Synthetic resin container, preform and method for manufacturing synthetic resin container

Abstract

To provide a synthetic resin container, a preform and a method for manufacturing a synthetic resin container which enable manufacture of a laminated peelable container at low cost.SOLUTION: A synthetic resin container 1 includes a cylindrical mouth part 4, a trunk part 5 continuous to the lower side of the mouth part 4, and a bottom part 6 for closing the lower end of the trunk part 5, and is formed by drawing blow molding, wherein the trunk part 5 and the body part 6 have outer layer bodies 2 and inner layer bodies 3 peelably laminated on the inner surfaces of the outer layer bodies 2, on the other hand, the mouth part 4 is not separated from the outer layer bodies 2 and the inner layer bodies 3, the bottom part 6 is provided with an outside air introduction hole 6b for introducing outside air into spaces between the outer layer bodies 2 and the inner layer bodies 3, and a peeling agent is coated onto the inner surfaces of the outer layer bodies 2, and the outer surfaces of the inner layer bodies 3.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a synthetic resin container having an outer layer and an inner layer peelably laminated to the inner surface of the outer layer, a preform that is a precursor to the synthetic resin container, and a method for manufacturing a synthetic resin container. [Background technology]

[0002] Delaminated containers, also known as delamination containers (delamination containers), have been known for some time as containers for storing liquid contents such as food seasonings such as soy sauce, beverages, cosmetics such as lotion, and toiletries such as shampoo, conditioner, and liquid soap (see, for example, Patent Document 1).

[0003] This type of delaminating container has a double structure in which a compressible inner layer, which provides a storage space for the liquid contents, is peelably laminated on the inner surface of an outer layer, which has a cylindrical mouth, a body connected to the mouth, and a bottom closing the lower end of the body and forms the outer shell of the container. It is used, for example, as a squeeze-type pouring container combined with a pouring cap equipped with a check valve or as a pump-equipped container combined with a pump. In this case, the liquid contents can be poured out by squeezing the body of the outer layer or operating the pump. After pouring, outside air can be introduced between the inner layer and the outer layer through an outside air inlet provided in the outer layer, keeping the inner layer in a compressed and deformed state. In this way, the delaminating container allows the liquid contents contained in the inner layer to be poured without being replaced with outside air, thereby reducing contact of the liquid contents contained inside the inner layer with outside air and preventing deterioration or deterioration.

[0004] The above-mentioned delaminated container can be manufactured by stretch blow molding a preform assembly having an outer preform made of, for example, polyethylene terephthalate (PET) and an inner preform arranged radially inside the outer preform and also made of polyethylene terephthalate (PET). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-117220 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the delaminated container described in Patent Document 1, it was necessary to mold the outer preform and the inner preform separately, assemble the preform assembly, and then perform biaxial stretch blow molding, which made it difficult to reduce manufacturing costs, and there was still room for improvement in this regard.

[0007] The present disclosure has been made in consideration of such problems, and its purpose is to provide a synthetic resin container, a preform, and a method for manufacturing a synthetic resin container that can produce a delaminated container at low cost. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems, the synthetic resin container of the present disclosure has: [1] A cylindrical mouth portion, a body portion connected to a lower portion of the mouth portion; a bottom portion that closes the lower end of the body portion; A synthetic resin container formed by stretch blow molding, The body and the bottom have an outer layer and an inner layer peelably laminated on the inner surface of the outer layer, while the mouth is not separated into the outer layer and the inner layer, an air inlet hole for introducing air into a space between the outer layer body and the inner layer body is provided in the bottom portion; The inner surface of the outer layer body and the outer surface of the inner layer body are coated with a release agent.

[0009] Further, the synthetic resin container of the present disclosure is [2] In the configuration described in [1] above, it is preferable that the thickness of the body of the inner layer body is less than 0.1 millimeters.

[0010] In order to solve the above-mentioned problems, the preform of the present disclosure has: [3] A preform having a neck portion, a cylindrical body portion connected to a lower portion of the neck portion, and a bottom wall portion closing a lower end of the body portion, the barrel portion and the bottom wall portion have an outer body and an inner body provided radially inside the outer body with a hollow portion interposed therebetween, while the mouth portion is not separated into the outer body and the inner body, The bottom wall portion is characterized in that a hole is provided to connect the outside to the hollow portion.

