Sustainable Blister Packaging

Abstract

The blister package includes a thermoformed web (30) having a product cavity (10) formed therein, the web including at least two coextruded layers: a main layer (34) including HDPE and up to 2% of a first additive, and a sealing layer (36) including HDPE and up to 50% LLDPE; and a flat lid (20) including at least three coextruded layers: an outer HDPE layer (22) including up to 5% of a second additive, a middle HDPE layer (24) including a third additive suitable for reducing elongation at break, and an inner sealing layer (26), the thermoformed web (30) and the flat lid (20) being heat-sealed to each other. The invention further relates to a packaged pharmaceutical or nutritional product including such a blister package and a solid pharmaceutical or nutritional product (40) contained in the cavity. The invention also relates to a method for producing such a product.

Description

[Technical field]

[0001] The present invention relates to a sustainable blister package comprising two multi-layer films and a method for producing such a blister package containing a pharmaceutical or nutritional product. [Background technology]

[0002] Blisters are frequently used as packaging for solid pharmaceutical or nutritional products (e.g., tablets, caplets, lozenges, gel tabs, gum). A conventional blister includes a thermoformed web with a cavity for the product formed therein and a lid that is sealed onto the web to close the cavity. Blisters provide good physical protection and, depending on the materials used, can provide an oxygen and / or moisture barrier to prevent degradation of the product contained therein. Blisters also allow removal of one product, i.e., a single dose of a medication, without altering the packaging of other products.

[0003] There are several challenges with blister packaging. One challenge is that, at least for pharmaceutical products, the package must preferably be child-resistant, i.e. opening the blister package must be difficult for a child to use so that the child cannot access the contents. At the same time, opening the package must be easy enough for older consumers or those with deformed joints or other conditions that affect dexterity. Packages that meet these criteria are commonly called Child-Resistant Senior-Friendly (CRSF). Detailed criteria for CRSF certification are set out in the European standard ISO 14375 for non-reclosable child-resistant packages for pharmaceutical products, or in the corresponding US standard CFR Title 16, Part 1700.20. In the case of blisters, the consumer must break the lid to use the product. This is done by pressing the thermoformed web in which the cavity is formed until the solid product contained in the cavity breaks the lid. The ease of opening depends heavily on the material properties of the film used for the lid, and it can be difficult to reconcile the conflicting objectives of CRSF.

[0004] Another challenge with blister packaging is sustainability. Currently, blisters generally use a bottom film layer and a top film layer sealed together. The bottom film layer, in which the cavity for the product is formed, is referred to herein as the "web" and is usually thermoformed. The bottom film layer is generally based on halogenated polymers such as polyvinyl chloride (PVC), polyvinylidene chloride (PVdC), or fluorinated polymers such as poly(chlorotrifluoroethylene) (PCTFE). However, these polymers are not a preferred solution from an environmental point of view, as they can generate hazardous by-products during manufacture, processing, and disposal. Non-halogenated alternatives such as polyethylene terephthalate (PET), polypropylene (PP), or multi-layer structures based on olefins including barrier layers, as described, for example, in US Pat. No. 9,962,913 or EP 2520615 B1, are also available on the market.

[0005] The top film layer, commonly and herein referred to as the "lid", is usually an aluminium foil, coated on one side with a heat seal layer and on the other opposite side with a lacquer, which prevents damage to the aluminium. To comply with the above CSRF requirements, this lacquer may be completed by a reinforcing layer to increase the force required to open the blister. This alternative layer may be paper-based or polymer-based, such as polyethylene terephthalate (PET).

[0006] The lid and the web are usually attached to each other by heat sealing, which is very difficult to separate due to the high affinity between the heat seal layer of the lid and the material of the web. Heat sealing can be performed using a heated seal roll or a heated seal plate. The resulting blisters therefore pose recycling challenges since they are made of a combination of aluminum and polymer. For example, blisters with an aluminum lid and a thermoformed polymer web cannot be recycled mechanically. Pyrolysis is conceivable, but this method is not available on an industrial scale, requires a large amount of energy, and in the case of halogenated polymers, requires specific treatments to limit the toxic gases produced by these polymers during the recycling process.

