Paper material crimping type and crimping method

Abstract

To improve peel strength of a crimp part of a corrugated cardboard having a wavy corrugated structure, and suppress cracking of a surface layer to enable forming a package that can endure shipping of a product.SOLUTION: In a crimping die, a male die 1 and a female die 2 each has pinching parts 5, 6 on bases 3, 4. The pinching parts 5, 6 each have a plurality of convex teeth 7, 8 forming a parallel wavy cross section via trough streaks 9, 10 to enable engagement with each other. In the male die 1, both end faces of the tooth 7 are each a gradually inclined face 7b having a taper angle between 20° and 45°, an edge 1a of a boundary portion between a top part 7a and the inclined face 7b of the tooth 7 has a rounded shape, and a width of the top part 7a of the tooth 7 of the male die 1 is smaller than a width of a top part 8a of the tooth 8 of the female die 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a crimping mold for pressing together multiple sheets of paper material, including corrugated cardboard, and a crimping method using the crimping mold. [Background technology]

[0002] For the purpose of improving the recyclability of paper materials, a device has been provided that binds multiple sheets of paper together without using staples, glue, thread, string, etc. Patent Document 1 describes the following as a binding die set applicable to such a device.

[0003] This mold set consists of a pair of molds equipped with clamping parts that interlock on opposing surfaces. The pair of molds are used to clamp and press together multiple sheets of paper material that are stacked on top of each other. The clamping parts of the pair of molds are shaped such that multiple convex teeth extend in the width direction from a rectangular base, with grooves running parallel to each other in the length direction, and one or both end faces of the teeth become inclined surfaces that slope in the width direction towards the top.

[0004] This mold set allows you to, for example, bind multiple sheets of paper together to create booklets such as brochures, without tearing them, because the sheets are thin and flexible.

[0005] Incidentally, in recent years, mail-order sales using the internet have become widespread, and the type of packaging shown in Figure 10 has been proposed for shipping these products. This packaging is an envelope-like structure formed by preparing two sheets of corrugated cardboard 11, which is a corrugated core with a liner laminated to one side, placing the cores facing each other, sandwiching the product G, such as a book, between the two sheets of corrugated cardboard 11, and then pressing the two sheets of corrugated cardboard 11 together at the edges 12 and 13 along the two opposing sides of the perimeter.

[0006] The edges 12 along two opposing sides of this packaging extend in the transport direction specified in the manufacturing process of the single-sided corrugated cardboard 11, and the two single-sided corrugated cardboard 11 are bonded together by pressure molding using an adhesive.

[0007] Furthermore, the edges 13 along the other two opposing sides extend in a width direction perpendicular to the transport direction of the single-sided corrugated cardboard 11, and the two single-sided corrugated cardboards 11 are joined together by pressing them together with the joining portion 13a without using adhesive.

[0008] This packaging is formed by the crimping device shown in Figures 11 and 12. This crimping device has a lower plate 21 and an upper plate 22, with the upper plate 22 moving up and down relative to the lower plate 21.

[0009] The lower plate 21 and the upper plate 22 are each provided with a pressing member 23 for bonding and a crimping die 24 for fastening, facing each other. As the lower plate 21 and the upper plate 22 approach each other, bonding is performed by the pressing member 23 and the crimping die 24. The pressing member 23 has an elastic top that forms a continuously elongated flat pressing surface, and the crimping die 24 has a pressing surface with uneven clamping portions formed on the pressing surface of a row of metal blocks.

[0010] To form a package using the crimping device described above, adhesive is applied to the core side of the edges 12 of two single-sided corrugated cardboard sheets 11, the cores of the two single-sided corrugated cardboard sheets 11 are placed facing each other, the product is sandwiched in the middle, and the crimping device is used to clamp one edge 13 with the clamping parts of the opposing crimping molds 24 to fasten and bond the edge 13.

[0011] Then, the two single-sided corrugated cardboard sheets 11 are transported, and when the lower plate 21 and the upper plate 22 are brought close together, they are pressed together by the opposing pressing members 23, and the edges 12 on both sides of the two single-sided corrugated cardboard sheets 11 are bonded together. At the same time, the other edge 13 is pressed together by the pressing parts of the opposing crimping type 24 and bonded together by the fastening part 13a.

