EP4673310A1

EP4673310A1 - Method for producing a packaging article and a packaging article

Info

Publication number: EP4673310A1
Application number: EP23737854.2A
Authority: EP
Inventors: Marcus MAYR; Mathias FORSTHUBER; Damian POPLAWSKI; Lars Göran Berglund
Original assignee: Mondi AG
Current assignee: Mondi AG
Priority date: 2023-03-02
Filing date: 2023-06-21
Publication date: 2026-01-07
Also published as: WO2024178445A1

Abstract

The invention relates to a method for producing a packaging article, the method comprising the following steps: - supplying, in particular continuously supplying, a base material (1), the base material (1) being paper, in particular Kraft paper, having an stretch at break in machine direction (MD) of at least 5% according to ISO 1924-3:2005, - plastically deforming the base material (1 ) for providing a structured layer (2), wherein deforming is performed at a temperature of between 10°C and 40°C, and wherein the base material (1) during deforming has an absolute water content of between 5% and 20%, - joining the structured layer (2) on at least one side thereof with an essentially flat cover material (3), the cover material (3) being paper, in particular Kraft paper, such that a compound layer (4) is formed, - forming a packaging article (5) from the compound layer (4), said packaging article (5) having at least one interior space (6) for receiving the object to be packaged.

Description

METHOD FOR PRODUCING A PACKAGING ARTICLE AND A PACKAGING

ARTICLE

The present invention relates to a method for producing a packaging article with the features of independent claim.

Various embodiments of packaging articles are known in the art. Such articles are typically used for packaging objects for shipping or other means of transport. Among the most important characteristics of such articles are durability, strength, and a certain cushioning effect in order to protect the packaged product from outer influences.

A well-known example of a packaging article are padded bags, which are equipped with a bubble-foil. Such bags find common use as envelopes for packing smaller items, such as in the e-commerce business. Said padded bags typically comprise a two-layer structure with a paper-based outer layer and a cushioning bubble-foil layer on their inner side. Other similarly structured packaging articles are known in the art, which employ a comparable principle of cushioning.

While those packaging articles provide superior properties as regards material strength and cushioning effect, they are disadvantageous as polymeric materials, i.e. , plastics, often stemming from fossil sources are necessary for the production of the bubble-foil layer. Additionally, in many regions of the world, regulations are being adopted which aim at reducing the use of plastics. Therefore, alternative solutions are necessary in order to overcome this limitation of prior art packaging materials.

It has been found that multi-layer paper-based materials, which comprise at least a flat cover layer and a structured layer may provide a similar cushioning effect as compared to padded bags with bubble-foils. Here, the structured layer may take over the cushioning effect, whereby embossment structures, such as knobs, or other types of plastically deformed structures, such as flute I wave structures may be employed.

However, these paper-based structures to date have the disadvantage that deformation of the structured layer typically requires elevated temperatures in combination with moisture in order to effect the deformation process and obtain a plastically deformed material. This means that substantive amounts of energy are required in the production process of such materials, which is also problematic in view of production costs and sustainability.

The object of the present invention may therefore be seen in providing a method for the production of a packaging article, which can at least partly overcome these disadvantages of prior art solutions. In particular, the goals of providing plastics-free materials along with low energy consumption during the production should be met. A further object of the invention may be seen in providing sustainable yet strong packaging articles.

It has been surprisingly found in the course of the present invention that at least one of these objects can be preferably solved by using a paper with a stretch at break in machine direction (MD) of at least 5% according to ISO 1924-3:2005. Using such paper, plastic deformation of the material at preferable temperatures of below 40°C and at a preferable absolute water content of between 5% and 20% of the paper is possible.

In order to provide even better deformation characteristics, a stretch at break of at least 8% according to ISO 1924-3:2005 in machine direction may be provided. The paper used for preparing the may also have specific characteristics in cross direction (CD), namely a stretch at break of at least 5% according to ISO 1924-3:2005, preferably of at least 8% according to ISO 1924-3:2005.

The stretch at break in MD and/or CD may be up to 15% according to ISO 1924-3:2005.

