Method, apparatus, and nozzle for applying varying amounts or types of adhesive on an elastic strand

Abstract

A method and devices for dispensing adhesive onto an elastic strand are configured to apply first, second, and third volumes of adhesive onto first, second, and third portions of the elastic strand, respectively. When the elastic strand is adhesively secured to a substrate to form a personal disposable hygiene product, the first and third portions of the elastic strand define opposing ends of the elastic strand, which are adhered with a larger amount of adhesive or a stronger adhesive material capable of limiting movement of the strand at the opposing ends. The method and devices advantageously use a module and nozzle which maintain separation between first and second adhesive streams received from different adhesive supplies at least until flow within the nozzle. This arrangement enables use of different adhesives to form the first, second, and third volumes, as well as “wet-on-wet” contact dispensing using multiple nozzle outlets.

What is claimed is: 
     
         1 . A dispensing apparatus for applying adhesive to a stretched elastic strand to be adhered to a substrate to form a personal disposable hygiene product, the elastic strand including first, second, and third portions along a length of the elastic strand, the dispensing apparatus comprising:
 a module including a first passage terminating at a first module outlet and configured to communicate with a first adhesive supply to thereby receive a first adhesive stream, said module also including a second passage terminating at a second module outlet and configured to communicate with a second adhesive supply to thereby receive a second adhesive stream, wherein said first and second passages are separated within said module such that the first and second adhesive streams remain separate during movement through said module;   a dispensing nozzle coupled to said module and including a first nozzle inlet communicating with said first module outlet, a second nozzle inlet communicating with said second module outlet, and at least one nozzle outlet for dispensing adhesive onto the stretched elastic strand; and   a first valve and a second valve that open and close to control flow of the first and second adhesive streams, respectively, through said module and into said nozzle, thereby controlling dispensing of adhesive onto the elastic strand such that a first volume of adhesive is applied onto the first portion of the elastic strand, a second volume of adhesive is applied onto the second portion of the elastic strand, and a third volume of adhesive is applied onto the third portion of the elastic strand, with the second volume being less than the first volume and less than the third volume,   wherein the first and third portions of the elastic strand define opposing ends of the elastic strand when adhered to the substrate, and the second portion of the elastic strand defines a central portion of the elastic strand extending between the opposing ends when adhered to the substrate.   
     
     
         2 . The dispensing apparatus of  claim 1 , wherein said at least one nozzle outlet of said nozzle further comprises:
 a first nozzle outlet communicating with said first nozzle inlet so as to receive and discharge the first adhesive stream onto the elastic strand; and   a second nozzle outlet communicating with said second nozzle inlet so as to receive and discharge the second adhesive stream onto the elastic strand, said second nozzle outlet being located downstream of said first nozzle outlet in a machine direction defined by movement of the elastic strand relative to said nozzle, and the first and second adhesive streams remaining separated during flow through said nozzle.   
     
     
         3 . The dispensing apparatus of  claim 2 , wherein said nozzle further comprises:
 a first expansion chamber at said first nozzle outlet and configured to contact the first adhesive stream with the elastic strand to contact dispense adhesive onto the elastic strand;   a second expansion chamber at said second nozzle outlet and configured to contact the second adhesive stream with the elastic strand to contact dispense adhesive onto the elastic strand; and   an air outlet positioned at a rear side of said nozzle which is downstream in the machine direction from each of said first and second expansion chambers, said air outlet configured to discharge pressurized air towards adhesive in contact with the elastic strand as the elastic strand moves past said rear side, to assist with spreading of the adhesive around the elastic strand.   
     
     
         4 . The dispensing apparatus of  claim 3 , wherein said nozzle further comprises:
 a first groove extending between said first and second expansion chambers, said first groove sized to receive the elastic strand with adhesive from the first adhesive stream during movement in the machine direction; and   a second groove extending between said second expansion chamber and said rear side, said second groove being sized larger than said first groove such that a larger volume of adhesive can be carried on the elastic strand.   
     
     
         5 . The dispensing apparatus of  claim 1 , wherein said at least one nozzle outlet consists of a single nozzle outlet that communicates with each of said first nozzle inlet and said second nozzle inlet so as to receive and discharge one or both of the first and second adhesive streams onto the elastic strand, the first and second adhesive streams thereby being combined during flow through said nozzle. 
     
