Primary molded body and manufacturing method of multipack using the same

Abstract

To provide a primary molded body 10 having excellent injection moldability even with a thin wall and a manufacturing method of a multipack 20 using the primary molded body.SOLUTION: A primary molded body 10 comprises a plurality of container forming regions 11, flange forming regions 13 surrounding each container forming region 11, and connecting portions 15 connecting adjacent flange forming regions 13. The primary molded body 10 is made of thermoplastic resin. The primary molded body 10 extends in a planar direction perpendicular to the thickness direction of the flange forming region 13, from the center of each container forming region 11 toward the outer peripheral edge of the flange forming region 13. An injection molding gate portion 14 is positioned at the center portion in the planar direction within each container forming region 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a primary molded article and a multipack. [Background technology]

[0002] Conventionally, multi-packs in which adjacent flanges are connected to each other have been used as cup-shaped containers for yogurt, etc. Generally, multi-packs are obtained by thermoforming a rolled sheet made of extruded polystyrene resin (Patent Document 1).

[0003] The applicant of the present application has also previously proposed a manufacturing method capable of efficiently forming cup-shaped containers from injection-molded sheet-like preforms (Patent Document 2). According to this invention, the injection-molded sheet-like preform is transferred to a vacuum forming and removal station while being held in a cavity mold by rotating a turntable, and then vacuum-formed or pressure-formed in a concave container mold to form a cup-shaped container. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-163356 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-220294 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional multi-packs such as those in Patent Document 1, the container portions are cut out from a continuous rolled sheet, and the portions not used for the containers are discarded. On the other hand, the manufacturing method in Patent Document 2 uses injection molding to form the containers, so no material is discarded like in Patent Document 1. However, because the method in Patent Document 2 injection molds multiple cup body forming portions from a single gate, it is difficult to form thin-walled preforms.

[0006] Therefore, an object of the present invention is to provide a primary molded article that is thin but has excellent injection moldability, and a method for producing a multi-pack using the same. [Means for solving the problem]

[0007] The present invention has been made to solve at least some of the above-mentioned problems, and can be realized as the following aspects or application examples.

[0008] [1] One aspect of the primary molded body according to the present invention is A primary molded article made of a thermoplastic resin, the primary molded article comprising: a plurality of container forming regions; flange forming regions around each of the container forming regions; and a connecting portion connecting adjacent flange forming regions to each other; the primary molded body extends in a planar direction that is a direction perpendicular to a thickness direction of the container forming region from a center of each of the container forming regions toward an outer peripheral edge of the flange forming region, A gate portion for injection molding is disposed at the center of each of the container forming regions in the planar direction.

[0009] According to one aspect of the primary molded article, a gate portion is disposed in each of the plurality of container forming regions, and therefore the primary molded article has excellent injection moldability even if it is thin-walled.

[0010] [2] In one embodiment of the primary molded body, The container-forming region may have a portion with a thickness greater than that of the flange-forming region.

[0011] According to one aspect of the primary molded article, the container-forming region is made thicker than the flange-forming region, thereby ensuring the required wall thickness for the portion that forms the container.

[0012] [3] In one embodiment of the primary molded body, Adjacent flange-forming regions can be connected to each other by a plurality of connecting portions formed by injection molding.

[0013] According to one aspect of the primary molded article, by having a plurality of injection-molded connecting parts of a predetermined shape, the connecting parts are less likely to break even when going through the multi-pack manufacturing process, content filling / production process, and sales process.

[0014] [4] In one embodiment of the primary molded body, The connecting portion has a notch portion formed therein that is thinner than the flange forming region, The notch portion may have a thickness that gradually decreases from both surfaces of the flange forming region toward the center in the thickness direction.

[0015] According to one aspect of the primary molded body, even a notch portion having a thin wall thickness can be easily filled with resin, and short shots can be prevented.

[0016] [5] In one embodiment of the primary molded body, The thermoplastic resin can be a polyester resin or a polyolefin resin.

[0017] According to one aspect of the primary molded article, the excellent injection moldability allows molding even polyester resin, which is difficult to mold into a thin wall, and also allows blow molding of a multi-pack with little thickness variation even from polyolefin resin, which is prone to thickness variation during blow molding.

