Paper container and paperboard base paper

Abstract

To provide a paper container having little forming imperfection and a paperboard base paper causing little forming imperfection.SOLUTION: A paper container 10 that is formed only by press forming from a single piece of paperboard base paper includes bottom portions 12a and 12b, a side wall portion 13 connected so as to surround each of the bottom portions 12a and 12b, storage portions 14a and 14b formed by the bottom portions 12a and 12b and the side wall portion 13, a partition portion 15 that is connected to the side wall portion 13 on an inner side of the side wall portion 13, is connected to each of the bottom portions 12a and 12b to stand up, and divides an inner side of the side wall 13 into the bottom portions 12a and 12b and into the storage portions 14a and 14b, and folded portions 17a and 17b formed in the vicinity of the connection points 16a and 16b between the partition portion 15 and the side wall portion 13. The folding portion 17a is formed by folding folding ruled lines 7a and 7b formed on the paperboard base paper, and the folding portion 17b is formed by folding folding ruled lines 7c and 7d, respectively.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a paper container and a paperboard base paper, and more particularly to a paper container having a partition and a paperboard base paper used for press-molding a paper container having a partition. [Background technology]

[0002] As containers for storing cooked foods, various paper containers have been proposed as alternatives to plastic containers, which place a heavy burden on the environment when disposed of after use and have poor heat resistance, and which reduce the burden on the environment when disposed of and are heat-resistant enough to withstand high temperatures in an oven range, etc. (for example, Patent Document 1).

[0003] FIG. 13 is a plan view of a first conventional paper container.

[0004] Referring to the figure, the paper container 70 is formed solely by press molding from a single sheet of paperboard (not shown). The paper container 70 has a generally rectangular outer edge with linear portions 71a, 71b, 71c, and 71d interconnected with curved portions 72a, 72b, 72c, and 72d. The paper container 70 also includes a bottom 74, a sidewall 73 connected to the bottom 74, a flange 75 connected to the sidewall 73 and extending horizontally, and a rolled-edge portion 76 formed on the outer periphery of the flange 75. The width W4 of a curved-edge portion 78 corresponding to the curved edge 72a is set larger than the width W3 of a linear-edge portion 77 corresponding to the linear portion 71d. The widths of the other curved portions 72b-72d and the linear portions 71a-71c are similarly set. Furthermore, a plurality of folds 79 extending radially toward the outer edge of the paper container 70 are formed in portions of the sidewall 73, flange 75, and rolled-edge portion 76 corresponding to the curved edge 72a. Similar creases 79 are also formed in the other curved portions 72b to 72d. These creases 79 are formed based on a plurality of radial lines that have been formed in advance on the paperboard base paper before press-molding, and wrinkles that occur due to sagging of the paper during press-molding of the paper container 70 are absorbed by the lines to form the creases 79.

[0005] Incidentally, the paper container 70 requires the use of separate dividers to store multiple foods in small portions, which is inconvenient for use as a lunch box, etc. Therefore, various paper containers with dividers have been proposed (for example, Patent Document 2).

[0006] FIG. 14 is a perspective view and a plan view of a second conventional paper container.

[0007] Referring to these figures, the paper container 80 is obtained by press molding, preferably deep drawing, using paperboard (not shown) in which a resin layer is laminated on one or both sides of a stretched paper, and has a flat rectangular container-shaped wall 83 formed around the periphery of a bottom plate 82. A number of vertical wrinkles 84 are formed at intervals around the entire periphery of the container-shaped wall 83. Furthermore, partition walls 85a and 85b are integrally formed between the container-shaped walls 83 so as to intersect in a crisscross pattern.

[0008] The intersection of container-shaped wall 83 and partition wall 85a or 85b has polygonal top surfaces 86a, 86b, 86c, and 86d, each having a side connecting the top of partition wall 85a or 85b to the wall surface of container-shaped wall 83. Furthermore, the intersection of partition walls 85a and 85b has polygonal top surface 87, each having a side connecting the top of partition wall 85a to the top of partition wall 85b. These top surfaces 86a-86d and 87 have slightly raised portions 88a, 88b, 88c, and 88d, and 89, respectively, on their sides, which serve to increase the strength of top surfaces 86a-86d and 87. With this configuration, paper container 80 has multiple storage compartments, allowing foods that should not be stored in the same storage compartment, such as rice and side dishes, to be stored in separate storage compartments. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 3411951 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-35312 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the paper container 80 described above, because the partition walls 85a and 85b are formed to bulge out from the paperboard, there is a risk of paper sagging during the press-molding process in the paper container 80. In particular, paper sagging is likely to occur near the intersection of the container shape wall 83 and the partition wall 85a or 85b, and near the intersection of the partition walls 85a and 85b. This paper sagging is crushed in the mold during press-molding, forming irregular wrinkles that reduce the appearance and strength of the paper container 80. Furthermore, in the process of forming the irregular wrinkles, the paper near the intersection may be unexpectedly stretched more than necessary, causing the paper container 80 to tear.

[0011] The present invention has been made to solve the above-mentioned problems, and has as its object to provide a paper container that is well formed and a paperboard base paper that is less likely to cause forming defects. [Means for solving the problem]

[0012] In order to achieve the above object, the invention described in claim 1 is a paper container formed solely by press molding from a single sheet of paperboard base paper, and comprises a bottom, a side wall connected to the bottom, a storage section formed by the bottom and the side wall, and at least one partition connected to the side wall at at least one point on the inner side of the side wall and connected to the bottom to separate the bottom and the storage section, and a slack absorption section is formed near the connection point between the partition and the side wall to absorb slack in the paper that occurs during press molding.