[0011] In order to solve the above-mentioned problems, the method for manufacturing a synthetic resin container according to the present disclosure includes: [4] A cylindrical mouth portion, a body portion connected to a lower portion of the mouth portion; a bottom portion that closes the lower end of the body portion; A method for manufacturing a synthetic resin container, comprising: preparing a mold for forming a preform having a mouth portion, a cylindrical body portion connected to a lower portion of the mouth portion, and a bottom wall portion closing a lower end of the body portion; supplying molten resin into the molding die through a gate provided in a cavity corresponding to the bottom wall portion of the molding die; supplying a gas into the cavity of the molding die through the gate to form a hollow portion at an intermediate portion in a thickness direction within the molten resin that constitutes the barrel portion and the bottom wall portion; providing a hole in the bottom wall portion that communicates with the outside and the hollow portion; supplying a release agent into the hollow portion through the hole and applying the release agent to the barrel portion and the bottom wall portion facing the hollow portion; forming a synthetic resin container by stretch blow molding the preform; The present invention is characterized by comprising: [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a synthetic resin container, a preform, and a method for manufacturing a synthetic resin container that allow delaminating containers to be manufactured at low cost. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a front partial cross-sectional view of a synthetic resin container according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is an enlarged view of part A in FIG. [Figure 3] FIG. 2 is an enlarged view of part B in FIG. [Figure 4] FIG. 1 is a front partial cross-sectional view of a preform according to an embodiment of the present disclosure. [Figure 5] 1 is a flowchart showing the steps of a method for manufacturing a synthetic resin container according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present disclosure will now be described in more detail with reference to the drawings.

[0015] The synthetic resin container 1 according to one embodiment of the present disclosure, shown in Figures 1 to 3, is also known as a delamination container or a delamination container. It has a double structure including an outer layer 2 and an inner layer 3, and its external shape is bottle-shaped, including a cylindrical mouth 4, a shoulder 7 located below the mouth 4 and expanding in diameter downward, a cylindrical body 5 connected to the lower end of the mouth 4 via the shoulder 7, and a bottom 6 closing the lower end of the body 5. In this embodiment, the body 5, bottom 6, and shoulder 7 include the outer layer 2 and inner layer 3. On the other hand, the mouth 4 is not separated into the outer layer 2 and the inner layer 3. That is, the resin layers that were separated into the outer layer 2 and the inner layer 3 at the shoulder 7 merge at the upper end of the shoulder 7 to form the mouth 4 as a single layer of synthetic resin. The junction of the outer layer 2 and the inner layer 3 is not limited to the upper end of the shoulder 7, but may be at a height other than the upper end of the shoulder 7, such as approximately the center height of the shoulder 7 or approximately the center height of the body 5. The region at the height of the mouth 4 is not, in principle, separated into the outer layer 2 and the inner layer 3. However, due to errors in gas-assisted molding when forming the preform 11, it is possible that the region below the mouth 4 may be slightly separated into the outer layer 2 and the inner layer 3. In this embodiment, the shoulder 7 is a region whose diameter expands downward, and the lower end of the region extending with the same diameter below the neck ring 8 is the lower end of the mouth 4 and the upper end of the shoulder 7. In the synthetic resin container 1, the inner surface refers to the surface facing the container S in FIG. 1, and the outer surface refers to the surface opposite the container S.

[0016] In this specification, claims, and drawings, the up-down direction means the upper and lower directions when the synthetic resin container 1 is in an upright position as shown in Fig. 1. Furthermore, the radially outward direction means the direction away from the central axis O1 along a straight line that passes through the central axis O1 of the synthetic resin container 1 in Fig. 1 and is perpendicular to the central axis O1, and the radially inward direction means the direction toward the central axis O1 along that straight line.

[0017] The mouth 4 is provided with a male thread 4a, and a dispensing member such as a dispensing cap or a dispensing pump can be attached to the mouth 4 by threading onto the male thread 4a. Note that the mouth 4 can also be configured to have an annular protrusion (for example, a bead 4d in FIG. 1) instead of or in addition to the male thread 4a, so that a dispensing cap or the like can be attached by engaging it in an undercut shape when stoppered. A neck ring 8 is provided at the bottom of the mouth 4 for fixing a preform 11, which will be described later, to a blow molding mold when molding the synthetic resin container 1 by, for example, stretch blow molding.

