WO1999055266A1

WO1999055266A1 - Diaper containing a washable absorption element

Info

Publication number: WO1999055266A1
Application number: PCT/NL1999/000253
Authority: WO
Inventors: Gregorius Maria Hubertus Goyarts
Original assignee: Goyarts BV
Current assignee: Goyarts BV
Priority date: 1998-04-29
Filing date: 1999-04-28
Publication date: 1999-11-04
Anticipated expiration: 2000-10-29
Also published as: NL1009034C2; AU3540199A; CA2330592A1

Abstract

An absorption element is described which consists of a liquid-absorbing layer (2) and liquid-transporting layers (3 and 4) in which, according to the invention, a large number of perforations (9) are arranged. Owing to the presence of the perforations (9), the drying time of the absorption element (1) is considerably shortened. The invention also relates to an application composition such as trainer pants or a pad, which incorporates at least a perforated absorption element (5, 20) according to the invention and is optionally permanently joined thereto.

Description

DIAPER CONTAINING A WASHABLE ABSORPTION ELEMENT

The invention relates to a washable absorption element which is suitable for reuse and which, seen in its vertical extent, comprises at least one liquid-absorbent layer which comprises a mixture of chemical and synthetic fibres and which, on its top and bottom side, is bonded to one or more liquid-transporting layers made of non woven material, which substantially comprise synthetic fibres.

Such a washable absorption element is disclosed by WO 97/34554 issued to the applicant. This publication describes an absorption element of the specified type, wherein the liquid-absorbent layer comprises a mixture of chemical and synthetic fibres such as viscose or polyester, and where the liquid-transporting layers consist of nonwoven material which substantially comprises synthetic fibres such as polyester.

The absorption element contains less than 100%, e.g. from 90 to 10% of chemical fibres such as viscose, and additional material to make up 100%, e.g. from 10 to 90% of synthetic fibres such as polyester. Expediently, the level of chemical fibres such as viscose is from 80 to 20%, whilst the proportion of synthetic fibres such as polyester takes up from 20 to 80%.

The abovementioned percentages are percentages by weight . To obtain optimal absorption capacity of the absorption element, the chemical fibres fraction preferably comprises fibres having a thickness of from 1 to 8 dTex and a length of from 30 to 100 mm, whilst the synthetic fibres fraction in the absorbing layer comprises fibres having a thickness of from 1 to 10 dTex and a length of from 30 to 100 mm.

Expediently, the synthetic fibres such as polyester in the liquid-absorbent layer can additionally comprise polyester having a thickness of less tha 1 dTex and a length of from 30 to 80 mm.

In particular, the liquid-absorbent layer of the absorption element comprises from 60 to 90% of chemical - 2 - fibres such as viscose and from 40 to 10% of synthetic fibres such as polyester, and preferably from 75 to 85% of viscose and from 25 to 15% of polyester.

Where reference has been made hereinabove to synthetic fibres and polyester is mentioned as an example, it should be noted that the synthetic fibre may also consist of polyamide, polyacrylic, polyethylene and polypropylene or modified forms thereof, or of mixtures of two or more of such fibres . Very good results are also obtained with polypropylene fibres in the quantities, thicknesses and lengths specified above with respect to polyester.

The chemical fibre preferably comprises viscose which may or may not be modified. Although, in terms of absorption capacity, the absorption element outlined in the above provides excellent results and said element also exhibits excellent washability, rapidly releasing the contaminating matter which is absorbed, the drying rate of the absorption element after washing for the purpose of reuse is still open to improvement .

It is an object of the present invention to provide a solution to the said drawback, the invention to this end being characterized in that the absorption element is provided with a large number of perforations which extend at least over part of the vertical extent of the absorption element .

It is found, surprisingly, that arranging perforations over at least part of the vertical extent of the absorption element does not significantly reduce the absorption capacity, while on the other hand the drying rate of the absorption element after washing for the purpose of reuse is considerably increased.

Expediently, the perforations are arranged in a regular pattern.

Said pattern can take a large variety of forms, such as a triangular, quadrangular or hexagonal pattern; a quadrangular pattern is quite satisfactory.

The pattern of holes can also be positioned on a - 3 - family of regularly arranged lines which may or may not be curved, such as a family of straight lines, sawtooth lines, sinusoidal lines and the like.

The perforations can be introduced in many ways, for example by the use of heated steel pins; hollow tubes which may or may not be heated; water jet perforation, laser perforation and many other ways which will be evident to those skilled in the art.

