JP7766459B2 - food packaging containers - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies Date posted on website: October 1, 2021 Website address: https://bookshelf.wisebook4.jp/html/denkawebbook/43972/#6 [Publications, etc.] Date of issue: October 1, 2021 Publication: Public relations magazine "The Denka Way" 2021 Autumn vol. 09 [Publications, etc.] Date of sale: See supplementary material "List of shipment records" Place of sale: See supplementary material "List of shipment records"

The present invention relates to a food packaging container for packaging foods such as sandwiches and other prepared foods.

Food packaging containers are known that are formed by vacuum forming synthetic resin sheet material. For example, this type of container is formed by vacuum-adhering the sheet material to a specified mold while heating it, forming it to the shape of the mold, and then removing the container from the mold (demolding). Vacuum forming can also be used to form containers of various shapes, as long as they are demoldable. For example, as shown in Patent Document 1, a known container has walls that stand up from the four corners of a rectangular bottom. The inside of the walls is a flat release surface formed as a bag-shaped inner periphery. The release surface is released from the mold, forming the wall of the desired shape.

Japanese Patent Application Laid-Open No. 2004-155466

To facilitate demolding, pressurized air or other means may be supplied toward the gap between the release surface and the mold. However, when the flat release surface is tightly attached to the mold, it is difficult to create a gap large enough for air to penetrate between the release surface and the mold, resulting in insufficient demolding, resulting in defects such as defective products and reduced yields.

The present invention aims to solve the above problems and provide a food packaging container that is easy to release from the mold after molding.

The present invention relates to a food packaging container formed from a bent sheet material, which comprises a bottom and a wall extending from the bottom. The wall has a release surface that forms the inner periphery of a bag. The release surface has a closed tip that is the end of the wall in the direction in which it is extended, an open portion that is the end opposite the tip in the direction in which it is extended, and a side surface between the tip and the open portion. The side surface is provided with a vertical rib that is convex or concave with respect to the internal space facing the release surface and extends along the direction in which it is extended.

A vacuum forming mold, such as a metal mold, is fitted into the internal space inside the wall and is in close contact with the release surface. When releasing, the vacuum forming mold moves relative to the wall in a direction away from the wall, and as a result, moves as if being pulled out through the open section. For example, if the contact surface between the release surface and the vacuum forming mold is flat all over, the pressurized air supplied for release will disperse, making it difficult for gaps that trigger release to occur.

In contrast, the food packaging container of the present invention has vertical ribs on the side of the release surface, which are convex or concave relative to the internal space and extend in the direction of the wall. After molding, the convex or concave shape of the vertical ribs disrupts the flatness of the contact surface between the vacuum forming mold and the release surface, making it prone to gaps. When pressurized air is supplied from the open side toward the vertical ribs in this state, the pressurized air enters the contact surface of the vertical ribs and forms gaps for release. This gap then acts as an opportunity for pressurized air to enter the entire contact surface, facilitating release. As a result, the above-mentioned food packaging container facilitates release from the mold.

The above-mentioned food packaging container may have multiple vertical ribs, at least some of which may be convex relative to the internal space. After molding, the convex shape of the vertical ribs disrupts the flatness of the contact surface between the vacuum forming mold and the release surface, making it easier for gaps to form and facilitating release from the mold.

In the above-mentioned food packaging container, the wall portion has an outer peripheral surface opposite the release surface, the vertical ribs are convex and protrude toward the interior space, and the outer peripheral surface may be provided with concave ribs that are recessed to overlap the vertical ribs and extend along the vertical direction. Since the upper food packaging container can be stacked so that the vertical ribs of the lower food packaging container overlap the concave ribs of the upper food packaging container, multiple food packaging containers can be stacked and stored in a compact state.

In the above-mentioned food packaging container, the wall portion has a standing wall portion provided along at least a portion of the periphery of the bottom portion, and the release surface, which is the inner periphery of the standing wall portion, has an inner release surface on the bottom side and an outer release surface facing the inner release surface and provided on the outside farther from the bottom than the inner release surface, and the vertical ribs may be provided on the outer release surface. The vertical ribs make it easier for gaps to occur at the contact surface between the outer release surface and the vacuum forming mold, facilitating release from the mold.

In the above-mentioned food packaging container, the release surface has a reference surface that extends along the shape of the peripheral edge of the bottom, and the vertical ribs are convex, protruding from the reference surface toward the internal space, and the amount of protrusion of the vertical ribs may gradually decrease from the open end side to the tip end side. By increasing the amount of protrusion of the vertical ribs on the open end side, the area where gaps are formed that encourage the initial entry of pressurized air is widened. On the other hand, the amount of protrusion at the tip end is reduced, allowing the internal space on the tip end side of the vertical wall to be reduced.

