JP7461761B2 - Paper container with lid for microwave cooking food - Google Patents

Description

This invention relates to a paper container with a lid for use in heating food in a microwave oven.

Prepared foods sold at retailers such as convenience stores are stored in disposable containers that are used only once for display, sale, etc., and can be cooked in a microwave oven when purchased or after taking the food home. After cooking, the food is eaten directly from the container. Because this type of container for prepared foods is a disposable container, it is common for it to be made of a molded synthetic resin sheet with a lid fitting structure that is as simplified as possible.

For example, foods such as rice bowls and noodles contain a relatively large amount of moisture, so internally fitted containers with lids are used in which the fitting part of the lid is tightly fitted to the inner wall part of the upper opening of the heat-resistant resin container body (see, for example, Patent Document 1). In internally fitted containers with lids, the inner wall part of the upper opening of the resin container body is formed in an inverted tapered shape, and the fitting part of the lid is formed in a protruding shape that corresponds to the inverted tapered inner wall part, so that the protruding fitting part of the lid fits deeply into the inverted tapered inner wall part of the container, thereby achieving tight contact between the two.

Meanwhile, for food containers for microwave cooking, such as gratin or doria, paper container bodies have traditionally been used, and for ease of consumption, they are formed into a deep dish or shallow cylinder shape with a low height compared to the flat shape. This type of paper container is made by rolling thick cardboard into a circular shape to form the body of the container body, the upper part of which is rolled outward to form the outwardly rolled opening edge, and the lower part is folded inward and joined to the bottom plate to form the bottom.

However, this type of paper container body has a smooth inner wall surface at the top opening, and cannot be specially shaped for internal fitting, such as an inverted taper shape, as with the resin containers described above. Therefore, when closing the lid, the peripheral wall portion that extends downward from the outer periphery of the lid surface of the lid body is attached from the outside to the rolled-up opening edge of the container body, and the peripheral wall portion of the lid body is engaged with the underside of the rolled-up edge of the container body to form an external fit.

In paper containers like this gratin, the food contents are heavy and contain a lot of moisture, so they require a relatively long time to heat in a microwave oven. When heated, steam is generated inside the container, and the lid is provided with a steam hole to release the steam inside the container. However, because conventional paper containers are closed by an external fitting, the pressure caused by heating and the deformation of the container can cause the fitting part between the container body and the lid to loosen, allowing steam to leak from the outer periphery of the lid and heating the area around the external fitting part between the container body and the lid. This causes the problem that when the container is taken out and carried after cooking and the fingers are placed on the edge of the container body, the container becomes hot and difficult to hold and handle.

In particular, for the lid, a synthetic resin sheet molded product is often used for its formability, and when the lid is fitted to the outside of the rolled edge of the opening of the paper container body, there is a tendency for the fitting to become loose when heated near the outer fitting part where the peripheral wall of the lid is located on the outside of the container body due to the difference in deformation characteristics when heated caused by the difference in the materials of the two, that is, the paper container body is capable of partial deformation and is relatively rigid as a whole and has a small amount of deformation (particularly in containers such as gratin and doria, the peripheral wall is low in height and has a rigid side wall), while the resin lid is flexible in that it is more likely to deform overall than partially (particularly in lids for gratin and doria, the peripheral wall is narrow compared to the lid surface, so deformation of the peripheral wall that fits externally is large).

JP 2019-127301 A

The present invention has been made in consideration of these points, and provides an advantageous paper container with a lid for heating food in a microwave oven, which has a paper container body and can close the lid properly simply by fitting the paper container body and the lid together, has high adhesion between the paper container body and the lid, and can minimize leakage of steam from the fitting part, especially during heating, is easy to use, and can significantly improve the uses and functions of conventional paper containers.

