ABSORBENT STRUCTURE

Abstract: An absorbent structure in an absorbent article such as a diaper, incontinence guard, sanitary napkin, wound dressing, bed protection and the like, formed from at least two superposed layers (5'; 5'') of one or more web-shaped absorption materials (5), said layers (5'; 5'') having different widths as seen in the transverse direction of the article. The absorbent structure (4) comprised of said layers has been compressed to a thickness which is substantially the same over the width of the structure, in such a way that the structure has a higher density in the areas thereof where the layers overlap each other and a lower density in other areas.

Description: ABSORBENT STRUCTURE Technical field The present invention refers to an absorbent structure m an absorbent article such as a diaper, incontinence guard, sanitary napkm, -wound dressing, bed protection and the like, formed from at least two superposed layers of one or more web-shaped absorption mateπals The refers to a method for manufactuπng the absorbent structure Background of the invention Many different types of absorbent structures m absorbent articles of the above mentioned kind are previously known They usually consist of one or more compressed layer of cellulosic fluff pulp, often in combination with so called superabsorbents, which are polymers with the capacity to absorb water or body liquids many times their own weight Other types of absorbent structures are airlaid cellulosic fibrous webs which have been bound with a bonding agent , e g latex, heat meltable bonding fibers or the like, dry formed reel pulp according to WO 90/0508, absorbent foam mateπals etc The body liquid is discharged to the absorbent article in a very limited area, the so called \\ etting point It shall from there be distπbuted further to unutilized portions of the absorbent structure. Above all it is desired to have a distπbution of liquid in the longitudinal direction of the article, while spreading towards the longitudinal edges can give edge leakage, which should be avoided. In order to enhance the liquid distribution in the longitudinal direction it is known to have special distribution layers in the absorbent article and/or to compress this m patterns in the form of longitudinal compression lines, along which the liquid can be easily distributed. Through EP 0 481 322 there is known an absorbent structure made from a web-shaped absorption material which in its initial position has an even density and thickness in the xy-direction and which has been compressed to a higher density and by that a lower thickness in certain areas. The mateπal is then folded together to form at least two layers which have different densities. In this way an absorbent structure having different densities m the z-direction can be produced. Object and most important features of the invention The object of the present invention is to provide an absorbent structure in an absorbent article of the above mentioned kind, in which it m a simple way is possible to create areas of different densities m the xy-direction of the structure. This has according to the invention been provided by the fact that the structure compπses at least two superposed layers of one or more web-shaped absorption mateπals, said layers having different widths as seen m the cross direction of the article and that the absorbent structure compnsed of said layers has been compressed to a thickness which is substantially the same over the width of the structure, m such a way that the structure has a higher density in the areas thereof where the layers overlap each other and a lower density m other areas The layers can either be formed from one and the same web-shaped absorption materials which have been folded to the desired configuration or alternatively be formed from separate pieces of the web-shaped mateπal, which either can be the same in the different layers or different. The invention further refers to a method for manufactuπng an absorbent article, at which at least two layers of one or more web-shaped absorption materials are placed superposed to each other, said layers having different widths as seen in the transverse direction of the article and that the absorbent structure comprised of said layers is compressed to a thickness which is substantially the same over the width of the structure, in such a way that the structure will have a higher density in the areas thereof where the layers overlap each other and a lower density in other areas. Further features of the invention are disclosed in the following description and from the claims. Description of the drawings The invention will m the following be closer descπbed with reference to some embodiments shown in the accompanying drawings Fig 1 shows in a view from above an absorbent article m the form of a sanitary napkm Fig 2 is a section according to the line II-II m Fig 1 Fig. 3 shows schematically an irregularly folded absorption mateπal forming the start point for an absorbent structure according to the invention Fig 4 shows schematically stπps of a web-shaped absorption mateπal of different