Patent Publication Number: US-2003224151-A1

Title: Direct thermal printable pull-aparts

Description:
RELATED APPLICATIONS  
     [0001] This is a continuation-in-part of pending U.S. application Ser. No. 09/899,313, filed on Jul. 5, 2001, and entitled Direct Thermal Printable Pull Tabs, which application is hereby incorporated by reference. 
    
    
     
       TECHNICAL FIELD  
       [0002] Pull-aparts, also referred to variously as tear-aparts, tear-opens, break-aparts, break-opens, crack-opens, pull tabs, rip-offs, jar tickets, and pickle cards, contain information concealed between layers of a laminate. Direct thermal printing is used in accordance with this invention to print the concealed information beneath one or more obscuring layers of the laminate.  
       BACKGROUND  
       [0003] Pull-aparts are printed with concealed information that is revealed upon disassembly of the pull-apart. Typically, the information is concealed by being blocked from view between two substrates that are bonded together. However, the bonding is patterned or otherwise limited to permit the two bonded substrates to be separated (e.g., pulled apart) in a manner that reveals the information concealed between them while permanently evidencing their separation. Such pull-aparts are used for a variety of purposes such as game pieces, promotional articles, and report forms.  
       [0004] The game pieces, which are often referred to as “pull tabs”, generally contain two layers of paper. The game results are printed on a base layer and are temporarily obscured by a cover layer. Perforations in the cover layer form removable tabs, which can be peeled away to reveal the game results through so-formed windows in the cover layer.  
       [0005] Ordinarily, the pull-tab game pieces are manufactured along high-speed in-line presses. In-line printing is applied to both the base layer and the cover layer to provide information and images for promoting and playing the game. A front surface of the base layer generally contains promotional and instructional information concerning game play. A back surface of the base layer contains the game results. Digital printing technology is used for serialization and for in-line printing of the results. Less expensive rotary transfer printing technologies are used for repeating patterns. The base layer and the cover layer are laminated together, and perforations are cut through the cover layer to form the tabs that can be peeled back to reveal the game results.  
       [0006] The preprinted game pieces require odds, prizes, and other details of game play and promotion be determined well in advance of play. This limits possibilities for user interaction with game-piece dispensing machines. Any desired change in the ticket price, level of risk, or rules of play requires different pre-printed game pieces. Sometimes, both the number and amounts of the winnings are known for prepackaged sets of game pieces. Early winnings can discourage further sales, because the remaining prizes are known to be diminished.  
       [0007] In addition, the preprinted game pieces require a high standard of security to prevent winning game pieces from being discovered prior to sale. For example, the results must remain hidden from sight by being completely obscured between two substrates. Any tampering of the substrates must be clearly evident. Control over the handling, packaging, and distribution of the pull-tab game pieces is required to guard against more sophisticated breeches of security.  
       [0008] Similar types of games have been developed for play on machines that print the game results locally prior to dispensing the game pieces. The game pieces are printed and dispensed on demand. Odds tables are stored within the machines, allowing for the calculation of odds and scale of winnings for different games and game piece prices. The results of any particular play are not known until the purchased game pieces are printed and dispensed.  
       [0009] Locally printed game pieces are provided in the same basic format, but the base layer is made with micro-encapsulated ink, which is often referred to as “carbonless paper”. An impact printer used without a ribbon forms images in the base layer through the cover layer. The pattern of impacts is apparent in the cover layer, which can detract from the anticipatory nature of the game by revealing the results before the game piece is opened.  
       [0010] However, the results are not known prior to the impact printing of the game piece, so the integrity of the game itself to fairly return results is not affected. The security requirements of pull-tab game pieces for protecting results prior to opening individual game pieces is considerably less if the game piece results are printed at the point of sale, since the results are not determined until a sale is made.  
       [0011] The gaming machines capable of locally printing results for pull-tab game pieces also benefit from their similarity to gaming machines used for traditional gambling purposes. However, pull-tab game pieces are legal in more jurisdictions.  
       [0012] Although on-demand printed pull-tab game pieces have many advantages over pre-printed pull-tab game pieces, impact printing of the game pieces poses problems that detract from the acceptance of the on-demand printed game pieces. In addition to forming an impression of the game results in the surface of the game pieces, which can detract from game play, impact printing is noisy, generates paper dust, and requires considerable maintenance. Costs associated with maintaining remote machines with impact printers can be prohibitively high.  
