Method for manufacturing a double-layer container, method for manufacturing a preform, and apparatus for manufacturing a double-layer container

Abstract

To provide a manufacturing method for manufacturing a peelable container by using a hot parison type blow molding method, a manufacturing method and manufacturing device for a preform, and a peelable container.SOLUTION: There is provided a method and device for manufacturing a double-layer container and preform by using a hot parison type blow molding method, comprising: an injection molding process of injection-molding a preform having a two-layer structure including an outer layer preform (60) and an inner layer preform (80); and a blow molding process of blow molding a preform to mold a double-layer container made of resin. The injection molding process includes: an outer layer molding step of filling an outer layer injection mold (50) to mold the outer layer preform (60) and to mold a thin film portion (61) in a portion of the outer layer preform (60); a thin film portion breaking step of breaking a thin film portion formed in the outer layer molding step; and an inner layer molding step of filling an inner layer injection mold (70) to mold the inner layer preform (80).SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a delaminatable container and an apparatus for manufacturing a delaminatable container. The present invention also relates to a method for manufacturing a preform and a delaminatable container.

Background Art

[0002] Conventionally, there are delaminatable containers that have a double structure consisting of an inner layer and an outer layer, wherein the inner layer delaminates from the outer layer as the content is discharged. In recent years, such delaminatable containers have been called delamination bottles or airless bottles, and are used as containers for seasoning liquids such as soy sauce, and cosmetics such as skin lotion.

[0003] Currently, for manufacturing such delaminatable containers, it is common to use an extrusion blow molding method, and stretch blow molding is rarely used (see Patent Document 1). For example, if a delaminatable container can be manufactured using a one-stage (hot parison) blow molding method in which the injection molding step to the blow molding step are continuously performed, improvements in the appearance, dimensional accuracy, and physical strength of the delaminatable container can be expected, and in addition, the environmental load can be reduced by reducing wasted material.

Prior Art Literature

Patent Literature

[0004]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0005] However, in the case of release containers, the melting point of the outer layer resin material is often set higher than that of the inner layer resin material. Therefore, in the injection molding process to form a two-layer preform, if the high-temperature outer layer resin material is filled after the inner layer has been molded, the surface of the inner layer in contact with the resin material melts and undergoes thermal deformation. For this reason, it was not possible to manufacture release containers using a one-stage (hot parison) blow molding method that performs the injection molding process and the blow molding process continuously.

[0006] Therefore, the present invention aims to provide a manufacturing method for producing a release container using a hot parison blow molding method, a method for producing a preform, a manufacturing apparatus, and a release container. [Means for solving the problem]

[0007] To achieve the above objective, the method for manufacturing a peeling container according to one aspect of the present invention is: An injection molding process for injection molding a two-layer preform having an outer layer and an inner layer, A method for manufacturing a release container, comprising a blow molding step of blow molding the preform to form a resin release container, The injection molding process described above is: An outer layer molding process in which a resin material for the outer layer is filled into a first injection mold to form the outer layer, and a thin film portion is formed on a part of the outer layer, An inner layer molding step is performed in which the inner layer resin material is injected toward the thin film portion to break the thin film portion, and the inner layer resin material, at a temperature lower than the melting point of the outer layer resin material, is filled into a second injection mold through the broken thin film portion to form the inner layer, It holds.

[0008] According to the above method, after the outer layer having a thin film is formed by the outer layer molding process, the inner layer molding process is carried out. In the inner layer molding process, the thin film is ruptured by the injection pressure of the inner layer resin material, and the inner layer resin material, which is at a temperature lower than the melting point of the outer layer resin material, is filled into the second injection mold through the ruptured thin film. At this time, since the inner layer resin material is filled at a temperature lower than the melting point of the outer layer resin material, the outer layer is less likely to undergo thermal deformation even when in contact with the molten, high-temperature inner layer resin material. After the two-layer preform is formed in this way, a resin release container is formed by blow molding the two-layer preform in the blow molding process. Thus, the above method provides a manufacturing method for producing a release container using a hot parison blow molding method.

[0009] Furthermore, a method for manufacturing a preform according to one aspect of the present invention by injection molding is: A method for injection molding a two-layer preform having an outer layer and an inner layer, An outer layer molding process in which a resin material for the outer layer is filled into a first injection mold to form the outer layer, and a thin film portion is formed on a part of the outer layer, An inner layer molding step is performed in which the inner layer resin material is injected toward the thin film portion to break the thin film portion, and the inner layer resin material, at a temperature lower than the melting point of the outer layer resin material, is filled into a second injection mold through the broken thin film portion to form the inner layer, It holds.

[0010] According to the above method, after an outer layer having a thin film is formed by the outer layer molding process, an inner layer molding process is carried out. In the inner layer molding process, the thin film is ruptured by the injection pressure of the inner layer resin material, and the inner layer resin material, at a temperature lower than the melting point of the outer layer resin material, is filled into the second injection mold through the ruptured thin film. At this time, since the inner layer resin material is filled at a temperature lower than the melting point of the outer layer resin material, the outer layer is less likely to undergo thermal deformation even when in contact with the molten, high-temperature inner layer resin material. In this way, a two-layer preform can be manufactured.

[0011] Further, an apparatus for manufacturing a peelable container according to one aspect of the present invention, which comprises: an injection molding unit that injection-molds a preform having a two-layer structure including an outer layer and an inner layer; and a blow molding unit that blow-molds the preform to mold a peelable container made of resin, wherein: the injection molding unit includes: a first injection mold that molds the outer layer resin material supplied from a hot runner mold into the outer layer, and forms a thin film portion on a part of the outer layer in conjunction with a valve pin included in the hot runner mold; and a second injection mold that breaks the thin film portion and molds the filled inner layer resin material into the inner layer.

[0012] Further, a peelable container according to one aspect of the present invention has a two-layer structure of an outer layer and an inner layer, and a part of the inner layer is exposed to the outside of the outer layer via a filling port formed in the outer layer. Effects of the Invention

[0013] According to the present invention, it is possible to provide a manufacturing method for manufacturing a peelable container using a hot parison type blow molding method, a method for manufacturing a preform, a manufacturing apparatus, and a peelable container. Brief Description of the Drawings

[0014] [Figure 1] It is a cross-sectional view showing an example of a dual-structure preform. [Figure 2] It is a cross-sectional view showing a peelable container according to an embodiment of the present invention. [Figure 3] It is a schematic diagram showing an apparatus for manufacturing a peelable container according to an embodiment of the present invention. [Figure 4] (a) is a cross-sectional view of an outer layer injection mold for molding an outer layer preform. (b) is a cross-sectional view of an inner layer injection mold for molding an inner layer preform. [Figure 5] It is a flowchart for explaining the method of manufacturing a peelable container. [Figure 6] ​It is a plan view of the manufacturing apparatus according to the first side surface. [Figure 7] It is a plan view of the manufacturing apparatus according to the second side surface. [Figure 8] It is a plan view of the manufacturing apparatus according to the third side surface. [Figure 9] It is a side view of the manufacturing apparatus according to the third side surface. [Figure 10] It is a plan view of the manufacturing apparatus according to a modified example of the third side surface. [Figure 11] It is a side view of the manufacturing apparatus according to a modified example of the third side surface. MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, for convenience of explanation, the dimensions of each member shown in the present drawings may differ from the actual dimensions of each member in some cases.

