Spundbonding spin pack characterized by uniform polymer distribution and method of use

Abstract

A meltspinning apparatus that provides for uniform distribution of a flow of a melt-processable thermoplastic polymer in a machine direction of the meltspinning apparatus. The meltspinning apparatus includes a spin pack having a plurality of side-by-side coathanger-shaped distribution chambers. Each of the distribution chambers uniformly distributes the polymer flow in the machine direction so that the molten polymer has a substantially uniform residence time in the chamber during distribution.

1 . A spin pack for forming a molten polymer into filaments, comprising: 
 a distribution plate including a length, a width, and a plurality of distribution chambers, each of said distribution chambers having an inlet receiving a flow of the molten polymer, a slotted outlet having a major axis oriented substantially parallel to said width, and a coathanger-shaped distribution passageway coupling said inlet with said slotted outlet; and    a spinneret downstream from said distribution plate, said spinneret having a plurality of channels and a plurality of spinning orifices from which the filaments are discharged, each of said spinning orifices associated with one of said channels, and said channels being arranged in a plurality of columns aligned along said width, each of said channels receiving the flow of the molten polymer from said slotted outlet of one of said distribution chambers.    
   
   
       2 . The spin pack of  claim 1  wherein said slotted outlet has opposite closed ends, and each of said distribution chambers includes a pair of distribution channels each diverging laterally away from said inlet toward a corresponding one of said opposite closed ends.  
   
   
       3 . The spin pack of  claim 2  wherein each of said distribution channels further includes a distribution passageway coupling said pair of distribution channels with said slotted outlet, said distribution passageway having a dimension measured parallel to said width that is smaller than a dimension measured parallel to said width of said pair of distribution channels.  
   
   
       4 . The spin pack of  claim 1  wherein said distribution passageway includes a major dimension measured parallel to said width that increases from said inlet to said slotted outlet.  
   
   
       5 . The spin pack of  claim 1  wherein said inlet of each of said plurality of distribution chambers is positioned on an imaginary line extending along said length.  
   
   
       6 . The spin pack of  claim 5  wherein said imaginary line bisects said distribution plate along said width.  
   
   
       7 . The spin pack of  claim 1  further comprising: 
 a transfer plate upstream from said distribution plate, said transfer plate including a plurality of passageways oriented parallel to said width, and each of said passageways providing the molten polymer to said inlet of a corresponding one of said distribution chambers.    
   
   
       8 . The spin pack of  claim 1  wherein said width is shorter than said length.  
   
   
       9 . A melt spinning apparatus for forming a molten polymer into filaments, comprising: 
 a collector positioned for collecting the filaments and moving in a travel direction;    a spin pack including a distribution plate and a spinneret downstream from said distribution plate, said distribution plate having a length, a width aligned substantially parallel to said travel direction, and a plurality of distribution chambers, each of said distribution chambers having an inlet receiving a flow of the molten polymer, a slotted outlet having a major axis oriented substantially parallel to said width, and a coathanger-shaped distribution passageway coupling said inlet with said slotted outlet, and said spinneret having a plurality of channels and a plurality of spinning orifices from which the filaments are discharged, each of said spinning orifices associated with one of said channels, and said channels being arranged in a plurality of columns aligned along said width, each of said channels receiving the flow of the molten polymer from said slotted outlet of one of said distribution chambers; and    a drawing device positioned between said spin pack and said collector, said drawing device operative for attenuating the filaments discharged from said spinning orifices.    
   
   
       10 . The melt spinning apparatus of  claim 9  wherein said slotted outlet has opposite closed ends, and each of said distribution chambers includes a pair of distribution channels each diverging laterally away from said inlet toward a corresponding one of said opposite closed ends.  
   
   
       11 . The melt spinning apparatus of  claim 10  wherein each of said distribution channels further includes a distribution passageway coupling said pair of distribution channels with said slotted outlet, said distribution passageway having a dimension measured parallel to said width that is smaller than a dimension measured parallel to said width of said pair of distribution channels.  
   
   
       12 . The melt spinning apparatus of  claim 9  wherein said distribution passageway includes a major dimension measured parallel to said width that increases from said inlet to said slotted outlet.  
   
   
       13 . The melt spinning apparatus of  claim 9  wherein said inlet of each of said plurality of distribution chambers is positioned on an imaginary line extending along said length.  
   
   
       14 . The melt spinning apparatus of  claim 13  wherein said imaginary line bisects said distribution plate along said width.  
   
   
       15 . The melt spinning apparatus of  claim 9  wherein said spin pack further comprises: 
 a transfer plate upstream from said distribution plate, said transfer plate including a plurality of passageways oriented parallel to said width, and each of said passageways providing the molten polymer to said inlet of a corresponding one of said distribution chambers.    
   
   
       16 . The melt spinning apparatus of  claim 9  wherein said width is shorter than said length.  
   
   
       17 . A method of operating a meltspinning apparatus for forming a plurality of filaments from a flow of a molten polymer, comprising: 
 moving a collector in a travel direction;    distributing the flow of the molten polymer in a first direction generally perpendicular to the travel direction;    distributing the flow of the molten polymer in a second direction generally parallel to the travel direction so that the molten polymer has a substantially uniform residence time in a distribution chamber during distribution;    supplying the distributed flow of the molten polymer to a plurality of channels for forming a plurality of filaments; and    collecting the plurality of filaments on the collector.    
   
   
       18 . The method of  claim 17  wherein the distribution chamber has a slotted outlet with a major axis oriented in the travel direction, and distributing the flow of the molten polymer in the second direction comprises: 
 adjusting the flow of portions of the molten polymer within the distribution chamber to provide the substantially uniform residence time in the distribution chamber for molten polymer emerging at all points across the slotted outlet.    
   
   
       19 . The method of  claim 17  wherein each of the distribution chambers has a slotted outlet with a major axis oriented in the travel direction, and distributing the flow of the molten polymer in the second direction comprises: 
 adjusting the flow of portions of the molten polymer within the distribution chamber so that the molten polymer emerging from the slotted outlet has a substantially uniform pressure at all points across the slotted outlet.    
   
   
       20 . The method of  claim 17  wherein distributing the flow of the molten polymer in the second direction comprises providing flow paths of different length in the distribution chamber to provide the substantially uniform residence time.