Absorbent article with elastic liner for waste material isolation

Abstract: A disposable absorbant article, such as a diaper (10), having a liquid impervious backsheet (14), a urine pervious liner (12), and absorbent core (18) intermediate the backsheet (14) and liner (12) is disclosed. The liner (12) has a passageway (22) to allow communication of solid waste materials to the core (18), thereby isolating such waste from the skin of the wearer. The liner (12), is at least partially composed of elastic panels. The elastic panels register the passageway (22) with the anal opening to minimize the size of the passageway and prevent unnecessary exposure of the skin to the solid waste materials.

Description: TECHNICAL FIELD The present invention relates to disposable absorbent articles, and more particularly to disposable absorbent articles having a lining to isolate fecal material from the skin of the wearer. BACKGROUND OF THE INVENTION Several attempts within the art relating to disposable absorbent articles have been made to isolate fecal waste from the wearer. Fecal material which reposes against the skin is often a source of epidermal irritation and makes cleaning of the wearer more difficult. One attempt is given by U. S. Pat. No. 2,690,749 issued to Nelson, October 5, 1954, which discloses a diaper having separate recesses to accept urine and solid fecal matter. U. S. Pat. No. 2,004,088 issued to Alsop, June 11, 1935 discloses an absorbent pad having a large opening. However, neither reference teaches a means of preventing solid waste materials from contacting the skin of the wearer. U. S. Pat. No. 3,532,093 issued to Lovret, October 6, 1970, discloses a diaper having separate compartments for the collection of urine and fecal matter. However, this diaper does not have an absorbent core and would therefore be somewhat uncomfortable to the wearer. An attempt to overcome these problems is disclosed in U. S. Pat. No. 4,662,877 issued to Williams, May 5, 1987, which discloses a diaper having an inelastic urine impervious facing sheet with an aperture to allow waste materials to pass through the facing sheet into the absorbent portion of the diaper. Williams teaches applying longitudinally oriented elastic strands on either side of the aperture. SUMMARY OF THE INVENTION It is an object of this invention to obviate the aforementioned problems related to fecal material reposing against the skin of the wearer of a disposable absorbent article. The invention comprises a disposable absorbent article having a longitudinal axis, said article comprising: a urine impervious backsheet; a longitudinally elastically contractible liner having at least one passageway through said liner adapted to permit waste materials to pass through said liner, said liner being at least partially peripherally affixed to said backsheet; and an absorbent core intermediate said liner and said backsheet, wherein said liner is formed at least in part of an elastic fabric and is foreshortened relative to said backsheet to form a void space in registry with said passageway, and disposed intermediate said liner and said backsheet. Wherein said liner comprises a tresection ecompassing the passageway of a first material and two panels made of a second material, the trisection being longitudinally centered intermediate the panels, the second material being of the elastic fabric, and the first material being substantially non-elastic. BRIEF DESCRIPTION OF THE DRAWINGS While the Specification concludes with Claims particularly pointing out and distinctly claiming the subject matter of the invention, it is believed the invention will be better understood from the following description taken in conjunction with the accompanying drawings wherein like parts are given the same reference numerals. Figure 1 is a top plan view, the core being shown in phantom; Figure 2 is a vertical sectional view of the diaper of Figure 1 when assembled about a wearer in the standing position, not shown, showing the void space between the liner and core; Figure 3 is a top plan view of a diaper having a urine impervious liner, the core being shown in phantom; The embodiments of Figures 1, 2 and 3 do not form part of the present invention. Figure 4 is a top plan view of a disposable diaper 1 according to the invention. DETAILED DESCRIPTION OF THE INVENTION A disposable article made according to the present invention is typically a diaper, but could also be a catamenial pad, a product for incontinent adults or any other execution known to those skilled in the art. The disposable article disclosed herein can be manufactured and prepared using methods and materials well known in commercial