[0007] One of the commercially proposed alternatives to these conventional blisters based on aluminum lids and halogenated thermoformed webs is a blister using a polypropylene (PP) web and a PP lid, such as the commercially available Etimex Purelay®. Such PP blisters are recyclable without the need to separate the lid and the web, since both components, the lid and the web, are made from the same polymer. However, specific equipment is required to thermoform PP, which significantly increases the production costs. Furthermore, it is difficult to achieve good adhesion of the PP lid on the PP web. For this reason, it is particularly difficult to obtain CRSF certification for blisters based on PP webs and PP lids. Summary of the Invention [Problem to be solved by the invention]

[0008] Therefore, at least one of the objectives underlying the present invention is to create a blister for pharmaceutical and nutritional products that provides the physical protection and barrier properties of a conventional blister, but which is more environmentally friendly, complies with child-resistant and senior-friendly standards, and can be manufactured and processed at a competitive price.

[0009] Thus, there is a need to develop improved materials, methods, and devices that can overcome one or more of the above limitations presented by conventional blister designs. The materials, methods, and devices described herein improve upon one or more of these limitations. [Means for solving the problem]

[0010] According to a first aspect of the present invention, - a thermoformed web having a cavity formed therein for the product, the thermoformed web comprising at least two coextruded layers, namely a main layer comprising high density polyethylene (HDPE) and up to 2% of a first additive, and a sealing layer comprising HDPE and up to 50% linear low density polyethylene (LLDPE); - comprising at least three coextruded layers, namely an outer HDPE layer containing up to 5% of a second additive, a middle HDPE layer containing a third additive suitable for reducing the elongation at break, and a flat cover comprising an inner sealing layer, A blister package is provided having a thermoformed web and a flat lid heat sealed together.

[0011] It should be noted that as the term "additive" is used herein, it can refer to one additive or a combination of different additives, and the amounts referred to herein refer to the total amount of additive in the corresponding layer in the case of a combination.

[0012] According to a second aspect of the invention there is provided a packaged pharmaceutical or nutritional product comprising such a blister package and a solid pharmaceutical or nutritional product, such as a tablet or caplet, contained in the cavity.

[0013] According to a third aspect of the invention there is provided a method for producing such a packaged pharmaceutical or nutritional product including such a blister package.

[0014] According to a preferred embodiment of the present invention, - a thermoformed web having a cavity formed therein for the product, the thermoformed web comprising at least two coextruded layers, namely a main layer comprising high density polyethylene (HDPE) and up to 2% of a first additive, and a sealing layer comprising HDPE and up to 50% linear low density polyethylene (LLDPE); - comprising at least three coextruded layers, namely an outer HDPE layer containing up to 5% of a second additive, a middle HDPE layer containing a third additive suitable for reducing the elongation at break, and a flat cover comprising an inner sealing layer, A blister package is provided having a thermoformed web and a flat lid heat sealed together.

[0015] Preferably, the main layer of the web comprises 0.2% to 2% of a first additive. Preferably, the sealing layer of the web comprises 2% to up to 50% of Linear Low Density Polyethylene (LLDPE). Preferably, the outer HDPE layer of the lid comprises 0.2% to 5% of a second additive. Preferably, the middle HDPE layer of the lid comprises at least 0.2% of a third additive suitable for reducing the breaking elongation.

[0016] According to a preferred embodiment of the present invention, the first additive in the main layer of the web is an inorganic additive.

[0017] According to a preferred embodiment of the invention, the second additive in the outer HDPE layer of the lid is an inorganic additive.

[0018] According to a preferred embodiment of the invention, the web has a total thickness before thermoforming of 200-600 μm, preferably 150-500 μm, more preferably 250-400 μm. According to a preferred embodiment of the invention, the lid has a total thickness of 30-300 μm, preferably 50-200 μm, most preferably 80-110 μm.

[0019] According to a preferred embodiment of the invention, the total polyolefin content of the product-free blister package is greater than 90%, preferably greater than 96%.

