Mold unit and blow molding apparatus

Abstract

To provide a die unit applied in a manufacturing method in which a preform is molded by performing multiple steps of injection molding in the order of an outer layer and an inner layer, and a resin container is manufactured by applying a hot parison-type blow molding method.SOLUTION: There is provided a die unit that is applied to a hot parison-type resin container manufacturing method and that accommodates a bottomed resin preform having retained heat released from an injection molding die to cool the preform, comprising: a core die having an outer shape corresponding to an inner shape of the preform and capable of being inserted into the preform; a cavity die for accommodating the preform and adjusting a temperature of the preform; and a movable member facing a bottom of the preform. The die unit has a perforation portion in either the core die or the movable member that forms an opening through the bottom of the preform.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a mold unit and a blow molding apparatus applied to the manufacture of resin containers.

Background Art

[0002] Conventionally, resin containers have been applied to various uses, and resin containers having a plurality of resin layers have also been put into practical use in various ways. For example, a resin peeling container having a two-layer structure of an inner layer and an outer layer, in which the inner layer peels off from the outer layer in response to the discharge of the contents, is known. This type of peeling container is also referred to as a delaminated bottle or an airless bottle, and is used, for example, as a container for liquid seasonings such as soy sauce, liquid cosmetics, liquid detergents such as shampoo and hand soap, and liquid medicines used for disinfection and sterilization. Currently, in the manufacture of this type of peeling container, the extrusion blow method is generally used, and the stretch blow method is rarely used (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, from the viewpoints of improving the appearance, dimensional accuracy, physical strength, etc. of the peeling container and reducing the environmental load by suppressing waste materials, in the manufacture of the peeling container, it has been considered to apply a one-stage hot parison blow molding method in which the injection molding process to the blow molding process is continuously performed.

[0005] However, when the release container is designed to meet all requirements in terms of functional aspects such as moisture barrier properties and gas barrier properties, physical properties such as buckling resistance (load resistance) and impact resistance (drop strength), and appearance design, the melting point of the resin material for the outer layer may be set higher than the melting point of the resin material for the inner layer. In the injection molding process of forming a two-layer preform, when the resin material for the outer layer at a high temperature is filled after forming the inner layer, the surface of the inner layer in contact with the resin material for the outer layer melts and undergoes thermal deformation. For this reason, it is extremely difficult to manufacture the release container itself by applying the hot parison blow molding method.

[0006] Therefore, the present invention has been made in view of such problems, and an object thereof is to provide a mold unit applicable to a manufacturing method of manufacturing a resin container by performing multi-stage injection molding in the order of the outer layer and the inner layer to form a preform and applying the hot parison blow molding method.

Means for Solving the Problems

[0007] A mold unit according to an aspect of the present invention is applied to a method for manufacturing a resin container of the hot parison type, and is a mold unit that accommodates a bottomed resin preform having retained heat released from an injection mold and cools the preform. The mold unit has an outer shape corresponding to the internal shape of the preform, a core mold that can be inserted into the inside of the preform, a cavity mold that accommodates the preform and adjusts the temperature of the preform, and a movable member facing the bottom of the preform. The mold unit has a perforated portion that forms an opening penetrating the bottom of the preform in either the core mold or the movable member.

Effects of the Invention

[0008] According to an aspect of the present invention, there is provided a mold unit applicable to a manufacturing method of manufacturing a resin container by performing multi-stage injection molding in the order of the outer layer and the inner layer to form a preform and applying the hot parison blow molding method.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, as an example of manufacturing a container by a hot parison blow molding method using a preform with a multilayer structure, the case of manufacturing a peelable container will be described.

[0011] In the embodiments, for easier understanding, structures and elements other than the main part of the present invention will be described in a simplified or omitted manner. Also, in the drawings, the same reference numerals are given to the same elements. Note that the shapes, dimensions, etc. of the respective elements shown in the drawings are schematically shown and do not indicate actual shapes, dimensions, etc.

[0012] <Configuration Example of Preform> First, with reference to FIG. 1, a configuration example of a preform for a peeling container according to this embodiment will be described. FIG. 1 is a longitudinal sectional view of the preform 10 of this embodiment. The overall shape of the preform 10 is a bottomed cylindrical shape with one end open and the other end closed. The preform 10 includes a cylindrical body portion 14, a bottom portion 15 that closes the other end side of the body portion 14, and a neck portion 13 formed at the opening on one end side of the body portion 14.

[0013] The preform 10 has a two-layer structure in which a second layer (inner layer) 12 is laminated inside a first layer (outer layer) 11. The first layer 11 and the second layer 12 are formed of different thermoplastic resin materials by two-stage injection molding as described later. The first layer 11 is composed of a synthetic resin having excellent moldability and transparency and capable of imparting buckling resistance and impact resistance required for the container. On the other hand, the second layer 12 is composed of a synthetic resin having properties (for example, moisture barrier property, gas barrier property, heat resistance, chemical resistance) that contribute to the stable storage of the contents of the container and the suppression of deterioration (oxidation) of the contents. Also, a resin material for the first layer 11 having a higher melting point than the resin material for the second layer 12 is selected. Note that the first layer 11 may also have properties that contribute to the stable storage of the contents and the suppression of deterioration of the contents. Furthermore, the first layer 11 and the second layer 12 may each have different properties. For example, the first layer 11 may be formed of a material having a moisture barrier property, and the second layer 12 may be formed of a material having a gas barrier property. Furthermore, the first layer 11 and the second layer 12 may be composed of the same type of synthetic resin (the melting points of the resin materials of the first layer 11 and the second layer 12 may be the same). In this case, it is preferable to contain an additive that contributes to the stable storage of the contents and the suppression of deterioration (oxidation) of the contents in at least one of the first layer 11 and the second layer 12.

