WO1996010976A1

WO1996010976A1 - Absorbent sanitary device

Info

Publication number: WO1996010976A1
Application number: PCT/US1995/013009
Authority: WO
Inventors: Giovanni Carlucci; Gennaro Giorgini; Antonello Colaianni; Maurizio Tamburro
Original assignee: The Procter & Gamble Company
Priority date: 1994-10-07
Filing date: 1995-10-05
Publication date: 1996-04-18
Also published as: IT1268108B1; AU3953295A; ITTO940802A1; EP0784458A1; KR970705959A; JPH10509336A; CA2159966A1; MX9702458A; ITTO940802A0

Abstract

An absorbent sanitary device (10) is provided, for example, an incontinence device for use by an adult female, the device (10) having a top side adapted in use to face the user, and a back side adapted to face away from the user. The device is elongate, and has a central region (12), and end regions (14, 16) which adjoin the central region (12), and which slope upwardly from the central region (12) as viewed from the top side. The device is provided with upstanding, elasticated, spaced apart barriers which extend longitudinally of the device adjacent laterally opposite side edges thereof and which, in cooperation with the end regions, define a user-engaging surface, the barriers being formed by upstanding portions of the topsheet.

Description

ABSORBENT SANITARY DEVICE

This invention relates to an absorbent sanitary device, for example in the form of a catamenial or a sanitary pad. However, it relates particularly to incontinence devices, and, more particularly, device for handling light or moderate incontinence in adult females. One characteristic which is particularly important in an incontinence device is its ability to conform to the adjacent part of the wearer's body, so that urine and other body fluids are directed into the device and do not bypass it. It is an object of the present invention to provide a device in which this is achieved to a particularly great extent. This is achieved by use of an advantageous system of elastication.

According to one aspect of the present invention there is provided an absorbent sanitary device having a top side adapted in use to face the user and a back side adapted to face away from the user, the device being elongate and having its end regions directed generally upwardly as viewed from the top side, the device comprising, as considered from the top side to the back side, a topsheet which is liquid permeable, a fluid storage core, and a liquid-impermeable backsheet sealed to the topsheet at least along a pair of laterally spaced, longitudinally extending, sealing lines, the device being provided with upstanding, elasticated. spaced apart barriers which extend longitudinally of the device along at least part of the length thereof, adjacent laterally opposite side edges thereof, inwardly of the said sealing lines, which barriers, in cooperation with the said end regions, define a user-engaging surface, the barriers being formed by upstanding, elasticated portions of the topsheet.

According to another aspect thereof there is provided an absorbent sanitary device having a top side adapted in use to face the user and a back side adapted to face away from the user, the device being elongate and having its end regions directed generally upwardly as viewed from the top side, the device comprising, as considered from the top side to the back side, a topsheet which is liquid permeable, a fluid storage core, and a liquid-impermeable backsheet sealed to the topsheet at least along a pair of laterally spaced, longitudinally extending, sealing lines, the device being provided with upstanding, elasticated, spaced apart barriers which extend longitudinally of the device along at least part of the length thereof, adjacent laterally opposite side edges thereof, which barriers, in cooperation with the said end regions, define a user- engaging surface, the barriers being formed by upstanding, elasticated portions of the topsheet, the topsheet material having a greater width than the backsheet material. According to yet another aspect there is provided an absorbent sanitary device having a top side adapted in use to face the user and a back side adapted to face away from the user, the device being elongate and having its end regions directed generally upwardly as viewed from the top side, the device comprising, as considered from the top side to the back side, a topsheet which is liquid permeable, a fluid storage core, and a liquid-impermeable backsheet sealed to the topsheet at least along a pair of laterally spaced, longitudinally extending, sealing lines, the device being provided with upstanding, elasticated, spaced apart barriers which extend longitudinally of the device along at least part of the length thereof, adjacent laterally opposite side edges thereof, which barriers, in cooperation with the said end regions, define a user- engaging surface, the barriers being formed by upstanding, elasticated portions of the topsheet, the elastication of said elasticated portions extending over at least 35% of the length of the device.

Each of the said barriers may be elasticated by means of a line of hot melt adhesive material, and the said material may be deactivated in at least one zone to cause it to be inelastic in the said zone, thereby to influence the shape of the device and/or increase the adhesion of the said material.

The invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a first embodiment showing the user side (i.e. the side which, in use faces the body .of the wearer) ;

Figure 2 is a top plan view of the device of Figure 1 in a tensioned condition, i.e. with the elastication therein stretched to cause the device to assume a planar configuration;

Figure 3 is a diagrammatic cross section through the centre of the device of Figure 1, showing the layers of which it is formed;

Figure 4 shows the patterns of adhesive applied to the various layers of the device of Figure 1;

Figure 5 is a view similar to Figure 3 but showing a second embodiment; and

Figure 6 is a view similar to Figure 3 but showing a third embodiment.

Referring first to Figure 3, it can be seen that, considered starting from the user side thereof, the device comprises the following layers: (a) Topsheet

The top layer (user side) is a topsheet 20 that must be comfortable to the touch, provide a dry feeling over an absorbent core filled with liquid, and pass fluid rapidly into the interior of the core. It is liquid permeable in the central longitudinal zone 22 and is liquid impermeable at least in the two lateral zones 24. As can be seen in Figure 3, the boundary between the central zone and each of the lateral zones coincides with a line of elastic glue, which is described in more detail below, though it is not essential that this should be so.

The topsheet can be of a variety of known materials, provided that it has a fluid-permeable central region and a fluid-impermeable edge region, for example: (a) a formed-film topsheet as described in U.S. Patent 3929135, or any of European Patent specifications Nos. EP-A-0018020, EP-A-0018684 and EP-A-0059506, (b) a partially perforated fibre/film composite described in EP-A-207904, the perforated area thereof providing a liquid permeable area, and the unperforated area thereof providing a liquid impermeable area, (c) a nonwoven film produced by the spunbonding or by a carded, thermal-bonded process, treated by appropriate hydrophobic finishing agents to give areas that are liquid permeable and liquid impermeable respectively, or (d) a sheet produced by various other processes currently practised, (b) Secondary Topsheet

This element 26 has the characteristics of accepting a high rate of fluid intake, serving as a temporary reservoir for the fluid, and then draining substantially completely into the storage core in order to remain empty for subsequent fluid loadings. In addition, this element must resist collapse when wet so that it maintains its performance through multiple loadings. This element must do all these things while also remaining extremely thin. An airlaid web of synthetic fibres can be used for this purpose. The secondary sheet should preferably have hydrophilic properties.

This material preferably has the following characteristics:

(a) A thickness of from 1 to 10mm, more preferably from 1.5 to 10mm, still more preferably from 1.8 to 7.5mm, and even more preferably from 2 to 6mm, the thickness being measured with the sheet under a pressure of 2kPa.

(b) A basis weight of from 35 to 300 g/m², more preferably from in excess of 40 up to 200 g/m², and still more preferably from 42 or 43 to 200 g/m².

(c) The sheet has a bulkiness of at least 15 cm³/g, when the sheet is under a pressure of 2kPa. More preferably, the bulkiness is from 15 to 65 cm³/g, still more preferably from 30 to 50 cm³/g. Yet more preferably, the minimum value for the bulkiness is 32, 33, 34 or 35 cm³/g.

(d) The ability to discharge to the storage core at least 95%, and more preferably at least 99% of the fluid which it receives in a loading.

(e) A wet collapse at 2.7kPa of not more than 45%, and more preferably not more than 40%.

(f) A wet resilience at 0.1 kPa of not more than 40%, more preferably not more than 30%, and still more preferably not more than 25%. (g) A wetting time of not more than 5 seconds, and preferably not more than 2 seconds.

(h) It is formed of fibres having a diameter of not more than about 20 μm, more preferably from about 15 to about 20um, and a length, at least when the sheet is an airlaid web, of not more than 20mm, preferably not more than 12mm, and most preferably about 6mm.

One suitable form of secondary topsheet is described in our Italian Patent Application No. TO 93a 000 402. In the embodiment illustrated in Figure 3 there are two secondary sheets 28, 30 each of which has the above mentioned characteristics.

