Patent Publication Number: US-2023150182-A1

Title: Manufacturing method and manufacturing apparatus for delamination container

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a manufacturing method and a manufacturing apparatus for a delamination container. 
     Description of the Related Art 
     Conventionally, there has been known a resin-made delamination container having a two-layer structure of an inner layer and an outer layer, in which the inner layer is peeled from the outer layer in accordance with discharge of contents thereof. This type of delamination container is also referred to as a delamination bottle or an airless bottle, and is used as, for example, a container of a seasoning liquid such as soy sauce or of a cosmetic liquid of cosmetic products. 
     At present, in the production of this type of delamination container, an extrusion blow method is generally used, and a stretch blow method is not used as often (see JP 5267901). 
     For example, from the viewpoint of improving the appearance, dimensional accuracy, physical property strength, and the like of the delamination container and reducing the environmental load of unnecessary materials, applying a blow molding method of a one-stage hot parison type in which an injection molding step to a blow molding step are continuously performed in the production of the delamination container has been considered. 
     However, in the delamination container, the melting point of the resin material of the outer layer is often set higher than the melting point of the resin material of the inner layer. In the injection molding step for molding a preform having the two-layer structure, when the resin material of outer layer that is at a high temperature is injected after the inner layer is formed, the surface of the inner layer in contact with the resin material of the outer layer is melted and thermally deformed. For this reason, it is extremely difficult to manufacture a delamination container by using a blow molding method of a hot parison type. 
     When the weldability between the outer layer and the inner layer is low in the preform of the delamination container, unintended separation or misalignment between the outer layer and the inner layer can occur. For example, when the core mold inserted into the preform having the two-layer structure is pulled out, if the inner layer is fixed to the core mold and wound up, unintended separation or misalignment from the outer layer can occur. In addition, for example, when the preform having a two-layer structure is blow-molded, an event can occur in which the inner layer and the outer layer slip with respect to each other, and the delamination container is molded in a state where the outer layer and the inner layer are misaligned. 
     SUMMARY OF THE INVENTION 
     A manufacturing method for a delamination container as an aspect of the present invention includes a first injection molding step of injection-molding a first layer of a preform having a bottomed cylindrical shape from a first resin material, a second injection molding step of injecting a second resin material different from the first resin material to form a second layer on an inner peripheral side of the first layer, and a blow molding step of blow-molding, in a state of having residual heat from injection molding, the preform obtained in the second injection molding step, to manufacture the delamination container. In the second injection molding step, a second resin material is guided from an opening portion formed in the first layer toward the inner peripheral side of the first layer, and a locking portion protruding from the opening portion toward an outer peripheral side of the first layer is integrally formed with the second layer. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a longitudinal section view of a preform of a first embodiment. 
         FIG.  2    is a longitudinal section view of a delamination container of the first embodiment. 
         FIG.  3    is a diagram schematically illustrating a configuration of a blow molding apparatus according to the first embodiment. 
         FIGS.  4 A to  4 C  are diagrams illustrating a manufacturing process of the preform of the first embodiment. 
         FIG.  5 A  is a diagram illustrating the vicinity of a bottom portion of a first layer in a first injection molding unit of the first embodiment, and  FIG.  5 B  is a diagram illustrating the vicinity of the bottom portion of the preform in a second injection molding unit of the first embodiment. 
         FIGS.  6 A and  6 B  are perspective views of a configuration example of a second cavity mold of the first injection molding unit. 
         FIG.  7    is a flowchart illustrating steps of a manufacturing method for the delamination container. 
         FIG.  8    is a longitudinal section view of a preform of a second embodiment. 
         FIGS.  9 A to  9 C  are diagrams illustrating a manufacturing process of the preform of the second embodiment. 
         FIG.  10 A  is a diagram illustrating the vicinity of the bottom portion of the first layer in a first injection molding unit of the second embodiment, and  FIG.  10 B  is a diagram illustrating the vicinity of the bottom portion of the preform in a second injection molding unit of the second embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 
     In the embodiment, for the sake of more understandable description, structures or elements other than the main parts of the present invention will be described in a simplified or omitted manner. In addition, in the drawings, the same elements are denoted by the same reference signs. To be noted, shapes, dimensions, and the like of each element are schematically illustrated in the drawings, and do not indicate actual shapes, dimensions, and the like. 
     First Embodiment 
     &lt;Configuration Example of Preform&gt; 
     First, a configuration example of a preform for a delamination container according to a first embodiment will be described with reference to  FIG.  1   .  FIG.  1    is a longitudinal section view of a preform  10  of the first embodiment. The overall shape of the preform  10  is a bottomed cylindrical shape in which one end side is open and the other end side is closed. The preform  10  includes a body portion  14  formed in a cylindrical shape, a bottom portion  15  that closes the other end side of the body portion  14 , and a neck portion  13  formed in an opening on the one end side of the body portion  14 . 
     The preform  10  has a two-layer structure in which a second layer (inner layer)  12  is formed on the inside of a first layer (outer layer)  11 . The first layer  11  and the second layer  12  are formed from different thermoplastic resin materials by two-stage injection molding as will be described later. The first layer  11  is formed from a synthetic resin having excellent moldability and transparency. In contrast, the second layer  12  is formed from a synthetic resin having a property (for example, moisture barrier property, gas barrier property, heat resistance, and chemical resistance) for stably storing the contents of the container and suppressing deterioration (oxidation). In addition, the resin material of the first layer  11  is selected to have a melting point higher than that of the resin material of the second layer  12 . 
     Hereinafter, the resin material of the first layer  11  will be also referred to as a first resin material, and the resin material of the second layer  12  will be also referred to as a second resin material. 