[0016] First, with reference to FIG. 1, a preform 10 for molding a peelable container according to an embodiment will be described. FIG. 1 is a cross-sectional view of the preform 10. The preform 10 includes an opening 12, a neck portion 14 connected to the opening 12, a body portion 16 connected to the neck portion 14, and a bottom portion 18 connected to the body portion 16.

[0017] The preform 10 is a resin molded product formed in a cylindrical shape. Further, the preform 10 is a resin molded product having a two-layer structure including an inner layer 22 and an outer layer 24. The ratio of the thickness t2 of the outer layer 24 to the thickness t1 of the inner layer 22 in the body portion 16 is 1.5 or more. From the viewpoint of the transparency of the peeled container to be molded, the ratio of the thicknesses is preferably 3.0 or less.

[0018] The inner layer 22 is made of a synthetic resin (a synthetic resin with excellent moisture barrier properties, gas barrier properties, heat resistance, chemical resistance, etc.) that has properties that allow for stable storage of the contents and suppress deterioration (oxidation), for example, PP (polypropylene). The outer layer 24 is made of a synthetic resin with excellent moldability and transparency, for example, PET (polyethylene terephthalate). The melting point of PP is about 160-170°C. The melting point of PET is higher than that of PP, at about 245-260°C.

[0019] The preform 10 has recesses 26a for air introduction holes. Here, the term "recesses for air introduction holes" formed in the preform as described herein is used to include both through-holes and recesses that do not penetrate. The recesses 26a for air introduction holes are formed in the bottom 18. However, the position in which the recesses 26a for air introduction holes are formed is not limited to the bottom 18. The recesses 26a for air introduction holes are cylindrical or prismatic recesses or holes, and at least two are formed along the circumferential direction of the preform 10. The recesses 26a for air introduction holes may be formed so that during the subsequent stretch blow molding process, a part of the recess 26a (such as a thin film area) breaks off and functions as an air introduction hole for introducing air to separate the outer and inner layers of the release container formed from the preform 10. In addition, a filling port (opening) 27 is formed in the center of the bottom 18, penetrating the outer layer 24. The filling port 27 is filled with a portion 28 of the inner layer 22, which is exposed to the outside of the outer layer 24 so as to block the filling port 27. The recess 26a for the air introduction hole is formed at a position further from the center of the bottom 18 than the position of the filling port 27. The recess 26a may be formed as a through-hole during the injection molding process (outer layer molding process) described later.

[0020] Next, with reference to Figure 2, a release container (two-layer container) 30 according to the embodiment will be described. Figure 2 is a cross-sectional view of the release container 30. The release container 30 is a bottle-shaped resin container obtained by blow molding a preform 10. The release container 30 comprises an opening 12, a neck portion 14 connected to the opening 12, a body portion 36 connected to the neck portion 14, and a bottom portion 38 connected to the body portion 36. The body portion 36 and bottom portion 38 of the release container 30 are formed by the expansion of the body portion 16 and bottom portion 18 of the preform 10 through stretch blow molding. In addition, during this stretch blow molding, a part of the recess 26a of the preform 10 (such as a thin film area) may break, forming an air inlet hole 26 in the release container 30. Furthermore, the recess 26a may be formed into a through-hole shape during the injection molding process (outer layer molding process and inner layer molding process) described later, thereby forming the air inlet hole 26.

[0021] The release container 30 has a two-layer structure, similar to the preform 10. The release container 30 is a resin container with a two-layer structure having an inner layer 42 and an outer layer 44. The ratio of the thickness t12 of the outer layer 44 to the thickness t11 of the inner layer 42 in the body portion 36 is the same as the ratio of the thickness t2 of the outer layer 24 to the thickness t1 of the inner layer 22 in the body portion 16 of the preform 10.

[0022] As described above, an air inlet 26 is formed in the bottom 38 of the peeling container 30. The air inlet 26 is formed to penetrate the outer layer 44. Also, a filling port (opening) 27 is formed in the center of the bottom 38, similar to the preform 10. The filling port 27 is formed to penetrate the outer layer 44. A portion 28 of the inner layer 42 is provided in a state where it is packed into the filling port 27 so as to block the filling port 27. A portion 28 of the inner layer 42 is exposed to the outside of the outer layer 44 through the filling port 27. The thickness of the portion 28 of the inner layer 42 is formed to be thicker than the thickness of the outer layer 44. By providing a portion 28 of the inner layer 42 that is exposed to the outside from the filling port 27 of the outer layer 44, misalignment of the inner layer relative to the outer layer 44 is prevented.

[0023] Next, with reference to Figures 3 and 4, a manufacturing apparatus 100 for the release container 30 according to the embodiment will be described. Figure 3 is a schematic diagram showing the manufacturing apparatus 100 for the release container 30. Figure 4(a) is an outer layer injection mold 50 (an example of a first injection mold) for molding an outer layer preform 60 consisting of the outer layer 24 of the preform 10. Figure 4(b) is an inner layer injection mold 70 (an example of a second injection mold) for molding an inner layer preform 80 consisting of the inner layer 22 of the preform 10.

[0024] As shown in Figure 3, the manufacturing apparatus 100 includes an injection molding section 102 for injection molding the preform 10 and a temperature control section 104 for adjusting the temperature of the molded preform 10. The manufacturing apparatus 100 also includes a blow molding section 106 for blowing the temperature-controlled preform 10 to manufacture the release container 30 and a removal section 108 for removing the manufactured release container 30. The injection molding section 102 consists of a first injection molding section 102a and a second injection molding section 102b. As described above, the manufacturing apparatus 100 is preferably a 5-station type hot parison blow molding apparatus (1-step blow molding apparatus) with at least five molding sections: the first injection molding section 102a, the second injection molding section 102b, the temperature control section 104, the blow molding section 106, and the removal section 108. Alternatively, the manufacturing apparatus 100 may be a 6-station type with additional molding sections. Examples of additional molding sections include a second temperature control section provided between the first injection molding section 102a and the second injection molding section 102b, a second blow molding section provided between the blow molding section 160 and the removal section 108, a post-processing section for the container (container inversion section), a container inspection section, and the like.

[0025] The preform 10 or release container 30 is transported by the transport means 110 within the manufacturing apparatus 100 in the following order: first injection molding section 102a, second injection molding section 102b, temperature control section 104, blow molding section 106, and removal section 108. The first injection molding section 102a, the second injection molding section 102b, the temperature control section 104, the blow molding section 106, and the removal section 108 are positioned at predetermined angles (for example, 72 degrees or 60 degrees each) around the transport means 110. The transport means 110 is composed of a transfer plate, such as a rotating plate. The preform 10 or release container 30 is transported to each section as the transfer plate or rotating plate of the transport means 110 rotates. The preform 10 or the release container 30 may be conveyed to its parts as the rotating plate rotates, with the neck portion 14 supported by a neck mold 56 attached to the rotating plate, as shown in Figures 4(a) and 4(b). The manufacturing apparatus 100 is a hot parison type resin container manufacturing apparatus that continuously manufactures the preform 10 and the release container 30.