The stretch characteristics in MD and CD may determine which type of structured layer can be prepared. If the stretch at break of at least 5% is provided only in machine direction, it may be desirable that the structured layer is essentially un-deformed in cross direction. An example of such structure would be a wave-like structure, which is known from corrugated cardboard. In this case, the structured layer may have a plurality of waves, which run in machine direction, the peak and valley of each wave running in cross direction of the paper.

If a stretch at break in MD and CD of at least 5% is provided, it may be possible to provide deformations in the paper, which extend in multiple directions. Such deformations may be knobs, bubbles, or other three-dimensional structures. In this case, the structured layer may comprise an arrangement of a plurality of deformations, directly adjacent to each other or interspersed by portions of flat material. The deformations may also be waves, which run for instance in diagonal direction over the structured layer.

In addition to stretch at break, the following further characteristics of the base material for the structured layer may be provided:

The basis weight of the base material may be at least 60 g/m² or between 60 g/m² and 160 g/m², all according to ISO 536:2012.

The burst strength of the base material may be at least 380 kPa or between 380 kPa and 1000 kPa, all according to ISO 2758:2014.

The tensile energy absorption of the base material in MD and/or in CD may be at least 150 J/m², in particular at least 200 J/m², all according to ISO 1924-3:2005. The tensile energy absorption of the base material in MD may be between 200 J/m² and 1000 J/m² according to ISO 1924-3:2005. The tensile energy absorption of the base material in CD may be between 200 J/m² and 400 J/m² according to ISO 1924-3:2005.

The tensile strength of the base material in MD and/or in CD may be at least 5,0 kN/m, in particular at least 7,0 kN/m, all according to ISO1924-3:2005. The tensile strength of the base material in MD may be between 5,0 kN/m and 19,5 kN/m according to ISO 1924-3:2005. The tensile strength of the base material in CD may be between 6,0 kN/m and 8,0 kN/m according to ISO 1924-3:2005.

The tear resistance of the base material in MD and/or in CD may be at least 500 mN, in particular at least 700 mN, all according to ISO 1974:2012. The tear resistance of the base material in MD may be between 700 mN and 2100 mN according to ISO 1974:2012. The tear resistance of the base material in CD may be between 800 mN and 3500 mN according to ISO 1974:2012.

In the course of the process according to the invention, a structured layer may be provided from the paper, which is subsequently used to form a cushioning layer of the packaging article.

The height of the structured layer, which is in particular the maximum extension of the structured layer in a direction perpendicular to the main plane of extension of the structured layer, may be at least 1 mm, in particular at least 2 mm, or at least 5 mm.

The deformation may provide a permanent or plastic deformation which leads to an elongation or stretching of the paper, i.e., the base material, of at least 3% in MD and/or in CD.

The deformation step yielding the structured layer may preferably be included into a production process for producing a packaging article, where all steps from supplying the base material to providing the final packaging article are performed in a continuous and/or directly subsequent manner. Such process may also be referred to as an integrated process. In such process, the materials used for the production of the packaging article may be supplied in a continuous manner, such as from a paper reel. Such paper reel may contain the material (paper) at a length of at least 100 m. The material may be provided by a material supply station.

From the material supply station, the base material and any other materials used for forming the packaging article may be conveyed through the production system. In particular, the material supply station may be followed by a structuring or deformation station, where the structured layer is formed.

The structured layer may be formed by various techniques, such as those known in the art. In particular, formation of the structured layer should be performed in a continuous manner. Examples are pressing and/or rolling. Thus, the structuring station may be provided with a flat press and/or a rolling device in order to form the structured layer.

After being formed, the structured layer may be combined with at least one essentially flat cover layer and/or with further structured layers, thus forming an at least two-layered compound material or compound layer.

For merging the different layers, an adhesive may be used. The adhesive may be one or more of a water-based adhesive; a solvent-based adhesive; a solvent-free adhesive; a starch-based adhesive; a protein-based adhesive; a polymer dispersion adhesive; a polymer solution adhesive; a resinous adhesive; an adhesive which can be activated by an electron beam; a hotmelt adhesive; a reactive adhesive, such as a two-component adhesive. Preferred are those adhesives, which do not involve the use of heat and/or water.

The cover layer may be essentially flat and it may be provided from a cover material.

The cover material may be the same or different from the base material used for forming the structured layer. In further steps, the compound material may be processed in order to yield a packaging article. Such further processing may include at least one of a cutting step; a folding step; a gluing step.

