Absorbent articles for disposable diaper

Abstract

An absorbent article includes an air-laid fibrous web having a medial portion of a greater basis weight than flanking end and side portions. The fibers forming one surface of the web are adhesively bonded together to provide an abrasion resistant, non-pilling, facing layer, and also to aid in maintaining the structural integrity of the web. The fibers forming the other surface of the web are either adhesively bonded together, or a separate backing sheet, preferably in the form of a water-proof plastic sheet, is adhered directly to the other surface of the web to form a stabilized backing layer. The above constructions are adapted for use as disposable diapers. Apparatus of this invention includes a vacuum box having an open end underlying a discrete section of a foraminous forming surface so that regions of the forming surface extend beyond the open end of the vacuum box. Vacuum connection means permit the establishment of a different pressure drop across the discrete section of the foraminous forming surface overlying the open end of the vacuum box than through regions of the foraminous forming surface extending beyond the vacuum box. Drive means move the foraminous forming surface and vacuum box in registration with each other through a web forming area for maintaining the same discrete section of the foraminous forming surface in overlying relationship with the open end of the vacuum box as the foraminous forming surface and the vacuum box are moved through the web forming area. The method of this invention employs the above-described apparatus in which the foraminous forming surface extends beyond, and completely circumscribes the open end of the vacuum box. A greater pressure drop is established through the discrete section of the foraminous forming surface overlying the vacuum box than through the regions extending beyond the vacuum box to form a fibrous web having a medial portion with a greater basis weight of fibers therein than in flanking end and side portions of the web. .Iadd.

Having described my invention, I claim: 
     
       1. An absorbent article suitable for use as a disposable diaper and the like; said absorbent article comprising a unitary assemblage of randomly arranged fibers in the form of a web, said web having a transverse dimension defined between spaced, elongate side edges and an elongate dimension defined between spaced end edges; a medial portion of said web having a greater basis weight and greater average thickness than flanking end and side portions thereof for establishing a step configuration in a upper surface of said web in both the elongate and transverse direction; adhesive means on said upper surface of said web for bonding together exposed surface fibers in said upper surface to provide an abrasion resistant, non-piling, facing layer, and to aid in maintaining the structural integrity of said web and stabilizing means for stabilizing a lower surface of said web; said upper surface being adapted to be positioned in contact with a wearer with the medial portion of the web in the perineal region, the flanking side portions about the thigh regions, and the flanking end portions about the front and back regions. 
     
     
       2. The absorbent article according to claim 1, wherein said flanking end and side portions have substantially the same basis weight and thickness. 
     
     
       3. The absorbent article according to claim 2, wherein said stabilizing means is adhesive on said lower surface for bonding together exposed surface fibers in said lower surface. 
     
     
       4. The absorbent article according to claim 2, wherein said stabilizing means includes a moisture-impervious sheet secured to said lower surface. 
     
     
       5. The absorbent article according to claim 2, wherein said randomly arranged fibers include a major proportion by weight of short cellulosic fibers of a papermaking length of less than 1/4 inch, and a minor proportion by weight of reinforcing fibers having an average length over 1/4 inch interspersed and randomly intermingled with said short cellulosic fibers to enhance the strength of said web. 
     
     
       6. The absorbent article according to claim 2, wherein said medial portion includes sections of different basis weights, the greatest basis weight being a section where it is most needed to absorb body fluids. 
     
     
       7. The absorbent article according to claim 2, wherein said adhesive means only partially penetrates through the thickness of said web in the medial portion thereof to leave interior fibers of said medial portion unbonded by adhesive. 
     
     
       8. The absorbent article according to claim 7, including compressed regions in the upper surface of the medial portion of the web to enhance wicking of fluids along said medial region. 
     
     
       9. The absorbent article according to claim 8, further including compressed regions in said flanking side and end portions disposed in a predetermined pattern and separated by substantially uncompressed high loft regions. 
     
     
       10. The absorbent article according to claim 9, wherein said adhesive means defines bonded networks completely through the web in only the compressed regions of the flanking end and flanking side portions thereof. 
     
     
       11. The absorbent article according to claim 2, wherein said medial portion joins said flanking side portions along side boundaries and joins said end portions along end boundaries, at least a portion of said side boundaries being recessed to define a narrow center crotch section adapted to be positioned in the perineal region of a wearer, said medial portion further including a forward section and rearward section disposed, respectively, on opposite sides of the crotch section, said forward and rearward sections having a greater transverse dimension than said crotch section. 
     
     
       12. The absorbent article according to claim 11, wherein said medial portion includes sections of different basis weights, the greatest basis weight being in a section where it is most needed to absorb body fluids. .Iadd. 13. A multi-layer disposable diaper comprising (1) a highly porous batt comprised at least primarily of short cellulosic fibers and   (2) a water-impervious backing sheet adjacent one surface of said batt and bonded thereto in spaced areas of adhesion, the fibers of said batt being bonded together by a resinous binder covering the surface opposite said backing sheet to provide a smooth permable skin as a body contacting surface of said batt, said resinous binder extending throughout the thickness of said batt in spaced linear areas. .Iaddend..Iadd. 14. The diaper of claim 13, wherein said backing sheet is adhered to said batt by a separate adhesive in the marginal areas of the region of contact between said backing sheet and said batt. .Iaddend..Iadd. 15. The diaper of claim 13, wherein said binder contains a surfactant. .Iaddend..Iadd. 16. The diaper of claim 13, wherein said binder is a thermoset material. .Iaddend..Iadd. 17. The diaper of claim 13, wherein said highly porous batt is comprised entirely of short fibers. .Iaddend..Iadd. 18. The diaper of claim 13, wherein said highly porous batt is comprised of short fibers and long fibers. .Iaddend..Iadd. 19. The diaper of claim 18, wherein said short and long fibers are uniformly blended. .Iaddend. .Iadd. 20. A method of making a diaper comprising the steps of applying a liquid resinous binder to a surface of highly porous batt of short cellulosic fibers, compressing said batt in spaced linear areas to cause said liquid resinous binder to move through the thickness of said batt in said area, solidifying said binder to provide a smooth liquid permable skin as a body contacting surface of said batt and to form spaced binder walls extending throughout the thickness of the batt and adhering the surface of said batt opposite said first named surface to a water-impervious backing sheet. .Iaddend..Iadd. 21. The method of claim 20, wherein said liquid resinous binder is an aqueous latex of a thermosetting material. .Iaddend..Iadd. 22. The method of claim 20, wherein said liquid resinous binder contains a surfactant. .Iaddend.