Method for manufacturing a barrier-type container and a barrier-type food container

Abstract

This invention provides a method for manufacturing a barrier container and a barrier food container, which can be obtained by preventing the rupture of the barrier layer and the springback of the multilayer film, thereby providing a container with excellent barrier properties. [Solution] The preform forming process includes a bottom forming process in which a bottom member made of a multilayer film is formed into the shape of a container, and a body integration process in which the bottom member formed into the shape of a container and a body member made of a multilayer film are combined into a preform using a mandrel. In the bottom forming process, a circular plate-shaped bottom member 12 made of a multilayer film 5 is formed into the shape of a container using upper and lower molds 31 and 41.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a container having barrier properties against gases, water vapor, etc., and a food container having barrier properties.

Background Art

[0002] Examples of containers having barrier properties include cans, bottles, cups with aluminum foil inserts, cups with barrier films inserted on the sides and bottom, cups formed by thermoforming a barrier sheet, etc. However, when using metal, there are problems such as the inability to remove foreign substances by a metal detector. Also, in the case of a cup with a barrier film inserted on the sides and bottom, the barrier property deteriorates at the gap portion of the film, and there is a problem that discoloration is prominent in solid substances. Further, a cup formed by thermoforming a barrier sheet has a problem that thin portions are formed during molding and the barrier property is low.

[0003] Methods for manufacturing containers having barrier properties are disclosed in Patent Documents 1 and 2.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Generally, when a barrier film is heated and compressed using a top-and-bottom mold, as in vacuum forming, the barrier layer breaks, resulting in a significant decrease in barrier properties. Furthermore, when a multilayer film is removed from a mold without heat before the resin layer is formed, it springs back, making it difficult to optimize the shape of the multilayer film for the container. Additionally, even when using a barrier film, structurally, areas without barrier properties can occur during manufacturing, leading to problems such as partial discoloration and deterioration of the contents.

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a method for manufacturing a container with barrier properties and a food container with barrier properties, which can be obtained by preventing the rupture of the barrier layer and the springback of the multilayer film. [Means for solving the problem]

[0007] To achieve the above objective, this invention comprises the following embodiments.

[0008] 1) A method for manufacturing a barrier container by integrating a resin layer into a multilayer film having barrier properties against gases or water vapor, wherein the method includes a preform forming step in which the multilayer film is molded into the shape of a container before integrating the resin layer, the preform forming step includes a bottom forming step in which a bottom member made of the multilayer film is molded into the shape of the container, and a body integration step in which the bottom member molded into the shape of the container and a body member made of the multilayer film are combined into the preform using a mandrel, the bottom forming step in which a circular plate-shaped bottom member made of the multilayer film is molded into the shape of the bottom of the container using an upper and lower mold.

[0009] 2) The method for manufacturing a container having the barrier properties described in 1), wherein the bottom forming step comprises a first bottom forming step of forming the circular plate-shaped bottom member into a shape consisting of a circular plate-shaped main body and a rising portion rising from its outer peripheral edge using a first bottom forming upper and lower mold, and a second bottom forming step of bending the rising portion using a second bottom forming upper and lower mold to make it adhere closely to the main body, and the first upper and lower mold and the second upper and lower mold are each provided with heaters.

[0010] 3) The first lower mold for forming the bottom portion comprises a lower mold center that is movable vertically to receive the bottom member, a lower mold heater surrounding the lower mold center, and a lower spring that biases the lower mold center upward. The method for manufacturing a container having barrier properties as described in 2) above, wherein the first upper mold for forming the bottom comprises an upper mold center facing the lower mold center, with a downward projection at its lower end having a smaller diameter than the upper part, and an upper mold heater surrounding the upper mold center so as to cause the lower part of the upper mold center to protrude downward.

[0011] 4) The second lower mold for forming the bottom comprises a lower mold body, a lower mold center fixed to the upper end surface of the lower mold body and receiving the main body portion of the bottom member at its upper end surface, an outer lower mold portion arranged to surround the lower mold center and movable vertically relative to the lower mold center, a lower spring that biases the outer lower mold portion upward, and a lower mold heater located at the lower end of the lower mold body. The second upper mold for forming the bottom comprises an upper mold body that is movable vertically with respect to the upper mold central axis, an upper mold center fixed to the lower part of the upper mold central axis so as to surround the lower part of the upper mold central axis, an upper mold cylindrical part arranged so as to surround the upper mold central part and fixed to the lower end surface of the upper mold body, an upper mold outer part arranged so as to surround the lower end of the upper mold cylindrical part and movable vertically with respect to the upper mold cylindrical part, an upper mold inner spring that biases the upper mold center downward, an upper mold outer spring that biases the upper mold outer part downward, and an upper mold heater arranged at the lower end of the upper mold body so as to surround the upper mold central axis. A method for manufacturing a container having barrier properties as described in 2), wherein a tapered pressing portion is formed on the outer part of the upper mold to press against and tilt the rising portion of the bottom member, and the cylindrical part of the upper mold moves downward relative to the center of the upper mold to press against the tilted rising portion and bring it into close contact with the main body of the bottom member.

[0012] 5) The method for manufacturing a barrier container according to any one of 1) to 4) above, wherein the preform forming step comprises a flange forming step of forming a flange portion on the opening edge of the preform using upper and lower molds for preform forming.

[0013] 6) The lower mold for forming the preform comprises a lower mold central shaft portion that supports the bottom member of the preform from below, an elastic body fixed near the upper end of the lower mold central shaft portion and facing the opening edge of the preform from the inside, a lower mold main body portion that supports the elastic body, and a heater provided in the lower mold main body portion. The upper mold for forming the preform comprises an upper mold center that presses the bottom member of the preform from above, an upper mold outer part that presses the body of the preform from the outside, and a heater provided on the upper mold outer part, wherein the upper mold outer part is annular, and has a first tapered portion that supports the outer surface of the body of the preform and a second tapered portion that is connected to the lower end of the first tapered portion and faces the outer surface of the opening edge of the preform, the method for manufacturing a barrier container according to any one of 1) to 5) above.

