Method for manufacturing resin containers, manufacturing apparatus, and mold unit

Abstract

A method for manufacturing a resin container comprises: a first injection molding process in which a first layer of a user-shaped preform having a groove extending in the axial direction is injection molded with a first resin material; a second injection molding process in which a second resin material having a different color from the first resin material is injected into the groove of the first layer and a second layer is laminated on the outer or inner side of the first layer; and a blow molding process in which a multilayer preform obtained from the second injection molding process is blow molded while having heat retained during injection molding, and a resin container having a vertical striped color shape formed by the second layer is manufactured.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a resin container, a manufacturing apparatus, and a mold unit. Background Technology

[0002] Containers for holding cosmetics or liquids require an appearance that allows for aesthetic appreciation of the container itself in order to increase consumer purchasing desire. For containers holding these types of cosmetics, glass bottles are preferably used because they have a sense of weight and luxury and can maintain an elegant appearance even after repeated use. In addition, there is a demand to add vertical stripes as an internal coloring to containers for cosmetics in order to improve the aesthetics of the container.

[0003] However, glass bottles are heavy and fragile, and the costs associated with transportation and manufacturing are high. For this reason, replacing glass bottles with resin containers is being considered for packaging products such as cosmetics.

[0004] As a method for manufacturing resin containers, the hot parison blow molding method has been known for a long time. In the hot parison blow molding method, the resin container is blow-molded using the heat retained during the injection molding of the preform. Therefore, compared to the cold parison method, it is advantageous in that it allows for the production of resin containers with a wide variety of designs and excellent aesthetic appearance.

[0005] For example, Patent Documents 1 to 4 disclose a configuration in which a longitudinal band-shaped gas barrier resin is arranged in parallel in the circumferential direction as an intermediate layer of a PET resin container to improve the gas barrier of the container. In the technology of Patent Document 1, two types of resins are combined within multiple nozzles and filled into a mold cavity to form a laminated preform. Prior art literature

[0006] Patent Document 1: Japanese Patent No. 4,953,178 Publication Patent Document 2: Japanese Patent No. 5,765,656 Publication Patent Document 3: Japanese Patent No. 6,058,484 Publication Patent Document 4: Japanese Patent No. 6,058,485 Publication The problem to be solved

[0007] However, in the technology of Patent Documents 1 to 4, it is actually very difficult to precisely control the width, position, and shape of the intermediate layer by simultaneously injecting multiple types of resins, and the configuration of the injection molding device is also complex and expensive. Therefore, the technology of Patent Document 1 is not necessarily suitable for applications where vertical stripes are stably formed by internal coloring in a container after blow molding.

[0008] Therefore, the present invention has been made in consideration of these problems and aims to provide a manufacturing method capable of stably forming a vertical striped color pattern through internal coloring in a container after blow molding. means of solving the problem

[0009] A method for manufacturing a resin container, which is one aspect of the present invention, comprises: a first injection molding process in which a first layer of a bottomless preform having a groove extending in the axial direction is injection molded with a first resin material; a second injection molding process in which a second resin material having a different color from the first resin material is injected into the groove of the first layer and a second layer is laminated on the outer or inner side of the first layer; and a blow molding process in which the multilayer preform obtained in the second injection molding process is blow molded while having heat retained during injection molding, and a resin container having a vertical striped color pattern formed by the second layer is manufactured. Effects of the invention

[0010] According to one aspect of the present invention, vertical striped color patterns can be stably formed in a container after blow molding by internal coloring. Brief explanation of the drawing

[0011] FIG. 1 is a cross-sectional view of a preform with a multilayer structure according to the present embodiment. FIG. 2 is a drawing showing an example of a resin container of the present embodiment. FIG. 3 is a schematic diagram showing the configuration of a blow molding device of the present embodiment. Figure 4 is a drawing showing the manufacturing process of the preform of the first example. Figure 5 is a drawing showing the manufacturing process of the preform of the second example. Figure 6 is a flowchart showing the process of a method for manufacturing a container. FIG. 7 is a drawing showing a preform of a modified example of the present embodiment. FIG. 8 is a schematic diagram showing the configuration of a blow molding device in another embodiment. FIG. 9 is a flowchart showing the process of a method for manufacturing a container in another embodiment. Specific details for implementing the invention

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0013] In the embodiments, structures or elements other than the main parts of the present invention are described in a simplified or omitted manner to facilitate understanding. Additionally, in the drawings, the same reference numerals are used for identical elements. Furthermore, the shape, dimensions, etc., of each element shown in the drawings are schematic representations and do not represent the actual shape, dimensions, etc.

[0014] <Example of Freeform Composition>

[0015] First, with reference to FIG. 1, an example of the configuration of a multilayer preform according to the present embodiment will be described.

[0016] FIG. 1(a) is a longitudinal cross-sectional view of a preform (10) of the first example of the present embodiment, and FIG. 1(b) is a cross-sectional view along line Ib-Ib of FIG. 1(a). FIG. 1(c) is a longitudinal cross-sectional view of a preform (10) of the second example of the present embodiment, and FIG. 1(d) is a cross-sectional view along line Id-Id of FIG. 1(c).

