MXPA99004376A - Heterogeneous surge material for absorbent articles - Google Patents

Abstract

There is provided a surge material for personal care products comprising a layered structure of at least one relatively high permeability layer on a top side toward a wearer and at least one relatively low permeability layer where the structure has a capillary tension range between about 1 and 5 cm with a differential capillary tension of at least about 1 cm from to top bottom. The surge material should have a high permeability layer with a permeability of at least 1000 Darcys and a low permeability layer with a permeability of less than 1000 Darcys. The surge material should also have a said high permeability layer which has a permeability of at least 250 Darcys greater than the low permeability layer. Such a layered structure should have a first insult run-off value of at most 30 ml from 100 ml insult delivered at 20 ml/second. Such a surge material is useful in personal care products like diapers, training pants, absorbent underpants, adult incontinence products, feminine hygiene products and the like.

Description

HETEROGENEOUS SURFACE MATERIAL FOR ABSORBENT ITEMS FIELD OF THE INVENTION This invention relates to absorbent articles particularly absorbent structures which are useful in personal care products such as disposable diapers, incontinence guards, training pants for child care, or sanitary napkins. More particularly, the invention relates to absorbent articles which have a portion designed for rapid intake, temporary liquid control, and subsequent release of liquid surges repeated to the remainder of the article.

BACKGROUND OF THE INVENTION Personal care products are absorbent articles that include diapers, training pants, women's hygiene products such as sanitary napkins, incontinence devices and the like. These products are designed to absorb and contain body exudates and are generally single use or disposable items which are discarded after a relatively short period of use - usually a period of hours - and are not intended to be washed nor that they fly to use. Such products are usually placed against or in proximity to the user's body to absorb and contain various exudates discharged from the body. All of these products typically include a liquid-permeable body-side cover or liner, a liquid-impermeable outer backing sheet or cover, an absorbent structure positioned between the body-side liner and the outer cover. The absorbent structure may include an emergence layer beneath the body-side liner and in liquid communication contact with said body-side liner, and an absorbent core frequently formed from a mixture or a combination of pulp fluff fibers cellulose and absorbent gelation particles under the emergence layer and in liquid communication contact with said emergence layer.

Desirably, the absorbent articles for personal care exhibit a low drainage of the product and a dry feeling for the user. It has been found that urination can occur at rates as high as 15 to 20 milliliters per second and at speeds as high as 280 centimeters per second and that an absorbent garment, such as a diaper, can fail by draining from the areas of front or back waist or from the legs. The inability of the absorbent product to take up the liquid quickly can result in excessive liquid stagnation on the face-to-face surface of the body-side liner before the liquid is taken up by the absorbent structure. Such stagnant liquid can moisten the skin of the user and can drain from the leg or waist openings of the absorbent article, causing discomfort, potential health problems to the skin, as well as soiling of the outer clothing or bedding of the patient. user.

Runoff and stagnation can result from a variety of performance deficiencies in the design of the product, or from individual materials within the product. One cause of such problems is an insufficient rate of fluid intake into the absorbent core, which functions to absorb and retain exudates from the body. The taking of liquid from a given absorbent product, therefore, and particularly the side-to-body lining and emergence materials used in the absorbent product, should attempt to meet or exceed the expected delivery rates of liquid into the absorbent product. . An insufficient intake rate becomes more detrimental to the operation of the product on the emergence of second, third, or fourth liquid. In addition, runoff can occur due to a poor embedment of the wet product that results when multiple insults are stored at the target location and cause the sagging and falling of the heavy and wet retention material structures.

Several approaches have been taken to reduce or eliminate runoff from absorbent articles for personal care. For example, physical barriers, such as elasticized leg openings and elasticized containment fins, have been incorporated into such absorbent products. The amount and configuration of the absorbent material in the area of the absorbent structure in which liquid surges typically occur (sometimes referred to as the target zone) have also been modified.

Other approaches to improve the overall fluid intake of the absorbent articles have focused on the side-to-body liner and its ability to rapidly pass the liquid to the absorbent structure of the absorbent article. Non-woven materials, including carded and bonded fabrics and spunbonded fabrics, have been widely used as side-to-body liners. Such nonwoven materials are generally intended to be sufficiently porous and sufficiently open to allow the passage of the liquid rapidly, while also functioning to keep the wearer's skin separate from the wetted absorbent under the liner. Attempts to improve the liquid intake of the liner materials have included, for example, drilling the lining material, treating the fibers that form the lining material with surfactants to improve liner wettability, and altering the durability of the lining material. such surfactants.

Still another approach has been to introduce one or more additional layers of material, typically between the body-side liner and the absorbent core, to improve the liquid intake performance of the absorbent product and to provide a separation between the absorbent core and the absorbent core. the lining from the side to the body on one side of the wearer's skin. One such additional layer, commonly referred to as an emergence layer, can suitably be formed from coarse nonwoven and elevated materials. The emergence layers, particularly the high-volume, high-rise, compressive-resistant fibrous structures, particularly, provide a temporary absorption or retention function for the non-absorbed liquid even within the absorbent core, which tends to reduce the return flow of fluid or wet back from the absorbent core to the liner.

Despite these improvements, there is a need for further improvement in the operation of liquid intake of the lining materials used in the absorbent articles. In particular, there is a need for lining materials that can take up quickly and then control the spreading of a liquid insult to the underlying layers. This improved handling is critical for narrow crotch absorbent product designs that use less storage and retention material in the target region and incorporate distribution features that remove fluid for storage in remote locations in order to alleviate notch problems such as means to reduce runoff. The present invention provides a heterogeneous emergence material that provides such enhanced fluid intake and controlled spreading when used in absorbent articles.

SYNTHESIS OF THE INVENTION The objects of this invention are achieved by an emergence material for personal care products which is a layered structure of at least one relatively high permeability layer and at least one relatively low permeability layer wherein the structure it has a range of capillary tension of between about 1 and 5 centimeters with a difference of at least about 1 centimeter from the top (user side) to the bottom. Such a layered structure must provide a first insult spill value of at least 30 ml of a 100 ml insult delivered at 20 ml / second. Such emergence material is useful in personal care products such as diapers, training pants, absorbent undergarments, incontinence products for adults, products for women's hygiene and the like and that should have a thickness of less than 3 centimeters. The emergence material of this invention is particularly suitable for use in narrow crotch diapers (7.6 centimeters maximum width).

BRIEF DESCRIPTION OF THE DRAWINGS The Figure is a side view drawing of a crib used for the MIST evaluation test.