The two layers of the secondary topsheet are adhered to one another by, for example a spiro hot melt adhesive, the term "spiro" referring to adhesive which is applied in a spiral pattern. The use of a pattern, as opposed to a continuous layer, keeps to ensure that fluid permeability is not significantly impaired, (c) Storage Core

The storage core 32 is a thin, high-capacity absorbent core. While thin when dry, this element of the structure preferably expands when wetted to provide a high, tenacious fluid-holding ability, and it must avoid collapse when wet. The storage core is itself preferably formed, as illustrated, of a plurality of layers. For example, as shown in Figure 3 it may be a three layer structure in which the upper and lower layers are of a cellulose tissue material (and may be the same as, or different from, one another) . The upper layer 34 is a thermobonded, airlaid, nonwoven, of short cellulose fibres, the lower layer 36 is an airlaid nonwoven also of short cellulose fibres, and the middle layer 38 is of a water-insoluble hydrogel. This is a polymeric material in particulate form, capable of absorbing a large quantity of liquid and retaining it under moderate pressures. It is commonly known by the abbreviation "AGM".

It is important that the secondary sheet and the storage core work together. In particular, given the form of secondary sheet described above, it is possible in this structure to avoid the typical problem of gel blocking in the storage core, because the secondary sheet provides total distribution of the fluid, and then drains into the storage core whenever the storage core has not yet received fluid.

As an alternative to the form of storage core described above, it can be one of a number of thin, high capacity materials. For example, the storage core can be a sheet of fused AGM particles as described in International Patent Applications Nos. W091/14733, W091/14734, W091/15352 and W091/15368 or a high capacity foam, as described, for example, in International Patent Publications Nos. WO93/04092, WO93/03699, WO93/04093, WO93/04113 and WO93/04115.

Another possibility is to use a core which is a mixture of cellulose fluff and AGM. Still more preferably, the storage core can be an AGM- comprising core as described in International Patent Application No.. PCT/US93/06128, or as described in Italian Patent Application No. TO 93 A 01028 filed on 31st December 1993. TO 93A01028 describes a layered, absorbent structure, characterised in that it comprises, in combination, first and second layers of fibrous material and an intermediate layer comprising a hydrogelling, absorbent material, in an amount exceeding 120g/m², distributed between the first and second fibrous layers, at least one of the first and second layers being permeable to liquids, and the intermediate layer also comprising a thermoplastic material, the intermediate layer bonding the first and second fibrous layers together, with the intermediate layer between them, (d) Impervious backsheet

The backsheet 40 is impervious to liquids and, thus, prevents fluid which may be expressed from the absorbent core from soiling the body or clothing of the user. Suitable materials are well known in the art, including woven and nonwoven fabrics which have been treated to render them liquid repellent. Breathable or vapour pervious, liquid resistant materials, and those materials described in US-A-3,881,489 and US-A-3, 989, 867 can also be used. Preferred materials are those materials that are fluid and vapour impervious, because they provide additional fluid strikethrough protection. Especially preferred materials include formed thermoplastic films.

(e) Panty fastening adhesive

A layer of pressure-sensitive adhesive 42 is provided on the reverse side of the backsheet to enable it to be adhesively attached to the user's panties.

(f) Release paper

A silicone release paper 44 removably covers the panty fastening adhesive 42, to enable the incontinence device to be packaged, and handled by the user prior to use, without it becoming unintentionally adhered to itself or to anything else. The release paper 44 is removed by the user prior to use. Such release papers are well-known in the art.

The various layers are adhered to one another by adhesives disposed in suitable patterns, and these are shown in Figure 4. This shows:

(i) The release paper 44 and its adjacent layer of panty fastening adhesive 42 (the paper 44 extends beyond the adhesive 42 both at its ends and at its side edges) . (ii) The backsheet 40 and a layer of spiro hot melt adhesive 46 extending the full length thereof, by which it is attached to the core 32.

(iii) The secondary topsheet layers 28, 30, each with a respective layer 48, 50 of spiro hot melt adhesive extending the full length thereof, by which, respectively, the layer 28 is attached to the layer 30 and the layer 30 attached to core 32. (In the drawing of the layer 30 in Figure 4 the lateral extent of the absorbent core is indicated by broken lines) . (iv) A plurality of spaced, longitudinally extending lines of hot-melt adhesive 52 by means of which the topsheet 20 is attached to the secondary topsheet layer 28, and laterally outermost lines 53 by which the topsheet is attached to the backsheet 40.

