JPH0234775B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a food packaging container.

More specifically, the present invention relates to an improved method for manufacturing containers for food packaging that enables retort sterilization and significantly enriches the variety of filling materials.

In recent years, containers for food packaging, such as liquid beverages, have become popular, with containers mainly consisting of cylinders made by appropriately laminating synthetic resin, paper, and aluminum foil, rolling up laminated sheets, and welding the ends of the laminated sheets together. is being used in large numbers because it is lightweight, has excellent display properties as a container, is printable, and is easily incinerated.

However, such food packaging containers
Most containers use only low-density polyethylene resin with good sealing properties for the outer layer of the cylinder body, which is the main body of the container, and the joints of the cylinder bodies are simply overlapped and welded. No special efforts were made.

On the other hand, retort sterilization is known as a relatively inexpensive device and harsh sterilization conditions under high temperature and pressure.

However, if retort sterilization is performed at a temperature of about 120°C with a conventional container configured as described above, the low-density polyethylene resin on the surface of the container will melt, and the outer surface of the container will melt. When sterilized by placing a large amount of them side by side, they fuse together, and when they are separated after sterilization, the film peels off. On the other hand, on the inner surface of the container, rough skin and pinholes occur, causing problems in terms of appearance and food hygiene. In addition, the strength of the joints between the container cylinder and the lid and container cylinder decreases dramatically due to the melting of the low-density polyethylene resin, and the slight pressure inside and outside the container during retort sterilization Fluctuations easily caused joints to shift and bags to break. Furthermore, the paper absorbs water from the joint end surface of the container cylinders that are simply overlapped and welded together.
The strength of the paper decreased, which caused the container itself to buckle and cause deformations such as wrinkles.

Therefore, when conventional containers are used for distribution at room temperature, heating sterilization by hot filling at about 90° C. is the limit, and the types of filling materials are extremely limited.

Therefore, in order to increase the variety of filling materials, it is necessary to increase the heat sterilization conditions, and the general indicator for this is an F ₀ value of 4 or more.

The F ₀ value represents the heating time required to kill a certain concentration of bacteria (spores) at a certain temperature, and is the killing time in minutes at 250°C (121°C). Other temperatures are also expressed in terms of 250〓. For example, Clostridium potulinum is said to die in 250·4 minutes in a phosphate buffer, and is expressed as F ₀ =4.

The present inventors have solved the drawbacks of the conventional technology by using thermoplastic resin as the material for both outer layers of the container cylindrical body, excluding low-density polyethylene resin alone, and by improving the joints of the cylindrical body (waterproofing treatment). ) made a proposal.

However, it became clear that even these proposals were still inadequate.

That is, in order to manufacture the proposed container, the cylindrical body made of a laminated sheet and the lid material are integrated by heat fusion.

At this time, the cylindrical body is made of laminated sheets made of synthetic resin, paper, and aluminum foil that are rolled up and stacked one on top of the other, and both ends are welded together.Aluminium foil and synthetic resin are laminated on both the upper and lower openings of the cylindrical body. The container is manufactured by closing the lid material and heat-pressing it.
Here, heating is carried out by a block-shaped hot stamp that advances into the opening from the longitudinal direction of the cylinder and contacts and holds the central part of the lid. Furthermore, the pressing is performed on the hot stamp and around the hot stamp, converging radially from the circumferential direction of the cylindrical body, and the adjacent side ends are engaged with each other and integrated, so that the hot stamp This is done using a plurality of jaws that press the peripheral portion of the lid material between the outer circumferential surface of the cylinder body and form an outer rim projecting from the outer circumferential surface of the end of the cylinder.

By the way, the welded part of the laminated sheet in the cylinder,
That is, a level difference inevitably occurs at both end portions where two laminated sheets are stacked. Therefore, a gap is created between the step and the inner surface of the lid, and it is necessary to perform sufficient welding to fill the gap with molten resin.

However, when the openings at both ends of the cylinder are closed with a normal lid material that forms an outer rim with a uniform height (width), a gap between the step at the welded part of the laminated sheet and the inner surface of the lid material is created. The amount of melted resin for embedding becomes insufficient, resulting in poor welding.
In order to solve this problem, increasing the size of the lid itself so that the outer rim becomes larger has the disadvantage that the cost becomes too high.

If there is a defective weld, hot water will enter from there during retort sterilization.

Due to this water intrusion, the paper in the cylinder absorbs water and the strength of the paper is extremely reduced, causing wrinkles, buckling, etc. on the outer surface of the container.