[0012] Afterward, the lower plate 21 and the upper plate 22 are separated, and the formed packaging is removed from the crimping device. As shown in Figure 10, the packaging has two sets of opposing edges of single-sided corrugated cardboard 11, with one side edge 12 being bonded and the other side edge 13 being stitched together. Such packaging can be transported as is by attaching a shipping label to the liner, which is the surface of the single-sided corrugated cardboard. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] Patent No. 5080691 [Overview of the Initiative] [Problems that the invention aims to solve]

[0014] However, if the crimping type described in Patent Document 1 is used in the crimping device shown in Figures 11 and 12, and single-sided corrugated cardboard, in which a liner is attached to one side of a corrugated core, or double-sided corrugated cardboard, in which a liner is attached to both sides of a core, is layered to form a package as shown in Figure 10, sufficient adhesion may not be obtained because corrugated cardboard is made up of multiple layers of paper material.

[0015] Therefore, during transportation, there is a risk that the fastening portion 13a of the packaging may peel off, creating a gap between the corrugated cardboard pieces that are pressed together at the edges 13, or that tears may occur near the fastening portion 13a.

[0016] Therefore, this invention aims to improve the peel strength of the compressed portion of corrugated cardboard having a corrugated layer structure, suppress cracking of the surface layer, and create a packaging body that can withstand the transportation of goods. [Means for solving the problem]

[0017] In order to solve the above problems, the present invention provides a crimping die for laminating and crimping a plurality of paper materials, wherein at least one of the plurality of paper materials is a corrugated cardboard with a liner attached to the middle core forming a wavy step, which consists of a male die and a female die for sandwiching the overlapping paper materials, and the male die and the female die each have a clamping portion provided on a base. The clamping portions of the male die and the female die each have a plurality of convex teeth extending in the width direction and arranged in parallel in the length direction via valleys to form a wavy cross-section, and are configured to mesh with each other when facing each other. The widths of the bases of the male die and the female die in the width direction are the same. The male die has gentle inclined surfaces with a taper angle of 20° or more and less than 45° from the base to the top at both end surfaces of the teeth, and the edges at the boundary between the top of the teeth and the inclined surfaces are shaped with rounded corners. The female die has steep inclined surfaces with a taper angle of 45° or more and 70° or less from the base to the top at both end surfaces of the teeth, and there is no flat portion between the base of the inclined surface and the base. It is provided that the width of the top of the teeth in the male die is smaller than the width of the top of the teeth in the female die.

[0018] Also, both shoulders of the base of the male die protrude outward in the width direction from the base of the inclined surface of the teeth, and a flat portion is formed between the base of the inclined surface and the rounded portion of the shoulders.

[0019] Also, in the crimping die for these paper materials, it is provided that the edges at the boundary between the inclined surface of the teeth and the shoulders of the base of the male die, and the outer edges of the shoulders are each provided with rounded corners.

[0020] Furthermore, in the crimping die for these paper materials, when the clamping portions of the male die and the female die are meshed so as to overlap, the inclined surface of the teeth of the male die and the portion from the top of the teeth of the female die to the inclined surface intersect in a side view in the width direction.

[0021] Among a plurality of paper materials, at least one is a cardboard with a liner attached to the middle core forming a corrugated step, and a crimping method using a crimping mold that overlaps and crimps the paper materials, wherein the crimping mold is composed of a male mold and a female mold that sandwich the overlapping paper materials, and the male mold and the female mold each have a clamping portion on a base, and the clamping portions of the male mold and the female mold each have a plurality of convex ridges extending in the width direction, and the teeth are arranged in parallel in the length direction via valleys to form a corrugated cross-section and are opposed to mesh with each other. Both end surfaces of the teeth of the male mold are gentle inclined surfaces having a taper angle of 20° or more and less than 45° from the base to the top, and the edge of the boundary portion between the top of the teeth and the inclined surface is shaped with a rounded edge. The width of the top of the teeth in the male mold is smaller than the width of the top of the teeth in the female mold. It is provided with the above-mentioned constituent requirements. A method of crimping in which the step direction in which the step top of the middle core of the cardboard extends is directed in the length direction of the male mold and the female mold is provided.

