DETAILED DESCRIPTION OF THE INVENTION

[0019] The invention will be described with reference to an adult incontinence brief, in which the advantages of the invention are most conspicuous. However, it will be apparent from the description which follows, that advantages of the invention can be realized in other absorbent articles, including infant diapers.

[0020] The disposable absorbent article 10 has a construction which permits the article to be adjusted to ensure a proper and comfortable fit. To this end, the article 10 has a reinforced backing sheet 12 which permits removal and reattachment of tape fasteners 14 so that, after the article is initially positioned on the wearer, it can be readily adjusted for a proper and comfortable fit.

[0021] Typically, material and manufacturing costs are relatively high for a disposable absorbent article having an extra-strength, or reinforced, backing sheet. A significant aspect of this invention is that the absorbent article 10 is inexpensive to produce even though it utilizes a reinforced backing sheet. Material costs are minimized by a unique construction and manufacturing costs are minimized by a novel and cost-effective method of manufacture. The construction and manufacturing technique can be utilized for both infant diapers and adult briefs, but are particularly advantageous in the manufacture of adult briefs because of the requirements for larger sizes of sheet material and a greater number of relatively strong fastening tapes.

[0022] In FIG. 2, the outer face of the backing sheet 12 is seen in full, and the moisture absorbent pad 16 is shown in broken lines on the opposite, inner face of the backing sheet. The pad is secured to the inner face of the backing sheet, and covered by a moisture-permeable, body-contacting cover sheet (not shown) which may be coextensive with the backing sheet, or alternatively large enough to cover the absorbent pad but smaller than the backing sheet so that the backing sheet has a margin extending beyond the edges of the moisture-permeable cover sheet. As best illustrated in FIG. 1, the backing sheet 12 has an abdominal portion 12a and a rear portion 12b, and as best illustrated in FIG. 2, the rear portion of the backing sheet has opposite side edges 12c and 12d.

[0023] Plural fastening tapes 14 extend laterally from the rear portion 12b of the backing sheet, beyond the edges 12c and 12d so that, when the brief 10 is positioned on the wearer, the fastening tapes 14 extend forward and can be attached to the abdominal portion 12a of the backing sheet. Preferably, an adult brief 10, as illustrated, will include a pair of fastening tapes 14 extending from each backing sheet side edge, 12c and 12d. A pressure-sensitive adhesive on the inward facing sides 14a of the fastening tapes 14 permits the tapes to be secured to the backing sheet to attach the brief 10 to the wearer, and permits subsequent removal and reattachment.

[0024] The backing sheet 12 has two reinforced landing zones 18 to which the fastening tapes 14 may be attached. Each landing zone 18 is provided by a separate strip of material 20 permanently secured, by a layer 22 of adhesive, to the abdominal portion 12a of the outer face of the backing sheet. The layer of adhesive is also illustrated in FIG. 3, and its area of coverage is illustrated by dotted lines in FIG. 2. Reinforcement strip 20 must be secured to the backing sheet 12 in such a way as to avoid ripping of the strip 20 or the backing sheet 12, and also to avoid separation of the strip 20 from the backing sheet 12, when the fastening tapes 14 are pulled away from the landing zone 18 for adjustment. For example, if the adhesive layer 22 is not continuous, air pockets between the reinforcement strip 20 and backing sheet 12 will allow the reinforcement strip 20 to tear and/or separate from the backing sheet 12. Therefore, an important aspect of the invention is that the adhesive layers 22 are uninterrupted widthwise and lengthwise over the areas which they cover. Thus, if the layer of adhesive is rectangular, which is the preferred configuration for manufacturing efficiency, the adhesive layer covers the entire area within the borders of the rectangle. More generally, for a rectangular adhesive layer, or any other suitable shape, the adhesive layer is uninterrupted lengthwise and widthwise if substantially any straight path lying in the plane of the layer of adhesive and intersecting an edge of the adhesive layer, passes through adhesive substantially continuously and without interruption by a gap in the adhesive layer until it finally exits from the adhesive layer through an edge on the other side of the adhesive layer. Thus, the border of any adhesive layer will generally be either straight or convex at all locations. However, minor concavities are not objectionable.

[0025] Preferably, the continuous and uninterrupted layer of adhesive 22 is applied to the reinforcement strips 20 by a slot-coating process. In this process, the adhesive layer 22 extends the full length “L” of the reinforcement strip 20, but slightly less than the full width “W” of the reinforcement strip 20 as best illustrated in FIG. 2 by dotted lines. Thus, a pair of side edge margins, 20a and 20b, of the reinforcement strip 20 freely extend from the backing sheet 12 along opposite edges of the adhesive layer 22. The margins, 20a and 20b, do not form a part of the landing zone area 18 and are located so that the tape fasteners 14 are never secured to them. The application of adhesive to the strip material by slot coating results in several advantages. First, slot coating produces a continuous adhesive layer without gaps or air pockets which would allow ripping or separation to take place upon removal of the attachment tapes. Second, slot coating permits application of the adhesive in such a way as to provide the narrow margins 20a and 20b in the reinforcement strips along opposite edges of the adhesive area. These narrow margins avoid exposed adhesive that could cause parts of the article 10 to adhere to one another or cause adjacent articles 10 to adhere to each other in manufacture, or in the process of packaging the articles. Third, slot coating improves the efficiency of adhesive usage by avoiding application of adhesive to coating machine parts and to areas where it is not needed, and by producing a uniform adhesive coating having an optimum thickness.

