Abstract:
The present invention relates to a process for manufacturing a composite web for use in a disposable product, the process comprising the steps of: a) providing a continuous web of material; b) creating in the web a longitudinally repeating pattern of windows; and c) attaching at least one strip to the web, said strip at least partially covering the windows and having different functional characteristics than the web. The present invention also relates to a composite web formed in accordance with this process and to panels obtainable by cutting said web in cross direction.

Description:
Cross Reference to Related Applications 
     This application is a national stage filing under 65 U.S.C. 371 of PCT/EP2006/005488, filed Jun. 8, 2006, which claims priority to European Application No. 06009347.3, filed Jun. 9, 2005, and European Application No. 05012431.2, filed Jun. 9,2005, the disclosures of which are incorporated herein by reference in there entirety. 
     TECHNICAL FIELD 
     The present invention relates to a process for manufacturing a composite web for use in disposable products, particularly disposable diapers such as adult incontinence articles, a composite web for a disposable product, a process for manufacturing disposable diapers, and a disposable diaper. The disposable product may particularly be a diaper, and adult incontinence article, and the like. 
     BACKGROUND ART 
     WO 03/002053 relates to a sanitary absorbent article including a hook-and-loop-type fastener for releasably attaching a first and a second part of the article to each other. The first part is overlapping the second part when the parts are attached to each other. The fastener includes a hook member affixed to the first part of the article and a loop member affixed to the second part of the article, wherein each member comprises a base portion having a bottom surface affixed to the first or second part of the article and an opposite top surface containing hook elements and loop elements, respectively. The fastener has a first end region distal to the overlapping edge of the first part, in which the engagement force between the hooks and loops element of the members is reduced. This type of sanitary absorbent articles is also known as belt-type diapers or belted diapers. 
     Further belt-type diapers are disclosed in EP-A-1 142 547, US-A-2002/0151858, US-A-2001/0034511, U.S. Pat. Nos. 6,500,163, 6,432,099, 6,334,858, 6,241,716; 6,086,571, 5,906,604 and U.S. Pat. No. 5,904,673. 
     WO 2004/105668 A1 discloses a single-use hygiene article comprising a chassis with a front region and a rear region wherein at both sides of the rear region side flaps are directly or indirectly attached. Between the front region and the rear region is a crotch region  14 . 
     U.S. Pat. No. 4,381,781 discloses an elasticized waist diaper in which a layer of elastic material is positioned in an opening in the waist area of the diaper. The elastic layer is located such that it forms a portion of the waist edge of the diaper. The elastic layer may be formed from the same piece of elastic material as is used for the diaper leg elastic. 
     U.S. Pat. No. 6,692,476 B1 discloses a similar arrangement of a disposable diaper including a laminated panel that includes a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed therebetween. Side flaps of the panel are provided with leg-opening elastic members rectilinearly extending longitudinally thereof between the front and rear waist regions and secured under tension to the respective side flaps. The rear waist region of the panel is provided between the respective side edges of the core and the respective leg-opening elastic members with a pair of stretchable regions being elastically stretchable transversely of the panel. 
     Generally, the production of continuous webs with uniform machine direction and/or cross direction elastic features, or with continuous zoned elastification in cross direction are known in the art of hygiene products and used for the production of diapers. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved process for manufacturing a composite web for use in a disposable product as well as an improved composite web. A further object of the present invention is to provide an improved process for manufacturing disposable diapers as well as to provide an improved disposable diaper. These objects are achieved with the features of the claims. 
     According to the present invention, a process for manufacturing a composite web for use in a disposable product comprises the steps of providing a continuous web of material, preferably a non-woven, woven, fabric, scrim, film, or paper material, creating in the web a longitudinally repeating pattern of windows, and attaching one or more strips to the web. The strip(s) cover the windows at least partially and have different functional characteristics, particularly different elastic properties, than the web. The strip(s) may be provided as continuous tapes or as individual patches. If the strip(s) are provided as patches, it is preferred that each patch at least partially covers a single window. 
     The process may comprise the additional step of providing one or more fastening tabs and attaching the fastening tab(s) to sections of the composite web transversally of the strips, i.e. in the cross machine direction (CD direction). 
