Patent Abstract:
Diapers are made with substantial reduction of waste using a composite web of diaper main body material having a liquid impervious outer layer, a liquid pervious inner layer and an absorbent intermediate layer there between. The composite web has an indeterminate longitudinal extent substantially intact and uncut with parallel lateral side edge margins for substantially the entire web length. An independent web of diaper tab material is cut into discrete tab sections of predetermined mating shapes with substantially no unused waste material. The tab sections are affixed to the opposite edge margins of, and at regular longitudinal spacings along, the composite web. The composite web is cut transversely at regular longitudinal intervals there along corresponding to the spacings of the tab sections to produce discrete diapers each having a generally rectangular main body and four tabs at the respective corners of the main body.

Full Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to the production of diapers, particularly disposable diapers, and more specifically, to methods of producing such diapers. 
     Over recent decades, disposable diapers have come to dominate the market for both infant diaper products and adult incontinence products, largely replacing traditional cloth fabric diapers and incontinent garments. Such disposable diapers, both for infants and adults, basically comprise three main components: an inner web or sheet of a liquid permeable material, typically a non-woven, for direct contact with the wearer&#39;s body, an intermediate core of a liquid absorbent material typically in the form of a pad of hydrophilic fibers and often including a supplementary absorbent medium such as a super absorbent polymeric material for capturing and holding bodily fluids passing through the permeable inner layer, and an outer web or sheet of a liquid impervious material usually comprised of a laminate of film and non-woven materials to retain liquid within the absorbent core against leakage from the diaper. 
     For optimal fitting of such diapers to the typical contours of a wearer&#39;s body, such diapers commonly are formed of an overall hourglass shape providing a narrowed crotch area situated between wider front and back portions respectfully for covering the abdomen and buttocks of a wearer. The laterally extending margins of the wider front and back portions of the diaper form wing-like tabs which can be overlapped with one another when worn so as to encircle fully the waist of the wearer and, together with the crotch portion, to form leg openings encircling the upper legs of the wearer adjacent the wearer&#39;s crotch. The wing-like tab portions are typically provided with fastener elements, such as adhesive elements, hook-and-loop fastener elements, or other appropriate means for securely holding the tab-portions in overlapping relationship. The diapers are also often provided with elastic bands or filaments within the lateral borders of the crotch portion to enhance conformance of the crotch portion to the body of the wearer and thereby additionally mitigate risk of fluid leakage. 
     The process of making diapers of the basic above-described construction is generally well known in the relevant art and is accomplished by a substantially fully automated process wherein respective webs of liquid impervious and liquid permeable sheet roll stock are fed simultaneously with a web of absorbent padding material through so-called converting machinery which orients the respective webs in a sandwich-like relationship to be assembled by an appropriate manner of bonding of the webs, e.g., by ultrasonic welding. Each respective web is typically of an elongate continuously length of material having parallel lateral side edges. In the process of feeding the web of the outer liquid impervious layer, appropriate segments of the material are severed from each opposite side of the moving sheet roll stock at regular intervals to form a repeating pattern of hourglass shapes along the length of the advancing web material. In some cases, the sheet roll stock of liquid permeable material for forming the inner web may be of a dimension laterally coextensive with that of the outer web of material, in which case corresponding segments of material are severed from the inner web also, but alternatively the inner web may be of a more narrow lateral dimension to only overlie the crotch portion and the corresponding central regions of the front and rear portions of the outer web. 
     Disadvantageously, all such materials severed from the outer web, and optionally also from the inner web, constitute waste which must be discarded and may comprise up to approximately 11 percent of the overall costs of materials utilized in diapers. Accordingly, there is a substantial recognized need within the industry for alternative methodologies or techniques in the fabrication of such diapers that will enable the creation of discarded waste material to be eliminated or at least significantly reduced. 
     SUMMARY OF THE INVENTION 
     It is accordingly a general object of the present invention to provide an improved method of making diapers, particularly disposable diapers, with substantially reduced production of discarded waste material. A more particular object of the present invention is to eliminate the necessity of severing and discarding segments of web material in order to form diapers in a traditional hourglass configuration. A further object of the present invention is to provide a methodology by which the output by a single diaper production line can be essentially doubled. 