Such a situation not only causes a loss of marketability in terms of appearance, but also creates a risk that the contents may leak.

The present inventors have solved the drawbacks of these conventional techniques and have achieved the advantages of using a laminated sheet made of synthetic resin, paper, and aluminum foil as the main body of the container, while also making retort sterilization possible. Not only can the types of filling materials be greatly expanded, but also the food packaging container can be created without deformation of the container due to water seepage from the insufficiently welded part formed at the overlapping part of the cylinders in the lid fastening part of the container. As a result of intensive study to provide a manufacturing method,
Selection of the material for the outer layer of the container cylinder as described above,
The inventors have discovered that this object can be achieved by devising the joints of the cylinders and specifying the form of the lid material, and have arrived at the present invention.

In other words, the gist of the present invention is to waterproof a laminated sheet made of a synthetic resin, paper, and aluminum foil, with both outer layers made of a thermoplastic resin other than a low-density polyethylene resin alone, and then weld the ends of the laminated sheet rolled and stacked one on top of the other. A method of producing a container by forming a cylinder, and closing both the upper and lower openings of the cylinder with a lid made of aluminum foil whose inner surface is coated with a synthetic resin of the same type as the synthetic resin in the laminated sheet. In closing the opening of the cylindrical body with the lid, a block-shaped hot stamp that advances into the opening from the longitudinal direction of the cylindrical body and holds the central part of the lid, and a block-shaped hot stamp around the hot stamp. The cylindrical body converges radially from the circumferential direction, and the adjacent side ends engage with each other and become integrated, thereby pressing the peripheral part of the lid material between the outer peripheral surface of the hot stamp. In this case, a lid tightening jig is used, which includes a plurality of jaws forming an outer rim protruding from the outer peripheral surface of the end of the cylindrical body; A food packaging container characterized by using a lid material in which the portion to be welded from the outside facing both ends of rolled and stacked laminated sheets is bulged out in the peripheral direction more than other portions. It consists in the manufacturing method of

The present invention will be explained in more detail below.

The food packaging container manufactured according to the present invention is the first
As shown in the figure, it basically consists of a cylindrical body 1 and upper and lower lids 3.

The cylindrical body 1 is formed by welding both ends of laminated sheets 2 made of synthetic resin, paper, and aluminum foil rolled up and stacked one on top of the other.

Both outer layers of the laminated sheet 2 are thermoplastic resins excluding low density polyethylene resin alone.

Examples of this thermoplastic resin include commonly used thermoplastic resins other than those containing low-density polyethylene resin alone, such as polyethylene resins mainly consisting of high-density polyethylene resins, polypropylene resins,
Examples include polyethylene terephthalate resin. Among these, polyethylene resins, mainly consisting of high-density polyethylene resins, are preferably used.

Here, the high-density polyethylene resin generally refers to a resin with a density of 0.941 g/cm ³ or more.

"Mainly composed of high-density polyethylene resin" includes high-density polyethylene resin alone or blended with other resins.

However, if high-density polyethylene resin is used alone, there are some disadvantages in the extrusion laminate molding method that is often used for molding the laminated sheet 2 as described later, so blends with other resins are preferred. used.

Further, the polypropylene resin similarly includes a polypropylene resin alone or a blend with other resins having improved extrusion lamination properties.

Therefore, the processability required for the extrusion lamination method is the ability to form thin objects (the ability to make thinner resins, that is, the ability to form thinner films at higher speeds as the processing speed increases). Good quality and low net-in (a phenomenon in which the width of the extruded film is much smaller than the effective width of the die when forming a film using a T-die, and the thickness at both ends of the film becomes large) is required. be done.

For example, when high density polyethylene resin alone was used, all of the above requirements could not be satisfied, but it was found that the improvement could be achieved by blending low density polyethylene resin with good fluidity.

The blending amount of the low-density polyethylene resin is 10% to 25% by weight based on the high-density polyethylene resin, and the high-density polyethylene resin is the main component.

If the blend amount is less than this, the effect of blending will not be produced, and if it is too large, the heat resistance will be extremely reduced.

By the way, in retort sterilization under heat conditions of 10°C, the blended amount of low density polyethylene resin is limited to 25% by weight as mentioned above.

Note that the low-density polyethylene resin here refers to one having a density of 0.925 or less, as usual.

For example, the laminated structure of the laminated sheet 2 is, from the outer surface side of the cylinder, thermoplastic synthetic resin/paper/aluminum foil/
There are thermoplastic synthetic resins.

