materials that have hydrophilic properties, or can be formed from polymer materials that have hydrophobic properties (the edge angle of water in the air is greater than 90 degrees) so that these fibers are then processed to give them at least on the outer surface, hydrophilic properties.

For example, hydrophilic fibers can be formed from polymers that exhibit hydrophilic properties, such as a nylon block copolymer, for example nylon-6, and a polyamine oxide diamine. Such block copolymers are commercially available from Allied-Signal Inc. (Allied-Signal Inc.) under the trade name HYDROFIL. Alternatively, the fibers can be formed from polymers that exhibit hydrophobicity properties, such as polyolefins or polyesters, whose surface has been modified to provide a generally stable hydrophilic surface. Such surface-modified polyethylene is commercially available from the Dow Chemical Company under the trade name ASPUN Wettable Polyethylene.

When hydrophilic fibers are formed by hydrophilic surface treatment, typically a hydrophobic polymer, it is considered preferable to typically use a stable surface treatment to obtain the desired properties.

Synthetic polymer fibers suitable for use in accordance with the present invention can be formed using a melt extrusion process in which fibers of a polymer material are extruded and thinned to produce fibers having a desired diameter. Alternatively, fibers can be formed using a spinning process. Any fiber manufacturing method known to those skilled in the art is considered suitable for use in the present invention.

Fibers suitable for use in the present invention generally have a length of at least about 1 millimeter. These fibers can have a maximum length approaching infinity. That is, the fibers can be substantially continuous, such as fibers formed in the process of forming the fibers by the aerodynamic method from the melt under certain conditions known to those skilled in the art.

References to mixtures of fibers and absorbent material are intended to indicate a situation in which the absorbent material is in direct contact with the fibers or, in essence, there are no obstacles to migrating it so that it comes into contact with the fibers. Thus, for example, in a multilayer absorbent interior in which the first layer contains an air-laid mixture of wood pulp fluff and absorbent material, and the second layer contains only air-laid fluff, only the first layer is considered as a mixture of fibers and absorbent material, provided however, that essentially dry migration of the absorbent material between the two layers will be prevented. Ways to prevent such migration are known and include separating the layers using a sheet of wrapping cloth, a layer of high density fibers, or using similar means of preventing substantial dry migration of absorbent material between the two layers. A mixture of absorbent material and fibers may be relatively uniform or relatively non-uniform. In the case of a non-uniform mixture, the absorbent material may be arranged with a certain gradient or may be placed in layers with fibers.

When the retention aid contains a mixture of fibers and absorbent material, a mixture of fibers and absorbent material can be formed in various ways. For example, this mixture can be formed by laying with air or laying in a wet state of the fibers and absorbent material, in accordance with processes known in the art, to form layers of the mixture. Laying with air a mixture of fibers and absorbent material is intended to cover both situations in which pre-prepared fibers are laid with air with absorbent material, as well as in situations in which the absorbent material is mixed with the fibers during fiber formation, for example, using a melt aerodynamic method.

Absorbent materials in accordance with the present invention are particularly suitable for use in disposable absorbent articles. Typically, absorbent materials can be used in the same way as conventional odor-absorbing absorbent materials that are used, for example, in layered structures, in an absorbent interior with a relatively high density (i.e., a densely packed absorbent interior, calendared absorbent interior a densified absorbent core, etc.), or in a relatively low density absorbent core (i.e., a non-compact absorbent core, for example, absorbent interior formed by air laying). However, absorbent materials in accordance with the present invention have some advantages over conventional absorbent materials used in the absorption of odors. In general, compared with conventional absorbent materials, absorbent materials in accordance with the present invention exhibit improved efficiency in the treatment of complex liquids. In particular, absorbent materials in accordance with the present invention demonstrate improved efficiency in the treatment of menstrual flow. As a result of this improved efficiency, the absorbent materials of the present invention provide flexibility for product developers who can either supplement the absorbent materials typically found in disposable absorbent products by adding a sufficient amount of absorbent material in accordance with the present invention, or replace some absorbent materials normally contained in disposable absorbent articles, with sufficient amounts of absorbent material in accordance with Astoyan invention.

Test methods

Test Method for Absorption Rate and Re-wetting

The methodology used here for testing the rate of absorption and re-wetting allows the measurement of at least two of the following material characteristics:

1. Absorption rate - the amount of time in seconds that is necessary for a known amount of material to absorb multiple portions of a known amount of liquid; and

2. Re-wetting - the amount of fluid in grams that is released from the material when a sheet of blotting paper is placed on top of the material and a known pressure is applied for a predetermined period of time.