[0013] With this configuration, the slack of the paper when the partition is formed is absorbed by the slack absorbing section.

[0014] The invention of claim 2 is the same as the invention of claim 1, in which the slack absorbing portion comprises at least one ruled line formed on the paperboard base paper.

[0015] With this configuration, slack in the paper is guided by the ruled lines and absorbed by the slack absorbing section.

[0016] The invention of claim 3 is the same as the invention of claim 2, in which the slack absorbing portion comprises a plurality of ruled lines formed on the paperboard base paper.

[0017] With this configuration, the number of locations where slack in the paper can be guided to the slack absorbing section increases.

[0018] The invention described in claim 4 is the same as the invention described in claim 2, in which the slack absorbing portion is a folded portion formed by folding two folding lines formed in the paperboard base paper.

[0019] With this configuration, the slack of the paper is absorbed by the slack absorbing section by regular folding.

[0020] The invention described in claim 5 is the configuration of the invention described in any one of claims 2 to 4, wherein the ruled lines are formed in a mountain shape with the apex on the side wall portion side in a plan view.

[0021] With this configuration, the shape of the creases will be in line with the direction of the force applied to the paperboard base paper during pressing.

[0022] The invention of claim 6 is the same as the invention of claim 5, in which the minor angle of the ruled lines is 70° to 130°.

[0023] With this configuration, the shape of the creases is more in line with the direction of the force applied to the paperboard base paper during pressing.

[0024] The invention described in claim 7 is a configuration of the invention described in any one of claims 1 to 6, which has multiple intersecting partition sections, and intersecting slack absorption sections formed near the intersections of the partition sections.

[0025] With this configuration, slack in the paper near the intersection of the partitions that occurs during press molding is absorbed by the intersection slack absorbing section.

[0026] The invention described in claim 8 is the configuration of the invention described in any one of claims 1 to 7, in which the side wall portion has a flange portion connected to the side wall portion and extending horizontally, and a rolled edge portion formed on the outer peripheral edge of the flange portion.

[0027] With this configuration, the strength around the upper end of the side wall portion is improved.

[0028] The invention described in claim 9 is the configuration of the invention described in claim 8, in which the outer edge is a polygonal shape in which straight and curved portions are connected to each other, and the width of the curved portion of the flange portion that corresponds to the curved portion and where creases occur is greater than the width of the straight portion that corresponds to the straight portion.

[0029] With this configuration, each of the creases generated in the curved line corresponding portions is formed longer than when the width of the curved line corresponding portions is the same as the width of the straight line corresponding portions, and the sheet is compressed in that state.

[0030] The invention described in claim 10 is the configuration of the invention described in claim 9, in which a plurality of folds extending radially toward the outer edge are formed in parts of the side wall, flange and rolled edge that correspond to the curved portion.

[0031] The invention of claim 11 is the configuration of the invention of claim 10, in which the creases are formed based on a plurality of radial lines formed in advance on the paperboard base paper.

[0032] The invention described in claim 12 is a sheet of paperboard base paper used in press-molding paper containers, comprising a bottom forming portion, a side wall forming portion connected to the bottom forming portion, at least one partition forming portion connected to the side wall forming portion at at least one point on the inner side of the side wall forming portion and arranged to separate the bottom forming portion, and at least one crease formed near the connection point between the partition forming portion and the side wall forming portion.

[0033] With this configuration, any slack in the paper when forming the partition is guided along the crease and absorbed.

[0034] The invention described in claim 13 is the same as the invention described in claim 12, except that it has a plurality of intersecting partition forming portions, and intersecting point lines are formed near the intersection points of the partition forming portions.

[0035] With this configuration, any slack in the paper near the intersection of the partitions is guided along the ruled line at the intersection and absorbed. [Effects of the Invention]

[0036] As explained above, in the invention of claim 1, the slack of the paper when the partition is formed is absorbed by the slack absorbing section, resulting in a paper container that is well formed.

[0037] In addition to the effect of the invention of claim 1, the invention of claim 2 allows slack in the paper to be guided by the creases and absorbed by the slack absorbing section, resulting in a paper container that is better formed.

[0038] The invention of claim 3 has the effect of the invention of claim 2, and in addition, the number of locations for guiding slack in the paper to the slack absorbing section is increased, resulting in a paper container that is better formed.

[0039] The invention of claim 4 has the effect of the invention of claim 2, and in addition, the slack of the paper is absorbed into the slack absorption section by regular folding, thereby improving the appearance and strength of the slack absorption section.

[0040] The invention described in claim 5 has the effect of any of the inventions described in claims 2 to 4, and in addition, the shape of the ruled lines is aligned with the direction of the force applied to the paperboard base paper during pressing, thereby further improving the aesthetic appearance of the slack absorption section.

[0041] In addition to the effect of the invention of claim 5, the invention of claim 6 has the advantage that the shape of the ruled lines is more in line with the direction of the force applied to the paperboard base paper during pressing, thereby further improving the aesthetic appearance of the slack absorption section.

[0042] The invention described in claim 7 has the effect of any of the inventions described in claims 1 to 6, and in addition, the slack in the paper near the intersection of the partitions that occurs during press molding is absorbed by the intersection slack absorption section, so that even complex shapes can be formed into paper containers that are well-formed.

[0043] The invention of claim 8 has the effect of any one of the inventions of claims 1 to 7, and in addition, improves the strength around the upper end of the side wall portion, thereby improving the shape retention of the paper container.

[0044] In addition to the effects of the invention of claim 8, the invention of claim 9 has the advantage that each of the fold wrinkles that occur in the curved corresponding parts are formed longer than in a case where the width of the curved corresponding parts is the same as the width of the straight corresponding parts, and the paper container is compressed in that state, so the compression area is larger and the shape retention of the paper container is improved.