In the above-mentioned food packaging container, the wall portion has an outer peripheral surface opposite the release surface, the vertical ribs are concave and recessed into the internal space, and the outer peripheral surface may be provided with convex ribs that protrude to overlap the vertical ribs and extend along the vertical direction. The upper food packaging container can be stacked so that the vertical ribs of the lower food packaging container overlap the convex ribs of the upper food packaging container, allowing multiple food packaging containers to be stacked and stored in a compact state.

In the above-mentioned food packaging container, the peripheral edge of the bottom may have curved, bent corners, and the standing wall may be provided along the corners. This also makes it easier to release the container from the mold from the standing wall provided along the corners.

In the above-mentioned food packaging container, the bottom may have multiple opposing corners, and upright walls may be provided along each corner. After molding, the food packaging container hardens while shrinking relative to the vacuum forming mold. For example, if the food packaging container has multiple opposing polygonal corners, it may shrink in the opposing direction of the corners, hindering release from the mold. However, by providing vertical ribs on the multiple upright walls provided along the corners, the possibility of hindering release can be reduced.

The food packaging container of the present invention is easy to release from the mold after molding.

1 is a side view of a food packaging container according to one embodiment of the present invention. FIG. 1 is a plan view of a food packaging container. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 2 is an enlarged plan view showing the vertical wall portion of the food packaging container. FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5. FIG. 2 is a perspective view showing the state in which the lid is attached to the food packaging container. FIG. 10 is a cross-sectional view showing a first modified embodiment of the longitudinal rib. FIG. 10 is a cross-sectional view showing a second modified embodiment of the longitudinal rib. Other modified forms of the longitudinal rib are shown, where (a) is a plan view showing a third modified form, (b) is a plan view showing a fourth modified form, (c) is a plan view showing a fifth modified form, and (d) is a cross-sectional view showing a sixth modified form. Other variations of the longitudinal rib are shown, with (a) being a schematic plan view showing the seventh variation, (b) being a schematic plan view showing the eighth variation, and (c) being a schematic plan view showing the ninth variation. 1 shows a process for manufacturing a food packaging container, where (a) shows the process of vacuum-forming a sheet material, and (b) shows the process of releasing the sheet material on which the food packaging container has been formed from the mold. 1A and 1B are diagrams showing the process of releasing the sheet material from the mold, where FIG. 1A is a cross-sectional view of the food packaging container and the mold, and FIG. 1B is a cross-sectional view along line bb in FIG. 1A. 1A and 1B are diagrams showing the process of releasing the sheet material from the mold in the first modified form of the vertical rib, where (a) is a cross-sectional view of the food packaging container and the mold, and (b) is a cross-sectional view along line bb in (a). FIG. 10 is an explanatory diagram showing a state in which one container among a plurality of overlapping containers is being removed.

The following describes a food packaging container according to one embodiment of the present invention, with reference to the drawings. Note that the food packaging container of the present invention is not limited to this embodiment.

As shown in Figures 1 and 7, the food packaging container (hereinafter referred to as "container") 1 of this embodiment is a container for storing food F, such as a sandwich, and a food package 10 is formed by attaching a lid 2. In Figure 1, the lid 2 attached to the container 1 is shown by a two-dot chain line. Note that in this embodiment, the container 1 and the lid 2 are separate entities, and the food package 10 is formed by attaching the lid 2 to the container 1; however, the lid 2 may also be integrally molded with the container 1 via a hinge or the like.

Container 1 is formed from a bent sheet material S (see Figure 12) and has one surface (front side) that contacts and holds food F, and an opposite surface (back side). Container 1 is formed by vacuum forming sheet material S, and the back side is the surface that is in close contact with mold 102 (an example of a vacuum forming mold) and is also the surface that is released from mold 102 (demolded). In the following description, the side containing food F is referred to as the upper side and the opposite side as the lower side, based on the assumption that container 1 containing food F is placed and stabilized on a horizontal surface such as a table.

The container 1 comprises a bottom 3 and a wall 4 extending from the bottom 3. The bottom 3 is the portion on which food F is placed. The wall 4 is provided along the periphery 3a of the bottom 3 to surround the bottom 3, and abuts the food F from the side to hold the food F in place. In the following description, the extending direction Rd of the wall 4 (see Figure 5) refers to the direction moving upward away from the bottom 3, with the bottom 3 as the reference point.

As shown in Figure 2, the shape of the bottom 3 when viewed from above, i.e., when viewed in plan, can be determined appropriately to match the shape of the food F to be placed on it. In this embodiment, a substantially square shape with curved corners 3b in plan view is shown as an example. However, the shape of the bottom 3 may also be rectangular, polygonal such as triangular or pentagonal, or curved such as circular or elliptical.

