NL2028740B1

NL2028740B1 - Method of manufacturing packaging components with pre-applied seal

Info

Publication number: NL2028740B1
Application number: NL2028740A
Authority: NL
Inventors: Jacob Kat Simon
Original assignee: Hordijk Verpakkingsindustrie Zaandam B V
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2023-01-23

Abstract

A method of manufacturing a packaging component (2; 32) for packaging a product, in particular a consumable product, comprises the steps of an application step a) of applying a sealing material (20) on a plastic substrate (42), wherein the sealing material (20) is applied locally at a position of a peripheral sealing rim (16; 38) of the packaging component (2; 32) to be formed; a formation step b) of forming the packaging component (2; 32) by deformation of the substrate (42) on which the sealing material (20) has been locally applied; a cutting step c) of cutting the packaging component (2; 32) from the substrate (42) from which the packaging component (2; 32) has been formed.

Description

P35149NLO0/JV Title: Method of manufacturing packaging components with pre-applied seal

FIELD OF THE INVENTION The present invention relates to a method of manufacturing a packaging component from plastic substrate with pre-applied seal and use thereof in packaging a product.

BACKGROUND OF THE INVENTION Packaging containers, with packaging components like lids and trays, are widely used for packaging products, in particular consumable products, such as food and feed, medical products like drugs and medical devices. An important aspect of these containers is the extent to which air, moisture and pathogens can enter and leave the container, as these are of influence on the shelf life and quality of the packaged products. Multiple methods have been considered in the art to decrease the chances of leakage in and out of the container. One of these methods is to seal the lid and tray of the container together after packaging the consumable product.

In the art is known a method of sealing a lid and tray together by applying a layer of sealing material to the bottom face of a lid. In this method the sealing material is first applied to the full face of a substrate web by a roller. The substrate is a multi-layered plastic substrate comprising at least a carrier layer and a receiving layer for enhancing the adhesion of the sealing material. Then the lid is formed and cut from the substrate web containing the sealing material. After packaging a consumable product in a tray, the lid is sealed to the tray by e.g. applying heat and/or pressure to the rim parts of the lid and the tray that are to be sealed together.

Consequently, the entire bottom face of the lid is covered with sealing material, while only a small portion of the layer of sealing material is used for sealing. Multiple disadvantages can be recognized from this method of manufacturing a sealable lid, including the high material costs for redundant sealing material as the sealing material that has been applied over the full face, is only required at the sealing rim The sealing material is less transparent than the packaging material, thereby making the lid more opaque, which is often undesirable for packing consumable products. Moreover, upon applying the sealing material to the entire surface of the lid the risk of the contained product to come into contact with the sealing material increases, thereby causing contamination of the consumable product. And finally, the skeletal waste that is left after the packaging component has been cut from the substrate consists of multiple layers of different kinds of plastics, thus making recycling and reusing the substrate difficult.

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Furthermore, EP983947A1 discloses an unembossed lid with a sealing layer that is applied locally, corresponding to the shoulder of the tray, so the lid can be sealed to the shoulder of the tray by applying heat. The lid comprises a printing pattern at the inwardly facing layer, comprising a sealing layer (also known as a spacer sealing layer), enabling easy separation for thelids from a stack of lids in the packaging machine. The lids are specifically mentioned to be unembossed, as printing an image on an embossed lid produces the image in an unfavourable way. A disadvantage of such an unembossed lid with sealing material as described in EP983947A1, is that it is not possible to reclose the container after the seal of the container has been broken. Consequently, an extra reclosable lid would be required, or the use of a sealing material that is resealable. Unfortunately, resealable materials are expensive and should be applied on a larger area, increasing the risk of contamination of the packaged food with the sealing material.

Packaging materials used in EP983947A1 include plastics, such as polyethylene terephthalate (PET), polyvinylchloride (PVC) and polyolefin. These plastics materials are known to have unsatisfactory barrier properties: oxygen and water vapor permeability are high, posing a disadvantage for the shelf life and quality of the packaged consumable products. Consequently, EP983947A1 proposes to add extra layers to the substrate dedicated to the intended function, such as a layer of ethylene-vinyl alcohol (EVOH) or PVC, to improve the barrier properties. A drawback of these extra layers of plastic is the increased difficulty of recycling the packaging component, as the packaging component now consists of multiple kinds of plastic that cannot evidently be separated.

