Mold set, method for manufacturing shower using the mold set, and shower

Abstract

The purpose of the present invention is to provide a mold set that can be used when manufacturing a suction tube having a corrugated structure using an aliphatic polyester resin as a raw material, in a mold set (100), each mountain portion (14) of an inner mold (10) has a top portion having an R-surface, each mountain portion (24) of an outer mold (20) has a top portion having an R-surface, the length of each mountain portion (14) in the LD direction is 1.50 mm to 1.80 mm, and the length of each mountain portion (24) in the LD direction is 1.50 mm to 1.80 mm. And the length of each mountain part (24) is 1.50 mm to 1.80 mm.

Description

The manufacturing method of the mold assembly and the straw using the mold assembly, and the straw. Technical Field

[0001] This invention relates to a mold assembly, a method for manufacturing a straw using the mold assembly, and a straw. Background Technology

[0002] To achieve a straw that can extend or bend, techniques are known to form a corrugated structure in the straw body as an extension or bending portion. For example, Patent Document 1 discloses a straw made of thermoplastic resin with an extension portion. The extension portion of Patent Document 1 has a small-diameter portion, a large-diameter portion, and an inclined side portion located between the small-diameter portion and the large-diameter portion, wherein the small-diameter portion and the large-diameter portion are interconnected via the side portion. In the contracted state of the extension portion of Patent Document 1, the side portion folds back relative to the small-diameter portion and the large-diameter portion, overlapping each other. Patent Document 1 also discloses a mold assembly for forming the extension portion.

[0003] Furthermore, Patent Document 2 discloses a technique not related to straws made of thermoplastic resin, but rather a technique for forming a corrugated tube by creating an uneven surface on the outer peripheral wall of a tube formed from a thin-walled cylindrical body. In the technique of Patent Document 2, a mold is used, comprising a punch having uneven portions on its outer peripheral surface along its circumferential direction, and a die engaging with the uneven surfaces of the punch. Then, by positioning the outer peripheral wall of the tube between the punch and the die, rotating the punch, and simultaneously pressing the die into the punch, a corrugated tube is formed.

[0004] In addition, aliphatic polyester resins are used for various applications. Among them, biodegradable resins such as poly(3-hydroxyalkanoate) resins (hereinafter sometimes referred to as "P3HA resins") are attracting attention as environmentally friendly resins due to their biodegradability. Using these biodegradable resins as raw materials, efforts are underway to develop straws with corrugated structures.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 59-020120

[0008] Patent Document 2: Japanese Patent Application Publication No. 58-131036 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, if the mold set of Patent Document 1 or 2 is used and aliphatic polyester resins such as biodegradable resins are used as raw materials to mold the corrugated structure of the straw, there is a problem that the curved part of the corrugated structure may be crushed or destroyed, making it impossible to manufacture a straw that can be used in practice. Therefore, the mold set of Documents 1 and 2 cannot be improved in this respect when manufacturing straws with corrugated structures using aliphatic polyester resins such as biodegradable resins as raw materials.

[0011] One objective of the present invention is to realize a mold set that can be used when manufacturing a straw with a corrugated structure using aliphatic polyester resins such as biodegradable resins as raw materials, a method for manufacturing a straw using the mold set, and a straw.

[0012] Problem Solving Methods

[0013] To address the aforementioned problems, one embodiment of the present invention provides a mold assembly for forming a corrugated structure on a cylindrical straw body. This mold assembly comprises: a rod-shaped inner mold inserted into the interior of the straw body, and a rod-shaped outer mold that extrudes the straw body from the outside. The inner mold has a first protrusion / recess forming the ridge portion of the corrugated structure. The first protrusion / recess has: a first axial portion extending along the axial direction of the straw body, and a plurality of first... The outer mold has a second concave-convex portion forming the valley portion of the corrugated structure. The second concave-convex portion has: a second shaft portion arranged parallel to the first shaft portion; a plurality of second shaft portions that protrude radially relative to the second shaft portion along the outer mold and are respectively inserted between two adjacent first shaft portions; each first shaft portion has a first top with an R-surface; and each second shaft portion has a second top with an R-surface. In the axial direction of the straw body, the length of each first shaft portion is 1.50mm to 1.80mm, and the length of each second shaft portion is 1.50mm to 1.80mm.

[0014] In addition, to solve the above problems, another aspect of the present invention is a straw in which a corrugated structure is formed on a cylindrical straw body containing an aliphatic polyester resin, wherein the wall thickness of the straw body is 0.18 mm to 0.22 mm.

[0015] The effects of the invention

[0016] According to these methods of the present invention, a mold assembly that can be used when manufacturing a straw with a corrugated structure using aliphatic polyester resins such as biodegradable resins as raw materials can be realized. Attached Figure Description

[0017] Figure 1 shows the general structure of the mold assembly according to an embodiment of the present invention, 1001 is a side view and 1002 is a rear view viewed from the rear.

[0018] Figure 2 is a side view showing the general structure of the concave and convex parts of the inner mold shown in Figure 1.

[0019] Figure 3 is a side view showing the general structure of the concave and convex parts of the outer mold shown in Figure 1.

[0020] In Figure 4, 4001 to 4003 are schematic diagrams illustrating an example of the corrugated structure forming process in the straw manufacturing method according to an embodiment of the present invention.

[0021] Figure 5 is a cross-sectional view showing the general structure of the corrugated structure of the straw according to an embodiment of the present invention.

[0022] Symbol Explanation

[0023] 10 Inner mold

[0024] 12. Uneven part (first uneven part)

[0025] 13 Shaft Section (First Shaft Section)

[0026] 14 Yamabe (1st Yamabe)

[0027] 14a Inclined surface (first inclined surface)

[0028] 14c Top (First Top)

[0029] 20 Outer mold

[0030] 22. Concave-convex portion (second concave-convex portion)

[0031] 23 Shaft section (2nd shaft section)

[0032] 24 Yamabe (2nd Yamabe)

[0033] 24a Inclined surface (second inclined surface)

[0034] 24c Top (Second Top)

[0035] 30 straws

[0036] 31 Straw Body

[0037] 32. Corrugated structure

[0038] 32a Long side

[0039] 32b Short side

[0040] 32c and 32d edges (the connecting part between the long and short sides)

[0041] 32E Ridge Section

[0042] 32F Valley Section

[0043] 100 mold sets Detailed Implementation

[0044] One embodiment of the present invention will be described in detail below. It should be noted that, unless otherwise specified, "A~B" in this specification refers to "above A and below B". Furthermore, the entire contents of the documents described in this specification are incorporated herein by reference.

[0045] [Technical Ideas]

[0046] As disclosed in Patent Document 1, the technique for forming a corrugated structure on the straw body uses a mold assembly comprising an inner mold and an outer mold. The inner mold is inserted into the interior of the straw body and has uneven portions forming the ridge portion of the corrugated structure. The outer mold presses the straw body from the outside and has uneven portions forming the valley portion of the corrugated structure.

[0047] Next, the corrugated structure is formed on the straw body through the following process: a shaping process in which the above-mentioned mold assembly is placed on the straw body, the inner mold and the outer mold are rotated in opposite directions, and the outer mold is pressed against the outside of the straw body, thereby shaping the ridge and valley portions of the corrugated structure on the straw body; and a folding process in which the mold assembly is removed from the straw body after the shaping process, the shaped portions of the straw body are compressed from both sides and folded.