That is, the invention of claim 1 comprises a paper container body made of paper or a material mainly composed of paper or plant fiber, having an outer rolled edge at an upper opening, and a groove-like fitting portion formed on an inner peripheral wall portion near the outer rolled edge of the upper opening and running parallel to the outer rolled edge of the upper opening; a lid surface portion that covers the upper opening of the paper container body and has a steam hole for discharging steam from within the paper container body; a lid flange portion that abuts against the edge of the upper opening of the paper container body; and a lid flange portion that is interposed between the lid surface portion and the lid flange portion and enters the upper opening of the paper container body. the lid flange extends outward from the upper end of the hanging portion and a lid body having a convex strip fitting portion formed on the outer periphery of the hanging portion, the lid flange extending outward from the upper end of the hanging portion, the diameter (D1) of the lid body at the convex strip fitting portion is greater than the diameter (D2) of the paper container body at the concave groove-like fitting portion and the protruding length (L1) of the convex strip fitting portion is greater than or equal to the depth (L2) of the concave groove-like fitting portion, and when the lid is closed, the convex strip fitting portion is pressed against the concave groove-like fitting portion to fit therein .

The invention of claim 2 relates to a paper container with a lid for heating food in a microwave oven, as described in claim 1, in which the lid is made of a synthetic resin sheet molded product.

The invention of claim 3 relates to a heat-resistant paper container with a lid for heating food in a microwave oven, as described in claim 1 or 2, in which the paper container body is in the shape of a deep dish or a shallow cylinder for eating.

The invention of claim 4 relates to a paper container with a lid for heating food in a microwave oven, as described in claim 3, in which the maximum diameter of the paper container body is 25 cm or less, and the ratio of the diameter to the container height is 2 to 5.

The invention of claim 5 relates to a paper container with a lid for heating food in a microwave oven according to claims 3 or 4, in which the container is a gratin dish or a doria dish.

According to the invention of claim 1, the lidded paper container for food heated in a microwave oven comprises a paper container body made of paper or a material mainly composed of paper or plant fiber, with an outer rolled edge at an upper opening, and a groove-like fitting portion formed on an inner peripheral wall portion near the outer rolled edge of the upper opening and running parallel to the outer rolled edge of the upper opening; a lid surface portion covering the upper opening of the paper container body and having a steam hole for discharging steam from within the paper container body; a lid flange portion abutting the edge of the upper opening of the paper container body; and a hanging portion interposed between the lid surface portion and the lid flange portion and provided around the upper opening of the paper container body so as to enter the upper opening of the paper container body, and a lid body extending outward from the upper end of the lower portion and having a convex strip fitting portion formed on the outer periphery of the hanging portion , wherein the diameter (D1) of the lid body at the convex strip fitting portion is greater than the diameter (D2) of the paper container body at the concave groove-shaped fitting portion and the protruding length (L1) of the convex strip fitting portion is configured to be greater than or equal to the depth (L2) of the concave groove-shaped fitting portion, so that when the lid is closed, the convex strip fitting portion is pressed against the concave groove-shaped fitting portion to fit into it , thereby allowing the lid body to be held in an internally fitted state against the paper container body and improving the adhesion of the fitting portion, and even if steam is generated inside the container during cooking in a microwave oven, it is possible to prevent steam from being released from the fitting portion.

According to the invention of claim 2, the paper container with lid for microwave cooking food is the invention of claim 1, and since the lid is made of a synthetic resin sheet molded product, not only is there a large degree of freedom in the shape of the lid and it is easy to mold it precisely, but deformation of the convex fitting part of the synthetic resin sheet lid during heating can be prevented by the partial deformability of the groove-like fitting part of the paper container body and the overall rigidity of the container body, ensuring effective adhesion.

According to the invention of claim 3, the paper container with lid for microwave-heated food is in the invention of claim 1 or 2, and since the paper container body is in the shape of a deep dish or a shallow cylinder for eating, the rigidity strength in the circumferential direction of the side wall of the paper container body can be increased, and the convex-strip fitting portion of the lid can be more reliably received and pressed against the concave-groove fitting portion in the side wall of the container body, and the adhesion between the convex-strip fitting portion and the concave-groove fitting portion is further improved.

