Abstract:
Methods and apparatus for applying labels to products by effecting a complete or partial pre-release of the label from the carrier web are provided. Such initial de-lamination alters the label release value thereby enabling more consistent label application without unduly increasing web tension. Final label de-lamination may be aided using vacuum assist apparatus.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is generally directed toward methods and apparatus for separating labels, or at least a portion thereof, from a carrier web or liner and applying the labels to products. More specifically, the methods and apparatus allow for easy separation of labels having a high initial release value from their carrier web prior to being applied to products.  
         [0003]     2. Description of the Prior Art  
         [0004]     Reel-fed, pressure-sensitive labels generally comprise a laminate of face material, adhesive, release coating, and carrier web wound as a continuous reel. This construction is the means by which individual pressure sensitive labels are printed and converted from master reels into smaller reels suitable for use on common label dispensing systems. The most conventional method by which individual labels are released from the carrier web is by drawing the liner under controlled tension around the tip of a beak or peeler plate. This action induces a separated force, due to the stiffness of the face material, greater than the label adhesive attachment to the silicon substrate encouraging the label to break away from the liner in preparation for application onto its designated product.  
         [0005]     Pressure sensitive labels and liner can be constructed from a variety of materials including paper, synthetic materials, and combinations thereof having varying physical characteristics such as thickness (calliper), elasticity, and stiffness. In addition, different adhesive types and formulations, together with different coat-weights, are employed as best suited to the type of container and environmental conditions. The coat-weight and type of release coating process used to coat the liner can also be varied which will affect the attachment value of the label adhesive. The attachment value is often referred to as the “release value” which is determined using known Finat testing procedures.  
         [0006]     The relationship between these variables has a direct influence on the release value which in turn will affect the dispense characteristics of the label from the carrier web. For any given combination of label, adhesive, and release substrate there should always be a usable band of release values that enable good dispense of the label without the use of excessive web tension or the possibility of the label delaminating from the web prior to intended release. For most combinations of standard label construction, these values are well known giving reliable and consistent label dispensing at the point of application. However, if recommended storage conditions or defective conversion/finishing of the reels take place, then it is possible that the label release may become inconsistent resulting in labels failing to dispense properly or being misapplied to the product.  
         [0007]     Recent developments in the coating and conversion of down gauged or thinner films have necessitated a proportionate reduction in release values to a point where the usable band of consistent release has become extremely narrow with little or no margin. Therefore, any variations in quality, storage conditions, or web tension control have an immediate impact on label dispense consistency. Efforts have been made to reduce the release value on thin films to give consistent dispense without excessive web tension, but cannot be demonstrated to work effectively on thin films below 18 microns. This is especially true for thin films with cavitation or color pigmentation as a part of their construction, such as white polypropylene, or highly flexible thin films such as polyethylene. The situation is worsened when the carrier web has an ultra-smooth surface such as with a PET liner. While it is possible to lessen these effects by increasing the web tension and/or reducing the tip radius of the peeler plate, the likelihood of web stretch or web snap significantly increase and reduce the reliability of label application.  
         [0008]     Therefore, a need exists for a method and apparatus for consistently dispensing labels which would be difficult to consistently dispense by conventional means.  
       SUMMARY OF THE INVENTION  
       [0009]     The present invention overcomes the above difficulties using a system whereby a label is partially or fully pre-released from the carrier web and then re-laminated prior to drawing the web around a peel plate or peel roller thereby effecting final release of the label. By breaking the adhesive attachment, the release value of the label is reduced. Lowering the release value provides improved dispense characteristics without imposing undesirable web tension on labels which would otherwise fail to release at all or dispense inconsistently. The system also provides for the reduction or elimination of unintended label pre-release due to excessively low silicon release values relative to the laminate construction.  
         [0010]     In one aspect, the invention pertains to a method of applying labels to products comprising the steps of: (a) guiding a web comprising a plurality of pre-printed labels along a path; (b) applying a first vacuum to at least one of the labels proximate the leading edge thereof as the web travels along the path; (c) separating at least the leading edge of the label from the web; (d) reapplying the leading edge of the at least one label on the web; and (e) transporting the at least one label to a label application station where the at least one label is applied to a product.  
         [0011]     In another aspect, the invention is directed toward a method of applying labels to products comprising the steps of: (a) guiding a web comprising a plurality of pre-printed labels along a path; (b) stripping at least one of the labels from the web as the web travels along the path; (c) repositioning the at least one label on the web; and (d) directing the web to a label application station where the at least one label is applied to a product.  
         [0012]     In yet another aspect, the invention is directed toward a method of applying labels to products comprising the steps of: (a) guiding a web comprising a plurality of pre-printed labels along a path; (b) applying a vacuum to at least one of the labels proximate at least the leading edge thereof as the web travels along the path, the vacuum applied by a first vacuum belt; (c) stripping the web from the at least one label, the at least one label being adhered to the first vacuum belt; (d) transferring the at least one label from the first vacuum belt to a pitching belt, the pitching belt altering the pitch between the at least one label and at least one other label; and (e) transferring the at least one label from the pitching belt to an application belt which transports the at least one label to a label application station.  
