Abstract:
The present invention discloses and teaches an improved fitment for use on paperboard, gable top liquid containers and the like. More specifically the present invention teaches a easy open tamper evident seal including a pull ring attached to the seal by means of a post having an aspect ratio of less than two thereby requiring less pulling force to break the tamper evident seal and remove it from the fitment spout.

Description:
RELATED APPLICATIONS 
     This application claims the priority of Provisional Application Ser. No. 60/092,861, filed Jul. 15, 1998 and titled “Easy Opening Spout.” 
    
    
     BACKGROUND 
     The present invention generally relates to an improved pour spout, or fitment, commonly used on paperboard, gable top liquid containers. More particularly, the present invention relates to a linerless fitment having a thin frangible, tamper evident (TE), tear-away seal, integral with the inside the fitment opening. 
     Tamper evident seals as used on gable top containers typically have a “pull-ring” device attached to the frangible sealing membrane by a connecting post. The consumer pulls on the pull ring to break and remove the seal. A common complaint with such tear-away seals has been directed to the amount of force necessary to initially break and remove the seal. It has been discovered that the force necessary to break and remove the tear-away TE seal is directly dependent upon the geometry and location of the post connecting the pull ring to the TE seal. 
     By the present invention an improved post geometry has been developed to reduce the force required to break and remove the TE seal or disk from the fitment. An improved pull ring geometry has also been developed to improve grasping the ring. These improvements are considered important for the easy opening feature for consumer convenience. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an easy opening fitment spout that incorporates an integral tamper evident, ring pull seal that exhibits an opening force of 5 pounds or less to remove the TE seal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 presents a pictorial view of the spout portion of a fitment assembly embodying the present invention. 
     FIG. 2 presents a vertical crossection of a complete fitment assembly embodying the present invention. 
     FIG. 2A is an enlarged view of the circled area in FIG.  2 . 
     FIG. 3 presents a crossectional view taken along line  3 — 3  in FIG.  2 . 
     FIG. 4 presents a crossectional view taken along line  4 — 4  in FIG.  3 . 
     FIG. 5 presents a crossectional view taken along line  5 — 5  in FIG.  6 . 
     FIG. 6 presents partial bottom view looking upward along line  6 — 6  in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIGS. 1,  2 , and  2 A present an improved fitment assembly  10  embodying the present invention. My improved fitment assembly  10  generally comprises 2 basic components; an injection molded, linerless closure  12 , and an injection molded spout  14  with an integrated TE liner molded into the spout opening  18 . The integrated TE liner comprises a disk  16  molded to the inner spout wall  18 , and a pull ring  20  that is attached to disk  16  by means of an integral, upward extending post  22 . The circumference of the disk  16  at the attachment point to the inner wall  18  of spout  14  is molded into a thin, annular, sealing membrane  26  that is designed to tear away, when ring  20  is pulled, resulting in removal of the TE disk  16  when spout  14  is initially opened for use. 
     The force necessary to break and remove TE disk  16  is dependent upon several factors such as; the composition of the plastic resin, the thickness of annular sealing membrane  26 , the size, configuration and “aspect ratio” of post  22 , the location of the post attachment relative to the annular sealing membrane  26 , and the rigidity of the spout wall. The “aspect ratio” of post  22 , as used herein, is defined as the width w divided by the length l (see FIG.  4 ). 
     Typically, in this type of pull ring spout application, low density polyethylene (LDPE) is used because of the relative ease of disk removal although other materials can be used as will be evident from the ensuing discussion. 
     In addition to material selection, the thickness of the annular tear away sealing membrane  26  can influence the ease of opening of the TE disk  16 . The range of membrane thickness is restricted by the practical limits imposed by the injection molding process as well as the force to open. A TE membrane that is too thin, for example, may have material missing from the membrane area when molded or may fail during removal of the spout  10  from the injection mold during manufacture. Conversely, a sealing membrane that is too thick would require excessive force to break and remove it from the spout during initial opening by the consumer. A typical membrane thickness currently in commercial use lies within the range of 0.006″ to 0.013″. 
     The cross sectional area of the post  22  at the attachment to the disk  16  as well as the orientation and distance of the post attachment from the sealing membrane  26  can each influence the ease of disk removal for any given sealing membrane thickness. By focusing the pulling force at the sealing membrane  26  via an attachment or post with a small cross sectional area in close proximity to the sealing membrane, removal forces can be reduced significantly. As is the case with sealing membrane thickness, there is a practical limit to the smallest attachment post cross sectional area in order to eliminate the risk of attachment or post failure upon opening and removal of the TE disk. 
     I have discovered that for any given post attachment cross sectional area  32 , the aspect ratio of width w and length l is directly related to the force necessary to initially break and start the tearing off sealing membrane  26 , when removing the TE disk  16 . I have also discovered that a narrow attachment dimension x, tangent to sealing membrane  26  requires less force to initiate tearing of the sealing membrane than one which has a larger dimension x. 
     The proximity of post  22 &#39;s attachment area to sealing membrane  26  also influences the pulling force necessary to initiate tearing of membrane. The closer the post attachment to sealing membrane  26 , the less force required to remove TE disk  16 . The attachment area should be as close as possible but not interfere with removal of the assembly from the injection mold or it will result in removal related membrane failure prior to use. 
     The location of the membrane  26  attachment on the inner spout wall  18  of the spout  14  can also influence the force necessary to break and tear TE membrane  26 . Babcock et al. (U.S. Pat. No. 5,735,426) teaches that the membrane location should be located on an intermediate shoulder portion  30  of the spout inside wall in order not to reduce the effective cross sectional area of the spout. Locating the membrane above the transitional shoulder area  30 , as is the case in the present invention, takes advantage of the spout wall flexibility and results in an easier opening force without significantly reducing the effective opening area of the spout. In addition, there is a material savings associated with reducing the height h of attachment post  22  that results from moving the sealing membrane attachment to the spout inside wall  18  and thereby closer to the top of the spout. 
     Pull ring handle  20  (as illustrated in FIG. 6) is preferably offset by a convenient dimension S, approximately 0.010 inches for a nominal one inch diameter spout, thereby making it more easy to grasp pull ring  20  and avoids the difficulties associated with raising the pull ring up to open without the interference of the inside spout wall  18 . A pull ring which is concentric to TE disk  16 , and large enough to accommodate a large finger size, will contact the inside spout wall  18  when attempting to grasp the ring to open. This generally results in the finger slipping out of the ring and makes opening less convenient. 
     Experimental testing has indicated that a fitment having a post attachment cross section area  32  of 0.007 to 0.010 sq. in., and having a sealing membrane thickness  26  of 0.03 in to 0.07 in., and having an post aspect ratio w/l of less than 2, and having the attachment post  22  in close proximity to the TE disk membrane  26  requires less pulling force, upon pull ring  20  to remove the integrated TE disk  16  from the spout without compromising the TE feature. 
     Table A describes the relationship of the pull ring attachment dimension, aspect ratio, proximity to the tear away membrane seal, and membrane seal thickness to the force required to open three prior art fitments and the present improved fitment. As seen in Table A, the force required to break and remove the sealing membrane is 5.4 pounds as opposed to the nearest prior art fitment which requires 6.5 pounds of force, a reduction of twenty percent. However, as it is also shown in Table A, the force required to break the post is a substantial 9.5 pounds or 75 percent higher than the required membrane breaking force as opposed to 70 percent for the nearest performing prior art system identified as Sample C. 
     Having described the preferred embodiments of the present invention, and its benefits and advantages, it will be understood by those of ordinary skill in the art that the foregoing description is merely for the purpose of illustration and that numerous substitutions, rearrangements, and modifications may be made in the invention without departing from the scope and spirit of the appended claims. 
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE A 
               
