CONFORMABLE FILMS, LAMINATED STRUCTURES AND RELATED METHODS

Abstract

The disclosure modalities relate to a blister pack having a laminated structure that is heat-sealed to a lacquer layer on cold-formed aluminum foil. The blister pack includes a lid layer comprising cold-formed aluminum foil, a lacquer layer on a sealing surface of the cold-formed aluminum foil, and a laminated structure sealed directly to the lacquer layer. The laminated structure includes a multilayer film and a plurality of cavities formed therethrough. The multilayer film includes a first conformable layer of a thermoplastic material and a sealing layer of a copolyester material. The sealing layer covers the first conformable layer and has an outer surface opposite the first conformable layer. The sealing layer has a crystallinity of 5 to 20% as measured by differential scanning calorimetry (DSC).The outer surface of the sealing layer is sealed directly against the lacquer layer.

Description

CONFORMABLE FILMS, LAMINATED STRUCTURES AND RELATED METHODS Field of invention This specification generally refers to laminated structures having conformable films and, more specifically, to a blister having a laminated structure that is thermo-adhesive to a lacquer layer on cold-formed aluminum foil. Background of the invention Blister packs are well-known for packaging food products, pharmaceuticals, and other industrial goods. They are formed from laminated structures consisting of one or more conformable films. These laminated structures are sealed to a lid layer after the product is placed within the cavities formed in the lid. The lid layer is commonly made from cold-formed aluminum foil, and its sealing surface is coated with a layer of lacquer to improve the bond between the lid layer and the laminated structure. The bonding performance of the lacquer layer on the sealing surface of the lid layer varies widely depending on the nature and composition of the conformable films used in the laminate structure. In some cases, an outer layer of the laminate structure may have an additional coating layer, such as Vinoyl 15 / 45M manufactured by Wacker Polymers, to improve bonding performance. However, such an additional coating layer increases manufacturing complexity and cost, and can result in poor blister performance. In other cases, when the conformable films are made of thermoplastic materials such as uncoated polyethylene terephthalate (PET), biaxially oriented nylon (BON), polypropylene, and similar materials, the laminate structures do not bond well with the lid layer. Brief description of the invention The packaging configurations relate to a blister pack with a laminated structure that is heat-sealed to a lacquer layer on cold-formed aluminum foil. In one configuration, a multilayer film includes a first conformable layer of a thermoplastic material and a sealing layer of a copolyester material. The sealing layer covers the first conformable layer and has an outer surface opposite the first conformable layer. The sealing layer has a crystallinity of 5 to 20%, measured by differential scanning calorimetry (DSC), a well-known technique for those skilled in the art. In another embodiment, a blister pack for packaging a product is disclosed. The blister pack includes a lid layer comprising cold-formed aluminum foil, a lacquer layer on a sealing surface of the cold-formed aluminum foil, and a laminated structure sealed directly to the lacquer layer. The laminated structure includes a multilayer film and a plurality of cavities formed therethrough. The multilayer film includes a first conformable layer of a thermoplastic material and a sealing layer of a copolyester material. The sealing layer covers the first conformable layer and has an outer surface opposite the first conformable layer. The sealing layer has a crystallinity of 5 to 20% as measured by differential scanning calorimetry (DSC). The outer surface of the sealing layer is sealed directly against the lacquer layer of the aluminum foil lid. In yet another embodiment, a method for preparing a blister pack is disclosed. The method includes the step of laminating a lid layer and a multilayer laminated structure under pressure to form the blister. The lid layer comprises cold-formed aluminum foil with a lacquer coating on its sealing surface. The laminated structure comprises a multilayer film having a first conformable layer of a thermoplastic material and a sealing layer of a copolyester material. The sealing layer covers the first conformable layer and has an outer surface opposite the first conformable layer. The sealing layer has a crystallinity of 5 to 20%, as measured by differential scanning calorimetry (DSC). During the lamination step, the outer surface of the sealing layer comes into direct contact with the lacquer coating of the lid. These and other additional features provided by the modalities described in this document will be more fully understood by considering the following detailed description, along with the drawings. Brief description of the drawings The embodiments shown in the drawings are illustrative and exemplary in nature and are not intended to limit the scope defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where similar structures are indicated by similar reference numbers and in which: Figures 1A, 1B and 1C are schematic diagrams of three exemplary multilayer films having conformable film layers, according to one or more of the modalities shown and described herein; Figure 2 is a schematic diagram of a lamination process for forming an exemplary laminated structure with any of the exemplary multilayer films of Figures 1A-1C, according to one or more of the modes shown and described herein; Figure 3A is a schematic diagram of a sealing process for joining a lid layer to the exemplary laminated structure of Figure 2, according to one or more of the modalities shown and described herein; and Figure 3B is a schematic diagram of the formation of a blister after sealing the exemplary laminated structure of Figure 2 with the cap layer, according to one or more of the modalities shown and described herein. Detailed description of the invention Details of one or more of the currently disclosed subject matter modalities are presented in this document. Modifications to the modalities described in this document, and other modalities, will become evident to those skilled in the art after a study of the information provided herein. The information provided in this document, and in 4D0U, particularly the specific details of the exemplary modalities described, are provided primarily for clarity of understanding and should not be interpreted as imposing unnecessary limitations. In case of conflict, the descriptive summary of this document, including the definitions, shall prevail. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to whom the inventions pertain. All patents, patent applications, publications and published applications, databases, websites, and other published documents referenced throughout this disclosure are incorporated by reference in their entirety, unless otherwise indicated. In the event of multiple definitions for terms in this document, the definitions in this section shall prevail. Reference is made to a URL or other similar identifier or address, with the understanding that such identifiers may change and that particular information may appear and disappear on the Internet, but equivalent information may be found by searching the Internet.The reference to the same thing demonstrates the availability and public dissemination of such information. Although any method, device, and material similar or equivalent to those described herein may be used in the practice or testing of the subject matter currently disclosed, representative methods, devices, and materials are described herein. In accordance with an old patent law convention, the terms "a," "one," and "the" refer to one or more when used in this application, which includes the claims. Thus, for example, the reference to a layer includes a plurality of such layers, etc., unless otherwise stated. Furthermore, unless otherwise stated, all numbers expressing quantities of ingredients, properties such as reaction conditions, etc., used in the specification and claims, should be understood as modified in all cases by the term "approximately". Consequently, unless otherwise stated, the numerical parameters established in this specification and claims are approximations that may vary depending on the desired properties to be obtained from the currently disclosed subject matter. As used herein, the term “approximately”, when referring to a value or quantity of mass, weight, time, volume, concentration, or percentage, is intended to encompass variations of in some forms ±20%, in some forms ±10%, in some forms ±5%, in some forms ±1%, in some forms ±0.5%, and in some forms ±0.1% from the specified quantity, as such variations are appropriate for carrying out the disclosed method. As used herein, ranges may be expressed as starting from “approximately” a particular value and / or to “approximately” another particular value. It is also understood that there is a series of values ​​disclosed herein, and that each value is also disclosed herein as “approximately” that particular value in addition to the value itself. For example, if the value “10” is disclosed, “approximately 10” is also disclosed. It is further understood that each unit between any two particular units is also disclosed. For example, if 10 and 15 are disclosed, then 11, 12, 13, and 14 are also disclosed. The embodiments described herein relate to a blister pack having a laminated structure that can be heat-bonded to a lacquer layer on cold-formed aluminum foil. The laminated structure includes a sealing layer covering one or more conformable film layers. The sealing layer is made of a copolyester material and can be co-extruded with conformable film layers to form the laminated structure. The inventors have found that an additional coating layer on the outer surface of the laminated structure is not required to bond it to a cold-formed aluminum foil lid layer. This reduces the cost and complexity of the manufacturing process while improving the overall construction of the blister pack formed from the laminated structure. Now, with reference to Figures 1A, 1B, and 1C, schematic diagrams of three exemplary multilayer films 100 are shown, each having conformable film layers 120i. Each of the embodiments in Figures 1A-1C includes a multilayer film 100 of structure A / B / B having a sealing layer 110 covering a first conformable layer 120i and a second conformable layer 1202, wherein the first conformable layer 120i is interposed between the sealing layer 110 and the second conformable layer 1202. While the embodiments shown in Figures 1A-1C show only two conformable layers 120i and 1202, the multilayer film 100 is not restricted as such and may contain one or more conformable layers 120i, 1202, 1203, 1204,..., 120n depending on the particular application. In some models, the 110 sealing layer is made of a copolyester material and has a thickness of approximately 1.5 microns to approximately 4 microns. The material chosen for the sealing layer 110 must be compatible with both the material of the conformable layers 120i, 12O2 and with a multilayer extrusion process for forming the multilayer film 100. In some embodiments, the sealing layer 110 is formed from a copolyester material such as, among others, isophthalic acid copolyesters, ethylene glycol copolyesters, diethylene glycol (DEG) copolyesters, triethylene glycol (TEG) copolyesters, cyclohexanedimethanol (CHDM) modified PET copolyesters, n-propylene glycol copolyesters, and n-butylene glycol copolyesters. In exemplary embodiments, the copolyester material is formed by a catalyzed polycondensation reaction between one or more glycol components and one or more diacid components. In non-limiting examples, the glycol components may be ethylene glycol, DEG, TEG, CHDM, n-propylene glycol, n-butylene glycol, and similar linear and branched diols. In non-limiting examples, the diacid components may be purified terephthalic acid (PTA), comonomers of adipic acid, sebacic acid, succinic acid, and similar linear and branched diacids. In some embodiments, the copolyester material forming the sealing layer 110 has physical properties (e.g., intrinsic viscosity) that produce the thermo-adhesive characteristics of the copolyester material and improve interfacial compatibility with the material of the conformable layers 120i, 1202 so that the sealing layer 110 can be co-extruded at a high temperature. In some embodiments, the copolyester material has an intrinsic viscosity of approximately 0.5 deciliters / gram to approximately 1.0 deciliters / gram, preferably from approximately 0.6 deciliters / gram to approximately 0.7 deciliters / gram. The intrinsic viscosity (IV) of a polymer represents the property of a polymer in solution to increase the viscosity of the solution.Intrinsic viscosity is defined as the ratio of the specific viscosity of the solution (the relative viscosity of the polymer solution at a known concentration minus one) to the solute concentration extrapolated to zero. Therefore, intrinsic viscosity is the limiting value of the ratio between specific viscosity and concentration at zero. Intrinsic viscosity can be determined by measuring the relative viscosity of the solution at several different concentrations and then extrapolating the specific viscosity to zero. Intrinsic viscosity can also be determined by measuring the inherent viscosity at infinite dilution of the polymer, where inherent viscosity is the ratio of the natural logarithm of relative viscosity (the ratio of the viscosities of the polymer solution and the pure solvent at the same temperature) to the concentration. Intrinsic viscosity can be measured using a method described in ASTM D 4603 (Standard Test Method for Determining the Intrinsic Viscosity of Polyethylene Terephthalate (PET) Using a Glass Capillary Viscometer). In some forms, the copolyester material has a crystallinity of 1 to 25%, such as 5 to 20%, 5 to 15%, 5 to 10%, or 10 to 20%, as measured by differential scanning calorimetry (DSC). If the copolyester material has a higher crystallinity, it can often be rapidly heated and quenched in a commercial coextrusion process so that the crystallinity is reduced to within the range mentioned above. DSC provides a well-established analytical technique for determining polymer crystallinity (and other morphological characteristics) based on the heat required to melt the polymer. As a polymer sample is heated and cooled over a period of time within a predetermined temperature range, the differential heat flow into or out of the polymer is measured using sensors and plotted. As a polymer is initially heated, its heat capacity increases linearly as it passes the glass transition temperature (Tg). Subsequently, as the polymer is heated beyond the glass transition temperature Tg, the polymer molecules gain increasing amounts of energy until they form organized crystalline structures. The increased crystallinity allows the polymer to release additional heat (AHc) such that the temperature drops to the polymer's cold crystallization temperature (Tc).However, the further application of heat begins to break down the organized crystalline structures, and the polymer gradually transitions to an amorphous phase and eventually melts at a melting temperature (Tm) upon absorbing sufficient heat (AHm). Data plotted by DSC allow for the measurement of specific heat capacity, heat of transition, phase change temperatures, and the rate of heat flow into or out of a polymeric material, as a function of both time and temperature. The percentage of crystallinity of a polymer is measured using the following equation: % crystallinity = [AHm -AHc] *100% / AHm° (Equation 1), where: AHm = heat of fusion (measured in joules / gram) AHc = cold crystallization heat (measured in joules / gram) AHní = heat of fusion of a fully crystalline polymer (measured in joules / gram and is a commonly known reference value for different polymers) It is believed that a crystallinity of 5 to 20%, as measured by DSC, gives the copolyester material of sealing layer 110 the ability to seal directly to a lacquer layer on cold-formed aluminum foil by applying only heat and pressure, without the need for an additional coating or adhesive layer. The sealing strength of the sealing layer 110 thus formed has been experimentally verified, as described in Example A below. In some embodiments, the 110 sealing layer may contain silica, alumina, or a combination thereof blended with the copolyester material. Dry particles of silica, alumina, or a combination thereof are blended with one or more layers of the low-viscosity copolyester material and subsequently polymerized to form the blended 110 sealing layer. The sealing layer 110 has an outer surface 112 opposite an inner surface 114 facing the first conformable layer 120i. The outer surface 112 of the sealing layer 110 is heat-bonded directly to a lacquer layer 354 coated onto cold-formed aluminum foil 352 (shown in Figure 3A). In some embodiments, the sealability between the sealing layer 110 and the lacquer layer 354 can be observed from a temperature of approximately 85°C. In some embodiments, one or more of the conformable layers 120i are formed from a thermoplastic material capable of thermoforming or cold forming, such as, but not limited to, polyethylene, polypropylene, nylon, polystyrene, polyethylene terephthalate (PET), polylactic acid, and polyvinyl chloride (PVC). In some embodiments, one or more of the conformable layers 120i are formed from a biaxially oriented PET layer having a metaphase evidenced by a metaphase transition at approximately 180°C to approximately 200°C as measured by DSC after an initial heating and a molded volume greater than or equal to approximately 200%.In one example, the first conformable layer 1201 can be formed from a biaxially oriented PET layer having a metaphase evidenced by a metaphase transition at approximately 180°C to approximately 200°C as measured by DSC on an initial heating and a molded volume greater than or equal to approximately 200%. In another example, the second conformable layer 1202 can, in addition to or alternatively, be formed from a biaxially oriented PET layer having a metaphase evidenced by a metaphase transition at approximately 180°C to approximately 200°C as measured by DSC after an initial heating and a molded volume greater than or equal to approximately 200%. In this context, and as used in this document, the term “metaphase” refers to IVIA / a / ZUZ I 4D0U An amorphous phase induced in a conformable film that gives it excellent conformability (e.g., thermoformability) and tensile strength, and which is not found in standard biaxially oriented PET films. Such a metaphase can be induced and the resulting properties obtained by orienting the biaxially oriented PET film layer at reduced temperatures and tensile ratios, and subsequently allowing the biaxially oriented PET film layer to relax to a greater extent than is done in the production of other thermoformable films. The metaphase is readily observed in the DSC profile of biaxially oriented PET conformable films as a deflection point in the heat flux curves from approximately 180°C to approximately 200°C (e.g., 190°C) in early heating experiments.Since it is a metastable phase, subsequent heating or annealing experiments will not reveal this phase, as the metaphase will be smothered. Without wishing to be restricted to any particular theory, the metaphase is believed to be a quasi-stable phase intermediate in composition between that of the common crystalline and amorphous components of a semicrystalline thermoplastic. In particular, the phase is believed to be a bound amorphous phase associated with the crystalline structure within the film. This bound amorphous phase has additional latent elongation properties and thus allows for significantly greater conformability within biaxially oriented PET conformable films. In some embodiments, biaxially oriented PET conformable films can be described as having a metastable phase with a phase transition temperature lower than the film's crystalline melting point as measured by DSC. Specifically, in some embodiments, the phase transition temperature is approximately 40°C, 45°C, 50°C, 55°C, 60°C, or 65°C lower than the film's crystalline melting point as measured by DSC. The term “molded volume” refers to the amount of volume increase exhibited by a particular film layer before rupture occurs. Molded volume is commonly measured using reduced heat and pressure experiments, in which thin-film materials are placed on a cavity mold and, under reduced heat and pressure, molded into a crescent shape. These experimental procedures are generally optimized to produce the maximum molded volume before rupture occurs. The relative volume measured before rupture is normalized for a conventionally manufactured biaxially oriented PET film that would provide a 100% normalized volume under optimal conditions. As a result of the metaphase transition present in biaxially oriented PET moldable films, the molded volume of any cavity formed within them can exceed 200% due to an increase in cavity diameter. This volume increase can be measured by comparing the amount of water or other liquid required to completely fill the cavity before and after the moldable film undergoes metaphase transition. In some embodiments, one or more of the conformable layers 120 may include silica, alumina, or a combination thereof mixed with the thermoplastic material. In one example, the first conformable layer 120i may contain silica, alumina, or a combination thereof mixed with the thermoplastic material. In another example, the second conformable layer 1202 may also, or alternatively, contain silica, alumina, or a combination thereof mixed with the thermoplastic material. The process of mixing dry particles of silica, alumina, or a combination thereof into the thermoplastic material is substantially similar to the process of mixing them into the copolyester material of the sealing layer 110, as described above. In some applications, conformable 120 layers are prepared using conventional sequential biaxial orientation machines that have a single-screw main line extrusion train and a twin-screw subextrusion process. Other modifications to the standard machine configurations are also possible and well-known to technicians in the field. In this regard, in some methods, standard PET granules with a desired intrinsic viscosity can be fed to the main extrusion line, while granules of a different composition can be fed to a subextrusion process. For example, a mixture of standard PET granules and silica-filled PET granules can be fed to the subextrusion process.The materials can be melted separately and laminated together in a feed block to produce a desired multilayer melt structure (e.g., an A / B / A melt structure) in an extrusion die. The laminated PET layers emerging from the extrusion die are quenched in a cooled casting drum to produce a thick, amorphous film structure that is approximately 9 µm, 12 µm, 15 µm, 20 µm, 23 µm, 25 µm, 30 µm, 35 µm, 36 µm, 40 µm, 45 µm, or 50 µm thick. Figure 2 is a schematic diagram of a lamination process for forming an exemplary laminated structure 200 with any of the exemplary multilayer films 100 of Figures 1A-1C. In the embodiments, a laminated structure 200 may include the multilayer film 100 laminated to a core structure. The core structure may include at least one layer exhibiting a metaphase transition, such as a metaphase PET layer. In the embodiments, the core structure may include, for example, a three-layer metaphase structure 250. In the laminated structure 200, additional layers may be interposed between the multilayer film 100 and the core structure, such as the three-layer metaphase structure 250. For example, an intermediate layer 230 may be interposed between the multilayer film 100 and the core structure, such as the three-layer metaphase structure 250.In exemplary embodiments, the intermediate layer 230 can be a soft metal sheet, such as soft aluminum foil. The intermediate layer 230 can be bonded to the multilayer film 100 by a first adhesive layer 220 between the intermediate layer 230 and the multilayer film 100. The intermediate layer 230 can be bonded to the core structure, such as the three-layer metaphase structure 250, for example, by a second adhesive layer 240 between the intermediate layer 230 and the core structure. From now on, exemplary lamination processes for forming the laminated structure 200 will be described. As shown in Figure 2, the laminated structure 200 is formed through lamination step A and lamination step B. During lamination step A, the multilayer film 100 is laminated to an intermediate layer 230 with a first adhesive layer 220 such that the first adhesive layer 220 is located between the second conformable layer 1202 and the intermediate layer 230. In some embodiments, the intermediate layer 230 is formed from soft aluminum foil. In some embodiments, the first adhesive layer 220 is ADCOTE® 811A + COREACTANT F, produced by Rohm and Haas Chemicals LLC, Philadelphia, PA. In other products, adhesives based on polyol reactions and urethane prepolymers may be used. During lamination step B, a three-layer metaphase structure 250 is laminated to the intermediate layer 230 with a second adhesive layer 240, substantially similar to the first adhesive layer 220, such that the second adhesive layer 240 is located between the intermediate layer 230 and the three-layer metaphase structure 250. In some embodiments, the three-layer metaphase structure 250 has an ABA structure comprising a first PET layer 252, a second PET layer 256, and a silica-containing PET layer 254 interposed between the first PET layer 252 and the second PET layer 256. Thus, the intermediate layer 230 is positioned between the second conformable layer 1202 and the first PET layer 252.In some embodiments, the first PET 252 layer and the second PET 256 layer are formed from a biaxially oriented PET layer having a metaphase evidenced by a metaphase transition present at approximately 180°C to approximately 200°C as measured by DSC after an initial heating and a molded volume greater than or equal to approximately 200%. In some embodiments, one or more layers of thermoplastic material, such as polyethylene, polypropylene, nylon, polystyrene, PET, polylactic acid, and PVC, among others, may be removed in addition to or instead of the three-layer metaphase structure 250. Such additional layers may be incorporated through further lamination steps. The lamination process shown in Figure 2 produces an exemplary laminated structure 200 that can be used to prepare a blister 300, as described below. Figures 3A-3B depict the formation of a blister 300 from the exemplary laminated structure 200. In particular, Figure 3A shows a schematic diagram of a bonding sealing process of a lid layer 350 to the exemplary laminated structure 200 to prepare the blister 300, while Figure 3B shows a schematic diagram of the formation of a blister 360 after sealing the exemplary laminated structure 200 with the lid layer 350. As shown in Figure 3A, the lid layer 350 comprises the cold-form-hardened aluminum foil layer 352 having a sealing surface 353. The cold-form-hardened aluminum foil is typically brittle and can be easily punctured to recover the contents of the blister 300. The sealing surface 353 is coated with the lacquer layer 354.During the sealing process, the outer surface 112 of the sealing layer 110 is pressed directly against a lower surface 355 of the lacquer layer 354 and heated to a temperature above 85°C to form the blister 300. Accordingly, the lid layer 350 is laminated with the multi-layer laminated structure 200 under heat and pressure to form the blister 300. As shown in Figure 3B, the laminated structure 200 wound around an unwinder 310 is passed through a die to form a plurality of cavities 320 by applying pressure, typically between 4 and 6 kg / cm². The plurality of cavities 320 is formed by a cavity-forming part (not shown) at a rate of approximately 20 to approximately 30 blisters per minute. A product 330 is then inserted into each of the pluralities of cavities 320. The product 330 can be a food product, a pharmaceutical, or another commercial product. The lid layer 350 wound around a spindle 340 is pressed against the laminated structure 200 and heat-sealed to form the blister 300, as described above. Finally, individual blisters 360 are punched out from the blister 300. The apparatus and methods described herein can be advantageously used to prepare a laminated structure of conformable films that can be readily heat-bonded to a cold-formed, hardened aluminum foil lid layer to form a blister pack, without requiring additional coatings to improve the bond between the laminated structure and the lid layer. When additional coatings are used, the laminated structure must be processed through the laminating machine a second time to add the extra coating. However, since no additional coatings are needed due to the co-extruded sealing layer in the laminated structure, the laminating machine only needs to be used once. This results in significant savings in manufacturing cost and time, while improving the overall construction of the blister pack. The following specific but not limiting example, example A, demonstrates the strength of the sealing layer in the laminated structure through experimentally verified data. Example A - Measuring the seal strength of the sealing layer The sealing strength of the sealing layer described in this disclosure was examined using a first sample of the sealing layer partially heat-bonded on one surface to a cold-form-hardened aluminum foil layer coated with a lacquer layer on the sealing surface and a second sample of the sealing layer partially heat-bonded on both surfaces to the cold-form-hardened aluminum foil layers coated with lacquer layers on the sealing surfaces.The test measured the force required to separate the sealing layer from the cold-strain-hardened aluminum foil layers by clamping the unsealed portions of the cold-strain-hardened aluminum foil layers in the movable clamps of a tensile tester and then moving the clamps of the tensile tester at a constant strain rate to separate the sealed portions from the cold-strain-hardened aluminum foil layers. Test conditions were followed according to the standardized guidelines of ASTM D 882 and ASTM F 88. The applied force and displacement on the sealing layer were continuously measured. Seal strength was measured as the amount of force required (in grams) per 25 mm of sample width to separate the sealing layer from the cold-work-hardened aluminum foil layer. For each sample, the minimum, maximum, and average force required to break the seal were measured at different temperatures (100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, and 210°C) and compared to a desired reference seal strength of more than 500 g / 25 mm. The test data are shown in Table 1 below and demonstrate high seal strength in all cases. Table 1: Seal strength data provided by the tensile tester Ser. No. Temp. (°C) Seal resistance (g / 25 mm) Without support With Al / Alu laminate support Pressure Pressure 3.0 kg 4.0 kg 5.0 kg 4.0 kg 5.0 kg Min. Max. Avg. Min. Max. Avg. Min. Max. Avg. Min. Max. Avg. Min. Max. Avg. 1 100 430 720 575 375 800 590 560 740 650 — — — — — — 2 110 845 1180 1015 830 1100 965 775 1150 965 — — — — — — 3 120 760 1065 915 325 920 620 905 960 930 — — — — — — 4 130 610 670 640 445 915 680 380 675 530 — — — — — — 5 140 510 690 600 360 790 575 435 780 605 — — — — — — 6 150 500 565 535 565 915 740 565 895 730 695 710 700 565 660 610 7 160 500 760 630 575 750 660 830 715 770 555 800 675 400 760 580 8 170 510 720 615 565 610 585 750 785 770 480 950 715 595 1000 800 9 180 595 955 775 610 885 750 645 1155 900 645 710 680 460 925 695 10 190 290 420 355 365 680 520 465 680 570 430 945 690 535 885 710 11 200 425 740 585 490 535 515 345 1035 690 520 850 685 355 565 460 12 210 495 620 555 350 625 490 360 770 565 770 875 820 645 810 730 It is noted that the terms “substantially” and “approximately” may be used herein to encompass the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also used to represent the degree to which a quantitative representation may vary from a stated reference without resulting in a change to the basic function and intended scope of the subject matter in question. While the specific modalities have been illustrated and described herein, it should be understood that other changes and modifications may be made without departing from the essence and scope of the claimed subject matter. Furthermore, although various aspects of the claimed subject matter have been described herein, it is not necessary to use those aspects in combination. Therefore, it is intended that the appended claims encompass all changes and modifications that fall within the scope of the claimed subject matter.

Claims

CLAIMS 1. A multilayer film comprising: a first conformable layer comprising a thermoplastic material; and a sealing layer comprising a copolyester material, the sealing layer covering the first conformable layer and having an outer surface opposite the first conformable layer, the sealing layer having a crystallinity of 5 to 20% as measured by differential scanning calorimetry (DSC).

2. The multilayer film according to claim 1, wherein the outer surface of the sealing layer is heat-adhesive directly to a lacquer layer coated on a cold-formed hardened aluminum foil.

3. The multilayer film according to claim 1, wherein the thermoplastic material is selected from the group consisting of polyethylene, polypropylene, nylon, polystyrene, polyethylene terephthalate (PET), polylactic acid, and polyvinyl chloride (PVC).

4. The multilayer film according to claim 1, wherein the first conformable layer further comprises silica, alumina, or a combination thereof.

5. The multilayer film according to claim 1, wherein the copolyester material is selected from the group consisting of isophthalic acid copolyesters, ethylene glycol copolyesters, diethylene glycol (DEG) copolyesters, triethylene glycol (TEG) copolyesters, cyclohexanedimethanol (CHDM) modified PET copolyesters, n-propylene glycol copolyesters, and n-butylene glycol copolyesters.

6. The multilayer film according to claim 1, wherein the sealing layer further comprises silica, alumina, or a combination thereof.

7. The multilayer film according to claim 1, wherein the first conformable layer is a biaxially oriented PET layer having: a metaphase evidenced by a metaphase transition from approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating; and a molded volume greater than or equal to approximately 200%.

8. The multilayer film according to claim 7, wherein the first conformable layer is interposed between the sealing layer and a second conformable layer comprising the thermoplastic material.

9. The multilayer film according to claim 8, wherein the second conformable layer is a biaxially oriented PET layer having: a metaphase evidenced by a metaphase transition present at approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating; and a molded volume greater than or equal to approximately 200%.

10. The multilayer film according to claim 9, wherein the first conformable layer, the second conformable layer, or both, further comprises silica, alumina, or a combination thereof.

11. A laminated structure comprising: a multilayer film according to claim 1; and a core structure comprising at least one layer having a metaphase transition from approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating and having a molded volume greater than or equal to approximately 200%; an intermediate layer comprising a soft metal foil interposed between the multilayer film and the core structure.

12. A blister pack for packaging a product, the blister pack comprising: a lid layer comprising cold-formed aluminum foil and a lacquer layer on a sealing surface of the cold-formed aluminum foil; and a laminated structure sealed directly to the lacquer layer, the laminated structure comprising a multilayer film and a plurality of cavities formed therethrough, the multilayer film comprising: a first conformable layer comprising a thermoplastic material; and a sealing layer comprising a copolyester material, the sealing layer covering the first conformable layer and comprising an outer surface opposite the first conformable layer, wherein the sealing layer has a crystallinity of 5 to 20% as measured by DSC, wherein the outer surface of the sealing layer is sealed directly to the lacquer layer.

13. The blister according to claim 12, wherein the laminated structure further comprises one or more additional layers laminated to the multilayer film, one or more additional layers selected from an aluminum foil layer, a polyvinyl chloride (PVC) layer, and an adhesive layer.

14. The blister according to claim 12, wherein the thermoplastic material is selected from the group consisting of polyethylene, polypropylene, nylon, polystyrene, polyethylene terephthalate (PET), polylactic acid, and polyvinyl chloride (PVC).

15. The blister according to claim 12, wherein the first conformable layer further comprises silica, alumina or a combination thereof.

16. The blister according to claim 12, wherein the copolyester material is selected from the group consisting of isophthalic acid copolyesters, ethylene glycol copolyesters, diethylene glycol (DEG) copolyesters, triethylene glycol (TEG) copolyesters, cyclohexanedimethanol (CHDM) modified PET copolyesters, n-propylene glycol copolyesters, and n-butylene glycol copolyesters.

17. The blister according to claim 12, wherein the sealing layer further comprises silica, alumina or a combination thereof.

18. The blister according to claim 12, wherein the first conformable layer is a biaxially oriented PET layer having: a metaphase with a metaphase transition present at approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating; and a molded volume greater than or equal to approximately 200%.

19. The blister according to claim 18, wherein the multilayer film further comprises at least one additional biaxially oriented PET layer having: a metaphase with a metaphase transition present at approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating; and a molded volume greater than or equal to approximately 200%.

20. The blister according to claim 19, wherein the additional biaxially oriented PET layer further comprises silica, alumina, or a combination thereof.

21. The blister according to claim 12, wherein the sealing layer has a thickness of approximately 1.5 microns to approximately 4 microns.

22. A method for preparing a blister pack, the method comprising: laminating a lid layer and a multi-layer laminated structure under heat and pressure to form the blister pack, the lid layer comprising cold-form-hardened aluminum foil having a lacquer layer on a sealing surface of the cold-form-hardened aluminum foil, the laminated structure comprising a multi-layer film having a first conformable layer and a sealing layer, the first conformable layer comprising a thermoplastic material, the sealing layer comprising a copolyester material, the sealing layer covering the first conformable layer and having an outer surface opposite the first conformable layer, the sealing layer having a crystallinity of 5 to 20% as measured by DSC, wherein during lamination, the outer surface of the sealing layer is pressed directly against the lacquer layer.

23. The method according to claim 22, wherein the thermoplastic material is selected from the group of thermoplastic materials consisting of polyethylene, polypropylene, nylon, polystyrene, polyethylene terephthalate (PET), polylactic acid, and polyvinyl chloride (PVC).

24. The method according to claim 22, wherein the copolyester material is selected from the group consisting of isophthalic acid copolyesters, ethylene glycol copolyesters, diethylene glycol (DEG) copolyesters, triethylene glycol (TEG) copolyesters, cyclohexanedimethanol (CHDM) modified PET copolyesters, n-propylene glycol copolyesters, and n-butylene glycol copolyesters.

25. The method according to claim 24, wherein the thermoplastic material comprises PET.

26. The method according to claim 25, wherein the thermoplastic material further comprises silica, alumina, or a combination thereof.

27. The method according to claim 22, wherein the thermoplastic material is a biaxially oriented PET having: a metaphase evidenced by a metaphase transition present at approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating; and a molded volume greater than or equal to approximately 200%.

28. The method according to claim 22, wherein the multilayer film further comprises a second conformable layer comprising the thermoplastic material, the first conformable layer being interposed between the sealing layer and the second conformable layer.

29. The method according to claim 28, wherein the multilayer film further comprises: a three-layer metaphase structure comprising a first PET layer, a second PET layer, and a silica-containing PET layer between the first PET layer and the second PET layer; an intermediate layer comprising aluminum foil; a first adhesive layer; and a second adhesive layer, wherein: the intermediate layer is located between the second conformable layer and the first PET layer; the first adhesive layer is located between the second conformable layer and the intermediate layer; and the second adhesive layer is located between the intermediate layer and the three-layer metaphase structure.

30. The method according to claim 29, wherein the first PET layer and the second PET layer are biaxially oriented with a metaphase evidenced by a metaphase transition present at approximately 180°C to approximately 200°C as measured by differential scanning calorimetry (DSC) after a first heating and a molded volume greater than or equal to approximately 200%.