Method of protecting security elements from heat degradation during a heat-sealing process

Abstract

A blister pack includes a housing having a plurality of cavities and a cover sealed to the housing and enclosing the cavities. The cover includes a base layer, at least one security element, and a heat protection layer. The heat protection layer includes one of an amorphous polymer and a semi-crystalline polymer.

Claims

1. A multi-layer film, comprising: a base layer made of paper or metallic foil; a security layer with at least one security element directly atop the base layer, wherein the security element is at least one of: an embossed hologram, micro-printed words or images, an embossed pattern, and a security strip; an adhesive layer on the base layer, opposite the security layer and an outermost heat protection layer directly atop the security element; wherein the at least one security element has an uneven upper surface topography, and wherein the heat protection layer conforms to and locks in or secures the uneven upper surface topography of the security element, wherein the heat protection layer is comprised of a semi-crystalline polymer material and is positioned to insulate the at least one security element from heat applied to the outermost heat protection layer during heat sealing of an adhesive layer of the multi-layer film to a blister pack to act as a heat sink for protection of the at least one security element, the polymer material having a T.sub.g of greater than or equal to 85° C.; and wherein the base layer and security layer are coextensive.

2. The multi-layer film of claim 1 wherein the polymer material is PMMA.

3. The multi-layer film of claim 1, wherein the polymer material has a Tg ranging from 85° C. to about 165° C.

4. The multi-layer film of claim 1 wherein the protection layer is applied to the security layer in discrete patches corresponding to the at least one security element.

5. The multi-layer film of claim 1 wherein the protection layer varies in thickness over the security element.

6. The multi-layer film of claim 1 wherein the protection layer is also configured as a primer.

7. The multi-layer film of claim 1 wherein the multi-layer film is applied to a blister pack.

8. The multi-layer film of claim 7 wherein the security element is centered over at least one well of the blister pack.

9. The multi-layer film of claim 7 wherein an activation energy seals the film to the blister pack and wherein the protection layer protects the security element from the activation energy.

10. The multi-layer film of claim 1, wherein the security element is a hologram with an embossed surface and wherein the protection layer conforms to the embossed surface of the hologram.

11. The multi-layer film of claim 1, wherein the security element is a metallized, embossed hologram.

12. The multi-layer film of claim 1, wherein: the heat protection layer varies in thickness and includes at least one thicker area aligned with the at least one security element, and at least one thinner area that is located out of alignment with the at least one security element.

13. A method of forming a multi-layer film comprising: providing a base layer made of paper or metallic foil; forming a security layer with at least one security element directly atop the base layer, wherein the security element is at least one of: an embossed hologram, micro-printed words or images, an embossed pattern, and a security strip; an adhesive layer on the base layer, opposite the security layer and forming a heat protection layer directly atop the security element, wherein the at least one security element has an uneven upper surface topography, and the heat protection layer conforms to and locks in or secures the uneven upper surface topography of the security element, and wherein the heat protection layer comprises a semi-crystalline polymer material and is positioned to insulate the at least one security element from heat applied to the heat protection layer during heat sealing of an adhesive layer of the multi-layer film to a blister pack, the polymer material having a T.sub.g of greater than or equal to 85° C.; and wherein the base layer and security layer are coextensive.

14. The method of claim 13 wherein the security element is a metallized, embossed hologram.

15. The method of claim 13 further comprising: placing the multi-layer film over a blister pack; aligning at least one security element over at least one well of the blister pack; and, applying an activation energy.

16. The method of claim 15 further comprising: applying an additional layer.

17. The method of claim 13, wherein the security layer comprises a polymer material having a T.sub.g ranging from 85° C. to about 165° C.

18. The method of claim 13, wherein the security layer comprises a polymer material having a Tg ranging from 85° C. to about 165° C.

19. A multi-layer film, which is suitable for use in a blister pack, and which comprises: a base layer, a security layer including at least one security element directly atop the base layer, and a heat protection layer, wherein the heat protection layer comprises a first semi-crystalline polymer material arranged in discrete patches within the heat protection layer, and a second semi-crystalline polymer material arranged in discrete patches within the heat protection layer, the first semi-crystalline polymer material having a T.sub.g that is different than a T.sub.g of the second semi-crystalline polymer material, wherein the heat protection layer is positioned to insulate the at least one security element from heat applied to the heat protection layer during heat sealing of an adhesive layer of the multi-layer film to a blister pack, wherein the security element is at least one of: an embossed hologram, micro-printed words or images, an embossed pattern, and a security strip, wherein the at least one security element has an uneven upper surface topography, and the heat protection layer conforms to and locks in or secures the uneven upper surface topography of the security element.

