JP3209230B2 - Multi-layer thin-walled container with heat seal lid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container having a heat-sealing lid in which a heat-sealing lid is heat-welded to a flange formed at an upper end of a container for accommodating contents to seal the inside of the container. . In particular, the present invention relates to a multilayer thin-walled container in which the container is formed in a thin-walled shape by a plurality of resin layers having a specific function such as gas barrier properties.

[0002]

2. Description of the Related Art A container with a heat seal lid is constituted by a container for storing contents such as foodstuffs, and a heat seal lid which is heat-sealed to a flange of the container to seal the inside of the container. . Among these, the container body is required to have some or all of the following properties, that is, mechanical strength, gas barrier properties, moisture resistance, heat resistance, fragrance retention, and the like. It is known that each of these properties is achieved by a specific resin material. If there are a plurality of desired properties as required, one container is formed by laminating individual resin materials achieving the properties.

FIG. 8 shows an example of such a container. This container is constituted by a cup-shaped container body 1 provided with a flange 2 at the upper end of a container wall 3, and a heat seal lid 4 which is thermally welded to the flange 2. The contents are stored inside the container 1, and the inside of the container is sealed by the heat seal lid 4. The container wall 3 is formed by stacking a plurality of specific resin materials in order to achieve a specific function such as gas barrier properties. Such a container is required to have the performance that the flange is on the same plane (the sealing surface is flat). That is,
If the flange (sealing surface) is not flat (distorted or wavy), an unsealed portion remains, making it difficult to completely seal.

Various methods as described below have already been proposed as methods for producing such a container having a multilayer structure.

The first method is a so-called sheet forming method such as vacuum forming, pressure forming, plug assist forming and the like. In this sheet forming method, as shown in FIG.
A sheet sheet 51 is heated by a heater 52 while being conveyed at a predetermined feed pitch in the direction of arrow A, and then a container body 55 is formed by dies 53 and 54 arranged opposite to each other. It is.

In this sheet forming method, a large margin is formed between the individual container bodies 55 in accordance with the sheet feed pitch. Also, due to the structure of the dies 53 and 54, the space is perpendicular to the sheet feed direction A. A large margin is formed between the individual container bodies 55. These margins are very uneconomic because they become so-called scrap which does not contribute as a product.

[0007] It is also practiced to collect scraps and reuse them for part of the layer structure of the sheets 51 to regenerate the sheets 51 and to manufacture the container 55 from the regenerated sheets. However, in this method, the resin forming the sheet 51 gradually deteriorates due to pulverization at the time of reproduction or heat at the time of extruding the sheet, and causes problems such as coloring, unpleasant odor and strength deterioration. That is, when the scrap is to be reproduced, a part of the layer of the sheet 51 is constituted by the scrap layer or the scrap mixed layer. The sheet 51 in which such a resin is reused changes the composition of the scrap every time it is recycled, so that the properties of the sheet 51 as a whole change and the performance of each container to be formed may vary.

Further, it is extremely difficult to manufacture the sheet 51 to have a uniform thickness, and the thickness is inevitably uneven. That is, generally, a film is formed by an inflation method, an extrusion method, a co-extrusion method, etc.
The thickness of the sheet varies to some extent, and it is extremely difficult to make the thickness of a sheet obtained by laminating these layers uniform. If the thickness of the sheet 51 is uneven, the container 55 formed by the molds 53 and 54 has
The thickness distribution becomes uneven in one container body 55, and the thickness becomes uneven between the container bodies 55 as well. Further, in forming the sheet, the sheet 51 is heated and softened to form a container.
If the mold is not uniform in the width direction, or if the mold cooling conditions are not uniform for each cavity,
The thickness between containers becomes uneven. If the thickness of the container varies, particularly if the container has a thinner portion than a predetermined size, the container may not have sufficient mechanical strength (for example, buckling strength), or may be subjected to heat sterilization after filling the contents. A defect such as deformation of the container sometimes occurs.

