JP7249778B2 - Packaging container lid and packaging container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a packaging container lid and a packaging container comprising the lid and a container body.

2. Description of the Related Art In packaging containers for packaging foods and the like, in order to prevent foreign matter from entering the container, it is devised to minimize the gap between the container body and the lid and the places where ventilation is possible inside and outside the container. However, if the inside and outside of the container are ventilated, the container becomes more airtight and the air inside the container cannot be discharged when the lid is closed. As a result, the pressure inside the container increases, and a phenomenon that the lid is difficult to close may occur. In addition, if the fitting force between the container body and the lid is small, a phenomenon may occur in which even if the lid is once closed, the lid may come off due to the pressure inside the container.

2. Description of the Related Art When a food or the like stored in a highly sealed packaging container is heated in a microwave oven, it is necessary to discharge the water vapor generated from the contents to the outside of the container. In order to discharge water vapor to the outside of the container, it is necessary to perforate the container for ventilation or to form an air passage. If the water vapor generated in the container cannot be discharged smoothly, the pressure inside the container increases, and there is a risk that the cover will come off from the container body.

Several containers for microwave-heated foods have already been disclosed that have a means for discharging water vapor generated from the contents during heating in a microwave oven. Patent Literature 1 discloses a packaging container having a lid provided with ventilation holes having a diameter of 0.5 mm or less. Further, Patent Document 2 discloses a packaging container having a lid with a long exhaust hole having a width of 0.15 to 1.0 mm and a length of 1 to 12 mm.

JP 2017-81599 A JP 2017-165485 A

Packaging containers containing contents such as foodstuffs are often stacked during transportation and at stores. The container positioned on the upper side is stacked with the bottom surface of the container positioned on the upper side in contact with the upper surface of the lid of the container positioned on the lower side. In a commonly used thin synthetic resin sheet formed by molding, the top surface of the lid of the container located on the lower side bends downward due to the weight of the container located on the upper side. When provided, the deflection of the lid becomes even greater, and the stacked containers sometimes collapse.

The present invention is an invention made in view of such circumstances. That is, an object of the present invention is to provide a lid of a packaging container provided with ventilation holes, and when the packaging containers containing contents are stacked, the top surface of the lid of the packaging container located on the lower side is It is an object of the present invention to provide a lid of a packaging container with little downward deflection, and a packaging container comprising the lid and a container body.

The inventors of the present invention focused on the fact that an annular bulging portion, which is higher than the plane of the sheet, is formed on the outer peripheral portion of the ventilation hole. More specifically, by forming an annular bulging portion on the outer periphery of the ventilation hole, a portion thicker than the sheet thickness is generated in a part of the top surface portion, and the top surface portion itself can be increased without increasing the thickness of the sheet. It was found that the deformation was suppressed and the bending of the top surface portion could be improved. The present invention is based on such findings. That is, the present invention has the following configurations.

(1) A lid body of a packaging container that closes an opening of a container body, the lid fitting part fitting with a body fitting part formed in the container body, and a lid fitting part inside the lid fitting part. The top surface portion has a plurality of ventilation holes, and the top surface portion has a plurality of ventilation holes, and the outer peripheral portion of the ventilation holes bulges to at least one of the upper surface side and the lower surface side of the top surface portion. An annular bulging portion is formed, the vent hole is elliptical, the annular bulging portion is formed continuously over the entire circumference of the vent hole, and the vent hole has an elliptical shape. A packaging container characterized in that the height of the annular bulging portion located on the extension of the minor axis of the vent hole is larger than the height of the annular bulging portion located on the extension of the major axis. lid .
(2 ) The lid of the packaging container according to (1) , wherein the opening area of the ventilation holes on the upper surface side of the top surface portion is larger than the opening area of the ventilation holes on the lower surface side of the top surface portion. body.
( 3 ) The lid for a packaging container according to (1) or (2), wherein the lid is made of a transparent synthetic resin.
( 4 ) The lid for a packaging container according to ( 3 ), wherein the transparent synthetic resin is a styrene resin.
( 5 ) The lid of the packaging container according to any one of (1) to ( 4 ), which is for food heated in a microwave oven.
( 6 ) A packaging container comprising the lid of the packaging container according to any one of (1) to ( 5 ) and the container body.

The lid of the packaging container of the present invention has a ventilation hole, and when the packaging containers containing the contents are stacked, the top surface portion of the lid of the packaging container located on the lower side is less flexed downward. .