[0048] Therefore, the inventors of this application discovered that when using aliphatic polyester resins such as biodegradable resins as the raw material for the straw body, if the aforementioned mold assembly is used to mold the corrugated structure, the extrusion during the molding process causes the ridges of the curved portions (valley portions or ridge portions) of the straw body to whiten and crack. Furthermore, the inventors of this application also discovered that the compression of the molding portion during the folding process similarly causes the ridges of the curved portions of the straw body to whiten and crack. Therefore, the inventors of this application have devoted considerable effort to developing a mold assembly that can be used to manufacture straws with corrugated structures even when using aliphatic polyester resins such as biodegradable resins as the raw material for the straw body.

[0049] The inventors of this application believe that if a mold assembly can form a corrugated structure on a straw body with a relatively large wall thickness, it is possible to manufacture a usable straw that does not crack in the curved part of the corrugated structure. This can be used in the manufacture of straws with corrugated structures, and the inventors of this application have conducted in-depth research. As a result, the inventors of this application have discovered that, for the mold assembly, (1) by setting the length of each mountain (protrusion) of the concave and convex parts of the inner mold and the length of each mountain (protrusion) of the concave and convex parts of the outer mold to a specific numerical range in the axial direction of the straw body; and (2) by setting the top of each mountain of the concave and convex parts of the inner mold and the top of each mountain of the concave and convex parts of the outer mold to an R-surface, it is possible to manufacture a usable straw with a corrugated structure, and this embodiment can be completed.

[0050] That is, the mold assembly of this embodiment is a mold assembly for forming a corrugated structure on a cylindrical straw body. The mold assembly includes: a rod-shaped inner mold inserted into the interior of the straw body, and a rod-shaped outer mold that extrudes the straw body from the outside. The inner mold has a first uneven portion forming the ridge portion of the corrugated structure. The first uneven portion has: a first axial portion extending along the axial direction of the straw body, and a plurality of first ridge portions protruding radially relative to the first axial portion along the inner mold and arranged at given intervals along the axial direction of the straw body. The side mold has a second concave-convex portion forming the valley portion of the above-mentioned corrugated structure. The second concave-convex portion has a second shaft portion arranged parallel to the first shaft portion, and a plurality of second mountains that protrude radially relative to the second shaft portion along the outer mold and are respectively inserted between two adjacent first mountains. Each first mountain portion has a first top with an R-face, and each second mountain portion has a second top with an R-face. In the axial direction of the straw body, the length of each first mountain portion is 1.50mm to 1.80mm, and the length of each second mountain portion is 1.50mm to 1.80mm.

[0051] In addition, the straw in this embodiment is a straw with a corrugated structure formed on a cylindrical straw body containing an aliphatic polyester resin, and the wall thickness of the straw body is 0.18 mm to 0.22 mm.

[0052] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. As shown in the drawings, the length direction (axial direction) of the straw body is referred to as the LD direction, and in the LD direction, one side (front side) is designated as the LTa side and the other side (rear side) is designated as the LDb side.

[0053] (Structure of the mold assembly)

[0054] Figure 1 shows the general structure of the mold assembly 100 of this embodiment. Figure 1001 is a side view and Figure 1002 is a rear view viewed from the LDb side. As shown in Figures 1001 and 1002, the mold assembly 100 includes an inner mold 10 and an outer mold 20.

[0055] The inner mold 10 is a cylindrical rod-shaped component that is inserted into the interior of the cylindrical straw body. The diameter of the inner mold 10 is slightly smaller than the inner diameter of the straw body. Here, the radial direction of the inner mold 10 is defined as the RD1 direction.

[0056] The inner mold 10 has a cylindrical body portion 11 extending along the LD direction, and the body portion 11 has a concave-convex portion 12 (first concave-convex portion). The concave-convex portion 12 forms the ridge portion of the corrugated structure of the straw body. The term "ridge portion" here refers to the curved portion in the corrugated structure where the ridge line is located on the outer side.

[0057] The protrusion / concave portion 12 has a shaft portion 13 (first shaft portion) and a plurality of ridge portions 14 (first ridge portions). The shaft portion 13 extends along the LD direction and is coaxial with the portion of the body portion 11 other than the protrusion / concave portion 12. The ridge portions 14 protrude in the RD1 direction relative to the shaft portion 13. The ridge portions 14 are truncated cones about the shaft portion 13. Furthermore, the ridge portions 14 are arranged at given intervals along the LD direction.

[0058] The outer mold 20 is a component having a cylindrical side surface that extrudes the straw body from the outside. The diameter of the outer mold 20 is not particularly limited, but is preferably 5 mm to 60 mm, more preferably 10 mm to 40 mm. Here, the radial direction of the outer mold 20 is set as the RD2 direction.

[0059] The outer mold 20 is arranged opposite to the inner mold 10's protrusion 12, such that the inner mold 10's protrusion 12 and the outer mold 20 clamp the wall of the straw body. The outer mold 20 has a protrusion 22 (second protrusion). The protrusion 22 forms the valley portion of the corrugated structure of the straw body. Here, "valley portion" refers to the curved portion of the corrugated structure where the ridge line is located on the inside.

[0060] The concave-convex portion 22 has a shaft portion 23 (second shaft portion) and a plurality of mountain portions 24 (second mountain portions). The shaft portion 23 is arranged parallel to the shaft portion 13. That is, the shaft portion 23 extends in the LD direction. The mountain portions 24 protrude in the RD2 direction relative to the shaft portion 23. The mountain portions 24 are truncated cones about the shaft portion 23. In addition, the mountain portions 24 are arranged at a given interval in the LD direction. The mountain portions 24 are configured to be inserted between two adjacent mountain portions 14 in the concave-convex portion 12.

[0061] (The structure of the concave and convex parts of the inner mold)

[0062] Figure 2 is a side view showing the general structure of the protrusion 12 of the inner mold 10. As shown in Figure 2, in the protrusion 12, the hill 14 has a top 14c (first top) and an inclined surface 14a extending from the top 14c to the LDa side. More specifically, the hill 14 is a frustum-shaped cone about the axis X of the shaft 13, and is composed of the inclined surface 14a, a rear end surface 14b, and a front end surface 14d. The inclined surface 14a is a surface inclined relative to the axis X1 of the shaft 13, and is inclined in a manner that the distance from the shaft 13 decreases from the LDb side to the LDa side. In addition, the rear end surface 14b and the front end surface 14d are connected to the LDb side and the LDa side of the inclined surface 14a, respectively. The rear end surface 14b and the front end surface 14d are the end faces of the LDb side and the LDa side of the hill 14, respectively. Furthermore, the top 14c is the connection between the inclined surface 14a and the rear end surface 14b, and it is the part of the mountain 14 furthest from the shaft 13. It can be said that the top 14c is the edge part in the frustum-shaped mountain 14 described above.

[0063] The surface of the concave and convex portion 12 is a surface that alternately repeats from the LDb side to the LDa side, the surface 13a of the shaft portion 13 and the rear end surface 14b, inclined surface 14a and front end surface 14d of the mountain portion 14.

[0064] In the ridge portion of the corrugated structure of the straw body, the top 14c of the uneven portion 12 forms a ridge line. In the mold assembly 100 of this embodiment, the top 14c of each ridge 14 has an R-surface. Therefore, even if the inner surface of the straw body is strongly pressed against the uneven portion 12 by the pressure of the outer mold 20, cracks are not easily generated in the ridge portion of the corrugated structure. Therefore, in order to form the curved portion of the corrugated structure without generating cracks, the top 14c of the uneven portion 12 can be pressed against the inner surface of the straw body with a strong force.