According to the invention of claim 4, the paper container with lid for cooking food in a microwave oven is the invention of claim 3, in which the maximum diameter of the paper container body is within 25 cm and the ratio of the diameter to the container height is 2 to 5, making it easy to use for cooking food in a microwave oven, and allowing for a more appropriate internal fit between the container body and the lid, and further improving the adhesion between the convex fitting portion and the concave groove fitting portion.

According to the invention of claim 5, which is a paper container with a lid for cooking food in a microwave oven, in the invention of claims 3 or 4, the container is a gratin dish or a doria dish, so that the corresponding cooked food can be easily eaten as is after cooking.

1 is a schematic cross-sectional view of a lidded paper container for use in heating food in a microwave oven according to one embodiment of the present invention. FIG. 1 is a plan view of a lid having steam holes consisting of multiple long holes. FIG. 1 is a plan view of a lid having a steam hole formed by a tongue-shaped opening. FIG. 1 is a schematic cross-sectional view of the vicinity of the edge of the top opening of a lidded paper container when the lid is open. 1 is a schematic cross-sectional view of the vicinity of the edge of the top opening of a lidded paper container when the lid is closed. 1 is a schematic cross-sectional view of the vicinity of the edge of the upper opening when the lid is pressed into a paper container with a lid.

The paper container with lid 10 for microwave heating food according to one embodiment of the present invention shown in Figure 1 is a container for storing mainly cooked foods, and comprises a paper container body 20 and a lid 30. Foods that can be stored in the container 10 include various cooked foods, such as boxed lunches such as gratin, doria, curry rice, oyakodon, gyudon, katsudon, and Chinese rice bowls, as well as noodles such as udon, soba, ramen, and pasta. The container 10 is particularly suitable for storing foods that are large in mass (weight), contain a lot of moisture, and require a relatively long microwave heating time.

The lidded paper container 10 containing food is a container used to package various foods sold in stores such as convenience stores, supermarkets, department stores, restaurants, delicatessens, coffee shops, and service areas, and is suitable for cooking in a microwave oven. The main anticipated use is as a disposable container (throwaway container) that is used only once, such as one-way or disposable. Using a disposable container is convenient for sanitary management of food.

The paper container body 20 is a container for storing cooked food, made of paper or a material mainly made of paper or plant fiber. The paper or a material mainly made of paper or plant fiber that constitutes the paper container body 20 is a conventionally known thick paperboard. Since the paper container body 20 is made of paper and has excellent heat resistance, it can be suitably used for cooking in a microwave oven. In addition, in the paper container body 20, a resin film such as a polyethylene resin, a polystyrene resin, a polypropylene resin, or a polyester resin may be laminated on the inside or both the inside and outside of the container to impart water resistance, heat resistance, oil resistance, etc. The thickness of the laminated resin film is not particularly limited, but is, for example, about 15 to 40 μm. In the embodiment, a heat-resistant PET resin film having a thickness of 33 μm is laminated.

As shown in FIG. 1, this paper container body 20 has an outer rolled edge 22 at the upper opening 21, and a container body 24 stands upright from the container bottom 23 to the upper opening 21. The shape of the paper container body 20 is set appropriately according to the type of food to be stored. Reference numeral 28 denotes a folded portion of the bottom paperboard 23s that constitutes the bottom 23, and reference numeral 29 denotes a folded portion of the body paperboard 24s that constitutes the body 24, and the bottom 23 is formed by bonding together the folded portions 28 and 29.

The illustrated paper container body 20 is a deep dish or shallow cylinder shape with a height smaller than the diameter of the upper opening 21. The deep dish or shallow cylinder shaped paper container body 20 of the embodiment is a gratin dish or doria dish, and is suitable for eating cooked foods such as gratin, doria, curry rice, pasta, oden, and soups such as shark fin soup, tom yum goong, borsch, and bouillabaisse, and is served as it is as a dish after cooking these foods.