It is an exploded perspective view showing an example of a packaging container. FIG. 4 is a cross-sectional view showing a state in which packaging containers containing contents are stacked. (a) is a plan view of a lid, and (b) is an enlarged plan view of one vent hole among a plurality of vent holes formed in the top surface of the lid. 3(a) is a cross-sectional view taken along line AA of FIG. 3(b), and FIG. 3(b) is a cross-sectional view taken along line BB of FIG. 3(b).

Embodiments of the present invention are described below. However, embodiments of the present invention are not limited to the following embodiments.

FIG. 1 is an exploded perspective view showing the shape of an example of the packaging container of this embodiment. The top figure is the lid 1 and the bottom figure is the container body 2 . The packaging container comprises a bowl-shaped container body 2 having a circular opening 22 and a lid body 1 which is fitted into a body fitting portion 21 formed in the container body 2 to close the opening 22 . I have. Although FIG. 1 illustrates a bowl-shaped container body 2 and a lid body 1 having a corresponding shape, the shape of the packaging container is not particularly limited. The shape of the opening 22 is also not particularly limited and may be circular, elliptical, rectangular, triangular, pentagonal, hexagonal, or various other shapes.

The lid 1 has a lid fitting portion 11 fitted inside a body fitting portion 21 formed in the upper portion of the container body, and a top surface portion 12 located inside the lid fitting portion 11. ing. The packaging container of this embodiment is of an internal fitting type in which the lid 1 is fitted into the body fitting portion 21 of the container body 2 while covering the opening 22 of the container body 2 from above.

For molding the lid 1 and the container body 2, a known vacuum molding method, air pressure molding method, vacuum air pressure molding method, press molding method, or the like is usually used. In the vacuum forming method, air pressure forming method, or vacuum pressure forming method, a method using a hot plate as means for heating the sheet is sometimes referred to as a hot plate forming method. Moreover, the container body 2 and the lid body 1 may be molded by injection molding or blow molding without being limited to these molding methods.

Since the packaging container of the present embodiment is of the internal fitting type, the container is highly sealed. In such a packaging container, when the lid 1 is closed, the air in the container cannot be discharged, which may make it difficult to close the lid. Therefore, a plurality of ventilation holes 3 are provided in the top surface portion 12 of the lid body 1 . In this way, when the container main body 2 is closed with the lid 1, the air inside the container can be discharged. The ventilation holes 3 also have the function of discharging water vapor to the outside of the container when the food or the like stored in the container is heated with a microwave oven.

The planar shape of the ventilation hole 3 may be either circular or elliptical, but the elliptical shape is preferable because a large opening area can be obtained. In order to discharge steam, etc., it is necessary to increase the diameter, but if the diameter is too large, insects may enter. In general, whether or not insects enter is determined by the minimum length (minor diameter) of the opening. Therefore, if the planar shape of the vent hole 3 is elliptical, the minor axis SD is small, and the major axis LD is large, insects can be prevented from entering while ensuring a large opening area. Here, the major diameter LD is the maximum length of straight lines connecting two points on the outer periphery in a plan view of the ventilation hole 3 . The short diameter SD is the length of a straight line that passes through the center point of the long diameter LD and is perpendicular to the long diameter LD in the plan view of the ventilation hole 3 (see FIG. 3B). An ellipse is a shape made up of points where the sum of distances from two fixed points is constant, but the positions of the two fixed points of the ellipse and the sum of the distances are not particularly limited. In the present embodiment, the shape of the vent hole is not strictly limited to the shape defined as an ellipse, and may be a shape surrounded by a continuous curved line that bulges outward similar to an ellipse. . For example, it may have a bilaterally asymmetric oval shape.

When the vent hole 3 has a circular shape, the diameter is preferably 1.0 mm or less, more preferably 0.8 mm or less, from the viewpoint of exhaust efficiency and control of entry of foreign matter such as minute insects.

When the shape of the ventilation hole 3 is elliptical, the minor axis SD is preferably 0.30 to 0.68 mm, more preferably 0.40 to 0.55 mm. If it is less than 0.30 mm, the water vapor generated from the contents may condense and block the ventilation pores due to surface tension. Drosophila of a certain minimum size can invade. The upper limit is more preferably 0.55 mm in consideration of the certainty of preventing passage of insects. The major axis LD is preferably 1.3 to 2.0 times the minor axis SD, more preferably 1.5 to 1.8 times the minor axis SD. If the major diameter LD is less than 1.3 times the minor diameter SD, the area is not much different from that of a circular hole, and the water vapor discharge effect is small. There is

