CA1253320A - Absorbent structure containing corrugated web layers associated with superabsorbent - Google Patents

Abstract

Abstract An absorbent product which has a moisture-impermeable backing, a moisture-permeable facing and a corrugated fibrous web. The corrugated fibrous web has associated therewith at least about 10 percent by weight of superabsorbent. The corrugated web is stabilized to retain its transverse folds when wet.

Description

~25~3'~3 ABSORBENT STRUCTURE CONTAINING CORRUGA~ED W~B LAYERS
ASSOCIATED WITH SUPERABSORBENT
Background of the Invention The present invention relates to new and improved absorbent structures and more particularly to new and improved absorbent structures incorporating therein corrugated web layers which are associated with superabsorbent.

Disposable absorbent products have been known for some time, including such products as disposable diapers, sanitary napkins, wound dressings, bandages, incontinent pads, and the like. These products incorporate an absorbent batt which is used to absorb and hold, or contain, body fluids. Initially in many of these products, especially diapers and sanitary napkins, the absorbent batt comprised what is termed "wadding" or plies of tissue. The wadding was disposed between a liquid-impermeable backing and a liquid-permeable facing and the plies of tissue were used to absorb and, hopefully, contain the liquid within the product. A diaper which utilizes such an absorbent batt is disclosed in U.S. Reissue Patent No. 26,151.

The wadding type of batt was replaced, for the most part, by an improved absorbent batt which comprises what is termed "fluffed woodpulp fibers~. This absorbent batt comprises a layer of individualized woodpulp fibers with the layer having substantial thickness. A diaper which incorporates such a fluffed woodpulp absorbent batt is described in U.S. Patent No. 2,788,003. This diaper had ~Z53320 improved absorbent capacity and somewhat better contain-ment than a diaper using a wadding layer. Also, the fluffed woodpulp layer is quite soft, flexible and conformable, and hence produces an improved diaper over diapers using wadding as the absorbent layer.

Though the fluffed woodpulp absorbent batts have improved capacity, the efficiency with which the capacity is used in a diaper or sanitary napkin is poor. The reason for this is that the fluid to be absorbed is generally deposited in a localized area within the absorbent batt and the ability of the fluid to move along the plane of the batt is poor. The fluid tends to follow a radial wicking path and consequently moves to the closest edge of the batt where it generally is no longer contained and the product leaks.

U.S. Patent No. 3,017,304 discloses an absorbent product which incorporates in the product a densified paper-like layer. This paper-like layer acts as a wick, i.e., li~uid which is placed on the layer tends to move rapidly along the plane of the layer. When incorporated in combination with fluffed woodpulp fiber, the resultant product uses the absorbent capacity of the fluffed woodpulp much more efficiently. ~iapers which incorporate this paper-like layer combined with fluffed woodpulp are disclosed and described in U.~. Patent Nos. 3,612,055 and 3,938,522.
This concept of combining wicking ability, or a capillary skin or layer, with fluffed woodpulp fibers has gained wide acceptal~ce in many absorbent products, including disposable diapers and sanitary napkins. ~ven though these products make much greater use of the capacity of the absorbent batt, they still do not totally contain the absorbed liquid. It is probable that these products will leak before the full capacity of the batt is used for - ~2S~3320 absorption or,~at the very least, before the entire liquid void by the user is absorbed. This is especially true when pressure is placed on the batt while wet. For example, a baby sitting down on a previously wetted diaper will very often cause the batt to leak.

An incontinent adult faces many problems. First, the void of urine of an adult generally is much higher in volume than that of an infant. Second, a bulge under clothing due to a diaper is accepted by society for an infantr but the ambulatory adult with an incontinence problem longs for a product which is not visible through ordinary clothing. Third, the proportions and shape of the legs and torso of the adult differs considerably from those of an infant. Therefore, a mere enlargement of an infant diaper, such as that shown in U.S. Patent 4,253,461, is not a satisfactory product.

