Patent Publication Number: US-2007096457-A1

Title: Articles including removable concealing layers and methods of printing the same

Description:
RELATED APPLICATION  
      This application claims the benefit of U.S. Provisional Application No. 60/733,138, filed Nov. 3, 2005, which is incorporated herein by reference in its entirety. 
    
    
     FIELD OF INVENTION  
      The invention relates generally to printing and printed articles. More particularly, the invention relates to printed articles including removable concealing layers and methods of printing such articles.  
     BACKGROUND OF INVENTION  
      In some applications, it is desirable to conceal some or all of the printing or indicia on an article. The printing is often concealed by an opaque layer, such as a thin foil or ink, that can later be easily removed. The removable concealing layer may be applied as a security feature, such as to conceal a personal identification number (PIN), or as a novelty or combination thereof, such as on a scratch-off game piece. In one known application, removal is easily accomplished by scratching off the thin foil covering. Examples of articles that often include scratch-off concealed areas include gift cards, coupons, lottery tickets, game pieces, telephone calling cards, postcards, and other similar articles.  
      In one particular example, a printed telephone calling card may contain a PIN number to be revealed upon first use after purchase. The PIN number may be covered by a removable opaque concealing layer that can be removed by scratching, abrading, or some other similar process. In general, the removable concealing layer must be substantial enough to withstand handling prior to purchase of the card and a desired time of removal but relatively easy to remove for use when desired.  
      Printing methodologies used to produce articles that include selectively removable concealing areas are known in the industry. Flexography, lithography, inkjet, laser, variable digital, thermal imaging, silk screening, and other printing methodologies can be used to print on a substrate. A removable concealing layer is then applied over some or all of the printed areas. Such concealing layers can be a hot stamp foil, including pigment and metallic foils; opaque inks, including flexographic, lithographic, and silk screen inks; films; covered or coated labels; wax materials; adhesive-type materials; and other suitable concealing layers. Removable concealing layers are often applied by methods such as hot stamping, adhesives, additive printing methodologies, and other suitable methods. The removable concealing layer can be subsequently removed by means of scratching, abrading, and the like. In one example, a clear label coated with a removable opaque ink is applied over a printed area to be concealed. The ink can be easily removed and the printed area revealed, visible through the clear label that remains.  
      The manufacturing methods described above suffer from a number of disadvantages. For example, thermal imaging printing is frequently used in creating printed articles having removable concealed areas. Although thermal imaging printing generally produces high quality results, it is a slow process and output rates are lower when compared to alternative printing methods. Inkjet printing, on the other hand, is a faster, more efficient process, but produces relatively poor print quality compared to thermal imaging.  
      Some types of inkjet printing, particularly drop-on-demand (“DOD”) inkjet printing, produce print quality that is similar to thermal imaging at a high output rate. However, DOD printing produces a firm raised image upon curing. Referring to  FIG. 1 , upon application of a removable concealing layer  10  over DOD printing on a phone card  2 , a raised image  12  is apparent through the opaque layer. The purportedly concealed area remains viewable and/or tactilely discernable and thus is not completely concealed.  
      Accordingly, there remains a need for high quality, efficiently produced printed articles having removable concealing layers that provide sufficient concealment.  
     SUMMARY OF THE INVENTION  
      The invention resolves many of the above-described deficiencies and drawbacks inherent with printing high quality printed articles having removable concealing areas. In particular, one embodiment of the invention is directed to a system and method of printing a substrate according to an inkjet printing methodology, applying a clear doming layer to level a printed area, and applying a removable concealing layer over the clear doming layer and printed area.  
      Various embodiments of the invention disclosed and described herein incorporate inkjet printing methods such as drop-on-demand (“DOD”) printing to create relatively high quality images at a high output rate as compared to other printing techniques. Because the cured DOD printed indicia results in a raised, visually and/or tactilely discernable area, the raised area is subsequently covered by applying a clear material as a doming layer without distorting or degrading the underlying printed indicia. In one embodiment, the doming layer can be applied in a flood or solid area to fill in the raised area. In another embodiment, the doming layer can be applied in a non-solid pattern to sufficiently mask or deceive the underlying indicia such that the indicia are no longer discernable. The doming layer can be applied by various additive printing methodologies, extrusion, or other suitable means. A removable concealing layer, such as a hot stamped foil, is then applied over the optionally cured doming layer and printed indicia. The printed indicia are therefore sufficiently concealed and inconspicuous. Upon use, the removable concealing layer can be removed by scratching, abrading, or other suitable methods of revealing the underlying printed indicia.  
