Container with flange part and packaging having the container and lid

Abstract

To provide a container capable of sealing a flange part with a lid material by heat sealing, having both easy-to-open and sealable properties, no variation in burst strength between products, and easy product management, and a package formed by sealing the container with the lid material.SOLUTION: A container having a flange part at a periphery edge of an opening is provided. A surface sealing layer capable of being joined to a lid material is formed on an upper surface of the flange part. The container has a first joining part and a second joining part capable of being joined to the lid material and a connection part respectively on an outer end side and an inner end side in a container radial direction of the flange part and between them. The first joining part has a projecting shape projecting upward from the flange part. The connection part is connected to the first joining part and / or the second joining part, and the upper surface of the first joining part is located above the upper surface of the second joining in a container axial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a container having a flange portion, and more particularly, to a container having a flange portion provided with a joint portion to which a lid material can be attached by heat sealing so as to have both easy-openability and airtightness.

Background Art

[0002] A resin container sealed by heat-sealing a flexible lid material to a flange portion is widely used as a simple container for food and drink. In such a resin container, it is required to have both high airtightness and easy-openability that can be easily opened by heat sealing.

[0003] In order to achieve both airtightness and easy-openability in a container with a flange, it has been proposed to control the sealing strength with the lid in the flange portion. For example, in Patent Document 1 below, the flange portion has a flat portion where a seal portion is formed and an extension portion extending along the outer peripheral edge of this flat portion. The container body includes at least two layers of a seal layer and a base material layer. The seal layer has a thin portion or a missing portion on at least one of the outer peripheral side and the inner peripheral side of the flat portion, and has an easily separable means that can be easily separated on the other side. The flat portion is described as having a thickness on the side having the thin portion or the missing portion that is 20% or more and 98% or less of the thickness of the central portion thereof. In Patent Document 1 above, it is described that by forming the flange portion to be thinner toward the inner edge portion, position control of the seal portion becomes unnecessary when sealing the lid material and the container body, and it is possible to easily achieve both easy-openability and airtightness.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the container described in Patent Document 1 above, although it is tightly sealed to the lid material on the inclined surface of the flange portion so as not to be separable, when the sealing conditions become severe, a resin lump including a seal layer is formed on the inner edge portion side. When there is a large difference in the circumferential direction in the flange thickness, the sealing conditions become severe at the thick portion. As a result, when the lid is deformed into a dome shape due to an increase in internal pressure, unintended delamination starts from the inner edge side of the thin seal portion formed near the resin lump including the seal layer, resulting in a decrease in the seal strength (burst strength). Also, the burst strength varies greatly depending on the sealing temperature. As a result, there is a variation among products, and there is a risk that product management becomes complicated. In addition, when the upper surface of the flange portion is formed as an inclined surface simultaneously with the formation of the flange portion, compared with the case where the upper surface of the flange portion is formed as a flat surface, the mold processing becomes complicated, and there is a risk that the manufacturing cost of the mold increases, which is not satisfactory in terms of economy.

[0006] Therefore, an object of the present invention is to provide a container that can seal a lid material by heat sealing to the flange portion without causing the above-described problems, has both easy-openability and sealing performance, can reduce variations in burst strength even under the same sealing conditions or when the sealing conditions are different in the circumferential direction, and is easy to manage products, and a package formed by sealing a lid material to the container.

Means for Solving the Problems

[0007] According to the present invention, there is provided a container having a flange portion at the periphery of an opening, a surface seal layer capable of being joined to a lid material being formed on the upper surface of the flange portion, and a first joining portion, a second joining portion, and a connecting portion capable of being joined to the lid material being provided on the outer edge side and the inner edge side in the container diameter direction of the flange portion and between them, respectively. The first joining portion has a convex shape protruding upward from the flange portion, the connecting portion is connected to the first joining portion and / or the second joining portion, and the upper surface of the first joining portion is located above the upper surface of the second joining portion in the axial direction of the container.

[0008] In the above container of the present invention, (1) The height difference between the upper surface of the first joining portion and the upper surface of the second joining portion is 0.01 to 0.20 mm. (2) The upper surface of the flange portion has a stepped shape composed of the first joining portion, the connecting portion, and the second joining portion. (3) The connecting portion has a concave shape or a concavo-convex shape. (4) The width of the convex portion of the concavo-convex shape in the container diameter direction is smaller than the width of the first joining portion in the container diameter direction. is preferable.

[0009] According to the present invention, there is also provided a package comprising the above container and a lid material having a lid seal layer that is joined to the surface seal layer of the flange portion of the container to seal the container, wherein a resin lump including a surface seal layer protruding outward is formed at the outer peripheral end of the first joining portion of the container.

[0010] In the above package of the present invention, (1) It has a thin surface seal layer serving as an opening start portion in the downward direction in the container axial direction or the inner direction in the container diameter direction of the resin lump. (2) The opening start portion is near the interface between the surface seal layer and the container base material at the outer peripheral edge of the joining position. (3) During the opening operation, the thin surface seal layer aggregates and breaks from the opening start portion, and then the container is opened by the progress of the delamination between the base material of the container and the surface seal layer. is suitable.