[0018] [6] One aspect of the method for producing a multi-pack according to the present invention is to injection molding the primary molded body; heating at least the container-forming region of the primary molded body obtained by injection molding; The method is characterized in that the pressing region including the gate portion of the heated primary molded body is stretched with a stretching rod, and compressed air is introduced into the container forming region to perform stretch blow molding, thereby obtaining a multi-pack in which multiple adjacent containers are connected by the connecting portion.

[0019] According to one aspect of the method for manufacturing a multi-pack, the gate portion of the primary molded body is located at the center of each container forming region, so that a plurality of containers with little unevenness in thickness can be molded. [Effects of the Invention]

[0020] The primary molded article according to the present invention has excellent injection moldability even when it is thin-walled. Furthermore, the method for manufacturing a multi-pack according to the present invention makes it possible to mold a plurality of containers with little unevenness in wall thickness. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 2 is a perspective view of a primary molded body and a multipack according to the present embodiment. [Figure 2] FIG. 2 is a plan view of a primary molded body according to the present embodiment. [Figure 3] FIG. 3 is a front view of the primary molded body shown in FIG. [Figure 4] 3 is a vertical cross-sectional view schematically showing an injection molding step in the method for manufacturing a multi-pack according to the present embodiment. FIG. [Figure 5] FIG. 4 is a front view illustrating a heating step in the method for manufacturing a multi-pack according to the embodiment. [Figure 6] 3 is a longitudinal cross-sectional view illustrating a stretch blow molding step in the method for manufacturing a multi-pack according to the present embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0023] 1. Multipack The multi-pack 20 will be described with reference to Fig. 1. Fig. 1 is a perspective view of a primary molded body 10 and a multi-pack 20 according to this embodiment. Fig. 1 also shows a perspective view of a lid 30.

[0024] Multipack 20 is a packaging container in which multiple containers 21 are connected by connecting portions 15, filled with contents, and the containers 21 are sealed with lids 30 and distributed on the market. Consumers can divide multipack 20 into individual containers 21 by bending and folding connecting portions 15. Contents filled in multipack 20 include foods such as yogurt, tofu, mozuku seaweed, and pudding, and can also be used for medicines, cosmetics, etc.

[0025] The multi-pack 20 includes a plurality of containers 21, a plurality of flange portions 23, and a plurality of connecting portions 15. Although Fig. 1 shows a multi-pack 20 in which four containers 21 are integrated, the number of connected containers 21 is not limited to this. The multi-pack 20 may be an integrated set of two or three containers 21, or may be an integrated set of five or more containers 21.

[0026] The container 21 has a cylindrical portion extending downward from an opening rim 22 that opens into a flange portion 23, and a bottom portion that closes the lower end. Each container 21 is a so-called cup-shaped container. The cylindrical portion is, for example, approximately circular, but is not limited to this and may have an oval or polygonal cross section. There is no limit to the capacity of the container 21, but for food use it is, for example, 30 ml to 300 ml.

[0027] The flange portion 23 extends horizontally (in the X and Y directions) outward from the opening edge 22 of the container 21. The flange portion 23 is plate-shaped with a substantially flat front and back surface, but may have some irregularities or variations in thickness. The outer shape of the flange portion 23 is, for example, substantially rectangular, but other shapes may be adopted depending on the intended use of the container. The X, Y, and Z axes are perpendicular to one another.

[0028] The lid 30 is a thin sheet that seals the opening of the container 21. The lid 30 is produced in a manufacturing process separate from the manufacturing process of the multi-pack 20, and is adhered to the flange portion 23 after the contents have been filled into the container 21. A separation line 31 is formed in the lid 30 so that the lid 30 is separated together with the container 21 when the container 21 is separated. The material of the lid 30 can be paper, thermoplastic resin, or the like.

[0029] 2.Primary molded body The primary molded body 10 according to this embodiment will be described with reference to Figures 1 to 3. Figure 2 is a plan view of the primary molded body 10 according to this embodiment, and Figure 3 is a front view of the primary molded body 10 shown in Figure 2. Figure 2 is hatched to clarify each region.