[0045] In the invention described in claim 12, slack in the paper when forming the partition is absorbed and guided along the score lines, making it less likely that molding defects will occur.

[0046] The invention described in claim 13 has the effect of the invention described in claim 12, in addition to which slack in the paper near the intersection of the partition is absorbed and guided along the intersection line, making it less likely that molding defects will occur even with complex shapes. [Brief explanation of the drawings]

[0047] [Figure 1] 1 is a plan view of a paperboard base sheet according to a first embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the “X” portion shown in FIG. [Figure 3] FIG. 3 is an enlarged end view taken along the line III-III shown in FIG. 2. [Figure 4]FIG. 2 is a schematic diagram showing the process of press-molding the paperboard base paper shown in FIG. 1 to obtain a paper container according to the first embodiment of the present invention. [Figure 5] FIG. 5 is a front view of a paper container obtained by the process shown in FIG. [Figure 6] FIG. 5 is a plan view of a paper container obtained by the process shown in FIG. [Figure 7] FIG. 7 is an enlarged view of the “Y” portion shown in FIG. [Figure 8] FIG. 8 is an enlarged end view of the line VIII-VIII shown in FIG. 7. [Figure 9] FIG. 10 is a plan view of a paper container of a comparative example, and corresponds to FIG. 6 of the first embodiment. [Figure 10] FIG. 10 is an enlarged view of the “Z” portion shown in FIG. [Figure 11] FIG. 10 is a plan view of a paper container according to a second embodiment of the present invention, and corresponds to FIG. 6 of the first embodiment. [Figure 12] FIG. 13 is a plan view of a paper container according to a third embodiment of the present invention, and corresponds to FIG. 11 of the second embodiment. [Figure 13] FIG. 1 is a plan view of a first conventional paper container. [Figure 14] 1A and 1B are a perspective view and a plan view of a second conventional paper container. DETAILED DESCRIPTION OF THE INVENTION

[0048] FIG. 1 is a plan view of a paperboard base paper according to a first embodiment of the present invention, FIG. 2 is an enlarged view of the "X" portion shown in FIG. 1, and FIG. 3 is an enlarged end view of the III-III line shown in FIG. 2.

[0049] First, referring to FIG. 1, paperboard base paper 1 is made by punching out a sheet body in which resin layers are formed on both sides of a paper base material by extrusion lamination. The paperboard base paper 1 includes bottom forming portions 2a and 2b, a side wall forming portion 3 that connects and surrounds each of the bottom forming portions 2a and 2b, a plurality of lines 4a and 4b that extend radially from the bottom forming portions 2a and 2b toward the outer edge of the side wall forming portion 3 and toward boundary lines 8a, 8b, 8c, and 8d, a partition forming portion 5 that connects to each of a pair of opposing regions on the longitudinal side of the side wall forming portion 3 on the inner side of the side wall forming portion 3 and is arranged so as to divide the inner side of the side wall forming portion 3 into the bottom forming portions 2a and 2b, and folding lines (folding lines) 7a, 7b, 7c, and 7d formed near each of connection points 6a and 6b between the partition forming portion 5 and the side wall forming portion 3, and guide lines 9a and 9b. The effects of this configuration will be described later. The partition forming portion 5 extends perpendicular to the outer edge of the longitudinal side of the side wall forming portion 3, and the partition forming portion 5 and the side wall forming portion 3 are connected at connection points 6a and 6b so as to be substantially perpendicular to each other. The partition forming portion 5 is formed at a position eccentric to the center point of the paperboard base paper 1. Three ruled lines are formed on each side of the partition forming portion 5 along the partition forming portion 5.

[0050] Next, referring to FIG. 2, the folding lines 7a and 7b are formed in a mountain shape with their apexes on the side wall forming portion 3 side, and the minor angles θ1 and θ2 of the folding lines 7a and 7b are both set to 105°. The distance D between the folding lines 7a and 7b is set to 3.5 mm. The guide line 9a is formed linearly so as to extend from the apex of the folding line 7b to the apex of the folding line 7a toward the partition forming portion 5 side. The effects of this configuration will be described later. The boundary line 8a has one end connected to one of the lines 4a and the other end located on the partition forming portion 5 side, and is formed in an arc shape that divides the bottom forming portion 2a side and the connection point 6a side. One end of the folding line 7a is also connected to the boundary line 8a. The boundary stripe 8b is also formed on the other end side of the folding ruled line 7a in the same configuration as the boundary stripe 8a.

[0051] 2 and 3, only the folding line 7b close to the side wall forming portion 3 is formed so as to protrude toward the upper surface of the paperboard base paper 1, and the folding line 7a, guide line 9a, boundary lines 8a and 8b, and line 4b far from the side wall forming portion 3 are all formed so as to protrude toward the lower surface of the paperboard base paper 1. Note that line 4a, which is not shown in Fig. 3, is also formed so as to protrude toward the lower surface of the paperboard base paper 1. The effects of this configuration will be described later.

[0052] In addition, the folding lines 7c and 7d, the boundary lines 8c and 8d, and the guide line 9b formed near the connection point 6b shown in Figure 1 are formed in the same configuration as the folding lines 7a and 7b, the boundary lines 8a and 8b, and the guide line 9a, respectively.

[0053] FIG. 4 is a schematic diagram showing the process of press-molding the paperboard base paper shown in FIG. 1 to obtain the paper container according to the first embodiment of the present invention.

