TECHNICAL FIELD
[001] This invention is directed to a mono-layer film. In particular, the present invention relates to a thermoformable packaging film. More particularly, the present invention relates to thermoformable blister packaging film used for blister packaging of medicines and pharma/edible products.
BACKGROUND
[002] 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 specifically or implicitly referenced is prior art.
[003] The 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-seal ability, 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.
[004] In this regard, within the flexible packaging, there is often a need to create semi rigid or rigid 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 cold / 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.
[005] Heating of thermoformable web can be performed by thermal, induction, or radiant sources from one side or both sides of the web thickness. Thermal heating, however, is the most preferred methodology due to simplicity and cost considerations. Furthermore, the creation of the cavity from a thermoforming web-stock can be assisted with air pressure or vacuum application. The negative pressure (vacuum) on the bottom side of a flat web over a mold cavity provides a suction force to mould the heated web stock into the final desired shape as per cavity. Creation of the cavity 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 web into the cavities for forming.
[006] Other common methods of cavity formation include the use of a pressure piston to form the desired shape. Flat web-stock may be inserted into the mold press and under pressure such that a permanent well is formed in flexible films and layer. Indeed, such cold forming of aluminum foil containing layer is a common methodology for the production of blister materials in the pharmaceutical markets. For instance, U.S. Pat. No. 4,537,312, which describes the construction of foil blister packaging that is particularly suited for tamper evident pharmaceutical packaging.
[007] 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.
[008] 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 with good puncture resistance and are thus well suited for thermoforming and cold forming processes. Within the forming 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-polymers, 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 elongational 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.
[009] 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.
[010] 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.
[011] 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.
[012] 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.
[013] 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, 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
[014] It is an object of the present invention to provide a monolayer blister forming film.
[015] It is another object of the present invention to provide a monolayer blister forming film that replaces poly vinyl chloride (PVC) film with polyester-based film.
[016] It is another object of the present invention to provide a monolayer blister forming film that can be produced on wider & high speed BOPET line.
[017] It is another object of the present invention to provide a monolayer blister forming film that is cost efficient.
[018] It is another object of the present invention to provide a monolayer blister forming film that is non-carcinogenic.
SUMMARY
[019] This invention is directed to a monolayer film. In particular, the present invention relates to a thermoformable packaging film. More particularly, the present invention relates to thermoformable blister packaging film used for packaging medicines, medical devices and pharma / edible products.
[020] An aspect of the present invention provides a monolayer blister forming film comprising a composite structure having single layer, said monolayer film structure comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer.
[021] According to an aspect, total thickness of the monolayer blister forming film is in a range of 150~300 microns by thickness tester.
[022] According to an aspect, the outer surface of the monolayer is heat-sealable directly to a lacquer coated aluminum foil to be used as lidding substrate.
[023] According to an aspect, the copolymer of PET is isophthalic acid based.
[024] According to an aspect, the least single main-extruded layer is biaxially-oriented PET (BOPET) having melting point in a range of 190°C to 220°C as measured by Differential Scanning Calorimetry (DSC), as per ASTM D 3418 upon a first heating
[025] According to an aspect, machine direction and transverse direction total elongation is in a range of 150% to 350% measured as per ASTM D 882
[026] According to an aspect, crystallization temperature of extruded layer is in the range of 90°C to 156°C.
[027] According to an aspect, stretching ratio in machine direction and transverse direction is in a range of 2.0% to 3.3%.
[028] Another aspect of the present invention provides a blister package for packaging a product, the blister package comprising of a monolayer blister forming film having single layer, said monolayer film structure comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer, wherein the top side is a heat sealable layer and having an outer surface opposite the bottom layer, wherein the outer surface of the top side is heat-sealable directly with a heat sealable film to be used as lidding substrate of the blister package.
[029] According to an aspect, the lidding with heat sealable layer comprises any of a lacquer coated aluminum, and a heat sealable PET (HSPET) film.