     The combination of the first resin material and the second resin material can be appropriately selected according to the specification of the delamination container. Specific examples of the material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycyclohexanedimethylene terephthalate (PCTA), Tritan ((registered trademark): co-polyester manufactured by Eastman Chemical), polypropylene (PP), polyethylene (PE), polycarbonate (PC), polyethersulfone (PES), polyphenylsulfone (PPSU), polystyrene (PS), cyclic olefin polymer (COP/COC), polymethyl methacrylate (PMMA): acrylic resin, polylactic acid (PLA), and the like. 
     For example, the first resin material is polyethylene terephthalate (PET), and the second resin material is polypropylene (PP). The melting point of PP is about 160 to 170° C., and the melting point of PET is higher than the melting point of PP and is about 245 to 260° C. 
     In the body portion  14  of the preform  10 , a ratio (t 1 /t 2 ) of a thickness t 1  of the first layer  11  to a thickness t 2  of the second layer  12  is preferably 1.5 or more. The thickness ratio is preferably 3.0 or less from the viewpoint of ensuring the transparency of the delamination container to be molded. 
     In addition, in the bottom portion  15  of the preform  10 , an opening portion  16  penetrating the first layer  11  is formed at the center of the bottom portion of the first layer  11 . The opening portion  16  of the first layer  11  is closed from the inside by the second layer  12 . On the outer side of the first layer  11 , the second layer  12  has a locking portion  19  protruding outward from the opening portion  16  in the radial direction. The locking portion  19  may be annularly formed along the edge of the opening portion  16 , or a plurality of the locking portions may be formed at intervals in the circumferential direction. 
     In addition, a recess portion  17  for forming an air introduction hole in the delamination container is formed in the bottom portion  15  of the preform  10 . The recess portion  17  has, for example, a circular cross section, and is formed at least at one position spaced apart in the radial direction from the center of the bottom portion  15  of the preform  10 , but a plurality of recess portions  17  may be formed along the circumferential direction of the bottom portion  15 . The depth of the recess portion  17  in the thickness direction of the preform is set to such a dimension in which at least the recess portion  17  penetrates the first layer  11  and the surface of the second layer  12  is exposed in the recess portion  17 . To be noted, the recess portion  17  formed in the preform  10  having the two-layer structure may be distinguished from a recess portion (described later) formed only in the first layer  11  and may be referred to as a second recess portion. In addition, the cross section of the recess portion  17  may be a circular shape, an elliptical shape, a polygonal shape, a slit shape, or a shape in which these shapes are combined. 
     &lt;Configuration Example of Delamination Container&gt; 
     Next, a configuration example of the delamination container  20  formed from resin according to the first embodiment will be described with reference to  FIG.  2   .  FIG.  2    is a longitudinal section view of the delamination container  20  of the first embodiment. 
     The delamination container  20  is a bottle-shaped resin container obtained by performing stretch blow molding of the preform  10 , and contains, for example, a seasoning liquid such as soy sauce. To be noted, the delamination container  20  may be used to store other contents such as a cosmetic liquid of cosmetic products. 
     Similarly to the preform  10 , the delamination container  20  has a two-layer structure in which the second layer  12  is formed on the inside of the first layer  11 . In a body portion  22  of the delamination container  20 , a ratio (t 11 /t 12 ) of a thickness t 11  of the first layer  11  to a thickness t 12  of the second layer  12  is substantially similar to the ratio (t 1 /t 2 ) of the thickness in the body portion  14  of the preform  10 . 
     The delamination container  20  includes a neck portion  21  having an opening at an upper end thereof, 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 delamination container  20 , the body portion  14  and the bottom portion  15  of the preform  10  are expanded by stretch blow to be shaped into the body portion  22  and the bottom portion  23  of the delamination container  20 . In addition, at the time of the stretch blow, the recess portion  17  of the preform  10  is stretched, and thus an air introduction hole  24  penetrating the first layer  11  is formed in the bottom portion  23  of the delamination container  20 . 
     In the delamination container  20 , the space inside the second layer  12  is filled with the contents. In the delamination container  20 , when the contents are discharged from the second layer  12 , the air gradually flows into a space between the first layer  11  and the second layer  12  from 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 contents in the container can be replaced with air without bringing the contents of the second layer  12  into contact with air, and the contents filled into the second layer  12  can be discharged to the outside of the container. 
     In addition, similarly to the preform  10 , an opening portion  25  (non-laminated portion, single layer portion) penetrating the first layer  11  is formed at the center of the bottom portion  23  of the delamination container  20 . The opening portion  25  is filled with the material of the second layer  12  to close the opening portion  25 , and the second layer  12  is exposed to the outside of the first layer  11  in the vicinity of the opening portion  25  of the bottom portion  23  of the delamination container  20 . In addition, at the bottom portion  23  of the delamination container  20 , a locking portion  26  (bulging portion  26 ) of the second layer  12  protruding outward in the radial direction from the opening portion  25  of the first layer  11  is formed. The locking portion  26  is formed by stretching the locking portion  19  of the preform  10 . When the second layer  12  is exposed to the outside of the first layer  11  at the opening portion  25  of the delamination container  20 , the second layer  12  is partially fixed to the first layer  11 , and misalignment of the second layer  12  with respect to the first layer  11  is suppressed. 
     &lt;Description of Manufacturing Apparatus for Delamination Container&gt; 
       FIG.  3    is a diagram schematically illustrating a configuration of a blow molding apparatus  30  according to the first embodiment. The blow molding apparatus  30  of the first embodiment is an example of a manufacturing apparatus for the delamination container  20 , and employs a hot parison method (also referred to as a one-stage method) in which the delamination container  20  is blow-molded by utilizing residual heat (internal heat amount) from injection molding without cooling the preform  10  to room temperature. 
