Abstract:
Apparatus and methods are provided to allow for short length adhesive application in the machine direction. These short length adhesive applications can be used in creation of pocket style rear waistband feces containment features onto running webs for use in diaper manufacturing. Different configurations of adhesive and patch applications can be employed to create the pockets.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 61/563,322, filed 23 Nov. 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    During production of disposable products such as diapers, adhesives are often used to couple different woven, non-woven, or elastic components together. Based on desired product configuration, adhesives are often desired to be applied to a web running in the machine direction. Often, it is desired to have this adhesive be applied to a very short distance in the machine direction to create a narrow adhesive patch in the machine direction, and relative wider in the cross machine direction. 
         [0003]    This invention relates to the application of adhesives to moving webs. Adhesives can be used to couple discrete elements of disposable products onto a running continuous web of material. 
         [0004]    For instance, some disposable products are formed of a continuous running web of material, such as a non-woven material, to which discrete components are applied. Often the discrete components are coupled to the running web of material by adhesive materials. It is preferable that the adhesive applied to the material be applied to the continuous running web in a pattern matching a footprint of the discrete component. Such patterns can be of any shape, such as typical geometric shapes, but are typically square or rectangular. 
         [0005]    In automated machinery, there are processes that can limit top machine production speed. The application of hot melt adhesive on a running web is one such process. For example, conventional, commercially available hot melt adhesive application systems have a minimum valve open time of 4 ms to 5 ms. When applying an adhesive to a running web, the valve typically cannot open and close in times less than this 4 ms to 5 ms range. As web speed increases the minimum length of applied adhesive stripe increases. For example, if an adhesive pattern is applied by an applicator with a valve open time of 5 ms on a web that is traveling at 500 FPM, the same applicator would require a valve open time of 2.5 ms to apply the same length adhesive stripe on a web traveling 1000 FPM. 
         [0006]    If only a very small portion (or length, in the machine direction) of adhesive is desired on a running web, present adhesive applicators limit the speed of the running web, because faster speed of the running web results in a longer, and perhaps too long, application of adhesive in the machine direction. 
         [0007]    Generally, diapers comprise an absorbent insert or patch and a chassis, which, when the diaper is worn, supports the insert proximate a wearer&#39;s body. Additionally, diapers may include other various patches, such as tape tab patches, reusable fasteners and the like. The raw materials used in forming a representative insert are typically cellulose pulp, tissue paper, poly, nonwoven web, acquisition, and elastic, although application specific materials are sometimes utilized. Usually, most of the insert raw materials are provided in roll form, and unwound and applied in assembly line fashion. 
         [0008]    In the creation of a diaper, multiple roll-fed web processes are typically utilized. To create an absorbent insert, the cellulose pulp is unwound from the provided raw material roll and pulverized by a pulp mill. Discrete pulp cores are formed by a core forming assembly and placed on a continuous tissue web. Optionally, super-absorbent powder may be added to the pulp core. The tissue web is wrapped around the pulp core. The wrapped core is debulked by proceeding through a calender unit, which at least partially compresses the core, thereby increasing its density and structural integrity. After debulking, the tissue-wrapped core is passed through a segregation or knife unit, where individual wrapped cores are cut. The cut cores are conveyed, at the proper pitch, or spacing, to a boundary compression unit. 
         [0009]    While the insert cores are being formed, other insert components are being prepared to be presented to the boundary compression unit. For instance, the poly sheet is prepared to receive a cut core. Like the cellulose pulp, poly sheet material is usually provided in roll form. The poly sheet is fed through a splicer and accumulator, coated with an adhesive in a predetermined pattern, and then presented to the boundary compression unit. In addition to the poly sheet, which may form the bottom of the insert, a two-ply top sheet may also be formed in parallel to the core formation. Representative plies are an acquisition web material and a nonwoven web material, both of which are fed from material rolls, through a splicer and accumulator. The plies are coated with adhesive, adhered together, cut to size, and presented to the boundary compression unit. Therefore, at the boundary compression unit, three components are provided for assembly: the poly bottom sheet, the core, and the two-ply top sheet. 
