Patent Publication Number: US-6217078-B1

Title: Label sheet

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to laminated label sheets, and, more specifically, to the manufacture thereof. 
     Label sheets are commonly available in various configurations with and without printing thereon. A typical label sheet is a laminate of a paper overlay and an underlying release liner. An adhesive bonds the overlay to the liner in the finished article. 
     In typical use, information is printed atop the overlay, and the overlay is then removed from the liner by being peeled therefrom. The peeled away label has exposed adhesive so that it may be pressed against paper or other object for attachment thereto. A typical release liner is coated over one side with liquid silicone which is thermally cured for providing a low adhesion surface thereatop to which the overlay is temporarily bonded. The adhesive provides a weak bond between the overlay and the silicone liner which sufficiently maintains together the laminate until it is desired to remove the overlay from the liner. 
     More complex label sheets include several labels or decals in the overlay defined by respective perimeter die-cuts therebetween which allow removal of individual labels from the liner. The individual labels may be directly adjacent to each other or there may be an intervening label rim or border which remains attached to the liner after the individual labels are peeled away. 
     A further increase in complexity of the label sheet includes an integral paper form attached to the label portion of the overlay which does not overlie the liner. This type of label sheet may be manufactured using a lap joining method wherein the label and liner laminate is premanufactured and lap joined along an edge thereof to the paper form. In another, integrated, method of manufacture, the entire overlay, including the label and form portions thereof, is separately manufactured in a common sheet and the liner is then bonded below the label portion thereof. 
     These various label sheets nevertheless use a commonly fabricated release liner which is typically manufactured in large rolls with the silicone in liquid form being applied over the entire surface of the liner paper which is then thermally cured. The large roll of release liner is then cut into individual smaller rolls for use in various label sheet applications as required. 
     Since the low adhesion silicone covers the entire front surface of the release liner, only weak adhesive bonds with the paper overlay may be formed therewith. This presents a problem when several individual labels are formed in the overlay. For example, when the label sheet is passed through a laser printer, individual labels may separate from the liner as the adhesive is softened under heat and the sheet is bent tightly around narrow rollers. Not only may the label sheet be damaged during laser printing, but the released portions thereof have exposed adhesive which may adhere the overlay to internal components of the printer causing jamming thereof. Additional adhesive may also be squeezed out from between the labels and liner due to the heat and squeezing in the printer, and may also lead to printer jamming. 
     Furthermore, when an individual label is removed from an adjoining label border, the border portion itself may also separate from the liner, and the exposed adhesive on the border may inadvertently attach the border to other papers which is undesirable. 
     Another problem attributable to this liner construction occurs when the overlay includes a perforation line. Such lines are provided to tear apart portions of the label for various reasons. Since the label necessarily has a weak bond with the liner, tearing the label along the perforations typically breaks this bond and allows the label to slide on the liner and typically experience side tears emanating from the perforation line. 
     Since the liner is typically manufactured in large rolls, cut to size, and used for various applications, it is not practical or even possible to provide printing atop the liner and below the silicone surface. This leaves only the front and back sides of the overlay and the back side of the liner as available surfaces for printing, and therefore decreases the potential efficiency of the label sheet. 
     Accordingly, it is desired to provide an improved label sheet which resolves one or more of these various limitations in conventionally manufactured label sheets. 
     BRIEF SUMMARY OF THE INVENTION 
     A label sheet includes an overlay attached to a liner by an adhesive. The liner includes adjoining relatively low and high adhesion surfaces. And, the adhesive bonds together the overlay and liner at the high adhesion surface and allows separation of the overlay at the low adhesion surface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, in accordance with preferred and exemplary embodiments, together with further objects and advantages thereof, is more particularly described in the following detailed description taken in conjunction with the accompanying drawings in which: 
     FIG. 1 is an isometric view of the front side of a label sheet in accordance with an exemplary embodiment of the present invention. 
     FIG. 2 is an isometric view of the back side of the label sheet illustrated in FIG.  1  and taken along line  2 — 2 . 