The corners 3b of the bottom 3 have legs 3c protruding from the back side (see Figure 3). The bottom 3 also has reinforcing ribs 3d as needed.

As shown in Figure 3, the wall portion 4 has a mountain-like shape that curves upward and protrudes, and the back side of the wall portion 4 is bag-shaped. During vacuum molding, a mold 102 (see Figure 12) is placed on the back side of the wall portion 4. When the mold 102 is released, an internal space A is formed on the back side of the wall portion 4. The inner periphery of the bag-shaped portion facing the internal space A is the release surface 5, which has a shape that follows the mold 102.

As shown in Figures 1 and 3, the wall portion 4 comprises an inner wall portion 41 that is bent and erected from the bottom portion 3, an outer wall portion 42 that is provided opposite the inner wall portion 41, and an upper wall portion 43 that is provided between the inner wall portion 41 and the outer wall portion 42. The inner wall portion 41 is provided continuously around the entire periphery 3a of the bottom portion 3. The inner wall portion 41 comprises a lower inner wall portion 41a that is connected to the periphery 3a of the bottom portion 3, and an upper inner wall portion 41b that is connected to the upper wall portion 43. The inner area surrounded by the upper inner wall portion 41b is larger than the inner area surrounded by the lower inner wall portion 41a. The inner wall portion 41 is tapered from the lower inner wall portion 41a to the upper inner wall portion 41b so that the inner area expands.

Like the inner wall portion 41, the outer wall portion 42 is provided without interruption around the entire circumference of the bottom portion 3. The outer wall portion 42 comprises an upper outer wall portion 42a connected to the upper wall portion 43, and a lower outer wall portion 42b that is located at the lower end of the upper outer wall portion 42a and protrudes outward. Between the upper outer wall portion 42a and the lower outer wall portion 42b of the outer wall portion 42, there is provided a lid locking portion 42c that fits onto the inner circumference of the lid body 2 to hold the lid body 2, and a lid seat portion 42d that abuts against the flange portion 21 (see Figure 1) provided on the outer edge of the lid body 2 and supports the lid body 2.

As shown in Figures 1 and 2, the upper wall portion 43 includes a plurality of vertical wall portions 6 and connecting wall portions 7 that connect the vertical wall portions 6. The vertical wall portions 6 are arranged to protrude further upward than the connecting wall portions 7. In this embodiment, the multiple vertical wall portions 6 are arranged diagonally across the quadrilateral bottom portion 3 and are arranged along each of the multiple corners 3b of the bottom portion 3. In other words, the multiple vertical wall portions 6 are arranged to face each other across the bottom portion 3. The connecting wall portions 7 and the vertical wall portions 6, for example, abut against the inner periphery of the lid body 2 to support the lid body 2. Furthermore, the vertical wall portions 6 protrude taller than the connecting wall portions 7, and laterally support and stably hold food F placed on the bottom portion 3.

Next, the standing wall portion 6 will be described with reference to Figures 4 and 5. The multiple standing wall portions 6 basically have the same shape and structure, and one standing wall portion 6 will be described as a representative. The standing wall portion 6 is bent to form a mountain shape that is taller than the connecting wall portion 7 (see Figure 3). In cross section, the standing wall portion 6 is roughly inverted V-shaped and includes an inner wall portion 61 connected to the inner wall portion 41, an outer wall portion 62 connected to the outer wall portion 42, and an upper end wall portion 63 connected to the upper portion of the inner wall portion 61 and the upper portion of the outer wall portion 62. The inner wall portion 61 and the outer wall portion 62 are inclined so that the distance between them is smaller at the upper portion than at the lower portion.

The inner periphery of the standing wall portion 6 is part of the release surface 5. The release surface 5 of the standing wall portion 6 has a tip portion 51, which is the end (upper end) of the wall portion 4 in the standing direction Rd, and an open portion 52, which is the end (lower end) on the opposite side of the tip portion 51 in the standing direction Rd. The tip portion 51 closes the internal space A, and the open portion 52 opens the internal space A. The tip portion 51 essentially corresponds to the inner periphery of the upper end wall portion 63.

The release surface 5 of the standing wall portion 6 has a side portion 53 located between the tip portion 51 and the open portion 52. The side portion 53 has a vertical rib 8. The vertical rib 8 extends along the standing direction Rd. The side portion 53 has an inner release surface 53a, which is the inner periphery of the inner wall portion 61, and an outer release surface 53b, which is the inner periphery of the outer wall portion 62. The inner release surface 53a is the release surface 5 on the bottom 3 side, and the outer release surface 53b can also be described as a release surface 5 that faces the inner release surface 53a and is located outward, farther from the bottom 3 than the inner release surface 53a.

