MXPA99004223A - Multifunctional absorbent material and products made therefrom - Google Patents

Abstract

A multifunctional material is provided for use in personal care products. The multifunctional material has a permeability between 100 and 10000 Darcys and a capillary tension between about 2 and 15 cm. Structures containing this multifunctional material can have a runoff rate of less than 25 ml per 100 ml insult, over its life. The multifunctional material should have between about 30 and 75 weight percent of a slow rate superabsorbent, between 25 and 70 weight percent of pulp and from a positive amount up to about 10 percent of a binder component. The material preferably has a density between about 0.05 and 0.5 g/cc. The material has a liquid pass through function which desorbs a surge material across time frames consistent with user conditions and releases the liquid for distribution to remote storage locations. The material, when combined with the intake and distribution materials, defines a composite structure for use in personal care products.

Description

MULTIFUNCTIONAL ABSORBENT MATERIAL AND PRODUCTS MADE FROM THE SAME FIELD OF THE INVENTION The present invention relates to a material structure and an absorbent article for personal care products such as diapers, training pants, incontinence articles or sanitary napkins.

BACKGROUND OF THE INVENTION Additional absorbent systems for personal care products store substantially all liquid insults in the crotch region. This results in the crotch region being heavily loaded with the liquid of the first insult and may result in insufficient capacity for a second, third or subsequent insult. This loaded crotch area can cause the product to be pushed out of the user, causing discomfort for the user and creating the possibility of runoff. The storage of insults in the crotch region also requires that the crotch region be wider than would be possible for a system to store insults in a different place. A wider crotch area also causes discomfort to the user. In addition, storage in the crotch area does not use the entire product area for storage, resulting in a waste of the absorbent material which is usually scattered throughout the product area. Storage primarily in the crotch area will therefore raise the cost of the product through inefficient use of the materials. A system in which r. insult was accepted by a personal care product and was distributed to remote areas of the product for storage outside the crotch area so that the crotch area of the product could be free to accept another insult would be preferable for the storage design of crotch area. Such a system could maximize the use of the product area, reduce the bagging and allow the production of a personal care product with a narrower and more comfortable crotch. A more efficient use of the product materials can result in a lower cost for the consumer.

It is therefore an object of this invention to provide a multifunctional composite material that can be used in liquid communication with a dispensing material for urine handling applications. Such material will take an insult of liquid from the user, store some of it for a period of time and release a large part of the insult in a controlled manner to a distribution material which will move the liquid to a remote storage location. It is a further object of the invention to provide personal care products with narrow crotch designs.

SYNTHESIS OF THE INVENTION A multifunctional material is provided for use in personal care products. The multifunctional material has a permeability of between about 100 and 10,000 darcis, a capillary tension of between about 2 and 15 centimeters, the structures comprising this multifunctional material can have a running rate of less than 25 ml per 100 ml of insult during his lifetime. The multifunctional material should have between about 30 and 75 percent by weight of a superabsorbent, between 25 and 70 percent by weight of pulp and from a positive amount to about 10 percent of a binder component. The material preferably has a density of between about 0.05 and 0.5 g / cc. The material has a fluid transfer function that accepts the liquid during insults and then desorbs an emerging material through time frames consistent with the user's conditions and releases the liquid for distribution to remote storage locations. The material when combined with the intake and distribution materials defines a composite structure for use in personal care products. Personal care products using this material may have a narrower crotch than previous products due to superior performance of the material.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a cross-sectional side view of a diaper incorporating the multifunctional material of this invention.

Figure 2 is a side view drawing of a cradle used for the MIST evaluation test.

Figure 3 is a graph of the TUE data comparing the material of Example 1 with a commercially available Huggies® Ultratrim® diaper.

Figure 4 is a side view of a diaper assembled in Example 1.

Figure 5 is a graph of the run results for Example 1 (solid line and a Huggies® Supreme® diaper (dotted line).

Figure 6 is a graph illustrating the division of the liquid in the structure of Example 1 after the first insult showing grams of liquid on the y-axis and time on the x-axis. The first bar in each set of three bars indicates the liquid in the sprouting material. The second bar indicates the liquid in the multifunctional material. The third bar indicates the liquid in the distribution material.

Figure 7 is a graph illustrating the division of the liquid in the structure of Example 1, after a second insult using the same designations as in Figure 6.

Figure 8 is a graph illustrating the division of the liquid in the structure of Example 1, after a third insult using the same designations as in Figure 6.

Figure 9 compares a graph of the liquid profile of a system using the material of this invention with a 100 ml insult (dotted line) and after 3 insults of 100 ml (solid line). The distance from the insult site is indicated on the x axis.

DEFINITIONS "Disposable" includes being discarded or discarded after use and not intended to be washed and turned -used.

"Frontal" and "posterior" are used throughout this description to designate the relations relative to the garment itself rather than to suggest any position that the garment assumes when it is placed on a wearer.

"Hydrophilic" describes the fibers or fiber surfaces 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 contact angles and the surface tensions of the liquids and the materials involved. Equipment and techniques suitable for measuring the wettability of particular fiber materials can be provided by the Cahn SFA-222 surface force analyzer system, an essentially equivalent system. When measured with this system, fibers having contact angles of less than 90 ° are designated "wettable" or hydrophilic, while fibers having contact angles equal to or greater than 90 ° are designated "non-wettable" or "hydrophobic".

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

"Longitudinal" and "transverse" have their usual meaning, as indicated by the cross-sectional line x-x in figure x. 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 article is used. The transverse axis lies in the plane of the article generally perpendicular to the longitudinal axis. The article as illustrated is longer in the longitudinal direction than in the transverse direction.

"Particles" refers to any geometric shape such as, but not limited to spherical grains, cylindrical fibers or yarns, flat surfaces or rough surfaces, sheets such as ribbons, ropes, threads or the like.

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

The "spunbonded fibers" refers to fibers of small diameter, which are formed by extruding the melted thermoplastic material as filaments of a plurality of usually circular and thin capillaries of a spinner with the diameter of the filaments extruded then being rapidly reduced as for example, in U.S. Patent No. 4,340,563 issued to Apel et al., and in U.S. Patent No. 3,692,618 issued to Dorschner and others, in the Patent of the United States of America. United States No. 3,802,817 issued to Matsu i and others, in US Pat. Nos. 3,338,992 and 3,341,384 issued to Kinney, in United States Patent No. 3,502,763 issued to Hartman, and in the patent of the United States of America No. 3,542,515 granted to Dobo et al. Spunbonded fibers are generally non-tacky when deposited on a collecting surface. Spunbond fibers are generally continuous and have average diameters (from a sample of at least 10) larger than 7 microns, and more particularly, between 10 and 30 microns. The fibers may also have shapes such as those described in U.S. Patent Nos. 5,277,976 to Hogle et al., U.S. Patent No. 5,466,410 to Hills and 5,069,970 and 5,057,368 to Largman and others, which describe fibers with unconventional shapes.

"Melt blowing fibers" means fibers formed by extruding a melted thermoplastic material through a plurality of capillary vessels, usually circular and thin, such as melted threads or filaments in gas streams with (for example air), usually hot to high speed and converging which attenuate the filaments of the 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. Melt-blown fibers are microfibers which can be continuous or discontinuous, are generally smaller than 1 microns of average diameter and are generally sticky when deposited on a collecting surface.

"Conjugated fibers" refer to fibers which have been formed from at least two extruded polymers from separate extruders but which are spun together to form a fiber. Conjugated fibers are also sometimes referred to as multicomponent or bicomponent fibers. The polymers are usually different from one another even though the conjugated fibers can be monocomponent fibers. The polymers are arranged in distinct zones placed essentially constantly across the cross section of the conjugate fibers and extend continuously along the length of the conjugate fibers. The configuration of such a conjugate fiber can be, for example, a sheath / 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 Caneco et al., In U.S. Patent No. 5,336,552 issued to Strack et al., And in U.S. Pat. North America No. 5,382,400 issued to Pike et al. For two component fibers, the polymers can be present in proportions of 75/25 50/50, 25/75 or any other desired proportions. The fibers may also have forms such as those described in U.S. Patent No. 5,277,976 to Hogle et al. And 5,069,970 and 5,057,368 to Largman et al., And incorporated herein by reference in their entirety which describe fibers with unconventional ways.

