Extrusion blow-molded container

Abstract

To provide an extrusion blow-molded container allowing for inhibiting a crack originating from an inner parting line without providing ribs.SOLUTION: An extrusion blow-molded container 1 made of synthetic resin comprises a cylindrical mouth 10 and a container body 20 continuing in one body to a lower end of the mouth 10. The container body 20 has a cylindrical outer-faced wall 21, a bottom wall 22 closing a lower end of the outer-faced wall 21, an annular inner peripheral wall 23 continuing in one body to the outer-faced wall 21 in both side portions 23a, 23b and demarcating / forming in an outer-faced wall 21 an opening 24 penetrating the outer-faced wall 21, an annular pinch-off portion 32 formed in a surface of the inner peripheral wall 23 and extending annularly along a circumferential direction of the inner peripheral wall 23, and a protrusion 40 greater in wall thickness than the inner peripheral wall 23 provided in one body with the inner peripheral wall 23, extending along the annular pinch-off portion 32 and projecting toward the opening 24 with respect to the inner peripheral wall 23.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an extrusion blow molded container made of a synthetic resin. [Background technology]

[0002] Conventionally, as a container for storing contents such as laundry detergent, soy sauce, cooking oil, etc., there has been known an extrusion blow molded container made of a synthetic resin, which has a cylindrical mouth and a container body integrally connected to the lower end of the mouth, the container body having a cylindrical outer surface wall, a bottom wall closing the lower end of the outer surface wall, and an annular inner peripheral wall integrally connected to the outer surface wall at both sides and defining openings in the outer surface wall that penetrate the outer surface wall. By having an opening, such an extrusion blow molded container can configure a part of the container body as a grip portion.

[0003] The extrusion blow molded container can be formed by extrusion blow molding (EBM) in which a molten synthetic resin material is extruded downward from an extruder to form a cylindrical parison, this parison is sandwiched between left and right split dies to cut off its bottom end and cut off the part corresponding to the opening with an island insert, and in this state, pressurized air or the like is blown into the top end of the parison to blow it into a shape that fits the cavity of the die. The opening of the container body is provided by punching out and removing the part cut off by the island insert after extrusion blow molding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-080687 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, as described above, in an extrusion blow molded container having an opening in the container body, the portion along the annular cut-off portion that is cut off by the island insert on the inner wall becomes the seam of the synthetic resin parison, so there is a problem in that if the container is subjected to impact by being dropped, etc., there is a risk that the container will crack, starting from the annular cut-off portion.

[0006] To address this issue, it is possible to form ribs along the annular cut-off portion on the inner wall to prevent cracking. However, if the entire container is made thinner to reduce its weight and the amount of resin used, the thickness of the ribs formed on the annular cut-off portion will also become thinner, resulting in the problem that it will be difficult to achieve the effect of preventing cracking.

[0007] The present invention has been made in consideration of these problems, and its object is to provide an extrusion blow molded container that is capable of suppressing cracks originating from the annular cut-off portion without providing a rib. [Means for solving the problem]

[0008] The extrusion blow molded container of the present invention is an extrusion blow molded container made of a synthetic resin having a cylindrical mouth portion and a container body portion integrally connected to the lower end of the mouth portion, wherein the container body portion has a cylindrical outer surface wall, a bottom wall closing the lower end of the outer surface wall, an annular inner wall integrally connected to the outer surface wall at both side portions and defining an opening in the outer surface wall that penetrates the outer surface wall, an annular cut-off portion formed on the surface of the inner surface wall and extending annularly along the circumferential direction of the inner surface wall, and a convex portion that is thicker than the inner surface wall, is formed integrally with the inner surface wall, extends along the annular cut-off portion, and protrudes toward the opening side of the inner surface.

[0009] In the extrusion blow molded container of the present invention having the above-mentioned configuration, it is preferable that the cross section of the protrusion perpendicular to the axis of the container body is arc-shaped.