[0030] The primary molded body 10 is made of a thermoplastic resin. The primary molded body 10 is molded by injection molding. The primary molded body 10 includes a plurality of container-forming regions 11, flange-forming regions 13 located around each of the container-forming regions 11, and connecting portions 15 connecting adjacent flange-forming regions 13. The primary molded body 10 extends in a planar direction, which is a direction perpendicular to the thickness direction of the container-forming regions 11, from the center of each of the container-forming regions 11 toward the outer periphery of the flange-forming regions 13. Here, in this embodiment, the thickness direction is a direction along the Z axis, and the planar direction is a direction along a plane passing through the X axis and the Y axis. The primary molded body 10 is formed, for example, entirely along a single imaginary plane 18. The imaginary plane 18 clearly shows the shape extending in the planar direction and is an imaginary plane parallel to a plane passing through the X axis and the Y axis.

[0031] Each container-forming region 11 and each flange-forming region 13 extends in a planar direction and is formed, for example, along one imaginary plane 18. For example, one surface of each of the container-forming regions 11 and flange-forming regions 13 may be on the imaginary plane 18, or the imaginary plane 18 may be located anywhere in the thickness direction of each of the container-forming regions 11 and flange-forming regions 13. The container-forming regions 11 and flange-forming regions 13 can be injection-molded to have a predetermined shape. The injection molding process will be described later.

[0032] The container-forming region 11 and the flange-forming region 13 may be flat and have a predetermined thickness. The predetermined thickness of the container-forming region 11 and the flange-forming region 13 is preferably as thin as possible within the range of the specifications required for the multi-pack 20, and may be, for example, 0.5 mm to 2.0 mm, more preferably 0.5 mm to 1.5 mm, and particularly 0.5 mm to 0.8 mm. Note that the term "flat" refers to a generally flat plate shape. One or both surfaces of the container-forming region 11 and the flange-forming region 13 may be flat. Having at least one flat surface in the primary molded body 10 facilitates mechanical transport to the heating process or stretch blow molding process after injection molding. Furthermore, a flat primary molded body 10 remains compact even when multiple primary molded bodies 10 are stacked, thereby saving space during storage and transportation. The container-forming region 11 and the flange-forming region 13, which may have slight irregularities or thickness variations depending on the specifications required for the multi-pack 20, are also considered flat.

[0033] 1 to 3 show an example in which the container-forming region 11 and the flange-forming region 13 have the same thickness. However, the container-forming region 11 may have a portion with a thickness greater than that of the flange-forming region 13. The thickness of the container-forming region 11 in the Z-axis direction may be, for example, 1.1 to 4.0 times, or even 1.1 to 3.0 times, the thickness of the flange-forming region 13. By making the container-forming region 11 thicker than the flange-forming region 13, the required thickness for the portion forming the container 21 can be ensured. Conventional roll-shaped sheets such as those shown in Patent Document 1 have the same thickness, making it difficult to adjust the thickness of the container 21. However, this embodiment makes it possible to injection-molde the container-forming region 11 to match the thickness of the container 21. The flange-forming region 13 may also have a portion with a different thickness. For example, the flange-forming region 13 may have a step along its inner periphery to form an annular portion along the inner periphery that is thinner than the outer periphery. In FIG. 2, for the sake of explanation, the hatched area is the container forming area 11 (including the pressing area 12), and the area outside of this is the flange forming area 13.

[0034] The outer edge of the flange-forming region 13 is approximately square in plan view. Adjacent flange-forming regions 13 are provided on the same imaginary plane 18 with a small gap between them. The gap between adjacent flange-forming regions 13 (the length of the connecting portion 15) can be 0.2 mm to 1.0 mm. A connecting portion 15 is provided to bridge the gap between two adjacent sides of each flange-forming region 13. The flange-forming region 13 is a portion that holds the primary molded body 10 in a mold during stretch blow molding, which will be described later. The flange-forming region 13 is also a portion to which the lid 30 is attached after the multi-pack 20 is filled with contents. The flange-forming region 13 may have thin-walled or stepped corners, for example, to allow a consumer to place their fingers on when peeling off the lid 30.

