JP7459205B1 - Top seal food container - Google Patents

Abstract

[Problem] To provide a top-sealed food container that fits well into a bucket when heat-sealed. [Solution] The container comprises a bottom 10, a wall 11 extending upward from the outer edge of the bottom 10, a second wall 14 that bulges outward from the top end of the wall 14 via a step 18, and a flange 13 that extends outward from the top end of the second wall 14, and has bulging portions 12 at at least two opposing locations on the wall 11, and a stacking rib 15 that protrudes inward is formed on a portion of the second wall 14. [Selected Figure] Figure 1

Description

The present invention relates to a top-sealable food container.

In recent years, there has been a social demand for reducing the amount of plastic containers used in food packaging containers for selling lunch boxes and side dishes sold at supermarkets and convenience stores, from the perspective of reducing environmental impact. Furthermore, as there is a growing need to extend the shelf life of food and reduce food loss, and to maintain the freshness of stored food, so-called top-seal lids are used to seal the containers after storing food in the container body. Molded containers of the type in which the lid material is heat-sealed to the flange of the main body are becoming widely used.

Such molded containers are usually stacked in multiple stacks during transportation and storage, but in order to prevent the containers stacked one above the other from coming into close contact with each other and becoming difficult to remove, a stacking rib is installed on the top of the container wall. For example, in Patent Document 1, a slightly larger wall portion is provided near the upper end of the wall surface of the container main body, a flat portion is provided on the lower surface of the wall portion, and a portion of the wall surface is provided with a flat portion on the lower surface. A technique has been disclosed in which a convex portion is provided that protrudes inward, thereby causing the convex portion to function as a stack rib.

However, forming a bulging wall surface that bulges outward over the entire circumference near the base of the flange, and forming a stack rib by partially protruding inward, is effective in achieving stacking properties. When storing the contents and sealing the top film, when fitting the container body into the bucket, the bulging wall surface catches on the top surface of the bucket, making it difficult to fit it neatly into the bucket. It is difficult to refit the bucket manually each time, which is a hassle, and the workability and productivity are poor.

Patent No. 6975007

Therefore, an object of the present invention is to provide a top-sealable food container that fits well into a bucket during heat sealing.

As a result of intensive studies to solve the above-mentioned problems, the present inventors focused on the side surface shape of the food container for top sealing, and the two opposite sides of the container body, from any position below or above the wall surface to the base of the flange. By forming slope-shaped bulges that bulge outward from the side wall surface at more than two locations, it is possible to fit into the bucket almost completely even though so-called stack ribs are provided. They discovered this and completed the present invention.

That is, the present invention relates to a top-sealable food container that opens at the top and has a bottom, a wall portion extending upward from the outer edge of the bottom, a second wall portion that bulges outward from the upper end of the wall portion via a step portion, and a flange portion with a flat surface that can be top-sealed from the upper end of the second wall portion, and is characterized in that at least two opposing locations on the wall portion have bulging portions that bulge outward when viewed from the contents side, and whose lower ends are joined to the wall surface and whose upper ends are joined to the base of the flange.

According to the present invention, it is possible to provide a top-sealable food container that fits well into a bucket during heat sealing.

FIG. 1 is a perspective view of a top-sealable food container of the present invention. FIG. 2 is a plan view of the top-sealable food container of the present invention. FIG. 3 is an AA end view in FIG. 2. FIG. 4 is a BB end view in FIG. 2. FIG. 5 is a front view of the top-sealable food container of the present invention, viewed from the bottom to the top in FIG. 2. FIG. 6 is a diagram showing a successful example of a bucket fitting test in the embodiment. FIG. 7 is a diagram showing a failure example of the bucket fitting test in the comparative example. FIG. 8 is a perspective view showing another embodiment of the top seal food container of the present invention.

