JPS621907B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a container, and more particularly to a cup-shaped container that is lightweight, has gas barrier properties, and is hard to bend.

Cup-shaped containers manufactured by drawing and forming metal plates such as tinplate (tinned steel plate), stain-free steel (electrolytic chromic acid treated steel plate), or aluminum (alloy) plate usually have gas barrier properties. Although it is highly rigid and difficult to bend, it has the problems of high material cost, large weight, and difficulty in disposing of it after use. As a solution to this problem, a cup-shaped container manufactured by drawing and forming a relatively thin flexible laminate made of metal foil and plastic film has been proposed; There is a problem in that when the sealed container sealed by the lid portion is grasped and opened by hand, the container is easily deformed during transportation or the like. Particularly when the package is opened, the contents tend to spill out and cause problems such as staining the surrounding area.

Relatively thick cup-shaped containers made of a single piece of plastic do not suffer from the above-mentioned problems such as deformation, but they generally have poor gas barrier properties and are unsuitable for long-term storage of foods at room temperature. On the other hand, a method of manufacturing a cup-shaped container by drawing a laminate made of a relatively thick plastic sheet and metal foil can be considered, but drawing of this type of laminate (which is usually done at room temperature) is difficult. , which is usually difficult to implement because it tends to wrinkle or break. Even if this is possible, the spring back after drawing is large and it is difficult to form the desired shape, and the residual stress is large, so heat treatment is not recommended during retort sterilization heat treatment or hot filling (for example, filling orange juice at 95°C). It has a problem of being easily deformed. If the above-mentioned laminate is thermoformed (for example, heated to a softening temperature and then vacuum-formed), the above thermal deformation will not occur, but in the case of thermoforming, large elongation deformation is generally involved, so thin There is a problem that the metal foil breaks and gas barrier properties are lost.

It is an object of the present invention to solve the problems of the prior art described above. In order to achieve the above object, the present invention provides a second layer in which the inner layer is made of a thermoplastic plastic film and has a flange portion formed by drawing from a blank of a flexible laminate containing metal foil. A second molded product having a shape corresponding to that of the first molded product and having a shape corresponding to that of the first molded product is hard to bend and is formed by thermoforming a thermoplastic plastic that can be thermally bonded to the thermoplastic plastic film inside the first molded product. The present invention provides a container in which a molded body is housed, and the first molded body and the second molded body are joined together by thermal bonding at least at each flange portion.

Furthermore, the present invention provides a first structure in which the layers to be the inner and outer surfaces are made of thermoplastic plastic film and have a flange portion formed by drawing from a blank of a flexible laminate containing metal foil.
A molded body is formed by thermoforming a thermoplastic that can be thermally bonded to the thermoplastic plastic film of the layer that is to become the outer surface,
The second molded body is housed inside a hard-to-flex second molded body having a shape corresponding to that of the first molded body, and the first molded body and the second molded body are joined together by thermal bonding at least at each flange portion. The present invention provides a container characterized by:

The present invention will be described below with reference to the drawings which are examples.

In FIGS. 1 and 2, 1 is a container, and a molded body 2 (hereinafter referred to as a laminate molded body) formed by drawing and curling a flexible laminate blank; It consists of a molded body 3 (hereinafter referred to as a plastic molded body) which is housed inside a laminate molded body 2 and is formed by thermoforming thermoplastic plastics. The laminate molded body 2 and the plastic molded body 3 have flange portions 4 and 5, respectively, and except for the curled portion 6 provided on the laminate molded body 2, both molded bodies have corresponding shapes, that is, both molded bodies have flange portions 4 and 5, respectively. It has a shape that can almost be fitted. Flange portion 5 of plastic molded body 3
and an inner layer 2a made of a thermoplastic film on the flange portion 4 of the laminate molded body 2 are thermally bonded via a heat sealing portion 7. In the example shown in FIG. 2, a gap 10 (width in the radial direction of 1 mm or less) remains between the body 8 of the laminate molded body 2 and the body 9 of the plastic molded body 3, but normally the gap 10 is almost It is preferable that the body parts 8 and 9 are in close contact with each other in order to prevent dents and the like when pressed with fingers.

