IE41647B1 - Absorbent articles - Google Patents

Abstract

1509229 Absorbent pads COLGATEPALMOLIVE CO 4 Aug 1975 [12 Aug 1974] 32551/75 Heading A5R [Also in Divisions A4 and B5] An absorbent article I such as a diaper surgical pad etc., comprises an outer backing sheet 2 of water - impervious material having marginal edges 6, 7, 8, 9 a facing sheet 3, 5 of fluid - resistant material having apertures 22 and having marginal edges 6, 7, 8, 9 and an absorbent pad 4 disposed between the backing and the facing sheet and having a plurality of apertures 16, the sheets being secured together at their marginal edges and through the apertures of the pad. The apertures in sheet 5 are smaller than those in pad 4 and are disposed in an area smaller than the area of the pad, except where the sides of the pad have relieved portions 14, 15 for comfortable fitting between a child's legs. The facing sheet is fixed to the backing sheet by adhesive, or welding in the case of plastics material sheets, through the apertures 16, the pad thus being held in position.

Description

This invention relates to absorbent articles such as diapers, catamenial pads, fluid-absorbent bed sheets, surgical or medicinal absorbent pads or drapes, and surgical or medicinal dressing pads . or bandages.

Currently available absorbent articles, particularly diapers, have disadvantages, particularly complexity of manufacture and less than the desired effectiveness in use. For example, pulverized . wood pulp absorbent pads of diapers tend to have low wet strength integrity resulting in pulling.apart and balling when contacted by fluid. Unless they have a special sheet, called a wadding sheet, they also disintegrate and shift in position . when disposed between plastic sheets. Typically, they must be glued across one entire surface to retain them in position, with consequent loss of absorbency, use of large quantities of adhesive, and extra layers of material. The wieking action . of the pad is thereby reduced and the spreading action of backing sheets is also hindered. The requirement of additional layers makes for a bulky diaper, uncomfortable and ill fitting in use, and the rate of liquid penetration is reduced . with each additional layer required, and particularly by the wadding sheet. Not only does the wadding sheet reduce the rate of fluid penetration, it also significantly adds to the cost of the diaper. Likewise, there is no way to prevent or . reduce reverse fluid flow and excessive urine 2. - contact with the skin.

The present Invention provides improvements in absorbent articles. The invention is applicable more particularly, hut not exclusively, to diapers.

. According to the invention an absorbent article comprises a water-impervious first sheet having marginal edges, a second sheet of fluid-resistant material having a plurality of apertures therein and having marginal edges, an absorbent pad disposed between the first and (as hereinafter defined) . second sheets and having a plurality of apertures/therethrough, these apertures being of equal size to or larger than the apertures in the second sheet, the first and second sheets being secured to each other through apertures individual in at least part of areas defined by / pad apertures, . and the marginal edges of the first and second sheet being secured to each other.

The term apertures as used herein does not include discontinuities which extend to an edge of the respective pad or sheet and divide it into separate areas.

. By way of example, in an absorbent article embodying the invention and useful as a diaper the first sheet is an outer or backing sheet and the second sheet is an apertured interlayer sheet, these sheets having disposed therebetween an apertured absorbent pad. An inner or . top sheet overlies the interlayer sheet, the inner sheet and the interlayer sheet serving a cover sheets for the absorbent pad. The apertures of the pad are large and permit direct bonding of the interlayer sheet to the outer sheet through the pad apertures without bonding to the . pad. This retains the pad in position without need for a special retainer or wadding sheet which in a conventional.. 3. diaper defines the front surface of the pad, and without adhesive to position the pad and retain it in place. The apertures in the pad also provide additional wicking surfaces for rapid absorption . 'of fluid passing through the inner and interlayer sheets. The interlayer sheet has a plurality of apertures smaller than those in the pad, which allow fluid to pass from the inner sheet to the pad.