As described above, the top-sealable food container of the present invention is a top-sealable food container that is open at the top, and includes a bottom, a wall portion extending upward from the outer edge of the bottom portion, and an external portion extending from the upper end of the wall portion through a step portion. a flange portion having a flat surface that can be top-sealed from an upper end of the second wall portion; It is characterized by having a bulge that bulges outward when viewed from the content side, the lower end of which is joined to the wall surface, and the upper end of which is joined to the base of the flange. In the present invention, since the wall surface of the container main body has a bulging portion that bulges outward from the wall surface, it is difficult to fit the container into the bucket when heat welding the film-like lid after accommodating the contents. This results in better jamming and greatly improves the workability of the top seal. Here, it is preferable that the bulging portion is formed in a slope shape or a substantially arcuate slope shape in cross section so as to expand from the lower side toward the top, and that the upper end thereof is joined to the inner edge end of the flange.

The top-sealed food container of the present invention may be circular, elliptical, or rectangular in plan view, but a rectangular shape in plan view is particularly preferred because bucket fitting errors have been prone to occur in the past and the improvement provided by the present invention is excellent. In the case of such a rectangular top-sealed food container in plan view, it is preferable that the bulges are provided at two opposing corners, and it is particularly preferable that all corners have bulges. For example, in the case of a square shape in plan view, it is preferable that each of the four corners has a bulge.

In particular, in order to be able to smoothly fit the bucket into the bucket, for example, as shown in FIG. preferable.

Furthermore, a second wall portion bulging outward from the content side is formed in the wall portion of the container body in the circumferential direction between the wall portion and the inner edge end of the flange flat portion, Further, the wall surface portion and the second wall surface portion are joined via a step. Here, in the present invention, it is preferable that a part of the second wall portion protrudes inward to form a stacking rib. In the present invention, a structure is provided in which a second wall part is provided between the upper end of the wall part and the inner edge of the flange flat part via a step part, and a part of the second wall part protrudes inward. Even if stack ribs are formed, it is possible to prevent the stepped portion from getting caught when fitting the bucket. In order to improve this effect and enable smooth fitting into the bucket, it is preferable that the upper end of the bulge be configured to be flush with the wall of the second wall. preferable.

The shape of the bulge is not particularly limited, but examples include an arcuate or U-shaped shape when viewed from the front, or a triangular, square, or trapezoidal shape with the apex facing downward when viewed from the front. However, as shown in the bulging portion 12 in FIG. 5, a circular arc or U-shaped one in front or side view is preferable from the viewpoint of ensuring a wide effective width of the bulging portion.

Specifically, for example, as shown in FIG. 5, the bulge is formed in an arc shape, is seamlessly connected to the second wall (the second wall 14 in FIGS. 1 and 5), and It is preferable that a part of the second wall portion be configured to have a stacking rib (for example, the stacking rib 15 in FIGS. 1 and 5) protruding inward.

The width of the bulging portion can be appropriately selected depending on its position, taking design into account, but the width at the corner portion is the maximum value of the straight line length in plan view (for example, the width w12 in FIG. 2). is preferably in the range of 20 to 120 mm. It is sufficient that at least one corner portion satisfies the range of the maximum width of the corner portion, but it is particularly preferable that each corner portion satisfies the range. In the present invention, it is extremely important to have a bulge at this corner from the viewpoint of fitting into the bucket.

On the other hand, the width of the bulge on the long or short side of the container (for example, width w11 in FIG. 5) is not particularly limited, but it is preferable that the length between the joint with the second wall portion at the upper end is in the range of 10 to 80 mm. Also, as shown in FIG. 1, when partitions 16 and 17 are provided, it is preferable that the bulge has a shape that is connected to the wall surface that constitutes the partition and is seamlessly integrated into the wall surface. In this case, it is preferable that the bulge is formed up to the partition wall surface in a plan view, and is arc-shaped or semi-U-shaped.

Further, when a plurality of lower end portions of the bulge portions are formed on the wall surface portion, it is preferable that the lower end portions of the bulge portions are all located at the same height from the viewpoint of ease of fitting into the bucket.