[0014] 7) The lower mold for forming the preform comprises a lower mold center that supports the preform, a lower mold movable part fixed to the lower mold center and movable up and down, a lower mold outer part that guides the lower mold movable part, and a heater provided on the lower mold outer part. The upper die for forming the preform comprises an upper die center that presses the bottom member of the preform from above, an upper die outer part that presses the outer peripheral surface of the body member of the preform from the outside, an upper die main body that is fixed to the upper die center and the upper die outer part and is movable up and down, and a heater provided on the outer peripheral surface of the upper die outer part. The central part of the lower mold has a horizontal surface facing the bottom member of the preform, a tapered surface facing the inner circumferential surface of the body member of the preform, and a projection for forming a flange portion provided in conjunction with the tapered surface. A method for manufacturing a barrier container according to any one of 1) to 5) above, wherein the upper mold descends, resulting in a first state in which the bottom member of the preform, pressed by the center of the upper mold, is in close contact with the upper surface of the center of the lower mold; a second state in which the inner circumferential surface of the outer part of the upper mold contacts the tapered surface of the center of the lower mold via the body member of the preform; and a third state in which the flange-forming projection presses the opening edge of the body member of the preform, and by going through these three states, a flange portion shaped along the flange-forming projection of the center of the lower mold is formed on the preform.

[0015] 8) The method for manufacturing a barrier container according to any one of 1) to 7) above, wherein the resin layer forming step involves integrating the resin layer with the preform by injection molding using an injection molding die.

[0016] 9) The method for manufacturing a barrier container according to any one of 1) to 7) above, wherein the resin layer forming step involves integrating the resin layer with the preform by pressure molding using a pressure molding die.

[0017] 10) A method for manufacturing a barrier container according to any one of 1) to 9) above, comprising a heat retention step of keeping the preform warm at 70°C to 110°C before the resin layer formation step.

[0018] 11) A food container manufactured by the method for manufacturing a container having barrier properties according to any one of 1) to 10) above, wherein the multilayer film is composed of unstretched polypropylene (CPP) / barrier material / unstretched polypropylene (CPP), and the barrier material is any one of alumina vapor deposition, aluminum vapor deposition, and aluminum foil or a metal foil other than aluminum, a food container having barrier properties.

Effect of the Invention

[0019] According to the method for manufacturing a container having barrier properties of 1) above, it includes a preform forming step of forming a preform by shaping a multilayer film into the shape of a container, and the bottom forming step forms a circular plate-shaped bottom member made of a multilayer film into the shape of a container using an upper and lower mold, so that at the stage before resin molding, a preform that can prevent breakage of the barrier layer and springback of the multilayer film can be formed, and a container having barrier properties that solves the conventional problems can be manufactured.

[0020] According to the method for manufacturing a container having barrier properties of 2) above, the bottom forming step is divided into a first step and a second step, and heaters are provided in the first upper and lower mold and the second upper and lower mold respectively, so that springback of the multilayer film can be more reliably prevented, and a container having barrier properties that solves the conventional problems can be manufactured.

[0021] According to the method for manufacturing a container having barrier properties of 3) above, the device for performing the first bottom forming step can be made into a preferable configuration.

[0022] According to the method for manufacturing a container having barrier properties of 4) above, the device for performing the second bottom forming step can be made into a preferable configuration.

[0023] According to the method for manufacturing a container having barrier properties of 5) above, by forming a flange portion at the stage of shaping the preform, a container having barrier properties that solves the problems associated with forming a flange portion on the container can be manufactured.

[0024] According to the method for manufacturing a barrier container described in 6) above, the apparatus for performing the flange formation process can be configured in a preferred way.

[0025] According to the method for manufacturing a barrier-type container described in 7) above, the apparatus for performing the flange formation process can be configured in a preferred way without using an elastic body.

[0026] According to the method for manufacturing a barrier container described in 8) above, by forming a preform before resin molding and performing injection molding using a mold, it is possible to manufacture a barrier container that eliminates the conventional problems that occur during resin molding.

[0027] According to the method for manufacturing a barrier container described in 9) above, by forming a preform before resin molding and using pressure molding with a mold, it is possible to manufacture a barrier container that eliminates the conventional problems that occur during resin molding.

[0028] According to the method for manufacturing a barrier container described in 10) above, by warming the preform to 70-110°C in a constant temperature bath and then placing it in a mold for resin layer formation, the film becomes flexible, and the mold conformability during resin layer formation can be improved.

[0029] According to the barrier-type food container described in 11) above, by forming a preform before resin molding during manufacturing, it is possible to obtain a food container with excellent barrier properties that eliminates the conventional problems that occur during resin molding. [Brief explanation of the drawing]

[0030] [Figure 1] This is a cross-sectional view showing an example of a container obtained by the method for manufacturing a barrier-type container of this invention. [Figure 2] This figure shows the material shape used in the manufacturing method of a barrier container according to this invention. [Figure 3]This diagram schematically shows how the cross-sectional shape of the preform changes when manufactured using the barrier container manufacturing method of this invention. [Figure 4] This figure schematically shows the apparatus for the first bottom formation step to obtain the cross-sectional shape shown in Figure 3(a). [Figure 5] This figure shows an enlarged view of the main part of the apparatus for the first bottom formation process shown in Figure 4. [Figure 6] This figure schematically shows the apparatus for the second bottom formation step to obtain the cross-sectional shape shown in Figures 3(b) and 3(c). [Figure 7] This diagram schematically shows how the cross-sectional shape changes from that shown in Figure 3(a) to those shown in Figures 3(b) and 3(c) in the apparatus for the second bottom formation process. [Figure 8] This figure schematically shows the apparatus for the body integration process to obtain the cross-sectional shape shown in Figure 3(d), where (a) shows the initial state of the process, (b) shows the final state of the process, and (c) is an enlarged view of the part indicated by the dotted line in (b). [Figure 9] This figure schematically shows a first embodiment of a flange forming apparatus for obtaining the cross-sectional shape shown in Figure 3(e). [Figure 10] This figure schematically shows how the cross-sectional shape changes from that shown in Figure 3(d) to that shown in Figure 3(e) in the flange forming apparatus of the first embodiment. [Figure 11] This figure schematically shows a second embodiment of a flange forming apparatus for obtaining the cross-sectional shape shown in Figure 3(e). [Figure 12a] This diagram schematically shows how the cross-sectional shape changes from that shown in Figure 3(d) to that shown in Figure 3(e) in the flange forming apparatus of the second embodiment, and illustrates the state in which the center of the upper die is pressing against the bottom member of the preform. [Figure 12b] This figure shows the state after Figure 12a, where the outer part of the upper mold is pressing against the body member of the preform. [Figure 12c] This figure shows the state after Figure 12b, where the preform is aligned with the interlocking portion between the outer part of the upper mold and the center of the lower mold. [Figure 13]This figure compares the cross-sectional shape of the preform shown in Figure 8 with the cross-sectional shape of the preform inside the resin layer forming mold. [Figure 14] This figure schematically shows an example of the resin layer formation step, which is the final step in the manufacturing method of a barrier container according to this invention. [Figure 15] This figure schematically shows another example of the resin layer formation step, which is the final step in the manufacturing method of a barrier container according to this invention. [Modes for carrying out the invention]

[0031] A method for manufacturing a barrier-type container and a barrier-type food container according to an embodiment of this invention will be described below with reference to Figures 1 to 15.