     
         6 . The dispensing apparatus of  claim 5 , wherein said single nozzle outlet is positioned spaced above the elastic strand as the elastic strand moves relative to said nozzle in a machine direction, such that said single nozzle outlet is configured to dispense at least one of the first and second adhesive streams as a filament that travels towards the elastic strand, and said nozzle further comprises:
 a plurality of air outlets located proximate to said single nozzle outlet and configured to discharge air streams that generate a swirling motion in the filament as the filament travels towards the elastic strand.   
     
     
         7 . The dispensing apparatus of  claim 1 , said first and second valves each being positioned within said module such that flow of the first and second adhesive streams is selectively terminated before flow through said first and second module outlets and into said nozzle. 
     
     
         8 . The dispensing apparatus of  claim 7 , further comprising:
 a control operatively connected to said first and second valves and controlling operation of said first and second valves by:
 opening said first valve while leaving said second valve closed to apply the first volume of adhesive onto the first portion of the elastic strand; 
 closing said first valve to stop applying the first volume of adhesive; 
 opening said second valve while leaving said first valve closed to apply the second volume of adhesive onto the second portion; 
 closing said second valve to stop applying the second volume of adhesive; and 
 opening said first valve while leaving said second valve closed to apply the third volume of adhesive onto the third portion of the elastic strand. 
   
     
     
         9 . The dispensing apparatus of  claim 7 , further comprising:
 a control operatively connected to said first and second valves and controlling operation of said first and second valves by:
 opening the first and second valves to apply the first volume of adhesive to the first portion of the elastic strand;
 closing the second valve while leaving the first valve open to apply the second volume of adhesive to the second portion of the elastic strand; and 
 opening the first and second valves to apply the third volume of adhesive to the third portion of the elastic strand. 
 
   
     
     
         10 . A contact dispensing nozzle for applying adhesive to a stretched elastic strand moving in a machine direction, the nozzle comprising:
 a nozzle body including a front side, a rear side, and a slot for receiving the elastic strand and extending between said front and rear sides, said slot defining a strand guide portion which guides movement of the elastic strand along the machine direction;   a first adhesive passage formed in said nozzle body and extending between a first nozzle inlet and a first nozzle outlet, said first nozzle inlet configured to receive a first adhesive stream from a first adhesive supply, said first nozzle outlet communicating with said slot to deliver the first adhesive stream into contact with the elastic strand; and   a second adhesive passage formed in said nozzle body and extending between a second nozzle inlet and a second nozzle outlet, said second nozzle inlet configured to receive a second adhesive stream from a second adhesive supply, said second nozzle outlet communicating with said slot downstream from said first nozzle outlet in the machine direction to deliver the second adhesive stream into contact with the elastic strand, said first and second adhesive passages maintaining separation between the first and second adhesive streams during flow through the nozzle.   
     
     
         11 . The contact dispensing nozzle of  claim 10 , further comprising:
 an air passage formed in said nozzle body and terminating at an air outlet positioned proximate said rear side of said nozzle body, which is downstream from said first and second nozzle outlets in the machine direction, said air outlet configured to discharge pressurized air towards adhesive in contact with the elastic strand as the elastic strand moves past said rear side, to assist with spreading of the adhesive around the elastic strand.   
     
     
         12 . The contact dispensing nozzle of  claim 10 , further comprising:
 a first expansion chamber formed in said nozzle body adjacent said first nozzle outlet, said first expansion chamber sized to enable die swell of the first adhesive stream upon exit from said first nozzle outlet and at the point of contact dispensing the first adhesive stream onto the elastic strand; and   a second expansion chamber formed in said nozzle body adjacent said second nozzle outlet, said second expansion chamber sized to enable die swell of the second adhesive stream upon exit from said second nozzle outlet and at the point of contact dispensing the second adhesive stream onto the elastic strand.   
     
     
         13 . The contact dispensing nozzle of  claim 12 , wherein said slot further comprises:
 a first groove extending between said first and second expansion chambers, said first groove sized to receive the elastic strand with adhesive from the first adhesive stream during movement in the machine direction; and   a second groove extending between said second expansion chamber and said rear side, said second groove being sized larger than said first groove such that a larger volume of adhesive can be carried on the elastic strand.