Extrusion blow-molded container and extrusion blow-molding method

Abstract

To provide an extrusion blow-molded container in which a protrusion provided in a bottom has an appropriate wall thickness and an extrusion blow-molding method allowing for forming the extrusion blow-molded container.SOLUTION: An extrusion blow-molded container 1, made of synthetic resin, comprises in one body a cylindrical mouth 10, a body 11 continuing in one body to a lower end of the mouth 10 and a bottom 12 closing a lower end of the body 11. In the extrusion blow-molded container 1, the bottom 12 has a pinch-off portion 31 extending along a parting line 30 and a protrusion 26 disposed closer to a longitudinal end of the pinch-off portion 31 and projecting from a surface of the bottom 12 and, in a portion of the protrusion 26 adjacent to the pinch-off portion 31, a wall increased portion 28 is formed having a wall thickness greater than other portions of the protrusion 26. An extrusion blow-molding method allows for forming the extrusion blow-molded container.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Conventionally, as a container for storing contents such as hand soap, there has been known an extrusion blow molded container made of synthetic resin which has a cylindrical mouth, a body integrally connected to the lower end of the mouth, and a bottom which closes the lower end of the body.

[0003] Such extrusion blow molded containers can be formed by extrusion blow molding (EBM) in which molten synthetic resin material is extruded downward from an extruder to form a cylindrical parison, which is then sandwiched between a left and right split mold to cut off the bottom end, and pressurized air or the like is blown in from the top end to blow the parison into a shape that fits the cavity of the mold. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-083452 A Summary of the Invention [Problem to be solved by the invention]

[0005] As the above-mentioned extrusion blow molded container, there is known a container that is used in an inverted position with the bottom facing upward by attaching a cap with a contact surface to the mouth. For such extrusion blow molded containers, there is a demand for diversification of the shape, such as a container shaped like a character with convex parts that will become ears on the bottom that will become the top of the character's head.

[0006] However, when the shape of the extrusion blow molded container is such that the convex portion partially protrudes from the bottom, as in the case of the extrusion blow molded container of the above-mentioned shape, the parison is stretched more at the convex portion than at the other portion of the bottom when the parison is blow molded, and the thickness of the convex portion after molding becomes extremely thin, making it impossible to ensure the sufficient thickness for a container.

[0007] The present invention has been made in consideration of such problems, and its object is to provide an extrusion blow molded container having a convex portion on the bottom having an appropriate thickness, and an extrusion blow molding method capable of molding such an extrusion blow molded container. [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 and having a cylindrical mouth portion, a body portion integrally connected to the lower end of the mouth portion, and a bottom portion closing the lower end of the body portion, characterized in that the bottom portion has a pinch-off portion extending along a parting line and a convex portion protruding from the surface of the bottom portion at the longitudinal end portion of the pinch-off portion, and a wall-reservoir portion that is thicker than other portions of the bottom portion is formed in the convex portion.

[0009] In the extrusion blow molded container of the present invention having the above-mentioned configuration, it is preferable that an end in the longitudinal direction of the pinch-off portion is disposed on the convex portion.

[0010] In the extrusion blow molded container of the present invention having the above-mentioned configuration, it is preferable that the bottom portion has a pair of the protruding portions arranged at one end and the other end in the longitudinal direction of the pinch-off portion.

[0011] In the extrusion blow molded container of the present invention having the above-mentioned configuration, it is preferable that the bottom portion has a downwardly convex curved shape.

[0012] The extrusion blow molding method of the present invention is an extrusion blow molding method for molding the above-mentioned extrusion blow molded container, comprising: an extrusion process in which a cylindrical parison formed from a molten synthetic resin material is extruded downward from an extruder between a first die and a second die of a mold divided into left and right sides; a pinch-off process in which the lower end of the parison is sandwiched between the first die and the second die and cut off to form the pinch-off portion; and a blow process in which a pressurized medium is supplied into the inside of the parison from a blow nozzle inserted into the upper end of the parison to blow mold the parison into a shape that conforms to the cavity of the mold, and is characterized in that the mold used has a recess for molding the convex portion provided adjacent to the longitudinal end of the pinch-off portion of the cavity. Effect of the Invention

[0013] According to the present invention, it is possible to provide an extrusion blow molded container having a convex portion provided on the bottom portion with an appropriate thickness, and an extrusion blow molding method capable of molding the extrusion blow molded container. [Brief description of the drawings]