In a gluing step, different regions of one structured layer or regions of at least two structured layers may be connected using an adhesive. The adhesive may be selected from the ones described above in relation to the formation of the compound layer. In a cutting step, preforms may be provided from the compound material, which are then processed further to yield the packaging article. In a folding step, the compound material and/or the preforms may be folded in order to give the packaging article the desired shape.

Any combination of these steps may be used, which is suitable for producing a packaging article.

Prior to being cut, the compound material may be an essentially continuous sheet of material. Thus, cutting is preferably performed after the compound layer has been formed.

Different treatment or production steps may be included in the process of the invention. For example, two structured layers may be connected, in particular by using adhesive, before the packaging article is formed. Alternately, or in addition, one structured layer may be folded and different regions of this structured layer by be connected, in particular by using adhesive, before the packaging article is formed. In another embodiment, preforms may be cut from the compound layer, wherein the packaging article is then formed from the preforms.

The final packaging article may be a bag, an envelope, a box, a wrap, or the like. In one example, the packaging article may at least have an interior for receiving an object to be packaged and an opening for inserting the object. Such packaging article may further be provided with a closing means, such as a flap. The closing means may comprise and adhesive layer for fixing the closing means at a respective receiving region of the packaging article. Furthermore, a re-opening means may be provided in order to be able to remove the object from the packaging article. The re-opening means may be a tear strip, which may be used to rip the packaging article open in a controlled manner.

In the process of the invention, an object may be directly packaged in the packaging article, while the packaging article is formed. The process may therefore provide a packaging article without an object or it may provide a packaging article with an already packaged object.

Such process may include the steps of (i) placing one or more objects to be packaged on a surface of the compound layer; (ii) connecting predetermined regions of the compound layer, such to enclose the or each object; (iii) dividing the intermediate of step (ii) into multiple packaging articles which already contain the object to be packaged.

The invention may also relate to a system and/or a device for performing the process of the invention. Such system and/or device may contain one or more of the following parts:

- a material supply station for supplying the base material and/or the cover material;

- a deformation and/or structuring station for forming the structured layer from the base material;

- a compounding station for merging the structured layer with the cover material in order to form the compound layer;

- a processing station for forming the packaging article from the compound layer;

- an output station for providing the packaging article.

The processing station may contain one or more sub-stations, such as:

- a folding station;

- a merging station;

- a cutting station.

The invention also relates to a packaging article as such. The packaging article may particularly be formed by a process as described herein. Such packaging article may be provided with an interior space, an opening, and at least one closing means. The packaging article may comprise a compound material, which contains a structured layer and a flat layer as described herein.

The invention particularly relates to a method for producing a packaging article, the method comprising the following steps: supplying, in particular continuously supplying, a base material, the base material being paper, in particular Kraft paper, having an stretch at break in machine direction (MD) of at least 5% according to ISO 1924-3:2005, plastically deforming the base material for providing a structured layer, wherein deforming is performed at a temperature of between 10°C and 40°C, and wherein the base material during deforming has an absolute water content of between 5% and 20%, joining the structured layer on at least one side thereof with an essentially flat cover material, the cover material being paper, in particular Kraft paper, such that a compound layer is formed, forming a packaging article from the compound layer, said packaging article having at least one interior space for receiving the object to be packaged. The packaging article may have an opening and/or at least one closing means.

Optionally it may be provided that for forming the packaging article at least two regions of the compound layer or a preform made out of the compound layer are connected with each other using an adhesive.

Optionally it may be provided that the base material has an stretch at break in cross direction (CD) of at least 5% according to ISO 1924-3:2005.

Optionally it may be provided that deforming of the base material is performed in a rolling device or in a pressing device and/or a rolling device. Optionally it may be provided that the structured layer is provided with a plurality of waves to form a continuous wave structure, the waves running essentially parallel to the cross direction (CD) of the base material.

Optionally it may be provided that the structured layer is provided with a plurality of embossments to form an embossment structure, wherein neighbouring embossments are optionally separated from each other by essentially flat areas of the base material.

Optionally it may be provided that the base material is supplied from a paper reel, which paper reel contains the base material at a length of at least 100 m, and/or wherein the cover material is supplied from a paper reel, which paper reel contains the cover material at a length of at least 100 m.

