JPH0239930Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a food storage container made of a composite sheet of synthetic resin film, and focuses on the attributes required for this type of container, especially gas barrier properties and moisture resistance, which are important elements for food preservation. And the fragrance retention property is greatly improved.

It has been known to make food storage containers by molding composite sheets made by laminating various thermoplastic synthetic resin films, and the applicant has also developed polychlorinated polycarbonate films by interposing a polyolefin layer. A container formed from a composite sheet in which vinylidene film is laminated and a polyolefin layer is further provided thereon (Japanese Utility Model Publication No. 55-41333), and a polyvinylidene chloride film is laminated to a polyester film with a polyolefin layer interposed therebetween. At the same time, we proposed a container formed from a composite sheet on which a polyolefin layer was provided (Japanese Utility Model Publication No. 55-47941).

However, in the above case, since the composite sheet that is the material is mainly made of polycarbonate film or polyester film, not only does the former have problems with moldability and the latter with heat resistance, but both of them are particularly suitable for this type of food. Gas barrier properties, moisture proof properties, and aroma retention properties, which are important factors for storage containers, were not fully satisfactory.

In addition, in order to improve gas barrier properties, moisture proof properties, and fragrance retention properties, the applicant has also bonded an ethylene-vinyl alcohol copolymer film to a polycarbonate film with a polyolefin layer interposed therebetween, and also bonded the copolymer film to a polycarbonate film with a polyolefin layer interposed therebetween. A composite sheet with a polyolefin layer on top has been proposed (Utility Application No. 55-168061), but in this case, the gas barrier properties, moisture proofing properties, and fragrance retention properties are improved to some extent. However, it is still not the best.

Furthermore, in order to improve moldability as well as gas barrier properties, moisture resistance, and fragrance retention, a polyvinylidene chloride film is laminated to a polycarbonate film via a polyolefin layer, and a polyolefin layer is further provided on the polycarbonate film. A method in which the thickness of the polyolefin layer is increased (Utility Application No. 168062/1987) has been proposed, but in this case as well, the gas barrier properties and moisture proof properties have not been sufficiently improved and are still insufficient. It is. That is, the ethylene-vinyl alcohol copolymer film has an extremely low oxygen permeability in a dry state at 20°C, and exhibits the highest oxygen gas barrier property among various synthetic resin films. However, this gas barrier property decreases significantly with increases in temperature and humidity. Additionally, it has high moisture permeability under high temperature and high humidity conditions. In this way, oxygen gas barrier properties and moisture proof properties decrease in hot and humid conditions,
Containers made of ethylene-vinyl alcohol copolymer film cannot prevent food from going rancid in the summer. In addition, like today, when non-perishable foods are placed in storage containers and then pressure sterilized at high temperatures of 100°C or higher, or when they are immersed in boiling water and heated in their containers, oxygen and moisture can pass through, causing the food inside the container to go rancid. On the other hand, although the oxygen permeability of polyvinylidene chloride film in a dry state at 20°C is slightly higher than that of ethylene-vinyl alcohol copolymer film, the temperature dependence and humidity dependence of oxygen permeability are lower than that of other synthetic resin films. low. Further, the moisture permeability under high temperature and high humidity conditions is much lower than that of an ethylene-vinyl alcohol copolymer film. Therefore, by making a laminated composite sheet that has both of these properties, it is possible to synergistically improve the properties expected of this type of food storage container, especially gas barrier properties, moisture proof properties, and flavor retention properties. Furthermore, it was discovered that by including a metal vapor deposited film, the oxygen gas barrier properties and moisture proofing properties were dramatically improved, and the present invention was made based on this knowledge.

That is, the present invention is a composite film in which a three-layer film having polyolefin layers on both sides of an ethylene-vinyl alcohol copolymer film, a three-layer film having polyolefin layers on both sides of a polyvinylidene chloride film, and a metal vapor-deposited film are laminated. The food storage container is made of a sheet and is formed so that the metal vapor-deposited film is present on the outer surface of the container.