[0018] The following description will be given taking as an example a case where this synthetic resin container 1 is used as a squeeze-type dispensing container.

[0019] The outer layer 2 constitutes the outer shell of the synthetic resin container 1 and can be made of a synthetic resin material containing, for example, polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), or the like as a main component. The portion of the outer layer 2 corresponding to the body 5 is flexible and can be squeezed to become concave, and can also return to its original shape from the concave state. Note that when the synthetic resin container 1 is used as a pump-equipped container, the portion of the outer layer 2 corresponding to the body 5 does not need to be made squeezable.

[0020] In this embodiment, the inner layer body 3 can be formed from a synthetic resin material containing, for example, polyethylene terephthalate (PET), polypropylene (PP), or polyethylene (PE) as a main component, and is formed from the same synthetic resin material as the outer layer body 2. The inner layer body 3 can be formed into a bag-like shape thinner than the outer layer body 2 and is peelably laminated to the inner surface of the outer layer body 2. The interior of the inner layer body 3 forms a storage section S that is connected to the opening of the mouth portion 4. This storage section S can store, as contents, food seasonings such as soy sauce, beverages, cosmetics such as lotion, and toiletries such as shampoo, conditioner, and liquid soap. The inner layer body 3 may also be configured to have gas barrier properties by providing a vapor-deposited film of, for example, silica or diamond-like carbon (DLC) on its inside.

[0021] In this embodiment, as shown in Fig. 2, a void IN is formed between the outer layer body 2 and the inner layer body 3. This void IN is a hollow portion IN2 that was provided between the outer layer body 12 and the inner layer body 13 in the tubular barrel portion 15 and bottom wall portion 16 of the preform 11 described below, and was formed as a void between the outer layer body 2 and the inner layer body 3 after biaxial stretch blow molding. Note that the void IN does not exist with the same thickness over the entire area of ​​the barrel portion 5 and the bottom portion 6; the distance to the outer layer body 2 may be locally narrowed due to deformation of the inner layer body 3, or there may be areas where the inner layer body 3 and the outer layer body 2 are in contact with each other.

[0022] In this embodiment, a release agent is applied to the inner surface of the outer layer body 2 facing the gap portion IN and to the outer surface of the inner layer body 3. This configuration effectively prevents the contact points from sticking together and becoming inseparable, even when there is localized contact between the inner layer body 3 and the outer layer body 2 due to deformation of the inner layer body 3 or the like as described above.

[0023] In addition, the release agent to be applied to the inner surface of the outer layer body 2 and the outer surface of the inner layer body 3 may be, for example, silicone or liquid paraffin, but is not limited to these, and other release agents that can suppress adhesion between the outer layer body 2 and the inner layer body 3 may also be used.

[0024] 1 and 3, the bottom 6 is provided with an outside air inlet 6b for introducing outside air between the outer layer 2 and the inner layer 3. The outside air inlet 6b is formed at a gate position for supplying molten resin and gas into the cavity of the molding die when forming the preform 11. That is, the gate for supplying gas to form the hollow portion IN2 in the preform 11 communicates with the hollow portion IN2, and therefore the gate hole 16b (hole) (see FIG. 4) formed by cutting the gate portion from the preform 11 communicates with the hollow portion IN2. Therefore, the outside air inlet 6b and the void portion IN of the synthetic resin container 1 corresponding to the gate hole 16b and the hollow portion IN2 of the preform 11 also communicate with each other. When the synthetic resin container 1 is a so-called squeeze container, the opening diameter of the outside air inlet hole 6b is preferably set to a value that suppresses the escape of air from the gap IN through the outside air inlet hole 6b due to the pressure of the body 5 within a certain range, while allowing outside air to be introduced into the gap IN when the pressure is released, allowing for volumetric deformation of the inner layer body 3 due to use of the contents, and restoring the outer layer body 2 to its original shape. In the case of a squeeze container, an outside air inlet valve (check valve) that suppresses the escape of air due to the pressure may be provided in the outside air inlet hole 6b. Furthermore, when the synthetic resin container 1 is a pump container used with a pump attached to the opening 4, the size of the outside air inlet hole 6b is preferably set so as to prevent deformation of the outer layer body 2 due to volumetric deformation of the inner layer body 3 due to the discharge of the contents. In this case, the size of the gate hole 16b in the preform 11 (described later) can be increased, which also facilitates the supply of the release agent through the gate hole 16b. The shape of the outside air introduction hole 6b is not limited to a circular shape, and various other shapes such as an elongated hole can be adopted.

