GB2256803A

GB2256803A - Disposable diaper

Info

Publication number: GB2256803A
Application number: GB9212147A
Authority: GB
Inventors: Masamichi Senoo; Masao Kurahashi; Harumitsu Toyoda
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 1991-06-21
Filing date: 1992-06-09
Publication date: 1992-12-23
Also published as: JPH053889A; JP3213017B2; GB9212147D0

Abstract

The diaper (11) has front, rear and crotch portions and comprises a liquid permeable topsheet (12), a liquid impermeable backsheet (13) and an absorbent member (14) disposed between them. An elongate liquid permeable inner sheet (15) is situated adjacent the topsheet (12) and extends over the crotch portion, the two end portions (25, 26) of the inner sheet being connected to the front and rear portions, respectively, of the tops hoot. The connection of at least one of the end portions (25, 26) to the topsheet (12) is releasable and constituted by peelable adhesive or a line of perforations. The sides of the inner sheet are provided with expansible members (17) which, in use, form gathers. <IMAGE>

Description

DISPOSABLE DIAPERS This invention relates to disposable diapers, and is concerned with such diapers which are provided with an additional inner sheet which permits solid waste material to be disposed of separately from the remainder of the diaper.

Disposable diapers are, as the name indicates, intended to be discarded after use. When discarded, waste material is usually wrapped up within the whole disposable diaper which is then fastened by a tape fastener or the like and discarded into a waste bin or the like.

However, it is not desirable, for hygenic and aesthetic reasons, to keep solid waste material wrapped up in a disposable diaper in a waste bin in a house, even for a short period of time. Disposable diapers also give rise to environmental sanitation problems due to the fact that diapers with waste materials therein are often left as refuse together with other rubbish in public places, such as parks.

In order to reduce these problems, the user and/or an accompanying adult sometimes removes the solid portion of the waste materials, e.g. faeces, from the diaper and washes it away into a toilet, and only thereafter discards the diaper.

This is usually done by firstly securing the diaper to a toilet bowl and then carefully washing the content of the diaper away. However, faeces heavily adhered to the diaper are very difficult to wash away and there is a risk that the user's hands will become dirty. The process is also difficult and troublesome and means that the diaper does not fulfil its primary requirement, i.e.

that it be clean, si#mple and convenient. Moreover, there is the risk that, when washing the solid material from the diaper, the diaper will absorb water and thus become heavy and liable to drip filthy water. If the diaper itself is inadvertently washed away into the toilet bowl, it is liable to clog the drain pipe.

Diapers intended to facilitate the processing and discarding of waste materials on the topsheet of a disposable diaper are disclosed in U.S. Patent No.2450059 and Japanese Patent Publication No. Sho 53-26175, in which the topsheet is of multilayer structure, and an uppermost layer thereof is peeled off in order to enwrap the waste materials for easy disposal.

Japanese Patent Publication No. Sho 54-29932 discloses a diaper which includes a separable central portion, which can be discarded together with waste materials discharged thereon.

However, the above known diapers have certain shortcomings because the entire surface of the topsheet is bonded to the backsheet or the absorbent member which means that the topsheet does not smoothly follow the movement of the wearer and readily separates from the wearer's skin. Moreover, with these diapers, the topsheet or the absorbent member formed of a flap pulp is washed away together with the waste materials in the toilet bowl. However, disposable diapers, which are currently commercially available, are mostly formed of water-insoluble materials, such as synthetic fibres and a highly water absorbent polymer, and it is not desirable for such materials to be discarded in a toilet bowl.The known diapers also have the disadvantage that the job of peeling off the uppermost layer of the topsheet in order to enwrap the waste materials requires a considerable amount of care and training.

It is therefore an object of the present invention to provide a disposable diaper in which the uppermost or innermost sheet smoothly follows movements of the wearer and a solid waste material can be easily processed either by discarding it wrapped within the innermost sheet separately from the main body of the disposable diaper or by washing away only the solid portion of the waste material into a toilet bowl.

According to the present invention a disposable diaper having a front portion, a rear portion and a crotch portion comprises a liquid permeable topsheet, a liquid impermeable backsheet, an absorbent member disposed between the topsheet and the backsheet and an elongate liquid permeable inner sheet situated adjacent the topsheet and extending over the crotch portion, the two end portions of the inner sheet in the longitudinal direction thereof being connected to the front and rear portions, respectively, of the topsheet, the connection of at least one of the end portions to the topsheet being releasable and the sides of the inner sheet being provided with expansible members which, in use, form gathers.

