Patent Publication Number: US-2023144533-A1

Title: Method and apparatus for producing pant-like absorbent sanitary articles

Description:
TECHNICAL FIELD 
     The present invention relates to a method and apparatus for producing absorbent sanitary articles. 
     The invention has been developed in particular for producing absorbent sanitary articles wearable as pants, for example the so-called training pants. 
     More specifically, the invention is directed to the production of refastenable absorbent sanitary articles, which can be opened and reclosed while worn by the user. 
     The present invention relates in particular to a method and an apparatus for producing absorbent sanitary articles according to the production technique called “Cross Direction”. 
     BACKGROUND ART 
     A consolidated technique for producing absorbent sanitary articles wearable as pants (both permanently closed and reclosable) consists of forming a continuous composite web movable in a machine direction and formed by a continuous chain of product blanks which are positioned with the longitudinal axis of each individual article transversal with respect to the machine direction. This production technique is normally called “Cross Direction” and differs from the more traditional production technique called “Machine Direction” which involves producing the absorbent sanitary articles while they advance with their longitudinal axes parallel to the machine direction. 
     Examples of methods for producing absorbent sanitary articles according to the Cross Direction technique are described in documents EP-A-1013251, IT1379452, IT1410464 and IT1410465 by the same Applicant. 
     The continuous composite web forming the chain of product blanks may comprise two elastic bands which are parallel to the machine direction and spaced apart from each other in a direction orthogonal to the machine direction, and a plurality of absorbent cores which extend between the two elastic bands orthogonally to the machine direction. The continuous composite web advancing in the machine direction is folded along a longitudinal axis parallel to the machine direction, so that said elastic bands overlap onto each other. 
     For producing absorbent sanitary articles which are openable and reclosable, refastenable closure elements are applied on the continuous composite web in spaced apart positions. The refastenable closure elements connect opposite portions of the continuous composite web after the longitudinal folding of the continuous composite web, as disclosed for instance in EP-A-3498246 of the same Applicant. 
     In traditional methods for producing absorbent sanitary articles according to the Cross Direction technique, the closure elements of the absorbent sanitary articles are usually located on the sides of the waistbands of the absorbent sanitary articles. The presence of refastenable closure elements on the sides of the absorbent sanitary articles may be undesired. Users may prefer absorbent sanitary articles in which the closure zones of the waistbands are positioned on the front waistband rather than along the sides to improve comfort and appearance. 
     US6447628 describes a method for producing reclosable absorbent sanitary articles in which the closure elements of the waistbands are located on the front parts of the articles. This arrangement is obtained by making a continuous chain of blanks of absorbent sanitary articles which have front waist regions with a shorter length than the rear waist regions. To produce absorbent sanitary articles of this type with a Cross Direction production technique, it is necessary to remove longitudinal stretches of one of the two waistbands of the continuous composite web. In the method described in this document, the removal of portions of one of the waistbands is performed before the longitudinal folding of the continuous composite web. This solution is difficult to implement in practice because after the removal of the portions of one of the longitudinal bands of the continuous composite web it becomes very difficult to perform the longitudinal folding of the continuous composite web with the necessary precision. 
     OBJECT AND SUMMARY 
     This object of the present invention is to provide a method and apparatus for producing absorbent sanitary articles which overcome the problems of the prior art. 
     More specifically, the object of the present invention is to provide a method and an apparatus for producing refastenable pant-like absorbent sanitary articles which reduces the waste of raw material, and which improves the stability and the quality of the manufacturing process. 
     According to the present invention, these objects are achieved by a method according to claim  1  and by an apparatus according to claim  10 . 
     The claims are an integral part of the teaching provided herein in relation to the invention. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will now be described in detail with reference to the accompanying drawings, given purely by way of non-limiting example, in which: 
         FIGS.  1  and  2    are schematic views of an embodiment of an absorbent sanitary article in outspread and closed configurations, respectively, 
         FIGS.  3 ,  4 ,  5    are schematic views of another embodiment of an absorbent sanitary article in outspread, partially closed, and closed configurations, respectively, 
         FIGS.  6  and  7    are schematic views of yet another embodiment of an absorbent sanitary article in outspread and closed configurations, respectively, 
         FIG.  8    is a schematic side view of an apparatus for producing absorbent sanitary articles, 
         FIGS.  9  -  14    are schematic views showing various steps of a method for producing absorbent sanitary articles, 
         FIGS.  15  and  16    are schematic plan views showing a fist embodiment of a folding station used in the method for producing absorbent sanitary articles, and 
         FIGS.  17  and  18    are schematic plan views showing a second embodiment of a folding station used in the method for producing absorbent sanitary articles. 
