WO1999048454A1

WO1999048454A1 - Leakage reducing construction for absorbent articles

Info

Publication number: WO1999048454A1
Application number: PCT/US1999/005883
Authority: WO
Inventors: Stanley Michael Gryskiewicz; Frank Jerrel Akin; Thomas Gerald Bolwerk; Andrew Scott Burnes; Kuo-Shu Edward Chang; James Arthur Davis; Robert Cosmo Di Luccio; Clifford Jackson Ellis; Michael Franklin Kalmon; Alexander James Neeb; Jenny Lee Rollins; Lisa Ann Schild; Sandra Marie Yarbrough
Original assignee: Kimberly-Clark Worldwide, Inc.
Priority date: 1998-03-25
Filing date: 1999-03-17
Publication date: 1999-09-30
Also published as: AU3190399A

Abstract

The objects of this invention are provided by a personal care product having a surge layer on top of a distribution layer which is on top of a retention layer. The distribution layer has a tab portion on either side which extends around the edges of the surge layer in a 'U' shape and may extend over the surge layer covering an area of up to about 40 percent of the surge layer width. The retention layer may have bulge portions which fold around the surge and distribution layers in a 'U' shape and extend over the surge and distribution layers an amount of up to about 50 percent of the surge width.

Description

LEAKAGE REDUC ING CONSTRUCTION FOR ABSORBENT ARTICLES

FIELD OF THE INVENTION

This invention concerns improved personal care products, such as diapers, training pants, absorbent underpants, adult incontinence products, and feminine hygiene products.

BACKGROUND OF THE INVENTION

Personal care products may be thought of as "absorbent systems" which generally manage fluid wastes, though they may also handle solid waste as well. This invention is concerned primarily with the management of fluid wastes, more specifically urine or menses fluid.

Typical absorbent systems require three separate functions in order provide a level of protection from leakage and the associated staining of clothing and other negative effects. These functions are fluid intake, distribution, and containment. As personal care products are required to be thinner, i.e.; with narrower crotches, for improved comfort, as well as with improved leakage protection, it is necessary to optimize these functions. It is therefore an object of this invention to provide an improved construction for use in personal care products which reduces leakage even in narrow crotch product designs.

1 - SUMMARY OF THE INVENTION

The objects of this invention are provided by a personal care product having a surge layer on top of a distribution layer which is on top of a retention layer. The distribution layer has a tab portion on either side which extends around the edges of the surge layer in a "U" shape and may extend over the surge layer covering an area of up to about 40 percent of the surge layer width.

The retention layer may have bulge portions which fold around the surge and distribution layers in a "U" shape and extend over the surge and distribution layers an amount of up to about 50 percent of the surge width.

BRIEF DESCRIPTION OF THE DRAWING PORTIONS

Figure 1 is a drawing of a basic diaper design. Figure 2 is an exploded view of the diaper of Figure 1.

Figure 3 shows a diaper design meeting the objective of this invention and referred to as a single foldover design. In this design.

An exploded view of the diaper of Figure 3 is shown in Figure 4 and shows the tab portions 7 on the distribution layer 8. Figure 5 shows a diaper design meeting the objective of this invention and referred to as a dual foldover design.

An exploded view of the diaper of Figure 5 is shown in Figure 6 and shows the tab portions 11 on the distribution layer 8 and the bulge portions 12 on the containment layer 10. Figure 7 shows a cradle used to simulate body curvature of a user such as an infant and used in the MIST evaluation test. DEFINITIONS

As used herein the term "nonwoven fabric or web" means a web having a structure of individual fibers or threads which are interlaid, but not in an identifiable manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of material per square yard (osy) or grams per square meter (gsm) and the fiber diameters useful are usually expressed in microns. (Note that to convert from osy to gsm, multiply osy by 33.91).