BRIEF DESCRIPTION OF THE DRAWINGS
[030] 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.
[031] FIG. 1 illustrates an exemplary representation of monolayer blister packaging film (100) in accordance with an embodiment of the present invention.
[032] FIG. 2 illustrates an exemplary representation of monolayer blister packaging film (100) with formed well or a cavity in accordance with an embodiment of the present invention.
[033] FIG. 3A illustrates exemplary representation of steps for forming a blister package (300) starting from a web of monolayer film (304) and a web of lidding substrate (302) in accordance with an embodiment of the present invention.
[034] FIG. 3B illustrates an exemplary representation of blister package (300) in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[035] 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.
[036] 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.
[037] This invention is directed to a monolayer film. In particular, the present invention relates to a thermoformable packaging film (100). More particularly, the present invention relates to thermoformable blister packaging film (100) used for packaging medicines, medical devices and pharma/edible products etc.
[038] An aspect of the present invention provides a monolayer blister forming film (100) comprising a composite structure having single extruded layer, said monolayer film structure comprises a polyethylene terephthalate (PET) copolymer consisting essentially of 12% to 15.5% by weight of the copolymer.
[039] According to an aspect, total thickness of the monolayer blister forming film is a range of 150~300 microns or more preferably 150~250 by thickness tester.
[040] According to an aspect, the outer surface of the top side is heat-sealable directly to a lacquer coated aluminum foil to be used as lidding substrate (301).
[041] According to an aspect, the copolymer of PET is essentially Isophthalic acid based.
[042] According to an aspect, the single main-extruded layer is biaxially-oriented PET (BOPET) having: melting point in a range of 190°C to 220°C as per ASTM D3418, as measured by differential scanning calorimetry (DSC) upon a first heating,
[043] According to an aspect, machine direction and transverse direction total elongation is in a range of 150% to 350% as per ASTM D 882. According to an aspect, crystallization temperature of extruded main layer is in the range of 90°C to 156°C.
[044] According to an aspect, stretching ratio in machine direction and transverse direction is in a range of 2.0% to 3.3%.
[045] Another aspect of the present invention provides a blister package (300) for packaging a product, the blister package (300) comprising: a monolayer blister film structure comprises polyethylene terephthalate (PET), and a copolymer consisting essentially of 12% to 15.5% by weight of the copolymer by gas chromatography, wherein the top side of blister forming film (100A) is heat-sealable directly to a heat sealable lidding inner layer (320) of the lidding substrate (301) of the blister package (300).
[046] 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 non-limiting examples in this document.
[047] FIG. 1 illustrates an exemplary representation of single layer of blister packaging film (100) in accordance with an embodiment of the present invention.
[048] In an embodiment, the present invention provides a blister packaging film (100) (hereinafter interchangeably referred to as formable film (100) or thermoformable film (100) or blister film (100) or mono–extruded thermoformable film (100)). The blister forming film (100) comprises a composite structure of single main-extruded layer. The top side of monolayer blister forming film (100A) is the sealing side and bottom side of blister forming film (100B) is the non-sealing side of monolayer blister forming film (100).
[049] The presently-disclosed subject matter includes blister forming 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.
[050] In some embodiments, a blister forming film (100) is provided that comprises one BOPET layer. In some embodiments, such a blister forming film (100) includes a metaphase with a melting point of about 190°C to 220°C as measured by Differential Scanning Calorimetry (DSC) as per ASTM D3418 upon a first heating. As shown in FIG. 2 the thermoformed depth comprises a depth or cavity or well. The well comprises an inner side (202) and outer side (204). The inner side (202) of the well is utilized for storage of product that includes edible items, or medical or pharmaceutical items etc.
[051] In some embodiments, the formable film has a machine direction total elongation percentage of about 150% to about 350%, measured as per ASTM D882. In some embodiments, the formable film has a transverse direction total elongation of about 150% to about 350%, measured as per ASTM D882.
[052] In some embodiments of the presently-described blister forming 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 blister forming film (100) described herein, the metaphase of each of the biaxially-oriented polyethylene terephthalate (BOPET) layer 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 blister forming 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 blister forming film (100) have a machine direction tensile strength of greater than about 1000 kgf/cm2 at 25°C; a transverse direction tensile strength of greater than about 1000 kgf/cm2 at 25°C; a machine direction total elongation percentage measured at 25°C of greater than 150%; and a transverse direction of greater than 150%.
[053] In some embodiments, a formable film is provided having single BOPET layer, and in certain embodiments, can also include silica.