The amount of bulge of the bulge portion 12 is the horizontal width of the step portion (e.g. step portion 18 in FIG. 4) formed at the lower end of the second wall portion (e.g. The horizontal width S) in FIG. 4 is the maximum value, and specifically, it is preferably 1.5 to 4 mm. Further, it is preferable that the cross-sectional shape of the bulging portion be a slope shape that expands from the bottom to the top, from the viewpoint that it can be fitted into the bucket more reliably. Further, although this slope shape may be linear, it is preferably a slightly rounded slope shape as shown in FIG. The radius of curvature of this arcuate slope shape in cross-sectional view is preferably 20 to 50 mm.

Further, the length of the bulge in the vertical direction is not particularly limited, but may be the vertical length from the lower end of the bulge to the second wall (for example, height H3 in FIG. 5). It is preferable that the diameter is 10 to 30 mm, since the guide into the bucket is smooth. Furthermore, in the present invention, by ensuring a sufficient vertical length of the bulge with respect to the side wall, it becomes easier to avoid misalignment and fitting errors. Therefore, it is preferable that the lower end of the bulge exists at a position less than half of the overall height of the container body. Specifically, the vertical height from the lower end of the wall part to the lower end of the bulge (for example, height H2 in FIG. 3) is 5 to 20 mm, and the distance from the lower end of the bulge to the outside of the horizontal part of the flange part is 5 to 20 mm. It is preferable that the vertical height to the end (for example, height H1 in FIG. 3) is 15 to 40 mm, and H2<H1.

The size of the stacking rib can be set as appropriate, but for example, it is preferable for the protruding width (e.g., height w2 in Figure 4) to be 2 to 4 mm in order to ensure good stacking properties.

Furthermore, the height of the second wall portion, for example the height h1 in FIG. 4, is preferably 3 to 10 mm. The flange portion (flange portion 13 in FIGS. 1 and 3) formed outward from the upper stage of the second wall portion 14 may have a flat portion that can be top-sealed. The width of the flat part should be 4 mm or more, especially the horizontal width w1 shown in FIGS. 3 and 4, since the wider the width, the easier it is to adjust the sealing strength by selecting the heat sealing width. Preferably, it is 12 mm.

Furthermore, the flat part of the flange part is formed at a predetermined angle so as to be inclined outward and downward as shown in Figure 4, which prevents food and dirt from getting caught during the top sealing process. More specifically, it is preferable to have an inclination of 2 to 6 degrees. Further, it is preferable that a skirt is provided below from the outer edge of the flat part, and a horizontal end is formed outward from the lower end of the skirt, from the viewpoint of increasing the rigidity of the flange part itself.

The top-seal food container of the present invention may be a container with multiple storage compartments with partitions, as shown in Figure 1, or a container without partitions, as shown in Figure 8.

The top-sealable food container of the present invention described in detail above may be a foamed container or a non-foamed container, but it is particularly advantageous because it is a cold-resistant container and has excellent strength in cold and hot environments. It is preferable that the container is a non-foaming container made of a polyolefin resin containing an inorganic filler.

Specifically, a composite sheet in which a polyolefin resin and an inorganic filler are dispersed using the resin as a matrix is preferably formed into a predetermined shape, and examples of the inorganic filler include talc, calcium carbonate, calcium sulfate, Examples include barium sulfate, kaolin, mica, zinc oxide, dolomite, silica, silicon dioxide, bentonite, clay, and zeolite. Among these, talc is preferred because it has good dispersibility as a polyolefin and has a remarkable effect of improving strength.

Furthermore, in the present invention, among the above-mentioned talc, it is preferable that the average particle diameter (D50) is in the range of 2 to 8 μm and the aspect ratio is in the range of 30 to 50. This is preferable from the point of view that it is possible to achieve the following. Here, talc usually has a flat shape, and as the particle size decreases, the aspect ratio indicating the flatness rate also tends to decrease, but those with the above average particle size and aspect ratio are Although the average particle diameter is small, the aspect ratio is high. By using talc having such a unique particle size and aspect ratio as a dispersion filler, the strength of the container after thermoforming can be dramatically improved.