Advantages of the Invention

[0011] In the container of the present invention, as a joint portion that becomes a sealing portion with the lid material, a first joint portion on the outer edge side in the radial direction of the container and a second joint portion that is located on the inner edge side in the radial direction of the container and has a lower height in the axial direction of the container than the first joint portion are formed. As a result, when heat-sealing, pressure from the sealing head is likely to be applied to the first joint portion, and it is difficult for pressure to be applied to the second joint portion. As a result, a resin pool is likely to be formed by the container surface seal layer on the outer side in the radial direction of the first joint portion, and it adheres to the resin pool by the lid material seal layer, improving the easy-openability. On the other hand, in the second joint portion, it is difficult for a resin pool to be formed by the container surface seal layer on the inner side in the radial direction of the second joint portion, that is, since the formation of the starting point of cohesive failure can be suppressed, unintentional peeling from the inside when the internal pressure rises can be effectively prevented. Also, as described above, since it is easy to control the resin pool formed by the container surface seal layer on the inner side in the radial direction of the second joint portion, it is possible to reduce the variation in strength (burst strength) that causes delamination from the inside due to an increase in internal pressure, and it is also possible to control the burst strength according to the sealing temperature. Furthermore, since the upper surface of the joint portion is flat, when heat-sealing, the pressure received by the joint portion from the sealing head can be received by the entire upper surface of the joint portion. Therefore, the influence on the base material constituting the container can be reduced, and deformation of the base material can be prevented. Also, since the processing of the mold (locator) used for the molding process of the first joint portion, the second joint portion, and the connecting portion can be performed with a tool processed into a flat shape, the processing is easy and the economic efficiency is excellent.

[0012] In the package of the present invention, a resin accumulation formed by a container surface seal layer formed radially outside of a first joint portion, which is a heat seal portion between a lid material and a container flange portion, is adhered to a resin accumulation formed by the surface seal layer of the lid material. As a result, when the lid material is lifted, the container surface seal layer including these resin accumulations is easily peeled off from the container base material layer in combination with the fact that the container surface seal layer in the vicinity of the resin accumulation is formed to be thin, so that excellent easy-openability is exhibited. On the other hand, as described above, since it is difficult to form a resin accumulation due to container surface sealing at the inner peripheral end of the second joint portion, even when the internal pressure of the container rises, it does not start to open from the inside, and the sealing performance is ensured.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Embodiments for Carrying Out the Invention

[0014] FIG. 1 shows a perspective view (A) and a layer structure (B) of a first embodiment of the container of the present invention, and FIG. 2 is a cross-sectional view showing an enlarged view of the flange portion of the container shown in FIG. 1. The container generally represented by 1 is roughly composed of a bottom portion 2, a body portion 3, a flange portion 4 extending radially outward from the upper end of the body portion 3 in the container radius direction, and an outer wall 5 hanging down from the outer peripheral edge of the flange portion 4. As is clear from FIG. 2, the container 1 is integrally formed from a laminate 6 composed of a base material layer 6a and a surface seal layer 6b such that the surface seal layer 6b becomes the upper surface at a position facing a lid material (not shown) in the flange portion 4. It is preferable that the base material layer 6a and the surface seal layer 6b are formed of resins having peelability from each other. Thereby, when the lid material is opened, the space between the base material layer 6a and the surface seal layer 6b can be easily peeled off, and the opening property is improved.

[0015] As is clear from FIG. 2, on the upper surface of the flange portion 4, an annular joint portion 41 which is a portion joined to the lid material by heat seal at the central portion, and an inner step portion 42 are formed inside the annular joint portion 41. In the specific example shown in FIG. 2, an outer step portion 43 is formed outside the annular joint portion 41. In the specific example shown in FIG. 2, the annular joint portion 41 is composed of a first joint portion 41a located on the outer side in the container diameter direction and a second joint portion 41b located on the inner side in the container diameter direction. The upper surface of the second joint portion 41b is located below the upper surface of the first joint portion 41a by a distance L1 in the container axial direction, and the width (D2) of the second joint portion 41b in the container diameter direction is formed wider than the width (D1) of the first joint portion 41a in the container diameter direction. Also, between the first joint portion 41a and the second joint portion 41b, a step (side wall portion) due to the height difference (L1) between the two is formed to constitute a connecting portion 41c.

[0016] Also, as described above, when the container is made of the laminate 6 in which the base material layer 6a and the surface seal layer 6b have peelability, the surface seal layer 6b' in the side wall portion 44 between the first joint portion 41a and the outer step portion 43 and the side wall portion 45 between the second joint portion 41b and the inner step portion 42 is formed thinner than the surface seal layer 6b of other portions. Further, a groove (notch) 46 is formed at the lower end of the side wall portion 44, and a groove (notch) 47 is formed at the lower end of the side wall portion 45 or on the outer peripheral side of the inner step portion.

[0017] FIG. 3 is a partially enlarged cross-sectional view showing the sealed state of the package in which the lid material 10 is joined to the container shown in FIG. 2. As shown in FIG. 3, the lid material 10 is heat-sealed to the annular joint portion 41 of the flange portion 4 of the container 1, and by joining, the container is in a sealed state. That is, in the inner step portion 42 formed inside the annular joint portion 41 and the outer step portion 43 formed outside the annular joint portion 41, the lid material 10 and the flange portion 4 of the container 1 are not joined. The lid material 10 is composed of a base material layer 10a and a heat-seal layer 10b made of a heat-sealable resin that can be heat-sealed to the surface seal layer 6b of the container 1, as is clear from FIG. 3. As shown in FIG. 3, when the lid material 10 is pressed and heated at the annular joint portion 41 of the container 1 by a known method using a heat-seal head or the like, the pressure from the heat-seal head (not shown) is mostly applied to the upper surface of the first joint portion 41a and is difficult to be applied to the second joint portion 41b. As a result, in the portion of the first joint portion 41a, the surface seal layer 6b of the container 1 and the heat-seal layer 10b of the lid material 10 are melted and joined more than by the second joint portion 41b. A resin pool 7 formed by the surface seal layer 6b is formed at the outer peripheral end 49 of the first joint portion 41a. Also, since heating is generally performed from the lid material side during heat-sealing, the heat-seal layer 10b of the lid material 10 melts more, and a resin pool 11a formed by the heat-seal layer of the lid material larger than the resin pool 7 formed by the container surface seal layer is formed.