[0032] Figure 1 shows an example of a food container obtained by the method for manufacturing a barrier container according to this invention. As shown in Figure 1, the food container (1) has a shape consisting of a body (2) with a flange (3) and a bottom (4), and a multilayer film (5) and a resin layer (6) are used as the materials to form these parts.

[0033] The multilayer film (5) is a multilayer film that has barrier properties against gases or water vapor, for example, CPP / barrier material / CPP. The outermost and innermost layers are not limited to CPP; other materials can be used as long as they are materials that can fuse with the injection resin and the films themselves (for example, heat-sealable OPP when the injection resin is PP). For the barrier material portion, a vapor-deposited film is used, but the most suitable barrier material can be used as appropriate depending on the required level of barrier protection and whether microwave compatibility is necessary. Examples of barrier materials include vapor-deposited PET, vapor-deposited PP, aluminum foil or other metal foils, light-shielding films, and EVOH. In addition, foamed PP or PE can be used to make the container easier to handle when the contents are heated. Furthermore, depending on the required application (for example, heat insulation to prevent burns when using a microwave or hot warmer), a multilayer structure of vapor-deposited PET with foamed PP or PE, or aluminum foil with foamed PP or PE may be used.

[0034] The present invention provides a method for manufacturing a barrier container, comprising a preform forming step (see Figures 2 to 13) in which a multilayer film (5) is formed into a preform (10) consisting of a body (2) with a flange portion (3) (or a body without a flange portion) and a bottom portion (4), and a resin layer forming step (see Figures 14 and 15) in which a resin layer (6) is formed on the preform (10) using a molding die (81) (82) (91).

[0035] The body (2) with flange portion (3) is formed from a fan-shaped body member (11) made of multilayer film as shown in Figure 2(a), and the bottom portion (4) is formed from a circular bottom member (12) made of multilayer film as shown in Figure 2(b). The hatched portion (11a) of the body member (11) indicates the portion that will be bonded during manufacturing, and the dashed line portion (12e) of the bottom member (12) indicates the portion that will be folded during manufacturing.

[0036] The manufacturing method of this container involves, as shown in Figure 3, a preform forming step: Figure 3(a): A step of forming a rising portion (12b) on the bottom member (12) shown in Figure 2 to form a bottom member (12) consisting of a main body (12a) and a rising portion (12b); Figure 3(b): A step of forming an inclined rising portion (12c) by folding back the rising portion (12b) of the bottom member (12) at a predetermined angle to form a bottom member consisting of a main body (12a) and an inclined rising portion (12c) that forms an acute angle with respect to the main body (12a). Figure 3(c): The process of folding back the inclined rising portion (12c) of the bottom member (12) to form a bottom member (12) consisting of a main body portion (12a) and a folded-back contact portion (12d) that is in close contact with the main body portion (12a); Figure 3(d): The process of joining the bottom member (12) with the folded-back contact portion (12d) and the cylindrical body member (11) to create a preform (10); and Figure 3(e): The process of forming a flange portion (13) on the opening edge of the preform (10).

[0037] Figure 4 shows the apparatus for the first step of forming the bottom of the bottom member (12) which forms the rising portion (12b) on the bottom member (12) shown in Figure 3(a). In Figure 4, the apparatus (20) for the first bottom forming process comprises a lower mold (21) fixed to a base (not shown) and an upper mold (23) supported by the base so as to be vertically movable relative to the lower mold (21). The lower mold (21) has a lower mold center (22) that supports the bottom member (12) and is movable up and down, and the upper mold (23) has an upper mold center (24) that faces the lower mold center (22).

[0038] The lower end of the upper mold center (24) is provided with a downward projection (24a) whose diameter is smaller than the upper part by the thickness of the bottom member (12). The upper mold (23) is provided with an upper mold heater (25) that surrounds the upper mold center (24) so ​​that the lower part of the upper mold center (24) protrudes downward.

[0039] The lower mold center (22) has an outer diameter smaller than the outer diameter of the bottom member (12), and can receive the portion of the bottom member (12) excluding the outer peripheral edge (the portion of the bottom member (12) inside the dashed line portion (12e) in Figure 2). The lower mold center (22) is biased upward by a lower spring (27) provided on the lower mold (21) and is configured to receive the lower end of the upper mold center (24) via the bottom member (12). The lower mold (21) is provided with a lower mold heater (26) that surrounds the lower mold center (22).

[0040] In the first bottom forming step using the bottom forming first step apparatus (20), first, a circular bottom member (12) (see Figure 2(b)) is set in the lower mold (21) as shown in Figure 4(a) at the center of the lower mold (22), and then the upper mold (23) is lowered. As a result, the center of the upper mold (24) comes into contact with the bottom member (12) supported by the center of the lower mold (22), and further lowering the upper mold (23) compresses the spring (27) that is biasing the center of the lower mold (22) as shown in Figure 4(b), causing the center of the lower mold (22) to descend downward. As a result, the outer peripheral edge of the circular bottom member (12) (the part outside the dashed line (12a) in Figure 2(b)) is bent along the downward projection (24a), forming a bottom member (12) with a raised portion (12b) at the outer peripheral edge.

[0041] In the above, the upper and lower molds (21) and (23) that form the rising portion (12b) on the bottom member (12) are made of aluminum and are cold-drawn molds (a molding process in which the material is allowed to flow into the mold without the male and female molds holding it in place during press work). Heaters (25) and (26) are installed inside the upper and lower molds (21) and (23) to prevent springback, and by applying a constant temperature to melt the CPP surface of the multilayer film (5), the concave shape with the rising portion (12b) is maintained.

[0042] In the bottom forming first step apparatus (20) described above, regarding the clearance (C) between the lower projection (24a) of the upper die center (24) shown in Figure 5 and the recess (21a) of the lower die (21) that receives it, there is a narrow gap at the corner portion of the outer peripheral rise portion (up to the corner R rise portion) (C1). For this portion (C1), considering wrinkles, it is best to provide a clearance of twice the thickness of the multilayer film (92 μm in this embodiment), and it is desirable to make it 1 to 3 times the thickness of the multilayer film. Furthermore, for the portion above the corner, damage to the multilayer film (5) can be reduced by making the outer peripheral surface (24b) of the lower projection (24a) of the upper die center (24) a reverse taper from a right angle to -10 degrees. By providing the above clearance and reverse taper, the multilayer film (5) can be molded without stretching, thereby preventing the multilayer film (5) from breaking and ensuring barrier properties.