Tests in accordance with this method consist in using a stopwatch to determine the time in seconds required for 20 ml of material to absorb multiple portions (1 or 2 ml) of the liquid. The Harvard Syringe Pump is programmed to dispense 2 ml of liquid per 20 ml of absorbent material while starting the stopwatch. The stopwatch is stopped when 2 ml of liquid is absorbed into the material. Then a second supply of 2 ml of liquid is made and time is detected. After the second portion, a third portion follows, this time amounting to 1 ml, the absorption time of which is also timed. As a result, 5 ml of liquid is administered in three portions. After absorption of the third portion, approximately 60 seconds are expected, and then a pre-weighed sheet of blotting paper is placed in 20 ml of material and a pressure of 0.5 psi (0.035 kg / cm ² ) is applied for 60 seconds. After 60 seconds, the blotter paper is reweighed, and the mass of liquid in grams that has been absorbed by the blotter paper is considered the rewet value. The test is usually carried out under the conditions of the standard TAPPI (Technical Association of the US paper industry).

Equipment and materials

- Harvard Programmable Injection Pump, Model Number 44, commercially available from Harvard Apparatus, South Natick, MA 01760 USA.

- The fluid in this case, only as an example, and not for limitation, is artificial menstrual flow (simulating fluid), which are described in US patent No. 5883231, which was issued March 16, 1999 to the authors Achter and others (Achter et al .), the description of which is given here by reference in such a way that this description is consistent (i.e. does not contradict) with this description. The simulating fluid described and claimed in US patent No. 5883231, commercially available from Cocalico Biologicals Inc. 449 Stevens Rd., P.O. Box 265, Reamstown, PA 17567 USA.

- Disposable plastic weighing ditches, commercially available from NCL of Wisconsin, Inc., Bimamwood, WI 54414 USA, product number W-D 80055.

- A disposable syringe with a capacity of 60 cm ³ , commercially available from Becton Dickinson, Franklin Lakes, NJ 07417 USA; Tygon tubing, size 16 with an inner diameter of 0.12 "(3.05 mm), part number 6409-16, commercially available from Cole-Farmer Instrument Company, Chicago, IL 60648 USA; and a hose with an outer diameter of 1 / 8 "(3.2 mm), part number R-3603, which is also commercially available from Cole-Farmer Instrument Company.

- 5.5 cm blotter paper, which is commercially available from VWR Scientific Products, 1145 Conwell Ave., Willard, OH 44890 USA, catalog number 28310-015.

- A 100 ml Pyrex laboratory beaker filled with any suitable substance to a mass of 717.5 g to obtain a load of 0.5 psi (0.035 kg / cm ² ).

- Scales with a division value of 0.001 g (note: must comply with the NIST standard (National Institute of Standards and Technology) and must be re-certified frequently often to ensure accuracy).

- A stopwatch with a division value of 0.1 s (note: the stopwatch must comply with the NIST standard).

- Graduated cylinder with a mark of 20 ml.

- A transparent acrylic plate (large enough to fit on top of a disposable plastic weighed cuvette) with a hole drilled approximately in its center to insert the Tygon tube.

Sample preparation

The simulating liquid is removed from the refrigerator, mounted on a rotator and then gently rotated for about 30 minutes to thoroughly mix the contents and bring the simulating liquid to room temperature.

The graduated cylinder is placed on the scale for weight calibration. 20 ml of material is introduced into a graduated cylinder. The graduated cylinder is removed from the balance. The bottom of the graduated cylinder is gently hit on the surface of the laboratory bench or similar hard surface about 10 times to cause precipitation. Make a visual check to make sure that 20 ml of material is in the graduated cylinder. 20 ml of material is poured into a weighing cuvette and the material is carefully balanced.

Harvard injection pump is set to programming mode. The feed rate is set at 12 ml / min and the target volume is set at 2 ml. The diameter is set to the correct size of the syringe. A Harvard injection pump is filled with approximately 60 ml of simulated fluid.

The test procedure contains the following steps:

1. One end of a Tygon tube is inserted through an opening in an acrylic plate.

2. An acrylic plate is placed on top of a weighing cuvette containing 20 ml of absorbent material. The Tygon tube should be placed approximately above the center of the material.

3. At the same time, turn on the stopwatch and start dispensing the first 2 ml of the simulated fluid.

4. The stopwatch is stopped when the simulated liquid is absorbed by the material. The stopwatch is recorded in seconds as "Portion 1". In the case when the simulation fluid is not absorbed by the test material (i.e., the simulation fluid remains on the surface of the material) for five minutes, the test is stopped and 300+ seconds are recorded.