     FIG. 3 is a sectional view through a portion of the label sheet illustrated in FIG.  1  and taken along line  3 — 3 . 
     FIG. 4 is an isometric view of the front side of the liner illustrated in FIG.  3  and taken along line  4 — 4 . 
     FIG. 5 is a schematic representation of an exemplary printing machine for separately manufacturing an overlay and liner forming the label sheet illustrated in FIG.  1 . 
     FIG. 6 is a schematic representation of an exemplary laminating machine which bonds together the overlay and liner, adds separation joints therein, and cuts the label sheets to individual size. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Illustrated in FIGS. 1 and 2 is a label sheet or laminate  10  in accordance with an exemplary embodiment of the present invention. The sheet  10  includes a face sheet or overlay  12  which is preferably a single rectangular paper sheet although it may have other composition and configuration as desired. The overlay  12  includes a front or outer side  12   a  and an opposite inner or back side  12   b.    
     The overlay is laminated to an underlying release liner  14  which includes an inner or front side  14   a  which faces the overlay back  12   b , and an opposite outer or back side  14   b . The overlay  12  is illustrated in sectional view in FIG. 3 laminated to the liner  14 , with the liner  14  being shown in isolation in FIG.  4 . 
     In accordance with the present invention, the liner  14  illustrated in the exemplary embodiment in FIG. 4 includes both a relatively low adhesion surface  16  formed, for example, by applying silicone to a selected portion of the liner front  14   a , and a relatively high adhesion surface  14   c  which may simply be the remaining, exposed rim or border portion of the liner front  14   a  after application of the silicone. The liner  14  may be made of any suitable material such as paper, for example, which be locally coated with the silicone as described hereinbelow in a preferred manufacturing method. 
     As shown in FIG. 3, an adhesive  18  is used to permanently bond together the overlay and liner at the high adhesion surface  14   c  and allows peeling separation of the overlay at the low adhesion surface  16 . The adhesive  18  is permanently bonded to the overlay back  12   b  and covers the entire liner front  14   a , and may have any conventional composition to form a weak bond over the low adhesion surface  16  and a substantially permanent bond over the high adhesion surface  14   c . In this way, the overlay is intimately bonded to the liner over the liner&#39;s entire front surface except at the selected low adhesion surfaces  16 . This prevents the unintended separation of the overlay from the liner except at the local regions of the low adhesion surfaces  16 . 
     As shown in FIG. 1, the overlay  12  may include one or more decals or labels  20  having any suitable configuration or shape. The overlay may include one large label laminated over the entire liner  14 , or a plurality of individual labels either directly adjoining each other or separated by a remaining label border or rim  20   a  as shown for example. In the FIG. 1 embodiment, three differently sized labels are framed in the common border  20   a  laminated atop the liner  14  for showing various possible alternative features of the present invention. The individual labels or decals  20  may be blank, or printed with numerals, letters, or graphics. 
     Referring again to FIG. 4, the low adhesion surface defines a patch or spot, also designated  16 , which generally matches the corresponding configurations of the individual labels such as the rectangles illustrated. And, the high adhesion surface  14   c  surrounds the several spots  16  along the entire perimeters thereof. In this configuration, the liner  14  includes a plurality of the spots  16  which correspond with the respective labels  20  for allowing individual removal or peeling of the labels from both the rim  20   a  and the liner  14 . In this way, the individual labels may be easily removed in view of the weak bond between the underlying adhesive thereof and the liner spot  16  therebelow. The label border  20   a  is strongly or permanently bonded to the high adhesion surface defining the liner border  14   c.    
     As shown initially in FIG. 1, the overlay  12  further includes one or more cleaved separation joints, designated by the prefix  22 , which may be conveniently used for separating the overlay therealong. A first form of the separation joint is a conventional die-cut  22   a  which surrounds the individual labels  20  along the perimeters thereof in a substantially continuous cut for allowing easy removal of the individual labels from atop the liner  14 . 