The paper container body 20 is a circular or elliptical container with a maximum diameter of 25 cm or less so that it can be stored in a normal microwave oven, and considering convenience for eating, it is preferable that the ratio of the diameter (D) to the container height (H) is in the range of 2 to 5. In the embodiment, there are roughly three sizes as follows.
Size: Container height (H) Diameter (D) Ratio (D/H)
S: 40mm 135mm 3.38
M: 40mm 150mm 3.75
L: 40mm 160mm 4.00

The paper container body 20 is manufactured by a known paper container manufacturing method. For example, a fan-shaped or belt-shaped body paperboard 24s is formed into a cylindrical shape to form the container body 24, and the upper part of the body paperboard 24s is wrapped around the outside to form an upper opening 21 having an outer wrapped edge 22, and the folded part 29 at the lower part of the body paperboard 24s is joined to the folded part 28 of the circular bottom paperboard 23s to form the container bottom 23, thereby obtaining the paper container body 20. For example, the paper container body 20 is formed into a cylindrical shape in which the container body 24 is approximately vertical by making the upper opening 21 and the container bottom 23 approximately the same diameter, or is formed into an inverted truncated cone shape in which the container body 24 is tapered by making the upper opening 21 larger in diameter than the container bottom 23 as in the embodiment. The illustrated paper container body 20 is formed into an inverted truncated cone shape. The shapes of the upper opening 21 and the container bottom 23 may be approximately elliptical. The inverted truncated cone shape makes it easy to stack and store.

As shown in the figure, the paper container body 20 has a groove-shaped fitting portion 40 formed on the inner peripheral wall portion 24a of the container body 24 near the outer peripheral edge portion 22 of the upper opening 21, which runs parallel to the outer peripheral edge portion 22 of the upper opening 21. The groove-shaped fitting portion 40 is a portion that allows the lid body 30 described below to be fitted inside, and is formed by a known groove forming device or jig after the paper container body 20 is molded, so that it has a shape in which a part of the container body 24 is pushed out from the inside to the outside, as shown in the figure. Therefore, at a position corresponding to the groove-shaped fitting portion 40 on the outer peripheral wall portion 24b of the container body 24, the outer peripheral convex streak portion 25 is formed around the entire circumference. This groove-shaped fitting portion 40 can be formed by pressing a predetermined position of the container body 24 from the inside of the paper container body 20 using an appropriate pressing device or the like.

Although not shown in the figures, the paper container body 20 may have an appropriate insulating section formed on the outside. The insulating section may be a known container insulating structure such as embossing the container body 24 of the paper container body 20, uneven processing on the outer periphery of the paper container body 20 using insulating ink or the like, or wrapping a sleeve of insulating paper such as embossed paper. By providing an insulating section on the outside of the paper container body 20, the effect of heat when touching the paper container body 20 after cooking in a microwave oven can be mitigated.

The lid 30 is a member that covers the upper opening 21 of the paper container body 20, and as shown in FIG. 1, has a lid surface portion 31, a lid flange portion 34, and a hanging portion 35. The lid 30 is preferably made of synthetic resin, since it allows a large degree of freedom in the shape of the lid and allows for easy precision molding. For example, a molded product of a synthetic resin sheet is preferable in terms of mass production and economy. Examples of the synthetic resin sheet that constitutes the lid 30 include sheets of thermoplastic resins such as polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, and further sheets of thermoplastic resins such as biodegradable resins such as polylactic acid. The synthetic resin sheets are formed into various shapes, including those shown in the figure, by vacuum molding.

The lid surface portion 31 covers the upper opening 21 of the paper container body 20 and has a steam hole 32 that exhausts steam from within the paper container body 20. The shape of the steam hole 32 is not particularly limited as long as it can properly exhaust steam, and it is configured in an appropriate shape such as a small hole, a long hole, or a tongue-shaped opening.

