Resin container, apparatus and method for manufacturing resin container, and blow molding metal mold

Abstract

The present invention provides: a resin container having a hollow grip part, the resin container exhibiting enhanced drop resistance due to increased rigidity of a through-hole outer edge part; an apparatus and a method for manufacturing the resin container; and a blow molding metal mold. A resin container according to one aspect of the present invention comprises: a neck part that forms an inlet / outlet part for accommodated matter; a body part connected to the neck part; a bottom part connected to the body part and configured so as to close up a lower end of the body part; and a hollow grip part connected to and communicating with the body part. A through hole penetrating in a direction intersecting a central axis of the resin container is formed by the body part and the grip part. A reinforcing coupling part that is formed so as to join the body part and the grip part is further provided between the body part and the grip part facing the through hole and opposing each other.

Description

Resin container, manufacturing apparatus and method for resin container, and blow molding die

[0001] The present invention relates to a resin container, a manufacturing apparatus and method for a resin container, and a blow molding die, and particularly relates to a resin container provided with a hollow gripping portion, its manufacturing apparatus and method, and a blow molding die.

[0002] Conventionally, a technique for manufacturing a resin container in which a hollow gripping portion (handle) is integrally formed with the body portion of the container by an injection stretch blow molding method is known. When manufacturing a resin container provided with a hollow gripping portion by injection stretch blow molding, for example, a preform inflated to a certain size by preliminary blowing is shaped while being sandwiched between a pair of blow split dies having protrusions for forming through holes for the gripping portion. As a result, in the through hole forming portion, a container in a state where the sandwiched resin is welded is obtained. Next, by punching out the welded portion, a container having a hollow gripping portion is obtained.

[0003] For example, the handled container disclosed in Patent Document 1 includes a hollow and elongated gripping portion formed on the side surface portion (body portion) of the container, and this gripping portion is connected to the side surface portion of the container by a first connection end portion and a second connection end portion provided at a position closer to the bottom surface portion of the container than the first connection end portion. In this handled container, the gripping portion is formed such that the cross-sectional area of the gripping portion when cut by a plane orthogonal to the central axis of the container gradually decreases from the second connection end portion toward the first connection end portion. Thereby, when the container is turned upside down and washed, washing water or the like is easily guided to the gripping portion, making it easy to wash the inside of the gripping portion.

[0004] Japanese Patent No. 7106530

[0005] In resin containers with such gripping sections, the presence of through-holes in the body tends to result in inferior drop resistance compared to general resin containers without through-holes. Specifically, when a hollow container with a gripping section filled with liquid and sealed is dropped, water hammer from the bottom of the container propagates to the outer edge of the through-hole and its vicinity (hereinafter referred to as the "through-hole outer edge"), causing the through-hole outer edge on the container body side to bulge and deform, making it prone to cracking. Furthermore, this tendency is thought to become more pronounced as the capacity of the container increases. Therefore, there is a need to improve the cracking susceptibility of the through-hole outer edge and enhance drop resistance in resin containers with hollow gripping sections.

[0006] The present invention has been made in view of these problems, and aims to provide a resin container having a hollow gripping portion in which the rigidity of the outer edge of the through hole is increased to improve drop resistance, a manufacturing apparatus and method for manufacturing the resin container, and a blow molding die.

[0007] A resin container according to one aspect of the present invention comprises a neck portion that forms an entrance and exit for the contents, a body portion connected to the neck portion, a bottom portion connected to the body portion and configured to close the lower end of the body portion, and a hollow grip portion connected to and communicating with the body portion. In this resin container, a through hole is formed by the body portion and the grip portion, penetrating in a direction intersecting the central axis of the resin container. Furthermore, a reinforcing connecting portion is provided between the body portion and the grip portion, which face each other and are adjacent to the through hole, so as to connect the body portion and the grip portion.

[0008] Furthermore, an apparatus for manufacturing a resin container according to one aspect of the present invention comprises a neck portion that forms an entrance / exit for the contents, a body portion connected to the neck portion, a bottom portion connected to the body portion and configured to close the lower end of the body portion, and a hollow grip portion connected to and communicating with the body portion. The resin container has a through hole formed by the body portion and the grip portion in a direction intersecting the central axis of the resin container, and further comprises a reinforcing connecting portion formed between the body portion and the grip portion facing each other and facing the through hole, so as to connect the body portion and the grip portion. The manufacturing apparatus comprises an injection molding section that manufactures a bottomed preform by injection molding, and a blow molding section that manufactures a resin container by blow molding the injection-molded preform. This blow molding section comprises a blow molding die which is a pair of split molds that define the outer shape of the resin container. This blow molding die has a pair of detachable nesting molds which are configured to face each other with a gap when the mold is closed and which form cut-out portions that will become through holes when later cut out of the preform. This pair of nested units is provided with recesses for forming reinforcing connecting sections.

[0009] Furthermore, a blow molding die according to one aspect of the present invention is a blow molding die used in a blow molding apparatus for manufacturing a resin container by blow molding a resin preform. The resin container comprises a neck portion that forms an entrance and exit for the contents, a body portion connected to the neck portion, a bottom portion connected to the body portion and configured to close the lower end of the body portion, and a hollow grip portion connected to and communicating with the body portion. In this resin container, a through hole is formed by the body portion and the grip portion, penetrating in a direction intersecting the central axis of the resin container. In addition, a reinforcing connecting portion is further provided between the body portion and the grip portion, which face each other and are facing each other with respect to the through hole, so as to connect the body portion and the grip portion. The blow molding die has a pair of split molds that define the outer shape of the resin container, and has a pair of removable nesting molds that are configured to face each other with a gap when the blow molding die is closed, and which form a cut-out portion that will become a through hole when later cut out from the preform. The pair of nesting molds are provided with recesses for forming the reinforcing connecting portion.

[0010] Furthermore, a method for manufacturing a resin container according to one aspect of the present invention is a method for manufacturing a resin container comprising: a neck portion that forms an entrance and exit for the contents; a body portion connected to the neck portion; a bottom portion connected to the body portion and configured to close the lower end of the body portion; and a hollow grip portion connected to and communicating with the body portion. The resin container has a through hole formed by the body portion and the grip portion in a direction intersecting the central axis of the resin container, and further comprises a reinforcing connecting portion formed between the body portion and the grip portion facing each other and facing the through hole, so as to connect the body portion and the grip portion. The manufacturing method comprises an injection molding step of manufacturing a bottomed preform by injection molding, and a blow molding step of manufacturing a resin container by blow molding the injection-molded preform. The blow molding step includes a pre-blow molding step of blow molding an intermediate molded body by introducing pressurized gas into the preform and stretching it. Furthermore, the blow molding process includes a gripping portion molding step in which an intermediate molded body is placed in a pair of split molds that define the outer shape of a resin container, each split mold having a pair of nesting molds configured to face each other with a gap when the pair of split molds are closed and provided with recesses for forming reinforcing connecting portions, and the pair of split molds are closed to form a gripping portion by creating a portion to be cut out, which will become a through hole when later cut out, and a reinforcing connecting portion in the intermediate molded body. Furthermore, the blow molding process includes a final blow molding step in which pressurized gas is introduced into the intermediate molded body on which the portion to be cut out and the reinforcing connecting portion have been formed, thereby blow molding the resin container before the through hole is formed.

[0011] According to the present invention, it is possible to provide a resin container having a hollow gripping portion, in which the rigidity of the outer edge of the through hole is increased to improve drop resistance, as well as a manufacturing apparatus and method for manufacturing the resin container, and a blow molding die.

