Abstract:
A method and apparatus for formation of a preformed bonded pull tab over a reseal liner is disclosed. The pull tab seal layer of material is bonded together with a reseal liner layer of material for insertion into a closure. The pull tab on the pull tab liner seal is formed prior to combination of the two layers and is folded backwards between the two layers of material. Thus, after combining the two layers, punching out the closure liner and insertion into the closure, the reseal liner is separated from the pull tab seal and the pull tab seal is adhered to the rim of the container. Only one punch press step is required for forming the closure and container seals and insertion of the members into the closure. By forming the pull tab prior to combining the two layers, an assembly of the pull tab and reseal liner is made more efficient and less time consuming.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This present invention relates to manufacturing reseal and pull tab liners which are combined in a closure and which have a pull tab for removing, upon first use, a liner adhered to the container. These types of reseal liners are manufactured and placed in the interior of a closure which is either threadably attached to a container or is snap fitted on the container neck. The pull tab liner is adhered to the rim of the container mouth and is removed by the user upon first use of the container contents. There is also a gasket or reseal liner placed in the interior of the closure to properly seal the container after removal of the pull tab liner. 
     2. Discussion of the Prior Art 
     Pull tab reseal liners are fairly well known in the container and closure arts. Historically, these reseal liners are cut out of a web of material and inserted into the closure. A pull tab seal is then prepared, cut out and inserted into the closure which is then threadably screwed onto the container neck. There are many drawbacks however to the prior art manufacturing methods for generating reseal liners and pull tab liners which are adhered to the mouth or rim of a container. First and foremost, since the combined inserted liner is made of multiple layers of varying materials, multiple steps have historically been required for assembly and insertion of the pull tab liner and closure reseal liner into the closure. Additionally, these manufacturing problems have resulted in the layers of the sealing liner material being mis-aligned within the closure and possibly causing the pull tab to be improperly placed along the threads of the container lessening the accessibility of the pull tab for the user. 
     U.S. Pat. No. 4,754,890 to Ullman et al teaches a tamper evident safety seal which is formed from a sealing liner having an integral tab portion and having a tab being double folded for release of the pull tab liner. The sealing liner for the Ullman reference combines a layer of foil and foam causing the foil to be folded over one edge and then mated with the foam before punching out the liner into the closure. However, one drawback in the tamper evident safety seal taught therein is that the fold over portion of the liner results in a large section of wasted material as opposed to utilizing only a small pull tab, as is used in most removable pull tab and reseal liner combinations. Additionally, the large section of fold over liner material can prevent the closure from sealing properly on the neck of the container before the fold over seal liner is removed thereby impeding the closure from threading onto the container completely or preventing an adequate seal of the container. 
     There are additional methods of forming a pull tab reseal liner comprised of a first section of wax paperboard overlaid by a separate section of aluminum foil and plastic or seal material, the paperboard acting as the liner in the closure and the aluminum foil and other seal material acting as the pull tab seal liner on the container. These systems, however, such as is shown in U.S. Pat. No. 5,261,990 require the wax paperboard to be punched into the die containing the closure, and in a separate process the pull tab and liner material is separately formed and stamped into the closure for later bonding to the container rim after attachment of the closure on the container. The first layer of paperboard is glued into position against the top wall in the closure above the threads. The pull tab and liner material is then forcibly inserted and frictionally held into place by the threads until later bonding to the container. However, in this embodiment, accurate positioning of the liner material within the cap and of the pull tab is difficult because the separate layers are not combined and pressed into the closure concurrently causing positioning problems with the layers and other assembly difficulties. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to overcome the deficiencies of the prior art listed above. 
     It is another object of the present invention to provide a preformed bonded pull tab over a reseal liner which can be constructed in a single manufacturing step thereby preventing separate insertions of liner material into the closure. 
     It is an additional object of the present invention to form pull tabs on a sealing liner which can be accurately placed and positioned for the user to remove the liner from the container and which prevents the pull tab from being folded under the liner material or being creased along the threads of the container. 
     It is a further object of the present invention to provide an improved method and apparatus for construction of a preformed bonded pull tab which efficiently utilizes the lining material with limited waste and which can feed a combined paperboard and pull tab liner sheet of material through a standard lining machine for punching into a closure. 