Thus in the disposable diaper in accordance with the present invention the two ends of the inner sheet are secured to the topsheet and the provision of the expansible members along the sides of the inner sheet means that it adopts a U shape, in use, and readily fits against the wearer's undercrotch region. The gathered edges of the inner sheet thus follow the configuration of the wearer's undercrotch region. The inner sheet constitutes a pocket due to the provision of the expansible members and leakage of solid waste material is thus prevented.

In use, when the diaper has been soiled with solid waste material, the diaper is removed from the wearer and the side edges of the inner sheet rise upwardly and inwardly due to the expansible members and thus retain and virtually wrap the waste material therein. If the connection of each end of the inner sheet is a releasable connection, the two connections are then released and the solid waste material removed from the diaper within the inner sheet. The waste material can then be disposed of, either separately from the inner sheet or together with it, e.g. into a toilet bowl whilst the remainder of the diaper may be disposed of separately.If the connection of only one of the ends of the inner sheet is releasable, this connection is released and the solid waste material is then removed from the inner sheet, e.g by washing it into a toilet bowl whilst the remainder of the diaper is remote from the water in the toilet bowl and thus need not be wetted.

Due to the presence of the expansible members along the sides of the inner sheet, the inner sheet is formed into a shape generally similar to a bag in which the waste material may be easily retained or enclosed and which may easily be lifted by grasping its end portions between the fingers. The inner sheet can therefore easily be picked up without any risk of dropping the waste material therein and discarded into a toilet bowl.

The releasable connection of one or both ends of the inner sheet to the top sheet may be effected by means of a peelable adhesive or alternatively a line of spaced slits or perforations may be formed in the inner sheet whereby the inner sheet may be torn along the line of perforations.

Further features and details of the invention will be apparent from the following description of one specific embodiment which is given by way of example with reference to the accompanying drawings, in which: Figure 1 is a plan view of a disposable diaper in accordance with the present invention; Figure 2 is a perspective view showing how solid waste material is enwrapped with the diaper of Figure 1 for separate disposal; and Figure 3 is a view similar to Figure 2 showing a further stage in the wrapping of solid waste material.

The disposable diaper 11 is shown flat in Figure 1 with that surface which contacts the wearer uppermost and a part of the diaper is cut-away in order to clarify its structure.

The diaper 11 comprises a liquid permeable topsheet 12, a liquid impermeable backsheet 13, an absorbent member 14 disposed between the topsheet 12 and backsheet 13 and a liquid permeable inner sheet 15 attached to the topsheet 12. The inner sheet 15 is of rectangular shape and extends from the rear waist portion 21 of the diaper over the crotch portion 22 to the front waist portion 23. The sheet 15 includes elastic expansible members 29 disposed adjacent both longitudinal side portions. Both end portions 25 and 26 of the removable sheet 15 in the longitudinal direction are secured to the topsheet 12, in this case removably by means of peelable adhesive.

The diaper 11 is further provided with side flaps 24 extending laterally of the absorbent member 14, each of which includes a side flap elastic member 17 disposed between the backsheet 13 and the topsheet 12, so that gathers are formed around the legs of the wearer in order to enhance the fit of the diaper and its leakage properties.

The diaper 11 is of overall generally rectangular shape but is recessed in the vicinity of the croth portion 22 to form leg openings. The backsheet 13 and the topsheet 12 are of approximately equal length and width.

The backsheet is, in general, an opaque polyethylene sheet of low density having a thickness of 10 to 60u, and is preferably a vapour permeable, liquid impermeable porous sheet which scarcely generates a rubbing or crumpling sound and scarcely causes rashes. The expression "rubbing or crumpling sound" refers to the sound which is generated when a sheet is crumpled or rubbedagainst itself. The topsheet 12 is, in general, a non-woven fabric of 15 to 40g/m2, but it may be a film, net and the like provided it has liquid permeable properties. Particularly preferably, the peripheral portion of the topsheet 12 has water repellent properties and the central portion thereof has hydrophillic properties.

The side flap elastic members 17 may be a polyurethane and a natural rubber material formed into a ribbon shape or a yarn which exhibits expanding and contracting properties when wetted. Usually, 1 to 5 such ribbons or yarns constitute each elastic member. The length of each side flap elastic member 17 is approximately 30 to 60% of the length of the diaper and its expansion is preferably about 1.3 to 2.0 times its free length.