5. At the same time, turn on the stopwatch and start feeding 2 ml of a portion of the simulating liquid.

6. Stop the stopwatch when the simulated liquid is absorbed by the material. The stopwatch is recorded in seconds as "Portion 2". If the simulation fluid is not absorbed by the test material (i.e. the simulation fluid remains on the surface of the material) for five minutes, the test is stopped and 300+ seconds are recorded.

7. At the same time, start the stopwatch and simulate fluid. In this case, however, the Harvard injection pump is stopped after supplying 1 ml of simulating fluid.

8. Stop the stopwatch when 1 ml of the simulated liquid is absorbed by the material. The stopwatch is recorded in seconds as "Serving 3". Once again, if the simulation fluid is not absorbed by the test material (i.e. the simulation fluid remains on top of the material) for five minutes, the test is stopped and 300+ seconds are recorded.

9. Expect 60 seconds after the absorption of the third portion of the material.

10. Two pieces of blotting paper are weighed, and this mass is recorded as “dry PB” (BP).

11. At the end of the 60 seconds noted in step 9, carefully put blotting paper on the material and then carefully place the load, creating a pressure of 0.5 psi (0.035 kg / cm ² ), on blotting paper and turn on the stopwatch.

12. After 60 seconds, the load is removed and re-weighed blotting paper. This mass of blotting paper is recorded as “wet PB”.

Steps 3-12 described above are repeated until the simulating liquid is no longer absorbed by the material (that is, when the simulating liquid remains on top of the material and is not absorbed for five minutes).

The results of a portion of the test technique related to re-wetting are recorded in grams and calculated by the following formula:

(Wet PB) - (Dry PB) = Re-wetting

Method for determining retention ability

The method used here to determine retention ability allows you to measure the amount of test fluid that a sample of material holds under the influence of centrifugal force. The amount of fluid retained is calculated in grams per gram of retention. These tests are usually performed under the TAPPI standard. When the test fluid is a complex fluid, such as, for example, blood, menstrual flow, artificial menstrual flow (mimicking fluid), fecal discharge, nasal discharge, etc., the retention capacity of the material is sometimes referred to as the retention capacity of the complex fluid (WSS).

Typically, tests in accordance with this method are performed by placing a sample of material weighing 0.5 g in a modified cylinder, exposing the sample to the desired liquid for 60 minutes, and then placing the cylinders in a centrifuge to remove excess liquid. Results are calculated to obtain the number of grams of retained fluid per gram of sample material.

Equipment and materials

- Artificial fluid menstrual flow (simulating fluid) described in US Pat. No. 5,883,231 issued March 16, 1999 to Ahter et al. The simulating fluid described and claimed in US Pat. No. 5,883,231 is commercially available from Cocalico Biologicals Inc. 449 Stevens Rd., P.O. Box 265, Reamstown, PA 17567 USA.

- Sorvall RT 6000D Centrifuge, commercially available from Global Medical Instrumentation, Inc., 3874 Bridgewater Dr., St. Paul, MN 55123 USA.

- Four 200 ml centrifuge cups with screw caps, commercially available from International Equipment Co., 300 Second Ave., Needham Heights, MA 02494 USA.

- Scales with a division value of 0.001 g (note: must comply with the NIST standard and must be certified often enough to ensure accuracy).

- Four 50 ml Pyrex laboratory beakers.

- A laboratory timer with a maximum time of 60 minutes, a division time of one second, commercially available from VWR Scientific Products, 1145 Conwell Ave., Willard, OH 44890 USA.

- Four Lexan brand modified cylinders with a height of 9 cm, an internal diameter of 3.1 cm, an external diameter of 4.8 cm, and a sieve containing 300 holes per square inch (46.5 holes per square centimeter) is installed at the bottom.

- US standard No. 30 and 50 sieves (hole sizes 0.59 mm and 0.297 mm), 8 inches (20.3 cm) in diameter, 2 inches (5.1 cm) high, which are commercially available from VWR Scientific Products, 1145 Conwell Ave., Willard, OH 44890 USA, catalog numbers 57334-456 and 57334-464, respectively.

- A stainless steel sieve, 4 holes per inch (1.57 holes per centimeter), which has enough open space for the simulated liquid to drain.