     Finally, the present invention comprises a method for manufacturing a bonded pull tab over a reseal liner for a closure, comprising: forming pull tabs in a pull tab liner web of material; folding said pull tabs backwards and underneath said pull tab liner web; forming a bonded pull tab over a reseal liner by joining said pull tab liner web with a reseal liner web such that said pull tab is compressed therebetween; punching out into a closure said combined seals. Additionally, the present invention comprises an apparatus for manufacturing a bonded pull tab over a reseal liner, comprising; a web of reseal liner material; a web of pull tab seal material; a tab forming punch press, said web of pull tab seal material positioned below said punch press, said punch press further having at least one tab forming anvil extending downward therefrom and reciprocating through said web of pull tab seal material and forming at least one pull tab therein; means to fold said at least one pull tab backward against said web of pull tab seal material; a radiant heater to bond said web of pull tab seal material and said web of reseal liner material to form a combined web of material such that said at least one pull tab is compressed between said web of pull tab material and said reseal liner material; and a punch press for cutting out said combined web of material. Finally, the present invention creates a web of bonded pull tab over a reseal liner material, comprising: a layer of pull tab liner material, said material having a pull tab formed therethrough; a layer of reseal liner material; wherein said pull tab is compressed between said layer of pull tab liner material and said layer of reseal liner material. 
     These and other objects and the nature and advantages of the instant invention will be more apparent from the following detailed description of various embodiments of the invention taken in conjunction with the included drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the invention will be had upon reference to the following description in conjunction with the accompanying drawings in which like numerals refer to like parts and wherein: 
     FIG. 1 is a schematic side view of the apparatus for formation of a preformed bonded pull tab over a reseal liner of the present invention; 
     FIG. 2 is a top view of the pull tab liner strip of the present invention; 
     FIG. 3 is a sectional side view of the completed container liner seal of FIG. 1 which is punch-pressed into a closure; 
     FIG. 3A is a sectional side view of FIG. 3 showing the pull tab formed between the pull tab seal and the reseal liner adhered to the closure; 
     FIG. 4 is a close up side view of the tab forming punches shown in FIG. 1; 
     FIG. 5 is a close up of the punch and die shown in FIG. 1 which is utilized to punch the liner material from the liner web into the closures; 
     FIG. 6 is a perspective sectional view of fully formed bonded pull tab over a reseal liner manufactured with the method and apparatus of the present invention; and, 
     FIG. 7 is a cutaway side view of the closure of the present invention having a standard reseal liner attached to the top wall. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to FIG. 1 there is shown an apparatus  10  for manufacturing a preformed bonded pull tab seal over a reseal liner. The apparatus  10  is comprised of a tab forming punch press  20  which acts upon a pull tab web  27  passing therebelow. Tab forming punches  22  are reciprocally actuated by punch press  20  and are diagonally aligned along the width of pull tab web  27 . Tab forming anvils  22  form one or more pull tabs (in this embodiment four) upon each actuation of reciprocating shaft  21 . The pull tab web  27  is aligned for further processing after formation of pull tabs  26  by registration hole punch press  24  which forms registration holes  25 , shown in FIG. 2, in the pull tab web  27 . Registration holes  25 , positioned along the edge of web  27 , are formed in web  27  by the same reciprocating drive system  21  that activates tab forming anvils  22  which forms pull tabs  26  in liner web  27 . Corresponding registration holes  25   a  are also formed in reseal liner  28  by spring punch press  23 . Registration holes  25  and  25   a  aligns holes in both webs of material  27  and  28 . 