[0054] First, referring to Fig. 4 (1), the molding device 40 includes a pair of first and second molds 41 and 42. The second mold 42 is formed with a concave-convex shape corresponding to the bottom and partition of a paper container, which will be described later, and the first mold 41 is formed with a concave-convex shape corresponding to the concave-convex shape of the second mold 42. The first mold 41 is located above the second mold 42 and can be raised and lowered relative to the second mold 42. The second mold 42 is fixed in an installed position.

[0055] When press-forming the paperboard base paper 1 using the forming device 40, first, referring to Figures 4(1) and 1, the paperboard base paper 1 is fed one sheet at a time so as to be placed on the upper surface of the second mold 42. At this time, the upper surface of the paperboard base paper 1 faces the second mold 42. Note that to facilitate press-forming, the paperboard base paper 1 may be heat-treated by a device other than the forming device 40 (not shown) or by the forming device 40 before moving on to the next step shown in Figure 4(2) or during the step (2).

[0056] Next, referring to (2) in Figure 4, the first mold 41 is lowered toward the second mold 42, the paperboard base paper 1 is sandwiched between the first mold 41 and the second mold 42, and the paperboard base paper 1 is press-formed by the forming device 40. During this press-forming process, as the first mold 41 and the second mold 42 approach each other and the deformation of the paperboard base paper 1 progresses, sagging occurs in the paperboard base paper 1, and the sagging paper is eventually compressed in a folded state by the first mold 41 and the second mold 42. The folding of this sagging paper will be described later.

[0057] 4(3), the first mold 41 is raised away from the second mold 42, and the paper container 10 obtained by press molding is removed from the second mold 42, thereby completing the press molding of the paperboard base paper 1 by the molding device 40. In other words, the paper container 10 is formed from one sheet of paperboard base paper 1 only by press molding by the molding device 40.

[0058] Figure 5 is a front view of a paper container obtained by the process shown in Figure 4, Figure 6 is a plan view of a paper container obtained by the process shown in Figure 4, Figure 7 is an enlarged view of the "Y" portion shown in Figure 6, and Figure 8 is an enlarged end view of line VIII-VIII shown in Figure 7.

[0059] First, referring to Figures 5 and 6, the paper container 10 comprises bottoms 12a and 12b, side walls 13 that connect and surround each of the bottoms 12a and 12b, storage sections 14a and 14b formed by the bottoms 12a and 12b and the side walls 13, partitions 15 that are connected to each of a pair of opposing surfaces of the side walls 13 on the inner side of the side walls 13 and that connect to each of the bottoms 12a and 12b and rise, dividing the inner side of the side walls 13 into the bottoms 12a and 12b and the storage sections 14a and 14b, and fold-in sections (slack absorption sections) 17a and 17b formed near connection points 16a and 16b between the partitions 15 and the side walls 13. Note that the folding portion 17a is formed by folding along the folding lines 7a and 7b formed on the paperboard base paper 1 shown in FIG. 1, and the folding portion 17b is formed by folding along the folding lines 7c and 7d. The effects of this configuration will be described later. The partition 15 extends perpendicular to the longitudinal surface of the side wall 13, and the partition 5 and the side wall 3 are connected at connection points 16a and 16b so as to be substantially perpendicular to each other. Also, as shown in FIG. 1, since the partition-forming portion 5 is formed in an eccentric position on the paperboard base paper 1, the partition 15 is also formed in an eccentric position relative to the center point of the paper container 10. A plurality of fold wrinkles 19 based on the lines 4b shown in FIG. 1 are formed in the range from the bottom 12a to the boundaries 18a and 18c, and in the range from the bottom 12b to the boundaries 18b and 18d.

[0060] The paper container 10 has a generally rectangular outer edge with linear portions 51a, 51b, 51c, and 51d and curved portions 52a, 52b, 52c, and 52d connected to one another, a flange portion 55 connected to the side wall portion 13 and extending horizontally, and a rolled edge portion 56 formed on the outer periphery of the flange portion 55. The width W2 of the curved portion 58 of the flange portion 55, which corresponds to the curved portion 52a and where folds 59 occur, is set larger than the width W1 of the straight portion 57 corresponding to the straight portion 51d. The other curved portions 52b to 52d and the straight portions 51a to 51c are set similarly. Furthermore, a plurality of folds 59 extending radially toward the outer edge of the paper container 10 are formed in a portion of the side wall portion 13, flange portion 55, and rolled edge 56 corresponding to the curved portion 52a, based on the line 4a shown in FIG. Similar folds 59 are also formed in the other curved portions 52b to 52d. Also, a plurality of folds 54 based on the filaments 4a are formed in the side wall portions 13, flange portions 55 and rolled hemming portions 56 corresponding to the straight portions 51a to 51d.

[0061] With this configuration, the slack in the paper that occurs in the paperboard base paper 1 during press-molding of the paper container 10 is absorbed by the lines 4a, and folding can be generated in the intended locations as creases 54 or 59, thereby suppressing the occurrence of unintended creases. Also, compared to when the width W2 of the curve-corresponding portion 58 is the same as the width W1 of the straight-line corresponding portion 57, each of the creases 59 that occur in the curve-corresponding portion 58 is formed longer and is compressed in that state, which increases the compression area and improves the shape retention of the paper container 10. Furthermore, the flange portion 55 and the rolled edge portion 56 improve the strength around the upper end of the side wall portion 13, thereby improving the shape retention of the paper container 10.

[0062] Next, referring to Figures 1, 7 and 8, the folding portion 17a formed near the connection point 16a between the partition portion 15 and the side wall portion 13 is formed by folding the folding line 7a into a valley fold in plan view and the folding line 7b into a mountain fold in plan view, and folding the paperboard base paper 1 around the folding lines 7a and 7b over one another.