Sample preparation

Prepare a sample of material using sieves 30 and 50 according to the US standard for fractionation of the sample in sizes from 300 to 600 microns. The fractionated material sample is stored in a hermetically sealed substantially airtight container for use after preparation of the sample or material samples. The modified cylinder is placed on the scale and the weight is calibrated. Place 0.5 ± 0.005 g of the fractionated sample in one of the modified cylinders. Record this mass as Sample Mass. A modified cylinder containing a sample of material is weighed, and this mass is recorded as the Mass of the Dry Cylinder. Additional material samples are placed in the remaining three modified cylinders in accordance with the above steps.

The simulating liquid is removed from the refrigerator, placed on a rotator and then gently rotated for about 30 minutes to thoroughly mix the contents and bring the temperature of the simulating liquid to room temperature.

The test procedure contains the following steps:

1. Approximately 10 ml of the simulated liquid is placed in a 50 ml Pyrex beaker.

2. A modified cylinder containing a sample of material is placed in a 50 ml Pyrex beaker.

3. Approximately 15 ml of the simulated fluid is poured into the modified cylinder. This ensures that the sample of material will have access to the simulation fluid both from above and from below.

4. Repeat steps 1-3, as necessary, for all additional material samples.

5. After step 4 is completed, the timer is set to 60 minutes and turn it on.

6. After 60 minutes, the modified cylinders are removed from the Pyrex beaker and placed on a stainless steel sieve for 60 seconds.

7. After 60 seconds, the modified cylinders are removed from the stainless steel sieve and placed in 200 ml centrifuge glasses.

8. Glasses for a centrifuge are placed in a centrifuge for 3 minutes at a rotation speed of 1200 rpm.

9. After 3 minutes, the modified cylinders are removed from the centrifuge cups, and the modified cylinders containing material samples are weighed. This mass is recorded as the Mass of Wet Cylinders.

The complex fluid retention capacity (“SCLC”) of each absorbent material sample is then calculated in accordance with the following formula:

In all of the following examples, retention values are the average of two samples (i.e., n = 2).

Capillary pressure test procedure

Capillary pressure tests (ICDs) (CTTs) are tests that measure the ability of an absorbent material to absorb liquid (0.9 wt.% Solution of sodium chloride in distilled water) under the influence of a load or holding force under a negative pressure gradient.

An apparatus and method for determining ICD values will be described with reference to FIG. 1. The drawing shows a perspective view of the device in position during the test.

The drawing shows a laboratory bench (31), which is calibrated in centimeters and which has an adjustable ring (32), designed to raise and lower the ring (33) of the holder. The holder ring (33) holds the funnel (34), which has a diameter of 6 centimeters. A porous glass plate (35) is placed in the funnel (34), which has a nominal maximum pore diameter of about 40 to about 60 micrometers. The bottom of the funnel (34) is connected to the first flexible plastic tube (36), which is connected at the other end to a rigid plastic tube (37), which is held in place by a clamp (38). The other end of the rigid plastic tube (37) is connected to the second flexible plastic tube (39), which is connected to the other end with a reservoir (40) for a liquid in communication with the atmosphere, which is mounted on the balance (41), which are connected to the recording device (42) ) used to record the loss of mass of fluid from the fluid reservoir (40) in fluid communication with the atmosphere as the fluid is absorbed by the sample being evaluated.

The plastic cup (43) for the sample, which contains the sample (44) of the test material, has a bottom that is liquid permeable, and is mounted on top of the porous glass plate (35) inside the funnel (34). The load (46) is mounted on top of the separation disk (45), which is mounted on top of the sample material.

The sample cup (43) consists of a plastic cylinder having an inner diameter of 1 inch (2.54 cm) and an outer diameter of 1.25 inches (3.18 cm). The bottom of the cup (43) for the sample is formed by gluing a 10 mesh metal mesh that has 150 micron holes to the end of the cylinder by heating the mesh to a temperature above the melting temperature of the plastic and pressing the plastic cylinder against the hot mesh so that the plastic melts and the mesh sticks would to a plastic cylinder.

To perform this test, the material (44) of the sample with a volume of 10, 12 cubic centimeters is placed in the cup (43) for the sample. A weight (46) of 100 grams is then placed on top of the spacer disc, thereby applying a load of approximately 0.3 psi (0.021 kg / cm ² ). The sample cup is placed on a porous glass plate (35).