WO2012/069050A1 also discloses local application of sealing material on a packaging component, in this case the tray. After forming the tray from a plastic substrate, sealing material is applied with a roller on the sealing rim of the top of the side wall of the tray. This document describes sealing an unembossed lid to the sealing rim of the tray by applying heat. Also, with containers according to WO2012/069050, it is not possible to reclose the lid and the tray after the seal has been broken. Moreover, this document discloses a schematic representation of the application process, showing that the already cut trays are taken from a stack of trays before being put on a conveyer, after which the sealing material is applied to the rim of the trays by the roller. Thereafter the trays are stacked again. The extra steps of stacking and unstacking will increase the complexity of the manufacturing process including control thereof, as well as manufacturing time.

Another disadvantage of the process as described in W02012/069050, is that applying the sealing material directly to the rim of the tray increases the risk of contamination of the packaged product with the sealing material. As the sealing material is applied with a roller to the rim of the package there is a high likelihood of some of the sealing material to drip

23. over the edge of the rim. Thus, the packaged product is very likely to come into contact with this sealing material, especially when inserting or removing the product from the container.

BRIEF DESCRIPTION OF THE INVENTION The present invention aims to overcome one or more of the above disadvantages at least partly or to provide a suitable alternative manufacturing method.

In particular the present invention aims at providing a method of manufacturing packaging components that can be better recycled.

Another object is to provide a method of manufacturing packaging components of this kind with less likelihood of contamination of the packaged consumable product with the sealing material.

Yet another object is to provide a manufacturing process of packaging components that is easier to perform and requires less time.

Still another object is to provide packaging components at reduced costs.

The present invention provides a method of manufacturing a packaging component for consumable products, comprising the steps of an application step a) of applying a sealing material on a plastic substrate, wherein the sealing material is applied locally at a position of a peripheral sealing rim of the packaging material component to be formed; a formation step b) of forming the packaging component by deformation of the substrate on which the sealing material has been locally applied; a cutting step c) of cutting the packaging component from the substrate from which the packaging component has been formed.

In the method according to the invention the sealing material is applied to the plastic substrate by e.g. stamping or printing, such as jet printing or transfer printing, preferably gravure printing, the sealing material. The sealing material is applied locally in a closed contour to correspond to the peripheral sealing rim of the packaging component that is to be formed, which can either be a tray or a lid. After application of the sealing material, the substrate is deformed in order to provide a preform of the packaging component having the intended shape of the packaging component while the preform is still connected to the surrounding remaining skeleton of the substrate. Forming the packaging component can be done by thermoforming, also known as vacuum forming, the substrate on which the sealing material has been locally applied as such that the sealing material corresponds to the sealing rim of the packaging component. When the substrate is deformed in the shape of the packaging component, the preform of the packaging component is cut from the substrate, thereby resulting in the finished packaging component. In case that the packaging components are not used right away, the packaging components can

-4- be stacked after being cut. The shape of the packaging component is not critical and can be designed for containers having e.g. a rectangular, such as square, a circular or oval periphery.

Local application of the sealing material instead of applying it to the whole surface reduces the risk of contact between the sealing material and consumable product and thus contamination. In the present invention, the local application of the sealing material before forming and cutting the desired packaging component deems the additional unstacking and stacking performed in WO2012/069050 unnecessary, thereby allowing to perform the manufacturing method according to the invention as an inline process. Generally such an inline manufacturing process involves the provision of the plastic substrate as an (intermittently) moving web, wherein the steps of the method according to the invention are performed in dedicated stations that are arranged adjacent to one another without the need of intermediate storage by stacking and unstacking. This is particularly true in a production line, that further includes a filling station for filling the container that comprises a packaging component that has been manufactured according to the invention and a sealing station for sealing the tray and lid of the container together.

In a preferred embodiment of the invention, the packaging component is manufactured from a substrate consisting of a mono-component plastic. Starting from a mono-component plastic has the advantage that recycling the skeletal waste that arises after cutting the packaging component from the substrate is easier, because the skeletal waste does not comprise different plastics. The skeletal waste can be processed to form a new substrate, typically with the addition of virgin plastic, e.g. for the production of packaging components.

In a preferred embodiment of the invention, the packaging component is manufactured from a substrate consisting of a single layer of plastic. In an embodiment the single layer is obtained by coextrusion of thin films having the same base materials, e.g. virgin and recycled plastic. The films are indistinguishable in the substrate and cannot be separated from one another. Advantageously, a plastic substrate consisting of one layer of plastic which already has the desired properties, such as strength, flexibility and barrier properties, allows to use a plastic substrate having a reduced thickness compared to the multi-layered substrate known in the art, e.g. a substrate thickness in the range of 100-200 Um in the present invention, while multilayered substrate thickness according to prior art is in the range of 250-1200 um. Thus, less substrate is needed, thereby reducing the manufacturing costs.