As used herein the term "microfibers" means small diameter fibers having an average diameter not greater than about 75 microns, for example, having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, microfibers may have an average diameter of from about 2 microns to about 40 microns. Another frequently used expression of fiber diameter is denier, which is defined as grams per 9000 meters of a fiber and may be calculated as fiber diameter in microns squared, multiplied by the density in grams/cc, multiplied by 0.00707. A lower denier indicates a finer fiber and a higher denier indicates a thicker or heavier fiber. For example, the diameter of a polypropylene fiber given as 15 microns may be converted to denier by squaring, multiplying the result by .89 g/cc and multiplying by .00707. Thus, a 15 micron polypropylene fiber has a denier of about 1.42 (15² x 0.89 x .00707 = 1.415). Outside the United States the unit of measurement is more commonly the "tex", which is defined as the grams per kilometer of fiber. Tex may be calculated as denier/9. As used herein the term "spunbonded fibers" refers to small diameter fibers which are formed by extruding molten thermoplastic material as filaments from a plurality of fine, usually circular capillaries of a spinneret with the diameter of the extruded filaments then being rapidly reduced as by, for example, in US Patent 4,340,563 to Appel et al., and US Patent 3,692,618 to Dorschner et al., US Patent 3,802,817 to Matsuki et al., US Patents 3,338,992 and 3,341 ,394 to Kinney, US Patent 3,502,763 to Hartman, and US Patent 3,542,615 to Dobo et al. Spunbond fibers are generally not tacky when they are deposited onto a collecting surface. Spunbond fibers 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 US Patents 5,277,976 to Hogle et al., US Patent 5,466,410 to Hills and 5,069,970 and 5,057,368 to Largman et al., which describe fibers with unconventional shapes.

As used herein the term "meltblown fibers" means fibers formed by extruding a molten thermoplastic material through a plurality of fine, usually circular, die capillaries as molten threads or filaments into converging high velocity, usually hot, gas (e.g. air) streams which attenuate the filaments of molten thermoplastic material to reduce their diameter, which may be to microfiber diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly disbursed meltblown fibers. Such a process is disclosed, for example, in US Patent 3,849,241 to Butin et al. Meltblown fibers are microfibers which may be continuous or discontinuous, are generally smaller than 10 microns in average diameter, and are generally tacky when deposited onto a collecting surface.

As used herein, the term "coform" means a process in which at least one meltblown diehead is arranged near a chute through which other materials are added to the web while it is forming. Such other materials may be pulp, superabsorbent particles, natural polymers (for example, rayon or cotton fibers) and/or synthetic polymers (for example, polypropylene or polyester) fibers, for example, where the fibers may be of staple length. Coform processes are shown in commonly assigned US Patents 4,818,464 to Lau and

- 4 - 4,100,324 to Anderson et al. Webs produced by the coform process are generally referred to as coform materials.

As used herein the term "polymer" generally includes but is not limited to, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc. and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term "polymer" shall include all possible geometrical configurations of the molecule. These configurations include, but are not limited to isotactic, syndiotactic and random symmetries.

As used herein, the term "machine direction" or MD means the length of a fabric in the direction in which it is produced. The term "cross machine direction" or CD means the width of fabric, i.e. a direction generally perpendicular to the MD.

As used herein the term "conjugate fibers" refers to fibers which have been formed from at least two polymers extruded from separate extruders but spun together to form one fiber. Conjugate fibers are also sometimes referred to as multicomponent or bicomponent fibers. The polymers are usually different from each other though conjugate fibers may be monocomponent fibers. The polymers are arranged in substantially constantly positioned distinct zones 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 may be, for example, a sheath/core arrangement wherein one polymer is surrounded by another or may be a side by side arrangement, a pie arrangement or an "islands-in-the-sea" arrangement. Conjugate fibers are taught in US Patent 5,108,820 to Kaneko et al., US Patent 4,795,668 to Krueger et al., US Patent 5,540,992 to Marcher et al. and US Patent 5,336,552 to Strack et al. Conjugate fibers are also taught in US Patent 5,382,400 to Pike et al. and may be used to produce crimp in the fibers by using the differential rates of expansion and contraction of the two (or more) polymers. Crimped fibers may also be produced by mechanical means and by the process of German Patent DT 25 13 251 A1. For two component fibers, the polymers may be present in ratios of 75/25, 50/50, 25/75 or any other desired ratios. The fibers may also have shapes such as those described in US Patents 5,277,976 to Hogle et al., US Patent 5,466,410 to Hills and 5,069,970 and 5,057,368 to Largman et al., which describe fibers with unconventional shapes. As used herein the term "biconstituent fibers" refers to fibers which have been formed from at least two polymers extruded from the same extruder as a blend. The term "blend" is defined below. Biconstituent fibers do not have the various polymer components arranged in relatively constantly positioned distinct zones across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead usually forming fibrils or protofibrils which start and end at random.