[0018] On the other hand, at the second joint portion 41b, unlike the inner stepped portion 42, it is heat-sealed and joined to the lid material 10. However, since it is difficult for the pressure from the seal head to be applied, and in combination with the fact that it has a wider radial width and a flat upper surface than the first joint portion, almost no resin accumulation is formed by the container surface seal layer 6b at the second joint portion 41b. Further, since the lid material 10 is directly pressurized by the seal head, a resin accumulation 11b is formed by the lid material heat-seal layer, similar to the outer peripheral end of the first joint portion 41a. However, the resin accumulation 11b formed by the lid material heat-seal layer hardly contacts the side wall portion 45.

[0019] Upon opening, the resin accumulation 7 formed by the container surface seal layer 6b at the outer peripheral end 49 of the first joint portion 41a becomes integrated with the resin accumulation 11a formed by the lid material heat-seal layer, and the opening proceeds by being peeled off from the interface between the container surface seal layer 6b and the base material layer 6a. As described above, the surface seal layer 6b of the side wall portion 44 between the first joint portion 41a and the outer stepped portion 43 is formed to be thin, and since the resin accumulation 7 formed by the container surface seal layer 6b contacts the thin surface seal layer 6b and the resin accumulation 7 in the downward or inner direction, when the lid material is pulled up by opening, cohesive failure of the surface seal layer 6b can be easily caused from the downward or inner direction of the resin accumulation 7 formed by the container surface seal layer 6b integrated with the lid material heat-seal layer resin accumulation 11a. And since the location where this cohesive failure occurs is near the interface between the surface seal layer 6b and the base material layer 6a, subsequent delamination between the surface seal layer 6b and the base material layer 6a also easily proceeds, and the lid material can be easily removed from the container.

[0020] When the internal pressure in the container rises, due to the presence of the resin pool 11b formed by the lid material heat seal layer near the inner peripheral end 50 of the second joint, the upward movement of the lid material 10 starting from the inner peripheral end 50 of the second joint is suppressed. Also, since no resin pool is formed by the container surface seal layer 6b, the resin pool 11b formed by the lid material heat seal layer does not peel off integrally with the surface seal layer 6b, effectively preventing accidental opening due to the increase in internal pressure, and having excellent sealing performance (pressure resistance).

[0021] FIG. 4 is a partial cross-sectional view showing an enlarged flange portion of the container according to the second aspect of the present invention, and FIG. 5 is a partial enlarged cross-sectional view showing an enlarged flange portion in a state where a lid material is heat-sealed to the container shown in FIG. 4. In the aspect shown in FIGS. 4 and 5, the basic shape is the same as that of the container according to the first aspect shown in FIG. 2, except that the connecting portions 41c each have a concavo-convex shape with a flat upper surface, a concave portion 41c1 and a convex portion 41c2. In this aspect, the convex portion 41c2 in the first joint 41a and the connecting portion 41c have the same height in the container axis direction. The concave portion 41c1 in the second joint 41b and the connecting portion 41c may have different heights in the container axis direction with respect to the second joint 41b (for example, the concave portion 41c1 has a lower height in the container axis direction), but it is preferably formed L1 lower than the first joint 41a. Thereby, since the pressure from the seal head can be received by the first joint 41a and the convex portion 41c2, similar to the above-described aspect, in the first joint 41a, it is possible to form a resin pool 7 by the container surface seal layer 6b near the outer peripheral end 49 of the first joint. In the second joint 41b, since it is difficult for the pressure from the seal head to be applied, the formation of a resin pool by the container surface seal layer 6b near the inner peripheral end 50 of the second joint 41b is suppressed. Also, since the convex portion 41c2 is at the same height as the first joint 41a, it is possible to surely join with the lid material by these.

[0022] Also, as described above, when the heights of the convex portions 41c2 in the first joint portion 41a and the connecting portion 41c in the axial direction of the container are the same, the width (D3) of the convex portion 41c2 in the radial direction of the container is smaller than the width (D1) of the first joint portion 41a. Therefore, since the amount of crushing of the container surface seal layer 6b in the first joint portion 41a can be increased, it becomes possible to surely form the resin pool 7 by the container surface seal layer 6b near the outer peripheral end 49 of the first joint portion 41a, and the unsealing property is improved. On the other hand, if the width (D3) of the convex portion 41c2 is too small, the convex portion will be crushed during heat sealing, and it will be easier for the pressure from the seal head to be applied to the first joint portion 41a. Therefore, it is preferable that the width (D3) of the convex portion 41c2 is larger than the width (D2) of the second joint portion 41b and the width (D4) of the concave portion 41c1. Also in this aspect, in the second joint portion 41b, it is difficult for the pressure from the seal head to be applied, and it is difficult to form a resin pool by the container surface seal layer 6b near the inner peripheral end 50 of the second joint portion. Therefore, accidental unsealing due to an increase in internal pressure is effectively prevented. In the second joint portion 41b, a resin pool 8 is formed by the container surface seal layer 6b near the inner peripheral end 51 of the convex portion 41c2. However, since it is located on the outer peripheral side of the inner peripheral end of the joint portion between the lid material seal layer 10b and the container surface seal layer 6b, it does not affect the sealing performance during an increase in internal pressure. Rather, since such a resin pool 8 exists in a wedge shape in the lid material seal layer 10b, it becomes possible to improve the sealing property with the lid material 10 in the second joint portion 41b.

