WO1999012502A1

WO1999012502A1 - Disposable non-absorbent diaper shell with removable and replaceable absorbent pad and method of manufacture of same

Info

Publication number: WO1999012502A1
Application number: PCT/CA1997/000634
Authority: WO
Inventors: James Roy Brownlee
Original assignee: James Roy Brownlee
Priority date: 1997-09-08
Filing date: 1997-09-08
Publication date: 1999-03-18
Also published as: AU4108997A

Abstract

A disposable diaper which is adapted for multiple uses by means of a removable and replaceable absorbent pad is provided. The diaper consists of a standard disposable diaper, as currently available, with adhesive closures and elasticized legs, but without an integral central absorbent layer. A separate disposable absorbent pad is provided in the central crotch area of the disposable diaper, connected to the disposable diaper layer by a releasable adhesive strip. A method of manufacturing the diaper by conventional sandwiching methods in which the absorbent pad is not secured in the diaper, but rather a releasable adhesive strip, or an area for receiving same, is provided in the spine area of the diaper is also provided.

Description

DISPOSABLE NON-ABSORBENT DIAPER SHELL WITH REMOVABLE AND REPLACEABLE ABSORBENT PAD AND METHOD OF MANUFACTURE OF SAME

Technical Field

The invention relates to the construction of infant diapers, and particularly to a disposable diaper having a re-usable non-absorbent shell and a replaceable absorbent pad.

Background Art

Existing infant diapers are of three types: 1) disposable; 2) non- disposable (completely machine washable); and 3) non-disposable (machine washable) fabric shell with replaceable disposable absorbent insert.

Existing disposable diapers comprise a liquid impervious outer layer, an inner non- woven liner and an integral layer of absorbent material, typically pulp fluff or air laid paper, sandwiched between the inner and outer layers. The main drawbacks of the purely disposable diaper are cost and volume of waste, since the entire garment is disposed of after a single use. If the diaper is wetted or soiled even slightly, the entire diaper is discarded, at considerable expense and causing considerable waste. Partially or completely non-disposable diapers generate less waste but are more expensive in initial cost and require work and resources for washing the diaper or shell. For that reason, cloth diapers are less popular than disposable diapers due to the expense, time and labour required to wash them.

There is therefore a need for a purely disposable diaper design which reduces the expense and volume of waste created by allowing the outer liquid impervious, non-absorbent shell of the diaper to be re-used.

Various attempts have been made to make disposable diapers completely flushable. One such attempt has been to provide a water soluble outer shell for the disposable diaper. For example Ecoprogress Limited of Cambridge, England has disclosed in European patent application no. EP 6133362, and international application WO 9309740 published May 27, 1993, a water soluble film for use as the outer layer of a disposable article such as a diaper. The article comprises a bound viscose layer sealed to a water soluble backing layer with an intermediate super-absorbent. The water soluble backing material is made capable of maintaining its integrity during wetting in use by forming it of a layer of relatively soluble material and a layer of less soluble material or it may be a soluble membrane with a discontinuous layer of relatively insoluble material applied to one or more surfaces thereof.

The foregoing structure has not been commercially useful in disposable diapers for two reasons. First the water soluble film product is too expensive to be commercially accepted. Secondly the current structure of disposable diapers provides a layer of absorbent pulp which is glued to the backing shell. The combination of the pulp layer and water soluble backer is not usefully flushable, since it is too bulky, and the layer of non-soluble pulp delays the breakdown of the water soluble layer.

Disclosure of Invention

Consequently, the present invention provides a fully-disposable diaper which, nonetheless, is adapted for multiple uses by means of a removable and replaceable absorbent pad. The disposable diaper of the invention consists of a non- absorbent outer liquid impervious shell, as in a standard disposable diaper, and may have adhesive closures and elasticized legs, but without an integral central absorbent layer. Rather, a separate disposable absorbent pad is provided in the central crotch area of the disposable diaper, and may be connected to the disposable diaper layer by a releasable adhesive strip.