DEFINITIONS "Disposable" includes being discarded or discarded after usually a single use and not intended to be washed and flown to be used.

"Front" and "back" are used throughout this description to designate the relative relations to the garment itself, rather than to suggest any position assumed by the garment when it is placed on a wearer.

"Hydrophilic" describes the fibers or the surface of the fibers which are wetted by the aqueous liquids in contact with the fibers. The degree of wetting of the materials can, in turn, be described in terms of the contact angles and the surface tensions of the liquids and materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials can be provided by a Cahn SFA-222 surface force analyzer system, or an essentially equivalent system. When measured with this system, fibers having contact angles of less than 90 degrees are designated "wettable" or hydrophilic, while fibers having contact angles equal to or greater than 90 degrees are designated "non-humidifying" or hydrophobic.

"Interior" and "exterior" refers to positions relative to the center of an absorbent garment, and particularly transversely and / or longitudinally closer to or away from the longitudinal and transverse center of the absorbent garment.

"Layer" when used in the singular may have the dual meaning of a single element or a plurality of elements.

"Liquid" means a non-gaseous substance and / or a material that flows and can assume the interior shape of a container into which it is poured or placed.

"Liquid communication" means that liquid such as urine is able to move from one place to another place.

"Longitudinal" and "transversal" have their usual meanings. The longitudinal axis lies in the plane of the article when it is placed flat and fully extended and is generally parallel to a vertical plane that divides a user standing in the left and right body halves when the item is used. The transverse axis lies in the plane of the article generally perpendicular to the longitudinal axis.

"Particles" refers to any geometric shape such as, but not limited to spherical grains, cylindrical fibers or threads, or the like.

"Spraying" and variations thereof include forcibly ejecting the liquid, either as a stream such as swirling filaments, or atomized particles through a hole, nozzle, or the like, by means of an applied air pressure or of another gas, by force of gravity or by means of centrifugal force. Spraying can be continuous or non-continuous.

The "spunbond fibers" refer to fibers of small diameter which are formed by extruding a melted thermoplastic material as filaments from a plurality of usually circular and thin capillaries of a spinning organ with the diameter of the extruded filaments then being rapidly reduced as indicated, for example, in U.S. Patent No. 4,340,563 to Appel et al., and in U.S. Patent No. 3,692,618 to Dorschner et al. United States of America number 3,802,817 granted to Matsu i and others, in the patents of the United States of America numbers 3,338,992 and 3,341,394 granted to Kinney, the patent of the United States of America number 3,502,763 granted to Hartman, and the patent of the United States of North America number 3,542,615 granted to Dobo and others. Spunbond fibers are not generally sticky when they are deposited on a picking surface. The fibers bound by spinning are generally continuous and have average diameters (from a sample of at least 10) larger than 7 microns, more particularly, between about 10 and 20 microns. The fibers may also have shapes such as those described in U.S. Patent Nos. 5,277,976 issued to Hogle et al., Number 5,466,410 issued to Hills and numbers 5,069,970 and 5,057,368 issued to Largman et al. conventional "Fibers formed by meltblowing" means fibers formed by extruding a melted thermoplastic material through a plurality of capillary matrix vessels, usually circular and thin, such as melted threads or filaments into gas streams (e.g. air) , usually hot and high speed and convergent which attenuate the filaments of melted thermoplastic material to reduce its diameter, which can be to a microfiber diameter. Then, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collector surface to form a meltblown fabric of fibers randomly discharged. Such a process is described, for example, in U.S. Patent No. 3,849,241. The fibers formed by meltblowing are microfibers which can be continuous or discontinuous, these are generally smaller than 10 microns in average diameter, and are generally sticky when deposited on a collecting surface.

As used herein, the term "coform" means a process in which at least one meltblown die head is arranged near a conduit through which other materials are added to the fabric while it is being formed. . Such other materials can be pulp, superabsorbent particles, cellulose or short fibers, for example. Such coform processes are shown in commonly assigned United States patents 4,818,464 to Lau and 4,100,324 to Anderson et al. Fabrics produced by the coform process are generally referred to as coform materials.

The term "conjugated fibers" refers to fibers which have been formed from at least two polymer sources extruded but spun together to form a fiber. Conjugated fibers are also sometimes referred to as multi-component or bicomponent fibers. The polymers are usually different from each other even though the conjugated fibers can be monocomponent fibers. The polymers are arranged in different zones placed essentially constant across the cross section of the conjugated fibers and which extend continuously along the length of the conjugate fibers. The configuration of such a conjugate fiber can be, for example, a pod / core arrangement where one polymer is surrounded by another or can be a side-by-side arrangement, a cake arrangement, or an arrangement of "islands in the sea". " Conjugated fibers are shown in U.S. Patent No. 5,108,820 issued to Kaneko et al., In U.S. Patent No. 5,336,552 issued to Strack et al., And in the U.S. Patent Number 5,382,400 awarded to Pike and others. For two component fibers, the polymers may be present in proportions of 75/25, 50/50, 25/75 or in any other desired proportions. The fibers may also have shapes such as those described in U.S. Patent Nos. 5,277,976 to Hogle et al., And in U.S. Patent Nos. 5,069,970 and 5,057,368 to Largman et al., Incorporated herein by reference. reference in its entirety, which describe fibers with unconventional shapes.

"Biconstituent fibers" refers to fibers that have been formed from at least two extruded polymers from the same extruder as a mixture. The term "mixture" is defined below. The biconstituent fibers do not have the various polymer components arranged in different zones placed relatively constant across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead of this they usually form fibrils or protofibrils which start and end in a random way. Biconstituent fibers are sometimes referred to as multi-constituent fibers. Fibers of this general type are discussed in, for example, U.S. Patent No. 5,108,827 issued to Gessner. Bicomponent and biconstituent fibers are also discussed in the textbook "Mixtures and Compounds of Polymers" by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenum Press, a division of Plenum Publishing Corporation of New York, IBSN 0-306-30831-2, pages 273 to 277.

"Carded and bonded fabric" refers to fabrics that are made of short fibers which are sent through a combing or carding unit, which separates or breaks and aligns the short fibers in the direction of the machine to form a fibrous non-woven fabric generally oriented in the direction of the machine. Such fibers are usually purchased in bales which are placed in an opener / mixer or picker that separates the fibers before the carding unit. Once the fabric is formed, it is then joined by one or more of the various known joining methods. One such bonding method is bonding with powder, wherein a powder adhesive is distributed through the fabric and then activated, usually by heating the fabric and adhesive with the hot air. Another suitable joining method is a pattern bonding, where heated calendering rolls or ultrasonic bonding equipment are used to join the fibers together, usually in a localized joined pattern, even when the fabric can be bonded through its full surface if desired. Another suitable and well known joining method, particularly when conjugated short fibers are used, is the bonding through air.