[0022] Also, the paper material is a single-sided cardboard with a liner attached only to one side of the middle core, and two single-sided cardboards are overlapped with their middle cores facing each other.

[0023] Also, in this crimping method, the dimensional ratio of the tooth height, which is the height of each tooth of the male mold and the female mold from the valley of the tooth, to the total paper thickness, which is the total of the paper thicknesses of the individual base papers constituting the overlapped single-sided cardboard, is such that the total paper thickness / tooth height is 0.4 times or more and 1.4 times or less.

Advantages of the Invention

[0024] The crimping die according to this invention has gently sloping surfaces on both ends of the teeth of the male clamping part, rounded edges on the clamping part, and the width of the top of the teeth of the male type is set to be smaller than the width of the top of the teeth of the female type. Therefore, when multiple sheets of paper material, including corrugated cardboard, are stacked and crimped using this crimping die, the stacked paper materials are smoothly compressed and come into strong contact with each other, resulting in sufficient peel strength without cracking of the corrugated cardboard surface. [Brief explanation of the drawing]

[0025] [Figure 1] Perspective views showing the male and female types of the first embodiment of the paper material crimping mold according to this invention. [Figure 2] A diagram showing the details of each side and clamping section of the male type shown above. [Figure 3] A diagram showing the details of each side and clamping section of the female mold shown above. [Figure 4] A side view in the width direction showing the male and female clamping parts facing each other. [Figure 5] A widthwise side view showing the meshing state of the clamping parts of the male and female types shown above. [Figure 6] A widthwise side view showing the male and female clamping portions facing each other in the second embodiment of the paper material crimping type according to this invention. [Figure 7] A widthwise side view showing the meshing state of the clamping parts of the male and female types shown above. [Figure 8] A widthwise side view showing the state of single-sided corrugated cardboard before crimping using the crimping method of the first embodiment described above. [Figure 9] Side view in the width direction showing the crimping process described above. [Figure 10] (a) Perspective view showing a package made by pressing together two pieces of single-sided corrugated cardboard; (b) Side view from the bonded edge. [Figure 11] Perspective view showing a crimping device for forming the above-mentioned packaging. [Figure 12] Side view showing the state during crimping as described above. [Figure 13] Diagram showing the specified names for the male and female parts related to peeling tests. [Modes for carrying out the invention]

[0026] <Crimping type> As shown in Figure 1, this crimping die consists of a metal male die 1 and a female die 2. Male die 1 and female die 2 are each equipped with clamping parts 5 and 6 on bases 3 and 4. The clamping parts 5 and 6 each have multiple convex teeth 7 and 8 extending in the width direction, which are parallel in the length direction via grooves 9 and 10, forming a wavy cross section that meshes with each other when facing each other. The width dimensions of the bases 3 and 4 of male die 1 and female die 2 are the same.

[0027] As shown in Figure 2, the male mold 1 has gently sloping surfaces 7b on both ends of the teeth 7, with a taper angle α of 20° or more and less than 45° from the base 3 to the apex 7a. A taper angle α of 25° or more and 35° or less is more preferable. A taper angle α greater than this is unsuitable because the effect is diminished. Furthermore, a taper angle α smaller than this is unsuitable because the width of the apex 7a becomes extremely narrow relative to the base 3, requiring an increase in the width of the base 3 to secure the necessary length of the apex 7a, which causes equipment inconvenience.

[0028] This male type 1 is based on the first embodiment, in which both shoulder portions 3a of the base 3 protrude outward in the width direction from the base of the inclined surface 7b, a flat portion is formed between the base of the inclined surface 7b and the rounded portion of the shoulder portion 3a, and the edges 1a at the boundary between the top portion 7a of the tooth 7 and the inclined surface 7b, the edges 1b at the boundary between the inclined surface 7b of the tooth 7 and the shoulder portion 3a of the base 3, and the outer edge 1c of the shoulder portion 3a are all rounded.