[0035] The connecting portion 15 connects adjacent flange-forming regions 13. The connecting portion 15 may extend in a planar direction along with the container-forming region 11 and the flange-forming region 13, for example, along a single imaginary plane 18. The connecting portion 15 is the portion where a consumer divides the multipack 20 into individual containers 21 after purchasing it. The connecting portion 15 can be easily bent and torn by the consumer. While there is no limit to the number or shape of the connecting portion 15, it is preferable that adjacent flange-forming regions 13 are connected by multiple connecting portions 15 formed by injection molding. Forming the connecting portion 15 of a predetermined shape by injection molding eliminates the need for post-processing to add a slit, as in the conventional method. Post-processing may be performed to facilitate the tearing of the connecting portion 15. Furthermore, by forming the connecting portion 15 by injection molding, the connecting portion 15 is less likely to tear even during the manufacturing process, the filling / production process, and the sales process of the multipack 20. One or more connecting portions 15 are provided between adjacent flange-forming regions 13. When there is one connecting portion 15, the length of the connecting portion 15 in plan view may be, for example, the same length as the straight portion of the adjacent flange-forming region 13. When there is one or more connecting portions 15, the length of each connecting portion 15 in plan view may be shorter than the straight portion. When multiple connecting portions 15 are provided, they are arranged at intervals as shown in FIG. 2. When there is an odd number of connecting portions 15 (one or more), it is preferable that one connecting portion 15 is arranged on an imaginary line connecting adjacent gate portions 14. This is because, during injection molding, the molten resin that enters the cavity 43 (FIG. 4) from the gate portion 14 first reaches the connecting portion 15 on the imaginary line, allowing the connecting portion 15 to be reliably molded.

[0036] As shown in FIG. 3 , the connecting portion 15 preferably has a notch portion 150 formed therein that is thinner than the flange-forming region 13. The notch portion 150 is formed so that its thickness gradually decreases from both surfaces of the flange-forming region 13 toward the center in the thickness direction. The notch portion 150 makes it easier for consumers to bend and break the multipack 20. The notch portion 150 includes a thinnest portion 151 located approximately in the center of the gap between adjacent flange-forming regions 13, and a thickness-reducing portion 152 whose thickness gradually decreases from both surfaces of the flange-forming region 13 toward the thinnest portion 151 located near the center in the thickness direction (along the Z axis). The notch portion 150 may be formed as a V-shaped inclined surface as shown in FIG. 3 . Because the thickness gradually decreases toward the center in the thickness direction, where the flow rate of the molten resin is faster during injection molding, even a thin notch portion 150 can be easily filled with resin, thereby preventing short shots.

[0037] The container forming region 11 is a portion that will be formed into the container 21 by stretch blow molding, which will be described later. The container forming region 11 is located inside the flange forming region 13. The outer edge of the container forming region 11 will become the opening edge 22 of the multi-pack 20. The container forming region 11 includes a pressing region 12 on its central side that is pressed by a stretch rod 64, which will be described later. When the pressing region 12 is pressed by the stretch rod 64, the container forming region 11 can be stretched in the direction along the Z axis. Depending on the specifications required for the container 21, the container forming region 11 may include, for example, a portion that is thicker than the flange forming region 13.

[0038] An injection molding gate 14 is located at the center of each container-forming region 11. The injection molding gate 14 is a gate mark used during injection molding of the primary molded body 10. The gate 14 is the portion where molten resin flows into the mold during injection molding of the primary molded body 10, as described below. Thin-walled injection-molded products are generally prone to short shots during injection molding. However, by locating a gate 14 in each of the multiple container-forming regions 11, the primary molded body 10 exhibits excellent injection moldability even when it is thin. Furthermore, since the molten resin spreads circumferentially from the gate 14 toward the outer periphery of the flange-forming region 13 during injection molding, locating the gate 14 approximately at the center of the container-forming region 11 reduces flow unevenness in the circumferential direction. This reduces thickness deviations when molding a thin-walled container 21. Note that, for illustrative purposes, the gate 14 is depicted protruding from the container-forming region 11, but it does not have to protrude.

[0039] Furthermore, if the gate portion is located exactly in the middle of two container forming areas as in the aforementioned Patent Document 1, it is difficult to accommodate three containers in a row, but since the primary molded body 10 has gate portions 14 located in each of the container forming areas 11, it can be applied to a multi-pack 20 having an odd number of containers 21, such as three or five.