widths placed superposed to each other and forming the start point for an absorbent structure according to the invention Fig 5 shows schematically an absorbent structure with different densities in different areas obtained by compressing the mateπal shown in Fig. 3 or Fig 4 Description of embodiments Fig. 1 and 2 shows an embodiment of a sanitary napkm 1 compπsmg a liquid pervious topsheet 2, a liquid impervious backsheet 3 and an absorbent body 4 arranged therebetween Further layers be included, such as liquid acquisition layers, distπbution layers etc It should be pointed out that the sanitary napkm shown m the drawings only constitutes a non- limiting example of an absorbent article Thus the shape and construction of the article may vary. The absorbent article can also consist of a diaper, a pant diaper, an incontinence guard, a wound dressing, a bed protection and the like. The liquid pervious topsheet 2 may consist of a nonwoven material, for example a spunbond material of synthetic filament, a meltblown material, a thermobonded material or a bonded carded fibrous web. Alternatively it may consist of a perforated plastic film or a perforated laminate of nonwoven or plastic film. The liquid pervious backsheet 3 may consist of a plastic film, a nonwoven material which is coated with a liquid impervious material or a hydrophobic nonwoven material which resists liquid penetration. On the underside of the liquid impervious backsheet 3 fastening means in the form of longitudinal strings 6 of adhesive glue are provided. The glue areas are preferably before use covered with a releasable protective strip (not shown) of paper or plastic film treated with a release agent. In the shown embodiment the fastening means consist of longitudinal glue areas. A plurality of other glue patterns, e g crosswise, are of course possible as well as other types of fastening means such as Velcro-type, press buttons, girdles, special underpants and the like. The sanitary napkm in the shown embodiments is hourglass shaped with broader end portions 7 and a narrow crotch portion 8. The crotch portion 8 is the portion of the sanitary napkin which during use is intended to be placed in the crotch area of the user and serve as a receiving surface for the discharged body fluid. The topsheet 2 and the backsheet 3 have a somewhat larger extension in the plane of the absorbent body 4 and extend outside the edges thereof. The layers 2 and 3 are interconnected within the projecting portions, e g by gluing or welding with ultrasonic or heat. The absorbent body 4 can be of an optional web-shaped absorption material 5, such as airlaid cellulosic fibers which have been bonded with a bonding agent, e g latex, heat meltable bonding fibers or the like, dry-formed reel pulp according to WO 90/0508, sheets of absorbent foam material etc. A certain amount of superabsorbent material may possibly be incorporated in the absorption material. The absorption material 5 according to the embodiment shown in Fig. 3 is irregularly folded in zigzag-shape along five folding lines, in such a way that six layers 5 ' are formed which have different widths. The outer of these lavers 5 ' have the smallest width while the innermost layers have the largest width. The configuration of the πregular folding can of course be vaπed in many different ways, of which the shown only is one example. The irregularly folded web-shaped absorption mateπal forms the start point for the production of the absorbent structure according to the invention In the embodiment shown m Fig 4 three separate stπps 5 of a web-shaped absorption mateπal have been placed m superposed relationship These stπps have three different widths and can be of the same or of different web-shaped absorption matenals Besides they have different lengths Upon compressing any of the mateπals composed of several layers according to Fig 3 or 4 to an even thickness the portions that consist of the most layers will have a density which is higher than that of the portions that consist of fewer layers In the shown embodiments the middle portion 9 will have the highest density and the immediately outside said middle portion located side portions 10 will have a higher density, while the outermost edge portions 11 will have the lowest density Since liquid is more rapidly distπbuted in smaller capillaπes, which means a more rapid distπbution with an increased density, the liquid will at first hand be distπbuted along the hardest compressed middle portion 9, while the outside this located portions 10 and 11 will serve as a kind of safety zones, which mainly are utilized when the middle portion is saturated with liquid. With such a construction of the absorbent article edge leakage from the longitudinal edges of the article can be minimized. If the layers also have different lengths as is shown in Fig. 4, the risk for edge leakage from the transverse edges of the article is also minimized. The different material layers can be compressed together in a pattern for forming longitudinal compression lines, at which the liquid distribution in the longitudinal direction is further improved.