       SUMMARY OF INVENTION  
       [0013] Our invention provides an improved construction for on-demand printed pull-aparts for supporting the direct thermal printing of concealed information. The new construction features a direct thermal imaging layer that is located beneath an obscuring layer of a laminate. Images can be formed in the thermal imaging layer through the obscuring layer so that concealed information can be printed on demand after the laminate is fully assembled. The pull-aparts can be supplied as media for such purposes as game pieces, promotional articles, and report forms all capable of receiving information on demand that remains concealed until the pull-aparts are individually opened.  
       [0014] An exemplary pull-apart according to our invention includes a base substrate that is at least partially transparent. A thermosensitive imaging layer overlays a front surface of the base substrate, and an opaque layer covers the thermosensitive imaging layer. Bonded to a back surface of the base substrate is a cover substrate. The base substrate and the cover substrate are at least partially separable for exposing a view of the thermosensitive imaging layer through the back surface of the base substrate. The opaque coating on the front surface of the base substrate transmits concentrations of heat required to form thermal images in the thermosensitive imaging layer from a thermal print head. However, the opaque coating at least partly obscures a view of the thermal images formed in the thermosensitive imaging layer from the front side of the base layer. When the substrates are separated, the opaque coating visually contrasts with the thermal images revealed in the thermosensitive imaging layer as a background against which the thermal images can be distinguished through the back surface of the base layer.  
       [0015] A tab is preferably formed in one of the substrates, and the tab is at least partially retractable with respect to the other of the substrates for exposing the view of the thermosensitive imaging layer through the base substrate. The tab is temporarily bonded to the other of the substrates, and a remaining portion of the one substrate is permanently bonded to the other substrate.  
       [0016] The base substrate is preferably a transparent or translucent film. The opaque coating is preferably an ink, such as an ink printable along an in-line press. The ink&#39;s color should differ from the color of thermal images formed in the thermosensitive imaging layer to provide the desired contrast. To further obscure the thermal images formed in the thermosensitive layer, additional coatings, preferably inks, can be applied over the opaque coating. For example, a confusion pattern having a color matching the color of the thermal images can be printed over the opaque coating.  
       [0017] The removable tab can be formed in a variety of ways. For example, the tab can be formed by a die-cut pattern of perforations in the cover substrate. A permanent adhesive responsible for bonding the cover substrate to the base substrate can be patterned to avoid areas of overlap between the tab and the base substrate. Alternatively, the tab can be more completely cut out of the cover and held in place by a temporary adhesive (e.g., a fugitive adhesive or a dry release adhesive). Part of the cut-out tab is preferably permanently bonded to the base substrate or attached to the remaining cover substrate to avoid producing separate pieces of scrap.  
       [0018] Instead of forming the removable tab in the cover substrate, the removable tab could be formed in the base substrate. When retracted, the thermal images appear in the back of the retracted tab. Such tabs can be completely removed for collection, redemption, or other subsequent use, or can remain attached to the cover substrate to reduce instances of scrap. The tabs can be defined in all or just part of the cover or base substrates. For example, single or multiple tabs can be formed as limited parts of either substrate, or either substrate can be fashioned entirely as a single tab.  
       [0019] Another exemplary pull-apart according to our invention also includes a base substrate that is at least partially transparent. However, instead of supporting a thermosensitive imaging layer on the front surface of the base substrate, the thermosensitive imaging layer is supported on a back surface of a thermally transmissive substrate, which is bonded to the front surface of the base substrate. The thermosensitive imaging layer is oriented adjacent to the front surface of the base substrate. The thermally transmissive substrate is at least partially opaque or rendered opaque by the thermosensitive imaging layer itself or an additional coating applied to a front surface of the thermally transmissive substrate. A retractable tab is mounted on the back surface of the base substrate overlying a region of the thermosensitive imaging layer intended for direct thermal printing through the thermally transmissive substrate. Opaque regions of the thermally transmissive substrate and the retractable tab obscure views of the direct thermal printable region of the thermosensitive imaging layer from both sides of the base substrate.  