As a second example of a method for manufacturing a multilayered container, there is a method disclosed in Japanese Patent Publication No. 57-1415. This method heats the square-shaped multilayer sheet material,
Further press molding to produce a disc-shaped preform,
Further, the disc-shaped preform is formed by vacuum forming or the like to produce a container body.

According to this method, scrap can be considerably reduced as compared with the above-described sheet forming. However, when a multilayer sheet material is press-formed to form a preform, it is necessary to heat the sheet material to a high temperature to reduce its viscosity. In this case, the layer structure of the multilayer sheet material is likely to collapse. That is, the layer is partially thinned or is easily separated. For a container formed from a multilayer sheet material having a collapsed layer structure, a target specific function such as gas barrier properties cannot be obtained.

Further, a good preform cannot be obtained unless a resin having good fluidity is used as a resin in contact with a mold for molding the preform. That is, the resin that can be used as the multilayer sheet material is limited to a narrow range.

Further, as a method of manufacturing a container using a preform, JP-A-60-178020 and JP-A-60-178020 can be used.
No. 244518, No. 63-130330 and No. 63-
There is a so-called injection blow method disclosed in each publication of 296921. In the injection blow method, a disc-shaped preform is formed by injection molding, and the preform is subjected to a molding process such as plug assist molding to form a container body.

In the injection blow method, since the injection molding method, that is, the injection molding method is used in the step of molding the preform, it is extremely difficult to form the preform into a multilayer structure. Only a preform is made. Therefore, there is a problem that a container having a specific function such as gas barrier property cannot be manufactured.

When a preform is formed by injection molding, for example, as shown in Japanese Patent Application Laid-Open No. 3-176126, if a preform is formed by using a plurality of injection devices and a multi-layer injection nozzle, a multi-layered preform is formed. Reforms can be manufactured. In this case, the layer configuration becomes symmetrical, and for example, research is progressing toward the practical use of cup-shaped containers and bottles having a gas barrier resin as an intermediate layer. However, according to this technique, not only is it extremely difficult to make the thickness of each resin layer uniform, but also, in many cases, near the end of the cavity where the flowing resin finally reaches, the multilayer structure itself does not hold. Thus, it is not possible to provide a uniform multilayer structure over the entire preform. Further, when a large number of resins need to be laminated in an asymmetric layer configuration as in the present invention, this method cannot be applied.

[0015] As another method of manufacturing a container having a multilayer structure, JP-A-2-45352 and JP-A-2-80519 are disclosed.
There is a method disclosed in each of the publications. In this method, a cup-shaped container material is pre-formed by sheet forming, and an outer layer is formed on the outer periphery by injection molding to manufacture a container body.

In the injection molding, a resin is poured into a gap in a mold. If the gap does not have a certain thickness or more, sufficient molding cannot be performed. Therefore, in the above-mentioned conventional method, there is a problem that the thickness of the container wall of the completed container body becomes too thick.

[0017]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned various problems, and is intended to reduce the layer structure of a thin-walled container having a multilayer structure. It is another object of the present invention to reduce the generation of scrap as much as possible and economically manufacture the scrap.

Another object of the present invention is to provide a multi-layer thin-walled container with a heat-sealing lid which can reliably weld the heat-sealing lid to the container body flange without subjecting the completed container to secondary processing.

[0019]

A multilayer thin container according to the present invention comprises a multilayer thin container having a flange and a plurality of laminated resin layers, and a heat seal lid thermally welded to the flange. Have. The multilayer thin container body is formed by subjecting a single preform having a plurality of resin layers to a molding process. The preform is formed by laminating an injection resin layer by injection molding on a surface of a sheet material including a resin layer having a specific function. Then, during the injection molding of the sheet material, the single-layer resin layer is formed wider than the sheet material such that the outer edge of the single-layer resin layer is outside the outer edge of the sheet material. In molding the preform, the preform is molded while fixedly supporting the outer edge of the single-layer resin layer protruding outside the sheet material in the preform. The outer edge of the single-layer resin is used as it is as the flange.