Figure 6 is a cross-sectional view of the standing wall portion 6 cut along a plane intersecting (e.g., perpendicular to) the standing direction Rd of the standing wall portion 6. Note that the standing direction Rd of the standing wall portion 6 essentially means the standing direction Rd of the wall portion 4. As shown in Figure 6, the inner release surface 53a is curved to follow the peripheral edge 3a of the bottom portion 3. The outer release surface 53b has a reference surface 53x that is curved to follow the shape of the inner release surface 53a. Because the reference surface 53x follows the shape of the inner release surface 53a, it can be said that, like the inner release surface 53a, it extends to follow the shape of the peripheral edge 3a of the bottom portion 3.

The vertical ribs 8 according to this embodiment are provided on the outer release surface 53b and are provided so as to be convex toward the internal space A in a cross-sectional view. Note that the convex shape of the vertical ribs 8 means that they are provided so as to protrude toward the internal space A beyond the reference surface 53x of the outer release surface 53b. Furthermore, although the vertical ribs 8 according to this embodiment protrude toward the internal space A while being curved, they may also have a shape that protrudes toward the internal space A due to a bent shape.

The vertical ribs 8 (see Figure 5) according to this embodiment are provided continuously and without interruption from the open portion 52 of the release surface 5 to the tip 51. The upper ends of the vertical ribs 8 may reach the tip 51 or may be slightly spaced apart from the tip 51.

As described above, the vertical ribs 8 protrude into the internal space A. The degree of this protrusion can be described as the protrusion amount D of the vertical ribs 8. The protrusion amount D of the vertical ribs 8 can be determined at each position along the erection direction Rd of the vertical wall portion 6. For example, when viewing the vertical wall portion 6 in a cross section perpendicular to the erection direction Rd (see Figure 6), first imagine an imaginary reference plane 53y where the reference plane 53x of the outer release surface 53b extends to the vertical rib 8. Next, identify the position on the vertical rib 8 on the cross section that is farthest from the imaginary reference plane 53y. The distance from this position to the imaginary reference plane 53y is the protrusion amount D of the vertical rib 8. The protrusion amount D of the vertical rib 8 is greatest on the open portion 52 side and smallest on the tip end 51 side. Furthermore, the protrusion amount D of the vertical rib 8 gradually decreases from the open portion 52 side to the tip end 51 side.

The outer wall portion 62 of the standing wall portion 6 has an outer peripheral surface 62a that is opposite the outer release surface 53b. The outer peripheral surface 62a is provided with recessed ribs 62b that are recessed so as to overlap the vertical ribs 8. Like the vertical ribs 8, the recessed ribs 62b extend along the standing direction Rd.

In the above-described embodiment, the height H of the upright wall portion 6 is, for example, 10 mm to 15 mm. The outer wall portion 62 and the inner wall portion 61 are inclined with respect to an imaginary plane perpendicular to the bottom portion 3. For example, the inclination angle α between a reference plane parallel to the bottom portion 3 and passing through the opening and the outer release surface 53b of the outer wall portion 62 is, for example, 70° to 85°. The inclination angle β between the reference plane and the inner release surface 53a of the inner wall portion 61 is, for example, 70° to 85°. The protrusion amount D of the vertical rib 8 is maximum on the open portion 52 side, and this maximum value is, for example, 0.4 mm to 1.0 mm. When viewed in cross section, the vertical rib 8 is arc-shaped, and the radius of curvature of the vertical rib 8 is, for example, 0.5 mm to 2.0 mm.

Here, we will explain modified forms of the vertical rib 8. Figure 8 is a cross-sectional view showing a first modified form of the vertical rib 8. As shown in Figure 8, the vertical rib 8A according to the first modified form is provided on the outer release surface 53b, and is provided so as to be concave with respect to the internal space A in a cross-sectional view. Note that the concave shape of the vertical rib 8 refers to a shape that protrudes toward the opposite side of the internal space A from the reference surface 53x. In other words, the concave shape of the vertical rib 8 can also be described as a shape that protrudes in the direction in which the internal space A expands. Note that the concave shape of the vertical rib 8 may be a curved or bent shape.

The degree to which the vertical rib 8A is recessed relative to the internal space A can be described as the recess depth Dp of the vertical rib 8A. Similar to the protrusion amount D, the recess depth Dp can be determined at each position along the erection direction Rd of the vertical wall portion 6. For example, when viewing the vertical wall portion 6 in a cross section perpendicular to the erection direction Rd (see Figure 8), first imagine an imaginary reference plane 53y where the reference plane 53x of the outer release surface 53b extends to the vertical rib 8. Next, identify the position on the vertical rib 8A on the cross section that is farthest from the imaginary reference plane 53y. The distance from this position to the imaginary reference plane 53y is the recess depth Dp of the vertical rib 8A. The recess depth Dp of the vertical rib 8A is greatest on the open portion 52 side and smallest on the tip end 51 side. Furthermore, the recess depth Dp of the vertical rib 8A gradually decreases from the open portion 52 side to the tip end 51 side.