[0010] In the extrusion blow molded container of the present invention, in the above-mentioned configuration, it is preferable that one side of the opening of the container main body portion forms a gripping portion, the other side of the opening of the container main body portion forms a main body side portion having a larger diameter than the gripping portion, and the convex portion is provided on the inner wall on the other side of the opening of the container main body portion. Effect of the Invention

[0011] According to the present invention, it is possible to provide an extrusion blow molded container that is capable of suppressing cracks originating from the annular cut-off portion without providing a rib. [Brief description of the drawings]

[0012] [Figure 1] 1 is a side view of an extrusion blow molded container according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of the extrusion blow molded container shown in FIG. [Diagram 3] FIG. 3 is a cross-sectional view taken along the line AA in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing, in extrusion blow molding, a state in which a portion of the parison corresponding to FIG. 3 is bitten off by an island insert of a mold. [Diagram 5] 5 is a cross-sectional view corresponding to FIG. 4, illustrating the state of the parison when blow molding of the parison is started. FIG. [Figure 6] 5 is a cross-sectional view corresponding to FIG. 4, showing, in schematic form, the state of the parison when blow molding is completed. FIG. [Figure 7] 5 is a cross-sectional view of a portion of an extrusion blow molded container provided with a protrusion according to a modified example, the portion corresponding to FIG. 3. FIG. [Figure 8] 10 is a cross-sectional view of a portion of an extrusion blow molded container provided with a protrusion according to another modified example, the portion corresponding to FIG. 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, an extrusion blow molded container 1 according to one embodiment of the present invention will be described in more detail with reference to the drawings.

[0014] An extrusion blow molded container 1 according to one embodiment of the present invention shown in Figures 1, 2 and 3 can be used for applications such as storing contents such as soy sauce and edible oil. This extrusion blow molded container 1 is made of synthetic resin formed by extrusion blow molding a synthetic resin material such as polyethylene resin (PE), and integrally comprises a mouth portion 10 and a container body portion 20. The container body portion 20 is a portion that stores contents therein, and the mouth portion 10 is a portion that allows the contents to be put in and taken out of the container body portion 20.

[0015] The extrusion blow molded container 1 is a relatively thin-walled container in order to reduce the amount of synthetic resin material used.

[0016] In this specification and the claims, the up-down direction refers to the up-down direction when the extrusion blow molded container 1 is in an upright position with the mouth 10 facing upward, as shown in Figures 1 and 2.

[0017] The mouth portion 10 has a tubular shape (cylindrical shape in this embodiment) centered on an axis O. Although not shown in detail, a cap having a spout can be attached to the mouth portion 10 by taping.

[0018] The mouth portion 10 may have a configuration in which a cap is attached by screw connection. Also, the mouth portion 10 is not limited to a cylindrical shape as long as it is tubular, and may be, for example, a square cylindrical shape or an elliptical cylindrical shape.

[0019] The container body 20 is generally cylindrical with a bottom and is coaxial with the mouth 10, i.e., centered on the axis O, and is integrally connected to the lower end of the mouth 10. More specifically, the container body 20 has an outer surface wall 21, a bottom wall 22, and an inner peripheral wall 23.

[0020] The outer surface wall 21 is substantially cylindrical and is integrally connected to the lower end of the mouth 10 to form the outer shell of the container body 20. In this embodiment, the outer surface wall 21 has an upper portion 21a that is integrally connected to the mouth 10 and has a truncated cone shape that gradually expands in diameter from the upper end to the lower end, and a lower portion 21c that is cylindrical and has a slightly smaller diameter than the lower end of the upper portion 21a and is integrally connected to the lower end of the upper portion 21a via a step portion 21b.

[0021] In addition, the outer surface wall 21 is not limited to a substantially cylindrical shape as long as it is tubular, and may be, for example, a substantially rectangular cylindrical shape or a substantially elliptical cylindrical shape.

[0022] The bottom wall 22 is integrally connected to the lower end of the outer surface wall 21 and closes the lower end of the outer surface wall 21. In this embodiment, the bottom wall 22 has an annular grounding portion 22a that is integrally connected to the lower end of the outer surface wall 21, a recess 22b that is integrally connected to the inner peripheral edge of the grounding portion 22a, and a pinch-off portion 22c that protrudes downward from the recess 22b.

[0023] The bottom wall 22 is not limited to the above shape as long as it closes the lower end of the outer wall 21 .