     
    
    
     It should be appreciated that the attached drawings are schematic and not to scale with respect to real products and that various figures may not be represented in the same scale. Also, in various figures some elements may not be shown to better show other elements. 
     DETAILED DESCRIPTION 
       FIGS.  1  and  2    show a first embodiment of a refastenable pant-like absorbent sanitary article  10 , respectively in an outspread configuration and in a closed configuration. In the closed configuration the refastenable absorbent sanitary article  10  has a pant-like shape typical of the so-called training pants. 
     The refastenable pant-like absorbent sanitary article  10  comprises an absorbent body  12  elongated along a main direction  14  and having first and second end portions  16 ,  18  opposite to each other with respect to a first folding line  20  orthogonal to the main direction  14  of the absorbent body  12 . In the closed configuration shown in  FIG.  2    the absorbent body  12  is folded about the first folding line  20  and the first and second end portions  16 ,  18  are overlapped to each other. 
     The absorbent body  12  has two side edges  22  extending along the main direction  14 . The side edges  22  may be straight and parallel to the main direction  14  as shown in the drawings. Alternatively, the side edges  22  may be curved to conform to the legs of the user when the refastenable pant-like absorbent sanitary article  10  is worn. 
     The absorbent body  12  may comprise an absorbent core enclosed between a topsheet of permeable material and a backsheet of impermeable material. The absorbent body  12  may also comprise elastic leg cuffs attached to the topsheet and extending parallel to the main direction  14 , as customary in the field. The absorbent body  12  may also comprise leg elastics extending along the side edges  22 . 
     The refastenable pant-like absorbent sanitary article  10  comprises a single elastic waistband  24  attached to the first end portion  16  of the absorbent body  12 . The elastic waistband  24  is elongated along a direction X transverse to the main direction  14  of the absorbent body  12 . The elastic waistband  24  is elastically stretchable along the direction X and may comprise a plurality of elastic wires enclosed between two non-woven layers. 
     The elastic waistband  24  has two elastic lateral bands  26  projecting laterally from opposite side edges  22  of the absorbent body  12 , and a central portion  28  attached to the first end portion  16  of the absorbent body  12 . The central portion  28  of the elastic waistband  24  may be attached, e.g. by glue, to the backsheet of the absorbent body  12 . In the central portion  28  the elastic elements of the elastic waistband  24  may be deactivated, e.g. by cuts that interrupt the elastic wires. 
     The elastic waistband  24  has an outer edge  30  and an inner edge  32 . The outer edge  30  may be straight and transverse to the main direction  14  of the absorbent body  12  and may project beyond a transverse edge of the absorbent body  12 . The inner edge  32  may be shaped to conform to the legs of the user when the refastenable pant-like absorbent sanitary article  10  is worn. 
     The lateral bands  26  of the elastic waistband  24  have respective first and second refastenable closure elements  34 ,  36  attached to respective distal portions. The refastenable closure elements  34 ,  36  may be micro-hook closure elements or refastenable adhesive elements. In the distal portions of the elastic waistband  24  where the refastenable closure elements  34 ,  36  are attached the elastic elements of the elastic waistband  24  may be deactivated, e.g. by cuts that interrupt the elastic wires. 
     The first and second refastenable closure elements  34 ,  36  may have areas with differential closure strength, which may be obtained through: 
     shape of the first and second refastenable closure elements  34 ,  36  (e.g. trapezoidal instead of rectangular);   micro-hook density variable on the surface of the first and second refastenable closure elements  34 ,  36 ;   any other means which provides differential closure strength.   

     In the closed configuration of  FIG.  2   , the lateral bands  26  of the elastic waistband  24  are folded about respective second folding lines  38 . The second folding lines  38  may be parallel to the main direction  14  and orthogonal to the first folding line  20 . 
     In the closed configuration of  FIG.  2   , the first and second refastenable closure elements  34 ,  36  releasably engage respective engagement areas  40 ,  42  on the backsheet of the absorbent body  12 . The engagement areas  40 ,  42  may be suitable for establishing a releasable surface connection with micro-hook closure elements and may be formed by portions of a frontal tape of loop material or by portions of a non-woven layer applied on the backsheet of the absorbent body  12 . 
     When the absorbent sanitary article  10  is worn, the refastenable closure elements  34 ,  36  are positioned on the front waist portion of the user and the elastic lateral bands  26  are smooth on the sides of the user, which is advantageous when the absorbent sanitary article  10  is worn beneath the garments. 
       FIGS.  3 - 5    show a second embodiment of a refastenable pant-like absorbent sanitary article  10 . The elements corresponding to those previously described are indicated by the same numeral references. 