         [0013]     In still another aspect, the invention is directed toward an apparatus for applying labels to products comprising: a continuous web comprising a plurality of pre-printed labels; a first vacuum device for selectively applying a vacuum to at least one of the labels proximate the leading edge thereof and separating at least a portion of the at least one label from the web, the vacuum device further configured to reapply the portion of the at least one label on the web; and a label application station where the at least one label is stripped from the web and applied to a product. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is a schematic view of a label dispensing system wherein individual labels undergo complete pre-release and vacuum assisted stripping from the carrier web.  
         [0015]      FIG. 2  is an alternate embodiment of the label dispensing system illustrated in  FIG. 1 .  
         [0016]      FIG. 3  is a schematic view of a label dispensing system wherein individual labels undergo complete pre-release and re-application to the carrier web prior to application to products.  
         [0017]      FIG. 4  is a diagram of an alternate release mechanism whereby the leading edge of a label is contacted with suction supplied by a vacuum drum.  
         [0018]      FIG. 5  depicts the suction separating the leading portion of the label from the carrier web as the vacuum drum rotates and the web continues along a path.  
         [0019]      FIG. 6  depicts the use of positive pressure air to reapply the leading portion of the label to the web.  
         [0020]      FIG. 7  is a schematic view of a label dispensing system including apparatus for pitching the labels prior to being applied to products.  
         [0021]      FIG. 8  is a top view of the label dispensing system of  FIG. 7 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]     The following description sets forth preferred methods of applying labels to products and apparatus for carrying out the same. It is to be understood, however, that this description is provided by way of illustration and nothing therein should be taken as a limitation upon the overall scope of the invention.  
         [0023]     Turning now to  FIG. 1 , a label application system  10  is shown that includes a label pre-release station  12  and a label application station  14 . A reel  16  comprising a liner web  18  having a plurality of pressure sensitive labels  20  disposed thereon is provided. Preferably, labels  20  are preprinted so that reel  16  is simply changed out from time to time. However, it is within the scope of the present invention for reel  16  to be replaced with an on-demand label making system such as that disclosed in U.S. Pat. No. 6,863,756, incorporated by reference herein.  
         [0024]     Preferably, the labels used in conjunction with the present invention have a thickness of between about 0.1-3 mils, more preferably between about 0.1-2 mils, and most preferably between about 0.2-1 mils. Preferred labels also comprise release values of at least 15 grams, more preferably between about 15.5-30 grams, and most preferably between about 16-25 grams, as determined by Finat testing procedures.  
         [0025]     Web  18  is guided along a path indicated by the arrows. Initially, web  18  passes by sensor  22 , preferably an optical scanner, which senses the position of individual labels  20  on web  18 . Web  18  is guided between nip roller  24  and a first vacuum drum  26 . Vacuum drum  26  includes a plurality of vacuum apertures  28  through which the vacuum is primarily directed. Vacuum drum  26  is preferably servo controlled using the output from sensor  22 . Sensor  22  detects the leading edge of a particular label  20  so that by the time label  20  reaches vacuum drum  26 , aperture  28  is in position to apply suction to the label proximate the leading edge thereof. Preferably, the vacuum is engaged on the leading edge of the label.  
         [0026]     The strength of the vacuum is such that as vacuum drum  26  rotates in a counterclockwise direction, label  20  is completely stripped from web  18 . Web  18  continues around roller  30  and is guided toward nip  32  which is formed by vacuum drum  26  and nip roller  34 . At nip  32 , label  20  is re-laminated to web  18  and the suction force by vacuum drum  26  proximate the leading edge of label  20  is subsequently released. As label  20  passes through nip  32 , the remaining portion of label  20  is re-attached to web  18 .  
         [0027]     Web  18  is then directed toward label application station  14 . Belt  36  which is entrained around nip roller  34  and peel roller  38  assists in guiding web  18  toward nip  40  formed by vacuum drum  42  and peel roller  38 . At nip  40 , a vacuum is applied to label  20  proximate the leading edge thereof so that the label adheres to vacuum belt  44  as web  18  is directed around peel roller  38 . Web  18  is then taken up on waste roll  46 . Label  20  continues along vacuum belt  44  and passes sensor  48 , preferably an optical sensor, which is used to coordinate the pitching of labels  20  to match the pitch of incoming products  50 . The rotation of vacuum belt  44 , vacuum drum  42 , and application roller  52  is preferably servo controlled so that the pitch between labels  20  may be adjusted as needed. Finally, label  20  is applied to product  50  with the aid of application roller  52 .  