Biconstituent fibers are sometimes also referred to as multiconstituent fibers. Fibers of this general type are discussed in, for example, US Patents 5,108,827 and 5,294,482 to Gessner. Bicomponent and biconstituent fibers are also discussed in the textbook Polymer Blends and Composites 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, at pages 273 through 277.

"Bonded carded web" refers webs are made from staple fibers which are sent through a combing or carding unit, which breaks apart and aligns the staple fibers in the machine direction to form a generally machine direction-oriented fibrous nonwoven web. Such fibers are usually purchased in bales which are placed in a picker which separates the fibers prior to the carding unit. Once the web is formed, it then is bonded by one or more of several known bonding methods. One such bonding method is powder bonding, wherein a powdered adhesive is distributed through the web and then activated, usually by heating the web and adhesive with hot air. Another suitable bonding method is pattern bonding, wherein heated calender rolls or ultrasonic bonding equipment are used to bond the fibers together, usually in a localized bond pattern, though the web can be bonded

- 6 - across its entire surface if so desired. Another suitable and well-known bonding method, particularly when using bicomponent staple fibers, is through-air bonding.

"Airlaying" is a well known process by which a fibrous nonwoven layer can be formed. In the airlaying process, bundles of small fibers having typical lengths ranging from about 6 to about 19 millimeters (mm) are separated and entrained in an air supply and then deposited onto a forming screen, usually with the assistance of a vacuum supply. The randomly deposited fibers then are bonded to one another using, for example, hot air or a spray adhesive.

As used herein, through-air bonding or "TAB" means a process of bonding a nonwoven bicomponent fiber web in which air which is sufficiently hot to melt one of the polymers of which the fibers of the web are made is forced through the web. The air velocity is between 100 and 500 feet per minute and the dwell time may be as long as 6 seconds. The melting and resolidification of the polymer provides the bonding. Through air bonding has relatively restricted variability and since through-air bonding (TAB) requires the melting of at least one component to accomplish bonding, it is restricted to webs with two components like conjugate fibers or those which include an adhesive. In the through-air bonder, air having a temperature above the melting temperature of one component and below the melting temperature of another component is directed from a surrounding hood, through the web, and into a perforated roller supporting the web. Alternatively, the through-air bonder may be a flat arrangement wherein the air is directed vertically downward onto the web. The operating conditions of the two configurations are similar, the primary difference being the geometry of the web during bonding. The hot air melts the lower melting polymer component and thereby forms bonds between the filaments to integrate the web. As used herein, uncreped through air dried or UCTAD means articles made according to the UCTAD method as described, for example, in US Patent 5,399,412 and 5,492,598. This process involves the application of differential pressure to a tissue web while the web is supported on a coarse fabric at a consistency of about 30 percent or greater. The differential pressure causes air to pass through the web, thereby drying it. As used herein, the term "personal care product" means diapers, training pants, absorbent underpants, adult incontinence products, and feminine hygiene products.

TEST METHODS

Multiple Insult Test (MIST Evaluation): In this test a fabric, material or structure composed of two or more materials is placed in an acrylic cradle to simulate body curvature of a user such as an infant. Such a cradle is illustrated in Figure 7. The cradle has a width into the page of the drawing as shown of 33 cm and the ends are blocked off, a height of 19 cm, an inner distance between the upper arms of 30.5 cm and an angle between the upper arms of 60 degrees. The cradle has a 6.5 mm wide slot at the lowest point running the length of the cradle into the page.

The material to be tested is placed on a piece of polyethylene film the same size as the sample and placed in the cradle. The material to be tested is insulted with 60 ml of a saline solution of 8.5 grams of sodium chloride per liter, at a rate of 15 cc/sec with a nozzle normal to the center of the material and inch (6.4 mm) above the material. The placement of the insult at the lowest point in the cradle is believed to mimic the target zone for females. The amount of runoff is recorded. The material is tested in the same manner a total of three times, each insult separated from another insult by 30 minutes. DETAILED DESCRIPTION OF THE INVENTION

As the crotch of a personal care product becomes narrower, the amount of instantaneous or "void" volume in the target area into which the fluid may go is significantly reduced. As a result, the target zone may not be able to accept all of the incoming liquid. This places more stress on the rest of the personal care product to keep the fluid from leaking out. Thus a narrow crotch product is more likely to leak during use than a wider product.