     Tab forming anvils  22 , the diagonal positioning of which is more clearly shown in FIG. 2, create pull tabs  26  along a line diagonally across the width of pull tab web  27  in order to more efficiently utilize the surface area of pull tab web  27 . Diagonal formation of the pull tabs  26  is not necessarily required and therefore any positioning of the pull tabs for subsequent processing can be considered with related loss of efficiency of usage for foil web  27 . As shown in FIG. 2, pull tabs  26  are formed on the peripheral edge of the eventual pull tab seal  29 , the position of which is shown in phantom. Registration holes  25  and  25   a  in both webs  27  and  28  insure that pull tabs  26  are properly formed such that subsequent processing, cutting and formation of the bonded pull tab over reseal liner  50  which is placed into the closure  56 , shown in FIG. 5, occurs. Pull tabs  26  are formed prior to joining of the pull tab web  27  and the wax paperboard reseal liner  28 , shown in FIG.  1 . After formation of the pull tabs  26  by the tab forming punches  22 , shown in FIG. 4, tab forming die  19   a  reciprocates to individually fold the pull tabs along the underside of pull tab web  27 . This allows the pull tabs  26  to be folded backwards such that it is compressed between the two layers of material  27 ,  28  inserted into a closure after they are combined. Reseal layer web  28  acts as a reseal liner in the closure for adequate sealing of the container by acting like a gasket in the closure. Therefore, after combination of layers  27 ,  28 , insertion of the pull tab over reseal liner  50  into a closure, bonding of the pull tab seal to the container rim and separation of the two layers of material, the pull tab  26  of seal  29  is upwardly extending and easily accessible by the user as shown in FIG.  6 . Die  19   a  actuates sufficiently to cause the pull tab  26  to be folded backwards along the underside of pull tab seal  29  as shown in FIG. 4 such that continued forward motion of the pull tab web  27  causes full backward folding of the tab  26 . 
     Registration holes  25   a  in the paperboard reseal liner web  28  are formed by a separate punch die  23  which is spring actuated as shown in FIG.  1 . The resulting holes  25   a  in paper board web  28  are larger than the registration holes  25  in the pull tab web  27  to allow proper mating of the two material webs. Alternatively the index holes in both webs could be formed by the same punch die  24  or similarly, the paper board web  28  can be narrower than the pull tab web  27  to not cover the index holes  25  located thereon. In this embodiment however, for precise locations of subsequent punching operations, both webs are provided with alignment or registration holes  25  and  25   a.    
     Turning to FIG. 3A, the bonded pull tab over a reseal liner  50  which is comprised of the pull tab web  27  and wax &amp; paper board web  28  are shown subsequent to bonding. Alternatively, other materials such as plastic foam with an absorbent layer and foil or foam may be used. The pull tabs  26 , formed by pull tab punches  22 , are folded under the pull tab web  27  and compressed between pull tab web  27  and reseal liner web  28 . As displayed in FIG. 3A, the layer of the pull tab seal web  27  is adhered to the rim of the container mouth and the layer of the reseal liner web  28  is sealed to the top wall of the closure  56 . Pull tab  26 , after combining the two layers  27  and  28  of material, insertion into a closure and subsequent separation by bonding of pull tab seal  29  to a container, may be upwardly exposed as is shown in FIG. 6 in order to provide access to the formed pull tab seal  29  or may be lying flat against the top surface of seal  29  at which point it is merely raised up and removed by upward force. 
     Turning to FIG. 3, pull tab web  27  is comprised of three layers of material. The top most layer of material joining to form pull tab web  27  is a layer of bottle compatible plastic  45  which is used to join the surface of the formed pull tab seal  29  to the container or mouth rim of the container  51 . Directly below the bottle compatible plastic layer  45  is a layer of MYLAR®  46  or other bidirectionally strengthened material which forms a substantial portion of the formed pull tab seal  29 , shown in FIG.  2  and FIG.  6 . This bidirectionally strengthened material  46  insures that upon application of a removal force on pull tab  26 , the formed pull tab seal  29  does not tear or rip. Thus, with an upward force applied to pull tab  26 , the entire pull tab seal  29  is removed from the mouth of container  51  separating the melted plastic layer  45  from bottle  51 . The MYLAR layer  46  can alternatively be replaced with a paper based material to form a frangible liner that readily tears rather than removing the liner in a single piece as is suggested in this embodiment. Finally, foil layer  47  is combined in the liner material  50  as a portion of web  27  to transfer heat evenly across the pull tab seal  29  and melt the plastic layer  45  when bonding to the container  51 . This is accomplished through induction heating wherein the resistance of the foil layer  47  caused by an induction field creates sufficient heat to cause the plastic layer  45  to melt and bond with the container  51 . 