A number of years ago "superabsorbent materials", i.e., materials which will absorb many times their weight of liquid were developed. Since the development of such materials, there have been many attempts to incorporate them in absorbent products such as diapers and sanitary _ napkins to enhance the absorptive performance of these products. Theoretically, a minimum amount of superabsorbent incorporated in a product would make that product perform as well as or better than the prior art products. Perhaps one of the first products to incorporate such a superabsorbent material in a disposable diaper is disclosed in U.S. Patent No. 3,670,731. This patent discloses an absorbent dressing comprising an absorbent layer sandwiched between a permeable facing and an impermeable backing sheet. The absorbent layer contains water-insoluble cross-linked hydrocolloid polymer as the superabsorhent material.

~53~20 Even though superabsorbent materials have been available for some time, they have not gained wide acceptance in absorbent products such as dispGsable diapers and sanitary napkins. A primary reason for this lack of acceptance is failure to develop a product capable of economically utilizing the highly increased absorptive capacity of the superabsorbent material. In order to economically utilize a superabsorbent, the liquid being absorbed must be transported to the superabsorbent material. In other words, the superabsorbent material must be placed in contact with the liquid. Furthermore, as a superabsorbent material absorbs the liquid, it must be allowed to swell.
If the superabsorbent is prevented from swelling, it will cease absorbing liquid. Hence, if the superabsorbent material is to function in diapers and sanitary napkins, werein the liquid to be absorbed is placed in a small void area, the structure of the absorbent layer containing superabsorbent materials appears to be critical. Over the years a number of techniques have been disclosed in an attempt to provide structures which make efficient use of the superabsorbent material. Such products are disclosed in U.S. Patent Mo. 4,103,062; 4,102,340 and 4,235,237.
In addition, methods for incorporating superabsorbents into suitable layers or suitable configurations which can be placed in an absorbent product, are disclosed in U.S. Patent No. 4,186,165; 4,340,057 and 4,364,992. To date, none of these products has met with any substantial commercial success.

In both the infant diaper and adult incontinent product marketplace, a product is needed which has a large storage capacity. For instance, shaped containers have been suggested. However, these containers have been substantially rigid, do not stay in place, and are guite uncomfortable. A product with a substantially large liquid storage capacity, with an ability to move liquid lZS~32~

away from the void zone, which is disposable, which i5 comfortable, and which does not show through wearing apparel is needed in the marketplace.

S The present invention provides a new and improved absorbent product which provides a large storage capacity and ability to transport liquid from the void zone which is soft and comfortable and which can be designed so as not to be apparent through normal clothing. In addition, the new absorbent product will contain absorbed liquid even when pressure is placed upon the product during use.

Summary of the Invention The present invention provides a disposable absorbent product comprising a corrugated fibrous web having associated therewith at least about 10% by weight of said web of superabsorbent. The product also comprises a liquid-impermeable barrier covering at least one side of the web, and a li~uid-permeable facing covering at least the other side of the web. The corrugated web is stabilized to retain its transverse folds when wet.

The fihrous web comprises substantially hydrophobic, resilient, preferably synthetic fibers generally in the form of a nonwoven web.

The superabsorbent in the form of particles, globules, film pieces, granules, powder or the like is distributed in the product and is associated with the fibrous web in such a manner as to permit maximum utilization of the superabsorbent as it contacts the liquid.

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The liquid-impermeable barrier generally is a waterproof type film such as polyethylene or polypropylene. It covers at least one side of the corrugated fibrous web.

The liquid-permeable facing generally is a nonwoven fabric or a perforated film or the like. The facing covers at least one side of the corrugated web, that slide being the side opposite the one covered by the barrier.

After or during corrugation of the web, the web is stabilized to retain its transverse folds, even when the product becoMes wet. The stabilization is provided by applying a layer of adhesive on one side of the web or by placing fusible fibers in the fibrous layer and raising the temperature of the web to a temperature close to the melting point of the fusible fibers. This stabilization is effected by the transverse folds partially adhering one to another.

When the absorbent product of the present invention is utilized, the liquid enters the corrugated web and the web because of its open structure, provides a large storage area. The superabsorbent is placed in contact with the liquid and the containing features of the web coupled with the liquid-impermeable barrier provide time for the superabsorbent to absorb the liquid and swell. The corrugations of the corrugated web preferably are placeA
in an absorbent structure, such as a diaper or incontinent product, so as to lie parallel to the longitudinal axis of the product.