In an embodiment of the invention, the packaging component is manufactured from a thermoplastic, advantageously selected from a group consisting of polyethylene terephthalate (PET), amorphous PET (APET), polypropylene (PP), polystyrene (PS), polyethylene furanoate (PEF) and amorphous PEF (APEF), preferably APET or APEF. The thermoplastic

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substrate according to this embodiment can be manufactured e.g. from a blend of virgin and recycled thermoplastic, such as virgin APET and recycled APET (also known as rPET), or from coextruded films as explained above. The use of APET or APEF is preferred due to their high transparency, so the consumable product that is packaged can be seen from the outside. Moreover, APET and APEF, and especially APEF, display high stiffness and impact resistance to prevent deformation of the packaging component once manufactured, and oxygen and water vapor permeability are low, thereby increasing the shelf life of the packaged consumable product.

In a preferred embodiment of the invention, the sealing material is a polymeric substance, preferably based on the same monomeric units of the plastic substrate, more preferably APET- or APEF-based. An advantage of using essentially the same polymeric material for the plastic substrate and the sealing material, such as an APET substrate and an APET-based sealing material is that the packaging component consists of a single type of plastic, which is beneficial for recycling the used packaging component after use by the customer. The sealing material should be able to withstand the conditions during the subsequent deformation step of the substrate without staining, smearing or bleeding.

In a preferred embodiment of the invention, the sealing material is applied on the plastic substrate in more than one sub steps, for example 2-5 sub steps, such as three sub steps, to ensure a uniform layer thickness across the sealing rim.

If the packaging component is a lid, generally the lid comprises a central section surrounded by a sealing and reclosing section, provided with the sealing rim, for engaging an associated (complementary) sealing and reclosing section of a tray.

In case of tray as packaging component, generally the tray comprises a bottom, an upstanding wall and at the top of the upstanding wall a sealing and reclosing section, provided with the sealing rim, for engaging an associated (complementary) sealing and reclosing section of a lid.

In a preferred embodiment of the invention, the packaging component is a lid having a (flat) central part and a sealing recess part comprising the sealing rim at the periphery of the lid surrounding the centre part, wherein advantageously the sealing recess part extends upwardly with respect to the centre part, wherein the sealing recess part comprises a sealing recess part inner wall, a sealing recess part outer wall connected by a sealing rim, wherein the sealing material is applied in the sealing recess part on the lower face of the sealing rim.

Applying the sealing material locally before forming the lid has the advantage that it is easier to apply the sealing material. Application of the sealing material in a later stadium of the process, such as after the forming the lid, could pose problems because the sealing material must be applied into the recess on the sealing rim, which is complex to perform in an inline process. If application is not done accurately, sealing material ends up on the sides of

-6- the walls or the sealing recess part, increasing the risk of contamination of the packaged consumable products.

In a preferred embodiment of the invention, the lid comprises a tab on the outside of the lid. The tab can be used to manually engage the lid, so the lid can be pulled off the tray to open the container after it has been closed.

A lid manufactured according to the invention can be sealed to a corresponding sealing rim of a tray (without sealing material applied to this tray rim) by application of heat and/or pressure after inserting the product in the tray.

Preferably a container made from a lid that has been manufactured according to the invention and a tray is reclosable.

In a preferred embodiment of the invention, therefore the lid also comprises a closing recess part in between the sealing recess part and the central part, which advantageously extends downwardly with respect to the centre part and comprises a closing recess part bottom wall, a closing recess part inner wall and a closing recess part outer wall, wherein the closing recess part outer wall, at a position below the sealing recess part inner wall, a notch is positioned that extends outwardly. The recess can engage the tray of the container, making the lid and the tray of the container reclosable.

In a further embodiment of the invention, the packaging component is a tray comprising a bottom part, a side wall and a sealing rim at the top of the periphery of the side wall, wherein the sealing material is applied on the sealing rim. The formation of the tray after application of the sealing material has the advantage that the sealing material cannot drip over the sides of the peripheral sealing rim of the tray, thereby decreasing the risk of contamination of the packaged food with the sealing material.

A tray manufactured according to the invention can be sealed to a corresponding sealing rim of a lid (without sealing material applied to this lid rim) by application of heat and/or pressure after inserting the product in the tray.

In other cases, both the lid and the tray have sealing material applied on their sealing rim, that are sealed together upon packaging the product.