A negative pressure gradient is established by lowering the funnel (34) until the fluid from the fluid reservoir (40) communicating with the atmosphere flows through the tubes (37, 38 and 39) into the funnel (34) so that it enters contact with a porous glass plate (35). The funnel (34) is then raised to a certain level along the graduated laboratory bench (31) until the required negative pressure gradient (which is measured as the height difference in centimeters between the upper liquid level in the liquid reservoir (40) communicating with atmosphere and porous glass plate level (35)). The recording device then measures the amount of fluid that has been removed from the fluid reservoir (40) in communication with the atmosphere and absorbed by the absorbent material, in grams of absorbed liquid per gram of base material, as a function of the negative pressure gradient. The negative pressure gradient is inversely proportional to the equivalent radius of the intermediate pores in accordance with the following equation:

R = (2γcosθ) / (δgh)

where R is the equivalent radius of the intermediate pores, γ is the surface tension of the liquid, θ is the retreating angle of wetting, δ is the density of the liquid, g is the acceleration of gravity, and h is the negative pressure gradient.

According to this test procedure, a table of the total pore volume can be compiled as a function of the equivalent radius of the intermediate pores.

Gel permeability test procedure

A device in the form of a piston / cylinder suitable for performing gel permeability tests (GHS) is shown in FIGS. 2 and 3. As can be seen in FIG. 2, device (120) consists of a cylinder (122) and a piston (in general, designated by number 124). As shown in FIG. 2, the piston (124) consists of a LEXAN cylindrical shaft (126), which has a concentric cylindrical channel (128) drilled along the longitudinal axis of the shaft. Both ends of the shaft (126) are processed in such a way that the first and second ends (130, 132) are formed. The load (134) is mounted on the first end (130) and has a cylindrical hole (136) drilled through its center. A round piston head (140) is inserted from the second end (132). The piston head (140) is dimensioned so that it can move vertically inside the cylinder (122). As shown in FIG. 3, the piston head (140) has inner and outer concentric rings containing seven and fourteen cylindrical holes approximately 0.375 inches (0.95 cm) in size, respectively (indicated generally by arrows 142 and 144). These holes in each of the concentric rings are drilled from top to bottom in the piston head (140). The piston head (140) also has a cylindrical hole (146) drilled in its center for installation of a second end (132) of the shaft (126) in it.

Attached to the lower end of the cylinder (122) is a mesh (148) in the form of a 400 mesh stainless steel fabric, which is stretched in the direction of both axes so that tension is generated before it is attached. A stainless steel mesh (150) is attached to the lower end of the cylinder head (140) in the form of a 400 mesh fabric, which was stretched in the direction of both axes to form tension before attaching. A sample (152) of absorbent material is mounted on a grid (148).

The cylinder (122) is formed by drilling from a rod of transparent LEXAN material or equivalent material and has an inner diameter of 6.00 cm (area = 28.27 cm ² ), a wall thickness of approximately 0.5 cm and a height of approximately 5.0 cm. (140) The piston is made of a rod made of LEXAN material. It has a height of approximately 0.625 inches (1.59 cm) and is such a diameter that it enters the inside of the cylinder (122) with a minimum clearance between the walls, but can move freely. A hole (146) in the center of the piston head (140) has a hole with a thread of 0.625 inches (1.59 cm) (18 turns / inch) (7 turns per centimeter) for the second end (132) of the axis (126). The shaft (126) is made of a shaft made of LEXAN material and has an outer diameter of 0.875 inches (2.22 cm) and an inner diameter of 0.250 inches (0.64 cm). The second end (132) is approximately 0.5 inches (1.27 cm) in length, and a thread is cut into it that corresponds to the thread in the hole (146) in the piston head (140). The first end (130) has a length of about 1 inch (2.54 cm) and a diameter of 0.623 inches (1.58 cm) so that an annular stop for forming a load (134) of stainless steel is formed. The stainless steel ring load (134) has an inner diameter of 0.625 inches (1.59 cm) so that it is put on the first end (130) of the shaft and mounted on the ring stop (126) formed on it. The total weight of the piston (124) and the load (134) is approximately 596 g, which corresponds to a pressure of 0.30 pounds per square inch (20.685 dyne / cm ² ), for an area of 28.27 cm ² .

When fluid flows through the device from the piston / cylinder, the cylinder (122) generally abuts against a rigid support mesh mesh 16 of stainless steel (not shown) or its equivalent. The piston and load are placed in an empty cylinder to obtain measurements of the distance from the bottom of the load to the top of the cylinder. This measurement is made using a vernier caliper with a division value of 0.01 mm. This measurement will subsequently be used to calculate the layer height of the absorbent material sample (152). It is important to measure each cylinder when empty and to keep track of which piston and load were used. The same piston and weight should be used for measurements when the sample of absorbent material swells.