Here, the average particle diameter (D50) is the median diameter (D50) determined by laser diffraction/scattering method, and specifically, according to JIS Z8824, if necessary, ultrasonic treatment is performed to obtain a primary particle dispersion, and then This is a value measured in accordance with JIS Z8825. In the present invention, particles having an average particle diameter (D50) of 3 to 7 μm, particularly 4 to 6 μm are preferable because the above-mentioned effects are clearly exhibited.

In addition, the aspect ratio is determined by observing talc particles at 30,000 to 100,000 times using an ultra-high resolution field emission scanning electron microscope (product name "S-4800" manufactured by Hitachi, Ltd.). It is possible to arbitrarily select 10 pieces, measure the thickness and length of each cross section, calculate each aspect ratio (length/thickness), and further calculate the arithmetic mean value.

Further, the talc preferably has a specific surface area (BET) in the range of 7 to 10 m ² /g from the viewpoint of good wettability with the resin component constituting the matrix.

In addition, to check the properties of the talc used from a molded container, for example, cut out an 80 mm x 80 mm area from the bottom of the container, dissolve the test piece in a high boiling point solvent such as decalin at high temperature, extract the talc, and dry it. It can be measured by the method described above.

The talc described in detail above may be treated with a silane coupling agent to improve wettability when dispersed in the resin.

Next, examples of the olefin resin constituting the matrix include polyethylene resin, polypropylene resin, and ethylene-vinyl acetate copolymer, but in the present invention, it can be used as a mixed resin of polypropylene resin and high-density polyethylene. is preferable because it can exhibit excellent performance in cold resistance and heat resistance.

Examples of the polypropylene resin include polypropylene such as isotactic polypropylene, syndiotactic polypropylene, and attack polypropylene, ethylene-propylene random polymer, ethylene-propylene block copolymer, ethylene-propylene butene copolymer, and propylene-based polypropylene. Butene-1 copolymer, propylene-butene copolymer, propylene-maleic anhydride copolymer, propylene-propylene-butene-1 copolymer, polyethylene or polypropylene modified with unsaturated carboxylic acid (e.g. maleic anhydride) can be mentioned.

Among these, ethylene-propylene block copolymer (hereinafter sometimes abbreviated as "block polypropylene (A)") has a sea-island structure in which polyethylene is dispersed in the form of islands in a propylene phase. This is preferable because the rubber phase present at the interface exhibits excellent impact resistance.

Further, when using block polypropylene (A), it is preferable to mix high density polyethylene (hereinafter sometimes referred to as "high density polyethylene (B)") with the block polypropylene (A). Here, the high-density polyethylene (B) is polyethylene with a density of 0.942 to 0.970, and by using a relatively large amount of this high-density polyethylene (B) in the present invention, it can be made into a molded product that is harder and more rigid. Become.

The blending ratio (content ratio) of block polypropylene (A), high density polyethylene (B), and talc is based on mass, and [(A)/(B)/talc] is 20/60/20 to 35/30. A ratio of /35 can effectively prevent falling when molded, stacking, and cracking and distortion when subjected to heavy loads, and improve impact resistance in a frozen environment. This is preferable because it increases dramatically. In particular, these various effects are more pronounced when the composite sheet contains 25-35% by mass of block polypropylene (A), 35-50% by mass of high-density polyethylene (B), and 25-35% by mass of talc. It is preferable from the point of view of being useful. In this way, by using a relatively large amount of high-density polyethylene (B) and talc with a specific size and shape, the rigidity can be increased without impairing the impact strength of block polypropylene (A), and the impact strength at ultra-low temperatures can be increased. It is noteworthy that this phenomenon is also expressed.

The composite sheet may contain various additives, such as antioxidants, colorants, ultraviolet absorbers, antistatic agents, plasticizers, and lubricants, as necessary.