[0020] According to a preferred embodiment of the present invention, both the web and the lid include an oxygen barrier layer.

[0021] According to a preferred embodiment of the invention, the elongation at break of the lid is less than 20%, preferably less than 10%.

[0022] According to a preferred embodiment of the present invention, the inner sealing layer of the lid is composed primarily of an ethylene copolymer, preferably a copolymer comprising ethylene and vinyl acetate.

[0023] According to a preferred embodiment of the present invention, the inner sealing layer of the lid has a thickness of about 5 to 30 μm, preferably about 15 to 25 μm.

[0024] According to a preferred embodiment of the present invention, the inner sealing layer of the lid (20) comprises up to 2% by weight, preferably up to 1% by weight, of slip agent.

[0025] According to a preferred embodiment of the invention, the third additive in the middle HDPE layer of the lid is an inorganic additive selected from CaCO3, TiO2, talc, chalk, clay, or metal salts.

[0026] According to some embodiments of the present invention, the third additive in the middle HDPE layer of the lid is a polymer that is incompatible with HDPE.

[0027] According to a preferred embodiment of the invention, the seal layer of the thermoformed web comprises 88% to 95% by weight of HDPE and 5% to 12% by weight of LLDPE. Preferably, the LLDPE is a metallocene LLDPE.

[0028] According to a preferred embodiment of the present invention, the thermoformable web further comprises an outer layer comprising a major component of HDPE.

[0029] As HDPE is the main material for the web and lid, the finished blister can be recycled in the mono-material recycle stream without the need to separate the lid and web before recycling. Polyethylene (PE), more specifically high density polyethylene (HDPE), is a good choice from an environmental perspective, as it is the second most recycled polymer. HDPE has good mechanical performance, especially stiffness, and has inherently good moisture barrier performance. Furthermore, it can be easily tailored to the specific needs of blister packaging by adding additives or other polymers to improve or modify certain properties, such as adhesion behavior, barrier properties, and perforation properties. In contrast to most PP-based films, HDPE-based films are suitable for standard-fit thermoforming without plug assist.

[0030] The first additive in the main layer of the web improves the cuttability of the web, thereby facilitating processing. Preferably, the first additive is an inorganic additive, although organic nucleating agents may be used.

[0031] The multi-layer structure of the films used for the lids and webs allows for all the desired properties to be obtained, with each layer providing a specific property such as heat resistance, surface look and feel, moisture or gas barrier, or adhesive strength, etc. Such multi-layer films can be manufactured on an industrial scale by extrusion cast or blown film extrusion.

[0032] The addition of low density polyethylene (LLDPE) to the HDPE in the sealing layer of the web helps to improve its sealing performance, its formability, and its barrier performance.

[0033] To obtain the desired opening force for the lid to pass CRSF certification as specified in ISO 14375, an additive that reduces breaking elongation is added to the middle HDPE layer of the lid, also referred to herein as the "third additive."

[0034] One way to do this can be to adjust the thickness of the lid, another is to adjust the breaking elongation and breaking strength of the film.

[0035] It should be noted that all polymers used in the blister packages of the present invention, particularly polyethylene, may be derived from non-renewable sources such as crude oil, or from renewable sources such as recycled animal or vegetable oils, corn starch, sugar cane, etc. (bio-based or renewable-based polymers).

[0036] According to a preferred embodiment, the web has a total thickness of 200-600 μm, preferably 150-500 μm, more preferably 250-400 μm, before thermoforming. Also according to a preferred embodiment, the lid has a total thickness of 30-300 μm, preferably 50-200 μm, most preferably 80-110 μm. The total thickness of the blister package (between the cavities) is preferably 400-600 μm. With regard to the thickness of the thermoformed web, this thickness is sufficient to provide good thermoforming quality, including a sufficient residual thickness at the top of the cavities after thermoforming, thereby preventing destruction (puncture or breakage). The thickness of the lid is specifically optimized to provide easy opening and still pass child resistance certification.