[0065] From the viewpoint that the top 14c of the concave-convex portion 12 abuts against the surface with a strong force, the radius of curvature of the R-surface of the top 14c is preferably 0.01 mm to 1.00 mm, more preferably 0.05 mm to 0.20 mm. The radius of curvature of the R-surface of the top 14c is, for example, 0.10 mm.

[0066] Furthermore, in the mold assembly 100, in the LD direction, the length L1 of each mountain portion 14 of the concave-convex portion 12 is 1.50mm to 1.80mm, preferably 1.55mm to 1.77mm, and more preferably 1.60mm to 1.75mm. By making the length L1 within the above-mentioned range, even if the thickness of the ridge portion is relatively large, it can be achieved by using a ridge that can be folded along the ridgeline. Even for a straw body with a relatively large wall thickness, a corrugated structure can be formed. The length L1 is, for example, 1.64mm.

[0067] Furthermore, the larger the inclination angle θ1 of the inclined surface 14a relative to the shaft portion 13, the stronger the force required to bring the top 14c of the protrusion 12 into contact with the inner surface of the straw body. From this perspective, the inclination angle θ1 is preferably 30.0° to 40.0°, more preferably 30.0° to 35.0°. For example, the inclination angle θ1 is 31.07°.

[0068] Furthermore, the greater the distance H1 between the top 14c and the shaft portion 13, the deeper the groove formed by the two adjacent ridge portions 14. The deeper the groove, the stronger the force required to bring the top 14c of the protrusion 12 into contact with the inner surface of the straw body. From this perspective, the distance H1 between the top 14c and the shaft portion 13 is preferably 1.10mm to 1.80mm, more preferably 1.30mm to 1.70mm. For example, a distance H1 of 1.49mm is suitable.

[0069] Furthermore, in the concave-convex portion 12, if the distance (pitch) P1 between two adjacent mountain portions 14 is large, then the relatively thick ridge portion can be folded along the ridgeline. From this perspective, the distance P1 between two adjacent mountain portions 14 is preferably 2.20 mm to 2.50 mm, more preferably 2.25 mm to 2.40 mm. It should be noted that the distance P1 between two adjacent mountain portions 14 refers to the distance between the two tops 14c of the two adjacent mountain portions 14. For example, distance P1 is 2.3 mm.

[0070] Furthermore, in the two adjacent hill sections 14, the distance D1 between the rear end face 14b of one hill section 14 and the front end face 14d of the other hill section 14 is not particularly limited, but is preferably 0.2mm to 0.8mm, more preferably 0.4mm to 0.7mm. By keeping the distance D1 within the above-mentioned range, the contact portion between the portion of the uneven part 12 (excluding the top 14c) and the straw body can be reduced. This reduces the contact between the mold and the straw (excluding the ridge line 32d) of the well-appearing corrugated straw structure, thereby improving the appearance. For example, the distance D1 is 0.6mm.

[0071] (The structure of the concave and convex parts of the outer mold)

[0072] Figure 3 is a side view showing the general structure of the protrusion 22 of the outer mold 20. As shown in Figure 3, in the protrusion 22, the mountain 24 has a top 24c (second top) and an inclined surface 24a extending from the top 24c along the LDb side. More specifically, the mountain 24 is a frustum-shaped cone about the axis X2 of the shaft 23, and is composed of the inclined surface 24a, a front end surface 24b, and a rear end surface 24d. The inclined surface 24a is an inclined surface relative to the axis X2 of the shaft 23, and is inclined such that the distance from the shaft 23 decreases from the LDa side to the LDb side. In addition, the front end surface 24b and the rear end surface 24d are connected to the LDa side and the LDb side of the inclined surface 24a, respectively. The front end surface 24b and the rear end surface 24d are the end faces of the LDa side and the LDb side of the mountain 24, respectively. Furthermore, the top 24c is the connection between the inclined surface 24a and the front end surface 24b, and it is the part of the mountain 24 furthest from the axis 23. It can be said that the top 24c is the edge part in the frustum-shaped mountain 24 described above.

[0073] The surface of the concave-convex portion 22 is a surface that alternates from the LDb side to the LDa side, with the surface 33a of the shaft portion 23 and the rear end surface 24d, inclined surface 14a and front end surface 24b of the mountain portion 24.

[0074] Furthermore, when viewed from the side as shown in Figure 1 (viewed from a direction perpendicular to axes X1 and X2), with the mountain 24 inserted between two adjacent mountain sections 14, it is preferable that the inclined surface 14a and the inclined surface 24a are parallel to each other. The various dimensions of the mountain 24 are preferably the same as those of the mountain 14 of the inner mold 10. Here, "same" means that the dimensions of the mountain 24 are the same as those of the mountain 14 within the measured limits or design limits.

[0075] In the valley portion of the corrugated structure of the straw body, the top 24c of the mountain 24 forms a ridge. In the mold assembly 100 of this embodiment, the top 24c of each mountain 24 has an R-surface. Therefore, even when the outer surface of the straw body strongly abuts against the uneven portion 22 under the pressure of the outer mold 20, cracks are less likely to occur in the ridge portion of the corrugated structure. Therefore, in order to form the curved portion of the corrugated structure without cracking, the top 24c of the uneven portion 22 can be made to abut against the outer surface of the straw body with a strong force.

[0076] From the viewpoint of applying strong force to bring the top 24c of the protrusion 22 into contact, the radius of curvature of the R-surface of the top 24c is preferably 0.01 mm to 1.00 mm, more preferably 0.05 mm to 0.20 mm. Furthermore, the radius of curvature of the R-surface of the top 24c is preferably the same as the radius of curvature of the R-surface of the top 14c. For example, the radius of curvature of the R-surface of the top 24c is 0.10 mm.

[0077] Furthermore, in the mold assembly 100, in the LD direction, the length L2 of each mountain portion 24 of the concave-convex portion 22 is 1.50mm to 1.80mm, preferably 1.55mm to 1.77mm, and more preferably 1.60mm to 1.75mm. Moreover, the length L2 is preferably the same as the length L1 of the mountain portion 14. By making the length L2 within the above-mentioned range, even if the thickness of the valley portion is relatively large, a valley that can be folded along the ridge can be achieved. Even for a straw body with a relatively large wall thickness, a corrugated structure can be formed. The length L2 is, for example, 1.64mm.

[0078] Furthermore, the larger the inclination angle θ2 of the inclined surface 24a relative to the shaft portion 23, the stronger the force required to make the top 24c of the concave-convex portion 22 abut against the outer surface of the straw body. From this viewpoint, the inclination angle θ2 is preferably 30.0° to 40.0°, more preferably 30.0° to 35.0°. Moreover, the inclination angle θ2 is preferably the same as the inclination angle θ1. For example, the inclination angle θ2 is 31.07°.

[0079] Furthermore, the greater the distance H2 between the top 24c and the shaft portion 23, the deeper the groove formed by the two adjacent ridge portions 24. The deeper the groove, the stronger the force required to bring the top 24c of the protrusion 22 into contact with the outer surface of the straw body. From this perspective, the distance H2 between the top 24c and the shaft portion 23 is preferably 1.10mm to 1.80mm, more preferably 1.30mm to 1.70mm. Furthermore, the distance H2 is preferably the same as the distance H1. For example, the distance H2 is 1.49mm.

[0080] Furthermore, in the concave-convex portion 22, if the distance (pitch) P2 between two adjacent mountain portions 24 is large, then for valley portions with relatively large thickness, folding along the ridge line is possible. From this perspective, the distance P2 between two adjacent mountain portions 24 is preferably 2.20 mm to 2.50 mm, more preferably 2.25 mm to 2.40 mm. Moreover, the distance P2 is preferably the same as the distance P1. It should be noted that the distance P2 between two adjacent mountain portions 24 refers to the distance between the two tops 24c of the two adjacent mountain portions 24. For example, the distance P2 is 2.30 mm.

