Method for Manufacturing a Product Having Elastic Means Disposed in the Transverse Direction

The present invention relates to methods and apparatus for inserting an elastic member in the transverse direction of a product, and more specifically to methods and apparatus for placing elastic members in the waist-encircling portion of a disposable diaper.

Over the years, there have been a number of products which have an elastic member disposed in the transverse direction of the product, such as plastic pants, training pants, and the like. The elastic members may be sewn or adhered to the product in various manners as are well known in the art. Recently, there have come on the market a number of disposable diapers, which have elastic members inserted in the longitudinal direction of the product to make the leg-encircling portion of the diaper elastic. There are also a number of U.S. Patents which describe such products and methods for their manufacture such as U.S. Pat. Nos. 3,860,003; 4,050,462, and 4,081,301.

There are a number of U.S. Patents which describe elastic means disposed in the waist-encircling portion of a diaper or other techniques for providing stretch in the waist of the diaper or similar product; for example, see U.S. Pat. Nos. 3,920,018; 3,951,150; 3,990,450; 3,995,638; 4,036,233 and 4,041,949. To the best of my knowledge, none of the products having elastic waistband areas as described in these patents has enjoyed any commercial success. It is believed a primary reason for this lack of success is that no efficient, economical method has been discovered for inserting the elastic member in a suitable position in a diaper so as to render the waist-encircling portion of the diaper stretchable.

What I have discovered is a simple, economical, efficient, fast method for inserting elastic members transverse of a continuous web.

What I have discovered is a method of applying an elastic member transverse of a continuously moving web to gather selected transverse portions of the web. In my method, the web is foreshortened in its transverse direction and while so foreshortened a preferably unstretched elastic member is adhered to the web to span the foreshortened area.

In a particular embodiment, the center of the web is disposed out of the plane of the side portions of the web and while so disposed, an elastic member is adhered to the side portions spanning the center portion. The foreshortened or the transversely reduced web is returned to its original transverse dimension and in so doing the unadhered center portion of the elastic member is stretched and may then be adhered to the straightened web. The web with elastic members thereon may then be severed as desired to produce one or more individual articles.

In a specific embodiment of the present invention, a continuous laminate of diaper stock which comprises an impervious film backing member, spaced apart absorbent pads disposed on said backing, and a continuous pervious facing member is produced. The facing and backing members are adhered to each other along their longitudinal side portions and are also adhered to each other in the transverse portion between adjacent absorbent pads. Such a laminated material is well known in the art and is usually cut or separated between adjacent absorbent pads and then folded in various manners to produce disposable diapers. In a specific method of the present invention, the laminate, prior to being cut into individual diaper portions, is passed over a bowing member or shoe which displaces the center portion of the laminate out of the plane of the continuously moving laminate while allowing the side portions to remain in that plane. In the preferred embodiment, the center portion is disposed in a direction away from the film backing side of the laminate and while so disposed, an elastic member is adhered to the film backing. Each end of the elastic member is adhered to a side portion of the film backing so that the center of the elastic member spans the center portion of the laminate which is disposed out of the plane of the web. The elastic member may have a pressure-sensitive adhesive applied to one surface and that surface is easily adhered to the side portions by the application of pressure. Once adhered, the laminate is passed over a bowed roll to straighten or pull the laminate in the transverse direction and return the laminate to its original transverse dimension. Such bowed rolls are well known in the art. While being pulled in the transverse direction, the center portion of the elastic member is stretched while the end portions remain unstretched but adhered to the film backing. Upon stretching to the full transverse direction of the continuous laminate, the center portion is pressed to the film backing and adhered thereto. Individual diaper blanks are then severed from the laminate.

The diaper blanks are folded and packaged as is well known in the art.

The invention will be more fully described in conjunction with the following drawings wherein:

FIG. 1 is a schematic view in cross-section of one form of apparatus for carrying out the method of the present invention;

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1;

FIG. 3 is a cross-sectional view taken along line 3--3 of FIG. 1;

FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 1;

FIG. 5 is a schematic view of another apparatus for carrying out the method of the present invention;

FIG. 6 is a cross-sectional view taken along line 6--6 of FIG. 5;

FIG. 7 is a perspective view of one end of a diaper product which is foreshortened in the transverse direction and has an elastic member spanning the foreshortened portion; and

FIG. 8 is a perspective view of the diaper of FIG. 7 which has been returned to its original transverse dimension.