It has been observed that a personal care product has to keep an insult controlled for about 6 seconds, or the duration of the typical urine insult. As fluid enters the product, it goes from free fluid to fluid that is slightly controlled in the upper part of the product. As fluid reaches the edges of the product, it returns to an uncontrolled state either out of the side or the top of the product.

In order to eliminate this uncontrolled movement of fluid, the inventors have developed a "foldover" concept which increases the instantaneous void volume. The fluid enters a surge material within the fold, fills the surge and an upper layer. The fluid reaches the side of the absorbent near the fold but instead of going out of the side of the product it continues to spread into the fold, increasing the overall surface area of contact. Since there is more surface area, the fluid is thus held within this greater surface area longer. This increases the time the superabsorbent has to begin to intake the fluid and prevent it from leaking. The more path length the fluid has to follow without becoming uncontrolled, the more likely a superabsorbent particle will begin to absorb it.

Turning now to Figure 1 , there can be seen an example of a basic diaper shape consisting of three layers. These layers are shown in the exploded view of Figure 2 to be a surge layer 1 , a distribution layer 2 and an absorbent layer 3. Such products also usually have a liner material and backsheet (not shown for clarity). While it may appear obvious, it should be noted that in order to function effectively, the materials used must have sufficient contact to transfer liquid between them.

The liner is sometimes referred to as a bodyside liner or topsheet and is adjacent to the surge material. The liner material is the layer against the wearer's skin and so the first layer in contact with liquid or other exudate from the wearer. The liner further serves to isolate the wearer's skin from the liquids held in an absorbent structure and should be compliant, soft feeling and non-irritating.

Various materials can be used in forming the bodyside liner of the present invention, including apertured plastic films, woven fabrics, nonwoven webs, porous foams, reticulated foams and the like. Nonwoven materials have been found particularly suitable for use in forming the bodyside liner, including spunbond or meltblown webs of polyolefin, polyester, polyamide (or other like fiber forming polymer) filaments, or bonded carded webs of natural polymers (for example, rayon or cotton fibers) and/or synthetic polymers (for example, polypropylene or polyester) fibers. For example, the bodyside liner can be a nonwoven spunbond web of synthetic polypropylene filaments. The nonwoven web 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 gsm to about 42.0 gsm, a bulk or thickness ranging from about 0J3 millimeter (mm) to about 1.0 mm, and more particularly from about 0J8 mm to about 0.55 mm, and a density between about 0.025 grams per cubic centimeter (g/cc) and about 0J2 g/cc, and more particularly between about 0.068 g/cc and about 0.083 g/cc. Additionally, the permeability of such nonwoven web can be from about 150 Darcy to about 5000 Darcy. The nonwoven web can be surface treated 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 web by any conventional means, such as spraying, printing, brush coating and the like.

- 10 - The surge layer is most typically interposed between and in intimate, liquid communicating contact with the bodyside liner and another layer such as a distribution or retention layer. The surge layer is usually subjacent the inner (unexposed) surface of bodyside liner. To further enhance liquid transfer, it can be desirable to attach the upper and/or lower surfaces of the surge layer to the liner and the distribution layer, respectively. Suitable conventional attachment techniques may be utilized, including without limitation, adhesive bonding (using water-based, solvent-based and thermally activated adhesives), thermal bonding, ultrasonic bonding, needling and pin aperturing, as well as combinations of the foregoing or other appropriate attachment methods. If, for example, the surge layer is adhesively bonded to the bodyside liner, the amount of adhesive add-on should be sufficient to provide the desired level(s) of bonding, without excessively restricting the flow of liquid from the liner into the surge layer. Exemplary surge materials may be found in US Patent Applications numbers 08/754,417, 08/755,514 and US Patent 5,490,846. The '514 Application, for example, presents a surge material which is a web of wettable fibers of 30 microns in diameter or less which is substantially uniform and where the web has a permeability of between about 250 and 1500 Darcys and a capillary tension between 1.5 and 5 cm.