[0037] In some cases, the total polyolefin content of the blister packaging from which the product is dispensed is greater than 90%, and in some embodiments preferably greater than 96%, which in some cases allows for recycling in the mono-material recycle stream, resulting in high quality recycled polyethylene material.

[0038] Preferably, the multi-layer structure of the web and lid is obtained by co-extrusion blow molding or co-extrusion casting.

[0039] Depending on the packaged product and its stability, an additional oxygen barrier may be required, in which case the web and lid may include an oxygen barrier layer, such as ethylene vinyl alcohol (EVOH) or any other oxygen barrier layer known in the art.

[0040] According to a preferred embodiment, the lid has a breaking elongation of less than 20%, preferably less than 10%. As mentioned above, in some cases, this allows for the desired opening force required for CSRF authentication. Furthermore, this allows for a "clean" opening where removal of one product does not unintentionally open other cavities. Preferably, the breaking elongation is less than 10%. In some embodiments, the lid comprises a thickness of about 100 μm and has a breaking elongation of less than 20% or less than 10%. Preferably, the tensile breaking strength is between 10 MPa and 50 MPa, more preferably between 20 MPa and 30 MPa. In some embodiments, the lid is isotropic. For example, in some cases, the lid has similar properties in each direction, i.e., directional property variations that may be introduced by some processes are minimized.

[0041] According to another preferred embodiment, the sealing layer of the lid is made of or comprises an ethylene copolymer, preferably a copolymer comprising ethylene and vinyl acetate. Optionally, the copolymer comprises ethylene vinyl acetate (EVA) having a vinyl acetate content of 28%. Optionally, the ethylene copolymer enhances the adhesive properties of the lid.

[0042] Preferably, the sealing layer of the lid has a thickness of about 5 to 30 μm, more preferably about 15 to 25 μm.

[0043] According to another preferred embodiment, the sealing layer of the lid comprises a slip agent up to 2% by weight, preferably up to 1% by weight. The role of this slip agent or antiblocking agent is to reduce friction during unwinding of the lid film and when the lid is sealed onto the thermoformed web, thereby avoiding possible blocking of the lid film, especially during unwinding. In some cases, amides are suitable slip and antiblocking agents, such as the slip agent commercialized under the trade name Crodamide® by Croda International Plc.

[0044] According to a preferred embodiment, the second additive in the outer HDPE layer of the lid is an inorganic additive, although organic nucleating agents may also be used.

[0045] According to a preferred embodiment, the third additive in the intermediate HDPE of the lid, which enhances the breaking elongation, is preferably an inorganic additive selected from CaCO3, TiO2, talc, chalk, clay, or metal salts, or combinations thereof. The amount of this additive is preferably less than 20% by weight, more preferably about 2% to 10% by weight, even more preferably 3% to 5% by weight, depending on the additive selected. If a metal salt is used, it may also function as a nucleating agent to improve the moisture barrier performance of the lid. Alternatively, according to another preferred embodiment, the additive is a polymer that is chemically incompatible with HDPE, such as polypropylene, ionomeric ethylene copolymers known as Surlyn®, or polystyrene. Optionally, the additive provides a clear film failure without elongation and maintains the opening force of the lid high enough to pass child-resistant certification according to standard ISO 14375. The intermediate layer of the lid preferably has a thickness of 20 to about 60 μm.

[0046] According to a preferred embodiment, the additive in the outer HDPE layer of the lid is CaCO3 in an amount of up to 2% by weight. The outer layer of the multi-layer lid film may have a higher heat resistance than the other layers of the film since it is in direct contact with the heated sealing roll during the assembly of the blister. The outer layer has a thickness of about 5 to about 30 μm, more preferably about 15 to about 20 μm, and comprises a mixture of HDPE with an addition of up to 5% by weight, preferably up to 2% by weight, more preferably about 0.5% by weight of CaCO3. The addition of such an amount of CaCO3 slightly increases the heat resistance of HDPE from 140° C. to about 145° C., thus allowing an increase in the sealing temperature and therefore improving the seal strength of the lid on the web.