[0025] The synthetic resin container 1 having such a configuration can be configured as a pouring container by attaching a pouring member such as a pouring cap to its opening 4. In this case, the contents can be poured out through the pouring member by squeezing the portion of the outer layer 2 corresponding to the body 5, and the inner layer 3 can peel off from the inner surface of the outer layer 2 and undergo volume reduction and deformation as the contents are poured out. After the squeeze is released, outside air is introduced into the space (void IN) between the outer layer 2 and the inner layer 3 through the outside air inlet 6b provided in the bottom 6, allowing the outer layer 2 to return to its original shape while the inner layer 3 remains compressed and deformed. Furthermore, if the synthetic resin container 1 is a pump container used by attaching a pump to the opening 4, the outer layer 2 will always maintain its original shape, and only the inner layer 3 will undergo volume reduction and deformation as the pump pours the contents out of the inner layer 3. Therefore, the contents stored in the storage section S can be poured out without being replaced with outside air, thereby reducing contact of the contents stored in the storage section S with outside air and suppressing deterioration or alteration of the contents.

[0026] The synthetic resin container 1 is formed by fixing a neck ring 18 of a preform 11 (see FIG. 4) corresponding to the neck ring 8 in FIG. 1 to a blow molding die and then performing stretch blow molding.

[0027] Furthermore, after molding the synthetic resin container 1, an initial peeling process may be performed in which the inner layer body 3 is forcibly peeled off from the outer layer body 2 by, for example, blowing air through the outside air inlet hole 6b, and then air is forced in through the upper opening of the mouth portion 4 to return the inner layer body 3 to its original state. In this case, a gap is likely to form between the inner layer body 3 and the outer layer body 2. By having such a gap (void portion IN) between the inner layer body 3 and the outer layer body 2, it becomes easier to introduce outside air into the space between the inner layer body 3 and the outer layer body 2 through the outside air inlet hole 6b during use (when the contents are discharged).

[0028] This synthetic resin container 1 can be formed by stretch blow molding a synthetic resin preform 11 shown in FIG.

[0029] The preform 11 has a cylindrical (approximately test tube) external shape with a bottom, including a cylindrical mouth portion 14, a cylindrical body portion 15 connected to the lower side of the mouth portion 14, and a bottom wall portion 16 that closes the lower end of the body portion 15.

[0030] The up-down direction refers to the upper and lower directions when the preform 11 is in an upright position with the nozzle 14 disposed above the bottom wall 16, as shown in Fig. 4. The radially outward direction refers to the direction away from the central axis O2 along a straight line that passes through the central axis O2 of the preform 11 in Fig. 4 and is perpendicular to the central axis O2, and the radially inward direction refers to the direction toward the central axis O2 along that straight line.

[0031] In this embodiment, the neck portion 14 is a region of the tubular portion having approximately the same inner diameter, and the lower end of the tubular portion having the same inner diameter below the neck ring 18 is the lower end of the neck portion 14 and the upper end of the barrel portion 15. As shown in Fig. 4, the preform 11 has a double structure in the barrel portion 15 and bottom wall portion 16, including an outer body 12 made of synthetic resin that forms the outer layer body 2, and an inner body 13 made of synthetic resin that forms the inner layer body 3. The space between the outer body 12 and the inner body 13 forms a hollow portion IN2 that communicates with the outside through a gate hole 16b.

[0032] As shown in FIG. 4 , the resin layers that were separated into the outer body 12 and the inner body 13 in the barrel portion 15 merge at the upper end of the barrel portion 15 to form the neck portion 14 as a single layer of synthetic resin. In this embodiment, the upper end of the hollow portion IN2 extends to the upper end of the barrel portion 15, but this is not limited to this configuration. The upper end of the hollow portion IN2 may extend to a height lower than the upper end of the barrel portion 15. In principle, the height region of the neck portion 14 is not separated into the outer body 12 and the inner body 13. However, due to errors in gas-assisted molding when forming the preform 11, it is possible that the lower region of the neck portion 14 may be slightly separated into the outer body 12 and the inner body 13. The hollow portion IN2 need only be provided in at least the region that will become the body 5 and the bottom 6 of the synthetic resin container 1, and may terminate midway through the region that will become the shoulder 7 or the region that will become the body 5 of the synthetic resin container 1.