The apertures in the interlayer sheet are preferably . restricted to an area of the interlayer sheet within the area thereof in contact with the pad to reduce the risk of return flow of fluid through the interlayer sheet. The outer sheet and the interlayer sheet are preferably of a thermoplastic material to keep the . outer surface of the diaper dry, to promote fluid spreading, and permit bonding without need for adhesives. The marginal edges of the sheets are preferably bonded together to prevent fluid escape. The inner sheet is preferably a non-woven fibrous material that , minimizes direct skin contact with plastics material and has a suitable feel or hand. Such a diaper shows an improved rate of fluid absorbency, improved penetration, excellent one-way fluid transmission through the interlayer, excellent spreading by the . backing sheet and improved wicking into the pad and fluid retention. The diaper is simple to construct, permitting omission of a wadding sheet, yet having improved pad location and retention without hailing in use.

. In a modified form of the invention the interlayer sheet is omitted and the inner or top sheet is the said second sheet. In this case the inner sheet is not only fluid-pervious hut is of a fluid-resistant, i.e. hydrophobic, material, such as a non-woven, fibrous . synthetic material. An absorbent pad is disposed between the inner and backing sheets, said pad having a plurality of apertures extending therethrough, and the inner sheet is secured to the backing sheet through a plurality of the pad apertures.

. The pad may be cut away or relieved in areas disposed mid-way along the two sides in the diaper crotch region, to provide for a better leg fit. The diaper may be folded-in a box pleat, and adherent tabs may be provided for removably retaining the diaper . in position on a child.

The invention may be performed In various ways, and one embodiment and some modifications will now be described by way of example with reference to the accompanying drawings, in which:20. Figure 1 is a plan view of a diaper embodying the invention, parts being broken away to show the several layers; Figure 2 is a fragmentary section along the line 2-2 of Figure 1, the lower part of the Figure . illustrating a modification; Figure 3 shows in perspective the embodiment of Figure 1 folded in a box pleat form ready for use; and Figure 4 is a fragmentary section of a modified . form of diaper embodying the invention.

. Referring to Figure 1, the absorbent article 1, in this embodiment a disposable diaper, comprises an outer backing sheet 2 (the said first sheet) and an optional inner sheet 3 having disposed therebetween . an absorbent pad 4, and an interlayer sheet 5 (the said second sheet). These sheets 2, 3, and 5 are shown for purposes of illustration as generally rectangular, each having a pair of lateral side edges 6, 7 and a pair of end edges 8, 9 connecting the side . edges 6, 7, the edges of all the sheets being substantially in registry. However, other shapes, depending on use and preference, such as square, triangular, polygonal or combinations -thereof may be employed for the sheets.

The sheets may have straight or curved edges.

. The outer hacking sheet 2 is of water-impervious material, e.g. a thermoplastic or thermosetting plastics material, such as a polyolefin (polyethylene or polypropylene), a polystyrene or a vinyl polymer such as polyvinylchloride.

. Mixed polymers, copolymers, terpolymers and laminated materials may also be used. This sheet may he made by a continuous extrusion, casting, or other operation.

It is preferably a homogenous web. Where the desired water -imperviousness is achievable, the sheet may . be of woven, non-woven, or felted fabric. Sheet thickness may vary and typically is in the range from 0.1 to 3.0 mils, thicknesses of about 1.0 mils being used for diapers and thicker sheets being used , for heavy duty applications such as _______ 6. surgical pads or draping. The interlayer sheet 5 is preferably of the same material and gauge. The sheets, particularly the outer backing sheet and inter5. layer sheet, may be differently coloured, for coding purposes in manufacture of the article, to ensure proper orientation in use, for sales appeal or for aesthetic reasons. For example, the outer backing sheet may be white while the interlayer . is blue; if semi-translucent, the inner sheet 3 takes on the blue colour of the interlayer sheet and the'absorbent article thus has differently colour-coded sides that can be referred to in manufacturing and use instructions. Other colours, . patterns and designs may be used.

The absorbent pad 4 may be any suitable absorbent material, such as pulverized wood pulp, cellulose wadding, or any woven, non-woven or felted, natural or synthetic, fibrous or non-fibrous . (such as open or closed cell-sponge or foam-type) material. The rectangular pad of this embodiment, as best shown in Figures 1 and 2, has end edges 10, and side edges 12, 13· These edges are generally spaced inwardly from the edges 6, 7, 8 . and 9 of the sheets. As noted above, the pad may have a variety of shapes and sizes. One diaper configuration is shown in Figures 1 and 3, 14, 15 wherein the pad has portions ybf its sides relieved in'the crotch region of the diaper. 50. As best shown in Figure 3, this prevents excess 7. bulk ih the baby's crotch area and provides a better fit. The segment-shaped areas between the outer backing sheet and the interlayer bounded by the relieved sides of the pad help to collect fluid in the crotch area and . spread it to the unrelieved portions of the pad away from the crotch area.