The dimensions and spacing of the perforations is critical because of possible delamination of the layers. Given the fibre lengths and thicknesses in an absorption element according to the invention, the perforations will generally have a diameter of from 1 to 5 mm and a centre- to-centre spacing of from 8 to 30 mm. In a preferred embodiment, the perforations have a diameter of about 3 mm and a centre-to-centre spacing of about 12 mm.

In addition to circular, the shape of the perforations can also be square, triangular, oval, star-shaped or the like, whilst combinations of shapes can also be present .

The absorption element outlined above has liquid- transporting layers on both sides in the form of a layer made of nonwoven material which substantially comprises synthetic monofilaments . Because of the mechanical stresses to be expected in the washing treatment it is advantageous for the absorption element to be covered on at least one side by a liquid-permeable covering layer of synthetic fibres, said liquid-permeable covering layer of synthetic fibres having a knitted or woven structure, on the grounds of mechanical strength.

The synthetic fibres of the liquid-permeable covering layer can be the synthetic fibres as mentioned hereinabove, i.e. polyester, polyamide, polyacrylic, polypropylene, polyethylene, good utility being ensured by polyester and polypropylene .

The novel absorption element described here, which is provided with perforations to improve the drying rate, comprises, on at least one side of the absorption element, - 4 - a spacing structure made of synthetic onofilaments, said spacing structure being disposed between the surface of the absorption element and the liquid-permeable covering layer. If a spacing structure is present only on one side of the absorption element, said spacing structure will preferably be positioned on that side of the absorption element which is closest to the body of the user. The spacing structure may or may not be permanently joined to the absorption element . Regarding the joining of the layers of the absorption element to one another and the possible joining of the spacing structure to the absorption element, reference is made to the abovementioned WO 97/34554, which states, regarding the joining together of the layers of the absorption element, that the layers are expediently bonded to one another with interpenetration of the fibres of the one layer into the other, and that said bonding can be effected by means of needling.

In an expedient embodiment, the needling of two sides of the absorption element has taken place, said needling being able to take place, if desired, simultaneously from two sides of the absorption element. The liquid-absorbent layer of the absorption element generally has a thickness of between 0.5 and 25 mm, and the liquid- transporting layers generally have a thickness of between 0.25 and 10 mm. Following the bonding treatment of the layers, the absorption element material can be subjected to a thermofixation treatment, for example at a temperature of at most 185°C, to reduce shrinking of the element in use. For further details on the absorption element reference should be made to the abovementioned WO 97/34554 which is incorporated herein by reference .

The above-described spacing structure which may form part of the absorption element will, if joining of the spacing structure and the absorption element has taken place, likewise optionally be joined to the absorption element with the aid of needling techniques. The fastening method is, however, not limited thereto; equally conceivable are local fusing of the spacing structure with - 5 - the absorption element or local gluing together thereof.

The spacing structure expediently is a knitted material made of synthetic filaments, the materials capable of being used being those specified previously; preferably, the structure is a knitted polyester material.

The invention also relates to an application composition, such as trainer pants or a pad, which comprises a liquid-impermeable synthetic material and an absorption element, said application composition being characterized in that it comprises an absorption element according to the invention as described hereinabove and preferably an absorption element which on at least one side is covered by a liquid-permeable covering layer made of synthetic fibres, on at least one side a spacing structure optionally also being present.

The application composition is not restricted to a trainer pants or pad; application is also possible in the packaging industry, furniture industry, automotive industry, agricultural and horticultural bonded fibre webs, bonded fibre webs for roofing, insulation materials, drainage media, filter materials, fume cupboards, fire blankets, absorption blankets, clothing such as sports clothing and sports accessories, also workwear, protective material against, for example, oil (in this case a laminated film can be applied to the absorption element) , horse blankets, saddlecloths, absorption material for animal cages and the like, such as, for example, cat litter, cleaning articles, incontinence and decubitus materials, mattress covers, bandaging materials, and blankets to play on and to be used in playpens, for children.

In a highly attractive embodiment, the absorption element in the application composition according to the invention, on the side which will come into contact with the body of the user, comprises a liquid-permeable covering layer of synthetic fibres, which covering layer projects beyond the absorption element and is joined to the liquid- impermeable material of the application composition. As a result of the covering layer made of synthetic fibres being - 6 - joined to the liquid-impermeable material of the application composition such as trainer pants or a pad, an application composition comprising an absorption element is obtained, which forms a whole and which can as such be subjected to a washing operation for reuse.