20. The multi-layer film of claim 19, wherein the security layer comprises a semi-crystalline polymer material having a T.sub.g of greater than or equal to 85° C.

21. The multi-layer film of claim 20, wherein the polymer material has a Tg ranging from 85° C. to about 165° C.

22. The multi-layer film of claim 19, wherein the T.sub.g of each of the first semi-crystalline polymer material and the second semi-crystalline polymer material is greater than or equal to 85° C.

23. The multi-layer film of claim 22, wherein the T.sub.g of each of the first semi-crystalline polymer material and the second semi-crystalline polymer material ranges from 85° C. to about 165° C.

24. The multi-layer film of claim 19, wherein both the security layer and the heat protection layer comprise a semi-crystalline polymer material having a T.sub.g of greater than or equal to 85° C.

25. The multi-layer film of claim 24, wherein the polymer material of the heat protection layer and the security layer has a T.sub.g ranging from 85° C. to about 165° C.

26. The multi-layer film of claim 19, wherein both the security layer and the heat protection layer have a thickness ranging from 0.8 to 4.0 microns.

27. The multi-layer film of claim 19, wherein the security element is a metallized, embossed hologram.

28. A multi-layer film, comprising: a base layer made of paper or metallic foil; a plurality of security elements directly atop the base layer, wherein the security elements are embossed holograms having an uneven upper surface topography; and a heat protection layer directly atop the security elements, which conforms to and locks in or secures the uneven upper surface topography of the embossed holograms, wherein the heat protection layer is comprised of a first semi-crystalline polymer material arranged in discrete patches within the heat protection layer, and a second semi-crystalline polymer material arranged in discrete patches within the heat protection layer, the first semi-crystalline polymer material having a T.sub.g that is different from a T.sub.g of the second semi-crystalline polymer material, and wherein the heat protection layer is positioned to insulate the embossed holograms from heat applied to the heat protection layer during heat sealing of an adhesive layer of the multi-layer film to a blister to act as a heat sink for protection of the embossed holograms, the first semi-crystalline polymer material and the second semi-crystalline polymer material each having a T.sub.g of greater than or equal to 85° C.

29. The multi-layer film of claim 28, wherein: the discrete patches of the first semi-crystalline polymer material are aligned with the security elements.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Features and advantages of embodiments of the present invention will become apparent on reading the detailed description below with reference to the drawings, which are illustrative but non-limiting, wherein:

(2) FIG. 1 is a cross-sectional view of an embodiment of a heat resistant multilayer film. FIG. 1A is a cross-sectional view of an embodiment of a heat resistant multilayer film in which a heat resistant coating or protection layer is applied to a security layer in discrete patches corresponding to a number of security elements, while FIG. 1B is a cross-sectional view of an embodiment of a heat resistant multilayer film in which a heat resistant coating or protection layer varies in thickness over a number of security elements.

(3) FIG. 1C is a cross-sectional view of an embodiment of a heat resistant multi-layer film, according to another embodiment of the present invention.

(4) FIG. 2 is a flow chart illustrating a method of making a heat resistant multi-layer film according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) Reference will be made below in detail to exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference characters used throughout the drawings refer to the same or like parts, without duplicative description.

(6) While embodiments disclosed herein are described with respect to heat stable coatings and films used to protect security elements integrated into the lidding material of pharmaceutical blister packs, the present invention is not so limited in this regard. In particular, it is contemplated that the inventive coatings and films may be utilized in any application where heat protection of a deposited or printed element on a substrate is desired including, but not limited to, security papers, product packaging, lidding, and the like.

(7) As used herein, the terms “substantially,” “generally,” and “about” indicate conditions within reasonably achievable manufacturing and assembly tolerances, relative to ideal desired conditions suitable for achieving the functional purpose of a component or assembly.

(8) Moreover, the term “multi-layer film” or “film” refers to a multi-leveled material that usually takes the form of a sheet when assembled. Individual layers may be of uniform material or have multiple materials incorporated into a single layer. An individual layer may also be comprised of sub-layers with individual properties. Materials comprising the various layers may be formed and bound together in any number of orders using any of the various techniques known in the art. Certain layers may be a continuous sheet at time of application, other layers may be formed by discrete deposition (e.g., sprayed on inks or polymers, floating a liquid that then cures, etc.).