[0063] With this configuration, the slack in the paper that occurs when forming the divider 15 in the paperboard base paper 1 is absorbed and guided along the folding lines 7a to 7d and is further absorbed by the folding sections 17a and 17b of the paper container 10, making it less likely that poor forming will occur in the paperboard base paper 1. That is, as shown in Figures 5 and 6, the paper container 10 is well formed. Note that to clarify that the paper container 10 is well formed and the various effects that result from the above configuration, a comparative example will be used below to explain the following.

[0064] FIG. 9 is a plan view of a paper container of a comparative example, and corresponds to FIG. 6 of the first embodiment, and FIG. 10 is an enlarged view of the "Z" portion shown in FIG.

[0065] Referring to these figures, the paper container 90 is constructed based on the idea that, in order to reduce the problems caused by the sagging of the paper described above, folds similar to the folds 79 formed in each of the curved sections 72a to 72d of the paper container 70 shown in Fig. 13 are intentionally formed around the connection points 96a and 96b between the side wall section 93 and the divider section 95. Therefore, the paperboard base paper on which the paper container 90 is based is provided with a plurality of radial lines corresponding to the line 4b shown in Fig. 1, but does not have lines corresponding to the folding lines 7a to 7d and the guide lines 9a, 9b. Note that the other components of the paperboard base paper and paper container 90 and the press-forming process are the same as those of the paperboard base paper 1 and paper container 10 according to the first embodiment, and therefore will not be described again here.

[0066] The paper container 90 is formed solely by press molding from a single sheet of paperboard base paper having the above-described configuration, and comprises bottoms 92a and 92b, side wall portions 93 connected to each of the bottoms 92a and 92b, a storage section 94a formed by the bottom 92a and the side wall portions 93, a storage section 94b formed by the bottom 92b and the side wall portions 93, and partition portions 95 connected to the side wall portions 93 on the inner side of the side wall portions 93, and connected to each of the bottoms 92a and 92b and rising to separate the bottoms 92a and 92b and the storage sections 94a and 94b, respectively.

[0067] Due to the above-described configuration of the paperboard base paper, regular fold wrinkles 99 that absorb the slack in the paper that occurred during press molding are formed around the joint 96a in the range from the bottom 92a to the boundary 98a of the paper container 90 and in the range from the bottom 92b to the boundary 98b. On the other hand, on the top surface of the joint 96a, multiple unintended wrinkles 97 have occurred irregularly due to slack in the paper that could not be absorbed by the fold wrinkles 99 alone. Note that a similar phenomenon also occurs at the joint 96b.

[0068] In other words, simply providing stripes around the connection points 96a and 96b does not solve the problem of paper sagging, and it can be said that the paper container 90 and the paperboard base paper used to form the paper container 90 are insufficiently effective in reducing unintended wrinkles 97. Furthermore, the connection points 96a and 96b, where wrinkles 97 occur irregularly, are prone to bending and also have reduced horizontal strength. Therefore, the paper container 90 may bend at the connection points 96a and 96b when unable to withstand the weight of the stored items, or may be pulled toward the stored items, causing each storage section 94a and 94b to bend downward, and it can also be said that the paper container 90 lacks reliability in terms of strength.

[0069] Compared to this paper container 90, the paper container 10 shown in Figures 5 to 8 can be said to be well-formed because the slack in the paper when the divider 15 is formed is absorbed by the folding sections 17a and 17b. In particular, the slack in the paper is guided by the folding lines 7a to 7d and absorbed by the folding section 17a or 17b, making it easier to control the slack in the paper, resulting in a well-formed paper container 10. Also, folding section 17a is provided with folding lines 7a and 7b, and folding section 17b is provided with folding lines 7c and 7d, respectively, and multiple folding lines are formed corresponding to each folding section, so there are more locations where the slack in the paper can be guided to the folding sections 17a and 17b, resulting in a well-formed paper container 10. Furthermore, by providing two folding lines for each folding portion, slack in the paper during the formation of the partition portion 15 is absorbed by the regular folding, improving the aesthetic appearance of the folding portions 17a and 17b. Furthermore, by forming each of the folding lines 7a to 7d in the mountain shape with the specific dimensions described above, all of the folding lines 7a to 7d are aligned with the direction of the force acting on the paperboard base paper 1 to swell the paperboard base paper 1, further improving the aesthetic appearance of the folding portions 17a and 17b. In addition, because the paperboard base paper is regularly folded to form the folding portions 17a and 17b, the vertical and horizontal strength of the connection portions 16a and 16b is improved, making it less likely that the connection portions 16a and 16b will bend or that the storage portions 14a and 14b will warp. Furthermore, boundary lines 8a-8d form boundaries 18a-18b, clearly separating partition 15 from storage sections 14a and 14b. Such boundary lines 8a-8d are connected to folding lines 7a or 7c, i.e., are formed near folding lines 7a or 7c, which encourages the folding lines 7a-7d to absorb slack in the paper, making it easier to control the slack in the paper.

[0070] FIG. 11 is a plan view of a paper container according to a second embodiment of the present invention, and corresponds to FIG. 6 of the first embodiment.