Further, as another example, there are thermoplastic synthetic resin/aluminum foil/paper/aluminum foil/thermoplastic synthetic resin from the outer surface side of the cylinder. Of course, the structure is not limited to this example, and may have a laminated structure with more layers, and may be changed as desired.

In particular, when using a laminated structure in which aluminum foil is placed on both sides of the paper, the synthesis of the outer layer is difficult in conveyance systems such as belt conveyors during container manufacturing, conveyance systems into retort sterilization pots, and movement of containers during retort sterilization. This is preferable because it eliminates inconveniences such as hot water soaking due to flaws that often occur in resins. There is essentially an adhesive layer between each layer of thermoplastic synthetic resin, paper and aluminum foil. This adhesive layer is interposed between the aluminum foil and the thermoplastic synthetic resin, which is mainly made of high-density polyethylene resin, which serves as both outer layers, and between the aluminum foil and the paper to ensure good adhesion between each layer. For this purpose, low density polyethylene resin can be used as the adhesive layer.

In addition, paper is paperboard in the JIS terminology, and is a general term for thick paper made mainly of wood chemical pulp, ground wood pulp, straw pulp, waste paper, etc., and is made using a paperboard machine.

This paper is hard and stiff, so it is often used as a packaging material, and there are corrugated cardboard materials, yellow paperboards, and white paperboards, but white paperboard made from white paper stock is particularly preferred. used.

The basis weight of paper is usually about 180 to 400 g/m ² .

Furthermore, aluminum foil is a common material often used for packaging materials, etc., and its thickness is 5 to 150 μm.
That's about it.

In particular, the cylindrical body of the container is preferably 5 to 20 microns, and the lid is preferably about 100 to 150 microns.

The laminated sheet 2 made of such a material is molded by an appropriate molding method such as the extrusion lamination method as described above.

To obtain a food packaging container according to the present invention, first, the laminated sheets 2 are rolled up and overlapped, and both ends thereof are waterproofed and welded to form a cylinder. This "waterproofing treatment" refers to a treatment that prevents both ends of the rolled and stacked laminated sheet 2 from coming into direct contact with the contents or being exposed to the outside air.
Although various aspects are conceivable, preferred aspects will be described below.

That is, a tape-shaped aluminum foil 4 coated on both sides with the same type of synthetic resin as the synthetic resin in the laminated sheet 2 is used.

Here, the synthetic resin of the same type as the synthetic resin in the laminated sheet 2 is basically a thermoplastic resin excluding low-density polyethylene resin alone, as described above, and also includes differences in density within regulations. It is something that

The tape-shaped aluminum foil 4 is applied to both side ends of the laminated sheet by steps A to D shown in FIG.

That is, in FIG. 2 A to B, both ends of the laminated sheet 2 are surrounded by tape-shaped aluminum foils 4 in a substantially dogleg shape with a gap from the outside, and at least one of the tape-shaped aluminum foils 4 is surrounded. One end of the foil 4 is bent inward within one side of the laminated sheet 2 and inserted.

In the case where both ends of the laminated sheet 2 are surrounded by tape-shaped aluminum foil 4 in a substantially doglegged shape, the "doglegged" shape is intended to ensure effective heating and melting in the subsequent stage. The bending angle may be obtuse or acute, but is preferably around 90 degrees. At such an angle, it is preferable that the tape-shaped aluminum foil 4 is not offset as much as possible with respect to the laminated sheet 2, and furthermore, it is surrounded from the outside with a suitable gap as shown in the figure.

In addition, bending one end of the tape-shaped aluminum foil 4 inward on one side of the laminated sheet 2 and inserting the aluminum foil 4 in a tape shape surrounding both side ends of the laminated sheet 2 in a substantially dogleg shape. Of the aluminum foils 4, one or both may be used. In particular, in the case of both, one side of the laminated sheet 2 should be in the same plane.

Next, in step C, both sides of the tape-shaped aluminum foil 4 and the laminated sheet 2 are heated by the burner 5 through the acute-angled gap between the top and bottom of the tape-shaped aluminum foil 4 and the laminated sheet 2 to weld them together. Fair.

This special heating method almost eliminates the stringy phenomenon in the subsequent pressing process, but
To ensure this, the following considerations should be taken.

That is, the flame from the burner 5
It is preferable to provide a shielding plate 6 made of a suitable material such as metal so that the aluminum foil 4 does not protrude outside the tape-shaped aluminum foil 4 surrounding the aluminum foil 4 in a substantially dogleg shape.

