Resealable Leak-Resistant Containers Having A Pressed Pulp Tray With A Thermoformed Plastic Lid

Abstract

A leak-resistant pulp container with a plastic lid is disclosed, including a tray formed of molded pulp and having a boom and a sidewall forming an interior volume. The tray has an edge extending peripherally outward from an upper edge of the sidewall, and the tray edge has an outer portion. The container further includes a plastic lid having an edge extending peripherally outward therefrom, and the lid edge having an outer portion.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This is a U.S. national stage of application No. PCT/US2014/028541, filed on 14 Mar. 2014, which claims the benefit of U.S. Provisional Patent Application No. 61/799,008, filed on 15 Mar. 2013, both of which are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The disclosed embodiments relate to resealable containers with leak-resistant features for storing food, liquids, and various other items. In particular, the disclosed embodiments relate to resealable leak-resistant containers having a molded pulp tray with a plastic lid.

BACKGROUND OF THE INVENTION

The use of plastic disposable containers and trays for packaging, distributing, food are widespread in the marketplace. There is a need for containers that are easy open and close, but at the same time, resist leaks. This is especially true for containers designed for liquids, e.g., soup containers. The leak-resistance must be maintained even when the container is accidentally tilted during transportation and handling so that the liquid contained therein reaches the seam where the bottom (i.e., tray) and lid of the container are joined.

Containers having a tray formed of molded pulp are often seen as an environmentally-friendly option. However, the physical properties of pulp material and its production processes can make it difficult to produce a pulp container with leak-resistant properties.

For example, it can be difficult to manufacture a pulp container with a small “draft angle,” which is the angle of the upper edge of the container wall relative to vertical. Due to the nature of the manufacturing processes of pulp containers, small draft angles can create an array of production and quality problems, such as uneven distribution of fibers in the produced part, inconsistent part geometry, damage to manufacturing equipment, etc. A typical paper container, on the other hand, such as a soup cup, may have a draft angle of between 5 and 7 degrees. This relatively small draft angle allows the container wall to exert a greater force on the lid when it is wedged into the upper portion of the container wall to seal the container, i.e., because the force exerted by the container wall is largely in a horizontal direction. This helps maintain a tighter seal for the paper container. Similarly, plastic containers may be formed with an equally small draft angle relatively easily.

A container having a small draft angle is difficult to achieve in a molded pulp process, because a larger, i.e., wider, draft angle typically must be used with pulp materials due to the nature of the pulp molding process. The use of a wider draft angle results in a greater portion of the force exerted by the container walls on the lid being directed in a vertical direction of the container when upright, i.e., a direction which tends to produce an upward force on the lid. Therefore, a conventional pulp container can be harder to seal in a leak-resistant manner.

Another physical property of pulp material which can make a leak-resistant container difficult to manufacture is the relative lack of flexibility of molded pulp. The lack of flexibility arises from the characteristics of the natural fibers, which tend not to stretch very much on their own or when molded together. This lack of flexibility means that certain geometries, known as “undercuts,” cannot easily be used in pulp containers. An undercut is a portion, e.g., an edge portion, of a container which decreases in width as the sidewall of the container extends toward its upper edge. In a container lacking undercuts, on the other hand, the width of the container increases continuously as the sidewall extends toward its upper edge. An undercut can be achievable and useful in creating an interconnection between a container tray and lid, such as in a container made entirely of flexible materials, such as plastic. However, a pulp container part having undercuts will likely tear as it is removed from the mold due to its lack of flexibility and also due to inherent texture characteristics of the pulp arising from its manufacturing process. This characteristic effectively limits the geometries which can be used in a pulp container and makes it more difficult to achieve a leak-resistant design.

SUMMARY OF THE INVENTION

The disclosed embodiments provide leak-resistant, resealable containers, e.g., for food products. The disclosed embodiments include containers designed for liquids, e.g., soup containers, and the like. The leak-resistance is maintained even when the container is tilted so that the liquid contained therein reaches the seam where the bottom (i.e., tray) and lid of the container are joined.