[0071] Referring to the figure, the paper container 20 is a replacement for the paper container 10 according to the first embodiment, which has two dividers 25a and 25b that intersect in a T-shape, and which divide the inner side of the side wall 23 into bottoms 22a, 22b, and 22c and storage sections 24a, 24b, and 24c by the dividers 25a and 25b. The vicinity of an intersection 26 between the dividers 25a and 25b is provided with an intersection fold section 28 formed by folding in intersection fold lines (intersection fold lines) 27a and 27b that are formed in advance on the paperboard base paper of the paper container 20. This intersection fold section 28 serves as an intersection slack absorbing section that absorbs slack in the paper that occurs near the intersection 26 during press molding. Furthermore, a fold section 17c is formed near a connection section 16c between the divider 25b and the side wall 23, with a configuration similar to that of the fold section 17a according to the first embodiment. The cross folding creases 27a and 27b have the same configuration as the folding creases 7a and 7b according to the first embodiment, and are formed in a mountain shape in plan view with the apex at the intersection 26. The cross folding crease 27a protrudes downward and tends to bend into a valley fold, while the cross folding crease 27b protrudes upward and tends to bend into a mountain fold. The guide crease 29 is formed in the same configuration as the guide creases 9a and 9b, extending from the apex of the cross folding crease 27b, via the apex of the cross folding crease 27a, toward the partition forming portion 25b.

[0072] The cross-folded portion 28 is formed by absorbing the sagging of the paper around the dividers 25a and 25b and the force that bulges the paperboard base paper using the bending of the cross-folding scores 27a and 27b and the guide scores 29, guiding the sagging to between the cross-folding scores 27a and 27b, and folding and compressing a portion of the paperboard base paper on the inside of the cross-folding score 27a, a portion of the paperboard base paper between the cross-folding scores 27a and 27b, and a portion of the paperboard base paper on the outside of the cross-folding score 27b. Note that the other components of the paper container 20 and the press-forming process are the same as those of the paper container 10 according to the first embodiment, so the description here will not be repeated.

[0073] With this configuration, slack in the paper that occurs when forming the dividers 25a and 25b in the paperboard base paper that forms the base of the paper container 20 is absorbed and guided along the cross-folding scores 27a and 27b and further absorbed in the cross-folding section 28 of the paper container 20, making it less likely that poor forming will occur even with a complex shape. In other words, slack in the paper near the intersection 26 of the dividers 25a and 25b is absorbed by the cross-folding section 28, resulting in a paper container 20 that is well formed even with a complex shape where the dividers intersect.

[0074] FIG. 12 is a plan view of a paper container according to a third embodiment of the present invention, and corresponds to FIG. 11 of the second embodiment.

[0075] Referring to the figure, the paper container 30 is replaced by a paper container 20 according to the second embodiment, which has two cross-shaped dividers 35a and 35b, and the dividers 35a and 35b divide the inner side of the side wall 33 into bottoms 32a, 32b, 33c, and 32d and storage sections 34a, 34b, 34c, and 34d. The vicinity of the intersection 36 between the dividers 35a and 35b is provided with cross-folding creases (cross-section creases) 37a and 37b formed in advance in the paperboard base paper of the paper container 30, and cross-folding sections (cross-slack absorbing sections) 38a and 38b formed by folding the cross-folding creases 37c and 37d, respectively. Further, near the connection point 16d between the partition portion 35b and the side wall portion 33, a folding portion 17d is formed with a configuration similar to that of the folding portion 17c according to the second embodiment. The cross folding lines 37a and 37c are formed with the same configuration as the cross folding line 27a according to the second embodiment, the cross folding lines 37b and 37d are formed with the same configuration as the cross folding line 27b according to the second embodiment, and the guide lines 39a and 39b are formed with the same configuration as the guide line 29 according to the second embodiment. The cross folding lines 38a and 38b are also formed with the same molding process and configuration as the cross folding line 28 according to the second embodiment. Note that the other components and press molding process of the paper container 30 are the same as those of the paper container 20 according to the second embodiment, and therefore will not be described again here.

[0076] With this configuration, slack in the paper that occurs when forming the dividers 35a and 35b in the paperboard base paper that forms the base of the paper container 30 is absorbed and guided along the cross-folding lines 37a to 37d and further absorbed by the cross-folding portions 38a and 38b of the paper container 30, making it less likely that poor forming will occur even with a complex shape. In other words, slack in the paper near the intersection 36 of the dividers 35a and 35b is absorbed by each of the cross-folding portions 38a and 38b, resulting in a paper container 30 that can be well formed even with a complex shape where the dividers intersect.

[0077] In the above embodiments, the paper container has a substantially rectangular outer edge with a continuous straight line and curved line, but it may have other polygonal shapes, or may have other shapes such as a circle or an ellipse. The size of the paper container is also not particularly limited.

[0078] Furthermore, in each of the above embodiments, the paper container has a flange portion connected to the side wall portion and a rolled edge portion formed on the outer peripheral edge of the flange portion, but it may have only one of these, or neither.

[0079] Furthermore, in each of the above embodiments, the width of the curved line-corresponding portion of the flange of the paper container where creases occur was set larger than the width of the straight line-corresponding portion, but it may also be set the same or smaller.

[0080] Furthermore, in each of the above embodiments, creases based on the lines formed on the paperboard base paper were formed on the side wall portions, flange portions and parts of the edge roll portions of the paper container corresponding to the curves, but the lines do not have to be formed on the paperboard base paper, and the paper container does not have to have creases.

[0081] Furthermore, in each of the above embodiments, the paper container has one or two dividers, but it is sufficient that at least one divider is formed, and it may have three or more dividers.The paperboard base paper also has to have at least one divider-forming portion, and it may have multiple dividers.

[0082] Furthermore, in each of the above embodiments, the partitions of the paper container extend perpendicular to one of the surfaces of the side wall, and the partitions and the side wall are connected at the connection points so as to be substantially perpendicular, but the partitions may extend in an oblique direction relative to each surface of the side wall, for example, in the diagonal direction of a rectangular side wall, and the partitions and the side wall do not have to be perpendicular to each other. In the paperboard base paper, too, the partition-forming portions may extend in an oblique direction relative to each region of the side wall-forming portions, and the partition-forming portions and the side wall-forming portions do not have to be perpendicular to each other.