[0014] [Figure 1] 1 is a front view of an extrusion blow molded container according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a bottom view of the extrusion blow molded container shown in FIG. [Diagram 3] 2 is a cross-sectional view of a protruding portion of the extrusion blow molded container shown in FIG. 1. [Figure 4] 1 is a diagram showing an internal structure of a mold used in an extrusion blow molding method according to an embodiment of the present invention. [Diagram 5] 5 is a cross-sectional view taken along line AA of the mold shown in FIG. 4. [Figure 6] 2 is a side view of a state in which a parison is extruded from an extruder in the extrusion step of the extrusion blow molding method according to the embodiment. FIG. [Figure 7] 4 is a side view of the parison being cut off by the mold in the cut-off step of the extrusion blow molding method according to the embodiment of the present invention. FIG. [Figure 8] 1 is a cross-sectional view of a front view of a state in which a parison has been cut off by a mold in a cutting step of the extrusion blow molding method according to the present embodiment. FIG. [Figure 9] FIG. 2 is a side view of a parison after it has been blow-molded in the blowing step of the extrusion blow molding method according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An extrusion blow molded container 1 and an extrusion blow molding method according to one embodiment of the present invention will be illustrated and described in more detail below with reference to the drawings.

[0016] 1 and 2, an extrusion blow molded container 1 according to one embodiment of the present invention can be used to store contents such as hand soap. This extrusion blow molded container 1 is made of a synthetic resin such as polyethylene resin (PE), and integrally comprises a mouth portion 10, a body portion 11, and a bottom portion 12.

[0017] 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 on the top and the bottom 12 on the bottom, as shown in Figure 1.

[0018] The mouth 10 is cylindrical with its center on the axis O, and has an external thread 10a integrally formed on its outer circumferential surface. Although not shown in detail, a cap with a contact surface can be attached to the mouth 10 by screwing it onto the external thread 10a. By attaching a cap with a contact surface to the mouth 10, the extrusion blow molded container 1 can be placed in an inverted position during use, with the contact surface of the cap attached to the mouth 10 facing downward and the bottom 12 facing upward.

[0019] The mouth portion 10 may have an annular protrusion instead of the male thread 10a, and the cap may be attached by undercut engagement with the annular protrusion when the cap is tapped. In this case, the mouth portion 10 is not limited to a cylindrical shape, and may be a square or elliptical cylindrical shape, as long as it is tubular.

[0020] The body 11 is generally cylindrical with its center on the axis O, and is integrally connected to the lower end of the mouth 10. The bottom 12 is integrally connected to the lower end of the body 11, and closes the lower end of the body 11. In this embodiment, the body 11 and the bottom 12 are formed in the shape of a character 20.

[0021] The character 20 has a head 21 and a torso 22. The bottom 12 has a downwardly convex curved shape (a substantially hemispherical shape centered on axis O) and constitutes the lower part including the top of the head 21. The torso 11 is generally cylindrical with a narrowed portion 11a centered on axis O, and constitutes the upper part of the head 21 and the torso 22.

[0022] The character 20 is upside down so that when the extrusion blow molded container 1 is in an upright position, the character is in an inverted position with the head 21 facing downward, and when the extrusion blow molded container 1 is in an inverted position during use, the character is in an upright position with the head 21 facing upward.

[0023] The head 21 has projections and recesses to define the eyes 23, nose 24, and mouth 25 of the character 20.

[0024] Further, head 21 is integrally provided with a pair of protrusions 26 that protrude from the surface of bottom 12 toward the opposite side to mouth 10, i.e., downward. Each protrusion 26 is generally in the shape of an inverted triangle when viewed from the front as shown in Fig. 1 and gradually becomes thinner from top to bottom, and is hollow so as to communicate with the internal space of head 21. The pair of protrusions 26 are disposed symmetrically with a gap between them on either side of axis O, and these protrusions 26 represent the ears of character 20.

[0025] The torso 11 has projections and recesses to represent a pair of arms 27 of the character 20.

[0026] The extrusion blow molded container 1 according to this embodiment is formed by extrusion blow molding using a left-right split mold, and therefore has a parting line 30, which is the dividing line of the mold, on its surface. The parting line 30 extends from the upper end of the mouth 10, through the body 11, to the center position of the lower end of the bottom 12 (the position of the axis O) along the side of the character 20, and passes through the center of the pair of protrusions 26 in the thickness direction of the bottom 12.

[0027] Moreover, since the extrusion blow molded container 1 according to this embodiment is formed by extrusion blow molding using a left-right split mold, it has a pinch-off portion 31 at the bottom 12, which is formed by pinching and cutting off a cylindrical parison made of a molten synthetic resin material extruded downward from an extruder between the left-right split mold. The pinch-off portion 31 has an elongated shape extending along the parting line 30, with one end in the longitudinal direction thereof being disposed at one of the protruding portions 26 and the other end in the longitudinal direction thereof being disposed at the other protruding portion 26.