The pad 4 may be treated with agents such as medicaments, deodorants, emollients, powders (e.g. baby powder), wetting agents or other surfactants, salves, . perfumes, bactericides or germicides, as desired.

The pad 4 has a plurality of large apertures 16 spaced inwardly from its edges 10, 11, 12 and 13· These apertures permit direct bonding of the interlayer sheet 5 (and optionally the inner sheet . 3) to the outer backing sheet 2 in zones 17, in the manner shown best in the upper half of Figure 2. The bonding may be by any suitable means, such as by heat bonding, solvent bonding or adhesive bonding. Heat bonding is preferred. Each bonding . zone occupies only a portion of the area defined by the corresponding aperture 16. The bonds effectively retain the pad in position between the outer backing sheet 2 and the interlayer sheet 5 without adhesive having to be applied to the pad, and they present . a quilted effect. The pad does not shift in position during transport or use, and does not pill, wad or ball upon contact with fluid. The lower portion of Figure 2 shows an alternative embodiment wherein 8. the inner sheet 3 is not bonded to the interlayer sheet 5 or the outer backing sheet 2 in the zone 17.

With such constructions the single or multilayer wadding sheet and the pad wrapper or pouch . commonly employed in disposable diapers can be omitted, with consequent improvement in liquid permeability and reduced cost.

The pad apertures have edges 18 which provide additional wicking surfaces for rapid absorption . of fluid by the pad. Absorption by exposed fibrous ends, such as presented by the aperture edges 18, and hy the side and/or end edges 10, 11, 12, and 13 is generally faster than through the inner surface 19 of the pad.

. The inner surface 20 of the outer backing sheet helps to spread fluid into contact with the wicking edges 10, 11, 12, 13 and 18 of the pad, and into contact vzith the back. surface of the pad 4 intermediate the apertures 16. Since no glue is . required to retain the pad in place, better fluid spreading is obtained.

Each bonding zone 17 occupies only a portion of the area defined by the corresponding pad. aperture 16, leaving annular spaces 21 between the . interlayer sheet 5 and the outer backing sheet 2 in the region of the apertures 16, seen best in Figure 2. These spaces serve as reservoirs for fluid passing through apertures 22 in the interlayer sheet 5. Thus, the penetration rate limiting . factor is the speed of transfer through the inter9. sheet layer/apertures 22, rather than the absolute rate of absorption through the pad. surface 19. Fluid does not tend to puddle on the inner surface 23 sheet of the interlayer/5 while awaiting the relatively 5. slow sorption through the surface of the pad.

Rather, the fluid can run quickly through the apertures 22 into the reservoir Spaces 21 and then wick through the pad aperture edges 18. Urine contact With the skin is thus minimized, sheet . The interlayer/apertures 22 generally will be smaller and more numerous than the pad apertures 16. As an example, the apertures 16 in the pad may be f in diameter, while the apertures 22 in the interή layer sheet 5 may be ‘/a in diameter. This . provides a flow gradient effect permitting a large number of access ports for fluid to the pad 4 and the reservoir spaces 21, and minimizing hack flow to the interlayer sheet surface 23 and contact with the skin. Further, the larger number of . apertures 22 ensures registry with the apertures 16 and the annular spaces 21. The small apertures 22 are limited in lateral extent (both horizontally and vertically as shown in Figure 1) to an area generally smaller than the area of the underlying . pad 4 (except as may optionally occur in the relieved portions 14 and 15) to eliminate leakage or backwieking from the edges 10, 11, 12 and 13.

Thus, the interlayer sheet 5 and the backing sheet 2 provide a seal to prevent . leakage at the side edges and end edges of the diaper.

The inner sheet 3 is optional but is preferred in order to minimize skin contact with the plastics material of the interlayer sheet 5 and to provide a smooth feel or hand. The inner sheet 3 . is preferably of a woven or non-woven, fibrous, natural (e.g. cellulosic) or synthetic material.