[0014] Hereinafter, the resin material of the first layer 11 will also be referred to as the first resin material, and the resin material of the second layer 12 will also be referred to as the second resin material. The combination of the first resin material and the second resin material can be appropriately selected according to the specifications of the peeling container. Specific types of materials include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (policyclohexane dimethylene terephthalate), Tritan (registered trademark: copolyester manufactured by Eastman Chemical Company), 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 the like.

[0015] As an example, the first resin material is PET (polyethylene terephthalate), and the second resin material is PP (polypropylene). The melting point of PP is about 160 - 170°C, and the melting point of PET is higher than that of PP, about 245 - 260°C.

[0016] Also, in the body portion 14 of the preform 10, the ratio (t1 / t2) of the thickness t1 of the first layer 11 to the thickness t2 of the second layer 12 is preferably 1.5 or more. From the viewpoint of ensuring the transparency of the formed peeling container, the ratio of the thickness is preferably 3.0 or less.

[0017] Also, in the bottom portion 15 of the preform 10, an opening 16 is formed through the center of the bottom of the first layer 11 and penetrates the first layer 11. The opening 16 of the first layer 11 is blocked from the inside by the second layer 12. Also, in the preform 10, an exposed portion made of the second layer 12 is formed outside the opening 16. The diameter of the exposed portion is formed larger than the diameter of the opening 16.

[0018] Further, a recess 17 for forming an air introduction hole in the peeling container is formed at the bottom 15 of the preform 10. The recess 17 is, for example, circular in shape and is formed at least at one location at a radial interval from the center of the bottom 15 of the preform 10. However, a plurality of recesses 17 may be formed along the circumferential direction. The depth of the recess 17 in the thickness direction of the container is set to a dimension such that at least the recess 17 penetrates the first layer 11 and the surface of the second layer 12 is exposed within the recess 17.

[0019] <Configuration Example of Peeling Container> Next, with reference to FIG. 2, a configuration example of the resin peeling container 20 according to the present embodiment will be described. FIG. 2 is a longitudinal sectional view of the peeling container 20 of the present embodiment.

[0020] The peeling container 20 is a resin container in a bottle shape obtained by stretch blow molding the preform 10, and contains, for example, a seasoning liquid such as soy sauce. Note that the use of the peeling container 20 may be to contain other contents such as a cosmetic lotion, shampoo (liquid detergent), or a disinfectant / sanitizing liquid (drug).

[0021] Similar to the preform 10, the peeling container 20 has a two-layer structure in which the second layer 12 is laminated inside the first layer 11. In the body portion 22 of the peeling container 20, the ratio (t11 / t12) of the thickness t11 of the first layer 11 to the thickness t12 of the second layer 12 is substantially the same as the ratio (t1 / t2) of the thicknesses in the body portion 14 of the preform 10.

[0022] The peeling container 20 has a neck portion 21 having an opening at the upper end, a cylindrical body portion 22 continuous from the neck portion 21, and a bottom portion 23 continuous from the body portion 22. In the manufacture of the peeling container 20, the body portion 14 and the bottom portion 15 of the preform 10 are inflated by stretch blow molding, thereby shaping the body portion 22 and the bottom portion 23 of the peeling container 20. Further, during stretch blow molding, the recess 17 of the preform 10 is stretched, so that an air introduction hole 24 penetrating the first layer 11 is formed in the bottom portion 23 of the peeling container 20. Note that a plug body (not shown) is engaged with the neck portion 21 in an airtight state. The plug body is provided with a push-type pump mechanism or a discharge mechanism that blocks / suppresses the inflow of outside air. By engaging the plug body with the neck portion 21, the inflow of outside air from the neck portion 21 into the body portion 22 can be suppressed, and the deterioration (oxidation) of the content can be suppressed except when the content is discharged. Further, the plug body prevents outside air from flowing into the space between the first layer 11 and the second layer 12 from the neck portion 21.

[0023] In the peeling container 20, the content is filled in the space inside the second layer 12. In the peeling container 20, when the content is discharged from the second layer 12, air gradually flows into the space between the first layer 11 and the second layer 12 through the air introduction hole 24, and the first layer 11 and the second layer 12 are peeled off. As a result, the volume occupied by the content in the container can be replaced with air without allowing the content in the second layer 12 to come into contact with air, and the content filled in the second layer 12 can be discharged outside the container. Further, in the peeling container 20, the volume of the second layer 12 automatically decreases as the content is consumed, and when the content decreases, the content can be concentrated on the side of the pump mechanism or the discharge mechanism of the plug body. Therefore, in the peeling container 20, the remaining amount of the content that cannot be discharged can be minimized.