Similarly, it is preferable that the bottom portion 11 of the laminate molded body 2 and the bottom portion 12 of the plastic molded body 3 are also in close contact with each other from the viewpoint of increasing the heat transfer coefficient during retort heat sterilization treatment. However, if a flat container 1 as shown in Figure 1 is filled with food with a low heat transfer coefficient and sealed,
When performing retort heat sterilization, the presence of voids 10 will reduce the thermal conductivity in the body.
Heat is transmitted almost uniformly in the radial direction mainly from the bottom 11 and the lid 13 (see Figure 3), and the heating temperatures of the food near the center of the container and the body become relatively close, resulting in overheating of the food near the body. This has the advantage of preventing quality deterioration due to

As shown in FIG. 2, the laminate molded body 2 includes an inner layer 2a made of a thermoplastic plastic film, an intermediate layer 2b made of a metal foil (for example, aluminum foil, electrolytic iron foil, steel foil, etc.), and a thermoplastic plastic film. The outer layer 2c is made of Each layer is bonded via an adhesive layer (not shown) such as a urethane adhesive or acid-modified polyolefin. The thermoplastic plastic film forming the inner layer 2a is preferably a plastic with a relatively low melting point that can be easily heat-sealed, such as polyethylene, polypropylene, copolymers or blends thereof, nylon 11, nylon 12, linear polyester, etc. It is made of polymer, polyester-ether, etc., and has a thickness of preferably about 10 to 200 μm, more preferably about 30 to 100 μm. about
If it is thinner than 10 μm, the above-mentioned plastic molded body 3
On the other hand, if the thickness is more than about 200 μm, residual stress due to drawing will increase, resulting in increased spring back after drawing and retort heating. This is because thermal deformation occurs during sterilization treatment. Therefore, from the point of view of cost reduction, it is desirable that the material be as thin as possible within the range that ensures self-shape retention after drawing.

The thickness of the metal foil forming the intermediate layer 2b is approximately 7~
Preferably it is 100 μm. This is because when the thickness becomes thinner than about 7 μm, the foil becomes porous and loses its gas barrier properties (against oxygen, water vapor, etc.). Thickness greater than approximately 100μm means low cost,
This is not preferable in achieving the objectives of the present invention, which are weight reduction and ease of disposal. In addition, in order to achieve the above object, it is more preferable that the thickness of the metal foil is as thin as possible, that is, about 7 to 30 μm.
However, in this case, drawing forming using the normal wrinkle pressing method causes significant wrinkles on the flange portion 4 and the body portion 8 (because they will break if a large wrinkle pressing force is applied to prevent wrinkles), and this is not satisfactory. It is not possible to obtain a molded product. However, if drawing is performed while applying rubber elastic pressure to the workpiece at the die shoulder according to the method previously proposed by the present inventors in JP-A No. 54-14363, satisfactory results can be obtained without wrinkles. A molded body can be obtained.

Examples of the thermoplastic plastic film forming the outer layer 2c include nylon 6, nylon 6,6, nylon 6,10, stretched or unstretched polyethylene terephthalate, polyethylene, polypropylene, or copolymers or blends thereof. is used. The thickness is preferably as thin as possible from the viewpoint of cost reduction, ensuring self-shape retention after drawing and corrosion protection of the metal foil, and within a range that allows lamination work. Therefore, it is usually about 50 μm.
It is as follows. Note that a printed container can be obtained by gravure printing on the back side of the film forming the outer layer 2c. Printing in this case is less expensive than printing on tin cans and the like because it does not require a baking process. Furthermore, since the printed portion is not exposed to the outside, it has the advantage of not peeling off. In addition, when the intermediate layer 2b is relatively thick, the anticorrosive baking coating may be formed directly on the metal foil without laminating the thermoplastic plastic film.

The plastic molded body 3 is made of a thermoplastic that can be thermally bonded to the inner layer 2a, that is, preferably the same or the same type of thermoplastic as the thermoplastic forming the inner layer 2a (the same type refers to, for example, low-density polyethylene and medium-density polyethylene). Formed by thermoforming from thermoplastic.

Here, thermoforming refers to a forming method such as vacuum forming, pressure forming, injection molding, etc., which is carried out in a softened or molten state, and almost no residual stress remains after forming. The wall thickness of the plastic molded body 3 is preferably about 0.3 to 2 mm, more preferably about 0.5 to 1.0 mm. If it is thinner than about 0.3 mm, it becomes easy to bend, and the reinforcing effect on the laminate molded body 2 is lost, while if it is thicker than about 2 mm, it becomes difficult to thermally bond the flange portion, and this results in increased cost and weight. be. Note that any method such as a heat bar method, a high frequency induction heating method, an ultrasonic method, an impulse method, etc. can be used for thermal bonding of the flange portion.