The invention further provides a method of manufacturing the diaper by conventional sandwiching methods in which the absorbent pad or material is not incorporated into the diaper, but rather a releasable adhesive strip, or an area for receiving same, is provided in the crotch area of the diaper.

The invention therefore provides a product and a method of manufac- turing the product. The product has three aspects:

1) a disposable diaper shell without absorbent material in the centre crotch area but capable of accepting a removable and replaceable absorbent pads:

2) a disposable diaper shell with a removable absorbent pad removably secured therein: and 3) a disposable diaper shell without absorbent material in the centre crotch area in combination with a plurality of replaceable absorbent pads which can be secured therein.

The method of manufacture provides a method of producing a disposable diaper without absorbent centre capable of accepting removable and replaceable absorbent pads by following a conventional disposable diaper manufacturing process while omitting the insertion of the absorbent pad material and providing one or more releasable adhesive strips in the spine or crotch area of the diaper. Alternatively the spine or crotch area of the diaper shell can be adapted to receive an absorbent pad insert having a releasable adhesive thereon. The removable pad insert can be manufactured and packaged separately, or alternatively can be inserted into the shell during the manufacturing and packaging process.

Brief Description of Drawings

In drawings which disclose a preferred embodiment of the invention: Fig. 1 is a perspective view of a conventional disposable infant diaper; Fig. 2 is a cross-section taken along line 2-2 of Fig. 1 (not to scale); Fig. 3 is a perspective view of the disposable non-absorbent infant diaper shell of the invention;

Fig. 4 is a cross-section taken along line 4-4 of Fig. 3 (not to scale); Fig. 4 A is a cross-section illustrating a second embodiment of the invention taken along line 4-4 of Fig. 3 (not to scale);

Fig. 5 is a perspective view of the removable/ replaceable absorbent pad of the invention; and Fig. 6 is a cross-section taken along line 6-6 of Fig. 5 (not to scale).

Best Mode(s) For Carrying Out the Invention

Fig. 1 illustrates a conventional disposable diaper 10. It is constructed of an hour-glass shaped backsheet 12 made of a lightweight liquid-impervious polyethylene plastic, a non-woven liner 14 made from a non- absorbent synthetic plastic such as non- woven polypropylene, and an absorbent pad 16 sandwiched between backsheet 12 and liner 14. The diaper has a back waist section 18, front waist section 20, and crotch area 26. Adhesive flaps 28 are provided to attach the garment around the infant. Areas 29 of high gloss polyethylene plastic film are provided on backsheet 12 to which adhesive strips 28 can releasably adhere without tearing the backsheet 12 on removal. Elasticized leg cuffs 30, 32 are formed in the non-woven liner with elastic members 38 running along inner edges 40, 42. Further elastic members 38 are provided along lines 44, 46. Elastic members 38 are typically thin rubber ribbons, or a hot melt elastomeric adhesive may be used as is known in the disposable diaper art.

As illustrated in Figure 2, the non-woven liner 14 comprises three sections, an inner hydrophillic sheet 15 and outer hydrophobic sheets 17. Sheet 15 permits moisture to penetrate to pad 16 while keeping the skin of the infant away from the pad 16. Sheets 17 form the leg cuffs 30, 32 which retain fecal matter and moisture in the central crotch area 26. Absorbent pad 16 is formed of pulp fluff material which is wrapped in a thin layer of absorbent paper tissue to maintain the integrity of the pad and prevent bunching of the fluff. Crystals of super absorbent polymers are typically distributed throughout the fluff to increase the absorbency of the pad 16. In the existing manufacturing process, the two outer hydrophobic sheets 17 are first typically formed by slicing a tensioned sheet of the material and then forming outward folds 19 around elastic members 38. Sheet 15 is then glued or heat welded at either edge 21, 23 to outer sheets 17 along lines 25, 27. In a continuous process, non- woven liner 14, backsheet 12 and pad 16 are then glued or heat welded into a single unitary sandwich, with glue typically applied to the upper surface of backsheet 12 to secure pad 16 and liner 17. A few small spaced drops of glue are also applied to the top of pad 16 in spaced locations to attach it to sheet 15 and prevent movement of the pad 16.