The "biconstituent fibers" refer to fibers which 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, forming instead of these usually fibers or protofibrils which start and end at random. Biconstituent fibers are sometimes also referred to as multi-constituent fibers. Fibers of this general type are discussed in, for example, United States Patent No. 5,108,827 issued to Gessner. Bicomponent and biconstituent fibers are also discussed in the text "Mixtures and Compounds of Polymers" by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenum Press, a division of Plenurr. Publishing Corporation of New York, IBSN 0-306-30831-2, pages 273 to 277.

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

"Air placement" is a very familiar process by which a fibrous nonwoven 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 assistance of a vacuum supply. The randomly deposited fibers are then bonded together using, for example, hot air or a sprayed adhesive.

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

TEST METHODS Absorption Time Index (ATI): In this test the absorptive capacity of a superabsorbent material is determined against time by up to 200 minutes under a light pressure, for example, of about 0.01 psi.

A 25.4 millimeter inner diameter cylinder with a 100 mesh integral stainless steel grid on one end was used to contain 0.16 ± 0.005 grams of dry superabsorbent. The superabsorbent should be placed carefully in the cylinder so that the superabsorbent does not stick to the sides of the cylinder. The cylinder should be gently tapped to evenly distribute the superabsorbent over the grid. A plastic piston of 0.995 inches in diameter (252.73 millimeters mm) and 4.4 grams was then placed in the cylinder and the cylinder, the piston and the superabsorbent were assembled together. The assembly is placed in a 76.4 millimeter by 76.4 millimeter liquid container having a salt water solution of 0.875 percent by weight NaCl. Strike the cylinder gently to remove any air trapped under it and maintain the depth of salt water to one centimeter through the test.

Use a stopwatch capable of reading 200 minutes at one second intervals. Start the chronization and after 5 minutes in the solution, remove the assembly and dry on an absorbent paper. A preferred role is that of Kleenex® Premium dinner towels from Kimberly-Clark Corporation even when any other effective paper can be used. When drying with a blotter, press the paper lightly against the cylinder to ensure good contact. Touch the cylinder 3 times with the dry paper and there should be very little liquid removed the third time. Start the assembly and return the assembly to the liquid container. Drying and weighing should take about 5 seconds and the timer should be kept running through the test. Take readings at 5, 10, 15, 20, 30, 45, 60, 75, 90, 120, 160 and 200 minutes. Use fresh dry napkins for each reading.

After the final reading, calculate the grams of liquid absorbed per gram of superabsorbent. The amount of liquid absorbed at particular times divided by the amount absorbed at 200 minutes can be plotted against time for a graphical representation of the absorption rate.

The ATI was calculated as follows: ATI = (t10 + t20 + t30 + t40 + t50 + t60 + t70 + t80 + t90) / 9 where tn is the time in minutes to which a percentage of the absorbent capacity was used at 200 minutes, t30 is the time in which 30 percent of the total capacity is used.

Tension Absorption Test (AUT): This test is a modified version of the TAPPI T561pm-96 method which is entitled "absorption rate and capacity of absorbent paper products using gravimetric principles". Appendix A2 of the TAPPI T561pm-96 method discusses non-standard variations.

A specimen of the sample is placed on a horizontal test plate so that its bottom surface rests on the plate and its top surface is covered by the test weight. The sample is surrounded by a constraint so that it can only expand in one direction. The direction covered by the weight. The test plate is connected to a liquid reservoir by means of a siphon tube. The specimen is in contact with the effluent (salty solution of 8.5 g / 1) of the siphon tube and the upper surface of the liquid reservoir in relation to the sample can be adjusted during the test. The liquid reservoir is placed on a suitable weighing device. During the test, the liquid is absorbed into the specimen and this absorption causes a reduction of the liquid present in the liquid reservoir which can be measured by the weighing device.

The decrease in weight in the liquid reservoir can be drawn directly and divided by the grams of the sample to provide an absorbent capacity per gram of sample over time.

In the test procedure used here, the sample was 6.25 centimeters in diameter and the weight of the sample depends on the density of the sample. The sample was surrounded by a round glass ring 6.25 centimeters in diameter to horizontally restrict its expansion. The test weight was 664.14 grams in order to maintain a pressure of about 0.25 psi on the sample. The height difference of the liquid reservoir and the sample was maintained at zero centimeters.

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, a height of 19 centimeters, an internal distance between the upper arms of 30.5 centimeters and a angle between the upper arms of 60 degrees. The crib has a 6.5 mm wide slot at the lowest point running at the length of the crib on 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 a salty water solution of 8.5 grams of sodium chloride per liter, at a rate of 20 cc / sec with a normal nozzle at the center of the material and a quarter of an inch ( 6.4 mm) above the material. The amount of spill is recorded. The material is removed immediately from the crib, weighed and placed on a dry 40/60 pulp / superabsorbent pad having a density of 0.2 g / cc in a horizontal position under a pressure of 0.01 psi and being weighed after 5 , 15 and 30 minutes to determine the desorption of the liquid from the material inside the superabsorbent pad as well as the retention of the liquid in the material. The pulp fluff and superabsorbent used in this test is Kimberly-Clark pulp (Dallas, Texas) CR-2054 and FAVOR 870 superabsorbent from Stockhausen Company (of Greensboro, North Carolina 27406) even though other superabsorbents and comparable pulps may be used. provided that they give a desorption pad of 500 grams per square meter and 0.2 g / cc which after immersion in the salt water solution under conditions of free inflation for 5 minutes, retains at least 20 grams of water solution salt per gram of desorption pad after having been subjected to the air pressure difference, by vacuum suction, for example, of about 3.45 kPa applied 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 the liquid between them and they are reassembled after each weighing and are placed again on the fluff / superabsorbent . The test is repeated using fresh desorption pads on each insult so that a total of 3 insults are entered and the division of the liquid is measured for 1.5 hours with 30 minutes between the insults. Five tests of each sample material are recommended.

X-Ray Image Test: This test was a method used to determine the amount of liquid in each of the five zones of the absorbent systems. The X-ray image is known in the art as discussed, for example, in an article entitled "Liquid distribution: comparison of X-ray image data" by David F. Ring, Osacar Lijap and Joseph Pasente, in the journal World of Nonwovens, summer 1995, pages 65-70. Generally this procedure compares the X-ray images of a wet and dry sample in order to calculate the liquid content. Such X-ray systems are available from Trionics Inc., of 31 Business Park Drive, Branford, CT 06045 as model no. 101561 HF 100 / annex. This system employs the Optumus Inc computer program. , from Ft. Collins, CO as Bio-scan Optimate5 S / N OPM4101105461 version 4.11.

Capillary Tension: The capillary tension (ct) expressed in centimeters (cm) of the liquid was calculated from the characteristics of the fiber and the fabric by equalizing the capillary pressure exerted by the material with the hydrostatic pressure provided by a column of liquid per a method known in the art and taught in a reference number, for example, "Textile Science and Technology", volume 7, by Pronoy K. Chatterjee, published by Elsevier Science Publishers BV 1985 ISBN 0-444-42377-X (volume 7), chapters 2,4,5. These calculations assume a surface tension of 68 dynes / centimeter which is taken from a saline solution of 8.5 gm / 1 used as an approximation or simulation of the urine. Urine can be quite variable in surface tension.

The capillary tension can be computed or determined experimentally by means of the vertical transmission height test described here, the computations are used in the presence of test liquids, especially materials containing superabsorbents when exposed to salt water.