"Air placement" is a well-known process by means of which a fibrous non-woven layer can be formed. In the air laying process, bunches of small fibers having typical lengths ranging from about 3 to about 19 millimeters (mm) are separated and carried in an air supply and then deposited on a forming grid, usually with the help of a vacuum supply. The randomly deposited fibers are then bonded to one another using, for example, spray adhesive or hot air.

"Personal care product" means diapers, training pants, absorbent underwear, adult incontinence products, and women's hygiene products.

TEST METHODS Multiple Insult Test (MIST Evaluation): In this test a fabric, material or structure composed of two or more materials was placed in an acrylic crib to simulate the curvature of a user's body such as an infant. Such a cradle is illustrated in Figure 2. The cradle has a width within the page of the drawing as shown of 33 centimeters and the ends are blocked, at a height of 19 centimeters, from an internal distance between the upper arms of 30.5 centimeters and an angle between the upper arms of 60 degrees. The crib has a 6.5-millimeter wide groove at the lowest point running at the length of the crib on the inside of the page.

The material to be tested is placed on a piece of polyethylene film of the same size as the sample and placed in the cradle. The material to be tested is insulted with 100 ml of salt water solution of 8.5 grams of sodium chloride per liter, at a rate of 20 cc / second with a normal nozzle at the center of the material and 6.4 mm above the material. The amount of spill is recorded. The material is immediately removed from the crib, weighed and placed on a 40/60 dry super absorbent pulp pad, having a density of 0.2 g / cc in a horizontal position under a pressure of 0.01 psi and weighed after of 5, 15 and 30 minutes to determine the desorption of fluid from the material in the super absorbent pad as well as the retention of fluid in the material. The pulp fluff and superabsorbent used in this test are CR-2054 pulp from Kimberly-Clark (from Dallas, Texas) and super absorbent FAVOR 870 from Stockhausen Company (from Greensboro, North Carolina 27406) even when other comparable superabsorbents and pulps they can be used as long as they give a desorption pad of 500 grams per square meter and 0.2 g / cc which after immersion in salt water solution under conditions of free inflation for 5 minutes, retains at least 20 grams of salt water solution per gram of desorption pad after being subjected to a difference in air pressure, by vacuum suction, for example, of about 0.5 psi (about 3.45 kPa) applied to through the thickness of the pad for 5 minutes. If the tested piece is made of other components (for example it is a laminate) the components or layers are separated and weighed to determine the division of liquid between them and then they are reassembled after each weighing and placed back on the waste / super absorbent. This test is repeated using fresh desorption pads in each insult so that a total of three insults are entered and the fluid division was measured over 1.5 hours with 30 minutes between insults. Five tests of each sample material are recommended.

Permeability: The permeability (k) can be calculated from the Kozeny-Carman equation. This is a widely used method. References include an article by R. Hoyland and R. Field in the newspaper "Tecnolocfía y Industria del Papel", December 1976, pages 291-299 and "Transport of Medium Porous Fluid and Poro Structure" by F.A.L. Dullien, 1979, Academic Press, Inc. ISBN 0-12-223650-5.

Calculated Variable Equation Dimensions Permeability p.p.11 Darcys Constant of Kozeny = K Without Dimension Surface area by material mass = Sv =? X¡ cm2 / g -i, effec P? Density of average mass component of mass = Pprom g / cm3 surface area by = S0 = Sv Pprom cm "1 solid volume of the material Porosity = e = 1 -? X¡ Pteh Without Dimension Fiber effective radio = ri efec p. p. 12 cm Density of the fabric = Pteía g / cm3 For long effec cylinders For spheres riefec p.p.12 Where di = diameter of the component i (microns) Pj = density of the component i (g / cm3) Xi = mass fraction of the component i in the fabric BW = weight of sample / area (g / m2) t = sample thickness (mm) under 0.05 psi (23.9 dyne / cm2) or load of 2.39 Pascal (N / m2) Permeability Example Calculation For a structure which contains 57 percent southern softwood pulp, 40 percent super absorbent and 3 percent binder fiber, and has a basis weight of 617.58 g / m2 and a volume thickness of 5.97 mm at 0.05 psi, follow the example permeability calculation.

The properties of the component are as follows (note that the form is approximate): Pteía (g / cm3) p.p.13 Pteía (g / cm3) Pteía (g / cm3) = 0.1034 = 1? X¡ Ptela P: 10 0. 9309 Sv (cm2 / g) = S X, _ - * - i, efec '• i Sv (cm2 / g) Sv (cm2 / g) = 1194 Pprom (g / cm3) Pprom (g / cm3) Pprom (g / cm3) = 1,496 SQ (cm "1) = Sv Pprom S0 (cm" 1) 1194 x 1,496 S0 (cm "1) = 1786 K K K = 10.94 k p.p.14 p.p.14 k = 491 darcys Material Caliber (thickness). The material gauge is a measure of thickness and is measured at 0.05 psi with a Starret type volume tester, in units of millimeters.

Density. The density of the materials was calculated by dividing the weight per unit area of a sample in grams per square meter (gsm) by the volume of the sample in millimeters (mm) to 68.9 paséales and multiplying the result by 0.001 to convert the value to grams per cubic centimeter (g / cc). A total of three samples were evaluated and averaged for the density values.

Transmission Time and Vertical Fluid Flow of an Absorbing Structure. A sample strip of approximately 5 centimeters by 38 centimeters material was placed vertically so that when the sample strip was placed on top of a liquid reservoir at the beginning of the test, the bottom of the sample strip will just touch the surface of liquid. The liquid used was a saltwater solution of 8.5 g / l. The relative humidity should be maintained at around 90 to about 98 percent during the evaluation. The sample strip is placed above the known weight and liquid volume and a timing is started as soon as the bottom edge of the sample strip touches the surface of the solution.