[0081] Furthermore, in the two adjacent mountain sections 14, the distance D2 between the front end face 24b of one mountain section 24 and the rear end face 24d of the other mountain section 24 is not particularly limited, but is preferably 0.2mm to 0.8mm, more preferably 0.3mm to 0.7mm. Moreover, distance D2 is preferably the same as distance D1. By making distance D2 within the above-mentioned range, the contact portion between the portion of the uneven section 22 (excluding the top 24c) and the straw body can be reduced, thereby improving the appearance of the corrugated structure. For example, distance D2 is 0.6mm.

[0082] As described above, the mold assembly 100 has the following structures (1) and (2). Each mountain portion 14 has a top 14c with an R-surface, and each mountain portion 24 has a top 24c with an R-surface. (2) In the LD direction, the length L1 of each mountain portion 14 is 1.50mm to 1.80mm, and the length L2 of each mountain portion 24 is 1.50mm to 1.80mm. Therefore, according to the mold assembly 100, the tops 14c and 24c can be brought into contact with the straw body with a strong force, and a corrugated structure can be formed even for a straw body with a relatively large wall thickness. Therefore, even if the thickness of the curved portion is large, a straw that can maintain a corrugated structure without cracks in the ridge portion can be realized. Therefore, according to the mold assembly 100, even when using a straw body made of aliphatic polyester resin such as biodegradable resin, a straw with a corrugated structure that can be used in practice can be manufactured. Therefore, according to this embodiment, when a straw with a corrugated structure is manufactured using aliphatic polyester resins such as biodegradable resins as raw materials, a mold assembly 100 that can be used can be realized.

[0083] (The manufacturing method of straws)

[0084] The method for manufacturing a straw according to this embodiment (hereinafter, sometimes referred to as this manufacturing method) includes a corrugated structure forming step of forming a corrugated structure on a straw body using the above-described mold assembly 100. Therefore, even when using a straw body made from an aliphatic polyester resin such as a biodegradable resin, a practically usable straw with a corrugated structure can be manufactured.

[0085] If this manufacturing method includes the above-described corrugated structure forming process, then any method is acceptable. From the viewpoint of the processability of the corrugated structure, the corrugated structure forming process preferably includes a molding process and a folding process. In the molding process, a mold assembly is used to mold the ridge and valley portions of the corrugated structure onto the straw body. In the folding process, the straw body, after being molded in the molding process, is compressed, and the ridge and valley portions are folded to form the corrugated structure. Figures 4001 to 4003 are schematic diagrams illustrating an example of the corrugated structure forming process in this manufacturing method. This corrugated structure forming process includes the preparation process shown in Figure 4001, the molding process shown in Figure 4002, and the folding process shown in Figure 4003.

[0086] As shown in Figure 4001, in the preparation step, a mold assembly is placed on the cylindrical straw body 31. In this preparation step, the outer mold 20 and the concave-convex portion 12 of the inner mold 10 are arranged facing each other. The straw body 31 is installed on the inner mold 10 arranged in this way. Specifically, the straw body 31 is installed in such a way that the inner mold 10 is inserted into the interior of the straw body 31.

[0087] Furthermore, as shown in Figure 4002, during the molding process, for the straw body 31 with the inner mold 10 installed inside, the inner mold 10 and the outer mold 20 are rotated in opposite directions while the outer mold 20 is squeezed from the outside. Through this rotation and squeezing, the valley portion 32E and the ridge portion 32F of the corrugated structure 32 are shaped on the straw body 31. Next, the ridge line 32c of the valley portion 32E is formed at the contact portion between the straw body 31 and the top 14c of the inner mold 10. In addition, the ridge line 32d of the ridge portion 32F is formed at the contact portion between the straw body 31 and the top 24c of the outer mold 20. Through the molding process, the valley portion 32E and the ridge portion 32F are alternately formed on the straw body 31 along the LD direction. If the above-described mold assembly 100 is used, cracks will not occur at the ridge line 32c of the valley portion 32E and the ridge line 32d of the ridge portion 32F during the molding process. It should be noted that the ridge lines 32c and 32d can be represented as the bent or folded lines of the valley portion 32E and the ridge portion 32F in the corrugated structure 32.

[0088] Here, in the molding process, the rotation speed and rotation time of the inner mold 10 and the outer mold 20 are only required to be the rotation speed at which the ridges 32c and 32d are formed on the straw body 31, and can be appropriately set according to the thickness, material, etc. of the straw body 31. For example, the rotation speed of the inner mold 10 and the outer mold 20 is 50 rpm to 1000 rpm, preferably 200 rpm to 600 rpm. The rotation time of the inner mold 10 and the outer mold 20 is 0.5 seconds to 30 seconds, preferably 1.5 seconds to 10 seconds. More specifically, the rotation speed and rotation time of the inner mold 10 and the outer mold 20 are 300 rpm and 5 seconds, respectively.

[0089] Furthermore, the outer mold 20 presses against the straw body 31, for example, by moving the outer mold 20 further toward the inner mold 10 while it is in contact with the outer surface of the straw body 31. The distance the outer mold 20 moves toward the inner mold 10 corresponds to the amount of material squeezed into the straw body 31 by the outer mold 20. The amount of material squeezed into the straw body 31 can be set appropriately based on the thickness and material of the straw body 31, as long as the rotational speed at which the ridges 32c and 32d are formed on the straw body 31 is constant. For example, for a straw body 31 with a wall thickness of 0.16 mm to 0.20 mm, the amount of material squeezed into the straw body 31 is preferably 0.1 mm to 1.0 mm, and more preferably 0.2 mm to 0.8 mm.

[0090] As shown in Figure 4003, during the folding process, the inner mold 10 and the outer mold 20 are removed from the straw body 31 after it has been shaped in the molding process. Next, the straw body 31 is compressed from both sides. As a result, the valley portion 32E and the ridge portion 32F are compressed, forming a corrugated structure 32 on the straw body 31. If the above-mentioned mold assembly 100 is used, cracks will not occur at the ridge line 32c of the valley portion 32E and the ridge line 32d of the ridge portion 32F due to the above compression during the folding process.

[0091] (Straw body 31)

[0092] Here, according to the manufacturing method, in the above-mentioned corrugated structure forming process, the elastic modulus of the straw body 31 is preferably 1300MPa~2200MPa, and the fracture strain is preferably 200%~600%. In this way, since the elastic modulus and fracture strain of the straw body 31 are within a specific range of values, the corrugated structure 32 exhibits excellent processability. Specific effects are as follows: (1) In the above-mentioned molding process, the curved portion (valley portion 32E or ridge portion 32F) of the straw body 31 is not crushed. (2) In the above-mentioned folding process, no cracks are generated at the ridges 32c and 32d of the curved portion of the straw body 31 (the corrugated structure 32 does not crack at the ridges 32c or 32d).

[0093] For the dumbbell-shaped membrane obtained by cutting from the straw body 31, the above-mentioned elastic modulus and fracture strain are obtained by performing a tensile test using a tensile testing machine (Shimadzu Corporation: EZ-LX 1kN) according to JIS K 7127 at a tensile speed of 100 mm / min, and the SS curve is obtained, and the calculation is based on the SS curve.

[0094] The elastic modulus is preferably 1400 MPa to 2100 MPa, more preferably 1500 MPa to 2000 MPa. Furthermore, the fracture strain is preferably 200% to 500%, more preferably 240% to 500%.