Variable Dimensions cm salt water a _ v * *, -? co s < 0) cm2 / g r. r A Pproro g / cm3 cela - - BW g / cm3 105 / cm SA, for large cylinders (c) 4 pd.L 4x10 * 4pd¿ for spheres r, rf (c) - 3 8 = _ 6 10 * where Y = liquid surface tension (dina / cm) 0X = liquid-solid contact angle of advance (degrees) for component i ir = 3.1415906 pteía = fabric density (g / cm3 pprom = average heavy component density of mass (g / cm3) di = diameter of component i (microns) px = density of component i (g / cm3) xA = fraction of mass of component i in the fabric rlßf £ = effective fiber radius (cm) BW weight of sample / area (g / m2) t = sample thickness (mm) under 0.05 psi (23.9dine / cm2) or 2.39 Pascal (N / m2) load L = cylinder length (cm) V ± = volume of component i (cm3) SAi = surface area of component i (cm2) Calculation of Example of Capillary Tension For a structure which contains 57 porcientc of soft southern wood pulp, 40 percent of superabsorbent and 3 percent of binder fiber, and has a basis weight of 617.58 g / m2 and a volume thickness of 5.97 mm to 0.05 psi, the Example calculation of saltwater capillary tension follows.

The component properties are as follows: Component Shape Diameter cL_ Density Anglepj Fraction (micras) Contactofi (g / cm3) of Mass xs Soft Wood So. Cylinder 13.3 45 1.55 0.57 Super Absorber Sphere 1125 30 1.49 0.40 Fiber Cylinder 17.5 90 0.91 0.03 Binder Note that the shape and contact angles are approximate.

Variable orícm g) = S Xj eos (0) aícrrrVg) - 0-S7cos (43) 0.40cos (30) 0.03 cosí 90) or (cm2 / g) = 794.5 pprom = (\ S Xj) / _1 -1 Pproß = (0.57 + 0.40 + 0.03 1.55 1.49 0.925 Pproo (g / cmJ) = 1.496 p eia (g / cm3) = B W 103t ptßiaíg / cm ») = 617.58 (5.97) 103 pteia (g / cm3) = 0.1034 c.t. (cm salt water) »_2_ f? ^ -. ^ - \ o c.t. (cm salt water) = _2_ 68 794.5 (-! - ') 980 0.1034 \ A96 c.t. (cm salt water) = 6.91 Permeability: The permeability (k) can be calculated from the Kozeny-Carman equation. This is a widely used method. References include an article by R.W. de Hoyland and R. Field in the newspaper "Tecnología y Industria del Papel", December 1976, p. 291-299 and "Transportation of Porous Liquid Medium and Poro Structure" of F.A.L. Dullien, 1979, Academic Press Inc., ISBN 0-12-223650-5.

Variable Equation Dimensions Calculable Permeability = 1 Darcys KS, 2 (l-e) 2 9.87 x W Constant K _ 3.5eJ - e) J] sin (1 - e) * i [l + 57 (l Kozeny dimension Area = Surface area by material mass Mass Average Pprom heavy -ter g / cm3 Area = Sv Ppro cm * Surface area of component density per solid volume of material Porosity = no dimension Fiber radius = cm SA. effective Density = pcela _ BW g / cm3 10J t cloth pd.2L For cylinders = long For spheres = where dx «diameter of conponence. sil ras Pi > coaqponent density i g CT '. Xx »fraction of ta =» of compor.er.ee i er. -s a »weight of sample BW (g / m ') - thickness of rr esrara irruí) b jo CCS psi (23.9 dine / ctr."' or 2.39 Paacal (N / a1; load Permeability Example Calculation For a structure which contains 57% southern softwood pulp, 40% superabsorbent and 3% binder fiber and has a basis weight of 617.58 g / m2 and a volume thickness of 5.97 millimeters at 0.05 psi the permeability calculation example follows.

The properties of the component are as follows (note the approximate form): Component Shape Diameter Density Fraction dx x Mass x1 (microns) (g / cm3) Soft wood Cylinder 13.3 1.55 0.57 south Superabsorbent Sphere 1125 1.50 0.40 Binder Cylinder 17.5 0.925 0.03 . 617.58 pteia (g / cm3) (5.97) 10 'pteia (g / cm3) = 0.1034 P¡ 0.1034 0.1034 _.0.1034 e -057- -0.40- -0.0 ^ = 0.9309 Sv (cm "/ g) ß? Frfí. pProm (g / cm3) »1,496 S0 (cnf1) sSvP «», S0 (cm '= 1194 X 1,496 S0 (cm "1) = 1786 = 3.5eJ K .Ji-rIl +, w ..). | K = 10.94 e3 1 k KS, 2 (l-e > - 9.87 x 10 ' k (0.9309) * 1 (10.94) (i786) * (l-0.9309) 2 9.87 x 10 »k = 491 darcys Material Caliber (Thickness). The caliber of a material is a measure of thickness and is measured at 0.05 psi by 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 will be evaluated and averaged with respect to the density values.

Transmission Time and Vertical Fluid Flow of an Absorbing Structure. A strip of sample material of approximately 5 centimeters by 38 centimeters 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 touch just above the surface of the liquid. The liquid used was a saltwater solution of 8.5 g / 1. Relative humidity should be maintained at around 90 to about 98% during the evaluation. The sample strip was placed above the known weight and volume of the liquid and a timing was 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 height of the front of the liquid against time was put in outline 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 Flux Value of the Strip Sample at a particular height was calculated by dividing the grams of liquid absorbed by the sample strip by each of: the basis weight (gsm) of the sample strip; the time, er. minutes, which is necessary for the liquid to reach the particular height; and the width, in inches, of the sample strip. Capillary tension in materials not containing superabsorbents (eg emergence materials) was measured simply by the equilibrium vertical transmission height of a saltwater solution of 8.5 g / 1 after 30 minutes.

DETAILED DESCRIPTION OF THE INVENTION Previous attempts to improve the effectiveness of disposable personal care products have included distributing the particles of lint or superabsorbent material (sam) in particular areas of the article or providing differently shaped retaining or storage areas in which the liner particles can be used. insults are absorbed before absorption by the absorbent core. Such methods do not generally use the entire available interior surface of the product or use it in the same degree, thereby resulting in inefficient use of the body of the product article.

Previous attempts also turned out er. structures in which the liquid to be absorbed remains in the crotch area of the article. A structure thus taught should be very wide in the crotch region and therefore not comfortable for the user, particularly after absorbing the liquid by the absorbent core and the subsequent swelling of the absorbent material. Storage in the crotch region also increases the tendency of the product to be bagged out of the user's body.

There is therefore a need for a disposable personal care product in which a large part of the available area of the article is used for the absorbency of the liquid insults of the body and which does not retain the volume of the insult in the area of crotch. This will allow articles to be produced that conform more to the body with a narrower crotch and therefore result in a better fit and greater user comfort, and a more efficient use of materials. When referring to diapers and training pants, a narrow crotch is one which is at most 7.6 centimeters wide, more particularly at least 5 centimeters wide.

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

The emergence control materials, the "S" in SC, are provided to quickly accept the incoming insult 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 typically must be capable of handling an incoming insult of between about 60 and 100 cc at a volumetric flow rate of from about 5 to 20 cc / c, for infants, for example.

The containment or retention materials, the "C" in SC, must absorb the insult quickly and efficiently. These must be able to absorb the liquid without a significant "gel block" or a liquid penetration block further inside the absorbent by the expansion of the outer layers of the absorbent. The retention materials are also frequently superabsorbent materials of higher rates such as blends of polyacrylate superabsorbent and fluff. These materials absorb and quickly retain the liquid. Examples of retention materials can be found in commonly assigned United States Patent No. 5,350,370 to Jackson et al.

As mentioned above, traditional absorbent systems having the grasping and holding functions usually retain the vast majority of any insult in the target area, usually the crotch area. The liquid is moved out of the crotch in such systems only after the crotch capacity is filled. This results in products for personal care, having crotches which are very wide. Examples of the retaining ability and the location of the containment of the various commercial diapers are presented in Table 3 of the United States Patent Application No. filed the same day and assigned to the same assignee of this application. entitled "Absorbent Articles with Controllable Filling Patterns".