     The step of creating a longitudinally repeating pattern of windows may be particularly performed by perforating, scoring, slitting, abrading, melting and/or cutting. This may be accomplished, e.g., by a die cutting process, particularly rotary die cutting. In accordance with a particularly preferred embodiment, the web material within the windows is cut out and removed from the web material. 
     The repeating pattern of windows in the web may be longitudinally and/or transversally offset. In accordance with a preferred embodiment, the windows are both longitudinally and transversally offset. The windows may have a wide variety of shapes including, for example, rectangular, oval, circular. 
     The strips are typically provided from a continuous roll of material, preferably an elastic material. Preferably, the strips or patches are provided and fed to the web by one or more vacuum wheel applicators. Advantageously, the strips or patches are attached to the web by adhesive bonding, thermal bonding, or sonic bonding or combinations of common bonding methods along at least two of the edges of the window. The patches may be slightly larger than the windows so that they can be attached along at least two opposing edges of the windows and patches. The strips or patches may also fit into the windows so as to form a butt joint. The elastic material that is preferably used for the patches may be any type of elastic, but is preferably a multi-layer elastic material comprising an elastic core and at least one less elastic or non-elastic skin layer. Such elastic materials are disclosed, e.g., in EP 0 521 883 and EP 1 066 008. 
     Another aspect of the present invention relates to a composite web for a disposable product, comprising a web having a longitudinally repeating pattern of windows forming designated sections, wherein the windows are at least partially covered with strips, such as patches, having different functional characteristics, preferably different elastic properties, than the web. Typically, the web is a non-woven, woven, fabric, scrim, film or paper material. The composite web may be provided with one or more fastening tabs attached to sections of the composite web transversally of the strips. The windows in the web may be present in the form of perforations, scorings, slits and/or cut-outs. Preferably, at least parts of the web material within the windows is removed. The windows are advantageously created in the web to be both longitudinally and transversally offset. The strips may be attached to the web by adhesive bonding, thermal bonding, or sonic bonding or combinations of common bonding methods. 
     Where the strips or patches are made from an elastic material, e.g., a multilayer elastic material, the composite web is provided with elasticity in the areas of the windows. 
     According to a further aspect of the present invention, a process for manufacturing disposable diapers or adult incontinence articles is disclosed. This process relating to a diaper comprises the steps of providing a continuous web of a plurality of diaper chassis, providing a composite web having a longitudinally and optionally transversally repeating pattern of windows which are at least partially covered with strips (e.g., patches) having different characteristics than the web, providing individual front, rear and/or belt panels by cutting said composite web in cross-direction and thereafter intermittently attaching said panels to the web of diaper chassis. The present invention also relates to a diaper comprising a chassis with a front and a rear panel or belt manufactured according to the above-mentioned process. 
     A specific advantage of the various aspects of the present invention is that the process and composite web may be used with existing diaper manufacturing equipment. The process and composite web according to the present invention may be particularly advantageously used in the manufacturing of diapers or adult incontinence articles which are made from a diaper chassis and front and rear panels or belts which do not have elastic functionality. Typically, in the manufacturing of adult incontinence articles front and rear side panels or belts are supplied from a continuous roll of inelastic material (e.g. non-woven material) that is attached to the chassis so as to extend transversally from both longitudinal edges of the chassis. 
     Typically, these side panels are about 20 cm to 25 cm wide and 15-30 cm in height. The front panel may not require any elasticity because it is generally only wrapped towards the rear side of the wearer for reasons of comfort. On the contrary, with the composite web and process according to the present invention it is advantageously possible to provide the rear panel with elastic properties so as to allow some degree of stretching, e.g., between 3 and 10 cm per side, in order to increase the fastening and wearing comfort of the incontinence article. 
     Belt style diapers are typically wider, as they surround the entire body with the left and right belt elements and are attached either at the front on each other or to the front part of the diaper, possibly in specific designated landing zones. A typical length of each belt element is about 50 cm. Such belt systems are typically between 8 and 20 cm high. The process according to this invention will allow the production of elastic strips or patches into a basically non elastic and thus cheaper nonwoven web. It will also enable the elastification of left and right belt portions from one web, followed by separation and placement to the diaper. 
