US 3528421 A
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United States Patent  Inventors Vincent L. Vaillancourt' Livingston, New Jersey; 2 Thomas Thackston, Florham Park, New Jersey; Donald R. Roberts, North Plainfield, New Jersey  Appl. No. 784,668  Filed Dec. 18, 1968  Patented Sept. 15, 1970  Assignce C.R. Bard Inc.
Murray Hill, New Jersey a corporation of New York 541 DISPOSADLE nnsonnizis'r n'iimini w OR THE LIKE 21 Claims, 4 Drawing Figs.
 US. Cl 128/284, 128/156, 128/287, 128/296, 5/90, 5/354  lnt.Cl. ..A61f 13/18, B32b 3/24, B32b 3/26 Field ofSearch 5/90, 91,
 References Cited UNITED STATES PATENTS 2,620,494 12/ 1952 Kay 297/219X 2,660,735 l/1953 Baum 5/354 2,707,289 5/1955 Taggart 5/354 3,344,789 10/1967 Arnold et al 128/287 3,427,670 2/1969 Mimoy 5/354 3,431,911 3/1969 Meiset, Jr. 128/287 Primary Examiner-Casmir A. Nunberg Attorney-W. Saxton Seward ABSTRACT: A disposable absorbent underpad for hospital patients, or similar product, in which a powdered chemical absorbent such as hydrous calcium silicate is deposited in retentive relation to a sheet or sheets of cotton linters or the like, the combination sheet or sheets and powder being preferably faced upwardly with a permeable sheet of non-wetting material such as spun-bonded polyester and backed with a liquid impervious sheet of polyethylene or the like extending across the entire bottom surface and folded over the edges of the underpad.
Patented Sept. 15, 1970 t 3,528,421
Vincent LVAiHZnCoUHZ Thomas ThbckstOn Donald RtRoberf m tmat ATTORNEYS INVENTORS DISPOSABLE ABSORBENT UNDERPAD OR THE LIKE Underpads currently available are commonly formed of a 0.5 to 1.0 mil film of polyethylene as a water-proof backing, absorbent wadding or loose pulp generally of a cellulosic nature and a cover sheet of soft, wet-strength, non-woven material. Such a pad in the common sizes of 17%" x 24" or 36" x 24" can absorb 25 to 50 ml. of water and will remain entirely wet and soggy to the touch. The presence of such a wet pad is very detrimental to the patient, causing diaper rash or other skin irritations unless the pads are changed often and offering no protection or comfort to the patient. In many cases liquid runs off the pads onto the bed sheets. In practice several such pads may be used at a time, with frequent changes, increasing the expense and taking up nursing time.
It is, therefore, an object of this invention to provide a disposable bedpad or the like having an absorption layer of wet-strength paper which immobilizes urine (or other liquid) and offers the patient a relatively drier surface on which to lie, thereby decreasing his chances of developing bedsores, secondary bacterial infection, and any other skin irritation associated with skin and urine contact for extended periods of time.
A previous attempt was made (as shown in U.S. Pat. No. 3,344,789) to immobilize urine using hydrous calcium silicate. Such attempts have been shown to be inadequate. For example, when the powder is packaged in packets it creates a very lumpy and uncomfortable pad and is extremely difficult to dispose of, and at the same time is extremely costly.
It has now been found that the filling of a paperboard sheet on conventional paper-forming equipment such as a fourdrinier, with hydrous calcium silicate provides a product which is softer, more comfortable, immobilizes more liquid, and is easier to dispose of, as well as being easier to manufacture. It has been found that certain grades (the absorbent ones) of cotton linter pulp provide a better finish in combination with a hydrous calcium silicate along with commercially available retention aids for helping to retain the powder in the sheet. Using this technology, paperboard can be filled with the hydrous calcium silicate in quantities of up to 70 percent by weight. Laboratory hand sheets indicate that the quantity may be as high as 80 percent although at this high percent the product is fragile. In theory the greater the loading of absorbent powder, the more absorbent the resultant product will be per given basis weight and obviously the more economical the product is on a cost performance basis.
It has been found that the amount of liquid immobilized is a factor of three parameters, (1) Amount of powder, (2) Type of pulp, (3) Density of the sheet. Laboratory experiments show that products made using the same pulp, the same quantity of powder (based on a standard TAPPI ash test) but having different densities, do in fact, immobilize different quantities of urine (any liquid). The less dense the sheet the more liquid the sheet will immobilize.
The cotton linter pulp offers the advantage of being able to disperse the fluid from the point of contact to the outer fringes of the pad, thereby utilizing a greater percentage of surface than other products now available.