[0040] The thermoplastic resin used to form the primary molded body can be any resin, crystalline or amorphous, as long as it can be injection molded and stretch-blow molded. However, from the perspective of recyclability, polyester resin or polyolefin resin is preferred. Polyester resin, in particular, can be recycled as a container and has a low environmental impact. Because the primary molded body 10 has a structure with excellent injection moldability, it can be molded even from polyester resin, which is difficult to injection mold into thin walls. Furthermore, because the gate portion 14 is located approximately in the center of the container-forming region 11, it is possible to blow-molde a multi-pack 20 with little thickness variation, even from polyolefin resin, which is prone to thickness variation during blow molding.

[0041] Polyester resins include, but are not limited to, polyethylene terephthalate (PET), polylactic acid (PLA), polyethylene furanoate (PEF), polyethylene naphthalate (PEN), and blends / mixtures of these polymers.

[0042] Polyolefin resins include, but are not limited to, polyethylene (PE), polypropylene (PP), olefin elastomers, and blends / mixtures of these polymers.

[0043] 3. Multipack manufacturing method The method for producing the multipack 20 according to this embodiment will be described with reference to Figures 4 to 6. Figure 4 is a vertical cross-sectional view schematically showing the injection molding step in the method for producing the multipack 20 according to this embodiment, Figure 5 is a front view illustrating the heating step in the method for producing the multipack 20 according to this embodiment, and Figure 6 is a vertical cross-sectional view illustrating the stretch blow molding step in the method for producing the multipack 20 according to this embodiment. In Figure 6, the left side shows the primary molded body 10 set in the blow molding die 60, and the right side shows the primary molded body 10 stretch blow molded to form the container 21.

[0044] The manufacturing process for multi-pack 20 includes injection molding, heating, and stretch blow molding steps.

[0045] 3-1. Injection molding process As shown in Fig. 4, in the injection molding process, the primary molded article 10 shown in Figs. 1 to 3 is injection molded using an injection mold 40. The injection mold 40 includes a movable mold 41 that can advance and retreat in the direction of the arrow, and a fixed mold 42 that is fixed to an injection molding apparatus (not shown) together with a hot runner 44. As shown in the figure, a cavity 43 is formed when the movable mold 41 is closed relative to the fixed mold 42.

[0046] The cavity 43 is a space formed in the outer shape of the primary molded body 10 described with reference to FIGS.

[0047] With the injection mold 40 closed, molten resin is injected from an injection device (not shown) through a hot runner 44 and nozzles 45 into the cavity 43. The cavity 43 is a space extending in a planar direction. In the example of FIG. 4 , the molten resin injected into the cavity 43 from each nozzle 45 extending in the Z-axis direction spreads radially in a planar direction through the cavity 43 corresponding to the container-forming region 11. The molten resin further spreads radially in the planar direction to fill the cavity 43 corresponding to the flange-forming region 13 and the cavity 43 corresponding to the connecting portion 15 around the container-forming region 11. The filled resin is held until it solidifies to a state that allows it to be removed, and then the movable mold 41 is opened and the primary molded body 10 is ejected from the mold.

[0048] The primary molded body 10 is shaped to be stretch-blow molded after a heating process to form the multi-pack 20, so no scrap is generated, unlike the scrap generated when conventional sheets are thermoformed. Therefore, the load on the environment is smaller than that of conventional general styrene-based multi-packs (Patent Document 1).

[0049] Furthermore, it is preferable that the distance from the gate portion 14 to the connecting portion 15 is equal in both container formation regions 11 adjacent to the connecting portion 15. This is because the molten resin filled from the gate portion 14 reaches the connecting portion 15 at approximately the same time and joins at the connecting portion 15.

[0050] As shown in the partially enlarged view of Figure 4, the molten resin flowing within the cavity 43 flows in the direction of the arrows from both sides of the adjacent flange-forming regions 13 at the connecting portion 15. The molten resin flows fastest near the center of the cavity 43 in the height direction, as shown by the velocity distribution indicated by the dashed line in Figure 4. Therefore, even if the height of the cavity 43 gradually decreases due to the inclined surface of the reduced-thickness portion 152, the resin fills up to the thinnest portion 151, preventing short shots. Furthermore, because the reduced-thickness portion 152 determines the rate of the resin flow, even if there is a slight delay in filling the adjacent flange-forming regions 13, the resin will merge at the connecting portion 15, forming a weld line that is easy to break by bending.