     Briefly summarized, the present invention provides a method of making diapers wherein a composite web of material for making a diaper main body is provided with a substantially liquid impervious outer layer, a substantially liquid impervious inner layer, and an absorbent intermediate layer between the outer and inner layers. The composite web has a longitudinal extent of an indeterminate continuous length which is substantially intact and uncut without any portions or sections severed therefrom and discarded, such that the composite web has substantially parallel linear edge margins along opposite lateral sides thereof for substantially the entire continuously length of the composite web. An independent web of material for forming diaper tabs is also provided and has a longitudinal extent of indeterminate continuous length. The web of tab material is cut into discrete tab sections of predetermined mating shapes which produce substantially no waste material which is unused as the tab sections. The tab sections are affixed to the opposite edge margins of, and at predetermined regular longitudinal spacings along, the composite web. Thereafter, the composite web is cut transversely at regular longitudinal intervals along the web corresponding to the spacings of the tab sections, to produce a plurality of discrete diapers each having a generally rectangular main body formed by the material of the composite web and four tabs at respective corners of the main body, formed by the tab sections. 
     In a preferred embodiment of the method of the present invention, the composite web is preformed by providing the outer and inner layers of coextensive indeterminate continuous lengths having corresponding substantially parallel linear longitudinal edges along opposite lateral sides thereof, and assembling the outer and inner layers coextensively in overlying relation with one another substantially without cutting and discarding any material from the inner and outer layers. In assembling the outer and inner layers, the absorbent material is inserted therebetween, preferable as discrete absorbent pads spaced longitudinally from one another. The tab sections are preferably affixed to the composite web at the spacings intermediately of the absorbent pads. 
     The transverse cutting of the composite web is preferably performed at the spacings intermediately of the absorbent pads at a location longitudinally intermediately along the tab sections for separating each tab section into at least two tabs. 
     The tab sections may be affixed to the composite web in any suitable manner, but most preferably by means of a fin-type seal between each tab section and the composite web. 
     Most preferably, the steps of the present method are performed while continuously advancing the composite web of diaper main body material and the independent web of diaper tab material in synchronism with respect to each other. 
     In a preferred embodiment, the composite web is formed with the discrete absorbent pads arranged in two laterally spaced longitudinal rows of correspondingly longitudinally spaced absorbent pads inserted and assembled between the inner and outer layers of the composite web. The tab sections are affixed not only at the opposite edge margins of the composite web but also intermediate the longitudinal rows of the absorbent pads, with the tab sections at predetermined regular longitudinal spacings along the composite web corresponding to the spacings intermediately of the absorbent pads. The composite web is cut both transversely at regular longitudinal intervals at locations longitudinally intermediately along the tab sections and also cut longitudinally between the two rows of absorbent pads transversely intermediate the tab sections therebetween. In this manner, two identical pluralities of discrete diapers are produced, with each diaper having a generally rectangular main body formed of the composite web material and four tabs at the respective corners of the main body formed by the tab sections. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic depiction of the conventional prior art methodology for fabricating disposable diapers in the traditional hourglass shape as above-described; 
         FIG. 2A  is a schematic depiction in side elevation showing the formation of a composite web of material for a diaper main body in accordance with a preferred embodiment of the method of the present invention; 
         FIG. 2B  is a schematic depiction in top plan view corresponding to the illustration of the production of the composite web of  FIG. 2A ; 
         FIG. 3  is a schematic depiction of a web of diaper tab material being advanced and cut into discrete tab sections in accordance with a preferred embodiment of the method of the present invention; 
         FIGS. 4A and 4B  schematically depict sequential steps in the placement and affixation of the diaper tab sections to the composite web, followed by the transverse and longitudinal cutting of the composite web to produce plural discrete diapers, also according to a preferred embodiment of the method of the present invention; and 
         FIG. 5  is a schematic perspective view of a diaper made in accordance with the preferred embodiment of the method of the present invention depicted in  FIGS. 2A ,  2 B,  3 ,  4 A and  4 B. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the accompanying drawings  FIG. 1  depicts in simplified schematic form the general methodology of the current state of the art for the mechanized automated manufacture of disposal diapers wherein an advancing web of diaper material, generally indicated at  10 , is preliminarily cut to remove arcuate segments  12  from the opposed side edges of the web  10  at regular periodic spacings to pre-form the web into a repeating lengthwise series of hourglass shapes. This pre-forming step is performed on at least the web material  10  to be incorporated into a diaper as the liquid impervious outer layer of the diaper, but may also be performed for some diaper embodiments to correspondingly pre-form the web material for the liquid pervious inner layer (not shown). The arcuate segments  12  which are thusly removed constitute waste which is discarded. Even though such waste material may be susceptible of recycled use, the waste adds significantly to the costs of production of diapers, as already discussed above. 
