Microwave paper cups

Abstract

To provide a paper cup for microwave oven which can facilitate processing of a bottom rim part, while being suitable for microwave oven heating.SOLUTION: A paper cup 1 for microwave oven at least includes a trunk member 15 formed in a cylindrical shape, and a bottom member 25 comprising a bent part in which an outer peripheral edge part is folded and a bottom surface part 22. A bottom rim part 31 is folded inside which is formed by sandwiching the bent part of the bottom member 25 between a folding part in which a lower end part of the trunk member 15 is folded and the trunk member 15 which is not folded. There is an interval at the bottom rim part 31 and the bottom surface part 22. The interval becomes larger as it goes from the upper side of the bottom rim part 31 toward the lower side, and the interval is the largest at a tip of the bottom rim part 31.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to microwave-safe paper cups (paper containers). The term "microwave-safe" does not mean that the product is exclusively for microwave use, but rather that it is suitable for use in microwave heating. [Background technology]

[0002] Paper cups are widely used as containers for instant foods, confectionery, beverages, and prepared meals. Sometimes, these paper cups, containing their contents such as food or beverages, are heated in a microwave oven, either directly in the cup or after being transferred to the cup.

[0003] When a paper cup containing food is heated or cooked in a microwave oven, there is a risk of charring occurring at the bottom of the cup where the body and bottom parts of the paper cup are joined. In particular, the heat generated is high at the joint where the paper overlaps (heat dissipation is not high), so heat tends to accumulate there, making charring more likely.

[0004] Conventionally, the technologies disclosed in Patent Documents 1 and 2 describe paper cups that can be used for microwave heating (hereinafter referred to as microwave paper cups). These microwave paper cups do not scorch at the base of the cup when heated in a microwave oven.

[0005] The bottom of the cup is stiff and difficult to bend because it is made up of two or more sheets joined together. In the microwave paper cup described in Patent Document 1, the base of the cup is significantly folded. Furthermore, in the microwave paper cup described in Patent Document 2, the base of the cup is significantly folded and then folded until it touches the bottom. In the microwave paper cups described in Patent Documents 1 and 2, the bottom edge is positioned closer to the bottom surface to prevent burning of the bottom edge during microwave heating. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2002-345639 [Patent Document 2] Japanese Patent Publication No. 2014-227221 [Overview of the initiative] [Problems that the invention aims to solve]

[0007] However, with the aforementioned microwaveable paper cups, the process of bending the stiff base significantly can be difficult, potentially increasing the processing time.

[0008] This disclosure was made to solve the above-mentioned problems, and the objective is to provide a microwave-safe paper cup that is suitable for microwave heating while also being easy to process at the base. [Means for solving the problem]

[0009] The above-mentioned problems can be solved by the following embodiments of this disclosure. In other words, the microwave paper cup 1 of this disclosure is A body member 15 formed in at least a cylindrical shape, A bottom member 25 consisting of a bent portion with a folded outer edge and a bottom surface portion 22, The bent portion of the bottom member 25 is formed by sandwiching and joining the folded portion where the lower end of the body member 15 is folded back with the unfolded body member 15, and the thread tail portion 31 is bent inward. A gap is provided between the thread tail portion 31 and the bottom portion 22. As you move from the upper side to the lower side of the thread tail portion 31, the gap increases. The gap is largest at the tip of the thread tail portion 31.

[0010] Furthermore, the microwave paper cup 1 of this disclosure is The string end portion 31, which is cut by a plane passing through the vertical line Z of the microwave paper cup 1, may be in a straight line.

[0011] Furthermore, the microwave paper cup 1 of this disclosure is The length L of the bent thread end portion 31 is 5 mm or more and 6 mm or less. The folding angle θ1 formed by the thread end portion 31 and the horizontal plane X perpendicular to the vertical line Z of the microwave paper cup 1 may be 60° or less in the plane passing through the vertical line Z of the microwave paper cup 1.

[0012] Furthermore, the microwave paper cup 1 of this disclosure is The length L of the bent thread end portion 31 is 7.5 mm or more and 8.5 mm or less. The folding angle θ1 formed by the thread end portion 31 and the horizontal plane X perpendicular to the vertical line Z of the microwave paper cup 1 may be 50° or less in the plane passing through the vertical line Z of the microwave paper cup 1.

[0013] Furthermore, the microwave paper cup 1 of this disclosure is The length L of the bent thread end portion 31 is 5 mm or more and 8.5 mm or less. The folding angle θ1 formed by the thread end portion 31 and the horizontal plane X perpendicular to the vertical line Z of the microwave paper cup 1 may be 50° or less in the plane passing through the vertical line Z of the microwave paper cup 1. [Effects of the Invention]

[0014] According to the embodiments of the present disclosure described above, it is possible to provide a microwave-safe paper cup 1 that is suitable for microwave heating while also being easy to process the threaded end portion 31. Because the threaded end portion 31 is easy to process, the processing work becomes simpler and the processing time is shortened, which contributes to reducing the manufacturing cost of the microwave-safe paper cup 1. In the present specification, microwave heating suitability refers to the property that, when the microwaveable paper cup 1 containing contents is cooked in a microwave, no charring that carries a risk of ignition or smoke generation occurs at the curled bottom portion 31. [Brief Description of the Drawings]

