Molded pulp container with peelable laminated plastic film

Abstract

A molded pulp container with a peelable laminated plastic film is provided. [Solution] A molded pulp container with a peelable laminated plastic film including a molded pulp layer (10), a barrier film layer (20), and a sealant layer (30). The molded pulp layer has an outer peripheral edge (11) and a flange (12) extending outward from the outer peripheral edge in a stepped manner with a decreasing height. The barrier film layer is laminated to the molded pulp layer and has a seal strength in the range of 0.15 to 0.34 N / mm. The sealant layer is attached to the outer peripheral edge with a seal strength in the range of 0.20 to 0.27 N / mm. The molded pulp container with the peelable laminated plastic film allows the sealant layer to be peeled off to open the package without the laminated barrier film being separated from the molded pulp. Furthermore, the barrier film is peeled off from the molded pulp layer after consumption, allowing contaminants to be separated from the molded pulp container and the molded pulp container to be recycled.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to the field of chemistry, and more particularly to molded pulp containers with peelable laminated plastic films. [Background technology]

[0002] Food containers made from natural pulp have gained popularity due to their environmental benefits and recyclability. However, several problems arise when such containers are used for refrigerated and frozen foods. These include loss of structural integrity after exposure to moisture or heat and an inability to maintain the freshness and flavor of food. This is primarily due to the porous nature of natural pulp, which allows air to pass through. During the production process, heat-sealing natural pulp containers with plastic sealants presents challenges due to poor adhesion between the natural pulp and the plastic material.

[0003] To improve the structural stability of natural pulp containers after exposure to moisture or heat and maintain food quality over a specified period of time, plastic film lamination technology has been applied to the interior of molded pulp containers. This, combined with a heat seal on the top surface, creates a barrier that minimizes air and moisture ingress and egress. Despite these advances, molded pulp containers with plastic film lamination still have limitations. When peeling the seal layer to open the package, the laminated film often comes off along with the seal layer, creating a film bag, as shown in Figure 1. Furthermore, consumers cannot easily separate the laminated film from the molded pulp container after use, complicating the process of separating contaminants from such molded pulp containers for recycling.

[0004] As outlined above, the widely used molded natural pulp containers laminated with plastic films still present functional limitations. Thus, there is a need for the development or improvement of such containers to address these challenges.

[0005] International Patent Publication No. WO2019190309A1, entitled "Molded Pulp Container with a Removable Laminate Layer and Method for Manufacturing Such Container Units," discloses a container including a cavity or compartment for holding a product, particularly a food product. The product-contacting surface consists of a removable laminate layer that functions as an oil barrier. After use, the laminate layer can be removed, allowing the molded pulp material to be separated from the laminate layer. The laminate layer can then be discarded as waste, while the molded pulp material can be recycled and potentially used to produce new container units.

[0006] U.S. Patent Application Publication No. 20210347518(A1), entitled "Recyclable Molded Pulp Container," discloses a molded pulp food container including a base made from molded pulp material and a pulp edge section. The base includes an upright wall extending from the base and an outer rim. The container has both an inner surface and an outer surface. The pulp edge section is connected to the outer rim by an upper surface and a lower surface. A barrier film laminated to the inner surface of the container and the upper surface of the edge section can be removed when the pulp edge section is detached from the base. This design allows the barrier film to remain attached to both the base and the pulp edge section, allowing the film to be peeled away from the base by pulling the edge section.

[0007] The above-mentioned inventions demonstrate the development of molded pulp containers laminated with a removable plastic film to facilitate recycling. Additionally, some container designs feature an extended lip on the base to facilitate peeling the sealing film. However, none of these inventions address the development of a molded pulp container in which the sealing layer can be peeled without removing the laminate film. This problem arises due to the weaker bond between the natural pulp and the laminate film compared to the bond between the laminate film and the sealing layer. Furthermore, after use, the laminate film should be easily peelable from the molded pulp container to allow for proper separation of the materials for recycling. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Patent Publication No. WO2019190309A1 [Patent Document 2] U.S. Patent Application Publication No. 20210347518(A1) Summary of the Invention [Means for solving the problem]

[0009] The present invention relates to an improvement to a molded pulp container with a peelable laminated plastic film. The molded pulp container includes a molded pulp layer, a barrier film layer, and a sealant layer. The invention enhances the surface energy between the molded pulp layer and the barrier film layer to improve adhesion between them. The invention also involves determining and controlling the seal strength between the molded pulp layer, including the peripheral edge and collar, and the barrier film layer, and optimizing the adhesive strength between the barrier film layer and the sealant layer. The production process is also further improved by introducing a heating step after laminating the barrier film layer onto the molded pulp layer.