     The present invention seeks to overcome these disadvantages of known diaper forming methods by a novel methodology depicted schematically in  FIGS. 2A ,  2 B,  3 ,  4 A and  4 B. In basic generalized terms, the present invention contemplates the initial formation of a composite web of material suitable for use as the main body of a diaper, that is, comprising a liquid impervious outer layer, a liquid pervious inner layer and an absorbent intermediate layer therebetween as depicted schematically in  FIGS. 2A and 2B ; the coordinated formation of a separate independent web of material into discrete diaper attachment tab sections, as depicted schematically in  FIG. 3 ; and the subsequent affixation of the diaper attachment tab sections to the composite web, as depicted schematically in  FIG. 4A , followed by the cutting of the composite web into a plurality of discrete diapers, as depicted schematically in  FIG. 4B . 
     With reference more specifically to  FIGS. 2A and 2B , the composite web is indicated in assembled form generally at  14  and basically comprises a web or sheet  16  of a liquid impervious material such as a thermoplastic film to serve as the outer layer (sometimes called the bottom layer) of the main body of a diaper. Commonly, the outer, or bottom, layer may include a non-woven web laminated to the thermoplastic film along a central area of the web. The composite web  14  further comprises a web or sheet  18  of a liquid permeable or liquid pervious material, such as a non-woven web suitable to form the inner, or top, layer of the main body of a diaper. Each web  16 ,  18  is of a flat open-width sheet-like configuration having substantially parallel linear longitudinal edges (see  FIG. 2B ) along opposite lateral sides thereof. The webs  16 ,  18  are stored on and fed from respective storage rolls  22 ,  24  on which an elongate continuous indeterminate length of the web is wound, with the webs being fed therefrom to advance in a common direction for assembly together in width wise and length wise coextensive overlying relation to one another. 
     As the outer and inner webs  16 ,  18  are thusly advanced, the absorbent core material is correspondingly advanced from a suitable source of supply to be fed between the outer and inner webs  16 ,  18 , for assembly therewith as an intermediate absorbent layer. The absorbent material may be of any suitable type and form capable of liquid absorption, e.g., a non-woven web of padding material of hydrophilic fibers, and may incorporate supplementary absorptive media such as a super absorbent polymeric material impregnated in, intermingled with, or otherwise contained by the absorbent web. The absorbent web is preferably cut as it is advanced into discrete absorbent pads which are delivered between the outer and inner webs  16 ,  18 , at lengthwise spacings from one another to form respective absorbent crotch pads in discrete diapers to be subsequently formed according to the present method. This technique is commonly known and used in the industry and therefore is only schematically represented in  FIG. 2A  by the discrete absorbent pads  20  advancing forwardly from a cutting element represented only by knife  26 . In the cutting of the absorbent web into discrete absorbent pads  20 , it is additionally preferred that the absorbent web be cut into an oblong hourglass configuration, as best shown in  FIG. 2B , in conformity to the general shape of the crotch and adjacent forward and rearward areas in a diaper when worn. However, it is to be understood that the present invention is not limited to this type and configuration of absorbent pad. For example, the web of absorbent material could be fed as a continuous uninterrupted length of web correspondingly to that of the outer and inner webs  16 ,  18 . 
     In the formation of the composite web  14 , other common elements of disposable diapers may also preferably be incorporated into the web, such as elastic filaments  28  to extend along opposite side edges of the composite web. Other common components of disposable diapers not shown in the drawings may also be incorporated into the composite web at this stage of assembly, e.g., a perforated acquisition distribution film layer may desirably be fed and inserted between the absorbent pads  20  and the inner web layer  18 . These and other common diaper construction elements are not excluded from use in the present invention but do not form a part of the novelty of the present invention. 