[0015] [Figure 1] It is a partial cross-sectional front view of the paper cup according to the first aspect of the first embodiment of the present disclosure. [Figure 2] It is an enlarged view of part A in FIG. 1. [Figure 3] It is the paper cup before processing the curled bottom portion. [Figure 4] It is an inverted perspective view of the paper cup shown in FIG. 1. [Figure 5] It is a bottom view of the paper cup shown in FIG. 4. [Figure 6] It is an inverted perspective view of the paper cup according to the second aspect of the first embodiment of the present disclosure. [Figure 7] It is a bottom view of the paper cup shown in FIG. 6. [Figure 8] It is a bottom view of the paper cup according to the third aspect of the first embodiment of the present disclosure. [Figure 9] It is a partial cross-sectional front view of the paper cup (insulated paper cup) according to the first aspect of the second embodiment of the present disclosure. [Figure 10] It is a partial cross-sectional front view of the paper cup (insulated paper cup) according to the second aspect of the second embodiment of the present disclosure. [Mode for Carrying Out the Invention]

[0016] The present embodiment will be described below with reference to the drawings. FIGS. 1 to 10 are diagrams showing the present embodiment. Each of the drawings shown below is a schematic diagram. Therefore, the size and shape of each part are appropriately exaggerated for ease of understanding. Also, modifications can be made as appropriate without departing from the technical concept of the present invention. In the figures shown below, the same parts are denoted by the same reference numerals, and some detailed explanations may be omitted. Furthermore, the numerical values ​​such as dimensions and material names of each component described in this specification are examples of embodiments and are not limited to them; they can be selected and used as appropriate. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and perpendicular, are used not only in their strict sense but also to include substantially the same conditions.

[0017] In this specification, "upper" and "lower" refer to the top and bottom of the paper cup when it is in an upright position (Figure 1), respectively. Also, in this specification, "upper side" and "upward" refer to the "upper" direction as described above, and "lower side" and "downward" refer to the "downward" direction as described above. Furthermore, in this specification, "inside" and "inner surface" refer to the side facing the contents, while "outside" and "outer surface" refer to the outside of the paper cup, the side that does not come into contact with the contents. In addition, for elements that do not come into contact with the contents, such as the bottom edge described later, "inside" and "inner surface" refer to the side of the paper cup that is aligned with the center line (vertical line), while "outside" and "outer surface" refer to the side opposite the center line (vertical line) of the paper cup.

[0018] ≪First aspect of the first embodiment≫ In the microwave oven paper cup 1 of this embodiment, a partial cross-sectional front view showing a partial cross-section is shown in Figure 1, and an enlarged view of part A in Figure 1 is shown in Figure 2.

[0019] The microwave paper cup 1 in this embodiment consists of a top curl portion 13, a body portion 11, and a bottom portion 21, in order from the top. The bottom portion 21 includes a threaded tail portion 31. The threaded tail portion 31 is formed when the lower end of the body member 15 is folded inward, and the bent portion of the outer edge of the bottom member 25 is sandwiched in the gap between the folded portion of the body member 15 and the unfolded portion of the body member 15, and joined together.

[0020] In typical paper cups, the outer surface of the base is smoothly connected to the body and forms a single surface. This surface is curved in paper cups where the body has a circular cross-section, but partially flat when the body has a polygonal cross-section.

[0021] The top curl portion 13 is generally formed by the upper end of the body member 15 being bent (curled) outward, as shown in Figure 1. The top curl portion 13 curves downward, then toward the body 11, and then curves (curls) further upward. Depending on the intended use of the microwave paper cup 1, the top curl portion 13 may be omitted.

[0022] In this embodiment of the microwave paper cup 1, the bottom edge 31 is folded inward. Figure 1 shows a vertical line Z and a horizontal plane X. The vertical line Z is a line that passes through the center of the cross-section of the body 11 of the microwave paper cup 1 and is perpendicular to the cross-section. The horizontal plane X is a plane perpendicular to the vertical line Z. Although some distortion is expected during the manufacturing of the microwave paper cup 1, the horizontal plane X may be considered to be a plane approximately parallel to the bottom surface 22 of the bottom member 25. Also, the vertical line Z may be considered to be a vertical line passing through the center of the bottom surface 22 of the microwave paper cup 1.

[0023] The bending angle θ1 shown in Figure 2 is the angle formed by the horizontal plane X and the thread butt portion 31. The outer surface of the thread butt portion 31 may be used as the reference point for the angle, or the center line in the width direction of the thread butt portion 31 may be used as the reference point for the angle. The thread butt portion length L is the length from the boundary between the body portion 11 and the bottom portion 21, in this case the bending portion 16, to the tip of the thread butt portion 31. If the bending portion 16 is a curved shape with a large radius of curvature, the starting point on the upper side of the curve may be used as the upper starting point of the thread butt portion length L.