In contrast to traditional absorbent systems, the patent application of "Absorbent Articles with Controllable Filling 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 pre-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 liquid located in the area of central target, usually in the crotch, to each of the two end zones that is less than 5: 1 after three insults of 100 ml separated by 30 minutes. It is preferred that this filling rate be less than 3: 1, and more preferably that it be less than 2.5: 1. Many diapers currently commercially available have filling ratios of 20: 1, 50: 1, or even larger, for example these retain most of the liquid insult in the crotch.

In addition to the materials of emergence control and containment in traditional absorbent systems, recent work has introduced another component interposed between layers S and C. This new components a distribution material, producing a system with a control of emergence distribution and containment or "SDC".

The distribution materials, the "D" in SDC, must be able to move the liquid 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. By "ready for the next insult" it means that enough liquid has moved out of the target area so that the next insult results in the absorption of the liquid and the spill within acceptable volumes. The time between insults can vary from just a few minutes to hours generally depending on the age of the user.The multifunctional material of this invention is located between the emergence material and the distribution material as shown in Figure 1, which is a cross-sectional view of a personal care product, in this case a diaper. The diaper 1 has the emergence material 2 in the collection area, the multifunctional material 3 below the emergence material 2, the distribution material 4 under the multifunctional material 3 and the retention / storage material 5, 6 at either end of the material. diaper 1. Such products usually have a lining material and a backing sheet (not shown for clarity). While it may seem obvious, it should be noted that in order to function effectively, the materials used in this invention must have sufficient contact to transfer the liquid therebetween.

The lining is sometimes referred to as a lining on the side of the body or upper sheet and is adjacent to the emergence material. 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 fluids maintained in the superabsorbent and must be docile, soft-feeling and irritating. The diaper 1 has the emergence material 2 in the collection area, the multifunctional material 3 below the emergence material 2, the distribution material 4 below the multifunctional material 3 and the retention / storage material 5,6 at either end of the material. diaper 1. Such products as well. They usually have a liner material and a backing sheet < r. shown for clarity). While it may seem obvious, it should be noted that in order for them to function effectively, the materials used in this invention must have sufficient contact for liquid transfer therebetween.

The liner is sometimes referred to as a liner on the side of the body or top sheet and is adjacent to the emergence material. 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 user's skin from liquids maintained in an absorbent structure and must be docile, soft feeling and non-irritating.

Various materials may be used in forming 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 to be particularly suitable for use in the formation of the side-to-body liner, including fabrics spunbonded or meltblown from polyolefin filaments, polyester, polyamide (or other type-forming polymer). fiber) or bonded carded fabrics of natural polymers (e.g., rayon or cotton fibers) and / or synthetic polymer fibers (e.g., polyester polypropylene). For example, the side-to-body liner may be a fabric bonded by non-woven yarn of synthetic polypropylene filaments. The non-woven fabric can have a basis weight ranging from about 10.0 grams per square meter (gsm) to about 68.0 gsm, and more particularly from about 14.0 grams per square meter to about 42.0 grams per square meter, a volume or thickness varying from about 0.13 millimeters (mm) to about 1.0 mm, and more particularly from about 0.18 mm to about 0.55 mm 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 Darcy to about 5000 Darcy. The non-woven fabric can be treated on the surface with a selected amount of surfactant such as about 0.28% Triton X-102 surfactant, or otherwise processed to impart the desired level of wettability and hydrophilicity. If a surfactant is used, it can be applied to the fabric by any convenient means, such as spraying, printing, brush coating and the like.

The emergence layer is more typically interposed between and in intimate liquid communication contact with the body-side liner and another layer such as a distribution or retention layer, even though in this invention it is in contact with the multifunctional material of the invention. The emergence layer is usually below the inner (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. Such suitable conventional clamping techniques may be used, including without limitation, bonding with adhesive (using solvent-based adhesives, and thermally activated, water-based adhesives), thermal bonding, ultrasonic bonding, perforation and bolt 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 of bonding, without excessively restricting the flow of liquid from the liner to the layer of adhesive. emergence. An example emergence material can be found in the patent application of the United States of America No., filed the same day and assigned to the same assignee of this application and entitled HIGHLY EFFICIENT SURFING MATERIAL FOR ABSORBING ARTICLES, which presents a material of emergence which is a fabric of wettable fibers of 30 microns in diameter or less which is essentially uniform and where the fabric has a permeability of between about 250 and 1500 Darcys and a capillary tension of between 1.5 and 5 cm.

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 bonded fabric blown by melting or joined by spinning polyolefin filaments. Such woven r.c. fabric layers may include conjugated, 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 bonded carded fabric can, for example, be a carded fabric bonded with powder, a carded fabric joined by infrared or a carded fabric bonded through air. The attached carded fabrics may optionally include a mixture or combination of different fibers, and the fiber lengths within a selected fabric may vary from about 3 mm to about 60 mm. The example sprouting layers can have 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 to one square inch. pressure of 68.9 Paséales, a volume of at least about 1.0 mm at a pressure of 68.5 Paséales, a volume recovery of at least about 75 percent, a permeability of around 500 to around 5000 Darcy, and a surface area per hollow volume of at least about 20 square centimeters per cubic centimeter. The emergence layer may be composed of an essentially hydrophobic material, and the hydrophobic material may optionally be treated with a surfactant or otherwise processed to impart the desired level of wettability and hydrophilicity. The emergence layer can have a generally uniform thickness and a cross-sectional area.

The distribution layer may be able to move the liquid from the initial deposit point to where storage is desired. The distribution must take place at an acceptable rate so that the target's insult area usually the crotch area, be ready for the next insult. The time between insults can vary from just just a few minutes to hours, usually depending on the age of the user. In order to achieve the transportation function, a distribution layer must have a high capillary tension value. The capillary tension in the distribution and other materials not containing absorbents is measured simply by the equilibrium vertical transmission height of a saltwater solution of 8.5 g / 1 according to the vertical liquid flow rate test, not by the Test method given for materials containing superabsorbents. A successful distribution layer must have a capillary tension greater than that of the adjacent material from which it receives the liquid (on the side towards the user) and preferably a capillary tension of at least about 15 cm. 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 which exhibits a vertical liquid flow rate at a height of about 15 centimeters, adequate of at least about 0.002 grams of liquid per minute per square meter. (gsm) of distribution material per inch width in cross section of the distribution material g / (min * gsm * inch) to about 0. 1 g / (min * gsm * inch). As used here, the Rate value of Vertical Liquid Flow of a distribution material is meant to represent the amount of liquid transported through a limit by a specified vertical distance outward from insult location of the centralized liquid per minute per standardized amount of the distribution material. The vertical liquid flow rate, at a height of about 15 centimeters from a distribution can be measured according to the test method described here.

Another desired liquid transport property of a suitable distribution material than that exhibiting a vertical liquid flow rate, at a height of about 5 centimeters, suitably of at least about 0.01 g (min * gsm / inch) ) 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, foams and filamentary materials. For example, the distribution layer may be a nonwoven fabric layer composed of polyolefin, polyester, polyamide (or other fabric forming polymer) filaments. Such nonwoven fabric layers may include conjugated, 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 gsm, or more preferably from 80 to 200 gsm, a density of between about 0.08 and 0.5 g / cc, and a permeability of between about 50 and 1000 Darcys.

The backing sheet is sometimes referred to as the outer cover and is located as 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 an absorbent structure from wetting or soiling the user's clothes, the sheets or bedding or other materials that make contact with the diaper. The outer cover can be, for example, a polyethylene film having an initial thickness of from about 0.5 mil (0.012 millimeters) to about 5.0 mil (0.12 millimeters). The outer cover of polymer film can be etched and / or matte finished 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 laminates formed of a woven or non-woven fabric and thermoplastic film. The outer cover can optionally be composed of a "breathable" microporous, permeable to vapor or gas material, which is permeable to vapors or gas but is 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 particles of 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 multifunctional material of this invention is located on one side of the emergence material and between the emergence material and the distribution material and accepts and retains much of the liquid of an insult until the distribution material can move the liquid out of the zone. of taking. The basic structure of the multifunctional material of this invention is a unique combination of a superabsorbent material, preferably a slow rate superabsorbent, with a high volume wet elastic pulp, and a structure stabilizing component, such as a binder fiber. of polyolefin in a composite structure.