[0026] Another important aspect of the invention is that the use of a continuous and uninterrupted layer of adhesive 22 permits the use of relatively thin and inexpensive sheet materials for the backing sheet 12 and reinforcement strips 20. For example, the sheet material for either the backing sheet or the reinforcement strips can be polyethylene, polypropylene, a co-polymer blend, co-extruded film, polyester or polyurethane. The backing sheet and reinforcement strips can be made of the same sheet material or of different sheet materials. Preferably, the backing sheet 12 has a uniform thickness of about 0.3 to 0.9 mils, and each reinforcement strip 20 has a uniform thickness of about 0.2 to 0.9 mils.

[0027] By way of example, one contemplated embodiment of article 10 utilizes a backing sheet 12 made of polyethylene having a thickness of 0.8 mils and reinforcement strips 20 made of polypropylene having a thickness of 0.5 mils. In this embodiment, the combined thickness of the polyethylene and polypropylene components of each landing zone area 18 is 1.3 mils, and the thickness of the remaining portions of the backing sheet is 0.8 mils. Thus, the material usage in the construction of the backing sheet is optimized by reinforcing only the area to which the tape fasteners 14 are likely to be attached in normal use. In addition, the use of a continuous and uninterrupted layer of adhesive 22 permits further reduction in the thickness of the reinforcement strip material. The embodiment is thereby produced inexpensively, but permits repeated removal and reattachment of the attachment tapes.

[0028] In the manufacture of the disposable absorbent article 10, a continuous, elongate, advancing strip of landing zone reinforcement material is transfer coated with a pressure sensitive adhesive. Preferably, a slot-coating process is utilized, in which an adhesive is extruded through an elongate narrow slot onto a PTFE chill roll or a PTFE- or silicone-coated chill roll, and than transferred to the advancing reinforcement material. To this end, the slot extends transversely relative to the advancing elongate strip of material so that the reinforcement material is transfer coated with a continuous elongated layer of adhesive 22. The width of the slot is slightly less than the width of the reinforcement material so that the opposite side edge margins 20a and 20b of the reinforcement material are not covered by the adhesive layer. Slot-coating ensures that the layer of adhesive 22 is continuous and uninterrupted, and provides for cost-effective and efficient coating of the reinforcement material and avoidance of exposed adhesive.

[0029] Preferably, the adhesive is a low-temperature processing, pressure sensitive, construction adhesive. An example of such an adhesive is an adhesive sold under the trademark COOL-LOK by National Starch & Chemical of Bridgewater, N.J.

[0030] In the slot-coating process, when the temperature sensitive adhesive is transferred from the elongate narrow slot to the chill roll, the temperature of the adhesive is in the range of about 150° to 350° F. (66° to 177° C.), preferably at approximately 200° F. (93° C.). The temperature of the adhesive is at a lower level when it is transferred from the chill roll onto the elongated strip of landing zone material.

[0031] After the elongate strip of landing zone reinforcement material is coated with adhesive, the material is transferred onto a vacuum roll and then cut on a rotary die to produce multiple, individual landing zone reinforcement strips 20. The individual landing zone reinforcement strips 20 are applied directly onto the outer faces of backing sheets 12

[0032] The above-described disposable absorbent article and method of manufacture of the article provide a brief having a reinforced backing sheet which permits repeated removal and reattachment of fastening tapes. Material costs and manufacturing costs are minimized by utilizing thin and inexpensive sheet materials and a applying a continuous and uninterrupted layer of pressure sensitive adhesive onto the reinforcement strips by slot-coating.

[0033] While a preferred disposable absorbent article and method of its manufacture have been described, various modifications can be made to the brief construction and to the method of manufacture. For example, the number of tapes for attachment to each landing zone can be varied from one in the case of an infant diaper, to two or more in the case of an adult brief. Although the illustrated embodiment has a pair of landing zones 18 in order to minimize the amount of material needed for strips 20, one elongate landing zone, extending across the abdominal portion 12a of the backing sheet 12, could be utilized instead. The thicknesses of the backing sheet and reinforcing strips are desirably kept at a minimum, but can be varied. Moreover, the thicknesses of the backing sheet and reinforcing strips can be identical or different from each other. The reinforcing strips, although preferably rectangular for convenience of manufacture, can be provided in other shapes, such as circular or oval, provided that the adhesive layer has no gaps permitting ripping of the reinforcement strips or detachment of the reinforcement strips from the backing layer. Other modifications, alterations, and changes may be made without departing from the spirit and scope of the invention as defined in the appended claims.