[0024] Paper cups often have a roughly inverted truncated cone shape, and the angle between the edge of the body 11 and the vertical line Z is the body angle θ2. When calculating the angle, the vertical line Z may be considered as having been translated. The body angle θ2 may be measured, or the diameter of the cross-section of the body 11 may be measured at multiple points in the vertical direction and calculated from the measurement data. The angle between the body 11 and the tail end 31 (body-tail end angle) θ3 may be determined by measurement, or it may be calculated in the same way as the body angle θ2. The folding angle θ1 can also be calculated using the following formula. θ1 = 90 - (θ2 + θ3)

[0025] The angles are calculated using the cross-section of microwave paper cup 1, which is cut by a plane passing through vertical line Z. If actual cutting is not performed, the calculation may be performed using an assumed cross-section.

[0026] This disclosure presents a microwave-safe paper cup 1 in which the thread end portion 31 does not burn when heated in a microwave oven, by appropriately setting the thread end portion length L and the bending angle θ1 in combination.

[0027] In the prior art, microwave paper cups with a foldable tail end were folded until the tail end was approximately horizontal. When this was considered as the folding angle θ1 as defined in this disclosure, θ1 was 0° or an angle close to it (including negative angles, i.e., angles where the tip of the tail end was upward from horizontal). In this case, because the tail end, where three material sheets constituting the paper cup are joined together, is rigid, bending the tail end required considerable force and advanced technology. Consequently, the production of microwave paper cups in the prior art required processing time, resulting in poor production efficiency.

[0028] In this embodiment, the microwaveable paper cup 1 is suitable for microwave heating even if the base portion 31 is not strongly (largely) folded. That is, there may be a space between the base portion 31 and the bottom portion 22. When the base portion 31 is folded, it is folded at the folded portion 16 near the upper end of the base portion 31. A gap is provided between the base portion 31 and the bottom portion 22, and this gap increases from the top to the bottom of the base portion 31. Furthermore, this gap is largest at the tip of the base portion 31. Furthermore, the shape of the thread end portion 31, from which the bent portion 16 has been removed, when cut by a plane passing through the vertical line Z may be straight. Alternatively, it may be curved, in which case it may be a curve with the outer (lower) side convex. moreover,

[0029] In this embodiment of the microwaveable paper cup 1, the threaded end portion 31 is not strongly (largely) folded, that is, even if the folding angle θ1 is not close to θ1 = 0°, it is still suitable for microwave heating. In other words, the tip of the threaded end portion 31 does not need to be located near the bottom portion 22, so the vertical distance between the bottom portion 22 and the threaded end portion 31 may gradually increase as you move downwards (inwards) towards the bottom of the threaded end portion 31. Near the bottom of the folded portion 16, the distance is small, and at the tip of the threaded end portion 31, the distance is maximum.

[0030] Folding the thread end portion 31 along its entire length or at multiple points in the vertical direction is difficult due to the rigidity of the thread end portion 31, resulting in slower processing speeds and reduced production efficiency. Therefore, the number of folding points in the thread end portion 31 may be reduced. In the cross-sectional view shown in Figure 2, the thread end portion 31 may be folded at only one folding point 16, while the rest of the thread end portion 31 remains straight. This reduces the effort required for folding the thread end portion 31. Note that although Figure 2 shows only one folding point 16, in the microwave paper cup 1, the folding points 16 exist circumferentially when viewed three-dimensionally.

[0031] In this embodiment of the microwaveable paper cup 1, the numerical values ​​of the combination of the thread end length L and the folding angle θ1, and the suitability for microwave heating will be explained. The thread butt length L may be 0.5 mm shorter or 0.5 mm longer than the designed length, with the designed length being the central value. Within this range, performance will not be affected and will be treated as within the normal range.

[0032] In the microwave oven paper cup 1 of this embodiment, if the length L of the thread end is 5 mm or more and 6 mm or less, then the cup is suitable for microwave heating if the folding angle θ1 is 60° or less.

[0033] Furthermore, in the microwaveable paper cup 1 of this embodiment, if the length L of the thread end is 7.5 mm or more and 8.5 mm or less, then the cup is suitable for microwave heating if the folding angle θ1 is 50° or less.

[0034] Furthermore, the longer the length L of the thread end, the greater the heat generated at the thread end 31 during microwave heating. Additionally, the thread end 31 is further away from the bottom surface 22, making it more prone to charring. Therefore, the shorter the length L of the thread end, the better suited it is for microwave heating. However, the thread butt portion 31 needs to be sufficiently airtight to prevent leakage of the contents (especially liquids). For this reason, it is desirable that the thread butt length L be 5 mm or more.

[0035] To summarize the above, in the microwave-safe paper cup 1 of this embodiment, if the length L of the thread end is 5 mm or more and 8.5 mm or less, then the cup is suitable for microwave heating if the folding angle θ1 is 50° or less.

[0036] The procedure for manufacturing microwaveable paper cups 1 will be described below. First, a paper cup 5 before processing the threaded end portion 31, as shown in Figure 3 (hereinafter referred to as "pre-processed paper cup 5"), is manufactured using a known method. In Figure 3, the pre-processed paper cup 5 is shown upside down with the bottom portion 22 facing upwards. This is to make it easier to explain the processing procedure for the bottom portion 22; in actual processing, the pre-processed paper cup 5 may be upright, upside down, or on its side.