Without this shielding plate 6, the flame that protrudes outward may heat and melt the surface side directly in contact with the pressure roller in the latter stage, causing stringiness. It is preferable that the shielding plate 6 be placed very close to the tape-shaped aluminum foil 4 without coming into contact with it.

At this time, although not particularly shown in the drawings, it is more preferable to install an edge roller for adhering the outside of the dogleg shape of the tape-shaped aluminum foil 4 to the end surface of the laminated sheet 2.

In addition, when heating the tape-shaped aluminum foil 4 and the laminated sheet 2, an infrared heater, a hot air blowing device, etc. may be appropriately employed instead of the burner 5.

In step 2, the tape-shaped aluminum foil 4 heated in step 3 and the laminated sheet 2 are welded together by the upper and lower pressure of the pressure roller 7. The surface of the pressure roller 7 is preferably subjected to a surface treatment such as "Teflon" coating.

After welding the tape-shaped aluminum foil 4 to both ends of the laminated sheet 2 in this way, the tape-shaped aluminum foil 4 is rolled up so that the bent side becomes the inner surface of the container, and then stacked. Both ends are welded to form a cylinder.

For this welding, if one end of the tape-shaped aluminum foil 4 is bent at both ends of the laminated sheet, for example, when both tape-shaped aluminum foils 4 are bent, the tape-shaped aluminum foil 4 is bent as shown in FIG. The shaped aluminum foils 4 are simply made adjacent to each other and welded without overlapping each other.

When the bending process on one end of the tape-shaped aluminum foil 4 is performed on both tape-shaped aluminum foils 4 as shown in FIG. In this case, the welded portion becomes thick, which is not practical.

The end portion of the laminated sheet 2 located inside the overlapping portion of the cylinder obtained in this way is completely softened, and the inconvenience caused by water absorption from the inside of the cylinder (from the water content of the filling) is eliminated.

Furthermore, since the ends of the tape-shaped aluminum foil 4 do not come into contact with the filling material, there is no problem in terms of food hygiene.

Both the upper and lower openings of the cylindrical body are welded and closed by lid members made of aluminum foil whose insides are coated with a synthetic resin of the same type as the synthetic resin in the laminated sheet.

In the present invention, the following considerations are taken when closing the opening of the cylindrical body with the lid material.

First, when closing the opening of the cylinder with the lid material,
A lid tightening jig consisting of a combination of a hot stamp 8 and a jig 9 as shown in FIG. 4 is used.

The hot stamp 8 is block-shaped and extends from the longitudinal direction of the cylinder into both the upper and lower openings and holds the central portion of the lid.

The external shape and size of the hot stamp 8 are similar to the internal shapes of both the upper and lower openings of the cylindrical body, and are slightly smaller. That is, the configuration is such that a lid material can be interposed between the outer surface of the hot stamp 8 and the inner surfaces of both the upper and lower openings of the cylinder. The hot stamp 8 can be heated to a desired temperature as appropriate.

As shown in FIG. 4, a plurality of jaws 9 are provided around the hot stamp 8, converge radially from the circumferential direction of the cylinder, and are integrated by engaging adjacent side ends. Become.

The jaws 9 converge radially from the circumferential direction of the cylindrical body, and their adjacent side ends engage with each other to form an integral body, thereby tightening the peripheral portion of the lid material between the outer circumferential surface of the hot stamp 8 and the outer circumferential surface of the hot stamp 8. Pressing is performed to form an outer rim 10 protruding from the outer circumferential surface of the end of the cylindrical body.

FIG. 4C shows a form in which the jaws 9 converge radially from the circumferential direction of the cylindrical body, and their adjacent side ends engage with each other to form an integral body. That is, the side end portion of the jaw 9 forms a substantially comb-shaped cross section in which a plurality of thin plate-like bodies 11 are stacked at appropriate intervals in the vertical direction, that is, in the longitudinal direction of the cylindrical body. The side end portions of adjacent jaws 9 may be adjusted so as to closely rub against each other, and may be provided with a spacer or the like as appropriate.

In this way, the plurality of jaws 9 converge and engage with each other at their side ends to become an integral body, pressing the peripheral part of the lid member with the outer peripheral surface of the hot stamp 8, and pressing the outer peripheral part of the end of the cylindrical body. An outer rim 10 is formed which projects into the outer rim.

In the present invention, such a lid tightening jig is used, and a lid material adjusted to a special shape in advance is used.