[0026] As shown in Figures 4(a) and 4(b), the injection molding section 102 includes an outer layer injection mold 50 located in the first injection molding section 102a for molding the outer layer preform 60, and an inner layer injection mold 70 located in the second injection molding section 102b for molding the inner layer preform 80 inside the outer layer preform 60.

[0027] The outer layer injection mold 50 (an example of a first injection mold) includes an outer layer cavity mold 52 (an example of a first injection cavity mold), an outer layer core mold 54 (an example of a first injection core mold), and a neck mold 56. The outer layer injection mold 50 is configured to form an outer layer preform 60 by pouring (filling (injecting)) an outer layer resin material, such as PET, into the cavity formed by clamping these molds together. The outer layer resin material is supplied from a hot runner mold 59 and poured into the cavity through an outer layer gate 58.

[0028] The outer cavity mold 52 has hole-forming protrusions 53 (an example of a first projection) that project toward the outer core mold 54. The hole-forming protrusions 53 are cylindrical or prismatic protrusions for forming the recesses 26a for the air introduction holes described above in the outer preform 60. At least two or more hole-forming protrusions 53 are formed along the circumferential direction on the inner surface of the bottom of the outer cavity mold 52.

[0029] The hot runner mold 59 has a valve pin 59a that can move toward the outer layer gate 58 within the channel through which the outer layer resin material flows. The valve pin 59a is configured to move through the outer layer gate 58 to a position close to the outer layer core mold 54 after the outer layer resin material has filled the cavity. As a result, a thin film portion 61 is formed in the center of the bottom of the outer layer preform 60, where the thickness of the outer layer is thinner than that of the periphery.

[0030] The inner layer injection mold 70 (an example of a second injection mold) includes an inner layer cavity mold 72 (an example of a second injection cavity mold), an inner layer core mold 74 (an example of a second injection core mold), and a neck mold 56. The neck mold 56 is a common neck mold that moves to the position of the inner layer injection mold 70 while holding the outer layer preform 60 molded in the outer layer injection mold 50. The diameter of the core of the inner layer core mold 74 is formed to be smaller than the diameter of the core of the outer layer core mold 54 by the thickness of the inner layer preform 80 layer. In addition, the size (diameter) of the recess in the inner layer cavity mold 72 when viewed from above and the size (diameter) of the recess in the outer layer cavity mold 52 when viewed from above are formed to be the same diameter. The inner layer injection mold 70 is configured to form an inner layer preform 80 inside the outer layer preform 60 molded by the outer layer injection mold 50 by pouring (filling with molten resin) an inner layer resin material such as PP into the cavity formed when these molds are clamped together.

[0031] The inner layer resin material is supplied from a hot runner mold 79 and poured into the cavity through the inner layer gate 78. The inner layer resin material is poured into the cavity when the thin film portion 61 formed on the outer layer preform 60 is ruptured by the flow of the inner layer resin material. The rupture of the thin film portion 61 of the outer layer preform 60 forms a filling port 27 at the bottom 18 of the preform 10. The inner layer resin material poured into the cavity fills the cavity through the filling port 27.

[0032] The inner cavity mold 72 has a fitting projection 73 (an example of a second projection) that protrudes toward the inner core mold 74. The fitting projection 73 is formed in a position corresponding to the recess 26a for air introduction holes in the outer preform 60 formed by the hole-forming projection 53 of the outer cavity mold 52. When the inner injection mold 70 is clamped, the fitting projection 73 fits into each of the recesses 26a for air introduction holes in the outer preform 60. With the fitting projection 73 fitted into the recesses 26a for air introduction holes, the inner resin material is filled into the inner injection mold 70. The fitting projection 73 fitting into the recesses 26a positions the outer preform 60 in the inner cavity mold 72.

[0033] The temperature control unit 104 includes a temperature control cavity type and a temperature control core type, which are not shown in the figure. A cooling medium, such as water, flows inside the temperature control cavity type and the temperature control core type. The temperature control unit 104 is configured to sandwich the preform 10, which has been molded in the injection molding unit 102, between the temperature control cavity type and the temperature control core type, bringing them into contact, and to adjust the temperature of the preform 10 to a temperature suitable for blow molding. The temperature of the cooling medium flowing inside the temperature control cavity type and the temperature control core type is set to, for example, about 10°C to about 65°C. The temperature control unit 104 may also be configured to include a heating pot type and a heating core type that adjust the temperature of the preform 10 in a non-contact state.

[0034] The blow molding section 106 includes a blow cavity mold (not shown), a stretching rod, and a blow core mold. The preform 10, which is temperature-controlled by the temperature control section 104, is stretched, for example, by the stretching rod, while air (compressed air) is introduced from the blow core mold to inflate the preform 10 into the shape of the blow cavity mold, thereby forming the release container 30.

[0035] The removal section 108 is configured such that the peeling container 30 can be removed by releasing the neck portion 14 of the peeling container 30 from the neck mold 56.

[0036] Next, a method for manufacturing the release container 30 according to the embodiment will be described with reference to Figures 5 and 4. Figure 5 is a flowchart illustrating the method for manufacturing the release container 30. As shown in Figure 5, the method for manufacturing the release container 30 includes an injection molding step S11 for injection molding a preform 10, a temperature control step S12 for temperature adjustment of the preform 10, and a blow molding step S13 for blow molding the preform 10 to form the release container 30.

[0037] First, the injection molding process S11 will be described. The injection molding process S11 includes an outer layer molding process S1 for molding the outer layer preform 60 and an inner layer molding process S2 for molding the inner layer preform 80.

[0038] In the outer layer molding process S1, the outer layer injection mold 50, which consists of an outer layer cavity mold 52, an outer layer core mold 54, and a neck mold 56, is clamped, and the outer layer resin material (e.g., PET) is filled into the cavity of the clamped outer layer injection mold 50 through the outer layer gate 58.

[0039] At this time, a recess 26a for forming an air inlet 26 in the release container 30 is molded into the bottom of the outer layer preform 60. The recess 26a for the air inlet is formed by a hole-forming projection 53 provided on the outer layer cavity mold 52. The hole-forming projection 53 is positioned such that when the outer layer injection mold 50 is clamped, the top of the hole-forming projection 53 is in contact with the outer layer core mold 54, or there is a small gap between them and the outer layer. In this state, the recess 26a for the air inlet can be molded into the outer layer preform 60 by filling the cavity of the outer layer injection mold 50 with the outer layer resin material.

[0040] Furthermore, at this time, a thin film portion 61 is formed in the center of the bottom of the outer layer preform 60, where the thickness of the outer layer is thinner than that of the surrounding area. The thin film portion 61 is formed by a valve pin 59a on a hot runner mold 59 that supplies the outer layer resin material into the cavity of the outer layer injection mold 50. After filling the cavity of the outer layer injection mold 50 with the outer layer resin material, the valve pin 59a is moved toward the outer layer core mold 54, causing the tip of the valve pin 59a to create a depression in the center of the bottom of the outer layer preform 60. By cooling in this state for a predetermined time, the depression becomes the thin film portion 61. It is desirable that the thickness of the thin film portion 61 be 1 / 10 or less of the average thickness of the surrounding bottom.