[0037] When explaining the procedure for making the microwaveable paper cup 1, the upright microwaveable paper cup 1 shown in Figure 1 will be used as the reference point for indicating each direction and position. For example, in Figure 5, the bottom portion 22 is the upper side of the paper cup, but since the upright unprocessed paper cup 5 is used as the reference, the bottom portion 22 side will be the lower side of the unprocessed paper cup 5.

[0038] As shown in Figure 1, the thread butt portion 31 is folded inward. As the thread butt portion 31 moves downward, the circumference of the shape cut by its horizontal plane X (hereinafter referred to as the horizontal cross-sectional shape of the thread butt portion 31) decreases. In this embodiment, the horizontal cross-sectional shape of the thread butt portion 31 is circular, but it may also be a square or an ellipse. If it is not circular, such as a square, replace the circumference with the perimeter.

[0039] For the circumference of the horizontal cross-sectional shape of the thread end portion 31 to decrease, it must be smaller than the circumference of the same location on the thread end portion 31 of the paper cup 5 before processing, and the material sheet constituting the thread end portion 31 at that location undergoes appropriate shrinkage deformation. In this embodiment, multiple vertical lines 32 are provided on the thread end portion 31, and these vertical lines 32 deform into a concave shape when viewed from the outside (bottom). Because the material sheet deforms into a concave shape, the excess material sheet is absorbed by the vertical lines 32. As a result, the area of ​​each part of the thread end portion 31, as viewed from the outside, undergoes shrinkage deformation, the thread end portion 31 is appropriately folded inward.

[0040] The vertical lines 32 may be provided when the thread end portion 31 is folded. A thread end processing die (not shown) having a projection corresponding to the shape of the vertical lines 32 is prepared, and the die is pressed against the thread end portion 31 from the bottom of the paper cup 5 before processing. The projection then contacts the tip of the thread end portion 31, and the contact position gradually moves upward towards the top of the thread end portion 31. As the thread end processing die moves further upward, the base portion of the thread end processing die, which is the part other than the projection, comes into contact with the area of ​​the thread end portion 31 other than the vertical lines 32. The thread end processing die then rises to a predetermined position and stops. The thread end portion 31 of the desired shape is then completed.

[0041] Furthermore, the vertical lines 32 may be provided in the blank state before the paper cup 5 is made. Alternatively, they may be provided when the thread end portion 31 of the paper cup 5 is formed. The thread end portion 31 is made by stacking and joining three material sheets, and the vertical lines 32 may be processed by a pressure and joining component (not shown) when they are joined.

[0042] <Second aspect of the first embodiment> This embodiment differs from the first embodiment in that, when the thread end portion 31 is bent, the material sheet constituting that portion of the thread end portion 31 deforms appropriately to shrink. This embodiment will be described with reference to Figures 6 and 7. In this embodiment, the tail portion 31 may be divided into multiple sections in the circumferential direction, with concave portions 34 and convex portions 35 alternating. The boundary between the concave portions 34 and the convex portions 35 is a stepped line 33.

[0043] The concave portion 34 is concave when viewed from below on the folded thread end portion 31. That is, it is located above the convex portion 35. Conversely, the convex portion 35 is convex when viewed from below on the folded thread end portion 31. That is, it is located below the concave portion 34. The stepped line 33 connects the concave portion 34 and the convex portion 35, and the material sheet in the area of ​​the stepped line 33 is deformed to stretch in the direction of the front and back sides of the material sheet of the paper cup. Therefore, the material sheet in the part before the thread end portion 31 is processed was a smooth cylindrical shape (side surface of an inverted truncated cone) before deformation. However, when the thread end portion 31 is folded and deformed to reduce its size, it deforms into a concave portion 34, a stepped scribed line 33, and a convex portion 35. As a result, the length of the material sheet in the cross-section of the thread end portion 31 increases, and the excess material sheet is absorbed. This makes the folding process of the thread end portion 31 easier.

[0044] The concave portion 34, the convex portion 35, and the stepped crease line 33 may be provided when processing the thread end portion 31. A thread end processing die (not shown) having stepped portions corresponding to the shapes of the concave portion 34, the convex portion 35, and the stepped crease line 33 is prepared, and the thread end processing die is pressed against the thread end portion 31 from the bottom of the paper cup 5 before processing. The projection of the thread end processing die corresponding to the concave portion 34 then contacts the tip of the thread end portion 31, and the contact position gradually moves upward toward the top of the thread end portion 31. As the thread end processing die moves further upward, the recess of the thread end processing die corresponding to the convex portion 35 comes into contact with the area of ​​the convex portion 35 of the thread end portion 31. The thread end processing die then rises to a predetermined position and stops. The thread end portion 31 of the desired shape is then completed.

[0045] The stepped crease line 33 may be provided in the blank state before the paper cup 5 is made. Alternatively, it may be provided when the thread end portion 31 of the paper cup 5 is formed. The thread end portion 31 is made by stacking and joining three material sheets, and the stepped crease line 33 may be processed by a pressure-applying and joining component (not shown) when they are joined.

