Lid

Abstract

To provide a lid body for a paper container having a curled opening end, the temperature of a gripping portion of which is suppressed immediately after microwave heating in a closed lid state, and which quickly lowers in temperature over time and has excellent ease of handling with bare hands from immediately after cooking to eating.SOLUTION: A lid body according to the present invention has: a top surface 21; a lid body wall surface 22 hanging from the outer edge of the top surface 21; a groove bottom part 23 extending outwardly from the lower edge of the lid body wall surface; and a fitting part 24 extending from the groove bottom part outer edge and sandwiching the side wall of the cylindrical paper container, wherein the mating part 24 has a fitting inner wall 24a, an annular fitting upper part covering a curled opening end of the container body, and a fitting outer wall 24d, in addition the annular fitting upper part intermittently has aligned convex protrusions 24c along the circumference of its annular structure, with the circumference as the long side.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a lid suitable for a microwave-safe paper container for heated processed foods such as gratin and doria. [Background technology]

[0002] In recent years, with the rise in the need for single-person meals, there has been an increasing demand for fully cooked products such as gratin and doria at supermarkets, convenience stores, etc. Such gratin and doria are usually reheated in a microwave oven to a piping hot state just before eating, so shallow, heat-resistant cup-shaped paper containers are widely used, and the lids for these containers are usually made of transparent resin.

[0003] However, because gratin and doria containers are shallow and are usually reheated to high temperatures, the edges of the lid are also quite hot when removed from the container after microwave cooking, and because the insulating properties of the paper container make it difficult to cool. This creates problems such as burns when carrying or eating the food in your hands, and the heat makes it difficult to remove the lid.

[0004] Therefore, a lid that can be easily held with one hand after heating in a microwave oven as a lid for a gratin / doria container has been known in the past, which has a finger loop formed through a groove near the outer edge of the lid and has a protrusion connected to the finger loop (see Patent Document 1).

[0005] However, the lid described in Patent Document 1 employs a so-called external fitting method in which a fitting protrusion is provided on the outer peripheral skirt portion to fit with the paper container, and the structure is such that heated steam fills the inner wall of the container body up to the top end, making it inevitable that the gripping portion will become very hot immediately after heating. Furthermore, the protrusions formed on the finger hook portion of the lid described in Patent Document 1 are small protrusions that are dot-shaped in plan view, and when heated steam enters, there is no space within the small protrusions to temperature-limit the heated steam, so ultimately the protrusions themselves will inevitably become very hot. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent Publication No. 2021-155053 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the problem that the present invention aims to solve is to provide a lid for a paper container having a curled opening end, which keeps the temperature of the handle portion low immediately after heating in a microwave oven with the lid closed, and which quickly cools down over time, making it easy to handle with bare hands from immediately after cooking until eating. [Means for solving the problem]

[0008] As a result of intensive research into solving the above-mentioned problems, the inventors have discovered that by adopting a so-called inner-outer fitting in which the fitting portion of a lid for a cylindrical paper container clamps the upper part of the inner wall and the upper part of the outer wall of the container body, and by providing convex protrusions with their long sides in the circumferential direction intermittently along the outer edge of the lid on the upper surface of the fitting portion, the temperature of the convex protrusions does not become too high immediately after cooking in a microwave oven and quickly cools down after cooking, thereby completing the present invention.

[0009] That is, the present invention provides a lid for a cylindrical paper container having an opening at the top and a curled opening edge at the top end thereof, the lid having a top surface, a lid wall hanging down from the outer edge of the top surface, a groove bottom extending outward from the lower end of the lid wall, and a fitting portion continuing from the outer edge of the groove bottom and clamping the side wall of the cylindrical paper container, The fitting portion has an inner fitting wall that extends upward from the outer edge of the groove bottom and abuts against the inner wall surface of the container, an annular fitting upper portion that covers the curled opening end, and an outer fitting wall that extends downward from the outer edge of the annular fitting upper portion and abuts against the upper outer wall of the container, and the lid body is further characterized in that the annular fitting upper portion has intermittent convex protrusions along the circumferential direction of its annular structure. [Effects of the Invention]