Advantageously the tray also comprises a shoulder in the side wall for delimiting the vertical position of the lid. When the tray is closed by a lid having a notch at a closing recess part outer wall, the shoulder is arranged at a position below the notch of the lid.

A container comprising a lid and tray manufactured as packaging components according to the above embodiments can be reclosed to prolong the shelf life of the packaged consumable product.

In a further aspect the invention concerns the use of a packaging component manufactured according to any one of the preceding claims in packaging a product.

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BRIEF DESCRIPTION OF THE DRAWINGS The invention is further illustrated by the attached figures, wherein: - Fig. 1 shows a top view of an embodiment of a lid manufactured according to the invention; - Fig. 2 shows an enlarged detail of a cross-sectional view of the lid of fig. 1; - Fig. 3 shows an embodiment of a tray manufactured according the invention; - Fig. 4 shows an enlarged detail of a cross-sectional view of the tray of fig. 3; - Fig. 5 shows subsequent steps of manufacturing a packaging component with pre-applied seal according to the invention;

DETAILED DESCRIPTION OF THE DRAWINGS Fig. 1 shows a top view of an embodiment of a plastic lid 2 manufactured according to the invention. In this embodiment the lid 2 has a circular shape and comprises a centre part 4 consisting of a flat plane and a closing recess part 6 which in this case encircles the centre part 4. The closing recess part 6 can engage a tray as to make the lid 2 and tray reclosable. The lid 2 further comprises a sealing recess part 8 encircling the outside of the closing recess part 6 at the periphery of the lid 2, in which the sealing material (not shown) is locally applied before the lid 2 is formed by deforming a plastic substrate. Attached to the sealing recess part 8 and positioned on the outside of the lid 2 is a tab 10 which can be used to manually engage the lid as to pull the lid off the tray to access the tray and its contents. In Fig. 2 an enlarged detail of a cross-sectional view of the lid 2 according to Fig. 1 is shown. The sealing recess part 8 extends upwardly with respect to the flat centre part 4 of the lid 2 and comprises a sealing recess part inner wall 12, a sealing recess part outer wall 14, which are connected by a sealing rim 16. Sealing material 20 is applied on the lower face of the sealing rim 16 in the recess part 8. The sealing rim 16 is substantially flat as to have enough area to engage with the upper side of the sealing rim of the tray as shown in Fig. 3. Fig. 2 further shows a closing recess part 6 extending downwardly with respect to the centre part 4. The part 6 comprises a closing recess part bottom wall 24, a closing recess part inner wall 26 and a closing recess part outer wall 28. In the closing recess part outer wall 28, below the sealing recess part inner wall 12, a notch 30 is positioned extending outwardly. The notch 30 can engage the upstanding wall of the tray of the container, as to make the lid and the tray of the container reclosable. In Fig. 3 an embodiment of a tray 32 manufactured according to the invention is shown. The tray comprises a bottom part 34, an upstanding side wall 36 and a sealing rim 38 on the top of the of the wall 36, on which the sealing material (not shown) is locally applied before the tray 32 is formed by deforming a plastic substrate.

-8- In Fig. 4 an enlarged detail of a cross-sectional view of the tray 32 according to Fig. 3 is shown. At the periphery of the tray 32, on top of the side wall 36 is the sealing rim 38 which comprises a (flat) upper surface on which the sealing material 20 is applied. The width of the sealing rim 38 conforms to the width of the sealing rim of the associated lid, so the sealing rim of the tray fits into the sealing rim of that lid, and the tray and the lid can be sealed together. The tray also comprises a shoulder 39 in the side wall 36, which is, when the container is closed, below the notch 30 of the lid 2 according to Fig. 2. The shoulder 39 ensures better engagement of the lid 2 and the tray 32 so the container remains closed.

Fig. 5 illustrates schematically an inline process and device for manufacturing packaging components with preapplied sealing material according to the invention. The device comprises a motor-driven unwinding unit 40 on which a roll of plastic substrate web 42 is placed. The plastic substrate web 42 is transferred to a printing unit 44, in Fig. 5 shown as a gravure printer. The gravure printer 44 comprises two rollers 46 and 48, of which the bottom roller 48 comprises cavities which correspond to the sealing rim (advantageously slightly smaller than the width of that rim) of the component to be formed from the substrate web 42. As the bottom roller 48 rotates, it passes through a container that contains the sealing material 20, and the cavities are filled. Upon further rotation, the bottom roller 48 deposits the sealing material from the cavities on the substrate web 42. Although a single printing station 44 is shown, the application of sealing material can be repeated in multiple sub steps, for example 2-5 sub steps, such as 3 sub steps, by placing printers in series to thicken the layer of sealing material until it has the desired properties.