The absorbent layer used for the measurement of ASG is formed by swelling approximately 0.9 g of an absorbent material sample in the device of the ASG cylinder (dry absorbent material should be evenly distributed over the cylinder grid before swelling) with a liquid that is usually 0.9 (wt. ./ob .)% NaCl solution in water for about 15 minutes. A sample of absorbent material is taken from a variety of absorbent materials that have previously been passed through a 30 mesh sieve according to the American standard and are held in a 50 mesh sieve according to the American standard. The absorbent material, therefore, has a particle size of 300 to 600 microns. Particles can be pre-screened manually or automatically, for example, using a Ro-Tap Model B mechanical sieving shaker, which is commercially available from W.S. Tiler, Inc., Mentor, OH USA.

After 15 minutes, the cylinder is removed from the liquid, and the piston assembly with the load is placed on a sample of absorbent material. The thickness of the swollen absorbent material sample is determined by measuring the distance from the bottom of the load to the top of the cylinder using a micrometer. The value obtained from measurements on an empty cylinder is subtracted from the value obtained after swelling of the absorbent material sample. The resulting value represents the height of the layer of the swollen sample of absorbent material N.

The ASG measurement is started by adding liquid to the cylinder (122) until the liquid reaches a height of 4.0 cm above the bottom of the absorbent material sample (152). This fluid height is maintained throughout the test. The amount of fluid passing through the absorbent material sample (152) as a function of time is measured gravimetrically. Data is taken every second for the first two minutes of the test and every two seconds for the rest of the time. When the data are plotted as the amount of fluid passing through the layer of the absorbent material sample versus time, it will become clear to those skilled in the art when a constant flow rate is obtained. Only the data collected when the flow rate becomes constant is used in the calculation of the flow rate. The flow rate Q through the absorbent material sample (152) is determined in g / s units by fitting the least squares method of the fluid passing through the absorbent material sample (in grams) versus time (in seconds).

The permeability in cm ^{2 is} obtained from the following equation:

K = [Q · (H · Mu)] / [A · Rho · P]

where K is the permeability of the gel layer (cm ² ); Q is the flow rate (g / s); H is the height of the layer of the absorbent material sample (cm); Mu - fluid viscosity (poise); A is the cross-sectional area for the fluid flow (cm ² ); Rho is the density of the liquid (g / cm ³ ); and P is the hydrostatic pressure (dyne / cm ² ) (usually approximately 3.923 dyne / cm ² ).

Examples

The following examples describe various embodiments of the present invention. Other embodiments set forth in the scope of the claims will be apparent to those skilled in the art upon consideration of the description or practice of using the present invention described herein. It is intended that the description, along with examples, which are considered for illustrative purposes only, correspond to the scope and spirit of the present invention as defined by the claims following the Examples section.

Example 1

This example demonstrates how absorbent silica material is well suited for treating complex fluids such as menstrual flow. The absorbent material used in this example was Zeofree 5175B, which is a granular absorbent material commercially available from J.M. Huber Corp., Havre de Grace, MD USA. The material was granulated physically and did not contain any other ingredients other than precipitated silica particles. Zeofree 5175B material, as obtained, was used to evaluate the rate of absorption and re-wetting. The results of this assessment are shown in Table 1.

The retention capacity of the complex fluid (using a simulating fluid) for the above sample was at least about 2.05 g / g.

Example 2

This example illustrates the effect of particle size and distribution on the absorption of Zeofree 5175B, which is a deposited silica absorbent material layer commercially available from J.M. Huber Corp., Havre de Grace, MD USA. In this example, Zeofree 5175B was sieved so that a finely graded particle size distribution sequence was obtained. The effect of these distributions on the absorption rate and re-wetting in the form as it was obtained, as well as in combinations was evaluated to illustrate that the absorption rate can be influenced by the appropriate combination of particles having different sizes. The results of these estimates are shown in Table 2a and show that a narrow particle size distribution is not effective for relatively fast absorption of the liquid.

Table 2b below shows that when a narrow particle size distribution is re-combined into bimodal particle size distributions, some combinations can absorb liquids with an absorption time of less than 150 seconds, which is considered preferred. Suitable combinations contain a significant percentage of coarse materials. Adequate ratios of fine and coarse materials include preferably 10/90; more preferably 20/80; and most preferably 25/75 mesh. These recombined ratios can be characterized as having standard deviations of more than 25 percent of the average.