In the above structure, the resin layer having a specific function refers to a resin layer having various functions such as gas barrier properties, moisture proof properties, heat resistance properties, and fragrance retention (non-adsorptive properties). When laminating resins having poor adhesion, an adhesive layer provided between the layers and acting as an adhesive is also considered as a resin layer having a specific function. As a resin layer for achieving each of these functions, the following resin layers can be applied, respectively. Gas barrier properties: saponified ethylene-vinyl acetate copolymer (EVOH), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA) Moisture resistance: Polyamide (nylon), polypropylene, polyolefin incorporated with desiccant Heat resistance: polyester, polycarbonate, polypropylene Scent retention: polyester (PET), saponified ethylene-vinyl acetate copolymer (EVOH), polyacrylonitrile (PAN) Adhesive layer: ionomer, ethylene-vinyl acetate copolymer (EVA)

As a molding method, vacuum molding, pressure molding, plug assist molding and the like can be considered. Vacuum forming is a forming method in which the inside of the cavity is evacuated and the sheet material is deformed so as to be in close contact with the mold, thereby forming. Compressed air molding is a molding method in which a sheet material is pressed by air and brought into close contact with a mold to form the sheet material. The plug assist molding is a molding method in which the sheet material is assisted by a plug to form the sheet material in the vacuum forming or the pressure forming.

The resin layer laminated by injection molding on the sheet material mainly gives the container mechanical strength. Further, it is preferable that the resin is a resin having a heat-welding property capable of easily heat-sealing the heat seal lid (reference numeral 4 in FIG. 8). As such a resin, for example, polypropylene (PP), styrene, polyester, vinyl chloride or the like is used.

The heat seal lid usually includes a layer having excellent gas barrier properties such as an aluminum foil and an aluminum vapor-deposited film, and a resin layer having excellent heat welding properties is formed on the outer peripheral sealing surface. As a specific example, it can be formed in a four-layer structure of CPP / Al / print / PET. In addition, CPP indicates unstretched polypropylene, Al indicates aluminum, printing indicates a printing layer such as a label, and PET indicates polyethylene terephthalate.

[0024]

In manufacturing a thin multi-layer container, first, a container body for storing contents is manufactured as follows.
Prepare one sheet material containing one or more resin layers,
After being formed into a predetermined shape by punching or the like, it is mounted on an injection mold. Next, an injection resin such as polypropylene (PP) is laminated on the sheet material by injection molding to form a preform. Then, a container is manufactured by molding the preform. When the container is manufactured, the heat seal lid is welded to the flange of the container to complete the container as a product.

In the production of the container body, since the press molding is not used when molding the preform, the layer structure of the sheet material, that is, the layer structure of the preform does not collapse. In addition, since the preform is formed by a combination of the preformed sheet material and injection molding, even if the sheet material has some thickness variation, the variation is absorbed by the injection process, and the entire preform is formed. The thickness can be homogenized very precisely. Therefore, a container having a uniform thickness can be manufactured. Even in that case, the layer structure inside the container wall does not collapse.

Since a preform is prepared one by one and molded into a container, no scrap is generated unlike the conventional sheet molding method, and therefore, it is very economical. In this case, a large number of sheet materials to be mounted on the mold are created by, for example, punching or cutting one large sheet. At this time, since the sheet can be punched at a very high density, a large amount of scrap is not generated. In addition, when the resin layer is laminated by injection molding, almost no scrap is generated. The generation of scrap is extremely small.