[0012] This is a front view of a resin container according to one embodiment of the present invention. This is a cross-sectional view along the line B-B in Figure 1. This is a schematic diagram showing an example of the configuration of a resin container manufacturing apparatus according to one embodiment. This is a flowchart showing the steps of a resin container manufacturing method according to one embodiment. This is a diagram illustrating a preliminary blow molding section. This is a diagram illustrating a final blow molding section. This is a diagram illustrating a flat plate section and a reinforcing connecting section formed by the insert mold of a blow molding die. This is a diagram illustrating an insert mold that a blow molding die has. This is a diagram illustrating the final blow in the final blow molding section. This is a front view of a resin container according to a modified example. This is a diagram illustrating an insert mold used in the manufacture of a resin container according to a modified example. This is a front view of a resin container according to another modified example. This is a diagram illustrating an insert mold used in the manufacture of a resin container according to another modified example.

[0013] Embodiments of the present invention will be described below with reference to the drawings. In the embodiments, for the sake of clarity, structures and elements other than the main parts of the present invention will be simplified or omitted in the description. Also, the same elements will be denoted by the same reference numerals in the drawings. Note that the shapes and dimensions of each element shown in the drawings are schematic representations and do not represent the actual shapes and dimensions.

[0014] Furthermore, in the attached drawings, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system where appropriate. Each of the XYZ directions is a relative direction set with respect to the upright resin container 1 shown in Figure 1. The X direction is the left-right direction (width direction) in Figure 1. The Y direction is the up-down direction (height direction) in Figure 1 and is perpendicular to the X direction. The Z direction is the vertical direction (depth direction) of the paper in Figure 1 and is perpendicular to both the X and Y directions.

[0015] <Overview of the Resin Container> First, the resin container 1 according to this embodiment will be described. Figure 1 is a front view of the resin container 1 according to this embodiment. The raw material of the resin container 1 (i.e., the raw material of the preform 20 described later) is a thermoplastic synthetic resin, which can be appropriately selected depending on the application of the container. Specific types of materials include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (polycyclohexanedimethylene terephthalate), Tritan (Tritan®: a polyester copolymer using cyclobutanediol as a monomer, manufactured by Eastman Chemical Co.), PP (polypropylene), PE (polyethylene), PC (polycarbonate), PES (polyethersulfone), PPSU (polyphenylsulfone), PS (polystyrene), COP / COC (cyclic olefin polymer), PMMA (polymethyl methacrylate: acrylic), PLA (polylactic acid), and others.

[0016] As illustrated in Figure 1, the resin container 1 comprises a neck portion 2, a body portion 4, a bottom portion 5, and a grip portion 6. The resin container 1 may also have a shoulder portion 3 connecting the neck portion 2 and the body portion 4, which widens in diameter towards the body portion 4. The resin container 1 is manufactured by biaxial stretch blow molding (stretch blow molding).

[0017] The neck portion 2 is formed in a substantially cylindrical shape with an opening A at its upper end, and the opening A serves as an inlet and outlet for the liquid or solid contents of the resin container 1. A threaded portion 7 may be formed on the outer surface of the neck portion 2 to allow the attachment of a lid portion (not shown).

[0018] The body portion 4 is a roughly cylindrical part that connects to the neck portion 2. The body portion 4 extends in a circular motion around the central axis C of the resin container 1 and forms the side surface of the resin container 1.

[0019] The bottom portion 5 is connected to the body portion 4 and is configured to close the lower end of the body portion 4. The body portion 4 and the bottom portion 5 define the storage space for the contents of the resin container 1.

[0020] The grip portion 6 is provided to connect to the body portion 4 and is formed in a hollow shape that communicates with the inside of the body portion 4. As shown in Figure 1, the body portion 4 and the grip portion 6 form a through hole H that penetrates in the Z direction, intersecting the central axis C of the resin container 1. The formation of the through hole H makes it easy for the user of the resin container 1 to grasp the grip portion 6 with their palm and fingers, improving the convenience of transporting the resin container 1. Furthermore, if the resin container 1 has a capacity of, for example, about 2 liters and is used to hold beverages, it becomes easier for the user to handle the resin container 1 when drinking directly from the neck portion 2.

[0021] In the body portion 4 and the grip portion 6, a thickened portion 8 is formed on the outer edge of the through hole H and the surrounding area (through hole outer edge), where the thickness of the container wall is greater than the average thickness of the body portion 4 and the grip portion 6. The thickened portion 8 improves the strength of the through hole outer edge and improves the drop resistance of the through hole outer edge. In this embodiment, the thickened portion 8 is formed around the entire circumference of the through hole outer edge, but it is also possible to form the thickened portion 8 only on a part of the through hole outer edge, or to not form the thickened portion 8 at all.

[0022] Furthermore, as shown in Figure 1, a bridge portion (reinforcement connecting portion) 9 is provided between the body portion 4 and the grip portion 6, facing each other and overlooking the through hole H. The bridge portion 9 is integrally formed with the body portion 4 and the grip portion 6 and functions as a reinforcing member that improves the rigidity of the outer edge of the through hole. As a result, when the resin container 1 is subjected to impact such as dropping, the bulging deformation of the outer edge of the through hole (especially on the body portion 4 side) can be suppressed or reduced, thereby improving the drop resistance of the resin container 1.

[0023] The shape of the bridge portion 9 is not particularly limited as long as it is formed to connect the body portion 4 and the gripping portion 6 and can improve the rigidity of the outer edge of the through hole, but from the viewpoint of not hindering the ease of gripping the gripping portion 6, it is preferable to form the bridge portion 9 in the shape of a rod or plate.

[0024] Furthermore, in order to effectively improve the rigidity of the outer edge of the through hole, it is preferable that the bridge portion 9 be provided so as to extend substantially horizontally within the through hole H. On the other hand, the bridge portion 9 may be provided so as to extend in a direction other than substantially horizontal, as long as it contributes to improving the rigidity of the outer edge of the through hole. For example, the bridge portion 9 only needs to include a component that extends in the horizontal direction, and it is also possible to provide it at an angle so as to approach the neck portion 2 or the bottom portion 5 as it moves toward the central axis C side of the resin container 1.

[0025] Furthermore, in the resin container 1 of this embodiment, only one bridge portion 9 is provided near the center in the Y direction of the outer edge of the through hole. However, the position and number of bridge portions 9 are not limited to this, and any number of bridge portions 9 can be provided at any position. When providing multiple bridge portions 9, from the viewpoint of improving the strength of the outer edge of the through hole in a balanced manner, it is preferable to provide the bridge portions 9 so that they are evenly spaced in the Y direction. That is, when providing two bridge portions 9, it is preferable to provide each bridge portion 9 at positions that divide the length of the outer edge of the through hole in the Y direction into three equal parts, and when providing three bridge portions 9, it is preferable to provide each bridge portion 9 at positions that divide the length of the outer edge of the through hole in the Y direction into four equal parts. Alternatively, the bridge portions 9 may be provided at positions that take into consideration the ease of gripping the gripping portion 6.

[0026] Figure 2 is a cross-sectional view along the line B-B in Figure 1. As illustrated in Figure 2, the thickened portion 8 provided on the outer edge of the through hole in the body portion 4 and the grip portion 6 is formed to protrude inward from the outer surface of the body portion 4 or the grip portion 6 towards the inside of the through hole H.