Optionally it may be provided that the base material and the cover material are the same material.

Optionally it may be provided that all steps are performed within the production line of one manufacturing system.

Optionally it may be provided that the closing means is provided with a sealing region and optionally with a re-opening means.

Optionally it may be provided that the structured layer has a height of at least 1 mm, preferably at least 2 mm.

Optionally it may be provided that the structured layer is stretched by the amount of at least 3% in machine direction (MD) as compared to the base material, and/or wherein the structured layer is stretched by the amount of at least 3% in cross direction (CD) as compared to the base material.

Optionally it may be provided that prior to forming the packaging article, a preform is provided from the compound layer by cutting a discrete portion from the compound layer in a cutting station, and wherein the packaging article is formed from the preform. Optionally it may be provided that the preform is folded along at least one folding edge.

Optionally it may be provided that an intermediate, in particular a continuous intermediate is formed from the compound layer or from more than one compound layer, and wherein the packaging article is formed by cutting a discrete portion from the intermediate.

Optionally it may be provided that the intermediate is formed by joining two compound layers, or wherein the intermediate is formed by folding one compound layer along a folding edge and joining opposing regions of the compound layer.

The invention may also relate to a packaging article comprising or being composed of a compound layer formed by joining a structured layer on at least one side thereof with an essentially flat cover material, the structured layer and the cover material being paper, in particular Kraft paper, wherein the structured layer is formed from paper having a stretch at break in machine direction (MD) of at least 5% according to ISO 1924-3:2005, and wherein the said packaging article has at least one interior space for receiving the object to be packaged.

Optionally, it may be provided that the structured layer is formed from paper having a stretch at break in cross direction (CD) of at least 5% according to ISO 1924-3:2005.

Optionally, it may be provided that the structured layer has a height of at least 1 mm, preferably at least 2 mm.

The invention may also relate to a packaging article obtained by a method according to the invention.

Further features of the present invention can be derived from the patent claims, the description of the exemplary embodiments, and the drawings. In the following, the present invention will be described in detail by referring to exemplary embodiments. Those embodiments are intended for illustrative purposes and shall not restrict the scope of the patent claims.

In the drawings:

Fig. 1 shows a schematic drawing of a part of a process according to an exemplary embodiment of the invention;

Fig. 2 shows a schematic representation of a first inventive embodiment for forming a packaging article;

Fig. 3 shows a schematic representation of a second inventive embodiment for forming a packaging article;

Fig. 4 shows a schematic detailed view of a compound layer according to an inventive embodiment; and

Fig. 5 shows a schematic detailed view of a compound layer according to another inventive embodiment.

Unless otherwise used, the drawings show the following features and/or parts: Base material 1 ; structured layer 2; cover material 3; compound layer 4; packaging article 5; interior space 6; opening 7; closing means 8; preform 9; folding edge 10; intermediate 11 ; pressing device 12; wave 13; embossment 14; paper reel 15; connection region 16; cutting line 17.

Fig. 1 shows a schematic drawing of a part of a process according to an exemplary embodiment of the invention. In this part of the process a continuous compound layer 4 is formed, which then can be used for further processing and forming a packaging article.

The compound layer 4 is composed of two layers, namely an essentially flat cover layer and a structured layer 2. The cover layer and the structured layer 2 are made of Kraft paper with the characteristics as shown in Table 1 below. Table 1 : Parameters of the base material used in the exemplary embodiment

The paper is supplied from two different paper reels 15, each of the reels 15 containing approx. 200 m of paper at a width of approx. 70 cm. The paper used for production of the structured layer 2 is also referred to as base material 1. From its respective reel 15, the base material 1 is guided to a pressing device 12. In this embodiment, the pressing device 12 is a flat press, which is designed to give the base material an embossment structure with a plurality of knobs, interspersed by flat regions of material.

In other embodiments which are not shown here, the pressing device 12 may be replaced by a rolling device, in order to provide the base material 1 with a wave structure.

The production of the structured layer is performed at a temperature of approx. 28°C, which is the ambient temperature at the pressing device 12. Thus, no additional heat supply is provided. During pressing, the base material 1 has a water content of approx. 8%, which means that no additional moisture is added to the material.