[054] In some embodiments, a process for producing a formable film is provided that includes an initial step of producing one BOPET layer. In some embodiments, the process then includes: a step of stretching the BOPET layer in a machine direction at a temperature of about 64°C to about 82.5°C, at a draw percentage of about 200% to about 286%, or a combination thereof; and a step of stretching the BOPET layer in a transverse direction at a temperature of about 83°C to about 130°C, at a draw percentage of about 280% to about 330%, or a combination thereof. In some embodiments, subsequent to the stretching steps, the process includes crystallizing the layer at a temperature of about 90°C to about 156°C.
[055] 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 as per . In some embodiments, the temperature is varied according to the number of layer, 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.
[056] 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 55°C to 59°C. In some embodiments, the formable film is allowed to relax at a temperature about from 55°C to 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 2.0%. In some embodiments, the relaxation percentage is about 3.3%.
[057] In some embodiments of the presently-disclosed blister forming film (100), a formable film is provided that includes one BOPET layer, and that includes a metastable phase in which the metastable phase has a phase transition temperature of about 50°C to 78°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.
[058] In yet other embodiments of the presently-disclosed subject matter, the blister forming film (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 film including one BOPET film with the formable film 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 films.
[059] In some embodiments of the presently-disclosed monolayer structure, a monolayer 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, the mono BOPET layer includes an isophthalate copolyester.
[060] 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, as per ASTM D3763.
[061] 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 mono BOPET layer, and having a metaphase configured to increase a property of the formable film. In some embodiments, subsequent to providing the monolayer structure, the layer structure then undergoes cold or hot forming into a desired shape. In some embodiments, the BOPET layer used to produce the layer structure 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.
[062] FIG. 3A illustrates exemplary representation of steps for forming a blister package (300) starting from a web of main-extruded monolayer film (304) and a web of lidding substrate (302) in accordance with an embodiment of the present invention.
[063] In an embodiment, the process for producing blister package (300) comprises a web of monolayer blister film (304). The monolayer blister film (100) using thermal or cold forming technique is used for making well or cavity or blister on the blister forming film (100). The monolayer blister forming film (100) is pressed between a forming top plate (312-1) and bottom forming cavities (312-2) to acquire the desired cavity configuration. The desired cavity configuration is not limited to the drawing disclosed in this patent application and may vary according to the feeding product shape. The formed cavities (316) along the length are filled with product (314). After product feeding (314) the lidding inner layer (320) is sealed with the top surface (100 A) of the monolayer blister forming film (100) to get the final blister package (300) with product and lidding. After the well or blister have been formed, a product (314) is inserted in the created wells. After the product (314) is inserted, a lidding layer (306), received from a web of the lidding substrate (302), is applied that is heat sealed to pack thereby completing the packaging of the product inside the wells or cavities or blister. The heat-sealed blister package is cut off after a predetermined length thereby forming the blister package (300), as shown in FIG. 3B. Material of the lidding layer comprises lacquer coated aluminum foil, heat sealable PET (HSPET) film etc.
Examples
Example 1
Preparation of Monolayer Thermoformable PET Film
[064] Polyethylene terephthalate (PET) film was prepared via a conventional sequential biaxial orientation machine having a single screw mainline extrusion train and a twin screw sub-extrusion process. PET pellets having a desired intrinsic viscosity were fed into the main extrusion line, while a blend of Co-polymer PET pellets was feed into the extrusion process, such that the materials could be melted separately and then mixed together in a feed-block to produce a desired molten phase in a monolayer extrusion T-die. The monolayer PET material emerging from the extrusion die was then quenched on a chilled casting drum to produce a thick, amorphous film structure.
[065] 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 monolayer 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
Thermoformable Blister Film Thickness 120
µm 150
µm 160
µm 180
µm 200
µm 250
µm 300
µm
Die Adapter 259.5°C 260° C 259.9°C 260° C 260° C 260° C 260° C
Chill roll temperature 18° C 22.5° C 23° C 22.8° C 24° C 23.2° C 23.2°C
MDO Temperature (1-2) 64°C 78° C 77.5° C 77.9° C 77.0° C 77.2° C 78.5°C
MDO Temperature (3-6) 70.2° C 82.5° C 81° C 80° C 79.5° C 79.5° C 79.5°C
MDO Ratio 2.00 2.80 2.85 2.86 2.75 2.85 3.30
TDO stretching Temperature
(S1-S2) 83° C 103° C 105° C 111° C 112° C 120° C 120° C
TDO stretching Temperature 108° C 110° C 112° C 118° C 122° C 130° C 130° C
TDO crystallizing Temperature (S3) 150° C 160° C 165° C 170° C 175° C 180° C 180° C
TDO Relax Temperature 59° C 55° C 56° C 57° C 58° C 55° C 55° C
TDO Ratio ?2.00 3.25 3.26 ?3.26 ?3.03 ?2.80 ?3.30