The liquid-permeable covering layer made of synthetic fibres is generally of such fineness that liquids can pass through, but solid particles of, for example, faeces cannot, so that an accumulation of solids within the absorption element or within the liquid-permeable covering layer and the liquid-impermeable material is substantially prevented.

In a highly attractive embodiment of the application composition according to the invention as described hereinabove, in which the covering layer made of synthetic fibres is joined to the liquid-impermeable material, a spacing structure made of synthetic fibres is present on both sides of the absorption element.

The invention will now be described with reference to the drawing, in which:

Figure 1 shows a transverse section of a perforated absorption element according to the invention;

Figure 2 shows an absorption element as in Figure 1, which is surrounded by liquid-permeable covering layers;

Figure 3 shows the principle of the way in which the various layers of the absorption element are joined to one another;

Figure 4 schematically shows trainer pants with an absorption element incorporated therein; and

Figure 5 shows a schematic transverse section of the trainer pants according to Figure 4 with an absorption element permanently incorporated therein.

In Figure 1, an absorption element according to the invention is indicated by 1 and comprises a liquid- absorbent layer 2 and on both sides thereof liquid- transporting layers 3 and 4. The absorption element is provided with perforations 9 to improve the washing and drying rate for the purpose of reuse. The liquid-absorbent - 7 - layer comprises from 50 to 80% of viscose and from 20 to 50% of polypropylene, from 0.01 to 40% of the polypropylene optionally being polypropylene with fibres of a thickness of 1 dTex. The standard polypropylene fibres have an average thickness of 7 dTex and an average length of 60 mm, whereas the viscose fibres have an average thickness of 3 dTex and a length of 60 mm. The liquid-transporting layers 3 and 4 substantially comprise polypropylene, a fraction of which, from 0.01 to 40%, being polypropylene of a thickness of about 1 dTex. The polypropylene fibres have an average thickness of 7 dTex and a length of 60 mm. The abovementioned synthetic fibres may also comprise polyester, with the same beneficial impact on the accelerated drying effect. The perforations 9, in this specific case, have a diameter of about 3 mm, whilst the centre-to-centre spacing is about 12 mm. Other values for the diameter or the centre-to-centre spacing can lie within the ranges specified hereinabove in connection with the claims. The perforations 9, in the absorption element 1, extend across the entire vertical extent of the absorption element .

Good drying results are also achieved if the perforations only extend across the liquid-absorbent layer 2.

The absorption element in Figure 1 is drawn as a three-layer element having layers 2, 3 and 4. Also within the scope of the invention, however, are elements having four, five or more layers, although preferably care will be taken to ensure in such an arrangement that at least the top and bottom layer of the element are liquid-transporting layers which substantially consist of synthetic fibres.

Optionally, perforations can be introduced over the entire vertical extent of the absorption element or over part of the vertical extent of the absorption element. If the perforations are introduced over part of the vertical extent of the absorption element, expediently at least part of the liquid-absorbent layer or layers will be provided with perforations. - 8 -

Figure 2 shows the absorption element according to Figure 1, which is enclosed between a covering of liquid- permeable material in the form of covering layers 6 and 7, which are joined together at 8 to form a sealed envelope within which the absorption element is accommodated. Joining the layers 6 and 7 can be effected by welding, gluing, stitching etc. The liquid-permeable covering layers 6 and 7 are expediently made from polyester, the material having a knitted or woven structure to improve the mechanical strength and preferably having a knitted structure. Advantageously, at least on that side of the absorption element which comes to lie against the body of the user, the polyester substrate has been knitted, roughened and then cropped, in order to impart to the material a very soft character which, moreover, readily releases solids from faeces.

Figure 3 schematically shows how the various layers, for example the viscose- and polypropylene- containing layer 2 and the polypropylene-containing layer 3 are joined together. The interpenetration of fibres from the layers 2 and 3 is effected by a needle treatment in which needles penetrate via one layer as far as into the second layer and on the return stroke pull along fibres from the second layer until these extend into the first layer. This needling or needle treatment can take place from one side of the absorption element but may also be carried out from two sides, possibly simultaneously.