     In the embodiment of  FIGS.  3 - 5   , the second end portion  18  of the absorbent body  12  is provided with transverse elastic elements  44  so that the second end portion  18  is elastically stretchable in the direction X transverse to the main direction  14 . Accordingly, in the outspread configuration shown in  FIG.  3    the second end portion  18  of the absorbent body  12  is tapered towards the distal end of the absorbent body  12 , opposite to the elastic waistband  24 . 
     In this embodiment, during the folding of the absorbent body  12  about the first folding line  20 , the second end portion  18  of the absorbent body  12  is stretched in the direction X as shown by the arrows  46  in  FIG.  4   , so that the engagement areas  40 ,  42  are brought in a position in which they are parallel to the respective first and second refastenable closure elements  34 ,  36 . Therefore, when the elastic lateral bands  26  of the elastic waistband  24  are folded about the respective second folding lines  38 , the first and second refastenable closure elements  34 ,  36  overlap and engage the respective engagement areas  40 ,  42 . 
       FIG.  5    shows the closed configuration of the refastenable pant-like absorbent sanitary article  10 , after folding the absorbent body  12  about the first folding line  20 , transversally stretching the second end portion  18  and folding the lateral bands  26  about the second folding lines  38 . 
       FIGS.  6  and  7    show a third embodiment of a refastenable pant-like absorbent sanitary article  10 . The elements corresponding to those previously described are indicated by the same numeral references. 
     In the embodiment of  FIGS.  6  and  7    the first and second refastenable closure elements  34 ,  36  are inclined with respect to the folding lines  38 . The distal edged of the lateral bands  26  may be cut along inclined lines parallel to the respective first and second refastenable closure elements  34 ,  36 . 
     In the closed configuration of the refastenable pant-like absorbent sanitary article  10  shown in  FIG.  7    the first and second refastenable closure elements  34 ,  36  extend along respective directions which are inclined to the main direction  14 . The inclined arrangement of the closure formations is designed to improve the comfort of the refastenable pant-like absorbent sanitary article  10  when worn. 
     Also in this embodiment, the second end portion  18  of the absorbent body  12  may be provided with transverse elastic elements  44  so that in the outspread configuration shown in  FIG.  6    the second end portion  18  of the absorbent body  12  is tapered towards the distal end of the absorbent body  12 . Also in this embodiment, during the folding of the absorbent body  12  about the first folding line  20 , the second end portion  18  of the absorbent body  12  may be stretched in the direction X. 
     With reference to  FIG.  8   , numeral reference  50  indicates an apparatus for producing refastenable pant-like absorbent sanitary articles  10  as previously disclosed. 
     The apparatus  50  comprises a conveyor  52  configured for advancing in a longitudinal direction a continuous elastic band  54 . A glue dispenser  56  may be provided for applying discrete glue layers on a surface of the continuous elastic band  54 . 
     A continuous composite absorbent web  58  is fed to the apparatus  50  in a longitudinal direction. The continuous composite absorbent web  58  comprises a continuous absorbent core enclosed between a continuous backsheet and a continuous topsheet. The continuous composite absorbent web  58  may comprise continuous longitudinal leg cuffs, continuous longitudinal leg elastics and transverse elastic elements  44  spaced apart from each other in the longitudinal direction. 
     The apparatus  50  comprises a transverse cutting unit  60  configured for transversely cutting the continuous composite absorbent web  58  to form individual absorbent bodies  12 . At the exit of the transverse cutting unit  60  the individual absorbent bodies  12  are oriented with the respective main directions  14  parallel to the moving direction. 
     The apparatus  50  comprises a turn-and-repitch unit  62 , comprising a plurality of gripping elements which are configured for retaining respective absorbent bodies  12 , e.g. by suction. The gripping elements of the turn-and-repitch unit  62  take respective absorbent bodies  12  at the transverse cutting unit  60  and turn the individual absorbent bodies  12  by 90° such that the individual absorbent bodies  12  are oriented with the respective main directions  14  transverse to the moving direction. The gripping elements of the turn-and-repitch unit  62  are rotatable independently of each other around a common axis of rotation and are configured to space from each other the individual absorbent bodies  12  at an application pitch. 
     The individual absorbent bodies  12  are transferred from the gripping elements of the turn-and-repitch unit  62  to the continuous elastic band  54  and are applied in longitudinally spaced position on areas of the continuous elastic band  54  where glue layers have been previously applied, so that the individual absorbent bodies  12  are attached by glue to the continuous elastic band  54 . 