The maximum value of the recess depth Dp on the open portion 52 side is, for example, 0.4 mm to 1.0 mm. When viewed in cross section, the vertical rib 8A is arc-shaped, and the radius of curvature of the vertical rib 8 is, for example, 0.5 mm to 2.0 mm.

The outer wall portion 62 of the standing wall portion 6 has an outer peripheral surface 62a that is opposite the outer release surface 53b. The outer peripheral surface 62a is provided with a protruding rib 62c that protrudes so as to overlap the vertical rib 8A. Like the vertical rib 8A, the protruding rib 62c extends along the standing direction Rd.

Figure 9 is a cross-sectional view showing a second modified form of the vertical rib 8. As shown in Figure 9, the inner release surface 53a has a reference surface 53z that extends to follow the shape of the peripheral edge 3a of the bottom 3. The vertical rib 8B according to the second modified form is provided on the inner release surface 53a and is provided so as to be convex with respect to the internal space A in a cross-sectional view. In other words, the vertical rib 8B is provided so as to protrude further into the internal space A than the reference surface 53z of the inner release surface 53a. Note that the vertical rib 8 provided on the inner release surface 53a may also be concave with respect to the internal space A. In other words, the vertical rib 8 may be provided so as to protrude further toward the opposite side of the internal space A than the reference surface 53z of the inner release surface 53a.

Figures 10(a) to 10(c) are plan views showing various variations of the vertical rib 8. Note that, because Figures 10(a) to 10(c) are plan views, they do not directly show the release surface 5, which is the back surface, but for convenience, the vertical ribs 8C, 8D, and 8E are shown in solid lines.

As shown in Figure 10(a), in the third modified embodiment, multiple vertical ribs 8C are provided on the outer release surface 53b. In the third modified embodiment, multiple vertical ribs 8 are provided in a row along the peripheral edge 3a of the bottom 3. The vertical ribs 8 may have the same shape and dimensions, or may have different shapes and dimensions. Note that in the illustrated example, the vertical ribs 8C in the third modified embodiment protrude convexly from the outer release surface 53b toward the internal space A, but they may also be concave, or may be provided on the inner release surface 53a.

As shown in Figure 10 (b), the vertical ribs 8D according to the fourth modified embodiment are provided on the outer release surface 53b. In the fourth modified embodiment, the vertical ribs 8D are provided with a shorter length in the vertical direction Rd than the vertical ribs 8 according to the above-described embodiment. For example, the vertical ribs 8D are provided so as to extend to a midpoint between the open portion 52 and the tip portion 51. Note that, although the vertical ribs 8D according to the fourth modified embodiment are shown as protruding convexly from the outer release surface 53b toward the internal space A, they may also be concave, or may be provided on the inner release surface 53a.

As shown in Figure 10 (c), the vertical ribs 8E according to the fifth modified embodiment are provided on the outer release surface 53b. The vertical ribs 8E according to the fifth modified embodiment do not have a shape in which the protrusion amount D gradually decreases from the open portion 52 side to the tip end 51 side, but rather have a shape in which the same shape continues from the open portion 52 side to the tip end 51 side. Note that, although the vertical ribs 8E according to the fifth modified embodiment are shown as protruding convexly from the outer release surface 53b toward the internal space A, they may also be concave, or may be provided on the inner release surface 53a.

(d) of Figure 10 is a cross-sectional view showing a sixth modified form of the standing wall portion 6 and vertical rib 8. The vertical rib 8F in this sixth modified form is provided on the outer release surface 53b. The vertical rib 8F does not extend continuously from the open portion 52 side to the tip portion 51 side, but has a step along the way. Note that while the vertical rib 8F is shown as protruding convexly from the outer release surface 53b toward the internal space A, it may also be concave, or may be provided on the inner release surface 53a.

Figures 11(a) to 11(c) are plan views schematically showing various modified forms of the vertical wall portion 6 and bottom portion 3. Because Figures 11(a) to 11(c) are plan views, they do not directly show the release surface 5, which is the back surface, but for convenience, the vertical ribs 8 are shown in solid lines. As shown in Figures 11(a) to 11(c), the container 1 according to each modified form has, for example, vertical wall portions 6A, 6B, and 6C that surround the entire periphery of the bottom portions 3A, 3B, and 3C.