[0017] The overall shape of the preforms (10) of the first and second examples shown in FIG. 1 is a bottomless cylindrical shape with one end open and the other end closed. These preforms (10) have a first layer having a body part (14) formed in a cylindrical shape, a bottom part (15) that closes the other end of the body part (14), and a head part (13) formed at the opening on one end of the body part (14). In addition, these preforms have a multilayer structure in which a second layer (12) is laminated on the first layer (11). The first layer (11) and the second layer (12) are formed by two-stage injection molding as described below.

[0018] As shown in FIG. 1 (a) and (b), in the first example of the preform (10), a plurality of grooves (11a) extending along the axial direction are formed on the outer side of the first layer (11). The grooves (11a) of the first layer (11) are arranged at equal intervals in the circumferential direction, and thus the cross-section of the first layer (11) shown in FIG. 1 (b) forms the shape of an external gear. In addition, a second layer (12) is formed in each groove (11a) on the outer side of the first layer (11) to fill the space of the groove (11a).

[0019] Meanwhile, as shown in (c) and (d) of FIG. 1, in the preform (10) of the second example, a plurality of grooves (11b) extending along the axial direction are formed on the inner circumference side of the first layer (11). The grooves (11b) of the first layer (11) are arranged at equal intervals in the circumference direction, and thus the cross-section of the first layer shown in (d) of FIG. 1 forms an internal gear shape. In addition, a second layer (12) is formed in each groove (11b) on the inner circumference side of the first layer (11) to fill the space of the groove (11b). Also, as shown in (c) of FIG. 1, in the preform (10) of the second example, a hole (16) is formed in the center of the bottom of the first layer (11), and the hole (16) of the first layer (11) is blocked from the inside by the second layer (12).

[0020] In addition, the specifications, such as the shape or dimensions of the first layer (11) and the second layer (12), are appropriately adjusted according to the shape of the container being manufactured or the color pattern formed on the container.

[0021] Hereinafter, the resin material forming the first layer (11) is also referred to as the first resin material, and the resin material forming the second layer (12) is also referred to as the second resin material.

[0022] The first resin material and the second resin material are both thermoplastic synthetic resins and can be appropriately selected according to the specifications of the container. Specific types of materials include, for example, PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PCTA (polycyclohexanedimethylene terephthalate), Tritan (Tritan (registered trademark): copolyester manufactured by Eastman Chemical), PP (polypropylene), PE (polyethylene), PC (polycarbonate), PES (polyethersulfone), PPSU (polyphenylsulfone), PS (polystyrene), COP / COC (cyclic olefin polymer), PMMA (polymethyl methacrylate: acrylic), PLA (polylactic acid), nylon, etc. Additives such as coloring agents may be appropriately added to these resin materials.

[0023] In addition, in each of the above-mentioned preforms (10), the first layer (11) and the second layer (12) are made of resin materials of different colors. For example, the first resin material and the second resin material differ in the amount of coloring agent (shade of color) or the type of coloring agent (type of color). It is not necessary to add a coloring agent to either the first resin material or the second resin material.

[0024] In addition, all or at least one of the first layer (11) and the second layer (12), for example, the layer having a portion facing the outer periphery, may have the property of transmitting light (transparency). In addition, the layer having transparency may be colored. In this embodiment, the first resin material is described as being transparent (having transparency).

[0025] In addition, the first resin material and the second resin material can be appropriately combined according to the specifications of the container, and it is desirable to combine materials with high weldability to each other. As an example, the first resin material and the second resin material may be the same type of resin material with different coloring agent compositions (e.g., PETs together).

[0026] <Example of composition of resin container>

[0027] Next, referring to FIG. 2, an example of the configuration of a resin container (hereinafter also simply referred to as "container") according to the present embodiment will be described.

[0028] FIG. 2(a) is a drawing showing an example of a container (20) obtained by blow molding a preform (10) of the first example, and FIG. 2(b) is a cross-sectional view along line IIb-IIb of FIG. 2(a). FIG. 2(c) is a drawing showing an example of a container (20) obtained by blow molding a preform (10) of the second example, and FIG. 2(d) is a cross-sectional view along line IId-IId of FIG. 2(c). In each of FIG. 2(a) and FIG. 2(c), the right half of the drawing shows the exterior of the container (20), and the left half of the drawing shows the longitudinal section of the container (20).

[0029] The container (20) shown in FIG. 2 (a) and (c) contains, for example, lotion or liquid. The container (20) has a head portion (21) having an opening at the top, a cylindrical body portion (22) that is continuous from the head portion (21), and a bottom portion (23) that is continuous from the body portion (22).

[0030] The body portion (22) of these containers (20) is formed with a colored pattern extending along the axial direction to form a striped pattern in the circumferential direction. By applying this decorative pattern, the aesthetic appearance of the container (20) is improved, and when used as a cosmetic container, the consumer's desire to purchase can be further increased.

[0031] The color pattern of the container (20) of the present embodiment is formed by the thickness distribution of the first layer (11) and the second layer (12).