[0024] Also, at the center of the bottom 23 of the peeling container 20, an opening 25 (non-laminated portion 25, single-layer portion 25) that penetrates the first layer 11 is formed in the same manner as the preform 10. The opening 25 is filled with the material of the second layer 12 so as to block the opening 25, and in the vicinity of the opening 25 at the bottom 23 of the peeling container 20, the second layer 12 is exposed outside the first layer 11. The exposed portion (bulging portion) of the second layer 12 protrudes outward in the radial direction and is formed larger than the diameter of the opening 25. The exposed portion of the peeling container 20 is formed by extending the exposed portion of the preform 10. At the opening 25 of the peeling container 20, the second layer 12 is exposed outside the first layer 11, so that the second layer 12 is partially fixed (locked) to the first layer 11, and the displacement of the second layer 12 with respect to the first layer 11 is suppressed.

[0025] <Description of the manufacturing apparatus for the peeling container> FIG. 3 is a diagram schematically showing the configuration of the blow molding apparatus of the present embodiment. The blow molding apparatus 30 of the present embodiment is an example of a container manufacturing apparatus, and employs a hot parison method (also referred to as a one-stage method or a one-step method) in which the peeling container 20 is blow molded by utilizing the retained heat (internal heat quantity) at the time of injection molding without cooling the preform 10 to room temperature.

[0026] The blow molding apparatus 30 includes a first injection molding section 31, a first temperature adjustment section 32, a second injection molding section 33, a second temperature adjustment section 34, a blow molding section 35, a take-out section 36, and a transfer mechanism 37. The first injection molding section 31, the first temperature adjustment section 32, the second injection molding section 33, the second temperature adjustment section 34, the blow molding section 35, and the take-out section 36 are arranged at positions rotated by a predetermined angle (for example, 60 degrees) around the transfer mechanism 37.

[0027] (Transfer mechanism 37) The transfer mechanism 37 includes a rotating plate (transfer plate) 37a that rotates about an axis perpendicular to the plane of FIG. 3. One or more neck types 37b (not shown in FIG. 3) for holding the neck portion 13 of the preform 10 (or the neck portion 21 of the peeling container 20) are arranged at predetermined angles on the rotating plate 37a. By rotating the rotating plate 37a, the transfer mechanism 37 transfers the preform 10 (or the peeling container 20) held by the neck type 37b in the order of the first injection molding section 31, the first temperature adjustment section 32, the second injection molding section 33, the second temperature adjustment section 34, the blow molding section 35, and the take-out section 36. Note that the transfer mechanism 37 can also raise and lower the rotating plate 37a and perform operations related to mold closing and mold opening (ejection) in the first injection molding section 31 and the second injection molding section 33.

[0028] (First injection molding section 31) The first injection molding section 31 includes a cavity mold 40, a core mold 41, and a hot runner mold 42, and manufactures the first layer 11 of the preform 10 in cooperation with the neck type 37b conveyed during molding. The cavity mold 40 is composed of a first cavity mold 40A on the opening side (upper side) and a second cavity mold 40B on the bottom side (lower side). As shown in FIG. 3, a first injection device 38 for supplying a first resin material to the hot runner mold 42 is connected to the first injection molding section 31. The cavity mold 40 and the hot runner mold 42 are fixed to the machine base of the blow molding device 30 in an integrated state. The core mold 41 is fixed to a core mold lifting mechanism.

[0029] The cavity mold 40 defines the shape of the outer periphery of the first layer 11. The first cavity mold 40A is a mold facing the opening side of the cavity mold 40 and defines the shape of the outer periphery of the body portion of the first layer 11. The second cavity mold 40B is a mold facing the bottom side of the cavity mold 40 and defines the shape of the outer periphery of the bottom portion of the first layer 11. Further, the hot runner mold 42 has a resin supply portion 42a for introducing the first resin material from the first injection device 38. The core mold 41 is a mold that defines the shape of the inner peripheral side of the first layer 11 and is inserted into the inner peripheral side of the cavity mold 40 from above. The neck mold 37b defines the outer shape of the neck portion 13 of the preform 10 (the first layer 11). In FIG. 4, an example is shown in which the cavity mold 40 is divided into the first cavity mold 40A and the second cavity mold 40B, but the cavity mold 40 may be integrally configured without being divided.

[0030] Further, the hot runner mold 42 of the cavity mold 40 may have a valve pin (a rod-shaped member that opens and closes the resin supply portion 42a) that is axially movable to a position close to the core mold 41 inside. The valve pin of the hot runner mold 42 is, for example, housed inside the hot runner mold 42 until the first resin material fills the mold cavity, and after the first resin material fills the mold cavity, it protrudes to a position closer to the core mold 41 than the bottom surface of the second cavity mold 40B.

[0031] As shown in FIG. 4, in the first injection molding section 31, the above-described cavity mold 40, core mold 41, and the neck mold 37b of the transfer mechanism 37 are closed to form the mold cavity for the first layer 11. Then, by pouring the first resin material through the hot runner mold 42 from the bottom of the above-described mold cavity, the first layer 11 of the preform 10 is manufactured in the first injection molding section 31. When the hot runner mold 42 has the above-described valve pin, after pouring the first resin material into the mold cavity of the first layer 11, the valve pin may be raised and moved to a position protruding from the bottom surface of the second cavity mold 40B and close to the core mold 41. Thereby, since the center of the bottom portion of the first layer 11 can be formed into a thin film shape with a thickness thinner than the peripheral portion, the formation of the opening 16 in the first temperature adjustment section 32 described later can be performed more reliably.

