JP7561490B2 - Storage containers and storage container groups - Google Patents

Description

The present invention relates to a storage container and a group of storage containers formed by stacking multiple storage containers, and in particular to a storage container made of a sheet-like material and a group of storage containers formed by stacking multiple storage containers.

Conventionally, containers made of a sheet-like member in which a PBT resin film is laminated onto paper, having a bottom and a peripheral wall, and an open top, have been widely used, for example, for storing food. Some such storage containers are open at the top and have a bottom and a peripheral wall that rises from the periphery of the bottom and is formed in pleats, and are used, for example, for storing small portions of side dishes and other foods in lunch boxes.

To improve manufacturing efficiency, a technique is known in which a number of storage containers are integrally formed by hot press molding a number of stacked sheet-like molded bodies, as in Patent Document 1, for example. A number of storage containers (a group of storage containers) manufactured by this type of integral forming technique are stored in a plastic molded container and supplied to the market.

When using, the user takes out the required number of units from the group of storage containers housed in plastic molded containers.

JP 2000-93296 A

Figure 5 is a schematic diagram showing blocking in a conventional storage container group. However, referring to this figure, it has been known that when a storage container group is formed, a phenomenon occurs in which adjacent upper and lower storage containers stick to each other (hereinafter referred to as "blocking"). As shown in the figure, a blocking occurrence area 150 occurs between a first storage container 111 and an adjacent second storage container 112, and the first storage container 111 and the second storage container 112 may stick to each other. Furthermore, when this blocking occurs, the user may be unable to remove the storage container smoothly, or when removing the storage container, a part of one of the upper or lower storage containers may peel off and remain on the other storage container.

The present invention has been made to solve the above problems, and aims to provide a storage container and a group of storage containers in which blocking is suppressed.

Through the inventors' diligent research, it was discovered that the occurrence of blocking correlates with the crystallinity of the PBT resin.

In order to achieve the above object, the invention described in claim 1 is a storage container taken out from a group of storage containers obtained by hot press molding a plurality of stacked sheet-like members, the storage container being composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer (excluding those in which a release agent is blended in the PBT resin layer) laminated on at least one side of the base layer, the basis weight of the base layer being 20 g/ ^m2 to 100 g/ ^m2 , the thickness of the PBT resin layer being 5 μm to 30 μm, and the crystallinity of the PBT resin layer being 9.0% or more .

With this configuration, it is possible to prevent blocking from occurring between stacked containers over the entire circumference.
The invention described in claim 2 is a storage container taken out from a group of storage containers obtained by hot press molding a plurality of stacked sheet-like members, the storage container being composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one side of the base layer, the basis weight of the base layer being 20 g/ ^m2 to 100 g/ ^m2 , the thickness of the PBT resin layer being 5 μm to 30 μm, the crystallinity of the PBT resin layer being 11.7% to 20.2%, and the ratio of the basis weight of the base layer to the thickness of the PBT resin layer (basis weight of the base layer g/m2 ^÷ thickness of the PBT resin layer μm) being 1 to 8 .
With this configuration, it is possible to prevent blocking from occurring around the entire circumferential direction between stacked storage containers, and it is also possible to prevent blocking from occurring over an area of less than 1/4 of the circumferential direction between stacked storage containers.
The invention described in claim 3 is a storage container taken out from a group of storage containers obtained by hot press molding a plurality of stacked sheet-like members, the storage container being composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one side of the base layer, and having a peripheral wall portion in which pleats are formed in the circumferential direction, the basis weight of the base layer is 20 g/ ^m2 to 100 g/ ^m2 , the thickness of the PBT resin layer is 5 μm to 30 μm, the crystallinity of the PBT resin layer is 11.7% to 20.2% , and the ratio of the basis weight of the base layer to the thickness of the PBT resin layer (basis weight of the base layer g/m2 ^÷ thickness of the PBT resin layer μm) is 1 to 8 .
With this configuration, it is possible to prevent blocking from occurring between stacked containers over the entire circumference.

The invention described in claim 4 is the structure described in claim 1 , wherein the crystallinity of the PBT resin layer is 11.5% or more.