When a preform is manufactured by subjecting a sheet material to injection molding, the preform is formed so that the injection resin layer is wider than the sheet material. Then, the outer edge portion of the injection resin layer protruding outside the sheet material functions as a fixed support portion, for example, a clamp portion, when the preform is formed next. Further, after the molding is completed, the fixed support portion is used as a flange of the container body. That is, a container with a flange can be obtained without performing any secondary processing. Since this flange is formed by injection molding, its thickness is uniform. Moreover, the flange is formed only of the injection resin layer that does not include the sheet material. Therefore, if a resin having excellent heat welding properties is used as the injection resin, even if the sheet material is inferior in heat welding properties, it is possible to impart heat welding properties to the flange. Also in this case, there is no need to perform any secondary processing.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a multilayer thin container having the shape shown in FIG. 8 will be described by way of example.

In the above container, the container body 1 is subjected to the following steps, that is, a sheet material preparing step of preparing a disk-shaped sheet material 5 having a single-layer or multilayer structure as shown in FIG. An injection resin 6 is laminated on one surface (the lower surface in the figure) of the disc-shaped sheet material 5 by injection molding to form a preform 7.
Injection molding process for forming the preform 7
Cup-shaped container body 1 as shown by chain lines
And a container forming step of forming a container body.

In the preform 7 formed by the injection molding process, as shown in FIG. 6, the injection resin layer 6 is formed wider than the sheet material 5 and the outer edge C of the injection resin layer is formed on the sheet material 5. It protrudes outside. The above-described container forming step is performed in a state where the outer edge C is clamped, that is, fixedly supported. As a result, as shown in FIG. 9, in the container body 1 finally obtained, the container wall 3 is constituted by a multilayer resin layer in which the sheet material 5 and the injection resin layer 6 are laminated, while the flange 2 is formed by injection resin. It is constituted only by the layer 6.

The resin laminated on the sheet material 5 in the injection molding step has a mechanical strength capable of giving a desired shape to the container and a heat sealing flange (FIG. 8).
For example, a thermoplastic resin having a heat-welding property, such as polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polycarbonate (PC), which can be used as the reference 2), is used.

The above-mentioned molding is a processing method in which a preform is stretched and formed into a desired shape, for example, a cup shape. For example, vacuum forming, pressure forming, plug assist forming, and the like can be employed. While this molding is performed, the peripheral portion C of the preform 7 is clamped, that is, supported in a fixed state.

The sheet material 5 shown in FIG. 5 is formed in a specific single-layer structure or multi-layer structure in order to obtain target specific functions, for example, gas barrier properties, moisture-proof properties, heat-resistance properties, and fragrance-retaining properties (non-adsorption properties). Is done. For example, as a two-layer structure, PET / EVOH, PET / PVDC, etc., from the direction corresponding to the inside of the container, and as a three-layer structure, PET / EVOH / PP, PP / PVDC / PP, etc. can be considered. In addition, PET is polyester EVOH, saponified ethylene-vinyl acetate copolymer PP, polypropylene PVDC is polyvinylidene chloride. Further, an adhesive or an adhesive resin layer is present between the respective layers of the sheet material 5 as necessary.

The method for manufacturing the sheet material 5 is not limited to a special method, and any method can be used. For example, one large sheet having a target layer configuration is formed by an arbitrary sheet forming method, for example, an adhesive laminating method, a co-extrusion method or the like, and a large number of discs are formed from the single sheet by punching. The sheet material 5 can be manufactured. Since the punching can be performed at a high density, that is, the individual disk-shaped sheet materials 5 can be punched from very close positions, there is no fear that a large amount of scrap remains on the raw material sheet after the punching.

In the above-described container body manufacturing process, a preform heating step for preheating the preform 7 formed by the injection molding step is added between the injection molding step and the container molding step, if necessary. You can also.
This preform heating step is a step for preliminary heating the preform 7 before being molded. This step is performed in order to reliably fuse the disc-shaped sheet material 5 and the injection-molded layer laminated thereon, and to raise the temperature of the preform 7 to a temperature at which the preform 7 can be easily formed.