The device 10 as thus far described with reference to the drawings would lie in a flat plane. As illustrated in Figure 1, the device in fact has a generally flat central region 12 and an upwardly sloping region 14, 16 at each end. However, the basic requirements is for a device which is generally curved as viewed in longitudinal section, and this may take the form of a smooth curve extending from one end of the device to the other, rather than there being a distinct flat central region and distinct upwardly sloping end regions. The generally curved shape, whichever way it is achieved, enables the device to conform to a considerable degree to the user's body, with advantageous consequences in terms of its ability to catch urine and other body fluids.

The effect just described is achieved by two lines of elastication 54, 56 which are applied to the underside of the topsheet 30. The elastication preferably takes the form of two lines of a hot melt glue which is capable of being deactivated, a phenomenon described in more detail below. Suitable compositions for the purpose of the present invention are described in our copending Italian Patent Application No. [ ] entitled [title of DR52] .

By way of giving some theoretical background, it should be noted that for any elastic adhesive composition the elastic modulus G¹ can be measured as a function of the temperature. At room temperature G'>G", where G" is the viscous modulus. At a certain temperature, which coincides with the softening point of the material, G' and G" cross each other. At even higher temperatures G">G' and the material is liquid, while when G'>G" the material is solid. At any temperature below the softening point the value of G'is related to the storing of elastic tension. So if we subject the material at a certain temperature to a pressure at least equal or higher than the value of G' at that temperature, the material itself, even if still solid, flows and the internal tensions are relaxed. When this occurs the material ceases to be elastic, and is said to be "deactivated". The necessary pressure is zero at the softening point (at this temperature the material begins to turn into a liquid and any internal stress disappears spontaneously) , while at lower temperatures G' increases as the temperature decreases.

These facts are used in providing the lines of elastication 54, 56. A hot melt adhesive, preferably having a composition as described in the last mentioned copending Italian Patent Application, is extruded to give elongate pieces of adhesive, for example threads thereof. These are cooled, stretched to the desired elongation and tension and applied to the lower surface of the topsheet. A method of carrying out this procedure is described in our copending Italian Patent Application No. [ ] filed on [ ] and entitled [title of DR3.1]. Adhesion between the threads and the topsheet can be improved by exerting pressure, for example with a roll. This roll can be heated to a moderate temperature, to improve the adhesion between the threads and the topsheet. The combination of temperature and pressure must not be so great as to cause deactivation, at least not over the whole length of the threads. As described in Italian Patent Application No. [ ] [title of DR3.1], the roll can have a smooth surface, or it can have a toothed surface so that it presses the threads into contact with the topsheet only in selected zones.

Although, as already stated, the adhesive threads must not be deactivated through their entire length, they can be, and preferably are, deactivated over certain regions. At a plurality of points spaced along the central part thereof, where it runs alongside the central region 12, the adhesive threads can be subjected to a temperature, or a pressure, or, preferably, a combination of temperature and pressure which, though sufficient to improve the adhesion of the threads to the topsheet at those points, is insufficient to cause deactivation. However, ^' each thread is deactivated over the whole of each of its end parts, where it runs alongside the upwardly sloping regions 14, 16. This is done so that the threads are not in a tensioned state in these parts, and the sections 14, 16 do not curve, as viewed in side elevation.

The improved adhesion at selected points, and the deactivation along the regions 14, 16 can be carried out using heat and/or pressure applied by the same member, e.g. a single roll, or by different members, e.g. rolls. When a single member is used to carry out both functions, the single member can have a first zone where the temperature and/or pressure applied are sufficient to cause adhesion but insufficient to cause deactivation, and a second zone where the temperature and/or pressure are sufficient to cause deactivation. Typically, deactivation is carried out with a combination of temperature and pressure, so that the temperature required is less than or equal to the softening point.

In one example, the article has end regions each 45mm in length, over which the threads are completely deactivated, and a central region 156mm in length over which the threads are adhered to the topsheet over a plurality of short elements each 3mm in length, the centre- to-centre spacings of these elements being 7.8mm. It must be understood that these values are given by way of example only. The measurements apply to the article in its extended state, i.e. before the adhesive threads are allowed to cause contraction of the central region. The threads need not extend over the whole length of the article, and may extend only over part of the length thereof. Preferably, however, the threads, whether or not they are full length, have an elasticated portion which extends over at least 35% of the length of the article, and they may extend over 40%, 45%, 50%, or even more. In the example just quoted, the value is over 60%.