The vertical distance of the liquid front was recorded by moving upwards of the sample strip and the weight of the liquid absorbed by the sample strip at various times. The time plot was made against the front height of the liquid to determine the transmission time to around 5 centimeters and to around 15 centimeters. The weight of the liquid absorbed by the sample strip from the beginning of the evaluation to around 5 centimeters and around a height of 15 centimeters was also determined from the data. The Vertical Liquid Flow value of the sample strip of a particular height was calculated by dividing the grams of liquid absorbed by the sample strip by each of: the basis weight (grams per square meter) of the sample strip; the time, in minutes, necessary for the liquid to reach the particular height; and the width, in inches, of the sample strip. Capillary stress in materials not containing super absorbers (eg sprouting materials) was simply measured by the equilibrium vertical transmission height of a salt water solution of 8.5 g / l after 30 minutes.

DETAILED DESCRIPTION The traditional absorbent systems for personal care products can be generalized as having the functions of emergence control and containment (retention) or SC.

The emergence control materials, the "S" in SC, are provided to quickly accept the incoming insult and either absorb, retain or channel or otherwise handle the liquid so that it does not run out of the article. The emergence layer can also be referred to as a take-up layer, a transfer layer, a transport layer and the like. An emergence material should typically be capable of handling an incoming insult of between about 60 and 100 cubic centimeters at an insult volumetric flow rate of from about 5 to 20 cc / sec, for infants, for example.

The containment or retention materials, the "C" in SC, they must absorb the insult quickly and efficiently. These must be able to pull the liquid from the distribution layer and absorb the liquid without a significant "gel block" or a blockage of the liquid penetration further into the absorbent by the expansion of the outer layers of the absorbent. The retention materials are frequently super absorbent materials of higher rate such as the super absorbent mixtures of polyacrylate and fluff. These materials absorb and quickly retain the liquid.

As mentioned above, traditional absorbent systems having the functions of emergence and containment control usually retain the vast majority of any insult in the target area, usually the crotch. This results in products for personal care having crotches which are very wide. Examples of retaining ability and containment location of various commercial diapers are presented in Table 3 of United States Patent Application No. 08/755, 136, filed the same day and assigned to the same assignee as this application and entitled "ABSORBENT ARTICLES WITH CONTROLLABLE FILL PATTERNS".

In contrast to traditional absorbent systems, the patent application "ABSORBENT ARTICLES WITH CONTROLLABLE FILL PATTERNS" presents an absorbent system which includes components that have been designed, arranged, and assembled so that within a certain time after each insult , the liquid will be located in a previously specified area of the absorbent system, for example, separated from the target area. Using an absorbent system arbitrarily divided into five zones, these absorbent systems have a "fill ratio" of grams of fluid located in the central target zone, usually in the crotch, to each of the two end zones which is less than 5: 1 after three insults of 100 ml separated by 30 minutes. It is preferred that this fill ratio be less than 3: 1, and it is more preferred that it be 2.5: 1. Many commercial diapers currently available have filling ratios of 20: 1, 50: 1 or even larger, for example these should retain almost all the liquid insult in the crotch.

In addition to sprouting and containment control materials in traditional absorbent systems, recent work has introduced another layer interposed between layers S and C. This new layer is a distribution layer, which produces a system with an emergence control , distribution and containment or "SDC".

The distribution materials, the "D" in SDC, must be able to move the fluid from the initial deposit point to where it is desired to store it. The distribution must take place at an acceptable rate so that the target insult area, usually the crotch area, is ready for the next insult. By "ready for the next insult" is meant that enough liquid has been moved out of the target area so that the next insult results in liquid absorption and spillage within acceptable volumes. The time between insults can vary from just a few minutes to hours, generally depending on the age of the user.

Absorbent products, such as, for example, diapers, generally also have a liner which goes against the wearer, a back sheet which is the outermost layer. An absorbent product which may contain other layers such as the multifunctional materials described in patent application No. 08 / 754,414, filed the same day and assigned to the same assignee of this application and entitled "MULTIFUNCTIONAL ABSORBENT MATERIALS AND PRODUCTS MADE OF THEMSELVES " The retention materials in the absorbent product can also be sonified to provide specific filling patterns and to move liquids from the target area to remote storage areas as described in patent application number 08/755, 136, filed on same day and assigned to the same transferee of this application and entitled "ABSORBENT ARTICLES WITH CONTROLLABLE FILLING PATTERNS". While it may seem obvious, it should be noted that in order to function effectively, the materials used in the personal care product absorbent systems must have sufficient contact to transfer the liquid between them.

The liner is sometimes referred to as a side-to-body lining or a top sheet and is adjacent to the emergence material. In the direction of the thickness of the article, the lining material is the layer against the skin of the wearer and thus is the first layer in contact with the liquid or other exudate of the wearer. The lining also serves to isolate the wearer's skin from liquids maintained in the absorbent structure and must be docile, soft feeling and non-irritating.

Various materials can be used to form the side-to-body liner of the present invention, including perforated plastic films, woven fabrics, non-woven fabrics, porous foams, cross-linked foams and the like. Non-woven materials have been found particularly suitable for use in the formation of the side-to-body lining, including fabrics of yarn-bonded or melt-blown fabrics of polyolefin filaments, polyester, polyamide (or other similar fiber-forming polymer). ), or carded and bonded fabrics of natural polymers (eg, rayon or cotton fibers) and / or synthetic polymer fibers (eg, polypropylene or polyester). For example, the side-to-body liner may be a non-woven fabric of synthetic polypropylene filaments having an average fiber size (from a sample of at least 10) ranging from about 12 to about 48 microns. , and more particularly from around 18 to around 43 micras. The nonwoven fabric may have a basis weight (e.g., ranging from about 10.0 grams per square meter (gsm) to about 68.0 grams per square meter, and more particularly from about 14.0 grams per square meter to about 42.0 grams per square meter, a volume or thickness ranging from about 0.13 millimeters (mm) to about 1.0 millimeters, and more particularly from about 0.18 millimeters to about 0.55 millimeters, and a density of between about 0.025 grams per cubic centimeter (g / cc) and about 0.12 g / cc, and more particularly between about 0.068 g / cc and about 0.083 g / cc Additionally, the permeability of such non-woven fabric can be from about 150 Darcys to around 5000 Darcys The non-woven fabric can be treated on the surface with a selected amount of surfactant, such as about 0.28 percent Triton X-102 surfactant, or processed in another way a to impart the desired level of wettability and hydrophilicity. If a surfactant is used, it may be an internal additive or applied to the fabric by any conventional means, such as spraying, printing, embedding, brush coating and the like.