[0024] The inner peripheral wall 23 is annular, and is integrally connected to the outer surface wall 21 at both side portions 23a, 23b to define an opening 24 penetrating the outer surface wall 21. In this embodiment, the inner peripheral wall 23 and the opening 24 are provided in the upper portion 21a of the outer surface wall 21.

[0025] More specifically, the inner peripheral wall 23 is annular about an axis in the direction in which the opening 24 penetrates the container body 20, i.e., a horizontal axis, and is integrally connected to one side of the outer surface wall 21 along the entire circumference of one horizontal side portion (end portion) 23a, and is integrally connected to the other side of the outer surface wall 21 along the entire circumference of the other horizontal side portion (end portion) 23b. The inner peripheral wall 23 has a drum-like shape in which the inner diameter is maximum at the one side portion 23a and the other side portion 23b, and the inner diameter is initial at the center position between the one side portion 23a and the other side portion 23b. The opening 24 is defined inside the inner peripheral wall 23.

[0026] The inner peripheral wall 23 is integrally connected to the outer surface wall 21 to close the internal space of the container body 20. As a result, the container body 20 has an opening 24, and is configured so that the area around the opening 24 forms a storage space for the contents.

[0027] In this embodiment, the opening 24 is disposed offset to one side (the right side in FIG. 1 ) with respect to the axis O of the container body 20. As a result, one side of the container body 20 sandwiching the opening 24 constitutes a gripping portion 25. The gripping portion 25 is a hollow, elongated rod-like shape defined by a part of the inner circumferential wall 23 and a part of the outer surface wall 21, and its internal space constitutes a part of the internal space of the container body 20. A user can easily handle the extrusion blow molded container 1 by gripping the gripping portion 25 with his / her hand. In addition, the other side of the container body 20 sandwiching the opening 24 constitutes a main body side portion 26 having a larger diameter than the gripping portion 25. The inside of the main body side portion 26 is also hollow, and constitutes a part of the internal space of the container body 20.

[0028] The extrusion blow molded container 1 according to this embodiment is formed by extrusion blow molding using a left-right split mold. Therefore, the extrusion blow molded container 1 has an outer parting line 30 and an inner parting line 31, which are parting lines of the mold, on its surface.

[0029] The outer parting line 30 extends vertically along the front and back surfaces of the extrusion blow molded container 1 from the upper end of the mouth portion 10 to the lower end of the outer surface wall 21 of the container body portion 20, and also extends from the lower ends of the outer surface wall 21 at the front and back surfaces of the extrusion blow molded container 1 to the center position of the bottom wall 22 (the position of the axis O).

[0030] A portion of the outer parting line 30 within a predetermined range from the center position of the bottom wall 22 coincides with the seam of the parison that is cut off by the mold. The pinch-off portion 22c is provided to extend along the outer parting line 30 at the seam, thereby increasing the strength of the seam.

[0031] The inner parting line 31 is a cut mark formed on the surface (inner peripheral surface) of the inner peripheral wall 23 when the parison is cut by an island insert provided in a left-right split mold to form the inner peripheral wall 23 or the opening 24. That is, the part of the inner peripheral wall 23 where the inner parting line 31 is formed is an annular cut-off portion 32 which is a seam of the parison cut by the island insert of the mold. The inner parting line 31 or the annular cut-off portion 32 extends annularly along the circumferential direction of the inner peripheral wall 23 on the surface of the inner peripheral wall 23. The circumferential position of the inner parting line 31 or the annular cut-off portion 32 about the axis O in a plan view coincides with the circumferential position of the outer parting line 30 about the axis O in a plan view.

[0032] In the extrusion blow molded container 1 according to this embodiment, a convex portion 40 is provided on the container body 20 in order to increase the strength of the seam of the parison along the annular cut-off portion 32.

[0033] The protrusion 40 is integrally formed on the inner peripheral wall 23, extends along the annular cut-off portion 32, and protrudes from the inner peripheral wall 23 toward the opening 24. In this embodiment, the protrusion 40 is provided on the other side of the opening 24 of the container body 20, i.e., on the inner peripheral wall 23 in the body side portion 26 facing the grip portion 25.