       [0020] Retracting the tab allows the printable region to be viewed through the base substrate. Similar to the opaque layer of the previous example, the thermally transmissive substrate together with any immediate coatings or colorings provides contrast for thermal images formed in the thermosensitive imaging layer by direct thermal printing. The thermally transmissive substrate can be made of transmissive materials such as thin paper or film, which are preferably made in a color that contrasts with the thermal images formed in the thermosensitive imaging layer. Coatings, including ink coatings, can be added to provide more color. A confusion pattern or other printing can be added in place of or in addition to the coatings to provide for further obscuring the thermal images viewed from the front surface of the base substrate.  
       [0021] The tab can occupy an entire cover substrate or the tab can be one of one or more tabs that are formed within limited parts of the cover substrate. Alternatively, the tab could be formed as a part or all of the combined base and the thermally transmissive substrates. Upon retraction, the thermal images would appear in the back of the tab. The cover substrate would function to obscure the thermal images until the tab is retracted for separating the combined base and the thermally transmissive substrates from the cover substrate.  
       [0022] Yet another exemplary pull-apart includes a thermally transmissive substrate having front and back surfaces with a thermosensitive imaging layer supported on the back surface of the thermally transmissive substrate. A cover substrate is bonded to the back surface of the thermally transmissive substrate. A tab formed in the cover substrate overlaps a region of the thermosensitive imaging layer where thermal images can be formed through the thermally transmissive substrate by direct thermal printing. The thermally transmissive substrate is rendered opaque for obscuring view of the thermal images through the front surface of the thermally transmissive substrate. The tab is retractable from a remaining portion of the cover substrate for viewing the thermal images in the thermosensitive imaging layer.  
       [0023] Preferably, the remaining portion of the cover substrate is permanently bonded to the thermally transmissive substrate, and the tab is temporarily bonded to the thermally transmissive substrate. The remaining portion of the cover substrate can be arranged in a closed shape that frames a window surrounding the tab. The closed shape of the remaining portion of the cover substrate provides intrinsic support for retracting the tab and enables the thermally transmissive substrate to be optimized for thermal conductivity. For example, the thermally transmissive substrate can be made from a film that is less than ten microns thick.  
       [0024] Retraction of the tab opens the window through the cover substrate, which window is at least partially framed by the remaining portion of the cover substrate. The thermally transmissive substrate can itself be made opaque or an opaque coating can be applied to the thermally transmissive substrate for (a) obscuring the view of the thermal images through the front surface of the thermally transmissive substrate and (b) providing contrast for viewing the thermal images through the window formed in the cover substrate. Patterns can be printed on the front surface of the thermally transmissive substrate or on either surface of the cover substrate to further obscure the view of the thermal images until the tab is retracted. 
     
    
    
     DRAWINGS  
     [0025]FIG. 1 is a broken-away front view of a succession of pull-tab game pieces.  
     [0026]FIG. 2 is a broken-away back view of a succession of pull-tab game pieces.  
     [0027]FIG. 3 is an exaggerated thickness cross-sectional view of one of the pull-tab game pieces taken along line  3 - 3  of FIG. 2.  
     [0028]FIG. 4 is cross-sectional view similar to FIG. 3 of an alternative game piece.  
     [0029]FIG. 5 is a back view of an individual pull-away game piece.  
     [0030]FIG. 6 is a cross-sectional view of the individual game piece taken along line  6 - 6  of FIG. 5.  
     [0031]FIG. 7 is a front view of an individual promotional article showing a retracted tab.  
     [0032]FIG. 8 is a cross-sectional view of the individual promotional article of FIG. 7 with the tab still in place. 
    
    
     DETAILED DESCRIPTION  
     [0033] Pull-aparts can be used for a variety of purposes where printed information is intended to be concealed from view until revealed by separating layers of a laminate. These purposes include game pieces, promotional articles, and report forms. The pull-apart game pieces themselves can be used for a variety of purposes including low-stakes wagering, fundraising, and advertising. Other purposes include use as an alternative to scratch-off latex games, which can be messy. Direct thermal printing of such game pieces at point of sale or distribution to determine winnings is expected to provide heightened security over game pieces with preprinted results while providing a construction that still allows for the deferred revelation of the results by removing or otherwise retracting a tab.  