BRIFF DESCP~IPTION OF THE DRAWINGS

Figure 1 is a perspective view of one e~bodiment of the present invention, the view being partially broken away for clarity;

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Figure 2 is an enlarged cross-sectional view through lines

2-2 of Figure l;

Figure 3 is a perspective view illustrating another embodiment of the present invention;

Figure 4 is a perspective view illustrating a further embodiment of the invention;

Figure 5 is an enlarged cross-sectional view through lines 5~5 of Figure 4;

Figure 6 is a perspective view illustrating a still further embodiment of the present invention; and Figure 7 is an enlarged cross-sectional view through lines 7-7 of Figure 6.

DETAIL~D DESCRIPTION OF THE IN FMTIOrl Figure 1 provides a perspective view of an absorbent product 10 having a corrugated fibrous web 12 sandwiched between a liquid-permeable facing 16 and a liquid-impermeable barrier 18. The absorbent product permits ingress of liquid through the liquid-permeable facing 16 into the corrugateA web 12, which web contains superabsorbent materials. The corrugated web 12 is stabilized by the fusion of fusible fibers so that when the liquid enters the product, its transverse folds of the corrugation remains substantially stable.

Figure 2 provides an enlarged cross-sectional view along lines 2-2 of Figure 1. The portion of the absorbent product 20 consists of the corrugated web 22 containing superabsorbent 24 distributed throughout the corrugated fibrous web 22. Fusible fibers 26 have been rendered 1253;:~2(~

sufficiently tacky to secure the corrugations so as to prevent destruction or interference with the transverse folds even when the product is wet. The liquid-permeable facing 16 permits ingress of liquid into the product and the liquid-impermeable barrier 18 prevents the spilling of liquid from the product.

Referring to Fi~ure 3, a diaper 30 is depicted. A liquid-permeable facing 32 such as a nonwoven fabric provides the diaper surface. A liquid-impermeable substance 34 such as a polyethylene film, provides a liquid-impermeable barrier for the diaper. The diaper structure 30 contains a corrugated fibrous web 33 sandwiched between the facing 32 and the backing 34. The corrugated web 33 is that which is described in Figure 1. The diaper side edges are gathered in the crotch region by elastic members 37. To secure the diaper about the waist of the wearer, tape tabs 39 are provided. The diaper product 30 generally has the corrugated web 33 placed in such a manner that the corrugations run parallel to the longitudinal axis of the product.

Referring now to Figure 4, a urinary pad 40 is depicted.
The urinary pad 40 has a liquid-permeable facing 42 covering the entire upper surface. Immediately beneath the facing 42 is a liquid barrier 44 which encompasses the entire product except for the opening 45 on the upper surface which lies immediately below the facing 42. The opening 45 permits ingress of fluids. The li~uid barrier 44, which encompasses the vast majority of the corrugated web absorbent portion, prevents the leakage of liquid after its entry into the product. The corrugated fibrous web contains superabsorbent, Figure 5 is an enlarged cross-sectional view of Figure 4 taken along lines 5-5. The facing 52 is the layer which - l~S33;~0 is placed against the skin of the wearer. The liquid barrier 54 encompasses the corrugated web 53 containing the superabsorbent except for the opening 55 through which liquid is permitted to enter. The corrugated web 53 is similar to that depicted in Figure 2. As shown in Figure 5, the corrugations of the corrugated web run parallel to the longitudinal axis of the product.

Figure 6 depicts a sanitary napkin 60 having a fabric overwrap 62 which is liquid-permeable.

Figure 7 depicts an enlarged cross-sectional view of Figure 6 taken along line 7-7. The cross-sectional portion of product 70 is provided with a liquid-permeable overwrap 71 appearing with its overlapped portion on the upper surface of the drawing. Immediately below is a moisture-impermeable barrier 74 which encompasses the sides and the bottom of the product. The corrugated web consists of a fibrous web layer 76 and another layer 78 which layer has a higher capillary pressure than the fibrous web layer 76. Superabsorbent 75 is placed in the pockets created by the base of the corrugations of the web and the liquid-impermeable backing 74. The superabsorbent is substantially trapped in this pocket. The overwrap 72 provides the facing on the lower surface in the drawing.
The facing 72 is placed against the skin of the wearer.