     As depicted in  FIG. 2B , in a preferred embodiment of the present invention, the outer and inner webs  16 ,  18 , together with the absorbent pads  20  and the elastic filaments  28  are assembled to form simultaneously two identical composite webs in side-by-side relationship, integrated together by the common outer and inner webs  16 ,  18 . For such purpose, the absorbent pads  20  are delivered between the webs  16 ,  18  in side-by-side pairs to form the pads in the integrated composite web  14  in two laterally spaced longitudinal rows of pads which are correspondingly spaced longitudinally along the composite web  14 . Likewise, the elastic filaments  28  are fed between the inner and outer webs  16 ,  18  simultaneously along the opposite outer lateral edge margins of the webs  16 ,  18  and also along opposite sides of the longitudinal centerline extending the length of the outer and inner webs  16 ,  18 , (indicated at CL) between the spaced rows of absorbent pads  20 , all as depicted in  FIG. 2B . The two integrated composite webs are hereinafter respectively identified as composite webs  14 A and  14 B while the two composite webs  14 A and  14 B are collectively referred to herein as composite web  14 . The respective components of the composite web  14  are joined together in any suitable known manner, such as the common technique of ultrasonic welding of the respective webs together, thereby capturing and retaining the absorbent pads  20  and the elastic filaments  28  between the outer and inner webs  16 ,  18 . 
       FIG. 3  depicts schematically a processing line, operable in parallel and synchronism to the methodology for forming the composite web  14  depicted in  FIGS. 2A and 2B , by which is provided the separate independent web of material for forming diaper attachment tabs. The attachment tab web is represented schematically at  30  and is basically an open-width flat web of material of any suitable composition compatible for affixation with the material of the outer web  16  of the composite web  14 , e.g., by ultrasonic welding or another suitable means of affixation. For example, the diaper attachment tab web  30  may be made of the same thermoplastic film as is incorporated into the outer web  16 , or may be a non-woven web having a stretchable panel or stretch properties. The widthwise dimension of the diaper attachment tab web  30  is preferably less than one-half of the overall lateral width of the composite web  14  such that the web  30  may be conveniently cut into discrete tab sections for attachment as tab portions to each of the side-by-side composite webs  14 A and  14 B, all as more fully described below. 
     The diaper attachment tab web  30  is of an elongate continuous indeterminate length having substantially parallel edges along its opposite outer lateral sides. The diaper attachment web  30 , according to the methodology of the present invention, is continuously advanced and severed lengthwise and transversely in a repeating pattern of cuts producing three discrete tab sections  32 A,  32 B,  32 C for each repeating pattern of cuts. As depicted in  FIG. 3 , the broken lines in the unsevered section of the web  30  represent the repeating pattern of cuts, with one grouping of severed tab sections  32 A,  32 B,  32 C being shown as having advanced to the point in the processing line of being severed into the discrete tab sections. 
     As previously indicated, the advancing delivery of the diaper attachment tab web  30  is coordinated in synchronism with that of the production of the composite web  14  occurring in parallel.  FIG. 4A  depicts the affixation of the tab sections  32 A,  32 B,  32 C to the advancing composite web  14 . In  FIG. 4A , the broken lines CT, which extend transversely across the composite web  14  in perpendicular relation to the longitudinal center line CL along the composite web  14  midway intermediate the spaced pairs of absorbent pads  20 , represent cutting locations at which the composite web  14  will be subsequently severed into discrete individual diapers at a later downstream point in the diaper producing methodology, as more fully described hereinbelow. As will be seen, the tab section  32 A is of a size and configuration suitable to be severed into four discrete diaper tabs, as represented by the broken lines depicted in tab section  32 A. Similarly, each of tab sections  32 B and  32 C are of a size and configuration essentially one-half that of the tab section  32 A, so that each tab section  32 B and  32 C is suitable to be severed into two discrete diaper tabs, as represented by the transverse broken lines depicted in such tab sections  32 B and  32 C. 