(9) The term “primer”, as used herein, refers to a material applied to a layer in order to prepare it for a subsequent step. A primer may also be an individual layer as part of a multi-layer film, part of a layer, or in between layers. In some embodiments a primer material may serve more than one particular function (e.g., to prepare a surface for printing while serving as a protective barrier). Primer material may be formed or deposited on an adjacent surface. In certain embodiments the primer may be a polymer sheet. In certain other embodiments the primer may be sprayed on and cured.

(10) Also, as used herein the term “blister pack” refers to a type of packaging wherein cavities formed in a first material are subsequently sealed using a lidding film. A lidding film may be a multi-layer film or may be composed of a single material.

(11) Also, as used herein the term “security element” refers to elements designed and/or configured to combat counterfeiting, thus providing assurance to the consumer that products contained in packaging sealed by the film are genuine and unadulterated. In some embodiments the counterfeit-deterrence measure may be a hologram. In some embodiments the counterfeit-deterrence measure may be microprinted words or images that may also be a part of a hologram. In other embodiments an embossed pattern may be imposed over the surface of a layer. In other embodiments a security strip (e.g., a micro-optic security strip) may be embedded in the layer. The above examples may appear alone or in combination with each other and other similar measures. A counterfeit-deterrence measure may be part of a layer or sub-layer with multiple measures alone or in combination appearing as either an individual layer, part of a sub-layer, or in combinations thereof.

(12) As used herein, the term “semi-crystalline” polymer refers to a material comprised of a collection of polymer macromolecule chains having a morphology consisting of crystalline lamellae separated by amorphous regions. Such a material may be in the form of a sheet or otherwise formed or deposited in place as part of a multi-layer film. Alterations to side-chain groups and the presence or absence of plasticizing agents may affect the final structure and distribution of the crystalline lamellae and amorphous regions in the semi-crystalline polymer material. Semi-crystalline polymers are characterized by a T.sub.g at which the semi-crystalline polymer material undergoes a second order transition with a concomitant change in heat capacity. In some embodiments, at or above T.sub.g, significantly more heat may be added to the polymer without a greater rise in temperature. Likewise, “amorphous” polymers have no crystalline lamellae and also undergo a glass transition change at a glass transition temperature T.sub.g.

(13) Turning now to FIG. 1, a multi-layer construct 100 showing use of a heat resistant coating or protection layer 103 according to one embodiment of the present invention, is illustrated. The multi-layer construct 100 includes a base layer/substrate/housing 101, a security layer 102, and the heat resistant protection layer 103. As shown in FIG. 1, the multi-layer construct 100 reflects a blister pack having a plurality of wells 104 for retaining product 105 therein. As will be appreciated, the layers shown in FIG. 1 are not drawn to scale and sizes are exaggerated to better illustrate component parts. Moreover, it will also be appreciated that the product 105 may be anything that can be sealed in such a package. Examples can include: pharmaceuticals, electrical components, and sterilized medical supplies, amongst others.

(14) As will be appreciated by one of ordinary skill, the base layer 101 may be made of any material without departing from the broader aspects of the present invention. Indeed, the base layer 101 may be made of paper of various weights, thicknesses, and surface finishes. In other embodiments base layer 101 may be a metallic foil, likewise of various weights, thicknesses, and surface finishes, or base layer 101 may be a paper/foil laminate. In an embodiment, adhesives (e.g., heat-seal coatings or heat-activated adhesives) may be applied to base layer 101 in order to adhere the base layer 101 onto a surface (e.g., the material of the blister pack). The adhesives may be heat activated, optically activated (e.g., UV light cured); or configured for attachment to blister pack 104 by mechanical means (e.g., “knurled” or textured together; or, flowing and freezing into textured surface crevices).

(15) As also shown in FIG. 1, the security layer 102, which is adhered to layer 101, contains discreet security elements 106 that are imaged, printed or otherwise deposited thereon (e.g., a metalized, embossed holographic structure). The security layer 102 as well as the heat resistant protection layer 103 described below may be formed using one or more essentially colorless polymers including, but not limited to, acrylic, polyester, polypropylene, polyethylene, polyethylene terephthalate, polyvinyl chloride and polyurethane polymers, nitrocellulose, and the like, and combinations thereof. In an exemplary embodiment, the security layer is formed using one or more heat stable amorphous or semi-crystalline polymers (e.g., acrylic, polyester and polyurethane polymers) having a T.sub.g of greater than or equal to about 85° C., such as poly(methyl methacrylate) or PMMA and has a thickness of greater than or equal to 0.8 microns (preferably, from about 0.8 to about 4.0 microns). Such heat stable PMMA materials are available from Sun Chemical Corporation, 35 Waterview Boulevard, Parsippany, N.J. 07054-1285. In other embodiments, the security layer 102, itself, may define a security element. Specifically, security elements 106 do not need to be discreet, and instead may, for example, extend across all or substantially all of the upper surface of security layer 102. As will be readily appreciated by the skilled person, this would obviate the need to register security elements 106 to wells 104. Regardless, and as shown in the embodiment of FIG. 1, the security elements 106, are located above the opening of the wells 104, although one or more security elements 106 may be placed at any location within security layer 102 and with respect to the wells 104, without departing from the broader aspects of the present invention.

(16) Heat resistant protection layer 103, which safeguards the physical integrity and visual appearance of security layer 102, may be transparent, translucent, tinted, or pigmented and may provide additional functionality for security and authentication purposes. For its part, in an exemplary embodiment, the heat resistant protection layer 103, which conforms to the surface topography of the underlying security layer 102 and which has a minimum thickness of about 0.8 microns (preferably, from about 0.8 to about 4.0 microns) is composed of a semi-crystalline polymer material (e.g., acrylic, polyester and polyurethane polymer materials) having a T.sub.g of greater than or equal to about 85° C., preferably having crystalline lamellae separated by amorphous regions. It is an important recognition of the present invention that controlling the ratio, composition, and nature of the crystalline lamellae (e.g., high turned, or tilt-angled), as compared to the amorphous regions, essentially controls the T.sub.g of a particular polymer material. In other embodiments, the heat resistant protection layer 103 is composed of a substantially homogeneous amorphous polymer material with a T.sub.g of greater than or equal to about 85° C.

(17) In use, a plurality of security elements 106 are printed, impregnated or otherwise deposited upon the base layer or substrate of a package, such as the base layer 101 of the blister pack shown in FIG. 1. This combined base layer 101 plus security elements 106 must then be sealed to the material of the blister pack. Typically, this sealing process involves the application of heat, to melt or otherwise cause the material of the base layer 101 to become affixed to the material of the blister pack housing. It will be readily appreciated that it is of utmost importance that the heat-sealing process does not destroy or otherwise deform or degrade the security elements 106, during the sealing process.

(18) By applying heat at a temperature at or below the T.sub.g of the polymer material and above the activation temperature of the adhesive, the layer(s) formed using the polymer material (i.e., the heat resistant protection layer 103 and/or the security layer 102) does not deform and in the case of the protection layer 103, also serves to lock in or secure the fine surface structure of the underlying security layer 102, thus preserving the structure of security elements 106. At temperatures above T.sub.g the heat capacity of the semi-crystalline or amorphous polymer material increases, providing additional thermal protection should any process deviations occur (e.g., unexpected increase in temperature).

(19) It is therefore an important aspect of the present invention that it is possible to protect security elements formed on a substrate from the damaging effects of a heat-sealing operation by using a semi-crystalline or amorphous polymer material having a T.sub.g of greater than or equal to about 85° C. to form at least one of the security layer 102 and the heat resistant protection layer 103, alone. In this manner, the security elements 106 are adequately protected from the heat of the sealing process, all without the need for sophisticated heating dies, having complex architecture and differing areas of heat conductivity, as is currently known and employed in the art.

(20) In some embodiments, the security layer 102 is composed of a semi-crystalline polymer material such as PMMA or an amorphous polymer material, the polymer material having a T.sub.g of greater than or equal to about 85° C. (preferably from about 85 to about 165° C., more preferably from about 120 to about 150° C.). Such a heat stabilized polymer material allows the holographic or other fine-structured imagery of the security elements 106 to remain unaltered or substantially unaltered during a heat-sealing process, thus preserving the optical effect of security elements 106. This same effect may also be achieved by using one or more such polymer materials to form protection layer 103, or by using one or more such polymer materials to form both the protection layer 103 and the security layer 102.

(21) In other embodiments the protection layer 103 is composed of a semi-crystalline polymer such as PMMA or an amorphous polymer material, the polymer material having a T.sub.g of greater than or equal to about 85° C. As an example, a multi-layer construct 100 with a heat resistant protection layer 103 composed of PMMA having a T.sub.g of 165° C. is applied to a blister pack 104 using an application temperature range of 135−160° C. and commonly at a temperature of about 147° C. (dependent upon blister pack material composition, adhesives (if present), and specific multi-layer construct 100 composition). This is lower than the T.sub.g of 165° C. of the PMMA. Indeed, dependent upon other co-polymers, side chain compositions, presence of plasticizers, free volume of the polymer material, etc. PMMA formulations may have a T.sub.g in the range of 85−165° C. Thus, in practice, a protective film (and/or the security layer) may be formed from polymer materials chosen to have a T.sub.g above the application temperature range.