FIG. 2 is a cross-sectional view showing a state in which packaging containers containing contents are stacked. Packaging containers containing contents such as foodstuffs are transported in a stacked state and are often sold in a stacked state at stores. In this case, they are stacked in a state in which the bottom surface 23 of the main body 2 of the packaging container positioned above is in contact with the upper surface of the top surface portion 12 of the lid 1 of the packaging container positioned below. The lid 1 of the present embodiment is formed by molding a thin synthetic resin sheet and has flexibility. The top surface portion 12 bends downward due to the weight of the packaging container positioned above (see FIG. 2). Moreover, since the bending strength of the lid body 1 provided with the ventilation holes 3 is generally further reduced, the lid body 1 tends to bend downward due to the weight of the packaging container. Incidentally, the weight of the entire packaging container containing the contents is generally about 500 to 800 g.

In order to reduce the deflection of the top surface 12, the thickness of the synthetic resin sheet, which is the material of the lid 1, should be increased. descend. The inventors of the present invention have found that if an annular bulging portion 31 that bulges to at least one of the upper surface side and the lower surface side of the top surface portion 12 is formed in the outer peripheral portion of the ventilation hole 3, the top surface portion can be It has been found that the deformation of the top surface portion 12 can be improved by suppressing the deformation of the top surface portion 12 itself.

In FIG. 3B, an annular bulging portion 31 bulging toward the upper surface of the ceiling portion 12 is formed in the outer peripheral portion of the ventilation hole 3 . The annular bulging portion 31 is formed continuously over the entire circumference of the outer peripheral portion of the ventilation hole 3 . The lid body 1 of the present embodiment can increase the bending strength (rigidity) of the top surface portion 12 by forming the annular bulging portion 31 around the ventilation hole 3, and as a result, the container can be stacked. At this time, the deflection of the top surface portion 12 of the lid body 1 can be reduced.

However, when the shape of the vent hole 3 is elliptical and the height of the annular bulging portion 31 is the same, the force required for bending along the axis of the major axis is equal to the force required for bending along the axis of the minor axis. If the difference is large, when the containers with the lids 1 are stacked, there is a risk that the top surface portion 12 of the lids 1 will be greatly bent.

4 is an enlarged cross-sectional view of the vent hole 3, FIG. 4(a) is a cross-sectional view along AA in FIG. 3(b), and FIG. 4(b) is a cross-sectional view along BB in FIG. 3(b). It is a diagram. In this embodiment, the height of the annular bulging portion located on the extension of the minor axis SD of the vent hole 3 is higher than the height 31a of the annular bulging portion located on the extension of the major axis LD of the vent hole 3 . By making 31b larger, the force required to bend along the axis of minor axis SD increases. As a result, the force required for bending along the minor axis SD can be increased to a level equal to or greater than the force required for bending along the major axis LD. As a result, the deflection of the lid 1 when the packaging containers with the lid 1 are stacked can be reduced. 3(b) and 4, 32 indicates the extreme end of the long diameter LD of the vent hole 3, and 33 indicates the extreme end of the short diameter SD of the vent hole 3. In FIG.

The relationship between the force required for bending along the minor axis SD and the force required for bending along the major axis LD is defined as follows. The absolute value |SF-LF| of the difference obtained by subtracting the force LF (N/mm) required for bending along the major axis LD from the force SF (N/mm) required for bending along the minor axis SD is 5.0 N/mm or less is preferable, and 2 N/mm or less is more preferable.

Further, as shown in FIG. 4 , the opening area of the ventilation holes 3 on the upper surface side 12 a of the top panel 12 is larger than the opening area of the ventilation holes 3 on the lower surface side 12 b of the top panel 12 . By adopting such a configuration, it is possible to reduce deflection when packaging containers with lids 1 are stacked, compared to the case where the size relationship of the opening areas is reversed. In addition, when the packaging container containing the contents is heated in the microwave oven, the wide opening of the ventilation hole 3 is positioned on the upper surface side 12a of the top surface portion 12, so that the water vapor released from the ventilation hole 3 diffuses in the horizontal direction. easier to be

The method of perforating the ventilation holes 3 is preferably laser beam irradiation. The synthetic resin sheet is melted and perforated, and the melted resin aggregates around the perimeter of the hole to form the annular bulging portion 31 . Therefore, the height of the annular bulging portion 31 having the major diameter LD and the minor diameter SD can be controlled by appropriately adjusting a predetermined output and moving speed during perforation by laser beam irradiation.