[0010] According to the present invention, a lid for a paper container having a curled opening end can be provided, which keeps the temperature of the handle portion low immediately after heating in a microwave oven with the lid closed, and quickly cools down over time, making it easy to handle with bare hands from immediately after cooking until eating. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a perspective view of a paper container body. [Figure 2] FIG. 2 is an end view of a cross section cut along the diameter of the paper container body in a plan view. [Figure 3] FIG. 3 is a perspective view of the lid of the present invention. [Figure 4] FIG. 4 is a plan view of the lid of the present invention. [Figure 5] FIG. 5 is a partially enlarged view of the plan view of FIG. [Figure 6] FIG. 6 is a front view of the lid of the present invention. [Figure 7] FIG. 7 is an end view of the lid of the present invention. [Figure 8] FIG. 8 is a partially enlarged view of the end face of the lid of the present invention. [Figure 9] FIG. 9 is an end view showing the end face of the fitting portion between the paper container body and the lid body. [Figure 10] FIG. 10 is a perspective view of the paper container body and the lid body in a fitted state. DETAILED DESCRIPTION OF THE INVENTION

[0012] As described above, the lid of the present invention is a lid for a paper container having an opening at the top and a curled opening end, and has a top surface, a lid wall hanging down from the outer edge of the top surface, a groove bottom extending outward from the lid wall, and a fitting portion continuing from the outer edge of the groove bottom and clamping the upper part of the side wall of the cylindrical paper container.

[0013] Here, the fitting portion that clamps the upper side wall of the paper container has a structure with a fitting method called inner-outer fitting (for example, fitting portion 24 in Figure 3), and the fitting portion has as its essential components a fitting inner wall (for example, fitting portion 24a in Figure 3) that extends upward from the outer edge of the groove bottom and abuts against the inner wall surface of the container, an annular fitting upper portion (for example, ridge-like protrusion portion 24c and non-protrusion portion 24b in Figure 3) that covers the curled opening end, and an fitting outer wall (for example, fitting outer wall 24d in Figure 3) that extends downward from the outer edge of the annular fitting upper portion and abuts against the upper outer wall of the container. In this way, by fitting the upper side wall of the paper container in a constricted shape from the inside and outside, it is possible to prevent steam from moving upward from the lower end of the fitting portion when heated in a microwave oven, and to suppress a temperature rise at the upper end of the fitting portion. The state in which the fitting portion clamps the upper part of the side wall of the paper container body can be shown, for example, in Figures 9(a) and 9(b), where Figure 9(a) is an end view taken along line AA in Figure 4 in the closed state, and Figure 9(b) is an end view taken along line BB in Figure 4 in the closed state.

[0014] The upper fitting portion is characterized in that the annular upper fitting portion has intermittent ridge projections (e.g., ridge projections 24c in FIG. 3) along the circumferential direction of the annular structure. That is, the upper fitting portion has ridge projections that are continuously arranged at equal or approximately equal intervals in the circumferential direction of the outer edge of the lid, with non-projecting portions (e.g., non-projecting portions 24b in FIG. 3) interposed therebetween.

[0015] The planar shape of the ridge projections may be substantially rectangular, elliptical, polygonal, or the like. However, in the present invention, a substantially rectangular shape with the long sides extending in the circumferential direction is preferred in order to ensure a sufficiently large space within the ridge projections and to provide excellent grip when holding the container by hand. Here, the ridge projections form an internal space of a predetermined size between themselves and the top of the wall surface of the container body. Therefore, even if heated steam passes through the fitting inner wall and reaches the internal space, the steam diffuses within the internal space, preventing a temperature rise at the gripping portion.

[0016] In order to ensure sufficient internal space, the size of the protruding ridges is preferably such that the long side of the base (length of the protruding ridge (a)) in a generally rectangular shape in plan view is 4 to 10 mm, the long side of the top end (b) is 3 to 8 mm, the short side (width of the protruding ridge (d)) in a generally rectangular shape in plan view is 0.5 to 2 mm, and the height from the base to the top end (height of the protruding ridge (h)) is 0.5 to 2 mm. Here, the height of the protruding ridge (h) from the bottom to the top end is expressed as the height (h) at which the length of the perpendicular to the line segment passing through both bottom ends of the protruding ridge in a cross-sectional view is at its maximum, as shown in FIG. 8(a). Here, FIG. 8(a) is an end view taken along line AA in FIG. 4.

