JP2018024476A - Packaging container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a packaging container that can avoid difficulty in closing a lid body, prevent the lid body from falling off due to vapor pressure which is generated from contents even when being heated by an electronic oven and prevent intrusion of foreign matters and occurrence of cracking of the lid body.SOLUTION: A packaging container 5 is constituted of a container main body 1 having an opening part 4 at an upper side thereof and a lid body 2 made of synthetic resin which is closely fitted to the container main body 1 to block the opening part 4. The lid body 2 has a plurality of fine holes 3, and the fine holes 3 have the maximum diameter of 1.5 mm or less and the hole area of 1.8 mmor less, where the total of the hole areas of the fine holes 3 are 6 mmor more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a packaging container. More specifically, the present invention relates to a tightly fitting packaging container useful for food packaging applications.

  In a plastic packaging container that wraps food, etc., in order to prevent the contents stored in the container from leaking out of the container, a close fitting with improved adhesion between the container body and the lid Commonly used packaging containers are commonly used. A close-fitting packaging container can usually be manufactured by subjecting a heated synthetic resin sheet to vacuum forming or pressure forming.

  In a close-fitting packaging container, when the lid is closed, the air in the container cannot be discharged and the pressure in the container increases, so that a phenomenon may occur that the lid is difficult to close. Further, if the fitting force between the container body and the lid is small, there may be a phenomenon that the lid is detached due to the pressure in the container even if the lid is once closed.

  In addition, when heating contents such as food stored in a tightly fitting packaging container with a microwave oven, it is necessary to discharge water vapor generated from the contents out of the container. In order to discharge water vapor out of the container, it is necessary to perforate holes in the container or to form an air passage. If the generated water vapor cannot be discharged smoothly, the pressure in the container increases and the lid body may come off from the container body.

  Conventionally, a U-shaped slit has been provided on the top surface of the lid as a measure for avoiding difficulty in closing the lid and as means for discharging water vapor. Patent Document 1 discloses a lid of a packaging container in which a tongue piece portion is formed by cutting a top plate portion. Patent Document 2 discloses a lid for a food container for a microwave oven that has an opening / closing label for a heat-shrinkable film that is attached so as to cover the vapor vent portion of the lid and deforms when heated by a microwave oven.

JP 2007-191161 A JP 2014-91543 A

  However, the method of forming a tongue-shaped slit on the lid of the packaging container disclosed in Patent Document 1 and Patent Document 2 can discharge water vapor, but dust, insects, and the like enter from the slit. There is a problem that foreign matter is mixed by mischief at the store, or a tongue-shaped slit is broken and a section is mixed in the container.

  The present invention has been made in view of such a situation. That is, the problem of the present invention is that it is possible to avoid difficulty in closing the lid, and even if heated by a microwave oven, the lid does not come off due to the water vapor pressure generated from the contents. It is to provide a packaging container capable of preventing the occurrence of cracks.

  This inventor advanced examination about the shape of the hole formed in a cover body. In order to avoid the difficulty of closing the lid or to reduce the water vapor pressure when heated by a microwave oven, a sufficiently large hole may be formed. However, if it is a large hole, it is difficult to prevent the intrusion of foreign matter or to prevent the occurrence of cracks. Furthermore, from the viewpoint of the merchantability of the appearance, it is required to make the size of the hole as small as possible. And in order to prevent the lid from coming off due to the water vapor pressure when heated in a microwave oven, the relationship between the fitting strength and the hole size of the tightly fitting packaging container must be studied in detail. Was necessary. The present invention has been achieved as a result of such studies.

That is, the packaging container of the present invention has the following configuration.
(1) A packaging container composed of a container main body having an opening on the upper side and a synthetic resin lid that closely fits the container main body and closes the opening. The fine holes have a maximum diameter of 1.5 mm or less, a hole area of 1.8 mm ² or less, and a total of the hole areas of the fine holes is 6 mm ² or more. It is a packaging container.

(2) The packaging container according to (1), wherein an area of the opening of the container body is 300 cm ² or less.

(3) The packaging container according to (1) or (2), wherein an opening fitting force between the container body and the lid is 500 to 2000 cN.

(4) The packaging container according to any one of (1) to (3), wherein the container body and the lid body are fitted by an internal fitting method.