The substrate web 42 on which the sealing material 20 has been locally applied in a closed contour at the position of the sealing rim 18 passes from the printing unit 44 to the packaging component forming unit, which in Fig. 5 is shown as a thermoforming unit 50. The thermoforming unit 50 comprises two thermoforming tools 52 and 54 with cavities that correspond to the shape of the packaging component to be formed, which in Fig. 5 is a lid 2. The substrate web 42 on which the sealing material 20 has been locally applied is then thermoformed to form a lid 2, in such a way that the locally applied sealing material corresponds to the lower face of the sealing rim 18 of the lid 2, e.g. as shown in Fig. 2. The substrate web 42 can be cut before forming the packaging component as to prevent elongation of the substrate during thermoforming.

After the lid with the locally applied sealing material has been formed, the lid is cut from the substrate web 42 in the cutting unit 56. Subsequently, the lids can be stacked if they are not immediately used for packing consumable products. The leftover substrate can be recycled.

Claims

-9- CONCLUSIONS

Method for the manufacture of a packaging component being a lid (2) or a tray (32) of a packaging container for packaging a product, in particular a consumer product, comprising the steps of an applying step a) of applying a sealing material (20) on a web (42) of plastic substrate (42), the sealing material (20) being applied locally at a position of a peripheral sealing edge (16; 38) of the packaging component (2; 32) to be formed; a forming step b) of forming the packaging component (2; 32) by deforming the substrate (42) on which the sealing material (20) is locally applied; a die-cutting step c) of die-cutting the packaging component (2; 32) from the web of the substrate (42) from which the packaging component (2; 32) is formed.

The method of claim 1, wherein the substrate (42) is a monocomponent plastic substrate.

A method according to any one of the preceding claims, wherein the substrate (42) is a single-layer plastic substrate.

A method according to any one of the preceding claims, wherein the plastic of the plastic substrate (42) is a thermoplastic, advantageously selected from the group consisting of PET, APET, PP, PS, PEF and APEF, preferably APET or APEF.

A method according to any one of the preceding claims, wherein the sealing material (20) is a polymeric material, preferably based on the same monomer units of the plastic substrate, more preferably an APET-based sealing material.

A method according to any one of the preceding claims, wherein the applying step a) comprises pressing the sealing material (20) onto the substrate (42).

A method according to any one of the preceding claims, wherein the applying step a) comprises applying the sealing material (20) to the substrate (42) by gravure printing.

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A method according to any one of the preceding claims, wherein the application step a) comprises the application of the sealing material (20) in several sub-steps.

A method according to any one of the preceding claims, wherein the forming step b) comprises thermoforming the packaging component (2; 32) of the substrate (42).

A method according to any one of the preceding claims, wherein the packaging component is a lid (2) comprising a central part (4) and a sealing recess part (8) around the central part (4), the sealing recess part (8) extending upwards. with respect to the center part (4) of the lid (2) and a sealing recess inner wall (12), comprises a sealing recess outer wall (14) connected by a sealing rim (16), the sealing material (20) being arranged in the sealing recess part ( 8) on the sealing edge (16).

A method according to claim 10, wherein the cover (2) further comprises a tab (10) on the outside of the cover (2) and attached to the sealing recess (8) for manually grasping the cover (2).

A method according to claim 10 or 11, wherein the cover (2) further comprises a closure recess portion (6) extending downwardly from the center portion (4) of the cover (2) and further comprising a closure recess portion bottom wall (24) comprises a closure recess part inner wall (26) and a closure recess part outer wall (28), wherein the closure recess outer wall (28), below the sealing recess part inner wall (14), has a notch (30) that extends outwardly.

The method of any one of claims 1 to 9, wherein the packaging component is a tray (32) comprising a bottom portion (34), a side wall (36) and a sealing rim (38) at the top of the periphery of the side wall (36). ), wherein the sealing material (20) is applied to the sealing edge (38).

The method of claim 13, wherein the tray (32) further comprises a shoulder (39) in the side wall (36) to define the vertical position of the lid.

A method according to any one of the preceding claims, further comprising a stacking step d) of stacking the die-cut packaging components (2; 32) from step Cc).

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A method according to any one of the preceding claims, wherein the method is an inline process in which the web (42) is moved intermittently.

Use of a packaging component manufactured according to any one of the preceding claims in packaging a product.