[0083] Furthermore, in the first embodiment described above, the partition forming portion of the paperboard base paper is formed at a position eccentric to the center point of the paperboard base paper, and the partition of the paper container is also formed at a position eccentric to the center point of the paper container, but each may be formed at a central position or at a more eccentric position.

[0084] Furthermore, in the first embodiment, creases are formed along the partition forming portion on both sides of the paperboard base sheet, but the creases may be omitted.

[0085] Furthermore, in the first embodiment described above, the partition forming portion of the paperboard base paper has two connection points in the area of ​​the side wall forming portion, and the partition of the paper container has two connection points on the surface of the side wall, but it is sufficient if there is at least one connection point.

[0086] Furthermore, in each of the above-described embodiments, the minor angle of each of the folding lines and the cross folding lines is set to 105°, but it may be set in the range of 70° to 130°, and more preferably in the range of 90° to 120°.

[0087] Furthermore, in each of the above embodiments, the spacing between the folding lines forming the folding portion and the spacing between the cross folding lines forming the cross folding portion were both set to 3.5 mm, but they may be set to other spacings, preferably in the range of 2 mm to 6 mm, and more preferably in the range of 2.5 mm to 4.5 mm.

[0088] Furthermore, in the above-described embodiments, among the folding creases forming the folding portion, the outer folding crease is formed to protrude upward and form a mountain fold in plan view, and the inner folding crease is formed to protrude downward and form a valley fold in plan view, and among the cross folding creases forming the cross folding portion, the inner cross folding crease is formed to protrude upward and form a mountain fold in plan view, and the outer cross folding crease is formed to protrude downward and form a valley fold in plan view, but they may be formed to protrude in opposite directions, with the peaks and valleys of the folding reversed, or may be formed to protrude in the same direction.

[0089] Furthermore, in each of the above-described embodiments, the boundary line is connected to one of the lines extending radially toward the outer edge of the side wall forming portion and to one end of each of the folding lines, but either or none of these may be connected and each may be formed independently.

[0090] Furthermore, in each of the above embodiments, the folding lines are formed in a mountain shape with the apex on the side of the side wall forming portion (the side wall portion in a paper container), and the cross folding lines are formed in a mountain shape with the apex on the inner side, but they may also be formed in other shapes, such as an arc shape or a straight line shape.

[0091] Furthermore, in each of the above embodiments, the slack absorbing portion is formed by a folded portion formed by two folding creases, and the cross slack absorbing portion is formed by a cross folding portion formed by two cross folding creases. However, the slack absorbing portion may be formed by one or three or more creases, and the cross slack absorbing portion may be formed by one or three or more cross creases. In this configuration, slack in the paper is absorbed by the slack absorbing portion or the cross slack absorbing portion as the creases or the cross creases are compressed during press molding. Furthermore, the slack absorbing portion may not be formed by creases, and the cross slack absorbing portion may not be formed by cross creases, but by other configurations that control slack in the paper.

[0092] Furthermore, in the second embodiment, the partitions intersect in a T-shape, and in the third embodiment, they intersect in a cross-shape, but they may intersect in other shapes, and the intersecting points do not have to be perpendicular.

[0093] Furthermore, in the first embodiment, the boundary lines 8a and 8b are connected to one of the lines 4a and the folding line 7a, but they may also be connected to the folding line 7b. Also, except when the folding line 7b is extremely short, the boundary lines 8a and 8b may not be connected to either the line 4a or the folding lines 7a and 7b as long as they are formed near the folding line 7a. The same applies to the other boundary lines.

[0094] Furthermore, in each of the above-described embodiments, the type of paper base material for the paperboard base paper is not particularly limited, but pure white roll paper, kraft paper, coated cardboard, parchment paper, ivory paper, Manila paper, card paper, cup paper, glassine paper, etc. may be used depending on the desired application. Synthetic paper that has been treated to be water-resistant and oil-resistant may also be used.

[0095] Furthermore, in each of the above embodiments, the thickness of the paperboard base paper is not particularly limited, but is preferably 0.2 mm to 0.5 mm (basis weight 150 to 500 g / m 2 ) is preferable.

[0096] Furthermore, in each of the above embodiments, the paperboard base paper has resin layers formed on both sides of the paper base material by extrusion lamination, but it is not necessary for a resin layer to be formed, and depending on the intended use, it may be possible to use a paperboard with a resin film attached thereto, a paperboard coated with a resin, etc. Examples of methods for forming a resin layer include extrusion lamination, dry lamination, wet lamination, and coating with a resin solution.

[0097] When used for food storage purposes, as in the present invention, it is preferable that a resin layer be formed by extrusion lamination on at least one side of the paperboard base paper (the side that comes into contact with food). The type of resin is not particularly limited, and examples include thermoplastic resins such as polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin resins such as polypropylene, polyethylene, and polymethylpentene, acrylic (methacrylic) resins, diene resins such as polybutadiene, and polycarbonate resins. Furthermore, to make the paper container more environmentally friendly, biodegradable resins such as polylactic acid (PLA) can also be used. By laminating the resin, it is possible to impart properties such as heat resistance, water resistance, and gas / liquid permeability resistance to the molded paper container.

[0098] When a polyethylene terephthalate resin is used, the polyethylene terephthalate resin is a copolymerized polyethylene terephthalate resin obtained by copolymerization with isophthalic acid, and the copolymerization ratio of isophthalic acid in the copolymerized polyethylene terephthalate resin is preferably 1 mol % or more and less than 10 mol %, and the melting point is preferably 235°C or more and 250°C or less.