[0033] The neck portion 14 is formed in a shape corresponding to the opening 4 of the synthetic resin container 1, and is provided with a male thread 14a, a bead 14d, and a neck ring 18. The bottom wall portion 16 is formed in a curved shape (semispherical shape). The symbol O2 indicates a central axis common to the neck portion 14, the body portion 15, and the bottom wall portion 16. The inner surface of the preform 11 refers to the surface on the internal space S2 side in FIG. 4, and the outer surface refers to the surface opposite to the internal space S2.

[0034] The outer body 12 and the inner body 13 can be formed from the same synthetic resin material as the outer layer body 2 and the inner layer body 3, that is, a stretch-blowable synthetic resin material such as polyethylene terephthalate (PET), polypropylene (PP), or polyethylene (PE). The inner body 13 is formed thinner than the outer body 12, and is provided inside the outer body 12 so as to cover the entire inner surface of the outer body 12 via a hollow portion IN2.

[0035] Next, a method for manufacturing the synthetic resin container 1 according to an embodiment of the present disclosure will be described.

[0036] FIG. 5 is a flowchart showing the procedure for carrying out the method for manufacturing the synthetic resin container 1 according to this embodiment.

[0037] First, a method for forming a preform 11 for producing a synthetic resin container 1 by stretch blow molding (steps S101 to S104 in FIG. 5) will be described. First, a molding die is prepared for injection molding the preform 11 having a mouth portion 14, a barrel portion 15, and a bottom wall portion 16 shown in FIG. 4 (step S101 in FIG. 5). The molding of the preform 11 is not limited to injection molding, and other molding methods such as compression molding may also be used.

[0038] Next, molten resin is supplied into the molding die through a gate provided in a cavity corresponding to the bottom wall portion 16 of the molding die prepared in step S101 (step S102 in FIG. 5). In this embodiment, the gate for supplying molten resin is provided at the radial center position (on the central axis O2) of the bottom wall portion 16 in FIG. 4. After molding the preform, the gate portion formed by the gate is cut to form the gate hole 16b shown in FIG. 4. In this case, a hole may be formed that connects the end of the gate to the bottom wall portion 16.

[0039] Next, gas is supplied into the cavity of the molding die through the gate, creating a hollow portion IN2 (see FIG. 4) in the middle of the molten resin constituting the barrel portion 15 and the bottom wall portion 16 in the thickness direction (step S103 in FIG. 5). This hollow portion IN2 is formed by a technique known as gas-assisted molding, in which high-pressure nitrogen gas, high-pressure air, or other gas is supplied through the same gate that supplied the molten resin during the dwelling step of injection molding, and the supplied gas is sent to the middle of the bottom wall portion 16 and the barrel portion 15 in the thickness direction to form the hollow portion IN2. The molten resin injected through the gate solidifies from the contact surface with the mold toward the center of the cavity, so the high-pressure nitrogen gas, etc. supplied through the gate travels through the middle of the thickness direction of the barrel portion 15 and the bottom wall portion 16, where the molten resin has not yet solidified, forming the hollow portion IN2. In the above description, the "cavity" refers to a molding space formed between a core mold (male mold) and a cavity mold (female mold).

[0040] In the gas-assisted molding described above, it is possible to adjust the thickness of the inner body 13 and outer body 12 by adjusting the timing of supplying high-pressure nitrogen gas, the gas supply position, the temperature of the molding die, and other factors. This makes it possible to form a thin inner body 13, which was difficult to achieve with conventional preforms. This makes it possible to manufacture a synthetic resin container 1 having a thinner inner layer body 3 than before by blow molding, thereby reducing the amount of content that remains unused in the inner layer body 3. In order to achieve the above-mentioned effect, it is preferable that the wall thickness of the inner layer body 3 in the body portion 5 of the synthetic resin container 1 after blow molding is less than 0.1 millimeters.