The emergence layer is more typically interposed between and in an intimate liquid communication contact with the side-to-body liner and another layer such as a distribution or retention layer. The emergence layer is generally adjacent to the internal (unexposed) surface of the liner from side to body. To further improve the transfer of the liquid, it may be desirable to hold the upper and / or lower surface of the emergence layer to the liner and distribution layer, respectively. Suitable conventional clamping techniques can be used, including without limitation, bonding with adhesive (using water-based, solvent-based and thermally activated adhesives), thermal bonding, ultrasonic bonding, and bolt stitching and drilling, as well as combinations of the above or other appropriate fastening methods. If, for example, the emergence layer is adhesively bonded to the liner from side to body, the amount of adhesive added must be sufficient to provide the desired level or levels of bonding, without excessively restricting the flow of liquid from the liner to the layer of emergence. The emergence material of this invention will be discussed in more detail below.

As described in the previously cited and commonly owned patent application entitled "MULTIFUNCTIONAL ABSORBENT MATERIALS AND PRODUCTS MADE FROM THEM", the multifunctional material has been designed to assist the emergence material 1) by accepting a part of the volume of insult during the forced flow; for example during a real insult, 2) by desorbing the material arising from the liquid during and after the insults, 3) by allowing a part of the volume of insult to pass through itself (the multifunctional material) to the distribution material and 4) by permanently absorbing a part of the liquid insult. If such multifunctional material is used, the multifunctional and emergence material must be designed to function together as described in the previously cited and commonly owned patent application "MULTIFUNCTIONAL ABSORBENT MATERIALS AND PRODUCTS MADE OF THEM". The basic structure of the multifunctional material is a unique blend of superabsorbent material, high volume wet elastic pulp, and a structure stabilizing component such as a polyolefin binder fiber. The multifunctional material has a permeability of between about 100 and 10,000 Darcys, a capillary tension between about 2 and 15 centimeters, and a spill rate of less than 25 ml per 100 ml of insult, during its lifetime. The "life" of the multifunctional material is considered to be three insults of 100 ml each where each insult is separated by 30 minutes. In order to achieve the required capillary tension and permeability, it is preferred that the multifunctional material have between 30 and 75 percent by weight of a super absorbent of slow rate, between 25 and 70 percent by weight of pulp and from an amount positive up to about 10 percent of a binder component. The material should have a density between about 0.05 and 0.5 g / cc. The base weight of the material will vary depending on the application of the product but should generally be between about 200 and 700 grams per square meter. The multifunctional material is preferably located between the emergence and distribution layers.

The distribution layer must be able to move the fluid from the initial deposit point to where storage is desired. The distribution must take place at an acceptable rate so that the target insult area, usually the crotch area, is ready for the next insult. The time between insults can vary from just a few minutes to hours, generally depending on the age of the user. In order to achieve this transportation function, a distribution layer must have a high capillary tension value. The capillary tension in the distribution materials is measured simply by the equilibrium transmission of a saltwater solution of 8.5 g / ml according to the vertical liquid flow rate test, not by the test method given for the materials containing super absorbent. A successful distribution layer must have a capillary tension greater than that of the adjacent layer (on the side towards the user) and preferably a capillary tension of at least about 15 centimeters. Due to the generally inverse relationship between capillary tension and permeability, such high capillary tension indicates that the distribution layer will usually have a low permeability.

Another desired liquid transport property of a suitable distribution material is that it exhibits a vertical liquid flow rate, at a height of about 15 centimeters, suitably of at least about 0.002 grams of liquid per minute per meter. square (gsm) of the distribution material per inch of cross-sectional width of the distribution material g / (min * gsm * inch), up to about 0.1 g / (min * gsm * inch). As used herein, the Vertical Liquid Flow Rate value of the distribution material is intended to represent the amount of liquid transported through a limit at a specified vertical distance outward from the insult site of the centralized liquid per minute per minute. standardized amount of distribution material. The Vertical Liquid Flow Rate, at a height of about 15 centimeters, of a distribution can be measured according to the test method given here.

Another desired liquid transport property of a distribution material is that it exhibits a Vertical Liquid Flow Rate, at a height of about 5 centimeters, suitably of at least about 0.01 g / (min * gsm) * inch) of up to about 0.5 g / (min * gsm * inch). The Vertical Liquid Flow Rate, at a height of about 5 centimeters, of an absorbent structure can be measured according to the test method described here.

The materials from which the distribution layer can be made include woven fabrics and non-woven fabrics. For example, the distribution layer may be a non-woven fabric layer composed of a meltblown or spin-bonded fabric of polyolefin filaments, polyester, polyamide (or other fabric-forming polymer). Such non-woven fabric layers may include conjugate biconstituent and homopolymer fibers of short or other lengths and blends of such fibers with other types of fibers. The distribution layer can also be a bonded and carded fabric, an air-laid fabric or a wet-laid pulp structure composed of natural and / or synthetic fibers, or a combination thereof. The distribution layer can have a basis weight of from 35 to 300 grams per square meter, or more preferably from 80 to 200 grams per square meter, a density of between about 0.1 and 0.5 g / cc and a permeability of between about of 50 and 1,000 darcys.

The retention materials are typically cellulosic or super absorbent materials or mixtures thereof. Such materials are usually designed to rapidly absorb liquids and to retain them without usually releasing them. Super absorbers are commercially available from a large number of manufacturers including Dow Chemical Company of Midland, Michigan and Stockhausen Corporation of Greensboro, North Carolina. As described in the aforementioned and commonly owned patent application entitled "ABSORBING ITEMS WITH CONTROLLABLE FILL PATTERNS", the retention materials can be zoned and their composition can be chosen to move the liquids out of the target area into places more remote storage Such a design more efficiently uses the complete absorbent article and in the case of a diaper, for example, it helps the production of a narrower crotch article where the "narrow crotch" means diapers having a width of at most 7.6 centimeters. The filling patterns and materials shown in the patent application "ABSORBENT ARTICLES WITH CONTROLLABLE FILL PATTERNS" result in liquid by weight in the target area of less than 5 times that in the remote storage locations, which is a Significant improvement over previous designs.