(5) The packaging container according to any one of (1) to (4), wherein the fine hole is formed in one or both of the inclined surface portion and the curved surface portion of the lid.

(6) The packaging container according to any one of (1) to (5), wherein the lid is made of a transparent synthetic resin.

(7) The packaging container according to any one of (1) to (6), wherein the lid is made of a synthetic resin having a Vicat softening point of 107 ° C or higher.

(8) The packaging container according to any one of (1) to (7), wherein food is stored and heated in a microwave oven.

  The packaging container of the present invention can avoid the difficulty of closing the lid, and even when heated by a microwave oven, the lid does not come off due to the water vapor pressure generated from the contents. It is possible to prevent the occurrence of cracks.

It is a perspective view which shows the shape of an example of a packaging container. The upper figure is the lid, and the lower figure is the container body. It is sectional drawing which shows the shape of an example of a packaging container. The upper figure is a sectional view of the lid, and the lower figure is a sectional view of the container body. Specific examples (a) to (d) of the positions of the fine holes formed in the lid are shown. It is sectional drawing of the container main body (i) and (ii) in an Example. It is sectional drawing of the container main body (iii) and (iv) in an Example. It is a perspective view which shows the shape of an example of a packaging container. (A) is a cover body, (b) is an enlarged view of the micropore of the said cover body.

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

  The packaging container of this embodiment is a packaging container comprised from the container main body which has an opening part upwards, and the synthetic resin lid body which close-fits the said container main body and plugs up the said opening part. The fitting method is a method in which the container main body and the lid constituting the packaging container are fitted and joined to each other. Among the fitting methods, a fitting method in which the adhesion of the fitting portion between the container main body and the lid is improved so as to reduce air leakage is referred to as a close fitting method. The packaging container of the present embodiment is a close-fitting packaging container, and has the performance that the lid body does not come off due to the water vapor pressure generated from the contents even when heated by a microwave oven.

  The close fitting method may be any of inner fitting, outer fitting, and inner / outer fitting. The inner fitting method is a fitting method in which the outer peripheral fitting surface of the lid is in surface contact with the inner peripheral fitting surface of the opening of the container body. The outer fitting method is a fitting method in which the inner peripheral fitting surface of the lid is in surface contact with the outer peripheral fitting surface of the opening of the container body. The inner / outer fitting method means that the annular ridge or annular groove formed in the container body and the annular groove or annular ridge formed in the lid body are fitted to the inner fitting surface and the outer fitting of the annular ridge. This is a fitting method that makes contact on both sides of the surface. Among each of the inner fitting, outer fitting, and inner / outer fitting methods, the inner fitting method allows the outer peripheral edge of the lid to be accommodated inside the outer peripheral edge of the container body, and the lid is inadvertently removed. Since there is little possibility, it is more preferable.

  FIG. 1 is a perspective view showing an example of the shape of the packaging container 5. The upper view of FIG. 1 is a perspective view of the lid body 2 and has a plurality of fine holes 3. The lower view of FIG. 1 is a perspective view of the container body 1 and has an opening 4 on the upper side. FIG. 2 is a cross-sectional view showing an example of the shape of the packaging container. 2 is a cross-sectional view of the lid 2, and is a cross-sectional view at the position AA in the upper view of FIG. 2 is a cross-sectional view of the container body 1, and is a cross-sectional view taken along the line BB of the lower view of FIG. 1, in which the position of the opening 4 of the container body 1 is shown.

  For forming the fitting shape of the container body 1 and the lid 2, a known vacuum forming method, pressure forming method, vacuum / pressure forming method, press forming method, or the like is usually used. In the vacuum forming method, the pressure forming method, or the vacuum pressure forming method, a method using a hot plate as a sheet heating means may be referred to as a hot plate forming method.

  The packaging container 5 shown in FIG. 1 and FIG. 2 includes a bowl-shaped inner fitting type container body 1 having a circular opening 4 formed by vacuum forming a foamed synthetic resin sheet, and a synthetic resin sheet. And a lid 2 that fits closely into the opening 4 of the container body 1 formed by hot plate molding.