[0046] <Third aspect of the first embodiment> A third embodiment is shown in which, when the thread end portion 31 is bent, the material sheet constituting the thread end portion 31 at that point deforms to shrink appropriately. This will be explained with reference to Figure 8. In this embodiment, there are no ruled lines such as vertical ruled lines 32 or stepped ruled lines 33, nor are there any other means (processing) to assist in the folding process.

[0047] A die for processing the thread end (not shown) that does not have any protrusions for processing the creasing lines is prepared, and the die for processing the thread end is pressed against the thread end portion 31 from the bottom of the paper cup 5 before processing. The die for processing the thread end has a shape that corresponds to the folded thread end portion 31. The thread butt processing die rises and contacts the tip of the thread butt portion 31, and then the contact position gradually moves upward towards the top of the thread butt portion 31. The thread butt processing die moves further upward until it reaches a predetermined position and stops. Then the thread butt portion 31 with the desired shape is completed.

[0048] In this embodiment, since no creases or other markings are provided, the thread butt portion 31 bends irregularly. A crease may also form as a result. Furthermore, unlike the first and second embodiments of this embodiment, there is no processing (such as crease processing) that makes the thread butt portion 31 more easily deformable, so the thrust required to press the thread butt processing die against the thread butt portion 31 for processing becomes greater. Nevertheless, processing of the thread butt portion 31 is still possible, the structure of the thread butt processing die is simplified, and the parts cost of the thread butt processing die is reduced.

[0049] When the thread butt portion 31 is bent, a lubricant may be applied to the part of the thread butt processing die that comes into contact with the thread butt portion 31. This reduces the thrust required to process the thread butt portion 31, making processing easier. This is particularly effective in the third embodiment. Liquid paraffin or water-soluble silicone agents may be used as the lubricant. Alternatively, the surface of the thread butt processing die may be subjected to friction-reducing treatment (for example, a surface treatment including a fluororesin), and this may be used in combination with a lubricant.

[0050] Alternatively, the thread butt processing die may be made from an ultrasonic horn, and the ultrasonic frequency may be 15 kHz or higher and 30 kHz or lower. By pressing the vibrated thread butt processing die against the thread butt portion 31, the thrust force of the thread butt processing die can be reduced, and the processing time can be shortened.

[0051] The material sheets for the paper cup will be described below. The body member 15 and the bottom member 25 may use material sheets with the same layer structure, or they may use material sheets with different structures. The material sheet has at least paper as the base material (paper base material) and a thermoplastic resin as the innermost layer. Considering the suitability for paper cup processing, for example, cup base paper is mainly used from the viewpoint of suitability for processing the top curl portion 13, hygiene, strength against bending and pulling, and printability when printing on the surface of the paper base material, and its basis weight is 120 g / m². 2 More than 400g / m 2 The following is preferable. More preferably, 170 g / m². 2 More than 300g / m 2 Within the following range, there is a good balance between the strength of the molded paper cup, the ease of processing the paper cup, and the cost.

[0052] The innermost thermoplastic resin must protect the contents, especially preventing leakage even when filled with liquid. Furthermore, the body member 15 must be bonded together in a cylindrical shape by heat sealing, and the bottom 21 must be formed by joining the body member 15 and the bottom member 25, thus providing airtight sealing performance. Examples of thermoplastic resins include polyethylene, polypropylene, and ethylene-vinyl acetate copolymers. Plant-derived resins may also be used, such as biomass polyethylene or biomass polypropylene. Using these resins contributes to carbon neutrality and is environmentally friendly.

[0053] A thermoplastic resin layer may be provided on the outermost layer of the material sheet. This outermost thermoplastic resin layer stabilizes the bonding by making the bonding interface of the cylindrical seal of the body member 15 thermoplastic resin to thermoplastic resin. Furthermore, it prevents external moisture such as condensation from penetrating into the paper substrate. The thermoplastic resin of the outermost layer can be the same resin as the thermoplastic resin of the innermost layer.

[0054] To impart barrier properties to the microwave paper cup 1 of this disclosure, a barrier layer may be applied to the material sheet. As the barrier layer, a vapor-deposited film may be used, which is obtained by vapor deposition on a synthetic resin film that serves as the base material. In the vapor deposition process, high temperatures are reached, so a heat-resistant film is desirable, and examples include polyethylene terephthalate, polybutylene terephthalate, and nylon. Materials to be vapor-deposited include silicon dioxide (silica) and metal oxides (alumina, etc.), but metal vapor deposition (aluminum vapor deposition, etc.) is undesirable when considering microwave heating suitability. Alternatively, a barrier layer may be provided using a resin with barrier properties. For example, MXD6-nylon or ethylene-vinyl alcohol copolymer resin (EVOH) may be used. Metal foil (aluminum foil, etc.) is undesirable when considering microwave heating suitability.

[0055] <First aspect of the second embodiment> In this embodiment, an outer cylindrical member 41 is provided on the outside of the microwave paper cup 1. The microwave paper cup 1 equipped with the outer cylindrical member 41 is referred to here as an insulated paper cup 6. This embodiment will be explained with reference to Figure 9.