[0043] Figure 6 shows a bottom forming second step apparatus (30) for forming the inclined rising portion (12c) shown in Figure 3(b) and the folded-over adhesive portion (12d) shown in Figure 3(c) on the bottom member (12) which has a rising portion (12b) formed by the bottom forming first step.

[0044] In Figure 6, the apparatus (30) for the second bottom forming process comprises a lower mold (31) fixed to a base (not shown) and an upper mold (41) supported by the base so as to be vertically movable relative to the lower mold (31).

[0045] The lower mold (31) comprises a lower mold body (32), a lower mold center (33) fixed to the upper end surface of the lower mold body (32), a lower mold outer part (34) arranged to surround the lower mold center (33), a lower spring (35) that biases the lower mold outer part (34) upward, and a lower mold heater (36) positioned at the upper end of the lower mold body (32) so as to be able to heat the lower mold center (33) from the lower end surface side.

[0046] The inner peripheral edge of the lower mold outer part (34) has an inner diameter approximately equal to the outer diameter of the main body (12a) of the bottom member (12), and the upper end surface (33a) of the lower mold center (33) is lower than the upper end surface (34a) of the lower mold outer part (34) by about half the height of the rising portion (12b) of the bottom member (12). Therefore, by supporting the bottom member (12) with the inner peripheral edge of the lower mold outer part (34) and pushing the main body (12a) of the bottom member (12) downward, the main body (12a) of the bottom member (12) can move downward until it is received by the upper end surface (33a) of the lower mold center (33). There is a gap between the lower end surface (34b) of the lower mold outer part (34) and the upper end surface (32a) of the lower mold body (32), and the lower mold outer part (34) is movable up and down relative to the lower mold center (33). Therefore, when a downward force is applied to the lower mold outer part (34), the lower mold outer part (34) can move downward by compressing the lower spring (35).

[0047] The upper mold (41) comprises a cylindrical upper mold body (43) that is movable vertically relative to the upper mold central shaft (42), a cylindrical upper mold center (44) fixed to the lower part of the upper mold central shaft (42) so as to surround the lower part of the upper mold central shaft (42), an upper mold cylindrical part (45) arranged so as to surround the upper mold center (44) and fixed to the lower end surface of the upper mold body (43), and an upper mold cylindrical part (45) arranged so as to surround the lower end of the upper mold cylindrical part (45) The upper mold includes an annular upper mold outer part (46) that is movable up and down relative to the upper mold cylindrical part (45), an annular upper mold inner spring (inner elastic member) (47) that biases the upper mold central part (44) downward, an annular upper mold outer spring (outer elastic member) (48) that biases the upper mold outer part (46) downward, and an upper mold heater (49) that is positioned at the lower end of the upper mold body (43) so as to surround the upper mold central shaft part (42).

[0048] The outer diameter of the upper mold center (44) is approximately equal to the inner diameter of the rising portion (12b) of the bottom member (12), so that the upper mold cylindrical portion (45) faces the rising portion (12b) of the bottom member (12). A tapered pressing portion (50) is formed at the lower inner corner of the outer part (46) of the upper mold, which, when the upper mold (41) descends, comes into contact with the rising portion (12b) of the bottom member (12), pressing it inward and causing it to tilt.

[0049] The upper mold inner spring (47) of the upper mold (41) is supported at its upper end by the lower end surface (43a) of the upper mold body (43) and at its lower end by a spring receiving surface (44a) provided at the lower end of the upper mold center (44). As a result, when an upward force acts on the lower end surface of the upper mold center (44), the upper mold inner spring (47) is compressed, and the upper mold central shaft (42) and the lower end surface of the upper mold center (44) can move upward relative to the upper mold body (43). The upper outer spring (48) of the upper mold (41) is supported at its upper end by an upper spring support portion (43b) provided on the upper mold body (43), and at its lower end by a lower spring support portion (46a) provided on the upper end of the upper outer part (46). As a result, when an upward force acts on the lower surface of the upper outer part (46), the upper outer spring (48) is compressed, allowing the upper outer part (46) to move upward. If the upper outer part (46) does not move upward, the downward force on the upper outer part (46) increases.

[0050] The outer part of the upper mold (46) is biased by the outer spring of the upper mold (48) and is movable up and down relative to the upper mold body (43). The cylindrical part of the upper mold (45) is fixed to the upper mold body (43). Therefore, even when the outer part of the upper mold (46) moves up and down relative to the upper mold body (43), the cylindrical part does not move together with the outer part of the upper mold (46), and can move up and down relative to the central part of the upper mold (44).

[0051] In the second bottom forming step, first, as shown in Figure 6, the bottom member (12) with the rising portion (12b) formed in the first molding step is set in the lower mold (31).

[0052] When the upper mold body (43) is lowered in this state, the upper mold central axis (42) and the upper mold center (44) first come into contact with the lower mold center (33) via the main body (12a) of the bottom member (12). As a result, the bottom member (12) is fixed between the lower end surface of the upper mold center (44) and the upper end surface of the lower mold center (33). In this state, there is still a gap between the lower mold outer part (34) and the upper mold outer part (46).

[0053] When the upper mold body (43) is lowered further, the upper mold inner spring (47) compresses, causing the upper mold outer part (46) to descend. As a result, as shown in Figure 7(a), the upper mold outer part (46) comes into contact with the lower mold outer part (34), and the upper end portion of the rising part (12b) of the bottom member (12) tilts slightly inward along the tapered pressing part (50).

[0054] When the upper mold body (43) is lowered further from the state shown in Figure 7(a), as shown in Figure 7(b), the outer part of the upper mold (46) presses against the outer part of the lower mold (34), compressing the lower spring (35), and moves downward together with the outer part of the lower mold (34). As a result, the rising part (12b) of the bottom member (12) tilts further inward along the tapered pressing part (50), resulting in the bottom member (12) with the inclined rising part (12c) shown in Figure 3(b).