The composite sheet has the sheet described in detail above as a base layer (2), a first surface layer (3) on one surface thereof, and a second surface layer (3') on the opposite surface. It is preferable to use a laminated sheet because the final molded product has a good appearance gloss.

When the surface layer (3) and surface layer (3') are laminated on both surfaces of the base material layer (2) in this manner, a sheet having a so-called two-type three-layer structure is obtained. Here, the surface layer (3) and the surface layer (3') are preferably composed of a polyolefin resin, and in particular, a propylene homopolymer has excellent adhesion with the base material layer, and is suitable for molded products. This is preferred from the viewpoint of excellent gloss.

The thickness of the composite sheet is not particularly limited, and can be selected, for example, from a range of 200 to 600 μm in total thickness including the base layer and surface layer. As mentioned above, the present invention uses ordinary talc with an average particle diameter (D50) of 10 to 20 μm and an aspect ratio of about 20 to 25, since it can exhibit excellent mechanical strength when made into a container. The sheet thickness can be made thinner than when using the conventional type. Specifically, when trying to obtain the same strength as the conventional type, it is possible to reduce the total sheet thickness by 5 to 8%. .

From the above viewpoints, the thickness of the base layer is preferably in the range of 180 to 590 mm, and the thickness of the surface layer is preferably such that the total layer thickness on both surfaces is in the range of 1 to 10% of the total thickness of the sheet.

In order to manufacture the above-mentioned composite sheet, for example, a masterbatch is prepared by melt-mixing the above-mentioned components constituting the base material layer, and this is used to form a film by melt-kneading, extrusion through a T-die, and non-stretching. One method is to do so. In addition, when the base material layer has surface layers on both sides, the film can be formed to a predetermined thickness by a so-called coextrusion method.

The composite sheet detailed above can be thermoformed into a desired shape by a conventional method such as vacuum forming or pressure forming to produce the top-sealable food container of the present invention.

Next, the top film used in the top-sealing food container of the present invention may be any of the interfacial peeling type, interlayer peeling type, and cohesive peeling type. Among these, delamination type and cohesive peel type are preferred from the viewpoint of excellent adhesion and sealing properties with the container surface.

Specifically, such interlayer peeling type or cohesive peeling type top film may have a cohesive peeling layer or an interlayer peeling layer on a base film, and may have a multilayer structure of at least two or more layers. Among these, a multilayer film in which base film/support film/cohesive release layer (or interlayer release layer) are laminated in this order is preferred.

Here, various styrene resins, nylon resins, and polyester resins can be used as the base film, but nylon resins and polyester resins are particularly preferred from the viewpoint of rigidity. The thickness of the base film is, for example, in the range of 5 to 20 μm.

As the support film, a resin material having high affinity with the cohesive release layer or the interlayer release layer can be appropriately selected, and examples thereof include polyethylene, high-density polyethylene, polypropylene, propylene block copolymer, and the like. The thickness of such a support film is preferably in the range of 20 to 60 μm when used as one layer, and 20 to 60 μm in total when used as two layers.

In the present invention, the above-mentioned top-sealed product may be further wrapped in pillow packaging to make a food product.

Hereinafter, embodiments of the top-sealable food container of the present invention will be described based on the drawings.

<Embodiment 1>
This embodiment is represented by a container body 1 in FIG. 1, which includes a bottom portion 10, a wall portion 11 extending upward from the outer edge of the bottom portion, and an external portion extending from the upper end of the wall portion through a step portion 18 (see FIG. 4). The container body 1 is provided with a second wall portion 14 that bulges out in the direction, and a flange portion 13 having a flat surface that can be top-sealed from the upper end of the second wall portion. It has a bulging part 12 which bulges outward from the wall surface 11 when viewed from the content side, and whose lower end is joined to the wall surface and whose upper end is joined to the base of the flange.