         [0010]    A representative boundary compression unit includes a die roller and a platen roller. When all three insert components are provided to the boundary compression unit, the nip of the rollers properly compresses the boundary of the insert. Thus, provided at the output of the boundary compression unit is a string of interconnected diaper inserts. The diaper inserts are then separated by an insert knife assembly and properly oriented. At this point, the completed insert is ready for placement on a diaper chassis. 
         [0011]    A representative diaper chassis comprises nonwoven web material and support structure. The diaper support structure is generally elastic and may include leg elastic, waistband elastic and belly band elastic. The support structure is usually sandwiched between layers of the nonwoven web material, which is fed from material rolls, through splicers and accumulators. The chassis may also be provided with several patches, besides the absorbent insert. Representative patches include adhesive tape tabs and resealable closures. 
         [0012]    The process utilizes two main carrier webs; a nonwoven web which forms an inner liner web, and an outer web that forms an outwardly facing layer in the finished diaper. In a representative chassis process, the nonwoven web is slit at a slitter station by rotary knives along three lines, thereby forming four webs. One of the lines is on approximately the centerline of the web and the other two lines are parallel to and spaced a short distance from the centerline. The effect of such slicing is twofold; first, to separate the nonwoven web into two inner diaper liners. One liner will become the inside of the front of the diaper, and the second liner will become the inside of the back of that garment. Second, two separate, relatively narrow strips are formed that may be subsequently used to cover and entrap portions of the leg-hole elastics. The strips can be separated physically by an angularly disposed spreader roll and aligned laterally with their downstream target positions on the inner edges of the formed liners. 
         [0013]    After the nonwoven web is sliced, an adhesive is applied to the liners in a predetermined pattern in preparation to receive leg-hole elastic. The leg-hole elastic is applied to the liners and then covered with the narrow strips previously separated from the nonwoven web. Adhesive is applied to the outer web, which is then combined with the assembled inner webs having elastic thereon, thereby forming the diaper chassis. Next, after the elastic members have been sandwiched between the inner and outer webs, an adhesive is applied to the chassis. The chassis is now ready to receive an insert. 
         [0014]    To assemble the final diaper product, the insert must be combined with the chassis. The placement of the insert onto the chassis occurs on a placement drum or at a patch applicator. The inserts are provided to the chassis on the placement drum at a desired pitch or spacing. The generally flat chassis/insert combination is then folded so that the inner webs face each other, and the combination is trimmed. A sealer bonds the webs at appropriate locations prior to individual diapers being cut from the folded and sealed webs. 
         [0015]    Disposable diapers are susceptible to leakage of feces of a diaper wearer that escapes the diaper upwards in the lower back region of the wearer. To solve this problem, a fully adhered, cross-machine direction stretch waist band can be applied to the body side of the diaper&#39;s top sheet, or with a pocket feature, which requires a zone of non-adhesive in the center—forming a pocket. 
         [0016]    The existing product is made using a process of creating a machine direction stretch laminate, extended and applied to a puck, and then cut, turned and placed onto the product at matched speed, such as taught in U.S. Pat. No. 6,319,347, which is incorporated by reference. A cross-machine direction stretch laminate (commercially available from manufacturers such as Aplix, Koester, Tredegar and the like) can be used, which may consist of a tri-laminate, with an elastomeric film in the center and nonwoven facings on both sides. 
         [0017]    It is difficult however to provide the necessary intermittent adhesive application, provided in a short length in the machine direction and the cross-machine direction to a high speed (1200 FPM +) carrier web. 
         [0018]    One application of short length adhesive in the machine direction is used in applying waistband material. One side of the waist material is touched with a vacuum anvil roll (as well as infeed conveyor hardware), and that same piece of waist material—once cut—on the opposite side, is also touched in order to provide the cross-machine direction stretch. The cut and stretched piece is then applied to the running topsheet web. This process works well when a patch is desired to be placed on the interior side of that nonwoven topsheet web, but it is more difficult to apply the waist piece to the exterior, body side of the nonwoven topsheet. 