As described above, the composite sheet of the present invention includes a three-layer film having polyolefin layers on both sides of an ethylene-vinyl alcohol copolymer film,
It is made by laminating a three-layer film having polyolefin layers on both sides of a polyvinylidene chloride film and a metal vapor-deposited film. Since the layers are laminated with a polyolefin layer interposed therebetween, the adhesion between each layer is good and no delamination occurs even at high temperatures.

Furthermore, since the composite sheet includes a metal-deposited film as a constituent element, its oxygen gas barrier properties and moisture-proof properties are dramatically improved.

Furthermore, since the polyolefin layer contained in both three-layer films constituting the composite sheet occupies most of the total thickness of the composite sheet, it can be easily molded in the same way as a molded product of polyolefin.

Next, one embodiment of the present invention will be described based on the drawings.

In Figures 1 to 3, A indicates a container according to the present invention, which is formed into a container of a desired shape using a composite sheet of thermoplastic synthetic resin film by vacuum forming, pressure forming, press forming, etc. It has been done.

Therefore, the composite sheet that is the constituent material of container A, as shown enlarged in FIGS. 2 and 3,
It is composed of a laminate having an ethylene-vinyl alcohol copolymer film 1 and a polyvinylidene chloride film 4 in the layer, and in the illustrated embodiment,
Ethylene-vinyl alcohol copolymer film 1
as an intermediate layer and polyolefin layer 2 on both sides.
2 and a second three-layer film 6 having a polyvinylidene chloride film 4 as an intermediate layer and polyolefin layers 5, 5 on both sides thereof are bonded together. . The first three-layer film 3 and the second three-layer film 6 may be formed by directly laminating the polyolefin layers 2 and 5 on the surface thereof by fusing means, adhesive means, dry lamination method, etc. As shown in the figure, it is desirable to laminate the three-layer films 3 and 6 with a polyolefin layer 7 such as polyethylene or polypropylene film interposed therebetween. Further, the polyolefin layers 2, 2, 5, 5 of the first and second three-layer films 3, 6 may be made of either polyethylene or polypropylene.

In the illustrated embodiment, a polyolefin layer 8 of polyethylene or polypropylene film is interposed on the surface of the second three-layer film 6 having a polyvinylidene chloride film 4 as an intermediate layer, and a metal such as aluminum is deposited on one side. The polycarbonate films 9 are laminated so that the vapor-deposited surfaces are bonded together, and 10 indicates a metal-deposited film. In place of the polycarbonate film 9 described above, a polypropylene film coated with metal vapor deposition may also be used. Further, the film having the metal vapor deposited film is used as a first three-layer film 3 having the ethylene-vinyl alcohol copolymer film 1 as an intermediate layer.
It can also be laminated on the side surface. In any case, it is preferable that the metal-deposited film be colored transparently yellow, transparently silver, transparently red, or otherwise. In addition, when vacuum forming, pressure forming, or press forming the container A using such a composite sheet, the metallized film such as the polycarbonate film 9 should be placed on the outside of the container, that is, the polyolefin layer should be on the inside of the container. Shape. In some cases, the surface of the polycarbonate film 9 is subjected to metal vapor deposition, and then a resin baking coating is further applied thereon.

In the case of this embodiment, the composite sheet that is the constituent material of the container A includes a metal vapor-deposited film 10 such as aluminum, and the polycarbonate film 9 is exposed on the outer surface of the container, so even though it is thin, it feels stiff. In addition to giving the product a texture and feel similar to that of a metal plate, it also has a metallic luster due to the metal vapor deposited film 10, giving it the appearance of a metal foil product made of aluminum or the like, giving it a good appearance.

In the above embodiment, the first three-layer film 3 constituting the composite sheet has a thickness of about 30 to 800 microns, and the middle layer is ethylene-
The thickness of vinyl alcohol copolymer film 1 is 5
~90 microns. The second three-layer film 6 has a thickness of about 30 to 800 microns,
Of these, polyvinylidene chloride film (intermediate layer) 4
The thickness is about 5 to 90 microns. The polyolefin layer 7 interposed between the two three-layer films 3 and 6 and the polyolefin layer 8 interposed between the polycarbonate film 9 each have a thickness of 5 to 90 microns. Furthermore, the polycarbonate film 9 is relatively thin, having a thickness of about 10 to 90 microns, and is less than 1/5 of the thickness of the entire composite sheet. In addition, metal vapor deposition film 1
0 is usually 1 micron or less.