If the container molding step is to be started immediately after the preparation of the preform by injection molding, the preform heating step may not be required. This is because the sheet material 5 is heated by the injected high-temperature resin. If the time between injection molding and container molding is relatively short,
Only the sheet material 5 of the preform 7 needs to be heated. On the other hand, when the time from injection molding to container molding is long and the preform 7 is completely cooled, both the sheet material 5 and the injection resin layer are heated.

When the container body 1 is thus manufactured,
As shown in FIG. 8, the heat seal lid 4 is heat-welded to the flange 2 of the container body 1 to complete the container. As a method for heat-welding the heat seal lid 4, various methods conventionally proposed, for example, a seal using a heated hot plate, an ultrasonic seal, a high-frequency seal, an impulse seal, and the like can be used.

Hereinafter, a method of manufacturing a multilayer thin container (FIG. 8) will be described in detail with reference to a specific example of a container manufacturing apparatus. FIG.
(A) shows an embodiment of an apparatus for performing the above-described injection molding step for manufacturing the container body 1. This injection molding device 24 has a fixing plate 8 at the top,
A core 9 is fixed to the lower surface of the fixing plate 8. Core 9
Are provided with a coolant passage 10 and an air suction passage 22. Lip cavity 1 around the lower part of core 9
1 and a lip plate 12 are provided. In addition, core 9
Of the cavity 13 held by the holding plate 14
The tip of the hot runner 15 projects inside the cavity 13 and contacts the gate 16.

The core 9 can be reciprocated linearly in the vertical direction as shown by arrows AA 'together with the fixed plate 8.
It moves between the illustrated clamping position and an open position (not shown) far away from the cavity 13. The mold clamping position is a position where a gap G corresponding to a desired preform shape is formed between the core 9 and the cavity 13.

The lip cavity 11 is of a so-called split type, and the right and left lip cavities can reciprocate linearly in the left and right directions as indicated by arrows BB 'with respect to the center axis L. Due to this movement, the lip cavity 11 moves between the illustrated mold clamping position and an open position (not shown) which is largely separated from each other.

FIG. 2 shows an embodiment of an apparatus for performing a preform heating step. This preform heating device 25 is used in an injection molding process (FIG. 1A) which is a preceding process.
Has a heater 17 which can protrude above the preform 7 formed by the above. A heater 30 for heating the injection resin layer 6 is provided below the preform 7. This heater 30 can be omitted when the process proceeds to the container molding step immediately after the lamination of the injection resin layer 6.

FIG. 1B shows a plug assist molding apparatus 2 which is an embodiment of an apparatus for performing a container molding step.
6 is shown. This device has a lower mold 18 connected below the lip cavity 11, a core 19 movable in the vertical direction, and a plug 20 penetrating the core 19 and movable in the vertical direction.

The core 19 is provided with an air introduction hole 23. Further, the lower die 18 is provided with a concave portion 21 having an inner wall surface that matches the shape of the container body 1 (FIG. A).

FIG. 4 shows an example of a heat seal device 31 for welding the heat seal lid 4 to the container 1. The heat sealing device 31 has a lower mold 32 for receiving the flange 2 of the container body 1 and a hot plate 33 heated by a heating device (not shown). The hot plate 33 can move up and down. When the heat plate 33 moves downward, the outer edge of the heat seal lid 4 is pressed against the flange 2, and heat is applied to both the heat seal lid 4 and the flange 2 to generate heat. The seal lid 4 is welded to the flange 2.

Hereinafter, each step will be described. (Injection Molding Step) In FIG. 1A, both the core 9 and the lip cavity 11 are moved to an open position (not shown) far away from the cavity 13. This allows
The upper surface of the cavity 13 is largely opened. In this state, as shown in FIG. 3, the disc-shaped sheet material 5 (see FIG. 5) is attached to the lower end of the core 9. The sheet material 5 is suction-fixed to the lower end of the core by the air flowing through the air suction path 22. The upper surface of the mounted sheet material 5, that is, the surface in contact with the core 9 becomes the inner wall surface of the container.