The disclosed embodiments also provide various shapes of the lid and tray rims which form locking mechanisms to keep the lid attached to the bottom portion of the container.

In one aspect, the present invention provides a leak-resistant pulp container with a plastic lid, including a tray formed of molded pulp and having a bottom and a sidewall forming an interior volume. The tray has an edge extending peripherally outward from an upper edge of the sidewall, and the tray edge having an outer portion. The container further includes a plastic lid having an edge extending peripherally outward therefrom, and the lid edge having an outer portion. The lid edge and the tray edge each has a corresponding peripheral channel configured so that one of the peripheral channels is received in the other of the peripheral channels to secure the lid to the tray, each of the peripheral channels comprising an inner wall and an outer wall joined by a horizontal channel wall. The outer wall of the peripheral channel of the lid edge has a protrusion which mates with the outer portion of the tray edge to create an interference fit between the lid edge and the tray edge to secure the lid to the tray.

Embodiments of the present invention may include one or more of the following features.

The inner wall of the peripheral channel of the tray edge may have a sealing surface which presses against a corresponding sealing surface of the inner wall of the peripheral channel of the lid edge when the lid is secured to the tray, thereby forming a leak-resistant seal between the lid edge and the tray edge. The lid edge may be configured so that the outer wall of the peripheral channel of the lid edge applies force to the outer portion of the tray edge to force the sealing surface of the tray edge against the sealing surface of the lid edge. The sealing surfaces of the lid edge and the tray edge may extend to include at least a portion of the horizontal channel walls of the lid edge and the tray edge. The inner wall of the peripheral channel of the lid edge and the inner wall of the peripheral channel of the tray edge may be dimensioned to at least partially overlap in a cross-sectional plane, thereby forcing the sealing surface of the tray edge against the sealing surface of the lid edge when the lid is secured to the tray.

The protrusion of the outer wall of the peripheral channel of the lid edge may have a lower lip which extends inward to keep the outer portion of the tray edge in place in the protrusion, thereby acting to secure the lid to the tray. The lower lip of the protrusion of the outer wall of the peripheral channel of the lid edge may be formed in separate peripheral segments around the periphery of the lid.

The inner wall of the peripheral channel of the tray edge may form a draft angle with respect to a vertical direction of the container, when upright, of between about 8 degrees and about 12 degrees. The draft angle of the inner wall of the peripheral channel of the tray edge may be between about 10 degrees and about 12 degrees.

The outer portion of the tray edge may be substantially flat in a horizontal plane of the container when upright. A tab may extend from the lid edge and beyond the tray edge. The tray and the lid each may have a substantially oval shape.

The lid may be formed of any of the following plastic materials: high density polyethylene (HDPE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polylactic acid (PLA). The lid may be formed by a thermoforming process. The lid may be formed by an injection molding process.

In another aspect, the present invention provides a leak-resistant pulp container with a plastic lid, including a tray formed of molded pulp and having a bottom and a sidewall forming an interior volume. The tray has an edge extending peripherally outward from an upper edge of the sidewall, the tray edge having an outer portion. The container further includes a plastic lid having an edge extending peripherally outward therefrom, the lid edge having an outer portion. The lid edge and the tray edge each has a corresponding lock portion configured so that one of the lock portions mates with the other of the lock portions to secure the lid to the tray. The lid edge and the tray edge each has a corresponding seal portion configured so that one of the seal portions presses against the other of the seal portions when the lid is secured to the tray, thereby forming a leak-resistant seal between the lid edge and the tray edge.

Embodiments of the present invention may include one or more of the following features.