     The blow molding apparatus  30  includes a first injection molding unit  31 , a first temperature adjustment unit  32 , a second injection molding unit  33 , a second temperature adjustment unit  34 , a blow molding unit  35 , a taking-out unit  36 , and a conveyance mechanism  37 . The first injection molding unit  31 , the first temperature adjustment unit  32 , the second injection molding unit  33 , the second temperature adjustment unit  34 , the blow molding unit  35 , and the taking-out unit  36  are disposed at positions rotated by the same predetermined angle (for example, 60 degrees) about the conveyance mechanism  37 . To be noted, the blow molding apparatus  30  may omit the first temperature adjustment unit  32  (in this case, each molding station is disposed at a position rotated by 72 degrees about the conveyance mechanism  37 ). In addition, in the first injection molding unit  31  and the second injection molding unit  33 , an unillustrated core mold elevation mechanism is provided above the conveyance mechanism  37 . 
     (Conveyance Mechanism  37 ) 
     The conveyance mechanism  37  includes a rotating plate (transfer plate)  37   a  that rotates about a shaft in a direction perpendicular to the paper surface of  FIG.  3   . On the rotating plate  37   a , one or more neck molds  37   b  (not illustrated in  FIG.  3   ) for holding the neck portion  13  of the preform  10  (or the neck portion  21  of the delamination container  20 ) are arranged at each predetermined angle. The conveyance mechanism  37  rotates the rotating plate  37   a  to convey the preform  10  (or the delamination container  20 ) held by the neck mold  37   b  to the first injection molding unit  31 , the first temperature adjustment unit  32 , the second injection molding unit  33 , the second temperature adjustment unit  34 , the blow molding unit  35 , and the taking-out unit  36  in this order. To be noted, the conveyance mechanism  37  can also move up and down the rotating plate  37   a , and also performs operations related to mold closing and mold opening (mold releasing) in the first injection molding unit  31  and the second injection molding unit  33 . 
     (First Injection Molding Unit  31 ) 
     The first injection molding unit  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 mold  37   b  conveyed at the time of molding. The cavity mold  40  includes a first cavity mold  40 A on the opening side (upper side) and a second cavity mold  40 B on the bottom surface side (lower side). A first injection device  38  that supplies a first resin material to the hot runner mold  42  is connected to the first injection molding unit  31 . The cavity mold  40  and the hot runner mold  42  are fixed to a machine base of the blow molding apparatus  30  in an integrated state. The core mold  41  is fixed to a core mold elevation mechanism. 
       FIGS.  4 A and  4 B  illustrate the first injection molding unit  31  that molds the first layer  11  of the preform  10  of the first embodiment.  FIG.  5 A  is a diagram illustrating the vicinity of the bottom portion of the first layer  11  in the first injection molding unit  31  of the first embodiment.  FIG.  6 A  is a perspective view illustrating a configuration example of the cavity mold  40  (second cavity mold  40 B) of the first injection molding unit  31 . 
     The cavity mold  40  defines (determines) the shape of the outer periphery of the first layer  11 . The first cavity mold  40 A is a mold facing the opening side of the cavity mold  40  (the side in contact with the neck mold  37   b  when the mold is closed), and defines the shape of the outer periphery of the body portion of the first layer  11 . The second cavity mold  40 B is a mold facing the bottom surface side (the side in contact with the hot runner mold  42 ) of the cavity mold  40 , and defines the shape of the outer periphery of the bottom portion of the first layer  11 . The second cavity mold  40 B further includes a gate portion  40 Ba that guides the resin material from the hot runner mold  42  to the cavity surface. In addition, the hot runner mold  42  includes a resin supply portion  42   a  (resin flow path  42   a ) that introduces the first resin material plasticized (melted) by the first injection device  38  into the second cavity mold  40 B. 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  37   b  defines the outer shape of the neck portion  13  of the preform  10  (first layer  11 ). 
     As illustrated in  FIGS.  4 A and  4 B , in the first injection molding unit  31 , the cavity mold  40 , the core mold  41 , and the neck mold  37   b  of the conveyance mechanism  37  are closed to form a mold space for the first layer  11 . Then, the first resin material is poured from the bottom portion of the mold space described above through the hot runner mold  42 , and thus the first layer  11  of the preform  10  is manufactured in the first injection molding unit  31 . 
     A first protrusion portion  44  having a columnar shape, a tapered columnar shape, a prismatic shape, or the like is provided at a predetermined position on the upper surface side (cavity surface side) of the second cavity mold  40 B facing the outer periphery of the bottom portion of the first layer  11 . As illustrated in  FIG.  6 A , at least one first protrusion portion  44  is disposed at an interval in the radial direction from the center of the bottom portion where the resin supply portion  42   a  is located. As illustrated in  FIG.  5 A , a protrusion amount h 1  of the first protrusion portion  44  from the cavity standard surface of the second cavity mold  40 B (the cavity surface that defines the shape of the lower end side of the outer peripheral surface of the bottom portion of the first layer  11 ) is substantially the same dimension as the thickness of the first layer  11 . Therefore, when the molds of the first injection molding unit  31  are closed, the distal end of the first protrusion portion  44  faces the surface of the core mold  41  (disposed in the vicinity of the surface of the core mold  41 ). As a result, in the injection molding of the first injection molding unit  31 , a recess portion  11   a  such as a circular shape is formed in the first layer  11  at a position corresponding to the recess portion  17  of the preform  10  by the first protrusion portion  44 . The recess portion  11   a  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 portion  44 . To be noted, the recess portion  11   a  of the first layer  11  formed by the first injection molding unit  31  is also referred to as a first recess portion. 