[0041] After the outer layer resin material has been filled into the cavity, the outer layer preform 60 is molded by maintaining the clamped state of the outer layer injection mold 50 for a predetermined time and then releasing the clamp. At this time, in order to cool the outer layer resin material filled into the cavity, a cooling medium is circulated through circulation paths (refrigerant flow circuits) provided in the outer layer cavity mold 52 and the outer layer core mold 54. The temperature of the cooling medium is set, for example, within the range of approximately 5°C to approximately 20°C. This cools the surface temperature (skin layer temperature) of the outer layer preform 60 to a temperature below the melting point of the inner layer resin material (PP: 160°C), for example, when PET is used as the outer layer resin material and PP is used as the inner layer resin material.

[0042] The molded outer layer preform 60 is raised together with the outer layer core mold 54 and the neck mold 56 to release the outer layer preform 60 from the outer layer cavity mold 52. Next, the outer layer core mold 54 is raised further to release the outer layer core mold 54 from the outer layer preform 60. Then, the outer layer preform 60, held in the neck mold 56, is moved together with the neck mold 56 by the transport means 110 to above the inner layer cavity mold 72 (inner layer molding process).

[0043] In the inner layer molding process S2, the outer layer preform 60 is housed in the inner layer injection mold 70, which is composed of the inner layer cavity mold 72, the inner layer core mold 74, and the neck mold 56, by clamping the neck mold 56, which holds the outer layer preform 60, to the inner layer cavity mold 72 and the inner layer core mold 74 and the neck mold 56. Next, the inner layer resin material (e.g., PP) is filled into the cavity defined by the inner surface of the outer layer preform 60 and the inner layer core mold 74 and neck mold 56 through the inner layer gate 78. The temperature of the inner layer resin material PP to be filled is set to a temperature lower than the melting point of the outer layer resin material that makes up the outer layer preform 60 (e.g., PET: 260°C). In addition, the surface temperature of the outer layer preform 60 when filling with the inner layer resin material is cooled to a temperature below the melting point of the inner layer resin material to be filled (e.g., PP: 160°C).

[0044] When filling the cavity of the inner layer injection mold 70 with the inner layer resin material, the inner layer resin material is first injected toward the thin film portion 61 of the outer layer preform 60. By injecting the inner layer resin material toward the thin film portion 61, the injection pressure causes the thin film portion 61 to rupture, and the inner layer resin material is then filled into the cavity of the inner layer injection mold 70 through the ruptured portion of the thin film portion 61.

[0045] Furthermore, when filling the cavity of the inner layer injection mold 70 with the inner layer resin material, the fitting protrusion 73 provided on the inner layer cavity mold 72 is fitted into the recess 26a for the air introduction hole formed at the bottom of the outer layer preform 60 during filling. Since the fitting protrusion 73 and the recess 26a for the air introduction hole are located in corresponding positions, when the neck mold 56 holding the outer layer preform 60 is clamped to the inner layer cavity mold 72 and the inner layer core mold 74, the fitting protrusion 73 and the recess 26a for the air introduction hole are fitted together.

[0046] After the filling of the inner layer resin material into the cavity is complete, the clamped state of the inner layer injection mold 70 is maintained for a predetermined time, and then the clamp is released to mold the preform 10, which consists of an inner layer preform 80 and an outer layer preform 60. At this time, in order to cool the inner layer resin material filled in the cavity and the outer layer preform 60 in the inner layer injection mold 70, a cooling medium may be flowed through a circulation path (refrigerant flow circuit) provided in the inner layer cavity mold 72 and the inner layer core mold 74. The temperature of the cooling medium is set, for example, within the range of about 5°C to about 20°C.

[0047] The molded preform 10 is raised together with the inner core mold 74 and the neck mold 56 to release the preform 10 from the inner cavity mold 72. Next, the inner core mold 74 is raised further to release the inner core mold 74 from the preform 10. Then, the preform 10, held in the neck mold 56, is rotated together with the neck mold 56 by the transport means 110 and moved to the temperature control unit 104 (temperature control process).

[0048] Next, the temperature control process S12 will be described. The temperature control process S12 is a process for adjusting the temperature of the injection-molded preform 10 to a temperature range suitable for blow molding. In the temperature control process S12, first, the preform 10, which has been moved to the temperature control unit 104, is housed in a temperature control cavity mold (not shown) by lowering the neck mold 56. Next, the temperature control core mold (not shown) is lowered to bring it into contact with the inner surface of the preform 10. By sandwiching the preform 10 between the temperature control cavity mold and the temperature control core mold, the preform 10 is adjusted to a temperature suitable for blow molding. After temperature control, the preform 10 is released from the temperature control core mold by raising the temperature control core mold. Next, the preform 10 is released from the temperature control cavity mold by raising the neck mold 56. Then, the preform 10 held in the neck mold 56 is rotated together with the neck mold 56 by the transport means 110 and moved to the blow molding section 106 (blow molding process). In addition, in the temperature control process S12, a heating pot type and a heating core type may be used to adjust the temperature of the preform 10 in a non-contact manner.

[0049] Next, the blow molding process S13 will be described. In the blow molding process S13, the preform 10 is placed in a blow cavity mold (not shown). The preform 10 is stretched with a stretching rod (not shown) and blow air is introduced from a blow core mold (not shown) to inflate the preform 10 to the shape of the blow cavity mold, thereby forming the release container 30. During the stretch blowing, a part of the recess 26a for the air introduction hole (for example, the bottom) breaks, and the air introduction hole 26 is formed in the release container 30. After that, the release container 30 is released from the mold of the blow molding section 106 and moved to the removal section 108. Alternatively, the recess 26a may be formed into a through hole shape during the injection molding process S11 (outer layer molding process S1 and inner layer molding process S2) to form the air introduction hole 26.

[0050] Currently, the extrusion blow method is the most common method for manufacturing peeling containers, which are composed of two layers, with the stretch blow method being less frequently used. If peeling containers could be manufactured using the stretch blow method, improvements in appearance, dimensional accuracy, and physical strength could be expected, as well as a reduction in environmental impact due to a decrease in waste material. Currently, one practical manufacturing method for release containers using the stretch blow molding method is the hot parison type blow molding method, which utilizes either the inner or outer preform as an insert material. However, this molding method requires an injection molding machine to pre-manufacture the two-layer preform pieces in addition to the blow molding machine, resulting in increased manufacturing costs and processes. Furthermore, in release containers, the melting point of the outer layer resin material is often set higher than that of the inner layer resin material. Therefore, in an injection molding process to form a two-layer preform, for example, if the inner layer preform is molded first and then the outer layer preform is molded, the surface of the inner layer preform that comes into contact with the high-temperature outer layer resin material melts and undergoes thermal deformation when the resin material is filled in. Therefore, it has not been possible to manufacture release containers using a one-stage hot parison type blow molding method that performs the injection molding process and the blow molding process in a continuous manner.