[0032] In the circumferential direction of the container (20), the parts other than the grooves (11a, 11b) of the first layer (11) (parts of the ridges (11c, 11d)) are formed almost entirely of the first layer (11) (high proportion of the first layer (11)), so the color of the first layer (11) is visible.

[0033] Meanwhile, in the circumferential direction of the container (20), a second layer (12) is stacked in each of the grooves (11a, 11b) of the first layer (11). Therefore, in the grooves (11a, 11b) of the first layer (11), the color of the second layer (12) located on the outer periphery is shown in FIG. 2 (a) and (b), or the color of the second layer (12) on the inner side is shown beyond the transparent first layer (11) in FIG. 2 (c) and (d).

[0034] Additionally, the thickness of the body portion (22) of the container (20) may be formed to be significantly thinner than the bottom portion (23), and the body portion (22) may have a uniform thickness distribution. If the container (20) is shaped with the above thickness distribution, a sense of luxury or weight is emphasized, and the container (20) can be made closer to the image of a cosmetic container that consumers have.

[0035] <Description of the container manufacturing device>

[0036] FIG. 3 is a schematic diagram showing the configuration of a blow molding device of the present embodiment. The blow molding device (30) of the present embodiment, as an example of a container manufacturing device, adopts a hot parison method (also called a "1-stage method") in which a container (20) is blow molded by utilizing the retained heat (internal heat quantity) during injection molding without cooling the preform (10) to room temperature.

[0037] The blow molding device (30) comprises a first injection molding section (31), a second injection molding section (32), a temperature control section (33), a blow molding section (34), an ejection section (35), and a conveying mechanism (36). The first injection molding section (31), the second injection molding section (32), the temperature control section (33), the blow molding section (34), and the ejection section (35) are arranged at positions rotated by a predetermined angle (e.g., 72 degrees) around the conveying mechanism (36).

[0038] (Return mechanism (36))

[0039] The conveying mechanism (36) is equipped with a conveying plate (not shown in FIG. 3) that rotates around an axis in the direction perpendicular to the ground in FIG. 3. A neck shape (36a) (not shown in FIG. 3) that holds the head portion (13) of the preform (10) (or the head portion (21) of the container (20)) is disposed on the conveying plate. When the conveying plate is composed of a single roughly disc-shaped member, at least one neck shape (36a) is disposed at each predetermined angle. When the conveying plate is composed of a roughly fan-shaped member divided into each molding portion, at least one neck shape (36a) is disposed on each divided conveying plate.

[0040] The conveying mechanism (36) conveys the preform (10) (or container (20)), in which the head portion is held by the neck shape (36a), in the order of the first injection molding section (31), the second injection molding section (32), the temperature control section (33), the blow molding section (34), and the ejection section (35) by rotating the conveying plate. Accordingly, each neck shape (36a) is shared in a plurality of molding stations (at least in the first injection molding section (31) and the second injection molding section (32). In addition, a tapered portion (36a1) is formed on the outer surface (or inner surface) of the neck shape (36a). By the tapered portion (36a1) contacting or fitting with the mold of each molding station, the relative positional relationship between the two during molding can be regulated. Additionally, the conveying mechanism (36) may raise and lower the transfer plate and also perform operations related to mold closing or mold opening (molding) in the first injection molding section (31) or the second injection molding section (32).

[0041] (First injection molding section (31))

[0042] The first injection molding unit (31) is equipped with a first injection molding mold consisting of a cavity type (40), a core type (41), and a hot runner type (42), and manufactures a first layer (11) of a preform (10). A first injection device (37) that supplies a first resin material to the hot runner type (42) is connected to the first injection molding unit (31). The cavity type (40) is provided with a fitting part (fitting protrusions, position regulating parts) (40b) on the side opposite to the side facing the hot runner type (42) (see FIG. 4 (a), FIG. 5 (a), (b)). The fitting portion (40b) has a tapered portion (40b1) that is roughly similar to the tapered portion (36a1) of the neck shape (36a), and receives the tapered portion (36a1) of the neck shape (36a) at the tapered portion (40b1).

[0043] FIG. 4(a) shows a first injection molding part (31a) that molds the first layer (11) of the first example preform (10) (Fig. 1(a)). FIG. 5(a) and (b) show a first injection molding part (31b) that molds the first layer (11) of the second example preform (10) (Fig. 1(c)). Also, when there is no need to distinguish between the first injection molding part (31a, 31b) in this specification, they are collectively referred to as the first injection molding part (31).

[0044] As shown in FIG. 4(a) and FIG. 5(a), in the first injection molding section (31), the above cavity type (40), core type (41) and the neck type (36a) of the conveying mechanism (36) are closed to form a mold space (molding space) of the first layer (11).

[0045] The cavity shape (40) shown in FIG. 4 (a) defines the outer circumference shape of the inner layer (first layer (11)) of the preform (10). The core shape (41) shown in FIG. 4 (a) is inserted into the cavity shape (40) and defines the inner circumference shape of the inner layer.

[0046] Meanwhile, the cavity shape (40) shown in FIGS. 5 (a) and (b) defines the outer circumference shape of the outer layer (first layer (11)) of the preform (10). The core shape (41) shown in FIGS. 5 (a) and (b) is inserted into the cavity shape (40) and defines the inner circumference shape of the outer layer.