[0055] In Figure 7(b), there is a gap between the lower end surface of the upper cylinder portion (45) and the main body portion (12) of the bottom member (12) on the lower center portion (33). Therefore, when the upper body (43) is lowered further, the upper central shaft portion (42) that is in contact with the main body portion (12) of the bottom member (12) maintains its position, further compressing the upper inner spring (47), and the upper cylinder portion (45) descends together with the upper body (43).

[0056] As a result, as shown in Figure 7(c), the lower end surface of the upper cylindrical portion (45) presses against the inclined rising portion (12c) of the bottom member (12), causing the inclined rising portion (12c) to adhere closely to the main body portion (12), and a bottom member (12) with a folded-over adhesive portion (12d) as shown in Figure 3(c) is obtained.

[0057] The rising portion (12b) of the bottom member (12) is approximately 45-90° after the first bottom forming process, and the lower die center (33) is provided with an 80-90° taper so that the rising portion (12b) is corrected to 80-90° when set in the bottom forming second process device (30). The pressing portion (50) has a taper of 5-20°. The lower die center (33), upper die center (44), and upper die cylindrical portion (45) are heated to the appropriate sealing temperature (120-200°C) for the multilayer film (5) by the lower die heater (36) and upper die heater (49), respectively, and the entire circumference of the bottom member (12) is fused in a folded state. If the folded portion is not sufficiently tightly bonded at this point, it can be completely folded by applying heat and pressure in the third molding process device, but if it is sufficiently fused in the second process, the third process may be omitted.

[0058] The upper and lower molds (21), (23), (31), and (41) of the above bottom forming first and second process apparatus (20) and (30) are molds for cold drawing, and the raising and lowering of the molds is performed by a press machine. The drive source for the press machine is, for example, a servo motor, but since a clamping force of 200 kg is sufficient and complex adjustment of the lowering speed is not required, the drive source can be any of a hydraulic cylinder, servo motor, or air cylinder. The molds are designed so that the upper and lower centers come into contact first, and then the outer circumference rises when the mold closes. Because the above multilayer film does not have dead-hold properties, even if the shape is matched with a mold, it will return to almost flat the moment it is released. For this reason, heaters (cartridge heaters) (25), (36), (26), and (49) are provided in the lower molds (21) and (31) and upper molds (23) and (41) to maintain the shape of the bottom member (12). The heater temperature should ideally be between 80°C and 150°C, but if it's too high, deformation in the next process will be suppressed. Therefore, around 100°C is most preferable.

[0059] The body integration process is carried out using a metal mandrel (51) as a molding die and a sealing plate (52) for sealing the bottom member (12) obtained in the molding process and the cylindrical body member (11), as shown in Figure 8.

[0060] As shown in Figure 2(a), the body member can be formed by trimming a multilayer film (5) into a fan shape, folding one of the straight sections on the left or right of the fan shape and welding the end face, wrapping this around a mandrel (51), and further welding the overlapping portions of the left and right vertical sections. It is preferable to trim the lower side of the fan-shaped body member (11) to extend it by 2 to 6 mm beyond the side length in order to join it with the bottom member (12).

[0061] As shown in Figure 8(a), the bottom member (bottom member with the folded-over adhesive portion (12d) shown in Figure 3(c)) (12) is first set on the mandrel (51), then the body member (see Figure 2(a)) is wrapped around it in a cylindrical shape and set, and then, as shown in Figures 8(b) and (c), the sealing plate (52) is used to fold the adhesive portion of the body member (11) and weld it to the bottom member (12). At this time, by extending the sealing plate (52) to the shoulder portion, the ability to follow the mold (81)(82)(91) during the resin layer formation in the next process is improved.

[0062] Regarding this wrap-around shape (52a), it is not necessary to perfectly match the shape of the molds (81), (82), and (91) used in subsequent processes. Making it larger (R1 to R5) than the corner radius of the molds (81), (82), and (91) results in less damage to the multilayer film (5) and yields better results. In this specification, this welded molded product is called a preform (10), and the edges of the multilayer film (5) used for the bottom member (12) and body member (11) are all folded or molded to be on the outside of the preform (10) so that they do not come into contact with the contents (to prevent the adhesive from leaching out).

[0063] While sealing plates (52) are usually flat, by providing a wrap-around shape (52a) on the sealing plate (52) and sealing it so that it wraps around to match the corner shape of the mandrel (51), it is possible to create a preform (10) that conforms more closely to the injection molding die (81)(82).

[0064] The manufacturing method of this container (1) further includes a flange molding step using the flange molding apparatus (60) of the first embodiment, as shown in Figures 9 and 10, as a preform forming step. As shown in Figure 9, the flange forming apparatus (60) of the first embodiment includes a lower mold (62) and an upper mold (63) supported on a base (61).

[0065] The lower mold (62) comprises a lower mold central shaft (71) that supports the bottom member (12) of the preform (10) from below, a silicone rubber (elastic body) (72) fixed near the upper end of the lower mold central shaft (71) and facing the opening edge of the body member (11) of the preform (10) from the inside, a lower mold body (73) that supports the silicone rubber (72), and a heater (74) fixed to the lower surface of the lower mold body (73). The lower mold (62) is supported by a lower mold support (64) fixed to the lower part of the base (61).

[0066] The upper mold (63) is fixed to a rectangular frame (66) which is moved up and down by a hydraulic cylinder (65) provided at the upper end of the base (61). The upper die (63) comprises an upper die center (76) that presses the bottom member (12) of the preform (10) from above, an upper die outer part (77) that presses the outer circumferential surface of the body member (11) of the preform (10) from the outside, and a heater (78) fixed to the outer circumferential surface of the upper die outer part (77). The upper die outer part (77) is annular in shape, and its inner circumferential edge has a first tapered portion (77a) that supports the outer circumferential surface of the body member (11) of the preform (10), and a second tapered portion (77b) that is connected to the lower end of the first tapered portion (77a) and faces the outer circumferential surface of the opening edge of the body member (11) of the preform (10). The taper angle of the second tapered portion (77b) is greater than the taper angle of the first tapered portion (77a). The upper mold center (76) is supported by the upper surface of the peripheral edge of a through hole (66a) provided in the center of the lower end of the frame (66), and the upper mold outer part (77) is supported by the lower surface of the peripheral edge of the same through hole (66a).

[0067] When the hydraulic cylinder (65) is driven to lower the upper mold (63) from the state shown in Figure 9, first the bottom member (12) is pressed, as shown in Figure 10(a), and then the outer surface of the body member (11) of the preform (10) is pressed as the upper mold (63) lowers. As a result, as shown in Figure 10(b), the silicone rubber (72) is crushed and expands, and the opening edge of the body member (11) of the preform (10) expands in accordance with the silicone rubber (72), forming a flange portion (13) (see Figure 3(e)).

