WO1986006623A1

WO1986006623A1 - Absorbent pad

Info

Publication number: WO1986006623A1
Application number: PCT/US1985/000828
Authority: WO
Inventors: Winalee G. Mitchell
Original assignee: Tranquility Products International, Inc.
Priority date: 1985-05-03
Filing date: 1985-05-03
Publication date: 1986-11-20
Also published as: EP0220173A1

Abstract

The absorbent pad (10) comprises a layer (11) of a water-impervious backing material, a water-absorbing layer (12) comprising at least one super-absorbent polymer and a water-pervious sheath (13). The water-absorbing layer (12) is received within the sheath (13) and is movable therein but, prior to use, is frictionally engaged to prevent such movement in normal handling. When the absorbent layer (12) is wet from use its weight makes it easy to move the layer from the sheath (13). Both layers of one end of the sheath (13) are adhered to the backing material (11) adjacent that end. The layers of the sheath (13) are adhered to the backing material (11) at its other end only at the outermost extremities of that end.

Description

ABSORBENT PAD

Technical Field of the Invention Thi s i nvention rel ates to an absorbent pad f or the absorbtion of bodily fluids, and to a method of producing such a pad. The absorbent pad according to the invention compri ses a longitudinally extending layer of a water-impervious backing material , a longitudi nal ly extending water-absorbing layer, and a water pervious sheath. The water pervious sheath is adhered to the layer of backing material and the water absorbing layer is received within the sheath so that relative longitudinal movement between the sheath and the water absorbing layer is difficult when the latter is dry, but easy when it is wet. The pad is particul arly adapted for use i n the care of uri nary incontinence.

Background of the Invention

A variety of attempts have been made to produce absorbent pads suitable for the care of urinary incontinence. Some of the parameters which πust be considered are absorbtive capaci ty and rate, protection against leakage and odor emission, method of disposal and wearer comfort which can i nvolve bulk, weight, exertion of pressure on local ized areas of the skin and relative feeling of dryness. The prior art is inundated with pads incorporating methods of dealing with at least one of these considerations, but is devoid of a pad which deals satisfactorily with al l of them.

United States patent No. 4,293,609 granted October 6, 1981 to Pobert E . Erickson discloses an absorbent laminate comprising a water-swel l abl e or l i ghtly cross-l i nkedhydrophi l ic polymer, preferrably an essential ly water soluble nolyel ectrolyte in the sal t form, and layers of a wicking substrate. Erickson further discloses an absorbent pad comprising the laminate described above, at least one layer of a wicking substrate, a water-impervious bottom sheet and a water-pervious top sheet.

United States patent Ho. 4,176,567 granted December 4, 1979 to Julian M. Herring discloses an absorbent pad comprising an absorbent layer, described as a film of water-swel lable gel-forming cross-linked oolyacrylite polymers mechanically bonded to a crεped substrate, a bottom sheet, a top sheet and any number of layers of filler material . According to the reference, parallel edges of the water-impervious bottom sheet may be folded upwardly and inwardly toward each other and then sealed, the pad being constructed in a manner whereby the ridges in the crened substrate of the absorbent layer direct the flow of liquid deposited therein toward the sealed edges of the bottom sheet.

United States patent no. 3,903,889 granted September 9, 1975 to David Torr discloses a liquid-absorbent product comprising a o articulate liquid-absorbent gel -formi ng material , modified guar gum being preferred, which can be adhered to additional components by means of a water soluble adhesive. The '889 patent further discloses the use of the absorbent product described above with a liquid-pervious body contacting layer and an outer layer, which has been waterproofed at one or both sides, to form an absorbent pad which is described as disposable by flushing in a toilet system.

United States patent No. 3,683,919 granted August 15, 1972 to Myron B. El l s discloses a sani tary napki n havi ng a conventional high wet-strength, non-woven cover which can readily be torn longitudinally into two substantially equal portions to release the absorbent core from the encasing cover thereby permitting flushing away of the core and the cover separately in a conventional water closet. Summary of the Invention