[0032] On the upper surface side of the second cavity mold 40B facing the bottom outer periphery of the first layer 11, a first protrusion 44 is provided at a predetermined position. For example, the first protrusion 44 has a cylindrical shape, a conical shape (tapered cylindrical shape), a prismatic shape, or a pyramidal shape, and at least one is arranged at a radial interval from the center of the bottom where the resin supply part 42a is located. The shape of the first protrusion 44 may be other shapes such as a rib shape extending in the axial direction, and a plurality of them may be formed to be rotationally symmetric with respect to the center of the bottom. Also, the number of the first protrusions 44 may be plural. In that case, each of the first protrusions 44 may be arranged in a point-symmetric positional relationship with respect to the central axis.

[0033] As shown in FIG. 4, the protruding amount h1 of the first protrusion 44 from the bottom outer peripheral surface of the first layer 11 (or the cavity reference surface of the second cavity mold 40B) is approximately the same dimension as the thickness of the first layer 11. Therefore, when the first injection molding part 31 is closed, the tip of the first protrusion 44 faces the surface of the core mold 41 (that is, the tip of the first protrusion 44 is arranged near the surface of the core mold 41). Thereby, in the injection molding of the first injection molding part 31, a concave part 11a such as a circle is formed in the first layer 11 at a position corresponding to the concave part 17 of the preform 10 by the first protrusion 44. The concave part 11a of the first layer 11 may penetrate the first layer 11 or may have a thin film formed between the core mold 41 and the first protrusion 44.

[0034] Also, when the first injection molding part 31 is opened, the neck mold 37b of the transfer mechanism 37 is not opened and holds and transfers the first layer 11 of the preform 10 as it is. The number of preforms 10 simultaneously molded by the first injection molding part 31 (that is, the number of peeling containers 20 that can be simultaneously molded by the blow molding device 30) can be set as appropriate. In FIG. 3, a configuration for simultaneously transferring four preforms is shown.

[0035] (First Temperature Adjusting Part 32) The first temperature adjustment unit 32 includes either the mold unit 50a of the first example or the mold unit 50b of the second example described later. The first temperature adjustment unit 32 adjusts the temperature (the first layer 11 is heated or cooled) by accommodating the first layer 11 of the preform 10 having retained heat after injection molding (in a high-temperature state) in the mold units 50a and 50b maintained at a predetermined temperature. Further, the first temperature adjustment unit 32 also has the function of adjusting the temperature distribution of the first layer 11 of the preform 10 to a predetermined state before being transported to the second injection molding unit 33. Furthermore, when the first temperature adjustment unit 32 accommodates the first layer 11 of the preform 10 in the mold units 50a and 50b, an opening 16 is formed at the center of the bottom of the first layer 11.

[0036] FIG. 5 is a view showing the mold unit 50a of the first example of the first temperature adjustment unit 32. The mold unit 50a of the first example includes a cavity mold (pot mold) 51, a core mold 52a, and a movable mold 53a.

[0037] The cavity mold 51 is a mold having a temperature control space capable of accommodating the first layer 11 of the preform 10 manufactured in the first injection molding unit 31. The cavity mold 51 has a configuration divided into three upper and lower stages along the axial direction of the preform 10, and in order from the top, it has an upper stage mold 51a, a middle stage mold 51b, and a lower stage mold 51c. The lower stage mold 51c of the cavity mold 51 is placed on a support base 56. Also, a space for inserting the movable mold 53a is formed along the axial direction at the center of the bottom of the lower stage mold 51c facing the bottom 15 of the preform 10 and the support base 56.

[0038] Each of the upper-stage type 51a, the middle-stage type 51b, and the lower-stage type 51c is provided with a heater or has a flow path (not shown) through which a temperature adjustment medium (cooling medium) flows inside. Therefore, the temperature of the cavity type 51 is maintained at a predetermined temperature by the heater or the temperature adjustment medium. Note that the temperature distribution of the preform 10 may be changed in the axial direction by changing the temperatures of the heaters and the temperature adjustment media of the upper-stage type 51a, the middle-stage type 51b, and the lower-stage type 51c. The cavity type provided with a heater heats the preform 10 in a non-contact manner, and the cavity type provided with a flow path for the temperature adjustment medium performs temperature adjustment or cooling in contact with the preform 10.

[0039] The core mold 52a is a mold that is movable in the axial direction with respect to the cavity mold 51 and is inserted inside the first layer 11 accommodated in the cavity mold 51. Inside the core mold 52a, a flow path (a temperature adjustment member or a cooling member (not shown)) through which a temperature adjustment medium (cooling medium) flows is formed or incorporated, and the core mold 52a is maintained at a predetermined temperature by the above temperature adjustment medium. Further, the shape of the core mold 52a is formed in a shape corresponding to the inner peripheral surface of the first layer 11. Therefore, when the core mold 52a is inserted into the first layer 11, the inner peripheral surface of the first layer is in surface contact with the surface of the core mold 52a, and efficient heat exchange is performed between the two.

[0040] Also, at the center of the tip of the core mold 52a facing the bottom 15 of the first layer 11, a conical punching portion (punching needle) 54 that protrudes axially downward is provided. The punching portion 54 penetrates the bottom of the first layer 11 when the core mold 52a is inserted into the first layer 11 and functions to form an opening 16 at the center of the bottom of the first layer 11.