       FIG.  9    schematically shows the continuous elastic band  54  after the attachment thereon of the absorbent bodies  12  in longitudinally spaced positions. The absorbent bodies  12  are oriented with the respective main directions  14  orthogonal to the longitudinal direction X of the continuous elastic band  54 . The absorbent bodies  12  project transversally from the continuous elastic band  54 . The first end portions  16  of the absorbent bodies  12  are attached to the continuous elastic band  54  and the second end portions  18  project freely from the continuous elastic band  54 . The continuous elastic band  54  may have a longitudinal edge portion  64  of non-woven material which may be folded about a longitudinal folding line to overlap the transverse edges of the absorbent bodies  12 . Elastic elements may be inserted in the folded longitudinal edge portion  64  to form a gasketing formation along the outer edges of the waistbands. 
     With reference to  FIG.  8   , the apparatus  50  comprises two closure element application units  66 ,  68 , configured for applying on the continuous elastic band  54  first and second refastenable closure elements  34 ,  36  in spaced apart positions along the longitudinal axis X. The first and second refastenable closure elements  34 ,  36  may be formed by transversally cutting respective continuous webs unwound from respective reels. 
       FIG.  10    shows the continuous elastic band  54  with the first and second refastenable closure elements  34 ,  36  applied thereon. As shown in  FIG.  10   , the first and second refastenable closure elements  34 ,  36  are arranged in pairs, each pair being formed by one first closure element  34  and one second closure element  36  parallel and close to each other and transverse to the longitudinal direction X of the continuous elastic band  54 . Each pair of first and second refastenable closure elements  34 ,  36  is applied to the continuous elastic band  54  in a position intermediate between two adjacent absorbent bodies  12 . The first and second refastenable closure elements  34 ,  36  may be fixed to the continuous elastic band  54  by glue and/or welding (thermocompression or ultrasonic welding). 
     When two closure element application units  66 ,  68  are provided, the first closure element application unit  66  applies the first refastenable closure elements  34  and the second closure element application unit  66  applies the second refastenable closure elements  36 . In a possible embodiment, the apparatus  50  may comprise a single closure element application unit  62  or  64  configured for applying simultaneously pairs of first and second refastenable closure elements  34 ,  36 . 
     With reference to  FIG.  8   , the apparatus  50  may comprise a longitudinal cutting unit  70  configured for cutting the longitudinal edge  32  of the continuous elastic band  54  along a shaped profile designed to conform to the legs of the user. The longitudinal cut of the longitudinal edge of the continuous elastic band  54  may be carried out before or after applying the pairs of first and second closure elements  34 ,  36 .  FIG.  10    shows the continuous elastic band  54  after the application of the pairs of first and second closure elements  34 ,  36  and after the longitudinal cut of the longitudinal edge  32 . 
     With reference to  FIG.  11   , the continuous elastic band  54  is cut along transverse cutting lines  72  extending between each pair of first and second closure elements  34 ,  36  to form a succession of individual refastenable absorbent sanitary article  10  in an outspread configuration. 
     With reference to  FIG.  8   , the apparatus  50  comprises a folding unit  74  configured for folding in a pant-like configuration the individual refastenable absorbent sanitary articles  10  initially in an outspread configuration. 
     With reference to  FIG.  8   , the folding unit  74  may comprise a rotating knife  80  configured for transversally cutting the continuous elastic band  54  on the rotating drum  76  to form the succession of individual absorbent sanitary articles  10  in outspread configuration. In a possible embodiment, the continuous elastic band  54  may be cut upstream of the folding unit  74  so that the rotating drum  76  receives a flow of individual absorbent sanitary articles  10  in outspread configuration. 
     With reference to  FIGS.  8  and  12 ,  13   , the folding unit  74  comprises a rotating drum  76  carrying a plurality of folding stations  78  each of which is configured for receiving a respective individual absorbent sanitary articles  10  in the outspread configuration. 
     With reference to  FIGS.  12  and  13   , each folding station  78  comprises a base  82  configured for receiving and retaining, e.g. by suction holes, a respective absorbent sanitary article  10  in the outspread configuration. Each folding station  78  comprises at least one longitudinal folding shoe  84  articulated to the base  82  and configured for folding the respective absorbent body  12  of the respective absorbent sanitary article  10  about the first folding line  20 . 
     Each folding station  78  comprises two transverse folding shoes  86  articulated to the base  82  and configured for folding the two lateral bands  26  of the respective absorbent sanitary article  10  about respective second folding lines  38  to close the absorbent sanitary article  10  in a pant-like configuration. When the two lateral bands  26  are folded about the respective folding lines  38  the first and second refastenable closure elements  34 ,  36  are overlapped to the respective engagement areas  40 ,  42  and establish a surface connection therewith. 