The absorbent member 14 may be a cotton-like member formed of a crushed Kraft pulp of a needle-leaf tree and covered with water absorbent paper. Pulp with a high molecular weight water absorbent polymer impregnated therein is particularly preferred. The weight of the cotton-like member is typically about log to 40g. The high molecular weight water absorbent polymer may be located in the upper layer, the intermediate layer or the lower layer of the absorbent member or be distributed throughout its thickness. The water absorbent polymer may be in granular form from the protein series, cellulose series or synthetic polymer series. Suitable examples of such a high molecular weight water absorbent polymer are starch-acrylic (salt) graft copolymer, a saponified material of starch-acrylonitrile copolymer, bridged material of sodium carboxymethylcellulose, acrylic (salt) polymer and the like.Such polymer grains have the ability to absorb and retain more than twenty times their own weight of liquid and may be gelled.

The liquid permeable inner sheet 15 extends along the length of the disposable diaper 11 adjacent the upper, inner surface of the topsheet 12. Both end portions 25 and 26 of the removable sheet 15 are bonded to the inner sheet 12 at its rear waist portion 21 and front waist portion 23. The central portion of the removable sheet 15 is not so bonded but forms a free portion 27.

Although a central portion of the liquid permeable inner sheet 15 is not bonded to the topsheet 12 in this embodiment, it may be bonded to it if the shape-holding ability of the U-shaped inner sheet and its fit are taken into account.

The width of the inner sheet 15 is preferably about 30 to 70% of the maximum width of the disposable diaper 11 and particularly preferably narrower than the minimum width of the crotch portion 22 of the absorbent member 14 so as to effectively utilise the absorbency of the absorbent article 14. The length of the inner sheet 15 is not necessarily equal to the length of the diaper 11 and it is preferred that it is substantially shorter. When flat, the inner sheet 15 may be of hourglass shape, that is to say the width of the free portion 27 may be less than that of the front and rear end portions 25 and 26, so that it can be more intimately fitted to the crotch portion of the wearer. However, the width of the front and rear end portions 25 and 26 may be equal to or greater than that of the free portion 27.

The elastic expansible members 29 arranged on the inner sheet 15 are disposed along its longitudinal side edges.

As is shown in Figure 2, when in a natural state, the free portion 27 forms a bag-like pocket 31 and two gathers 32. By forming such a pocket 31, when the diaper 11 is in use, solid waste material A is held on the inner sheet 15, and the gathers 32 intimately fit against the wearer and thus prevent leakage of the solid waste material A.

With regard to the material of the inner sheet 15, liquid permeable sheets such as non-woven fabrics, mesh sheets, porous sheets, and elastic sheets may be used. In order to prevent leakage of water-abundant, i.e. soft faeces, the inner sheet may have an absorptivity of 5g/cm2 or more. Alternatively, a water soluble material may be used so that the inner sheet 15 can be washed away directly in the toilet bowl. Examples of such water soluble materials are rayon and/or pulp sheets made by a wet paper making method and sheets formed of a water soluble resin such as a polyvinyl alcohol.

The peeling force required to peel off the inner sheet 15 is preferably between 35g/25mm and 150g/25mm, more preferably between 50g/25mm and 100g/25mm, when dry, and between 25g/25mm and 100g/25mm, more preferably between 25g/25mm and 75g/25mm, when wet. If the peeling force is in this range, the inner sheet will not be peeled off at the time when the diaper is put on or during the time the diaper is worn, but can be easily peeled off when solid waste material is to be discarded. Furthermore, the inner sheet 15 and topsheet 12 are not torn when the inner sheet 15 is peeled off. The peeling force can be easily adjusted by adjusting the bonding strength of the front and rear portions 25 and 26.

The peeling force is tested as-follows: Test samples are prepared by cutting out portions of the inner sheet 15 and the topsheet 12, which are connected together and have a width of 25mm. The ends of both sheets are pulled by a tension testing instrument and the strengths are measured. The measurement of the dry peeling force is effected at a temperature of 200C and a relative humidity of 60%, while the wet peeling force is measured whilst the test samples are saturated with water.

With regard to the adhesive, a hot melt type adhesive is preferred. As regards the properties of the adhesive, adhesive is preferably left on both the inner sheet 15 and topsheet 12 when the inner sheet 15 is peeled off.

The reason for this is that the inner sheet 15 can be secured when rolled up for discarding purposes and therefore maintained sanitary and a fresh inner sheet can be attached to the topsheet 12.

The mode of operation of this embodiment is as follows: In a manner similar to that used with a conventional disposable diaper, when the diaper of the present invention is to be worn, the inner sheet 15 is brought into contact with the wearer's skin, with the rear waist portion 21 abutted against the back of the wearer and with the front waist portion 23 abutted against the stomach of the wearer and then a tape fastener 16 on each side of the rear waist portion 21 is attached to a target tape 33 (see Figure 2) on the stomach side.