[0023] In the container of the present invention, the height difference (L1) between the first joint portion and the second joint portion is preferably in the range of 0.01 to 0.20 mm. Thereby, while ensuring the sealing property by reliable joining by the annular joint portion, a resin pool is formed by the container surface seal layer 6b near the outer peripheral end of the first joint portion, and on the other hand, even if a resin pool is formed near the inner peripheral end of the second joint portion by the container surface seal layer 6b, it can be made extremely small. As a result, the formation of the resin pool by the container surface seal layer 6b can be controlled, and it becomes possible to reduce the easy unsealing property and the variation in burst strength due to the sealing temperature. Also, it is preferable that the width (D1) in the container radial direction of the first joint portion and the width (D2) in the container radial direction of the second joint portion in the first aspect are in the range of D1:D2 = 1:2 to 5:1. Thereby, the above-described effects can be efficiently exhibited. Also, the width (D1) in the container radial direction of the first joint portion and the width (D3) in the container radial direction of the convex portion of the connecting portion in the second aspect only need to satisfy D1≧D3 as described above. Preferably, it is in the range of D1:D3 = 5:1 to 1:1. Furthermore, it is preferable that the width (D2) in the container radial direction of the second joint portion in the second aspect is in the range of 10 to 70% of the width in the container radial direction of the annular joint portion. Thereby, formation of resin accumulation by the container surface seal layer 6b at the inner peripheral end of the second joint portion can be suppressed, and variation in burst strength can be suppressed. Moreover, it is preferable that the width (D4) in the container radial direction of the concave portion of the connecting portion is in the range of 10 to 50% of the width in the container radial direction of the annular joint portion. Thereby, it becomes possible to receive the molten resin from the first joint portion and the convex portion of the connecting portion into the concave portion.

[0024] In the present invention, the thickness of the surface seal layer of the annular joint portion can be appropriately set according to the type of resin constituting the surface seal layer, the width of the annular joint portion, etc., but it is preferably in the range of 10 to 80 μm. When the thickness of the surface seal layer of the annular joint portion is within the above range, the step of the inner stepped portion is preferably in the range of 0.1 to 0.5 mm, more preferably in the range of 0.25 to 0.5 mm. Also, the step of the outer stepped portion is preferably in the range of 0.1 to 0.5 mm, more preferably in the range of 0.25 to 0.5 mm.

[0025] In the container of the present invention, by forming a stress concentration portion that protrudes outward from the container on a part of the annular joint portion when viewed from the top surface of the container, it becomes possible to open the container with a small force. That is, on the upper surface of the container flange portion in the first aspect shown in FIG. 6(A), since the shape of the annular joint portion 41 has a protruding portion 52 that protrudes in a V shape outward in the container diameter direction, after the delamination between the base material layer 6a and the surface seal layer 6b during opening, the thin surface seal layer 6b in the inner peripheral side groove (notch) 47 is likely to break due to stress concentration, which is preferable. As other protruding shapes of such an annular protruding portion, for example, a U shape, an L shape, or a wavy shape in which a plurality of these are continuous may be used. Also, in the specific example shown in FIG. 6(A), a protrusion 53 is formed outside the protruding portion 52 to enable air venting of the mold (locator) when forming the annular joint portion. Thereby, for example, it is possible to suppress air from staying in the concave portion of the locator corresponding to the first joint portion, and it becomes possible to mold an annular joint portion having a dimensional stability as per the mold shape.

[0026] Also, in the container of the present invention, a steam vent portion for releasing the internal pressure can be formed in a part of the annular joint portion when the internal pressure rises due to microwave heating or the like. That is, as shown in FIG. 6(B), a plurality of steam vent portions 54 that protrude inward from the container are formed when viewed from the top surface of the container. When the internal pressure rises due to microwave heating, stress concentrates on these inwardly protruding steam vent portions, and delamination starts preferentially in other portions, making it possible to efficiently release the internal pressure. Note that since the upper surface of the annular joint portion is flat at the location of the steam vent portion 54, in the first aspect, the second joint portion is not formed (FIG. 6(B)), and in the second aspect, the concave portions of the second joint portion and the connecting portion are not formed. By adopting such a shape, it is possible to efficiently form a resin accumulation by the lid material heat seal layer inside the container during heat sealing, and a package body provided with a steam vent portion capable of releasing the internal pressure can be obtained. Furthermore, if the variation in burst strength can be reduced in the flange portion other than the steam vent portion as described above, it becomes possible to surely release the internal pressure at the steam vent portion.

[0027] In the specific examples shown in FIGS. 6(A) and 6(B), the container has a round shape, but the container of the present invention is not limited to a round shape and may be a square container (tray-shaped container) as shown in FIGS. 7 and 8. Also in this embodiment, by forming a stress concentration portion protruding outward from the container on a part of the annular joint portion when viewed from the top surface of the container, it becomes possible to open the container with a small force. That is, FIG. 7 is a top view showing an example of the square container of the present invention. Also in the square container shown in FIG. 7, on the upper surface of the flange portion 4, the shape of the annular joint portion 41 has a protruding portion 52 protruding in a V shape outward in the container diameter direction. As a result, after the delamination between the base material layer 6a and the surface seal layer 6b at the time of opening, the thin surface seal layer 6b in the inner peripheral side groove (notch) 47 is likely to break due to stress concentration, which is preferable. Further, when the thickness of the sheet used for forming the container of the present invention is thin and the height of the annular joint portion cannot be sufficiently ensured, as shown in FIG. 7, by providing a depression 56 (at a position lower than the inner peripheral step) adjacent to the protruding portion 52, the thickness of the thin portion of the surface seal layer of the container can be made thinner, and fluffing after opening can be prevented.

[0028] Also in the case of a square container, a steam vent portion for releasing the internal pressure can be formed in a part of the annular joint portion when the internal pressure rises due to microwave heating or the like. That is, FIGS. 8(A) and (B) are partial enlarged views showing an embodiment in which the form of the corner portion 55 of the square container shown in FIG. 7 is changed. As shown in FIG. 8, a steam vent portion 54 is formed in the corner portion 55 when viewed from the upper surface of the container. When the internal pressure rises due to microwave heating, since the steam vent portion is designed to be weaker against the internal pressure than other parts, delamination starts preferentially in other parts, and it becomes possible to efficiently release the internal pressure. The steam vent portion 54 is preferably formed in at least one of the four corner portions of the square container, but may also be formed in a part other than the corner portion.