[0027] Enlarged view B1 of Figure 2 shows a partial enlargement of the body portion 4. As shown in the figure, the portion of the body portion 4 where the thickened portion 8 is formed is formed such that the dimension from the inner surface to the outer surface of the body portion 4 is larger than the portion where the thickened portion 8 is not formed. Also, enlarged view B2 of Figure 2 shows a partial enlargement of the gripping portion 6. As shown in the figure, the portion of the gripping portion 6 where the thickened portion 8 is formed is formed such that the dimension from the inner surface to the outer surface of the gripping portion 6 is larger than the portion where the thickened portion 8 is not formed. In other words, the thickness of the wall portions of the body portion 4 and gripping portion 6 where the thickened portion 8 is formed is thicker than the average thickness of the body portion 4 or the average thickness of the wall portions of the gripping portion 6 at the outer edge of the through hole, respectively.

[0028] In this embodiment, the resin container 1 has a thickened portion 8 that extends around the entire circumference of the outer edge of the through hole. However, the cross-sectional shape and dimensions of the thickened portion 8 may be the same at any point on the outer edge of the through hole, or they may be different at each point.

[0029] Furthermore, the bridge portion 9 provided between the body portion 4 and the grip portion 6 is formed to connect the vicinity of the apex in the X direction of the thick portion 8 formed on the body portion 4 side with the vicinity of the apex in the X direction of the thick portion 8 formed on the grip portion 6 side.

[0030] Generally, when manufacturing a hollow resin container with a handle using injection stretch blow molding, a portion of the preform's body is sandwiched between blow molding dies and blow-molded, resulting in a resin container where the sandwiched resin film is welded together. After blow molding, the welded portion is removed to create a through-hole, resulting in a container with a handle. Due to this manufacturing process, the area surrounding the through-hole in the body and handle, i.e., the outer edge of the through-hole, is formed by the joining of the sandwiched resin films. Such an outer edge of the through-hole is usually weaker than other parts of the resin container. In particular, the body-side surface of the outer edge of the through-hole is prone to bulging deformation due to the propagation of pressure from water hammer generated when the container is dropped, making it susceptible to cracking.

[0031] In contrast, according to the resin container 1 of this embodiment, a thickened portion 8 is formed on the outer edge of the through hole in the body portion 4 and the grip portion 6, projecting inward toward the inside of the through hole H. As a result, the rigidity of the portion where the thickened portion 8 is formed is increased, and deformation when an impact is applied to the outer edge of the through hole can be suppressed.

[0032] Furthermore, in the resin container 1 of this embodiment, a bridge portion 9 is integrally formed between the opposing portions of the outer edges of the through-holes in the body portion 4 and the grip portion 6, connecting the body portion 4 and the grip portion 6. The bridge portion 9 formed in this manner functions as a reinforcing member that supports the outer edges of the through-holes in the body portion 4 and the grip portion 6 from the outside, further improving the rigidity of the outer edges of the through-holes. Therefore, the drop resistance of the resin container 1 can be improved.

[0033] In particular, in the resin container 1 of this embodiment, the bridge portion 9 is formed in the shape of a rod or plate and is provided to extend substantially horizontally within the through hole H, so that the rigidity of the outer edge of the through hole can be effectively increased without impairing the ease of gripping the grip portion 6.

[0034] Furthermore, in the resin container 1 of this embodiment, the bridge portion 9 is formed to connect the thickened portion 8 formed in the body portion 4 and the thickened portion 8 formed in the grip portion 6, so that the bridge portion 9 can more stably support the outer edge of the through hole. As a result, the rigidity of the outer edge of the through hole can be further improved, and the drop resistance of the resin container 1 can be further improved.

[0035] The resin container 1 of this embodiment is formed by first creating a bottomed preform 20 by injection molding, and then stretch blow molding this preform 20. In other words, the resin container 1 of this embodiment is manufactured by injection stretch blow molding (ISBM). The manufacturing method and manufacturing apparatus for the resin container 1 will be described below.

[0036] <Overview of Blow Molding Apparatus 10> Figure 3 is a schematic plan view showing the configuration of the blow molding apparatus 10, which is a manufacturing apparatus for the resin container 1 according to this embodiment. The blow molding apparatus 10 is an example of a manufacturing apparatus for the resin container 1 and employs a hot parison method (also called a one-stage method) in which the resin container 1 is blow molded by utilizing the heat retained during injection molding (internal heat quantity) without cooling the resin preform 20 to room temperature. The blow molding apparatus 10 manufactures the resin container 1 by performing a biaxial stretch blow molding method on the preform 20.

[0037] The blow molding apparatus 10 comprises an injection molding unit 11, a temperature control unit 12, a blow molding unit 13, a removal unit 14, an injection device 15, and a transport mechanism 16. The injection molding unit 11, the temperature control unit 12, the blow molding unit 13, and the removal unit 14 are positioned at predetermined angles (for example, 90 degrees) around the transport mechanism 16.

[0038] (Transport mechanism 16) The transport mechanism 16 includes a transport plate (not shown) that moves in a rotational direction about an axis perpendicular to the plane of the paper in Figure 3. The transport plate is composed of a single disc-shaped flat plate member or a plurality of substantially fan-shaped flat plate members divided for each molding station. One or more neck-shaped members 161 (see Figure 5, etc.) for holding the neck portion of the preform 20 (or intermediate molded body 30, resin container 1) are arranged on the transport plate at predetermined angles.

[0039] The transport mechanism 16 includes a rotating mechanism (not shown) that intermittently rotates the transport plate, for example, counterclockwise when viewed from above. This allows the transport mechanism 16 to transport the preform 20 (or intermediate molded body 30, resin container 1), whose neck is held by the neck mold 161, to the injection molding section 11, the temperature control section 12, the blow molding section 13, and the removal section 14 in that order. In the transport mechanism 16, the preform 20 is transported to each section with its neck facing upwards and its longitudinal direction aligned vertically in an upright position. The transport mechanism 16 also includes a lifting mechanism (vertical mold opening / closing mechanism) and a mold opening mechanism for the neck mold 161, which perform operations such as raising and lowering the transport plate, and mold closing and mold opening (release) in the injection molding section 11, etc.

[0040] (Injection molding section 11) The injection molding section 11 manufactures the preform 20 using an injection mold. As shown in FIG. 3, an injection device 15 for supplying a resin material, which is the raw material of the preform 20, is connected to the injection molding section 11.

[0041] The overall shape of the preform 20 is a bottomed cylindrical shape with one end open and the other end closed (see FIG. 5). The preform 20 has a neck portion formed at one end and having an opening, a body portion connected to the neck portion and formed in a cylindrical shape, and a bottom portion connected to the body portion and closing the other end.

[0042] The injection molding section 11 includes an injection cavity mold, an injection core mold, and a hot runner mold for guiding the molten resin supplied from the injection device 15 into the mold space (none of which are shown). The injection cavity mold and the injection core mold are an example of an injection mold. In the injection molding section 11, the molten resin injected from the injection device 15 is introduced into the mold space defined by the injection mold (the space defining the outer shape of the preform 20), thereby molding the preform 20 having the above-described shape.

[0043] (Temperature adjustment section 12) After the injection-molded preform 20 is removed from the injection mold, it is conveyed to the temperature adjustment section 12 by the conveying mechanism 16. The temperature adjustment section 12 includes a temperature adjustment mold (not shown), and adjusts the temperature (heating) of the preform 20 in a high-temperature state after injection molding by housing it in the temperature adjustment mold maintained at a predetermined temperature. Further, the temperature adjustment section 12 also has a function of adjusting the temperature distribution of the preform 20 to a predetermined state before conveying it to the blow molding section 13.