Lasers include various lasers such as carbon dioxide laser, YAG laser, semiconductor laser, argon laser, etc., and carbon dioxide laser with a wavelength range of 9 to 11 μm is preferably used. In particular, it is preferable to irradiate a carbon dioxide laser with an output of 10 to 100 W. When the output range of the carbon dioxide laser is lower than 10 W, the workability is poor and the resin may not be penetrated. may not be achieved.

As for the transport speed of the laser beam, if the irradiation beam is moved to the resin surface at a transport speed of 5 to 30000 mm/s, the perforation can be performed smoothly. If the moving speed of the laser beam is lower than 5 mm/s, workability is poor and excessive irradiation may occur, which is not preferable. On the other hand, if the moving speed of the laser beam exceeds 30000 mm/s, it may not be possible to achieve the desired diameter of the hole.

The position of forming the ventilation holes in the lid 1 may be other than the horizontal surface portion of the top surface portion 12 (for example, an inclined surface portion such as a side surface, a curved surface portion, or the like).
In a packaging container containing food, a band seal may be applied to the central portion of the packaging container. In this case, in order to prevent the vent hole 3 from being blocked by the band seal, a convex portion higher than the position of the vent hole 3 is provided around the vent hole 3 so that the band seal does not directly hang on the vent hole 3. may be formed. Alternatively, a concave portion may be provided in the top surface portion 12 and the ventilation holes 3 may be provided in the bottom of the concave portion.

The materials of the lid 1 and the container body 2 of the present embodiment may be the same type or different types as long as they are synthetic resins. In the case of heating with a microwave oven, the container main body side can be made of foamed polystyrene in consideration of heat conduction. It is preferable to use a transparent synthetic resin for the lid 1 so that the contents in the packaging container can be visually confirmed. As the transparent synthetic resin, styrene-based, polypropylene-based, polyester-based, and polyethylene-based synthetic resins can be used. The lid body 1 of the present embodiment is manufactured by molding a sheet obtained by stretching the above synthetic resin. A biaxially oriented sheet is preferable to a uniaxially oriented sheet because it has a better balance of physical properties. In particular, a biaxially oriented styrene resin sheet has well-balanced properties in terms of rigidity, heat resistance, transparency, environmental friendliness, and workability, and is suitable as a material for the lid 1 . In addition, styrene-based resins are superior in terms of production efficiency because they can be perforated with a laser beam faster than other synthetic resins.

The styrene-based resin is preferably a copolymer of styrene and other vinyl-based monomers. Other vinyl-based monomers may be those having an olefinic double bond copolymerizable with styrene, acrylic acid monomers such as acrylic acid and methacrylic acid, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, Examples include (meth)acrylic acid ester monomers such as butyl acrylate and methyl methacrylate, α,β-ethylenically unsaturated carboxylic acids such as maleic anhydride and fumaric acid, and imide monomers such as phenylmaleimide and cyclohexylmaleimide. . The content of styrene monomer units is preferably 50% by mass or more.

When storing food in a packaging container using the lid 1 of the present embodiment and heating it in a microwave oven, the packaging container needs to have heat resistance. As a microwave oven, it is required to be able to withstand heating when a commercial microwave oven of 1500 W is used. In particular, in the lid 1, considering the temperature rise due to water vapor, the synthetic resin constituting the lid 1 preferably has a heat resistance of 107° C. or higher, more preferably 110° C. or higher, in Vicat softening point. , 115° C. or higher. An example of heat-resistant styrene-based resins having a Vicat softening point of 107° C. or higher includes styrene-based resins obtained by copolymerizing (meth)acrylic acid or the like.

Here, the Vicat softening point is measured according to JIS-K7206:1999. That is, after molding an injection molded product with a thickness of 3.2 mm as a test piece, it was left in a constant temperature and humidity chamber at 23 ° C. × 50% RH for 24 hours to adjust the condition. It is measured as the temperature when the indenter penetrates 1 mm into the test piece by increasing the temperature at a rate of temperature rise of /hr. In this embodiment, this operation is repeated three times, and the Vicat softening point is defined as the average value.

With the lid 1 of the packaging container and the packaging container of the present embodiment, when the packaging containers containing the contents are stacked, the lid 1 of the packaging container located on the lower side is less flexed. Also, the ventilation holes 3 can be formed in a short time by laser beam irradiation. The lid 1 and the packaging container of the present embodiment can be suitably used as a packaging container for food to be heated in a microwave oven or as a packaging container using the same.

Embodiments of the present invention will be described in more detail below, but the present invention is not limited to these examples.