[0029] As shown in FIGS. 8(A) and (B), at the location of the steam passage portion 54, the upper surface of the annular joint portion 41 is flat. Also, in the embodiment shown in FIG. 8(A), on the upper surface of the flange portion, since the annular joint portion 41 has a protruding portion 52 that protrudes in a V shape outward in the container diameter direction, after the delamination between the base material layer 6a and the surface seal layer 6b during opening, the thin surface seal layer 6b in the inner peripheral side groove (notch) 47 is likely to break due to stress concentration. In addition, in a rectangular container, when an opening start location is provided at a corner, since the thin surface seal layer 6b has already been cut or requires a large force to break when it is extremely thin, it is not necessarily required that the annular joint portion 41 has a protruding portion that protrudes in a V shape outward in the container diameter direction as shown in FIG. 8(A), and a shape as shown in FIG. 8(B) may also be used. Also, the shape of FIG. 8(A) may be present at only one corner, or a plurality of corners may have the shape of FIG. 8(A).

[0030] The container and the package of the present invention are not limited to the specific examples shown in FIGS. 1 to 8, and various modifications are possible. For example, in the specific example shown in the figures, an outer step portion was formed outside the annular joint portion, but it does not necessarily have to be formed, and a mode in which the outer peripheral end of the flange portion and the outer peripheral end of the annular joint portion coincide may also be used. Also, it is preferable for the flange portion to have an outer wall 5 in the shape of a skirt flange that hangs down from the outer peripheral end of the flange portion in order to improve the mechanical strength of the flange portion etc., but depending on the thickness of the flange portion etc., the outer wall may not be formed. Furthermore, in the specific example shown in the figures, the container was integrally formed from a laminate including a base material layer and a surface seal layer, and the surface seal layer was also formed on the inner surface of the container, but of course, the surface seal layer may be formed only on the flange portion.

[0031] The container of the present invention is preferably cup-shaped, but is not limited thereto, and as long as it has a flange portion, it may be tray-shaped. Also, FIG. 6 shows a round container shape, FIG. 7 shows a rectangular container shape, but other polygonal containers or elliptical containers may also be used. As the lid material compatible with the container of the present invention, in addition to the flexible sheet-like lid material, a molded lid in the form of a drop lid may also be used.

[0032] Also, as described above, it is preferable that the base material layer and the surface seal layer of the container are peeled off by delamination, but as long as easy peelability can be exhibited, cohesive delamination or interfacial delamination may be used. Further, the base material layer and the heat seal layer on the lid material side may exhibit easy peelability, and it is of course good if the seal layer of the lid material undergoes cohesive delamination. As a peel strength suitable for satisfying both the sealing performance and the easy opening performance, as shown in FIG. 9, a push-pull gauge is attached to the gripping portion of the lid, and the opening force (peel strength) measured by pulling it in a direction of 45 degrees with respect to the lid is preferably in the range of 0.3 to 3.0 Kgf, and more desirably in the range of 0.5 to 2.5 Kgf. Regarding the sealing performance of the container, in the case of a formed container-packed food that has been retort sterilized, in the "Container Packaging of Pressurized Heat-Sterilized Foods in Food, Additives, etc. Standard Criteria (Ministry of Health, Labour and Welfare Notification No. 370)" based on the Food Sanitation Law, the measured (after retort) burst strength (internal pressure strength in the standard criteria) is specified to be 20 kPa {0.2 kgf / cm 2} or more. The method for measuring the burst strength (rupture strength) is as follows: After attaching a silicon rubber plate with double-sided adhesive tape near the center of the lid material, an air needle is pierced from the rubber plate portion, and air is fed in an amount of 1.0 ± 0.2 L / min. The seal portion of the lid material is visually observed, and the pressure at which leakage occurs is determined as the burst strength and expressed in kPa {kgf / cm 2}. It conforms to JIS Z 0238 (1998) "Test Methods for Heat-Sealed Flexible Packaging Bags and Semi-Rigid Containers - Test for Burst Strength of Containers".

[0033] As a combination of resins capable of exhibiting such a peel strength, two or more thermoplastic resins having heat sealability and no compatibility can be appropriately combined. The base material layer of the container can use conventionally known thermoplastic resins such as olefin resins, polyester resins, and others that have been conventionally used for molding resin containers. For example, when the base material layer is composed of a propylene-based polymer, by forming the surface seal layer from a blend of an ethylene-based polymer and a propylene-based polymer, it is possible to maintain easy peelability while ensuring airtightness, and the peel strength can be adjusted by appropriately changing the blend ratio of the blend.

[0034] Examples of the propylene-based polymer include, in addition to homopolypropylene, block copolymers and random copolymers of propylene and ethylene or other α-olefins, such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc. Examples of the ethylene-based polymer include homopolymers of ethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium / high-density polyethylene (MDPE, HDPE), etc., or copolymers of ethylene and other α-olefins such as 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc., vinyl monomers such as (meth)acrylic acid, ethyl (meth)acrylate, methyl (meth)acrylate, vinyl acetate, styrene, etc., or ionomers, etc.

[0035] In addition to combinations of the above olefin-based polymers, blends can also use combinations of thermoplastic polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and isophthalate-modified copolymers thereof, etc., with the above olefin-based polymers, as well as combinations with polycarbonate resins, polyacrylonitrile resins, etc. When using a propylene-based polymer and an ethylene-based polymer as the blend, in order for the flange member made of the blend to exhibit good peelability from the container body made of the propylene-based polymer, it is preferably suitable to use a blend obtained by blending the propylene-based polymer and the ethylene-based polymer in a weight ratio in the range of 5:5 to 9.5:0.5.

[0036] In order to suitably form a thin surface seal layer during container molding, it is preferable to appropriately adjust the temperature of the locator and the MFR of the surface seal layer so that the resin constituting the surface seal layer can exhibit fluidity in response to the pressure applied by the locator. The container may be formed by integrally molding a two-layer laminate having the above-described base material layer and surface seal layer, or may have a multi-layer structure having a gas barrier intermediate layer as an intermediate layer between the base material layers. Also, as described above, a surface seal layer may be formed only on the flange portion of the container. As long as the flange portion of the container of the present invention satisfies the above-described configuration, the manufacturing method is not limited, but preferably, it is preferable to integrally mold the laminate by thermoforming such as vacuum forming or plug assist pressure air forming. According to this method, at the time of molding, unevenness corresponding to the annular joint portion and the inner stepped portion can be easily formed on the upper surface of the flange portion by the locator (flange presser).