This configuration also makes it possible to prevent blocking from occurring between stacked storage containers over an area of less than 1/4 of the circumference.

The invention described in claim 5 is the configuration of the invention described in claim 1 , in which the ratio of the basis weight of the base material layer to the thickness of the PBT resin layer (basis weight of the base material layer g/m ² ÷ thickness of the PBT resin layer μm) is 0.67 to 20.

This configuration ensures that the basis weight of the base material layer and the thickness of the PBT resin layer are within the appropriate range.

The invention described in claim 6 is a storage container group obtained by hot press molding a plurality of stacked sheet-like members, each of which is composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer (excluding those in which a release agent is blended in the PBT resin layer) laminated on at least one side of the base layer, the basis weight of the base layer being 20 g/ ^m2 to 100 g/ ^m2 , the thickness of the PBT resin layer being 5 μm to 30 μm, and the crystallinity of the PBT resin layer being 9.0% or more.

With this configuration, it is possible to prevent blocking from occurring between stacked containers over the entire circumference.
The invention described in claim 7 is a storage container group obtained by hot press molding a plurality of stacked sheet-like members, each of which is composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one side of the base layer, the basis weight of the base layer being 20 g/m2 ^to 100 g/ ^m2 , the thickness of the PBT resin layer being 5 μm to 30 μm, the crystallinity of the PBT resin layer being 11.7% to 20.2%, and the ratio of the basis weight of the base layer to the thickness of the PBT resin layer (basis weight of the base layer in g/m2 ^÷ thickness in μm of the PBT resin layer) being 1 to 8 .
With this configuration, it is possible to prevent blocking from occurring around the entire circumferential direction between stacked storage containers, and it is also possible to prevent blocking from occurring over an area of less than 1/4 of the circumferential direction between stacked storage containers.
The invention described in claim 8 is a storage container group obtained by hot press molding a plurality of stacked sheet-like members, each of which is made up of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one side of the base layer, and has a peripheral wall portion in which pleats are formed in the circumferential direction, the basis weight of the base layer is 20 g/ ^m2 to 100 g/ ^m2 , the thickness of the PBT resin layer is 5 μm to 30 μm, the crystallinity of the PBT resin layer is 11.7% to 20.2% , and the ratio of the basis weight of the base layer to the thickness of the PBT resin layer (basis weight of the base layer g/m2 ^÷ thickness of the PBT resin layer μm) is 1 to 8 .
With this configuration, it is possible to prevent blocking from occurring between stacked containers over the entire circumference.

According to a ninth aspect of the present invention, in the sixth aspect of the present invention, the crystallinity of the PBT resin layer is 11.5% or more.

This configuration also makes it possible to prevent blocking from occurring between stacked storage containers over an area of less than 1/4 of the circumference.

The invention described in claim 10 is the same as the invention described in claim 9 , except that partial blocking, in which blocking occurs over a range of less than 1/4 of the circumference between stacked storage containers, does not occur.

This configuration makes it easier to remove the storage container when in use.

The invention described in claim 11 is the same as the invention described in claim 6 , in which the ratio of the basis weight of the base material layer to the thickness of the PBT resin layer (basis weight of the base material layer g/m ² ÷ thickness of the PBT resin layer μm) is 0.67 to 20.

This configuration ensures that the basis weight of the base material layer and the thickness of the PBT resin layer are within the appropriate range.

As described above, the invention described in claim 1 can prevent blocking from occurring around the entire circumference between stacked storage containers, making them easy to remove and use.
The invention described in claim 2 can prevent blocking from occurring around the entire circumference between stacked storage containers, making them easy to remove and use when in use. In addition, it can prevent blocking from occurring around less than 1/4 of the circumference between stacked storage containers, making them even easier to remove and use when in use.
The invention described in claim 3 can prevent blocking from occurring over the entire circumference between stacked storage containers, making them easy to take out and use.

The invention described in claim 4, in addition to the effects of the invention described in claim 1 , can also prevent blocking from occurring between stacked storage containers over an area of less than 1/4 of the circumference, making them easier to remove and use.