Here, as shown in FIG. 3, the bulging portion 12 is formed so as to expand upward from the lower side in a slope shape in a substantially circular arc shape when viewed in cross section, and its upper end is the inner edge of the flange portion 13. It is joined at the end. The top seal food container in this embodiment has a rectangular shape in plan view. As described above, top seal containers that are rectangular in plan view have been prone to bucket fitting errors, so the improvement effect by employing the bulging portion 12 of the present invention is significant.

Furthermore, a second wall portion 14 is formed in the circumferential direction between the wall portion 11 of the container body and the inner edge of the flange portion 13, and the second wall portion 14 is connected to the wall portion 11 via a step portion 18. A part of the second wall portion 14 protrudes inward to form a stacking rib. In the past, there was a problem that the stacking rib was difficult to fit into the bucket when it was provided, but this invention can almost completely solve this problem. In this embodiment, the shape of the bulge portion is an arc shape when viewed from the front.

Here, in this embodiment, the bulging portion 12 is seamlessly connected to the second wall portion 14 at its upper portion.

More specifically, the width w12 of the bulged portion 12 at the corner portion (the maximum linear length in plan view in FIG. 2) is 33 mm, and the width w12 at the long side or the short side (the width w12 between the second wall portion and the second wall portion) is 33 mm. The length between the joints (width w11) in FIG. 5 is 58 mm.

The lower ends of the bulging portions 12 are all located at the same height. The amount of bulging of the bulging portions 12 is such that the horizontal width S of the step portion 18 of the second wall portion shown in FIG. 4 is 2.6 mm, and the radius of curvature of the arc-shaped slope shape in cross section is 36 mm.

Furthermore, the vertical length of the bulging portion 12 is the vertical length from the lower end of the bulging portion to the second wall portion 14, and the height H3 in FIG. 5 is 18.5 mm . The vertical height from the lower end of the portion 11 to the lower end 12 of the bulge (height H2 in FIG. 3) is 9.5 mm, and the vertical height from the lower end of the bulge 12 to the outer end of the horizontal portion of the flange portion is 9.5 mm. The height (height H1 in FIG. 3) is 25.5 mm.

The height of the second wall portion 14, specifically the height h1 in FIG. 4, is 7 mm, and the protruding width of the stacking rib 15 (height w2 in FIG. 4) is 3.4 mm.

Furthermore, the flange portion 13 formed outward from the upper stage of the second wall portion 14 has a flat portion that can be top-sealed, and in this embodiment, the width w1 of the flat portion is 8 mm and is configured with an inclination angle α of 4 degrees downward from the horizontal. Furthermore, a skirt is formed downward from the outer edge of the flat portion, and a horizontal end portion is formed outward from the bottom end of the skirt.

Furthermore, in this embodiment, the container has multiple storage compartments separated by partitions 16 and 17, as shown in FIG. 1.

Another embodiment is a container without partitions as shown in FIG. The presence or absence of partitions and the number thereof can be appropriately selected depending on the purpose.

Example 1
A masterbatch for the base layer (2) and a masterbatch for the surface layers (3) and (3') were prepared according to the formulations in Table 1 below. The masterbatch for the base layer (2) and the masterbatch for the surface layer (3) were each fed to an extruder and extruded through a T-die to obtain a two-kind, three-layer unstretched laminate sheet.
The obtained sheet was subjected to various evaluations, and the results are shown in Table 1.

<Tensile test (tensile modulus)>
Test pieces were cut from the sheet obtained in Example 1 in the MD and TD directions, and a tensile test was carried out at room temperature [test speed: 1 (mm/min)] to determine the tensile modulus of elasticity.

<Bending test (flexural modulus)>
Test pieces were cut from the sheet obtained in Example 1 in the MD and TD directions, and a bending test was carried out at room temperature [test speed: 100 (mm/min)] to determine the bending modulus.

<Cold resistance and impact resistance (-30℃ DuPont impact test)>
A test piece was taken from the sheet obtained in Example 1 and subjected to a DuPont impact test [striking core diameter: 12.689 (mm)] in an environment of -30°C to determine the 50% fracture energy.