[0047] Text, logos or patterns can be printed onto the outer HDPE layer of the lid. Optionally, a lacquer can be applied over the HDPE layer to protect the printing.

[0048] According to a preferred embodiment, the sealing layer of the thermoformed web comprises 88% to 95% by weight of HDPE and 5% to 12% by weight of LLDPE. Preferably, the thickness of this layer before thermoforming is about 5 to about 30 μm, more preferably about 15 to about 20 μm. Preferably, the LLDPE is a metallocene LLDPE. Preferably, the melt flow index (MFI) of the HDPE is selected within the low viscosity range, for example, from 5 to 20 MFI measured at 190° C. and 2.16 kg, to promote good adhesion. Optionally, a tackifier can be added to the sealing layer to further improve adhesion.

[0049] According to another preferred embodiment, the thermoformed web further comprises an outer layer that comprises HDPE as a major component, i.e., 90% or more HDPE, which outer layer can have a thickness of 5 to about 30 μm and can include a colorant such as TiO2 for a white appearance.

[0050] According to a preferred embodiment of the present invention, the first additive in the main layer of the web is an inorganic additive selected from CaCO3, TiO2, talc, chalk, or clay. Nanoscale fillers or metal salts can also be used. All the above additives can be used alone or in combination. The additives can be added via a masterbatch, and in some cases the carrier is chemically compatible with HDPE. Preferably, the amount of the first additive in the main layer of the web does not exceed 0.5% by weight. If an inorganic additive is used, again preferably, the amount of inorganic additive in the main layer of the web does not exceed 0.5% by weight. This amount is sufficient to ensure a clean cut at the edge of the blister by improving the cuttability of the web film and the resulting blister. Instead of an inorganic additive, an organic nucleating agent may be used. Examples of such organic nucleating agents include ultra-high molecular weight PE, sisal fiber, high modulus PE fiber, or anthracene, although a variety of nucleating agents that can be used with HDPE are known and commercially available.

[0051] The invention also relates to a packaged pharmaceutical or nutritional product comprising any of the blister packages described herein, and a solid pharmaceutical or nutritional product, such as a tablet or caplet, contained in a cavity, the size of which is tailored to the size of the tablet or caplet to limit the movement of the tablet or caplet and prevent mechanical deterioration of the tablet or caplet.

[0052] In accordance with the present invention, a method for producing a packaged pharmaceutical or nutritional product comprises the steps of: - preheating a web material comprising at least two coextruded layers, namely a main layer comprising HDPE and up to 2% of a first additive, and a seal layer comprising HDPE and up to 50% LLDPE; - thermoforming a web material to form a web having cavities therein; - introducing a solid pharmaceutical or nutritional product, such as a tablet or caplet, into each cavity; - preheating a lid material comprising at least three coextruded layers, namely an outer HDPE layer comprising up to 5% of a second additive, a middle HDPE layer comprising a third additive suitable for reducing the elongation at break, and an inner sealing layer; - sealing an inner sealing layer of the lid onto the sealing layer of the web between the cavities using a heated sealing roll; - cutting the resulting product into blister packages of the desired format.

[0053] In some embodiments, the thermoforming described herein is performed using a vacuum to form the preheated web material into a cavity defined by a suitable mold. In addition, mechanical assistance in the form of a plug can optionally be used to force the film into the mold (plug assist), although preferably the thermoforming is performed without a plug assist.

[0054] The sealing step is carried out in a direct heat sealing process, in some cases using a permanently heated heat sealing roll, in other cases a heat sealing plate, at a temperature preferably between 100°C and 160°C, preferably below 145°C, and at a pressure preferably below 5 bar, so that the heat seal strength is sufficient to withstand the pressure exerted when the solid contents are pressed against the lid to be removed. The pressure is preferably applied for a period of 0.2 to 0.5 seconds.

[0055] Preferably, a cooling step is performed after the thermoforming step to prevent the product from being introduced into a hot cavity. Optionally, a cooling step may be performed after the sealing step.