     As shown in FIG. 3, the die-cuts  22   a  are preferably disposed atop the respective silicone spots  16  closely adjoining the liner border  14   c . In this way, individual labels  20  may be peeled away from the liner as illustrated by the partially removed label B in FIG. 1 which separates along the die-cut  22   a , with the surrounding label border  20   a  remaining securely bonded to the underlying liner  14 . This prevents separation of the label border  20   a  and eliminates the problem of exposed adhesive therefrom which could otherwise jam a laser printer for example. Furthermore, the secure bonding of the label border  20   a  to the underlying liner prevents squeeze out of the adhesive when passed through the hot fusion rollers in the laser printer. 
     As initially shown in FIG. 4, the liner  14  may now also include inked printing  24  in any form such as letters, numerals, and graphics atop the liner front  14   a  and below one or more of the several silicone spots  16 . The silicone spots are applied in an extremely thin layer and have a clear or transparent composition for viewing the printing therebelow. As indicated above, it is not possible in the present manufacture of thermally produced silicone release liners to provide printing under the silicone layer. However, in view of the manufacturing process described hereinbelow, printing atop the liner front  14   a  may now be accomplished prior to the application of the silicone spots  16  thereabove. 
     In the preferred embodiment illustrated in FIG. 1 and 2, the overlay  12  and the liner  14  may now also include printing  24  on both front and back sides thereof, including under the silicone spots  16 . The printing becomes visible upon removal of the individual labels and may provide any useful information or promotions thereunder. Since the liner front  14   a  is now available for printing, compression of the entire label sheet  10  may be affected to contain the same amount of information in a reduced size. This reduces both the amount of material required in manufacturing the label sheet  10  as well as reducing its cost. 
     The printing under the silicone spot  16  is extremely difficult to modify because it is protected by the overlying silicone. This printing is therefore secure from adulteration and may be used for various security purposes not otherwise available in conventional label sheets. Furthermore, the printing below the silicone spots  16  is also protected from chemical and mechanical degradation or attack and substantially increases the longevity of the printing thereunder. 
     As shown in FIG. 1, a second form of the separation joint includes a plurality of perforations or micro-perforations  22   b  which are disposed linearly across the label border  20   a , and extend through both the label  20  and the liner  14 , and through the adhesive therebetween. 
     As shown in more detail in FIG. 3, the perforations  22   b  are disposed atop the high adhesion surface of the liner border  14   c  in a path straddling the perforations to define a skip devoid of the silicone. This allows the label and liner to be torn along the perforations  22   b  in a relatively clean tear without separation of the label and liner along the tear. The strong adhesive bond along the perforations  22   b  maintains the integrity of the label/liner joint while permitting the separation along the perforations. This also prevents the inadvertent exposure of adhesive at the torn edges which could inadvertently attach to other papers. 
     As shown in FIGS. 1 and 2, the overlay  12  may also include a form  26  in the exemplary configuration of a paper sheet extending integrally from the label border  20   a . And, the liner  14  underlies solely the labels and border and not the form  26 . In a preferred embodiment, the entire overlay  12  is a single sheet of paper having portions thereof defining the individual labels  20 , the label border  20   a , and the form  26 . The form  26  may have any suitable configuration and may be blank or printed with various information as desired. 
     Also if desired, the overlay may additionally include a third form of the separation joint having another plurality of perforations  22   c  disposed linearly across the form  26  adjacent the label border  20   a  as illustrated in FIGS. 1 and 2. As shown in FIG. 3, the form perforations  22   c  extend solely through the form  26  since the liner  14  terminates short thereof for allowing the form  26  to be separated from the labels and rim as desired. 
     The single label sheet  10  disclosed above combines various improvements thereof for clarity of presentation. The most significant feature of the present invention is the spot application of the silicone which allows construction of label sheets not previously possible. These new constructions eliminate previous limitations in conventional label sheets and offer various improvements in the label sheets. The invention may therefore be used in various applications which may benefit from the spot application of the silicone or any other comparable low adhesion surface composition as desired. The invention may be applied to single label sheets, multiple label sheets, and combined label and form sheets. The improved label sheets may be used in various industries including the retail market, and the pharmaceutical market for multifunction pharmacy scripts. 