     Following severing of each repeating group of three tab sections  32 A,  32 B,  32 C, the severed tab sections are transferred by suitable mechanical implements (not shown) as are known in the art, onto the surface of the inner web  18  at one transverse cutting location CT, as depicted in  FIG. 4A . More specifically, the tab section  32 A is rotated 180 degrees from its orientation when cut from the diaper attachment tab web  30  and, in such rotated orientation, is placed at the intersection of the longitudinal center line CL and the transverse cutting line CT in the composite web  14  so as to symmetrically overlap each of the adjacent four diaper sections of the composite webs  14 A,  14 B, whereby the tab cutting lines transversely and longitudinally in the tab section  32 A coincide with the underlying transverse and center lines CT, CL in the composite web  14 . Similarly and simultaneously, the two tab sections  32 B and  32 C are transferred to overlie laterally outward edge margins of the composite web  14  with their respective transverse cutting lines coinciding with the transverse cutting line CT across the composite web  14 , whereby each tab section  32 B and  32 C respectively overlies symmetrically the two adjacent diaper sections of the respective composite webs  14 A and  14 B. 
     With the tab sections  32 A,  32 B and  32 C thusly positioned overlying the composite web  14 , the respective tab sections are affixed to the composite web  14 , preferable by ultrasonic welding. More specifically, the laterally outwardly oriented edges of the tab sections  32 B and  32 C are bonded respectively to the underlying laterally outward edge margins of the respective composite webs  14 A,  14 B along lines just outwardly of the elastic filaments  28  which extend along such edge margins of the composite webs  14 A,  14 B, thereby forming a fin-type seal between the tab sections and the composite web. Simultaneously, the tab section  32 A is bonded along its lengthwise extending central cutting line to each composite web  14 A,  14 B along the longitudinal center line CL of the composite web  14  laterally adjacent the elastic filaments  28  extending therealong, similarly forming a fin-type seal. 
     As the composite web  14  with the thusly attached diaper sections  32 A,  32 B and  32 C is further advanced along the diaper producing line, the composite web  14  and the attached tab sections  32 A,  32 B and  32 C are severed transversely at the cutting line CT and longitudinally along the center line CL, thereby severing the tab section  32 A into four discrete diaper tabs and severing each of tab sections  32 B and  32 C into two discrete diaper tabs, and thereby producing two discrete diapers each with four diaper tabs, as represented by diapers  34  in  FIG. 4B . As the composite web  14  continues to advance with subsequently attached diaper tab sections  32 A,  32 B and  32 C at following transverse cutting lines CT, the repetitive performance of the methodology as above described thusly produces simultaneously two identical pluralities of diapers  34 . 
       FIG. 5  depicts schematically the basic construction of each such diaper  34 . As will be recognized, for sake of clarity, the diaper  34  in  FIG. 5  is depicted with the elastic filaments  28  still stretched in the elongated state in which the filaments are held throughout the method steps depicted from  FIGS. 2A and 2B  through the final process steps of  FIGS. 4A and 4B . However, those persons skilled in the art will recognize that, upon severing of the individual diapers  34 , the elastic filaments  28  will be caused to relax longitudinally. 
     Each diaper  34  thusly has a main diaper body  36  essentially of a rectangular configuration as formed by one diaper section of one composite web  14 A,  14 B, comprising basically an outer layer of web material  16 , an inner layer of web material  18 , and a single absorbent pad  20  disposed therebetween, and with four individual diaper tabs  38  at the respective corners of the main diaper body  36  disposed in overlying relation to the main diaper body  36  by virtue of the fin-type seal by which the tabs  38  were bonded to the lateral edges of the main diaper body  36  in the process step of  FIG. 4A . 
     The methodology of the present invention will thus be understood to offer distinct advantages over the current state of the relevant art. First, as already discussed above, the basic process methodology of the present invention enables the main body of a diaper to be fabricated of a rectangular configuration without cutting and discarding any waste material of the inner and outer webs, thereby accomplishing a significant cost savings over conventional methods wherein the discarded waste material represents as much as 11% of the overall material costs of diapers. Further, the formation of the main diaper body of a rectangular configuration conveniently enables multiple pluralities of diaper bodies to be fabricated in side-by-side relation from a single composite web, thereby at least doubling the overall output of a single diaper processing line. The attachment of the diaper tabs by a fin-type seal avoids the conventional necessity with traditional diapers of manipulating the tabs into such overlapping relation as part of the process of folding and packaging diapers, thereby more conveniently simplifying and facilitating the folding and packaging of the diapers of the present invention. 
     It will therefore be readily understood by those persons skilled in the art that the present invention is susceptible of broad utility and application. Many embodiments and adaptations of the present invention other than those herein described, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description thereof, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to its preferred embodiment, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the claims appended hereto and the equivalents thereof.

Technology Classification (CPC): 0