[0029] As shown in Figure 3, the female mold 2 has steeply inclined surfaces 8b on both end faces of the tooth 8, with a taper angle β of 45° or more and 70° or less from the base 4 to the apex 8a, and the edge 2a at the boundary between the apex 8a of the tooth 8 and the inclined surface 8b is rounded. If the taper angle β is larger than this, it is unsuitable because the effect is reduced. Also, if the taper angle β is smaller than this, since the male mold 1 also has a taper, the width of the apex 8a of the female mold 2 may become narrower than that of the male mold 1, in which case it is unsuitable because it will hinder bonding. In the female mold 2, there is no flat portion formed between the base of the inclined surface 8b of the tooth 8 and the base 4.

[0030] Then, as shown in Figure 4, when the clamping portions 5 and 6 of the male type 1 and the female type 2 are placed opposite each other, and as shown in Figure 5, when the clamping portions 5 and 6 of the male type 1 and the female type 2 are engaged so that they overlap, the inclined surface 7b of the teeth 7 of the male type 1 and the parts on both ends of the top 8a of the teeth 8 of the female type 2 intersect at intersection point K in a side view in the width direction.

[0031] Furthermore, in the male type 1, as shown in the second embodiment in Figure 6, there is no portion on the base 3 that protrudes outward from the base of the inclined surface 7b of the tooth 7, and there are also cases where there are no portions corresponding to both shoulder portions 3a shown in the first embodiment.

[0032] Furthermore, as shown in Figures 5 and 7, when the clamping portions 5 and 6 of the male type 1 and the female type 2 are engaged so as to overlap, the position of the intersection point K where the inclined surface 7b of the teeth 7 of the male type 1 and the inclined surface 8b of the teeth 8 of the female type 2 intersect in a widthwise side view changes depending on the taper angle α of the inclined surface 7b of the teeth 7 of the male type 1, the taper angle β of the inclined surface 8b of the teeth 8 of the female type 2, and the presence or absence of both shoulder portions 3a of the base 3 of the male type 1 (see Figures 4 and 6). As shown in Figure 7, a configuration in which the inclined surface 7b of the teeth 7 of the male type 1 and the inclined surface 8b of the teeth 8 of the female type 2 intersect at the intersection point K in a widthwise side view is also conceivable.

[0033] <Crimping using a crimping tool> (Crimping method) As shown in Figures 8 and 9, in order to crimp two single-sided corrugated cardboard sheets 11, each with a liner 11b attached to only one side of the core 11a, using the crimping dies described above, the male die 1 and female die 2 are attached to the crimping device shown in Figure 11 in place of the crimping die 24. In Figures 8 and 9, the crimping dies of the first embodiment are shown.

[0034] Then, the two single-sided corrugated cardboard sheets 11 are placed on top of each other with their cores 11a facing each other, and the corrugation direction where the tops of the cores 11a extend is oriented in the longitudinal direction of the male mold 1 and the female mold 2, and the two single-sided corrugated cardboard sheets 11 are sandwiched between the clamping parts 5 and 6 of the male mold 1 and the female mold 2.

[0035] Here, in relation to the single-sided corrugated cardboard 11, the crimping type is such that the tooth heights h and h' of the teeth 7 and 8 of the male type 1 and female type 2, respectively, from the valleys 9 and 10, are lower than the wave height H of the core 11a of the single-sided corrugated cardboard 11, and the dimensional ratio of the tooth heights h and h' of the male type 1 and female type 2 to the total paper thickness, which is the sum of the thicknesses of the individual base papers constituting the overlapped single-sided corrugated cardboard 11, is such that the total paper thickness / tooth height is 0.4 times or more and 1.4 times or less. In calculating this total paper thickness, the corrugation ratio, which is the ratio of the length of the core 11a to the length of the liner 11b, is used. For example, when two single-sided corrugated cardboard 11 are overlapped, it is (thickness of liner base paper + thickness of core base paper × corrugation ratio) × 2, and when two double-sided corrugated cardboard are overlapped, it is (thickness of liner base paper + thickness of core base paper × corrugation ratio + thickness of liner base paper) × 2.

[0036] Furthermore, the crimping type is configured such that the width w1 of the top 7a of the teeth 7 in the male mold 1 is smaller than the width w'1 of the top 8a of the teeth 8 in the female mold 2.