Example

[0037] (Experimental Example 1) A cup-shaped container with a skirt flange shape having a PP layer with a thickness of 1 mm and a two-layer sheet with an HDPE layer as the surface layer (surface seal layer), with a diameter of 84 mm and a flange width of 5 mm, was created by plug assist vacuum pressure air forming, and annular joint portions of three shapes shown in Table 1 below were formed on the flange portion. For all three types, the step between the annular joint portion (the second joint portion in FIGS. 2 and 4) and the inner stepped portion is 0.4 mm, and the step between the annular joint portion (the first joint portion in FIGS. 2 and 4) and the outer stepped portion is 0.51 mm for the tapered shape and the shape in FIG. 2, and 0.49 mm for the shape in FIG. 4. The HDPE had an MFR of 5 g / 10 min at 190°C, and the thickness of the surface layer was 20 μm. A lid material (seal layer thickness: 150 μm) with a seal layer made of LLDPE was heat-sealed to this container at the seal temperature and seal time of 2.3 seconds and a seal pressure of 100 kgf / cup shown in Table 1 below, and the burst strength was measured. The burst strength under each seal condition was measured, and the variation in burst strength was measured. The results are shown in Table 1.

[0038] The burst test was conducted in accordance with JIS Z 0238 (1998), "Test Methods for Heat Seal Flexible Packaging Bags and Semi-Rigid Containers - Test for Burst Strength of Containers". For cup-shaped containers with heat-sealed lid materials, after attaching a silicon rubber plate with double-sided adhesive tape near the center of the lid material, an air needle was inserted through the rubber plate part, and air was fed in at a rate of 1.0 ± 0.2 L / min. The internal pressure at the time of rupture was taken as the burst strength. As is clear from Table 1, when a tapered annular joint was formed, the burst strength was in the range of 21 - 40 kPa (range 19), whereas when an annular joint of the shape shown in Fig. 2 was formed, the burst strength was 32 - 48 kPa (range 16), and when an annular joint of the shape shown in Fig. 4 was formed, the burst strength was 36 - 44 kPa (range 8). All of them were 20 kPa or more required for retort containers by the Food Sanitation Law. However, the burst strength of the container with a tapered annular joint varied relatively more depending on the sealing conditions and was inferior to the other two in terms of product management.

[0039] (Experimental Example 2) For the containers obtained in Experimental Example 1, as shown in Fig. 9, a push-pull gauge was attached to the gripping part of the lid, and the opening force (peel strength) was measured by pulling it upward in a direction 45 degrees with respect to the lid. The opening force was taken as the maximum value at the start of opening. The results are shown in Table 1. As is clear from Table 1, when a tapered annular joint was formed, the opening force was in the range of 6.0 - 11.8 kgf, whereas when an annular joint of the shape shown in Fig. 2 was formed, the opening force was 6.2 - 7.6 kgf, and when an annular joint of the shape shown in Fig. 4 was formed, the opening force was 5.9 - 8.5 kgf. It can be seen that the container of the present invention is also excellent in easy-openability.

[0040] (Experimental Example 3) A two-layer sheet with a PP layer having a thickness of 1 mm and a surface layer (surface seal layer) of HDPE was used to create a cup-shaped container with the same shape as that in Experimental Example 1 by plug-assisted vacuum pressure forming, and annular joints with three types of shapes shown in Table 2 below were formed at the flange portion. For all three types, the step between the annular joint and the inner stepped portion is 0.4 mm, and the step between the annular joint and the outer stepped portion is 0.51 mm for the tapered shape and the shape in Figure 2, and 0.49 mm for the shape in Figure 4. The HDPE had an MFR of 7 g / 10 min at 190 °C, and the thickness of the surface layer was 30 μm. A lid material similar to that in Experimental Example 1 was heat-sealed to this container at the seal temperature, seal time of 2.3 seconds, and seal pressure of 100 kg / cup shown in Table 2 below, and the burst strength was measured. The burst strength under each sealing condition was measured, and the variation in the burst strength was measured. The results are shown in Table 2.

[0041] As is clear from Table 2, when a tapered annular joint was formed, the burst strength was in the range of 26 - 73 kPa (range 47), whereas when the annular joint of the shape in Figure 2 was formed, the burst strength was 36 - 49 kPa (range 13), and when the annular joint of the shape in Figure 4 was formed, the burst strength was 49 - 60 kPa (range 11). Although all of them are 20 kPa or more required for retort containers by the Food Sanitation Law, in this case as well, the one with a tapered annular joint had more variation in the burst strength depending on the sealing conditions and was inferior to the other two in terms of product management.

[0042] (Experimental Example 4) Regarding the container obtained in Experimental Example 3, as shown in Figure 9, a push-pull gauge was attached to the gripping portion of the lid, and the opening force (peel strength) was measured by pulling it upward in a direction 45 degrees with respect to the lid. The results are shown in Table 2. As is clear from Table 2, when a tapered annular joint was formed, the opening force was in the range of 9.1 - 12.5 kgf, whereas when the annular joint of the shape in Figure 2 was formed, the opening force was 8.7 - 11.9 kgf, and when the annular joint of the shape in Figure 4 was formed, the opening force was 8.9 - 9.1 kgf. It can be seen that the container of the present invention is also excellent in easy-openability.