     In conjunction with the pull tab web  27 , a mating web of material comprising wax and paperboard  28  is utilized in combination to provide the formed closure reseal liner  54  shown in FIG.  7 . Wax paperboard  28  is comprised of a pulp or other paper material  49  above which is a layer of wax material  48  shown in FIG.  3 . These materials comprise the paperboard web  28 . Above the wax material  48  after joining of the two distinct web layers  27  and  28  is aluminum foil  47  or other metallic structure for the welding step of the pull tab liner  29  to the container. The foil  47  is formed as a part of the pull tab membrane  27  separate from paperboard  28 . As a result, as shown in FIG. 3, the combined bonded pull tab over reseal liner  50  after joining of the wax paperboard material  28  and the pull tab web  27 , is comprised of multiple layers, being: a bottle compatible plastic  45 ; MYLAR or bidirectionally strengthened material  46 ; aluminum foil or other metallic structure  47 ; wax  48 ; and, pulp or paperboard  49 . Below the wax paperboard  49  and immediately prior to insertion into a closure  56 , a glue or other adhesive is applied to the bottom surface of paperboard  49  for adhesion of the reseal liner  54  into the closure  56 . Alternatively, no glue may be needed to hold the liner disc in the closure. The liner may be snap fit into the closure if during assembly the reseal liner disc  56  is forced past the threads of the closure such that it is held in place by friction and the diameter of the reseal liner disc  56  is slightly larger than the closure opening (See FIG.  7 ). 
     As seen by the schematic outline of FIG. 1, after formation of pull tabs  26  in the pull tab web  27 , pull tab  26  is compressed between the two layers consisting of pull tab web  27  and paperboard web  28  before insertion into a closure  56 , as shown in FIG.  3 A. Ultimately after induction welding of the bonded pull tab over reseal liner  50 , which is inserted in the closure  56 , the pull tab seal  29  will be adhered to the rim of container  51  while the reseal liner  54  will be adhered to the interior underside of closure  56 . Upon removal of the closure  56  from container  51 , pull tab  26  and pull tab seal  29  will be exposed as is shown in FIG.  6 . 
     Examining FIG. 3 again, the topmost layer of material as displayed in the figure is bottle compatible plastic  45 . Most containers which the formed pull tab seal  29  is adhered to are comprised of a thermoplastic material and are made through an extrusion or injection molding process. The layer of bottle compatible plastic  45  on the pull tab web  27  allows the formed pull tab seal  29  to be adhered to the container mouth rim after application of an induction field, the resulting heat of which is dispersed along the entire surface of liner  29  by aluminum layer  47 . Once the pull tab web  27  is combined with the reseal liner web  28  and the combined web is placed into the interior of a closure  56 , the induction field mentioned above is applied to the closure after placement onto the container. Such induction field causes resistance to build in the aluminum  47  foil thereby creating an even layer of heat which melts the bottle compatible plastic layer  45  and adheres the pull tab seal  29  to the container mouth rim. 
     Returning to FIG. 4, the pull tab rotary punch press  20  is shown with reciprocating tab forming punches  22  and pull tab web  27  which passes therebelow. Pull tab die  19  provides an aperture for anvil  22  to pass therethrough in order to form the pull tabs  26  in the pull tab web  27  as is shown. Tab forming punches  22 , shown in FIG. 4, contain pointed or sharpened portions  18  for piercing the pull tab web  27  and an opposite edge  17  which has a reduced curvature such that tab  26  upon formation is not severed by edge  17 . Also shown in FIG. 4 is reciprocating punch die posts  19   a  which moves horizontally from left to right as shown in order to fold tabs  26  backwards after cutting. Tab forming punches  22  reciprocates as shown in FIG.  1  and produces one or more tabs, here shown as four pull tab punches in diagonal relationship in order to increase the efficiency and usage of the pull tab web  27 . Pull tab  26 , folded downward and backwards, is fully folded below web  27  upon forward movement of the web  27 . 