[0095] This manufacturing method further preferably includes a step of forming the straw body 31 (straw body forming step); and a curing step of storing the straw body 31 formed in the straw body forming step under given curing conditions (curing time, curing temperature, etc.) until the aforementioned corrugated structure forming step. The values ​​of the aforementioned elastic modulus and fracture strain can be controlled, for example, by adjusting the curing time of the straw body 31 in the aforementioned curing step. There is a tendency that the longer the curing time, the higher the aforementioned elastic modulus. In addition, there is a tendency that the longer the curing time, the lower the aforementioned fracture strain.

[0096] The curing time is not particularly limited as long as the elastic modulus and fracture strain are within the range specified above. Preferably, it is 1 to 24 days, and more preferably, it is 2 to 15 days. Similarly, the curing temperature is not particularly limited as long as the elastic modulus and fracture strain are within the range specified above. Preferably, it is -20°C to 50°C, and more preferably, it is 0°C to 30°C.

[0097] Furthermore, when the aforementioned aliphatic polyester resin is a P3HA resin, the aforementioned elastic modulus and the aforementioned fracture strain can be controlled, for example, by adjusting the average content ratio of other hydroxyalkyl ester units to all monomer units constituting the P3HA resin component.

[0098] (straw)

[0099] Figure 5 is a cross-sectional view showing the general structure of the corrugated structure 32 of the straw 30 in this embodiment. The straw 30 can be manufactured, for example, by the manufacturing method described above, that is, the manufacturing method of the straw using the mold assembly 100 described above.

[0100] As shown in Figure 5, the straw 30 has a corrugated structure 32 formed on a cylindrical straw body 31 containing an aliphatic polyester resin. The aliphatic polyester resin contained in the straw body 31 will be described later.

[0101] The corrugated structure 32 includes multiple valley portions 32E and multiple ridge portions 32F, which are alternately arranged along the axial direction of the straw body 31. In the cross-sectional shape along the axial direction of the straw body 31, i.e., the cross-sectional shape shown in FIG. 5, the corrugated structure 32 has a corrugated wall portion with alternating long side portions 32a and short side portions 32b. The valley portions 32E and the ridge portions 32F are together formed by the long side portions 32a and the short side portions 32b. Moreover, in the valley portions 32E and the ridge portions 32F, portions of the ridge lines 32c and 32d together form the connecting portion of the long side portions 32a and the short side portions 32b. In the valley portion 32E, a portion of the ridge line 32c is arranged on the outer side, while in the ridge portion 32F, a portion of the ridge line 32d is arranged on the inner side.

[0102] In this embodiment of the straw 30, the wall thickness T1 of the straw body 31 is 0.18 mm to 0.22 mm, more preferably 0.185 mm to 0.205 mm. By making the wall thickness of the straw body 31 within the above-mentioned range, a straw 30 that maintains the corrugated structure 32 and has no cracks at the edges 32c and 32d can be achieved. Therefore, the straw 30 can be used when manufacturing a straw with a corrugated structure using aliphatic polyester resins such as biodegradable resins as raw materials.

[0103] Furthermore, in the cross-sectional shape along the axial direction of the straw body 31, i.e., the cross-sectional shape shown in FIG5, the length of the long side 32a / length of the short side 32b is preferably 1.50 to 2.50, more preferably 1.70 to 2.30. By making the length of the long side 32a / length of the short side 32b within the above-mentioned numerical range, a straw 30 with no cracks at the ridges 32c and 32d and capable of maintaining the corrugated structure 32 can be achieved.

[0104] Furthermore, the wall thickness T2 of the portions along the edges 32c and 32d, i.e., the connecting portion between the long side 32a and the short side 32b, is preferably 0.040 mm to 0.120 mm, more preferably 0.070 mm to 0.110 mm. By making the wall thickness of the connecting portion between the long side 32a and the short side 32b within the above-mentioned range, a straw 30 that maintains the corrugated structure 32 and has no cracks at the edges 32c and 32d can be achieved.

[0105] (Thermoplastic resin)

[0106] The straw body of the mold assembly 100 in this embodiment, i.e., the straw body used in this manufacturing method and the straw of this embodiment, is made of thermoplastic resin. There is no particular limitation on the thermoplastic resin. Preferred thermoplastic resins include, in addition to general-purpose resins such as polypropylene, polyethylene, polyvinyl chloride, polyvinyl acetate, polyoxymethylene, polyoxymethylene, polycarbonate, polyamide, acrylonitrile, butadiene, polystyrene, and acrylic polymers, biodegradable resins such as P3HA resins, polylactic acid, polyglycolic acid, polybutylene succinate, polybutylene adipate, polybutylene terephthalate, polybutylene terephthalate, and polycaprolactone. Furthermore, a single thermoplastic resin may be used, or two or more may be used in combination.

[0107] In particular, the straw (straw body) of this embodiment preferably comprises an aliphatic polyester resin. Furthermore, this aliphatic polyester resin is preferably a poly(3-hydroxyalkanoate) resin (hereinafter, sometimes referred to as P3HA resin). In this specification, "P3HA resin" refers to a resin containing a repeating 3-hydroxyalkanoic acid unit represented by the general formula: [-CHR-CH2-CO-O-] (where R is C...). n H 2n+1 The alkyl group represents a polyhydroxyalkanoate, where n is an integer greater than or equal to 1 and less than or equal to 15. ) is a repeating unit.

[0108] More specifically, the P3HA-based resin preferably contains 3-hydroxybutyrate (3HB) units. The P3HA-based resin containing 3HB units is preferably selected from poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P3HB3HV), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (P3HB3HH), poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-3-hydroxyhexanoate) (P3HB3HV3HH), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), and poly(3-hydroxybutyrate-co-3-hydroxydecanoate). The P3HA-based resin may contain only one type or more types.

[0109] As a P3HA-based resin, a P3HA-based resin produced by microorganisms is preferred (microbially produced P3HA-based resin). Microbially produced P3HA-based resins typically consist only of polyhydroxyalkanoate monomer units in the D-body (R-body) form. From the viewpoint of ease of industrial production, P3HB, P3HB3HH, P3HB3HV, P3HB3HV3HH, and P3HB4HB are preferred among microbially produced P3HA-based resins, and more preferably P3HB, P3HB3HH, P3HB3HV, and P3HB4HB.

[0110] P3HA-based resins can be manufactured using methods described, for example, in International Publication No. 2010 / 013483. Commercially available P3HA-based resins include, for example, KANEKA Corporation's "KANEKA Biodegradable Polymer PHBH (Registered Trademark)".

[0111] In addition, the above-mentioned P3HA resin contains at least one copolymer of 3HB unit and other hydroxyalkyl ester units, and the 3-hydroxybutyrate unit in the above-mentioned poly(3-hydroxyalkanoate) resin is 65.0 to 99.0 mol% of all repeating units (100 mol%), preferably 68.0 to 98.5 mol%, more preferably 70.0 to 98.5 mol%, and even more preferably 70.0 to 98.0 mol%.

[0112] By increasing the composition ratio of 3HB repeating units to 90.0 mol% or more, the rigidity of P3HA-based resins is further improved, and the crystallization rate is accelerated, reducing burrs. The reduction of monomer content tends to increase productivity. On the other hand, by keeping the composition ratio of 3HB repeating units below 99.0 mol%, the melting point is lower than the thermal decomposition temperature, thus enabling stable and continuous production. It should be noted that the monomer composition ratio of P3HA-based resins can be determined by methods such as gas chromatography (for example, refer to International Publication No. 2014 / 020838).