<Example 1>
Heat-resistant biaxially oriented polystyrene (Denka Thermosheet High Heat-resistant BOPS (R roll) manufactured by Denka Co., Ltd.) was vacuum-formed to prepare a disk-shaped lid. The diameter of the top surface was 175 mm, and the material thickness of the lid was 0.3 mm. In the vicinity of the center of the top surface of the lid, 100 elliptical ventilation holes with a long diameter of 0.9 mm and a short diameter of 0.5 mm were drilled at intervals of 0.5 mm by irradiation with a laser beam. Here, the height of the annular bulging portion located on the extension of the major axis and the height of the annular bulging portion located on the extension of the minor axis can be adjusted by appropriately adjusting the average output of the laser beam and the moving speed of the laser beam. , 0.035 mm and 0.075 mm, respectively.
Irradiation with a laser beam was performed using a carbon dioxide gas laser Videojet 3330 manufactured by Videojet Corporation at a wavelength of 10.6 μm and a maximum average output of 30 W.

A sheet material made of heat-resistant expanded polystyrene (polypropylene film-covered article) was used for the container body. This was processed into a pot-shaped (bowl-shaped or bowl-shaped) container body having a circular cross section by vacuum forming. The container main body had an opening diameter of 160 mm, a bottom diameter of 100 mm, a depth of 70 mm, and a content capacity of the container main body (capacity for accommodating food) of about 800 mL.

<Examples 2 to 7, Comparative Example 1>
In Examples 2 to 7 and Comparative Example 1, in the same manner as in Example 1, various ventilation holes were formed by appropriately adjusting the output and moving speed of the laser beam. The lengths of the major and minor diameters of the ventilation pore and the height of the annular bulging portion positioned on the extension of the major and minor diameters were adjusted by finely adjusting the output and moving speed of the laser beam. In Comparative Example 1, vent holes were formed under the condition that the annular bulging portion was not formed. The results are shown in Table 1.

The evaluation method and criteria for each evaluation item in Table 1 are as follows.
(1) Force required for bending along the major and minor axes ) is cut out, and the sheet is fixed with a chuck of a tensile tester (Orientec Tensilon (model number: RTC-1210A)), and then compressed at 300 mm / min in the compression direction (opposite direction to tension). The force LF (N/mm) required for bending along the major axis and the force SF (N/mm) required for bending along the minor axis were obtained, and the absolute value of the difference between the two | SF-LF| was obtained.

(2) Deflection of the lid Deflection of the lid is the height of the empty packaging container stacked on top of the packaging container, as shown in FIG. The distance that the weight of 930 g descended when placed in the upper packaging container was evaluated. Evaluation criteria are as follows.
◎: Lid deflection less than 3.0 mm ○: Lid deflection 3.0 mm or more and less than 4.5 mm ×: Lid deflection 4.5 mm or more

Since Examples 1 to 7 had the annular bulging portion, the deflection of the lid body was smaller than that of Comparative Example 1, which did not have the annular bulging portion. In Examples 1 to 5, by adjusting the height of the annular bulging portion located on the extension of the major axis and the minor axis, the force required for bending along the axis of the major axis and the force required for bending along the axis of the minor axis Since the absolute value of the difference in the force required for the opening was particularly small, it was found that the deflection of the lid was even smaller.

REFERENCE SIGNS LIST 1 lid 11 lid fitting portion 12 top surface portion 2 container body 21 body fitting portion 22 opening 23 bottom surface 3 ventilation hole 31 annular bulging portion

Claims (6)

A packaging container lid that closes the opening of the container body,
a lid fitting portion that fits with a body fitting portion formed on the container body; and a top portion positioned inside the lid fitting portion,
The top surface portion has a plurality of ventilation holes,
An annular bulging portion that bulges to at least one of the upper surface side and the lower surface side of the top surface portion is formed on the outer peripheral portion of the ventilation hole,
said vent hole is elliptical,
The annular bulging portion is formed continuously over the entire circumference of the ventilation hole,
The height of the annular bulging portion located on the extension of the minor axis of the vent hole is larger than the height of the annular bulge portion located on the extension of the major axis of the vent hole. The lid body of the packaging container. 2. The lid of a packaging container according to claim 1 , wherein the opening area of said ventilation holes on the upper surface side of said top surface portion is larger than the opening area of said ventilation holes on the lower surface side of said top surface portion. 3. The lid of a packaging container according to claim 1 , wherein said lid is made of a transparent synthetic resin. 4. The lid of a packaging container according to claim 3 , wherein said transparent synthetic resin is a styrene resin. The packaging container lid according to any one of claims 1 to 4 , which is for food to be heated in a microwave oven. A packaging container comprising the lid of the packaging container according to any one of claims 1 to 5 and the container body.

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