The absorbent pad accordi ng to the i nstant i nvention compri ses a longitudinally extending layer of a water-impervious backing material , a longitudinal ly extending water-absorbi ng l ayer compri si ng at least one super-absorbent polymer that is capable of absorbing at least five times its dry weight of water and a water-pervious sheath, the water-absorbing layer being received within the sheath. Further, a pad in accordance .nth the invention is constructed in a such a manner that the water-absorbing layer is longitudinally movable within the sheath but, pri or to use, i s f rictionally engaged therewith to an extent necassary to prevent such movement i n normal handl ing. When the absorbent l ayer is wet from use its wei ght i s greatl y i ncreased a nd i ts tendency f or l ongitudinal movement is correspondingly increased. Both layers of one end of the sheath are adhered to the backing materi al adjacent that end by means of a heat seal or appropriate adhesive. The layers of the sheath are adhered to the backi ng material at i ts other end only at the outermost extremities of that end. Accordingly, after use, when the pad i s gripped by the ful ly seal ed end and downward motion is imparted thereto toward the partial ly seal ed end and that notion i s suddenly stopped, the absorbent layer is forced by its inertia from its position i n the sheath into a wai ting recent icle. Addi tionally, since the water-absorbent layer comprises water-dispersible components, it may be rienosited as described above into a standard toilet and subsequently flushed away without fear of clogging sewage or septic systems.

Brief Description of the Drawings

Fi gure 1 i s a pl an view of a pad accordi ng to the invention.

Figure 2 i s a bottom plan view of a portion of the pad of Figure 1, namely a sheath with a water-absorbing layer received within the sheath.

Figure 3 is a view, with parts broken away to show details of construction, of the water-absorbing layer of the pad of

Figure 2.

Figure 4 is a view of an alternate water-absorbing layer for a pad according to the invention. Figure is a view of the bottom of the pad of Figure 1. Detailed description of the Invention Referring now in more detail to the drawings, and, in particular, to Figure 1, a pad according to the instant invention is indicated generally at 10. The pad 10 comprises a layer 11 of a water-imperviou s backing material, e.g., polyethylene, a water absorbing layer 12, and a water-pervious sheath 13. The pad 10, the layer 11 and the sheath 13 are substantially coextensive in plan, each extending longitudinally from a first convex end 14 to a second concave end 15; each has generally parallelsides 16 and 17. The water absorbing layer 12 is receivedwithin the sheath 13, having generally parallel sides 18 and 19, and extending longitudinally from a first end 20 to a second end 21. The sheath 13, adjacent its first end 14, i s adhered to the backing material 11 by a heat seal indicated generally at 22 and, adjacent its second end 15,by heat seals indicated generally at 23 and 24, and ispositioned between a first major surface 25 of the backingmaterial layer 11 and opposed edges 26 and 27 thrreof whichextend upwardly and inwardly from the major surface 25.

The first major surface 25 of the backing material layer 11 is seen in Figure 1 where portions of the sheath 13, namely a layer 28 having a major surface 29 and a layer 30 having a major surface 31 (Figure 2) , have been broken away. The major surfaces 31 and 28 (Fiηure 1) constitute second and first major surfaces, respectively, of the sheath 13.

The major surface 25 of the backing layer 11 faces the major surface 31 (Figure 2) of the sheath layer 30 i n the pad 10. The sheath 13 i s composed of a single layer of a polyester, non-woven fiber mat with the edges thereof overlapped as indicated at 32 to form the layer into the sheath 13; i n the pad 10 the sheath 13 i s comoressed adjacent its sides 16 and 17 so that the opposed surfaces thereof constitute apparently separate sheath layers 28 and 30, as previously described.

The water-absorbing layer 12 is composed of a layer 33 of a pleated laminate of at least one cellules ic tissue and a cross-linked starch-acrylic graft copolymer, a cross-linked acryl ic polymer, or a blend of the two which, in any case, is capable of absorbing at least five times its own dry weight of water. The layer 33 is wrapped in three layers 34 of a cellulosic tissue. There are arcuate cuts , as i ndicated at 35, in the pleated laminate layer 33, which form flaps 3fi attached to the laminate layer 33. When the flans 36 are fol ded away from the cuts indicated at 35 there are openings through the laminate layer 33. It has b een f ound that a l ami nate of the type described, particularly when the openings are of optimum size and constitute an optimum proportion of the total surface of the laminate, is pecul iarly effective at picking up and hol ding, even under substantial pressure, the discharge of one who suffers from urinary incontinence.