It may be a paper-process type of non-woven material, felted or randomly intertangled to form a selfsupporting sheet. The sheet 3 also helps provide . fluid transfer to the interlayer and skin protection. As with the pad 4, the inner sheet 3 may be treated with medicaments or other agents if desired.

Figure 3 shows the pad of Figure 1 folded into a conventional box pleat diaper configuration, . having adhesive-faced securing tabs 24, 24' with release sheets 25, 25’ thereover. To form the box pleat, adhesive 27, 27' may be applied to spots C and D of the inner sheet (see Figure 1) and folds 28, 29 formed and retained in place by the , adhesive. For packaging and shipping, the diaper may be folded transversely along the fold line F-F’. The relieved portions 14, 15 of the pad prevent bulking along the fold line, and permit better diaper fit. Xn use, the baby is laid on . the diaper, front end A is brought up between the baby's legs, the release sheets 25, 25' are removed and the tabs 24, 24' are secured to the outer surface 26 of the backing sheet 2.

In the embodiment illustrated in Figure 4 . the interlayer sheet 5 is omitted and the inner or top sheet 3(which in this embodiment Is the said second sheet) is bonded directly to the backing sheet 2 through the pad, apertures 16. The bonded top and backing sheets prevent shifting of the absorbent pad, as previously . described in connection with the diaper of Figures 1-3. In this embodiment the top sheet 3 is made of a porous water-resistant material such as a non-woven fibrous synthetic material, the pores constituting the said apertures in this sheet.

The quilted diaper of the present invention has . a plurality of raised and recessed surface portions and 34, respectively, defining an undulating front and rear surface of the diaper which is pleasing to the eye. When the diaper is placed on an Infant, the tape strips are secured in place, the outer backing . sheet is pulled somewhat taut, tending to accentuate the depressed front or inner surface portions and the undulating front or inner surface of the diaper.

Accordingly, the diaper presents a discontinuous front or inner surface with the raised portions contacting . the infant’s skin, and the depressed portions providing air pockets promoting the circulation of air within the placed diaper. To the extent that the front or inner surface becomes moist, its discontinuous configuration minimizes the wet surface . area which contacts the infant. The discontinuous front or inner surface also minimizes clinging of the inner sheet (or the interlayer sheet if there is no inner sheet) against the infant’s skin, which otherwise might be present in a continuous front surface.

Claims (10)

1. WHAT WE Claim is:1. An absorbent article comprising a waterimpervious first sheet having marginal edges, a second sheet of fluid-resistant material having a plurality of apertures therein and having marginal edges, an absorbent pad disposed between the first and second sheets and (as hereinbefore defined) having a plurality of apertures/therethrough, rhese apertures being of equal size to or larger than the apertures in the second sheet, the first and second sheets being secured to each other through pad apertures individual in at least part of areas defined by / pad apertures, and the marginal edges of the first and second sheets being secured to each other.

2. An absorbent article as olaimed in Claim 1 wherein the apertures in the second sheet are disposed in an area smaller than the area of the pad.

3. An absorbent article as claimed in Claim 1 or Claim 2 wherein marginal edges of the pad are inwardly spaced from the secured marginal edges of the first and second sheets.

4. An absorbent article as claimed in any of the preceding Claims which includes a third sheet, of fibrous material, disposed adjacent the second sheet on the side remote from the pad and secured to at least one of the first and second sheets. 13.

5. An absorbent article as claimed in any of the preceding Claims wherein the first and second sheets are of plastics material and are secured to each other by heat bonding, solvent bonding or adhesive bonding.

6. An absorbent article as claimed in any of the preceding Claims which is a diaper.

7. · A diaper as claimed in Claim 6 wherein two opposed pad margins are relieved in the crotch 10 portion of the diaper.

8. A diaper as claimed in Claim 7 the side margins of which, including the relieved portions of the pad, are pleated.

9. · A diaper as claimed in any of Claims 6 15 to 8 having a plurality of longitudinal folds defining a box-pleat configuration. herein

10. A diaper substantially as described/With reference to Figures 1, 2 (upper part) and 3, or as modified with reference to Figure 2 (lower part) 20 or Figure 4, of the accompanying drawings.