     In addition, as illustrated in  FIG.  4 B , the resin supply portion  42   a  of the hot runner mold  42  is provided with a valve pin (a bar-shaped member that opens and closes the resin supply portion  42   a )  43  that is movable in the axial direction to a position close to the core mold  41 . The valve pin  43  is accommodated in the hot runner mold  42  until the mold space is filled with the first resin material, and protrudes to a position closer to the core mold  41  than the opening end on the cavity side of the gate portion  40 Ba after the mold space is filled with the first resin material. By such movement of the valve pin  43  during injection molding, a thin film portion  18  in which the thickness of the resin material is smaller than that of the peripheral portion can be formed at the center of the bottom portion of the first layer  11 . 
     In addition, even when the molds of the first injection molding unit  31  are opened, the neck mold  37   b  of the conveyance mechanism  37  keeps on holding and conveying the first layer  11  of the preform  10  without opening. The number of the preforms  10  simultaneously molded by the first injection molding unit  31  (that is, the number of the delamination containers  20  that can be simultaneously molded by the blow molding apparatus  30 ) can be appropriately set. 
     (First Temperature Adjustment Unit  32 ) 
     The first temperature adjustment unit  32  includes an unillustrated temperature adjustment mold (a heating pot or a temperature adjustment pot (conditioning pot) that adjusts the temperature of the first layer  11  from the outside, and a heating rod, a temperature adjustment rod (conditioning rod), or an air introduction rod that adjusts the temperature of the first layer  11  from the inside). The first temperature adjustment unit  32  cools (or heats) the first layer  11  in a high-temperature state after injection molding by accommodating the first layer  11  in the temperature adjustment mold maintained at a predetermined temperature. In addition, the first temperature adjustment unit  32  also has a function of adjusting the temperature distribution of the first layer  11  to a predetermined state before being conveyed to the second injection molding unit  33 . 
     (Second Injection Molding Unit  33 ) 
     The second injection molding unit  33  includes a cavity mold  50 , a core mold  51 , and a hot runner mold  52 , and performs injection molding of the second layer  12  on the inner peripheral side of the first layer  11  in cooperation with the neck mold  37   b  conveyed at the time of molding. The cavity mold  50  includes a first cavity mold  50 A on the opening side (upper side) and a second cavity mold  50 B on the bottom surface side (lower side). A second injection device  39  that supplies a second resin material to the hot runner mold  52  is connected to the second injection molding unit  33 . 
       FIG.  4 C  illustrates the second injection molding unit  33  that molds the second layer  12  of the preform  10 .  FIG.  5 B  is a diagram illustrating the vicinity of the bottom portion of the preform  10  in the second injection molding unit  33 . 
     The cavity mold  50  is a mold that accommodates the first layer  11 . The first cavity mold  50 A is a mold facing the opening side of the cavity mold  50 , and accommodates the body portion of the first layer  11 . The second cavity mold  50 B is a mold facing the bottom surface side of the cavity mold  50 , and accommodates the bottom portion of the first layer  11 . The second cavity mold  50 B further includes a gate portion  50 Ba that guides the resin material from the hot runner mold  52  to the cavity surface. In addition, the hot runner mold  52  includes, at the center of the bottom portion, a resin supply portion  52   a  (resin supply path  52   a ) that introduces the second resin material plasticized (melted) by the second injection device  39 . The core mold  51  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  50  from above. The neck mold  37   b  defines an upper end surface (top surface) of the neck portion  13  of the preform  10  (second layer  12 ). Note that the hot runner mold  52  may have a structure including a valve pin like the hot runner mold  42 . However, the position of the valve pin when closing the second resin material is set to a position not protruding from the opening end on the cavity side of the gate portion  50 Ba. 
     As illustrated in  FIG.  4 C , the second injection molding unit  33  accommodates the first layer  11  of the preform  10  injection-molded by the first injection molding unit  31 . In a state where the second injection molding unit  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  51 . In the second injection molding unit  33 , the second resin material is poured from the bottom portion of the mold space described above through the hot runner mold  52  to form the preform  10  in which the second layer  12  is formed on the inner peripheral side of the first layer  11 . 
     In addition, on the upper surface side (cavity surface side) of the second cavity mold  50 B facing the outer periphery of the bottom portion of the first layer  11 , a second protrusion portion  54  having a columnar shape or the like corresponding to the shape of the recess portion  17  of the preform  10  is provided at a predetermined position corresponding to the first protrusion portion  44  of the first injection molding unit  31 . The second protrusion portion  54  is inserted into the recess portion  11   a  of the first layer  11  when the first layer  11  is accommodated in the second injection molding unit  33 . As described above, the basic configuration of the protrusion and the like in the second cavity mold  50 B is substantially similar to that of the second cavity mold  40 B of the first injection molding unit  31 . 
     Here, as illustrated in  FIG.  5 B , a protrusion amount h 2  of the second protrusion portion  54  from the cavity standard surface of the second cavity mold  50 B (the cavity surface in contact with a lower end side region of the outer peripheral surface of the bottom portion of the first layer  11 ) is a larger dimension than the thickness of the first layer  11 . That is, the protrusion amount h 2  of the second protrusion portion  54  is larger than the protrusion amount h 1  of the first protrusion portion  44  (h 2 &gt;h 1 ). Therefore, when the second injection molding unit  33  is closed, the distal end of the second protrusion portion  54  penetrates the recess portion  11   a  of the first layer  11  and protrudes to the inner peripheral side of the first layer  11 . By providing the second protrusion portion  54  in the second cavity mold  50 B of the second injection molding unit  33 , the recess portion  17  can be formed in the bottom portion  15  of the preform  10 . 