[0056] The body angle θ4 of the outer cylinder member 41 is smaller than the body angle θ2 of the microwave paper cup 1. Also, the inner diameter of the upper part of the outer cylinder member 41 is approximately the same as the outer diameter of the microwave paper cup 1 at the position of the top curl portion 13. Therefore, if the space between the microwave paper cup 1 and the outer cylinder member 41 is considered an insulating space 42, this insulating space 42 becomes larger towards the bottom. The insulating space 42 is also intended to provide insulation so that when the microwave paper cup 6 is held in the hand, the hands do not become hot due to the presence of high-temperature contents inside the microwave paper cup 1.

[0057] Furthermore, an outer cylinder curl portion 43 is provided at the lower end of the outer cylinder member 41. In this embodiment, the lower end of the outer cylinder member 41 extends downward from the lower end of the microwave paper cup 1. Therefore, when the insulated paper cup 6 is held by hand, the outer cylinder curl portion 43 is supported by the fingers or palm, so it does not hurt even if fingers or other body parts touch the outer cylinder member 41. In addition, because the outer cylinder member 41 is equipped with an outer cylinder curl portion 43, the lower end of the circumferential outer cylinder curl portion 43 is reinforced, making it less prone to deformation.

[0058] Furthermore, it is desirable that the thread end portion 31 be folded uniformly around its entire circumference. However, when processing the thread end portion 31, the folding angle θ1 of the thread end portion 31 may vary within a small range. In that case, because the position of the tip of the thread end portion 31 varies in the vertical direction, the microwave paper cup 1 may tilt instead of standing upright when placed on it. In this embodiment, the lower end of the outer cylinder member 41 extends downward from the lower end of the microwave paper cup 1. Therefore, when the insulated paper cup 6 is placed on a table or the like, the outer cylinder curl portion 43 of the outer cylinder member 41 comes into contact with the table or the like, making it easier for the insulated paper cup 6 to stand upright without tilting.

[0059] Depending on the application and usage conditions, the outer cylinder curl portion 43 may be folded over. Alternatively, the outer cylinder curl portion 43 may be omitted. Furthermore, the heat insulating space 42 may be omitted or may be very small. In this case, the heat insulating performance is ensured by the performance of the material sheet of the outer cylinder member 41.

[0060] The material sheet for the outer cylinder member 41 may be a paper base material, and the paper base material may be coated cardboard, cup paper, ivory, cardstock, etc. From the viewpoint of preventing the heat insulating space 42 from collapsing when held in the hand, processing from the blank to the outer cylinder member (cylindrical processing, processing of the outer cylinder curl portion 43 if necessary), and cost, the basis weight of the paper base material is 100 g / m². 2 More than 400g / m 2 The following is preferable. More preferably, the basis weight of the paper substrate should be 150 g / m². 2 More than 250g / m 2 The following is preferable.

[0061] Furthermore, a thermoplastic resin layer may be provided on at least one of the outermost layer (including a single layer) or innermost layer (including a single layer) of the material sheet of the outer cylinder member 41, including the paper substrate. The function of this thermoplastic resin layer is to provide adhesion, moisture resistance, and stain resistance, and this thermoplastic resin may be the same as the thermoplastic resin of the innermost layer in the first embodiment.

[0062] The microwave paper cup 1 and the outer cylinder member 41 are joined at a joint 44 near the top curl portion 13. This joining may be done using an adhesive, such as a hot melt adhesive or an aqueous emulsion adhesive. If a thermoplastic resin layer is provided on both or one of the outer surfaces of the microwave paper cup 1 and the inner surface of the outer cylinder member 41, the thermoplastic resin layer may be melted by heat to perform heat welding.

[0063] <Second aspect of the second embodiment> In this embodiment, as in the first embodiment, a cylindrical outer cylinder member 41 is attached to the microwave paper cup 1. This embodiment will be explained with reference to Figure 10. The relationship between the body angle θ2 of the microwave paper cup 1 and the body angle θ4 of the outer cylinder member 41, and the shape of the heat insulating space 42 are the same as in the first embodiment. Also, the relationship between the inner diameter of the upper part of the outer cylinder member 41 and the outer diameter at the position of the top curl portion 13 of the microwave paper cup 1, and the method of joining the outer cylinder member 41 and the microwave paper cup 1 are the same as in the first embodiment.

[0064] In this embodiment, the lower end of the outer cylinder member 41 is above the lower end of the microwave paper cup 1. The lower end of the outer cylinder member 41 is near the lower end of the body portion 11 and does not extend over the threaded end portion 31. In this case, the outer cylinder curl portion 43 contacts the body portion 11, making it easier to maintain the shape of the heat insulating space 42. In particular, even when the body portion of the heat insulating paper cup 6 is firmly gripped by hand, the heat insulating space 42 does not narrow, and the heat insulating performance is maintained. If the outer cylinder curl portion 43 were to contact the folded threaded end portion 31, which has a smaller horizontal cross-sectional diameter, the heat insulating space 42 would narrow, and the heat insulating performance would decrease. The outer cylinder curl portion 43 and the body portion 11 may alternatively be joined, and the joining method at that site may employ the same method as the joining at the position of the top curl portion 13.

Examples

[0065] Hereinafter, the embodiments of the present disclosure will be described more specifically with reference to examples. Note that " / " indicates the boundary between mutually adjacent layers.