practice. The diaper described herein is suitable for infants of either sex weighing from approximately 5kg. to approximately 11kg. It is contemplated that various sizes of wearers will be able to use the diaper of this invention, providing it is properly scaled to the size of the wearer. Figure 1 is a top plan view of an unfolded and flattened diaper 10 having the basic components typical of such an absorbent article comprising an elastic liner 12, a backsheet 14 and absorbent core 18. The diaper 10 comprises a laminated structure having a generally hourglass shape in the flat, unfolded position. The diaper 10 is generally symmetric about a longitudinal axis oriented from the front to back of the diaper 10, which axis is generally aligned with the machine direction of the diaper 10 during manufacture. A transverse axis is orthogonal to the longitudinal axis of the diaper 10, and intersects the longitudinal axis at or near the midpoint of the diaper 10. As used herein, the front and rear portions of the diaper 10 are defined by and coterminous of the transverse axis and are generally the portions of the diaper 10 disposed to the front and rear of the diaper 10 as observed by the wearer. The diaper 10 comprises a backsheet 14 which is preferably urine impervious and flexible. An opaque polymer sheet is often utilized. The backsheet 14 provides a chassis for assembly of the diaper 10 about the arcuate posterior of the wearer and which holds the other diaper components hereinafter discussed. The backsheet 14 is sized to be drawn between the legs of the wearer and fastened about the waist using tapes 42 disposed at the back of the backsheet 14. A diaper 10 generally constructed according to the teachings of U.S. Pat. No. 3,860,003, is suitable. A low density polyethylene sheet of thickness from 0.01mm to 0.3mm. is typical, with a thickness of about 0.03mm. being preferred. A backsheet 14 having a longitudinal dimension of 45cm., a transverse dimension between either end of the longitudinal edges 16 of 32cm. and a transverse dimension at the center of the longitudinal edges 16 of 20cm. is suitable. Juxtaposed with the backsheet 14, towards the skin of the wearer, is a urine absorbent core 18, which is generally soft, conformable and compliant. The core 18 comprises any urine absorbent material such as cellulose fibers, and is typically comminuted cellulosic fiber, often known as air felt. The core 18 may be elasticized or padded and further comprise absorbent gelling polyacrylate materials to increase the core capacity. The core 18 is designed to absorb and retain the expected volume of liquid discharge for the article's intended use, wear time and capacity. For the embodiment described herein, the core 18 should preferably have a minimum capacity of 300ml., to accommodate urine discharges of the wearer. The core 18 may be generally rectangular, having two opposed faces of length from 35 cm to 40 cm and of width from 10 cm to 15cm. wide, although it will be apparent to one skilled in the art that other shapes or sizes could be used as well. The core 18 is longitudinally shorter than the backsheet 14 to provide a free margin 24 at each transverse edge 26 of the diaper 10. The core 18 may be integrally affixed to the backsheet 14, may be peripherally affixed to the backsheet 14, or not affixed to the backsheet 14. If it is desired to affix the core 18 to the backsheet 14, affixing may be accomplished with any suitable FDA approved adhesive, such as Century 5227 made by Century Adhesives of Columbus, Ohio. It is preferable that the core 18 remains intact, in position and not clump, break up or experience undue variations in thickness, otherwise discomfort to the wearer and uneven absorption capacity might result. To provide stability to the core 18, and prevent such disturbances to core 18 uniformity from occurring, the core 18 may be tightly covered with an envelope 20. The envelope 20 may cover either or both faces of the core 18 and be peripherally or integrally affixed to the backsheet 14, using the aforementioned adhesive. The envelope 20 may be made of any urine pervious material, such as spun bonded or carded polyethylene or polypropylene fabric having a caliper of 0.25mm. and a basis weight of 16.7 gm. per sq. m. Juxtaposed with the absorbent core 18 (or envelope 20, if included), towards the wearer, is a urine pervious, generally nonabsorbent elastic liner 12. The liner 12 is soft and nonirritating to the skin. As used herein, a liner 12 is considered urine pervious if it has a zone or portion of the liner 12 which is specifically adapted to permit urine, but generally not solid fecal material, to pass therethrough, even