Patent Publication Number: US-2020297545-A1

Title: Device for forming a composite web of an absorbent pad for absorbent articles

Description:
This application claims priority to Italian Patent Application 102019000004097 filed Mar. 21, 2019, the entirety of which is incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     This invention relates to a device for forming a composite web of an absorbent pad for absorbent articles. 
     The composite web of this device is a web comprising “meltblown” fibers, that is to say, a composite web having at least one layer obtained by melt blowing. 
     In this field of application, the need was felt to control the concentration of superabsorbent polymer material particles fed into the layer of meltblown fibers. 
     SUMMARY OF THE INVENTION 
     In this context, one aspect of this invention is to provide a device for forming a composite web of an absorbent pad for absorbent articles, such as diapers, for example, and which comprises an extruding means for extruding a thermoplastic material and provided with one or more channels, each having a respective delivery mouth for delivering filaments of thermoplastic material. 
     A delivery means for delivering superabsorbent polymer material has at least one outlet mouth for feeding the superabsorbent polymer material into the flow of filaments of thermoplastic material coming out of the extruding means. 
     A suction forming surface is configured to receive the filaments of thermoplastic material coming out of the extruding means and comprising the superabsorbent polymer material, to make a composite, meltblown web comprising meltblown thermoplastic fibers and superabsorbent polymer material. 
     The outlet mouth of the delivery means is configured to be movable at least from a first distance to a second distance, or vice versa, relative to the delivery mouth of the extruding means in such a way as to vary the concentration of the superabsorbent polymer material in the composite web. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features of the invention and its advantages are more apparent in the following non-limiting description of preferred but non-exclusive embodiments of a device for forming a composite web of an absorbent pad for absorbent articles, as illustrated in the accompanying drawings, in which: 
         FIG. 1  is a schematic front view of a first embodiment of the device according to this invention; 
         FIG. 2  is a schematic front view of a second embodiment of the device according to this invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The reference numeral  1  denotes a device for forming a composite web of an absorbent pad for absorbent articles according to this invention. 
     The term “absorbent articles” is used to mean diapers for children and/or adults. 
     The device  1  comprises a tank  2  for containing thermoplastic material. 
     By way of non-limiting example, the thermoplastic material may be polypropylene, polyethylene, acrylic resin, polyamide (nylon, for example), polystyrene, polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), polycarbonate. 
     A substantially hydrophilic polymeric material, such as hydroxyl-polypropylene for example, may also be used. 
     An extruding means  3  for extruding thermoplastic material fed from the tank  2  comprises one or more channels, each having a respective delivery mouth  4  for delivering filaments  5  of thermoplastic material. 
     The extruding means  3  is configured to produce a flow of filaments  5  of meltblown thermoplastic material. 
     A source  6  of heated, pressurized gaseous fluid is in fluid communication with the extrusion ducts of the extruding means  3 . 
     A delivery means  9  for delivering superabsorbent polymer material  10  is configured to feed the superabsorbent polymer material  10  into the flow of filaments  5  of thermoplastic material coming out of the extruding means  3 . 
     In a variant embodiment, a pressurized fluid source  20  is connected to the delivery means  9  so that the superabsorbent polymer material  10  is fed under pressure into the flow of filaments  5  of thermoplastic material coming out of the extruding means  3 . 
     A suction forming surface  7  is configured to receive the flow of filaments  5  of thermoplastic material coming out of the extruding means  3  and to receive the superabsorbent polymer material  10  coming out of the delivery means  9 , to make a composite web  8  of meltblown fibers comprising the superabsorbent polymer material  10 , or composite meltblown web  8 . 
     In this embodiment, the suction forming surface  7  is the peripheral surface of a suction roller  12  that rotates about its axis  12   a.    
     The delivery means  9  is provided with at least one outlet mouth  11  for feeding the superabsorbent polymer material  10 . 
     Optionally, the delivery means  9  for delivering the superabsorbent polymer material  10  may be provided with a means for heating the superabsorbent polymer material  10 . 
     The outlet mouth of the delivery means is configured to be movable at least from a first distance “d 1 ” to a second distance “d 2 ”, or vice versa, relative to the delivery mouth  4  of the extruding means  3  in such a way as to vary the concentration of the superabsorbent polymer material  10  in the meltblown composite web  8 . 
     This distance variation allows the outlet mouth  11  of the delivery means  9  to be positioned near or far from the delivery mouth  4  of the extruding means  3  so as to vary the concentration of the superabsorbent polymer material  10  in the meltblown composite web  8 . 
     More specifically, by positioning the outlet mouth  11  of the delivery means  9  near the delivery mouth  4  of the extruding means  3  at a distance d 1 , the concentration of the superabsorbent polymer material  10  in the flow of filaments  5  of thermoplastic material is greater than when the outlet mouth  11  of the delivery means  9  is positioned far from the delivery mouth  4  of the extruding means  3 , at a distance d 2  greater than d 1 . 
     That is because the temperature of the flow of filaments  5  of thermoplastic material decreases from the delivery mouth  4  of the extruding means  3  to the forming surface  7  of the composite web  8 ; hence, the superabsorbent polymer material  10  adheres to the flow of filaments  5  of thermoplastic material more when it is closer to the delivery mouth  4  of the extruding means  3  than it is to the forming surface  7  of the meltblown composite web  8 . 
     The device  1  comprises a first feed unit  13  for feeding a first continuous web  14  of non-woven fabric, preferably spunbond, disposed upstream of the forming surface  7 , in the feed direction of the meltblown composite web  8 , so that the meltblown composite web  8  is made on the first continuous web  14 , as illustrated in  FIG. 2 , held by suction on the forming surface  7 . 
     The presence of the first feed unit  13  for feeding the first continuous web  14  of non-woven fabric is optional. 
     In the second embodiment, shown in  FIG. 2 , the device comprises a second feed unit  15  for feeding a second continuous web  16  of non-woven fabric, preferably spunbond, disposed downstream of the forming surface  7 , in the feed direction of the meltblown composite web  8 , so that the second continuous web  16  is disposed on the meltblown composite web  8  made on the forming surface  7 . 
     The presence of the second feed unit  15  for feeding the second continuous web  16  of non-woven fabric is optional. 
     If the device  1  comprises both the first feed unit  13  and the second feed unit  15 , the meltblown composite web  8  is interposed between the first continuous web  14  and the second continuous web  16  to define a continuous multilayer web  19 . 
     In a variant embodiment, the device  1  comprises a feeding means  17  for feeding a moistening substance  18  and disposed downstream of the second feed unit  15 , in the feed direction of the second continuous web  16 . 
     That way, the moistening substance  18  is delivered to the second continuous web  16 . 
     Alternatively, in a variant not illustrated, a moistening substance  18  is fed to the extruding means  3  so that the flow of filaments comprises the moistening substance when it comes out of the extruding means  3 . 
     In the first embodiment of the invention, shown in  FIG. 1 , only the meltblown composite web  8  comprising superabsorbent polymer material  10  is fed out of the device  1 . In the second embodiment of the invention, shown in  FIG. 2 , the web feeding out of the device  1  is a multilayer web  19  comprising the meltblown composite web  8  interposed between the first continuous web  14  of non-woven fabric, specifically spunbond, and the second web  16  of non-woven fabric, specifically spunbond. 
     The meltblown composite web  8  or the multilayer web  19  comprising the meltblown composite web  8  will subsequently be cut into respective pieces to define the absorbent pad of an absorbent article. 
     The meltblown composite web  8  or the multilayer web  19  will subsequently define a roll of meltblown composite web  8  or a roll of multilayer web  19 .