The fifth aspect of the invention has the same effects as the first aspect, and furthermore, the basis weight of the base material layer and the thickness of the PBT resin layer are within appropriate ranges, making it possible to obtain a product that is more preferable in terms of production and use.

According to the sixth aspect of the present invention, blocking can be prevented from occurring over the entire circumference between stacked storage containers, making them easy to take out and use.
The invention described in claim 7 can prevent blocking from occurring between stacked storage containers over the entire circumferential direction, making them easy to remove and use when in use. In addition, it can prevent blocking from occurring between stacked storage containers over a range of less than 1/4 of the circumferential direction, making them even easier to remove and use when in use.
The eighth aspect of the invention can prevent blocking from occurring over the entire circumference between stacked storage containers, making them easy to take out and use.

The invention described in claim 9 has the effects of the invention described in claim 6 , and further prevents blocking from occurring between stacked storage containers over an area of less than 1/4 of the circumference, making the containers easier to remove and use.

The invention according to claim 10 has the effect of the invention according to claim 9 , and in addition, the container can be easily removed when in use, making it even easier to remove and use.

The eleventh aspect of the invention has the same effects as the sixth aspect, and furthermore, since the basis weight of the base material layer and the thickness of the PBT resin layer are within appropriate ranges, it is possible to obtain a product which is more preferable in terms of production and use.

FIG. 2 is a partial end view showing the storage container group according to the first embodiment of the present invention. 2A and 2B are diagrams showing one storage container included in the storage container group shown in FIG. 1, in which (a) is a plan view, (b) is a side view, and (c) is a cross-sectional view of part P in (b). FIG. 2 is a schematic diagram showing an example of a molding device for producing a storage container group. FIG. 11 is a schematic diagram illustrating the degree of blocking. FIG. 13 is a schematic diagram showing blocking of a conventional storage container group.

Figure 1 is a partial end view showing a storage container group according to a first embodiment of the present invention, and Figure 2 is a diagram showing one storage container included in the storage container group shown in Figure 1, where (a) is a plan view, (b) is a side view, and (c) is a cross-sectional view of part P in (b).

Referring to these figures, the storage container group 10 is composed of multiple storage containers 11, each open at the top, stacked one on top of the other.

The storage container 11 has a bottom 12 that is circular in plan view, and a peripheral wall 13 that rises from the periphery of the bottom 12 and has pleats formed in the circumferential direction. The storage container 11 is composed of a base layer 15 made of a paper material, and a polybutylene terephthalate (PBT) resin layer 16 that is layered on top of the base layer 15.

The basis weight of the base layer 15 is from 20 g/m ² to 100 g/m ² , and more preferably from 20 g/m ² to 80 g/m ² .

The thickness of the PBT resin layer 16 is 5 μm to 30 μm, more preferably 10 μm to 25 μm, and even more preferably 10 μm to 20 μm.

Here, the ratio of the basis weight (g/ ^m2 ) of the base material layer 15 to the thickness (μm) of the PBT resin layer 16 (basis weight g/ ^m2 of base material layer ÷ thickness μm of PBT resin layer) is 0.67 to 20, and more preferably 1 to 8. By configuring in this way, the basis weight of the base material layer and the thickness of the PBT resin layer are in appropriate ranges, resulting in a more preferable one in terms of production and use.

The above-mentioned storage container group 10 is obtained by hot press molding a plurality of stacked sheet-like members. An example of the hot press molding method is as follows.

Figure 3 is a schematic diagram showing an example of a molding device for producing a storage container group.

Referring to the figure, the press molding device 20 that produces the storage container group includes a male mold 21, a female mold 23 that corresponds to the male mold 21, and a tubular portion 25 that is connected downstream of the female mold 23. In addition, although not specifically shown in the figure, the device includes a moving means for moving the male mold 21 toward and away from the female mold 23, heaters for heating the female mold 23 and the tubular portion 25, and a control means for controlling the operation of the heater.