The water-absorbing layer 12 can be produced as described i n published application PCT/US82/00312, which application also discloses the optimum ratio of open area to total area and the optimum sizing for the openings. Sui table cross-l inked acrylic polymers and methods for their nroduction are disclosed in U.S. patent Mo. 4,117,184, while suitable cross-l inked starch-acrylic graft co polymers and methods for their production are disclosed i n U . S . patent No . 4,076,673. Preferably, the polymers and copolymers are operahle to absorb at least 25, and, most desirably, at l east 40 ml of a 1 percent by wei ght aqueous sodium chloride solution per gram of the polymer or copolymer.

The laminate layer 33 is shown in Figure 4 in an unpleatedcondition. it is composed of upper and lower layers 37 and 33 of a cross-l inked starch-acryli c graft copolymer laminated between two layers of a cellulosic tissue and anintermediate cellulosic tissue layer 39; the layers 37, 38and 39 are adhered together to form the laminate layer 33.The cuts 35 extend all the way through the laminate layer33; the flaps 36 are composed of the three layers.

Prior to use of the pad 10, the water absorbing layer 12 thereof i s comparati vely l i ght, and i s ef fecti vely s upported therei n by the shea th 13 a nd the w a te r impervioius backing material layer 11 with its inturned edges 26 and 27. The layer 12 i s movable longitudinally within the sheath 13, but is sufficiently engaged, frictionally, that such movement does not occur i n normal usage and handling. When the layer 12 is wet from use, however, its weight is significantly increased, perhaps as much aa 40 times, and, as a consequence, its tendency for longitudinal movement is greatly increased. For example, when the layer 12 is wet, the pad 10 can be supported over a toilet by the end 14, with the end 15 pointing toward thetoilet, and moved in the direction of the toilet; upon thesudden stopping of the movement or, in extreme cases a reversal of the direction of movement, the layer 12 will continue to move in the original d irection and wil l fa ll into the toi let for disposal.

A laminate layer 40 is shown in Figure 3. The layer 40 is a ful l equivalent for the layer 33, having cuts 35 and flaps 35, and differing only in that it is composed only of upper and lower layers 41 and 42 of a cross-linked starch-acrylic graft copolymer l ami nated between two l aye rs o f a cel l ul osic ti ssue; the l ayers 41 and 42 are adhered together to form the laminate layer 40

Air lai d sheets of cel lulosic fibers, usual ly of finely ground wood, are Known. It is also known that particles of a super-absorbent polymer can be codepos i ted wi th cel lulosic fibers as they are being formed into sheets by the air-l aying process so that the ultimate product is an air laid cellulosic fiber sheet with the polymer particles distributed therethrough. Such an absorbent sheet can be used in place of the water-absorbing layer 12 of the pad 10. The cellulosic fibers of air laid sheets, however, are comparatively bulky and, therefore, are more likely to clog sewage systems into which they are flushed than are the previously described water-absorbing layers 12. They are, therefore, less desirable for use in a pad according to the instant invention, because easy di sposability by flushing i s an importan t fea ture o f a p ad accordi ng to theinvention. The pad 19 c a n p roduced simpl y by cutti ng th i n polyethylene sheet material to an eppropri ate size and shape, pl aci ng a water porvious sheath wi th a water absorbing layer received therein on the cut sheet, folding edges of the cut sheet over the edges of the sheath, and heat seal ing or gluing the sheath to the cut sheet as indicated at 22, 23 and 24 in Figure 1. The seals indicated a t 22, 23 and 24 not only l ock the sheath to the polyethylene sheet material, but also holn the edges 25 and 27 of the polyethylene in their folded-over positions where they support the sheath 13 with the water absorbing layer 12 therein in the pad 10.

The second major surface 43 of the backing material layer 11 is shown in Figure 5 and is opposed to the major surface 25 (Figure 1) . Affixed thereto is a pressure sensitive adhesive strip 44 protected by a strippable cover 45. For use, the cover 45 i s removed from the adhesive strip 44; the pad 10 can then be secured to an undergarment (not illustrated) of the user.