The structured layer 2 formed thereby has a height of approx. 5 mm, measured from the peak of one knob to the flat area between adjacent knobs, in the direction perpendicular to the main direction of extension of the structured layer. Use of the pressing device 12 leads to a plastic deformation, i.e., stretching, of the base material 1 of approx. 6% both in MD and CD.

After exiting the pressing device 12, the structured layer 2 is connected to the cover layer 3 provided from another paper reel 15 by means of an adhesive. The adhesive is applied to the flat portions of the structured layer 2, such that the cover layer 3 can be connected with the structured layer. In this embodiment, the structured layer 2 has a flat side and a structured side. The connection to the cover layer is made on the flat side, such that the knobs protrude from the compound layer 4. In this embodiment, the adhesive is a reactive adhesive, which can be cured without application of additional heat and moisture. Thus, a compound layer 4 is produced, which then can be subjected to further processing steps.

In alternative embodiments, other papers could be used as base material 1. The parameters of such further exemplary base materials 1 are listed in Tables 2 and 3 below.

Table 2: Parameters of an alternative base material Table 3: Parameters of a further alternative white base material

Fig. 2 shows a schematic representation of a first inventive embodiment for forming a packaging article 5, where a compound layer 4, such as the one previously described in connection with the embodiment shown in Fig. 1 , is used.

In this embodiment, a cutting device is used to cut a preform 9 from the continuous compound layer 4. The shape of the preform 9 is designed such that a packaging article 5 can be formed from it. For this purpose, in a further step, the preform 9 is folded using a folding device along predetermined folding edges 10. After being folded, the overlapping regions are connected using a reactive adhesive so to provide a packaging article 5 in the form of an envelope. This envelope has an interior space 6 for receiving an object to be packaged, an opening 7, through which the object can be inserted, and a closing means 8. The closing means 8 is provided with an adhesive layer, which can be attached to a corresponding region of the packaging article 5 in order to seal the interior space 6. The closing means 8 is also provided with a re-opening means in the form of a tear strip (not shown), which can be used to re-open the packaging article 5.

In this packaging article 5, the cover layer 3 lies on the outer side, with the structured layer 2 being provided on the inner side, in order to provide a good cushioning effect. Fig. 3 shows a schematic representation of a second inventive embodiment for forming a packaging article 5, where a compound layer 4, such as the one previously described in connection with the embodiment shown in Fig. 1 , is used.

In contrast to the embodiment described in connection with Fig. 2, no preform is prepared in this embodiment of the production process. The process used here is similar to the so-called HFFS (Horizontal Form-Fill-Seal) process. Here, the compound layer 4 is first folded along a folding edge 10, such that a folded continuous material is provided.

The material is then connected in predetermined connection regions 16 using an adhesive, such as the adhesive as described above. Thereby, an intermediate 11 is produced, which essentially is a series of subsequently arranged packaging articles 5. However, the packaging articles 5 are still attached to each other.

In order to separate the packaging articles 5 from each other, the continuous intermediate 11 is cut at predetermined cutting lines 17, which cutting lines 17 run in the center of each connection region.

Finally, separate packaging articles 5 are formed, which again have an interior space 6, an opening 7, and a closing means 8.

Fig. 4 shows a schematic detailed view of a compound layer 4 according to an inventive embodiment. In this compound layer 4, the structured layer 2 has a wave structure. The cover layer 3 is connected to the waves 13 at their peaks and the waves run in the cross direction of the base material 1 .

The structured layer 4 shown here may be produced using a process described in connection with Fig. 1 , where the pressing device 12 is substituted by a roller device. This material is similar to corrugated cardboard and can be used for similar purposes.

Fig. 5 shows a schematic detailed view of a compound layer 4 according to another inventive embodiment, such as the compound layer 4 formed in the process described in connection with Fig. 1 . The structured layer 2 is provided with a regular pattern of embossments 14 in the form of knobs.

Claims

1. A method for producing a packaging article, the method comprising the following steps: a. supplying, in particular continuously supplying, a base material (1 ), the base material (1 ) being paper, in particular Kraft paper, having a stretch at break in machine direction (MD) of at least 5% according to ISO 1924- 3:2005, b. plastically deforming the base material (1 ) for providing a structured layer (2), wherein deforming is performed at a temperature of between 10°C and 40°C, and wherein the base material (1 ) during deforming has an absolute water content of between 5% and 20%, c. joining the structured layer (2) on at least one side thereof with an essentially flat cover material (3), the cover material (3) being paper, in particular Kraft paper, such that a compound layer (4) is formed, d. forming a packaging article (5) from the compound layer (4), said packaging article (5) having at least one interior space (6) for receiving the object to be packaged.