If a pad is designed to hold 330 ml of liquid, it has been found when up to 80 percent of this amount is put on the product its surface will become dry to the touch within lk to 5 minutes. If only percent or 20 percent of the theoretical limit is utilized the surface will dry in 30 seconds or less. When an amount of fluid less than the designed limit of the sheet is immobilized, the sheet (or bedpad) can be held up or squeezed and no liquid will drip from it; this drastic demonstration of fluid retention and patient protection cannot be ps tq msqx j a t sm sa abls prq t a l A modified form of absorbent product is made by hydroforming, using conventional paper technology, two layers of paperboard which ideally should be cotton linter stock but may be other materials such as alpha cellulose, wood pulp, etc. Between the two layers is sandwiched hydrous calcium silicate which may be deposited in line on the first formed layer product. In this fashion the hydrous calcium silicate is trapped between the two layers. This product will also behave quite similarly to the previous one mentioned above which may be referred to as a Matrix powder paper product. One advantage of this modified product is in those applications where the edges are confined and large immobilizing capacities required; the two outer layers, one on either side, can be relatively thin with a heavy layer or core of hydrous calcium silicate. In a modification of this particular composition, the bottom layer may be of a water-proof barrier material such as polyethylene.
Additionally, a non-wetting material such as spunbonded polyester may be provided to serve as the cover layer for either of the two products, that is, the Matrix powder paper, or the composite sheet product previously mentioned. When using this type product one commercially available material of this type is Remay (a product of the DuPont Company). It has been found that two significant advantages accrue from the use of such a material. The first is that, for a given amount of fluid poured onto the surface of the product with the Remay surface layer or like product, the time required to achieve a dry surface, that is dry to the touch or skin, is appreciably reduced. Reductions of time in excess of 50 percent have been experienced. The second significant advantage is that it has been found that the immobilizing capacity of the underlayer, that is, the Matrix powder paper product or composite sheet, is increased. This is apparently due to the fact that the layers of the Matrix powder paper product which are at the surface or immediately adjacent to the surface can be utilized to immobilize liquid without experiencing a surface wet to the touch or skin. Evidence appears to indicate that at least 10 percent additional capacity per given sheet can be expected.
The pads according to the present invention can immobilize from 25 to 500 ml. of liquid while remaining relatively dry to the touch. As a result, there is effected reduction in number of pads used, number of changes, hospital inventory, patient discomfort and irritation, number of sheets soiled, and need for nursing attention.
A practical embodiment of the invention is shown in the accompanying drawing wherein:
FIG. 1 represents a plan view of one comer of the underpad, parts being broken away;
FIG. 2 represents a section on the line IIII of FIG. 1, the thickness of the layers being exaggerated for purposes of illustration;
FIG. 3 represents a similar section showing a duplication of the absorbent layers; and
FIG. 4 represents a similar section of a modified form of underpad.
The underpad is shown in FIGS. 1 and 2 as comprising a combined distribution and absorption layer 1 made of 100 percent cotton linter pulp, and a quantity of hydrous calcium silicate (commercially available, for instance, under the trademark Micro-Cel-E, Johns-Mansville Sales Corp., which is capable of immobilizing up to 560 percent of its weight of liquid while remaining a dry powder) included in the pulp to form a homogeneous sheet of any desired thickness, resembling blotting paper. The precent (by weight) of powder in a sheet can vary widely, depending on the desired end use, but the maximum is about percent for practical purposes. The powder is added to the pulp according to methods which are conventional in paper making. Cotton linters have excellent wicking properties and assure immediate distribution of the liquid to the included powder.
The cover layer 2 is a non-woven porous material having non-wetting properties and capable of transmitting liquid rapidly while retaining its wet strength. Spunbonded polyester gives excellent results and other non-woven fabrics produced by conventional methods are satisfactory.
The backing layer 3 is a liquid-proof barrier between the absorbent layer 1 and the support (e.g. bed) on which it rests, being conveniently constituted by a sheet of 0.5 mil to 1.0 mil polyethylene, turned up around the marginal edges of the layers 1 and 2 and overlying the peripheral portions thereof as indicated at 4 where the three layers are sealed together. The backing layer may be turned up and sealed around all four sides of a rectangular pad, as indicated in FIG. 1, or may be left unsealed across the shorter ends.
If greater capacity is desired than that provided by a single distribution and absorption layer, this element may be duplicated or multiplied, FIG. 3 showing a section of a pad having two such layers 5, 6 covered by a non-woven porous sheet 7, as described above, and backed by a liquid impervious sheet 8, also as previously described.
Each layer 1, 5 or 6 may suitably have an uncompressed thickness in the range of 0.25-2.5 mm, which provides adequate flexibility as well as absorption capacity. A plurality of such layers, where needed, are naturally more flexible than a single layer of equal thickness.