[0041] The movable mold 53a is a mold that faces the center of the bottom of the first layer 11 from below and is inserted into the lower-stage type 51c and the support base 56 so as to be able to move up and down. On the surface of the movable mold 53a, a concave portion 55a corresponding to the shape of the punching portion 54 of the core mold 52a and receiving the punching portion 54 at the time of mold closing is formed.

[0042] Next, while referring to FIG. 6, the configuration of the mold unit 50b of the second example will be described. In the description of the mold unit 50b of the second example, the same components as those of the mold unit 50a of the first example are denoted by the same reference numerals, and redundant description will be omitted.

[0043] The mold unit 50b of the second example includes a cavity mold (pot mold) 51, a core mold 52b, and a movable mold 53b.

[0044] The core mold 52b of the mold unit 50b of the second example is a mold that is axially movable with respect to the cavity mold 51 and is inserted inside the first layer 11 accommodated in the cavity mold 51. Inside the core mold 52b, a flow path (not shown) through which a temperature adjustment medium (cooling medium) flows is formed or incorporated, and the core mold 52b is maintained at a predetermined temperature by the above temperature adjustment medium. Further, the shape of the core mold 52b is formed in a shape corresponding to the inner peripheral surface of the first layer 11. Therefore, when the core mold 52b is inserted into the first layer 11, the inner peripheral surface of the first layer is in surface contact with the surface of the core mold 52b, and efficient heat exchange is performed between the two. Also, at the center of the tip of the core mold 52b facing the bottom 15 of the first layer 11, a concave portion 55b corresponding to the shape of a punching portion 54b (punching needle) provided in the movable mold 53b described later and receiving the punching portion 54b at the time of mold closing is formed.

[0045] The movable mold 53b is a mold facing the center of the bottom of the first layer 11 from below and is inserted into the lower mold 51c and the support base 56 so as to be movable up and down. The movable mold 53b is provided with a conical punching portion 54b (punching needle) protruding axially upward. The punching portion 54b functions to penetrate the bottom 15 of the first layer 11 in a state where the core mold 52b is inserted when the movable mold 53b rises and the mold is closed, and to form an opening 16 at the center of the bottom of the first layer 11.

[0046] Also, the mold units 50a and 50b shown in FIGS. 5 and 6 heat the first layer 11 from the outside with radiant heat from the cavity mold 51 and cool the first layer 11 from the inside by bringing the core molds 52a and 52b through which the temperature adjustment medium flows into contact.

[0047] In the second injection molding section 33, as will be described later, the outer side of the first layer 11 is cooled by contact with the cavity mold 60, and the temperature decreases. Therefore, in order to suppress the preform 10 from being difficult to expand during blow molding, it is preferable that the first temperature adjustment section 32 heats the first layer 11 from the outside to secure the retained heat.

[0048] Also, in the second injection molding section 33, as will be described later, the inner side of the first layer 11 is heated by the second resin material, so the first layer 11 is likely to turn white. Therefore, it is preferable that the first temperature adjustment section 32 cools the first layer 11 from the inside to suppress clouding (crystallization) of the first layer 11.

[0049] (Second injection molding section 33) As shown in FIG. 7, the second injection molding section 33 includes a cavity mold 60, a core mold 61, and a hot runner mold 62. It cooperates with the neck mold 37b conveyed during molding and injection molds the second layer 12 on the inner peripheral portion of the first layer 11. The cavity mold 60 is composed of a first cavity mold 60A on the opening side (upper side) and a second cavity mold 60B on the bottom side (lower side). Also, as shown in FIG. 3, a second injection device 39 for supplying the second resin material to the hot runner mold 62 is connected to the second injection molding section 33.

[0050] The cavity mold 60 is a mold that houses the first layer 11. The first cavity mold 60A is a mold facing the opening side of the cavity mold 60 and houses the body portion 14 of the first layer 11. The second cavity mold 60B is a mold facing the bottom side of the cavity mold 60 and houses the bottom portion 15 of the first layer 11. Also, the hot runner mold 62 has a resin supply portion 62a for introducing the second resin material from the second injection device 39. The core mold 61 is a mold that defines the shape of the inner peripheral side of the second layer 12 and is inserted into the inner peripheral side of the cavity mold 60 from above. The neck mold 37b defines the upper shape of the neck portion 13 of the preform 10 (second layer 12). Note that the cavity mold 60 may be integrally configured without the first cavity mold 60A and the second cavity mold 60B being divided.

[0051] As shown in FIG. 7, the second injection molding section 33 houses the first layer 11 of the preform 10 injection molded by the first injection molding section 31. In a state where the second injection molding section 33 is closed, a mold space is formed between the inner peripheral side of the first layer 11 and the surface of the core mold 61. In the second injection molding section 33, by pouring the second resin material through the hot runner mold 62 from the bottom of the above mold space, a preform 10 is formed in which the second layer 12 is laminated on the inner peripheral side of the first layer 11.

[0052] Also, on the upper surface side of the second cavity mold 60B facing the outer periphery of the bottom of the first layer 11, at a predetermined position corresponding to the first protrusion 44 of the first injection molding section 31, a second protrusion 64 having a columnar shape or the like corresponding to the shape of the recess 17 of the preform 10 is provided. When the first layer 11 is housed in the second injection molding section 33, the second protrusion 64 is inserted into the recess 11a of the first layer 11.