  In the packaging container 5 of this embodiment, the lid body 2 has 5 × 5 = 25 fine holes 3. Since the air inside the packaging container 5 can be discharged to the outside through the micro holes 3, the difficulty of closing the lid 2 can be avoided, and the lid is generated by the water vapor pressure generated when heated in a microwave oven. 2 can be prevented from coming off. In addition, since the lid body 2 has a plurality of micro holes 3, the size per one micro hole 3 can be reduced, the appearance appearance can be improved, and the lid body 2 can be cracked. Occurrence can be prevented.

  The fine hole 3 has a maximum diameter of 1.5 mm or less. If the maximum diameter of the fine holes 3 exceeds 1.5 mm, dust or insects may enter. The maximum diameter of the fine holes 3 is preferably 0.3 mm or more and 1.0 mm or less. When the maximum diameter is smaller than 0.3 mm, there is a concern that it is difficult to smoothly discharge water vapor out of the container. Here, the maximum diameter means the longest length among the linear distances connecting the inner peripheries of the fine holes 3.

The fine hole 3 has a hole area of 1.8 mm ² or less. If the hole area of the fine hole 3 exceeds 1.8 mm ² , dust or insects may enter. The hole area of the fine holes 3 is preferably 0.05 mm ² or more and 0.8 mm ² or less. When the hole area of the fine hole 3 is less than 0.05 mm ² , there is a concern that it is difficult to smoothly discharge water vapor out of the container. The hole area of the fine hole 3 is obtained as the area of the surface formed on the inner periphery of the fine hole 3. Usually, a magnified photograph is taken with an optical microscope, and is calculated from the dimensions of the micropores 3.

The total hole area of the fine holes 3 is 6 mm ² or more. By setting the total hole area of the fine holes 3 to 6 mm ² or more, it is possible to reduce the lid 2 from being removed by the water vapor pressure generated from the contents even when a 1500 W microwave oven is used. The total hole area of the fine holes 3 is preferably 30 mm ² or less. If the total hole area of the fine holes 3 exceeds 30 mm ² , it is necessary to form a large number of fine holes 3 in order to ensure the hole area of the fine holes 3, which is not preferable from the viewpoint of productivity, and also in terms of appearance. It is not preferable.

  As the total area of the fine holes 3 formed in the lid 2 is larger, more water vapor generated inside the packaging container 5 can be discharged, and an increase in pressure inside the packaging container 5 can be suppressed. On the other hand, if the amount of water vapor generated in the packaging container 5 exceeds the amount of water vapor discharged from the fine holes 3 to the outside of the packaging container 5, the pressure in the packaging container 5 increases and the lid 2 may be removed. Comes out. When the opening pressing force exceeds the opening fitting force between the container body 1 and the lid body 2, the lid body 2 is detached from the container body 1.

  In the present embodiment, the opening fitting force between the container body 1 and the lid body 2 is preferably 500 to 2000 cN, and more preferably 1000 to 1500 cN. If the opening fitting force is less than 500 cN, the lid body 2 is easily detached, and if it exceeds 2000 cN, it is difficult to remove the lid body 2, and there is a practical concern. The open lid fitting force can be obtained as the maximum force (cN) when the container body 1 and the lid body 2 are pulled in the opposite directions and both come off. A tensile tester is usually used to measure the lid opening fitting force.

  The method for drilling the fine holes 3 is not particularly limited. For example, there are a method of drilling using a trimming machine (trimming method) and a method of drilling by irradiating various lasers such as carbon dioxide laser, YAG laser, semiconductor laser, argon laser (laser method). However, in the trimming method, there is a problem that if a thin cutting blade jig is used, the cutting blade jig is easily broken. Further, in the trimming method, there is a tendency that the scraps generated during the drilling are easily mixed in the container or cracks are easily generated from the fracture surface. For this reason, the laser method is preferable to the trimming method as a method for drilling the fine holes 3, and it is particularly preferable to use a carbon dioxide gas laser having a wavelength region of 9 to 11 μm.

  The shape of the fine hole 3 is not particularly limited. However, it is usually preferable to use a circular shape because of ease of processing regardless of whether it is a trimming method or a laser method.

  In the case of the laser method, irradiation with a carbon dioxide laser light source having an output of 10 to 100 W is preferable. When the output range of the carbon dioxide laser is lower than 10 W, the workability is poor, and the resin may not be able to penetrate. There are things that cannot be achieved.