In the modified form of FIG. 4, a layer of hydrous calcium silicate 9 is shown as being sandwiched between upper and lower layers 10, 11 of paperboard which is preferably cotton linter stock but may be alpha cellulose, wood pulp or the like. The layers 9, l and 11 are shown as being backed by a sheet or film of impermeable material 12, as in the case of FIGS. 1 to 3, this sheet being folded around the edges, as indicated at 13 in order to enclose completely the layer of absorbent material, thus forming, in effect, a single large packet of powder, the displacement of which is inhibited by association with the adjacent surface or surfaces of distribution material. A cover sheet 14, corresponding to the sheet 2, may be provided if desired. Variations of the form shown in FIG. 4, which can be understood without specific illustration, include increasing the thickness of the absorbent layer 9 relative to layers 10 and/or 11 for greater liquid immobilizing capacity, and omitting the layer 11 (the layer 9 being deposited directly on the sheet 12).
If the upper surface of the sheets 1, and is of a suitable character (e.g., smooth and/or soft enough to be comfortable) the cover sheet 2, 7 or 14 may be omitted, the wicking action of the distribution material being relied on to remove liquid rapidly from the upper surface and conduct it to the immobilizing material.
The materials described above appear to be applicable not only to use as hospital underpads, but also in appropriate sizes and shapes-as sanitary napkins, nursing cups, diapers, wound dressings and other applications not necessarily limited to the medical field.
1. An absorbent article for absorbing liquid wastes comprising a body layer containing a substantially uniformly distributed powdered chemical absorbent characterized by the ability to immobilize without becoming wet at least 400 percent of its weight of liquid a porous cover sheet extending over one surface of said layer and a liquid impermeable backing sheet extending over another surface of said body.
2. An absorbent article according to claim 1 in which the body layer is a sheet of homogeneously combined fibrous distribution material and powdered chemical absorbent.
3. An absorbent article according to claim 1 in which the body layer includes at least one sheet of cotton linter pulp.
4. An absorbent article according to claim 2 in which the distribution material is cotton linters.
5. .An absorbent article according to claim 1 in which the absorbent is hydrous calcium silicate.
6. An absorbent article according to claim 2 in which the absorbent is hydrous calcium silicate in a proportion up to percent by weight of the combined materials.
7. An absorbent article according to claim 1 in which the body layer includes at least one sheet of fibrous distribution material and the absorbent is distributed as a layer between said sheet and the backing sheet.
8. An absorbent article according to claim 1 in which the body layer includes two sheets of fibrous distribution material and the absorbent is distributed as a layer between said two sheets.
9. An absorbent article according to claim 1 in which the cover sheet is a non-woven fabric. I
10. An absorbent article according to claim 9 in which the cover sheet is a spun bonded polyester.
11. An absorbent article according to claim 1 in which the backing sheet covers the entire surface of the body layer opposite the surface covered by the porous cover sheet and is folded over at least two opposite edges of said body layer and cover sheet.
12. An absorbent article according to claim 7 in which the backing sheet covers the entire surface of the body layer opposite the surface covered by the porous cover sheet and is folded over all the edges of the body layer and cover sheet to enclose the layer of absorbent.
13. An absorbent article according to claim 2 in which the article is a disposable incontinent pad, bed pad or under pad.
14. An absorbent article according to claim 7 in which the article is a disposable incontinent pad, bed pad or under pad.
15. An absorbent article according to claim 2 in which the article is formed in a size and shape adapting it for personal wear.
16. An absorbent article for absorbing liquid wastes comprising a sheet of homogeneously combined fibrous liquid distribution material and a substantially uniformly distributed powdered chemical absorbent characterized by the ability to immobilize without becoming wet at least 400 percent of its weight of liquid, and means associated with one surface of said sheet for inhibiting the passage of liquid therefrom to a surface in contact therewith.
17. An absorbent article for absorbing liquid wastes comprising fibrous liquid distribution material and a powdered absorbent material characterized by a sheet-like body comprising said distribution material and the absorbent material in intimate contact with each other, said absorbent material having the ability to immobilize without becoming wet at least 400 percent of its weight in liquid.
18. An absorbent article according to claim 17 in which the absorbent material is disposed in a layer covered by the distribution material.
19. An absorbent article according to claim 18 which includes a liquid impermeable backing sheet.
20. An absorbent article according to claim 17 in which the sheet-like body includes two layers of said fibrous distribution material and a layer of said absorbent material sandwiched between said two layers.
21. An absorbent article according to claim 20 which includes a liquid impermeable backing sheet.