[0068] If the opening edge of the body member (11) of the preform (10) is simply widened, the preform (10) will return to its original shape due to its elasticity. Therefore, the preform (10) is widened while applying heat of 75°C to 130°C using heaters (e.g., plate heaters) (74) (78) installed in the lower mold (62) and upper mold (63), respectively. This causes the preform (10) to be held in that state. The preferred temperature for the heaters (74) (78) is around 110°C. At this time, the elongation rate of the preform (10) is 10% or less. If the elongation rate is 10% or less, the preform (10) will not break and its barrier properties will not be reduced.

[0069] The manufacturing method of this container (1) also allows for the omission of the above-mentioned silicone rubber (elastic body) (72) in the preform formation step. Figures 11 and 12(a), (b), and (c) show a flange molding apparatus (70) of a second embodiment that performs the flange molding step. As shown in Figure 11, the flange forming apparatus (70) of the second embodiment includes a lower mold (102) supported on a base (101) and an upper mold (103) that can move up and down relative to the base (101).

[0070] The lower mold (102) comprises a lower mold center (111) that supports the preform (10), a lower mold movable part (112) whose upper surface is fixed to the lower surface of the lower mold center (111), an annular lower mold outer part (113) fixed to the upper surface of the base (101) so as to surround the lower mold movable part (112), a pair of fixed guide shafts (114) fixed to the base (101) and guiding the lower mold movable part (112) to move up and down, a heater (115) fixed to the outer circumferential surface of the lower mold outer part (113), a thermocouple (116) for measuring the temperature of the lower mold movable part (112), and a thermocouple (117) for measuring the temperature of the lower mold outer part (113).

[0071] The lower mold center (111) has a horizontal surface (111a) facing the bottom member (12) of the preform (10), a tapered surface (111b) facing the inner circumferential surface of the body member (11) of the preform (10), and a vertical surface (111d) connected to the tapered surface (111b) via an arcuate surface (111c) and projecting outward beyond the extension of the tapered surface (111b). The arcuate surface (111c) and the vertical surface (111d) form a flange-forming projection (118) for forming a flange on the outer circumferential edge of the body member (11) of the preform (10).

[0072] A gap (G1) exists between the lower surface of the lower mold movable part (112) and the upper surface of the base (101), and the lower mold central part (111) is able to move up and down together with the lower mold movable part (112), which moves up and down guided by the lower mold outer part (113) and a pair of fixed guide shafts (114). The lower mold movable part (112) is provided with a gap (G2) to avoid interference with the thermocouple (116) when the lower mold movable part (112) moves up and down.

[0073] The upper mold (103) comprises an upper mold center (121) that presses the bottom member (12) of the preform (10) from above, an upper mold outer part (122) that presses the outer peripheral surface of the body member (11) of the preform (10) from the outside, an upper mold body (123) to which the upper mold center (121) and the upper mold outer part (122) are fixed, a pair of fixed guide shafts (124) that guide the upper mold body (123) to move up and down, a heater (125) fixed to the outer peripheral surface of the upper mold outer part (122), and a thermocouple (126) for measuring the temperature of the upper mold outer part (122).

[0074] The outer part of the upper mold (122) is annular, and its inner circumferential surface (122a) is a tapered surface facing the outer circumferential surface of the body member (11) of the preform (10). The main body of the upper mold (123) consists of a large diameter portion (123a) and a small diameter portion (123b) that protrudes downward from the lower surface of the central part of the large diameter portion (123a). The upper surface of the central part of the upper mold (121) is fixed to the lower surface of the small diameter portion (123b), and the upper end of the outer part of the upper mold (122) is fixed to the lower surface of the outer part of the large diameter portion (123a) and the outer circumferential edge of the small diameter portion (123b).

[0075] When the upper mold (103) is lowered from the initial state shown in Figure 11, first, as shown in Figure 12a, the bottom member (12) of the preform (10), which is pressed by the center of the upper mold (121), comes into close contact with the upper surface of the center of the lower mold (111).

[0076] Furthermore, as the upper die (103) descends, the body member (11) of the preform (10) is pressed against the outer part (122) of the upper die. As a result, the inner circumferential surface (122a) of the outer part (122) of the upper die comes into contact with the tapered surface (111b) of the center of the lower die (111) via the body member (11) of the preform (10). That is, the preform (10) takes on a shape that conforms to the inner circumferential surface (122a) of the outer part (122) of the upper die and the tapered surface (111b) of the center of the lower die (111) (second state). At this point, as shown in Figure 12b, there is a gap (G3) between the lower surface of the outer part (122) of the upper die and the upper surface of the outer part (113) of the lower die, which is the same size as the gap (G1) mentioned above. Here, the clearance between the inner circumferential surface (122a) of the outer part (122) of the upper mold and the tapered surface (111b) of the central part (111) of the lower mold is, for example, 0.2 mm. This clearance can be changed between 0.15 mm and 0.5 mm, and in this embodiment, it is set to 0.2 mm because a narrower clearance results in better vertical wrinkle formation (thinner wrinkles) of the body member (11) of the preform (10).

[0077] When the upper mold (103) is lowered further from the state shown in Figure 12b, the entire upper mold (103) and the lower mold center (111) and lower mold movable part (112) of the lower mold (102) move downward by the amount of the gaps (G1) and (G3). As a result, the entire inner circumferential surface (122a) of the outer part (122) of the upper mold and the entire outer circumferential surface of the lower mold center (111) come into contact with the body member (11) of the preform (10), and the flange-forming projection (118) presses against the opening edge of the body member (11) of the preform (10). As a result, a flange portion is formed on the preform (10) in the shape of the flange-forming projection (118) of the lower mold center (111) (third state).

[0078] In this second embodiment as well, simply pressing the opening edge of the body member (11) of the preform (10) with the flange-forming projection (118) would cause the preform (10) to return to its original shape due to its elasticity. Therefore, heat is applied by heaters (115) and (125) installed on the lower mold outer part (113) and the upper mold outer part (122), respectively. The temperature is set to 80°C for both the lower mold outer part (113) and the upper mold outer part (122). This causes the preform (10) to be maintained in that state. If the temperature is too high (for example, 110°C), the surface will melt, and if the temperature is too low, the shape cannot be maintained. Therefore, the preferred temperature during molding is in the range of 60°C to 100°C. Since the preform (10) molded in the manner described above is approximately the same size as the resin layer forming mold (M) described later, when the preform (10) is inserted into the resin layer forming mold (M) and injection resin is poured, defects such as the preform (10) being exposed on the side of the body or misalignment of the flange top surface are less likely to occur.