though a portion or zone of the liner 12 may be urine impervious. The elastic liner 12 may be made of an elastomeric fiber nonwoven thermoplastic polyurethane elastomer spun bonded fabric or an in-elastomeric fiber knitted fabric. If an elastomeric fabric is selected, it preferably does not resemble the feel of natural rubber when placed against the skin. Kanebo fabric made by the Kanebo Company of Osaka, Japan and having a basis weight between 25 and 35g. per sq. m. and a thickness between 0.11 and 0.21mm has been found suitable, with a basis weight of 25g. per sq. m. being preferred. If a knitted fabric is selected, nylon as commonly used to manufacture women's stockings is suitable. A fabric of nylon or Antron/Lycra made by the Du Pont Company of Wilmington, Delaware and having a basis weight of 80g. per sq. m.. has been found to work well. The liner 12 is longitudinally contracted, or foreshortened, to enhance the conformability and shaping of the liner 12 to the buttocks of the wearer. The magnitude of the longitudinal contraction should be great enough to provide a snug fit, and maintain this fit during various motions of and throughout the period worn by the wearer. However, the magnitude of the longitudinal contraction should not be so great as to cause marking or irritation of the wearer's skin. If the Kanebo fabric is selected, the liner 12 may advantageously have from 75 to 100 percent elongation in the uncontracted state and work well in the diaper 10 disclosed above. If the knitted nylon is selected, the liner 12 may advantageously have about 110 percent elongation in the uncontracted state. As known to one skilled in the art, both elastomeric fiber nonwoven materials and inelastic fiber knitted materials provide elasticity, however achieve it in different manners. It is known that in the former case elasticity is achieved through the stretching of elastomeric fibers while in the latter case the fibers are knit to achieve elasticity. It is further recognized that either type of material is available with biaxial or uniaxial elasticity. One principal axis of elasticity is preferably oriented generally parallel to the longitudinal axis of the diaper 10. The liner 12 may generally correspond in size and shape to the backsheet 14. The liner 12 is at least partially, and preferably fully, peripherally affixed to the backsheet 14, laminating the core 18 intermediate the liner 12 and backsheet 14. The liner 12 may be affixed to the backsheet 14 using any well known method such as adhesive affixing, thermal sealing or ultrasonic welding. The liner is considered to be affixed to the backsheet 14 if the liner 12 is directly attached to the backsheet 12 (as shown) or indirectly attached to the backsheet 14 through a separate component. Associated with the liner 12 is a passageway 22 which permits communication of waste materials, particularly including but not limited to solid fecal materials, through the liner 12 and into the region of the absorbent core 18, thereby isolating the waste materials from the skin of the wearer. In a preferred embodiment, the passageway 22 takes the form of an aperture. As used herein, a passageway is any opening which is sufficient to permit fecal material to pass through the liner 12 without significant obstruction. As used herein the term aperture includes but is not limited to holes, slits and combinations thereof. Preferably the aperture is an oblong hole having a doubly convex shape. The size of the passageway 22 is a balance between the minimum size necessary to accommodate variations in the placement of the anus relative to the perineum and various cross sections of solid fecal material, while minimizing undue skin contact with the waste material. It is preferred that the passageway 22 have a greater longitudinal than transverse dimension, to ensure registration with the anal opening when the diaper 10 is placed in various longitudinal alignments on the infant. An aperture having a longitudinal dimension of about 4.0cm. to about 6.5cm., and a transverse dimension between about 1.5cm. and about 6.0cm. is suitable. The aperture is generally transversely centered on the liner 12 and longitudinally offset at least about 1cm. towards the back of the diaper 10. The liner 12 preferably has an inelastic area, referred to as a free margin 24, at each end of the diaper 10 intermediate the transverse edge 26 of the core 18 and the transverse edge 26 of the backsheet 14. This arrangement reduces liner wrinkling and contraction in the free margin 24 areas, providing more comfort to the user and reducing leakage around the waist of the diaper 10. Also, by making the elastically contracted portion