         [0019]    One application of short length adhesive in the machine direction is used in order to provide a feces capturing structure. Adhesive required between a feces capturing structure and a topsheet assembly (including cuff in some cases) needs to be applied to the topsheet. Because the topsheet travels at a high rate of speed, and the intermittent portion of the adhesive pattern is very short (approx. 12 mm), it is difficult to perform this application with an intermittent adhesive applicator, because a 12 mm adhesive pattern in the machine direction, which carries webs at speeds such as 1250 feet/minute, web results in an intermittent on time of 2 milliseconds, difficult to achieve. 
         [0020]    It is desirable to provide disposable products with short adhesive patches carried by an intermediate carrier layer. In a preferred embodiment, the techniques are used to create a rear body, downward facing pocket in a waistband area of a diaper. 
       SUMMARY OF THE INVENTION 
       [0021]    In order to overcome processes that can limit top machine production speed, a novel application of hot melt adhesive on a running web is disclosed in order to provide a small portion (or length, in the machine direction) of adhesive on a running web. 
         [0022]    In one embodiment of the present invention, an intermediate web is provided, which could serve as one of the layers of a tri-laminate, which receives an intermittent adhesive application, and is processed through a traditional cut slip applicator (which only requires handling of the web from one side). The intermittent timing required when the web length (per product) is much more favorable to an intermittent adhesive applicator. 
         [0023]    Such an applicator can provide reliable performance down to a minimum on or off time of 4-6 milliseconds. 12 mm on a 40 mm web running at 1000 PPM requires a minimum timing of 18 milliseconds (well within operating range). Once that layer is applied to the top running web, a continuous adhesive pattern is applied to that chassis web/receiving patch combination at full length. The receiving layer is nonwoven, and is glued down using the desired pattern—and the CD stretch laminate is glued fully to the intermediate patch, and a feces capturing structure is provided. 
         [0024]    In an alternative embodiment, a “full size” rectangular adhesive pattern is applied to the running web. A smaller, intermediate patch is applied to this adhesive pattern to cover a portion of the adhesive pattern, and a cross-machine direction elastic component is provided, again to result in a feces capturing structure. 
         [0025]    In a second alternative embodiment, adhesive patterns are provided on outboard edges of the topsheet, and then a stretched waistband patch is applied onto the adhesive pattern. After that step, a non-extensible, non-woven patch can be applied, with the use of a traditional slip/cut unit. This patch could be glued continuously, and this patch anchors the waistband patch already adhered to the top sheet along one edge, and effectively provides a loose pocket to create the feces capturing structure. 
         [0026]    The present method enables faster machine process speeds beyond performance capability of adhesive system(s) themselves. Additionally, adhesives can be masked so as to not be apparent from the outside of articles employed on. Further, complex adhesive pattern or patterns, such as stars, circles, etc. can be used in conjunction with a similar shape of mask put on top of the applied adhesives. Masks can be formed by laser cutting, die cutting, slitting, or other cutting forms known in the art. 