Claims: Claims 1 An absorbent structure in an absorbent article such as a diaper, incontinence guard, sanitary napkm, wound dressing, bed protection and the like, formed from at least two superposed layers (5 ',5 ' ') of one or more web-shaped absorption mateπals (5), characterized in that said layers (5 '.5") of the web-shaped absorption mateπal(-s) (5) have different widths as seen m the cross direction of the article and that the absorbent structure (4) compπsed of said layers has been compressed to a thickness which is substantially the same over the width of the structure, in such a way that the structure has a higher density m the areas thereof where the layers overlap each other and a lower density m other areas 2 Absorbent structure according to claim 1, characterized in that said layers (5 ') are formed from one and the same web-shaped absorption mateπals (5) which has been folded to the desired configuration 3. Absorbent structure according to claim 2, characterized in that the web-shaped absorption mateπal is folded in zigzag-shape m such a way that the structure in a middle portion (9) comprises more layers than in the longitudinal edge portions (11), at which the structure has a higher density in the middle portion than in the edge portions. 4. Absorbent structure according to claim 1, characterized in that said layers (5") are formed form separated stπps of the web-shaped absoφtion material(-s). 5. Absorbent structure according to claim 4, characterized in that said separate strips have different widths and are placed in supeφosed relationship in such a way that the structure in a middle portion (9) comprises more layers than in the longitudinal edge portions (11), at which the structure has a higher density in the middle portion than in the edge portions. 6. Absorbent structure according to claims 4 or 5, characterized in that different types of absoφtion materials are used in the different layers ( 5 "). 7. Absorbent structure according to any of the preceding claims, characterized in that said layers ( 5';5") of the web-shaped absoφtion material(-s) (5) also have different lengths as seen in the longitudinal direction of the article. 8. Absorbent article such as a diaper, incontinence guard, sanitary napkin, wound dressing, bed protection and the like of the kind comprising a liquid pervious topsheet (1), a liquid impervious backsheet (2) and an absorbent structure (4) arranged therebetween, characterized in that the absorbent structure (4) is of a kind stated in any of claims 1-7. 9. Method for making an absorbent structure in an absorbent article such as a diaper, incontinence guard, sanitary napkin, wound dressing, bed protection and the like, at which at least two layers (5';5") of one or more web-shaped absoφtion materials are placed supeφosed to each other, characterized in that said layers (5';5") of the web-shaped absoφtion material(-s) have different widths as seen in the transverse direction of the article and that the absorbent structure (4) comprised of said layers is compressed to a thickness which is substantially the same over the width of the structure, in such a way that the structure will have a higher density in the areas thereof where the layers overlap each other and a lower density in other areas. 10. Method as claimed in claim 9, characterized in that the web-shaped absoφtion material (5) is folded to the desired configuration for forming said layers (5 '), after which compression to a substantially even thickness takes place. 11. Method as claimed in claim 10, characterized in that the web-shaped absoφtion material is folded in zigzag-shape in such a way that the structure in a middle portion (9) will comprise more layers than in the longitudinal edge portions (11), and that then the structure is compressed to an essentially even thickness at which it will have a higher density in the middle portion than in the edge portions. 12. Method as claimed in claim 9, characterized in that at least two separate pieces of the web-shaped absoφtion material(-s) of different widths are placed supeφosed to each other for forming said layers (5"), after which compression to an essentially even thickness takes place. 13. Method as claimed in claim 12, c aracterized in that said separate strips are placed on each other in such a way that the structure in a middle portion (9) comprises more layers than in the longitudinal edge portions (11), at which the structure is given a higher density in the middle portion than in the edge portions after compression ta an essentially even thickness. 14. Method as claimed in claim 12 or 13, characterized in that different types of absoφtion materials are used in the different layers (5")-

Inventors: WALLSTROEM LEIF, WALLSTROEM, LEIF
Applicants: SCA HYGIENE PROD AB, WALLSTROEM LEIF, SCA HYGIENE PRODUCTS AB, WALLSTROEM, LEIF
Application year: 1999
Main classification: A61F13
IPC codes: A61F13