These and other pro~ucts such as incontinent pads, wound dressings and the like may be prepared in accordance with the present invention.

In the absorbent products of the present invention, the corrugated fibrous web consists of one or two or more layers. The fibrous web layer initially receiving the liquid void is the fibrous layer of the corrugated fibrous web having the lowest capillary pressure. The requirement ~ZS33ZO

for this fibrous web layer is the ability to accept liquid rapidly and at the same time to maintain the void volume, even with body weight pressure applied, until the remaining portions of the structure substantially drain the liquid from this first fibrous web and begin transporting the liquid away to another part of the product. Draining of the liquid from the first fibrous web generally is accomplished by immediate contact, by the first fibrous web layer, with a higher capillary pressure region in the form of a second layer, united with, but discrete from the first fibrous layer. The higher capillary pressure of the second layer provides the means for draining a substantial portion of the liquid load from the first fibrous layer and the higher capillary pressure also assists in transporting the liquid from the void zone to another part of the product. In the ~eantime, the superabsorbent associated with the second layer is absorbing liquid and swelling either within the corrugations or the zone in which the superabsorbent was placed.

What appears to be only a s~all difference in capillary pressure, is all that is requireA for the second layer to attract and drain the first fibrous layer of liquid the latter has received. The force causing a liquid to enter a cylindrical capillary is expressed by the equation:

P - (2v cos e) r wherein the force is represented by the capillary pressure and:

P is the capillary pressure, v is the surface tension of the liquid, e is the liquid-fiber contact angle, and JBD-32 r is the capillary radius.

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With a given liquid, the pressure (capillary force) increases with the cosine of the liquid-fiber contact ang~e (reaching a maximum where the angle is zero) and also increases with narrower capillary radii so that narrower capillaries will draw liquid from the wider ones.

The relative wickability between the first fibrous layer and the second layer is affected by both the relative densities of the layers and the relative wettability of the individual fibers in each layer. The individual fibers of the second layer have substantially smaller liquid-fiber contact angles than those of the first fibrous layer overcoming the density difference and providing a significant overall increase in capillary pressure to absorb liquid into the second layer.

The second layer fibers (or particles) and the density of the layer are selected to create the small, but significant difference in capillary pressure from the first fibrous layer.

mhe first fibrous layer is preferably a fibrous web which is of substantially high loft and which upon dry co~pression, followed by release, has a tendency to return substantially to its original thickness. For instance, fibrous webs formed from synthetic staple fibers such as polyethylene, polypropylene, polyester, nylon, bi-component fibers, mixtures thereof, and the like are particularly suitable. ~owever, cellulosic fibers such as rayon may be used. Generally, the fibers are carded to form a web which is then stabilized if needed.
Stabilization may be achieved by heat-through bonding, adhesive bonding, point embossing with heat or adhesive or both, and the like. The stabilizing process is selected according to the fibers used and the process used to form JBD-32 the web. Other suitable procedures for for~ing a web i;~S3~0 include air-laying, wet-laying, spun-bonding, laying of melt blown fibers and other known techni~ues. The fibrous web before corrugation preferably has a dry bulk of at least about 10 cc per gram and a weight less than about 4 ounces per square yard.

In one embodiment, a blend of staple polyester fibers with a minor portion of fusible fibers, such as lower melt polyester fibers, are air-laid to form a web. The web is subsequently lightly bonded by passing hot air through the fibers making the fusible fibers tacky so as to stick to each other and the staple fibers, to provide the desired degree of integrity to the web structure.

The second fibrous (or particle) layer is generally comprised of fibers having a lower liquid-contact angle or a layer having a narrower capillary radii, or both.
~xamples of such fibers include hydrophilic fibers such as rayon fibers, cellulosic fibers, or peat moss, or mixtures thereof, or acrylic fibers, or the like. Cellulosic fibers inclucle woodpulp fibers, cotton linters and the like.