  Moreover, about the transfer speed of a laser, if it is performed by operating an irradiation light beam with the transfer speed of 5-30000 mm / s on the resin surface, a perforation can be formed smoothly. When 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, when the moving speed of the laser beam exceeds 30000 mm / s, there may be a case where drilling with a desired diameter cannot be achieved.

  In the present embodiment, the position where the microhole 3 is formed is not particularly limited, and the microhole 3 can be formed at any position of the packaging container 5. When the plurality of fine holes 3 are formed in the lid body 2, the fine holes 3 may be formed all at a specific location of the lid body 2, or may be divided into a plurality of groups and formed at a plurality of locations. Good. Further, the pattern of arranging the plurality of fine holes 3 is not particularly limited. FIG. 3 shows specific examples (a) to (d) of the positions of the fine holes 3 formed in the lid 2.

  When the fine hole 3 is formed in the lid body 2, the position where the fine hole 3 is formed may be a horizontal surface portion of the top surface of the lid body 2, an inclined surface portion such as a side surface of the lid body 2, or a curved surface portion. Good. When the fine hole 3 is formed in one or both of the inclined surface portion and the curved surface portion of the lid body 2, the appearance can be improved, and the fine hole 3 is blocked when the packaging container 5 is banded. This is preferable because it is difficult and dust is less likely to enter.

  In the packaging container 5 containing food, the central part of the packaging container 5 may be wrapped around the entire body from the container main body 1 to the lid body 2. In this case, in order to prevent the fine holes 3 from being blocked by the banding, a convex portion which is higher than the other top surface is provided on the top surface of the lid body 2 so that the fine holes are not formed on the top surface where the banding is not applied. 3 may be formed. Moreover, when providing the fine hole 3 under the band seal, in order to prevent the fine hole 3 from being directly plugged by the band seal, a concave portion lower than the other top surface is provided at that position, and the fine hole 3 is provided in the concave portion. May be formed.

As for the packaging container 5 of this embodiment, it is preferable that the area of the opening part 4 of the container main body 1 is 300 cm < ² > or less. When the area of the opening 4 is larger than 300 cm ^{2, the} opening force that pushes up the lid 2 in the container by the water vapor pressure generated from the contents when heated in the microwave oven causes the fitting between the container body 1 and the lid 2. There is a risk that the resultant will exceed the resultant force and the lid body 2 may come off. More preferably, the area of the opening 4 is not less than 100 cm ^{2 and not} more than 300 cm ² . If the area of the opening 4 is smaller than 100 cm ² , the inner volume of the packaging container 5 is too small and lacks practicality. Here, the area of the opening 4 of the container body 1 is surrounded by the lowermost line of the belt portion where the fitting surface of the opening 4 of the container body 1 and the fitting surface of the lid 2 are in surface contact. It refers to the area.

Even if the area of the opening 4 is larger than 300 cm ^2, if the fitting force between the container body 1 and the lid 2 is increased, the lid 2 will not come off even if the lid opening force due to the water vapor pressure increases. Can be. However, if the fitting force is too large, a large force is required to open and close the lid 2, and there is a practical concern.

  The material of the lid body 2 of the present embodiment is not particularly limited as long as it is a synthetic resin. However, since the contents in the packaging container 5 can be visually confirmed, it is preferable to use a transparent synthetic resin. As the transparent synthetic resin, styrene-based, polypropylene-based, polyester-based, and polyethylene-based synthetic resins are often used. In particular, the stretched styrene-based synthetic resin has a balanced performance in rigidity, heat resistance, transparency, environmental properties, and processability, and is suitable as a material for the lid 2. The transparency of the synthetic resin can be evaluated by Haze, preferably 5% or less, and more preferably 3% or less. Haze is measured according to JIS-K7361. As the Haze Meter, NDH5000 (manufactured by Nippon Denshoku Industries Co., Ltd.) was used.

  The material of the container body 1 of the present embodiment is not particularly limited. Various materials such as synthetic resins, papers, metals, ceramics, and composite materials thereof can be used. However, it is preferable to use a synthetic resin because it can form a shape that can be closely fitted to the lid 2, is lightweight, and is excellent in mass productivity. Furthermore, it is more preferable to use a foamed synthetic resin because heat insulation can be imparted to the container body 1.