[0066] <Example 1> For both the body member 15 and the bottom member 25, material sheets having the following layer configuration were prepared. (Outer surface side) Outermost thermoplastic resin layer (polypropylene 20 μm, SunAllomer Ltd. PHA03A) / Paper base material (cup base paper 220 g / m 2 O&C Ivory Board Co., Ltd. COC HCV) / Innermost thermoplastic resin layer (polypropylene 40 μm, SunAllomer Ltd. PHA03A) / (Inner surface side)

[0067] The above material sheets were processed to produce an unprocessed paper cup 5. The main dimensions of the unprocessed paper cup 5 are as follows. Outer diameter (diameter) of top curl portion 13: 100 mm Height of unprocessed paper cup 5: 89 mm Body angle θ2: 7.6° Outer diameter of the lower end of the curl bottom portion 31 of unprocessed paper cup 5: 70.6 mm Length L of the curl bottom portion: 5.5 mm Full capacity: 457 ml

[0068] The curl bottom portion 31 of the unprocessed paper cup 5 was processed to produce the microwave paper cup 1. The shape is the one described in the first aspect of the first embodiment, in which vertical ruled lines 32 are provided on the curl bottom portion 31, and 36 vertical ruled lines 32 are provided. The bending angle θ1 of the curl bottom portion 31 was 53.3°.

[0069] <Example 2> A microwaveable paper cup 1 was manufactured that was the same as in Example 1, except that the folding angle θ1 of the thread end portion 31 was 56.7°.

[0070] <Example 3> For both the body member 15 and the bottom member 25, material sheets with the following layer configuration were prepared. (Outside side) Paper base material (cup paper base 240g / m²) 2 Nippon Paper Industries Co., Ltd. CUP-N(D) / Innermost thermoplastic resin layer (low-density polyethylene, 25 μm) Nippon Polyethylene Co., Ltd. (LC520) (Inner side)

[0071] The above material sheet was processed to create the unprocessed paper cup 5. The main dimensions of the unprocessed paper cup 5 are as follows: Outer diameter (diameter) of top curl section 13: 98mm Height of paper cup 5 before processing: 97mm Body angle θ2: 6.0° Outer diameter of the lower end of the thread base 31 of the paper cup 5 before processing: 72.3 mm Thread butt length L: 8.0 mm Full capacity: 480ml

[0072] The threaded end portion 31 of the unprocessed paper cup 5 was processed to produce the microwaveable paper cup 1. The threaded end portion 31 had a concave portion 34, a convex portion 35, and stepped lines 33, as described in the second aspect of the first embodiment, with 36 stepped lines 33 provided. The folding angle θ1 of the threaded end portion 31 was 46.0°.

[0073] <Example 4> A microwaveable paper cup 1 was manufactured that was the same as in Example 3, except that the folding angle θ1 of the thread end portion 31 was 48.5°.

[0074] <Example 5> A microwaveable paper cup 1 was manufactured that was the same as in Example 3, except that the folding angle θ1 of the thread end portion 31 was 49.5°.

[0075] <Comparative Example 1> A microwaveable paper cup 1 was manufactured that was the same as in Example 1, except that the folding angle θ1 of the thread end portion 31 was 61.3°.

[0076] <Comparative Example 2> A microwaveable paper cup 1 was manufactured that was the same as in Example 1, except that the folding angle θ1 of the thread end portion 31 was 60.4°.

[0077] <Comparative Example 3> This comparative example uses the paper cup 5 from Example 1 before processing, and a microwaveable paper cup 1 was produced that is the same as in Example 1 except that the folding angle θ1 was 82.4°. The folding angle θ1 is θ1 = 90° - body angle θ2.

[0078] <Comparative Example 4> A microwaveable paper cup 1 was manufactured that was the same as in Example 3, except that the folding angle θ1 of the thread end portion 31 was 51.8°.

[0079] <Comparative Example 5> A microwaveable paper cup 1 was manufactured that was the same as in Example 3, except that the folding angle θ1 of the thread end portion 31 was 52.7°.

[0080] <Comparative Example 6> A microwaveable paper cup 1 was manufactured that was the same as in Example 3, except that the folding angle θ1 of the thread end portion 31 was 56.8°.

[0081] <Comparative Example 7> A microwaveable paper cup 1 was manufactured that was the same as in Example 3, except that the folding angle θ1 of the thread end portion 31 was 62.9°.

[0082] <Comparative Example 8> This comparative example uses the paper cup 5 from Example 3 before processing, and a microwaveable paper cup 1 was produced that is the same as in Example 3, except that the folding angle θ1 was 84.0°. The folding angle θ1 is θ1 = 90° - body angle θ2 (= 6.0°).

[0083] <Rating> Paper cups (samples) from Examples 1 to 5 and Comparative Examples 1 to 8 were heated in a microwave oven, and the condition of the base was checked. A "○" indicated no charring at the base, while a "×" indicated charring. Minor discoloration that did not pose a risk was also indicated as "○". The results are shown in Table 1.

[0084] The evaluation method for microwave heating is as follows: First, 200 ml of tap water at room temperature (20°C or higher, 30°C or lower) is poured into the sample. Next, the sample containing the tap water is placed in the center of the microwave oven and heated for 2 minutes. The microwave oven used for the evaluation was a household 700W microwave oven (Matsushita Electric Industrial Co., Ltd. NE-S300F).