     In addition, the protrusion amount h 2  of the second protrusion portion  54  is set to be smaller than the thickness of the preform  10 . That is, in the injection molding in the second injection molding unit  33 , since the second resin material flows into a space between the core mold  51  and the second protrusion portion  54 , a hole penetrating the second layer  12  is not formed by the second protrusion portion  54 . 
     In addition, as illustrated in  FIG.  5 B , in the cavity mold  50 , a cavity end portion  53  connected to the gate portion  50 Ba is formed with an enlarged diameter portion (bulging portion) expanding toward the mold space and having a curved surface shape. Therefore, in the vicinity of the center of the bottom portion of the second injection molding unit  33 , a gap is generated between the curved surface of the cavity end portion  53  of the cavity mold  50  and the outer peripheral surface of the first layer  11 . The second resin material flows into the gap described above during injection molding. As a result, the locking portion  19  protruding outward in the radial direction from the opening portion  16  can be integrally formed with the second layer  12  on the outside of the first layer  11 . 
     (Second Temperature Adjustment Unit  34 ) 
     The second temperature adjustment unit  34  includes an unillustrated temperature adjustment mold unit (a heating pot or a temperature adjustment pot (conditioning pot) that adjusts the temperature of the preform  10  from the outside, and a heating rod, a temperature adjustment rod (conditioning rod), or an air introduction rod that adjusts the temperature of the preform  10  from the inside). The second temperature adjustment unit  34  accommodates the preform  10  conveyed from the second injection molding unit  33  in a mold unit maintained at a predetermined temperature to equalize temperature and remove temperature unevenness, and adjusts the temperature of the preform  10  to a temperature suitable for final blowing (for example, about 90° C. to 105° C.). In addition, the second temperature adjustment unit  34  also has a function of cooling the preform  10  in a high temperature state after injection molding. 
     (Blow Molding Unit  35 ) 
     The blow molding unit  35  performs blow molding on the preform  10  whose temperature has been adjusted by the second temperature adjustment unit  34  to manufacture the delamination container  20 . 
     The blow molding unit  35  includes a blow cavity mold which is a pair of split molds corresponding to the shape of the delamination container  20 , a bottom mold, a stretching rod, and an air introduction member (all not illustrated). The blow molding unit  35  blow-molds the preform  10  while stretching the preform  10 . As a result, the preform  10  is shaped into the shape of the blow cavity mold, and the delamination container  20  can be manufactured. 
     (Taking-Out Unit  36 ) 
     The taking-out unit  36  is configured to release the neck portion  21  of the delamination container  20  manufactured by the blow molding unit  35  from the neck mold  37   b  and take out the delamination container  20  to the outside of the blow molding apparatus  30 . 
     &lt;Description of Manufacturing Method for Container&gt; 
     Next, a manufacturing method for the delamination container  20  by the blow molding apparatus  30  of the first embodiment will be described.  FIG.  7    is a flowchart illustrating steps of the manufacturing method for the delamination container  20 . 
     (Step S 101 : First Injection Molding Step) 
     First, as illustrated in  FIG.  4 A , in the first injection molding unit  31 , the first resin material is injected from the first injection device  38  into the mold space formed by the cavity mold  40 , the core mold  41 , and the neck mold  37   b , and the first layer  11  of the preform  10  is formed. At this time, the first protrusion portion  44  forms the recess portion  11   a  at the bottom portion of the first layer  11 . 
     In the first injection molding unit  31 , as illustrated in  FIG.  4 B , after the first layer  11  of the preform  10  is formed, a step of protruding the valve pin  43  to a position close to the core mold  41  is performed. As a result, the thin film portion  18  having a thickness smaller than that of the peripheral portion is formed at the center of the bottom portion of the first layer  11 . 
     Thereafter, the molds of the first injection molding unit  31  are opened to release the first layer. When the molds of the first injection molding unit  31  are opened, the rotating plate  37   a  of the conveyance mechanism  37  rotates by a predetermined angle, and the first layer  11  of the preform  10  held by the neck mold  37   b  is conveyed to the first temperature adjustment unit  32  in a state of having residual heat from injection molding. 
     (Step S 102 : First Temperature Adjustment Step) 
     Next, in the first temperature adjustment unit  32 , the first layer  11  of the preform  10  is accommodated in the temperature adjustment mold, and cooling of the first layer  11  and adjustment of the temperature distribution (temperature equalization and removal of temperature unevenness) are performed. To be noted, the first temperature adjustment step may be omitted. 
     After the first temperature adjustment step (or the first injection molding step), the rotating plate  37   a  of the conveyance mechanism  37  rotates by a predetermined angle, and the first layer  11  having undergone temperature adjustment and held in the neck mold  37   b  is conveyed to the second injection molding unit  33 . 
     (Step S 103 : Second Injection Molding Step) 
     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 illustrated in  FIG.  4 C , a mold space is formed between the inner peripheral side of the first layer  11  and the surface of the core mold  51  facing the inner periphery of the first layer  11 , and the second resin material is injected into the mold space described above from the hot runner mold  52 . To be noted, although the thin film portion  18  is formed at the bottom portion of the first layer  11 , the thin film portion  18  is broken by the injection pressure of the second resin material to form an opening portion  16  at the bottom portion, and the second resin material is guided from the opening portion  16  to the inner peripheral side of the first layer  11 . 
     Here, the temperature of the second resin material injected in the second injection molding unit  33  is set to a temperature lower than the melting point of the first resin material. In addition, the surface temperature of the first layer  11  when the second resin material is injected 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. 
     In the second injection molding unit  33 , the cavity mold  50  faces the outer peripheral side of the first layer  11 , and the shape of the first layer  11  is held by the cavity mold  50  from the outer peripheral side. Therefore, even when the second resin material comes into contact with first layer  11 , thermal deformation of first layer  11  can be suppressed. 