For example, FIG. 2 is a plan view of a lid body 30A having a steam hole 32a consisting of a plurality of long holes. The steam hole 32a is formed in a concave surface portion 33 formed at an appropriate position of the lid surface portion 31, and constitutes a group of long holes consisting of a plurality of long holes. The steam hole 32a consisting of a plurality of long holes is preferably formed, for example, by laser processing using irradiation of a laser beam. Laser processing can form the steam hole 32a simply, quickly, and accurately. The size of the long hole is not particularly limited as long as it is possible to appropriately discharge steam from within the paper container body 20. For example, when the steam hole 32 is a group of long holes, the appropriate conditions for discharging steam and preventing foreign matter from entering the paper container body 20 are a width of 0.15 to 1.0 mm, a length of 1 to 12 mm, and a total opening area of 0.3 to 100 mm2, which allows steam to be appropriately discharged and makes it possible to prevent foreign matter from entering the paper container body 20 without providing a member that covers the steam hole 32 to prevent foreign matter from entering the paper container body ^20. Although not shown in the figure, fine holes (group of fine holes) may be formed instead of the long holes (group of long holes). The appropriate conditions for the pores (group of pores) to discharge steam and suppress the ingress of foreign matter are a diameter of 0.15 to 1.0 mm, preferably 0.15 to 0.59 mm, a number of 8 to 1000, and a total opening area of 0.25 to ¹⁰⁰ mm2.

Figure 3 is a plan view of the lid 30B having a steam hole 32b consisting of a tongue-shaped opening. The steam hole 32b is formed by a known processing device such as a punching blade. The steam hole 32b consisting of a tongue-shaped opening is pushed up and opened by steam generated inside the container, allowing the steam to be discharged. The steam hole 32b consisting of a tongue-shaped opening can be formed inexpensively and easily. The lid 30B having this steam hole 32b is preferably used when the entire container 10 is covered with a film or the like when packaging a product.

The lid flange 34 is a portion that contacts the edge of the upper opening 21 of the paper container body 20 over its entire circumference, and prevents the lid 30 from excessively entering or dropping into the paper container body 20 when the lid is closed. The shape of the lid flange 34 is not particularly limited as long as it can contact the edge of the upper opening 21 of the paper container body 20. For example, since the upper opening 21 has an outer rolled edge 22 and the upper side of the edge is curved, it is preferable to have a lid flange 34a with a curved shape corresponding to the outer rolled edge 22, as shown in Figures 4 and 5. The curved lid flange 34a improves the sense of moderation when the lid 30 is closed. The lid flange 34 may be knurled as necessary.

As shown in Figures 4 and 5, the hanging portion 35 is a portion that is interposed between the lid surface portion 31 and the lid flange portion 34 and is provided so as to enter the upper opening 21 of the paper container body 20, and is adjacent to or abuts the inner wall portion 24a near the upper opening 21 when the lid is closed. The shape of the hanging portion 35 is appropriate, such as being perpendicular to the lid surface portion 31 or inclined along the inner wall portion 24a of the paper container body 20. In addition, the lid flange portion 34 is extended outward from the upper end of this hanging portion 35.

The hanging portion 35 has a protruding fitting portion 50 formed on the outer periphery 35a, which fits into the groove-like fitting portion 40 of the paper container body 20 when the lid is closed. The protruding fitting portion 50 is a portion that fits into the groove-like fitting portion 40 of the paper container body 20 when the lid is closed, thereby enabling the lid body 30 to maintain its internal fit.

