Abstract:
A method is provided for continuous mass production of winged absorbent articles, including T-shaped absorbent articles, by attachment of wing portions to the chassis of the absorbent article which comprises a topsheet, a backsheet and a core sandwiched between the topsheet and the backsheet. The method comprises feeding at least one web of wing-making material, which may be at least partly elasticated, simultaneously attaching landing zones in spaced apart relationship on a surface of the web, attaching tape tabs on the edge of the web, folding the web longitudinally in a generally Z-fold configuration, feeding the chassis of the absorbent article in the general direction of the web, severing individual folded wing portions from said web and attaching the winged portions to the chassis at predetermined spaced intervals.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 09/797,334, filed Mar. 1, 2001 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a method of making absorbent articles with wings (flaps) and is particularly related to a method of attaching wings to the chassis of an absorbent article. In one specific aspect, the present invention relates to a method of attaching wings to the chassis of an absorbent article by a continuous method which is suitable for commercial production. In another specific aspect, the present invention relates to such method for formation of T-shaped absorbent articles. 
     BACKGROUND OF THE INVENTION 
     Absorbent articles such as diapers, incontinent undergarments, sanitary napkins and the like are widely used in various homes, hospitals and health care institutions. Typically, an absorbent article such as, e.g., a diaper, comprises a chassis defined basically by a liquid permeable topsheet, a liquid impervious backsheet and an absorbent sheet or layer sandwiched between the topsheet and the backsheet. Sometimes, the chassis may also include an acquisition layer disposed between the topsheet and absorbent sheet and one or more other layers for one purpose or another. The chassis itself has a front waist section and a backwaist section, the waist section being somewhat flared so that the flared portion may be wrapped around the torso of the wearer, and fastening means or adhesive strips are used to secure the flared portions (wings) together. 
     In order to improve securement of the diaper around the waist of the wearer, so-called T-shaped diapers have been proposed and described in several prior art patents. One T-shaped absorbent article has been described in U.S. Pat. No. 4,995,873 issued to Jackilyn M. Knight on Feb. 26, 1991. The absorbent article described by Knight has a crosspiece and an intersecting piece, which together form a generally T-shaped configuration when the article is laid out flat. Releasable fastening means such as press-on/rip-off adhesive or Velcro® strips are used to attach the crosspiece and intersecting piece together. 
     Commonly assigned, copending application Ser. No. 09/797,334, filed Mar. 1, 2001, describes a T-shaped absorbent article, e.g., a diaper with emphasis on the type of fastening system used in order to enhance securement of diaper to the body. The prior art patents discussed in said copending application describe other T-shaped absorbent garments. One patent mentioned therein, U.S. Pat. No. 5,906,604 issued on May 25, 1999 to Ronnberg et al., describes an attachment means for a belt used with an absorbent garment. The belt is either integrated with the absorbent garment, or it can be separately attached thereto by means of a releasable attachment system such as hook and loop type fastening means, e.g., Velcro®. 
     Regardless of whether the absorbent article is T-shaped or the more traditional type, it is generally recognized that their commercial production involves the use of complicated machinery and equipment. The paramount consideration in the design and operation of such machinery and equipment is the efficiency of production and quality of the absorbent garments which are produced. The efficiency of production depends, in turn, on the effectiveness of the method of assembly of the component parts of the absorbent garment. These are serious considerations in the economic and competitive fabrication of absorbent garments, particularly the recently used T-shaped absorbent garments. 
     Therefore, it is an object of the present invention to provide an efficient and commercially viable method of manufacturing absorbent articles. 
     It is also an object of the present invention to provide a method of manufacturing absorbent articles having wings or flaps attached to the chassis of the article. 
     It is a further object of the present invention to provide a continuous method of attaching wings to the chassis of an absorbent article such as a T-shaped brief. 
     It is yet another object of the present invention to provide a continuous method of forming a T-shaped diaper complete with all basic components of the diaper, including a fastening system, ready for shipment from the manufacturing plant. 