[0044] The temperature adjustment mold of the temperature adjustment section 12 is configured to be able to accommodate the preform 20 therein, and includes a temperature adjustment pot (or heating pot) for adjusting the temperature of the body portion and the bottom portion of the preform 20 from the outside, and a temperature adjustment rod (or heating rod) inserted into the preform 20 for adjusting the temperature of the preform 20 from the inside.

[0045] As will be described later, in the present embodiment, the temperature adjustment unit 12 adjusts the temperature of the preform 20 to a temperature significantly higher than the softening temperature of the resin material, which is the material. The temperature adjustment unit 12 of the present embodiment is configured to be able to suppress the preform 20 from contacting the temperature adjustment pod even when the preform 20 is stretched downward (so-called drawdown) due to its own weight. For example, a temperature adjustment pod whose position of the pot member facing the bottom of the preform 20 can be changed in the vertical direction, or a rod member that sucks the inner surface of the bottom of the preform 20 to suppress drawdown is provided.

[0046] (Blow molding unit 13) The blow molding unit 13 performs stretch blow molding on the preform 20 whose temperature has been adjusted by the temperature adjustment unit 12 to manufacture the resin container 1 before the through-hole H is formed. As will be described later, the blow molding unit 13 of the present embodiment includes a preliminary blow molding unit 50 (see FIG. 5) that performs preliminary blow molding on the preform 20 to form an intermediate molded body 30, and a final blow molding unit 60 (see FIGS. 6 to 9) that performs final blow molding on the intermediate molded body 30 to form the resin container 1 before the through-hole H is formed. Details of the configuration and operation of each molding unit will be described later. In the blow molding unit 13 of the present embodiment, the preliminary blow molding unit 50 and the final blow molding unit 60 are configured to be in the same position. However, the blow molding unit 13 may be configured such that the preliminary blow molding unit 50 and the final blow molding unit 60 are arranged at different positions, and the intermediate molded body 30 is transported from the preliminary blow molding unit 50 to the final blow molding unit 60.

[0047] (Take-out unit 14) The take-out unit 14 is configured to release the neck portion 2 of the resin container 1 manufactured by the blow molding unit 13 from the neck mold 161 and take out the resin container 1 to the outside of the blow molding apparatus 10.

[0048] <Explanation of the method for manufacturing the container> Next, the method for manufacturing the resin container 1 by the blow molding apparatus 10 of the present embodiment will be described. FIG. 4 is a flowchart showing the steps of the method for manufacturing the resin container 1.

[0049] (Step S401: Injection Molding Process) First, in the injection molding section, molten resin is injected from the injection device 15 into the mold space, which is shaped like a preform and formed by the injection cavity mold, the injection core mold, and the neck mold 161 of the transport mechanism 16, to form a preform 20. Then, after the injection (filling and holding pressure) of the resin material is completed, or after a cooling time has elapsed after the completion of injection, the mold of the injection molding section 11 is opened.

[0050] While not particularly limited, from the viewpoint of manufacturing containers in a high-speed molding cycle, it is preferable to perform mold opening in step S401 without providing a cooling time for the preform 20 in the injection molding die after the completion of resin material injection (filling and holding pressure). On the other hand, if minimal cooling of the preform 20 is performed in the injection molding die, it is preferable that the time for cooling the resin material without applying pressure after the completion of resin material injection in the injection molding section 11 (cooling time) is 1 / 2 or less of the time for injecting the resin material (total time of injection time, filling time and holding pressure time). This allows the surface layer (skin layer) of the body and bottom of the preform 20 to solidify, and the preform 20 can be released from the injection molding die without deformation. In addition, the internal layer (core layer) sandwiched between the surface layers of the body and bottom of the preform 20 retains a high amount of heat, which can shorten the heating time of the preform 20 in the temperature adjustment process.

[0051] Once the injection molding of the preform 20 is complete, the mold in the injection molding section 11 is opened, and the preform 20 is released from the injection cavity mold and the injection core mold. Next, the transfer plate of the transport mechanism 16 moves to rotate by a predetermined angle, and the preform 20, held in the neck mold 161, is transported to the temperature control section 12 while still retaining the heat from the injection molding process.

[0052] (Step S402: Temperature adjustment process) Next, in the temperature adjustment section 12, the preform 20 is placed in a temperature adjustment mold, and the temperature of the preform 20 is adjusted to bring it closer to a temperature suitable for stretch blowing in the blow molding process. The temperature adjustment section 12 adjusts the temperature of the preform 20 at the time it is transported to the blow molding section 13 (immediately before blow molding or pre-blowing) to a temperature significantly higher than the softening temperature of the resin material (for example, in the case of copolyester resin with a softening point of about 95°C to 110°C, the temperature is 170°C to 220°C, which is near the melting point, and in the case of PET resin with a softening point of about 70°C to 80°C, the temperature is 160°C to 200°C, which is near the melting point). For this reason, in the temperature adjustment process, for example, the temperature of the preform 20 transported from the injection molding section 11 is adjusted to a temperature 10°C to 50°C higher than the temperature of the preform 20 at the time it is transported to the blow molding section 13 (immediately before blow molding or pre-blowing).

[0053] In this way, the preform 20 is adjusted to a temperature significantly higher than the softening temperature, which is the normal optimal temperature for stretching the resin material. This allows the resin film portions (flat plate portions P) that are pressed against each other to be well welded together when the resin film portion corresponding to the gripping portion 6 of the intermediate molded body 30 is pressed with the nesting mold 80 during the subsequent blow molding process (gripping portion molding process S404 to final blow molding process S405). Furthermore, it prevents the resin film from rupturing at or near the pressed portion when blow air is introduced. As a result, when the flat plate portions P are later removed from the resin container 1 to form a through hole H, sufficient strength can be provided to the outer edge of the through hole, improving drop resistance.

[0054] After the temperature adjustment process, the transfer plate of the transport mechanism 16 moves to rotate by a predetermined angle, and the temperature-adjusted preform 20 held in the neck mold 161 is transported to the blow molding section 13.

[0055] (Blow molding process) Next, the resin container 1 is blow molded in the blow molding section 13. The blow molding process in this manufacturing method is configured to include a preliminary blow molding process in step S403, a gripping part molding process in step S404, and a final blow molding process in step S405.

[0056] (Step S403: Pre-blow molding process) The pre-blow molding process is a process in which the pre-blow molded body 30 is manufactured by pre-blowing the preform 20, which has been transported to the blow molding section 13 under temperature control conditions. Figure 5 is a schematic diagram showing an example of the configuration of the pre-blow molding section 50. In the figure, the shape of the preform 20 is shown by a dashed line. The pre-blow molding section 50 is equipped with a pre-blow core mold 51 and a stretching rod 52. The pre-blow core mold 51 is inserted into the neck of the preform 20 and is configured to introduce pre-blow air into the preform 20. The stretching rod 52 is inserted through the pre-blow core mold 51 so as to be movable in the vertical direction. When the pre-blow molding section 50 and the final blow molding section 60 are in the same position, the pre-blow core mold 51 is the same as the final blow core mold 63 described later, and the stretching rod 52 is the same as the stretching rod 64 described later.