The disposable diaper shell 50 of the present invention is shown in Fig. 3 and 4. The backsheet 52 and liner 54 are formed in a manner similar to the conventional disposable diaper 10, however no absorbent pad or material 16 is provided in the crotch area. Elasticized leg cuffs 62, 64 are formed in outer liner sheets 57. The central hydrophillic liner 15 is omitted and in its place one or more strips 56 having a layer of releasable pressure-sensitive adhesive 59, such as is used on flaps 28, is provided. While the use of three adhesive strips 56 has been shown, one or two such strips would be sufficient for operation of the invention. Use of a single central strip 56a makes attachment of the pad easier and improves the lateral stretchability of the garment. The use of two strips 56b adjacent the leg cuffs reduces the possibility of a gap forming between the pad and the leg cuff along which liquid can flow over the ends of the diaper.

In a second embodiment shown in Fig. 4A, a liner sheet 55 cor- responding to the liner sheet 15 can be included for ease of manufacture, and glued to backer 52 along with liner sheets 57. The adhesive strip or strips 56 are then applied to the upper surface of sheet 55.

To make diaper shell 50 useable, a disposable absorbent pad 70 is provided to attach to adhesive strip or strips 56. The pad is sized to fit snugly up against leg cuffs 62, 64 along either edge 72, 74 and not to extend beyond waist areas 68, 70. Such pad has a mass of absorbent material 75 which may be manufactured from any of the existing absorbent materials, pulp fluff, super- absorbent polymer, air- laid paper, air-laid paper with thermally-bonded super-absorbent polymer materials of the type manufactured by Merfin Hygienic Products Ltd, or fibrous super- absorbent polymer. The absorbent material 75 is preferably wrapped in a layer 76 of non-woven hydrophillic material to keep the skin of the infant from the pad, and may also be provided with an absorbent paper tissue wrap (not shown) between the absorbent material 75 and layer 76 to improve wicking and absorbency. The lower surface 71 of pad 70 is provided with one or more areas 73 of polyethylene plastic film (of the sort used on areas 29 of the conventional diaper in Fig. 1) according to the location of strips 56 in shell 50, to which adhesive strips 56 can releasably adhere without tearing the pad on removal. Alternatively the entire lower surface of pad 70 could be provided with a polyethylene film coating, although it is preferred to leave absorbent areas accessible to the flow of liquid on the lower surface 71 of pad 70.

The pad 70 is manufactured as a separate element and may be packaged and sold separately to the consumer. Shell 50 can similarly be provided to the consumer without a pad 70 secured therein. In that case the adhesive strip 56 on the shell 50 will be provided with a layer of release paper 59 to cover the adhesive 56 until use. Alternatively a pad 70 can be secured to the adhesive strip 56 during the manufacturing and packaging process after the shell 50 has been manufactured. To use the invention in the case of the latter, the consumer will apply the diaper to the infant in the usual way as with the conventional disposable diaper. After the pad 70 has been wet or soiled, it is removed from shell 50 and either flushed down the toilet or placed in a waste disposal container. Shell 50 can then be rinsed, and a fresh pad 70 is applied to adhesive strip 56. After one or more replacement pads have been similarly used, the shell 50 can be discarded and a new shell 50 and pad 70 used. In this way, the disposable diaper shell 50 may be re-used once or several times until it also becomes soiled, or the adhesive strips 56 or adhesive closure strips 28 no longer function. The disposable diaper shell 50 cannot practically be machine washed but in this way an inexpensive disposable diaper shell can be reused at least once and perhaps several times, thereby drastically reducing the consumption of materials and the resulting expense and waste. At the same time, no significant amount of additional work is required by the mother in terms of washing. In this way, the present invention provides a fully-disposable diaper which, nonetheless, is adapted for multiple uses by means of a removable and replaceable absorbent pad.