         [0027]    These methods can also be employed to attain short glue patterns on otherwise fast moving webs. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is top perspective view of a prior art disposable product with a rear waistband feature for rear feces containment; 
           [0029]      FIG. 2  is a perspective view of a main web carrying a rear waistband feces containment structure; 
           [0030]      FIG. 3A  is a top view of a first running web containing two machine direction adhesive applications, and a plurality of cross-machine direction adhesive applications; 
           [0031]      FIG. 3B  is a top view of the first running web showing lines of separation to create individual rear waistband feces containment features; 
           [0032]      FIG. 3C  is a side schematic view of a slip/cut applicator used to cut lines of separation to create individual rear waistband feces containment features, and apply the features to a main web; 
           [0033]      FIG. 3D  is a top view of a main web carrying a rear waistband feces containment feature; 
           [0034]      FIG. 3E  is a top view of a main web carrying a rear waistband feces containment feature covered by an elasticized waistband feature; 
           [0035]      FIG. 4A  is a top view of an alternate method of forming a rear waistband feces containment feature, with an adhesive patch laid onto a main web; 
           [0036]      FIG. 4B  shows a patch material used to partially conceal a portion of the adhesive patch; 
           [0037]      FIG. 4C  shows a pocket forming material, laid atop the first patch material; 
           [0038]      FIG. 4D  shows the pocket forming material deployed atop the first patch material and the unconcealed portion of the adhesive patch to form a pocket style rear waistband feces containment feature; 
           [0039]      FIG. 5A  is a top view of a second alternate method of forming a rear waistband feces containment feature, with a first running web containing two machine direction adhesive applications; 
           [0040]      FIG. 5B  is a top view of the first running web showing lines of separation to create first portions of individual rear waistband feces containment features; 
           [0041]      FIG. 5C  shows first portions of individual rear waistband feces containment features deposited onto the main web; 
           [0042]      FIG. 5D  shows deployment of a second, adhesive backed patch portion, which is deployed atop the first portions of individual rear waistband feces containment features; 
           [0043]      FIG. 5E  shows the second, adhesive backed patch portion deployed atop the first portion of individual rear waistband feces containment features to create a completed pocket style rear waistband feces containment feature. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0044]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
         [0045]    It is noted that the present techniques and apparatus are described herein with respect to products such as diapers, but as previously mentioned, can be applied to a wide variety of processes in which discrete components are applied sequentially. 
         [0046]    Referring now to  FIG. 1  a top perspective view of a prior art disposable product  10  is shown, with a rear waistband feature  12  for rear feces containment. An inner nonwoven layer  20  is visible, with cuffs  14  provided in the side region of the diaper  10 . An absorbent core is carried between the inner nonwoven layer and an outer layer (not shown). A combination ear/fastening mechanism  18  is provided to fasten the diaper  10  around the waist of a wearer. 
         [0047]    The product of  FIG. 1  can be made as either a fully adhered, cross-machine direction stretch waist band applied to the body side of the diaper&#39;s top sheet, or with a “bowel movement dam” feature, which requires a zone of non-adhesive in the center—forming a pocket. The product of  FIG. 1  is made using a process of creating a machine direction stretch laminate, extended and applied to a puck, and then cut, turned and placed onto the product at matched speed, as described in U.S. Pat. No. 6,319,347 incorporated by reference. 
         [0048]    Referring now to  FIG. 2 , a perspective view of a main web  20  carrying a rear waistband feces containment structure  11  is shown. This main web  20  is preferably the inner non-woven layer  20  of  FIG. 1 , and additional components of the diaper such as those shown in  FIG. 1  (and others) can be combined with the main web  20  and rear waistband feces containment structure  11  in sequential fashion (not shown) as desired. 
         [0049]    The present invention, shown generally in  FIGS. 3A-5E  relates in part to methods of forming the pocket-like rear waistband feces containment structure  11 , and diapers  10  embodying the rear waistband feces containment structure  11 . The methods can Along with solving the problem of providing this product feature for use on disposable diapers to create a bowel movement dam feature, the methods described below can be used in other applications to attain short glue patterns on otherwise fast moving webs. 
         [0050]    In order to solve the problem of applying an intermittent adhesive application in a short machine direction length to a high speed (1200 FPM +) carrier web, three alternatives are described. 
         [0051]    The first embodiment, shown in  FIGS. 3   a - 3 E generally provide an intermediate web (which could serve as one of the layers of a tri-laminate) which receives an intermittent adhesive application, and is processed through a traditional cut slip applicator which only requires that handling the web from one side, which is preferably a side not containing adhesive. The intermittent timing required when the web length (per product) is much slower, such as prior to a slip cut or accelerating unit, is more favorable to an intermittent adhesive applicator. Such an applicator can provide reliable performance down to a minimum on or off time of 4-6 milliseconds. 12 mm on a 40 mm web running at 1000 PPM requires a minimum timing of 18 milliseconds (well within operating range). Once that cross-machine direction adhesive layer is applied to the top running web, a continuous adhesive pattern is applied to that chassis web/receiving patch combination at full length. Because the receiving layer is nonwoven, and is glued down using the desired pattern—and the cross machine direction stretch laminate is glued fully to the intermediate patch, a short machine direction length of adhesive is provided. 