As shown in Figure 11(a), the container 1 according to the seventh modified embodiment has a bottom 3A that is approximately rectangular in plan view, and the vertical ribs 8 are provided at the corners 3b and approximately the centers of the long sides of the bottom 3A. As shown in Figure 11(b), the container 1 according to the eighth modified embodiment has a bottom 3B that is approximately triangular in plan view, and the vertical ribs 8 are provided at positions along the corners 3b of the bottom 3B. As shown in Figure 11(c), the container 1 according to the ninth modified embodiment has a bottom 3C that is elliptical in plan view, and the vertical ribs 8 are provided at multiple positions along the periphery 3a of the bottom 3C.

Next, the function and effect of the container 1 with vertical ribs 8 will be explained while explaining the manufacturing method of the container 1 with reference to Figures 12 and 13. The container 1 is made of a synthetic resin sheet material S and is manufactured by vacuum forming using a mold 102. The synthetic resin from which the container 1 is made can be polystyrene, polypropylene, or polyester, depending on the application. High impact polystyrene (HIPS), which has excellent impact resistance, is preferably used to stably hold food F. Alloys of these resins or laminates of these resins may also be used.

First, we will explain the molding machine 100. The molding machine 100 is equipped with a mold 102 (an example of a vacuum forming mold) for forming the sheet material S into a desired shape. Note that in Figures 12 and 13(a), the back side of the container 1 is shown facing upward and the front side facing downward.

The molding machine 100 includes, for example, a heating platen 103 (heating section) that heats the sheet material S, a mold 102 positioned opposite the heating platen 103 across the conveying path of the sheet material S, a movable device 104 (mold moving section) that moves the mold 102 to move the mold 102 toward or away from the sheet material S, and a conveying device (sheet conveying section) that conveys the sheet material S. In addition, as ancillary equipment of the molding machine 100 or as separate equipment from the molding machine 100, there is also equipment that is connected to the cavity 102a of the mold 102 to draw air and supply pressurized air into the cavity 102a (to apply air pressure).

The manufacturing method using this molding machine 100 is known as hot plate molding, and is an example of vacuum forming. The molding machine 100 has a mold 102 and a hot plate 103 arranged opposite each other, with the transport path of the sheet material S in between. A transport device transports the unprocessed portion of the sheet material S to a predetermined position. This predetermined position is a position between the mold 102 and the hot plate 103. At the predetermined position, the back surface of the sheet material S faces the cavity 102a of the mold 102.

Next, the movable device 104 is driven to move the mold 102 closer to the sheet material S, bringing the cavity 102a into contact with the sheet material S. The sheet material S is heated by the heating platen 103 from the side opposite the side facing the cavity 102a, and softens to the extent that it can be molded.

Next, the molding process is carried out. In this molding process, suction is applied to the heated sheet material S within the cavity 102a. As a result, the sheet material S comes into contact with the cavity 102a and deforms to conform to the shape of the cavity 102a, becoming a molded product. In this molding process, the temperature of the mold 102 is lower than that of the heated sheet material S. As a result, when the sheet material S comes into contact with the cavity 102a, the molded product shrinks. Note that the actual container 1 is created by cutting and separating the molded product from the sheet material S, but for the sake of convenience, the following explanation will also refer to the molded product before separation as container 1.

Next, a demolding process is performed to remove the container 1 from the mold 102. Figure 12(b) shows the demolding process. Figure 13(a) is an enlarged cross-sectional view of the vertical wall portion 6 and mold 102, showing the state in which pressurized air P is being supplied during the demolding process. Figure 13(b) is a cross-sectional view taken along line b-b in Figure 13(a), showing the area T to which pressurized air P is supplied surrounded by a two-dot chain line.

In the above molding process, the contact surface between the mold 102 and the container 1 becomes the mold release surface 5. In the mold 102, for example, the protrusion 102b forming the standing wall portion 6 is fitted into the internal space A inside the standing wall portion 6 and is in close contact with the mold release surface 5. In the mold release process, the protrusion 102b moves relative to the standing wall portion 6, for example, in a direction away from the standing wall portion 6, and as a result, moves as if being pulled out of the opening 52 and is released from the mold.

During demolding, pressurized air P is supplied to the contact surface between the mold 102 and the release surface 5 to promote separation between the mold 102 and the release surface 5, which are in close contact with each other. Here, if the contact surface between the release surface 5 and the mold 102 is flat and continuous over the entire surface, for example, the pressurized air P supplied for demolding will disperse without penetrating into the gaps at the contact surface, making it difficult for gaps that trigger demolding to occur.