     [0034] The pull-apart promotional articles provide for distributing coupons or product offerings in an interactive format. The pull-apart report forms provide for the controlled distribution of confidential, proprietary, classified, restricted, or personal information, particularly to targeted individuals. For example, information such as test scores, lab results, banking codes, shipping data, and prize winning announcements can be printed on demand while concealed from view until the pull-aparts are irreversibly opened.  
     [0035] A strip of exemplary pull-aparts in the form of game pieces  10  is depicted in FIGS.  1 - 3 . As shown particularly in FIG. 3, the pull-apart game pieces  10  are an assembly of two substrates, base substrate  12  and cover substrate  22 . The base substrate  12  is an at least partially transparent (e.g., translucent) paper or film having a front surface  14  supporting a thermosensitive imaging layer  18 . Thermal images  20  (e.g., game results) formed in the thermosensitive imaging layer  18  on the front surface  14  of the base substrate  12  are visible through a back surface  16  of the base substrate  12 .  
     [0036] The base substrate  12  and thermosensitive imaging layer  18  are preferably acquired together as a direct thermal printable paper or film. One example is an 81 micron polypropylene film, product number C-100 from Kanzaki Specialty Papers of Ware, Mass., coated with an ultra-high sensitivity thermosensitive coating for reacting with heat to form black images. Direct thermal papers are available from Appleton Papers Inc. of Appleton, Wis.  
     [0037] The cover substrate  22 , which can also be made of paper or film, has a front surface  24  that is partially bonded to the back surface  16  of the base substrate  12  with a patterned permanent adhesive  28 . One or more layers of printing ink  30  are applied to a back surface  26  of the cover substrate  22 , which are visible in FIG. 2 as printed images on a back surface  36  of the pull-apart game pieces  10 . Either the cover substrate  22  or the layers of printing ink  30 , and preferably both, are opaque to obscure any view of the thermal images  20  through the back surface  36  of the pull-apart game pieces  10 .  
     [0038] Also shown in FIG. 2 as well as in FIG. 3 are patterns of perforations  32 , which partially surround gaps in the patterned permanent adhesive  28 . The patterns of perforations  32  are cut through both the layers of printing ink  30  and the cover substrate  22  to form retractable tabs  40  that can be pulled away or otherwise separated from the base substrate  12  forming window frames  42  within which the thermal images  20  can be viewed through the base substrate  12 .  
     [0039] A temporary adhesive  38  such as a clean release or fugitive adhesive can be applied between the retractable tabs  40  and the base substrate  12  to hold the tabs  40  in place and to prevent the formation of air pockets within the pull-aparts  10 . Such air pockets can cause undesirable wrinkling or delaminating, particularly during manufacture. The temporary adhesive  38  forms a weak bond that prevents the formation of air pockets but is easily broken to allow retraction of the tabs  40 . Hot-melt or water-based adhesives can be used for this purpose. However, a combination of a water-based adhesive applied over a layer of release on the back surface of the base substrate  12  is preferred to provide reliable release properties without leaving sticky residue on either the tabs  40  or the base substrate  12 .  
     [0040] One of the retractable tabs  40  is shown in a retracted position in FIG. 2, revealing thermal images  20  in the form of two different star burst patterns within one of the window frames  42  formed in a remaining bonded portion of the cover substrate  22 . The window frames  42  limit the viewing area of the thermosensitive imaging layer  18  to the thermal images  20  immediately beneath the retractable tabs  40  that are pulled apart from the window frames  42 .  
     [0041] To enhance the visibility of the thermal images  20  through the windows  42  while obscuring visibility of the same thermal images  20  from a front surface  34  of the pull-apart game pieces  10  (see FIG. 1), an opaque coating  46  (see FIG. 3) is applied over the thermosensitive imaging layer  18  on the front surface  14  of the base substrate  12 . The opaque coating  46  is preferably a layer of printing ink in a color (e.g., white) that contrasts with the color (e.g., black) of the thermal images  20  to enhance visibility of the thermal images  20  through the back surface  16  of the translucent base substrate  12 . However, the opaque coating  46  impairs transmissions of light to at least partially obscure view of the same thermal images  20  through the front surface  34  of the pull-apart game pieces  10 . One such ink is an opaque UV white sold as product number UFA 90100 by Akzo Nobel of Plymouth, Minn. Other colors are also available.  