2. The method according to claim 1 , wherein for forming the packaging article (5) at least two regions of the compound layer (4) or a preform (9) made out of the compound layer (4) are connected with each other using an adhesive.

3. The method according to claim 1 or 2, wherein the base material has an stretch at break in cross direction (CD) of at least 5% according to ISO 1924-3:2005.

4. The method according to any of claims 1 to 3, wherein deforming of the base material (1 ) is performed in a rolling device or in a pressing device (12) and/or a rolling device.

5. The method according to any of claims 1 to 4,

- wherein the structured layer (2) is provided with a plurality of waves (13) to form a continuous wave structure, the waves (13) running essentially parallel to the cross direction (CD) of the base material (1 ), - or wherein the structured layer (2) is provided with a plurality of embossments (14) to form an embossment structure, wherein neighbouring embossments are optionally separated from each other by essentially flat areas of the base material (1 ).

6. The method according to any of claims 1 to 5, wherein the base material (1 ) is supplied from a paper reel (15), which paper reel (15) contains the base material (1 ) at a length of at least 100 m, and/or wherein the cover material (3) is supplied from a paper reel (15), which paper reel (15) contains the cover material (3) at a length of at least 100 m.

7. The method according to any of claims 1 to 6, wherein the base material (1 ) and the cover material (3) are the same material.

8. The method according to any of claims 1 to 7, wherein all steps are performed within the production line of one manufacturing system.

9. The method according to any of claims 1 to 8, wherein the closing means (8) is provided with a sealing region and optionally with a re-opening means.

10. The method according to any of claims 1 to 9, wherein the structured layer (2) has a height of at least 1 mm, preferably at least 2 mm.

11 . The method according to any of claims 1 to 10, wherein the structured layer (2) is stretched by the amount of at least 3% in machine direction (MD) as compared to the base material (1 ), and/or wherein the structured layer (2) is stretched by the amount of at least 3% in cross direction (CD) as compared to the base material (1 ).

12. The method according to any of claims 1 to 11 , wherein prior to forming the packaging article (5), a preform (9) is provided from the compound layer (4) by cutting a discrete portion from the compound layer (4) in a cutting station, and wherein the packaging article (5) is formed from the preform (9).

13. The method according to claim 12, wherein the preform (9) is folded along at least one folding edge (10).

14. The method according to any of claims 1 to 11 , wherein an intermediate (11 ), in particular a continuous intermediate (11 ) is formed from the compound layer (4) or from more than one compound layer (4), and wherein the packaging article (5) is formed by cutting a discrete portion from the intermediate (11 ).

15. The method according to claim 14, wherein the intermediate (11 ) is formed by joining two compound layers (4), or wherein the intermediate (11 ) is formed by folding one compound layer (4) along a folding edge (10) and joining opposing regions of the compound layer (4).

16. The method according to any of claims 1 to 15, wherein the packaging article (5) comprises an opening (7) and/or at least one closing means (8).

17. A packaging article comprising or being composed of a compound layer (4) formed by joining a structured layer (2) on at least one side thereof with an essentially flat cover material (3), the structured layer (2) and the cover material (3) being paper, in particular Kraft paper, wherein the structured layer is formed from paper having a stretch at break in machine direction (MD) of at least 5% according to ISO 1924-3:2005, and wherein the said packaging article (5) has at least one interior space (6) for receiving the object to be packaged.

18. The packaging article according to claim 17, wherein the structured layer is formed from paper having a stretch at break in cross direction (CD) of at least 5% according to ISO 1924-3:2005.

19. The packaging article according to claim 17 or 18, wherein the structured layer (2) has a height of at least 1 mm, preferably at least 2 mm.

20. The method according to any of claims 17 to 19, wherein the packaging article (5) comprises an opening (7) and/or at least one closing means (8).

21 . A packaging article obtained by a method according to any of claims 1 to 16.