[0047] Then, by flowing a first resin material from the first injection device (37) into the above-mentioned mold space through a hot runner type (42), a first layer (11) of the preform (10) is manufactured in the first injection molding part (31).

[0048] Here, on the inner surface of the cavity shape (40) of the first injection molding part (31a), protrusions (40a) extending along the axial direction are formed at equal intervals in the circumferential direction, and although not shown in the illustration, the inner surface of the cavity shape (40) forms an internal gear shape. Each protrusion (40a) of this cavity shape (40) has a shape corresponding to the groove (11a) of the first layer (11), and by the above cavity shape (40), as shown in (b) of FIG. 1, a groove (11a) extending along the axial direction and a ridge (a narrow, thin, and long protrusion) (11c) are formed on the outer circumference of the first layer (11).

[0049] Meanwhile, on the surface of the core shape (41) of the first injection molding part (31b), protrusions (41a) extending along the axial direction are formed at equal intervals in the circumferential direction, and although not shown in the illustration, the cross-section of the core shape (41) forms an internal gear shape. Each protrusion (41a) of the core shape (41) has a shape corresponding to the groove (11b) of the first layer, and by the above-described core shape (41), grooves (11b) and ridges (11d) extending along the axial direction are formed on the inner circumference of the first layer (11), respectively, as shown in (d) of FIG. 1.

[0050] In addition, Figures 5 (a) and (b) show the cross-sectional view of the portion of the protrusion (41a) of the core type (41).

[0051] Also, as shown in FIG. 5(b), in the first injection molding section (31b), a valve pin (43) that can move axially to a position close to the core mold (41) is provided inside the hot runner mold (42). The valve pin (43) is received inside the hot runner mold (42) until the first resin material is filled into the mold space, and after the first resin material is filled into the mold space, it protrudes to a position close to the core mold (41). By moving the valve pin (43) during injection molding, a thin film section (18) in which the thickness of the resin material is thinner than the surrounding area can be formed at the center of the bottom of the first layer (11).

[0052] Also, even when the first injection molding section (31) is opened, the neck (36a) of the conveying mechanism (36) is not opened and maintains the first layer (11) of the preform (10) as is and conveys it. The number of preforms (10) that are simultaneously molded in the first injection molding section (31) (i.e., the number of containers (20) that can be simultaneously molded in the blow molding device (30)) can be appropriately set.

[0053] (2nd injection molding part (32))

[0054] The second injection molding unit (32) is equipped with a mold for second injection molding composed of a cavity type (50), a core type (51), and a hot runner type (52), and injection molds a second layer (12) on the outer or inner periphery of the first layer (11). A second injection device (38) that supplies a second resin material to the hot runner type (52) is connected to the second injection molding unit (32). In addition, the cavity type (50) is provided with a fitting part (position regulating part) (50b) on the side opposite to the side facing the hot runner type (52) (see FIG. 4 (b) and FIG. 5 (c)). The fitting portion (50b) has a tapered portion (36a1) of the neck shape (36a) and a tapered portion (50b1) of approximately the same shape, and receives the tapered portion (36a1) of the neck shape (36a) at the tapered portion (50b1).

[0055] FIG. 4(b) shows a second injection molding part (32a) that molds the second layer (12) of the first example preform (10) (Fig. 1(a)). FIG. 5(c) shows a second injection molding part (32b) that molds the second layer (12) of the second example preform (10) (Fig. 1(c)). Additionally, when there is no need to distinguish between the second injection molding part (32a, 32b) for the purposes of this specification, they are collectively referred to as the second injection molding part (32).

[0056] The second injection molding section (32a) accommodates the first layer (11) of the preform (10) injection molded in the first injection molding section (31a). As shown in FIG. 4 (b), when the second injection molding section (32a) is closed, a mold space is formed between the inner surface of the cavity mold (50) and the body portion on the outer side of the first layer (11) and the bottom portion.

[0057] The core shape (51) shown in FIG. 4(b) is inserted into the inner layer (first layer (11)) of the preform (10) and holds the inner layer from the inside. The cavity shape (50) shown in FIG. 4(b) accepts the inner layer into which the core shape (51) is inserted, and also forms a shape space of the outer layer (second layer (12)) between the inner layer and the outer surface of the inner layer, and defines the outer surface shape of the outer layer.

[0058] By filling the second resin material from the second injection device (38) through the hot runner type (52) into the above-mentioned mold space, a second layer (12) is formed in each part of the groove (11a) of the first layer (11). By this, the first example preform (10) is manufactured.

[0059] The second injection molding section (32b) accommodates the first layer (11) of the preform (10) injection molded in the first injection molding section (31b). As shown in FIG. 5 (c), when the second injection molding section (32b) is in a closed state, a mold space is formed between the groove (11b) on the inner side of the first layer (11) and the surface of the core mold (51).

[0060] The cavity type (50) shown in FIG. 5 (c) accepts the outer layer (first layer (11)) of the preform (10) and maintains the outer layer from the outside. The core type (51) shown in FIG. 5 (c) is inserted into the inner side of the outer layer and forms a space for the inner layer (second layer (12)) between the inner surface of the outer layer and the inner surface of the outer layer, and defines the inner surface shape of the inner layer.