[0017] The above-mentioned convex protrusions are arranged intermittently along the outer periphery of the lid of the present invention, and the length between the convex protrusions in the circumferential direction, i.e., the length of the non-protrusion portion (for example, the gap length (c) in Figure 5), is preferably 1.5 to 3 mm.

[0018] The annular fitting portion is preferably formed to minimize the gap along the shape of the curled opening edge located at the top of the container body opening. Specifically, its diameter (fitting portion width (w)) is preferably 2.5 to 5 mm. Here, the diameter width (w) of the annular fitting portion is, for example, as shown in FIG. 8(b), the length of the straight line between the intersection point x of a tangent to the fitting inner wall 24a of the annular fitting portion and a line passing horizontally through the vertex of the non-protruding portion 24b of the annular fitting portion, and the intersection point y of a perpendicular line tangent to the fitting outer wall 24d and a line passing horizontally through the vertex of the non-protruding portion 24b of the annular fitting portion. Here, FIG. 8(b) is a B-B end view of FIG. 4.

[0019] In the present invention, the convex protrusion is located on the upper surface of the lid fitting portion, but it is preferable that it is located outward from the viewpoint of preventing the intrusion of heated steam. Specifically, it is preferable that the midpoint of the width (d) of the convex protrusion is located outward from the midpoint of the width (w) of the fitting portion.

[0020] Furthermore, it is preferable that the ratio of the width (d) of the ridge projection to the width (w) of the fitting portion [(d) / (w)] is in the range of 0.15 to 0.8, as this keeps the thermal conductivity to the ridge projection low and improves the vapor diffusion effect in the space within the ridge projection.

[0021] The lower end of the fitting outer wall is further bent inward in cross section so as to enclose the upper part of the side wall of the paper container body, narrowly covering the curled edge and connecting to a skirt portion (for example, skirt portion 25a in Figure 6). Furthermore, the lower end of the skirt portion is positioned lower than the curled opening end, and the skirt portion preferably has a fitting locking portion (for example, fitting locking portion 25b in Figure 6) that protrudes inward like a convex strip to make the internal and external fitting of the lid body of the present invention stronger and to ensure a secure fit with a click when the lid body is fitted. The size of this fitting locking portion is determined by the length in the circumferential direction of the outer edge of the lid body 2 (for example, the fitting locking portion width W in Figure 6). 25b ) is preferably 20 to 60 mm.

[0022] Next, the top surface of the lid 2 (for example, top surface 21 in FIG. 3) is preferably circular or elliptical in plan view, but it is preferable to match the shape of the opening of the container body. In particular, for use as a container for single-serving doria or gratin, it is preferable to use a container body that is circular in plan view, and to use a container body that is circular in plan view, and to use a container with a top surface that is circular in plan view to match this.

[0023] In addition, it is preferable to have a thread-end-like convex rib portion (for example, thread-end-like convex rib portion 21a in Figure 3) on the periphery of the top surface, which forms a convex rib at the top along the outer periphery, as this increases the rigidity and strength of the entire lid body 2, stabilizes the fitting state, and provides a good effect in preventing the gripping portion from becoming too hot.

[0024] The height (t2) of the ridge-like ridge portion on the top surface of the lid (see FIG. 8(b)) is preferably 0.8 to 1.5 mm, as this improves the rigidity and strength of the entire lid. Furthermore, the radius of curvature Re of the ridge-like ridge portion 21a is preferably 0.4 to 0.8 mm, as this improves the strength of the entire lid and improves the stability of the fit.

[0025] Furthermore, the thread-end-like convex rib portion on the top surface of the lid may be arranged edgelessly on the outer edge of the top surface, but by forming it intermittently through missing portions 21b as shown in Figure 3, the strength of the thread-end-like convex rib portion itself is increased, and the top surface can be effectively prevented from buckling due to external forces.