[0034] 3, the cross section of the protrusion 40 perpendicular to the axis O of the container body 20 has an arc shape that protrudes toward the opening 24 side with respect to the inner circumferential wall 23, and has a semi-cylindrical shape extending along the annular cut-off portion 32 between the upper and lower ends of the opening 24. The protrusion 40 is thicker than the inner circumferential wall 23 that is integrally connected to both sides of the protrusion 40. In this embodiment, the inner circumferential wall 23 that is integrally connected to both sides of the protrusion 40 is flat and plate-like between the protrusion 40 and the outer surface wall 21.

[0035] In this manner, in the extrusion blow molded container 1 according to the present embodiment, in a configuration in which the opening 24 is provided in the container body 20, the inner circumferential wall 23 defining the opening 24 is provided with a protruding portion 40 that extends along the annular cut-off portion 32, protrudes from the inner circumferential wall 23 toward the opening 24, and is thicker than the inner circumferential wall 23, so that the thickness of the seam of the parison along the annular cut-off portion 32 cut off by the island nest can be increased to increase the strength of the seam. As a result, even if the extrusion blow molded container 1 is formed relatively thin, the annular cut-off portion 32 where the seam is provided can be made thicker by the protruding portion 40 without providing a rib at the seam of the parison, and it is possible to prevent the extrusion blow molded container 1 from cracking starting from the annular cut-off portion 32 when an impact is applied due to being dropped, etc.

[0036] The extrusion blow molded container 1 according to this embodiment having the above-mentioned configuration is formed by extrusion blow molding using a left-right split mold 50 shown in Fig. 4. The mold 50 has a first die 51 and a second die 52, and in a portion of the mold 50 that forms the opening 24, the first die 51 is provided with a first island nest 51a, and the second die 52 is provided with a second island nest 52a. In addition, in a portion of the mold 50 that forms the opening 24, the cavity 53 of the mold 50 has a first portion 53a shaped to correspond to the grip portion 25, a second portion 53b shaped to correspond to the main body portion 26, and a third portion 53c shaped to correspond to the protrusion 40.

[0037] As shown by the two-dot chain line in Fig. 4, when a parison 54 formed into a cylindrical shape from a synthetic resin material is sandwiched between the first die 51 and the second die 52, the parison 54 is cut off by the first island insert 51a and the second island insert 52a in the portion forming the opening 24 of the mold 50. As a result, as shown by the hatched solid line in Fig. 4, in the portion forming the opening 24 of the mold 50, the parison 54 is separated into a first portion 54a disposed in the first portion 53a of the cavity 53 and molded into the gripping portion 25, a second portion 54b disposed in the second portion 53b and the third portion 53c of the cavity 53 and molded into the main body portion 26 and the protrusion 40, and a third portion 54c held between the first island insert 51a and the second island insert 52a.

[0038] When a pressurized medium such as pressurized air is supplied to the inside of the parison 54 from the state shown in Figure 4 and blow molding is started, the first portion 54a of the parison 54 is stretched inside the first portion 53a of the cavity 53, and the second portion 54b of the parison 54 is stretched inside the second portion 53b and the third portion 53c of the cavity 53.

[0039] At this time, the third portion 53c of the cavity 53 is shaped to protrude toward the first island nesting member 51a or the second island nesting member 52a with respect to the second portion 53b, and the second portion 54b of the parison 54 is supported by being connected to the portion cut off by the first island nesting member 51a and the second island nesting member 52a. Therefore, as shown in FIG. 5, the second portion 54b of the parison 54 stretched by the supply of the pressurized medium contacts the inner peripheral surface of the third portion 53c of the cavity 53 before contacting the inner peripheral surface of the second portion 53b of the cavity 53. In this way, the second portion 54b of the parison 54 contacts the inner peripheral surface of the third portion 53c of the cavity 53 in the early stage of blow molding where the stretch ratio is low, and is molded into the convex portion 40. Therefore, the convex portion 40 is formed to have a relatively thick wall thickness close to that of the parison 54.

[0040] The shape of the parison 54 shown by the hatched solid line in FIG. 4 and the shape of the parison 54 shown by the solid line in FIG. 5 are each schematic shapes.