      The above summary of the invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description that follow more particularly exemplify these embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a prior art phone card with discernable printed indicia.  
       FIG. 2  is a perspective view of one side of a printed article according to one embodiment of the invention.  
       FIGS. 3A, 3B , and  3 C are cross-sectional layer diagrams according to embodiments of the invention.  
       FIG. 4  is a block diagram of a printing process according to one embodiment of the invention.  
       FIG. 5  is a flowchart of a method according to one embodiment of the present invention.  
       FIG. 6  is a layer diagram of a lenticular printed article according to one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      The invention includes printed articles with removable concealing areas. The printed articles are of a high print quality and attractive appearance and can be efficiently produced according to methods and printing processes and systems of various embodiments of the invention described herein. The printed articles, methods, and printing processes and systems are described in more detail below with reference where applicable to  FIGS. 1-6 .  
      One side of a printed article including a removable concealing area is shown generally in  FIG. 2 . Printed article  100 , depicted in  FIG. 2  as a phone card, can also comprise a gift card, coupon, lottery ticket, game piece, advertisement, debit card, credit card, postcard, mailer, and virtually any other article or object on which concealed printing is desired. Printed article  100  therefore generally comprises a substrate  102 , printed indicia  104 , and concealed area  112  concealing additional printed indicia. Printed article  100  can be two-sided, including printed indicia  104  on both sides of substrate  102 , although only a single side is shown in  FIG. 2 . Printed article  100  can also optionally comprise a magnetic stripe  110  on either side of substrate  102  for encoding information such as the value of a gift card, identifying information, access privileges, and other suitable information.  
      Other attributes can be added to printed article  100  on either side of substrate  102  as desired, such as bar coding, encrypted bar coding, radio frequency identification (RFID) tags, and other identifiers and indicia. Further, it can be appreciated that certain illustrated features, such as concealed area  112  and magnetic strip  110 , need not be included on the same surface of substrate  102  or can be included on both major surfaces of substrate  102 . Printed article  100  will often include printed indicia  104  on both major surfaces of substrate  102 .  
      Substrate  102  can comprise plastic, laminated plastic, paper, coated paper, laminated paper, laminated synthetic paper, cardstock, foil, and other suitable substrates for printing and can comprise a sheet, web, card, or other form prior to and during printing. Printed indicia  104  can comprise text, numbers, pictures, drawings, symbols, and other indicia that can be printed on a substrate. Printed indicia  104  can comprise curable inks in a variety of colors and effects, such as a metallic appearance in one embodiment, although non-curable inks can be used in other embodiments. To accomplish high quality printing at an efficient output, inkjet printing can be used to apply indicia  104  to substrate  102  in one embodiment. For example, a curable inkjet printing methodology, such as a radiation curable inkjet printing methodology, a UV curable inkjet printing methodology, a drop-on-demand (“DOD”) inkjet printing methodology, or a radiation curable DOD inkjet printing methodology can be used to print indicia  104  on substrate  102  in various embodiments of the invention described in more detail below. Other printing methodologies or a combination of printing methodologies can also be used in other embodiments of the invention.  
      DOD printing methodologies can be used to print all or only part of indicia  104  and any indicia concealed by concealing layer  108 . Referring to  FIG. 1 , the properties of DOD ink generally result in firm raised printed areas  12  on the substrate, particularly after curing. Examples of suitable DOD inks include black, red, blue, and other custom colors of DOD inkjet inks commercially manufactured by Sun Chemical or Graphtech. The appearance of DOD printed areas is therefore of a high quality and attractive appearance but has heretofore been incompatible with hot stamp foil concealment because of the resultant three-dimensional printed area.  
      Referring to  FIGS. 3A, 3B , and  3 C, printed indicia  104  form a plurality of raised areas relative to substrate  102 . To adequately conceal desired indicia  104  on printed article  100 , a filler or doming layer  106  is subsequently applied to substrate  102  over printed indicia  104 . In one embodiment, doming layer  106  creates a level area for subsequent application of removable concealing layer  108 . For example, if the raised areas of printed indicia  104  have a height relative to a surface of substrate  102 , an application of doming layer  106  can be within +/−50 percent of the height of printed indicia  104 , preferably within +/−25 percent of the height of printed indicia  104 , more preferably within +/−10 percent of the height of printed indicia  104 , to adequately conceal printed indicia  104 , maintain an attractive appearance of printed article  100 , and minimize waste of material of doming layer  106 .  