Various woven fabrics and nonwoven webs can be used to construct a surge layer. For example, the surge layer may be a nonwoven fabric layer composed of a meltblown or spunbond web of polyolefin filaments. Such nonwoven fabric layers may include conjugate, biconstituent and homopolymer fibers of staple or other lengths and mixtures of such fibers with other types of fibers. The surge layer also can be a bonded carded web or an airlaid web composed of natural and/or synthetic fibers. The bonded carded web may, for example, be a powder bonded carded web, an infrared bonded carded web, or a through-air bonded carded web. The bonded carded webs can optionally include a mixture or blend of different fibers, and the fiber lengths within a

- 11 - selected web may range from about 3 mm to about 60 mm. Exemplary surge layers can have a basis weight of at least about 0.50 ounce per square yard (about 17 grams per square meter), a density of at least about 0.010 gram per cubic centimeter at a pressure of 68.9 Pascals, a bulk of at least about 1.0 mm at a pressure of 68.9 Pascals, a bulk recovery of at least about 75 percent, a permeability of about 500 to about 5000 Darcy, and a surface area per void volume of at least about 20 square centimeters per cubic centimeter. The surge layer may be composed of a substantially 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 surge layer can have a generally uniform thickness and cross-sectional area.

The distribution layer must be capable of moving liquid from the point of initial deposition to where storage is desired. Distribution must take place at an acceptable rate such that the target insult area, generally the crotch area, is ready for the next insult. The time between insults can range from just a few minutes to hours, generally depending on the age of the wearer. In order to achieve this transportation function, a distribution layer must have a high capillary tension value. Capillary tension in distribution and other materials not containing superabsorbents is measured simply by the equilibrium vertical wicking height of a 8.5 g/l saline solution according to the Vertical Liquid Flux rate test, not by the test method given for materials containing superabsorbents. A successful distribution layer must have a capillary tension greater than the adjacent material from which it receives liquid (on the side toward the wearer) and preferably a capillary tension of at least about 15 cm. Because of the generally inverse relationship between capillary tension and permeability, such a high capillary tension indicates that the distribution layer will usually have a low permeability. Materials from which the distribution layer may be made include woven fabrics and nonwoven webs, foams, particles and filamentious materials. For example, the

- 12 - distribution layer may be a nonwoven fabric layer composed of a meltblown or spunbond web of polyolefin, polyester, polyamide (or other web forming polymer) filaments. Such nonwoven fabric layers may include conjugate, biconstituent and homopolymer fibers of staple or other lengths and mixtures of such fibers with other types of fibers. The distribution layer also can be a bonded carded web, an airlaid web or a wetlaid pulp structure composed of natural and/or synthetic fibers, or a combination thereof. The distribution layer may have, for example, between about 40 and 90 percent pulp and between about 10 and 60 percent superabsorbent and may have a basis weight of from 35 to 700 gsm, or more preferably from 200 to 600 gsm, a density of between about 0.08 and 0.5 g/cc and a permeability between about 50 and 1000 Darcys.

The absorbent layer, also called a containment or retention layer, must absorb the insult quickly and efficiently. They should be capable of absorbing the liquid without significant "gel blocking" or blocking of penetration of liquid further into the absorbent by the expansion of the outer layers of absorbent. Retention materials are often composites containing high rate superabsorbent polymers such as blends of polyacrylate superabsorbent and fluff. These materials rapidly absorb and hold liquid.

The retention materials used in this invention must absorb liquid from the distribution layer in a controlled manner. Suitable retention materials for this application should contain an absorbent composition comprising from 20 to 85 weight percent of superabsorbent, from 80 to 0 weight percent pulp, from a positive amount to about 10 weight percent of a binder component and which has a density between about 0J and 0.4 g/cc. The retention materials must, of course, be mechanically stable in order to survive dry and wet use conditions. The integrity of the retention materials may be provided by small amounts of thermally activated conjugate binder fiber, for example, or by any other suitable means such as with liquid adhesives, heat activated film adhesives, or with meltblown fibers which bind the other ingredients mechanically (by entanglement) or

- 13 - adhesively. An example of suitable retention materials may be found in US Patent 5,350,370 to Jackson et al. commonly assigned.