  The packaging container 5 of this embodiment needs to have heat resistance when food is stored and used for heating a microwave oven. As a microwave oven, it is necessary to be able to withstand heating when using a commercial 1500 W microwave oven. In particular, in the lid 2, considering the temperature rise due to water vapor, the synthetic resin constituting the lid 2 preferably has a heat resistance of 107 ° C. or higher at the Vicat softening point, and more preferably 110 ° C. or higher. More preferably, the temperature is 115 ° C. or higher. As an example of a styrene resin having a Vicat softening point of 107 ° C. or higher, there is a styrene resin 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 having a thickness of 3.2 mm as a test piece, it was left in a constant temperature and humidity chamber of 23 ° C. × 50% RH for 24 hours to adjust the condition, and using a 5 kgf weight, The temperature is increased at a rate of temperature increase of hr, and the temperature is measured when the indenter enters 1 mm into the test piece. In the present embodiment, this operation is repeated three times, and the Vicat softening point is defined as the average value.

  Although the shape of the packaging container 5 of this embodiment illustrated the bag-shaped container main body 1 and the cover body 2 of the shape corresponding to it in FIG. 1, it is not specifically limited. The shape of the opening 4 can also be various shapes such as a circle, an ellipse, a rectangle, a triangle, a pentagon, and a hexagon, and is not particularly limited.

As described above, in the packaging container 5 of the present embodiment, since the lid body 2 has a plurality of fine holes 3, the air in the packaging container 5 is discharged when the lid body 2 is closed, and the packaging container 5 The phenomenon that it is difficult to close the lid body 2 due to the pressure increase in 5 can be avoided. In addition, since the maximum diameter of the fine hole 3 is 1.5 mm or less and the hole area is 1.8 mm ² or less, it is possible to prevent entry of foreign matters such as dust and insects, and cracks in the lid 2 can be prevented. Occurrence can also be prevented.

In addition, when the food stored in the packaging container 5 is heated by a microwave oven, the total pore area of the micropores 3 is 6 mm ² or more, so that water vapor generated from the contents is removed from the container through the micropores 3. It can discharge | emit and it can prevent that the cover body 2 remove | deviates by the pressure rise in a container. In particular, if an inner fitting type tight fitting packaging container is used, the outer peripheral edge of the lid body 2 fits inside the outer peripheral edge of the container body 1, so that the possibility that the lid body 2 is inadvertently removed is reduced.

  Moreover, since the fine hole 3 has a small maximum diameter and a small hole area, the fine hole 3 is excellent in appearance, and the stored contents in the packaging container 5 are easily visible. Further, by providing the fine holes 3 in the inclined surface portion or curved surface portion other than the horizontal surface portion of the top surface of the lid body 2, foreign matter is less likely to enter, and the horizontal top surface portion does not have the fine holes 3, so that the packaging container It becomes easier to visually recognize the stored items in 5.

  Hereinafter, embodiments of the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

The sample preparation conditions used in Experiment I are as follows.
(Container body)
Two types of container main bodies (i) and (ii) having the shapes described in FIG. 1 and having the following dimensions were produced. Since both are for heat resistance and pressure resistance test, they were modeled using bakelite.
(I) Container body with an opening diameter of 125 mm and an opening area of 123 cm ² (ii) Container body with an opening diameter of 175 mm and an opening area of 240 cm ² FIG. 4 shows the container body (i) and (ii) It is sectional drawing. 4A is a cross-sectional view of the container body (i), and FIG. 4B is a cross-sectional view of the container body (ii).

(Lid)
By hot plate molding a heat-resistant biaxially stretched polystyrene sheet (Denka Co., Ltd., Denka Thermo sheet high heat resistance BOPS (R anti) (Haze 1.2%, Vicat softening point 122 ° C.)) having a thickness of 0.25 mm. Two types of lids having the shapes described in 1 and having different diameters were produced. These are two types of lids having a shape that fits closely into the two types of container bodies (i) and (ii). Various fine holes described in Tables 1 and 2 were formed on the top surface of the lid. The micropores were drilled using a carbon dioxide laser, and the micropores were all circular. As the carbon dioxide laser, Videojet 3340 manufactured by Videojet Co. was used. The laser irradiation conditions were a wavelength of 10.6 μm and a maximum average output of 45 W. Desired drilling was achieved by appropriately adjusting the average power of the laser and the moving speed of the laser beam.