[0051] In contrast, according to the method for manufacturing a release container having the above steps, in the injection molding step S11 of the preform 10, first an outer layer preform 60 having a thin film portion 61 is molded by the outer layer molding step S1, and then an inner layer preform 80 is molded inside the outer layer preform 60 by the inner layer molding step S2. In the inner layer molding step S2, the thin film portion 61 is ruptured by the injection pressure of the PP (resin material for the inner layer), and the PP is filled into the inner layer injection mold 70 through the ruptured thin film portion 61. At this time, the PP that is filled into the inner layer injection mold 70 is filled at a temperature lower than the melting point (260°C) of the PET (resin material for the outer layer) that constitutes the outer layer preform 60. For this reason, even if molten, high-temperature PP comes into contact with the already molded outer layer preform 60 during the PP filling process, thermal deformation of the outer layer preform 60 is unlikely to occur.

[0052] Furthermore, according to the method for manufacturing the release container, in the outer layer molding process S1, after the surface temperature of the outer layer preform 60 falls below the melting point of PP, the process moves to the inner layer molding process S2, where PP is filled into the inner layer injection mold 70. Therefore, the filled PP is less likely to undergo thermal deformation even when it comes into contact with the outer layer preform 60 housed in the inner layer injection mold 70.

[0053] Furthermore, according to the method for manufacturing a release container, in the outer layer molding process S1, after PET is filled into the outer layer cavity mold 52 from the hot runner mold 59, the valve pin 59a of the hot runner mold 59 is moved toward the filled PET, and the tip of the valve pin 59a causes a part of the filled PET to become recessed, thereby forming a thin film portion 61. For this reason, a thin film portion 61 can be formed at the bottom of the outer layer preform 60 by utilizing the valve pin 59a of the valve on the hot runner mold 59, without providing a dedicated mechanism for forming the thin film portion 61.

[0054] Furthermore, according to the method for manufacturing the release container, in the outer layer molding step S1, a recess 26a for air introduction holes is formed in the outer layer preform 60 by a hole-forming protrusion 53 provided on the outer layer cavity mold 52. Based on this recess 26a, an air introduction hole 26 for separating the outer layer and inner layer of the release container 30 can be formed during blow molding.

[0055] Furthermore, according to the method for manufacturing a release container, in the inner layer molding process S2, the fitting protrusion 73 provided on the inner layer cavity mold 72 is fitted into the recess 26a for the air introduction hole formed in the outer layer preform 60, and PP is filled into the inner layer cavity mold 72. Therefore, even if, for example, the bottom of the recess 26a for the air introduction hole is fractured, it is possible to prevent the PP from filling the air introduction hole 26 of the outer layer preform 60 when filling with PP. In addition, since the outer layer preform 60 is positioned in the inner layer cavity mold 72, the cavity (molding space) for the inner layer preform can be formed with good dimensional accuracy.

[0056] Furthermore, according to the method for manufacturing a release container, after the two-layer preform 10 is formed in this manner, a resin release container 30 is formed in the blow molding step S13 by blow molding the two-layer preform 10. Therefore, according to the above method for manufacturing a peeling container, the peeling container 30 can be manufactured using a hot parison blow molding method.

[0057] Furthermore, the manufacturing apparatus 100 for the release container having the above configuration is a four-station type with a temperature control unit 104 provided between the injection molding unit 102 and the blow molding unit 106. The injection molding unit 102 includes an outer layer injection mold 50 for injection molding the outer layer preform 60 and an inner layer injection mold 70 for injection molding the inner layer preform 80. The outer layer injection mold 50 molds the PET supplied from the hot runner mold 59 into the outer layer preform 60 and, in conjunction with the valve pin 59a of the hot runner mold 59, can form a thin film portion 61 at the bottom of the outer layer preform 60. The inner layer injection mold 70 can break the thin film portion 61 of the outer layer preform 60 and mold the PP filled in the inner layer injection mold 70 into the inner layer preform 80. At this time, the PP filled in the inner layer injection mold 70 is filled at a temperature lower than the melting point (260°C) of the PET that constitutes the outer layer preform 60. Therefore, even if molten, high-temperature PP comes into contact with the already molded outer layer preform 60 during PP filling, thermal deformation of the outer layer preform 60 is unlikely to occur. Consequently, the release container manufacturing apparatus 100 can be used to manufacture the release container 30 using a one-stage hot parison type blow molding method that performs the injection molding process and the blow molding process continuously.

[0058] Here, a manufacturing apparatus relating to a different aspect from the embodiment described above will be explained with reference to Figures 6 to 11. Figure 6 is a plan view of the manufacturing apparatus 1100 relating to the first aspect, Figure 7 is a plan view of the manufacturing apparatus 2100 relating to the second aspect, Figure 8 is a plan view of the manufacturing apparatus 3100 relating to the third aspect, and Figure 9 is a side view of the manufacturing apparatus 3100 relating to the third aspect. These other aspects are examples of specific forms of manufacturing apparatus capable of implementing the manufacturing method in the embodiment described above. Note that the dimensions of each component shown in the drawings may differ from the actual dimensions of each component for the sake of explanation, and some components of the same shape (such as neck-shaped components) may be omitted.

[0059] First, the manufacturing apparatus 1100 relating to the first side will be described with reference to Figure 6. The manufacturing apparatus 1100 comprises five molding stations in this order in the circumferential direction: a first injection molding section 1102a, a second injection molding section 1102b, a temperature control section 1104, a blow molding section 1106, and an extraction section 1108. The manufacturing apparatus 1100 includes a transport means 1110 comprising a transport plate 1110a configured to be rotatable about a central axis A, and a neck type support section 1110b that supports and guides a neck (lip) type 1110c configured to hold a resin molded product (preform, container). The transport plate 1100a is a single flat plate-like member (rotating plate) with a substantially disc shape. Each station is arranged at a position that is divided into five equal parts in the circumferential direction about the central axis A of the transport means 1110. The conveying means 1110 is configured to rotate intermittently by 72 degrees at a time, enabling it to sequentially convey the resin molded products held by the neck type 1110c to each station. Five sets of neck types 1110c are provided, corresponding to the five stations. The five sets of neck types 1110c are arranged on the underside of the transfer plate 1100a, corresponding to positions that are divided into five equal parts in the circumferential direction around the central axis A of the transfer plate 1100a. The manufacturing apparatus 1100 has an upper base 1101a that supports the conveying means 1110, and a lower base (machine stand) 1101b located below it. The manufacturing apparatus 1100 further has a conveying means (lifting means) not shown that raises and lowers the upper base 1101a. The conveying means 1110 is configured to simultaneously raise and lower the resin molded products held by the neck type 1110c at each station via the lifting and lowering operation of the upper base 1101a.