[0043] (Experimental Example 5) Using a two-layer sheet with a PP layer having a thickness of 0.5 mm and an HDPE layer as the surface layer (surface seal layer), a square container with a flange having the shape shown in FIG. 7 with an outer dimension of 153 mm × 121 mm and a height of 32.5 mm was created by vacuum pressure forming, and an annular joint portion having the same shape as that in FIG. 4 was formed on the flange portion. At this time, the step between the annular joint portion (second joint portion) and the inner stepped portion was 0.25 mm, and the step between the annular joint portion (first joint portion) and the outer stepped portion was 0.34 mm. The HDPE had an MFR of 2.3 g / 10 min at 190° C., and the thickness of the surface layer was 20 μm. After commercially available sterile cooked rice was repacked in this container, a lid material (seal layer thickness: 50 μm) whose seal layer was made of LLDPE was heat-sealed at the seal temperature and seal time of 2.3 seconds and a seal pressure of 125 kgf / cup shown in Table 3 below, and the burst strength was measured. The burst strength under each seal condition was measured, and the variation in the burst strength was measured. The results are shown in Table 3. As is clear from Table 3, the burst strength was 35 to 48 kPa (range 13). Compared with Experimental Example 1 and Experimental Example 3, even though a sheet with half the thickness was used and the container had a non-circular shape, the variation in the burst strength was at the same level as that of the shape in FIG. 4 of Experimental Example 1 and the shape in FIG. 4 of Experimental Example 3.

[0044] (Experimental Example 6) Regarding the container obtained in Experimental Example 5, as shown in FIG. 9, a push-pull gauge was attached to the gripping portion of the lid, and by pulling it upward in a direction of 45 degrees with respect to the lid, the opening force (peel strength) when opening from the corner of the square container was measured. The results are shown in Table 3. As is clear from Table 3, the opening force was 6.8 to 10 kgf, and it can be seen that the container of the present invention is also excellent in easy-openability.

[0045] (Experimental Example 7) A two-layer sheet with a 1-mm-thick PP layer and a surface layer (surface seal layer) of HDPE was used to create a cup-shaped container with the same shape as in Experimental Example 1 by plug-assist vacuum pressure forming. An annular joint having a steam passage portion as shown in Fig. 6(B) was formed on the flange portion when viewed from the flange top surface side. At this time, the step between the annular joint (second joint) of the portion other than the steam passage portion and the inner step portion was 0.4 mm, and the step between the annular joint (first joint) and the outer step portion was 0.49 mm. The HDPE had an MFR of 13 g / 10 min at 190 °C, and the thickness of the surface layer was 30 μm. A lid material similar to that in Experimental Example 5 was heat-sealed to this container at a seal temperature of 210 °C, a seal time of 2.5 seconds, and a seal pressure of 125 kg / cup, and a burst test was similarly performed. At this time, the burst itself occurred due to the steam passage of the steam passage portion, and this pressure was defined as the steam passage pressure. Also, for the container after measuring the steam passage pressure, as shown in Fig. 9, a push-pull gauge was attached to the grip portion of the lid, and the opening force (peel strength) was measured by pulling it upward in a direction 45 degrees with respect to the lid. The results of the steam passage pressure and the opening force at this time are shown in Table 4.

[0046] (Experimental Example 8) A two-layer sheet with a 1-mm-thick PP layer and a surface layer (surface seal layer) that shows cohesive peelability by blending PP and LDPE was used to create a cup-shaped container with the same shape as in Experimental Example 1 by plug-assist vacuum pressure forming. An annular joint having the same shape as in Experimental Example 7 was formed on the flange portion. At this time, the step between the second joint of the annular joint and the inner step portion was 0.4 mm, and the step between the first joint of the annular joint and the outer step portion was 0.49 mm. Heat sealing was performed on this container under the same conditions as in Experimental Example 7, and a burst test was performed. At this time, the burst itself occurred due to the steam passage of the steam passage portion, and this pressure was defined as the steam passage pressure. Also, for the container after measuring the steam passage pressure, as shown in Fig. 9, a push-pull gauge was attached to the grip portion of the lid, and the opening force (peel strength) was measured by pulling it upward in a direction 45 degrees with respect to the lid. The results of the steam passage pressure and the opening force at this time are shown in Table 4.

[0047] (Experimental Example 9) A container similar to that in Experimental Example 7 was prepared. Heat sealing of the lid material was performed in the same manner as in Experimental Example 7 except that 20 cc of water was put into this container, and then microwave heating was carried out. As a result, it was confirmed that automatic steaming occurred from the steaming part. Also, for the container after automatic steaming, as shown in Fig. 9, a push-pull gauge was attached to the gripping part of the lid, and the opening force (peel strength) was measured by pulling it upward in a direction 45 degrees with respect to the lid. The results of the time taken for automatic steaming and the opening force at this time are shown in Table 4.

[0048] (Experimental Example 10) A container similar to that in Experimental Example 8 was prepared. Heat sealing of the lid material was performed in the same manner as in Experimental Example 8 except that 20 cc of water was put into this container, and then microwave heating was carried out. As a result, it was confirmed that automatic steaming occurred from the steaming part. Also, for the container after automatic steaming, as shown in Fig. 9, a push-pull gauge was attached to the gripping part of the lid, and the opening force (peel strength) was measured by pulling it upward in a direction 45 degrees with respect to the lid. The results of the time taken for automatic steaming and the opening force at this time are shown in Table 4.

[0049] (Experimental Example 11) A container with a flange, in which all four corners of a rectangular container shown in Fig. 7 with an outer dimension of 153 mm × 121 mm and a height of 32.5 mm are in the shape shown in Fig. 8(B), was prepared by vacuum pressure forming using a two-layer sheet with a PP layer having a thickness of 0.5 mm and an HDPE layer as the surface layer (surface seal layer), and an annular joint was formed in the flange part. The step between the annular joint (second joint) of the part other than the steaming part and the inner stepped part at this time was 0.2 mm, and the step between the annular joint (first joint) and the outer stepped part was 0.29 mm. The HDPE had an MFR of 1.1 g / 10 min at 190°C, and the thickness of the surface layer was 20 μm. After repacking commercially available sterile cooked rice into this container, a lid material similar to that in Experimental Example 5 was heat-sealed at the sealing temperature and sealing time of 2.5 seconds and a sealing pressure of 125 kg / cup shown in Table 5, and a burst test was performed. It was confirmed that steam passed through the steam-through part. The pressure at this time was defined as the steam-through pressure. Also, for the container after measuring the steam-through pressure, as shown in Fig. 9, a push-pull gauge was attached to the gripping part of the lid, and by pulling it up in a direction 45 degrees with respect to the lid, the opening force (peel strength) when opening from the corner of the rectangular container was measured. The results of the steam-through pressure and the opening force at this time are shown in Table 5.