             
             
               
                   
               
               
                 SUMMARY OF TAMPER EVIDENT PULL RING ATTACHMENT DIMENSIONS 
               
               
                  AS RELATED TO OPENING FORCE 
               
             
          
           
               
                   
                   
                   
                   
                 Distance From 
                   
                 Average 
               
               
                   
                   
                 Dimensional 
                   
                 Post 
                 Average 
                 Force To 
               
               
                   
                 Attachment 
                 Aspect 
                 Thickness of 
                 To Centerline 
                 Force To 
                 Break 
               
               
                   
                 Area 
                 Ratio 
                 Membrane 
                 Of Membrane 
                 Open 
                 Post 
               
               
                 Identification 
                 (sq. in.) 
                 w/l 
                 (in.) 
                 (in.) 
                 (lb) 
                 (lb) 
               
               
                   
               
             
          
           
               
                           Sample A 
                 0.02799 
                 0.71 
                 0.013 
                 0.007 
                 9.1 
                 14.3 
               
               
                 Sample B 
                 0.01109 
                 3.11 
                 0.009 
                 0.02 
                 8.4 
                 13.8 
               
               
                 Sample C 
                 0.01497 
                 3.22 
                 0.006 
                 0.08 
                 6.5 
                 11.1 
               
               
                 IMPROVED 
                 0.00813 
                 1.10 
                 0.006 nom 
                 0 
                 5.4 
                 9.5