     [0042] One or more additional printing layers  48  can be applied over the top of the opaque coating  46  to form printed images on the front surface  34  of pull-apart game pieces  10  or to further obscure the front-side view of the thermal images  20 . The printed layers  48  can contain information for playing or promoting the game or patterns, such as confusion patterns for additionally obscuring the thermal images  20 . However, the opaque coating  46  and printing layers  48  are sufficiently thermally transmissive (e.g., sufficiently thin) to enable the thermal images  20  to be printed by a conventional direct thermal printer through the front surface  34  of the pull-apart game pieces  10 . The required thermal transmissivity requires heat conduction with a minimum of dispersion, which can be accomplished by material thinness or material compositions that preferentially conduct heat in the thickness dimension over other directions that would tend to blur the thermal images  20 .  
     [0043] As shown in FIGS. 1 and 2, the pull-apart game pieces  10  are separated from one another along a continuous strip or web  50  by lines of perforation  52 . The strip  50  of pull-apart game pieces  10  is preferably loaded into a direct thermal printer in a continuous form such as a roll or fan-folded stack. The direct thermal printing through the front surface  34  of the pull-apart game pieces  10  should be mirror reversed to permit the desired image to be viewed from the back surface  36  of the pull-apart game pieces  10 .  
     [0044] Following the direct thermal printing of the thermal images  20  (e.g., game results), the individual pull-apart game pieces  10  are separated in groups of one or more along the lines of perforation  52 . Alternatively, the pull-apart game pieces  10  can be pre-cut or otherwise separated in sheet form prior to being loaded into the direct thermal printer. The printer can also be assembled with a cutting mechanism as an alternative to use of perforations.  
     [0045] The first two drawing figures illustrate three retractable tabs  40  per game piece  10 . However, the number of retractable tabs  40  per game piece  10  can vary considerably from one to six or more. The pattern of perforations  32  preferably leaves some portion of each of the retractable tabs  40  connected to the cover substrate  22  after retraction to reduce instances of scrap. The remaining portions of the retractable tabs  40  preferably remain bonded to the base substrate  12 . Alternatively, the tabs  40  could be cut out along continuous rather than perforated lines and held in place with a clean release or fugitive adhesive. In addition, the cover substrate  22  could be formed as one or more retractable tabs  40  without the surrounding window frames  42 , and a clean release or fugitive adhesive could be applied to hold them in place on the base substrate  12 .  
     [0046] Another exemplary pull-apart game piece  60  shown in FIG. 4 looks and functions similar to the pull-apart game pieces  10  but has a different cross-sectional configuration. The assembly requires three substrates: a base substrate  62 , a cover substrate  72 , and a thermally transmissive substrate  82 . Like the preceding embodiment, the base substrate  62  is an at least partially transparent (e.g., translucent) paper or film.  
     [0047] Also similar to the preceding embodiment, a front surface  74  of the cover substrate  72  is bonded by a patterned adhesive layer  68  to a back surface  66  of the base substrate  62 . One or more layers of printing ink  80  cover the back surface  76  of the cover substrate  72 . Preferably, both the cover substrate  72  and the printed ink layers  80  are opaque. A pattern of perforations  78  formed through the printed layers  80  and the cover substrate  72  form retractable tabs  96  similar to the preceding embodiment.  
     [0048] A back surface  86  of the thermally transmissive substrate  82  supports a thermosensitive imaging layer  88  within which thermal images  90  (e.g., game results) are formed. A permanent adhesive layer  92  bonds the thermally transmissive substrate  82  to a front surface  64  of the base substrate  62 . Preferably, the thermally transmissive substrate  82  is opaque in a color that contrasts with a color of the thermal images  90 . One or more layers of printing ink  94  cover the front surface  84  of the thermally transmissive substrate  82  to further obscure the thermal images  90 . Among the layers of printing ink  94  can be a confusion pattern as well as information associated with the play or promotion of the pull-apart game piece  60 .  