It will be apparent that various changes and modifications can from the speci fic ails of the instant invention as shown in the attached drawings and described i n connection therewi th. For example, while the water impervious layer 11 has been described as a polyethylene sheet, any other thin, flexible material that is water-impervious in the sense that it is capable of preventing l eakage the re tiirough in ordinary use of a pad according to the i nvention can be used. Other polyol ef i ns , vi nyl chloride-vinylidene chloride conolymers and even cellophane coated to impart the requisite degree of impermeability to water are examples of other suitable material s. Similarly,while the water pervious sheath 12 has been described as a polyester, non-woven fiber mat, other material s can be used, for example nolyolefin non-woven fiber mats, the only requisi te bei ng that the sheath be water-pervious and sufficiently strong and water-resistant that it is capable of supporting the water-absorbing layer 12 in the pad 10 prior to and during use. Other changes and modi fications wil l be apparent to those skil led in the art and can be made wi thout departing from the spiri t and scope of the invention as defined in the appended claims.

Claims

1. A pad for absorbing body fluids, said pad comprising a l ongi tudi nal ly extendi ng l ayer havi ng opposed major s urf aces o f a water-impervious backing material , a longitudinally extending water-absorbing layer having first and second major surfaces and generally paral lel sides, sai d layer comprising at least one super-absorbent polymer that is capable of absorbing at least five times its dry weight of water, and that is physiologically acceptable for external contact with tiie human body, and a water-pervious s heath havi ng general ly paral l el s i des , a f i rs t substatially closed end and a second substantially open end, said water-absorbing layer being received within said sheath, said sheath being adhered to said backing material l ayer, and sai d backing material layer being so sized, relative to sai d sheath, that it constitutes a barrier to the flow of a fluid from all portions of the first major surface of said water-absorbing layer in a direction normal to the major surfaces of sai l backing material layer, said water-absorhing layer being so received within said sheath that rel ative longi tudinal movement between the two is difficult when said layer is dry, while the monentum of s a i d l ayer, when wet , and when the pad i s moved longitudinally toward the second end of said sheath and is stopped, causes relative longitudinal movement between the two, enabling easy removal of said layer from said sheatn, and said sheath having sufficient wet strength that it is capable of supporting said water-absorbing layer, when wet, relative to said backing layer.

2. A pad as claimed i n cl aim 1 wherei n sai d hacki ng material layer nas opposed generally parallel edges which extend upwardly and inwardly toward one-another across a portion of sai d sheath and a corresponding portion of the second major surface of sai d water-absorbi ng l ayer contained therein.

3. A pad as claimed in claim 2 wherein both layers of the first end of said sheath are sealed to the adjacent portion of said backing material layer.

4. A pad as cl aimed i n cl ai m 3 wherei n the outer extremities of both layers of the second end of said sheath are seal ed to tiie adjacent portions of sai d backing material.

5. A pad as claimed in claim 1 wherein the super-absorbent polymer is selected from the group consisting of cross-l inked acrylic polymers, cross-linked starch-acrylic graft copolymers and blends of the two.

6. A pad as claimed in claim 2 wherein the suner-arsorbent polymer is selected from the group consisting of cross-l inked acryl ic polymers, cross-l inked starch-acrylic graft copolymers and blends of the two.

7. A pad as claimed in claim 3 wherein the super-absorbent polymer is selected from the group consisting of cross-linkerd acryl ic polymers, cross-linked starch-acrylic graft copolymers and blends of the two.

8. A pad as claimed in claim 4 wherein the super-absorbent polymer is selected from the group consisting of cress-li nked acrylic polymers, cross-linked starch-acrylic graft copolymers and blends of the two.

g. A pad as claimed in claim 5 wherein the super-absorbent polymer is a laminate on a tissue sheet.

10. A pad as claimed in claim 6 wherein the super-absorbent polymer is a laminate on a tissue sheet.

11. A pad as claimed in claim 7 wherein the super-absorbent polymer is a laminate on a tissue sheet.

12. A pad as claimed in claim 3 wherein the super-absorbent polymer is a laminate on a tissue sheet.

13. A pad as claimed in claim 5 wherein the super-absorbent polymer is intimately associated with the fibers of a sheet of intermeshed cellulose fibers.

14. A pad as claimed in claim 5 wherein trie super-absorbent polymer is intimately cssociated with the fibers of a sheet of intermeshed cellulose fibers.

15. A pad as claimed in claim 7 wherein the super-absorbent polymer is intimately associated with the fibers of a sheet of intermeshed cellulose fibers.

15. A pad as claimed in claim 8 wherein the super-absorbent polymer is intimately associated with the fibers of a sheet of intermeshed cellulose fibers.