The backing sheet is sometimes referred to as the outer cover and this is the farthest layer from the user. The outer cover is typically formed of a thin thermoplastic film, such as a polyethylene film, which is essentially impermeable to liquid. The outer cover functions to prevent the exudates of the body contained in the absorbent structure from wetting or soiling the wearer's clothing, bedding, or other materials in contact with the diaper. The outer cover can be, for example, a polyethylene film having an initial thickness of from about 0.012 millimeters to about 0.12 millimeters. The outer shell of polymer film may be etched and / or have a matte finish to provide a more aesthetically pleasing appearance. Other alternate constructions for the outer cover include woven or non-woven fibrous fabrics that have been constructed or treated to impart the desired level of liquid impermeability, or the materials formed of a woven or non-woven fabric and a thermoplastic film. The outer cover can optionally be composed of a "breathable" microporous material, permeable to steam or gas, which is permeable to vapors or gas but essentially impermeable to liquid. Respirability can be imparted to the polymer films by, for example, the use of fillers in the film polymer formula, extruding the filler / polymer formula into a film and then stretching the film sufficiently to create voids around the filler particles. filler, thus making the film breathable. Generally, the more filler is used and the higher the degree of stretch, the greater the degree of breathability. The backrests can also serve the function of a member that matches for mechanical fasteners, in the case, for example, where a non-woven fabric is the outer surface.

In relation to emergence materials, various woven fabrics and non-woven fabrics can be used to construct an emergence layer. For example, the emergence layer may be a layer of non-woven fabric composed of a fabric formed by meltblown or joined by spinning polyolefin filaments. Such non-woven fabric layers may include conjugate biconstituent and homopolymer fibers of short or other lengths and blends of such fibers with other types of fibers. The emergence layer can also be a carded and bonded fabric or an air-laid fabric composed of natural and / or synthetic fibers. The carded and bonded fabric can, for example, be a carded and bonded fabric, a carded and infrared-bonded fabric, or a carded fabric bonded through air. The carded and bonded fabrics may optionally include a mixture or combination of different fibers, and the fiber lengths within a selected fabric may vary from about 3 millimeters to about 60 millimeters. Prior emergence layers have had a basis weight of at least about 0.50 ounces per square yard (about 17 grams per square meter), a density of at least about 0.010 grams per cubic centimeter and a pressure of 68.9 passéales, a volume of at least about 1.0 millimeters at a pressure of 68.9 paséales, a volume recovery of at least about 75 percent, a permeability of around 500 to about 5,000 darcys, and a surface area by hollow volume of at least about 20 square centimeters per cubic centimeter. Examples of such materials can be found in U.S. Patent No. 5,490,846 issued to Ellis and others and in U.S. Patent No. 5,364,382 issued to Latimer. A material of homogeneous emergence is described in the patent application number 08/755, 514, filed on the same day and assigned to the same assignee of this application and entitled "HIGHLY EFFICIENT SURFING MATERIAL FOR ABSORBENT ARTICLES". The emergence layers may be composed of an essentially hydrophobic material, and the hydrophobic material may optionally be treated with a surfactant or otherwise processed to impart a desired level of wettability and hydrophilicity. The emergence layers may have a generally uniform thickness and a cross-sectional area.

Emergence control materials can take liquid insults at the rate and volume of delivery to prevent the top surface from overflowing and keeping the liquid inside the structure once it is taken to prevent spillage. Traditional emergence control materials are high permeability and low density structures with low capillary tension that facilitates collection and spreading, especially during an insult. However, these low permeability, low capillary structures exert a low level of control over the liquid and the scattered liquid can quickly approach the perimeter of the emergence and spill control material. This is a source of runoff in the crotch area of personal care products where the width of the product is generally less than the length of the product and is of particular concern in narrow-leg personal care products ( less than 7.6 centimeters).

If the hollow volume of the emergence control material is maintained, the thickness of a narrow crotch emergence control material should be greater than the broader crotch examples or more emergence control material should be made available in the dimension of the product length. Additional thickness and / or additional length will not be beneficial unless this Extra hollow volume is filled with liquid before draining. The lower permeabilities are required to make the thicker emergence control materials fill to a higher height during an insult and higher capillary stresses are required to control the liquid keeping it in the structure as well as transmitting the liquid in such a way that more hollow volume can be used along the length of the product. The lower permeability acts to increase the height of the liquid and decelerate the planar spreading preventing it from reaching the edges of the material while the upper capillary tension acts to retain the liquid so that it will not come out at the edges during and after filling.

The benefits of high capillary tension surge control materials and lower permeability are demonstrated in the patent application entitled "HIGHLY EFFICIENT SURFING MATERIAL FOR ABSORBENT ITEMS". However, as the permeability is reduced, the potential for surface stagnation or spillage of liquid from the upper surface of the material increases, especially at higher insult rates or when an insult hits the surface of the emergence control material at a acute angle, limiting the penetration of liquid from the emergence control structure. These effects may vary depending on the user's habits and the conditions of use. It has been found that the emergence control material with a decreasing permeability gradient in the z-direction, where a capillary voltage gradient can also be imparted provides an improved control input and operation especially for insult conditions of volume and high rate with narrow crotch products under many conditions of use.

The emergence material of this invention is designed to refer to a number of important aspects of liquid collection and controlled spreading.

The intake of liquid is important since it has been found that urination can occur at volumetric rates as high as 15 to 20 milliliters per second and at a rate as high as 280 centimeters per second. The failure to quickly take this fluid can result in runoff from the legs or from the front or back waist areas. The inability of an absorbent product to rapidly take up the liquid can also result in excessive stagnation of the liquid on the surface facing the body of the liner from side to body before the liquid is taken up by the absorbent structure. Such stagnant liquid can moisten the wearer's skin and can squeeze from the leg or from the waist openings of the absorbent article, causing discomfort, potential skin health problems, as well as soiling of outer clothing or bedding of the user.

Controlled spreading of the liquid from an insult is important, particularly in narrow crotch absorbent articles since it increases the contact area of the underlying layer to the emergence layer with the incoming liquid insult. This greater contact area uses more efficiently all the mass of the underlying layers.

The acquisition and controlled spreading objectives of this invention are achieved by the use of an emergence material having a permeability gradient in the z-direction combined with an increasing level of capillary control in the z-direction. More particularly, the inventive emergence has a relatively high permeability on the side of the material towards the user and a relatively lower permeability on the remote side of the user and towards the underlying layers. Even more particularly, the emergence of the invention has a permeability on the user side of more than 1,000 darcys and on the user's far side of less than 1,000 darcys. Even more particularly, the inventive emergence should have a difference of permeability between the layers of at least about 250 darcys and more particularly of at least 500 darcys.

In addition to the permeability requirements of the inventive emergence material, such emergence material must have a gradient of capillary tension in the z-direction where the layer has a relatively low capillary tension on the material side towards the user and a tension relatively superior capillary on the remote side of the user and towards the underlying layers. More particularly, the inventive emergence has a range of capillary tension of between about 1 and 5 centimeters with a difference of at least about 1 centimeter from the top to the bottom.