Figure 4 diagrammatically shows trainer pants with an absorption element according to the invention incor- porated therein. The trainer pants 10 consist of a liquid- impermeable material such as, for example, polyurethane , whilst a liquid-absorbing element of the type as described in Figure 2 is incorporated in the trainer pants . The trainer pants, as customary, have closure means 13 which expediently comprise a velcro strip material, and customary leakage prevention edges 11. 12 indicates a piece of elastic which is fitted at the rear of the trainer pants and which ensures that the trainer pants 19 with the absorption element 5 present are more comfortable to wear. - 9 -

In Figure 4, the absorption element can be inserted as a removable element; alternatively, however, absorption element 5 can be permanently joined to the trainer pants, as shown in Figure 5. Figure 5 schematically shows an absorption element 20 with liquid-transporting layers 23 and 24 and a liquid-absorbing layer 30. The absorption element comprises perforations 25 of the type described previously, which run through the absorption element over its entire vertical extent. The absorption element is surrounded on both sides by spacing structures 26 and 27 which, for example, consist of a knitted material or woven material made of polyester or polyamide and which reduce the risk of decubitus when used as a nappy or incontinence material . The spacing structures further contribute to an improved washing/drying time; provide better absorption distribution, contribute to softer handle of the entire composition and potentially serve as an additional moisture storage space . Although polyester or polyamide is a convenient material for the spacing structures, other synthetic fibres of moisture-permeable character can likewise be used. The moisture-impermeable material which forms part of the trainer pants or pad is indicated by 31; this material can be polyurethane, for example. 28 indicates a liquid-permeable covering layer of synthetic fibres such as polypropylene, the liquid-permeable covering layer being joined, at 29, to the liquid-impermeable material 31, welding, gluing or stitching or the like being suitable options. The composition thus obtained of liquid- impermeable material 31, an absorption element 20 having perforations 25, and a liquid-permeable covering layer 28 made of synthetic material form a contextural whole which, when washed for purposes of reuse, retains its contexture. Trials have indicated that the drying time of such a composition in a typical case is from 0.5 to 0.75 hour for a composition in which an absorption element according to the invention having perforations is used, whereas the same composition, which contains an absorption element without perforations, under the same conditions required a drying time after washing for the purpose of reuse of from - 10 -

1.25 to 1.5 hours.

Claims

- 11 -CLAIMS

1. Washable absorption element (1, 5) which is suitable for reuse and which, seen over its vertical extent, comprises at least one liquid-absorbent layer (2) which comprises a mixture of chemical and synthetic fibres and which, on its top and bottom side, is bonded to one or more liquid-transporting layers (3, 4) made of non woven material, which substantially comprise synthetic fibres, characterized in that the absorption element (1, 5) is provided with a large number of perforations which extend at least over part of the vertical extent of the absorption element (1, 5) .

2. Absorption element (1, 5) according to claim 1, characterized in that the perforations (9) are arranged in a regular pattern.

3. Absorption element (1, 5) according to claim 1 and 2, characterized in that the perforations (9) are arranged in a quadrangular pattern.

4. Absorption element (1, 5) according to one or more of claims 1 to 3 inclusive, characterized in that the perforations (9) have a diameter of from 1 to 5 mm and a centre-to-centre spacing of from 8 to 30 mm.

5. Absorption element (1, 5) according to claim 4, characterized in that the perforations (9) have a diameter of about 3 mm and a centre-to-centre spacing of about 12 mm.

6. Absorption element (1, 5) according to one or more of the preceding claims, characterized in that the absorption element (1, 5) on at least one side is covered by a liquid-permeable covering layer (6, 7) of synthetic fibres.

7. Absorption element (1, 5) according to claim 6, characterized in that the liquid-permeable covering layer (6, 7) made of synthetic fibres has a knitted or woven structure.

8. Absorption element (20) according to claim 6 or 7, characterized in that at least on one side of the absorption element (20), a spacing structure (26, 27) made of synthetic fibres is present between the absorption element (20) and the liquid-permeable covering layer (28) .

9. Absorption element according to claim 8, characterized in that the spacing structure (26, 27) is a knitted nylon fabric .

10. Application composition, such as trainer pants or a pad, which comprises at least one liquid-impermeable synthetic material (10) and an absorption element (5; 20), characterized in that the absorption element is an absorption element according to one or more of claims 6 to 9 inclusive.

11. Application composition according to claim 10, characterized in that the absorption element (20) , on the side which will come into contact with the body of the user, comprises a liquid-permeable covering layer (28) made of synthetic fibres, which covering layer (28) projects beyond the absorption element (20) and is joined to the liquid-impermeable material (31) of the application composition.

12. Application composition according to claim 11, characterized in that on both sides of the absorption element (20) a spacing structure (26, 27) of synthetic fibres is present.