In particular, the standing wall portion 6 is thinner than the other parts of the wall portion 4, and therefore the gap that forms in the internal space A facing the release surface 5 is also very narrow. As a result, there is a possibility that the container 1 will shrink during release and pinch the mold 102. As a result, when forming a thin wall portion 4 such as the standing wall portion 6 by vacuum forming the sheet material S, even if pressurized air P is supplied, release problems are likely to occur.

In contrast, in the container 1 according to the above embodiment, vertical ribs 8 are provided on the side surface 53 of the release surface 5. After vacuum molding, the convex shape of the vertical ribs 8 disrupts the flat continuity of the contact surface between the mold 102 and the release surface 5, making it easier for gaps to form (see Figure 13(a)). In this state, when pressurized air P is supplied toward the vertical ribs 8 from the open portion 52 side, the pressurized air P enters the contact surface of the vertical ribs 8 and forms gaps Sp for release. This gap Sp then triggers the pressurized air to enter the entire contact surface, facilitating release. As a result, the container 1 makes release easier.

Containers 1 according to other modified embodiments also achieve the same effect. For example, Figure 14(a) shows the first modified embodiment, and is an enlarged cross-sectional view of the vertical wall portion 6 provided with vertical ribs 8A and the mold 102 (protrusion 102b), illustrating the state in which pressurized air P is being supplied during the demolding process. Figure 14(b) is a cross-sectional view taken along line b-b in Figure 14(a), and shows the area Ta to which pressurized air P is supplied surrounded by a two-dot chain line.

In the first modified form, pressurized air P is also supplied toward the contact surface between the mold 102 and the release surface 5 to promote separation between the mold 102 and the release surface 5, which are in close contact with each other. In the container 1 according to the first modified form, after vacuum molding, the flat continuity of the contact surface between the mold 102 and the release surface 5 is interrupted by the concave shape of the vertical ribs 8A, making it easy for gaps to form. In this state, when pressurized air P is supplied toward the vertical ribs 8A from the open portion 52 side, the pressurized air P enters the contact surface of the vertical ribs 8A and forms gaps Sp for release. This gap Sp then triggers the pressurized air to enter the entire contact surface, promoting release. As a result, container 1 equipped with vertical ribs 8A facilitates release.

Containers 1 according to other modified embodiments also achieve similar effects. That is, containers 1 according to other modified embodiments are provided with vertical ribs 8B-8F, and after vacuum molding, the flat continuity of the contact surface between the mold 102 and the release surface 5 is interrupted by the convex or concave shape of the vertical ribs 8B-8F, making it easy for gaps to form. When pressurized air P is supplied toward the vertical ribs 8B-8F in this state, the pressurized air P enters through the contact surface of the vertical ribs 8B-8F and forms gaps Sp for release. This gap Sp then triggers the pressurized air to enter the entire contact surface, facilitating release. As a result, containers 1 equipped with vertical ribs 8B-8F facilitate release.

The container 1 according to this embodiment has multiple vertical wall portions 6, each of which has a vertical rib 8. In this embodiment, all of the multiple vertical ribs 8 are convex with respect to the internal space A that the release surface 5 faces. However, some of the multiple vertical ribs 8 may be convex with respect to the internal space A, and the rest may be concave.

In addition, the container 1 according to the embodiment has recessed ribs 62b that overlap the vertical ribs 8. Therefore, for example, the vertical ribs 8 of the upper container 1 can be placed over the recessed ribs 62b of the lower container 1 (see FIG. 15). As a result, multiple containers 1 can be stacked and stored in a compact manner. Furthermore, when the vertical ribs 8 are placed over the recessed ribs 62b, a small gap is likely to form between the recessed ribs 62b and the vertical ribs 8. As a result, a single container 1 can be easily removed from multiple stacked containers 1 without any difficulty. Note that, as shown in FIG. 8, the container 1 having the vertical ribs 8A according to the first modified embodiment also achieves the same effect. That is, in the container 1 having the vertical ribs 8A, the vertical ribs 8A of the upper container 1 can be placed over the protruding ribs 62c of the lower container 1. As a result, multiple containers 1 can be stacked and stored in a compact manner. Furthermore, when the vertical rib 8 is placed over the convex rib 62c, a small gap tends to form between the convex rib 62c and the vertical rib 8A. As a result, when removing one container 1 from multiple stacked containers 1, it can be removed easily and without strain.

In addition, in the container 1 according to this embodiment, the protrusion amount D of the vertical rib 8 gradually decreases from the open portion 52 side toward the tip portion 51 side. By increasing the protrusion amount D of the vertical rib 8 on the open portion 52 side, the area where gaps are formed that encourage the initial entry of pressurized air becomes larger. Note that the recess depth Dp of the vertical rib 8A according to the first modified embodiment gradually decreases from the open portion 52 side toward the tip portion 51 side. By increasing the recess depth Dp of the vertical rib 8A on the open portion 52 side, the area where gaps are formed that encourage the initial entry of pressurized air becomes larger.