Table 2c shows the intermediate pore size distribution for the sifted Zeofree 5175B sieved from about 30 to about 50 mesh in accordance with the definition of the capillary pressure test method. Table 2d shows the intermediate pore size distribution for Zeofree 5175B material with a ratio of 75% material from about 20 to about 30 mesh and 25% material from about 40 to about 50 mesh as defined by the Capillary Pressure Test Procedure. The pore size distribution obtained by combining the two sets of particle sizes shown in Table 2d contains a smaller percentage of small pores than in the sample shown in Table 2c. A relatively larger percentage of pores with a size greater than about 100 microns for the combined particle mixture correlates with improved absorption, according to the data in Tables 2a and 2b.

Example 3

This example illustrates that vermiculite, a hydrated layered magnesium-aluminum-iron-silicate (commercially available from Strong-Lite Products, P.O. Box 8029, Pine Bluff, AR 71611 USA), exhibits the required absorption rate, re-wetting, and complex fluid retention capabilities. Table 3a shows that vermiculite exhibits a suitable pore size distribution to provide the required absorption rate and re-wetting. The pore size distribution shown in Table 3b was determined by the capillary pressure test procedure. It is believed that the layered internal pore structure of vermiculite leads to the fact that this absorbent material exhibits the required properties of absorption rate, re-wetting and the ability to retain complex fluid.

Vermiculite shows a complex fluid retention capacity of at least about 2.17 g / g.

Example 4

This example shows that in the initial state, Ryolex 3, an absorbent material of aluminum silicate (commercially available from Silbrico Corp., River Rd., Hodgkins, IL 60525-4257 USA), which is known as perlite, exhibits the required absorption time as shown in Table 4a. Table 4b shows that Ryolex 3 has a suitable pore size distribution to provide the desired absorption rate. The pore size distribution of Table 4b is determined using the capillary pressure test method. Ryolex 3 exhibits a complex fluid retention capacity of at least about 4.4 g / g.

Example 5

This example illustrates that the Celphere CP305 material, small ball microcrystalline cellulose (commercially available from FMC Corp., 1735 Market St., Philadelphia, PA 19103 USA), exhibits the required absorption and rewet speed properties, as shown in Table 5.

Celphere CP305 is an example of an absorbent material with relatively spherical particles that has a uniform particle size distribution (i.e., the average particle diameter is about 400 microns). Since the particles are made with rather large sizes and are relatively spherical, the permeability of this material is high (i.e., above about 1000 K). Such high permeability explains the required absorption value. However, since the Celphere CP305 material does not have an internal structure, the complex fluid retention capacity is approximately 0.63 g / g and indicates the need for pores with sizes less than about 100 microns to retain the complex fluid.

Example 6

This example illustrates that LC200 HF material made from granular cellulose fibers (commercially available from J. Rettenmaier & Sohne GmbH & Co., D-73496, Rosenberg, Germany) exhibits the required absorption and rewet properties as shown in Table 6.

Example 7

Cab-O-Sil M5, which is raw distilled silica (commercially available from Cabot Corp., Boston, MA 02109 USA), has an effect on the rate of absorption of a complex fluid (simulating fluid in this case) caused by dehydration of fluids due to for the presence of too high a percentage (> 2 percent of small pores (<1 micron).

Table 7a shows the effect of excess pore size of less than about 1 micron on the absorption rate of a complex fluid.

The data in Table 7b illustrates that the pore size distribution for Cab-O-Sil material, determined by mercury porosimetry, contains about 8 percent of the pore volume in pores smaller than about 1 micron in diameter. Mercury porosimetry data was obtained from Micromeritics Instrument Corp., One Micromeritics Dr., Norcross GA 30093 USA. The required tests were macro- and meso-distribution of volume / size using mercury porosimetry, Test Number 005-65000-31. The sample was tested with a Micromeritics Instrument Corp.'s AutoPore Mercury Porosimeter, Unit 750 mercury porosimeter, starting at 17:00 on July 28, 1999 and ending at 10:00 on July 29, 1999.

The above examples are not intended to limit in any way the scope of the present invention. Various modifications and other embodiments and uses of the described composite materials containing superabsorbent material that are obvious to those skilled in the art are also considered to be within the scope of the present invention.