[0050] (Experimental Example 12) A two-layer sheet consisting of a PP layer with a thickness of 0.5 mm and a layer showing cohesive peelability with the surface layer (surface sealing layer) being a blend of PP and LDPE was used to create a flanged container with an outer dimension of the container of 153 mm × 121 mm and a height of 32.5 mm, where all four corners of the rectangular container shown in Fig. 7 have the shape shown in Fig. 8(B) by vacuum pressure thermoforming, and an annular joint was formed at the flange part. At this time, the step between the annular joint and the inner stepped part was 0.2 mm, and the step between the annular joint and the outer stepped part was 0.29 mm. After repacking commercially available sterile cooked rice into this container, a lid material similar to that in Experimental Example 5 was heat-sealed at the sealing temperature and sealing time of 2.5 seconds and a sealing pressure of 150 kg / cup shown in Table 5, and a burst test was performed. It was confirmed that steam passed through the steam-through part. The pressure at this time was defined as the steam-through pressure. Also, for the container after measuring the steam-through pressure, as shown in Fig. 9, a push-pull gauge was attached to the gripping part of the lid, and by pulling it up in a direction 45 degrees with respect to the lid, the opening force (peel strength) when opening from the corner of the rectangular container was measured. The results of the steam-through pressure and the opening force at this time are shown in Table 5.

[0051] (Experimental Example 13) The container was created and the lid was heat-sealed in the same manner as in Experimental Example 11, and when microwave heating was performed, it was confirmed that automatic steaming occurred from the steaming section. Also, for the container after automatic steaming, as shown in Fig. 9, a push-pull gauge was attached to the gripping section of the lid, and by pulling this upward in a direction 45 degrees with respect to the lid, the opening force (peel strength) when opening from the corner of the rectangular container was measured. The results of the time taken for automatic steaming and the opening force at this time are shown in Table 5.

[0052] (Experimental Example 14) The container was created and the lid was heat-sealed in the same manner as in Experimental Example 12, and when microwave heating was performed, it was confirmed that automatic steaming occurred from the steaming section. Also, for the container after automatic steaming, as shown in Fig. 9, a push-pull gauge was attached to the gripping section of the lid, and by pulling this upward in a direction 45 degrees with respect to the lid, the opening force (peel strength) when opening from the corner of the rectangular container was measured. The results of the time taken for automatic steaming and the opening force at this time are shown in Table 5.

[0053] [Table 1]

[0054] [Table 2]

[0055] [Table 3]

[0056] [Table 4]

[0057] [Table 5] [Industrial Applicability]

[0058] The container of the present invention is excellent in easy-openability and also excellent in pressure resistance when the internal pressure rises in a sealed state, and can be suitably used as a container for filling and sealing contents that require heat sterilization such as retort sterilization. Further, since there is no variation in burst strength depending on the sealing conditions, it is possible to provide a container with stable quality, and product management is easy.

[0059] 1 Container, 2 Bottom, 3 Body, 4 Flange portion, 5 Outer wall, 6a Base material layer, 6b Surface seal layer, 7 Resin accumulation of container surface seal layer, 10 Lid material, 11a, 11b Resin accumulation of lid material heat seal layer, 41 Annular joint (joint position), 41a First joint, 41b Second joint, 41c Connecting portion, 42 Inner step portion, 43 Outer step portion, 46, 47 Grooves (notches), 52 Protruding portion, 53 Protrusion, 54 Steam passage portion.

Claims

1. A container having a flange around an opening, the flange having a surface seal layer formed on an upper surface thereof that can be joined to a lid, The flange portion has a first joint portion and a second joint portion, which can be joined to a lid material, and a connecting portion on an outer edge side and an inner edge side in a radial direction of the container, and between the first and second joint portions and the connecting portion, The first joint portion has a convex shape protruding upward from the flange portion, The connecting portion is connected to the first joint portion and / or the second joint portion, A container, characterized in that an upper surface of the first joint portion is located above an upper surface of the second joint portion in an axial direction of the container.

2. 2. The container according to claim 1, wherein a height difference between an upper surface of the first joint portion and an upper surface of the second joint portion is 0.01 to 0.20 mm.

3. The container according to claim 1 or 2, wherein an upper surface of the flange portion has a stepped shape consisting of a first joint portion, a connecting portion, and a second joint portion.

4. The container according to claim 1 or 2, wherein the connecting portion has a concave or convex shape.

5. The container according to claim 4 , wherein a width of the convex portion of the uneven shape in a radial direction of the container is smaller than a width of the first joint portion in the radial direction of the container.

6. A package comprising the container according to claim 1 and a lid having a lid seal layer that is joined to a surface seal layer of a flange portion of the container to seal the container, A package, in which a resin pool including an outwardly protruding surface seal layer is formed at the outer peripheral edge of the first joint of the container.

7. The package according to claim 6, further comprising a thin surface seal layer serving as an opening initiation point, below the resin pool in the container axial direction or inwardly in the container radial direction.

8. The package according to claim 7 , wherein the opening initiation point is near the interface between the surface seal layer and the container base material at the outer periphery of the joining position.

9. 9. The package according to claim 7 or 8, which is opened by the thin surface seal layer undergoing cohesive failure from the opening initiation point during an opening operation, followed by the progression of interlayer delamination between the base material of the container and the surface seal layer.

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