[0057] In the pre-blow molding process, a stretching rod 52 is inserted into the preform 20, which is held by the neck mold 161 and the pre-blow core mold 51. The tip of the stretching rod 52 is brought into contact with the bottom of the preform 20, and the stretching rod 52 is further displaced downward, thereby stretching the preform 20 in the vertical axis direction (Y direction). As a result, the height (length in the Y direction) of the preform 20 and the intermediate molded body 30 becomes equal to the height of the final molded product, the resin container 1.

[0058] After or in parallel with the stretching in the longitudinal direction by the stretching rod 52, low-pressure (0.10 MPa to 0.30 MPa) blow air (pre-blow air), which is pressurized gas, is introduced into the preform 20 from the pre-blow core mold 51, and the preform 20 is stretched radially. This gives rise to the intermediate molded body 30.

[0059] The intermediate molded body 30 is held by the neck mold 161 and transported to the final blow molding section 60 by the transport mechanism 16. In this embodiment, as described above, the preliminary blow molding section 50 and the final blow molding section 60 are configured to be in the same position, so this transport step is unnecessary.

[0060] The intermediate molded body 30 is molded to a size such that, in the gripping portion molding process described later, a gripping portion 6 can be formed by sandwiching a part of the body of the intermediate molded body 30 between the insert mold 80 attached to the blow cavity mold 51. That is, the intermediate molded body 30 is molded to be larger than the preform 20 and the same size as or slightly smaller than the resin container 1. For example, the intermediate molded body 30 may have a body diameter of 70% to 90% of the body diameter of the resin container 1, and a length that is the same as or 80% to 100% of the length of the resin container 1. In this embodiment, since the temperature of the preform transported to the pre-blow molding section 40 is adjusted to be significantly higher than the softening temperature of the resin material, the radial stretching of the preform 20 can be performed stably and effectively. Therefore, the moldability of the gripping portion 6 and the flat plate portion P (flat resin piece P) in later processes can be improved.

[0061] In the pre-blow molding process, the pressure of the pre-blow air supplied to the preform 20 is set lower than the pressure of the blow air in the final blow molding process, which will be described later, in order to prevent the preform 20 from bursting. In addition, the flow rate of the pre-blow air is set to a relatively low speed. For example, the flow rate (or flow rate) of the pre-blow air may be set to a flow rate that causes the intermediate molded body 30 to expand by 10% to 50%, preferably 20% to 40%, of its volume per second, or to a flow rate that causes the resin container 1 to expand by 10% to 40%, preferably 15% to 35%, of its volume per second.

[0062] (Step S404: Gripping part molding process) Next, in the final blow molding section 60, the blow molding die is closed with the intermediate molded body 30 housed inside. As will be described later, this gripping part molding process involves forming a cut-off section in the intermediate molded body 30 that will later be cut to form a through hole H, and a bridge section 9 that crosses the through hole H, thereby forming the gripping part 6. In other words, the final blow molding section 50 is also the gripping part molding section.

[0063] The blow molding die includes, for example, a blow cavity mold 61 and a blow bottom mold 62, as shown in Figure 6. The blow cavity mold 61, together with the neck mold 161 and the blow bottom mold 62, forms a blow molding space that defines the outer shape of the resin container 1. The final blow molding section 60 includes a final blow core mold 63 and a stretching rod 64. The final blow core mold 63 is inserted into the neck portion of the intermediate molded body 30 and is configured to introduce final blow air into the intermediate molded body 30. The stretching rod 64 is inserted through the final blow core mold 63 so as to be movable in the vertical direction. The final blow core mold 63 and the stretching rod 64 may be the same as the preliminary blow core mold 51 and stretching rod 52 of the preliminary blow molding section 50.

[0064] The blow cavity mold 61 and the blow bottom mold 62 can be configured to control the temperature of each mold, for example, by providing a refrigerant flow path inside and configuring the circulation of a refrigerant such as chiller water through this refrigerant flow path. The blow cavity mold 61 and the blow bottom mold 62 are set to a temperature of, for example, 5°C to 90°C. For example, the temperature of each mold may be set to 60°C to 80°C to alleviate residual stress from injection molding of the resin container 1 (intermediate molded body 30) and improve the strength of the resin container 1. Alternatively, each mold may be set to 5°C to 20°C to shorten the cooling time of the resin container 1.

[0065] The blow cavity mold 61 is a pair of split molds configured to open towards the front and back of the paper in the Z direction of Figure 6. A pair of removable nesting molds 80 are attached to the blow cavity mold 61. Each of the nesting molds 80 is formed to protrude inward from the blow cavity mold 61 and is configured to face each other with a small gap in between when the blow cavity mold 61 is closed.

[0066] Figure 7 illustrates the flat plate portion P and bridge portion 9 formed by the nesting mold 80. The flat plate portion P is an example of a portion to be cut later to form a through hole H. The flat plate portion P is formed when the nesting molds 80 come close together and press against the resin film of the body portion of the intermediate molded body 30. The flat plate portion P is cut off in a later process of the manufacturing process of the resin container 1 to form a through hole H. In this way, the nesting mold 80 is configured to form the flat plate portion P on the intermediate molded body 30. By forming the flat plate portion P on the intermediate molded body 30, a portion that will later become the gripping portion 6 in the resin container 1 (hereinafter simply referred to as the gripping portion of the intermediate molded body 30) is formed on the intermediate molded body 30. The gripping portion of the intermediate molded body 30 is formed to be hollow and in communication with the body portion.

[0067] Furthermore, as will be described later, the nesting mold 80 has a recess 82 provided to traverse the nesting mold 80. The recess 82 functions as a bridge portion forming portion that defines the outer shape of the bridge portion 9. When the nesting mold 80 presses against the body portion of the intermediate molded body 30, a flat plate portion P is not formed in the region where the recess 82 is provided, and a bridge portion 9 is formed that connects to the body portion and gripping portion of the intermediate molded body 30.

[0068] Figure 8 illustrates an example of an insert mold 80 in a blow molding die. As shown in the figure, each insert mold 80 has an annular cutting portion 81 that is formed to protrude toward the other insert mold 80 when attached to the blow cavity mold 61. The cutting portion 81 is configured to press the resin film on the body of the intermediate molded body 30 and bring the resin films into contact with each other.

[0069] Furthermore, the side wall portion 83 of the nesting mold 80 that constitutes the cutting portion 81 has a shape that is inclined (approximately wedge-shaped) so that it decreases in diameter as it approaches the other nesting mold 80 when attached to the blow cavity mold 61. Due to the shape of this inclined side wall portion 83, the thickened portion 8 at the outer edge of the through hole is formed in the body portion and grip portion of the intermediate molded body 30, and in the body portion 4 and grip portion 6 of the later resin container 1. In other words, the side wall portion 83 of the nesting mold 80 functions as a thickened portion forming portion that defines the outer shape of the thickened portion 8 formed at the outer edge of the through hole of the resin container 1.

[0070] Furthermore, when the blow cavity mold 61 is closed, a gap is formed between the opposing cutting portions 81. This gap is set to a range of, for example, 0.03 mm to 0.3 mm, preferably 0.05 mm to 0.20 mm. This gap forms a thin-walled portion, and the thick-walled portion 8 and the flat portion P are connected via the thin-walled portion, making it easy to remove the flat portion P, which is to be cut off later.