As mentioned above, since the container of the present invention is made of a composite sheet containing an ethylene-vinyl alcohol copolymer film, a polyvinylidene chloride film, and a metallized film, it is a particularly important element for food preservation. The gas barrier properties, moisture proof properties and aroma retention properties are greatly improved, and therefore, the food stored and sealed in the container A can be stored in good condition for a long period of time without spoiling or deteriorating. That is,
The container of the present invention, which is formed by combining an ethylene-vinyl alcohol copolymer film, a polyvinylidene chloride film, and a metal-deposited film, can be used both in the cold and dry winter months and in the hot and humid summer months.
Maintains excellent oxygen gas barrier properties and moisture resistance,
To effectively protect stored food from rancidity and deterioration.
In addition, even when pressure sterilized at a high temperature of 100°C or higher or heated by immersing in boiling water, it blocks oxygen and moisture, prevents food from going rancid, and protects the food.

Further, as a composite sheet that is a constituent material of the container of the present invention, a three-layer film 3 having polyolefin layers 2, 2 on both sides of an ethylene-vinyl alcohol copolymer film 1 as shown in the illustrated embodiment,
Since it mainly uses a laminate of a polyvinylidene chloride film 4 and a three-layer film 6 having polyolefin layers 5, 5 on both sides, it has an appropriate thickness that is neither too thin nor too thick for a food storage container. In addition, as a composite sheet, the polyolefin layers 2, 2, 5, contained in both three-layer films 3, 6,
5 occupies most of the total thickness, and therefore it can be molded in the same way as a polyolefin molded product. Furthermore, if the polyolefin layer is exposed on the inside of the container, there is no risk of contaminating the food even if it comes into direct contact with the food, and the polyolefin layer also has excellent oil resistance, so it can be used as a food storage container. It is hygienic and suitable.

Furthermore, this container has excellent heat resistance and cold resistance, and the composite sheet does not delaminate even after high temperature sterilization under pressure of 100 degrees Celsius or higher, and does not deteriorate even after high temperature sterilization. It also has the advantage that it can be placed in a microwave oven in its stored state or heated by immersing it in boiling hot water.

In this way, the present invention is a food storage container made of a composite sheet of thermoplastic synthetic resin film that has excellent properties required for food protection and long-term preservation, especially gas barrier properties, moisture proofness, and flavor retention. It has great practical effects, and can be mass-produced at a lower cost than aluminum containers, and can be provided at a lower cost. In addition, since there is a metal-deposited film on the outer surface of the container, it gives a hard feel even if it is thin, giving it the feel of a metal plate, and the metallic luster gives it the appearance of a metal foil product. Presentation is good.

The lid B for the container A is preferably one in which a polyolefin film 12 is laminated on one side of an aluminum foil 11. In particular, it is preferable to use the same type of polyolefin film 12 as the polyolefin layer 5 on the inner surface of the container A. suitable. In addition to the above-described materials, the lid B may be made of the same material as the composite sheet of which the container A is made, but which is thinner. In any case, after the food is placed in the container A, the lid B may be sealed with the polyolefin film surface of the lid B against the polyolefin layer at the opening edge of the container A by heat-sealing means.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic sectional view of a state in which food is contained and sealed, Fig. 2 is an enlarged sectional view of a part of the front view, and Fig. 3 is a structure of the container. FIG. 2 is an enlarged cross-sectional view of a portion of the composite sheet separated into constituent films. Explanation of symbols, 1... Ethylene-vinyl alcohol copolymer film, 2, 2... Polyolefin layer, 3... First three-layer film, 4... Polyvinylidene chloride film, 5, 5... Polyolefin layer, 6...Second three-layer film.

Claims (1)

[Scope of utility model registration request] A food storage product made of a composite sheet made by laminating an ethylene-vinyl alcohol copolymer film with a three-layer film having polyolefin layers on both sides, a polyvinylidene chloride film with polyolefin layers on both sides, and a metal-deposited film. 1. A food storage container, which is formed so that the metal vapor-deposited film is present on the outer surface of the container.