The talc used in Example 1 was the talc manufactured by Nippon Talc Co., Ltd. and listed in the table below, and the master batch was prepared by Starfield Corporation.

Next, the non-stretched laminated sheet obtained in Example 1 was molded into the top-sealable food container A shown in the embodiment of the present invention.

Comparative Example 1
As a comparative example, a top-sealed food container B (having a stepped portion and stacking protrusions around the entire circumference) was molded, which had the same dimensions as top-sealed container A, except that there were no bulging portions on each of the four sides or corners.

Example 2
A bucket fitting test was carried out using the top-sealable food container A according to the following test method. The results are shown in Table 3.
(Test method)
As shown in Figure 6, the bucket was placed on the base, and then a polystyrene foam pull-out stand was placed on top of that with a height of 50 mm to the bucket. The flange portion of container A was then placed on top of that, and the left and right polystyrene foam stands were pulled out simultaneously.
This was done 100 times and the number of times it fitted properly on the bucket was counted.

Example 3
Top-seal food container A was rotated 10 degrees to the right in plan view with respect to the four sides of the bucket opening and placed on a styrofoam pull-out stand, and a bucket fitting test was performed in the same manner as in Example 2. was carried out.

Comparative example 2
Container B was placed on a pull-out stand in the same manner as in Example 2, except that food container B for top sealing was used, and the left and right Styrofoam stands were pulled out at the same time.
This was done 100 times, and the number of times it fit properly onto the bucket was counted.

Comparative example 3
Container B was placed on a pull-out stand in the same manner as in Example 3, except that food container B for top sealing was used, and the left and right Styrofoam stands were pulled out at the same time.
This was done 100 times, and the number of times it fit properly onto the bucket was counted.

なお、成功した状態を図６に、失敗した状態を図７に模式的に示す。

Note that a successful state is schematically shown in FIG. 6, and a failed state is schematically shown in FIG.

1...Top seal food container 11...Wall surface part 12...Bulging part 13...Flange part 14...Second wall part 15...Stacking rib 16...Partition 17...・・Partition 18 ・・Step part 21 ・・Base 22 ・・Bucket 23 ・・Drawing stand

Claims (5)

A top-sealable food container having a rectangular shape in plan view and opening at the top, the food container comprising a bottom, a wall portion extending upward from the outer edge of the bottom, a second wall portion bulging outward from the upper end of the wall portion through a step portion, and a flange portion having a flat surface that can be top-sealed from the upper end of the second wall portion, the flange portion having a flat surface that can be top-sealed from the upper end of the second wall portion, and at least two corner portions at opposing positions of the wall portion, the bulging portions bulge outward from the wall portion when viewed from the side of the contents, the lower ends of the bulging portions being joined to the wall portion at a position that is less than half the height of the entire container , and the upper ends of the bulging portions being joined to the base of the flange,
The shape of the bulge portion when viewed from the front is an arc shape or a U shape with the lower end of the bulge portion as a vertex,
The cross-sectional shape of the bulging portion is an arc-shaped slope shape expanding from bottom to top,
A top-sealable food container , characterized in that the amount of expansion of the bulging portion is formed so as not to exceed the horizontal width of the step portion . 2. The top-sealable food container according to claim 1 , wherein a stacking rib protruding inward is formed at a location in the circumferential direction of the second wall where the bulge is not provided . The radius of curvature of the cross-sectional shape of the bulge is 20 mm to 50 mm,
The width of the corner portion of the bulge is 20 to 120 mm in a linear length in a plan view,
A vertical length from a lower end of the bulge portion to the second wall portion is 10 to 30 mm,
3. The top -sealable food container according to claim 1, wherein the vertical length from the lower end of the wall portion to the lower end of the bulge portion is 5 to 20 mm . The top-sealable food container according to claim 1 or 2, comprising a resin composition containing a polyolefin resin and an inorganic filler. The food container for top sealing according to claim 4 , wherein the inorganic filler is talc having an average particle diameter (D50) of 2 to 8 μm and an aspect ratio of 30 to 50.

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