[0085] [Table 1]

[0086] The following can be seen from the results of the microwave heating evaluation of Examples 1 and 2 and Comparative Examples 1 to 3: When the thread end length L is 5.5 mm, the product is suitable for microwave heating if the bending angle θ1 is less than 56.7°, and is not suitable for microwave heating if it is greater than 61.3°. To summarize the above, if the length L of the folded end portion 31 is 5 mm or more and 6 mm or less, then a microwave paper cup 1 with a folding angle θ1 of 60° or less is suitable for microwave heating.

[0087] The following can be seen from the results of the microwave heating evaluation of Examples 3 to 4 and Comparative Examples 4 to 8. When the thread end length L is 8.0 mm, the product is suitable for microwave heating if the bending angle θ1 is less than 49.5°, and is not suitable for microwave heating if it is greater than 51.8°. To summarize the above, if the length L of the folded end portion 31 is 7.5 mm or more and 8.5 mm or less, then a microwave paper cup 1 with a folding angle θ1 of 50° or less is suitable for microwave heating.

[0088] Based on the above, if the thread end length L is 5.5 mm or more and 8.5 mm or less, the thread is suitable for microwave heating if the bending angle θ1 is less than 49.5°, and not suitable for microwave heating if it is greater than 51.8°. To summarize the above, if the length L of the folded end portion is 5 mm or more and 8 mm or less, then the microwave paper cup 1 with a folding angle θ1 of 50° or less is suitable for microwave heating. [Explanation of symbols]

[0089] 1 Microwave paper cup 5. Paper cup before processing of the thread end (Paper cup before processing) 6 Insulated paper cups 11 Torso 13 Top curl section 15 Body parts 16. Folded section 21 Bottom 22 Bottom part 25 Bottom member 31. Butt section 32 vertical ruled lines 33 Stepped Ruled Lines 34 Concave portion 35 Convex portion 41 Outer cylinder member 42 Insulated Space 43 Outer cylinder curl section 44 Joint L Length of thread end X horizontal plane Z plumb line θ1 Bending angle θ2 Body angle θ3 is the angle formed between the body and the tail end (body-tail end angle). θ4 Angle of the outer cylinder body (Angle of the outer cylinder body)

Claims

1. In microwave paper cups, A body member formed at least in a cylindrical shape, A base member consisting of a bent portion with a folded outer edge and a bottom surface, The bent portion of the bottom member is formed by sandwiching and joining the folded portion where the lower end of the body member is folded back with the unfolded body member, and the thread tail portion is bent inward. A gap is provided between the thread end portion and the bottom portion. The bottom surface is flat, At the bent portion near the upper end of the thread tail portion, the thread tail portion is bent. The end portion of the microwave paper cup, cut by a plane passing through the vertical line, is straight. As you move from the upper side to the lower side of the thread tail portion, the gap gradually increases. At the tip of the thread end, the gap is largest. The length of the folded thread end portion is 5 mm or more and 6 mm or less. A microwave paper cup in which the angle of fold formed by the tail end portion and a horizontal plane perpendicular to the vertical line of the microwave paper cup is 60° or less in the plane passing through the vertical line of the microwave paper cup.

2. In microwave paper cups, A body member formed at least in a cylindrical shape, A base member consisting of a bent portion with a folded outer edge and a bottom surface, The bent portion of the bottom member is formed by sandwiching and joining the folded portion where the lower end of the body member is folded back with the unfolded body member, and the thread tail portion is bent inward. A gap is provided between the thread end portion and the bottom portion. The bottom surface is flat, At the bent portion near the upper end of the thread tail portion, the thread tail portion is bent. The end portion of the microwave paper cup, cut by a plane passing through the vertical line, is straight. As you move from the upper side to the lower side of the thread tail portion, the gap gradually increases. At the tip of the thread end, the gap is largest. The length of the folded thread end portion is 7.5 mm or more and 8.5 mm or less. A microwave paper cup in which the angle of fold formed by the tail end portion and a horizontal plane perpendicular to the vertical line of the microwave paper cup is 50° or less in the plane passing through the vertical line of the microwave paper cup.

3. In microwave paper cups, A body member formed at least in a cylindrical shape, A base member consisting of a bent portion with a folded outer edge and a bottom surface, The bent portion of the bottom member is formed by sandwiching and joining the folded portion where the lower end of the body member is folded back with the unfolded body member, and the thread tail portion is bent inward. A gap is provided between the thread end portion and the bottom portion. The bottom surface is flat, At the bent portion near the upper end of the thread tail portion, the thread tail portion is bent. The end portion of the microwave paper cup, cut by a plane passing through the vertical line, is straight. As you move from the upper side to the lower side of the thread tail portion, the gap gradually increases. At the tip of the thread end, the gap is largest. The length L of the folded thread end portion is 5 mm or more and 8.5 mm or less. A microwave paper cup in which the angle of fold formed by the tail end portion and a horizontal plane perpendicular to the vertical line of the microwave paper cup is 50° or less in the plane passing through the vertical line of the microwave paper cup.

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