of the liner 12 shorter than the backsheet 14, the diaper 10 will bow concave towards the liner 12 when the liner 12 and backsheet 14 are affixed, creating a frame suitable to accommodate the arcuate posterior of the wearer. For a backsheet 14 having a length of 45cm., as described above, a liner 12 having a longitudinally elastic portion ranging in longitudinal dimension from 23cm. to 36cm. is typically suitable. The longitudinally contracted elastic is disposed longitudinally nonadjacent the passageway 22. As used herein, longitudinally nonadjacent refers to any portion of the liner 12 which is displaced from the passageway 22 towards either transverse edge 26 of the diaper 10. Alternatively stated, any point on the liner 12 through which a line parallel to the transverse axis can be drawn without intersecting the passageway 22 is longitudinally nonadjacent the passageway 22. Without being limited to any theory of operation, it is believed this arrangement causes the liner 12 to better conform to the complex curvatures of the buttocks of the wearer and obviates longitudinal collapse of the passageway 22. Furthermore, it is believed this arrangement aligns the passageway 22 to the anal opening of the wearer and provides for affixing of the liner 12 against the skin of the wearer. A liner 12 having both front and rear elastic panels, one disposed longitudinally on either side of the central trisection (32) is provided. As shown in Figure 2, when worn, ideally the longitudinally contracted diaper liner 12 will generally conform to the wearer, while the larger radius of curvature of the absorbent core 18 will allow the core 18 to fall away from the liner 12 and create a void space 28 thereinbetween. Alternatively stated, the differential radii of curvatures creates a shallow hole in the absorbent core 18 to collect waste materials and isolate the collected materials from the wearer, preventing epidermal irritation. The volume of void space 28 is not critical, so long as at least 90gm. of fecal material can be accommodated. Likewise, the void space 28 shape is not critical, and indeed will be irregular. Preferably the liner 12 is not affixed to the core 18 near the vicinity of the passageway 22, otherwise the capacity of void space 28 may be substantially reduced. If desired, the urine acquiring zone of the liner 12 may be adhered to the core 18 to promote urine transmission through the liner 12. In Figure 3, a urine impermeable elastic liner 12 is provided. The liner 12 is preferably made of any such material known in the art and has the characteristics and physical properties described above. One material which works well is the elastic fabric having inelastic fibers disclosed in U.S. Patent No. 4,107,364. A liner 12 having an elongation of 25 percent in the uncontracted state works well. Alternatively, a Kanebo fabric liner 12, described above, having a basis weight ranging from 75 to 100 g per sq. m. is urine impervious, and works well with an elongation of from 50 to 75 percent in the uncontracted state. To obviate urine from being intercepted and retained against the skin by the liner 12, a larger passageway 22 to accommodate both genitals and permit urine to communicate to the core 18 is provided. A convexly rectangular aperture having a maximum longitudinal dimension of from 12cm. to 23cm. and a transverse dimension of from 6cm. to 10cm. is suitable, with a longitudinal dimension of 18cm. and a transverse dimension of 8cm. being preferred. To position the front edge of the passageway 22 outwardly of the genitalia, the hole is longitudinally offset towards the front of diaper 10. A longitudinal offset of 1.6cm. towards the front of the diaper 10 works well for the embodiment described herein, as illustrated in Figure 4, a liner 12 having front and rear panels 30 made of an elastic material, and a longitudinally centered inelastic trisection 32, intermediate and adjacent the elastic panels 30 and encompassing the passageway 22 may be used. This variant provides the advantage that the inelastic liner panel 32 adjacent the passageway 22 may be somewhat stiffened, as described below, to maintain the passageway 22 in an open condition while the diaper 10 is in use. The elastic panels 30 of such an execution may be limited to the centrally transverse portions of the panels 30, and particularly may coincide with the transverse extent of the passageway 22. However, as shown, for the diaper liner 12 illustrated in Figure 4 it is not necessary that any one trisection have an area or a length equivalent to those of any other given trisection or be symmetric about either axis. As described above, the elastic and inelastic panels