  100 cc of water was put into the container main body, the lid body was closed, and it was heated in a 1500 W microwave oven for 2 minutes to check whether the lid body was detached from the container main body. When the lid was removed, it was indicated as x, and when the lid was not removed, it was indicated as ◯. The lid opening fitting force between the container body and the lid before heating was measured. Furthermore, after the lid body was removed after heating, the lid body was again fitted to the container main body, and then the opening fitting force between the heated container main body and the lid body was measured. A round tension gauge manufactured by Oba Keiki Seisakusho Co., Ltd. was used for the measurement of the lid opening fitting force. The lid opening fitting force is measured in units of 50 cN. The results are shown in Tables 1 and 2 (Experiment Nos. 1 to 26).

Table 1 shows the presence or absence of lid removal during microwave heating when the maximum diameter and the hole area of the fine holes are changed when the number of fine holes is constant at 16. Experiment No. 1-6 is a case where the area of an opening part is 123 cm < ² >. 7-12 is a case where the area of an opening part is 240 cm < ² >. Experiment No. 3-6, Experiment No. In Nos. 9-12, the lid did not come off when heated in the microwave oven. In 1, 2, 7, and 8, the lids were removed when heated in the microwave. That is, regardless of the area of the opening, when the total hole area of the fine holes is 6 mm ² or more, the lid did not come off, but when the total hole area of the fine holes was less than 6 mm ² The lid was removed.

Experiment No. 2 in Table 2 Nos. 13 to 20 were examined for the presence or absence of lid removal during microwave heating when the maximum diameter of the micro holes was fixed at 1.5 mm and the hole area was fixed at 1.77 mm ² and the number of micro holes was changed. is there. Experiment No. 13-16 is a case where the area of an opening part is 123 cm < ² >. 17-20 is a case where the area of an opening part is 240 cm < ² >. Experiment No. In Nos. 14-16 and 18-20, the lid did not come off when heated in a microwave oven. In 13 and 17, the lid body was removed when heated in the microwave. That is, regardless of the area of the opening, when the total hole area of the fine holes is 6 mm ² or more, the lid did not come off, but when the total hole area of the fine holes was less than 6 mm ² The lid was removed.

Experiment No. 2 in Table 2 Nos. 21 to 26 were examined for the presence or absence of lid removal during microwave heating when the maximum diameter of the fine holes was constant at 0.4 mm and the hole area was fixed at 0.13 mm ² and the number of fine holes was changed. is there. Experiment No. 21-23 is a case where the area of an opening part is 123 cm < ² >. 24 to 26 are cases where the area of the opening is 240 cm ² . Experiment No. In Nos. 22, 23, 25 and 26, the lid did not come off when heated in a microwave oven. In Nos. 21 and 24, the lid body was removed when heated in a microwave oven. That is, Experiment No. Compared to 13-20, even when the maximum diameter of the fine holes is about 1/4 and the hole area per fine hole is about 14 times, the total hole area of the fine holes is 6 mm. When it was ² or more, the lid did not come off, but when the total pore area was less than 6 mm ² , the lid was removed.

  As can be seen from Tables 1 and 2, the opening fitting force between the container body and the lid was 850 to 900 cN before heating in the microwave, but after heating for 2 minutes in the microwave, The opening fitting force with the lid body was reduced to 500 to 600 cN. The reason why the lid opening fitting force is reduced after heating is considered to be that the dimensions of the lid body contracted by heating. When the dimensions of the lid body before and after heating were measured, the diameter of the lid body was contracted by 0.1 to 0.2% after heating. Experiment No. The lid fitting force after heating of 1, 2, 7, 8, 13, 17, 21, and 24 is 800 to 850 cN, and the lid fitting force before heating is a value equivalent to the lid fitting force before heating. This is because the lid has been removed before the size of the container shrinks.

  In addition to the above-described experiment of heating for 2 minutes in a microwave oven, an experiment of heating for 6 minutes in a microwave oven using an equivalent packaging container was also performed. As a result, Experiment No. As for the packaging containers of 3, 9, 14, 18, 22, and 25, the lid body was removed from the container main body during the period from the start of heating to 6 minutes exceeding 2 minutes. In addition, Experiment No. As for the packaging containers of 4-6, 10-12, 15, 16, 19, 20, 23, 26, the lid body did not come off from the container body even after heating for 6 minutes. The reason why the lid did not come off from the container body even after heating for 6 minutes is thought to be that the packaging container in this experiment is a packaging container by the close fitting method.