Referring to the drawings, FIG. 1 shows one form of apparatus for applying elastic members in accordance with the present invention. As shown in the drawing, elastic material 10 is supplied from a supply roll 11 and is fed to a rotating anvil-vacuum roll 12 by a pair of drive rolls 13 and 14. The movement of the elastic material is controlled by the drive rolls which advance the material a predetermined distance beyond the line where the cutter 15 meets the periphery of the anvil-vacuum roller. At this point, the cutter severs the appropriate length of the elastic material, and the elastic member 16 is held by the vacuum portion 17 of the anvil-vacuum roll and accelerated to the peripheral surface speed of that roll. The elastic member is carried by the vacuum portion to the application position A. In this embodiment, the elastic member has a pressure-sensitive adhesive mass on the surface disposed away from the anvil-vacuum roll for adhering the member to an appropriate web material. Diaper stock or other appropriate web or sheet material 18 is fed tangentially past the anvil-vacuum roll at a spot substantially adjacent the area where the vacuum is removed. The diaper stock is conveyed over a suitable chute 19 which causes the central portion 20 of the diaper stock to be displaced out of the plane of the diaper stock. This chute causes the longitudinal side portions 21 and 22 of the diaper stock to be urged towards each other. This is more clearly shown in FIG. 2 which is a cross-section of the chute 19 with the diaper stock 18 disposed about the chute in an appropriate configuration. At the application point A, the vacuum is removed from the elastic member and the pressure-sensitive adhesive attaches the elastic member to the diaper stock spanning the portion of the diaper stock disposed out of the original plane of the stock and around the chute. The diaper stock and elastic member are moved along to a pressure applying position. As is more clearly shown in FIG. 3, the diaper stock 18, in its position about the chute 19, passes over a back-up roller 23. The longitudinal side portions 21 and 22 of the stock are urged or pressed against the back-up roller by the pressing rollers 24 and 25. This pressure securely adheres each end 26 and 27 of the elastic member 16 in an unstretched state to the diaper stock. The diaper stock is continued to be conveyed and moved off the chute 19 and then over a bowed roll 26. The bowed roll expands or stretches the diaper stock back to its original flat position; in fact, to a concave position as shown in FIG. 4, and in so doing, stretches the elastic member in the center portion 29. This action also urges the elastic member against the diaper stock and adheres the center portion in a stretched condition to the diaper stock. The diaper stock or web may then be further processed as is well known in the art by separating intermittent lengths and folding and packing them as in the standard manufacture of diapers.

In FIG. 5, there is shown a modified form of apparatus for applying elastic members in accordance with the present invention. In this embodiment, the elastic member 30 in the form of a rubber material is intermittently fed through a pair of drive rollers 31 and 32 to the surface of an anvil-vacuum roll 33. A knife cutter roll 34 cuts an appropriate length of the elastic member which is then carried on the surface of the roll 33 by vacuum appropriate applied. Suitable hot melt or other adhesive is applied to the outer surface of the cut elastic member by nozzle 35 and the cut elastic member with the adhesive thereon is carried to the application zone 36. As described, in conjunction with FIGS. 2-4, the diaper stock 37 is conveyed in a path adjacent the surface of the anvil-vacuum roll and substantially at the point where the vacuum is removed from holding the elastic member. The diaper stock is conveyed over the chute 38 to dispose a center portion of the diaper stock out of the plane of the diaper while urging the longitudinal side margins of the diaper towards each other in the plane of the stock. The elastic member is urged against the diaper stock and the elastic member at its ends adhered to the diaper stock. As is more clearly seen in FIG. 6, the diaper stock with the elastic ribbon adhered thereto is passed between the back-up roll 39 and two pressure-applying rolls 40 and 41, one on each side of the chute, which press the ends 42 and 43 of the elastic member to the diaper stock and secures them thereto. The diaper stock is removed and conveyed away from the chute over a bowed roller 44 and the diaper stock stretched to a flattened, concave configuration which stretches the unadhered center portion of the elastic member and adheres the center portion to the diaper stock. The diaper stock may then be processed, that is, folded, cut, and packaged as individual diapers as is well known in the art.

FIG. 7 shows one specific diaper construction. Broadly, the diaper 45 comprises a water pervious facing sheet 46, suitable absorbent pad 47 of wood pulp or layers of tissue, and an impervious backing sheet 48, usually a polyolefin film. In this embodiment, the facing and backing sheet are co-extensive and the absorbent panel is smaller and fits within the perimeter of the facing and backing sheets. The central portion 49 of the diaper is disposed out of the plane of the diaper and that disposed portion has an elastic member 50 spanning the disposed portion. The elastic member in this embodiment is positioned against the impervious backing sheet or film. The elastic member is adhered to the backing sheet at the ends 51 and 52 of the elastic member with the center of the elastic member 53 unadhered at this time. As is shown in FIG. 8, upon returning the diaper to a uniform flat plane, the elastic member between its adhered ends is stretched and urged against the impervious backing member in the stretched portion to form a waist-encircling portion of a diaper that has stretchability or elasticity.

The elastic member may be made from rubber, either natural or synthetic, or other well known elastic, thermoplastic film materials. Elastic members may be adhered to the diaper either by pressure sensitive adhesive, standard adhesive latices, hot adhesives, and the like. The size of the elastic member, that is, the width and length, will depend on how much elasticity is desired in the transverse portion of the product and, of course, the size of the diaper product itself.

From the foregoing discussion, it will be appreciated that the present invention provides a new improvement, particularly adaptable for disposable diapers, to provide elastic waistband portions utilizing a simple and economical method and apparatus so that the fabrication and production of the diaper itself is more economical and produces a suitably functional diaper. Accordingly, others skilled in the art may make modifications to the disclosed embodiment without departing from the spirit and scope of the present invention as pointed out in the appended claims.