By "slow rate" superabsorbent what is meant is a superabsorbent having an absorption time index (ATI) of at least 5 minutes and preferably more than 10 minutes. Adjustment of the absorbency rate of a superabsorbent can be achieved by modifications to particle size, surface properties and polymer chemistry. Note that even though the slow-rate superabsorbents are preferred and are mentioned here, a mixture of slow-rate and conventional superabsorbents may also be used, provided that the permeability and capillary tension of the multifunctional material are within the required ranges as set forth herein. .

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 liquid emergence material during and any subsequent insults; 3) by allowing a part of the insult volume to pass through itself (the multifunctional material) during the insult to the distribution material and 4) by permanently absorbing a part of the insult from the liquid. The multifunctional material must carry out these functions despite the pressures of actual use and despite the serious effects caused by the user's movement.

During and after the insult, the multifunctional material described herein accepts the excess liquid retained in the emergence material and releases a defined portion of liquid to the distribution material for movement to the final storage locations. The multifunctional material provides permanent storage for a part of the liquid, but the advantages of volume and product filling will be achieved only if a relatively small part of the liquid is finally stored in the multifunctional material in the target insult area. Improvements in product performance will be achieved if that liquid stored in the multifunctional material in the target insult zone does not decrease the other three functions provided by the multifunctional material. All these functions must continue through multiple insults, requiring a degeneration of the internal hollow volume in the multifunctional material while maintaining the appropriate interactions with the intake and distribution materials. A method to illustrate the absorption of the multifunctional material of this invention is the test according to the AUT test and compares its absorbency with other known absorbers. Figure 3 shows the result of the AUT test of the material of Example 1 given below, and the absorbent material taken from a commercially available Huggies® Ultratrim® diaper. The Ultratrim® diaper contained 32 percent FAVOR 880 superabsorbent from Stockhausen and 68 percent southern softwood pulp and had a density of 0.183 g / cc and a base weight of 814 gsm. Figure 3 clearly showed that the material of Example 1 did not absorb an insult as quickly as the Ultratrim® diaper, thus allowing the liquid to remain available and pass to a distribution component for eventual storage elsewhere.

The overall intake rate of the multifunctional material, and the ability to allow some liquid to pass immediately through to the distribution component is controlled by the permeability of the multifunctional material and the capillary tension in relation to the materials in which the multifunctional material It is in liquid contact. More particularly, the permeability of the multifunctional material must be greater than 100 Darcys or more preferably greater than 250 Darcys. The superior binding of the permeability of the multifunctional material is most likely around 10,000 Darcye. The capillary tension of the multifunctional material must be greater than that of the emergence and less than that of the distribution material in order to move the liquid through the multifunctional material. Since emergence materials generally have capillary stresses below 2 cm and the distribution materials generally have capillary stresses above 15 cm, it is preferred that the multifunctional material have a capillary tension which varies from about 2 to about 15 centimeters during the life of the system. In the initial dry state, the multifunctional material of Example 1, for example, has a permeability of 490 Darcys and a capillary tension of 5.7 cm. Note that the capillary tension for superabsorbent-containing materials is calculated by the method given in the test methods section, and not by the equilibrium transmission.

In relation to the permeability, it is believed that when swelling the slow superabsorbent, the caliber of the multifunctional material increases and the geometric arrangement of the superabsorbent particles and fibers opens the structure maintaining an adequate permeability to provide the function of taking / transferring in the subsequent insults. Once the superabsorbent particles swell and the thickness of the material increases, by assuming that the aggregate liquid resides within the swollen superabsorbent articles after an equilibrium time of 30 minutes and measuring the thickness and wetted area, one can calculate the fractions of mass of the components, the particle diameter and the density, the porosity of the fabric, the permeability, and the capillary tension according to the test methods for any level of fabric saturation. In addition to maintaining adequate permeability for rapid liquid intake, the particle and fiber arrangement provides adequate void volume through multiple insults.

The capillary tension is important because it is believed that the temporary retention function and the ability to desorb the emergence material are controlled by the interstitial capillary matrix surrounding the superabsorbent. The liquid must be maintained in the capillary flutes created by the interstitial matrix at a capillary tension that is sufficiently high so that the liquid can be maintained and not released when the product suddenly undergoes changes of position. In addition, the capillary tension level of the multifunctional material must remain above the capillary tension level of the emergence material during the life of the system or product in such a way that desorption of the emergence material occurs and so that the residual liquid is not available for re-wetting the emergence material from the multifunctional material.

In addition to removing the liquid from the emergence material, the multifunctional material must release the liquid to the distribution material. The release of the liquid from the multifunctional material to the distribution material for subsequent permanent storage elsewhere is effected by a competition between the liquid absorption rate of the superabsorbent and the rate of transmission or capillary transfer to the underlying distribution material that they are both pulling liquid out of the fibrous matrix that surrounds the superabsorbent particles. If those rates are roughly matched, the amount of liquid that is released to the distribution layer will be about the same as the amount that is stored in the multifunctional material. If the rates are not balanced, the liquid placement changes. For example, if the absorber absorbs more quickly than the distribution material transmits, more liquid will be permanently stored in the multifunctional material. These competitive transfer rates make the difference in capillary tension between the multifunctional material and the distribution material very important to ensure the desired division of the liquid. Maintaining a sufficiently low capillary tension in the multifunctional material is therefore very important. The nature of the absorbent as well as that of the fibrous matrix between both affects the capillarity of the multifunctional material. It is important that the fibers of the matrix do not fold towards each other when the structure is wetted. The inclusion of fibers with binder and / or high wet modulus components will help to prevent such collapse and thus help to maintain acceptable capillarity. Capillarity is also related to the size of the superabsorbent and to the shape, because in the case of particles, for example, large particles cause a faster fall in capillarity after an insult than small particles do when swell. The functionality of the multifunctional material is therefore related to the size and shape of the superabsorbent and to the swelling speed. The rate of swelling in turn is influenced by the composition and chemistry of the superabsorbent. The surface properties, for example, the effect of any surface treatments, on shape and size. The superabsorbents are available in a variety of sizes and shapes such as beads, particles, foams, films and fibers. As a result of this, since a preferred range of the superabsorbent content of the multifunctional material is given here now, it should be remembered that the content of the superabsorbent above these ranges can also work if the capillary and permeability requirements are filled during its lifetime.

Another factor that can greatly affect multifunctional material is the spill rate for an insult.

The spill rate is very important in personal care products such as diapers since liquids not absorbed by the product will be free to escape from the product to dirty the user's clothes or sheets. The spill rate of the multifunctional material will be influenced by the capillarity of the multifunctional material among other factors, in the sense that a low capillary tension causes the liquid to enter the multifunctional material more slowly. The run rates for the structures containing the multifunctional material of this invention are below 25 ml for each 100 ml of insult for three insults separated by 30 minutes using a sample size as given in the examples.

While it may seem obvious, it should be noted that in order to function effectively, the materials used in the invention must have sufficient contact to transfer the liquid therebetween.

The multifunctional material must be mechanically stable in order to survive the conditions of dry and wet use. The integrity of the high superabsorbent containing compounds can be provided by the small amounts of thermally activated conjugated binder fiber, for example, or by any other suitable means such as biconstituent fibers, liquid adhesives or heat activated film adhesives. . Exemplary binder fibers include conjugated fibers of polyolefins and / or polyamides, and homopolymer microfibers such as polypropylene fibers blown by melting in a coform with the other ingredients to physically entangle them and / or bond them adhesively.