       FIG.  14    shows the array of finished refastenable absorbent sanitary articles  10  closed in a pant-like configuration at the exit of the folding unit  74 . 
       FIGS.  15  and  16    show a first embodiment of a folding station  78  configured for folding the respective absorbent body  12  about the first folding line  20  and for simultaneously stretching in the longitudinal direction X the distal portions of the respective second end portion  18 . 
     The folding station  78  comprises two longitudinal folding shoes  84  articulated to the base  82  about respective axes  88  inclined with respect to each other. The two longitudinal folding shoes  84  are provided with holes connected to a source of sub-atmospheric pressure, to retain by suction respective sections of the respective second end portions  18 . The base  82  is also provided with suction holes to retain by suction the refastenable absorbent sanitary article  10  in the outspread position shown in  FIG.  15   . 
     During the rotation of the two longitudinal folding shoes  84  about the respective axes  88 , the two longitudinal folding shoes  84  overlap the second end portion  18  to the respective first end portion  16 , as shown in  FIG.  16   . Since the two longitudinal folding shoes  84  rotate about respective axes inclined with respect to each other the distal end of the respective second end portion  18  is stretched in the direction indicated by the arrows  46  in  FIG.  18   . 
     In the embodiment of  FIGS.  15  and  16   , the two longitudinal folding shoes  84  have respective side openings  90  which leave exposed the respective engagement areas  40 ,  42  of the second end portion  18 . In this embodiment, after folding the second end portion  18  over the respective first end portion  16  the longitudinal folding shoes  84  continue to hold the second end portion  18  while the transverse folding shoes  86  fold the respective elastic lateral bands  26  around the respective second folding lines  38  and the first and second refastenable closure elements  34 ,  36  engage the respective engagement areas  40 ,  42  through the side openings  90  of the longitudinal folding shoes  84 . After the first and second refastenable closure elements  34 ,  36  engage the respective engagement areas  40 ,  42 , the longitudinal folding shoes  84  and the transverse folding shoes  86  release the second end portion  18  and the elastic lateral bands  26  and return to the position of  FIG.  15    in which they are coplanar to the base  82 . 
       FIGS.  17  and  18    show a second embodiment of a folding station  78  configured for folding the respective absorbent body  12  about the first folding line  20  and for simultaneously stretching in the longitudinal direction X the distal portions of the respective second end portion  18 . The elements corresponding to those previously disclosed are indicated by the same reference numbers. 
     In this second embodiment, the two longitudinal folding shoes  84  differ from the longitudinal folding shoes  84  of the first embodiment in that no side openings are provided. In this embodiment, after folding the second end portion  18  over the respective first end portion  16  the longitudinal folding shoes  84  cover the engagement areas  40 ,  42  of the second end portion  18 , as shown in  FIG.  18   . 
     In this embodiment, after folding the second end portion  18  over the respective first end portion  16  and simultaneously stretching in the direction X the distal edge of the second end portion  18  as shown in  FIG.  18   , the longitudinal folding shoes  84  release the second end portion  18  and return to the position of  FIG.  17   . The second end portion  18  is held in the folded position in that the distal edge of the second end portion  18  is in direct contact with the central portion  28  of the elastic waistband  24 . Since the elastic waistband  24  is porous, the distal edge of the second end portion  18  is retained by suction by the base  82 . 
     In this embodiment, after the longitudinal folding shoes  84  disengage from the second end portion  18  the transverse folding shoes  86  fold the respective elastic lateral bands  26  around the respective second folding lines  38  and overlap the first and second refastenable closure elements  34 ,  36  to the respective engagement areas  40 ,  42  to close the refastenable absorbent sanitary article  10  in the pant-like configuration. 
     The rotations of the longitudinal and transverse folding shoes  84 ,  86  about the respective axes  88 ,  38  may be controlled by cams or by actuators, which control the movement of the longitudinal and transverse folding shoes  84 ,  86  depending on the angular position of the rotating drum  76 . 
     In a possible embodiment, a micro-hook front panel including a plurality of micro-hooks may be provided on a portion of the outer surface of the backsheet in the first end portion  16  of the absorbent body  12  and the distal portions of the elastic lateral bands  26  may be provided with micro-loop material (e.g. a non-woven layer or micro-loop pads) suitable for establishing a refastenable connection with the micro-hooks of the front panel. The micro-hook front panel may be integrally formed on a portion of the outer surface of the backsheet, as disclosed in EP21181365.4 of the same applicant (not yet published at the filing date of this application). 
     Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may be widely varied with respect to those described and illustrated here, without departing from the scope of the invention as defined by the claims that follow.