[0041] When the pressurized medium is further supplied to the parison 54 from the state shown in FIG. 5, the part of the second part 54b of the parison 54 that is not in contact with the third part 53c is further stretched while contacting the inner peripheral surface of the second part 53b of the cavity 53. Then, as shown in FIG. 6, when the blow molding is completed, the first part 54a of the parison 54 contacts the first part 53a of the cavity 53 to form the grip part 25, and the second part 54b of the parison 54 contacts the inner peripheral surface of the third part 53c of the cavity 53 to form the main body part 26. Although not shown in detail, other parts of the extrusion blow molded container 1 are also molded into the shape shown in FIG. 1 and FIG. 2 along the cavity 53. Furthermore, after the blow molding is completed, the third part 54c is punched out and removed to form the opening 24.

[0042] In the extrusion blow molded container 1 after blow molding, the main body portion 26 and the inner peripheral wall 23 that constitutes it are thinner than the convex portion 40 because the parison 54 is stretched and molded further than the convex portion 40. In this way, by blow molding the parison 54, it is possible to easily manufacture the extrusion blow molded container 1 that has the convex portion 40 that is thicker than the inner peripheral wall 23.

[0043] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0044] For example, in the above embodiment, the convex portion 40 has an arc-shaped cross section perpendicular to the axis O of the container body portion 20, but this is not limited to this. As long as the convex portion 40 protrudes from the inner wall 23 toward the opening 24 and has a shape such that the parison 54 contacts the third part 53c of the cavity 53 of the mold 50 before the second part 53b during blow molding, the convex portion 40 may have various shapes, such as a shape in which the cross section perpendicular to the axis O of the container body portion 20 has three sides of a trapezoid as shown in Figure 7, or a shape in which the cross section perpendicular to the axis O of the container body portion 20 has two sides of a triangle as shown in Figure 8.

[0045] In the above embodiment, the opening 24 is arranged offset to one side with respect to the axis O of the container body 20, and a part of the container body 20 is configured as the gripping portion 25, but this is not limited thereto, and the position of the opening 24 can be changed in various ways, for example, by arranging the opening 24 so that its center coincides with the axis O. The shapes of the opening 24 and the inner peripheral wall 23 can also be changed in various ways.

[0046] Furthermore, in the above embodiment, the inner peripheral wall 23 and the annular cut-off portion 32 are annular and extend continuously all around the opening 24, but they may be annular and partially discontinuous. In this case, by providing the discontinuous portion on the lower end side of the opening 24, the gripping portion 25 may be formed into a lever shape whose upper end is connected to the main body portion 26 and whose lower end is separated from the main body portion 26. [Explanation of symbols]

[0047] 1. Extrusion blow molding containers 10 Mouth 20 Container body 21 External wall 21a Upper part 21b Step 21c lower part 22 Bottom wall 22a Grounding part 22b Recess 22c Pinch-off section 23 Inner wall 23a Side 23b Side 24 Aperture 25 Gripping part 26 Body side part 30 Outer parting line 31 Inner parting line 32 Annular cutting section 40 Convex 50 Mold 51 Type 1 51a 1st Island Nest 52 Type 2 52a 2nd Island Nest 53 Cavity 53a Part 1 53b Part 2 53c Part 3 54 パリソン 54a Part 1 54b Part 2 54c Part 3 O Axis

Claims

1. A synthetic resin extrusion blow molded container having a cylindrical mouth portion and a container body portion integrally connected to a lower end of the mouth portion, The container body portion is A cylindrical outer wall; A bottom wall closing the lower end of the outer wall; an annular inner peripheral wall integrally connected to the outer surface wall at both sides thereof to define an opening in the outer surface wall penetrating the outer surface wall; an annular cut-off portion formed on a surface of the inner circumferential wall and extending annularly along a circumferential direction of the inner circumferential wall; an extrusion blow molded container having a protrusion that is thicker than the inner peripheral wall, the protrusion being integral with the inner peripheral wall, extending along the annular cut-off portion, and protruding from the inner peripheral wall toward the opening.

2. 2. The extrusion blow molded container according to claim 1, wherein the cross section of the protrusion perpendicular to the axis of the container body is arc-shaped.

3. 3. The extrusion blow molded container according to claim 1, wherein one side of the opening of the container body portion forms a gripping portion, the other side of the opening of the container body portion forms a main body side portion having a larger diameter than the gripping portion, and the convex portion is provided on the inner wall on the other side of the opening of the container body portion.

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