[0056] Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0057] [Figure 1] FIG. 1 is a perspective view of a blister package according to the present invention, with several cavities containing product. [Diagram 2] 1 is a schematic cross-sectional view of the layered structure of a blister package according to the present invention. [Diagram 3] FIG. 2 is a perspective view of the blister package of FIG. 1 after the product has been removed from the cavity. [Figure 4] 1 is a schematic diagram of a manufacturing line in which packaged pharmaceutical or nutritional products according to the present invention are produced. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] The embodiments described herein can be more readily understood by reference to the following detailed description, examples, and drawings. However, the elements, devices, and methods described herein are not limited to the specific embodiments presented in the detailed description, examples, and drawings. It should be recognized that the exemplary embodiments herein are merely illustrative of the principles of the disclosed invention. Many modifications and adaptations will be readily apparent to those skilled in the art without departing from the spirit and scope of the invention.

[0059] Additionally, all ranges disclosed herein should be understood to encompass any and all subranges contained therein. For example, a range specified as "1.0 to 10.0" should be considered to include any and all subranges beginning with a minimum value equal to or greater than 1.0 and ending with a maximum value equal to or less than 10.0, such as 1.0 to 5.3, or 4.7 to 10.0, or 3.6 to 7.9.

[0060] All ranges disclosed herein should also be considered to include the endpoints of the range, unless otherwise specified. For example, a range "between 5 and 10" or "from 5 to 10" or "5-10" should generally be considered to include the endpoints 5 and 10.

[0061] Where only the maximum amount of an ingredient is disclosed, this should be understood to encompass all detectable amounts above zero that one of ordinary skill in the art would consider to have a technical effect.

[0062] 1 is a perspective view of an exemplary blister package 1 having a thermoformed web 30 with a cavity 10 formed therein and a lid 20 sealed onto the web 30. The seal between the lid 20 and the web 30 bonds the lid 20 and the web 30 to one another along the entire contact surface between the lid 20 and the web 30, i.e., everywhere except where the cavity 10 is formed.

[0063] Figure 2 is a schematic cross-sectional view of the multi-layer structure present between cavities 10 in the blister package 1 of Figure 1. The multi-layer structure includes a lid 20 having three layers 22, 24, 26 sealed onto a web having three layers 32, 34, 36.

[0064] The different layers correspond, from top to bottom, to the outer layer 22, the intermediate layer 24 and the sealing layer 26 of the lid, then to the sealing layer 36, the main layer 34 and the outer layer 32 of the web.

[0065] Examples of suitable layer structures are provided below: Tables 1 and 3 provide examples of suitable layer structures for the lid 20, and Tables 2 and 4 provide examples of suitable layer structures for the web 30. The example lid structures shown in Tables 1 and 3 can be combined with each of the example web structures shown in Tables 2 and 4, i.e., the lid structure of Table 1 can be used with the web structure of Table 2 or the web structure of Table 4, and the lid structure of Table 3 can be used with the web structure of Table 2 or the web structure of Table 4.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] [Table 4]

[0070] In the example of Table 1 above, the lid 20 is comprised of an HDPE outer layer 22, an intermediate layer 24, and a sealing layer 26, the HDPE outer layer 22 being 20 μm thick and containing 0.5% CaCO3, the intermediate layer 24 being 65 μm thick and containing 95% HDPE and 5% talc, and the sealing layer 26 being 15 μm thick and containing 99.6% EVA28%, i.e., ethylene vinyl acetate (EVA) with a vinyl acetate content of 28%, and 0.4% amide acting as a slip agent. In the example of Table 3, the talc in the intermediate layer 24 is replaced with 3% nucleating agent.

[0071] For the example in Table 1, the addition of 5% talc to the HDPE of the middle layer 24 reduces the elongation to break. The same is true for the addition of 0.5% CaCO3 to the outer layer 22, and for the example in Table 3, the addition of 3% nucleating agent to the HDPE of the middle layer. The resulting elongation to break is less than 10% for the finished closure 20 having the construction shown in Table 1 and less than 10% for the closure having the construction shown in Table 3, depending on the directional measurement of the closure material, providing the desired level of opening force for CRSF certification.