As mentioned above, the basic structure of the multifunctional material of this invention 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 10000 Darcys, a capillary tension of between about 2 and 15 cm. The Structurec comprises an emergence and distribution material as well as the multifunctional material of this invention has 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 separated by 30 minutes, for the purpose of this invention.

In order to achieve the required capillary tension and permeability it is preferred that the multifunctional material of this invention have between 30 and 75 percent by weight of slow rate superabsorbent, between 25 and 70 percent by weight of pulp and from a positive amount up to about 10 percent of a binder component. More particularly, the multifunctional material of this invention should have between 35 and 60 percent by weight of slow rate superabsorbent, between 40 and 65 percent by weight of pulp and between about 1 and 7 percent of a binder component. Even more particularly, the multifunctional material of this invention should have 40 and 55 weight percent slow rate superabsorbent between 45 and 60 weight percent pulp and between about 2 and 5 weight percent of a binder component. Even when not required, high wetting module pulps are especially desirable. 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 it should generally be between about 200 and 700 gsm.

The multifunctional material can be made in a composite structure of the type used in personal care products by the addition of an emergence material adjacent to one side and a distribution material adjacent to the other side. It is important, of course, that any emergence material used with the multifunctional material allows the liquid to pass to the multifunctional material and / or rapidly release the liquid to the multifunctional material. The composite structure can also include a retention material on one side of the dispensing material so that the dispensing material moves the liquid from the multifunctional material to the retention material.

In the examples that follow the component properties used in the calculations for permeability and capillary tension were as follows: Component Shape Diameter (mm) Density Angle (q / cm3) Contact pulp CR 1654 Cylinder 13.3 30 1.55 pulp CR 2054 Cylinder 13.3 30 1.55 HBAFF Cylinder 13.3 45 1.55 Kymene treated Cylinder 13.3 60 CR1654 O 2054 X AFA-126-15 * Sphere 1125 90 1.49 Favor 880 Sphere 450 30 1.49 2 denier PE / PP Cylinder 17.5 90 0.925 binder Dana lon fiber Note that the shape and contact angles are approximate.

* The polyacrylate account XL ARA-126 -15 is from Dow Chemical Company, of Midland, Michigan, 48674.

Example 1 In this example, the multifunctional material consists of about 40 percent by weight of slow-acting superabsorbent, about 57 percent by weight of free-flowing high-volume additive formaldehyde Weyerhaeuser (HBAFF), and about 3 percent by weight. Weight of conjugate binder core / polyethylene sheath / polypropylene (PE / PP) two denier short cut Danaklon.

The slow rate superabsorbent used was a polymerized polyacrylate suspension count of 850 to 1400 microns from the Dow Chemical Company of Midland, Michigan, designated XL AFA-126-15. The slow rate was achieved by particle size, surface properties and chemistry.

The high-volume additive pulp used was cross-linked pulp fiber with an improved wetted module commercially available from Weyerhaeuser Paper Company, under the designation HBAFF. The pulp fibers are mechanically treated to impart a twist and a contoured nature to the fiber. The chemical treatment sets in this curling and twisting, in addition to imparting an added dry and wet stiffness and fiber elasticity. The stiffened pulp fiber was combined with the binding fibers in a fibrillable pulp sheet. The binder fibers were from Danaklon a / s located in Engdraget 22, KD-6800 Varde, Denmark, and where the PE / PP conjugate core fibers of 2 deniers were cut into 6 mm sections.

The multifunctional material was formed by air using a laboratory hand sheet former to achieve an intermixed structure with a basis weight of 620 grams / square meter (gsm). The structure was stabilized in a heated and constricted press operating at about 150 ° C for 1 minute to activate the binder fiber and achieve a target density of about 0.1 g / cc. Any other satisfactory process known to those skilled in the art can be used to produce the material.

In addition to the multifunctional material, two other materials were included in the functional test to demonstrate complete composite performance.

The first material was an emergence layer of nonwoven fabric which was 90 percent by weight of polyethylene sheath / polyethylene core / 3 denier polyethylene terephthalate and 10 percent by weight rayon fiber 1.5 denier The fibers of the emergence layer were carded and thermally bonded at about 270oF (132oc) to achieve a density of about 0.045 g / cc and a basis weight of about 100 gsm The permeability of the emergence material was 1600 Darcys and had a capillary tension of about 1.5 to 2 cm as measured by vertical transmission.

The emergence structure was a 2 inch by 6 inch (5 cm x 15 cm) sample which was layered to provide 100 ml of an accessible hollow volume. Note that the test samples contained approximately 150 cc of total volume calculated by multiplying length times width times thickness. The test configuration, however, resulted in less than 10.2 cm of the total accessible and usable length for insults resulting in approximately 100 cc of accessible hollow volume. It has been empirically found that the samples in the MIST test cradle used about 2 inches in length on each side of the insult point, or 4 inches (10.2 cm), not the full sample length, which results in the 100 cc calculated from hollow volume.

The second material was a distribution layer which was a wet-laid pulp structure of 200 gsrr. with around a density of 0.17 g / cc. The permeability of the distribution material was around 50 to 100 Darcys and the capillary tension was greater than 15 cm as measured by vertical transmission.

The three materials were placed together in a width of two inches (5 cm) for a functional test simulating a narrow crotch design in the order of emergence, multifunctional and distribution materials. A side view is shown in Figure 4 which shows the emergence layer 7, the multifunctional material 8 and the distribution layer 9. The three components were placed in an acrylic cradle to simulate the curvature of a user's body, such as an infant, and they were tested according to the MIST evaluation test. The three components, with the emergence part above, were insulted with a salt water solution of 100 ml of 8.5 grams / liter at 20 cc / second with a normal nozzle at the center of the emergence material. The amount of spill was recorded. The three components were removed immediately from the cradle and weighed individually to determine the division of the liquid between them. After weighing, they were reassembled and placed on a 40/60 lint / superabsorbent pad in a horizontal position. The pressure was applied at 0.01 pounds per square inch over the atmospheric pressure, and the materials were removed from this configuration after 5 minutes, 15 minutes and 30 minutes and separated to weigh each material individually to determine the division of the liquid through this time frame. The samples were reassembled in the same order after each weighing and were put back in the crib to again simulate the curvature of the body. This test was repeated so that a total of three insults were introduced and the liquid divisions were measured over 1.5 hours. The results are given in Table 1 where the data are given in grams of liquid in the material immediately after the insult and at the 5, 15 and 30 minute marks for each layer for each of the three insults. The spill of the structure and the multifunctional material, the capillary tension and the permeability after each insult were also given.

Note that the amounts shown in the tables may not add exactly the expected or adequate sum due to rounding.

Table 1 g liquid in material Immediate 5 min. 15 min. 30 min. Insulting Emergence 51.26 6.94 5.36 3.75 Multifunctional 27.76 9.72 11.43 12.88 Distribution 15.72 18.19 15.21 12.79 Immediate 5 min. 15 min. 30 min. 2nd Insult Emergence 59.1 13. 7.8 6.0 Multifunctional 40.0 32.5 26.8 28.4 Distribution 21.4 31. 26.2 21.3 Immediate 5 min. 15 min. 30 min. 3 ° Insult Emergence 60.7 28.5 19.1 12.6 Multifunctional 53.5 37.4 38.2 39.2 Distribution 29.3 28.6 27.8 26.4 Insulting the 3rd Run 4.1 6.8 9.3 Capillary tension 6.9 5.6 6.5 Permeability 490 1160 660 Thickness (mm) 6 10 12 Moistened area (cm2) 0 56.4 56.4 Figure 5 graphically illustrates the spill results of Table 1 as a solid line. These test data demonstrate the low spill values for the two-inch wide material structure of this invention combined with the emergence and distribution elements where the e ^ ex is the number of the insult and the y-axis is the spill in grams.

For comparison, FIG. 5 also shows the results of the spill for a commercially available Huggies® Supreme® diaper four inches (10 cm) wide from the crotch width of Kimberly-Clark Corporation of Dallas, Texas as a dotted line. These data demonstrate the superior intake performance for the multifunctional narrow crotch compound through the three insult loads.