[0060] The first injection molding section 1102a is equipped with a first resin injection device 1103a. The first injection molding section 1102a is connected to a first injection molding die (first injection core die, first injection cavity die, neck die). The first injection molding section 1102a molds a first preform by injecting resin from the first resin injection device 1103a into the space (cavity) formed when the first injection molding die is clamped. The second injection molding section 1102b is equipped with a second resin injection device 1103b. The second injection molding section 1102b is connected to a second injection molding die (second injection core die, second injection cavity die, neck die). The second injection molding unit 1102b molds the second preform by injecting resin from the second resin injection device 1103b into the space formed when the first preform is transported and the second injection molding die is clamped, thereby forming a preform comprising the first and second preforms. The first injection cavity mold and the second injection cavity mold are connected to the lower base (machine base) 1101b.

[0061] The first injection molding section 1102a and the second injection molding section 1102b are provided with an integrated clamping plate 1112 that operates simultaneously across the two stations. The first injection core mold and the second injection core mold are connected to the integrated clamping plate 1112. The first injection core mold and the second injection core mold operate simultaneously in accordance with the lifting and lowering movement of the integrated clamping plate 1112.

[0062] The temperature control unit 1104, blow molding unit 1106, and removal unit 1108 of the manufacturing apparatus 1100 can take the same configuration as the temperature control unit 104, blow molding unit 106, and removal unit 108 of the manufacturing apparatus 100 according to the above embodiment. A detailed explanation is omitted here.

[0063] The manufacturing apparatus 1100 includes a transport means 1110 with an integrally operating transfer plate 1110a and an integrated clamping plate 1112, enabling the molding of preforms and containers with a first preform and a second preform using fewer components, and significantly reducing costs as a manufacturing apparatus with five stations. In the manufacturing apparatus 1100, it is preferable to lower the temperature of the primary preform in the first injection molding section 1102a to the appropriate injection molding temperature in the second injection molding section 1102b.

[0064] Next, the manufacturing apparatus 2100 relating to the second side will be described with reference to Figure 7. The manufacturing apparatus 2100 comprises five molding stations in this order in the circumferential direction: a first injection molding section 2102a, a second injection molding section 2102b, a temperature control section 2104, a blow molding section 2106, and an extraction section 2108. The manufacturing apparatus 2100 also comprises a transport means 2110 which includes a transport plate 2110a configured to be rotatable about a central axis A, and a neck type support section 2110b that supports and guides a neck (lip) type 2110c. The transport plate 2110a is a flat plate-like member with a roughly fan shape (divided rotating plate) resembling a disk divided into five sections, and is provided independently for each molding station. Each station is located at a position that is divided into five equal parts in the circumferential direction about the central axis A of the transport means 2110. The conveying means 2110 is configured to rotate intermittently by 72 degrees at a time, enabling it to sequentially convey the resin molded products held by the neck type 2110c to each station. Five sets of neck types 2110c are provided, corresponding to the five stations. Five sets of neck types 2110c are arranged on the underside of five roughly fan-shaped transfer plates. The conveying means 2110 is configured to allow the resin molded products held by the neck type to be raised and lowered independently at each station. The manufacturing apparatus 2100 has an upper base 2101a that supports the conveying means 2110 and a lower base (machine stand) 2101b located below it. The manufacturing apparatus 2100 further includes a conveying means (lifting means), not shown, for independently raising and lowering the transfer plates 2110a located in the first injection molding section 2102a, the second injection molding section 2102b, and the blow molding section 2106. Therefore, for example, the transport means 2110 can first lower the neck mold in the first injection molding section 2102a, and then lower the neck mold in the second injection molding section 2102b.

[0065] The first injection molding section 2102a is equipped with a first resin injection device 2103a. The first injection molding section 2102a is connected to a first injection molding die (first injection core die, first injection cavity die, neck die). The second injection molding section 2102b is equipped with a second resin injection device 2103b. The second injection molding section 2102b is connected to a second injection molding die (second injection core die, second injection cavity die, neck die). The first injection molding section 2102a and the second injection molding section 2102b can take the same configuration as the first injection molding section 1102a and the second injection molding section 1102b relating to the first side surface described above. A detailed explanation is omitted here. The first injection cavity die and the second injection cavity die are connected to the lower base (machine base) 2101b.

[0066] The first injection molding section 2102a and the second injection molding section 2102b are each provided with a first mold clamping plate 2112a and a second mold clamping plate 2112b, which can operate independently. The first mold clamping plate 2112a and the second mold clamping plate 2112b are each configured to be able to move up and down guided by at least three tie bars 2113. The first injection core mold and the second injection core mold are connected to the first mold clamping plate 2112a and the second mold clamping plate 2112b, respectively. The first injection core mold and the second injection core mold operate independently of each other in accordance with the respective up and down movements of the first mold clamping plate 2112a and the second mold clamping plate 2112b.

[0067] The temperature control unit 2104, blow molding unit 2106, and removal unit 2108 of the manufacturing apparatus 2100 can take the same configuration as the temperature control unit 104, blow molding unit 106, and removal unit 108 of the manufacturing apparatus 100 according to the above embodiment. A detailed explanation is omitted here.

[0068] The manufacturing apparatus 2100 includes a transport means 2110 configured to allow the resin molded product held in the neck mold 2110c to be independently raised and lowered at each station, as well as independent first and second mold clamping plates 2112a and 2112b. This increases the degree of freedom in the mold clamping operation related to the neck mold 2110c and the injection core mold, and increases the degree of freedom in molding the preform and container, which include the first and second preforms. Furthermore, since there is only one temperature control unit, costs can be reduced. In addition, in the manufacturing apparatus 2100, it is preferable to lower the temperature of the primary preform in the first injection molding section 2102a to the appropriate injection molding temperature in the second injection molding section 2102b.

[0069] Next, the manufacturing apparatus 3100 relating to the third side will be described with reference to Figures 8 and 9. The manufacturing apparatus 3100 comprises six stations arranged in this order in the circumferential direction: a first injection molding section 3102a, a first temperature control section 3104a, a second injection molding section 3102b, a second temperature control section 3104b, a blow molding section 3106, and an extraction section 3108. Details of each station are omitted in Figure 9. The manufacturing apparatus 3100 comprises a transport means 3110 which includes a transport plate 3110a configured to be rotatable about a central axis A, and a neck-type support section 3110b that supports and guides a neck (lip) type 3110c. The transport plate 3110a is a single flat plate-like member (rotating plate) with a substantially disc shape. Each station is arranged at a position that is divided into six equal parts in the circumferential direction about the central axis A of the transport means 3110. The conveying means 3110 is configured to rotate intermittently by 60 degrees increments, enabling it to sequentially convey the resin molded products held by the neck type 3110c to each station. The manufacturing apparatus 3100 has an upper base 3101a that supports the conveying means 3110, and a lower base (machine stand) 3101b located below it. The manufacturing apparatus 3100 has at least two (e.g., four) conveying means (lifting means) 3110d, such as hydraulic or pneumatic cylinders, for raising and lowering the upper base 3101a. Six sets of neck types 3110c are provided, corresponding to the number of stations (six). The six sets of neck types 3110c are arranged on the lower surface of the transfer plate 3110a, corresponding to positions that are divided into six equal parts in the circumferential direction around the central axis A of the transfer plate 3110a. The conveying means 3110 is configured to simultaneously raise and lower the resin molded products held by the neck type 3110c at each station. The transport means 3110 is guided up and down by tie bars 3113 on the first injection molding section 3102a and the second injection molding section 3102b side and tie bar 3114 on the blow molding section 3106 side.