     [0049] The thermally transmissive substrate  82  can be a paper or film, but must be sufficiently thermally transmissive (e.g., having a thickness around ten microns or less) to support the direct thermal printing of the thermal images  90  in the thermosensitive layer  88  through its front surface  84 . The direct thermal printing is preferably accomplished by conventional direct thermal printers that are widely available with standardized units of heat output power. Examples of direct thermal printable films laminated to underlying substrates are described in U.S. Pat. No. 6,124,236, entitled Direct Thermal Printable Film and Laminate, to one of the joint inventors herein, which is hereby incorporated by reference. Thin paper, such as paper referred to as “Bible paper”, can also be used as the thermally transmissive substrate  82 . A thin direct thermal paper is available from Appleton Papers Inc. of Appleton, Wis., under the trade name OPTIMA POS Plus thermal paper and having a target thickness of 0.002 inches or 50 microns. Any thermal insulating layer between the paper substrate and the thermosensitive imaging layer is preferably removed or replaced by a more thermally conductive layer.  
     [0050] The retractable tabs  96  can be pulled apart from remaining portions of the cover substrate  72  along the lines of perforation  78  to reveal the thermal images  90  through the translucent base substrate  62 . The thermally transmissive substrate  82  through which the images  90  are printed preferably provides both contrast for enhancing the view of the images  90  through the base substrate  62  and opacity for obscuring the view of the images  90  through the thermally transmissive substrate  82 .  
     [0051] Instead of supporting the thermosensitive imaging layer  88  on the back surface  86  of the thermally transmissive substrate  82 , the thermosensitive imaging layer  88  could be supported on the front surface  64  of the base substrate  62  similar to the preceding embodiment. However, transmissions of heat from direct thermal printing would be required to conduct through both the thermally transmissive substrate  82  and the adhesive layer  92  that permanently bonds the thermally transmissive substrate  82  to the base substrate  62 .  
     [0052] Another pull-apart game piece  100 , which is depicted in FIGS. 5 and 6 also includes a thermally transmissive substrate  102  having on its back surface  106  a thermosensitive layer  108  that is thermally imageable through its front surface  104  similar to the thermally transmissive substrate  82  of the immediately preceding embodiment. However, instead of mounting the thermally transmissive substrate  102  on a transparent base substrate, the thermally transmissive substrate  102  is mounted directly onto a cover substrate  112 . A patterned permanent adhesive  110  attaches a perimeter of the thermally transmissive substrate  102  to the cover substrate  112 .  
     [0053] Along the perimeter pattern of permanent adhesive  110 , die-cut lines of perforation  114  are formed through the cover substrate  112  to form a retractable tab  116 . Through cuts  115  form an ear of the retractable tab  116  for gripping and retracting the tab  116 . A clean release or fugitive adhesive  118  temporarily attaches the retractable tab  116  to the back surface  106  of the thermally transmissive substrate  102 . The permanent adhesive  110  permanently bonds a remaining portion  122  of the cover substrate  112  to the thermally transmissive substrate  102 . The remaining portion  122  of the cover substrate  112  has a closed shape that frames a window  124  that is opened by retracting the tab  116 . The closed shape of the remaining portion  122  provides a frame for retaining a planar shape for the thermally transmissive substrate  102  as well as an intrinsic support for retracting the tab  116 . The support functions afforded by the closed shape of the remaining portion  122  of the cover substrate  112  enables the thermally transmissive substrate  102  to be optimized for thermal conductivity. For example, the thermally transmissive substrate  102  can be made from a film that is less than ten microns thick.  
     [0054] The thermally transmissive substrate  102  can (as far as its thickness permits) be made opaque. However, an opaque coating  126  can also be applied to the thermally transmissive substrate  102  for obscuring a view of thermal images  128  through the front surface  104  of the thermally transmissive substrate  102  while providing contrast for viewing the thermal images  128  through the window  124  formed in the cover substrate  112 . Patterns  130  can be printed on the front surface  104  of the thermally transmissive substrate  102  or on either surface of the cover substrate  112  to further obscure the view of the thermal images  128 . Retraction of the tab  116  opens the window  124  through the cover substrate  112 , revealing the thermal images  128  printed in the thermosensitive imaging layer  108 .  
     [0055] Alternatively, the cover substrate  112  could be made thermally transmissive, permitting the substrate  102  to be made more substantial. The thermal images  128  would then be printed through the cover substrate  112  and the temporary adhesive  118 . The die cuts  114  could then be made through the more substantial substrate  102  to reveal the thermal images on the back surface of a retracted tab.  