- The woodpulp fibers generally are those that are used to form the fluff or fibrous batt layer in conventional absorbent products such as disposable diapers, sanitary napkins, etc. Other cellulosic fibers that might be used are rayon fibers, flax, hemp, jute, ramie, cotton, and the like. The fibers, or peat moss, or mixtures thereof are placed in such a way as to form a layer in which the particles are close to one another so as to promote wicking of liquid in the plane of the layer.

The second layer can be preformed and placed next to the first fibrous layer or, the particles (fibers or peat moss 12s33z~

or mixtures thereof) can be air-laid or wet-laid onto the first fibrous layer before the transverse folding or corrugating takes place.

Corrugating or transverse folding of the web, whether the web be one, two or more layers, is provided by known procedures such as that exemplified in U.S. Patent 4,111,733.

After or during corrugating, the fibrous web, whether it be a one or two layer structure, is stabilized to prevent the corrugations from pulling apart and flattening out.
~ne method of stabilizing the web is accomplished by using adhesive binders which may be a latex resin or other adhesive. A typical way to stabilize the corrugated material is to spray an adhesive on one corrugated surface thereof. Generally, the surface selected for the stabilizing is the surface opposite that which will receive liquid initially. Thereby, the non-stabilized surface is open and available to receive fluids. Another method of stabilizing the web is provided by adding a minor portion of fusible fibers to the fiber blend which forms the corrugated fibrous web. The corrugated web is _ subjected to temperatures sufficient to substantially melt the fusible fibers, thereby providing light, but sufficient, bonding between the corrugations.

Any additional layer~ provided in the corrugated fibrous web generally are comprised of fibers (or in the case of peat moss, particles), which when placed in the form of a layer provide a higher capillary pressure than the capillary pressure of any layer preceding it. As a result, each subsequent layer brings liquid from the previous layer and tends to wick the liquid away from the receiving zone. To summarize, the second or subsequent fibrous layer is generally comprised of fibers having a lZS332~

lower liquid-contact angle or wherein the layer has a narrower capillary radii or both.

The superabsorbent associated with the corrugated fibrous web is generally a water-insoluble but water-swellable polymeric substance capable of absorbing water in an amount which is at least 10 times the weight of the substance in dry form. The superabsorbent material is in the form of particles, or fibers, or spheres, or bits of film, or qlobules or the like. In addition, the superabsorbent may be formed in situ by spraying a liquid monomer solution onto the fibrous web and subsequently polymerizing and cross-linking the monomers to provide the water-insoluble, water-swellable polymeric substance.
One type of suitable superabsorbent in the form of particles or fibers may be described chemically as having a backbone of natural or synthetic polymers with hydrophilic groups or polymers containing hydrophilic groups being chemically bonded to the backbone or an intimate admixture therewith. Included in this class of materials are such modified natural and regenerated polymers as polysaccharides including, for example, cellulose and starch and regenerated cellulose which are modified by being carboxyalkylated, phosphonoalkylated, sulphoalkylated or phosphorylated to render them highly hydrophilic. Such modified polymers may also be cross-linked to improve their water-insolubility.

These same polysaccharides may also serve, for example, as the backbone onto which other polymer moieties may be bonded by graft copolymerization techniques. Such grafted polysaccharides and their method of manufacture are described in U.S. Patent No. 4,105,033 to Chatterjee et al. and may be described as polysaccharide chains having S33~Q

grafted thereon a hydrophilic chain of the general formula:

~CH2) - CR1 1 ~CH2) - CR2 L ~ r L C = 0 ~

wherein A and B are selected from the group consisting of -oR3,-o (alkali metal), -OHNH3, - NH2, wherein Rl, ~2and R3 are selected from the group consisting of hydrogen and alkyl having 1 to 4 carbon atoms, wherein r is an integer having a value of 0 to about 5000 or more, s is an integer having a value of 0 to about 5000 or more, r plus s is at least 500, p is an integer having a value of zero or 1 and q is an inte~er having a value of 1 to 4. The preferred hydrophilic chains are hydrolyzed polyacrylonitrile chains and copolvmers of polyacrylamide and polysodium acrylate.