     By use of the composite web of the invention typical manufacturing equipment and processes can be used because the front and rear panels are made from a single roll of a composite web with different elastic properties along its length. Thus, with the composite material and process according to the invention, it is possible to provide improved elasticated disposable articles without substantial investment in additional manufacturing equipment. 
     The present invention may generally use an inelastic non-woven web material for the front and rear side panels which can be provided from a single roll of material as is done on existing manufacturing equipment. This web material may be provided with fastening tabs, wherein typically one or two fastening tabs with mechanical or adhesive fastening means are provided at the rear panel and none on the front panel. The areas of the composite web according to the present invention comprising the cut out windows with the superposed strips or patches are arranged to be in the section of the rear panel of the diaper. The windows may have a size of, for example, 4 cm in width and 25 cm in length. The elastic material from which the patches are preferably made provide an effective elastic zone of, e.g., between 3 and 10 cm per side so as to provide elasticity to the rear panels. 
     The composite web according to the present invention which may be seen as a repeating pattern of longitudinally repeating front and rear panels, may be fed into existing applicators of diaper manufacturing lines. The composite web may be dispensed in a registered way to the diaper chassis. The resulting diaper comprises a diaper chassis, inelastic front panels and elastic rear panels. This can be achieved with essentially the same manufacturing equipment as previously used to manufacture diapers with both non-elastic front and rear panels. 
     The scope of this invention is described as example, but not meant to be limited to elastic strips or patches in non elastic webs. In general, it is a process to provide differentiated transversal and/or longitudinal functionality of webs and strips. These could include without being complete different color, breathability, haptic properties, softness, transparency, decorative features. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following, preferred embodiments of the present invention will be described with reference to the drawings in which: 
         FIG. 1  is a schematic view of a web material that can be used for the manufacture of a composite web for belt style diapers according to the present invention; 
         FIG. 2  is a schematic view of a composite web for belt style diapers comprising patches on the windows of the web shown in  FIG. 1 ; 
         FIG. 3   a  is a schematic illustration of another embodiment of a composite web for belt style diapers according to the present invention in which cut lines for side panel members for disposable diapers are shown; 
         FIG. 3   b  is a schematic illustration of another embodiment of a composite web for belt style diapers according to the present invention in which other cut lines for side panel members for disposable diapers are shown; 
         FIG. 4  illustrates various shapes of windows that can be used in the composite web according to the present invention; 
         FIG. 5  shows the windows of  FIG. 4  covered with patches; and 
         FIG. 6  shows another embodiment of the composite web for side panel style diapers according to the present invention during its manufacturing process. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A composite web  2  according to the present invention comprises a web  4  of material, preferably a non-woven web material which has a repeating pattern of sections  6 ,  8  with windows  10  in the longitudinal direction  12 , i.e. machine direction (MD). Preferably, the windows  10  are both longitudinally and transversally offset so that in each section  6  a window  10  is provided closer to a first longitudinal edge  14  and in each adjacent section  8  the windows  10  are provided closer to the opposite longitudinal edge  16 . Accordingly, in the embodiment shown in  FIG. 1  the windows  10  are arranged in a longitudinally and transversally offset configuration. 
     Referring to  FIG. 2 , the web  4  is shown similarly as in  FIG. 1 , however, with strips in the form of individual patches  18  covering the windows  10 . The patches  18  which impart different functional characteristics to the composite web  2  in the areas of the windows  10  are preferably made from an elastic material. As can be seen upon a comparison of  FIGS. 1 and 2 , the patches  18  are generally slightly larger than the windows  10  so that the patches  18  can be attached to the web  4  generally around the edges of the windows  10 . The attachment can be accomplished, for example, by means of adhesive bonding, thermal bonding and/or sonic bonding. 
     The composite web  2  shown in  FIG. 2  can be used, for example, as belt or rear side panels of disposable diapers, particularly adult incontinence articles. To this end, the composite web is cut along schematically illustrated cut lines  20  separating sections  6  and  8  from one another. After cutting of the sections  6  and  8 , the section  6  may be used as a right belt or rear side panel of the diaper and section  8  may be used as a left belt or rear side panel of the diaper or vice versa. 