[0113] The molecular weight of P3HA-based resins is not particularly limited, as long as it indicates substantially sufficient physical properties for the target application. The weight-average molecular weight range of P3HA-based resins is preferably 100,000 to 1,000,000, more preferably 150,000 to 700,000, further preferably 200,000 to 500,000, and particularly preferably 250,000 to 450,000. If the weight-average molecular weight is 100,000 or higher, moderate mechanical strength can be obtained. Furthermore, if the molecular weight is below 1,000,000, the increase in melt viscosity can be suppressed, resulting in excellent moldability.

[0114] The above-described method for determining the weight-average molecular weight used gel permeation chromatography (GPC) (Shodex GPC-101, manufactured by Showa Denko Corporation). The chromatographic column used was a polystyrene gel (Shodex K-804, manufactured by Showa Denko Corporation), with chloroform as the mobile phase. The molecular weight was calculated using polystyrene as the conversion factor. Standard curves were prepared using polystyrene with weight-average molecular weights of 31,400, 197,000, 668,000, and 1,920,000. Suitable columns for determining these molecular weights can be used as the chromatographic column in this GPC.

[0115] Furthermore, the material of the straw (straw body) in this embodiment may contain additives that can be used with thermoplastic resins, to the extent that it does not impair the effects of the present invention. Examples of such additives include: inorganic fillers such as talc, calcium carbonate, mica, and silica; colorants such as pigments and dyes; odor absorbers such as activated carbon and zeolite; fragrances such as vanillin and dextrin; plasticizers, oxidation inhibitors, antioxidants, weather resistance modifiers, ultraviolet absorbers, crystal nucleating agents, lubricants, release agents, water repellents, antibacterial agents, and slip modifiers. Only one type of additive may be included, or two or more may be included. The content of these additives can be appropriately set by those skilled in the art according to their intended use.

[0116] According to this embodiment, when P3HA-based resin is used as the raw material for the straw (straw body), marine pollution caused by waste can be suppressed, thereby contributing to the achievement of Sustainable Development Goals (SDGs) such as Goal 12 "Ensuring sustainable consumption and production patterns" and Goal 14 "Protecting and sustainably utilizing the ocean and marine resources to promote sustainable development."

[0117] The straw body used by this manufacturing method can be manufactured using a resin composition comprising the aforementioned aliphatic polyester resin, employing a known method. The straw body can be manufactured, for example, by the following method: a melt process in which the resin composition comprising the aliphatic polyester resin is melted in an extruder; and a molding process after the melt process, whereby the straw is extruded from an annular die connected to the outlet of the extruder and immersed in water to solidify and form a tubular shape.

[0118] This invention is not limited to the above-described embodiments. Various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this invention.

[0119] That is, one embodiment of the present invention is as follows.

[0120] <1> A mold assembly 100 is used to form a corrugated structure 32 on a cylindrical straw body 31. The mold assembly 100 includes:

[0121] A rod-shaped inner mold 10 is inserted into the interior of the straw body 31; and

[0122] The rod-shaped outer mold 20 presses the straw body 31 from the outside.

[0123] The aforementioned inner mold 10 has a first uneven portion (uneven portion 12) forming the ridge portion 32F of the aforementioned corrugated structure 32.

[0124] The aforementioned first concave-convex portion has:

[0125] The first shaft portion (shaft portion 13) extending along the axial direction (LD direction) of the straw body; and

[0126] Multiple first mountain portions (mountain portions 14) protrude radially (RD1 direction) relative to the aforementioned first shaft portion along the inner mold 10, and are arranged at given intervals along the axial direction of the aforementioned straw body 31.

[0127] The outer mold 20 described above has a second uneven portion (uneven portion 22) forming the valley portion 32E of the corrugated structure 32 described above.

[0128] The second concave-convex portion described above has:

[0129] A second shaft (shaft 23) is arranged in parallel with the first shaft;

[0130] Multiple second mountain sections (mountain sections 24), which protrude radially (RD2 direction) of the outer mold 20 relative to the aforementioned second shaft section, are respectively inserted between two adjacent first mountain sections (mountain sections 14).

[0131] Each first mountain section has a first top (top 14c) with an R-face, and each second mountain section has a second top (top 24c) with an R-face.

[0132] In the axial direction of the straw body 31, the length L1 of each first mountain part is 1.50mm~1.80mm, and the length L2 of each second mountain part is 1.50mm~1.80mm.

[0133] <2> according to <1> The mold assembly consists of 100 parts, among which...

[0134] Each first mountain section has a first inclined surface (inclined surface 14a) extending from the aforementioned first top, and each second mountain section has a second inclined surface (inclined surface 24a) extending from the aforementioned second top.

[0135] The inclination angle θ1 of the first inclined surface relative to the first shaft is 30.0°~40.0°.

[0136] The inclination angle θ2 of the second inclined surface relative to the second shaft is 30.0°~40.0°.

[0137] <3> according to <1> or <2> The mold assembly consists of 100 parts, among which...

[0138] The distance H1 between the first top portion and the first shaft portion is 1.10mm to 1.80mm.

[0139] The distance H2 between the second top and the second shaft is 1.10mm to 1.80mm.

[0140] <4> according to <1> ~ <3> 100 mold sets for any one of the items, among which,

[0141] The distance P1 between two adjacent first mountain sections (mountain section 14) is 2.20mm~2.50mm.

[0142] The distance P2 between two adjacent second mountain sections (mountain section 24) is 2.20mm~2.50mm.

[0143] <5> according to <1> ~ <4> 100 mold sets for any one of the items, among which,

[0144] The straw body 31 described above contains an aliphatic polyester resin.

[0145] <6> according to <5> The mold assembly consists of 100 parts, among which...

[0146] The aforementioned aliphatic polyester resin is a poly(3-hydroxyalkanoate) resin.

[0147] <7> A method for manufacturing a straw 30, comprising:

[0148] The process of forming the corrugated structure uses <1> ~ <6> The mold assembly 100 of any one of them forms a corrugated structure 32 on the straw body 31.

[0149] <8> according to <7> The method for manufacturing straws, wherein,

[0150] In the above-mentioned corrugated structure forming process, the elastic modulus of the straw body 31 is 1300MPa~2200MPa, and the fracture strain is 200%~600%.

[0151] <9> according to <8> The method for manufacturing straws, wherein,

[0152] The above-mentioned corrugated structure forming process includes:

[0153] In the molding process, using the aforementioned mold assembly 100, the ridge portion 32F and valley portion 32E of the corrugated structure 32 of the aforementioned straw body 31 are molded; and

[0154] In the folding process, the straw body 31, which has been shaped by the molding process, is compressed, and the ridge portion 32F and the valley portion 32E are folded to form the corrugated structure 32.

[0155] <10> according to <9> The method for manufacturing straws, wherein,

[0156] The above molding process includes:

[0157] In the extrusion process, the inner mold 10 is installed inside the straw body 31, and the inner mold 10 and the outer mold 20 are rotated in opposite directions while the outer mold 20 is extruded from the outside.

[0158] <11> according to <7> ~ <10> The method of manufacturing a straw according to any one of the following further includes:

[0159] The straw body forming process forms the aforementioned straw body 31; and

[0160] The curing process involves storing the straw body 31, which has been formed in the straw body forming process, under given curing conditions until the corrugated structure forming process described above.

[0161] <12> according to <11> The method for manufacturing straws, wherein,

[0162] In the above-mentioned curing process, the curing conditions include the following: curing time is 1 day to 24 days, and curing temperature is -20℃ to 50℃.