[0079] Figure 13 shows the shapes of the resin layer forming mold (M) and the preform (10). In Figure 13, the container (1) is defined by the shape of the resin molding die (M). The preform (10) obtained in the body integration process is defined by the shape of the mandrel (51). The portion of the preform (10) outside the point where the line representing the container (1) and the line representing the preform (10) intersect will stretch slightly during molding. It is possible to omit the flange molding process and proceed directly to the resin molding process, but by pre-expanding only the opening edge of the preform (10) with the flange molding device (60), the conformability to the shape of the resin molding die (M) (flange during injection molding) can be improved.

[0080] The resin layer formation process can be carried out by the method shown in Figure 14 or Figure 15.

[0081] Figure 14 shows the resin layer formation process, in which a resin layer (6) is integrated into the preform (10) by injection molding using injection molding dies (81) and (82). In Figure 14, a preform (10) is placed in the core-side mold (81), and a fan-shaped body label (83), printed as needed, is placed in the cavity-side mold (82). By injecting resin within the molds (81) and (82), a food container (1) (see Figure 1) is obtained that has barrier properties (on the inside) and is decorated on the body (2).

[0082] In the resin layer formation process described above, it is preferable to pre-form the preform (10) using a cold forming die and temperature control within the die before placing it in the injection molds (81) and (82) to bring it to a state close to the container shape of the injection molds (81) and (82) (flange and body shapes). Specifically, the preform (10) itself is kept warm at 70 to 110°C, and the warmed preform (10) is placed in the injection molds (injection male mold (81) and female mold (82)), and the flange and body shapes are molded together with the injection resin to the container shape inside the injection molds (81) and (82) by the injection pressure of the resin. Furthermore, since the lid film and the end face of the inserted preform (10) are bonded together during the lid peeling process, there is a risk that the lid film may peel off from the injection container. Therefore, it is preferable to design the mold shape and dimensions so that a step is provided on the inside of the flange so that the end face of the preform (10) is embedded in the injection resin.

[0083] The film inserted as the body label (83) can be the same as that commonly used for in-mold molding (e.g., OPP / HSOPP). In addition, since there is a risk of burns when handling heated objects during the resin layer formation process, it is also possible to further laminate with a foamed sheet of PE or PP that has an insulating effect. The body label (83) placed outside the resin layer (6) can be omitted, but printing on the body label (83) results in a food container (1) with superior aesthetic appeal.

[0084] In the resin layer formation process, instead of injection molding, the resin layer (6) can also be formed by pressure molding, for example, as shown in Figure 15. In Figure 15, a pre-formed (flange-formed) preform (10) is placed in a pressure molding die (91), and by applying a vacuum, it is made to conform to the die (91). Then, the sheet-like resin layer (6), which has been heated from above to a semi-molten state, is pressure-molded and integrated to obtain a food container (1) (see Figure 1) with barrier properties. According to this resin layer formation process, by pressing the resin layer (6) onto the preform (10) using air molding, a food container (1) with higher barrier properties than a typical sheet-molded container (a container in which a barrier material such as EVOH is co-pressed between sheets) can be obtained.

[0085] During pressure molding, air pockets tend to form between the preform (10) and the sheet (resin layer) (6) when pressure is applied. Therefore, it is preferable to make intermittent slits (10a) 2 to 5 mm away from the inside of the flange portion of the pre-molded preform (10), and to draw out the air that accumulates during molding by creating a vacuum through the slits (10a) via a vacuum hole (91a) provided in the mold (91). Barrier performance is ensured inside the slits (10a), resulting in a barrier food container (1). The slits (10a) may be trimmed if sealing performance can be ensured.

[0086] In a container manufactured using the above-described method for manufacturing barrier containers (a 110cc food container with a diameter of 71φ using a multilayer film with alumina deposition as a preform (1)), the oxygen permeability was 0.46 cm². 3 / (m 2 A value of (24h·atm) was obtained. In a typical aluminum-free barrier cup, 3.0cm 3 / (m 2 (24h·atm), and compared to this, better results were obtained.

[0087] Regarding the product shape of the food container (1), it is desirable to design it so that there are as few irregularities as possible on the inside surface that forms the barrier film. Also, since wrinkles occur on the inner surface due to abrupt angle changes from the bottom to the side and from the side to the flange, the angle changes need to be made gradual. In addition, although the corner radius is usually offset, increasing the offset radius of the smaller radius to +5 to 50% will prevent exposure to the surface. The product wall thickness should preferably be 5 to 20 times the thickness of the multilayer film.

[0088] Furthermore, if the end face of the multilayer film (5) and the top film are strongly bonded, the adhesive strength between the resin layer (6) and the layers of the multilayer film (5) may be insufficient, potentially causing peeling. Therefore, the seal with the top film must be designed to make strong contact with the resin layer (6). It is possible to further reduce peeling by removing the flange surface only at the end to prevent contact. However, to ensure sufficient barrier properties, it is desirable to secure a flange overlap width of 1 mm or more for the multilayer film (5). [Industrial applicability]

[0089] This invention relates to a method for manufacturing a barrier container by integrating a resin layer into a multilayer film that has barrier properties against gases or water vapor, and is suitably used in the manufacture of food containers with excellent barrier properties. [Explanation of Symbols]

[0090] (1): Food containers (2): Torso (3): Flange section (4):Bottom (5): Multilayer film (6): Resin layer (10): Preform (10a): Flange section (11): Body part (12):Bottom member (12a): Main body (12b): Rising section (12c): Inclined rising section (12d): Folded-over, tightly sealed section (20):Equipment for the first step of bottom formation (21): Lower mold (22): Center of lower mold (23): Upper mold (24): Upper mold center (24a):Downward protrusion (25): Heater (26): Heater (27): Spring (30): Bottom forming second step equipment (31):Lower mold (32): Lower body (33): Center of lower mold (34): Lower mold outer part (35): Lower spring (36): Heater (41): Upper mold (42): Upper mold center shaft part (43): Upper body (44): Upper mold center (45): Upper cylindrical section (46): Upper mold outer part (47): Upper mold inner spring (48): Upper outer spring (49): Heater (50): Pressing part (60): Flange forming apparatus (62): Lower mold (63): Upper mold (71): Lower mold center shaft part (72): Silicone rubber (elastic material) (73): Lower mold body (74): Heater (76): Upper mold center (77): Upper mold outer part (78): Heater (77a): First tapered section (77b): Second tapered section (70): Flange forming apparatus (102): Lower mold (103): Upper mold (111): Lower mold center (111a):Horizontal plane (111b): Tapered surface (112): Lower mold movable part (113): Lower mold outer part (115): Heater (118): Protrusion for forming flange portion (121): Upper mold center (122): Upper mold outer part (122a):Inner surface (123): Upper body section (125): Heater