Conventionally, it has been difficult to close a lid on a paper container body by simply fitting it inside. This is because, when the container body is made of paper, the inner wall portion near the top opening must be a substantially flat surface in normal manufacturing, and it is structurally difficult to fit the lid inside this flat inner surface. In other words, in order to close a lid on a paper container body by simply fitting it inside, it is necessary to hold the hanging part of the lid in a state in which it is pressed against the substantially flat inner wall portion of the container body. However, if the inner wall portion is a flat surface, the pressed part is slippery, and the pressed state is easily released by slight vibration or impact, causing the lid to come off. In addition, when manufacturing a paper container body, it is not possible to precisely mold it like synthetic resin, and because paper has the unique deformability, it is not possible to maintain the internal fitting of the lid like synthetic resin. Therefore, if the lid is closed by fitting the hanging portion of the lid into the container body, it is necessary to add a special structure other than the fitting, such as fixing the container body and the lid using other auxiliary fixing means such as adhesive tape.

Therefore, in the paper container 10 of the present invention, a groove-shaped fitting portion 40 is formed on the inner wall portion 24a of the paper container body 20, and a protruding fitting portion 50 is formed on the outer periphery 35a of the hanging portion 35 of the lid body 30, making it possible to close the lid by internal fitting alone, which was not possible with conventional paper containers. Here, the preferred conditions for the groove-shaped fitting portion 40 and the protruding fitting portion 50 are described in detail below.

First, the groove-shaped fitting portion 40 may be located in any position as long as it is located near the upper opening 21, which is above the top of the food contained in the paper container body 20. For example, the groove-shaped fitting portion 40 is located at a position where the distance from the upper opening 21 to the top of the fitting portion 40 is about 3 to 10 mm. If the fitting portion 40 is too close to the upper opening 21, the lid body 30 may not be able to fit properly inside, and if it is too far from the upper opening 21, there is a problem that the lid body 30 will penetrate more than necessary into the paper container body 20.

Furthermore, the convex fitting portion 50 provided on the hanging portion 35 of the lid body 30 is appropriately set according to the position of the concave groove fitting portion 40 .
Here, if the lid body 30 is made of a synthetic resin sheet molded product, there is a great deal of freedom in the shape of the lid body 30 and precise molding can be easily achieved. In addition, when the internal fitting structure of this invention is used, deformation of the convex strip fitting portion 50 of the synthetic resin sheet lid body when heated can be prevented by the partial deformability of the concave groove-like fitting portion 40 of the paper container body 20 and the overall rigidity of the container body, ensuring effective adhesion.

That is, as mentioned above, the paper container body 20 is capable of partial deformation due to the structure of the resin fibers, but has the characteristic that the surface as a whole is relatively rigid and the amount of deformation is small (particularly in the case of containers for gratin, doria, etc., the height of the peripheral wall is low, so the side wall is rigid), while the synthetic resin sheet lid 30 has the characteristic that the entire surface is more easily deformed than partial deformation, so that it has flexibility (particularly in the case of lids for gratin, doria, etc., the width of the peripheral wall is small compared to the lid surface, so the deformation of the fitting peripheral wall part is large). The difference between these two characteristics is that in the case of the conventional external fitting described above, the lid body separates from the container body, resulting in a defect that the fitting becomes loose, but in the case of the internal fitting of the present invention, on the contrary, the partial deformability of the groove-like fitting part 40 of the container body 20 and the overall rigidity of the container body firmly accept the deformation of the ridge fitting part 50 of the lid body, which has the advantage of ensuring effective adhesion.

As shown in Figures 1 and 4, the paper container body 20 and the lid 30 are configured such that the diameter D1 at the convex fitting portion 50 of the lid 30 is larger than the diameter D2 at the concave groove fitting portion 40 of the paper container body 20 (D1>D2). The diameter D1 at the convex fitting portion 50 of the lid 30 corresponds to the distance between the apexes (most protruding positions) of the convex fitting portions 50. The diameter D2 at the concave groove fitting portion 40 of the paper container body 20 corresponds to the distance between the upper inner wall portion 24c of the concave groove fitting portion 40 (the boundary portion between the concave groove fitting portion 40 and the inner wall portion 24a).