Using such a press molding device 20, a storage container is manufactured in the following process. First, the female mold 23 and the tube portion 25 are heated to an appropriate temperature by a heater. Next, blank laminates as multiple sheet-like members are placed between the male mold 21 and the female mold 23, and then the male mold 21 is moved toward the female mold 23 by the moving means, so that the blank laminate is sandwiched between the male mold 21 and the female mold 23. Next, with the blank laminate sandwiched between the male mold 21 and the female mold 23, the pressing portion 22 provided on the male mold 21 is moved downward to press the blank laminate toward the tube portion 25. As a result, an intermediate molded body 40 in which the bottom and peripheral wall portions are formed overall of the blank laminate is obtained, and this intermediate molded body 40 advances into the tube portion 25.

Then, the male die 21 is separated from the female die 23, and while the first intermediate molded body is held within the cylindrical portion 25, the next blank laminate is placed between the male die 21 and the female die 23, and the above-mentioned process is carried out again to form the next intermediate molded body so that it is stacked on top of the first intermediate molded body.

By repeating the above process several times, the previous intermediate molded body is pressed against the next intermediate molded body and moves inside the tube, and finally the intermediate molded bodies are discharged in order from the discharge port of the tube 25. In the process of moving through the tube 25, the intermediate molded bodies are heated and their shapes become stable. In this way, a storage container group 10 is obtained, and individual storage containers 11 can be removed from the storage container group 10.

In the present invention, since the crystallinity of the PBT resin layer constituting the storage container is 9.0% or more, it is possible to prevent blocking from occurring over the entire circumference between stacked storage containers 11. This makes it easy to take out individual storage containers 11 from the storage container group 10 when using the storage containers 11, and makes them easy to use. It is more preferable that the crystallinity of the PBT resin layer is 11.5% or more. Partial blocking, in which blocking occurs over a range of less than 1/4 of the circumference between stacked storage containers, is almost completely eliminated. The crystallinity of the PBT resin layer can be determined by calculating the relative crystallinity by the transmission method using a wide-angle X-ray diffraction measuring device.

Furthermore, in the above-mentioned storage container, the basis weight of the base material layer is set to 20 g/m ² to 100 g/m ² , which means that a relatively thin paper material is used. Therefore, since the rigidity is relatively weak, the upper and lower storage containers are likely to deform and come into contact with each other during molding or when the cylindrical part is heated to maintain the shape, which makes blocking more likely to occur. On the other hand, if the basis weight of the base material layer is increased to obtain high rigidity, the deformation of each storage container is suppressed, so blocking may be less likely to occur, but it becomes difficult to press mold multiple blanks stacked on top of each other.

Therefore, with the above-mentioned storage container, in a situation where the rigidity is relatively weak and blocking is likely to occur, it can be said that blocking can be efficiently suppressed by various settings, including the crystallinity.

In FIG. 1, the number of layers of the storage container group is specific, but there is no particular limit to the number of layers. In the above embodiment, the storage container is formed into a specific shape in a plan view, but this is not limited to this. The storage container may also be formed into an ellipse, a rounded rectangle, or another polygonal shape in a plan view. Furthermore, the peripheral wall of the storage container may not have pleats, or pleats may be formed in part of the circumferential direction (for example, the corners of the polygonal shape).

Furthermore, in the above embodiment, a method of heat press molding using a molding device of a specific structure has been described, but this is not limited to this. As long as a storage container group is produced, there are no particular limitations on the heat press molding method, and for example, a storage container group can be manufactured by press molding using conventionally known devices and methods.

In addition, in the above embodiment, the base layer is described as being made of a paper material, but it may also be coated with printing ink or wax. That is, the sheet member used to form the storage container group may be configured by laminating a PBT resin layer, a printing ink layer, a paper sheet layer, and a wax coat layer in this order. Also, an anchor coat layer may be interposed between the base layer and the PBT resin layer, and the paper material constituting the base layer may be subjected to a corona treatment.

Furthermore, a PBT resin layer may be laminated not only on one side of the base material layer but also on the other side.

Furthermore, although not specifically described in the above embodiment, the paper material constituting the base layer can be pure white roll paper, kraft paper, parchment paper, ivory paper, manila paper, card paper, cup paper, etc., depending on the desired application.