[0071] Furthermore, in the nesting mold 80 illustrated in Figure 8, the recess 82 that defines the outer shape of the bridge portion 9 extends in a direction intersecting the longitudinal direction of the nesting mold 80, and the cross-section along the longitudinal direction has a substantially semicircular arc shape. Therefore, the bridge portion 9 formed by the pair of nesting molds 80 has a cylindrical (rod-shaped) form. However, the shape of the bridge portion 9 formed by the recess 82 is not limited to a cylindrical (rod-shaped) form, but may be plate-shaped or any other arbitrary shape. Since the nesting mold 80 is detachable from the blow cavity mold 61, it can be replaced with nesting molds configured to form different shapes and numbers of bridge portions 9 according to the design of the resin container 1.

[0072] Furthermore, the nesting mold 80 may be thermally connected to a heater (not shown) that raises the temperature of the resin in contact with the nesting mold 80, thereby facilitating the welding of the resin films together. The heater may be provided inside or near the cutting section 81.

[0073] As illustrated in Figure 7, in the final blow molding process, the intermediate molded body 30 is first housed between the open blow cavity molds 61 in the final blow molding section 60. When the blow cavity molds 61 are closed in this state, the insert molds 80 attached to each split mold of the blow cavity molds 61 move closer to each other. The cutting portions 81 and recesses 82 of the insert molds 80 come into contact with the resin film of the intermediate molded body 30, pressing and deforming the contact portion. As a result, a flat portion P is formed by the resin film in the area surrounded by the cutting portions 81, and a bridge portion 9 is formed by the resin film sandwiched in the recesses 82. With the formation of the flat portion P and bridge portion 9 on the body of the intermediate molded body 30, a gripping portion of the intermediate molded body is formed at a position opposite the body and the flat portion P and bridge portion 9.

[0074] (Step S405: Final blow molding process) In the final blow molding process, pressurized blow air (final blow air) is supplied from the final blow core mold 63 to the intermediate molded body 30, which has the flat plate portion P, bridge portion 9, and gripping portion formed thereon. This stretches each part and shapes it into the form of the resin container 1. The pressure of the final blow air supplied to the intermediate molded body 30 in the final blow molding process is set higher than the pressure of the preliminary blow air. Furthermore, in order to successfully mold the resin container 1, which has a relatively complex three-dimensional shape due to the gripping portion 7, the final blow molding process may have multiple stretching processes. For example, the final blow molding process may consist of a primary blowing process in which stretching blow is performed at a lower pressure (e.g., 0.3 MPa to 0.5 MPa) and a secondary blowing process in which stretching blow is performed at a higher pressure (e.g., 0.5 MPa to 3.5 MPa).

[0075] In the final blow molding process, the final blow air is introduced into the intermediate molded body 30 from the final blow core mold 63, and the intermediate molded body 30 is shaped into the final molded product, the resin container 1. At this stage, the flat plate portion P, which is to be cut off, has not been removed, so the through hole H has not been formed, but the shapes of the body portion 5 and the grip portion 7 surrounding the through hole H are completely formed. At this time, the outer shape of the thickened portion 8 is also defined to match the shape of the side wall portion 83 of the insert mold 80, which is the thickened portion forming portion. As described above, the side wall portion 83 of the insert mold 80 has a shape that is inclined so that the diameter decreases towards the inside of the blow molding space, so the resin pressed by the insert mold 80 flows and accumulates, forming the thickened portion 8.

[0076] Once the final blow molding process is complete, the blow cavity mold 61 is opened, and the final blow core mold 63 is removed from the neck portion 2 of the resin container 1. This allows the resin container 1 to move out of the blow molding section 13.

[0077] (Step S406: Container Removal Process) The resin container 1, released from the blow molding die, is carried to the removal section 14 by the transport mechanism 16 while still held in the neck mold 161. In the removal section 14, the neck portion 2 of the resin container 1 is released from the neck mold 161, and the resin container 1 is removed to the outside of the blow molding apparatus 10. The neck mold from which the resin container 1 has been released is then transported again to the injection molding section 11 by the transport mechanism 16 and used in a new manufacturing cycle.

[0078] Furthermore, the flat portion P of the resin container 1 needs to be prevented from falling off the resin container 1 until the resin container 1 is removed from the blow molding apparatus 10 at the removal section 14. In this blow molding apparatus 10, the resin container 1 can be manufactured with the thick portion 8 and the flat portion P connected at the thin portion, thus preventing the flat portion P from falling off at an unintended timing. The flat portion P is cut off from the resin container 1 after the resin container 1 is removed from the blow molding apparatus 10, thereby forming a through hole H.

[0079] As described above, one container manufacturing cycle in the manufacturing method of the resin container 1 is completed. Thereafter, by moving the transfer plate of the transport mechanism 16 by a predetermined angle, each of the steps S401 to S406 described above is repeated. When the blow molding apparatus 10 is in operation, the manufacturing of four sets of containers, each with a time difference between each step, is carried out in parallel. Furthermore, in the configuration in this embodiment, where the preliminary blow molding step and the final blow molding step are performed in the same location, the time for each of the injection molding step, temperature adjustment step, blow molding step, and container removal step is the same length. Similarly, the transport time between each step is also the same length.

[0080] The effects of this embodiment will now be described. According to this embodiment, the resin container 1 comprises a neck portion 2 that forms an entrance and exit for the contents, a body portion 4 connected to the neck portion 2, a bottom portion 5 connected to the body portion 4 and configured to close the lower end of the body portion 4, and a hollow grip portion 6 connected to and communicating with the body portion 4. In this resin container 1, a through hole H is formed by the body portion 4 and the grip portion 6, penetrating in a direction intersecting the central axis C of the resin container 1. Furthermore, a bridge portion 9 is provided between the body portion 4 and the grip portion 6, which face each other and are located across the through hole H, so as to connect the body portion 4 and the grip portion 6.

[0081] In the resin container 1 of this embodiment, a bridge portion 9 is integrally formed between the body portion 4 and the grip portion 6 so as to connect the body portion 4 and the grip portion 6, at opposing portions on the outer edges of the through-holes of the body portion 4 and the grip portion 6. The bridge portion 9 formed in this manner functions as a reinforcing member that supports the outer edges of the through-holes of the body portion 4 and the grip portion 6 from the outside, further improving the rigidity of the outer edges of the through-holes. Therefore, the drop resistance of the resin container 1 can be improved. In particular, in the resin container 1 of this embodiment, the bridge portion 9 is formed in the shape of a rod or plate and is provided to extend substantially horizontally within the through-hole H, so that the rigidity of the outer edges of the through-hole can be effectively increased without impairing the ease of gripping the grip portion 6. Furthermore, in the resin container 1 of this embodiment, the bridge portion 9 is formed to connect the thickened portion 8 formed in the body portion 4 and the thickened portion 8 formed in the grip portion 6, so that the bridge portion 9 can support the outer edges of the through-hole more stably. As a result, the rigidity of the outer edges of the through-hole can be further improved, and the drop resistance of the resin container 1 can be further improved.

[0082] Furthermore, the manufacturing apparatus for the resin container 1 of this embodiment includes an injection molding section 11 for manufacturing a bottomed preform 20 by injection molding, and a blow molding section 13 for manufacturing the resin container 1 by blow molding the injection-molded preform 20. The blow molding section 13 includes a pair of split molds, which are blow molding dies (blow cavity dies 61) that define the outer shape of the resin container 1. These blow molding dies are configured to face each other with a gap when the mold is closed, and have a pair of removable insert dies 80 that form flat plate portions P which become through holes H when later cut out of the preform 20. The pair of insert dies 80 are provided with recesses 82 for forming bridge portions 9.