[0163] <13> A straw 30 is a cylindrical straw body 31 containing an aliphatic polyester resin, on which a corrugated structure 32 is formed, wherein...

[0164] The wall thickness T1 of the straw body 31 is 0.18mm~0.22mm.

[0165] <14> according to <13> 30 straws, of which,

[0166] In the cross-sectional shape along the axial direction (LD direction) of the straw body 31,

[0167] The aforementioned corrugated structure 32 has corrugated wall portions with alternating long side portions 32a and short side portions 32b.

[0168] The length of the long side portion 32a and the length of the short side portion 32b are 1.50 to 2.50.

[0169] <15> according to <14> 30 straws, of which,

[0170] The wall thickness T2 of the connection portion (the portion of the edges 32c and 32d) between the aforementioned long side 32a and the aforementioned short side 32b is 0.040mm to 0.120mm.

[0171] Example

[0172] The present invention will now be described in more detail based on embodiments, but the present invention is not limited to these embodiments.

[0173] The substances used in the examples and comparative examples are shown below.

[0174] [Poly(3-hydroxyalkanoate) resins]

[0175] PHB: Poly(3-hydroxybutyrate) (weight-average molecular weight 300,000 g / mol)

[0176] It was manufactured according to the method described in Comparative Example 1 of International Publication No. 2004 / 041936.

[0177] P3HB3HH-3: P3HB3HH (average content ratio 3HB / 3HH = 97.1 / 2.9 (mol% / mol%), weight-average molecular weight is 300,000 g / mol)

[0178] It was manufactured according to the method described in Example 2 of International Publication No. 2019 / 142845.

[0179] P3HB3HH-13: P3HB3HH (KANEKA biodegradable polymer PHBH (registered trademark)) (average content ratio 3HB / 3HH = 87.1 / 12.9 (mol% / mol%), weight-average molecular weight is 330,000 g / mol)

[0180] P3HB3HH-30: P3HB3HH (average content of 3HB / 3HH = 70.5 / 29.5 (mol% / mol%), weight-average molecular weight is 640,000 g / mol)

[0181] It was manufactured according to the method described in Example 9 of International Publication No. 2019 / 142845.

[0182] [additive]

[0183] Additive-1: Mountain Acid amide (manufactured by Nippon Seika Co., Ltd.: BNT-22H)

[0184] Additive-2: Erucamide (manufactured by Nippon Seika Co., Ltd.: NEUTRON-S)

[0185] [Plasticizer]

[0186] Plasticizer: Lauryl glycerol diacetate (manufactured by Riken Vitamin Co., Ltd.: BIOCIZER)

[0187] [other]

[0188] Polybutylene succinate (PBS) and cellulose acetate were used to prepare tubes, which were then used as the body of the straws. All tubes had an outer diameter of 6 mm and a wall thickness of 0.2 mm.

[0189] 1. Preparation of resin composition particles

[0190] Mix 12.0 parts by weight of PHB, 52.2 parts by weight of P3HB3HH-3, 22.8 parts by weight of P3HB3HH-30, and 13.0 parts by weight of P3HB3HH-13, then add 1.0 parts by weight of Additive-1, 0.5 parts by weight of Additive-2, and 4.3 parts by weight of Plasticizer, and mix further.

[0191] The obtained resin material (resin mixture) was fed into a φ26mm co-rotating twin-screw extruder with both the barrel temperature and die temperature set at 150℃. The resin material filament was extruded at a rate of 20kg / hour. The extruded resin material was then passed into a water bath filled with 40℃ hot water to solidify the filament, and then cut into granules using a granulator to obtain resin composition granules.

[0192] 2. Forming of the tube (straw body)

[0193] A φ50mm single-screw extruder with an annular die (15mm outer diameter, 13.5mm inner diameter) was used. The barrel and die temperatures were set to 160℃. Resin composition granules were fed in and extruded into tubular shapes. The extruded tubes were then passed through a 40℃ water bath located 100mm from the annular die and pulled at speeds of 25m / min, 30m / min, and 40m / min. The result was tubes with an outer diameter of 6mm and a length of 200mm, with wall thicknesses of 0.16mm, 0.18mm, and 0.20mm respectively.

[0194] 3. Processing of corrugated structures

[0195] In the processing of the corrugated structure, a pair of mold sets were used on the inner and outer sides of the straw body (see Figure 1).

[0196] Preparation process: Insert the tubes with different wall thicknesses made in step 2 into the rod-shaped inner mold, and then press the movable outer mold with the same shape as the inner mold from the outside of the tube.

[0197] Molding process: The outer mold is movable in a direction perpendicular to the length of the tube. After the outer mold contacts the outer surface of the tube, further extrusion is performed. Then, in this state, the outer and inner molds are rotated in opposite directions at 300 rpm for 5 seconds, thereby molding a corrugated structure on the tube. After the rotation of the inner and outer molds is complete, the tube separates from the outer mold and is removed from the inner mold. It should be noted that the extrusion depth after the outer mold contacts the outer surface of the tube is set to 0.30 mm and 0.60 mm.

[0198] Folding process: Next, insert the tube into the compression pin on the cylindrical side, apply force to the tube along the length direction to compress it, thereby folding the corrugated structure.

[0199] 4. Dimensions of the mold set used

[0200] Refer to Figures 2 and 3 to illustrate the dimensions of the mold assembly used in the processing of the corrugated structure.

[0201] Mold Set #1

[0202] Inner mold 10: The length L1 of the mountain 14 is 1.34 mm. The inclination angle θ1 of the inclined surface 14a relative to the shaft 13 is 27.18°. The distance H1 between the top 14c and the shaft 13 is 1.00 mm. The distance P1 between two adjacent mountains 14 is 2.00 mm. No R-surface is formed on the top 14c.

[0203] Outer mold 20: The length L2 of the mountain 24 is 1.34 mm. The inclination angle θ2 of the inclined surface 24a relative to the shaft 23 is 27.18°. The distance H2 between the top 24c and the shaft 23 is 1.00 mm. The distance P2 between two adjacent mountains 24 is 2.00 mm. No R-surface is formed on the top 24c.

[0204] Mold Set #2

[0205] Inner mold 10: The length L1 of the mountain 14 is 1.64 mm. The inclination angle θ1 of the inclined surface 14a relative to the shaft 13 is 31.07°. The distance H1 between the top 14c and the shaft 13 is 1.20 mm. The distance P1 between two adjacent mountains 14 is 2.30 mm. A radius of curvature R of 0.1 mm is applied to the top 14c.

[0206] Outer mold 20: The length L2 of the mountain 24 is 1.64 mm. The inclination angle θ2 of the inclined surface 24a relative to the shaft 23 is 31.07°. The distance H2 between the top 24c and the shaft 23 is 1.20 mm. The distance P2 between two adjacent mountains 24 is 2.30 mm. A radius of curvature R of 0.1 mm is applied to the top 24c.

[0207] 5. Evaluation of the processability of corrugated structures

[0208] The processability of the corrugated structure is evaluated as follows.

[0209] "Moldable": In the above folding process, the tube can be folded along the ridge and valley lines of the corrugated structure.

[0210] "Unformable": In the above folding process, it is impossible to fold the tube along the ridge and valley lines of the corrugated structure.

[0211] “Crack”: Whether it is “formable” or “unformable” as mentioned above, cracks occur at the ridges and valleys of the corrugated structure.

[0212] (Example 1)

[0213] The straw body was made using a 0.16mm thick tube as described in section 2. Using mold set #2, the extrusion depth after the outer mold contacts the outer surface of the tube was set to 0.3mm, and the corrugated structure was processed according to section 3. Next, the machinability of the corrugated structure was evaluated according to section 5.