[0072] In the example of Table 2, web 30 includes a seal layer 36 having a thickness of 20 μm and 90% HDPE and 10% metallocene LLDPE to improve adhesion, a main HDPE layer having 99.5% HDPE and 0.5% talc, and an outer layer of HDPE only having a thickness of 20 μm.

[0073] In the example of Table 2, the material selected for main layer 34 may also include an optional nucleating agent to further enhance moisture barrier properties.

[0074] In the example of Table 4, the web 30 again includes a 20 μm thick seal layer 36, but with 50% HDPE and 50% metallocene LLDPE, which further improves adhesion compared to the web examples of Table 2 and does not lead to adhesion problems during manufacturing. Additionally, the main layer of the example of Table 4 has 98% HDPE and 2% nucleating agent, namely, Milliken HYPERFORM® HPN-20E, which is 1,2-cyclohexanedicarboxylic acid, calcium salt:zinc stearate. The main layer has a thickness of 210 μm. The outer layer is again a 20 μm thick layer of HDPE only.

[0075] As previously mentioned, in some embodiments, an additional oxygen barrier layer can be included in or on the lid 20 or web 30. For the web 30, an EVOH layer (usually between two adhesive layers, also called tie layers) is preferred because the EVOH barrier properties do not change during thermoforming. For the lid 20, an EVOH layer may be used, but a coating that provides an oxygen barrier may be the appropriate choice.

[0076] 3 shows the reaction of lid 20 when an adult presses on blister package 1 to remove a tablet from the blister. Lid 20 bursts around cavity 10, thereby creating an opening through which the tablet can be removed, while all other cavities remain covered by lidding material 20 and the seal between lid 20 and web 30 is intact.

[0077] In another aspect, a method for producing a blister package according to the present invention containing a product will now be described with reference to FIG.

[0078] The 250 μm thick web film 30 is unwound using an unwinder 100, then preheated at 125° C. between two plates in a preheating station 102 and then thermoformed at a temperature of 130° C. in a thermoforming section 104. The thermoforming section 104 is a blister machine from Industria Macchine Automatiche SPA (IMA) designed to produce conventional polyvinyl chloride (PVC) blisters with type C80 lid foil. The line speed can be set at 250 blisters per minute. After the thermoforming step, the thermoformed web is cooled (not shown in FIG. 4) and a tablet feeder 106 feeds the tablets 40 into the cavities 10. A second unwinder 108 unwinds the 100 μm thick lid film 20. The lidding film 20 is then preheated at a temperature of 110° C. on a preheat roll 110 and heat sealed onto the thermoformed web 30 using a heat seal roll 112 and a chilled format roll 114 at 140° C. and 5 bar pressure. A direct contact heat seal established a sealed connection between the sealing layer 26 of the lidding film 20 and the sealing layer 36 of the thermoformed web film 30. In this sealing step, the lidding film 20 and the thermoformed web film 30 are between a first side of a direct contact heat sealer, the heated seal roll 112, and an opposing second side of the direct contact heat sealer, the chilled format roll 114. The heated seal roll 112 is in physical contact with the outer layer 22 of the lidding 20, and the chilled format roll 114 is in physical contact with the outer layer 32 of the web 30. Heat and pressure are applied by the heated seal roll 112 for a period of time to provide a direct contact heat seal between the two films 20, 30. The cooling format roll 114 effects cooling to a temperature below 25° C., for example about 12° C., to limit deformation due to plastic behavior of the thermoformed blister web 30. The cooling format roll 114 is cut to the shape of the thermoformed blister for direct contact with all sides of the thermoformed cavity.

[0079] The combination of thermoformed web 30 with tablets 40 in the cavities and lid 20 sealed onto web 30 can be embossed or printed at this stage to display variable data such as lot number, expiration date, or place of manufacture. The blisters are then punched or cut at cutting station 116 and ready for packaging.

[0080] The heat seal between the thermoformed web 30 and the lid 20 is of sufficient quality to pass a leak test in which the completed blister package 1 is placed in a vacuum chamber reduced to less than 2 bar for 2 minutes, the vacuum chamber being filled with methylene blue dye mixed with water.