[0037] (effect) With the crimping die described above, both end faces of the teeth 7 of the clamping part 5 of the male die 1 are made into gently sloping surfaces 7b, the edges 1a, 1b of the clamping part 5 and the edges 1c of the shoulders 3a of both the clamping part 5 and the base 3 are rounded, and the width w1 of the top 7a of the teeth 7 of the male die 1 is set to be smaller than the width w'1 of the top 8a of the teeth 8 of the female die 2. Therefore, when two single-sided corrugated cardboard sheets 11 are stacked and crimped using this crimping die, the stacked single-sided corrugated cardboard sheets 11 are smoothly compressed and come into strong contact with each other, and sufficient peel strength is obtained without surface cracking of the single-sided corrugated cardboard sheets 11.

[0038] In particular, when two single-sided corrugated cardboard sheets 11 are stacked with their cores 11a facing each other, it is presumed that the peel strength is improved as the cores 11a of the single-sided corrugated cardboard sheets 11 are smoothly folded into an S-shape during compression, and the cores 11a overlap each other in multiple layers, making strong contact with each other and entering into wrinkles. [Examples]

[0039] <Specific examples and verification of crimping type> To verify what shape and dimensions of the crimping type would provide sufficient adhesion and crack suppression, the dimensions of each part of the male and female types were defined as shown in Figure 13, and samples under various conditions shown in Table 1 were prepared using these dimensions as parameters. Paper materials shown in Table 2 were used as the materials for crimping. For each sample, the crack suppression effect during material crimping was visually confirmed, and peel tests (first test) to evaluate adhesion were performed, and the results are shown in Table 3. Furthermore, for the embodiment of the first test, peel tests (second test) were performed with varying relationships between the total paper thickness of the material and the tooth height, and the results are shown in Table 4.

[0040] (Paper material) As shown in [Table 2], the paper material used in the first test had a liner (LC) basis weight of 120 g / m². 2 The core (MC) has a basis weight of 115g / m². 2 This is a single-sided corrugated cardboard made of E-flute (EF), with the liner and core bonded together. The thickness of the single-sided corrugated cardboard sheet (flute thickness) is approximately 1.5 mm, and the corrugation ratio is 1.25.

[0041] Also, in the second test, an E-flute (EF) single-wall corrugated board with a flute thickness of 1.5 mm and a step-up ratio of 1.25, made of kraft paper with a basis weight of 50 g / m 2 a single-wall corrugated board of E-flute (EF) with the specifications used in the first test, a single-wall corrugated board of B-flute (BF) with a flute thickness of 3.0 mm and a step-up ratio of 1.40, made of a liner with a basis weight of 160 g / m 2 and a medium with a basis weight of 120 g / m 2 a single-wall corrugated board of B-flute (BF) with a flute thickness of 3.0 mm and a step-up ratio of 1.40, made of two liners with a basis weight of 160 g / m 2 and a medium with a basis weight of 120 g / m 2 a double-wall corrugated board of E-flute (EF) with a flute thickness of 1.5 mm and a step-up ratio of 1.25, made of two liners with a basis weight of 160 g / m 2 and a medium with a basis weight of 120 g / m 2 and a double-wall corrugated board of B-flute (BF) with a flute thickness of 3.0 mm and a step-up ratio of 1.40, made of two liners with a basis weight of 160 g / m

[0042] These paper materials were conditioned for 24 hours or more in an environment of 23°C and 50% RH, bonded using a hydraulic pressure of 15 bar with a press machine, conditioned for 24 hours or more in an environment of 23°C and 50% RH, and then a peel test was conducted.

[0043] (Peel Test Method) The peel test was carried out based on "7.4 Heat Seal Strength Test" of JIS Z 1707 General Rules for Plastic Films for Food Packaging and modified.

[0044] The apparatus used was the Autograph AGS-X manufactured by Shimadzu Corporation. The test specimen was 50 mm wide, and both ends of the specimen were clamped with chucks so that the distance between the chucks was 50 mm, and the specimen was opened 180° so that the compressed part was in the center between the chucks. The specimen was pulled at a tensile speed of 300 mm / min until the compressed part peeled off, and the peel strength (N) was measured to observe the crack suppression and adhesion. Regarding adhesion, the specimens were broadly classified into those that bonded and those that did not. Furthermore, among those that bonded, the specimens were observed in three categories during the peel test: material fracture (a phenomenon in which the bonded part is strongly bonded, and the part other than the bonded part breaks when peeled), partial material fracture, and pseudo-bonding (a phenomenon in which the bond is weak, and the bonded part completely separates when peeled).