In addition to modified natural and regenerated polymers, the hydrocolloid particle component may comprise wholly synthetic hydrophilic particles. Examples of those now known in the art are polyacrylonitrile fibers which may be modified by grafting moieties thereon such as polyvinyl alcohol chains, polyvinyl alcohol itself, hydrophilic polyurethane, poly(alkyl pho5phonates), partially hydrolyzed polyacrylamides ( e . g ., poly(N-N-dimethyl acrylamide), sulfonated polystyrene, or a class of poly(alkylene oxide). These highly hydrophilic synthetic polymers may be modified by other chemical treatments such as cross-linking or hydrolysis. Further examples known in the art are the non-ionic hydrophilic polymers such as polyoxyethylene, polyoxypropylene and mixtures thereof JB~-32 izs~

which have been suitably cross-linked, either chemically or by irradiation~ Still another more recent type is a derivative of isobutylene-maleic anhydride copolymer.

Hydrophilic polymers formed from water-soluble acrylate monomers, such as sodium, potassium, ammonium (or combinations of cations), acrylate, may be placed on the absorbing layer by spraying or otherwise placing a solution thereon followed by polymerization and cross-linking, for example, by irradiation.

Other suitable superabsorbent includes naturally occurringmaterials such as gums, and the like. Guar gum acacia gum and locust bean gum are examples of suitable gums.
The superabsorbent is associated with the second layer sufficiently that liquid entering the layer will be placed in contact with the superabsorbent. If the superabsorbent is a powder, it may be sprinkled on the fibrous web either in dry form or the web or superabsorbent may be moist. If the superabsorbent is in granular form, it may be desirable to slightly moisten the superabsorbent before placing it in contact with the web. The superabsorbent will contain particles or globules etc. which range in size from about 0.005 millimeters in diameter to globules that may be continuous along fibers for a distance up to several inches. The superabsorbent may be incorporated within the fibrous web structure before corrugation or it may be added to the product subsequently by placing it along the folds of the corrugation. In addition the superabsorbent may be placed between the multiple layers of the corrugated web before corrugation, if desired, or between the corrugated web and the liquid-impermeable backing.

iZ53320 The web corrugations range from about three to about six or even eight per inch of corrugated web. The corrugated web is generally from about 1/4 to about 3 inches preferably from about 1/2 to about one inch thick.
It has been found that using a corrugated web as the provider of void volume to contain body fluids has many advantages. For instance, fibers may be used to form the web that in the non-corrugated web form do not have enough wet resilience to retain void volume when the web becomes wet. Corrugating of the web provides the highly desirable resilience in the product that is required to initially accept and hold a high volume of fluid. Also it has been found that superabsorbent may be randomly distributed in small or large quantities within the web with surprisingly high utilization of the superabsorbent. It is theorized that the wet resilience of the corrugated web permits the void volume to remain available almost in totality when large quantities of fluid are present in the web. This would permit the superabsorbent to swell, as it captures the liquid, without substantial inhibition.

In one embodiment of the present invention, a blend of staple polyester fibers with a minor portion, about 10-15 percent, of fusible fibers, such as lower melt polyester fibers, are carded to form a web. The web is corrugated and then subsequently lightly bonded by p~ssing hot air through the fibers making the fusible fibers tacky so as to stick to each other and the staple fibers, to provide the desired degree of integrity to the web structure. The superabsorbent is then placed in the pockets of the corrugated web and the corrugated web is fixed in placed on a polyethylene film which provides a liquid-impermeable barrier. A facing which is a polyester nonwoven having a thickness of about 5 mils and weighing about 0.7 ounce per sq. yd. is placed on the surface of the corrugated web ;125~}3Z~

opposite the polyethylene sheet; and the polyethylene film and the polyester nonwoven are adhered to each other on the outside edges of the product.

The superabsorbent generally is present in an amount between 10~ and about 100% by weight of the fibrous web.
Preferably, the superabsorbent is present in an amount from about 50~ to about 90% by weight of the fibrous web.
The web generally is corrugated such that the height or thickness of the corrugated web is from about 1/4 to about

3 inches preferably about 1/2 inch to one inch and contains about 4 folds per inch of corrugated web.
However, the corrugated web may contain as few as two folds up to about 10 folds per inch of corrugated web depending on the thickness of the web prior to corrugation and the height of the corrugated web.