     The foregoing and other features and objects of the present invention will become more apparent from the ensuing description and the accompanying drawings. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, winged absorbent articles are produced by a method which is continuous, efficient and capable of mass production. The method basically comprises attaching wings to the chassis of an absorbent article, said chassis comprising a topsheet, a backsheet and an absorbent layer (core) sandwiched between the topsheet and the backsheet. The method comprises feeding at least one web of wing-making material, in a general machine direction, attaching a plurality of landing zones in spaced apart relationship on a surface of the web, said landing zone being perforated, or non-perforated if desired, followed by attaching tape tabs on the edge of said web. As the web advances in the machine direction, it is longitudinally Z-folded and a temporary bond is formed on the Z-folded portion. Simultaneously with folding said web, the chassis of the absorbent article is fed in the machine direction, and individual folded wing portions are severed and attached to the chassis of the absorbent article at predetermined spaced intervals. The method also contemplates feeding the web and the chassis in cross directions, however, means is provided for causing the web and/or the chassis to travel in the same direction at the point of attachment of the wings to the chassis. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, wherein like reference numerals are employed to designate like parts wherever possible: 
         FIG. 1  is a schematic flow diagram illustrating the method of this invention; 
         FIG. 2  is partly schematic, partly block diagram showing the formation of the chassis of the absorbent article and the subsequent steps of preparing the absorbent article for shipment and storage; 
         FIG. 3  is a partial cutaway of a T-shaped absorbent article, viewed when laid out flat, with each wing folded upon itself toward the vertical axis of the garment; 
         FIG. 4  is a sectional view taken along the line  4 - 4  in  FIG. 3 ; 
         FIG. 5  is a sectional view similar to  FIG. 4  illustrating a different way of folding the wings, and 
         FIG. 6  is another sectional view similar to  FIG. 4  illustrating still another way of folding the wings. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , two webs of wing material  11  and  13  are unwound from the respective feed rollers  15  and  17  with the webs moving in a generally parallel, spaced apart relation in the direction of the arrows A and B, in the machine direction, at the same predetermined speed. As the webs  11  and  13  advance in the machine direction, webs  19  and  21  of landing zone material are unwound from the respective feed rollers  23  and  25 , moving in the same direction as the webs  11  and  13 , a predetermined speed. As the webs  19  and  21  advance, individual strips of landing zones  27  and  29  are cut by a cutting means such as rotating blade (not shown) and each strip of landing zone  27  and  29 , which may be precoated with pressure sensitive adhesive, is attached on the surface of each web  11  and  13  at stations  20 , 22 . If the landing zone is not precoated with adhesive, the adhesive should be coated on the bottom surface of the landing zone prior to cutting the landing zone to individual pieces. The individual landing zone strips are attached to the wing surface of each web  11  and  13  in spaced apart relationship, as the webs move in the machine direction, and are usually precut to the desired dimensions. The landing zones  27  and  29  may be perforated in which case the webs  19  and  21  must be perforated before winding them on their respective feed rollers  23 , 25 . Obviously, if no landing zone is needed or desired, this step, i.e., attachment of landing zone strips to the surface of the webs  11  and  13  is omitted, in which case the feed rollers  23  and  25  are not used. The method of this invention also contemplates perforating the landing zone in line, in which case a perforation station is employed in the process line. Thus each of the webs  19  and  21  must be perforated individually or the landing zone may be perforated after attaching the landing zones on the wings. The exact manner and details of perforation of the landing zone are generally well known to those skilled in the art. Also, the webs  11 ,  13  may be at least partly elasticated in the cross machine direction, if desired. 
     Continuing with the method of this invention by reference to  FIG. 1 , after the landing zone strips  27  and  29  have been attached on the surface of the webs  11  and  13 , a wing tape is attached to the outer edge of either or both webs  11  and  13 . As shown in  FIG. 1 , tape dispensing stations (rollers)  31  and  33  on each side of the webs  11  and  13  dispense the tapes as shown at  35  and  37 , which are secured to the edge of the respective webs. The timing of attachment of the tapes to each web is synchronized with the speed of movement of the webs and the attachment of the landing zone strips to the webs. After attachment of the wing tapes each of the moving webs  11  and  13  is longitudinally folded by a folding means (not shown in drawing) at the folding stations  32 , 34 , to form a generally Z-fold, followed by temporarily (releasably) bonding the Z-folded wing layers to itself at the stations  36 , 38 , in order to form a folded web which is narrower than the width of the webs  11 , 13  prior to folding. Temporary bonding of the folded wing is achieved by the application of a releasable adhesive which serves to prevent the wing from unfolding as it passes through the diaper-making machine. Longitudinal folding of each web facilitates stacking, packaging and storage of the final product (diaper) prior to shipment for use. 
     As is further shown in  FIG. 1 , the method of this invention also comprises simultaneous feeding of the top sheet  39  from the topsheet feed roller  41  in the machine direction. Simultaneously, a backsheet layer  43  and an absorbent layer  45  are fed from the respective backsheet feed roller  47  and the absorbent layer feed roller  49  to combine with the topsheet thereby forming the chassis of the diaper with the absorbent layer or pad sandwiched between the topsheet and the backsheet. A pulp fluffing station  50  feeds pulp to the absorbent layer station  49  for mixing with the absorbent layer  45 . At about the point of combining the topsheet, the backsheet and the absorbent layer at station  52 , the individual Z-folded wings  51  are cut and permanently bonded to the topsheet  39  at stations  53 , 55 . Permanent bonding of the individual wings  51  to the topsheet  39  is effected by a suitable permanent adhesive intended to keep the wing attached to the chassis of the absorbent article during its use. As the chassis further advances in the machine direction with the wings attached thereto, the wings are again folded over the top surface of the coversheet as in  55 , 57  and a temporary bond such as, e.g., a releasable adhesive, is applied thereto to form a second temporary (releasable) bond, thus bonding the perforated wing on the coversheet. 