The seal portions of the lid edge and the tray edge may be formed in an inner portion of the lid edge and the tray edge with respect to the lock portions of the lid edge and the tray edge. The lock portion of the lid edge may include an outer wall having a protrusion which mates with the outer portion of the tray edge to create an interference fit between the lid edge and the tray edge to secure the lid to the tray. The lid edge may be configured so that the outer wall of the lock portion applies force to the outer portion of the tray edge to force the seal portion of the tray edge against the seal portion of the lid edge.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects and advantages will become more apparent and more readily appreciated from the following detailed description of the disclosed embodiments taken in conjunction with the accompanying drawings of which:

FIG. 1 shows a perspective view of an embodiment of a resealable leak-resistant container having a molded pulp tray with a plastic lid.

FIG. 2 shows a perspective view of the molded pulp tray of the container of FIG. 1.

FIG. 3 shows a top plan view of the container of FIG. 1.

FIG. 4 shows a top plan view of a resealable leak-resistant container having a square shape.

FIG. 5 shows a top plan view of a resealable leak-resistant container having a round shape.

FIG. 6 shows a vertical cross-sectional view of the container of FIG. 1 taken along line A-A depicted in FIG. 3.

FIG. 7 shows an enlargement of Region B of FIG. 6 showing the peripheral edge of the lid interlocking with the peripheral edge of the tray.

FIG. 8 shows a theoretical view of the enlargement of Region B of FIG. 6 showing the dimensional overlap of the peripheral edge of the lid and the peripheral edge of the tray, as designed.

DETAILED DESCRIPTION

FIGS. 1-3 show an embodiment of a resealable leak-resistant container 100 having a molded pulp tray 110 with a plastic lid 120. The tray 110 has a bottom 115 and a sidewall 117 forming an interior volume (see, e.g., FIG. 2). The tray 110 has an edge 125 extending peripherally outward from an upper edge of the sidewall 117. The tray 110 and the lid 120 each has a substantially oval shape (see, e.g., FIG. 3). Although, other shapes are also possible, such as square (see FIG. 4) or round (see FIG. 5). A tab 135 may extend from the lid edge 130 and beyond the tray edge 125. The inward facing lip portions 185 are described below in the discussion of FIG. 7.

The lid 120 of the leak-resistant pulp container 100 may be formed of any of the following plastic materials: high density polyethylene (HDPE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polylactic acid (PLA). The plastic lid can be formed by various processes, including, for example, thermoforming and injection molding.

The tray 110 of the leak-resistant pulp container 100 is formed of pulp which has undergone a pressing and molding process. The pulp may be formed of various fibrous materials, such as, for example, Bagasse, bamboo, wheat straw, wood, etc. The pulp is processed by pouring a suspension of pulp material and liquid (e.g., water) into a mold having a cavity with a number of holes and which is covered with a very fine mesh. The liquid is suctioned away, and the collected fibers on the mesh are pressed between two corresponding heated molds to squeeze out additional liquid. In further steps, additional pressing and heat processes may be applied to form and dry the final parts.

FIG. 6 shows a vertical cross-sectional view of the container 100 of FIG. 1 (when upright) taken along line A-A depicted in FIG. 3. It can be seen in this view that the lid edge 130 and the tray edge 125 each has a corresponding peripheral channel 140 configured so that one of the peripheral channels is received in the other of the peripheral channels to secure the lid 120 to the tray 110. In the embodiment depicted, the peripheral channel 140 of the tray edge 125 is received into the peripheral channel 140 of the lid edge 130.

FIG. 7 shows an enlargement of Region B of FIG. 6 showing the peripheral edge of the lid 130 interlocking with the peripheral edge of the tray 125. The peripheral channel 140 of the lid edge 130 has an inner wall 145 and an outer wall 150 joined by a horizontal channel wall 155. Similarly, the peripheral channel 140 of the tray edge 125 has an inner wall 160 and an outer wall 165 joined by a horizontal channel wall 170. In the embodiment depicted, the tray edge 125 has an outer portion 180 which is substantially flat in a horizontal plane of the container 100. The plastic lid 120 also has an edge extending peripherally outward therefrom which has a substantially flat outer portion 182.