     In addition, in the second injection molding unit  33 , since the second protrusion portion  54  penetrates and closes the recess portion  11   a  of the first layer  11 , the recess portion  17  of the preform  10  is not closed by the second resin material. In addition, since the distal end of the second protrusion portion  54  in the second injection molding unit  33  protrudes to the inner peripheral side of the first layer, the recess portion  17  of the preform  10  formed by the second protrusion portion  54  has a shape that penetrates the first layer  11  and the surface of the second layer  12  is exposed in the recess portion  17 . 
     In addition, in the second injection molding unit  33 , the locking portion  19  is integrally formed with the second layer  12  on the outside of the first layer  11  by allowing the second resin material to flow into the gap between the curved surface of the cavity end portion  53  adjacent to the gate portion  50 Ba of the cavity mold  50 B and the outer peripheral surface of the first layer  11 . The locking portion  19  is caught on the outside of the first layer  11 , and thus the second layer  12  is prevented from slipping out from the first layer  11 . 
     As described above, the preform  10  in which the second layer  12  is formed on the inner peripheral side of the first layer  11  is manufactured by the first injection molding step and the second injection molding step. 
     Thereafter, when the molds of the second injection molding unit  33  are opened, the rotating plate  37   a  of the conveyance mechanism  37  rotates by a predetermined angle, and the preform  10  held by the neck mold  37   b  is conveyed to the second temperature adjustment unit  34  in a state of having residual heat from injection molding. 
     (Step S 104 : Second Temperature Adjustment Step) 
     Subsequently, in the second temperature adjustment unit  34 , the preform  10  is accommodated in the temperature adjustment mold unit, and temperature adjustment for bringing the temperature of the preform  10  closer to a temperature suitable for final blowing is performed. Thereafter, the rotating plate  37   a  of the conveyance mechanism  37  rotates by a predetermined angle, and the preform  10  having undergone temperature adjustment and held in the neck mold  37   b  is conveyed to the blow molding unit  35 . 
     (Step S 105 : Blow Molding Step) 
     Subsequently, in the blow molding unit  35 , blow molding of the delamination container  20  is performed. 
     First, the blow cavity mold is closed to accommodate the preform  10  in the mold space, and the air introduction member (blow core) is lowered, so that the air introduction member abuts 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 inside, and blow air is supplied from the air introduction member while performing longitudinal axis stretching as necessary, and thus the preform  10  is stretched in the lateral axis. As a result, the preform  10  is shaped by being bulged so as to be in close contact with the mold space of the blow cavity mold, and is thus blow-molded into the delamination container  20 . 
     (Step S 106 : Container Take-out Step) 
     When the blow molding is completed, the blow cavity mold is opened. As a result, the delamination container  20  becomes movable from the blow molding unit  35 . 
     Subsequently, the rotating plate  37   a  of the conveyance mechanism  37  rotates by a predetermined angle, and the delamination container  20  is conveyed to the taking-out unit  36 . In the taking-out unit  36 , the neck portion  21  of the delamination container  20  is released from the neck mold  37   b , and the delamination container  20  is taken out to the outside of the blow molding apparatus  30 . 
     Thus, one cycle in the manufacturing method for the delamination container ends. Thereafter, by rotating the rotating plate  37   a  of the conveyance mechanism  37  by a predetermined angle, the respective steps of S 101  to S 106  described above are repeated. To be noted, during the operation of the blow molding apparatus  30 , six sets of the delamination containers  20  are manufactured in parallel at a time difference of one step each. 
     In addition, due to the structure of the blow molding apparatus  30 , the waiting 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 the same. Similarly, the conveyance times between the steps are also the same. 
     Hereinafter, effects of the blow molding apparatus and the blow molding method of the first embodiment will be described. 
     In the first embodiment, the first layer  11  (outer layer) of the preform  10  is molded in the first injection molding step, and the second layer  12  (inner layer) is injection-molded on the inside of the first layer  11  from the opening portion  16  of the first layer  11  in the second injection molding step to manufacture the preform  10  having a two-layer structure. According to the first embodiment, the outer layer can be first formed from a resin material having a high melting point, and then the inner layer can be formed from a resin material having a melting point lower than that of the outer layer. That is, the injection molding of the inner layer can be continuously performed while the outer layer has the residual heat from the injection molding, so that the preform  10  having the two-layer structure suitable for the specification of the delamination container  20  can be manufactured. In the first embodiment, since the preform  10  having a two-layer structure is released in a state where both the outer layer and the inner layer have residual heat form injection molding, it is possible to obtain the preform  10  suitable for manufacturing the delamination container  20  by a blow molding method of a hot parison type. 
     Further, in the first embodiment, the preform  10  having the two-layer structure described above is subjected to stretch blow molding in a state where the preform  10  has the residual heat from injection molding to manufacture the delamination container  20 . Therefore, in the first embodiment, the delamination container  20  having excellent aesthetic appearance, physical property strength, and the like can be manufactured by a blow molding method of a hot parison type. As compared with blow molding of a cold parison type, in the first embodiment, it is not necessary to cool the produced preform  10  to near room temperature, and the step of reheating the preform  10  is also unnecessary. Therefore, according to the first embodiment, a series of steps from injection molding of the preform  10  to blow molding of the delamination container  20  can be completed in a relatively short time, and the delamination container  20  can be manufactured in a shorter cycle. 
     In addition, in the first embodiment, in the second injection molding step, the locking portion  19  is integrally formed on the outer side of the first layer  11  from the second resin material forming the second layer  12 , and the second layer  12  is prevented from coming off from the first layer  11 . 