[0061] By filling the second resin material from the second injection device (38) through the hot runner type (52) within the above-mentioned mold space, a second layer (12) is formed in each part of the groove (11b) of the first layer (11). By this, a preform (10) of the second example is manufactured. In addition, in the second injection molding part (32), a narrow mold space may be provided between the ridge (11c) and the cavity type (50) or between the ridge (11d) and the core type (51), and a thin second layer (12) may also be formed on the outer surface of the ridge (11c, 11d). The thickness of the second layer (12) in the ridge (11c, 11d) is preferably 1 / 4 or less of the thickness in the groove (11a, 11b), and more preferably 1 / 5 or less of the thickness in the groove (11a, 11b).

[0062] In addition, Figure 5 (c) shows a longitudinal section at a location where a groove (11b) is formed in the first layer (11).

[0063] (Temperature control unit (33))

[0064] The temperature control unit (33) is equipped with a mold (temperature control port or temperature control core) for temperature control that is not shown. The temperature control unit (33) performs uniform temperature control or eliminates uneven temperature by receiving the preform (10) conveyed from the second injection molding unit (32) into a mold unit maintained at a predetermined temperature, and adjusts the temperature of the preform (10) to a temperature suitable for the final blow (e.g., about 90°C to 105°C). In addition, the temperature control unit (33) also performs the function of cooling the preform (10) in a high-temperature state after injection molding. Furthermore, the temperature control port is equipped with a fitting part (position regulating part) that can be fitted by contacting the neck type (36a), and the fitting part has a tapered part that is approximately similar to the tapered part (36a1) of the neck type (36a).

[0065] (Blow molding part (34))

[0066] The blow molding unit (34) performs blow molding on the preform (10) whose temperature is controlled by the temperature control unit (33) and manufactures a container (20).

[0067] The blow molding section (34) is equipped with a blow molding mold comprising a pair of split-type blow cavity types corresponding to the shape of the container (20), a bottom type, an elongation rod, and an air introduction member (blow core, all not shown). The blow molding section (34) blow molds the preform (10) while elongating it. By doing so, the preform (10) is formed into the shape of the blow cavity type, thereby enabling the manufacture of the container (20). The pair of blow cavity types is equipped with a fitting part (position regulating part) that can be fitted by contacting the neck type (36a), and the fitting part has a tapered part that is approximately similar to the tapered part (36a1) of the neck type (36a).

[0068] (Extraction unit (35))

[0069] The extraction unit (35) is configured to open the head portion (21) of the container (20) manufactured in the blow molding unit (34) from the neck portion (36a) and to extract the container (20) to the outside of the blow molding device (30). The extraction unit (35) is provided with an extraction rod (a mold for extraction) inserted through the opening of the neck portion (36a). The extraction rod is provided with a fitting portion (a position regulating portion) that can roughly come into contact with the neck portion (36a).

[0070] <Description of the container manufacturing method>

[0071] Next, a method for manufacturing a container using the blow molding device (30) of the present embodiment will be described. FIG. 6 is a flowchart showing the process of the method for manufacturing a container.

[0072] (Step S101: First injection molding process)

[0073] First, as shown in FIG. 4(a) and FIG. 5(a), in the first injection molding section (31), a first resin material is injected from the first injection device (37) into a mold space formed by a cavity shape (40), a core shape (41), and a neck shape (36a) of a conveying mechanism (36), and a first layer (11) of a preform (10) is formed. When forming the preform (10) of the first example, the first injection molding section (31a) is used, and when forming the preform (10) of the second example, the first injection molding section (31b) is used.

[0074] In the first injection molding section (31b), as shown in FIG. 5 (b), after the first layer (11) of the preform (10) is molded, a process is performed to protrude the valve pin (43) to a position close to the core shape (41). By doing so, a thin film section (18) is formed at the center of the bottom of the first layer (11), with a thickness thinner than that of the surrounding area.

[0075] After that, when the first injection molding section (31) opens, the transfer plate of the conveying mechanism (36) rotates at a predetermined angle, and the first layer (11) of the preform (10) held in the neck shape (36a) is conveyed to the second injection molding section (32) while containing the heat retained during injection molding.

[0076] (Step S102: Second injection molding process)

[0077] Next, the first layer (11) of the preform (10) is received in the second injection molding section (32), and injection molding of the second layer (12) is performed. When forming the preform (10) of the first example, the second injection molding section (32a) is used, and when forming the preform (10) of the second example, the second injection molding section (32b) is used.

[0078] In the second injection molding section (32a), as shown in Fig. 4 (b), a mold space is formed between the groove (11a) on the outer side of the first layer (11) and the cavity mold (50) facing the outer side of the first layer (11). A second resin material is filled into the mold space from a hot runner mold (52).

[0079] In FIG. 4(b), a core shape (51) is inserted into the inner circumference of the first layer (11), and the shape of the first layer (11) is maintained from the inner circumference by the core shape (51). Because of this, even if the second resin material comes into contact with the first layer (11), thermal deformation of the first layer (11) can be suppressed. In this way, when molding the preform (10) of the first example, a second layer (12) can be formed on the outer circumference of the first layer (11).