[066] Exemplary processing parameters of a PET film made in accordance with the presently disclosed subject matter as compared to available different thickness of thermoformable blister 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.

[067] 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 in ASTM D882. Table-2 and 3 below show the results of the testing for tensile strength, elongation and puncture force, being critical functional parameters.
[068] Lloyd universal tester is used to measure tensile, elongation and puncture properties of 25mm 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
Sr. No. Sample description
(By weight of Co-polymer) Puncture Load
(Kgf) Stiffness (N/mm) Depth in mm Melting Point (°C) Crystallization temp.
(°C)
1 PVC 30.0 - 31.0 30.9 13.3 - 13.5 170-210 -
2 PET
(0% Copolymer) 17.2 - 19.0 12.1 11.8 - 12.8 253 - 256 150-200
3 PET
(2.7% Copolymer) 14.4 - 15.5 14.9 19.4 - 20.5 244-248 160-175
4 PET
(3.6% Copolymer) 12.5 - 14.2 14.2 18.5 - 20.3 242- 246 155-165
5 PET (7.2% Copolymer) 13.6 - 14.3 13.9 18.3 - 21.6 234-238 140- 160
6 PET
(10% Copolymer) 15.5 - 20.6 14.2 18.6 - 21.5 220-235 130-160
7 PET
(12% Copolymer) 15.2 - 21.5 14.9 19.2 - 21.0 210-220 125-155
8 PET
(13.5% Copolymer) 22.5 - 24.6 15.2 19.2 - 21.4 212-216 120-156
9 PET
(15.5% Copolymer) 25.2 - 26.9 16.2 20.1 - 21.3 190-210 90- 123

[069] Exemplary analysis parameters of a PET film made in accordance with the presently-disclosed subject matter as compared to available different types of Co-polymer thermoformable blister film (100) in Table-2.
TABLE-3
Sr.
No. Section Units 120
µm 150
µm 160
µm 180 µm 200
µm 250 µm 300
µm
Mechanical Properties MD
1 Tensile Strength Kg/cm2 1019 ~1526 1386~1897 1676~1924 1446~1761 1361~1554 1226~1389 1271~ 1480
2 Elongation % 294 ~ 350 224~
320 220~
260 315~
350 222~
238 198~
248 150~
180
3 F-5 Value Kg/cm2 680 ~ 744 990~1120 1150~1277 1005~1232 928~1096 780~
999 865~
1154
Mechanical Properties TD
4 Tensile Strength Kg/cm2 1417~1965 1754~1777 1874~1922 1681~1709 1422~1590 1278~1540 1222~1559
5 Elongation % 188 ~ 216 207~
213 241~
268 257~
298 229~
263 192~
229 290~
350
6 F-5 Value Kg/cm2 989 ~ 1003 1002~1066 1150~1200 948~1052 872~
996 948~1032 966~
1027
Puncture Test
7 Penetrating Power N 49.5 51.2 55.3 49.1 46.95 46.2 45.9
8 Penetrating Power/
Thickness N/mm 135.8 232.3 197.9 205.7 218.3 232.3 238.4
9 Work until break MJ 58.8 76.2 79.6 84.3 96.9 69.9 71.2