     As a result, when a force in the pull-out direction acts on the second layer  12  toward the neck portion, the locking portion  19  abuts the first layer  11  to become a resistance to the force in the pull-out direction, and thus the outer layer and the inner layer of the preform  10  are less likely to deviate from each other. Therefore, in the first embodiment, for example, it is possible to suppress unintended separation and misalignment between the outer layer and the inner layer at the time of pulling out the core mold in the second injection molding step, the blow molding step, or the like, and it is possible to improve the production yield of the delamination container  20 . 
     Second Embodiment 
     Next, a second embodiment will be described. In the following description, elements similar to those of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted. 
     For example, in a case where the outer layer is molded first and the inner layer is molded later when a preform having a two-layer structure is molded, if the resin material of the inner layer to be injected later unintentionally wraps around the outer peripheral side to cover the outer side of the preform, the aesthetic appearance of the container after blow molding is greatly impaired. 
     In the second embodiment, a configuration for suppressing a molding defect in which the resin material of the inner layer unintentionally wraps around the outer peripheral side when the delamination container is manufactured by applying a blow molding method of a hot parison type will be described. 
       FIG.  8    is a longitudinal section view of a preform  10  of the second embodiment. Hereinafter, differences between the preform  10  of the first embodiment illustrated in  FIG.  1    and the second embodiment will be described. In the bottom portion  15  of the preform  10  of the second embodiment illustrated in  FIG.  8   , a raised portion  12   a  protruding in a curved surface shape is formed on the inner peripheral side of the second layer  12 . The raised portion  12   a  is a resin reservoir formed at the time of injection molding of the second resin material, and is formed at a position facing the opening portion  16  of the first layer  11 . 
     Note that the configuration of the delamination container  20  in the second embodiment is similar to that in the first embodiment, and thus redundant description will be omitted. 
     In addition, a basic configuration of the blow molding apparatus  30  of the second embodiment is similar to that of the blow molding apparatus  30  of the first embodiment illustrated in  FIG.  3   . Hereinafter, differences in the second embodiment will be described. 
       FIGS.  9 A to  9 C  are diagrams illustrating a manufacturing process of the preform of the second embodiment.  FIG.  10 A  is a diagram illustrating the vicinity of the bottom portion of the first layer in a first injection molding portion of the second embodiment, and  FIG.  10 B  is a diagram illustrating the vicinity of the bottom portion of the preform in a second injection molding portion of the second embodiment.  FIGS.  9 A to  9 C  correspond to  FIGS.  4 A to  4 C  of the first embodiment, and  FIGS.  10 A to  10 B  correspond to  FIGS.  5 A to  5 B  of the first embodiment. 
     In the first injection molding unit  31  of the second embodiment, as illustrated in  FIG.  9 A , the length of the inner peripheral portion of the cavity mold  40  in the axial direction corresponding from the upper end of the body portion to the bottom surface of the first layer  11  is set to L 1 . 
     In addition, in the second injection molding unit  33  of the second embodiment, as illustrated in  FIG.  9 C , the length (depth) in the axial direction of the inner peripheral portion of the cavity mold  50  that accommodates the upper end of the body portion and the bottom surface of the first layer  11  is set to L 2  smaller than L 1  (L 1 &gt;L 2 ). For example, L 2  is set to be smaller than L 1  by a deformation margin (corresponding to compression of the first layer  11  caused by pushing up of the cavity mold  50  or shrinkage of the first layer  11  caused by heat dissipation or the like before the second injection molding step) of the first layer  11 . That is, the depth of the mold space of the cavity mold  50  accommodating the first layer  11  is smaller than the length of the first layer  11  in the axial direction. 
     As illustrated in  FIGS.  9 C and  10 B , a concave portion  51   a  having a curved surface shape is formed at a distal end portion of a core mold  51  in the second embodiment. When the molds are closed, the concave portion  51   a  faces the outlet of the second resin material located at the center of the second cavity mold  50 B, and forms a space of a resin reservoir with the opening portion  16  of the first layer  11 . This resin reservoir forms the raised portion  12   a  on the inner peripheral side of the second layer  12 . 
     In addition, as illustrated in  FIG.  10 B , for example, in the second injection molding unit  33  of the second embodiment, an opening diameter d 2  (the diameter of the valve pin) of the distal end of the hot runner mold  52  is set to be smaller than the opening diameter (the diameter of the valve pin  43 ) of the distal end of the hot runner mold  42  of the first injection molding unit  31  and a diameter d 1  of the opening portion  16  of the first layer  11 . By reducing the opening diameter d 2  of the distal end of the hot runner mold  52  to be smaller than the diameter d 1  of the opening portion  16 , the flow velocity of the second resin material injected into the mold space of the second injection molding unit  33  can be increased. 
     As illustrated in  FIG.  7   , the steps of the manufacturing method for the delamination container  20  in the second embodiment include a first injection molding step (S 101 ), a first temperature adjustment step (S 102 ), a second injection molding step (S 103 ), a second temperature adjustment step (S 104 ), a blow molding step (S 105 ), and a container take-out step (S 106 ). The first injection molding step (S 101 ) and the first temperature adjustment step (S 102 ) of the second embodiment are similar to those of the first embodiment. 
     In the second injection molding step (S 103 ) of the second embodiment, 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 illustrated in  FIG.  9 C , a mold space is formed between the inner peripheral side of the first layer  11  and the surface of the core mold  51  facing the inner periphery of the first layer  11 , and the second resin material is injected into the mold space described above from the hot runner mold  52 . To be noted, although the thin film portion  18  is formed at the bottom portion of the first layer  11 , the thin film portion  18  is broken by the injection pressure of the second resin material to form an opening portion  16  at the bottom portion, and the second resin material is guided from the opening portion  16  to the inner peripheral side of the first layer  11 . 
