System and method for increased removal torque values for rationally engaging polymeric members

Abstract

A torque retention apparatus and method for use with container-closure combinations including selection of retainer or other component materials such that variations in material properties of the materials and/or dimensional changes in the components over time contribute to substantially increased torque retention. Selection of container contents and the configuration of supplemental sealing and/or attachment features may further contribute to the substantial increase in torque retention. A fitment having an annular well and tubular wick retainer is interposed between the container and the closure.

1 . A torque retention apparatus for use with a container and closure combination, the apparatus comprising: 
 a first retainer formed on the container, said first retainer comprised of a first polymer;    a second retainer formed on the closure and configured to engage said first retainer through application of a set torque during installation of the closure on the container, said second retainer comprised of a second polymer, said first and second polymers selected such that a removal torque applied to disengage said first and second retainers following an extended period of engagement is substantially greater than fifty percent of said set torque.    
   
   
       2 . The apparatus of  claim 1 , wherein said removal torque is at least equal to said set torque.  
   
   
       3 . The apparatus of  claim 1 , wherein said first and second polymers are selected from the group consisting of polypropylene, polyethylene, polyvinyl chloride, and copolymers of the same.  
   
   
       4 . The apparatus of  claim 1 , wherein said first and second retainers comprise complimentary threads.  
   
   
       5 . The apparatus of  claim 1 , wherein a substance contained by the container is selected to interact with at least one of said first and second polymers to contribute to said removal torque.  
   
   
       6 . The apparatus of  claim 1 , further comprising a fitment interposed between the container and the closure, said fitment configured to attach to at least one of the container and the closure, said fitment at least one of configured to and comprised of a material selected to contribute to said removal torque.  
   
   
       7 . The apparatus of  claim 6 , wherein said fitment is a wick holder comprising: 
 a tubular portion for receiving a wick;    at least a first sealing feature for sealingly engaging the closure; and    at least a second sealing feature for sealingly engaging the container.    
   
   
       8 . The apparatus of  claim 7 , wherein at least one of said first and second sealing features contributes to said removal torque.  
   
   
       9 . The apparatus of  claim 8 , wherein relative material properties of said first and second polymers, interaction between container contents and at least one of said first polymer, said second polymer and said fitment, and friction generated by at least one of said first and second sealing features cooperate to contribute to said removal torque.  
   
   
       10 . The apparatus of  claim 7 , wherein said fitment includes at least one of a circumferential skirt for engaging the neck of the container and an annular well surrounding said tubular portion.  
   
   
       11 . The apparatus of  claim 10 , wherein said first sealing feature is an annular projection contacting an outer sidewall of said well, and said second sealing feature is an annular projection on the closure contacting a complimentary annular grove in a top surface of said fitment.  
   
   
       12 . The apparatus of  claim 1 , wherein a first said removal torque is between 100 percent and 250 percent of a first said set torque, a second said removal torque is between 100 percent and 150 percent of a second said set torque of twice said first said set torque, and a third said removal torque is between 75 percent and 100 percent of a third said set torque of three times said first said set torque.  
   
   
       13 . A torque retention apparatus for use with a container and closure combination, the apparatus comprising: 
 a fitment interposed between the container and the closure and attachable to at least one of the container and the closure;    a first retainer formed on one of the container and said fitment, said first retainer comprised of a first polymer;    a second retainer formed on one of the closure and said fitment and configured to engage said first retainer through application of a set torque during installation of one of the closure and said fitment on the container, said second retainer comprised of a second polymer, said first and second polymers selected such that a removal torque applied to disengage said first and second retainers following an extended period of engagement is substantially greater than fifty percent of said set torque.    
   
   
       14 . The apparatus of  claim 13 , wherein the closure is retained by at least one of the container and said fitment.  
   
   
       15 . The apparatus of  claim 13 , further comprising a friction generating feature in addition to said first and second retainers contributing to said removal torque.  
   
   
       16 . The apparatus of  claim 13 , wherein at least two of a sealing feature formed on one of the container, the closure, and said fitment, a frictional feature formed on one of the container, the closure, and said fitment, and a substance contained in the container contribute to said removal torque.  
   
   
       17 . An improved container-closure combination, the improvement comprising: 
 a first retainer of a first polymer formed on the container;    a second retainer of a second polymer formed on the closure for rotational engagement of said first retainer by application of a set torque, said first and second polymers selected such that a removal torque required to disengage said first and second retainers following an extended period of engagement is substantially greater than fifty percent of said set torque.    
   
   
       18 . A method of increasing torque retention in rotationally engaged combinations, the method comprising: 
 selecting a first polymer;    forming a first retainer on a first component, said first retainer comprised of said first polymer;    selecting a second polymer;    forming a second retainer from said second polymer on a second component for rotational engagement with said first retainer, and    applying a set torque between said first and second components to engage said first and second retainers with frictional interference between said first and second retainers, a relative difference in a material property of said first and second polymers contributing to a reduced degree of loss of the frictional interference over time such that a removal torque required to overcome the frictional interference following at least one of an extended period of engagement at ambient temperature and a shortened period of engagement at an elevated temperature is substantially greater than fifty percent of said set torque.    
   
   
       19 . The method of  claim 18 , wherein at least one of said forming steps comprises forming at least one of said first and second retainers from at least one of polypropylene, and polyethylene.  
   
   
       20 . The method of  claim 18 , further comprising selecting a liquid for interaction with at least one of said first and second polymers to further reduce said degree of loss of said frictional interference.  
   
   
       21 . The method of  claim 18 , wherein said first forming step comprises forming threads on a container, said second forming step comprises forming complimentary threads on a closure, the method further comprising forming a fitment configured to attach to at least one of the container and the closure from at least one of said first polymer, said second polymer, and a third polymer.  
   
   
       22 . The method of  claim 18 , wherein said steps of selecting said first and second polymers contribute to said removal torque being in excess of said set torque.