~uitable liquid-permeable facings include a nonwoven fabric having a high degree of moisture permeability. For example, the fabric may be polyester, polyethylene, polypropylene, nylon, rayon, or the like. Preferably, the fabric used for the facing is a light-weight fabric in the range of ~.3-5.0 ounce per sq. yard and with a density _ less than about 0.2 grams per cc. The most suitable fabrics have unusually high elongation, loft, softness, and drape characteristics. Though the facin9 is liquid-permeable, it is preferably of the type, which, after permeation of the liquid, prevents strike-back of the body fluid when the absorbent product is approaching saturation.

Suitable liquid-impermeable barriers include films which are solid films such as polyethylene, polypropylene, and the like and breathable films which do not allow liquid to pass therethrough. The films generally are inexpensive, relatively thin, and flexible.

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Examples of methods of preparing the absorbent product of the present invention are as follows. These examples are not intended to be limiting in any way and extensions and modifications thereof without departure from the spirit and scope of the invention will become apparent from these examples.

Example I

A fibrous web is formed of polyester fibers, the fibers being staple fibers except for about 10-15% of fusible polyester fibers, the latter having a melting point of about 275F. The web is formed by carding the fibers.
The web is heat-bonded lightly by passing air, having a temperature of about 275F., through the web for a few seconds. The resulting web is about 25 grams per sq. meter basis weight. The specific polyester fibers used are identified as type 676 Dacron, and type 5~1 Dacron fibers manufactured and sold by E.I. duPont &
Company. The flexible longitudinal web is subjected to corrugating in accordance with the procedure set forth in U.S. Patent 4,111,733 and subjected to heat to a temperature of about 275F. during or subsequent to _ corrugation in order to again render the fusible fibers sufficiently tacky to adhere to themselves and to the staple fibers of the web in order to stabilize the corrugatefl web.

The corrugating provides a final product having a thickness of approximately 3/4 inch and which weighs about 13 oz. per yd. in its corrugated form. There are approximately four corrugations per inch. A powdered superabsorbent polymer is uniformly sprinkled into the pockets created by the corrugation of the nonwoven polyester fibrous web. The superabsorbent is present at a concentration of about 400 grams per sq~ meter of web.

lZS~3;20 The particular superabsorbent used is identified as Permasorb #10, manufactured by National Starch and Chemical Corporation. The corrugated fiber web containing the superabsorbent is placed on a polyethylene film wherein the film extends at least one inch beyond the corrugated web on each side of the web. Polyester facing in the form of a nonwoven polyester fiber web having a weight of about 0.7 oz/sq. yd is placed over the corrugated web and extends beyond it on all sides by at least one inch. The polyethylene backing and the polyester facing are adhered to each other by use of hot - melt adhesive on all four sides to provide a unitary disposable absorbent product. The product, when prepared in a size of approximately 12 in. by 12 in., will hold up to about 200 mililiters of urine when the urine is discharged onto the facing at least about 3 inches from the edge of the product.

Example II
The same polyester fibrous web formed in Example I is subjected to flooding with an aqueous solution of 38%
solids, the solution solids being 90~ sodium acrylate and 10~ acrylic acid. The resulting flooding substantially coats the fibers of the web with the aqueous solution.
Vacuum in the amount of 1 inch of mercury is used to draw the excess solution from the web. The web is then subjected to 6 megarads electron beam radiation after which about 70 grams per sq. meter of polysodium acrylate is present. The web is again flooded suhjected to vacuum and irradiated with 6 megarads of electron beam radiation to yield a total of about 140 grams per sq. meter of polysodium acrylate. After flooding a third time with the same monomer solution and after the vacuum treatment, the web is subjected to 12 megarads of electron beam radiation which polymerizes and cross-links the monomer and forms - 125332() polysodium acrylate substantially affixed to the polyester fibers of the web. Approximately 200 grams/sq. meter of polysodium acrylate is present in the substrate. This is equivalent to about 800% dry-add-on.
s Staple acrylic fibers are deposited on the polyester web so as to create an intimate layer having a weight of about 30 grams/sq. meter of acrylic fibers. The two-layer web is subjected to heat-through bonding wherein the fusible fibers in the polyester web assist in at least partially uniting the acrylic fiber layer to the polyester web. The two-layer flexible longitudinal web is then subjected to corrugating again in accordance with the procedures set forth in U.S. Patent NO. 4,111,733. Following corrugating, the web is stabilized in its corrugated form by spraying an elastomer solution onto the surface wherein the acrylic fibers are at the peaks of the corrugation.
The aqueous dispersion of the elastomer is cured and the product is thereby stabilized. The corrugated product is placed on a liquid-impermeable diaper backing and a facing is placed on the other surface. The backing and facing are united in the margins by known procedures. Tape tabs are then applied at one end of the diaper to provide a disposable diaper product which will receive and retain up to about 300 milliliters of urine.