     The order of bonding is not per se critical. Thus, the wing can be first permanently bonded to the chassis (e.g., to the topsheet), then folded onto the top surface of the diaper (topsheet) to be bonded temporarily, instead of attaching each wing to the coversheet as described in connection with  FIGS. 1 and 2  and folding as previously described, the prefolded wing can be attached to the backsheet and folded under the bottom surface of the backsheet and temporarily bonded as previously described. 
     Referring to  FIG. 2 , after the formation of the diaper chassis by combining the topsheet  39  from feed roller  41 , the backsheet  43  from backsheet feed roller  47  and the absorbent layer  45  from feed roll between said layers, shown in block at  52 , the diaper chassis is cut at  61 , the cut chassis is finally folded at  63 , stacked at stacking station  65 , packaged at  67  and stored at storage station  69 . 
     A stretched view of a diaper, partly broken away, with folded wings, is shown in FIG.  3 . As shown in this figure, each of the wings  301 , 303  is folded upon itself toward the center of the chassis  300 . The facing surfaces of each wing  301 , 303  may be attached to each other by a removable (releasable) adhesive, by ultrasonic means, or some other suitable attachment means, as indicated by the dotted circles C 1 , C 2 , C 3  and C 4 . Each of the folded wings  301  and  303  is folded over the top surface of the coversheet as shown by the dotted circles C 5 , C 6 , C 7  and C 8 . In order to use the diaper, each of the wings  301 , 303  has a finger lift portion  301 A, 303 A which may be gripped between the thumb and the forefinger and lifted to an open position. 
     Referring to  FIG. 4 , the wings  41 ,  43  are shown folded over the topsheet  45  in accordance with one folding embodiment. Also shown in this figure is backsheet  47  and tape tab  49  attached to an edge of the topsheet. 
       FIGS. 5 and 6  illustrate further folding techniques. In  FIG. 5 , the wings  151 , 153  are folded with tape tab  159  attached to the wing  151 . In this case the fold layer having the tape tab is the uppermost layer as compared to the layer with tape is the lowermost layer. The wings  151 , 153  are disposed above the topsheet  155  and backsheet  157 .  FIG. 6  illustrates a fold wherein the wing  161  is disposed under the fold  163  with the tape tab  169  attached to the wing  161 . In this case each wing is folded over the top surface of the coversheet  165  disposed above the backsheet  167 . 
     The materials and fabrics used in making the diapers of the present invention are generally of the type and variety known in the art and are described, for example, in U.S. Pat. Nos. 4,695,278 and 4,795,454 and in copending, commonly assigned application Ser. No. 09/149,265, filed Sep. 8, 1998, the disclosures of which are fully incorporated herein by reference. Thus, the liquid previous cover sheet is a compliant soft material which is skin friendly and does not cause rash or irritation. Such materials include porous foams, reticulated foams, plastics, natural fibers such as woods or cotton fibers, synthetic fibers made of polyester, polypropylene or from a combination of such materials. The topsheet may also be preferably made of spunbond nonwoven polypropylene, i.e., available from First Quality Nonwoven, Inc., Hazelton, Pa., and is usually coextensive with the backing film. In general, however, the various layers are of the type and materials well known in the diaper industry and are within the scope and knowledge of those versed in this art. 
     The absorbent pad or core may be manufactured from a wide variety of liquid absorbent materials of the type usually used in manufacturing disposable diapers and other absorbent articles. Such materials include comminuted wood pulp, creped cellulose wadding, absorbent foams and sponges, super absorbent polymers, or a combination of said materials. 
     The backsheet or film backing is usually a polyethylene layer which is liquid, air and preferably vapor impermeable, and is placed under the absorbent core to prevent the body exudates from leaking and otherwise soiling the user&#39;s bed and clothing. The width and length of the backing film (or composite film nonwoven laminate) are generally wider and longer than the width and length of the absorbent core. Polyethylenes suitable as backing film for the purpose of this invention are available from Cloplay Plastics, Cincinnati, Ohio. 
     An acquisition layer may also be used in some instances. If so, the acquisition layer is usually made of chemically bonded nonwoven polyester available from American Nonwovens, Columbus, Mo. Preferably, the width of this layer is substantially the same as the width of the crotch absorbent core. This core may be made of wood pulp fibers and super absorbent polymers (SAP) such as IM 7000 series available from Clarian Products, Inc., Portsmouth, Va., and Chemdal 2000 series available from Chemdal, Inc., Palantine, Ill. Alternatively, the absorbent core may be made of dual layer construction, in which case, the absorbent polymer may be securely position between each layer of the absorbent material. 
     Other layers may be used in making the chassis depending on the ultimate use of the absorbent garment. It must be noted, however, that the present invention is directed to the method of manufacturing the absorbent article regardless of the type and kind of the different layers used in forming such articles. 
     Also, while the fastening system in the method of this invention has been described with reference to landing zone strips and tape tabs, the landing zone may be a loop material and a complimentary male element may be used as the tape, as described in the aforementioned copending application Ser. No. 09/797,334 filed Mar. 1, 2001. The use of such fastening systems are within the purview of the method described herein.