      In another embodiment, doming layer  106  is applied in a pattern to mask or obscure indicia  104  such that indicia  104  is not visually or tactilely discernable. In yet another embodiment, doming layer  106  and removable concealing layer  108  comprise a single layer. In this embodiment, the single layer is sufficiently thick, is applied in an obscuring pattern, or has other properties, such as described in more detail below, to adequately tactilely and/or visually obscure printed indicia  104 .  
      Doming layer  106  can comprise a clear or substantially transparent material that does not distort or itself conceal printed indicia  104 . In some embodiments, doming layer  106  can comprise a clear curable ink applied by an additive printing methodology, such as flexography, inkjet printing, and the like. In other embodiments, doming layer  106  can comprise an extruded film or material that remains clear upon curing. Doming layer  106  can also be semitransparent, opaque, or substantially opaque in other embodiments. In yet another embodiment in which doming layer  106  and removable concealing layer  108  comprise a single layer, the single layer can be colored or tinted and/or can comprise granules, fibers, flakes, particles, and/or other texturizers to obscure printed indicia  104 . Suitable materials for doming layer  106  may include but are not limited to a clear UV silkscreen carrier, a clear UV varnish or coating, a clear aqueous coating, a solvent or water-based clear coating, a radiation curable clear coating, an adhesive, a pressure sensitive adhesive, a radiation curable adhesive, a wax material, and a UV screen matte doming compound commercially manufactured by Rad-Cure.  
      As depicted in  FIG. 3A , doming layer  106  can comprise a continuous layer completely covering printed indicia  104  and filling in any recesses. As depicted in  FIG. 3B , doming layer  106  can also be applied to only fill in the recesses of printed indicia  104 . As depicted in  FIG. 3C , doming layer  106  can also be applied in a regular or irregular pattern to mask or obscure indicia  104  such that indicia  104  is no longer visually or tactilely discernable. Doming layer  106  can be locally applied over only indicia  104  desired to be concealed, although doming layer  106  can also be applied over an entire surface of substrate  102  for a desired effect.  
      Removable concealing layer  108  typically applied over doming layer  106  can comprise an opaque material, such as, for example, a foil, including hot stamp, pigment, and metallic foils; opaque inks, including flexographic, lithographic, and silk screen inks; films; foil or ink coated labels; wax materials; adhesive-type materials; and other suitable opaque materials, to temporarily conceal printed indicia  104  until selective removal. In one embodiment of the invention, removable concealing layer  108  comprises a hot stamp foil that is frictionally removable, such as by scratching or abrading. Removable concealing layer  108  can be of a variety of colors and/or attractive metallic and other finish effects.  
      Removable concealing layer  108  is applied over doming layer  106 , and can be uniformly applied or applied in a pattern or other concealing or obscuring manner. Removable concealing layer  108  can comprise, for example, a hot foil scratch-off material; a metallic or pigment hot foil scratch-off material; a label coated with a scratch-off ink or other material; a UV or radiation cured varnish or coating followed by silkscreen, flexographic, or lithographic ink; extruded inks, adhesives, waxes, or other extruded materials; or radiation cured extruded inks, adhesives, waxes, or other materials. Removable concealing layer  108  can further comprise an opaque ink, flexographic ink, lithographic ink, silk screen ink, film, foil-coated label, ink-coated label, and/or adhesive material that is radiation curable, solvent-based curable, or water-based curable. Removable concealing layer  108  can also be of a solid color, a combination of colors, or some other form.  
      In another embodiment, removable concealing layer  108  comprises a scratch-off foil material applied onto or over one surface of a clear or tinted label. The label can be applied over doming layer  106  by hot stamping, adhering, or other attaching means and remains after the foil layer is removed, allowing the printed indicia  104  to be viewed. In yet another embodiment, the aforementioned label comprises doming layer  106  is applied over printed indicia  104 , and removable concealing layer  108  comprises the scratch-off foil material applied onto or over one surface of the label, as mentioned above.  