     As described above, the depth of the mold space of the cavity mold  50  accommodating the first layer  11  is smaller than the length of the first layer  11  in the axial direction. Therefore, when the first layer  11  is accommodated in the cavity mold  50 , the bottom portion of the first layer  11  is pressed against and thus brought into contact with the bottom surface of the cavity mold  50 , so that it is possible to suppress generation of a gap between the bottom portion of the first layer  11  and the cavity mold  50 . 
     In addition, a space of a resin reservoir is formed between the opening portion  16  of the first layer  11  and the concave portion  51   a  of the core mold  51 . The second resin material that has passed through the opening portion  16  hits the concave portion  51   a  of the core mold  51  and is agitated in the space of the resin reservoir, and then flows into the mold space between the inner periphery of the first layer  11  and the surface of the core mold  51 . As the second resin material is agitated in the space of the resin reservoir, fragments of the thin film portion  18  of the first layer  11  are mixed with the high-temperature second resin material and melted. This makes it possible to dissipate the fragments of the thin film portion  18  to such an extent as to be visually unrecognizable. 
     In addition, the opening diameter d 2  of the distal end of the hot runner mold  52  is reduced to be smaller than the diameter d 1  of the opening portion  16  of the first layer  11 . By increasing the flow velocity of the second resin material until the second resin material passes through the distal end of the hot runner mold  52  and hits the concave portion  51   a , sufficient agitation of the second resin material is caused in the space of the resin reservoir, and the fragments of the thin film portion  18  can be more easily dissipated. Furthermore, the thin film portion  18  can be more easily broken. 
     To be noted, part of the second resin material is guided to the outside of first layer  11  through opening portion  16  after hitting the concave portion  51   a , and circulates in the vicinity of opening portion  16 . Such a flow also agitates the second resin material to promote the dissipation of the fragments of the thin film portion  18 . 
     Here, the temperature of the second resin material injected in the second injection molding unit  33  is set to a temperature lower than the melting point of the first resin material. In addition, the surface temperature of the first layer  11  when the second resin material is injected 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. 
     In the second injection molding unit  33 , the cavity mold  50  faces the outer peripheral side of the first layer  11 , and the shape of the first layer  11  is held by the cavity mold  50  from the outer peripheral side. Therefore, even when the second resin material comes into contact with first layer  11 , thermal deformation of first layer  11  can be suppressed. 
     In addition, in the second injection molding unit  33 , since the second protrusion portion  54  penetrates and closes the recess portion  11   a  of the first layer  11 , the recess portion  17  of the preform  10  is not closed by the second resin material. In addition, since the distal end of the second protrusion portion  54  in the second injection molding unit  33  protrudes to the inner peripheral side of the first layer, the recess portion  17  of the preform  10  formed by the second protrusion portion  54  has a shape that penetrates the first layer  11  and the surface of the second layer  12  is exposed in the recess portion  17 . 
     As described above, the preform  10  in which the second layer  12  is formed on the inner peripheral side of the first layer  11  is manufactured by the first injection molding step and the second injection molding step. 
     Thereafter, when the molds of the second injection molding unit  33  are opened, the rotating plate  37   a  of the conveyance mechanism  37  rotates by a predetermined angle, and the preform  10  held by the neck mold  37   b  is conveyed to the second temperature adjustment unit  34  in a state of having residual heat from injection molding. 
     To be noted, the second temperature adjustment step (S 104 ), the blow molding step (S 105 ), and the container take-out step (S 106 ) of the second embodiment are similar to those of the first embodiment. 
     Hereinafter, effects of the blow molding apparatus and the blow molding method of the second embodiment will be described. 
     In the second embodiment, in the second injection molding unit  33 , the depth of the mold space of the cavity mold  50  accommodating the first layer  11  is smaller than the length of the first layer  11  in the axial direction. Therefore, the bottom portion of the first layer  11  is pressed against the bottom surface of the cavity mold  50 , and generation of a gap between the bottom portion of the first layer  11  and the cavity mold  50  is suppressed. Therefore, according to the present embodiment, the second resin material is less likely to flow into a space between the first layer  11  and the cavity mold  50 , and occurrence of the molding defect in which the second resin material covers the outer periphery of the first layer  11  is suppressed. 
     In addition, in the second embodiment, the concave portion  51   a  is provided at the distal end portion of the core mold  51 , and the fragments of the thin film portion  18  are mixed and melted by being agitated with the high-temperature second resin material during injection molding, so that the fragments of the thin film portion  18  are easily dissipated. As a result, in the preform  10  and the delamination container  20 , it is possible to reduce the possibility that the aesthetic appearance is impaired due to the fragments of the thin film portion  18  remaining in the inner layer. 
     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. 
     In the above embodiment, an example in which one recess portion  17  is provided in the bottom portion  15  of the preform  10  has been described, but for example, a plurality of recess portions  17  may be formed.  FIG.  6 B  illustrates an example in which the first protrusion portions  44  are provided at two positions in the second cavity mold  40 B of the first injection molding unit  31 . In the example of  FIG.  6 B , the two first protrusion portions  44  are arranged at point-symmetrical positions with respect to the central axis at an interval of 180°. To be noted, the number of the first protrusion portions  44  may be three or more. In this case, it is preferable that the first protrusion portions  44  are arranged in a point-symmetric positional relationship with respect to the central axis. 
     According to the above configuration, the unevenness of the flow of the resin in the circumferential direction during the injection molding is further reduced. To be noted, in the case of the above configuration, it is also necessary to arrange second protrusion portions  54  at positions similar to the first protrusion portions  44  also in the second injection molding unit  33 . 
     In addition, the embodiment disclosed herein should be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated not by the above description but by the claims, and it is intended that meanings equivalent to the claims and all modifications within the scope are included.