[0010] The object of the present invention is to provide a molded pulp container with a peelable laminated plastic film that incorporates a newly developed component with unique features that address previous limitations. The container allows the sealant layer to be peeled away to open the container without removing the barrier film laminated over the molded pulp layer. Additionally, the barrier film can be removed from the molded pulp container after consumption to allow for the separation of contaminants from the molded pulp, thus facilitating recycling. [Brief explanation of the drawings]

[0011] [Figure 1] 1 illustrates peeling of a sealing layer from an existing molded pulp container with a peelable laminated plastic film. [Figure 2] 1 shows a molded pulp container with a peelable laminated plastic film according to the present invention. [Figure 3] 1 illustrates peeling of a sealing layer from a molded pulp container with a peelable laminated plastic film according to the present invention. [Figure 4] 1 illustrates the peeling of a barrier film layer from a molded pulp container with a peelable laminated plastic film according to the present invention. [Figure 5] 1 is a line graph showing surface energy values, including total, dispersive, and polar components, for an unmodified molded pulp layer, an modified molded pulp layer, and a barrier film layer. DETAILED DESCRIPTION OF THE INVENTION

[0012] The molded pulp container with peelable laminated plastic film according to the present invention comprises a molded pulp layer 10, a barrier film layer 20, and a sealant layer 30. The present invention introduces an improvement to molded pulp containers with peelable laminated plastic film to address problems encountered during peeling of the sealant layer 30 and barrier film layer 20 laminated on the molded pulp layer 10 prior to recycling.

[0013] To address these challenges, the inventors have optimized and controlled the seal strength between the molded pulp layer (10), including the perimeter (11) and collar (12), and the barrier film layer (20). This ensures that the barrier film layer (20) can be peeled from the molded pulp layer (10) after consumption for recycling, separating contaminants from the molded pulp layer (10). Additionally, the seal strength between the sealant layer (30) and the perimeter (11) of the molded pulp container has been adjusted and controlled to allow the sealant layer (30) to be peeled without removing the barrier film layer (20). Improvements have also been made to the surface energy value to overcome the limitations mentioned above.

[0014] In a preferred embodiment, a barrier film layer (20) is laminated to a molded pulp layer (10) including a peripheral edge (11) and a flange (12) extending outward from the peripheral edge (11) in a stepped manner with a decreasing height. The seal strength between the molded pulp layer (10) and the barrier film layer (20) is set to a range of 0.15 to 0.34 N / mm. The initial peak force required to peel the barrier film layer is preferably between 2.3 and 5.2 N. If the force is below this range, the barrier film layer may detach from the molded pulp layer (10) and adhere to the sealant layer (30) when the container is opened. Conversely, if the force exceeds the specified range, the barrier film layer (20) will adhere too strongly to the molded pulp layer (10) and become difficult to remove.

[0015] The sealant layer (30) that adheres to the outer periphery (11) of the container has a seal strength set between 0.20 and 0.27 N / mm. The initial peak force required to peel the sealant layer (30) is preferably between 3.13 and 4.8 N. If the force is below this range, the container will open, allowing air to pass through. If the force exceeds the specified range (as shown in Table 1), the consumer will find the container difficult to open.

[0016] After defining and controlling the seal strength, it was discovered that the seal strength between the molded pulp layer (10), including the outer periphery (11) and collar (12), and the laminated barrier film layer (20) exceeded the seal strength between the sealant layer (30) and the outer periphery (11) by an optimal range of 5-25%. This solution prevents the formation of a film pouch between the sealant layer (30) and the barrier film layer (20) when the sealant layer is peeled off. This also allows the barrier film layer (20) to be peeled off from the molded pulp layer (10) for material separation before recycling, as shown in Figures 3 and 4.

[0017] In the illustrated configuration, a collar (12) with a stepped, decreasing height extending outward from the outer peripheral edge (11) serves as a surface for adhesion of the barrier film layer (20). This design ensures that the plane of the stamped edge of the barrier film layer (20) is at a different level than the plane from which the sealant layer (30) is peeled, preventing shearing or pulling of the barrier film layer (20) after stamping. This also shifts the starting point for peeling the sealant layer (30).

[0018] [Table 1]

[0019] In a further preferred embodiment, the surface energy has been enhanced to improve adhesion between the molded pulp layer (10), including the peripheral edge (11) and collar (12), and the laminated barrier film layer (20). This involves adjusting the total surface energy by considering both the dispersive and polar components, ensuring that the total value lines up closely with the dispersive component.

[0020] The surface energy of the molded pulp layer (10) in terms of dispersion value ranges from 20 to 45 mN / m, and the polar component ranges from 1 to 10 mN / m. As shown in FIG. 5, the surface energy of the barrier film layer (20) has a dispersion value between 20 and 50 mN / m, with the polar component ranging from 1 to 5 mN / m.

[0021] The difference in surface energy between the molded pulp layer (10), including the outer periphery (11) and collar (12), and the barrier film layer (20) should be within 1-25%. If the difference exceeds this range, the adhesion between the barrier film layer (20) and the molded pulp layer (10) will be weak, and the barrier film layer (20) will come off together with the sealant layer (30) when the container is opened.