While preferably the adhesive strips are provided on the disposable diaper shell 50, it will be readily apparent that the releasable adhesive strips could be provided on pads 70 with only a suitable surface to receive the adhesive being provided in the central area 26 of shell 50. The central crotch area of the disposable diaper shell 50 may in that case have a shiny low-friction type of surface which will readily release the adhesive strip attached to the removable absorbent pad/insert and may be strengthened so as not to tear when the pad is removed. Other forms of securement such as hook and loop fastener strips may be used in place of the adhesive strips 56 and indeed the securing strips 56 can be omitted and leg cuffs 62, 64 relied on to hold the pad 70 in place.

While preferably the disposable diaper outer has no absorbent layer, it is possible that certain areas of the outer could incorporate absorbent material to provide additional emergency absorbency for exceptional circumstances, or to improve the fit and shaping of the diaper. Different types of absorbent pad/inserts 70 could be provided, such as those with perfume, disinfectant or anti-bacterial additives and the like. The insert 70 may be bio-degradable and/or flushable. The invention is also applicable to disposable training pants/pull-ups.

Further, while preferably the disposable diaper shell 50 is provided with leg cuffs 62, 64 as in the popular form of disposable diapers, it will be readily apparent that the principle of the invention will also work using a diaper shell 50 which has no leg cuffs 62, 64. In a preferred form of the present invention the outer shell is formed of a water soluble flushable material such as the material referred to as B-9 film manufactured by Ecoprogress Limited of Cambridge, England and disclosed in European patent application no. EP 6133362, and international application WO 9309740 published May 27, 1993. In combination with the invention, the use of such material becomes commercially useful for two reasons. First, the splitting of the shell and absorbent material in the present disposable invention reduces the bulk of the shell and permits the water to access the water soluble film more readily to break it down. The reduced bulk is particularly useful for flushability in modern low volume flush toilets. Secondly, the fact that the shell is re-used several times makes the cost of the more expensive film competitive with standard single use disposable diapers. This latter advantage makes the present invention useful for taking advantage not only of existing water soluble films but other more expensive but useful films or other materials which may be desired for use in disposable diapers. Materials which are desirable for use in the shell or elsewhere in the diaper due to superior physical characteristics such as biodegradability, or breathability, but which have been commercially unacceptable to date due to cost, will be more acceptable for use in the present invention due to the multiple uses possible for each disposable shell and the resultant reduction in cost per use.

As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. A disposable diaper shell comprising a pliant non-absorbent, liquid impervious body for removable fitting to the wearer, forming an interior and an exterior surface, a front and back portion, opposed side edges and a crotch area when so fitted, said diaper shell comprising opposed, non-absorbent liner portions secured along said opposed side edges of said body and forming opposed elastically contractible leg cuffs extending between said front and back portion, said opposed elastically contractible leg cuffs thereby defining a central region between said opposed leg cuffs extending between said front and back portion, said central region being without absorbent material and without any additional liquid impervious layers on said interior surface of said liquid impervious body, said central region being adapted for removably receiving an absorbent pad in said crotch area.

2. The disposable diaper shell of claim 1 wherein said body comprises means for removably securing an absorbent pad in said crotch area, comprising an area of pressure sensitive releasable adhesive on the non-absorbent, liquid impervious interior surface in the crotch area of said body.

3. The disposable diaper shell of claim 1 wherein said diaper shell further comprises a central layer of non-absorbent liner material on the non-absorbent, liquid impervious interior surface in said central region and an area of pressure sensitive releasable adhesive on said central non-absorbent liner in the crotch area of said body.