[0051] 3-2.Heating process As shown in Fig. 5, the heating step heats at least the container formation region 11 of the primary molded body 10 obtained by injection molding. The container formation region 11 is heated by the heating step to a temperature at which stretch blow molding is possible. The heating step can be performed using a known heater 50. The heating step can be performed, for example, while the primary molded body 10 is being transported to the stretch blow molding step.

[0052] 3-3.Stretch blow molding process As shown on the left side of Fig. 6, in the stretch blow molding process, a heated primary molded article 10 is set at a predetermined position in a blow molding die 60. The blow molding die 60 includes, for example, a blow die 61 and a bottom die 62 that form a cavity 63 having the shape of the container 21, a presser plate 65 that holds the flange-forming region 13 between it and the blow die 61, and a stretch rod 64. The stretch rod 64 can push up the pressing region 12 (the area hatched with fine dots in Fig. 2) toward the bottom die 62. The stretch rod 64 is configured so that compressed air can be introduced between the stretch rod 64 and the container-forming region 11 (the entire hatched area in Fig. 2).

[0053] Next, as shown on the right side of Figure 6, the pressing region 12 including the gate portion 14 of the heated primary molded body 10 is stretched with a stretching rod 64, and compressed air is introduced into the container forming region 11 to perform stretch blow molding, thereby obtaining a multi-pack 20 as shown in Figure 1 in which multiple adjacent containers 21 are connected by connecting portions 15. Because the gate portion 14 of the primary molded body 10 is located at the center of each container forming region 11, multiple containers 21 with little thickness unevenness can be formed.

[0054] The present invention is not limited to the above-described embodiments, and various modifications are possible. The present invention includes configurations that are substantially the same as those described in the embodiments (configurations with the same functions, methods, and results, or configurations with the same purpose and effects). The present invention also includes configurations that replace non-essential parts of the configurations described in the embodiments. The present invention also includes configurations that achieve the same effects or purposes as the configurations described in the embodiments. The present invention also includes configurations that add publicly known technology to the configurations described in the embodiments. [Explanation of symbols]

[0055] 10...primary molded body, 11...container forming region, 12...pressing region, 13...flange forming region, 14...gate portion, 15...connecting portion, 150...notch portion, 151...thinnest portion, 152...wall thickness reduced portion, 18...imaginary plane, 20...multipack, 21...container, 22...opening edge, 23...flange portion, 30...lid, 31...separation line, 40...injection molding mold, 41...movable mold, 42...fixed mold, 43...cavity, 44...hot runner, 45...nozzle, 50...heater, 60...blow molding mold, 61...blow mold, 62...bottom mold, 63...cavity, 64...stretch rod, 65...holding plate

Claims

1. A primary molded article made of a thermoplastic resin, the primary molded article comprising: a plurality of container forming regions; flange forming regions around each of the container forming regions; and a connecting portion connecting adjacent flange forming regions to each other; the primary molded body extends in a planar direction that is a direction perpendicular to a thickness direction of the container forming region from a center of each of the container forming regions toward an outer peripheral edge of the flange forming region, A primary molded body, characterized in that a gate portion for injection molding is disposed in a central portion in the planar direction of each of the container forming regions.

2. The primary molded article according to claim 1, A primary molded article, wherein the container-forming region has a portion with a thickness greater than that of the flange-forming region.

3. The primary molded article according to claim 1, A primary molded article, characterized in that adjacent flange forming regions are connected to each other by a plurality of the connecting portions formed by injection molding.

4. The primary molded article according to claim 2, The connecting portion has a notch portion formed therein that is thinner than the flange forming region, A primary molded body, characterized in that the notch portion has a thickness that gradually decreases from both surfaces of the flange forming region toward the center in the thickness direction.

5. The primary molded article according to claim 1, A primary molded body, wherein the thermoplastic resin is a polyester resin or a polyolefin resin.

6. The primary molded article according to any one of claims 1 to 5 is injection molded, heating at least the container-forming region of the primary molded body obtained by injection molding; A method for manufacturing a multipack, characterized in that a pressing region including the gate portion of the heated primary molded body is stretched with a stretching rod, and compressed air is introduced into the container forming region to perform stretch blow molding, thereby obtaining a multipack in which multiple adjacent containers are connected by the connecting portion.

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