The exact permeabilities of a finished emergence material will depend on the width of the absorbent article as well as the thickness of the layers of emergence material. By reducing the thickness of the high permeability top layer of the emergence material, for example, the permeability of the lower layer should be reduced. As the overall width of the emergence material is reduced, the permeability of the lower emergence layer should also be reduced. For example, if the width of the emergence materials is 7.6 centimeters and the top layer has a permeability of 1,000 darcys and a thickness of 1.1 centimeters, the thickness and permeability of the lower layer should be 1.1 centimeters and 980 darcys. If the width of the emergence material is reduced to 5.1 centimeters with the same thickness and permeability of the top layer, the thickness and permeability of the bottom layer should be 4 centimeters and 74 darcs. If the width of the material of emergence is of 7.6 centimeters and the permeability of the upper layer is of 2,000 darcys and the thickness of 0.77 centimeters, the thickness and the permeability of the lower layer should be of 1.4 centimeters and 590 darcys.

The layers of the emergence material can also be oriented as determined by the stress test, in the machine direction (MD) or in the cross machine direction (CD). These can be oriented at least 3: 1, MD: CD or more. Such emergence is given in Example 6.

The permeability and thickness of the upper and lower emergence layers can be controlled by selecting the appropriate combination of fiber size and fabric density. In addition, the materials from which emergence layers are constructed can be selected to ensure that objective permeability levels are maintained through numerous liquid insults. Further, even when for discussion purposes the emergence has been referred to as having two layers, the emergence may have any number of layers provided that the capillary tension and the permeability of the overall layer structure is within the claimed invention.

A number of emergence layers were tested according to the MIST evaluation test to determine the effusion. The width of the emergence material was 5.1 centimeters and the length of 17.4 centimeters in Examples 1 - - 6 to result in an available void volume of around 100 cc. The insult was deliberate at a rate of 20 ml / sec to a total amount of 100 ml of 8.5 g / l salt water solution at room temperature. The data is shown in the Table where the density (Den) is in grams / cc, the number of layers in the sample is given in the "number of layers" column, the permeability (Perm) is given in darcys, the capillary tension (CT) is given in centimeters according to vertical balance transmission, the thickness of the general sample (esp) is in centimeters (cm), the spill after each insult (first R, etc.) is given in milliliters (ml) and the fluid retained after each insult (first F, etc.) in three columns on the right side in grams. Note that Examples 4 and 5 are multiple layer emergence materials as indicated in the permeability and capillary tension columns that give the data for each component layer.

In the Examples that follow the component properties used in the calculations given here were as follows: Note that the relationship between the denier and the diameter is as follows: diameter (miera) = (denier / pi x fiber density x 9 x 105) 1/2 x 104.

For the emergence material of this invention, the first spill value of insult should be equal to or less than 30 ml of an insult of 100 ml delivered at 20 ml / second, with the remaining two spills of insult being equal to or less than 30 ml each. In the most preferred modalities all three insults have spillage values less than or equal to 25 ml.

The materials described in Examples 1-4 are air-bound carded fabric structures produced on a dual 102-cent pilot card line. The bonded carded fabric structures were produced at a basis weight of approximately 100 grams per square meter. The test samples for Examples 1-4 had length and width dimensions of 15 centimeters by 5.1 centimeters respectively. The material layers of 100 grams per square meter were placed in layers as indicated in the Table to give the required thickness as indicated in the Table. The resulting test samples contained approximately 150 cc of the total volume calculated by multiplying length times width times thickness. The test configuration, however, resulted in less than 10.2 centimeters of the 15.2 length accessible and usable for insults resulting in approximately 100 cc of accessible hollow volume. It has been empirically found that the samples in the MIST test cradle use about 2 inches in length on each side of the insult point, or 10.2 centimeters, not the full sample length, which results in the 100 cc calculated hollow volume .

E J E M P O Example 1 is a carded fabric bonded through air containing 90 percent by weight polyethylene terephthalate / polyethylene terephthalate (PE / PET) sheath / core conjugate of 3.8 centimeters, 1.8 denier and 10 percent by weight of a 1.5-inch 1.5-denier rayon fiber. PE / PET fibers are available from BASF Fibers, 6805 Morrison Boulevard, Charlotte, North Carolina 28211-3577 and were polyethylene / polyethylene terephthalate (PE / PET) sheath / core conjugated fibers with a C S-2 finish based on polyethylene glycol. The rayon fibers were Merge 18453 1.5 denier fibers from Courtaulds Fibers Incorporated of Axis, Alabama.

E J E M P L O 2 Example 2 is an air-bonded carded fabric containing 90 percent by weight of 1.5 inch, 3.0 denier, and 10 percent by weight 1.5 inch rayon PE / PET conjugate core fibers. of 1.5 denier. PE / PET fibers are available from BASF Fibers, 6805 Morrison Boulevard, Charlotte, North Carolina 28211-3577 and were polyethylene / polyethylene terephthalate (PE / PET) sheath / core conjugated fibers with a C S-2 finish based on polyethylene glycol.

EXAMPLE Example 3 is an air-bonded carded fabric containing 90 percent by weight of 1.5 inch, 10.0 denier and 10 percent by weight of 1.5 inch rayon / PE conjugate core PE / PET fibers. and 1.5 denier. PE / PET fibers are available from BASF Fibers, 6805 Morrison Boulevard, Charlotte, North Carolina 28211-3577 and were polyethylene / sheath polyethylene terephthalate / conjugate core (PE / PET) with a C-S finish. 2 based on polyethylene glycol.

E J E M P L O 4 Example 4 is a two component gradient structure fulfilling the criteria of the invention. The top component is as given in Example 3 and the bottom is as given in Example 1.

E J E M P L O 5 Example 5 is a two-component gradient structure fulfilling the criteria of the invention. The top component is as given in Example 2 and the bottom is as given in Example 1.

E J E M P L O 6 Example 6 is a two-component gradient structure fulfilling the criteria of the invention. The upper component is a homogeneous mixture of 60 percent by weight of PE / PET conjugate fiber of 1.5 inches of 3.0 denier and 40 percent by weight of PET fiber of 1.5 inches of 6 denier. Nine layers of each component were stacked together to produce the material for the test.