[0028] Thus, in the extrusion blow molded container 1 of this embodiment, the bottom 12 is provided with a pair of protrusions 26 that protrude from the surface of the bottom 12 at one end or the other end of the longitudinal direction of the pinch-off portion 31.

[0029] In this embodiment, the pinch-off portion 31 is configured so that both longitudinal ends are arranged on the corresponding protrusions 26, but the pinch-off portion 31 may be configured so that both longitudinal ends are adjacent to the corresponding protrusions 26 so as to be in contact with them, or so that both longitudinal ends are adjacent to the corresponding protrusions 26 with a small gap between them.

[0030] 2 and 3, a pair of protrusions 26 provided on the bottom 12 each have a recess 28 formed therein that is thicker than the other parts of the bottom 12. Each recess 28 is provided around the longitudinal end of the pinch-off portion 31, and protrudes from the inner surface of a predetermined range of the corresponding protrusion 26 on the side closer to the axis O, making the recess thicker than the other parts.

[0031] The extrusion blow molded container 1 according to this embodiment having the above-mentioned configuration can be formed by an extrusion blow molding method (EBM: Extrusion Blow Molding) according to one embodiment of the present invention using a left-right split mold 40 shown in Figures 4 and 5.

[0032] The mold 40 is a left-right split mold configured by combining a first mold 41 and a second mold 42, and a cavity 40a having a shape corresponding to the outer shape of the extrusion blow molded container 1 is configured by a first cavity 41a provided in the first mold 41 and a second cavity 42a provided in the second mold 42. The cavity 40a has a pair of recesses 43 corresponding to the pair of protrusions 26 of the extrusion blow molded container 1.

[0033] In the extrusion blow molding method for forming the extrusion blow molded container 1, as shown in FIG. 6, the mold 40 is opened with the first die 41 and the second die 42 spaced apart, and a cylindrical parison 51 formed from a molten synthetic resin material is extruded downward from the extruder 50 between the first die 41 and the second die 42 (extrusion process).

[0034] Next, as shown in Fig. 7 and Fig. 8, the mold 40 is closed, and the parison 51 extruded from the extruder 50 is sandwiched between the first mold 41 and the second mold 42, and the lower end of the parison 51 is bitten off between the first mold 41 and the second mold 42, and the upper end of the parison 51 is cut off by a cutter (not shown) (biting and cutting process). At this time, as shown in Fig. 8, the parison 51 is bitten off between a pair of recesses 43 provided in the first mold 41 and the second mold 42 to form the protrusions 26, and at a part of these recesses 43, by the first mold 41 and the second mold 42. In this way, the parison 51 with the upper end open and the lower end sandwiched and closed between the first mold 41 and the second mold 42 is placed inside the cavity 40a of the mold 40.

[0035] Next, a blow nozzle 52 for blow molding is inserted into the upper end of the parison 51 inside the cavity 40a, and a pressurized medium such as pressurized air is supplied from the blow nozzle 52 into the inside of the parison 51, so that the parison 51 is blow-molded into a shape that conforms to the cavity 40a of the mold 40, i.e., into the shape of the extrusion blow-molded container 1, as shown in FIG. 9.

[0036] Once the parison 51 has been formed to conform to the shape of the cavity 40 a of the mold 40 , the mold 40 is then opened and the completed extrusion blow molded container 1 is removed from the mold 40 .

[0037] In the extrusion blow molding method of this embodiment, when the cylindrical parison 51 is sandwiched between the first die 41 and the second die 42 in the pinch-off process, the parison 51 is crushed in a direction perpendicular to the plane of the drawing in Fig. 8, deformed from a cylindrical shape to a flattened shape, and extends in the left-right direction, and the part extending in the left-right direction hits the end of the pinch-off forming part of the mold 40 that pinches the parison 51, preventing it from moving further outward. As a result, the pinched-off parison 51 generates a material pool 51a in which the synthetic resin material forming the parison 51 accumulates in each recess 43.

[0038] Therefore, when the parison 51 placed inside the cavity 40a is blow molded to form the extrusion blow molded container 1 in the blowing process, the portions of the parison 51 that have thicker material at both longitudinal ends, called "pockets 51a," are positioned inside the corresponding recesses 43. Therefore, in the extrusion blow molded container 1 formed by the extrusion blow molding method of this embodiment, even if the bottom 12 is provided with a convex portion 26 that protrudes from the surface of the bottom 12, when the parison 51 is blow molded, the pockets 51a are positioned in the recesses 43 for forming the convex portions 26, so that the thickness of the convex portions 26 does not become extremely thin.