      Printed articles  100  can be produced in a continuous in-line process or in a series of batch processes located at the same location or various locations. In one embodiment of the invention, as depicted in  FIG. 4 , concealed printing articles  100  are manufactured in a continuous process  200  comprising a series of in-line stations or manufacturing stages. Prior to process  200 , one or more optional preprocessing or preproduction stages may occur, including printing, cutting, forming, coating, treating, trimming, or any other pre-process desired or required to prepare article  100 , including substrate  102 . Substrate  102  can comprise a continuous web, sheets, or individual articles  100 . In the example embodiment of  FIG. 4 , article  100  comprises individual preformed cards, such as card  100 , fed by a card feeder  202 . In other embodiments, card feeder  202  instead comprises a sheet feeder, web roll handler, or other specialized feeder. Cards  100  are moved through process  200  by a belt, chain, or other suitable transporting means.  
      In one embodiment, cards  100  pass through an optional encoding head  204  which encodes a magnetic strip  110  on cards  100 . Magnetic strip  110  can be pre-applied to cards  100  or, although not depicted in  FIG. 4 , can be applied as part of process  200 . In another embodiment, optional encoding head  204  is omitted for articles  100  not comprising a magnetic strip or for articles including magnetic strips that are encoded outside of process  200 . In yet another embodiment, encoding takes place at a different point within process  200 .  
      Encoding head  204  is followed by a printing station  208 . Printing station  208  comprises an inkjet printing system, such as a DOD inkjet printing station, in one embodiment, although other or additional suitable printing systems can be used in other embodiments. Suitable DOD inkjet printing systems are commercially available from Atlantic Zeizer and CPST, for example. Suitable DOD inkjet heads are commercially available from Graphtech. An ink, such as a radiation or UV curable or other suitable ink, is deposited onto one or both sides of card  100  at printing station  208  to create printed indicia  104 , indicia to be concealed, and other printed content. Cards  100  can optionally include preexisting printed content applied during one or more optional preprocessing stages as previously discussed.  
      Printed indicia  104  can be cured at cure station  210 . Cure station  210  can comprise radiation curing, such as UV, electron beam, gamma radiation, and other suitable radiation curing methods known in the industry. Cure station  210  can comprise more than one curing step of the same type or a combination of radiation or other curing units. In another embodiment of the present invention, printed indicia  104  can be cured by thermal energy such as infrared (IR), heat, and the like at cure station  210 . In yet another embodiment of the present invention, cure station  210  can comprise a combination of radiation and thermal energy curing units.  
      After cure station  210 , printed cards  100  move to doming station  212 . In some embodiments, doming station  212  can comprise an additive printing methodology, such as, for example, flexography, inkjet, and other additive printing methodologies. In other embodiments, doming station  212  is an extrusion process incorporating an extruder and an extrusion die. A thin layer of suitable clear doming material as described above is deposited onto printed card  100  to form doming layer  106  over some or all of card  100 . As previously discussed, doming layer  106  can be a continuous flood layer that fills in or completely covers the underlying printing, or a selectively applied pattern to mask or sufficiently obscure the underlying printing such that the printing is difficult or impossible to distinguish.  
      Doming layer  106  is then cured at cure station  214 . Cure station  214  can comprise more than one curing of the same type or a combination of radiation curing units as described above with reference to cure station  210 .  
      Card  100  then enters stamping station  216 . In one embodiment, stamping station  216  comprises a hot stamp process that utilizes a heated die in combination with pressure to stamp a concealing layer  108 , such as a foil, foil label, and other suitable concealing materials as described above, onto printed card  100  where it is desired to conceal some or all of printed indicia  104 . A suitable hot foil unit is commercially available from Atlantic Zeizer. Stamping station  216  may be followed by an optional cure station (not shown) similar to cure stations  210  and  214  described above.  
      Printed article  100  then moves to optional post-processing step(s)  218 . Post-processing can include one or more cutting, trimming, affixing to a carrier, encoding, coating, sealing, converting, sorting, stacking, and/or packaging, stages, as well as other additional post-processes if desired. Optional post-processing step  218  is typically not in-line with, i.e., on the same machine as, the others steps of process  200 .  