     FIGS. 5 and 6 illustrate schematically an improved method of making the label sheets  10  in various configurations. Conventional, commercially available equipment is available for individually manufacturing the overlay  12  and the liner  14 , and then laminating together these components into the final label sheet. 
     FIG. 5 illustrates schematically the relevant components of a suitable printing machine  28  such a flexographic printing machine from the Webtron Company, Fort Lauderdale, Fla., under model designation “1618.” The machine  28  is conventional except for using a conventional printing drum  30  dedicated for spot application of liquid silicone which may be suitably cured using ultraviolet light (UV) or an electron beam (EB). UV/EB cured liquid silicone resins for use as a printing ink are commercially available from Rhodia Inc., Rock Hill, S.C., under the Silcolease® PC-600, PC-680, PC-670, and PC-702 designations. A suitable curing device  32 , such as an ultraviolet light or an electron beam generator is mounted downstream of the silicone printing drum  30  for substantially instantaneously curing the silicone spots  16  as they are applied to a moving continuous web  34  of the liner material unwound from a supply roll  34   a  and rewound upon printing on a takeup roll  34   b.    
     The printing machine  28  may be used in a conventional manner by supplying liquid silicone instead of a typical printing ink on the printing drum  30  for the desired pattern for printing the low adhesion surface spots  16  atop only a portion of the liner  14  for leaving a relatively high adhesion surface or liner border thereon. The printing drum  30  is configured for printing one or more of the liner configurations along the width of the web  34  and repeatedly in a continuous manner along the length of the web as it is moved past the printing drum  30 . 
     The printing machine  28  illustrated in FIG. 5 also includes one or more additional conventional printing drums  36  for sequentially printing ink of one or more colors on both sides of the liner, including atop the liner  14  and below the low adhesion surface spots prior to printing the silicone spots thereon. Both sides of the web may be printed by the drums using conventional turning bars to turn the web to properly face the drums. In this way, a continuous printing process for the silicone spot liners  14  may be effected. 
     Furthermore, the same type of printing machine  28 , without the silicone printing drum  30 , may be used for independently printing both sides of the overlay  12  in a corresponding web  34  configured specifically therefor. Both printing processes and printing machines for the overlay  12  and the liner  14  are otherwise conventional except for the introduction of the silicone printing drum  30  and the curing device  32  cooperating therewith. 
     As shown in FIG. 6, an additional laminating machine  38  is used for laminating or bonding the liners  14  below corresponding ones of the overlays  12  as they are unwound from the corresponding rolls  34   b . The laminating machine  38  may have any conventional configuration such as that used for presently forming the integrated label sheets introduced above in the background section. The adhesive  18  is supplied between the overlay  12  and the liner  14  over both the low and high adhesion surfaces  16 , 14   c . The adhesive  18  is typically a hot melt adhesive which bonds together the overlay and liner after cooling thereof. 
     The laminated overlay and liner are carried sideways through a pair of opposing rollers  40  to a conventional cleaving drum  42  which is configured for cleaving the separation joints  22  in the overlay  12  after the liner  14  is laminated thereto. 
     In the exemplary embodiment of the label sheet illustrated in FIG. 1, multiple labels  20  are defined in the overlay  12  atop the liner  14 . Accordingly, the cleaving drum  42  illustrated in FIG. 6 is configured for cleaving respective ones of the separation joints  22   a,b,c  in the overlay  12  around each of the several silicone spots  16  as well as for the two tear lines at the perforations. Either the same cleaving drum  42  may be used for forming both the die-cuts  22   a  and the perforations  22   b,c , or separate cleaving apparatus may be used therefor. 
     The individual label sheets  10  may then be cut to size using a suitable cutter  44  and stacked in reams, or otherwise packed in rolls as desired. 
     While there have been described herein what are considered to be preferred and exemplary embodiments of the present invention, other modifications of the invention shall be apparent to those skilled in the art from the teachings herein, and it is, therefore, desired to be secured in the appended claims all such modifications as fall within the true spirit and scope of the invention. 
     Accordingly, what is desired to be secured by Letters Patent of the United States is the invention as defined and differentiated in the following claims.