Patent GB-1438412-A (GB)
Title: Disposable diaper with double contoured panel
IPC: A61F13/49
Filed: 1974-07-08
Abstract: 1438412 Diapers JOHNSON & JOHNSON 8 July 1974 [9 July 1973] 30149/74 Heading A5R A multi-layer diaper comprises: an absorbent rectangular batt 14 centrally disposed on and in juxta position with a larger rectangular water-impervious backing sheet 12 and comprising a unitary, highly porous, loosely compacted, cellulosic fibrous layer continuous throughout its thickness and having a smaller quantity of fibres in at least two opposite marginal portions 14c of its area than in the centre, the batt having a smooth and gradual thickness contour between the marginal portions and the centre; and a rectangular porous facing layer 16 over said batt, said batt having a greater water-wettability than said facing layer. Batt 14 is double contoured i.e. contoured in the transverse and longitudinal directions to produce a smooth peak or major surface 14a. The other major surface 14b is planar and may include a paper-like densified layer 18. Batt 14 is of short i.e. shorter than  inch wood pulp fibres, cotton lintels or mixtures thereof, the adhesion being by interfibre bonds. Facing layer 16 is a mixture of 75%- 98% short cellulosic fibres e.g. wood pulp fibres or cotton linters with the remainder being textile length i.e. longer than  inch fibres e.g. rayon. Adhesion is by a specified bonding agent and the layer is treated with a specified wetting agent. Alternatively layer 16 may be an apertured non-woven fabric of natural and/or synthetic fibres e.g. polyester or a non-apertured material e.g. a non-woven isotropic web or sponge. A layer of tissue may be interposed between layer 16 and batt 14. Batt 14 and layer 16 are attached to the smooth or embossed polyethylene or polyethylene terephthalate sheet 12 throughout the interface therebetween by adhesive 22 in parallel lines of beads, other patterns or a continuous layer of heat sealing may be used. In the apparatus of Fig. 5 (not shown) a compacted wood pulp roll (41a) is as wide as the batt 14 to be produced and is commingled with a narrower roll (41b) to provide the batt's transverse contour. The pulp is ground (at 42) and blown as a stream through a duct (42a) onto a belt (43). The transverse contour may alternatively be produced by a baffled duct (42b, Fig. 7A, not shown) or by grinding fibres at one station and depositing them downstream to form a web of the width of batt 14 and grinding fibres at a second station and depositing them in a lesser width band on the aforesaid web, thus the batt may be of uniform density throughout its thickness. The longitudinal contour is achieved by varying the speed at which fibres are deposited on the belt (43) or by varying the speed of the belt (43) or by grinding fibres at one station to form a continuous web with a transverse contour and grinding further fibre at a further station to be deposited on the web to form the repetitive longitudinal contours. The apex thickness is 1.5 to 4.0 times the corner thickness. The pulp need not be completely ground into short fibres but 2%- 10% may be left in small clumps e.g; inch across to provide islands of increased liquidholding tenacity. Rolls (46, 47) compact the layer to form a web and the underside planar surface is water sprayed and compressed by rolls (49) to form the densified layer 18. A web (55) of facing layer 16 is applied from a roll (57) and supports the layer while a cutter (56) severs it into batts 14. Layer 16 and sheet 12 are brought into contact with opposite faces of the batts 14 and rolls (60, 61) compress the assembly and a cutter (62) cuts the strip into individual diapers which are subsequently folded and bonded.