4. The disposable diaper shell of claim 2 wherein said area of pressure sensitive releasable adhesive on the non-absorbent, liquid impervious interior surface in the crotch area of said body comprises a strip of pressure sensitive releasable adhesive extending centrally in said crotch area between said front and back portion.

5. The disposable diaper shell of claim 2 wherein said area of pressure sensitive releasable adhesive on the non-absorbent, liquid impervious interior surface in the crotch area of said body comprises two parallel strips of pressure sensitive releasable adhesive in said crotch area adjacent respective ones of said leg cuffs and extending between said front and back portion.

6. The diaper shell of claim 1 wherein said pliant, non-absorbent, liquid impervious body comprises a polyethylene plastic film.

7. The diaper shell of claim 2 further comprising .an absorbent pad adapted for removably securing to said central region in said crotch area, said pad comprising a layer of absorbent material and upper and lower surfaces, said lower surface being adapted for removably receiving and releasing a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer.

8. The diaper shell of claim 3 further comprising an absorbent pad adapted for removably securing to said central region in said crotch area, said pad comprising a layer of absorbent material and upper and lower surfaces, said lower surface being adapted for removably receiving and releasing a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer.

9. The diaper shell of claim 7 wherein said lower surface of said absorbent pad is provided with areas of a polyethylene plastic film.

10. The diaper shell of claim 8 wherein said lower surface of said absorbent pad is provided with areas of a polyethylene plastic film.

11. The diaper shell of claim 7 wherein said upper surface of said absorbent pad comprises a non-woven hydrophillic outer layer.

12. The diaper shell of claim 8 wherein said upper surface of said absorbent pad comprises a non-woven hydrophillic outer layer.

13. In combination in a package, the diaper shell of claim 28 and a plurality of absorbent pads, each said pad comprising a layer of absorbent material and upper and lower surfaces, said lower surface being adapted for removably receiving and releasing a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer.

14. In combination in a package, the diaper shell of claim 3 and a plurality of absorbent pads, each said pad comprising a layer of absorbent material and upper and lower surfaces, said lower surface being adapted for removably receiving and releasing a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer.

15. The diaper shell of claim 1 further comprising an absorbent pad adapted for removably securing to said central region in said crotch area, said pad comprising a layer of absorbent material and upper and lower surfaces, said lower surface comprising a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer.

16. In combination in a package, the diaper shell of claim 1 and a plurality of absorbent pads, each said pad adapted for removably securing to said central region in said crotch area, said pad comprising a layer of absorbent material and upper and lower surfaces, said lower surface comprising a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer.

17. A method of manufacturing a diaper shell without absorbent material in the crotch area thereof and adapted for removably securing an absorbent pad, said method comprising bonding in a continuous process a sheet of non-woven hydrophobic liner material to a sheet of liquid impervious backsheet material, providing a releasable adhesive strip along the central surface area of said backsheet and cutting said bonded sheets to form a disposable diaper shell comprising a non-absorbent, liquid impervious body and a non-absorbent liner having opposed elastically contractible leg cuffs, said diaper shell being without absorbent material in said crotch area of said body and being adapted for removably securing an absorbent pad in said crotch area.

18. A method of manufacturing a combination disposable diaper shell with non- absorbent crotch area and removable absorbent pad comprising: i) following a conventional disposable diaper manufacturing process while omitting the insertion of the absorbent material, and providing a releasable adhesive strip in the crotch area of said diaper shell; ii) manufacturing a roll of absorbent pad material adapted for securing to the crotch area of a garment said pad having upper and lower surfaces, said lower surface being adapted for removably receiving and releasing a pressure sensitive adhesive area, and said upper surface of said pad comprising a hydrophillic outer layer; iii) securing the pads to the diaper shell in a continuous process.

19. The disposable diaper shell of claim 1 wherein said pliant, non-absorbent, liquid impervious body comprises a water soluble film.

20. The disposable diaper shell of claim 1 wherein said pliant, non-absorbent, liquid impervious body comprises a biodegradable film.