[070] 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 of blister forming film (100) with similar co-polymer content in Table-3. Best mechanical and functional properties observed from 150-microns to 200-microns thickness in Table-3
Example 3
Measurement of Thermoformability and Evaluation of cavity formation
[071] 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 (volume ˜257 ml) with a vacuum line attached to the base. A 6.5 square inch 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 up to or less than 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 inch Hg) 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. The remaining volume of the graduated cylinder was then noted and subtracted from the initial volume to determine the displacement. Relative formability could also be judged by comparing the volumes of plain films, the thermoformable PET film, and co-polymer based films formed under the same conditions.
Table-4 - Evaluation of cavity formation
Sr. No. Sample Description
Thickness in microns Load
(Kgf) Load (Kgf) Average Stiffness (N/mm) Cavity formation in mm Load (Kgf) to create 13.7 mm cavity

1 PVC 180 30.4 - 31.5 30.9 30.9 13.4 30.2
2 PVC 200 25.11 25.11 28.11 14.1 24.9

3 Competitor- 1 150 53.5 - 62.3 57.9 57.9 16.8 55.3
Competitor - 2 175 61.2 - 67.9 61.7 61.7 16.4 63.4
4 PET Sample - 3 120 38.33 38.33 23.5 36.2 22.9
5 PET Sample - 4 150 29.1 18.3 21 35.8 17.1
6 PET Sample - 5 160 47.4 47.4 39.18 39.7 30.7
7 PET Sample - 6 (Left) 180 68.9 69.91 29.16 31.5 31.2
8 PET Sample - 6 (Center) 180 72.9 72.94 33.33 30.2 30.8
9 PET Sample - 7 (Left) 200 73.5 73.5 29.19 35.2 31.2
10 PET Sample - 7 (Center) 200 79.3 74.6 31.8 36.4 31.6

[072] Upon analysis of the results from the comparison of the thermoformable PET film to the PVC film at thicknesses of 180 µm, 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 parameters with thermoformable blister film (100) of thickness 180 microns and 200 microns.
Sr. No. Particulars Unit Thermoformable PET
(180 and 200 microns)
Trial
01 Trial
02 Trial
03 Trial
04 Trial
05 Trial 06
A) Parameters
1 Thickness of film Microns 180 200 180 200 180 120
1 Depth of Plunger from Top mm 28 28 28 28 28 28
2 Preheating Temp. OC 78 78 85 85 82 82
Upper Plate
3 Lower Plate OC 78 78 85 85 82 82
4 Chiller Temp. OC off off off off 22OC 22OC
B) Results
5 Blister Cavity Depth mm 9.4-9.8 9.5-9.8 9.7-10.1 9.8-10.2 9.8-10 9.85-10.20
C) Observations
a) Cavity Formation OK OK OK OK OK OK
b) Film Shrink No No No No No No
c) Stretch Marks
Observed No No No No No No
[073] Exemplary cavity formation parameters with a PET film made in accordance with the presently-disclosed subject matter as compared to available different process parameter and thickness of 180 microns and 200 microns thermoformable blister 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.
[074] Parameters constant for all Trials –
a) Pressure of Plunger: 4.5 Kg/cm2 .
b) Speed : 22 Cycles/min.
ADVANTAGES OF THE PRESENT INVENTION
[075] The present invention provides a monolayer blister forming film (100).
[076] The present invention provides a monolayer blister forming film (100) that replaces poly vinyl chloride (PVC) film with polyester-based film.
[077] The present invention provides a monolayer blister forming film (100) that can be produced on wider BOPET line.
[078] The present invention provides a monolayer blister forming film (100) that is cost effective.
[079] The present invention provides a monolayer blister forming film (100) that is non carcinogenic.