[0099] The copolymerized polyethylene terephthalate resin is preferably a biologically derived biomass polyethylene terephthalate resin with a biobased carbon content of 5% or more. It is also preferably a biologically derived (biomass resource-derived) biomass polyethylene terephthalate resin with a biobased carbon content of 5% or more. Polyethylene terephthalate resin is a resin obtained by polycondensing ethylene glycol and terephthalic acid as its main components, most of which are derived from fossil resources. By converting this into a biomass polyethylene terephthalate resin obtained from biological raw materials such as sugarcane, the amount of fossil resources used can be reduced and carbon neutrality is improved, thereby improving sustainability and contributing to environmental conservation.

[0100] In the present invention, the biobased carbon content, which is an indicator of the proportion of biologically derived materials in a polyethylene terephthalate copolymer resin, is preferably 5% or more, and more preferably 15% or more. The higher the biobased carbon content, the lower the proportion of fossil-derived materials, resulting in a container that is more environmentally friendly. On the other hand, a higher biobased carbon content also increases costs, so it is preferable for it to be within an appropriate range. The biobased carbon content can be expressed as the C14 content obtained by a radiocarbon (C14) measurement method in accordance with ISO-16620-2 (equivalent to the ASTM-D6866 standard). Fossil-derived materials contain very little C14, while biological sources contain a certain proportion (105.5 pMC). Therefore, if the C14 content in the polyethylene terephthalate copolymer resin is designated as PC14, the biobased carbon content can be calculated using the following formula:

[0101] "Bio-based carbon content (%) = PC14 / 105.5 x 100" Furthermore, in each of the above embodiments, the thickness of the resin on the surface of the paperboard base paper is not particularly limited, but is preferably 10 μm to 50 μm, and particularly preferably in the range of 20 to 30 μm.

[0102] Furthermore, in each of the above-described embodiments, the surface of the paperboard base paper may be printed, thereby improving the design. [Explanation of symbols]

[0103] 1...Paperboard base paper 2a, 2b...bottom forming part 3...Side wall forming part 5...Partition forming section 6a, 6b...Connection points 7a, 7b, 7c, 7d...Folding ruled lines 10...Paper containers 12a, 12b...bottom 13...Side wall 14a, 14b...Storage section 15...Partition 16a, 16b...Connection points 17a, 17b...folded section 20...Paper containers 22a, 22b, 22c...bottom 23...Side wall 24a, 24b, 24c...Storage area 25a, 25b...Partition 26...Intersection 27a, 27b...Cross-folding lines 28...Intersection fold 30...Paper containers 32a, 32b, 32c, 32d...bottom 33...Side wall 34a, 34b, 34c, 34d...Storage section 35a, 35b...Partition 36...Intersection 37a, 37b, 37c, 37d...Cross-folding lines 38a, 38b...Intersecting fold 51a, 51b, 51c, 51d...Straight section 52a, 52b, 52c, 52d...Curved section 55...Flange 56...Edge wrapping 57...Straight line corresponding part 58...Curved part 59...Folded wrinkles In addition, the same reference numerals in each drawing indicate the same or corresponding parts.

Claims

1. A paper container formed solely by press molding from a single sheet of paperboard base paper, The bottom and a sidewall portion connected to the bottom portion; a storage section formed by the bottom and the sidewall; and at least one partition portion that is connected to the side wall portion at at least one location on the inner side of the side wall portion and that is connected to the bottom portion and rises to separate the bottom portion and the storage portion, A paper container having a slack absorbing portion formed near the connection between the partition portion and the side wall portion, which absorbs slack in the paper that occurs during press molding.

2. The paper container according to claim 1 , wherein the slack absorber comprises at least one score line formed in the paperboard base paper.

3. The paper container according to claim 2 , wherein the slack absorbing portion comprises a plurality of the creases formed on the paperboard base paper.

4. 3. The paper container according to claim 2, wherein the slack absorbing portion comprises a folded portion formed by folding along two folding lines formed on the paperboard base paper.

5. The paper container according to claim 2 , wherein the lines are formed in a mountain shape with an apex on the side wall portion side in a plan view.

6. The paper container according to claim 5, wherein the minor angle of the crease is 70° to 130°.

7. The partition wall has a plurality of intersecting partitions, The paper container according to any one of claims 1 to 6, wherein an intersection slack absorbing section is formed in the vicinity of an intersection of the partition sections.

8. The side wall portion includes a flange portion connected to the side wall portion and extending in a horizontal direction; The paper container according to claim 1 , further comprising a rolled edge portion formed on an outer periphery of the flange portion.

9. The outer edge is a polygonal shape in which straight lines and curved lines are connected to each other, The paper container according to claim 8, wherein a width of a curved portion of the flange portion, which corresponds to the curved portion and where creases are generated, is greater than a width of a straight portion of the flange portion, which corresponds to the straight portion.

10. The paper container according to claim 9, wherein a plurality of folds extending radially toward the outer edge are formed in parts of the side wall portion, the flange portion, and the rolled edge portion corresponding to the curved portion.

11. The paper container according to claim 10, wherein the creases are formed based on a plurality of radial lines pre-formed in the paperboard base paper.

12. A sheet of paperboard base paper used in press-molding paper containers, a bottom forming portion; a sidewall forming portion connected to the bottom forming portion; at least one partition forming portion, the partition forming portion being connected to the side wall forming portion at at least one location on the inner side of the side wall forming portion and being arranged to partition the bottom forming portion; The paperboard base paper has at least one crease formed in the vicinity of a connection point between the partition portion forming portion and the side wall portion forming portion.

13. a plurality of intersecting partition forming portions; The paperboard base paper according to claim 12, wherein an intersection rule is formed in the vicinity of an intersection of the partition-forming portions.

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