[0039] In this way, the extrusion blow molded container 1 of this embodiment is configured so that a pair of protrusions 26 provided on the bottom 12 protrude from the surface of the bottom 12 at both longitudinal ends of the pinch-off portion 31 extending along the parting line 30, and form wall accumulation portions 28 that are thicker than other parts of the bottom 12.Therefore, the pair of protrusions 26 provided on the bottom 12 can be made to have an appropriate wall thickness suitable for a container.

[0040] In this embodiment, the recesses 43 provided in the cavity 40a of the mold 40 are preferably positioned at a distance from the central axis Op of the parison 51 that is greater than 1 and not greater than 1.7 times half the circumferential length of the parison 51 (outer diameter of the parison 51×π / 2). This allows the portions 51a of the parison 51 that have been cut off to be generated at appropriate positions relative to the recesses 43. The portions 51a may be provided adjacent to the recesses 43 so as to be in contact with each other or adjacent to each other with a small gap therebetween.

[0041] Furthermore, the extrusion blow molded container 1 of this embodiment is configured such that the longitudinal end of the pinch-off portion 31 is arranged in the convex portion 26, so that the meat reservoir portion 28 is reliably formed inside the convex portion 26, and the pair of convex portions 26 provided on the bottom portion 12 can be more reliably made to have an appropriate wall thickness suitable for a container.

[0042] Furthermore, the extrusion blow molded container 1 of this embodiment has a bottom 12 configured to have a pair of protrusions 26 arranged at one end and the other end of the longitudinal direction of the pinch-off portion 31, so that the bottom 12 can be shaped to have a pair of protrusions 26 corresponding to the ears of the character 20, while the pair of protrusions 26 provided on the bottom 12 can have an appropriate thickness suitable for a container.

[0043] Furthermore, the extrusion blow molded container 1 of this embodiment has a bottom 12 that is curved and convex facing downward, so that the bottom 12 can be shaped to correspond to the head 21 of the character 20, while the pair of convex portions 26 provided on the bottom 12 can have an appropriate thickness suitable for a container.

[0044] 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.

[0045] For example, in the above embodiment, the torso 11 and the bottom 12 are shaped like the character 20, and the bottom 12 is provided with a pair of protrusions 26 to represent the ears of the character 20; however, as long as the bottom 12 is provided with at least one protrusion 26 that protrudes from the surface of the bottom 12 at the longitudinal end of the pinch-off portion 31, the shapes of the torso 11 and the bottom 12 are not limited to the character 20 and may be of various shapes, and the protrusion 26 may also be of various shapes as long as it protrudes from the surface of the bottom 12. [Explanation of symbols]

[0046] 1. Extrusion blow molding containers 10 Mouth 10a Male thread 11. Torso 11a Constricted part 12 Bottom 20 Characters 21 Head 22 Body part 23 eyes 24 Nose 25 mouths 26 Convex 27 Arms 28 Meat Reservoir 30 Parting Line 31 Pinch-off section 40 Mold 40a cavity 41 Type 1 41a 1st cavity 42 Type 2 42a 2nd cavity 43 Recess 50 Extruder 51 Parison 51a Meat Pit 52 Blow nozzle O axis Op center axis

Claims

1. A synthetic resin extrusion blow molded container having a cylindrical mouth, a body integrally connected to a lower end of the mouth, and a bottom closing the lower end of the body, The bottom portion is A pinch-off portion extending along the parting line; a protrusion protruding from a surface of the bottom at an end of the pinch-off portion in a longitudinal direction; 2. An extrusion blow molded container comprising: a bottom portion having a wall thickness greater than that of the remaining portion of the bottom portion;

2. The extrusion blow molded container according to claim 1 , wherein an end portion in the longitudinal direction of the pinch-off portion is disposed on the protruding portion.

3. 3. The extrusion blow molded container according to claim 1, wherein the bottom portion has a pair of the protrusions arranged at one end and the other end in the longitudinal direction of the pinch-off portion.

4. 3. The extrusion blow molded container according to claim 1, wherein the bottom portion has a downwardly convex curved shape.

5. 2. An extrusion blow molding method for molding the extrusion blow molded container according to claim 1, comprising the steps of: an extrusion step of extruding a cylindrical parison formed from a molten synthetic resin material downward from an extruder between a first die and a second die of a mold divided into left and right halves; a pinch-off process for forming the pinch-off portion by pinching and cutting off the lower end of the parison between the first mold and the second mold; a blowing step of blowing the parison into a shape conforming to the cavity of the mold by supplying a pressurized medium into the interior of the parison from a blow nozzle inserted into the upper end of the parison, a die having a recess for forming the protrusion provided adjacent to an end of the pinch-off portion of the cavity in the longitudinal direction;

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