Since the diameter D1 at the convex fitting portion 50 of the lid 30 is larger than the diameter D2 at the concave groove fitting portion 40 of the paper container body 20, the convex fitting portion 50 can be properly fitted to the concave groove fitting portion 40. Also, when the apex of the convex fitting portion 50 abuts (presses) against the apex (the most recessed position) of the concave groove fitting portion 40, good adhesion is obtained between the convex fitting portion 50 and the concave groove fitting portion 40, and the fitted state can be more properly maintained. If the diameter D1 at the convex fitting portion 50 of the lid 30 is equal to or smaller than the diameter D2 at the concave groove fitting portion 40 of the paper container body 20, a problem occurs in which the convex fitting portion 50 cannot be fitted to the concave groove fitting portion 40. The upper limit of the diameter D1 of the lid 30 at the position of the convex fitting portion 50 is an appropriate distance that allows it to be pressed into the paper container body 20 and fitted into the concave fitting portion 40.

As shown in FIG. 4, the paper container body 20 and the lid 30 have a protruding length L1 of the ridge fitting portion 50 of the lid 30 that is greater than or equal to the depth L2 of the groove-like fitting portion 40 of the paper container body 20. The protruding length L1 of the ridge fitting portion 50 of the lid 30 corresponds to the distance from the outer periphery 35a of the hanging portion 35 to the apex of the ridge fitting portion 50. The depth L2 of the groove-like fitting portion 40 of the paper container body 20 corresponds to the distance from the upper inner wall portion 24c of the groove-like fitting portion 40 to the apex of the groove-like fitting portion 40.

By making the protruding length L1 of the convex-stripe fitting portion 50 of the lid body 30 equal to or greater than the depth L2 of the groove-shaped fitting portion 40 of the paper container body 20, the convex-stripe fitting portion 50 can be more reliably pressed against the groove-shaped fitting portion 40 when the convex-stripe fitting portion 50 and the groove-shaped fitting portion 40 are fitted together, and the adhesion between the convex-stripe fitting portion 50 and the groove-shaped fitting portion 40 is further improved. If the protruding length L1 of the convex-stripe fitting portion 50 of the lid body 30 is less than the depth L2 of the groove-shaped fitting portion 40 of the paper container body 20, there is a risk that sufficient adhesion between the convex-stripe fitting portion 50 and the groove-shaped fitting portion 40 cannot be obtained. In particular, if the diameter D1 of the convex-stripe fitting portion 50 of the lid body 30 at the position of the convex-stripe fitting portion 50 is too small, there is a risk that the fitting with the groove-shaped fitting portion 40 of the paper container body 20 will be released and the lid body 30 will be easily removed.

The width and depth of the groove-shaped fitting portion 40 and the width and protruding length of the ridge fitting portion 50 are not particularly limited as long as the width of the groove-shaped fitting portion 40 is equal to or less than the width of the groove-shaped fitting portion 40 and the protruding length of the ridge fitting portion 50 is equal to or greater than the depth of the groove-shaped fitting portion 40, so that the two can be properly fitted together. For example, the width of the groove-shaped fitting portion 40 is about 1.5 to 5 mm, the depth is about 0.2 to 1.0 mm, and the width of the ridge fitting portion 50 is about 1 to 4 mm, and the protruding length is about 0.2 to 1.0 mm. If the width and depth of the groove-shaped fitting portion 40 and the width and protruding length of the ridge fitting portion 50 are not appropriate, the fitting may be easily released or sufficient adhesion may not be obtained.

In the case of the paper container 10, when the hanging portion 35 of the lid 30 is inserted into the upper opening of the paper container body 20 to close the lid, as shown in FIG. 6, at least the lower side of the inner wall portion 24a between the upper opening 21 of the paper container body 20 and the groove-shaped fitting portion 40 is located inside the convex-stripe fitting portion 50 of the lid 30. When closing the lid, the convex-stripe fitting portion 50 of the lid 30 is pressed into the inner wall portion 24a of the paper container body 20, and as shown in FIG. 5, the convex-stripe fitting portion 50 reaches the groove-shaped fitting portion 40, and is fitted.