Claims (31)

1. An absorbent article comprising a retention aid and particles of at least one absorbent material, wherein the particles provide an absorbent pore volume that is provided by intermediate pores between the individual absorbent particles and the internal (within the particles) pores inside the individual absorbent particles, the absorbent particles provide the ability to retain liquid from 1 to 15 g of complex fluid per g of absorbent particles and individual absorbent particles have a pore diameter inside the particles of 100 about 0.2 μm, while in the means of holding 20 - 50% of the pore volume provided by the absorbent particles, pores with a diameter of more than 100 μm are formed for absorption of the complex liquid and distribution of the complex liquid and from 80 to 50% of the pore volume provided by the absorbent particles formed by pores with a diameter of less than 100 microns to hold the complex fluid, absorbent particles are present in the retention agent in an amount of at least 10% of the total weight of the retention agent and absorbent particles. 2. The absorbent article of claim 1, wherein the retention means comprises a top sheet and a back sheet. 3. Absorbent product according to claim 2, in which the top sheet is a non-woven material, permeable to liquid. 4. Absorbent product according to claim 2, in which the top sheet is a film with holes. 5. Absorbent product according to claim 2, in which the back sheet is a non-woven material. 6. The absorbent article of claim 1, wherein the absorbent material comprises a hydrophilic material. 7. The absorbent article of claim 1, wherein the absorbent particles are attached directly to the fibers or the polymer film. 8. Absorbent product according to claim 6, in which the absorbent material contains inorganic material. 9. The absorbent article of claim 8, wherein the absorbent material is selected from the group consisting of activated carbon, metal oxides, silicates, zeolites, carbonates, phosphates, borates and aerogels. 10. Absorbent product according to claim 6, in which the absorbent material contains organic material. 11. The absorbent product of claim 10, in which the absorbent material is selected from the group consisting of cellulosic materials, starches, chitins, alginates and synthetic polymers. 12. Absorbent product according to claim 6, in which the absorbent material is a mixture of organic and inorganic materials. 13. The absorbent product according to claim 1, in which the absorbent material has gaps from 100 to 1000 microns. 14. The absorbent product according to claim 1, in which less than 2% of the pore volume is formed by pores with a size of less than 1 μm. 15. An absorbent article comprising a retention aid and particles of at least one absorbent material, wherein the absorbent material particles provide a pore volume that is provided by intermediate pores between the individual absorbent particles and the internal (within the particles) pores inside the individual absorbent particles, wherein individual absorbent particles have internal pores with pore sizes within the particles of 100 to 0.2 μm and the absorbent particles provide complex fluid retention t 2 to 8 g of complex fluid per g of absorbent particles, while in the retention means from 80 to 50% of the pore volume provided by the absorbent particles, pores with a size of less than 100 μm are formed to hold the complex fluid, and the absorbent particles have a minimum average particle size comprising at least 200 μm with a standard deviation of at least 25% of the average particle size, the absorbent particles being present in the retention aid in an amount of at least 10% of the total mass of the retention aid and absorbent particles. 16. The absorbent article of claim 15, wherein the absorbent particles have an average particle size of 200-800 microns. 17. The absorbent article of claim 15, wherein the absorbent particles have an average particle size of 300 to 600 microns. 18. The absorbent article of claim 15, wherein the absorbent particles have an average particle size of 400-500 microns. 19. The absorbent article of claim 15, wherein the retention means comprises a top sheet and a back sheet. 20. The absorbent article of claim 15, wherein the absorbent material comprises a hydrophilic material. 21. The absorbent article of claim 15, wherein the absorbent particles are attached directly to the fibers or the polymer film. 22. The absorbent article of claim 15, wherein the absorbent material is a mixture of organic and inorganic materials. 23. The absorbent product according to clause 15, in which the absorbent material has gaps of 100 to 1000 microns. 24. The absorbent article of claim 15, wherein less than 2% of the pore volume is formed by pores with a size of less than 1 μm. 25. An absorbent article comprising a retention means and particles of at least one absorbent material, wherein the particles provide an absorbent pore volume that is provided by intermediate pores between the individual absorbent particles and the internal (within the particles) pores inside the individual absorbent particles, the absorbent particles provide the ability to retain liquid from 1 to 15 g of complex fluid per g of absorbent particles and individual absorbent particles have a pore diameter inside the particles of 100 up to 0.2 microns, while the absorbent particles in the retention aid comprise a combination of particles having different sizes, and the absorbent particles are present in the retention aid in an amount of at least 10% of the total weight of the retention aid and absorbent particles. 26. The absorbent article of claim 25, wherein the containment means comprises a top sheet and a back sheet. 27. The absorbent article of claim 25, wherein the absorbent material comprises a hydrophilic material. 28. The absorbent article of claim 25, wherein the absorbent particles are attached directly to the fibers or the polymer film. 29. The absorbent article of claim 25, wherein the absorbent material is a mixture of organic and inorganic materials. 30. The absorbent article of claim 25, wherein the absorbent material has gaps from about 100 to about 1000 microns. 31. The absorbent article of claim 25, wherein less than 2% of the pore volume is formed by pores with a size of less than about 1 μm.

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