[0045] In this peel test, comparative examples were fabricated with varying parameters such as shoulder edge shape, tooth taper angle, tooth width, and tooth height, while an example was fabricated with the shoulder edge shape, tooth taper angle, and tooth width kept constant, and only the tooth height and the flat portion of the male mold were changed. The results of each sample were then analyzed.

[0046] [Table 1]

[0047] [Table 2]

[0048] [Table 3]

[0049] [Table 4]

[0050] (Test results) In the first test, while the adhesive properties were good in both the comparative example and the example, it was found that the crack suppression effect was influenced by the shoulder edge shape, tooth taper angle, and tooth width. Based on these results, in the second test, which involved increasing the types of paper materials used in the example, samples F, G, and H (tooth height: 0.88 mm, 0.99 mm) performed well in terms of adhesive properties for single-sided corrugated cardboard, and sample F (tooth height: 0.99 mm) performed well for double-sided corrugated cardboard.

[0051] (verification) From this, it was confirmed that by rounding the shoulder edge of the male type, setting the taper angle of the male type teeth (α in Table 1) to 20° or more and less than 45°, more preferably 25° or more and less than 35°, setting the taper angle of the female type teeth (β in Table 1) to 45° or more and 70° or less, and setting the dimensional ratio of the tooth heights of the male and female types (male type: h, female type: h' in Table 1) to the total paper thickness, which is the sum of the thicknesses of the individual base papers that make up the stacked corrugated cardboard, such that the total paper thickness / tooth height is 0.4 times or more and 1.4 times or less, sufficient adhesion can be obtained without cracking in the liner, which is the surface layer of single-sided corrugated cardboard.

[0052] Under these conditions, it is presumed that the rounded edges on the shoulders of the male type made the surface of the single-sided corrugated cardboard less prone to cracking, improving impact resistance during compression. Furthermore, it is presumed that making the taper angle of the teeth of the male and female types gentler than in the comparative example also made the surface of the corrugated cardboard less prone to cracking, improving impact resistance during compression.

[0053] Furthermore, since the tooth width (in Table 1, male type: W, female type: W') was set larger than in the comparative example, it is presumed that the bonding area between the single-sided corrugated cards increased, improving stability during bonding and enhancing the crack suppression effect. In addition, since the tooth height (in Table 1, male type: h, female type: h') was set larger than in the comparative example, it is presumed that the overlapping single-sided corrugated cards were compressed more strongly, improving the adhesive properties.

[0054] Furthermore, when the paper material sandwiched between the male and female molds is a corrugated core with a liner attached, in addition to cases where both sheets are single-sided corrugated cardboard, in cases where single-sided corrugated cardboard is combined with a single-sheet paper material such as kraft paper, in cases where double-sided corrugated cardboard is combined with single-sided corrugated cardboard, in cases where both sheets are double-sided corrugated cardboard, or in cases where three or more sheets of paper material including single-sided or double-sided corrugated cardboard are used, it is understood that improved adhesion and crack suppression effects can be expected when corrugated cardboard with a liner attached to a core, where at least one sheet forms a corrugated ridge, is compressed. [Explanation of Symbols]

[0055] 1 Male type 1a, 1b, 1c Edge 2 Female type 2a Edge 3,4 Base 3a Shoulder 5,6 Clamping section 7,8 teeth 7a,8a top 7b,8b Slope 9,10 Valley 11 Single-sided corrugated cardboard 11a Middle core 11b Raina 12,13 Edge 13a Binding section 21 Lower board 22 Upper panel 23 Pressing member 24 Crimp type