Furthermore, although not specifically described in the above embodiment, the method of laminating the PBT resin to the base material layer (paper material) is not particularly limited, and examples include extrusion lamination, thermal lamination, dry lamination, wet lamination, etc.

The present invention will be described in detail below based on examples. Note that the embodiment of the present invention is not limited to the examples.

(Preparation of Examples)
The storage container group according to the embodiment was produced as follows.

Twelve blanks cut from the sheet were stacked together to form one blank stack, which was then set in the molding device described in the above embodiment and molded under the following conditions.

Molding speed: 3 seconds/shot (*1)
Amount of intermediate molded bodies held in the cylinder: 6 pieces Molding temperature: 170 degrees (※2)
(※1) A shot refers to the formation of one unit of intermediate laminate from one unit of blank laminate.

The configuration of each storage container that makes up the storage container group is as follows, the PBT resin layer is formed on the inner side (storage surface side) of the storage container, and the crystallinity of the PBT resin layer is in the following 9 ranges:

Basis weight of base layer: 35 g / m ²
Thickness of PBT resin layer: 15 μm
Ratio of basis weight of substrate layer to thickness of PBT resin layer (basis weight of substrate layer g/m ² ÷ thickness of PBT resin layer μm): 35 g/m ² ÷ 15 μm = 2.33
Crystallinity: 2.3% to 20.2%
(※2) This refers to the set temperature of the female mold and the tube section.

(Testing the degree of blocking and the number of occurrences)
A group of storage containers was prepared as described in the production of the above example, and of the blank laminates of the storage container group discharged from the discharge outlet of the cylindrical portion, the outermost sheet in contact with the cylindrical portion was evaluated for each crystallinity of the PBT resin layer constituting the storage container as follows.

Figure 4 is a schematic diagram explaining the degree of blocking.

First, referring to (a), we counted cases where no blocking occurred around the entire circumference of the peripheral wall between one of the stacked storage containers and the storage container stacked directly above it (no blocking), then referring to (b), we counted cases where blocking areas 50 were confirmed within an area of less than 1/4 of the circumference of the peripheral wall (less than 1/4 blocking), and finally referring to (c), we counted cases where blocking areas 50 were confirmed within an area of 1/4 or more of the circumference of the peripheral wall (including the entire circumference) (wide area blocking).

One storage container group unit obtained from one blank laminate unit contains a total of 12 storage containers, and the outermost container that contacts the cylindrical portion of one storage container group unit was extracted and evaluated for blocking, and 10 storage container groups were evaluated in the same manner. In other words, the outermost container that contacts the cylindrical portion of the total of 12 storage containers included in one storage container group unit was collected for 10 storage container groups, and evaluation was performed on these 10 storage containers.

However, the sticking phenomenon that occurs when paper fibers get tangled at the edge of the blank between storage containers is not counted as blocking.

(Test Results)
Table 1 below shows the nine crystallinity containers and the corresponding test results.

表１を参照して、比較例１及び比較例２では、広域ブロッキングが確認された。実施例１及び実施例２では、１／４未満ブロッキングが発生したものの件数的にはわずかであり、又、広域ブロッキングは発生しなかった。

With reference to Table 1, wide-area blocking was observed in Comparative Example 1 and Comparative Example 2. In Example 1 and Example 2, although blocking occurred in an amount of less than ¼, the number of cases was small, and wide-area blocking did not occur.

Therefore, in this example, effectiveness in suppressing blocking was confirmed with a crystallinity of 9.6% or more. It is believed that a sufficient blocking suppression effect can be obtained with a crystallinity of at least 10.0% or more.

Furthermore, in Examples 3 to 7, not only did broad-area blocking not occur, but blocking of less than 1/4 did not occur either. Therefore, in this example, it is believed that blocking will basically not occur when the crystallinity is 11.7% or more. It is believed that such further blocking suppression effects can be obtained if the crystallinity is 12.0% or more.

REFERENCE SIGNS LIST 10 storage container group 11 storage container 12 bottom portion 13 peripheral wall portion 15 base material layer 16 PBT resin layer The same reference symbols in each drawing indicate the same or corresponding parts.