The sample preparation conditions used in Experiment II are as follows.
(Container body)
Two types of container main bodies (iii) and (iv) having the shapes described in FIG. 1 and having the following dimensions were produced. All were produced with a styrene resin foam sheet.
(Iii) A container body having an opening diameter of 155 mm and an opening area of 190 cm ² (iv) A container body having an opening diameter of 170 mm and an opening area of 227 cm ² FIG. 5 shows the container body (iii) and (iv) It is sectional drawing. Fig.5 (a) is sectional drawing of a container main body (iii), FIG.5 (b) is sectional drawing of a container main body (iv).

(Lid)
By hot plate molding a heat-resistant biaxially stretched polystyrene sheet (Denka Co., Ltd., Denka Thermo sheet high heat resistance BOPS (R anti) (Haze 1.2%, Vicat softening point 122 ° C.)) having a thickness of 0.25 mm. Two types of lids having the shapes described in 1 and having different diameters were produced. These are two types of lids having a shape that fits closely into the two types of container bodies (iii) and (iv). Various fine holes described in Table 3 and Table 4 were formed on the top surface of the lid. The micropores were drilled using a carbon dioxide laser, and the micropores were all circular. As the carbon dioxide laser, Videojet 3340 manufactured by Videojet Co. was used. The laser irradiation conditions were a wavelength of 10.6 μm and a maximum average output of 45 W. Desired drilling was achieved by appropriately adjusting the average power of the laser and the moving speed of the laser beam.

  400 cc of water was put into the container body, the lid was closed, and it was heated in a 1500 W microwave oven for 2 minutes to check whether the lid was removed from the container body. When the lid was removed, it was indicated as x, and when the lid was not removed, it was indicated as ◯. The lid opening fitting force between the container body and the lid before heating was measured. The results are shown in Tables 3 and 4 (Experiment Nos. 27 to 52).

Table 3 shows the presence or absence of lid removal during microwave heating when the maximum diameter and area of the micropores are changed when the number of micropores is constant at 16. Experiment No. 27 to 32 are cases where the area of the opening is 190 cm ² . 33-38 is a case where the area of an opening part is 227 cm < ² >. Experiment No. 29-32, Experiment No. In 35 to 38, the lid did not come off when heated in a microwave oven. In 27, 28, 33, and 34, the lids were removed when heated in a microwave oven. That is, regardless of the area of the opening, when the total hole area of the fine holes is 6 mm ² or more, the lid did not come off, but when the total hole area of the fine holes was less than 6 mm ² The lid was removed.

Experiment No. 4 in Table 4 39-46 is the maximum diameter of the fine pores was 1.5 mm, the open area between 1.77 mm ² and the constant, which was examined whether the lid off during microwave heating in the case of changing the number of micropores is there. Experiment No. 39 to 42 are cases in which the area of the opening is 190 cm ² . 43 to 46 are cases where the area of the opening is 227 cm ² . Experiment No. In Nos. 40 to 42 and 44 to 46, the lid did not come off when heated in a microwave oven. In 39 and 43, the lid body was removed when heated in the microwave. That is, regardless of the area of the opening, when the total hole area of the fine holes is 6 mm ² or more, the lid did not come off, but when the total hole area of the fine holes was less than 6 mm ² The lid was removed.

Experiment No. 4 in Table 4 47-52 is the maximum diameter of the fine pores was 0.4 mm, the open area between 0.13 mm ² and the constant, which was examined whether the lid off during microwave heating in the case of changing the number of micropores is there. Experiment No. 47 to 49 are cases where the area of the opening is 190 cm ² . 50 to 52 are cases where the area of the opening is 227 cm ² . Experiment No. In Nos. 48, 49, 51, and 52, the lid did not come off when heated in a microwave oven. In 47 and 50, the lid body was removed when heated in a microwave oven. That is, Experiment No. Compared to 39-46, even when the maximum diameter of the fine holes is about 1/4 and the hole area per fine hole is about 14 times, the total hole area of the fine holes is 6 mm. When it was ² or more, the lid did not come off, but when the total pore area was less than 6 mm ² , the lid was removed.