Examples of suitable retention material components include the Stockhausen Company's FAVOR® 870 and 880 highly crosslinked surface superabsorbent, Coosa River CR-2054 pulp and Kymene® liquid binder. Others include AFA 94-21-5, a 850 to 1400 micron suspension polymerized polyacrylate particle and 16179 superabsorbent, both from The Dow Chemical Company of Midland, Ml, CR-1654 pulp commercially available from the Coosa River Corporation and which is a southern softwood pulp, and high bulk additive formaldehyde free pulp (HBAFF) available from the Weyerhaeuser Corporation of Tacoma, WA, which is a crosslinked southern softwood pulp fiber with enhanced wet modulus. HBAFF has a chemical treatment which sets in a curl and twist, in addition to imparting added dry and wet stiffness and resilience to the fiber. One binder fiber which may be used to mechanically stabilize the absorbent structure is from Danaklon a/s, located at Engdraget 22, KD-6800 Varde, Denmark, and is 2 denier conjugate PE/PP sheath/core fibers cut into 6 mm lengths. Kymene® 557LX liquid binder is available from Hercules Inc. of Wilmington, DE. Many other superabsorbents, pulps and binders are commercially available from various sources.

The retention layer can be a bonded carded web, an airlaid web an UCTAD web, a mechanical mixture of ingredients, or a combination thereof. An UCTAD web may, for example, also contain superabsorbent. The retention layer may have a basis weight of from 35 to 800 gsm and may have various ingredients zoned to certain areas in the retention layer. US Patent Application 08/755,136 shows examples of zoned retention layers.

The backsheet is sometimes referred to as the outer cover and is located the farthest layer from the wearer. The outer cover is typically formed of a thin thermoplastic film, such as polyethylene film, which is substantially impermeable to liquid. The outer

- 14 - cover functions to prevent body exudates contained in an absorbent structure from wetting or soiling the wearer's clothing, bedding, or other materials contacting the diaper. The outer cover may be, for example, a polyethylene film having an initial thickness of from about 0.5 mil (0.012 millimeter) to about 5.0 mil (0J2 millimeter). The polymer film outer cover may be embossed and/or matte finished to provide a more aesthetically pleasing appearance. Other alternative constructions for outer cover include woven or nonwoven fibrous webs that have been constructed or treated to impart the desired level of liquid impermeability, or laminates formed of a woven or nonwoven fabric and thermoplastic film. The outer cover may optionally be composed of a vapor or gas permeable, microporous "breathable" material, that is permeable to vapors or gas yet substantially impermeable to liquid. Breathability can be imparted in polymer films by, for example, using fillers in the film polymer formulation, extruding the filler/polymer formulation into a film and then stretching the film sufficiently to create voids around the filler particles, thereby making the film breathable. Generally, the more filler used and the higher the degree of stretching, the greater the degree of breathability.

Figure 3 shows a diaper design meeting the objective of this invention and referred to as a single foldover design. Figure 3 has the distribution layer 1 1 folded over the surge layer 10 and both are on top of the containment layer 12. The exploded view of the diaper in Figure 4 shows the tab portions 18 on the distribution layer 16. During fabrication or conversion of the diaper the tab portions 18 are folded around the surge layer 15. The tab portions 18 may be as long as the crotch length and each tab may fold over the surge layer an amount of between about 20 and 40 percent of the surge layer width for a total of from 40 to 80 percent for both tab portions. The ends of the tab portions 18 are not required to be square. Figure 4 also illustrates that various parts of the containment layer 17 may be divided into zones. These zones 19, 20, 21 may be comprised of different

- 15 materials and may be of differing shape. The shape of the zones 19, 20, 21 shown in Figure 4 is for illustrative purposes only.

Figure 5 shows a diaper design meeting the objective of this invention and referred to as a dual foldover design. In this design, the distribution layer 31 has tabs 33 which are folded over the surge layer 30 and the containment layer 32 has bulges 34 which are folded around both the distribution layer 31 and surge layer 30. An exploded view of the diaper of Figure 5 is shown in Figure 6 and shows the tab portions 43 on the distribution layer 41 and the bulge portions 44 on the containment layer 42. The tab portions 43 may be as long as the crotch length and each tab may fold around the edges of the surge layer 40 in a "U" shape. More particularly, each tab portion 43 may fold around and over to cover the surge layer 40 an amount up to about 40 percent of the surge width, or still more particularly, between about 20 and 40 percent of the surge layer width and the bulge portions 44 be as long as the crotch length and may fold around the edges of the surge layer 40 in a "U" shape. More particularly, each bulge portion 44 may fold around and over to cover up to about 50 percent of the surge layer 40, and still more particularly between about 20 and 50 percent of the surge layer 40 for a total of between about 40 and 100 percent for both bulge portions. The ends of the tab portions 43 and bulge portions 44 are not required to be square and may be flared as shown in Figure 6. Note that the terms "tab" and "bulge" may refer to the same shape extension of a material. The terms "tab" and "bulge" are used solely to differentiate between the layers. As shown also in Figure 6, the containment layer may be divided into zones 45, 46, 47, for example, which may be comprised of different materials and may be of differing shape.