[0026] The top surface preferably has steam holes for venting steam generated during cooking to the outside. The steam holes may have various shapes, such as round holes, linear elongated holes, L-shaped elongated holes, oblique lines, S-shaped elongated holes, C-shapes, U-shapes, and tongue-shaped holes. These steam holes can be formed by cutting with a press, irradiating with a laser, or irradiating with ultrasonic waves.

[0027] Among these, for use in gratin / doria containers, C-shaped, U-shaped, and tongue-shaped notched valves are preferred because they are heated to high temperatures and emit a large amount of steam, and because they prevent high-temperature steam from penetrating the peripheral edge of the lid of the present invention as much as possible and allow it to be efficiently emitted through the steam holes in the top surface. It is preferred that multiple C-shaped, U-shaped, and tongue-shaped notched valves be formed on the top surface, and specifically, it is preferred that 2 to 6 notched valves be provided in terms of steam emission efficiency.

[0028] Furthermore, when providing a C-shaped, U-shaped, or tongue-shaped notched valve, a recess one step lower than the top surface may be provided in the top surface, and the notched valve may be provided in the bottom surface of the recess, or a groove-shaped recess may be provided in the top surface, and the notched valve may be provided across the recess. Alternatively, an inverted dome shape may be formed with the lower side at the apex, and the notched valve may be provided in the groove or inverted dome.

[0029] The lid of the present invention has a lid wall (e.g., lid wall 22 in Figure 3) that hangs down outward from the periphery of the top surface, and a groove bottom (e.g., groove bottom 23 in Figure 3) that extends outward from the lower end of the lid wall, and the outer edge of the groove bottom is connected to the mating inner wall of the mating portion (e.g., mating inner wall 24a in Figure 3).

[0030] In the present invention, by positioning the groove bottom as low as possible, the height of the fitting portion can be ensured, and the fitting portion can more firmly and constrictively fit the barrel portion of the paper container body or the curled opening end. From this perspective, the height from the groove bottom to the apex of the non-projection portion 24b of the fitting portion, for example, the distance t1 from the groove bottom to the line segment horizontally passing through the apex of the non-projection portion 24b as shown in Figure 8(b), is preferably 5.5 to 10 mm.

[0031] Thus, the lid wall surface, the groove bottom, and the mating inner wall form an annular recess (e.g., annular recess R in FIG. 7). Furthermore, in the present invention, to increase the strength of the annular recess, it is preferable to provide annular ribs, each formed with a downwardly projecting ridge and a smokeless edge in the circumferential direction, on the inner and outer edge sides of the groove bottom. Such annular ribs can be represented, for example, as inner annular rib 23a and outer annular rib 23c in FIG. 3. Therefore, when such annular ribs are provided, the groove bottom structure, as shown in FIG. 3, is arranged in the following order from the contents side: inner annular rib 23a, groove bottom horizontal portion 23b, and outer annular rib 23c.

[0032] It is also preferable that the lid has an inwardly bulging recess for stacking (for example, recess 27 in FIG. 3) at the top of its wall surface. This recess is preferably formed integrally with the cutout portion (cutout portion 21b in FIG. 3) as shown in FIG.

[0033] The size of the lid 2 can be selected appropriately to match the container body, but when it is circular in plan view, the length between the mating outer walls in the diameter direction (for example, diameter W1 in FIG. 6) can be in the range of 140 to 200 mm, and the diameter of the top surface (for example, diameter W2 in FIG. 6) can be in the range of 100 to 170 mm. Furthermore, the width in the height direction of the lid 2 (for example, height T1 in FIG. 6) is preferably in the range of 11 to 60 mm.

[0034] When the lid body 2 is elliptical in plan view, the length between the mating outer walls in the diameter direction is preferably 150 to 300 mm in the long diameter direction and 100 to 200 mm in the short diameter direction, and the width in the height direction of the lid body 2 (for example, height T1 in Figure 6) is preferably in the range of 11 to 60 mm.

[0035] The lid can be made of a synthetic resin sheet such as polystyrene, polypropylene, polyethylene or other polyolefin, which has heat resistance and can be used in a microwave oven.