     Accordingly, with the composite web  2  according to the present invention left and right belt elements or side rear panels can be cut from a single roll of continuous web material without the need of supplying two separate materials for the respective belt elements or side panels. 
     Another embodiment of the composite web  2  according to the present invention is shown in  FIG. 3   a . According to this embodiment, the composite web  2  comprises a web material  4  and first and second sections  6 ,  8 . In accordance with this embodiment, the sections  6 ,  8  are provided in a form of a bottle neck instead of rectangles as shown in connection with the embodiment of  FIGS. 1 and 2 . The windows  10  in the web  4  according to the embodiment shown in  FIG. 3   a  are also covered with patches  18 . The windows  10  and patches  18  are also arranged in a longitudinally and transversally offset configuration. Furthermore, each of the sections  6 ,  8  is provided with a fastening tab  22 , preferably a mechanical fastener element like a hook tape. The cut lines  20  illustrated in  FIG. 3   a  are inclined with respect to the cross machine direction (CD), wherein longitudinally adjacent cut lines  20  are alternately inclined so as to define the trapezoidal shape of the sections  6 ,  8 . 
     Similarly as with the embodiment of  FIG. 2 , the composite web  2  according to the embodiment of  FIG. 3   a  can be cut along the cut lines  20  so as to form respective left and right belt elements or rear side panels that can be attached to diapers, like adult incontinence articles. 
     In the embodiment shown in  FIG. 3   b , the composite web  2  generally corresponds to the web of  FIG. 3   a . However, the cut lines are different in this embodiment. The sections  6 ,  8  of the composite web  2  are provided with cut lines  20  (dot-dash lines) in a center region of the web, and with additional cut lines  21  (dotted lines) at the edge regions of the web. Advantageously, these cut lines can be provided sequentially, wherein it is preferred that the cut lines  20  in the center region are provided before the cut lines  21  in the edge regions are made. 
     In  FIG. 4 , various types of window shapes are schematically illustrated that can be used in the composite web  2  according to the present invention. For example, the window  10 A in  FIG. 4  is generally rectangular, while window  10 B is generally parallelogram-shaped.  FIG. 5  illustrates patches  18  attached to the windows  10  shown in  FIG. 4 . As can be seen in  FIG. 5 , the patches  18  are generally somewhat larger than the windows  10  in order to provide for some additional area  24  that can be used to attach the patches  18  to the web  4 . For example, in the case of a rectangular window  10 A, the patch  18 A may be somewhat wider than the window  10 A so as to provide two longitudinal strips  24 A for attachment of the patch  18 A to the web  4 . Similarly, in the case of the parallelogram-shaped window  10 B, the patch  18 B is also parallelogram-shaped and somewhat wider than the window so as to provide attachment strips  24 B on both sides of the window which can be used to attach the patch  18 B to the web. It is also possible to attach the patches  18  completely around the windows  10  so as to provide an attachment region completely around the window. 
     In  FIG. 6  a further embodiment of a composite web  2  according to the present invention is illustrated. The composite web  2  comprises a web  4 , e.g., a non-woven web. Similarly as with the previous embodiments, the composite web  2  comprises in the longitudinal direction  12 , i.e. the machine direction (MD), various alternating sections  6 ,  8  that may be separated along cross machine direction (CD) cut lines  20 . Furthermore, in accordance with this embodiment of the composite web  2 , a longitudinal or machine direction cut line  26  is provided that separates the various sections  6 ,  8  into left and right sections  6   a ,  8   a ,  6   b ,  8   b . The windows  10  provided in sections  6   a ,  6   b  are covered with patches  18  in order to provide regions of different functional characteristics in the composite web  2 . Moreover, the sections  6   a ,  6   b  may be provided the with fastening tabs  22 . 
     Accordingly, with the composite web of the present invention presently used diaper manufacturing equipment can be used to provide improved diapers based on the composite web according to the present invention. 
     The web material used for the composite web can also be a multilayer web, wherein in each of the layers windows are provided. The strip(s) or patches of material with different functional characteristics can in this case be incorporated between the layers of the web.