It should be noted that the distribution and retention layers may themselves be comprised of multiple layers of material. In such a case some of the layers may have tab or bulge portions and some may not, within each distribution and retention layer.

16 It is also possible for the tabs or bulges to be comprised of different amounts of material than the rest of the layer of which they are a part or that different zones or parts of the layer may be comprised of differing amount or weight percentages of the components. For example, a tab or bulge may be comprised of UCTAD material only (without superabsorbent), while the layer of which it is a part may have superabsorbent in various zones. Various of the layers may also be embossed, if desired. Embossing may give increased strength or aesthetic value to the product and may also aid in liquid distribution.

The following Control and Examples illustrate the advantages of the instant designs.

Control

This control example used a through air bonded carded web surge layer having a basis weight of about 1.5 osy (50 gsm) and made from 2.2 denier polyester/polyethylene core/sheath fibers available from Trevira Inc., a distribution layer having a basis weight of about 400 gsm and made from 80 weight percent Buckeye HPK2 pulp and 20 weight percent Dow 16179 superabsorbent, and a retention layer having a basis weight of about 450 gsm and made from about 60 weight percent Coosa River CR-1654 pulp and about 40 weight percent Stockhausen Favor® 880 superabsorbent without binder.

The layers were laid on top of each other to approximate a diaper and subjected to the MIST test described in the Test Methods section above. The design looked like the diaper of Figure 2, i.e., there were no tab portions or bulge portions present.

Example 1

This example used the same surge as the control and is illustrated by Figures 3 and 4. The distribution layer had a basis weight of 350 gsm and was comprised of 50 weight percent CR-1654 pulp and 50 weight percent Favor® 880 superabsorbent. The

- 17 - retention layer had Favor® 880 superabsorbent between the second and third layers of four layers of 67 gsm UCTAD material. The superabsorbent was Favor® 880 and had a basis weight of about 150 gsm in zones 1 and 3 . Zone 2 had 50 gsm Favor® 880 superabsorbent. The layers were laid on top of each other to approximate a diaper and subjected to the MIST test described in the Test Methods section above. The design looked like the diaper of Figure 3 having distribution layer tab portions which were folded over the surge layer with each tab covering about 33 percent of the surge width.

Example 2

This example used the same surge layer as the control and is illustrated by Figures 5 and 6. The distribution layer had a basis weight of 475 gsm and was comprised of 50 weight percent CR-1654 pulp and 50 weight percent Favor® 880 superabsorbent. The retention layer had three layers of 67 gsm UCTAD material with superabsorbent between the first and second layers. The superabsorbent was Favor® 880 and had a basis weight of about 150 gsm in zones 1 and 3 . Zone 2 had no superabsorbent.

The layers were laid on top of each other to approximate a diaper and subjected to the MIST test described in the Test Methods section above. The design looked like the diaper of Figure 5 having distribution layer tab portions which were folded over the surge layer with each tab covering about 33 percent of the surge width, and having retention layer bulge portions with each bulge covering about 40 percent of the surge width. Grams of Runoff

Control Ex. 1 Ex. 2

1^st insult 13 6.8 1.5

2^nd insult 10 5.8 1.3

3^rd insult 29 12.3 5.5

18 As can clearly be seen from the above Control and Examples, the single fold design has less run-off and better absorption than the Control. The dual fold design performs better than the single fold design. In another aspect of the invention, it is possible to remove some of the material in the absorption product, particularly in the target area, and replace it with another material. If, for example, an oblong area of pulp and superabsorbent were removed from the distribution and retention layers and replaced with a material that accepted liquids more rapidly, for example, surge material or cotton, more surface area of the retention material would be exposed to the liquid. This would result in more rapid uptake of liquid by the retention materials. This objective could also be achieved by other means, for example, by aperturing the layers which take in liquids more slowly to allow liquid to pass through more rapidly, by adding a layer having high capillarity below the surge layer, and by removing just the distribution layer from the product. In order to test the concept of material removal from the target area, a 1 inch (2.5 cm) by 6 inch (15.2 cm) hole was cut into the upper layer of the product of Example 2, the distribution layer, and replaced with surge material. The material cut from the hole was placed around the sides of the hole. This product design as well as the Control were tested for runoff in the same manner as the Examples above and the results were: Grams of Runoff

Control Hole

1^st insult 17.5 7

2^nd insult 17 5.9

3^rd insult 18.9 10.5

- 19 - Clearly the "hole" design wherein a patch or portion (or multiple patches or portions) of material is removed and replaced with a more liquid receptive material, improves liquid intake and reduces run-off even further.