[0080] Meanwhile, in the second injection molding section (32b), as shown in Fig. 5 (c), a mold space is formed between the groove (11b) on the inner circumference side of the first layer (11) and the core mold (51) facing the inner circumference of the first layer (11). A second resin material is filled into the mold space from a hot runner mold (52). Additionally, a thin film section (18) is formed at the bottom of the first layer (11), but the thin film section (18) is broken by the injection pressure of the second resin material, creating a hole (16) at the bottom, and the second resin material is guided to the inner circumference side of the first layer (11) through the hole (16).

[0081] In Fig. 5(c), a cavity shape (50) faces the outer side of the first layer (11), and the shape of the first layer (11) is maintained from the outer side by the cavity shape (50). Because of this, even if the second resin material comes into contact with the first layer (11), thermal deformation of the first layer (11) can be suppressed. In this way, when molding the preform (10) of the second example, a second layer (12) can be formed on the inner side of the first layer (11).

[0082] In addition, the first layer (11) in the second injection molding process retains heat during injection molding and is in a relatively deformable state. Therefore, when the second resin material is injected into the mold space, the air present in the mold space is pushed upward and exhausted while slightly elastically deforming the first layer (11). Because of this, it is difficult for air to remain during the molding of the second layer (12), so molding defects of the preform (10) are suppressed.

[0083] As described above, a preform (10) of the first example or the second example is manufactured by the first injection molding process and the second injection molding process.

[0084] After that, when the second injection molding section (32) opens, the transfer plate of the conveying mechanism (36) rotates at a predetermined angle, and the preform (10) held in the neck mold (36a) is conveyed to the temperature control section (33) while containing the heat retained during injection molding.

[0085] (Step S103: Temperature adjustment process)

[0086] Next, in the temperature control unit (33), the preform (10) is received in the mold unit for temperature control, and temperature control is performed to bring the temperature of the preform (10) close to a temperature suitable for the final blow. After that, the transfer plate of the conveying mechanism (36) is rotated at a predetermined angle, and the preform (10) after temperature control, which is maintained in the neck shape (36a), is conveyed to the blow molding unit (34).

[0087] (Step S104: Blow molding process)

[0088] Next, blow molding of the container (20) is performed in the blow molding section (34).

[0089] 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 comes into contact with the head portion (13) of the preform (10). Then, the stretching rod is lowered to suppress the bottom portion (15) of the preform (10) from the inner surface, and while performing longitudinal stretching as needed, blow air is supplied from the air introduction member to stretch the preform (10) along the transverse axis. By doing this, the preform (10) is bulged and molded to adhere to the mold space of the blow cavity mold, and is blow-molded into a container (20). In addition, if the preform (10) is longer than the container (20), the bottom mold is kept in a lower position that does not come into contact with the bottom portion of the preform (10) before the blow cavity mold is closed, and is rapidly raised to the molding position after the mold is closed.

[0090] In addition, in this embodiment, by blow molding the preform (10) of the first example or the second example, a container (20) is manufactured with a vertical striped pattern that changes color in the circumferential direction due to the stretching of the first layer (11) and the second layer (12).

[0091] (Step S105: Container extraction process)

[0092] When blow molding is finished, the blow cavity is opened. By doing so, the container (20) can be moved from the blow molding section (34).

[0093] Next, the transfer plate of the transfer mechanism (36) rotates at a predetermined angle, and the container (20) is transferred to the extraction unit (35). At the extraction unit (35), the head portion (21) of the container (20) is opened from the neck portion (36a), and the container (20) is ejected to the outside of the blow molding device (30).

[0094] With this, one cycle in the method of manufacturing a container is completed. Afterwards, by rotating the transfer plate of the conveying mechanism (36) by a predetermined angle, each process from S101 to S105 above is repeated. In addition, when operating the blow molding device (30), the manufacturing of 5 sets of containers with a time difference of 1 process is carried out in parallel.

[0095] In addition, due to the structure of the blow molding device (30), the time for each of the first injection molding process, the second injection molding process, the temperature adjustment process, the blow molding process, and the container ejection process is the same length. Likewise, the return time between each process is also the same length.

[0096] As described above, in the present embodiment, a first layer (11) of a preform (10) is injection molded in a first injection molding process, and a second layer (12) is injection molded into grooves (11a, 11b) on the inner or outer side of the first layer (11) in a second injection molding process to manufacture a preform (10) with a multilayer structure. In the present embodiment, by forming the preform (10) with a multilayer structure through two stages of injection molding, the shape and thickness distribution of the grooves (11a, 11b) of the first layer (11) and the second layer (12) formed in the grooves (11a, 11b) can be controlled with high precision. By doing so, a vertical striped shape can be stably formed in the container (20) by internal coloring.

[0097] In addition, in this embodiment, a multilayer structure preform (10) is manufactured by two-stage injection molding, and a container (20) is manufactured by blow molding the preform (10) while maintaining the heat retained during injection molding. Therefore, compared to the case where a multilayer structure preform is manufactured by a single injection molding, the device configuration and control of each injection molding part can be simplified, so the manufacturing cost of the container can be reduced.