FIGS. 3 and 4 show a sealed container 15 in which the container 1 is filled with the contents 14 and then the lid 13 is heat-sealed. The lid part 13 is made of a metal plate (for example, an aluminum alloy plate or tin plate) on which a thermoplastic plastic forming the plastic molded body 3 and a thermoplastic plastic film (not shown) having thermal adhesive properties are laminated on the inner side. , is heat-sealed to the flange portion 5 of the plastic molded body 3 at its peripheral edge 13a. Lid part 13
This is a so-called full-open type lid that is easy to open, in which a ring pull tab 16 is bonded to the lid portion 13 at a fixed portion 16a, and the outer surface of the lid portion 13 has a circumferential shape defining an opening. score of 17
is formed. FIG. 5 shows a state in which the ring pull tab 16 is pulled up with the finger 18 and the score 17 is cut and opened. In this case, hold the container 1 with your other hand (not shown) and score 1.
Although the container 1 is gripped with some force against the force required to cut the container 7, due to the reinforcing action of the plastic molded body 3, troubles such as the container 1 being crushed and the contents 4 spilling out do not occur.

FIG. 6 shows a sealed container 19 in which the lid 20 is heat-sealed to the flange 5 of the plastic molded body 3 after the container 1 is filled with the contents 14. Note that 21 is a heat seal portion. Although not shown, the lid portion 20 includes an outer layer made of a reinforcing plastic film, an intermediate layer made of metal foil, and an inner layer made of a thermoplastic plastic film that is thermally adhesive to the thermoplastic plastic forming the plastic molded body 3. It is structured as follows. If the contents are retort food, the peel strength of the heat seal part 21 should be 2.3 kg/15 mm or more to meet legal regulations, and the
When a is pulled up with fingers, the thermoplastic forming the plastic molded body 3 and the thermoplastic plastic forming the inner layer film are separated so that the heat-sealed portion 21 is peeled off as shown in FIG. 7, for example. The combination of gases (eg, homopolypropylene with an ethylene-propylene copolymer or a polyethylene-propylene blend) is selected, and the heat sealing conditions are selected.

8 and 9 show a container 3 in which a laminate molded body 32 is housed inside a plastic molded body 33.
1, the outer layer 32c of the laminate molded body 32 and the plastic molded body 33 are arranged so that the outer layer 32c of the laminate molded body 32 and the plastic molded body 33 form a heat-sealing part 37 at each flange part 34 and 35, so that they can be thermally bonded. The thermoplastic plastic film forming the second
It differs from the container 1 in that it is the same type, thickness range, etc. as the thermoplastic plastic film that forms the inner layer 2a in the figure, but the other material compositions are the same, such as the inner layer of the laminate molded body 32. 32
The configurations of a and the intermediate layer 32b are the same as those of the inner layer 2a and the intermediate layer 2b of the laminate molded body 2, respectively. In this case, the flange portion 3 of the inner layer 32a
A lid portion (not shown) is heat-sealed to the portion corresponding to 4.

The containers 1 and 31 of the present invention are suitable for foods that require retort heat sterilization, such as salads, water bean paste, stews, vegetables, cooked rice, soups, fish, and preserved meat.
It is suitable for filling and sealing so-called hot-filled foods such as jellies and jams, but it goes without saying that it can also be applied to other foods such as seasonings, luxury goods, dried foods, drinks, etc. Nor.

Further, the shape of the container can be any shape such as a rectangular shape with rounded corners or an oval shape in cross section.

The container of the present invention is reinforced by combining a flexible drawn body with gas barrier properties with a hard-to-flex thermoformed plastic body at the flange portion by thermal bonding.
It has the advantage that it is difficult to deform during transportation or when opened after being sealed, and is lightweight and low cost. In addition, it is difficult to cause thermal deformation during retort heat sterilization treatment or hot filling, so in combination with the gas barrier properties mentioned above,
It has the advantage of being suitable for long-term storage of food at room temperature. Furthermore, since the container is mainly made of plastic, it has the advantage that it is less likely to undergo permanent deformation due to external forces, etc., compared to metal containers, and is also easier to dispose of by incineration, crushing, crushing, cutting, etc. In particular, when the inner side is made of a plastic molded body, there is an advantage that there is almost no corrosion or perforation of the metal due to the contents, which is often seen in metal containers, or the accompanying migration of metal ions into the contents.

A specific example will be explained below.

Specific example: The inner layer 2a is a polypropylene film with a thickness of 50 μm, the intermediate layer 2b is a soft aluminum foil with a thickness of 30 μm, and the outer layer 2c is gravure printed on the inner side.
A laminate blank made of a 20 μm unstretched nylon 6 film, each layer bonded with an isocyanate adhesive, was cold drawn using an elastic rubber-covered punch described in JP-A-54-14363, and then
A curling process was performed to form a laminate molded body 2 having the shape shown in FIG. The height to the upper surface of the flange portion 4 of this molded body 2 is 30 mm, the width of the flange portion 4 is 3 mm, and the diameter at the inner end of the flange portion 4 is 65 mm.
mm, and the internal volume was 75 c.c. Next, by vacuum forming method (forming temperature 190°C), the laminate molded body 2
The sixth container is made of polypropylene with a wall thickness of 0.8 mm and has a shape and dimensions that allow it to be stored in close contact with the inside of the container.
A plastic molded body 3 of the type shown in the figure was formed. Next, after the plastic molded body 3 was housed inside the laminate molded body 2, the flange parts 4 and 5 were heat-sealed by high-frequency induction heating.