In yet another aspect of the invention, anti-bacterial agents, odor control agents, enzyme inhibitors and/or sequestrants can be added to the target zone for particular objectives. This may be done in the products described in Examples 1 and 2 or in the Example describing the removal of material from the target area. Because of the generally high cost of such agents, their placement only on the material to go in the target area can save substantially, allowing a lower cost product to be available to consumers. Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the following claims. In the claims, means plus function claims are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Thus although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures.

It should further be noted that any patents, applications or publications referred to herein are incorporated by reference in their entirety.

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Claims

What is claimed is:

1. A personal care product comprising a surge layer on top of a distribution layer which is on top of a retention layer, wherein said distribution layer has a tab portion on either side which extends around edges of said surge layer in a "U" shape and extends over said surge layer covering an area of up to about 40 percent of said surge layer width.

2. The personal care product of claim 2 wherein said tab portion extends around and over said surge layer covering an area of from about 20 up to about 40 percent of said surge layer width.

3. The personal care product of claim 1 wherein said surge layer is a nonwoven fabric.

4. The personal care product of claim 1 wherein said distribution layer is made from a process selected from the group consisting of airlaying, wetlaying and bonding and carding.

5. The personal care product of claim 4 wherein said distribution layer comprises pulp and superabsorbent.

6. The product of claim 5 wherein said distribution layer has said pulp and superabsorbent in differing weight percentages in different zones.

7. The personal care product of claim 1 wherein said retention layer is made from a process selected from the group consisting of airlayng, the UCTAD process and mechanical mixtures of ingredients, or a combination thereof.

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8. The personal care product of claim 1 selected from the group consisting of diapers, training pants, absorbent underpants, adult incontinence products, and feminine hygiene products.

9. The personal care product of claim 1 further comprising an additive selected from the group consisting of enzyme inhibitors, sequestrants, anti-bacterial agents and odor control agents.

10. The personal care product of claim 1 having a portion of said distribution layer removed from the target area and replaced with a more liquid receptive material.

1 1. The personal care product of claim 10 wherein said more liquid receptive material is selected from the group consisting of surge material and cotton.

12. The personal care product of claim 10 further comprising an additive selected from the group consisting of enzyme inhibitors, sequestrants, anti-bacterial agents and odor control agents.

13. The personal care product of claim 1 having a portion of said distribution layer and said retention layer removed from the target area and replaced with a more liquid receptive material.

14. The personal care product of claim 13 wherein said more liquid receptive material is selected from the group consisting of surge material and cotton.

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15. The personal care product of claim 14 further comprising an additive selected from the group consisting of enzyme inhibitors, sequestrants, anti-bacterial agents and odor control agents.

16. The personal care product of claim 1 wherein said retention layer comprises bulge portions, wherein each bulge portion folds around said surge and distribution layers in a "U" shape and extends over said surge and distribution layers an amount of up to about 50 percent of said surge width.

17. The personal care product of claim 16 wherein each bulge portion folds around and over said surge and distribution layers an amount of from about 20 to 50 percent of said surge width.

18. The personal care product of claim 16 having a portion of said distribution layer removed from the target area and replaced with a more liquid receptive material.

19. The personal care product of claim 18 wherein said more liquid receptive material selected from the group consisting of surge material and cotton.

20. The personal care product of claim 19 further comprising an additive selected from the group consisting of enzyme inhibitors, sequestrants, anti-bacterial agents and odor control agents.

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21. The personal care product of claim 16 having a portion of said distribution layer and said retention layer removed from the target area and replaced with a more liquid receptive material.

22. The material of claim 21 selected from the group consisting of surge material and cotton.

23. The personal care product of claim 22 further comprising an additive selected from the group consisting of enzyme inhibitors, sequestrants, anti-bacterial agents and odor control agents.

24. The personal care product of claim 16 selected from the group consisting of diapers, training pants, absorbent underpants, adult incontinence products, and feminine hygiene products.

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