  In addition to the above-described experiment of heating for 2 minutes in a microwave oven, an experiment of heating for 6 minutes in a microwave oven using an equivalent packaging container was also performed. As a result, Experiment No. The lids of the 29, 35, 40, 44, 48, and 51 packaging containers were removed from the container body during the period from the start of heating to the 6 minutes exceeding 2 minutes. In addition, Experiment No. The packaging containers 30 to 32, 36 to 38, 41, 42, 45, 46, 49, and 52 did not come off the container body after heating for 6 minutes. The reason why the lid did not come off from the container body even after heating for 6 minutes is thought to be that the packaging container in this experiment is a packaging container by the close fitting method.

The sample preparation conditions used in Experiment III are as follows.
(Container body)
The same container body (iii) and (iv) used in Experiment II were used.

(Lid)
Two types of lids having the same diameter as the lids used in Experiment II were used except that the shape and position of the micropores 3 were as described in FIG. Various fine holes listed in Table 5 were formed on the top surface of the lid. The micropores were drilled using a carbon dioxide laser. The same carbon dioxide laser as in Experiment II was used. All the micropores were elongated holes having the maximum diameter and the minimum diameter shown in FIG.

  Here, the maximum diameter refers to the longest length (hole length) among the linear distances connecting the inner peripheries of the micropores 3, and the minimum diameter refers to the linear distance connecting the inner peripheries of the micropores 3. The shortest length (hole width) among them. The maximum diameter and the minimum diameter are measured using an image measuring device (manufactured by Mitutoyo Corporation, QS250Z). In the measurement method, an image of a hole enlarged on a display is automatically measured by designating the position of the maximum diameter and the position of the width (minimum diameter). Each experiment No. Five samples were prepared every time, and all the holes (10 and 15) drilled in each sample were measured, and the average value thereof was obtained.

  The evaluation method for the lid fitting force and the presence / absence of detachment of the lid is the same as in Experiment II. The results are shown in Table 5 (Experiment Nos. 53 to 58).

Table 5 shows the presence or absence of lid removal during microwave heating when the maximum diameter, the minimum diameter, and the number of holes are changed when the shape of the micro holes is an elongated hole. Experiment No. 53 to 55 are cases where the area of the opening is 190 cm ² . 56 to 58 are cases where the area of the opening is 227 cm ² .

Experiment No. 54 and Experiment No. In No. 57, the total hole area was 6 mm ² or more, and the lid opening fitting force was also appropriate, and the lid did not come off when heated in a microwave oven. However, experiment no. 53 and Experiment No. In 56, since the total hole area was small, the lid body was removed when heated in a microwave oven. On the other hand, Experiment No. 55 and Experiment No. 58, the total pore area was 6 mm ² or more, and the lid did not come off when heated in a microwave oven, but because the maximum diameter was 2 mm, foreign matter such as dust and insects could enter. It was what had.

DESCRIPTION OF SYMBOLS 1 Container main body 2 Cover body 3 Fine hole 4 Opening part 5 Packaging container

Claims (8)

A packaging container composed of a container body having an opening on the upper side, and a synthetic resin lid that close-fits the container body and closes the opening,
The lid has a plurality of micro holes,
The fine holes have a maximum diameter of 1.5 mm or less and a hole area of 1.8 mm ² or less.
The packaging container, wherein the total pore area of the micropores is 6 mm ² or more. The packaging container according to claim 1, wherein an area of the opening of the container body is 300 cm ² or less.   The packaging container according to claim 1 or 2, wherein an opening fitting force between the container body and the lid is 500 to 2000 cN.   The packaging container according to any one of claims 1 to 3, wherein the container body and the lid body are fitted by an internal fitting method.   The packaging container according to any one of claims 1 to 4, wherein the fine hole is formed in one or both of an inclined surface portion and a curved surface portion of the lid.   The packaging container according to claim 1, wherein the lid is made of a transparent synthetic resin.   The packaging container according to any one of claims 1 to 6, wherein the lid is made of a synthetic resin having a Vicat softening point of 107 ° C or higher.   The packaging container according to any one of claims 1 to 7, wherein the packaging container is used by storing food and heating in a microwave oven.

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