The fibers of the upper component were Hoechst Celanese Corporation of Charlotte, North Carolina under codes T256 and T295 respectively. The upper component had a basis weight of about 1.05 ounces per square yard (50 gsm) and a density of about 0.014 g / cc. The top component mixture was carded using a Master Card with an eb-Master® remover roller by John D. Hollingworth of heels, Inc., of Greenville, North Carolina. The upper component had a fiber orientation ratio of about 3 to 5: 1 MD: CD as determined by the tensile strength ratios in the MD and CD.

The bottom component was 100 percent by weight of 1.5 inch 2.2 denier polypropylene fiber available from Hercules Chemical Company of Wilmington, Delaware under code T186 and had a basis weight of about 35 gsm. After the air binding of this layer, it had a density of around 0.067 g / cc. This layer was carded using a Master Card with a Dof-Master® remover roller by John D. Hollingworth of Wheels, Inc. The bottom component had a fiber orientation ratio of 12 to 15: 1 MC: CD as determined by the proportions of resistance to tension.

The upper component had a capillary tension of around 0.6 and the background of around 2.7 centimeters.

E J E P L O Example 7 is a two component gradient structure similar to that of Example 6 fulfilling the criteria of the invention. The top component is a homogeneous mixture of 30 percent by weight of PE / PET conjugate fiber of 1.5 inches of 3.0 denier and 70 percent by weight of PET fiber of 1.5 inches of 6 denier. The bottom component was 100 percent by weight of 1.5 inch 2.2 denier polypropylene fiber. The suppliers and base weights of each layer were the same as in Example 6. No layer was carded to increase orientation.

B It is very surprising from the examination of the data in the Table that a multi-layer emergence material of about the same thickness as the single emergence layer material can have better (lower) spill results. This can be seen by comparing Example 3 with Examples 4 and 5, which, even though they are slightly thinner in general, have lower spill values than those of Example 3 of high homogeneous permeability. Such a result is counterintuitive.

Although only a few example embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications to the exemplary embodiments are possible without departing materially from the novel teachings and advantages of this invention. Therefore, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the clauses, the more average function claims are intended to cover the structures described here as carrying out the recited function and not only the structural equivalents but also the equivalent structures. Thus even when a nail and a screw may not be structural equivalents in the sense that a nail employs a cylindrical surface to secure the wooden parts together, while a screw employs a helical surface, in the environment of the clamping Wood parts, a nail and a screw can be equivalent structures.

Claims (24)

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

1. An emerging material for personal care products comprises a layered structure of at least one layer of relatively high permeability on an upper side towards a user and at least one relatively low permeability layer, wherein said structure has a capillary tension range between about 1 and 5 centimeters with a differential of at least about 1 centimeter from the top to the bottom.

2. The emergence material as claimed in clause 1 characterized in that said high permeability layer has a permeability of at least 1,000 darcys and said low permeability layer has a permeability of less than 1,000 darcys.

3. The emergence material as claimed in clause 2, characterized in that said high permeability layer has a permeability of at least 250 darcys greater than said low permeability layer.

4. The emergence material as claimed in clause 2, characterized in that said high permeability layer has a permeability of at least 500 darcys greater than said low permeability layer.

5. A personal care product selected from the group consisting of diapers, training pants, absorbent underwear, adult incontinence products, and women's hygiene products comprising the material as claimed in clause 1.

6. The emergence material as claimed in clause 1, characterized in that said high permeability layer is oriented.

7. The emergence material as claimed in clause 1, characterized in that said low permeability layer is oriented.

8. The emergence material as claimed in clause 1, characterized in that said layers of low and high permeability are oriented.

9. The product as claimed in clause 3, characterized in that said product for personal care is a product for the hygiene of women.

10. The product as claimed in clause 3, characterized in that said product for personal care is a product for adult incontinence.

11. The product as claimed in clause 3, characterized in that said product for personal care is a diaper.

12. The diaper as claimed in clause 11, characterized in that it has a crotch width of at least 7.6 centimeters.

13. The emergence material as claimed in clause 2, characterized in that it has a thickness of less than 3 centimeters.

14. The emergence material as claimed in clause 1, characterized in that said first value of spill of insult is at most 30 ml of an insult of 100 ml delivered at 20 ml / second.

15. The emergence material as claimed in clause 14, characterized in that two additional insult spills are at most 30 ml each.

16. The emergence material as claimed in clause 15, characterized in that all three insults have spill values of at most 25 ml.

17. An emergence material for personal care products comprising a layered structure of at least one relatively high permeability layer on one side towards a wearer and at least one relatively low permeability layer, wherein said relatively permeable layer High has a capillary tension range of between about 1 and 2.5 centimeters and said relatively low permeability layer has a capillary tension range of between about 2.5 and 5 centimeters.

18. The emergence material as claimed in clause 17, characterized in that said high permeability layer is oriented.

19. The emergence material as claimed in clause 17, characterized in that said low permeability layer is oriented.

20. The emergence material as claimed in clause 17, characterized in that said low and high permeability layers are oriented.

21. An emergence material for personal care products comprising a layered structure of at least one relatively high permeability layer on one side towards the user and at least one relatively low permeability layer, wherein said relatively permeable layer High is composed of conjugate sheath / core microfibers and has a permeability of at least 500 darcys greater than said low permeability layer and a capillary tension range of between about 1 and 2 centimeters, and said relatively low permeability layer It comprises homopolymer microfibers and has a capillary tension range of between about 2.5 and 5 centimeters, wherein at least one of said layers has an orientation of at least 3: 1 in MD: CD.

22. The emergence material as claimed in clause 21, characterized in that said high permeability layer is oriented.

23. The emergence material as claimed in clause 21, characterized in that said low permeability layer is oriented.

24. The emergence material as claimed in clause 21, characterized in that said high and low permeability layers are oriented. E S U M E N An emergence material for personal care products is provided which comprises a layered structure of at least one layer of relatively high permeability on an upper side towards a user and at least one relatively low permeability layer wherein the structure has a range of capillary tension of between about 1 and 5 centimeters with a capillary difference voltage of at least about 1 centimeter from the top to the bottom. The emergence material should have a high permeability layer with a permeability of at least 1,000 darcys and a low permeability layer with a permeability of less than 1,000 darcys. The emergence material must also have a high permeability layer which has a permeability of at least 250 darcys greater than the low permeability layer. Such a layered structure must have a first insult spill value of at most 30 ml of a 100 ml insult delivered at 20 ml / second. Such emergence material is useful in personal care products such as diapers, training pants, absorbent underwear, adult incontinence products, women's hygiene products and the like.