[0070] The first injection molding section 3102a includes a first resin injection device 3103a. The first injection molding section 3102a is connected to a first injection molding die (first injection core die, first injection cavity die, neck die). The second injection molding section 3102b includes a second resin injection device 3103b. The second injection molding section 3102b is connected to a second injection molding die (second injection core die, second injection cavity die, neck die). The first injection molding section 3102a and the second injection molding section 3102b further include a first mold clamping plate 3112a and a second mold clamping plate 3112b, which can operate independently of each other. The first mold clamping plate 3112a and the second mold clamping plate 3112b are each provided with at least three tie bars 3113. The first type clamping plate 3112a and the second type clamping plate 3112b can also take the same configuration as the first type clamping plate 2112a and the second type clamping plate 2112b relating to the second side described above. The first type clamping plate 3112a and the second type clamping plate 3112b are provided with a first injection core type movable plate 3112c and a second injection core type movable plate 3112d, respectively, to which the first injection core type and the second injection core type are connected. The first injection core type movable plate 3112c and the second injection core type movable plate 3112d are guided by a first guide rod 3112e and a first guide rod 3112f, respectively, to the first type clamping plate 3112a and the second type clamping plate 3112b, and move up and down independently of each other. The first injection cavity type and the second injection cavity type are connected to the lower base (machine base) 3101b. In the manufacturing apparatus 3100 shown in Figure 9, the first mold clamping plate 3112a and the second mold clamping plate 3112b may be fixed without moving up and down, and the first injection core mold movable plate 3112c and the second injection core mold movable plate 3112d, to which the first injection core mold 3112x and the second injection core mold 3112y are connected, may be configured to move up and down, respectively, by a first injection mold clamping cylinder (first injection mold clamping mechanism) 3112g and a second injection mold clamping cylinder (second injection mold clamping mechanism) 3112h, which are provided above the upper base plate 3101a, to clamp the injection molding die.

[0071] The first temperature control unit 3104a is an intermediate temperature control station located between two injection molding stations (the first injection molding unit 3102a and the second injection molding unit 3102b). The first temperature control unit 3104a comprises a first temperature control cavity mold and a first temperature control core mold (not shown in the figure). A cooling medium, such as water, flows inside the first temperature control cavity mold and the first temperature control core mold. The first temperature control unit 3104a is configured to sandwich the first preform molded in the first injection molding unit 3102a between the first temperature control cavity mold and the first temperature control core mold, thereby adjusting the temperature of the first preform to the appropriate injection molding temperature in the second injection molding unit 3102b. The temperature of the cooling medium flowing inside the first temperature control cavity mold and the first temperature control core mold is set to, for example, approximately 10°C to approximately 65°C. The first temperature control unit 3104a cools and / or heats the first preform to adjust its temperature. The first temperature control unit 3104a is not limited to the above configuration and may be configured in combination patterns such as a heating pot + heating core, an upper heating pot + lower temperature control pot + temperature control core, and other configurations are also possible.

[0072] The second temperature control unit 3104b, blow molding unit 3106, and removal unit 3108 of the manufacturing apparatus 3100 can take the same configuration as the temperature control unit 104, blow molding unit 106, and removal unit 108 of the manufacturing apparatus 100 according to the above embodiment. A detailed explanation is omitted here.

[0073] The manufacturing apparatus 3100 includes a transport means 3110 with an integrally operating transfer plate 3110a, and independent first and second mold clamping plates 3112a and 3112b. Compared to the case where a mechanism (transport means) is used to allow the neck mold 3110c to be raised and lowered independently, costs can be reduced, and the degree of freedom in the mold clamping operation related to the injection core mold can be increased, thereby increasing the degree of freedom in molding the preform and container, which include the first and second preforms. Furthermore, by including a first temperature control unit 3104a, which is an intermediate temperature control station, the temperature of the first preform can be appropriately controlled even if the mold clamping operation is simplified.

[0074] Furthermore, by equipping the manufacturing apparatus 3100 with a first temperature control unit 3104a, the primary preform molded in the first injection molding unit 3102a can be released from the mold in a short time, and the high-temperature primary preform can be cooled in the first temperature control unit 3104a. In this case, the cooling time of the primary preform in the first injection molding unit 3102a can be significantly reduced, and manufacturing efficiency can be greatly improved. In addition, when forming a release container, a lubricant can be applied to the primary preform in the first temperature control unit 3104a, increasing the degree of freedom in molding. Surface coloring (surface decoration) also becomes possible.

[0075] Here, a modified example of the mold clamping mechanism for the injection molding die in the manufacturing apparatus 3100 relating to the third side will be described with reference to Figures 10 and 11. Figure 10 is a plan view of the manufacturing apparatus 3100A relating to the modified example of the third side, and Figure 11 is a side view of the manufacturing apparatus 3100A relating to the modified example of the third side. The manufacturing apparatus 3100A shown in Figures 10 and 11 is the same as the manufacturing apparatus 3100 relating to the third side described above, except for the mold clamping mechanism in the injection molding die, so the same reference numerals are used for similar components and their explanation is omitted.

[0076] In the manufacturing apparatus 3100A, the first injection molding section 3102a and the second injection molding section 3102b are each equipped with a first mold clamping plate 3112aA and a second mold clamping plate 3112bA that can operate independently. The first mold clamping plate 3112aA and the second mold clamping plate 3112bA are not provided with members corresponding to the first injection core mold movable plate 3112c and the second injection core mold movable plate 3112d in the third side of the manufacturing apparatus 3100. The first mold clamping plate 3112aA and the second mold clamping plate 3112bA are connected to the first injection core mold 3112x and the second injection core mold 3112y, respectively. In the manufacturing apparatus 3100A, the first mold clamping plate 3112a and the second mold clamping plate 3112b may be configured to move up and down to clamp the injection molding die, for example, by a first injection clamping cylinder (first injection clamping mechanism) 3112gA and a second injection clamping cylinder (second injection clamping mechanism) 3112hA, which are located below the lower base (machine base) 3101b. The first mold clamping plate 3112aA and the second mold clamping plate 3112bA are connected via tie bars 3113 to the first traction plate 3112gB and the second traction plate 3112hB located below the lower base (machine base) 3101b. The first injection-type clamping cylinder 3112gA and the second injection-type clamping cylinder 3112hA are fixed to the first traction plate 3112gB and the second traction plate 3112hB, and the rods of the first injection-type clamping cylinder 3112gA and the second injection-type clamping cylinder 3112hA are connected to the lower surface of the lower base (machine base) 3101b. Alternatively, the first injection-type clamping cylinder 3112gA and the second injection-type clamping cylinder 3112hA may be fixed to the lower surface of the lower base (machine base) 3101b, and the rods of the first injection-type clamping cylinder 3112gA and the second injection-type clamping cylinder 3112hA may be connected to the upper surfaces of the first traction plate 3112gB and the second traction plate 3112hB.