Exam~le III

The corrugated web prepared in Example II is placed in a sanitary napkin so that the corrugations are parallel to the longitudinal axis of the sanitary napkin product. The liquid barrier is a polyethylene film and the overwrap is a polyester nonwoven fabric as described above. Adhesive lines are placed on the under side of the product and release film strips are placed over the adhesive lines.

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Upon removal of the release film strips, the product is readily adhered to the underclothing of the user.

Other methods for preparing the corrugated fibrous web and combining the superabsorbent and preparing a finished product may be used.

From the foregoing it will be observed that numerous variations and modifications may be effected without departing from the true spirit and scope of the novel concept of this invention.

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Claims (19)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An absorbent product comprising a corrugated fibrous non-woven web of synthetic resilient fibers having associated therewith at least about 10 percent by weight of said web of superabsorbent; a liquid-impermeable barrier covering at least one side of said web; and a liquid-permeable facing covering at least the other side of said web, said corrugated web being stabilized to retain its transverse folds when wet, said web having a high capillary pressure to provide preferential attraction and wicking of liquid.

2. The absorbent product of claim 1 wherein the super-absorbent is present in an amount between about 10 percent and about 150 percent by weight of said web.

3. The absorbent product of claim 1 wherein the super-absorbent is present in an amount from about 50 percent to about 90 percent by weight of said web.

4. The absorbent product of claim 1 wherein said super-absorbent is substantially affixed to the fibers of said corrugated fibrous web.

5. The absorbent product of claim 1 wherein the super-absorbent is placed in the folds of the corrugated web.

6. The absorbent product of claim 1 wherein the super-absorbent is placed between the corrugated web and the liquid-impermeable barrier.

7. The absorbent product of claim 6 wherein said super-absorbent is affixed to said liquid-impermeable barrier.

8. The absorbent product of claim 1 wherein said fibrous web has a dry bulk recovery of at least about 30 percent, and initial dry bulk of at least about 10 cc per gram and a weight less than about 4 oz./sq. yd. prior to corrugation.

9. The absorbent product of Claim 1 wherein said fibrous web is a nonwoven fibrous web.

10. The absorbent product of Claim 1 wherein the fibers of said fibrous web are synthetic, staple, resilient fibers.

11. The absorbent product of Claim 1 wherein the fibers in said fibrous web are selected from the group consisting of polyethylene fibers, polyester fibers, polypropylene fibers, polyamide fibers and mixtures thereof.

12. The absorbent product of Claim 1 wherein the fibers of said fibrous web are bicomponent fibers.

13. The absorbent product of Claim 1 wherein a second layer is discrete from but united to said fibrous web and substantially coextensive therewith, said second layer being denser than said fibrous web to provide preferential wicking of liquid in said second layer.

14. The absorbent product of Claim 13 wherein the super-absorbent is between said fibrous web and said second layer.

15. The absorbent product of Claim 1 wherein said corrugated fibrous web is stabilized by use of adhesive.

16. The absorbent product of Claim 1 wherein said corrugated fibrous web is stabilized by use of low melt fibers distributed in said fibrous web.

17. The absorbent product of Claim 1 wherein the product is a disposable diaper.

18. The absorbent product of Claim 1 wherein the product is a urinary pad.

19. The absorbent product of Claim 1 wherein the product is a sanitary napkin.