[0083] Furthermore, the manufacturing method of the resin container 1 of this embodiment includes an injection molding step S401 for manufacturing a bottomed preform 20 by injection molding, and a blow molding step (S403 to S406) for manufacturing the resin container 1 by blow molding the injection-molded preform 20. The blow molding step includes a preliminary blow molding step S403 in which pressurized gas is introduced into the preform 20 and stretched to blow-molde it into an intermediate molded body 30. The blow molding step also includes a gripping part molding step S404 in which the intermediate molded body 30 is placed in a pair of split molds (blow cavity molds 61) which define the outer shape of the resin container 1, and each split mold has a pair of nesting molds 80 configured to face each other with a gap when the pair of split molds are closed, and is provided with recesses 82 for forming a bridge part 9, and the gripping part 6 is formed in the intermediate molded body 30 by placing the intermediate molded body 30 in the intermediate molded body 30 and closing the pair of split molds. Furthermore, the blow molding process includes a final blow molding step S405 in which pressurized gas is introduced into the intermediate molded body 30 on which the flat plate portion P and bridge portion 9 are formed, thereby blow molding the resin container 1 before the through hole H is formed.

[0084] According to the manufacturing apparatus and method for resin containers of this embodiment, a blow molding die (blow cavity mold 61) having an insert mold 80 provided with a recess 82 for forming a bridge portion 9 can be used to form a gripping portion 6 on an intermediate molded body 30 by forming a flat plate portion P and a bridge portion 9. Therefore, the flat plate portion P, which is a portion to be cut out to become a through hole H when later cut off, and the bridge portion 9, which reinforces the outer edge of the through hole, can be easily formed in a single process. Furthermore, since the bridge portion 9 can be formed integrally with the body portion 4 and gripping portion 6 of the resin container 1, the rigidity of the outer edge of the through hole of the resin container 1 can be effectively increased by the bridge portion 9, and the drop resistance of the resin container 1 can be greatly improved. In addition, the insert mold 80 is detachable from the blow cavity mold 61. Therefore, by changing the insert mold, resin containers having different shapes and numbers of bridge portions 9 can be easily manufactured.

[0085] Here, a modified example of this embodiment, a resin container 100, will be described with reference to Figures 10 and 11. Components similar to those in the resin container 1 described above are denoted by the same reference numerals, and redundant explanations are omitted. As shown in Figure 10, the resin container 100 differs from the resin container 1 described above in that a plurality of small gripping holes S are formed within the through-hole H by the shape of the bridge portion 109.

[0086] Each gripping hole S can be formed in a circular, elliptical, oblong, or rounded polygonal shape, and in the resin container 100, all of the gripping holes S are formed in a circular shape. In the example of the resin container 100 shown in Figure 10, three bridge portions 109 that define the shape of the gripping holes S are arranged in the Y direction, so that four gripping holes S are also arranged in the Y direction. In this example, the four gripping holes S are formed to have different sizes (diameters), with those closer to the neck portion 2 having a larger diameter.

[0087] Each bridge portion 109 has a shape that defines a part of the shape of the adjacent circular gripping hole S. In this example, each bridge portion 109 has a shape that defines a part of the lower arc of the gripping hole S adjacent to the neck portion 2 side and a part of the upper arc of the gripping hole S adjacent to the bottom portion 5 side. Therefore, each bridge portion 109 has the smallest width in the Y direction at its center position in the X direction, and the width in the Y direction gradually increases as it moves away from the center position in the X direction. Due to the shape of the bridge portion 109, the bridge portion 109 connects to the thickened portion 108 of the body portion 4 and gripping portion 6 at the position where the width in the Y direction is largest, so that the outer edges of the through holes of the body portion 4 and gripping portion 6 can be more firmly supported and the rigidity can be improved. As a result, the resin container 100 can be given high drop resistance. Because there is a structure in which multiple bridge portions 109 are arranged in such a manner that they cross the through holes H, the drop resistance of the resin container 100 is increased.

[0088] Furthermore, the shape of each gripping hole S is mainly defined by the bridge portion 109 and the outer edge of the through hole. These multiple gripping holes S are configured so that a user can pass their fingers through them when gripping the gripping portion 6 of the resin container 100. For example, by passing different fingers through each of the multiple gripping holes S to grip the gripping portion 6, the load when lifting the resin container 100 is distributed to each finger, thereby preventing a large load from being placed on only some fingers.

[0089] Figure 11 shows a nesting mold 180 used in the manufacture of the resin container 100. The nesting mold 180 is attached to the blow cavity mold 61 and used in the gripping part molding step (step 404) of the manufacturing process of the resin container 100. The manufacturing process of the resin container 100 is the same as that of the resin container 1, except that the nesting mold 180 is used instead of the nesting mold 80.

[0090] As shown in the figure, each nesting mold 180 has four annular cutting portions 181 corresponding to the shapes of the four gripping holes S, and recesses 182 are provided between each cutting portion 181 to define the outer shape of the bridge portion 109. In addition, the side wall portion 183 provided near the outer circumference of the nesting mold 180 functions as a thickness-forming portion that defines the outer shape of the thickness portion 108 formed on the outer edge of the through hole of the resin container 100, similar to the side wall portion 83 of the nesting mold 80. Similar to the embodiment of the resin container 1, when the blow cavity mold 61, which is a split mold, is closed, the side wall portions of the nesting molds 180 that constitute the cutting portions 181 have a shape that is inclined so that the diameter decreases as it approaches the other nesting mold 180, and a gap of, for example, 0.03 mm to 0.3 mm is provided between the two cutting portions 181 to form a thin-walled portion. Before being removed from the blow molding section 13, the resin container 100 has four sections to be cut, which are connected to the thin film section, and each section to be cut becomes a resin piece P with a shape (for example, circular) corresponding to each nesting mold 180.

[0091] Next, a resin container 200 according to another modification of this embodiment will be described with reference to Figures 12 and 13. As with the modification described above, the same reference numerals are used for components similar to those of the resin container 1 described earlier, and redundant explanations are omitted. As shown in Figure 12, the resin container 200 differs from the resin container 100 according to the modification described above in that it has three small gripping holes S.

[0092] As shown in the figure, the resin container 200 has two elliptical gripping holes S of almost the same shape near the neck 2, and one larger, vertically elongated oval or rounded polygonal gripping hole S near the bottom 5. This allows the user to grip the gripping part 6 of the resin container 200 by, for example, passing their index and middle fingers through the two elliptical gripping holes S and their ring and little fingers through the oval or rounded polygonal gripping hole S. In this case, compared to the resin container 100 where the load is distributed to each finger, the load on the little finger can be reduced, thus reducing the strain on the little finger. A resin container 200 having such gripping holes S is particularly suitable as a relatively large container, for example, having a capacity of 1 gallon (approximately 4 liters) or more.

[0093] Furthermore, the bridge portion 209 of the resin container 200, like the bridge portion 109 of the resin container 100, has a shape that defines a part of the lower arc of the gripping hole S adjacent to the neck portion 2 and a part of the upper arc of the gripping hole S adjacent to the bottom portion 5. Therefore, similar to the bridge portion 109, each bridge portion 209 has a shape in which the width in the Y direction is smallest at the center position in the X direction and gradually increases as it moves away from the center position in the X direction. As a result, the bridge portion 209, like the bridge portion 109, can more firmly support the outer edges of the through holes in the body portion 4 and grip portion 6, thereby improving rigidity and giving the resin container 200 high drop resistance. Since multiple bridge portions 209 are provided so as to cross the through holes H, the drop resistance of the resin container 100 is increased.