[0077] Although the first side, second side, third side, and manufacturing apparatuses 1100, 2100, 3100, and 3100A relating to the third side have been described, when manufacturing a two-layer preform or container with the said manufacturing apparatus, the inner layer may be the primary preform and the outer layer the secondary preform, or the outer layer may be the primary preform and the inner layer the secondary preform. In the configuration where the outer layer is the primary preform and the inner layer the secondary preform, the outer layer injection mold 50 and inner layer injection mold 70 described in the above embodiment can be used.

[0078] Furthermore, the present invention is not limited to the embodiments described above, and can be freely modified and improved as appropriate. In addition, the material, shape, dimensions, numerical values, form, number, and placement of each component in the embodiments described above are arbitrary and not limited as long as they can achieve the present invention.

[0079] This application is based on Japanese patent applications filed on 26 September 2019 (JP 2019-175844) and on 21 February 2020 (JP 2020-028040), which are incorporated herein by reference in their entirety. All references incorporated herein are incorporated as a whole. [Explanation of Symbols]

[0080] 10: Preform, 12: Opening, 14: Neck, 16: Body, 18: Bottom, 22: Inner layer, 24: Outer layer, 26a: Recess, 26: Air inlet, 27: Filling port (opening), 28: Part, 30: Release container, 36: Body, 38: Bottom, 42: Inner layer, 44: Outer layer, 50: Outer layer injection mold (example of first injection mold), 52: Outer layer cavity mold (example of first injection cavity mold), 53: Hole forming protrusion (example of first projection), 54: Outer layer core mold (example of first injection core mold), 56: Neck mold, 5 8: Outer layer gate, 59: Hot runner mold, 59a: Valve pin, 60: Outer layer preform, 61: Thin film section, 70: Inner layer injection mold (example of second injection mold), 72: Inner layer cavity mold (example of second injection cavity mold), 73: Fitting protrusion (example of second projection), 74: Inner layer core mold, 78: Inner layer gate, 79: Hot runner mold, 80: Inner layer preform, 100: Manufacturing equipment, 102: Injection molding section, 104: Temperature control section, 106: Blow molding section, 108: Take-out section, 110: Conveying means

Claims

1. An injection molding process for injection molding a two-layer preform having an outer layer and an inner layer, A blow molding process is performed to blow-molde the aforementioned preform to form a two-layer container made of resin, A method for manufacturing a double-layered container having the following characteristics: The injection molding process described above is: An outer layer molding process in which a resin material for the outer layer is filled into a first injection mold to form the outer layer, and a thin film portion is formed on a part of the outer layer, A thin film rupture step is performed to rupture the thin film portion formed in the outer layer molding step, An inner layer molding step is performed in which, from the outside of the thin film portion fractured in the thin film portion fracture step, an inner layer resin material having a temperature lower than the melting point of the outer layer resin material is filled into a second injection mold to form the inner layer, It has, In the outer layer molding process, after the surface temperature of the outer layer is reduced to below the melting point of the inner layer resin material, the process proceeds to the inner layer molding process. The aforementioned first injection mold comprises a first injection cavity mold and a first injection core mold. The thin film portion is formed at the bottom of the outer layer of the preform, In the aforementioned outer layer molding process, After filling the first injection cavity mold with the outer layer resin material, the valve pin of the hot runner mold that supplies the outer layer resin material to the first injection cavity mold is moved toward the first injection core mold, causing the tip of the valve pin to protrude beyond the tip of the hot runner mold. By cooling a portion of the outer layer for a predetermined time in a recessed state by the amount that the tip of the valve pin protrudes beyond the tip of the hot runner mold, the thin film portion is formed. A method for manufacturing a double-layered container.

2. The inner layer resin material is injected toward the thin film portion to break the thin film portion, and the inner layer resin material is filled into a second injection mold through the broken thin film portion to form the inner layer. A method for manufacturing a double-layered container according to claim 1.

3. A first temperature adjustment step for adjusting the temperature of the outer layer molded in the outer layer molding step, A second temperature adjustment step for adjusting the temperature of the inner layer formed in the aforementioned inner layer molding step, A method for manufacturing a double-layered container according to claim 1, comprising having the characteristics described above.

4. The first injection cavity mold has a first projection, In the outer layer molding process, the first projection forms a recess in the outer layer for an air introduction hole to separate the outer layer and the inner layer of the two-layer container. A method for manufacturing a double-layered container according to claim 1.

5. The second injection mold has a second injection cavity mold having a second projection, In the inner layer molding process, the inner layer resin material is filled into the second injection cavity mold with the second projection fitted into the recess for the air introduction hole. A method for manufacturing a double-layered container according to claim 4.

6. A method for manufacturing a two-layer preform having an outer layer and an inner layer by injection molding, An outer layer molding process in which a resin material for the outer layer is filled into a first injection mold to form the outer layer, and a thin film portion is formed on a part of the outer layer, A thin film rupture step is performed to rupture the thin film portion formed in the outer layer molding step, An inner layer molding step is performed by filling a second injection mold with an inner layer resin material having a temperature lower than the melting point of the outer layer resin material to form the inner layer. It has, In the outer layer molding process, after the surface temperature of the outer layer is reduced to below the melting point of the inner layer resin material, the process proceeds to the inner layer molding process. The aforementioned first injection mold comprises a first injection cavity mold and a first injection core mold. The thin film portion is formed at the bottom of the outer layer of the preform, In the aforementioned outer layer molding process, After filling the first injection cavity mold with the outer layer resin material, the valve pin of the hot runner mold that supplies the outer layer resin material to the first injection cavity mold is moved toward the first injection core mold, causing the tip of the valve pin to protrude beyond the tip of the hot runner mold. By cooling a portion of the outer layer for a predetermined time in a recessed state by the amount that the tip of the valve pin protrudes beyond the tip of the hot runner mold, the thin film portion is formed. A method for manufacturing preforms.

7. An injection molding unit for injection molding a two-layer preform having an outer layer and an inner layer, A manufacturing apparatus for a double-layer container, comprising: a blow molding section for blow molding the aforementioned preform to form a double-layer container made of resin, The injection molding section is, A first injection mold is used to form an outer layer resin material supplied from a hot runner mold into the outer layer, and to form a thin film portion in a part of the outer layer by recessing a part of the outer layer by the amount that the tip of the valve pin of the hot runner mold protrudes beyond the tip of the hot runner mold, and A second injection mold for molding the inner layer resin material into the inner layer, It has, The first injection mold is equipped with a breaking means for breaking the thin film portion formed therein, The first injection mold is equipped with a cooling mechanism that cools the surface temperature of the outer layer to below the melting point of the inner layer resin material. A manufacturing apparatus for double-layered containers.

8. A first temperature control unit adjusts the temperature of the outer layer molded in the first injection mold, A second temperature control unit for adjusting the temperature of the inner layer molded in the second injection mold, A manufacturing apparatus for a double-layered container according to claim 7.

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