         [0052]    Referring now to  FIG. 3A , a top view of a first running web  12  containing two machine direction adhesive applications  22   a  is shown. A plurality of cross-machine direction adhesive applications  22   b  are also provided on the running web  12 , which eventually forms the pocket-like rear waistband feces containment structure  11 . 
         [0053]    Referring now to  FIG. 3B , first running web  12  is cut along lines of separation  24  to create individual rear waistband feces containment features by means such as a slip/cut applicator consisting of a vacuum anvil  26  and knife  28  combination as shown in  FIG. 3C . The individual rear waistband feces containment features  11  are applied in such a fashion to an incoming inner non-woven web  20 , resulting in the configuration shown in  FIG. 3D . A pocket is formed by the downstream edges of the rear waistband feces containment features  11 , which, because no adhesive is applied in that area, forms the pocket for containment of escaping matter from the rear of the diaper  10 . 
         [0054]    Referring now to  FIG. 3E , the rear waistband feces containment feature  11  can be covered by an elasticized waistband feature  200 , if desired, by slip cutting this material  200  onto the rear waistband feces containment feature  11  as previously described with relation to the slip cut unit shown in  FIG. 3C . 
         [0055]    The second embodiment, described with reference to  FIGS. 4A-4D  is generally to apply a “full size” rectangular adhesive pattern to the running web. Placing a smaller, intermediate patch on this adhesive pattern and then applying the CD elastic waistpiece would be another approach to achieving a similar product performance result. Again, the adhesive applicator requirements here are not a challenge. 
         [0056]    Referring now to  FIGS. 4A-4D , a top view of an alternate method of forming a rear waistband feces containment feature  11  is shown. In this embodiment, an adhesive patch  22   c  is laid directly onto the main web  20 , prior to receiving a piece of patch material  30 , preferably slip/cut onto the main web  20 . The patch material  30  covers a portion of the adhesive patch  22   c , leaving an exposed portion of the adhesive patch  22   c ′ as shown in  FIG. 4B . The patch material serves as the bottom layer of the pocket structure. In this embodiment, the inner non-woven can receive intermittently applied adhesive at an easily controlled interval. 
         [0057]    Referring now to  FIG. 4C , a pocket forming material  32  is laid atop the first patch material  30 , and is coupled to the main web  20  at the exposed portion of the adhesive patch  22   c ′ after being slip/cut and deposited again by a traditional slip/cut unit. In a preferred embodiment, the pocket forming material  32  is a cross-machine direction stretch waistband. This configuration results in a pocket between the pocket forming material  32  and the first patch material  30 , as shown in  FIG. 4D  to form the a pocket style rear waistband feces containment feature  11 . 
         [0058]    The third embodiment described generally with reference to  FIGS. 5A-5E  is to provide adhesive patterns on the outboard edges of the topsheet, then applying the stretched waistband patch into the adhesive pattern. After that step, a non-extensible, NW patch could be applied (again, with the use of a traditional slip/cut unit). This patch could be glued continuously—with no fear of touching both sides of that web. Said patch would anchor the waistband patch already adhered to the top sheet—along one edge, and effectively providing that loose pocket for the BM dam function. 
         [0059]    Referring now to  FIG. 5A-5E , top views of a second alternate method of forming a rear waistband feces containment feature  11  is shown. In this embodiment a first running web  12  containing two machine direction adhesive applications  22  is slip/cut along lines  24  and deposited onto the main web  20  as shown in  FIGS. 5B and 5C . In a preferred embodiment, the first running web  12  is a cross-machine direction stretch waistband. 
         [0060]    Next, as shown in  FIG. 5D , a second, adhesive backed patch portion  34  (preferably a non-woven material) or cross machine direction back pocket patch  34  is slip/cut onto the main web  20  and onto the rear of the previously deposited portions of the web  12 . A small portion of the cross machine direction back pocket patch  34  extends rearward of the deposited portions of the web  12  thereby blocking the back end of the pocket formed underneath the deposited portions of the web  12  to provide a completed pocket style rear waistband feces containment feature  11 . 
         [0061]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.