[0094] Figure 13 shows a nesting mold 280 used in the manufacture of the resin container 200. The nesting mold 280 is attached to the blow cavity mold 61 and used in the gripping part molding step (step 404) of the manufacturing process of the resin container 200. The manufacturing process of the resin container 200 is the same as that of the resin container 1, except that the nesting mold 280 is used instead of the nesting mold 80.

[0095] As shown in the figure, each nesting mold 280 has three annular cutting portions 281 corresponding to the shapes of the three gripping holes S, and recesses 282 are provided between each cutting portion 281 to define the outer shape of the bridge portion 209. In addition, the side wall portion 283 provided near the outer circumference of the nesting mold 280 functions as a thickness-forming portion that defines the outer shape of the thickness portion 208 formed on the outer edge of the through hole of the resin container 200, similar to the side wall portion 83 of the nesting mold 80. Similar to the resin container 1 and the resin container 100, when the blow cavity mold 61 is closed, the side wall portions of the nesting molds 280 that constitute the cutting portions 281 have a shape that is inclined so that the diameter decreases as it approaches the other nesting mold 280, and a gap of, for example, 0.03 mm to 0.3 mm is provided between the two cutting portions 281 to form a thin-walled portion. Before being removed from the blow molding section 13, the resin container 200 has three cut-off sections connected to the thin film section, and each cut-off section becomes a resin piece P with a shape corresponding to each nesting mold 280 (for example, two circular shapes and one oval shape).

[0096] The present invention has been described above based on embodiments. The present invention is not limited to the above embodiments, and various improvements and design changes may be made without departing from the spirit of the invention. For example, in the above embodiments, an example was described in which the method for manufacturing a resin container of the present invention is carried out using a four-station blow molding apparatus 10 having an injection molding unit 11, a temperature control unit 12, a blow molding unit 13, and a removal unit 14. However, the method for manufacturing a resin container of the present invention may also be carried out using a three-station blow molding apparatus that does not have a temperature control unit. Furthermore, the resin container 1 may be manufactured using a cold parison type (two-step type) blow molding apparatus, such as U.S. Patent No. 7,727,454. In addition, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the above description, and all modifications in the sense and scope equivalent to the claims are intended to be included.

[0097] 1, 100, 200... Resin container, 5... Body of resin container, 7... Gripping part of resin container, 8, 108, 208... Thick-walled part, 9, 109, 209... Bridge part, 10... Blow molding machine (resin container manufacturing machine), 11... Injection molding part, 12... Temperature control part, 13... Blow molding part, 20... Preform, 30... Intermediate molded body, 50... Pre-blow molding part, 60... Final blow molding part, 61... Blow cavity mold (pair of split molds), 80, 180... Nesting mold, 81, 181... Cutting part, 82, 182... Recess, 83, 183... Side wall part of nesting mold, H... Through hole, P... Flat plate part (part to be cut), S... Small hole for gripping

Claims

1. A resin container comprising: a neck portion forming an entrance / exit for contents; a body portion connected to the neck portion; a bottom portion connected to the body portion and configured to close the lower end of the body portion; and a hollow grip portion connected to and communicating with the body portion, wherein the body portion and the grip portion form a through hole that penetrates in a direction intersecting the central axis of the resin container, and a reinforcing connecting portion is further provided between the body portion and the grip portion facing each other and facing the through hole, so as to connect the body portion and the grip portion.

2. The resin container according to claim 1, wherein the reinforcing connecting portion is formed in the shape of a rod or plate and is provided to extend substantially horizontally within the through hole.

3. The resin container according to claim 1, wherein a plurality of the reinforcing connecting parts are provided.

4. The resin container according to claim 1, wherein at least a portion of the circumferential direction of the through hole in the body portion and the grip portion is formed with a thickness greater than the average thickness of the body portion and the grip portion, and protrudes toward the inside of the through hole, and the reinforcing connecting portion is formed to connect the thickened portion formed in the body portion and the thickened portion formed in the grip portion.

5. The resin container according to claim 1, characterized in that the reinforcing connecting portion forms a plurality of small gripping holes within the through hole for gripping the gripping portion by passing fingers through it.

6. The resin container according to claim 5, characterized in that the gripping holes are formed in a circular, elliptical, oblong, or rounded polygonal shape.

7. A manufacturing apparatus for a resin container comprising: a neck portion that forms an entrance / exit for contents; a body portion connected to the neck portion; a bottom portion connected to the body portion and configured to close the lower end of the body portion; and a hollow grip portion connected to and communicating with the body portion, wherein the resin container has a through hole formed by the body portion and the grip portion in a direction intersecting the central axis of the resin container, and further comprises a reinforcing connecting portion formed between the body portion and the grip portion facing each other and facing the through hole, connecting the body portion and the grip portion, the manufacturing apparatus comprising: an injection molding section for manufacturing a bottomed preform by injection molding; and a blow molding section for manufacturing the resin container by blow molding the injection-molded preform, wherein the blow molding section comprises a pair of split molds that define the outer shape of the resin container, A manufacturing apparatus for resin containers, wherein the blow molding die has a pair of removable inserts configured to face each other with a gap when the mold is closed, and which are to be cut out later from the preform to form the through-hole, and the pair of inserts are provided with recesses for forming the reinforcing connecting portion.

8. A blow molding die used in a blow molding apparatus for manufacturing a resin container by blow molding a resin preform, wherein the resin container comprises a neck portion that forms an entrance / exit for contents, a body portion connected to the neck portion, a bottom portion connected to the body portion and configured to close the lower end of the body portion, and a hollow grip portion connected to and communicating with the body portion, wherein the body portion and the grip portion form a through hole that penetrates in a direction intersecting the central axis of the resin container, and a reinforcing connecting portion is further provided between the body portion and the grip portion that face each other facing the through hole and is formed to connect the body portion and the grip portion, wherein the blow molding die comprises a pair of split molds that define the outer shape of the resin container, and has a pair of removable insert molds configured to face each other with a gap when the blow molding die is closed, and which form a cut-out portion that will later be cut out from the preform to become the through hole, and the pair of insert molds are provided with recesses for forming the reinforcing connecting portion.

9. A method for manufacturing a resin container comprising: a neck portion forming an entrance / exit for contents; a body portion connected to the neck portion; a bottom portion connected to the body portion and configured to close the lower end of the body portion; and a hollow grip portion connected to and communicating with the body portion, wherein the resin container has a through hole formed by the body portion and the grip portion in a direction intersecting the central axis of the resin container, and further comprises a reinforcing connecting portion formed between the body portion and the grip portion facing each other and facing the through hole, the manufacturing method comprising: an injection molding step of manufacturing a bottomed preform by injection molding; and a blow molding step of manufacturing the resin container by blow molding the injection-molded preform, wherein the blow molding step comprises a pre-blow molding step of blow molding an intermediate molded body by introducing pressurized gas into the preform and stretching it, A method for manufacturing a resin container, comprising: a gripping portion molding step, in which the intermediate molded body is placed in a pair of split molds that define the outer shape of the resin container, each split mold having a pair of nesting molds configured to face each other with a gap when the pair of split molds are closed and provided with recesses for forming the reinforcing connecting portion; and a final blow molding step, in which pressurized gas is introduced into the intermediate molded body on which the resin container has the cut-off portion and the reinforcing connecting portion formed, thereby molding the gripping portion; and a final blow molding step, in which pressurized gas is introduced into the intermediate molded body on which the cut-off portion and the reinforcing connecting portion are formed, thereby blow molding the resin container before the through-hole is formed.

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