[0053] As shown in FIG. 7, the protruding amount h2 of the second protrusion 64 from the outer peripheral surface of the bottom of the first layer 11 (or the cavity reference surface of the second cavity mold 60B) is a dimension larger than the thickness of the first layer 11. That is, the protruding amount h2 of the second protrusion 64 is larger than the protruding amount h1 of the first protrusion 44 (h2>h1). Therefore, when the second injection molding section 33 is closed, the tip of the second protrusion 64 penetrates the recess 11a of the first layer 11 and protrudes to the inner peripheral side of the first layer 11. By providing the second protrusion 64 in the second cavity mold 60B of the second injection molding section 33, a recess 17 can be formed in the bottom 15 of the preform 10.

[0054] Also, the protruding amount h2 of the second protrusion 64 is set to be smaller than the thickness of the preform 10. That is, in the injection molding in the second injection molding section 33, since the second resin material flows between the core mold 61 and the second protrusion 64, a hole penetrating the second layer 12 is not formed by the second protrusion 64.

[0055] In the second injection molding section 33, the axial depth of the cavity space of the cavity mold 60 that houses the first layer 11 may be shorter than the axial length of the first layer 11. As a result, when the first layer 11 is housed in the cavity mold 60, the bottom of the first layer 11 is pressed against the bottom surface of the cavity mold 60 and the two come into contact, suppressing the formation of a gap between the bottom of the first layer 11 and the cavity mold 60. Further, a concave-shaped molding space may be provided in the central region of the bottom of the second cavity mold 60B so that the second layer 12 can be exposed from the opening 16 of the first layer 11, and a slight gap may be formed between the first layer 11 and the second cavity mold 60B in the central region of the bottom.

[0056] (Second temperature adjustment section 34) The second temperature adjustment section 34 equalizes the temperature of the preform 10 manufactured in the second injection molding section 33 and removes temperature unevenness, adjusting the temperature of the preform 10 to a temperature suitable for the final blow (for example, about 90°C to 105°C). Further, the second temperature adjustment section 34 also functions to cool the preform 10 in the high-temperature state after injection molding. Furthermore, the second temperature adjustment section 34 may have a function of heating the preform 10.

[0057] (Blow molding section 35) The blow molding section 35 performs blow molding on the preform 10 whose temperature has been adjusted by the second temperature adjustment section 34 to manufacture the peeling container 20. The blow molding section 35 includes a pair of split molds corresponding to the shape of the peeling container 20, namely a blow cavity mold, a bottom mold, a stretching rod, and an air introduction member (none of which are shown). The blow molding section 35 performs blow molding while stretching the preform 10. Thereby, the preform 10 can be shaped into the shape of the blow cavity mold to manufacture the peeling container 20.

[0058] (Take-out section 36) The take-out section 36 is configured to release the neck portion 21 of the peeling container 20 manufactured by the blow molding section 35 from the neck mold 37b and take out the peeling container 20 to the outside of the blow molding apparatus 30.

[0059] <Description of the method for manufacturing a container> Next, a method for manufacturing the peelable container 20 using the blow molding apparatus 30 of the present embodiment will be described. FIG. 8 is a flowchart showing the steps of the method for manufacturing the container 20.

[0060] (Step S101: First injection molding step) First, as shown in FIG. 4, in the first injection molding section 31, a first resin material is injected from the first injection device 38 into the mold cavity formed by the cavity mold 40, the core mold 41, and the neck mold 37b of the transfer mechanism 37, and the first layer 11 of the preform 10 is molded. At this time, due to the first protrusion 44, a recess 11a is formed at the bottom of the first layer 11.

[0061] After that, when the first injection molding section 31 is opened, the rotating plate 37a of the transfer mechanism 37 rotates by a predetermined angle, and the first layer 11 of the preform 10 held by the neck mold 37b is transferred to the first temperature adjustment section 32 in a state including the holding heat during injection molding.

[0062] (Step S102: First temperature adjustment step) Next, in the first temperature adjustment section 32, the first layer 11 of the preform 10 is accommodated in the first example of the mold unit 50a or the second example of the mold unit 50b, and the cooling of the first layer 11 and the adjustment of the temperature distribution (uniform temperature or removal of temperature deviation) are performed.

[0063] When the first example of the mold unit 50a is adopted, when the core mold 52a is inserted inside the first layer 11, the perforation 54a provided at the tip of the core mold 52a comes into contact with the bottom 15 of the first layer 11. At this time, when the movable mold 53a is raised toward the first layer 11, the first layer 11 is pressed against the core mold 52a, so that the perforation 54a penetrates the bottom 15 of the first layer 11, and an opening 16 is formed at the center of the bottom of the first layer 11.

[0064] When the mold unit 50b of the second example is adopted, when the core mold 52b is inserted inside the first layer 11, the core mold 52b comes into contact with the inner surface of the bottom 15 of the first layer 11. At this time, when the movable mold 53b is raised toward the first layer 11, the perforated portion 54a of the movable mold 53b penetrates the bottom 15 of the first layer 11, and an opening 16 is formed at the center of the bottom of the first layer 11.