When the sheet material 5 is mounted on the lower end of the core 9, the core 9 and the lip cavity 11 are set at the mold clamping position as shown in FIG. In this state, the resin flows into the cavity recess G through the hot runner 15. Thus, the injection resin layer 6 (FIG. 6) is laminated on the lower surface of the sheet material 5 to form the preform 7 as shown by the solid line in FIG. When the preform 7 is formed, the process proceeds to the next preform heating step.

(Preform Heating Step) When the injection molding is completed, the core 9 moves from the mold clamping position to the open position in FIG. The lip cavity 11 continues to hold the outer edge C of the preform 7 while remaining at the mold clamping position. Then, the preform 7 is replaced with the lip cavity 11
While being held at the heating stage shown in FIG. In this heating stage, the heater 17 is carried out to a position immediately above the preform 7, and the preform 7 is heated by the heat radiated from the heater 17 and the heater 30 arranged as necessary. With this heating,
The fusion of the sheet material 5 and the injection resin layer 6 (FIG. 6) is promoted, and preheating for the next step, a container forming step, is performed. This preform heating step can be omitted in some cases.

(Container Forming Step) After the preform heating step is completed, the preform 7 is sent to the forming stage shown in FIG. 1B while being held by the lip cavity 11. The provided core 19 is set from above the preform 7 to a molding position shown in the figure, and molding is performed. At this time, the outer edge portion C of the preform 7 is fixedly supported by the lip cavity 11. That is, the preform 7 is pressed downward by the downward movement of the plug 20, and at the same time, the preform 7 is
Is prolonged. The preform 7 thus extended is
The wall shape of the concave portion 21 of the lower mold 18, that is, the cup shape is formed, and the container body 1 as shown in FIG. 8 is completed.

(Post-Processing Step) After the container forming step is completed, in FIG. 1B, if the lip cavity 11 holding the container body 1 is opened in the direction B, the container body 1 can be taken out as it is. Can be.

(Heat Sealing Step) When the container body 1 is thus manufactured, the contents are filled and sealed by heat sealing. In this heat sealing, for example, as shown in FIG. 4, the heat seal lid 4 is placed on the flange 2 of the container 1, and the heat seal lid 4 is welded to the flange 2 by the hot plate 33.

The flange 2 does not include the sheet material 5 and is composed of only the injection resin layer 6, and the injection resin layer 6 is formed of a resin having excellent heat welding property, for example, polypropylene (PP). I have. Therefore, no matter what kind of resin the sheet material 5 is made of,
The heat seal lid 4 can be reliably welded by heat. In this case, since the flange 2 is formed by injection molding, its thickness is very uniform, and its shape is stable without being distorted or waving, so that the heat sealability is further ensured. .

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the embodiments. For example, the shape of the preform may be a flat shape 27 without a step as shown in FIG. 7 instead of the stepped shape 7 as shown in FIG. Also, the shape of the product container can be an arbitrary shape (for example, a square tray shape). In this case, it is obvious that the shape of the sheet material 5 is prepared in a shape corresponding to the shape of the product container. Also, if necessary, repeat the injection molding process a plurality of times,
It is also possible to form two or more injection-molded resin layers.

In the above embodiment, the container is manufactured with the sheet material side being the inner surface side of the container. However, such a configuration has the following advantages. That is, the sheet material 5
Materials that can be suitably used are materials having a specific function, such as a saponified ethylene-vinyl acetate copolymer as a gas barrier resin and a polyester resin as a non-adsorptive resin. Since the resin is a resin such as polypropylene which is a main structural material of the container, the resin of the injection resin layer is generally more suitable for molding into a container shape such as sheet molding. Therefore, when the sheet material is formed, by disposing the sheet material 5 on the inner surface side of the container, it is possible to prevent molding failure of the sheet material 5 (thickness variation, cracking, etc. due to insufficient elongation during sheet molding). When a non-adsorbent resin is used for the sheet material 5, the purpose can be achieved only when the resin is disposed at a position in contact with the contents, and therefore, it is preferable that the resin be manufactured in a positional relationship as in the above embodiment. .