     Returning to the schematic of FIG. 1, after formation of pull tabs  26  in the pull tab web  27  and formation of index holes  25   a  in the pulp board web  28 , both webs are pulled through the heating box  40  by the indexing motor drive  30 . An additional drive may be provided after formation of the registration holes to help push the web material forward. Upon entry into the radiant heater box  40 , pull tab web  27  and wax paperboard  28  are joined or bonded together. Heating box  40  is preferably a radiant heater which provides an increased temperature environment of sufficient heat to evenly melt the wax layer  48  adjacent the foil layer  47  thereby bonding the pull tab web with the closure reseal liner web  28  upon hardening of the wax. Upon exiting the heater box  40  the tab liner and pulp bond webs are forcibly pressed together and cooled by contact with the compression rollers  34 ,  35  and  43 ,  41 . 
     As previously indicated, larger registration holes  25   a  are formed in the wax paperboard web  28 . Providing these registration holes  25  and  25   a  in both layers of material  27  and  28 , insures accurate processing by punch press  60  shown in FIG.  1 . Registration holes  25  and  25   a  are optically sensed by optical sensor  58  immediately prior to punch press  60  so that the punch press and particularly the safety seal anvils  52  are properly aligned with the pull tab liner seal locations  29  and the pull tabs  26  which are shown in FIG.  2 . These registration holes  25  and  25   a  are sensed by the optical sensor means  58  which is operably connected to the compression rollers  42  and  43  which feeds the formed bonded pull tab over reseal liner  50  into the punch press  60 . Optical sensing means  58  may be any of a multiple of known sensors such as photo cells, air gap sensors or metallic proximity sensors. 
     Referring now to FIG. 5, a close up is shown of the internal mechanisms of punch press  60  which acts to punch pull tab seal  29  and reseal liner  54  from the combined container liner  50  and place the combined punch material into the interior of the closure  56 . Below die  53  is placed a closure  56  typically formed of plastic material through an injection, extrusion, or compression molding process. As shown in FIG. 5, the closure  56  utilized in the present embodiment is a threaded closure for screwing onto the neck of a container  51 . However, alternate embodiments may incorporate snap fit closures which have a snap fit bead directed inwardly from the closure sidewall in order to hold the closure in place on the container neck. 
     In FIG. 5, closure safety seal anvil  52  operates in a reciprocating motion puncturing the liner web  50  and inserting the formed container liner  29  with a pull tab  26  formed therebetween and forcing the paper board reseal liner  54 , of FIG. 7, into the closure interior. The combined liner strip  50  is guided by the index holes  25  and  25   a  to maintain proper positioning and location within the machinery. Liner web  50  is advanced by stepper motor  30 . Motor  30  is operably connected with optical sensor  38  to control the advancement of web  50  for correct placement of the web under the cutting dies. Indexing the liner web  50  is controlled by index holes  25  and  25   a  to provide proper linear advance of the web  50  so that the formed tabs are accurately placed under the punch anvil  52  and opening in the die  53  such that the tabs are formed properly on the edge of each cut liner circle  29  outlined in FIG.  2 . The anvils  52  may be placed in a diagonal fashion as is shown in FIG. 2 in order to maximize the usage of the liner web  50  and minimizing any wasting of said material. Optical sensing means  38  thereby controls servo rollers  42  and  43  and placement of the liner web  50  by reading the registration holes  25  and  25   a  so that the anvils cut out a bonded pull tab over reseal liner  51  for insertion into the interior of the closure  56 . Additionally, an adhesive material may be placed in the interior top wall  58  of closure  56  such that upon insertion of the liner web  50  after punch press  52  reciprocates through dye  53 , the reseal liner  54  adheres to the interior of closure  56 . 
     As shown in FIG. 6, after insertion of the liner material into closure  56 , the closure may be threadably attached to a container  51  which, after induction welding or application of heat, can separate pull tab seal  29  from the reseal liner  54  thus exposing the pull tab seal  29  upon first removal of closure  56  from container  51 . 
     The foregoing detailed description is given primarily for clearness of understanding and no unnecessary limitations are to be understood therefrom for modifications will become obvious to those skilled in the art upon reading this disclosure and may be made without departing from the spirit of the invention or the scope of the appended claims.