The graphs of Figures 6, 7 and 8 illustrate the unique liquid transfer characteristics of the multifunctional composite material including the immediate transfer function, the desorption of the emergence material, and the release of the multifunctional compound liquid in the distribution material with time. Figures 6, 7 and 8 graphically show the data in Table 1 for the first, second and third insults, respectively, giving the amounts of immediate liquid, 5, 15 and 30 minutes in grams (y axis) in each layer. In Figures 6, 7 and 8, the take or emergence material is the first bar in each set, the multifunctional material is the second bar and the distribution material is the third bar.

The first set of columns in the graph of Figure 6 shows the division of liquid between the three components immediately after the first insult. These columns show that the emergence material is retaining about half or 50 ml of the 100 ml insult while the multifunctional material of this invention retains about 30 ml. About 15 ml is retained within the distribution material below the multifunctional material. This illustrates that the multifunctional material has a sufficiently high initial permeability to allow some liquid to pass immediately through to the distribution material.

After a desorption time of 5 minutes, the second set of columns in the graph of figure 6 illustrates that the emergence material has been desorbed at a level of about 5 ml. Because it is located above the multifunctional material through the complete test procedure, the liquid is passed through the multifunctional material during the desorption phase.

The second set of columns in the graph of figure 6 shows that the multifunctional material has released about 20 ml of liquid during the desorption phase. This supports the design criteria that a part of the liquid is pulled out of the matrix of multifunctional material while a part is being transferred to the slow superabsorbent of the multifunctional material for permanent storage.

The graph of figure 7 is an illustration of the division of the liquid after the second insult of 100 ml. The first set of bars shows the emergence material taking again about 50 ml. Note that the first bar indicates about 55 ml total but also that the emergence material is retaining 5 ml after the first insult making the total take of 50 ml consistent with the operation of the first insult. The second bar within the first bar set illustrates the taking of the multifunctional material around 30 m, similar to the operation of the first insult. Note that while this bar shows 40 ml, the multifunctional material was containing 10 ml at the end of the first desorption cycle so that only 30 ml was taken during the second insult.

The distribution material shows similar saturation levels through the desorption test. During the desorption test, the dispensing material is in contact with a desorption retention pad used in this test configuration. Once the distribution material is saturated in the first insult, its saturation level remains approximately consistent because it is being fed by the liquid that is being released from the multifunctional compound, and is releasing the liquid to the retention material at a rate Similary.

The graph of figure 8 illustrates the liquid division of desorption phase after the third insult and reconfirms the conclusions of data discussed in relation to figures 6 and 7.

Example 2 In this example the multifunctional material consisted of about 40 weight percent of the same slow rate superabsorbent of Example 1 and about 60 weight percent of South Kimberly-Clark CR2054 soft wood fluff which had been treated with 0.2 percent by weight of a liquid binder. The particular liquid binder used was Kymene® 557LX binder available from Hercules, Inc., of Wilmington, Delaware. The liquid binder was activated by the addition of 20 percent by weight of water and heating around 105 ° C for about 10 minutes.

The multifunctional material was placed by air using a laboratory sheet former to achieve an intermixed structure with a basis weight of 440 gsm. The structure had a target density of around 0.22 g / cc.

This multifunctional material was tested with the same layers of distribution and emergence material as in Example 1 in the same manner given there and the results are given in Table 2.

Table 2 g liquid in material Immediate 5 mm. 15 min. 30 min. Insulting Emergence 44.4 4.7 3.5 3.1 Multifunctional 19.8 19.7 22.0 24.3 Distribution 14.4 21.6 17.7 10.6 Immediate 5 min. 15 min. 30 min. 2nd insult Emergence 51.4 5.5 3.9 3.4 Multifunctional 45.4 40.5 41 41.9 Distribution 23.0 26.8 24.0 20.2 Immediate 5 min. 15 min. 30 min. 3rd Insult Emergence 54.6 6.7 4.6 4.1 Multifunctional 58.8 55.4 53.8 53.1 Distribution 27.2 29.8 27.4 23.2 Insult the 2nd 3rd Run 19 20 23 Capillary tension 16.3 6.1 6.9 Permeability 140 840 660 Thickness (mm) 2 7 8.4 Moistened area (cm2) 0 118 118 Example 3 In this example, the multifunctional material consisted of about 60 weight percent of the same slow rate superabsorbent as in Example 1, about 37 weight percent Kimberly-Clark CR1654 and about 3 weight percent binder fiber Danaklon conjugate.

The multifunctional material was placed by air using a laboratory hand sheet former to achieve an intermixed structure with a base weight of 660 gsm. The structure had a target density of around 0.12 g / cc.

This multifunctional material was tested with the same layers of distribution and emergence material as in Example 1 in the same manner given there and the results are given in Table 3. Note that even when capillary tension and permeability after each insults were not calculated, it is anticipated that these will be similar to the values of Example 1 due to the similarity in the composition of the materials.

Table 3 g liquid in material Immediate 5 min. 15 min. 30 min. Insulting Emergence 51.9 4.9 2.7 Multifunctional 2.0.3 12.8 16.7 18.38 Distribution 14.6 18.3 13.5 1'J.

Immediate 5 min. 15 min. 30 min. 2nd Insult Emergence 58. 8.4 5.2 3.8 Multifunctional 39.7 32.2 35.6 37.9 Distribution 19.6 20.7 15.8 11.9 Immediate 5 min. 15 min. 30 min. 3rd insult Emergence 64.2 22.9 11.9 6.4 Multifunctional 58.6 50.8 53.9 56.9 Distribution 20. 21.1 20.3 18.1 Insult the 2nd 3rd Run 10.5.4 9.8 7.4 Capillary tension 800 NA * NA Permeability 0.5 NA NA Thickness (mm) 0 NA NA Moistened area (cm2) NA NA * Note: NA means not available.

Example 4 In this example, the multifunctional material consisted of about 60 weight percent of the slow rate superabsorbent of about 37 percent of the same pulp as in Example 1 and about 3 percent of Danaklon's conjugated binder fiber.

The slow rate superabsorbent used was the same as that used in Example 1.

The multifunctional material was formed by air using a laboratory hand sheet former to achieve an interspersed structure with a basis weight of 440 gsm. The structure had a target density of about 0.09 g / cc.

This multifunctional material was tested with the same layers of emergence and distribution material as in Example 1 in the same manner given there and the results are given in Table 4.

Table 4 g liquid in material Immediate 5 min. 15 min. 30 min. Insulting Emergence 53.4 4.3 3.4 2.7 Multifunctional 21.9 13.3 14.4 15.1 Distribution 15.2 12.5 10.1 8.5 Immediate 5 min. 15 min. 30 min. 2nd Insult Emergence 58.2 7.4 4.8 4. Multifunctional 38.0 31.4 32.7 33.7 Distribution 17.9 27.8 19.3 15.3 Immediate 5 min. 15 min. 30 min. 3rd Insult Emergence 65.4 11.0 6.7 5.1 Multifunctional 53. 44.2 45.9 47.0 Distribution 24.2 25.3 22.8 21.9 Insult the 2nd 3rd Run 7.6 6.9 5.5 Capillary tension 3.8 2.0 2.3 Permeability 1370 9150 5980 Thickness (mm) 5 12.5 14 Moistened area (cm2) 0 84 84 Example 5 In this example, the multifunctional material consisted of about 70 percent by weight of the same slow rate superabsorbent as in Example 4, about 27 percent by weight of the same pulp as in Example 1 and about 3 percent. by weight of Danaklon conjugated binder fiber. _ The multifunctional material was formed by air using a hand sheet former to achieve an intermixed structure with a basis weight of 500 gsm. The structure had a target density of around 0.12 g / cc.