That is, among the peripheral parts of the lid material, the part that is formed as the outer rim and is welded from the outside facing the both ends of the rolled and stacked laminated sheets is preliminarily moved in the peripheral direction from the other parts. Use expanded lid material.

Here, the term "peripheral direction" refers to the state where the lid material is a single flat plate.

The degree of bulge is preferably at least twice the height (width) of the outer rim when the non-bulged portion is formed on the outer rim. Since excessive expansion is undesirable from the viewpoint of workability and cost, it is usually preferable to expand the size by about twice as much. The range of the bulge is such that it can sufficiently cover the welded portion of the laminated sheet in the cylinder body, that is, the side end portions where two laminated sheets are stacked, from the outside. The shape of the bulge is not particularly limited.

As mentioned above, the periphery of the lid material having such a bulge is formed as an outer rim protruding from the outer circumferential surface of the end of the cylindrical body using a lid tightening jig consisting of a hot stamp and a plurality of jaws. ,
It is welded to the outer peripheral surface of the end of the cylinder.

During such welding, if the swollen portion of the lid material is opposed from the outside to both ends of the two laminated sheets, the gap between the step formed at both ends and the inner surface of the lid material will be reduced. Sufficient molten resin can be obtained to fill the voids, and welding can be performed satisfactorily.

Therefore, the conventional inconvenience caused by poor welding is completely eliminated.

Furthermore, since only a portion of the peripheral portion of the lid material is expanded, the cost is reduced compared to increasing the size of the entire lid material.

The present invention will be further described below based on Examples, but the present invention is not limited to the following Examples unless the gist of the invention is exceeded.

Example 1 A laminated sheet for forming a cylindrical body, a tape-shaped aluminum foil for covering the joints of the laminated sheets, and a lid material were manufactured into the following configuration by an extrusion lamination method or the like.

Laminated sheet for cylinder formation (width 240mm): outer layer side,
Polyethylene resin ⁽¹⁾ (20μ) / LDPE ⁽²⁾ (20μ) / Aluminum foil ⁽³⁾ (12μ) / LDPE ⁽²⁾ (20μ) / Paperboard (270
g/m ² )/LDPE ⁽²⁾ (20μ)/Aluminum foil ⁽³⁾ (12μ)/
LDEPE ⁽²⁾ (20μ) / Polyethylene resin ⁽¹⁾ (45μ), Inner layer tape aluminum foil (width 20mm): Polyethylene resin ⁽¹⁾ (25μ) / LDPE ⁽²⁾ (25μ) / Aluminum foil ⁽³⁾
(25μ) / LDPE ⁽²⁾ (25μ) / Polyethylene resin ⁽¹⁾
(25μ) Lid material (width 90mm): Inner layer side, polyethylene resin ⁽¹⁾
(50μ) / LDPE ⁽²⁾ (30μ) / Aluminum foil ⁽³⁾ ′ (130μ) (1) High-density polyethylene resin (Novatec
JVO40, MI-5.0, ρ=0.968, Novatec is a registered trademark of Mitsubishi Chemical Industries, Ltd.) 80% by weight and low density polyethylene resin (Novatec-L, L-300,
MI = 3.5, ρ = 0.922) 20% by weight blend.

(2) Low-density polyethylene resin (Novatec-L,
L-300, MI=3.5, ρ=0.922, Novatec-
(L is a registered trademark of Mitsubishi Chemical Industries, Ltd.) (3) Both sides are treated with a regular urethane anchor coating agent.

(3)' Only one side in contact with LDPE is treated with a regular urethane anchor coating agent.

From these parts a container with top and bottom lids as shown in FIG. 1 was made which was filled with 700 ml of water. (Manufactured by F, L, Hetsselmaschinenfabrik AG, HYPA system equipment.) The joints of the cylinders of the obtained containers were made as shown in Figure 3.

Note that the tape-shaped aluminum foil 4 at the joint portion
(Width: 20 mm) The width on the unbent end side was approximately 7 mm.

The lid material used had a height (width) of the outer rim opposite to both ends where two laminated sheets were stacked.
mm, the height (width) of the outer rim is half 3
mm.

The following considerations were made when blocking the lid material.

That is, there are four block-shaped hot stamps that are similar in shape to the inner surface shape of the upper and lower openings of the cylinder and are slightly smaller, and four hot stamps are arranged around the hot stamp and converge radially from the circumferential direction of the cylinder. A lid tightening jig consisting of an integrated jig was used.
(As shown in Figure 4 A to C) The Jyo is made of five stainless steel plates with a thickness of 1 mm stacked one on top of the other in the vertical direction, so that the side edges of adjacent Jyo are interlocked with each other. be.