[0054]

According to the present invention, a preform is formed by performing injection molding in a state where a sheet material is mounted in a mold. A multi-layered preform of high quality can be obtained.

Since preforms are formed one by one by injection molding and a product container is formed from the preform, unnecessary components such as scraps are hardly generated. Therefore, it is very economical.

Since the preform is made by injection molding instead of press molding, the layer structure in the preform does not collapse. Therefore, specific functions such as gas barrier properties can be reliably obtained.

Since injection molding is used, the preform has extremely high precision in thickness. Since the preform having a uniform thickness is formed into a container shape to form a container, the preform is thin and has a small thickness in the container and between containers. It is possible to produce a container body having stable thickness accuracy with no variation.

Since the outer edge portion C of the injection resin layer is used as a flange of the container as it is, a flange having uniform thickness, excellent shape accuracy and excellent flatness can be obtained without performing secondary processing.
Therefore, it is convenient as a flange for a heat seal lid.

Conventionally, when a container body is formed using a material having a resin layer having poor heat sealability on the inner surface side of the container,
In order to impart heat sealing properties to the flange portion of the container body, surface cutting and other secondary processing are required, which is not only economically disadvantageous but also involves contamination by foreign matter such as cutting chips. It was difficult in practice to adopt such a configuration. On the other hand, according to the present invention, even if the sheet material itself is a resin having poor heat sealing properties, if a resin having excellent heat sealing properties is used as the injection resin, without performing any secondary processing, Excellent heat sealability can be given to the container body flange. Therefore, the limitation of the resin that can be used on the inner surface side of the container could be reduced.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of an apparatus for producing a multilayer thin container according to the present invention. In particular, FIG.
It is a side sectional view showing an example of an injection molding device. Also,
(B) is a side sectional view showing an example of the container forming apparatus.

FIG. 2 is a side sectional view showing one embodiment of a preform heating apparatus.

FIG. 3 is an enlarged sectional view showing a main part of FIG. 1 (A).

FIG. 4 is a side sectional view showing one embodiment of the heat sealing device.

FIG. 5 is a perspective view showing one embodiment of a sheet material.

FIG. 6 is a view showing a preform and a container.

FIG. 7 is a side view showing another example of the preform.

FIG. 8 is a perspective view showing an example of a multilayer thin-walled container.

FIG. 9 is a side sectional view showing a sectional structure of the container body of FIG. 8;

FIG. 10 is a perspective view showing an example of a conventional container manufacturing apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Container body 2 Flange 4 Heat seal lid 5 Sheet material 6 Injection resin layer 7 Preform 9 Core 11 Rip cavity 13 Cavity 24 Injection molding device 26 Container molding device 27 Preform C Injection edge of injection resin layer

Continuation of the front page (56) References JP-A-4-358822 (JP, A) JP-A-53-83884 (JP, A) JP-A-60-178020 (JP, A) JP-A-63-99913 (JP) , A) JP-A-60-244518 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 51/00-51/46 B29C 49/00-49/80 B29C 69/00 -69/02 B29D 22/00

Claims (1)

(57) [Claims] 1. A multilayer thin-walled container having a flange and having a plurality of laminated resin layers, and a heat seal lid thermally welded to the flange. Is formed by subjecting one preform having a resin layer to a molding process, and the preform is formed by laminating an injection resin layer by injection molding on a surface of a sheet material including a resin layer having a specific function. When injection molding into a sheet material, the single-layer resin layer is formed wider than the sheet material so that the outer edge of the single-layer resin layer is outside the outer edge of the sheet material, and the preform is formed. During the forming process, the preform is formed while fixing and supporting the outer edge of the single-layer resin layer protruding outside the sheet material of the preform, and the outer edge of the single-layer resin is used as the flange. Multilayer thin-walled container with a heat-sealed lid, characterized in that.