Furthermore, the upright wall portions 6 of the container 1 are provided along the corners 3b of the bottom 3, and because vertical ribs 8 are provided on these upright wall portions 6, demolding is facilitated even for upright wall portions 6 provided along the corners 3b. In particular, the bottom 3 according to this embodiment has multiple corners 3b arranged opposite each other, and the upright wall portions 6 are provided along each corner 3b. After molding, the container 1 hardens while shrinking relative to the mold 102. For example, if the container 1 has multiple polygonal, opposing corners 3b, it may shrink in the opposing directions of the corners 3b, hindering demolding. However, by providing vertical ribs 8 on the multiple upright wall portions 6 provided along the corners 3b, the possibility of demolding being hindered can be reduced.

The present invention is not limited to the above-described embodiment. For example, the vertical wall portion may be erected directly from the bottom portion. Furthermore, the vertical ribs may have a mixture of convex and concave shapes relative to the internal space.

1...container (food packaging container), 3, 3A-3C...bottom, 3a...periphery, 3b...corner, 4...wall, 5...release surface, 6, 6A-6C...standing wall, 51...tip, 52...opening, 53...side, 8, 8A-8F...vertical rib, 53a...inner release surface, 53b...outer release surface, 53x...reference surface, A...internal space, D...protrusion amount, 62a...outer peripheral surface, 62b...concave rib, 62c...convex rib, P...compressed air, Rd...standing direction, S...sheet material, Sp...gap.

Claims (8)

A food packaging container formed from a bent sheet material,
The bottom and
a wall portion erected from the bottom portion,
The wall portion has a release surface that is a bag-shaped inner periphery,
the release surface comprises a closed tip portion which is an end of the wall portion in the standing direction, an open portion which is an end opposite to the tip portion in the standing direction, and a side portion which is between the tip portion and the open portion,
The side surface portion is provided with a vertical rib that is convex or concave with respect to an internal space that the release surface faces,
The vertical rib extends from the open portion to the tip portion along the upright direction. The longitudinal ribs are provided in plurality,
The food packaging container according to claim 1 , wherein at least some of the plurality of longitudinal ribs are convex with respect to the internal space. The wall portion has an outer peripheral surface opposite the release surface,
The longitudinal rib has a convex shape that protrudes toward the internal space,
3. The food packaging container according to claim 1, wherein the outer peripheral surface is provided with recessed ribs that are recessed to overlap the longitudinal ribs and extend along the vertical direction. The wall portion has a standing wall portion provided along at least a part of the periphery of the bottom portion, and the release surface which is the inner periphery of the standing wall portion has an inner release surface which is on the bottom portion side, and an outer release surface which faces the inner release surface and is provided on the outside farther from the bottom portion than the inner release surface,
The food packaging container according to any one of claims 1 to 3, wherein the vertical ribs are provided on the outer release surface. A food packaging container formed from a bent sheet material,
The bottom and
a wall portion erected from the bottom portion,
The wall portion has a release surface that is a bag-shaped inner periphery,
the release surface comprises a closed tip portion which is an end of the wall portion in the standing direction, an open portion which is an end opposite to the tip portion in the standing direction, and a side portion which is between the tip portion and the open portion,
The side surface portion is provided with a vertical rib that is convex or concave with respect to an internal space that the release surface faces and extends along the erection direction,
The wall portion has a standing wall portion provided along at least a part of the periphery of the bottom portion, and the release surface which is the inner periphery of the standing wall portion has an inner release surface which is on the bottom portion side, and an outer release surface which faces the inner release surface and is provided on the outside farther from the bottom portion than the inner release surface,
The longitudinal rib is provided on the outer release surface,
the release surface of the upright wall portion has a reference surface extending along the shape of the periphery of the bottom portion,
The vertical rib has a convex shape that protrudes from the reference surface toward the internal space,
The amount of protrusion of the vertical rib gradually decreases from the opening to the tip. The wall portion has an outer peripheral surface opposite the release surface,
The longitudinal rib is recessed relative to the internal space,
3. The food packaging container according to claim 1, wherein the outer peripheral surface is provided with a convex rib that projects so as to overlap the vertical rib and extends along the vertical direction. The peripheral edge of the bottom portion has curved corners,
6. The food packaging container according to claim 4, wherein the upright wall portion is provided along the corner portion. The bottom portion has a plurality of the corner portions arranged opposite to each other,
The food packaging container according to claim 7 , wherein the upright wall portions are provided along each of the corners.