[0036] Furthermore, the sheet material may be a sheet in which an inorganic substance is dispersed in the aforementioned synthetic resin, or an oriented sheet obtained by oriented the aforementioned sheet, etc. Among these, oriented sheets obtained by uniaxially or biaxially oriented polystyrene, polypropylene, etc. are particularly preferred because they have the heat resistance required for microwave heating, and oriented polypropylene sheets are particularly preferred because they have excellent oil resistance and heat resistance, good moldability, and the formation of cut valves is easy.

[0037] The paper container body 1 used in the present invention is a paper container body having an opening at the top, a curled opening end with its upper edge curled outward, a body, and a bottom as essential components. The planar shape of the opening is circular or elliptical, just like the lid, and can be selected appropriately depending on the contents to be stored. The paper container body 1 can store a variety of foods, such as gratin, doria, pasta, curry, pilaf, pho, soup, and prepared dishes. However, a circular shape is preferable, especially when used as a container for single-serving gratin or doria.

[0038] Furthermore, since thin containers are the mainstream for gratin and doria, a shallow cylindrical container is preferable.

[0039] Here, the curled opening end located at the opening of the paper container body 1 has a shape that is curled outward, and may be partially curled, or semi-rolled, or may be curled outward one or more times, but a shape that is curled outward one or more times is preferred, as this increases the rigidity of the curled opening end itself, ensures the fitting strength when the lid is fitted, and effectively prevents heated steam from entering the fitting portion.

[0040] The body portion continuing from the curled opening end is preferably formed into a cylindrical shape, and its inner surface is preferably laminated with an oil-resistant film. In this case, the laminate film is preferably laminated onto a paper substrate and used for container formation, and therefore, it is preferably laminated continuously onto the surface of the curled opening end.

[0041] The bottom of the paper container body 1 has a shape that forms a bottom similar to the shape of the opening. Here, it is preferable that the inner diameter of the opening of the paper container body 1 is slightly wider than the diameter of the bottom, as this provides excellent container strength and makes it easier to grip after cooking. Specifically, the ratio of the opening inner diameter (D12) to the bottom diameter (D11) [(D12) / (D11)] is preferably in the range of 1.01 to 1.2. In other words, the body is preferably an inverted truncated cone shape that widens upward. The opening inner diameter (D12) refers to the length of a line segment connecting the straight line of the wall surface in the cross section of the paper container 1 to the inflection point that continues to the curled opening end in the diameter direction.

[0042] As mentioned above, the paper container body 1 is preferably a shallow cylindrical container, and in this case, the ratio of the bottom diameter (D11) to the height (H12) [(H12) / (D11)] is preferably 0.2 to 0.6. Furthermore, in the present invention, it is preferable that the bottom 11 of the paper container body 1 is configured as an upper bottom from the viewpoint of heating efficiency during microwave cooking, and in this case, it is preferable that the ratio of the height (H11) of the upper bottom to the height (H12) of the paper container body 1 [(H11) / (H12)] ​​is in the range of 0.1 to 0.3.

[0043] The paper container body 1 may also be a bottomless paper cylinder with a curled opening end and a body, with a bottomed resin inner container that covers the inside fitted to the curled opening end.

[0044] <Implementation> This embodiment uses a cylindrical paper container body 1 shown in Figure 1 as the container body, and essential components include a bottom 11, a body 12, and a curled opening end 13. Here, the body 12 has an inverted truncated cone shape that expands upward as shown in Figure 2, and is folded, with the ratio [(D12) / (D11)] of the opening inner diameter (D12) to the bottom diameter (D11) being 1.05. Furthermore, as shown in Figure 9, the curled opening end 13 has an outwardly curled shape that wraps around more than once. Furthermore, the bottom 11 is formed in an upside-down shape as shown in Figure 2, and the ratio [(H11) / (H12)] ​​of the bottom 11 to the height (H12) of the paper container body 1 is 0.15.