      In various embodiments of the invention, at least one camera verification station can be positioned throughout in-line process  200 . As depicted in  FIG. 4 , optional camera verification stations  206 ,  209 ,  211 ,  213 ,  215 , and  217  are located after encoding head  204 , printing station  208 , curing station  210 , doming station  212 , curing station  214 , and stamping station  216 , respectively. Any combination of optional camera verification stations  206 ,  209 ,  211 ,  213 ,  215 , and  217 , or more or fewer stations, can be placed throughout process  200  to monitor and verify processing and progress within process  200 .  
      In other alternate embodiments of the present invention, a plurality of printing units can be stationed at printing station  208 . For example, a combination of inkjet and/or DOD inkjet printing heads can be used for different colors, different inks, or other applications. In other embodiments, a combination of printing methodologies including or excluding at least one inkjet or DOD inkjet printing head can be used at printing station  208  to print substrate  102 . In another embodiment of the present invention, multiple printing stations  208  and curing stations  210  and combinations thereof can be located throughout process  200 .  
      In embodiments of process  200 , at least 5,000 or more high quality printed articles  100 , such as gift, debit, credit, or phone cards, can be produced in-line per hour. The rate will vary according to the size and production complexity of the printed articles and related variations in process  200 , as can be appreciated by those skilled in the art. The print quality is typically better than ordinary inkjet and comparable with that provided by thermal imaging printing methodologies.  
      Referring to  FIG. 5 , and in one embodiment of a method of the invention, printed article  100  can be manufactured in a continuous in-line process in a series of steps, such as process  200  of  FIG. 4 . In step  300 , a magnetic strip on substrate  102  is encoded. Encoding can also take place at an alternate point in the process. Indicia  104  is then printed on substrate  102  according to a DOD inkjet printing methodology in step  302  and optionally cured at step  304  to created printed indicia  104 . A doming layer  106  is applied over printed indicia  104  in step  306 , and subsequently optionally cured in step  308 . Removable concealing layer  108  is applied over doming layer  106  and printed indicia  104  and optionally cured in step  308  to create concealed printing article  100 .  
      In another embodiment of the invention, printed article  100  comprises a lenticular article  400  including a lenticular lens layer  402  as depicted in  FIG. 6 . Lenticular article  400  can comprise a sheet, card, label, insert, jacket, wrap, cup, cylinder, container, or other item suitable for displaying a lenticular image. Similar to as described above, indicia can be mapped and printed onto some or all of flat surface  401  of lenticular lens layer  402  or onto a substrate layer  404  of lenticular article  400  to create a printed indicia layer  406 . A suitable doming material, label, or layer is then applied to some or all the lens layer  402  of lenticular lens  400  to fill in or cover the valleys  410  between ridges  412  and create doming layer  408 . A removable concealing layer  414 , such as a scratch-off hot stamp foil as described herein above, is applied over some or all of doming layer  408  and to conceal printed indicia layer  406  visible as a lenticulated image through lens layer  402 . Upon scratching or abrading to remove concealing layer  108 , printed indicia layer  406  is visible as a lenticulated image through lenticular lens layer  402 .  
      Printed indicia layer  406  can also be printed directly onto lenticular lens layer  402 . Doming layer  408  can then be applied over printed indicia layer  406  on lenticular lens layer  402 , followed by removable concealing layer  108 . Upon scratching or abrading to remove concealing layer  108 , printed indicia layer  406  is visible on lens layer  402 .  
      Alternatively, printed indicia layer  406  can be applied onto doming layer  408  applied over lenticular lens layer  402 . Upon scratching or abrading to remove concealing layer  108  applied over printed indicia layer  406  on doming layer  408 , printed indicia layer  406  is visible on doming layer  408 . Doming layer  408  can be clear or semitransparent in order to view an underlying lenticulated image, or doming layer  408  can be opaque to obscure any underlying lenticulated image and possibly make viewing of printed indicia layer  406  easier.  
      In yet another embodiment similar to that depicted in  FIG. 6 , indicia is printed on a top surface of lenticular lens  400 , in addition to or instead of on surface  401  or substrate  404 . A filler layer or label is first applied to lens  400  to fill in or cover valleys  410  between ridges  412  to create a printing surface. Indicia is then printed over the filler layer, followed by application of a doming layer or label over the indicia. A removable concealing layer is then applied over the doming layer to cover or obscure the printed indicia.  
      The invention therefore addresses and resolves many of the deficiencies and drawbacks inherent with printing high quality printed articles having removable concealing areas. The invention may be embodied in other specific forms without departing from the essential attributes thereof, therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive.