TECHNICAL FIELD

[0001] This invention is directed to a multi-layer film. In particular, the present invention relates to a thermoformable packaging film. More particularly, the present invention relates to thermoformable packaging film used for packaging medicines and pharma/edible products.

BACKGROUND

[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the present invention, or that any publication specifically or implicitly referenced is prior art.

[0003] The flexible packaging of edibles such as food items, medical or pharmaceutical products, industrial goods, and the like is an ever growing industry. The creation of flexible packaging materials is usually a multi-step process. Converters, or the producers of flexible packaging films, are companies that typically initially print flexible films, layer, slit and supply the flexible web stock to an end-user. Such web stocks are then chosen for printability, barrier properties, clarity, scuff resistance, heat-sealability, and several other technical and cost considerations for use in the final product. The web stocks, after creation and selection, are then further processed on a product packaging line to create a pouch, bag, tray, lid, blister or similar structure at the point of use. That creation of the end-use package subsequently allows for an increased freshness or shelf-life extension for many commodities. Indeed, it is a goal within the industry to increase shelf-stability for a range of food and medical materials, while also presenting an appealing packaged product to the consumer.

[0004] In this regard, within the flexible packaging, there is often a need to create formable structures from a flat web. The creation of a well, or cavity, is a well-known packaging methodology to provide for the easy packaging of meats, medical devices, medicines, snacks and other materials. For instance, the creation of a cavity, or well, can be accomplished through a combined heat and suction by vacuum process that draws the web into cavity, whereby the cavity is designed to provide the overall volume needed for packaging the targeted commodity. See, for example, U.S. Pat. No. 3,496,143, which is incorporated herein by reference.

[0005] U.S. Pat. No. 4,537,312, which describes the construction of foil blister packaging that is particularly suited for tamper evident pharmaceutical packaging.

[0006] Within the blister packaging technical area, high barrier is often necessary and aluminum foils are not susceptible to thermoforming. Thus, the use of cold forming technique is prevalent. These methods are typically referred to as cold formed foils or CFF. A particularly important forming structure in this area consists of Nylon films layered to aluminum foils and then again to polyvinylchloride films (PVC). Such structures, when formed into blisters, have advantageous product protection, product integrity, and compliance attributes as described in Pharmaceutical Technology, November 2000, pages 66-77, which is also incorporated herein by reference.

[0007] Commonly, within the flexible packaging technical field, nylon films have been used in combination with aluminum foil to create many cavity structures. In this regard, it is appreciated that nylon films are known to have high elongation properties and are thus well suited for thermoforming and cold forming processes. Within the molding process itself, it is often necessary for the flat web materials to be able to stretch and distort uniformly under heat and pressure to the desired mold volume. Rheological properties of the material dictate the amount of deformation under an applied stress, strain recovery after elimination of the applied load, and permanence of the strain. For many materials including PET, co-polyesters, and blends of PET and miscible components, tan delta values from torsional stress/strain experiments are typically higher at low temperatures and are maximized at the glass transition temperatures of the materials. The importance of these principles to thermoforming can be found, for example, in “Importance of elongation properties of polymer melts for film blowing and thermoforming”; Polymer Engineering & Science Volume 46, Issue 9, pages 1190-1195, September 2006, which is further incorporated herein by reference.

[0008] A typically desired input web may be any combination of printed material, barrier webs, adhesives, sealable materials, and the like. In this regard, it is sometimes considered important that all components of the flexible web have the capability to distort uniformly into the mold structure, as differences in moldability between the discontinuous web-stocks of the flexible web can cause molding issues like splitting, uneven distortion, crystallization, or other defects capable of diminishing the suitability of the molded web for the end-use application.

[0009] Within the flexible film and flexible packaging technology areas, the use of thermoplastic materials like polyethylene, polypropylene, nylon, polystyrene, polyethylene terephthalate (PET), polylactic acid, and other thermoplastic commodities to produce films is appreciated. Each base polymer, or resin, has intrinsic technical attributes like barrier properties, optical clarity, hardness, surface energy, softness, etc. that makes their selection for the end-use need appropriate. Extruding these thermoplastic polymers into web structures and orienting them into thin films is an important industrial process to induce further enhanced properties into polymeric materials. Stretching and orientation are appreciated in the art to improve tensile and elongation properties, tear properties, scuff resistance, etc. For pharma and medical devices in rigid or semi-rigid blisters PVC sheet is commonly used however this material is not considered good for human exposure having carcinogenic properties and often has heavy metal content due to many additives. Therefore, it is also appreciated in the art to select a base resin and filming process capable of creating a suitable film substrate for the technical needs in a flexible packaging web.

[00010] Among films currently available, PET is a material with excellent barrier, clarity, printability, and hardness properties. Film forming and orientation of that material can be used to create thin profile webs with excellent properties for use in flexible packaging. Typically, such PET films have high thermal stability and low subsequent moldability properties. In fact, although traditional biaxially-oriented PET (BOPET) films can be produced with subsequent down-stream moldability, the moldability is generally not high. Alternatively, however, high thermoforming with PET films can be achieved if the films are not oriented, or are monoaxially oriented as described, for example, in U.S. Pat. No. 4,073,857, which is also incorporated herein by reference.

[00011] Despite the advantageous properties of PET films, when thermoforming oriented PET web material under heat and pressure, current PET film structures and converted webs will often split or break easily. Due to the limitations of current PET films, the utility of these materials for the production of thermoformed trays, wells or cavities has thus been limited. Converters, therefore, often need to select other film materials when the packaging structure involves a thermoformable structure.

[00012] To resolve such low formability issues of current PET film materials, there has been research into blends of PET with other materials to improve the molding process. Such techniques, however, although improving the thermo-molding properties, have only created other issues such as increased cost, regulatory clearance issues, optical clarity problems, and recycling issues. Accordingly, there remains a need in the art for PET film structures capable of easy forming and use in a range of end-use packaging requirements, including thermo-formed and cold-formed wells, trays, or cavities, and for a range of applications, including foodstuffs, medical products, and industrial goods.

OBJECT OF THE PRESENT INVENTION

[00013] It is an object of the present invention to provide a multilayer thermoformable film.

[00014] It is another object of the present invention to provide a multilayer thermoformable film that replaces poly vinyl chloride (PVC) film with polyester-based film.

[00015] It is another object of the present invention to provide a multilayer thermoformable film that can be produced on wider & high speed BOPET line. [00016] It is another object of the present invention to provide a multilayer thermoformable film that is cost efficient.

[00017] It is another object of the present invention to provide a multilayer thermoformable film that is non-carcinogenic and environment friendly.

SUMMARY

[00018] This invention is directed to a multi-layer film. In particular, the present invention relates to a thermoformable packaging film. More particularly, the present invention relates to thermoformable packaging film used for packaging medicines, medical devices and pharma/edible products.

[00019] An aspect of the present invention provides a multilayer thermoformable film comprising a composite structure having at least three co-extruded layers, said multilayer film comprising: a top layer of the composite structure comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer; a bottom layer of the composite structure comprises a layer of PET consisting essentially of 69% to 79% of the weight of the total polymer layers; and a core layer of the composite structure comprises PET copolymer consisting essentially of 12% to 15.5% by weight of copolymer.

[00020] According to an aspect, total thickness of the multilayer thermoformable film is in a range of 150-300 microns.

[00021] According to an aspect, thickness of the top layer is in a range of 20-55 microns, the core layer is in a range 10-45 microns, and the bottom layer is in a range of 120 200 micron.

[00022] According to an aspect, the top layer is a heat sealable layer and having an outer surface opposite the bottom layer.

[00023] According to an aspect, the outer surface of the top layer is heat-sealable directly to a lacquer coated aluminum foil to be used as lidding substrate.

[00024] According to an aspect, the copolymer of PET is isophthalic acid based.

[00025] According to an aspect, the least three co-extruded layers are biaxially-oriented PET(BOPET) having: melting point in a range of 190°C to 220°C as measured by differential scanning calorimetry (DSC) upon a first heating; and a thermoformed depth volume of less than or equal to 200%.

[00026] According to an aspect, machine direction and transverse direction total elongation is in a range of 150% to 350%.

[00027] According to an aspect, crystallization temperature of co-extruded at least three layers is in the range of 90°C to 156°C. [00028] According to an aspect, stretching ratio in machine direction and transverse direction is in a range of 2.0% to 2.6%.

[00029] Another aspect of the present invention provides a blister package for packaging a product, the blister package comprising: a multilayer thermoformable fdm comprising a composite structure having at least three layers, said multilayer fdm comprising: a top layer of the composite structure comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer; a bottom layer of the composite structure comprises a layer of PET consisting essentially of 69% to 79% of the weight of the total polymer layer; and a core layer of the composite structure comprises PET copolymer consisting essentially of 12% to 15.5% by weight of copolymer, wherein the top layer is a heat sealable layer and having an outer surface opposite the bottom layer, wherein the outer surface of the top layer is heat-sealable directly to a heat sealable fdm to be used as lidding substrate of the blister package.

[00030] According to an aspect, the lidding with heat sealable layer comprises any of a lacquer coated aluminum, and a heat sealable PET (HSPET) fdm.

BRIEF DESCRIPTION OF THE DRAWINGS

[00031] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

[00032] FIG. 1 illustrates an exemplary representation of multiple layers of thermoformable packaging fdm in accordance with an embodiment of the present invention.

[00033] FIG. 2 illustrates an exemplary representation of multiple layer fdm with formed well or a cavity in accordance with an embodiment of the present invention.

[00034] FIG. 3A illustrates exemplary representation of steps for forming a blister package starting from web of co-extruded multilayer fdm and web of lacquer coated aluminum foil in accordance with an embodiment of the present invention.

[00035] FIG. 3B illustrates an exemplary representation of blister package in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION [00036] The presently-disclosed subject matter meets some or all of the above-identified needs, as will become evident to those of ordinary skill in the art after a study of information provided in this document.

[00037] This summary describes several embodiments of the presently-disclosed subject matter, and in many cases lists variations and permutations of these embodiments. This summary is merely exemplary of the numerous and varied embodiments. Mention of one or more representative features of a given embodiment is likewise exemplary. Such an embodiment can typically exist with or without the feature(s) mentioned; likewise, those features can be applied to other embodiments of the presently-disclosed subject matter, whether listed in this summary or not. To avoid excessive repetition, this summary does not list or suggest all possible combinations of such features.

[00038] This invention is directed to a multi-layer film. In particular, the present invention relates to a thermoformable packaging film. More particularly, the present invention relates to thermoformable packaging film used for packaging medicines, medical devices and pharma/edible products etc.

[00039] An aspect of the present invention provides a multilayer thermoformable film comprising a composite structure having at least three co-extruded layers, said multilayer film comprising: a top layer of the composite structure comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer; a bottom layer of the composite structure comprises a layer of PET consisting essentially of 69% to 79% of the weight of the total polymer layer; and a core layer of the composite structure comprises PET copolymer consisting essentially of 12% to 15.5% by weight of copolymer.

[00040] According to an aspect, total thickness of the multilayer thermoformable film is in a range of 150-300 microns.

[00041] According to an aspect, thickness of the top layer is in a range of 20-55 microns, the core layer is in a range 10-45 microns, and the bottom layer is in a range of 12200.

[00042] According to an aspect, the top layer is a heat sealable layer and having an outer surface opposite the bottom layer.

[00043] According to an aspect, the outer surface of the top layer is heat-sealable directly to a lacquer coated aluminum foil to be used as lidding substrate.

[00044] According to an aspect, the copolymer of PET is isophthalic acid based.

[00045] According to an aspect, the least three co-extruded layers are biaxially-oriented PET (BOPET) having: melting point in a range of 190°C to 220°C, as measured by differential scanning calorimetry (DSC) upon a first heating; and a thermoformed depth volume of less than or equal to 200%. [00046] According to an aspect, machine direction and transverse direction total elongation is in a range of 150% to 350%.

[00047] According to an aspect, crystallization temperature of co-extruded at least three layers is in the range of 90°C to 156°C.

[00048] According to an aspect, stretching ratio in machine direction and transverse direction is in a range of 2.0% to 2.6%.

[00049] Another aspect of the present invention provides a blister package for packaging a product, the blister package comprising: a multilayer thermoformable fdm comprising a composite structure having at least three layers, said multilayer fdm comprising: a top layer of the composite structure comprises polyethylene terephthalate (PET), and a copolymer consisting essentially of 12% to 15.5% by weight of the copolymer; a bottom layer of the composite structure comprises a layer of PET consisting essentially of 69% to 79% of the weight of the total polymer layer; and a core layer of the composite structure comprises polyethylene terephthalate (PET), and copolymer consisting essentially of 12% to 15.5% by weight of copolymer, wherein the top layer is a heat sealable layer and having an outer surface opposite the bottom layer, wherein the outer surface of the top layer is heat-sealable directly to a heat sealable fdm to be used as lidding substrate of the blister package.

[00050] According to an aspect, the heat sealable layer comprises any of a lacquer coated aluminum foil, and a heat sealable PET (HSPET) fdm.

[00051] Further features and advantages of the presently-disclosed subject matter will become evident to those of ordinary skill in the art after a study of the description, figures, and nonlimiting examples in this document.

[00052] FIG. 1 illustrates an exemplary representation of multiple layers of thermoformable packaging film in accordance with an embodiment of the present invention.

[00053] In an embodiment, the present invention provides a thermoformable packaging film (interchangeably referred to as formable film 100 or thermoformable fdm 100 hereinafter) 100. The thermoformable film 100 comprises a composite structure of three co-extruded layers. The three co-extruded layers comprise atop layer 102, a core layer 104 and a bottom layer 106.

[00054] The top layer 102 of the thermoformable fdm 100 comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer such that thickness of the top layer is about 20-55 microns. The bottom layer 106 comprises a layer of the PET copolymer consisting essentially of 69% to 79% of the weight of the total polymer layer such that thickness of the bottom layer is about 120-200 microns. The core layer 104 comprises PET copolymer consisting essentially of 12% to 15.5% by weight of copolymer such that thickness of the core layer is about 10-45 microns. The total thickness of the thermoformable film is in the range of 150-300 microns. The copolymer includes isophthalic acid etc.

[00055] The presently-disclosed subject matter includes thermoformable film 100, including the formable films, and processes for producing and using the Thermoformable film 100. In particular, the presently-disclosed subject matter includes BOPET (PET) films that are capable of thermoforming structures including such PET films, and methods of making and using the thermoformable PET films and their structures.

[00056] In some embodiments, a thermoformable film 100 is provided that comprises one or more BOPET layers. In some embodiments, such a thermoformable film 100 includes a metaphase with a melting point of about 190°C to 220°C. as measured by differential scanning calorimetry (DSC) upon a first heating. In some embodiments, the formable film has a thermoformed depth of less than or equal to about 200%. As shown in FIG. 2 the thermoformed depth comprises a depth or cavity or well 202. The formed well or cavity comprises an inner side of formed cavity 202 and outer side of formed cavity 204. The inner side if formed cavity 202 is utilized for storage of product that includes edible items, or medical or pharmaceutical items etc. The inner side of formed cavity 202 is non- carcinogenic and can be used for storing the edible items for a longer period of time.

[00057] In some embodiments, the formable film has a machine direction total elongation percentage of about 150% to about 350%. In some embodiments, the formable film has a transverse direction total elongation percentage of about 150% to about 350%.

[00058] In some embodiments of the presently -described Thermoformable film 100 can be made in a range of thicknesses and/or with various coatings. Regardless of the particular thickness and/or coatings applied to a film, in the Thermoformable film 100 described herein, the metaphase of each of the biaxially-oriented polyethylene terephthalate (BOPET) layers is generally configured to increase one or more properties of the film relative to a conventional BOPET film. For example, in some embodiments of the Thermoformable film 100 described herein, the increased property of the formable film is selected from tensile strength, drawability, formability, or a combination of those properties. For instance, in some embodiments, the BOPET Thermoformable film 100 have a machine direction tensile strength of greater than about 500 kgf/cm at 25°C; a transverse direction tensile strength of greater than about 1000 kgf/cm at 25°C; a machine direction total elongation percentage measured at 25°C of greater than 270%; and a transverse direction of greater than 130%

[00059] With respect to the one or more BOPET layers included in the Thermoformable film 100 of the presently-disclosed subject matter, in some embodiments, at least one of the polyethylene terephthalate layers is comprised of a polyethylene terephthalate homopolymer or is comprised of polyethylene terephthalate copolyester. In some embodiments, at least one of the polyethylene terephthalate layers includes silica. Furthermore, in some embodiments of the Thermoformable fdm 100, the one or more polyethylene terephthalate layers are comprised of at least two, at least three, at least four, or more BOPET layers. For example, in some embodiments, a formable film is provided having three BOPET layers, and in certain embodiments, one of those three layers includes silica.

[00060] In some embodiments, a process for producing a formable film is provided that includes an initial step of producing one or more BOPET layers. In some embodiments, the process then includes: a step of stretching the one or more BOPET layers in a machine direction at a temperature of about 64°C. to about 74°C., at a draw percentage of about 180% to about 250%, or a combination thereof; and a step of stretching the one or more BOPET layers in a transverse direction at a temperature of about 83°C. to about 110°C., at a draw percentage of about 108% to about 250%, or a combination thereof. In some embodiments, subsequent to the stretching steps, the process includes crystallizing the one or more layers at a temperature of about 90°C. to about 156°C.

[00061] Turning now to the crystallization step, in some embodiments, the crystallizing step is performed at a temperature of about 90°C. to about 156°C. In some embodiments, the temperature is varied according to the number of layers, coatings, and thickness of the film. In some embodiments of the process, the step of crystallizing the film is performed at a temperature of about 156°C

[00062] In some embodiments of the processes for producing a formable film described herein, a process for producing a formable film includes a further step of allowing the film to relax to further induce a metaphase in the film. In some embodiments, the formable film is allowed to relax at a temperature of about 50°C. to about 60°C. In some embodiments, the formable film is allowed to relax at a temperature of about 59°C. The relaxation percentage at which the formable film is allowed to relax can be varied according to final desired properties of the formable film. In some embodiments, the formable film is allowed to relax to a relaxation percentage greater than about 2%. In some embodiments, the relaxation percentage is about 3%.

[00063] In some embodiments of the presently-disclosed Thermoformable film 100, a formable film is provided that includes one or more BOPET layers, and that includes a metastable phase in which the metastable phase has a phase transition temperature of about 50°C to 74°C. less than the crystalline melting point of the film as measured by differential scanning calorimetry. In some embodiments, the formable film is capable of forming a cavity with little spring -back force. [00064] In yet other embodiments of the presently-disclosed subject matter, the Thermoformable fdm 100 described herein can also be included as part of a layer structure. In some embodiments, a layer structure is provided that includes a formable fdm including one or more BOPET fdms with the formable fdm having a metaphase as described herein above and also having a thermoforming depth of greater than about 200% when compared to traditional biaxially-oriented PET fdms. In some embodiments, one or more additional layers are layered to the one or more BOPET layers to thereby produce the layer structure. In some embodiments, the one or more additional layers of the layer structure are selected from an aluminum foil layer and a polyvinyl chloride layer. In some embodiments, the one or more additional layers are layered to the one or more BOPET layers with an adhesive.

[00065] In some embodiments of the presently-disclosed layer structures, a layer structure is provided that includes a single BOPET layer, an aluminum foil layer layered to the single BOPET layer, and a polyvinyl chloride layer layered to the aluminum foil layer. In other embodiments, an exemplary layer structure includes a first BOPET layer and a second BOPET layer, and an aluminum foil layer interposed between the first BOPET layer and the second BOPET layer. In other embodiments, the first BOPET layer includes an isophthalate copolyester top layer 102.

[00066] In further embodiments, the layer structures can also include properties suited for a particular end use. For instance, in some embodiments, the layer structure has a puncture strength greater than about 20 Kgf.

[00067] Further provided herein are processes for producing a packaging (e.g., a blister packaging) using the layer structures of the presently-disclosed subject matter. In some embodiments, the process comprises providing a layer structure including: a formable film having one or more BOPET layers, and having a metaphase configured to increase a property of the formable film; and one or more additional layers layered to the one or more BOPET layers. In some embodiments, subsequent to providing the layer structure, the layer structure then undergoes cold or hot forming into a desired shape. In some embodiments, the BOPET layers used to produce the layer structures include a metaphase configured to increase a property of the film selected from the group consisting of tensile strength, drawability, thermoformability, and combinations of these properties.

[00068] FIG. 3A illustrates exemplary representation of steps for forming a blister package starting from web of co-extruded multilayer film and web of aluminum lidding in accordance with an embodiment of the present invention.

[00069] In an embodiment, process for producing blister package 300 comprises a web 304 of thermoformable film 100. The thermoformable film 100 using thermal or cold forming technique is used for making well or cavity 316 on the thermoformable film 100. The film 100 is heated with a heating plate 308 and the heated film 100 is then pressed between a forming top plate 312-1 from the top layer 102 side of the film 100. The forming top plate 312-1 comprises one or more plugs that presses the heated film 100 with bottom forming cavities 312-2 at the bottom such that the top forming plate 312-1 presses the film 100 against the bottom forming cavities 312-2 thereby creating cavities 316. Furthermore, the creation of the cavity from the film 100 can be assisted with air pressure from top plate side or vacuum application from the bottom forming cavities side or combination of both. The negative pressure (vacuum) on the bottom side of the film over the bottom forming cavities 312-2 provides a suction force to mold the heated film 100 into the final desired shape as per cavities. Creation of the cavities 316 based on size and shape is also performed with pressure thermoforming. Sometimes for intricate shape and deep drawn cavities, a combination of vacuum and pressure is used with shaped plugs pushing the heated film 100 into the cavities for forming.

[00070] After the wells or cavities 316 have been formed, product feeding 314 is performed to feed a product 310 in the formed cavities 316. After the product 310 is inserted, a lidding layer received from a web 302 of the lidding material is applied to the formed cavities 316 to seal the product 310.

[00071] In an embodiment, the lidding substrate 302 can be a lacquer 320 coated aluminum layer 306 that is heat sealed to product-feeding 314 side of the thermoformable film 100. In another embodiment, the lidding layer is a heat sealable PET (HSPET). It would be apparent to the person skilled in the art that the lacquer coated lidding substrate would be appropriate for packaging products 310 such as pharmaceutical products such as medicines, tablets or capsules etc., and the lidding substrate of HSPET would be appropriate for sealing edible products such as food items, fruits, vegetables, pre-cooked items, semi-cooked items and the like.

[00072] In an embodiment, the heat-sealed blister package 300 is cut off after a predetermined length as blister package 300, as shown in FIG. 3B. Materials in the lidding substrate comprise lacquer coated aluminum foil, heat sealable PET (HSPET) film etc.

Examples

Example 1

Preparation of Thermoformable PET Film

[00073] Polyethylene terephthalate (PET) film was prepared via a conventional sequential biaxial orientation machine having a single screw mainline extrusion train and a twin screw subextrusion process. PET pellets having a desired intrinsic viscosity were fed into the main extrusion line, while a blend of standard PET pellets and silica-filled PET pellets were fed into the sub-extrusion process, such that the materials could be melted separately and then layered together in a feed-block to produce a desired molten structure (e.g., an A/B/C molten structure) in a multilayer extrusion T-die. The layered PET material or layer emerging from the extrusion die was then quenched on a chilled casting drum to produce a thick, amorphous film structure.

[00074] That amorphous film is subsequently stretched in the machine direction (MD), or long direction axis of the film, utilizing a heater roller train. The MD oriented film is then stretched in the transverse direction (TD) with a gripper and chain driven system. Table- 1 below provides exemplary processing parameters used to produce the different thicknesses of multiplayer PET film made in accordance with the presently-disclosed subject matter. In short, the two-step process described above induces the biaxial orientation of the PET polymer chains in the easily formable PET film, imparting tensile strength and other desired properties.

TABLE- 1

[00075] Exemplary processing parameters of a PET film made in accordance with the presently- disclosed subject matter as compared to available different thickness of thermoformable film with same Co-polymer content.

Example 2

Measured properties of the Inventive samples with different co-polymer content, with the measurement comparative examples of thermoformable film 100 for puncture force, stiffness and depth and mechanical analysis.

[00076] Further examine the properties of the thermoformable PET films made in accordance with the presently-disclosed subject matter, the thermoformable PET film and control film were tested on a Dynamic Mechanical Analysis (DMA) machine at various temperatures and the modulus properties at low stretching was measured. Conditions of testing were as described by ASTM D 882. Table-2 and 3 below show the results of the testing for tensile strength, elongation and puncture force, as critical functional parameters.

[00077] Lloyd universal tester is used to measure tensile, elongation and puncture properties of 1" wide test specimen. The Lloyd tensile tester has an enclosed chamber, which is temperature controlled, and the test specimen is pulled by placing between set of grips. The tensile strength is reported on HMI at various set temperatures.

TABLE - 2

[00078] Exemplary analysis parameters of a PET film made in accordance with the presently- disclosed subject matter as compared to available different type of Co-polymer thermoformable film 100 in Table-2.

TABLE-3

[00079] Exemplary mechanical analysis parameters of a PET film made in accordance with the presently disclosed subject matter as compared to available different type of thickness thermoformable film 100 with similar co-polymer content in Table-3. Best mechanical and functional properties observed in 180-micron thickness in Table-3

Example 3

Measurement of Thermoformability and Evaluation of cavity formation

[00080] Following production of the PET films, the thermoformability of the films was subsequently evaluated and analyzed. Briefly, to measure the thermoformability of the films, an aluminum block was assembled to form a circular mold 4 inches in diameter and 1.25 -inch-deep (volumc~257 ml) with a vacuum line attached to the base. A 6.5 inch ² of the film to be tested was placed over the open top of the mold and held in place with a flange to form an airtight seal. The mold was then placed into a preheated forced-air oven at a temperature 70°C to 80°C above the target forming temperature. As the film warmed, the surface temperature was monitored by a thermocouple and when the target temperature reached, a vacuum of 26.5 inches of Hg below ambient was applied for 5 seconds (controlled using a PLC). The mold was then immediately removed to avoid shrinkage. To measure the volume, a very light vacuum (approximately 1 inFig) was applied to pull the formed film into shape without further deforming the film, and water from a graduated cylinder was then carefully poured until the surface tension snapped the meniscus to the lower edge of the flange.

[00081] To evaluate the formability of various films, cavity was formed using different types of films on automatic cupping tester (model no. SP4300 from TQC B.V.) as per ISO 1520 to a specified depth or defining the minimum depth at which the test fails by gradually increasing the indentation. The ISO- 1520 standard requires film to be slowly deformed at a steady rate between 0.1 mm/s and 0.3 mm/s without interruption. The Automatic Cupping Tester is driven by a micro-step controlled electro motor which allows precise and steady deformation with 0.01 mm steps. Automatic Cupping Tester is equipped with micrometer to measure the depth of the cavity formed, if the test passed the specific depth was recorded.

[00082] The depth of the cavities can also be verified by using Vernier caliper keeping the beam edge on the multilayer film surface and opening the jaws such that depth measuring blade enters into the cavity and touches the lower surface of the cavity. The depth reading is noted down from the scale in mm.

Table -4 - Evaluation of cavity formation

[00083] Upon analysis of the results from the comparison of the thermoformable PET film to the PVC film at thicknesses of 180 pm, it was found that the thermoformable PET film exhibited an increased machine direction elongation percentage, an increased transverse direction elongation percentage, and increased machine direction tensile strength, an increased transverse direction tensile strength, and a higher increase in maximum volume as compared to the PVC film and as described in Table- 4.

Table-5 - Different process parameter and thickness of 180 mic thermoformable film 100.

[00084] Exemplary cavity formation parameters of a PET film made in accordance with the presently-disclosed subject matter as compared to available different process parameter and thickness of 180 mic thermoformable film 100 in Table-5. Not much variation is observed in the final film w.r.t. - Blister Cavity Depth, Cavity Formation, Film Shrink and Stretch Mark.

[00085] Parameters constant for all Trials - a) Pressure of Plunger: 4.5 Kg. b) Speed : 22 Cycles/min.

ADVANTAGES OF THE PRESENT INVENTION

[00086] The present invention provides a multilayer thermoformable film.

[00087] The present invention provides a multilayer thermoformable film that replaces poly vinyl chloride (PVC) film with polyester-based film.

[00088] The present invention provides e a multilayer thermoformable film that produces wider BOPET line.

[00089] The present invention provides a multilayer thermoformable film that is cost effective.

[00090] The present invention provides a multilayer thermoformable film that is non carcinogenic and environment friendly.