Once the lines of elastication 54, 56 have been applied to the topsheet 20, it is thermally crimped to the backsheet 40, adhesion being assisted in the crotch region by means of the lines of adhesive 53. At this stage, the lines of elastication 54, 56 are in tension. When this tension is released, the elasticity therein causes the adjacent parts of the topsheet (which are not adhered to the secondary topsheet situated below them) to stand up, thus producing side barriers 60, 62 (see Figure 3) , and causing the incontinence device as a whole to assume the curved shape shown in Figure 1. Typically, the width of the topsheet, before assembly, exceeds that of the backsheet by about 45mm, so permitting the formation of two barriers each about 10mm high. These barriers 60, 62, together with the upwardly sloping end regions 14, 16, define, so to speak, a kind of gasket which engages the body of the user and helps to prevent fluid escaping past the edges of the device before the device has had time to absorb it. It will be seen that each barrier has a triangular cross-section, with the generally upright walls of each triangle not being adhered to one another. All or part of the inner one of these walls may be fluid permeable, but the other one of these walls should be fluid impermeable.

An example of an incontinence device according to the invention will now be set out in more detail.

EXAMPLE

This is a light incontinence device for use by an adult female. The device is hourglass shaped as indicated in the drawings, and has a length of 246mm, a width at its widest point of 98mm, a width at its narrowest point of 76mm, and a weight of 10.58g. The details of the components used in the construction are shown in the following Table. Corresponding measurements appear on the drawings, all of which are in mm.

TABLE

Material Length (mm) Width (mm)

ABSORBENT CORE 219 56

TOPSHEET 246 98 (widest) 76 (narrowest

SECONDARY TOPSHEET 219 78 (widest)

(2 LAYERS. EACH LAYER) 60 (narrowest

BACKSHEET 246 98 (widest) 76 (narrowest

ELASTIC GLUE 246 (in stretched 2

(2 lines - each line) state)

With reference to the above Table, the topsheet is a partially perforated fibre/film laminated composite as already mentioned with reference to EP-A-207904; the composite may be ring rolled, and the perforated region is 65mm wide. Ring-rolling is used to provide the composite with a degree of extensibility. Suitable processes for ring-rolling are described in US Patents 4107364, 4834741, 5143679, 5156793 and 5167897.

The absorbent core is a layered structure of the type described above. The upper fibrous layer is a thermal bonded airlaid (about 76% cellulose fibres and about 24% bicomponent PE-PP fibres) 219mm long 56mm wide and with a basis weight of 75 g/m²; the intermediate layer, 219mm long and 48mm wide, comprises particles of AGM (XZ 91002.01 by Dow Chemical) with a basis weight of 385 g/m²; the lower fibrous layer is a latex bonded airlaid (100% cellulose fibres) 219mm long, 56mm wide and with a basis weight of 55 g/m².

The secondary topsheet is a 100% bicomponent PE-PP fibres thermal bonded air laid.

The backsheet is a thermoplastic film 40 μm thick.

The elastic glue is of the type described above.

The embodiment shown in Figure 5 is similar in most respects to that of Figure 3, and the same references are used for corresponding elements, but increased by 100. The two embodiments differ in that in Figure 5 the topsheet 20 wraps around the edges of the backsheet 40, so avoiding the laterally extending flanges of topsheet and backsheet which are present in Figure 3 in the region wherein the two are bonded together.

The embodiment shown in Figure 6 is similar to the two previous embodiments, and the same reference numerals are used as for Figure 3, but increased by 200. The principal difference from the previous embodiments is that the topsheet is turned over at its outer lateral edges and sealed to itself, enclosing the lines of elastication.

A number of tests are referred to in the preceding description, and the following gives details of how those tests are conducted.

Wet collapse

The samples 39 x 50mm are made of as many superimposed layers of material as are needed to get an overall basis weight of 500 g/m². The samples are completely plunged in synthetic urine (the composition of which is given below) and left in it for 1 minute. They are then placed on a perforated plexiglass plate and subjected to three dynamic cycles of compression and decompression (speed of the pressing head lOmm/min, maximum load for each cycle 2.7 kPa) . The minimum thickness of the sample under compression is measured.