List of Reference Numerals as described in complete specification:
100: Monolayer blister forming film
100 A: Top side of monolayer blister forming film
100 B: Bottom side of monolayer blister forming film
202: Inner side of well/formed cavity
204: Outer side of well/formed cavity
300: Blister package
301: Lidding substrate
302: Web of the lidding substrate
304: Web of monolayer blister forming film
306: Lidding Outer layer
308: Heating plate
312-1: Forming top plate
312-2: Bottom forming cavities
314: Product
316: Formed cavities
318: Heat sealing plate
320: Lidding inner layer

We Claim:

1. A monolayer blister forming film (100) comprising of a mono-extruded layer, said monolayer film (100) comprises from 12% to 15.5% by weight of the copolymer polyethylene terephthalate (PET).
2. The monolayer blister forming film (100) as claimed in claim 1, wherein the monolayer film Microns (100) comprises from 12.5% to 13.5% by weight of the copolymer polyethylene terephthalate (PET).
3. The monolayer blister forming film (100) as claimed in claim 1, wherein the monolayer film has a thickness ranging from 150 microns to 300 microns.
4. The monolayer blister forming film (100) as claimed in claim 1, wherein the monolayer film has a thickness ranging from 150 microns to 250 microns.
5. The monolayer blister forming film (100) as claimed in claim 1, wherein the top side of the monolayer blister forming film (100 A) is heat-sealable lacquer coated on lidding outer layer (306).
6. The monolayer blister forming film (100) as claimed in claim 1, wherein the copolymer of PET is isophthalic acid.
7. The monolayer blister forming film (100) as claimed in claim 1, wherein the monolayer film is biaxially-oriented PET (BOPET) having melting point ranging from 190°C to 220°C as measured by Differential Scanning Calorimetry (DSC).
8. The monolayer blister forming film (100) as claimed in claim 1, wherein total elongation of the monolayer film is in machine direction and transverse direction ranging from 150% to 350%.
9. The monolayer blister forming film (100) as claimed in claim 1, wherein the monolayer film has a crystallization temperature ranging from 90°C to 156°C.
10. The monolayer blister forming film (100) as claimed in claim 1, wherein stretching ratio in machine direction and transverse direction is ranging from 2.0% to 3.3%.
11. A blister package (300) for packaging a product (314) comprising:
a mono-extruded layer blister forming film (100); and
a lidding substrate (301);
wherein the top side of monolayer blister forming film (100A) is heat sealable with a heat sealable lidding inner layer (320) of the lidding substrate (301);
wherein the monolayer blister forming film (100) is copolymer polyethylene terephthalate (PET) consisting essentially of ranging from 12% to 15.5% by weight of the copolymer.
12. The blister package (300) as claimed in claim 11, wherein heat sealable lidding inner layer (320) comprises a heat sealable lacquer coating.
13. The blister package (300) as claimed in claim 11, wherein monolayer blister forming film (100) has a thickness of ranging from 150 microns to 300 microns.
14. The blister package (300) as claimed in claim 11, wherein the monolayer blister forming film (100) comprises of isophthalic acid based copolymer of PET.
15. The blister package (300) as claimed in claim 11, wherein the monolayer blister forming film (100) is a biaxially-oriented PET (BOPET) layer having a melting point ranging from 190°C to 220°C as measured by Differential Scanning Calorimetry (DSC) upon a first heating and a thermoforming depth volume of about 200% or less.
16. The blister package (300) as claimed in claim 11, wherein the monolayer blister forming film (100) is stretched in machine direction and transverse direction of ranging from 150% to 350%.
17. The blister package (300) as claimed in claim 11, wherein the monolayer blister forming film (100) has a crystallization temperature of ranging from 90°C to 156°C.
18. The blister package (300) as claimed in claim 11, wherein the monolayer blister forming film (100) has a stretching ratio in machine direction and transverse direction of ranging from 2.0% to 3.3%.