Claims (11)

A storage container taken out from a group of storage containers obtained by hot press molding a plurality of stacked sheet-like members, the storage container being composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer (excluding those in which a release agent is blended in the PBT resin layer) laminated on at least one of the base layers ,
The base layer has a basis weight of 20 g/m ² to 100 g/m ² ;
The thickness of the PBT resin layer is 5 μm to 30 μm,
A storage container, wherein the PBT resin layer has a crystallinity of 9.0% or more. A storage container taken out from a group of storage containers obtained by hot press molding a plurality of stacked sheet-like members, the storage container being composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one of the base layers,
The base layer has a basis weight of 20 g/m ² to 100 g/m ² ;
The thickness of the PBT resin layer is 5 μm to 30 μm,
The crystallinity of the PBT resin layer is 11.7% to 20.2%,
A storage container in which a ratio of the basis weight of the base material layer to the thickness of the PBT resin layer (basis weight of the base material layer g/m ² ÷ thickness of the PBT resin layer μm) is 1-8 . A storage container taken out of a group of storage containers obtained by hot press molding a plurality of stacked sheet-like members, the storage container being made of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one of the base layers, and having a peripheral wall portion with pleats formed in the circumferential direction,
The base layer has a basis weight of 20 g/m ² to 100 g/m ² ;
The thickness of the PBT resin layer is 5 μm to 30 μm,
The crystallinity of the PBT resin layer is 11.7% to 20.2% ,
A storage container in which a ratio of the basis weight of the base material layer to the thickness of the PBT resin layer (basis weight of the base material layer g/m ² ÷ thickness of the PBT resin layer μm) is 1-8 . 2. The container according to claim 1 , wherein the PBT resin layer has a crystallinity of 11.5% or more. 2. The storage container according to claim 1 , wherein a ratio of the basis weight of said base material layer to the thickness of said PBT resin layer (basis weight of base material layer g/m ² ÷ thickness of PBT resin layer μm) is 0.67 to 20. A storage container group obtained by hot press molding a plurality of sheet-like members in a stacked state, each storage container constituting the storage container group is composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer (excluding those in which a release agent is blended in the PBT resin layer) laminated on at least one of the base layers ,
The base layer has a basis weight of 20 g/m ² to 100 g/m ² ;
The thickness of the PBT resin layer is 5 μm to 30 μm,
A group of storage containers, wherein the PBT resin layer has a crystallinity of 9.0% or more. A storage container group obtained by hot press molding a plurality of sheet-like members in a stacked state, each storage container constituting the storage container group is composed of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one of the base layers,
The base layer has a basis weight of 20 g/m ² to 100 g/m ² ;
The thickness of the PBT resin layer is 5 μm to 30 μm,
The crystallinity of the PBT resin layer is 11.7% to 20.2%,
A group of storage containers, wherein the ratio of the basis weight of the base material layer to the thickness of the PBT resin layer (basis weight of the base material layer g/m ² ÷ thickness of the PBT resin layer μm) is 1 to 8 . A storage container group obtained by hot press molding a plurality of stacked sheet-like members, each of which is made up of a base layer made of a paper material and a polybutylene terephthalate (PBT) resin layer laminated on at least one of the base layers, and has a peripheral wall portion in which pleats are formed in the circumferential direction,
The base layer has a basis weight of 20 g/m ² to 100 g/m ² ;
The thickness of the PBT resin layer is 5 μm to 30 μm,
The crystallinity of the PBT resin layer is 11.7% to 20.2% ,
A group of storage containers, wherein the ratio of the basis weight of the base material layer to the thickness of the PBT resin layer (basis weight of the base material layer g/m ² ÷ thickness of the PBT resin layer μm) is 1 to 8 . 7. The container group according to claim 6 , wherein the PBT resin layer has a crystallinity of 11.5% or more. A storage container group according to claim 9, in which partial blocking does not occur between stacked storage containers over an area of less than 1/4 of the circumference. 7. The storage container group according to claim 6 , wherein a ratio of the basis weight of said base material layer to the thickness of said PBT resin layer (basis weight of base material layer g/m ² ÷ thickness of PBT resin layer μm) is 0.67-20.

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