[0045] Next, as shown in Fig. 3, the lid 2 has a top surface 21, a lid wall surface 22 hanging down from the outer edge of the top surface 21, a groove bottom 23 extending outward from the lower end of the lid wall surface, and a fitting portion 24 continuing from the outer edge of the groove bottom 23 and clamping the side wall of the cylindrical paper container. The fitting portion 24 has a fitting inner wall 24a extending upward from the outer edge of the groove bottom and abutting the inner wall surface of the container, an annular fitting upper portion covering the curled opening end, and a fitting outer wall 24d extending downward from the outer edge of the annular fitting upper portion and abutting the upper part of the outer wall of the container. In other words, as shown in Fig. 9, the curled opening end of the paper container body 1 has a structure in which the fitting portion 24 fits from the inside and outside, thereby exhibiting excellent fitting strength and effectively preventing the intrusion of heated steam from the contents into the vicinity of the curled opening end during cooking. 7, the lid wall surface 22, the groove bottom 23, and the fitting inner wall 24b form an annular recess R, and by making this recess deep enough, the height of the fitting portion 24 increases, effectively preventing the intrusion of heated steam into the vicinity of the curled opening end. For this reason, in this embodiment, the fitting portion height (t1) in FIG. 8(b) is 7.7 mm. Furthermore, the annular fitting upper portion has elongated ridges 24c that are arranged intermittently along the circumferential direction of the annular structure.

[0046] In this embodiment, the ridge-like projection is generally rectangular in plan view, with a long base side (ridge-like projection length (a)) of 3 mm, a long top side (b) of 5 mm, and a short side (ridge-like projection width (d)) of 1 mm in plan view. The height from the base to the top (ridge-like projection height (h)) is 1 mm.

[0047] The protruding ridges are arranged at equal intervals in the circumferential direction, and the length between two protruding ridges, that is, the length of the non-protruding portion 24b (gap length (c) in FIG. 5) is 2.3 mm.

[0048] The annular fitting portion has a width in the diameter direction (fitting portion width (w)) of 3.6 mm.

[0049] In the present invention, as described above, the convex protrusion is located on the upper surface of the lid fitting portion, but it is preferable to position it as far outward as possible from the viewpoint of preventing the intrusion of heated steam. In this embodiment, the midpoint of the convex protrusion width (d) is located outside the midpoint of the fitting portion width (w), and further, the ratio of the convex protrusion width (d) to the fitting portion width (w) [(d) / (w)] is 0.28.

[0050] The lower end of the fitting outer wall 24d further encloses the upper part of the side wall of the paper container body, more specifically, the lower end is positioned lower than the curled opening end, bends inward in cross section, covers the curled edge in a narrowed shape, and connects to the skirt part 25a. The skirt part has a fitting locking part 25b that protrudes inward like a convex strip to make the internal and external fitting of the lid body of the present invention stronger and to ensure a secure attachment with a click feeling when the lid body is fitted. Such fitting locking part 25b has a fitting locking part width W in the circumferential direction of the outer edge of the lid body 2. 25b are arranged at 40 mm.

[0051] To prevent cuts when touching the hand, the skirt end (skirt end 26 in Figs. 3, 8 and 9) has a continuous fine uneven shape (not shown).

[0052] In addition, the outer edge of the top surface 21 is formed with butt-shaped ridges 21a intermittently via cutouts 21b. This increases the strength of the butt-shaped ridges themselves, effectively preventing the top surface 21 from buckling due to external force. In this embodiment, the cutouts 21b are formed integrally with the stack recess 27. Here, the height (t2) of the butt-shaped ridge portion 21a is 1 mm, and the radius of curvature Re thereof is 0.6 mm.

[0053] In this embodiment, the steam vents 30 formed on the top surface are provided with four C-shaped notched valves as shown in FIG.

[0054] Furthermore, in this embodiment, the groove bottom 23 has downwardly projecting annular ribs formed with smokeless ends in the circumferential direction on both the inner and outer edges of the groove bottom 23. As shown in Fig. 3, the inner annular rib can be represented as the inner annular rib 23a, and the outer annular rib 23c. The groove bottom has a structure in which, from the content side, the inner annular rib 23a, the groove bottom horizontal portion 23b, and the outer annular rib 23c are arranged in this order, as shown in the end views of Figs. 8 and 9.

[0055] In this embodiment, the above-mentioned lid body 2 can be obtained by molding oriented polypropylene.