[0065] Also, the first layer 11 in the first temperature adjustment unit 32 has the retained heat during injection molding and is in a state where it is relatively easy to deform. Therefore, when the opening 16 is formed in the first layer 11, the first resin material at the center of the bottom of the first layer 11 is pushed out through the perforated portions 54a and 54b and integrated with the material around the opening 16. Therefore, in this embodiment, it is not necessary to generate waste material when forming the opening 16. After that, the rotating plate 37a of the transport mechanism 37 rotates by a predetermined angle, and the first layer 11 of the preform 10 held by the neck mold 37b is transported to the second injection molding unit 33.

[0066] (Step S103: Second injection molding process) Subsequently, the first layer 11 of the preform 10 is accommodated in the second injection molding unit 33, and injection molding of the second layer 12 is performed. In the second injection molding unit 33, as shown in FIG. 7, a mold space is formed between the inner peripheral side of the first layer 11 and the surface of the core mold 61 facing the inner periphery of the first layer 11, and the second resin material is filled into the above mold space from the hot runner mold 62. When injection molding, the second resin material is guided from the opening 16 of the first layer 11 to the inner peripheral side of the first layer 11.

[0067] Here, the temperature of the second resin material filled in the second injection molding unit 33 is set to a temperature lower than the melting point of the first resin material. Also, the surface temperature of the first layer 11 when filling the second resin material in the second injection molding unit 33 is cooled to a temperature equal to or lower than the melting point of the second resin material.

[0068] In the second injection molding section 33, the cavity mold 60 faces the outer peripheral side of the first layer 11, and the shape of the first layer 11 is held from the outer peripheral side by the cavity mold 60. Therefore, even if the second resin material comes into contact with the first layer 11, thermal deformation of the first layer 11 can be suppressed.

[0069] Also, in the second injection molding section 33, since the second protrusion 64 penetrates and closes the recess 11a of the first layer 11, the recess 17 of the preform 10 is not blocked by the second resin material. Further, since the tip of the second protrusion 64 in the second injection molding section 33 protrudes to the inner peripheral side of the first layer, the recess 17 of the preform 10 formed by the second protrusion 64 has a shape in which the surface of the second layer 12 is exposed into the recess 17 through the first layer 11.

[0070] Also, in the second injection molding section 33, the axial depth of the mold space of the cavity mold 60 that houses the first layer 11 is shorter than the axial length of the first layer 11. Therefore, the bottom 15 of the first layer 11 is pressed against the bottom surface of the cavity mold 60, and the generation of a gap between the bottom 15 of the first layer 11 and the cavity mold 60 is suppressed. Accordingly, it becomes difficult for the second resin material to flow into the space between the first layer 11 and the cavity mold 60, and the occurrence of molding defects in which the second resin material covers the outer periphery of the first layer 11 is suppressed.

[0071] In the above manner, by the first injection molding step and the second injection molding step, a preform 10 in which the second layer 12 is laminated on the inner peripheral side of the first layer 11 is manufactured. Thereafter, when the second injection molding section 33 is opened, the rotary plate 37a of the transfer mechanism 37 rotates by a predetermined angle, and the preform 10 held by the neck mold 37b is transferred to the second temperature adjustment section 34 in a state including the holding heat during injection molding.

[0072] (Step S104: Second temperature adjustment step) Subsequently, the preform 10 is housed in the second temperature adjustment section 34, and temperature adjustment is performed to bring the temperature of the preform 10 closer to a temperature suitable for the final blow. Subsequently, the rotating plate 37a of the transfer mechanism 37 rotates by a predetermined angle, and the preform 10 after temperature adjustment held by the neck mold 37b is transferred to the blow molding section 35.

[0073] (Step S105: Blow molding process) Subsequently, in the blow molding section 35, blow molding of the release container 20 is performed. First, the blow cavity mold is closed to accommodate the preform 10 in the mold space, and by lowering the air introduction member (blow core), the air introduction member is brought into contact with the neck portion 13 of the preform 10. Then, the stretching rod is lowered to press the bottom portion 15 of the preform 10 from the inner surface, and while performing longitudinal axis stretching as necessary, blow air is supplied from the air introduction member to perform horizontal axis stretching of the preform 10. As a result, the preform 10 bulges and is shaped so as to adhere to the mold space of the blow cavity mold, and is blow molded into the release container 20. When the preform 10 is longer than the release container 20, the bottom mold waits at a lower position where it does not contact the bottom portion 15 of the preform 10 before the blow cavity mold is closed, and quickly rises to the molding position after the mold is closed.

[0074] In this embodiment, by blow molding the preform 10 having the concave portion 17 formed in the bottom portion 15, an air introduction hole 24 that penetrates the first layer 11 and reaches the surface of the second layer 12 can be reliably formed in the release container 20.

[0075] (Step S106: Container removal process) When the blow molding is completed, the blow cavity mold is opened. As a result, the release container 20 becomes movable from the blow molding section 35. Subsequently, the rotating plate 37a of the transfer mechanism 37 rotates by a predetermined angle, and the release container 20 is transferred to the take-out section 36. In the take-out section 36, the neck portion 21 of the release container 20 is released from the neck mold 37b, and the release container 20 is taken out to the outside of the blow molding apparatus 30.

[0076] Thus, one cycle in the manufacturing method of the peeling container 20 is completed. Thereafter, by rotating the rotary plate 37a of the transfer mechanism 37 by a predetermined angle, the above steps S101 to S106 are repeated. During the operation of the blow molding device 30, the manufacturing of six sets of containers with a time difference for each step is executed in parallel.