The contents are filled with warm water (liquid temperature 85℃).
After that, set the temperature of the hot stamp to 200℃,
The mixture was further cooled with water to produce a filled container.

The external appearance of the lid fastening portion facing the opposite side ends where two laminated sheets were stacked was that the long outer rim sufficiently filled in the step.

The obtained filled container was retort sterilized under the following conditions.

The sterilizer used was ROTOMAT.
RSE, type 2, hot water rotary retort (West Germany, stock)
company). Retort sterilization conditions: Initial product temperature 19℃
The temperature was raised from 122℃ to 122℃ in 3 minutes.
Hold for a minute. Set pressure 2.2Kg/ ^cm3 (gauge pressure),
After cooling for 15 minutes (under the same set pressure) and retort sterilization at a rotation speed of 8 rpm of the container holding cage in the retort pot, the container did not see any water seepage, bag breakage, deformation, or contents, and its appearance was the same as before sterilization. There was no change at all and everything was normal.

The weight increase of the filled container after sterilization was 0.1 g (most likely due to moisture absorption by the outer layer resin).

Further, in order to check the water resistance (quality of welding) of the overlapping portion of the cylinders in the lid-clamping portion of the filled container, the container was immersed in a methylene blue-alcohol solution.

If the welding is defective, it can be easily determined because the paper of the laminated sheet of the cylinder permeates the solution and becomes colored blue.

As a result of the immersion, no coloring was observed on the lid of the container.

In addition, the containers were packed in a cardboard box (containing 20 bottles) and stored in four stacks for one week, and the appearance was re-inspected, but no abnormality was found.

Comparative Example 100 filled containers were obtained by carrying out the same operation as in the example except that no bulge was provided and a lid material whose outer rim height (width) was uniformly 3 mm was used. .

Then, retort sterilization was performed under the same conditions as in the example.

The weight increase of the container after retort sterilization is 0.6 to 19
It was hot at g. In total, the area of the areas flooded with water was less than about 10% of the entire container, and the container appeared normal in appearance, with no ink bleeding or wrinkles in the film.

The filled containers thus obtained were immersed in a methylene blue-alcohol solution in the same manner as in the Examples, and the quality of welding was checked by coloring the paper. As a result, in 83 out of 100 containers after retort sterilization, water was found only in the overlapping part of the cylinders at the lid tightening part.

However, when we packed the containers in a cardboard box (containing 20 bottles) and stored them in 4 stacks for a week and re-inspected their appearance, we found that 5 out of 20 containers were in the bottom cardboard box. As many as 7 bottles had wrinkles or small creases on the outer surface of the container.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view of a container obtained by the present invention;
Fig. 2 is a schematic diagram showing how the tape-shaped aluminum foil and the laminated sheet are welded, Fig. 3 is an enlarged partial cross-sectional view of the joint of the container cylinder, and Fig. 4 is the lid fastening method used in the present invention. It is a schematic diagram showing an aspect of a jig. 1: cylindrical body, 2: laminated sheet constituting the cylindrical body,
3: Lid material, 4: Tape-shaped aluminum foil, 8: Hot stamp, 9: Jyo, 10: Outer rim, 11: Jyo thin plate.

Claims (1)

[Claims] 1 Laminated sheets made of synthetic resin, paper, and aluminum foil with both outer layers made of thermoplastic resin (excluding low-density polyethylene resin alone) are rolled up and stacked on top of each other, and both ends are waterproofed and welded to form a cylinder. , a method for manufacturing a container by closing both upper and lower openings of the obtained cylinder with a lid material made of aluminum foil whose inner surface is coated with a synthetic resin of the same type as the synthetic resin in the laminated sheet, the method comprising: When closing the opening of the cylindrical body, a block-shaped hot stamp that advances from the long axis direction of the cylindrical body into the opening and holds the central part of the lid material, and around the hot stamp, the cylindrical body By converging radially from the circumferential direction of the cylinder body and engaging with each other to form an integral unit, the peripheral part of the lid member is pressed between the outer peripheral surface of the hot stamp and the cylindrical body is heated. A lid tightening jig consisting of a plurality of jaws forming an outer rim protruding from the outer circumferential surface of the end is used, and the laminated sheets are rolled up and stacked, forming the outer rim in the peripheral part of the lid material. A method for producing a food packaging container, characterized in that a lid material is used in which a portion of the lid material that is welded from the outside facing the joined end portions is bulged out in the peripheral direction more than other portions.