After filling 70g of potato salad with a salt content of 1% by weight into the container 1 manufactured in this way, the inner layer was
Aluminum foil, which is the intermediate layer, is made by simultaneous two-layer extrusion coating method consisting of a blend of polypropylene (8 parts by weight) and polyethylene (2 parts by weight) with a thickness of 10 μm and maleic anhydride-modified polypropylene with a thickness of 5 μm as an adhesive. A laminate consisting of a laminated film adhered to a laminate film, an intermediate layer of aluminum foil with a thickness of 50 μm, and an outer layer of a gravure-printed biaxially stretched polyethylene terephthalate film with a thickness of 12 μm on the inner side (the intermediate layer and the outer layer are bonded with an isocyanate adhesive). The lid portion 20 having the knob portion 20a formed from the above was heat-sealed to the flange portion 4 portion of the inner layer 2a using a heat bar at 230° C. for 1 second. The peel strength under this condition is
It was 2.5Kg/15mm.

After the above sealing, 120℃×30 under air pressure of 2Kg/cm ²
During the heat treatment, no troubles such as deformation or swelling of the container occurred. In addition, the above-mentioned sterilized sealed container is
When the container 0a was pulled up with fingers and the heat-sealed portion 21 was peeled off and opened as shown in FIG. 7, there was no deformation such as crushing of the container 1 at all.

Comparative example: Polypropylene film with inner layer thickness of 50 μm,
The outer layer consists only of a laminate molded body (i.e., a plastic molded body) which is cold-drawn using an ordinary punch from a laminate blank (bonded with an isocyanate adhesive) made of a 120 μm thick externally baked soft aluminum foil. A sterilized sealed container was produced in the same manner as in the specific example except that a container (not using 3) was used and the external air pressure during retort heat sterilization was 3 Kg/cm ² . This was opened in the same manner as in the specific example, but the container was crushed at the part where it was gripped, and it was difficult to open.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a container that is an embodiment of the present invention, FIG. 2 is an enlarged vertical cross-sectional view of section A in FIG. 1, and FIG.
The figure is a plan view of a sealed container made by heat-sealing the lid part of the first example to the container of Figure 1, and Figure 4 is a plan view of the sealed container of the third example.
Fig. 5 is a longitudinal sectional view taken along the line - in the figure, Fig. 5 is a longitudinal sectional view showing the sealed container shown in Fig. 3 in an unsealed state, and Fig. 6 is a lid section of the container shown in Fig. 1 as a second example. 7 is a perspective view showing the sealed container of FIG. 6 in an unsealed state, and FIG. 8 is a longitudinal sectional view of a container according to another embodiment of the present invention. The plan view and FIG. 9 are an enlarged vertical cross-sectional view of section B in FIG. 8. DESCRIPTION OF SYMBOLS 1, 31... Container, 2, 32... Laminate molded body (first molded body), 2a, 32a... Inner layer (layer to be the inner surface), 2b, 32b... Intermediate layer (metal foil), 32
c... Outer layer (layer to be the outer surface), 3, 33... Plastic molded body (second molded body), 4, 34... Flange part, 5, 35... Flange part, 7, 37... Heat-sealed part.

Claims (1)

[Claims] 1. A first molding having a flange portion in which the inner layer is made of a thermoplastic plastic film and is formed by drawing from a blank of a flexible laminate containing metal foil. A hard-to-flex second molded body having a shape corresponding to the first molded body is formed by thermoforming a thermoplastic plastic that can be thermally bonded to the thermoplastic plastic film inside the body. is stored and the first
A container characterized in that the molded body and the second molded body are joined together by thermal bonding at least at each flange portion. 2. A first molded body whose layers to become the inner and outer surfaces are made of thermoplastic plastic film and has a flange portion formed by drawing from a flexible laminate blank containing metal foil. A second molded body that is hard to bend and has a shape corresponding to that of the first molded body is formed by thermoforming a thermoplastic plastic that can be thermally bonded to the thermoplastic plastic film of the layer that is to become the outer surface. 1. A container which is housed inside the container, and wherein the first molded body and the second molded body are joined together by thermal bonding at least at each flange portion.