[0056] The state in which the paper container body 1 and lid 2 are fitted together can be shown in the perspective view of Fig. 10, and as shown in Fig. 9(a), which is the AA cross section of Fig. 4, and Fig. 9(b), which is the BB cross section, the fitting portions 24a and 24d of the lid 2 are in tight contact with the curled opening end 13. Furthermore, the convex protrusion 24c forms a gap between itself and the upper end of the curled opening end 13, which contributes to mitigating the temperature of the heated steam. [Example]

[0057] EXAMPLES The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to these examples.

[0058] Example 1 A paper container shown in Fig. 1 and a lid body shown in Fig. 3 obtained by molding an oriented polypropylene sheet were prepared. These paper containers and lid body have the shapes shown in the above embodiment. Next, the test doria food was placed in the paper container, and the lid was closed and fitted. In this case, it was confirmed that skilled operators could close the lid securely due to the clicking sensation when closing it. Next, it was heated in a 1500W microwave oven for 70 seconds, and the surface temperatures of the ridge projections 24c and the skirt end 26 were measured with a thermometer immediately after heating. Furthermore, the surface temperatures of 24c and 27 were measured 30 seconds and 60 seconds after the end of heating. The results are shown in Table 1.

[0059] Comparative Example 1 A lid having the same shape as the above embodiment, except that it did not have the ridge protrusion 24c on the upper fitting portion, was used, and a heating test was conducted in the same manner as in Example 1. The surface temperatures of the upper fitting portion and the end of the skirt were measured immediately after heating, 30 seconds after heating, and 60 seconds after heating was completed. The results are shown in Table 1.

[0060] [Table 1]

[0061] From the above results, it can be seen that when cooking in a microwave oven using the lid of the present invention, the temperature of the upper part of the fitting portion is suppressed immediately after heating, and the temperature subsequently drops rapidly. Also, the temperature rise at the end of the skirt is suppressed immediately after heating, and the temperature then drops rapidly. [Explanation of symbols]

[0062] 1: Paper container body 11: Bottom 12: Torso 13: Curled opening end 2: Lid 21: Top 21a: Thread tail-like convex stripe 21b: Defective part 22: Lid wall 23: Groove bottom 23a: Inner edge annular rib 23b: Groove bottom horizontal part 23c: Outer edge annular rib 24: Fitting part 24a: Fitting inner wall 24b: Non-protruding part 24c: Convex protrusion 24d: Fitting exterior wall 25a: Skirt section 25b: Fitting locking part 26: Skirt end 27: Stack recess 30: Steam vent a: Length of the ridge b: Circumferential length of non-convex ridge portion c: Gap length d: Protrusion width t1: Fitting height t2: Height of the thread-tail-like convex part T1: Lid height h: Height of the ridge R: Annular recess w: Fitting width W 25b: Fitting lock width W1: Length between mating outer walls W2: Top diameter

Claims

1. A lid for a cylindrical paper container having an opening at the top and a curled opening edge at the top, The container has a top surface, a lid wall surface hanging down from the outer edge of the top surface, a groove bottom portion extending outward from the lower end of the lid wall surface, and a fitting portion continuing from the outer edge of the groove bottom portion and clamping the side wall of the cylindrical paper container, the fitting portion has a fitting inner wall extending upward from the outer edge of the groove bottom portion and abutting against the inner wall surface of the container, an annular fitting upper portion covering the curled opening end, and a fitting outer wall extending downward from the outer edge of the annular fitting upper portion and abutting against the upper portion of the outer wall of the container, the annular fitting upper portion has a shape in which convex ridge protrusions and non-convex ridge portions are alternately arranged along the circumferential direction in a plan view, the center of the width (d) of the convex ridge protrusion is located outward from the center of the width (w) of the annular fitting upper portion, and the portion of the annular fitting upper portion that is more inward than the convex ridge protrusion in plan view is a non-convex ridge portion; The non-protruding portion is continuous with the fitting inner wall and the fitting outer wall, and has a shape that follows the curled opening end and abuts against the curled opening end.

2. The lid according to claim 1 , wherein the ridge projection has a generally trapezoidal shape in a circumferential cross section and a generally rectangular shape in a plan view.

3. A lid body as described in claim 1 or 2, wherein the bottom of the groove has annular ribs on its inner and outer edges that are convex downward.

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