[0098] In addition, compared to the case where, for example, a cooled preform is fitted to produce a multi-layered preform and then blow molding is performed after reheating (cold parison method), in the present embodiment, the preform does not need to be cooled to near room temperature, and the processes of assembling the preform or reheating are also unnecessary. Therefore, according to the present embodiment, a series of processes from injection molding of the preform (10) to blow molding of the container (20) can be completed in a relatively short time, and a container (20) having a vertical striped shape can be manufactured in a shorter cycle.

[0099] The present invention is not limited to the above embodiments, and various improvements and design changes may be made within the scope of not departing from the spirit of the invention.

[0100] In the above embodiment, an example was described in which a preform (10) with a two-layer structure is formed by two-stage injection molding, and the preform (10) is blow-molded. However, in the blow-molding apparatus (30) of the present invention, additional injection molding sections may be added, and a preform with an n-layer structure may be formed by n-stage injection molding (provided that n is an integer greater than or equal to 3). By doing so, it becomes possible to manufacture a container with a more complex color scheme. Furthermore, when three or more injection molding sections are provided, a temperature control section may be appropriately added between the injection molding sections to adjust the heat retained by each layer to a desired temperature.

[0101] Furthermore, the striped pattern of the present invention is not limited to the examples of the above embodiments. As an example, FIG. 7(a) shows a cross-section of a preform (10) in which two grooves (11a) (ridges (11c)) are formed at 180° intervals on the outer circumference of the first layer (11) as a modified example of FIG. 1(b). When the preform (10) of FIG. 7(a) is blow-molded, a container (20) having two vertical striped patterns is formed. In addition, when forming a container of the same type, a groove (11b), a ridge (11d), and a second layer (12) may be formed on the inner circumference of the first layer (11). Also, since the first layer (11) forming the ridge (11c) or groove (11b) is transparent (possessing light transmittance), the body portion of the container (20) corresponding to the ridge (11c) or groove (11b) can also be a portion where the remaining amount of contents can be checked.

[0102] Additionally, FIG. 7(b) shows a cross-section of a preform (10) in which the depth of the groove (11b) changes in a curved shape in the circumferential direction as a variation of FIG. 1(d). When the preform (10) of FIG. 7(b) is blow-molded, a periodic gradient in the shape of vertical stripes can be created in the circumferential direction of the container (20) along with the change in thickness in the circumferential direction of the second layer (12). Furthermore, when forming a container of the same type, the groove (11a) and the second layer (12) may be formed on the outer circumference of the first layer (11).

[0103] In addition, in (d) of FIG. 2, the ridge (11d) of the first layer may be shaped to protrude toward the central axis of the container (20), and a convex rib may be formed on the inner side of the container. The convex rib formed on the inner side of the container (20) is formed to extend from at least the lower side of the body portion (22) to the inner side of the bottom portion (23), and it is preferable to provide the spacing of the convex ribs to be approximately even. By doing so, the rigidity or pressure resistance of the container (20) can be increased.

[0104] In addition, specifications such as the number, width, and spacing of the grooves for each variant can be changed at will.

[0105] In addition, in the above embodiment, an example configuration of a so-called 5-station type blow molding device (30) has been described. However, the blow molding device of the present invention may also be a 6-station type blow molding device having a temperature control unit that additionally heats or cools the first layer (11) of the preform (10) between the first injection molding unit (31) and the second injection molding unit (32).

[0106] FIG. 8 is a schematic diagram showing an example of the configuration of a 6-station type blow molding device (30a) as another embodiment. FIG. 9 is a flowchart showing the process of a method for manufacturing a container in another embodiment. In addition, in the description of other embodiments below, redundant descriptions regarding elements similar to those in the above embodiments are appropriately omitted.

[0107] The blow molding device (30a) shown in FIG. 8 comprises a first injection molding unit (31), a temperature control unit (39) (first temperature control unit), a second injection molding unit (32), a temperature control unit (33) (second temperature control unit), a blow molding unit (34), an ejection unit (35), and a conveying mechanism (36). The first injection molding unit (31), the temperature control unit (39), the second injection molding unit (32), the temperature control unit (33), the blow molding unit (34), and the ejection unit (35) are arranged at positions rotated by a predetermined angle (e.g., 60 degrees) around the conveying mechanism (36).

[0108] The conveying mechanism (36) of the blow molding device (30a) is equipped with a conveying plate (36b) that rotates around an axis in the vertical direction of the ground in FIG. 8. The conveying plate (36b) conveys a preform (10) (or container (20)) in which the head portion is maintained by a neck shape in the order of the first injection molding section (31), the temperature control section (39), the second injection molding section (32), the temperature control section (33), the blow molding section (34), and the ejection section (35).

[0109] Additionally, the temperature control unit (39) has a configuration almost identical to that of the temperature control unit (33) and is equipped with a mold for temperature control (temperature control port or temperature control core) not shown. The temperature control unit (39) performs auxiliary heating or cooling of the first layer (11) by receiving the first layer (11) of the preform (10) conveyed from the first injection molding unit (32) into a mold unit maintained at a predetermined temperature.