[0041] Next, after removing the preform 11 from the molding die, the gate portion is cut to form a gate hole 16b (hole) in the bottom wall portion 16 that connects the outside to the hollow portion IN2 (step S104 in FIG. 5). In forming this preform 11, the gate portion solidified within the gate also has a hollow portion, so that after cutting the gate portion, it is possible to reliably form the gate hole 16b (see FIG. 4) that connects to the hollow portion IN2. For example, a preform 11 may be molded in which the gate hole is blocked by a gate portion that protrudes downward from the underside of the bottom wall portion 16, and after removing the preform 11 from the molding die, the gate portion may be cut away to open the gate hole 16b.

[0042] Next, a release agent is supplied into hollow portion IN2 through gate hole 16b formed in step S104, and the release agent is applied to tubular body portion 15 and bottom wall portion 16 facing hollow portion IN2 (step S105 in FIG. 5). By supplying a release agent such as silicone through gate hole 16b, the release agent can be applied to the inner surface of outer body 12 and the outer surface of inner body 13 at tubular body portion 15 and bottom wall portion 16 facing hollow portion IN2 that communicate with gate hole 16b.

[0043] Next, the preform 11 formed in steps S105 is stretch-blow molded to form the synthetic resin container 1, which is a delaminating container (step S106). During this stretch-blow molding, the stretched portions of the preform 11 (the tubular barrel portion 15 and the bottom wall portion 16) are first heated in a heating furnace to a temperature at which they can be stretched. Next, while the preform 11 is heated, the neck ring 18 of the preform 11 is abutted against the reference surface of a blow-molding mold and fixed, and the preform 11 is stretch-blow molded. The outer body 12 and inner body 13 of the tubular barrel portion 15 and the bottom wall portion 16 are stretched downward by a stretch rod while being blown radially outward by high-pressure air. During this process, the outer body 12 and inner body 13, made of the same material, may adhere to each other in a semi-molten state. However, the release agent between them prevents welding / fusion. Therefore, the inner layer 3 can be peeled from the outer layer 2 as the pressure inside the inner layer 3 decreases during use. Therefore, the function of the delaminating bottle is not impaired.

[0044] In the synthetic resin container 1 of this embodiment, the mouth portion 4 and the body portion 5 are formed into a substantially cylindrical shape, but are not limited to this and can also be formed into, for example, a rectangular or elliptical cylindrical shape. Similarly, in the preform 11 of this embodiment, the mouth portion 14 and the body portion 15 are formed into a substantially cylindrical shape, but are not limited to this and can also be formed into, for example, a rectangular or elliptical cylindrical shape.

[0045] As described above, the synthetic resin container 1 according to this embodiment is a synthetic resin container 1 formed by stretch blow molding, and includes a cylindrical mouth 4, a body 5 connected below the mouth 4, and a bottom 6 closing the lower end of the body 5. The body 5 and bottom 6 have an outer layer 2 and an inner layer 3 peelably laminated to the inner surface of the outer layer 2, while the mouth 4 is not separated into the outer layer 2 and the inner layer 3, and the bottom 6 is provided with an outside air inlet hole 6b for introducing outside air into the space between the outer layer 2 and the inner layer 3, and a release agent is applied to the inner surface of the outer layer 2 and the outer surface of the inner layer 3. By employing this configuration, the synthetic resin container 1, which is a delaminating container, can be formed by stretch blow molding a single preform 11, allowing the delaminating container to be manufactured at low cost.

[0046] Furthermore, in the synthetic resin container 1 according to this embodiment, the thickness of the body 5 of the inner layer body 3 is configured to be less than 0.1 millimeters. By adopting such a configuration, the inner layer body 3 can be easily deformed, thereby reducing the amount of content remaining in the inner layer body 3.

[0047] Moreover, the preform 11 according to this embodiment has a mouth 14, a cylindrical body 15 connected below the mouth 14, and a bottom wall 16 closing the lower end of the body 15, and the body 15 and the bottom wall 16 have an outer body 12 and an inner body 13 provided radially inside the outer body 12 via a hollow portion IN2, while the mouth 14 is not separated into the outer body 12 and the inner body 13, and the bottom wall 16 has a hole (gate hole 16b) that connects the outside with the hollow portion IN2. By employing such a configuration, a synthetic resin container 1 that is a delaminating container can be formed by stretch blow molding a single preform 11, and therefore delaminating containers can be manufactured at low cost.