[0077] Also, due to the structure of the blow molding device 30, the times of the first injection molding step, the first temperature adjustment step, the second injection molding step, the second temperature adjustment step, the blow molding step, and the container take-out step are all of the same length. Similarly, the transfer times between the respective steps are also all of the same length.

[0078] Hereinafter, the effects of the blow molding device and the blow molding method of the present embodiment will be described. In the present embodiment, the first layer 11 (outer layer) of the preform 10 is formed in the first injection molding step, and the second layer 12 (inner layer) is injection molded from the opening 16 of the first layer 11 to the inside of the first layer 11 in the second injection molding step, thereby manufacturing the preform 10 having a two-layer structure. According to the present embodiment, the outer layer can be formed first with a resin material having a high melting point, and then the inner layer can be formed with a resin material having a lower melting point than the outer layer. That is, the injection molding of the inner layer can be continuously performed while the outer layer has the retained heat during injection molding, and the preform 10 having a two-layer structure suitable for the specifications of the peeling container 20 can be manufactured. In the present embodiment, since the preform 10 having a two-layer structure is demolded with both the outer layer and the inner layer having the retained heat during injection molding, a preform 10 suitable for manufacturing the peeling container 20 by the hot parison blow molding method can be obtained.

[0079] In this embodiment, the preform 10 having a two-layer structure is stretch blow molded to manufacture the peelable container 20 while having the retained heat during injection molding. Therefore, in this embodiment, a peelable container 20 excellent in aesthetic appearance, physical properties strength, etc. can be manufactured by a hot parison blow molding method. Compared with the cold parison blow molding, in this embodiment, it is not necessary to cool the manufactured preform 10 to near room temperature, and the process of reheating the preform 10 is also unnecessary. Therefore, according to this embodiment, a series of processes from the injection molding of the preform 10 to the blow molding of the peelable container 20 can be completed in a relatively short time, and the peelable container 20 can be manufactured in a shorter cycle.

[0080] Further, in this embodiment, a first temperature adjustment step is provided between the first injection molding step and the second injection molding step, and an opening 16 is formed in the first layer 11 in this first temperature adjustment step. By passing through the first temperature adjustment step, the cooling time in the mold in the first injection molding step can be shortened, and the uneven temperature of the first layer 11 can be suppressed before molding the second layer 12. Further, by forming the opening 16 in the first layer 11 in the first temperature adjustment step, it is not necessary to incorporate a mechanism for forming the opening 16 in the injection mold, so the configuration of the injection molding apparatus can be simplified.

[0081] The present invention is not limited to the above embodiment, and various improvements and design changes may be made without departing from the gist of the present invention.

[0082] In the above embodiment, the case of manufacturing a peelable container by a hot parison blow molding method using a preform having a laminated structure has been described. However, the blow molding method of the present invention is not limited to the manufacture of peelable containers, and is also applicable to the manufacture of other resin containers. For example, the present invention can also be applied to the case of manufacturing a resin decorative container by injection molding in the order of the outer layer and the inner layer using resin materials of different colors to form a preform having a gradation or color separation pattern, and then using a hot parison blow molding method.

[0083] In addition, the embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included. For example, the number of forming stations of the blow molding apparatus 30 may be increased or decreased as appropriate (for example, omitting the second temperature adjustment unit 34, the take-out unit 36, etc. to make it five). Further, the mold units 50a and 50b may be mounted on an injection molding apparatus not provided with the blow molding section 35 and used for the purpose of molding a preform for a peeling container.

Explanation of Signs

[0084] 10… preform, 11… first layer, 12… second layer, 15… bottom, 16… opening, 20… peeling container, 30… blow molding apparatus, 31… first injection molding section, 32… first temperature adjustment unit, 33… second injection molding section, 34… second temperature adjustment unit, 35… blow molding section, 38… first injection device, 39… second injection device, 50a, 50b… mold units, 51… cavity mold, 52a, 52b… core molds, 53a, 53b… movable molds, 54a, 54b… perforations, 55a, 55b… recesses

Claims

1. A mold unit that is applied to a method for manufacturing a resin container of the hot parison type, accommodates a bottomed resin preform having retained heat released from an injection mold, and cools the preform, comprising: a core mold having an outer shape corresponding to the inner shape of the preform and insertable into the interior of the preform; a cavity mold that accommodates the preform and adjusts the temperature of the preform; a movable member facing the bottom of the preform; and a punching portion that forms an opening penetrating the bottom of the preform in either the core mold or the movable member. The mold unit.

2. The punching portion is formed to protrude in the axial direction of the preform from the tip of the core mold, and the movable member has a recess for receiving the punching portion. The mold unit according to Claim 1.

3. The punching portion is formed to protrude in the axial direction of the core mold and formed in the movable member, and the core mold has a recess for receiving the punching portion. The mold unit according to Claim 1.

4. A first injection molding section that injection-molds a first layer of a bottomed cylindrical preform with a first resin material; a temperature adjustment section that has the mold unit according to any one of Claims 1 to 3, adjusts the temperature of the first layer manufactured in the first injection molding section, and forms an opening at the bottom of the first layer; a second injection molding section that injects a second resin material from the opening to the inner peripheral side of the first layer and laminates a second layer on the inner periphery of the first layer; and a blow molding section that blow-molds the multi-layer preform obtained in the second injection molding section in a state having retained heat during injection molding to manufacture a resin container. The blow molding apparatus.

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