[0110] As shown in FIG. 9, the method of manufacturing a container by a blow molding device (30a) of another embodiment differs from the manufacturing method of the embodiment shown in FIG. 6 in that a first temperature adjustment process (S101a) is performed between the first injection molding process (S101) and the second injection molding process (S102).

[0111] In the first temperature control process (S101a), the first layer (11) of the preform (10) is received in a temperature control mold unit in the temperature control unit (39), and cooling of the first layer (11) and adjustment of the temperature distribution (uniform temperature or removal of uneven temperature) are performed. At this time, heating of the first layer (11) may be performed in the temperature control unit (39) as needed.

[0112] After that, the transfer plate (36b) of the transfer mechanism (36) rotates at a predetermined angle, and the first layer (11) of the preform (10) held in the neck shape is transferred to the second injection molding section (33). Also, the other process of FIG. 9 is the same as the process of FIG. 6.

[0113] In addition, the embodiments disclosed herein should be considered as illustrative and not limiting in all respects. The scope of the invention is defined by the claims of the patent, rather than by the description above, and is intended to include all modifications within the meaning and scope of equivalents to the claims of the patent. Explanation of the symbols

[0114] 10: Preform 11: 1st layer 11a, 11b: Home 12: Second layer 13: Head 14: Torso 15 : Bottom 16 : Hole 18 : Thin film part 20 : Container 22: Body part 30: Blow molding device 31: 1st injection molding section 32: 2nd injection molding section 34: Blow molding section 37: First injection device 38 : Second injection device 50 : Cavity type 51 : Core type

Claims

Claim 1 A first injection molding process for injection molding a first layer of a bottomless, tubular preform having a groove extending in the axial direction using a first resin material; a second injection molding process for injecting a second resin material having a color different from that of the first resin material into the groove of the first layer and laminating a second layer on the inner circumference of the first layer; and a blow molding process for blow molding the multilayer preform obtained in the second injection molding process while maintaining heat during injection molding and manufacturing a resin container having a vertical striped color pattern formed by the second layer, wherein in the first injection molding process, the groove is formed on the inner circumference of the first layer using a first core mold having a groove formed therein, and in the second injection molding process, a cavity mold maintaining the shape of the first layer is disposed on the outer circumference of the first layer, and the second resin material is between the second core mold different from the first core mold and the groove of the first layer Method for manufacturing an injection-molded resin container. Claim 2 delete Claim 3 delete Claim 4 A method for manufacturing a resin container according to claim 1, wherein in the first injection molding process, a thin film portion is formed on a part of the first layer, and in the second injection molding process, the thin film portion is broken by the injection of the second resin material to guide the second resin material toward the inner circumference of the first layer. Claim 5 A method for manufacturing a resin container according to claim 1 or claim 4, wherein the first resin material and the second resin material are resin materials of the same type having different compositions of coloring agents. Claim 6 A manufacturing apparatus for a resin container having a first injection molding unit that injection molds a first layer of a bottomless tube-shaped preform having a groove extending in the axial direction using a first resin material, a second injection molding unit that injects a second resin material having a color different from that of the first resin material into the groove of the first layer and laminates a second layer on the inner circumference of the first layer, and a blow molding unit that blow molds the multilayer preform obtained from the second injection molding unit while maintaining heat during injection molding and manufactures a resin container having a vertical striped color shape by the second layer, wherein the first injection molding unit forms the groove on the inner circumference of the first layer using a first core mold having a groove formed therein, and the second injection molding unit places a cavity mold that maintains the shape of the first layer on the outer circumference of the first layer and injects the second resin material between a second core mold different from the first core mold and the groove of the first layer. Claim 7 delete Claim 8 A mold unit used in a manufacturing apparatus described in claim 6, comprising a first mold used in a first injection molding section for forming an outer layer of the preform, and a second mold used in a second injection molding section for laminating a bottom-shaped inner layer of the preform on the inner side of the outer layer, wherein the first mold comprises a first cavity mold that defines the outer circumference shape of the outer layer and a first core mold inserted into the first cavity mold and defines the inner circumference shape of the outer layer, and the second mold comprises a second cavity mold that receives the outer layer and holds the outer layer from the outside, and a second core mold that is inserted into the inner side of the outer layer and forms a mold space of the inner layer between the inner surface of the outer layer and defines the inner circumference shape of the inner layer, wherein a groove or protrusion extending in the axial direction is formed on the surface of the first core mold. Claim 9 The mold unit of claim 8 further comprises a neck type that is shared at least in the first injection molding section and the second injection molding section, and which grips a molded product of the first injection molding section and conveys it to the second injection molding section, wherein the first cavity mold and the second cavity mold each have a position regulating section that regulates the position of the neck type. Claim 10 A mold unit according to claim 9, further comprising a third mold having a position regulating part, which is used in a process of the manufacturing device different from the first injection molding part and the second injection molding part. Claim 11 In claim 10, the third mold is a mold unit that is a mold used in any of the temperature control unit for controlling the temperature of the preform or the molded product of the first injection molding part, the blow molding part, or the ejection part of the resin container.

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