In this way, the groove-shaped fitting portion 40 is formed on the inner peripheral wall portion 24a of the paper container body 20, and the protruding fitting portion 50 is formed on the outer peripheral portion 35a of the hanging portion 35 of the lid body 30. When the lid is closed, the protruding fitting portion 50 is fitted into the groove-shaped fitting portion 40, so that the lid body 30 can be held in an internally fitted state with the paper container body 20. Therefore, the adhesion of the fitting portion between the paper container body 20 and the lid body 30 is improved, and even if steam is generated inside the container during cooking in a microwave oven, it is possible to suppress the steam from being discharged from the fitting portion. Therefore, steam is appropriately discharged from the steam hole 32 side of the lid body 30, and the vicinity of the fitting portion is not unnecessarily heated by steam, and the difficulty of holding the edge of the container body immediately after cooking is alleviated, making it easier to handle.

As described above, the paper container with lid for microwave heating food of the present invention can close the lid properly by simply fitting the lid together. This provides a strong adhesion between the paper container body and the lid, minimizing steam leakage from the fitting portion, especially during heating. It is easy to use and can greatly enhance the uses and functions of conventional paper containers, providing an advantageous paper container with lid for microwave heating food.

Reference Signs List 10 Paper container with lid for food heated in a microwave oven 20 Paper container body 21 Top opening 22 Outer rolled edge 23 Container bottom 23s Bottom paperboard 24 Container body 24a Inner wall 24b Outer wall 24c Inner wall above groove-shaped fitting 24s Body paperboard 25 Outer ridge 28 Folded portion of bottom paperboard 29 Folded portion of body paperboard 30, 30A, 30B Lid 31 Lid surface 32, 32a, 32b Steam hole 33 Concave surface 34, 34a Lid flange 35 Hanging portion 35a Outer periphery of hanging portion 40 Groove-shaped fitting 50 Convex fitting D Diameter of container body D1 Diameter at position of convex fitting D2 Diameter at the groove-shaped fitting position H Container height L1 Projection length of the protruding part L2 Depth of the groove-shaped fitting part

Claims (5)

a paper container body made of paper or a material mainly composed of paper or plant fiber, having an outer rolled edge at an upper opening, and a groove-shaped fitting portion formed on an inner peripheral wall portion near the outer rolled edge of the upper opening and running parallel to the outer rolled edge of the upper opening;
a lid body having a lid surface portion which covers the upper opening of the paper container body and has steam holes for discharging steam from within the paper container body, a lid flange portion which abuts the edge portion of the upper opening of the paper container body, and a hanging portion which is interposed between the lid surface portion and the lid flange portion and is provided around the upper opening of the paper container body so as to enter the upper opening of the paper container body, the lid flange portion extending outward from an upper end of the hanging portion, and a convex fitting portion formed on the outer periphery of the hanging portion ,
The diameter (D1) of the lid body at the position of the convex fitting portion is larger than the diameter (D2) of the groove-shaped fitting portion of the paper container body, and the protruding length (L1) of the convex fitting portion is greater than or equal to the depth (L2) of the groove-shaped fitting portion, so that when the lid is closed, the convex fitting portion is pressed against and fitted into the groove-shaped fitting portion.
A lidded paper container for heating food in a microwave oven. The paper container with lid for use in heating food in a microwave oven according to claim 1, wherein the lid is made of a synthetic resin sheet. The paper container with lid for use in heating food in a microwave oven according to claim 1 or 2, wherein the paper container body is in the shape of a deep dish or a shallow cylinder for consumption. The paper container with lid for heating food in a microwave oven according to claim 3, wherein the maximum diameter of the paper container body is 25 cm or less, and the ratio of the diameter to the container height is 2 to 5. 5. The paper container with a lid for use in heating food in a microwave oven according to claim 3 or 4, wherein the container is a gratin dish or a doria dish.

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