Claims

1. - a thermoformed web (30) in which a cavity (10) for the product is formed, comprising at least two coextruded layers, namely a main layer (34) comprising HDPE and up to 2% of a first additive, and a sealing layer (36) comprising HDPE and up to 50% LLDPE; - a flat cover (20) comprising at least three coextruded layers, namely an outer HDPE layer (22) containing up to 5% of a second additive, a middle HDPE layer (24) containing a third additive to reduce elongation at break, and an inner sealing layer (26), The thermoformed web (30) and the flat lid (20) are heat sealed together in a blister package.

2. 2. The blister package of claim 1, wherein the first additive in the main layer (34) of the web (30) is an inorganic additive.

3. 3. A blister package according to claim 1 or 2, characterised in that the second additive in the outer HDPE layer (22) of the lid (20) is an inorganic additive.

4. 4. The blister package of any one of claims 1 to 3, characterized in that the first additive in the main layer (34) of the web (30), the second additive in the outer HDPE layer (22) of the lid (20), and the third elongation reducing additive in the intermediate HDPE layer (24) of the lid are all present in an amount of at least 0.2% in each layer.

5. 5. A blister package according to any one of claims 1 to 4, characterised in that the web (30) has a total thickness, before thermoforming, of 200 to 600 μm and / or the lid (20) has a total thickness of 30 to 300 μm.

6. A blister package according to any one of claims 1 to 5, characterised in that the total polyolefin content of the blister package without product is greater than 90%.

7. A blister package according to any preceding claim, characterised in that both the web and the lid comprise an oxygen barrier layer.

8. A blister package according to any one of claims 1 to 7, characterised in that the breaking elongation of the lid is less than 20%.

9. A blister package according to any one of claims 1 to 8, characterised in that the inner sealing layer (26) of the lid (20) is made from an ethylene copolymer.

10. A blister package according to claim 1 or 2, characterized in that the inner sealing layer (26) of the lid (20) has a thickness of 5 to 30 μm.

11. A blister package according to any one of claims 1 to 10, characterised in that the inner sealing layer (26) of the lid (20) comprises up to 2% by weight of slip agent.

12. The third additive in the middle HDPE layer (24) of the lid (20) is CaCO 3 , TiO 2 12. The blister package according to claim 1, wherein the inorganic additive is selected from the group consisting of talc, chalk, clay, and metal salts.

13. A blister package according to any one of claims 1 to 11, characterised in that the third additive in the intermediate HDPE layer (24) of the lid (20) is a polymer which is incompatible with HDPE.

14. 14. The blister package according to any one of claims 1 to 13, characterized in that the sealing layer (36) of the thermoformed web (30) comprises 88% to 95% by weight of HDPE and 5% to 12% by weight of LLDPE, and / or the LLDPE is a metallocene LLDPE.

15. A blister package according to any one of claims 1 to 14, characterised in that the thermoformable web (30) further comprises an outer layer (32) mainly composed of HDPE.

16. A blister package according to any one of claims 1 to 15; and a solid pharmaceutical or nutritional product (40) contained in the cavity.

17. 17. A method for producing the packaged product of claim 16, comprising the steps of: - preheating a web material comprising at least two coextruded layers, namely a main layer comprising HDPE and up to 2% of a first additive, and a seal layer comprising HDPE and up to 50% LLDPE; - thermoforming the web material to form a web having cavities therein; - introducing a solid pharmaceutical or nutritional product into each cavity; - preheating a lid material comprising at least three coextruded layers, namely an outer HDPE layer containing up to 5% of a second additive, a middle HDPE layer containing an additive to reduce elongation at break, and an inner seal layer; - sealing the inner sealing layer of the lid onto the sealing layer of the web between the cavities using a heated sealing roll; - cutting the resulting product into blister packages of the desired format.

18. 20. The method of claim 17, wherein the first additive in the primary layer of the web material is an inorganic additive.

19. 19. The method of claim 17 or 18, wherein the second additive in the outer HDPE layer of the lid is an inorganic additive.

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