The outer wall 150 of the peripheral channel 140 of the lid edge 130 has a protrusion 175 which mates with the outer portion 180 of the tray edge 125 to create an interference fit between the lid edge 130 and the tray edge 125 to secure the lid 120 to the tray 110. The inner wall 160 of the peripheral channel 140 of the tray edge 125 has a sealing surface 162 which presses against a corresponding sealing surface 147 of the inner wall 145 of the peripheral channel 140 of the lid edge 130 when the lid 120 is secured to the tray 110, thereby forming a leak-resistant seal between the lid edge 130 and the tray edge 125. The sealing surfaces (147, 162) of the lid edge 130 and the tray edge 125 may extend to include at least a portion of the horizontal channel walls (155, 170) of the lid edge 130 and the tray edge 125.

The inner wall 160 of the peripheral channel 140 of the tray edge 125 may form a draft angle with respect to a vertical direction of the container (when upright) of between about 8 degrees and about 12 degrees, or between about 10 degrees and about 12 degrees. In the embodiment depicted, the draft angle is about 12 degrees. The draft angle of the inner wall 162 of the lid edge 130 is substantially equal to that of the inner wall 160 of the tray edge 125 in order to achieve a strong seal.

The protrusion 175 of the outer wall 150 of the peripheral channel 140 of the lid edge 130 has a lower lip 185 which extends inward to keep the outer portion 180 of the tray edge 125 in place in the protrusion 175, thereby acting to secure the lid 120 to the tray 110. The lower lip 185 may be formed continuously around the periphery of the lid 120 or in separate peripheral segments (see, e.g., FIG. 1).

FIG. 8 shows a theoretical view of the enlargement of Region B of FIG. 6 showing the dimensional overlap, i.e., interference fit, of the peripheral edge of the lid 130 and the peripheral edge of the tray 125, as designed. The inner wall 145 of the peripheral channel 140 of the lid edge 130 and the inner wall 160 of the peripheral channel 140 of the tray edge 125 are dimensioned to at least partially overlap in a cross-sectional plane. This, in turn, helps force the sealing surface 162 of the tray edge 125 against the sealing surface 147 of the lid edge 130 when the lid 120 is secured to the tray 110. The view depicted is theoretical, in the sense that the dimensionally-overlapping portions will actually deform slightly and abut each other when the container is closed.

In addition, the lid edge 130 may be configured so that the outer wall 150 of the peripheral channel 140 of the lid edge 130, and in particular the protrusion 175 formed therein, applies force to the outer portion 180 of the tray edge 125 to force the sealing surface 162 of the tray edge 125 against the sealing surface 147 of the lid edge 130. This may be done by dimensioning the outer portion 180 of the tray edge 125 so that it has dimensional overlap, i.e., an interference fit, with the protrusion 175, as shown in FIG. 8.

Although example embodiments have been shown and described in this specification and figures, it would be appreciated by those skilled in the art that changes may be made to the illustrated and/or described example embodiments without departing from their principles and spirit.

Claims

1. A leak-resistant pulp container with a plastic lid, comprising:

a tray formed of molded pulp and having a bottom and a sidewall forming an interior volume, the tray further comprising an edge extending peripherally outward from an upper edge of the sidewall, the tray edge having an outer portion; and

a plastic lid having an edge extending peripherally outward therefrom, the lid edge having an outer portion,

wherein the lid edge and the tray edge each has a corresponding peripheral channel configured so that one of the peripheral channels is received in the other of the peripheral channels to secure the lid to the tray, each of the peripheral channels comprising an inner wall and an outer wall joined by a horizontal channel wall, and

wherein the outer wall of the peripheral channel of the lid edge has a protrusion which mates with the outer portion of the tray edge to create an interference fit between the lid edge and the tray edge to secure the lid to the tray.