(22) The heat resistant protection layer 103 may further serve and be configured as a primer enabling the deposition of inks or other materials. Thus, in some embodiments, inks may be “overprinted” on top of the protection layer 103. As will also be appreciated, the protection layer 103 may be the final layer in the multi-layer film, or it may be beneath or between one or more layers. In some embodiments, the protection layer 103 may vary in thickness with thicker or thinner areas corresponding to areas needing more or less protection. In some embodiments the protection layer 103 may contain an embossed design that also serves as a counterfeit deterrence measure on its own or as part of security elements 106. With reference to FIG. 1C, in still other embodiments protection layer 103 may contain two or more polymer materials with two or more T.sub.gs. The two or more polymer materials may be in discrete patches 120, 122, or may be continuous and/or contiguous with each other with either blended transitions between polymer materials or defined transitions.

(23) In an embodiment, the heat resistant protection layer 103 may be deposited directly atop the base layer 101 or the security layer 102 (with security elements 106) through the use of a spray applicator or liquid coating. In other embodiments, it is envisioned that the protection layer 103 may be applied using a transfer film and/or a transfer lamination process.

(24) Thus, the heat resistant protection layer 103 serves as a protective brace and/or heat sink. As noted above, the protection layer 103 conforms to the surface topography of the underlying security layer 102 and holds the surface microstructure of the security elements 106 in place, thus protecting the counterfeit-deterrence properties to an extent that the integrity of the security elements 106 will not be compromised (e.g., distort, degrade, break, alter color, alter texture, etc.). In some embodiments, the protection layer 103 may serve in the same capacity against other activation energies, for example, UV light.

(25) Therefore, in those embodiments that use heat as the activation energy, the protection provided by protection layer 103 and/or security layer 102 eliminates the need for specially configuring the heating/sealing plate/platen of the blister pack packaging system. Indeed, the protection layer and/or security layer enables the use of standard, flat, heating plates to seal the lidding film with integrated security elements 106 onto a blister pack without degrading such security elements. The manufacturing process is therefore substantially simplified, rendering it much more cost effective.

(26) Turning now to FIG. 2, a method 200 of manufacturing a multi-layer film 100 having a protection layer 103 is illustrated. In a first step 201, a base layer 101 is provided. In a second step 202, a security layer 102 with a plurality of security elements 106 is formed or deposited on top of a base layer 101. In a third step 203, the protection layer 103 is formed or deposited on top of security layer 102. Optionally, protection layer 103 may also be formed on top of base layer 101, sandwiching anti-counterfeit layer 102 between two protection layers. In an optional fourth step 204, an additional layer of ink or other material may be deposited on top of the protection layer 103.

(27) With further reference to FIG. 2, additional steps may be employed depending on the end use for the film. For example, when using the film as a lidding material for a blister pack, in a fifth step 205, the multi-layer film 100 may be placed over the blister pack. In practice, this may be accomplished by unspooling/unwinding the multi-layer film 100 from a roll and placing it in close proximity to a blister pack sheet 104 with wells 104 containing product 105. As a sixth step 206, the multi-layer film 100 with security elements 106 may be aligned over the blister pack shown in FIG. 1 in such a fashion so that security elements 106 are aligned with wells 104. Finally, an activation energy (heat, UV rays, microwaves, mechanical pressure, etc.), such as heat applied from a heating plate/platen, is applied as a seventh step 207 sealing the multi-layer construct 100 to blister pack.

(28) It is further to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. Additionally, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from its scope.

(29) In contrast to existing systems/methods, the multi-layer film disclosed herein allows for the use of security elements in blister packs and other applications without the need for customized tooling, molds, or manufacturing devices (such as specialized heating plates). This decreases the overhead required to start a manufacturing process and increases the overall utility of a multi-layer film.

(30) Finally, the written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

(31) Since certain changes may be made in the above-described invention, without departing from the spirit and scope of the invention herein involved, it is intended that all of the subject matter of the above description shown in the accompanying drawings shall be interpreted merely as examples illustrating the inventive concept herein and shall not be construed as limiting the invention.