When the diaper is being worn, leg gathers are formed around the leg of the wearer by the side flap elastic members 17 in order to prevent leakage of waste material and the free portion 27 of the inner sheet 15 forms a pocket 31 for receiving solid waste material.

The front and rear ends of the inner sheet 15 are secured to the topsheet 12 in order to match it to the configuration of the wearer's crotch, while the free portion 27 follows the movement of the wearer separately from the remainder of the disposable diaper 11. Since the inner sheet 15 is maintained in intimate contact with the skin of the wearer by the elastic expansible members 29 on the inner sheet 15, the fit of the inner sheet 15 is further improved. Therefore, leakage of solid waste material A from the sheet 15 can be reliably prevented.

In order to discard accumulated solid waste material A, the diaper is removed and both side portions of the inner sheet 15 are raised away from the topsheet 12 by the elastic expansible members 29 so that a space or clearance is formed between the inner sheet 15 and the topsheet 12. The two side portions of the sheet 15 thus rise up together so as to enwrap the waste material and the two adhesive connections are peeled apart to separate the inner sheet 15 from the topsheet 12. The two end portions 25,26 are moved close to each other so that the sheet 15 is formed into a round shape similar to that of a bag. The solid waste material is thus not liable to be dropped during the disposal process. Thus, as shown in Figure 3, the sheet 15 is formed into a bag shape in order to transport the solid waste material A and discarded directly into the toilet bowl together with the waste material.Alternatively, sheet 15 may be discarded separately after the waste material has been washed away from the disposable diaper by a water jet in the toilet bowl. Since the solid waste material can be easily removed from the disposable diaper and discarded into a toilet bowl with one hand, the disposable diaper does not adversely affect the environmental sanitation even if it is left with ordinary rubbish.

If the inner sheet 15 is formed of a water soluble material, it dissolves in a toilet bowl thereby making it easy to handle.

The present invention is not limited to the above embodiment. Various modifications can be made without departing from the scope of the present invention.

For example, the removable connection of the inner sheet 15 to the topsheet 12 need not be provided by adhesive and in one modification slits (or perforations) are formed in the free portion 27 at areas near the front and rear end portions 25 and 26 across the width thereof.

The end portions 25,26 are then permanently connected to the topsheet 12 but the remainder of the inner sheet 15 may be removed by tearing it along the perforated lines.

The perforations are so dimensioned and spaced that the sheet 15 has sufficient strength in the longitudinal direction but may be relatively easily torn in the lateral direction.

In the embodiments described above the inner sheet 15 is removably connected to the topsheet 12 at both ends.

However, the connection at one end may be permanent and it is only necessary that the connection at one of the two ends be releasable, e.g. constituted by peelable adhesive or a perforated line. In this case, in use, the connection is released at one end of the sheet 15 and the solid waste material discarded or washed away whilst keeping the remainder of the diaper sufficiently remote from e.g. the water in the toilet bowl. Thereafter the diaper is disposed of together with the inner sheet 15.

Claims

1. A disposable diaper having a front portion, a rear portion and a crotch portion and comprising a liquid permeable topsheet, a liquid impermeable backsheet, an absorbent member disposed between the topsheet and the backsheet and an elongate liquid permeable inner sheet situated adjacent the topsheet, and extending over the crotch portion, the two end portions of the inner sheet in the longitudinal direction thereof being connected to the front and rear portions, respectively of the topsheet, the connection of at least one of the end portions to the topsheet being releasable and the sides of the inner sheet being provided with expansible members which, in use, form gathers.

2. A diaper as claimed in claim 1 in which the inner sheet is connected to the topsheet by a peelable adhesive connection.

3. A diaper as claimed in claim 2 in which the adhesive remains both on the inner sheet and the topsheet when the inner sheet is peeled away from the topsheet.

4. A diaper as claimed n claims 2 or 3, in which the or each connection has a peeling strength of 35 to 150g/25mm when dry and 25 to l00g/25mm when wet.

5. A diaper as claimed in claim 1, in which the inner sheet is tearably secured to the topsheet by one or more lines of perforations.

6. A diaper as claimed in any one of claims 1 to 5, in which the inner sheet is water soluble.

7. A diaper as claimed in any one of claims 1 to 6 in which the water absorption capacity of the inner sheet is 5g/cm2 or more.

8. A disposable diaper substantially as specifically herein described with reference to the accompanying drawings.