     [0056] An exemplary pull-apart in the form of a promotional article  140  is depicted in FIGS. 7 and 8. The promotional article  140  is built upon two substrates—an at least partially transparent base substrate  142  and a cover substrate  148 . A thermosensitive imaging layer  154  directly overlies a front surface  144  of the base substrate  142 . An opaque coating  156  and a printed pattern  158  cover the thermosensitive imaging layer  154 . Die cuts  160  through the printed pattern  158 , the opaque coating  156 , the thermosensitive imaging layer  154 , and the base substrate  142  define a tab  162  that is partially or completely removable from a surrounding portion  164  of the base substrate  142 . The die cuts can be made in a continuous or discontinuous pattern (e.g., perforations) depending upon the degree or manner in which the tab  162  is required to be attached to the remainder of the pull-apart  140 .  
     [0057] A permanent adhesive layer  166  permanently bonds the surrounding portion  164  of a back surface  146  of the base substrate  142  to a front surface  150  of the cover substrate  148 . A temporary adhesive layer  168  temporarily bonds the tab  142  to the cover substrate. Although shown as a single layer, the temporary adhesive  168  can be composed of multiple layers, such as a combination of adhesive and release layers. In addition, in place of separate permanent and temporary adhesive materials, the same adhesive material could be used to cover the entire back surface  146  of the base substrate  142  together with a layer of release applied only in the region of the tab  162  to provide the desired temporary bond.  
     [0058] Graphic layers  170  and  172  are printed onto the front surface  150  and a back surface  152  of the cover substrate  150 . At least the graphic layer  170  is pre-printed during the assembly of the pull-apart promotional article  140  as a form of a thermally printable medium. Prior to distribution or use, thermal images  174  are thermally printed in the thermosensitive imaging layer  154  through the overlying printed pattern  158  and the opaque coating  156 . The thermal images  174  are concealed by the printed pattern  158  (which can be printed as a confusion pattern) and the opaque coating  156  from the front side  144  of the base substrate and by the cover substrate  148  and its graphic layers  170  and  172  from the back side  146  of the base substrate  142 .  
     [0059] Retraction of the tab  162 , including its complete or partial removal, exposes the thermal images  174  through the back surface  145  of the at least partially transparent base substrate  142 . The opaque layer  156  is preferably printed with an ink of a color that contrasts with a color of the thermal images  174 . In addition, the retraction of the tab  162  reveals the pre-printed graphics  170  on the front surface  150  of the cover substrate  148  through a window  176  bordering the surrounding portion  164  of the base substrate  142 .  
     [0060] Adhesive materials or films that favor the conduction of heat along one orthogonal axis (i.e., an axis corresponding to a thickness dimension) over the remaining two orthogonal axes could be used (for either or both of the adhesive layer  92  and thermally transmissive substrate  82 ) to maintain concentrated transmissions of heat through larger distances. Such materials or arrangements of materials that exhibit uniaxial anisotropic electrically conductive properties having metal particle or fiber alignments are also likely candidates for supporting similar anisotropic thermally conductive properties. Thermagon, Inc. of Cleveland, Ohio, produces a range of thermally conductive dielectric polymers, including T-gon 300 and 400 series paste adhesives, that could be printed (e.g., screen printed) in a dot matrix form to favor heat transfers between adjacent layers with a minimum of lateral thermal diffusion.  
     [0061] The thermal coupling materials or material arrangements exhibiting uniaxial anisotropic thermal conductivity have widespread relevance to imaging thermosensitive materials through overlying layers and larger distances from thermal print heads. Such materials in the form of adhesives can provide for bonding protective layers (e.g., paper or film substrates) over otherwise supported thermosensitive imaging layers. In other forms, such as coatings, the materials themselves can provide protection and other overlying functions. For example, in accordance with the illustrated embodiments, the thermal coupling layer is preferably opaque to obscure the image formed in the thermosensitive layer until the pull-apart is retracted.  
     [0062] Although the pull-apart game pieces  10 ,  60 , and  100  and promotional article  140  and their various substrates are referenced with respect to front and back surfaces, the labels of “front” and “back” are used for convenience of reference only and can be altogether exchanged with one another without any structural implications.  
     [0063] The new pull-aparts  10 ,  60 ,  100 , and  140  can be manufactured along in-line presses for performing sequential operations involving printing, coating, die cutting, laminating, and rolling or stacking. The printing operations for repeating patterns are preferably performed using flexographic printing processes. Digital printing is preferred for printing security codes or other variable information.