may be joined by any means commonly known to those skilled in the art including adhesive affixing, thermal sealing, and ultrasonic welding. It is preferred that the juncture of the adjacent panels not have a seam which will abrade or irritate the wearer. It will be apparent to one skilled in the art that other sizes and shapes of passageway 22 apertures are feasible to permit waste materials to pass through the liner 12. For example, a diamond shaped aperture of the aforementioned dimensions and having the corners oriented in the longitudinal and transverse directions is suitable. An aperture such as a slit having a longitudinal dimension ranging from 4.0cm. to 6.0cm. and a transverse dimension of 0.5cm. may be used. If the diaper 10 is to be scaled for a larger infant, a larger passageway 22 disposed closer to the rear of the diaper 10 may be desirable. All such passageways 22 are within the scope of the invention. If desired, the portion of the liner 12 near the passageway 22 may be reinforced to prevent tearing or wrinkling. Reinforcement may be accomplished by providing a double thickness of the liner 12 material in a band adjacent and concentric of the passageway 22 and having a radial dimension of from 1.0cm. to 2.0cm, Alternatively, the passageway 22 may be elasticized such that it is smaller in size until solid fecal material passes through. Elasticization may be provided by circumscribing the passageway 22 with an elastic strand. Elastic strands having an untensioned generally rectangular cross section ranging from 2.4mm to 6.4mm by 0.2mm, an elastic modulus of 125,000 kg. per sq. m. at from 100 to 200 percent elongation are suitable. The elastic strands may advantageously have from 50 to 100 percent elongation in the uncontracted state, with higher elongations being generally preferred for holes of greater circumference. Fulflex 9411 strands made by the Fulflex Company of Scotland Neck, North Carolina have been found to work well. If desired, a transverse contracting means may be incorporated into the panels of liner 12, for example by orienting a principal axis of elastic contraction in any nonlongitudinal orientation. This method is feasible for both biaxially elastic and uniaxially elastic materials. The magnitude of the transverse contraction is not critical, but may be used to generally neutralize any lateral necking which occurs due to the longitudinal contraction. If a knitted nylon fabric having a longitudinal uncontracted elongation of about 110 percent is used, a transverse contraction increasing from about 10 percent at the transverse edges of the liner 12 to about 190 percent at the center of the liner 12 has been found to work well.

Claims: A disposable absorbent article (10) having a longitudinal axis, said article comprising: a urine impervious backsheet (14); a longitudinally elastically contractible liner (12,30,32,34,36,38,40) having at least one passageway (22) through said liner adapted to permit waste materials to pass through said liner (12), said liner being at least partially peripherally affixed to said backsheet (14); and an absorbent core (18) intermediate said liner (12) and said backsheet (14), characterised in that said liner (12) is formed at least in part of an elastic fabric and is foreshortened relative to said backsheet (14) to form a void space (28) in registry with said passageway (22), and disposed intermediate said liner (12) and said backsheet (14) and wherein said liner (12) comprises a trisection (32) encompassing the passageway (22) made of a first material and two panels (30) made of a second material, said trisection (32) being longitudinally centered intermediate said panels (30), said second materials being of said elastic fabric, and said first material being substantially non-elastic. A disposable absorbent article according to Claim 1 wherein said passageway (22) is an aperture. A disposable absorbent article according to Claim 2 wherein said aperture (22) has a greater longitudinal dimension than its transverse dimension. A disposable absorbent article according to any one of Claims 1 to 3 characterised in that said article (10) further comprises a means for transverse contraction of the elastic panel of said liner. A disposable absorbent article according to Claim 4 characterised in that said means for transverse contraction of the elastic panel of said liner comprises an elastic fabric panel having a principal axis of elastic contraction oriented in a nonlongitudinal direction.

Inventors: FREELAND MARY ELAINE, FREELAND, MARY ELAINE
Applicants: PROCTER & GAMBLE, THE PROCTER & GAMBLE COMPANY
Application year: 1989
Main classification: A61F13
IPC codes: A61F13