         [0028]     The system depicted in  FIG. 2  operates in a substantially similar manner to the system shown in  FIG. 1  with the exception that nip roller  34 , belt  36 , and peel roller  38  have been replaced with peel plate  54 . All other features remain essentially unchanged from  FIG. 1  and have been labeled with the same reference numerals. In operation, after labels  20  have been re-laminated to web  18  at nip  32 , web  18  is directed toward nip  40  where vacuum drum  42  applies suction to label  20  proximate the leading edge thereof and web  18  is directed around peel plate  54  thereby stripping web  18  from labels  20 .  
         [0029]      FIG. 3  depicts an alternate embodiment according to the present invention. Label pre-release station  12  is identical to that shown in  FIG. 2 . All corresponding elements are marked with the same reference numerals. However,  FIG. 3  does not depict a corresponding label application station. Rather, labels  20  are directly applied to products  50  as web  18  is directed around peel plate  54 . The release values of the particular labels  20  used with this system have been sufficiently decreased by the pre-release operation so that any further vacuum assist in stripping web  18  from labels  20  is unnecessary.  
         [0030]      FIGS. 4-6  depict a further pre-release configuration  56  wherein labels  58  are only partially delaminated from carrier web  60 . Beginning with  FIG. 4 , label  58  approaches vacuum drum  62  at which time a vacuum is drawn through aperture  64  thereby adhering the leading portion of label  58  to vacuum drum  62 . At the same time, a vacuum former  66  is employed to maintain suction on web  60 . As web  60  advances ( FIG. 5 ), vacuum drum  62  rotates in a counterclockwise manner thereby separating the leading portion of label  58  from web  60 . Web  60  remains adhered to vacuum former  66  thereby ensuring this separation. Preferably, at least about 5% of label  58  is separated from web  60 , more preferably up to about 50% of label  58  is separated, even more preferably between about 5-50% of label  58  is separated, and most preferably between about 10-20% of label  58  is separated. An important distinction of this embodiment over those described above is that less than all of the label is delaminated from the carrier web.  
         [0031]     As shown in  FIG. 6 , after at least a portion of label  58  is separated from web  60 , the vacuum in aperture  64  is shut off and a burst of positive pressure air is passed there through to blow the separated portion of label  58  back down onto web  60 . Web  60  then continues on toward a label application station such as any of those described previously herein.  
         [0032]      FIG. 7  depicts yet another embodiment of the present invention that employs vacuum assist in order to delaminate labels from a carrier web. In addition,  FIG. 7  illustrates a preferred label pitching assembly  68  whereby the pitch between labels is adjusted to match the pitch of the products to which the labels are to be applied. A carrier web  70  having a plurality of labels  72  positioned thereon is supplied to a label release station  74 . Web  70  is drawn between roller  76  and a vacuum belt assembly  78 . As labels  72  are contacted with vacuum belt assembly  78 , suction supplied from vacuum former  80  adheres labels  72  to assembly  78 . The force with which labels  72  are adhered to assembly  78  is greater than the release value of the labels from web  70 . Therefore, as web  70  is drawn around roller  76 , labels  72  are stripped from web  70 .  
         [0033]     Next, labels  72  are transferred to a pitching belt assembly  82  wherein the pitch or spacing between successive labels  72  is adjusted to match the pitch of products  84 . In order to accomplish this pitching, pitching belt assembly  82  operates at a different speed from vacuum belt assembly  78 . As labels  72  are likely to be closely positioned on web  70 , the pitch between labels will likely need to be adjusted upward. Therefore, it is preferably that pitching belt assembly  82  operates at a faster speed than vacuum belt assembly  78 . As with vacuum belt assembly  78 , labels  72  remain adhered to pitching belt assembly  82  by drawing a vacuum through former  86 . Finally, labels  72  are transferred to a label application belt assembly  88  for application to individual products  84 .  
         [0034]      FIG. 8  is a top view of the apparatus shown in  FIG. 7 . Vacuum belt assembly  78  comprises five individual belts  90  entrained around rollers  92 ,  94 , and  96 . Power to roller  92  may be supplied by a motor connected to shaft  98 . Labels  72  are subsequently transferred to pitching belt assembly  82  which comprises four belts  100  entrained around rollers  94 ,  102 , and  104 . Vacuum belt assembly  78  and pitching belt assembly  82  share roller  94  in common. However, the belts on each assembly rotate at a different speed. Therefore, roller  94  preferably comprises a plurality of independently rotatable pulleys  106  mounted on shaft  108 . Next, labels  72  are transferred to label application belt assembly  88  which comprises five belts  110  entrained around rollers  102  and  112 . In order to maintain the pitch between labels  72  established by pitching belt assembly  82 , application belt assembly  88  operates at the same speed as pitching belt assembly  82 . Therefore, even though belts  100  and  110  are arranged in an alternating fashion on roller  102 , roller  102  need not comprise independently rotatable pulleys as does roller  94 . In fact, pitching belt assembly  82  and application belt assembly  88  may be powered by the same motor located on either of shafts  114  or  116 .