[0214] (Examples 2-7, Comparative Examples 1-5)

[0215] The wall thickness of the tube used as the straw body, the type of mold set used in the processing of the corrugated structure, and the extrusion amount after the outer mold comes into contact with the outer surface of the tube were set to the conditions described in Table 1. Otherwise, the corrugated structure was processed by the same method as in Example 1. Next, the processability of the corrugated structure was evaluated according to 5.

[0216] The evaluation results of the workability of the corrugated structure are shown in Table 1.

[0217]

[0218] (Examples 8-12, Comparative Examples 6-9)

[0219] The evaluation methods implemented in Examples 8-12 and Comparative Examples 6-9 will be described below.

[0220] [Tensile Testing: Calculation of Elastic Modulus and Fracture Strain]

[0221] The fabricated tube was cut into membranes, and then cut into No. 8 dumbbell shapes according to JIS K 625. Next, a tensile test was performed on the cut membrane using a tensile testing machine (Shimadzu EZ-LX 1kN) according to JIS K 7127 at a tensile speed of 100 mm / min. Based on the SS curve obtained from the tensile test, the tensile modulus of elasticity and the fracture strain were calculated.

[0222] [Evaluation of the processability of corrugated structures]

[0223] The processability of the corrugated structure is evaluated as follows.

[0224] "Crushing": In the folding process, the ridge and valley sections of the corrugated structure, excluding the ridge lines, fold.

[0225] “Crack”: Cracks are observed at the ridges and valleys during the above-mentioned shaping or folding processes.

[0226] "No problem": In the above folding process, folding along the ridge and valley sections can form a corrugated structure, and no cracks were observed at the ridges.

[0227] (Example 8)

[0228] The straw body was made in step 2 and then cured for 1 hour. The straw body was then processed with a corrugated structure according to step 3, and the processability of the corrugated structure was evaluated. Furthermore, a tensile test was performed on the straw body, and the elastic modulus and fracture strain were calculated.

[0229] The evaluation results of the elastic modulus and fracture strain of the straw body, as well as the processability of the corrugated structure, are shown in Table 2.

[0230] (Examples 9-11, Comparative Examples 6-8)

[0231] As the straw body, the curing time of the tube prepared in step 2 was set as shown in Table 2. Otherwise, the corrugated structure was processed using the same method as in Example 8. In addition, a tensile test was performed on the straw body, and the elastic modulus and fracture strain were calculated.

[0232] The evaluation results of the elastic modulus and fracture strain of the straw body, as well as the processability of the corrugated structure, are shown in Table 2.

[0233] (Example 12)

[0234] Polybutylene succinate was used to make the straw body, and the curing time was set as shown in Table 2. Otherwise, the corrugated structure was processed using the same method as in Example 8. It should be noted that a tensile test was performed on the straw body, and the elastic modulus and fracture strain were calculated.

[0235] The evaluation results of the elastic modulus and fracture strain of the straw body, as well as the processability of the corrugated structure, are shown in Table 2.

[0236] (Comparative Example 9)

[0237] Cellulose acetate was used to make the straw body, and the curing time was set as shown in Table 2. Otherwise, the corrugated structure was processed using the same method as in Example 8. It should be noted that a tensile test was performed on the straw body, and the elastic modulus and fracture strain were calculated.

[0238] The evaluation results of the elastic modulus and fracture strain of the straw body, as well as the processability of the corrugated structure, are shown in Table 2.

[0239]

[0240] According to the results in Table 2, when the elastic modulus of the straw body is 1300MPa~2000MPa and the fracture strain of the straw body is 200%~600%, the processability of the corrugated structure is not a problem.

[0241] Industrial applicability

[0242] This invention can be used in the field of straw manufacturing.

Claims

1. A mold assembly for forming a corrugated structure on a cylindrical straw body, the mold assembly comprising: a rod-shaped inner mold inserted into the interior of the straw body; and a rod-shaped outer mold that presses the straw body from the outside, the inner mold having a first protrusion forming a ridge portion of the corrugated structure, the first protrusion having: a first axial portion extending along the axial direction of the straw body; and a plurality of first ridge portions protruding radially relative to the first axial portion along the inner mold and arranged at given intervals along the axial direction of the straw body, wherein... The outer mold has a second concave-convex portion forming the valley portion of the corrugated structure. The second concave-convex portion has: a second shaft portion arranged parallel to the first shaft portion; a plurality of second mountain portions that protrude radially relative to the second shaft portion along the outer mold and are respectively inserted between two adjacent first mountain portions. Each first mountain portion has a first top with an R-face, and each second mountain portion has a second top with an R-face. In the axial direction of the straw body, the length of each first mountain portion is 1.50mm to 1.80mm, and the length of each second mountain portion is 1.50mm to 1.80mm.

2. The mold assembly according to claim 1, wherein, Each first mountain portion has a first inclined surface extending from the first top, and each second mountain portion has a second inclined surface extending from the second top. The inclination angle of the first inclined surface relative to the first axis portion is 30.0°~40.0°, and the inclination angle of the second inclined surface relative to the second axis portion is 30.0°~40.0°.

3. The mold assembly according to claim 1 or 2, wherein, The distance between the first top and the first shaft portion is 1.10mm to 1.80mm, and the distance between the second top and the second shaft portion is 1.10mm to 1.80mm.

4. The mold assembly according to claim 1 or 2, wherein, The distance between two adjacent first mountain sections is 2.20mm~2.50mm, and the distance between two adjacent second mountain sections is 2.20mm~2.50mm.

5. The mold assembly according to claim 1 or 2, wherein, The straw body contains an aliphatic polyester resin.

6. The mold assembly according to claim 5, wherein, The aliphatic polyester resin is a poly(3-hydroxyalkanoate) resin.

7. A method for manufacturing a straw, comprising: The corrugated structure forming process uses the mold set described in claim 1 or 2 to form a corrugated structure on the straw body.

8. The method for manufacturing a straw according to claim 7, wherein, In the process of forming the corrugated structure, the elastic modulus of the straw body is 1300MPa~2200MPa, and the fracture strain is 200%~600%.

9. The method for manufacturing a straw according to claim 8, wherein, The corrugated structure forming process includes: a molding process, using the mold set to mold the ridge and valley portions of the corrugated structure onto the straw body; and a folding process, compressing the straw body after molding and folding the ridge and valley portions to form the corrugated structure.

10. The method for manufacturing a straw according to claim 9, wherein, The molding process includes an extrusion process in which the inner mold is installed inside the straw body, and the inner mold and the outer mold are rotated in opposite directions while the outer mold is extruded from the outside.

11. The method for manufacturing a straw according to claim 7, further comprising: The process includes a straw body forming process, which forms the straw body; and a curing process, which stores the straw body formed in the straw body forming process under given curing conditions until the corrugated structure forming process.

12. The method for manufacturing a straw according to claim 11, wherein, In the aging process, the aging conditions include the following: aging time is 1 to 24 days, and aging temperature is -20℃ to 50℃.

13. A straw, wherein a corrugated structure is formed on a cylindrical straw body comprising an aliphatic polyester resin, wherein... The wall thickness of the straw body is 0.18mm~0.22mm.

14. The straw according to claim 13, wherein, In the cross-sectional shape along the axial direction of the straw body, the corrugated structure has a corrugated wall portion with alternating long and short sides, and the ratio of the length of the long side portion to the length of the short side portion is 1.50 to 2.

50.

15. The straw according to claim 14, wherein, The wall thickness of the connection portion between the long side and the short side is 0.040mm~0.120mm.

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