2. The leak-resistant pulp container of claim 1, wherein the inner wall of the peripheral channel of the tray edge has a sealing surface which presses against a corresponding sealing surface of the inner wall of the peripheral channel of the lid edge when the lid is secured to the tray, thereby forming a leak-resistant seal between the lid edge and the tray edge.

3. The leak-resistant pulp container of claim 2, wherein the lid edge is configured so that the outer wall of the peripheral channel of the lid edge applies force to the outer portion of the tray edge to force the sealing surface of the tray edge against the sealing surface of the lid edge.

4. The leak-resistant pulp container of claim 2, wherein sealing surfaces of the lid edge and the tray edge extend to include at least a portion of the horizontal channel walls of the lid edge and the tray edge.

5. The leak-resistant pulp container of claim 2, wherein the inner wall of the peripheral channel of the lid edge and the inner wall of the peripheral channel of the tray edge are dimensioned to at least partially overlap in a cross-sectional plane, thereby forcing the sealing surface of the tray edge against the sealing surface of the lid edge when the lid is secured to the tray.

6. The leak-resistant pulp container of claim 1, wherein the protrusion of the outer wall of the peripheral channel of the lid edge has a lower lip which extends inward to keep the outer portion of the tray edge in place in the protrusion, thereby acting to secure the lid to the tray.

7. The leak-resistant pulp container of claim 6, wherein the lower lip of the protrusion of the outer wall of the peripheral channel of the lid edge is formed in separate peripheral segments around the periphery of the lid.

8. The leak-resistant pulp container of claim 1, wherein inner wall of the peripheral channel of the tray edge forms a draft angle with respect to a vertical direction of the container, when upright, of between about 8 degrees and about 12 degrees.

9. The leak-resistant pulp container of claim 8, wherein the draft angle of the inner wall of the peripheral channel of the tray edge is between about 10 degrees and about 12 degrees.

10. The leak-resistant pulp container of claim 1, wherein the outer portion of the tray edge is substantially flat in a horizontal plane of the container when upright.

11. The leak-resistant pulp container of claim 1, wherein a tab extends from the lid edge and beyond the tray edge.

12. The leak-resistant pulp container of claim 1, wherein the tray and the lid each has a substantially oval shape.

13. The leak-resistant pulp container of claim 1, wherein the lid is formed of any of the following plastic materials: high density polyethylene (HDPE), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polylactic acid (PLA).

14. The leak-resistant pulp container of claim 1, wherein the lid is formed by a thermoforming process.

15. The leak-resistant pulp container of claim 1, wherein the lid is formed by an injection molding process.

16. A leak-resistant pulp container with a plastic lid, comprising:

a tray formed of molded pulp and having a bottom and a sidewall forming an interior volume, the tray further comprising an edge extending peripherally outward from an upper edge of the sidewall, the tray edge having an outer portion; and

a plastic lid having an edge extending peripherally outward therefrom, the lid edge having an outer portion,

wherein the lid edge and the tray edge each has a corresponding lock portion configured so that one of the lock portions mates with the other of the lock portions to secure the lid to the tray, and

wherein the lid edge and the tray edge each has a corresponding seal portion configured so that one of the seal portions presses against the other of the seal portions when the lid is secured to the tray, thereby forming a leak-resistant seal between the lid edge and the tray edge.

17. The leak-resistant pulp container of claim 16, wherein the seal portions of the lid edge and the tray edge are formed in an inner portion of the lid edge and the tray edge with respect to the lock portions of the lid edge and the tray edge.

18. The leak-resistant pulp container of claim 16, wherein the lock portion of the lid edge comprises an outer wall having a protrusion which mates with the outer portion of the tray edge to create an interference fit between the lid edge and the tray edge to secure the lid to the tray.

19. The leak-resistant pulp container of claim 16, wherein the lid edge is configured so that the outer wall of the lock portion applies force to the outer portion of the tray edge to force the seal portion of the tray edge against the seal portion of the lid edge.