The wet collapse is:

(initial thickness - minimum thickness/initial thickness of the sample) x 100 (%) .

Wet resilience

In the above described test the final thickness of the sample after the last decompression is measured.

The wet resilience is then obtained as:

(initial thickness - final thickness) /initial thickness) x 100 (%) .

Wetting time

In this test, samples of the secondary sheet having a volume of about 5cc are tested. The samples are placed horizontally onto the surface of synthetic urine by means of a metallic net. The wetting time is the time needed for each sample to get completely soaked.

Synthetic urine

The synthetic urine used was a solution in distilled water of the following salts (in weight %) : Urea 2%, sodium chloride 0.9%, magnesium sulfate (heptahydrate) 0.11%, calcium chloride (anhydrous) 0.06%.

Claims

CLAIMS :

1. An absorbent sanitary device having a top side adapted in use to face the user and a back side adapted to face away from the user, the device being elongate and having its end regions directed generally upwardly as viewed from the top side, the device comprising, as considered from the top side to the back side, a topsheet which is liquid permeable, a fluid storage core, and a liquid-impermeable backsheet sealed to the topsheet at least along a pair of laterally spaced, longitudinally extending, sealing lines, the device being provided with upstanding, elasticated, spaced apart barriers which extend longitudinally of the device along at least part of the length thereof, adjacent laterally opposite side edges thereof, inwardly of the said sealing lines, which barriers, in cooperation with the said end regions, define a user-engaging surface, the barriers being formed by upstanding, elasticated portions of the topsheet.

2. An absorbent sanitary device having a top side adapted in use to face the user and a back side adapted to face away from the user, the device being elongate and having its end regions directed generally upwardly as viewed from the top side, the device comprising, as considered from the top side to the back side, a topsheet which is liquid permeable, a fluid storage core, and a liquid-impermeable backsheet sealed to the topsheet at least along a pair of laterally spaced, longitudinally extending, sealing lines, the device being provided with upstanding, elasticated, spaced apart barriers which extend longitudinally of the device along at least part of the length thereof, adjacent laterally opposite side edges thereof, which barriers, in cooperation with the said end regions, define a user-engaging surface, the barriers being formed by upstanding, elasticated portions of the topsheet, the topsheet material having a greater width than the backsheet material.

3. An absorbent sanitary device having a top side adapted in use to face the user and a back side adapted to face away from the user, the device being elongate and having its end regions directed generally upwardly as viewed from the top side, the device comprising, as considered from the top side to the back side, a topsheet which is liquid permeable, a fluid storage core, and a liquid-impermeable backsheet sealed to the topsheet at least along a pair of laterally spaced, longitudinally extending, sealing lines, the device being provided with upstanding, elasticated, spaced apart barriers which extend longitudinally of the device along at least part of the length thereof, adjacent laterally opposite side edges thereof, which barriers, in cooperation with the said end regions, define a user-engaging surface, the barriers being formed by upstanding, elasticated portions of the topsheet, the elastication of said elasticated portions extending over at least 35% of the length of the device.

4. A device according to any preceding claim, further comprising at least one secondary topsheet positioned between the first mentioned topsheet and the fluid storage core to act as a temporary fluid reservoir.

5. A device according to any preceding claim, wherein the backsheet has a layer of adhesive on the side thereof which faces away from the fluid storage core, said adhesive being adapted to enable the device to be secured to a garment of the user.

6. A device according to any preceding claim, wherein each of the said barriers is elasticated by means of a line of hot melt adhesive material.

7. A device according to claim 6, wherein the said line of hot melt adhesive is applied to the side of the topsheet which, in use, faces away from the user.

8. A device according to claim 7, wherein the said adhesive material is deactivated in at least one zone to cause it to be inelastic in the said zone. thereby to influence the shape of the device and/or increase the adhesion of the said material.

9. A device according to claim 8, wherein the material is deactivated along end sections at each end thereof which run alongside the said end regions of the device.

10. A device according to any one of claims 7 to 9, wherein each line of hot melt adhesive is adhered to the topsheet, or adhered to it more strongly, at a plurality of points spaced along a central part thereof, such adherence, or stronger adherence, being achieved by temperature or pressure or a combination thereof.

11. A device according to any preceding claim, in the form of an incontinence device for use by an adult female.