This multifunctional material was tested with the same layers of emergence and distribution material as in Example 1 in the same manner given there, the results are given in Table 5. Note that the low capillary tension of the multifunctional material prevented the desorption of the liquid of the emergence layer. This low capillary tension is believed to be caused by the large and hydrophobic nature of the superabsorbent particles used in this Example 5 to achieve the desired slow rate. If the slow rate of the multifunctional material was achieved by a method other than particle size and hydrophobicity, a multifunctional material having 70 percent by weight of superabsorbent should work acceptably well within the goals and limits of the invention. In fact, using the information of the second and third insults of Example 5 which is required to predict the permeability and capillarity, and assuming a multifunctional material having 70 percent by weight of superabsorbent with a size of 450 microns and a contact angle of 30 degrees, capillary tension and permeability conforming to the invention were calculated and shown below (note that since no actual material was made, the spill data are absent): Insult 1 or 2 or 3 or Capillary tension 4. 1 3. 1 2 9 Permeability 1325 3590 3880 Table 5 g liquid in material Immediate 5 min. 15 min. 30 min. Insulting Emergence 56 38.1 34. 31.1 Multifunctional 13.9 9.9 13.7 16.5 Distribution 13.3 13. 9.7 8.3 Immediate 5 min. 15 min. 30 min. 2 or Insult Emergence 60.4 55. 50.6 46.7 Multifunctional 31.1 25.2 28.5 30.9 Distribution 18. 14.4 12.4 10.9 Immediate 5 min. 15 min. 30 min. 3 or Insult Emergence 65.8 56.2 52.6 49.7 Multifunctional 48.5 38.6 40.5 41.6 Distribution 20.5 13.5 11.9 10.0 Insult the 2nd 3rd Run 16.5 43.3 43.4 Capillary tension 3.9 2.4 2.1 Permeability 1490 5670 7060 Thickness (mm) 4 10 14. Xea moistened (cm2) 0 71.6 71.6 Finally, the graph of Figure 9 shows the liquid distribution data of a complete absorbent system with the emergence, multifunctional and distribution materials of Example 1 placed in a diaper frame and tested on the babies. This absorbent system is shown in Figure 1 and has the permanent storage retention compounds in place. The permanent storage retention compounds were made from 60 percent by weight of the crosslinked superabsorbent surface highly FAVOR 870 of Stockhausen Company, 38 percent by weight of pulp CR2054 of Kimberly-Clark Corporation and about 2 percent by weight. weight of Kymene® liquid binder. The diapers were placed on 20 babies and they were insulted with three milliliter insults of salt water solution of 8.5 g / 1 at 30 minutes of separation. The diapers were removed from the babies and at the end of 30 minutes and from the 90 minutes they were put in X-rays to determine the distribution of the liquid. The graph of Figure 9 shows that the liquid has moved to the ends of the product with respect to both insults of 100 ml and 300 ml. This illustrates that the liquid splitting characteristics of the multifunctional material operate in fully absorbent systems and allow liquid distribution to occur under conditions of simulated real use.

In summary, the example multifunctional material data illustrate the unique fluid flow liquid handling and capillary flow liquid splitting characteristics of the material and the structure of the invention. These data illustrate the values of low spillage by a multifunctional composite structure of narrow crotch. further, the example banking data show that the composite structure has a function to pass the liquid, desorb the emergence material through its time frames consistent with the user conditions (for example, around 90 minutes) and release the liquid from its interstitial matrix for distribution to remote storage locations instead of retaining most of an insult in the intake area. The benefit of distribution of the multifunctional material is demonstrated in the complete absorbent system test within a diaper shell construction on live infants.

Although only a few exemplary embodiments of this invention have been described in detail, 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 claims, the media clauses plus function are intended to cover the structures described herein as carrying out the recited function and not only the structural equivalents but also the equivalent structures. Therefore even when a screw and a nail may not be structural equivalents in the sense that a nail employs a cylindrical surface to secure joints to the wooden parts, while a screw employs a helical surface, in the environment of the fastening Wood parts, a nail and a screw can be equivalent structures.

Claims (20)

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

1. A multifunctional material comprising superabsorbent, pulp and a binder component wherein said multifunctional material has a permeability of between 100 and 10000 Darcys, and a capillary tension of between about 2 and 15 cm during its lifetime.

2. The material as claimed in clause 1, characterized in that it has between 30 and 75 percent by weight of a superabsorbent, between 25 and 70 percent by weight of pulp and from a positive amount up to about 10 percent of a binder component.

3. The material as claimed in clause 1, characterized in that it has a density between about 0.05 and 0.5 g / cc.

4. The material as claimed in clause 1, characterized in that it has a basis weight of between about 200 and 700 gsm.

5. The material as claimed in clause 1, characterized in that said superabsorbent has an absorption time index of more than 5 minutes.

6. The material as claimed in clause 1, characterized in that said superabsorbent has an absorption time index of more than 10 minutes.

7. The material as claimed in clause 1, characterized in that said superabsorbent is selected from the group consisting of particles, beads and fibers.

8. The material as claimed in clause 1, characterized in that said binder component is selected from the group consisting of liquid and fiber adhesives.

9. The material as claimed in clause 8, characterized in that said binder is a heat activated adhesive fiber.

10. The material as claimed in clause 9, characterized in that said fiber is selected from the group consisting of polyethylene / polyethylene terephthalate, polyethylene and polyethylene / polypropylene.

11. A composite structure for personal care products comprising an emergence material adjacent to the multifunctional material as claimed in clause 1 which is adjacent to a distribution material.

12. The lime and eats composite structure is claimed in clause 11, characterized in that said multifunctional material has a capillary tension greater than that of said sprouting material and smaller than that of the distribution material.

13. The composite structure as claimed in clause 11, further characterized in that it comprises a distribution material adjacent said distribution material so that said distribution material distributes the liquid from said multifunctional material to said retaining material.

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

15. The product as claimed in clause 14, characterized in that said product for personal care is a product for feminine hygiene.

16. The product as claimed in clause 14, characterized in that said product for personal care is a product for adult incontinence.

17. The product as claimed in clause 14, characterized in that said product for personal care is a diaper.

18. The product as claimed in clause 17, having a crotch width of at least 7.6 cm.

19. A narrow crotch diaper comprising: a material of emergence, a layer of multifunctional material in communication of the liquid with said emergence material and comprising between 35 and 60 percent by weight of a superabsorbent of slow rate, between 40 and 65 percent by weight of pulp and between about 1 and 7 percent of a binder component, wherein said multifunctional materials have a permeability of between 250 and 10,000 Darcys, and a capillary tension of between about 2 and 15 cm, during their lifetime. a distribution layer, a retention material in liquid communication with said distribution layer and which stores the liquid; Y wherein said diaper has a crotch having a width of at most 5 cm and a running rate of less than 25 ml for an insult of 100 ml.

20. A narrow crotch diaper comprising: an emergence material capable of handling an incoming insult of between about 60 and 100 cc at a volumetric flow rate of from about 5 to 20 cc / sec, a layer of functional material in communication of the liquid with said emergence material and having a liquid passage function which also desorbs the emergence material through the time frames consistent with the user conditions and releases the liquid for distribution. . to remote storage locations, a distribution layer in communication of the liquid with said multifunctional material having a capillary tension greater than 15 cm, which moves the liquid from said multifunctional material to the remote storage locations, the retention material in communication of the liquid with said distribution layer which stores the liquid, wherein said diaper has a crotch having a width of at most 5 cm. SUMMARY A multifunctional material is provided for use in personal care products. The multifunctional material has a permeability of between 100 and 10000 Darcys and a capillary tension of between about 2 and 15 cm. The structures containing this multifunctional material can have a run rate of less than 25 ml per 100 ml insult, during its lifetime. The multifunctional material should have between about 30 and 75 percent by weight of a slow-rate superabsorbent, between 25 and 70 percent by weight of pulp and from a positive amount to about 10 percent of a binder component. The material preferably has a density of between about 0.05 and 0.5 g / cc. The material has a liquid transfer function which desorbs an emerging material through time frames consistent with the user conditions and releases the liquid for distribution to remote storage locations. The material, when combined with the intake and distribution materials, define a composite structure for use in personal care products.