[0048] The method for manufacturing a synthetic resin container 1 according to this embodiment is a method for manufacturing a synthetic resin container 1 having a cylindrical mouth portion 4, a body portion 5 connected to the lower side of the mouth portion 4, and a bottom portion 6 closing the lower end of the body portion 5, and includes the steps of: preparing a molding die for a preform 11 having a mouth portion 14, a cylindrical body portion 15 connected to the lower side of the mouth portion 14, and a bottom wall portion 16 closing the lower end of the body portion 15; and supplying molten resin into the molding die through a gate provided in a cavity of the molding die corresponding to the bottom wall portion 16. supplying a gas into the cavity of the molding die through a gate to form a hollow portion IN2 at a thickness-wise intermediate portion of the molten resin that forms the tubular barrel portion 15 and the bottom wall portion 16; providing a hole (gate hole 16b) in the bottom wall portion 16 that connects the outside to the hollow portion IN2; supplying a release agent into the hollow portion IN2 through the hole to apply the release agent to the tubular barrel portion 15 and the bottom wall portion 16 that face the hollow portion IN2; and forming the synthetic resin container 1 by stretch blow molding the preform 11. By employing such a configuration, the synthetic resin container 1, which is a delaminating container, can be formed by stretch blow molding a single preform 11, thereby enabling the delaminating container to be manufactured at low cost.

[0049] Although the present disclosure has been described based on various drawings and examples, it should be noted that those skilled in the art can easily make various modifications and alterations based on the present disclosure. Therefore, it should be noted that these modifications and alterations are included in the scope of the present invention. For example, the functions included in each component can be rearranged so as not to cause logical inconsistencies, and multiple components can be combined into one or divided. It should be understood that these modifications and alterations are also included in the scope of the present invention.

[0050] For example, in this embodiment, the gas for gas-assisted molding is supplied through the gate that supplies the molten resin, but this is not a limitation and the gas for gas-assisted molding may be supplied through an opening different from the gate that supplies the molten resin. [Explanation of symbols]

[0051] 1. Synthetic resin containers 2 Outer body 3. Inner layer 4 Mouth 4a male thread 4d bead 5. Torso 6 Bottom 6b Outside air intake 7 Shoulder 8 Neck Rings 11 Preform 12 External body 13 Inner body 14 Mouth part 14a male thread 14d bead 15 Trunk section 16 Bottom wall 16b Gate hole (hole) 18 Neck Ring IN cavity IN2 Hollow part O1,O2 Center axis S storage section S2 interior space

Claims

1. A cylindrical mouth portion, a body portion connected to a lower portion of the mouth portion; a bottom portion that closes the lower end of the body portion; A synthetic resin container formed by stretch blow molding, The body and the bottom have an outer layer and an inner layer peelably laminated on the inner surface of the outer layer, while the mouth is not separated into the outer layer and the inner layer, an air inlet hole for introducing air into a space between the outer layer body and the inner layer body is provided in the bottom portion; A synthetic resin container, wherein a release agent is applied to the inner surface of the outer layer body and the outer surface of the inner layer body.

2. 2. The synthetic resin container according to claim 1, wherein the thickness of the body of the inner layer is less than 0.1 millimeters.

3. A preform having a neck portion, a cylindrical body portion connected to a lower portion of the neck portion, and a bottom wall portion closing a lower end of the body portion, the barrel portion and the bottom wall portion have an outer body and an inner body provided radially inside the outer body with a hollow portion interposed therebetween, while the mouth portion is not separated into the outer body and the inner body, The preform has a hole in the bottom wall portion that connects the outside with the hollow portion.

4. A cylindrical mouth portion, a body portion connected to a lower portion of the mouth portion; a bottom portion that closes the lower end of the body portion; A method for manufacturing a synthetic resin container, comprising: preparing a mold for forming a preform having a mouth portion, a cylindrical body portion connected to a lower portion of the mouth portion, and a bottom wall portion closing a lower end of the body portion; supplying molten resin into the molding die through a gate provided in a cavity corresponding to the bottom wall portion of the molding die; supplying a gas into the cavity of the molding die through the gate to form a hollow portion at an intermediate portion in a thickness direction within the molten resin that constitutes the barrel portion and the bottom wall portion; providing a hole in the bottom wall portion that communicates with the outside and the hollow portion; supplying a release agent into the hollow portion through the hole and applying the release agent to the barrel portion and the bottom wall portion facing the hollow portion; forming a synthetic resin container by stretch blow molding the preform; A method for manufacturing a synthetic resin container, comprising:

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