[0022] The molded pulp layer (10) may preferably be selected from any one or more of eucalyptus pulp, sugarcane bagasse pulp, bamboo pulp, or combinations thereof. The barrier film layer (20) used in the present invention may be selected from any one or more of films made from polypropylene, polyethylene, polyethylene terephthalate, polybutylene adipate terephthalate, polylactic acid, ethylene vinyl alcohol, or combinations thereof.

[0023] In a further preferred embodiment, the manufacturing process for a molded pulp container with peelable laminated plastic film comprises the steps of: a. forming a molded pulp layer (10) including a peripheral edge (11) and a collar (12) using a heated mold with a vacuum vent; b. Laminating a barrier film layer (20) on the molded pulp layer (10) including the peripheral edge portion (11) and the collar portion (12) at a temperature of 120 to 220°C; c. subjecting the container from step b to a heat treatment at 160-220°C for 5-180 seconds to enhance adhesion between the molded pulp layer (10), including the peripheral edge (11) and collar (12), and the barrier film layer (20); It consists of:

[0024] Heat treating the barrier film layer (20) at a specified temperature and duration significantly improves the adhesion between the molded pulp layer (10), including the perimeter edge (11) and collar (12), and the barrier film layer (20). A sealant layer (30) is then laminated onto the perimeter edge (11) after the container is filled with food. [Best mode of the invention] As described above in the detailed description of the present invention. [Explanation of symbols]

[0025] 10 Molded pulp layer 11 Outer periphery 12 Collar 20 Barrier film layer 30 Sealant Layer

Claims

1. A molded pulp container with a peelable laminated plastic film comprising a molded pulp layer (10), a barrier film layer (20), and a sealant layer (30), The molded pulp layer (10) has a peripheral edge (11) and a flange (12) with a decreasing height that extends outward from the peripheral edge (11) in a stepped manner; The barrier film layer (20) is laminated and has a seal strength in the range of 0.15 to 0.34 N / mm, The sealant layer (30) is attached to the outer peripheral edge (11) with a seal strength in the range of 0.20 to 0.27 N / mm. A molded pulp container with a peelable laminated plastic film.

2. It is preferable that the seal strength of the molded pulp layer (10) including the outer peripheral edge portion (11) and the flange portion (12) laminated with the barrier film layer (20) is in the range of 2.3 to 5.2 N. providing the initial peak force required to peel off the barrier film layer (20); A molded pulp container with the peelable laminated plastic film of claim 1.

3. It is preferable that the seal strength of the sealant layer (30) attached to the outer peripheral edge portion (11) is in the range of 3.13 to 4.8 N. providing the initial peak force required to peel the sealant layer (30); A molded pulp container with the peelable laminated plastic film of claim 1.

4. It is preferable that the seal strength of the molded pulp layer (10) including the outer periphery (11) and the collar (12) to which the barrier film layer (20) is laminated is 5 to 25% higher than the seal strength of the sealant layer (30) attached to the outer periphery (11). A molded pulp container with the peelable laminated plastic film of claim 1.

5. The surface energy of the molded pulp layer (10) is Dispersion component: 20 to 45 mN / m 1 to 10 mN / m for polar components in the range of A molded pulp container with the peelable laminated plastic film of claim 1.

6. The surface energy of the barrier film layer (20) is Dispersion component: 20 to 50 mN / m 1 to 5 mN / m for polar components in the range of A molded pulp container with the peelable laminated plastic film of claim 1.

7. The difference in total surface energy between the molded pulp layer (10), including the outer periphery (11) and the collar (12), and the barrier film layer (20) is in the range of 1 to 25%. A molded pulp container with a peelable laminated plastic film according to any one of claims 1, 5 or 6.

8. the molded pulp layer (10) is selected from any one or more of eucalyptus pulp, bagasse pulp, bamboo pulp, or combinations thereof; A molded pulp container with a peelable laminated plastic film according to any one of claims 1 to 7.

9. the barrier film layer (20) is selected from any one or more of polypropylene, polyethylene, polyethylene terephthalate, polybutylene adipate terephthalate, polylactic acid, ethylene vinyl alcohol, or combinations thereof; A molded pulp container with a peelable laminated plastic film according to any one of claims 1 to 8.

10. 10. A process for producing a molded pulp container with the peelable laminated plastic film of claim 1, comprising: a. forming the molded pulp layer (10) including the outer periphery (11) and the collar (12) using a heated mold with vacuum air holes; b. laminating the barrier film layer (20) onto the molded pulp layer (10), including the outer periphery (11) and the collar (12), at a temperature of 120-220°C; c. Heating the container obtained from step b at a temperature of 160-220°C for 5-180 seconds to enhance adhesion between the molded pulp layer (10), including the outer periphery (11) and the collar (12), and the barrier film layer (20); Including, After the food container is completed, the sealant layer (30) is applied onto the outer periphery (11). process.

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