Claims

1. In a crimping type, at least one of the multiple sheets of paper material is a corrugated cardboard (11) in which a liner (11b) is attached to a corrugated core (11a), and the paper materials are overlapped and pressed together. The device consists of a male mold (1) and a female mold (2) that sandwich the overlapping paper material, and the male mold (1) and the female mold (2) each have a base (3,4) with a clamping section (5,6), and the clamping sections (5,6) of the male mold (1) and the female mold (2) each have multiple convex teeth (7,8) extending in the width direction, which are parallel in the length direction via valleys (9,10) and form a wavy cross section, and are arranged to interlock with each other when facing each other, and the width dimensions of the bases (3,4) of the male mold (1) and the female mold (2) are the same. The male mold (1) has both end faces of the teeth (7) as gently inclined surfaces (7b) with a taper angle of 20° or more and less than 45° from the base (3) to the top (7a), and the edge (1a) of the boundary between the top (7a) and the inclined surface (7b) of the teeth (7) is rounded. The female mold (2) has both end faces of the teeth (8) as steeply inclined surfaces (8b) that have a taper angle of 45° or more and 70° or less from the base (4) to the top (8a), and there is no flat portion between the base of the inclined surface (8b) and the base (4). A crimping mold for paper material, characterized in that the width (w1) of the top (7a) of the teeth (7) in the male mold (1) is smaller than the width (w'1) of the top (8a) of the teeth (8) in the female mold (2).

2. The paper material crimping mold according to claim 1, characterized in that both shoulder portions (3a) of the base (3) of the male mold (1) protrude outward in the width direction from the base of the inclined surface (7b) of the teeth (7), and a flat portion is formed between the base of the inclined surface (7b) and the rounded portion of the shoulder portion (3a).

3. The paper material crimping mold according to claim 2, characterized in that the male mold (1) has rounded edges on the inclined surface (7b) of the teeth (7) and the boundary portion (1b) of the shoulder portion (3a) of the base (3), and on the outer edge (1c) of the shoulder portion (3a).

4. The paper material crimping mold according to claim 3, characterized in that when the clamping portions (5,6) of the male mold (1) and the female mold (2) are engaged so as to overlap, the inclined surface (7b) of the teeth (7) of the male mold (1) and the portion of the teeth (8) of the female mold (2) from the top (8a) to the inclined surface (8b) intersect in a widthwise side view.

5. A crimping method using a crimping die in which, among multiple sheets of paper material, at least one sheet is a corrugated cardboard (11) in which a liner (11b) is attached to a corrugated core (11a), and the paper materials are overlapped and pressed together, wherein the crimping die is It consists of a male mold (1) and a female mold (2) that sandwich the overlapping paper material, and the male mold (1) and the female mold (2) each have a base (3,4) with a clamping part (5,6), and the clamping parts (5,6) of the male mold (1) and the female mold (2) each have a plurality of convex teeth (7,8) extending in the width direction, which are parallel in the length direction via valleys (9,10) and form a wavy cross section, and are arranged to interlock with each other when facing each other. The male mold (1) has both end faces of the teeth (7) as gently inclined surfaces (7b) with a taper angle of 20° or more and less than 45° from the base (3) to the top (7a), and the edge (1a) of the boundary between the top (7a) and the inclined surface (7b) of the teeth (7) is rounded. The width (w1) of the apex (7a) of the tooth (7) in the male mold (1) is smaller than the width (w'1) of the apex (8a) of the tooth (8) in the female mold (2). It shall have the following constituent requirements, A method for crimping paper materials, characterized in that the direction in which the crests of the corrugated cardboard (11a) extend is crimped in the direction of the length of the male mold (1) and the female mold (2).

6. In the method for pressing paper materials according to claim 5, A method for compressing paper materials, characterized in that the paper material is a single-sided corrugated cardboard (11) in which a liner (11b) is attached only to one side of the core (11a), and two single-sided corrugated cardboards (11) are stacked on top of each other with their cores (11a) facing each other.

7. In the method for compressing paper materials according to claim 5 or 6, A method for crimping paper materials, characterized in that the crimping mold has a dimensional ratio of tooth height (h, h'), which is the height of the teeth (7, 8) of the male mold (1) and the female mold (2) from the grooves (9, 10), to the total paper thickness, which is the sum of the paper thicknesses of the individual base papers constituting the stacked single-sided corrugated cardboard (11), such that the total paper thickness / tooth height is 0.4 times or more and 1.4 times or less.

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