Claims

1. In a method for manufacturing a barrier container by integrating a resin layer into a multilayer film that has barrier properties against gases or water vapor, The process includes a preform forming step in which the multilayer film is molded into the shape of a container before the resin layer is integrated. The preform forming process comprises a bottom forming step of forming the bottom member made of the multilayer film into the shape of the container, and a body integrating step of forming the preform by using a mandrel to combine the bottom member formed into the shape of the container and the body member made of the multilayer film. A method for manufacturing a container having barrier properties, wherein in the bottom forming step, a circular plate-shaped bottom member made of the multilayer film is formed into the bottom shape of the container using upper and lower molds.

2. The method for manufacturing a barrier container according to claim 1, wherein the bottom forming step comprises a first bottom forming step of shaping the circular plate-shaped bottom member using a first bottom forming upper and lower mold to form a circular plate-shaped main body and a rising portion rising from its outer peripheral edge, and a second bottom forming step of bending the rising portion using a second bottom forming upper and lower mold to make it adhere to the main body, and the first upper and lower mold and the second upper and lower mold are each provided with heaters.

3. The first lower mold for forming the bottom portion comprises a lower mold center that is movable vertically to receive the bottom member, a lower mold heater surrounding the lower mold center, and a lower spring that biases the lower mold center upward. The method for manufacturing a barrier container according to claim 2, wherein the first upper mold for forming the bottom comprises an upper mold center facing the lower mold center, having a downward projection at its lower end that is smaller in diameter than the portion above it, and an upper mold heater surrounding the upper mold center such that the lower part of the upper mold center protrudes downward.

4. The second lower mold for forming the bottom comprises a lower mold body, a lower mold center fixed to the upper end surface of the lower mold body and receiving the main body portion of the bottom member at its upper end surface, an outer lower mold portion arranged to surround the lower mold center and movable vertically relative to the lower mold center, a lower spring that biases the outer lower mold portion upward, and a lower mold heater arranged in the lower mold body so as to be able to heat the lower mold center. The second upper mold for forming the bottom comprises an upper mold body that is movable vertically with respect to the upper mold central axis, an upper mold center fixed to the lower part of the upper mold central axis so as to surround the lower part of the upper mold central axis, an upper mold cylindrical part arranged so as to surround the upper mold central part and fixed to the lower end surface of the upper mold body, an upper mold outer part arranged so as to surround the lower end of the upper mold cylindrical part and movable vertically with respect to the upper mold cylindrical part, an upper mold inner spring that biases the upper mold center downward, an upper mold outer spring that biases the upper mold outer part downward, and an upper mold heater arranged at the lower end of the upper mold body so as to surround the upper mold central axis. A method for manufacturing a barrier container according to claim 2, wherein a tapered pressing portion is formed on the outer part of the upper mold to press and tilt the rising portion of the bottom member, and the cylindrical part of the upper mold moves downward relative to the center of the upper mold to press the tilted rising portion and bring it into close contact with the main body of the bottom member.

5. The method for manufacturing a barrier container according to any one of claims 1 to 4, wherein the preform forming step comprises a flange forming step of forming a flange portion on the opening edge of the preform using upper and lower molds for preform forming.

6. The lower die for forming the preform comprises a lower die central shaft portion that supports the bottom member of the preform from below, an elastic body fixed near the upper end of the lower die central shaft portion and facing the opening edge of the preform from the inside, a lower die main body portion that supports the elastic body, and a heater provided in the lower die main body portion. The upper mold for forming the preform comprises an upper mold center that presses the bottom member of the preform from above, an upper mold outer part that presses the body of the preform from the outside, and a heater provided on the upper mold outer part, wherein the upper mold outer part is annular, and has a first tapered portion that supports the outer surface of the body of the preform and a second tapered portion that is connected to the lower end of the first tapered portion and faces the outer surface of the opening edge of the preform, the method for manufacturing a barrier container according to any one of claims 1 to 5.

7. The lower die for forming the preform comprises a lower die center that supports the preform, a lower die movable part fixed to the lower die center and movable up and down, a lower die outer part that guides the lower die movable part, and a heater provided on the lower die outer part. The upper die for forming the preform comprises an upper die center that presses the bottom member of the preform from above, an upper die outer part that presses the outer peripheral surface of the body member of the preform from the outside, an upper die main body that is fixed to the upper die center and the upper die outer part and is movable up and down, and a heater provided on the outer peripheral surface of the upper die outer part. The central part of the lower mold has a horizontal surface facing the bottom member of the preform, a tapered surface facing the inner circumferential surface of the body member of the preform, and a projection for forming a flange portion provided in conjunction with the tapered surface. A method for manufacturing a barrier container according to any one of claims 1 to 5, wherein the upper mold descends, resulting in a first state in which the bottom member of the preform, pressed by the center of the upper mold, is in close contact with the upper surface of the center of the lower mold; a second state in which the inner circumferential surface of the outer part of the upper mold contacts the tapered surface of the center of the lower mold via the body member of the preform; and a third state in which the flange-forming projection presses against the opening edge of the body member of the preform, and a flange portion having a shape along the flange-forming projection of the center of the lower mold is formed on the preform by going through these three states, wherein a flange portion has a shape along the flange-forming projection of the center of the lower mold.

8. The method for manufacturing a barrier container according to any one of claims 1 to 7, wherein the resin layer formation step involves integrating the resin layer with the preform by injection molding using an injection molding die.

9. The method for manufacturing a barrier container according to any one of claims 1 to 7, wherein the resin layer formation step involves integrating the resin layer with the preform by pressure molding using a pressure molding die.

10. A method for manufacturing a barrier container according to claim 8 or 9, comprising a heat retention step of maintaining the preform at 70°C to 110°C before the resin layer formation step.

11. A food container manufactured by the method for manufacturing a barrier container according to any one of claims 1 to 10, wherein the multilayer film consists of unoriented polypropylene (CPP) / barrier material / unoriented polypropylene (CPP), and the barrier material is one of alumina deposition, aluminum deposition, aluminum foil, or a metal foil other than aluminum.

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