JPH08207970A - Hermetically-sealed food container for reheating - Google Patents

Abstract

PURPOSE: To provide a hermetically-sealed food container for reheating which allows retort sterilization, is easily wrapped to provide easy peelability, is highly resistant to heat, therefore allows hereating over direct fire, and exhibits excellent quality when contents are taken out after reheated. CONSTITUTION: In a hermetically-sealed food container with a flange for use in reheating, the entire contents-filling area of its aluminum foil container main body is coated with polyamide-imide-based, heat-resistant resin 2, and, further, the upper surface of its flange and the area which is, when contents are filled into it, higher than the surface of the contents are coated with a synthetic resin layer 3 comprising as a main component a resin composition consisting of epoxy resin and unsaturated carboxylic acid or its anhydride.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a simple packaged food sealing container that allows cooked food to be distributed at room temperature and can be reheated by direct heat when eating, and has excellent removability of contents.

[0002]

2. Description of the Related Art With the progress of packaging technology, freezing or refrigeration technology, and the spread of convenience stores,
Many types of prepared foods are marketed, not only solid foods, but liquids such as curry, stew and soup that require reheating during meals and fluid foods. Many of these are polyethylene, polypropylene, heat-sealed in a bag of aluminum foil laminate, etc., to impart normal temperature flowability by heat sterilization in a retort, and soak in hot water as a bag at meal time, It is used by reheating.

By the way, some cooked foods, such as gratin and hamburger, need to be heated to the extent that the surface is slightly scraped when reheating. Such foods should be placed in an open fire, electric oven or toaster oven.
Since it has to be heated to a high temperature of about 0 ° C, plastic bags such as those used for ordinary retort food do not have the heat resistance against the above high temperatures even if they can withstand the boiling water temperature. Foods such as gratin and hamburger that require high temperature heating were placed in a metal container such as aluminum and then placed in a plastic bag or the like. However, since it cannot be completely sealed with this, the retort sterilization cannot be performed, and it was unavoidably unavoidable that it was frozen and marketed for long-term storage. Foods frozen in this way must be kept frozen during the course of product distribution and after purchase, and must be thawed and then heated before being eaten. It is necessary to prevent the taste from falling compared to food.

As a countermeasure against this, the present inventors have previously made an epoxy resin coating layer on the entire inner surface of the container body in a flanged aluminum foil container, and the epoxy resin and unsaturated carboxylic acid or its anhydride on the upper surface of the flange. We proposed a cooked food sealing container in which a synthetic resin coating layer containing a polyolefin resin modified with a product as a main component is formed (Actual Kaihei 2-40016). Compared to plastic bags for retort sterilization, this food-sealing container is a simple package that has easy peeling properties, can be distributed at room temperature, has significantly improved heat resistance, and can be heated by an electric oven or oven toaster. Although it was a sealed container with some effect, users can perform simple cooking at higher temperatures, for example, reheating with a direct fire such as a gas stove, and food after reheating from the container It has been desired to develop a closed container that can be easily taken out.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a conventional food-sealing container, which can hermetically package cooked food, sterilize it by retort and distribute it at room temperature, is simple and has easy peeling property. A further object is to develop a sealed food container for reheating, which has higher heat resistance, can be reheated by direct flame, and has excellent removability of contents after reheating.

[0006]

According to the present invention, the entire inner surface of the aluminum foil container body (in the present invention, refers to both the inside of the container and the upper surface of the flange portion) is a heat-resistant resin based on polyamideimide (hereinafter referred to as a heat-resistant resin). , A heat-resistant resin), and when the upper surface of the flange and the contents are further filled, the area above the upper surface is composed of an epoxy resin and a polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof. A food container for reheating with a flange, which is laminated and coated with a synthetic resin layer containing a resin composition (hereinafter, referred to as an adhesive resin composition) as a main component, and the entire inner surface of the aluminum foil container body is an adhesive resin composition. Is coated with a synthetic resin layer containing as a main component, and when the contents are filled, the heat-resistant resin is laminated and coated up to the part where the contents come into contact. Reheating food sealed container with a lunge. Flange coated with a synthetic resin layer containing an adhesive resin composition as a main component, when the content of the inner surface of the aluminum foil container is filled with the content, the heat-resistant resin is coated up to just above the contacting portion. Attached to one side of the reheated food sealed container and aluminum foil, a synthetic resin layer mainly composed of an adhesive resin composition is formed, and when the contents are filled, heat resistance is applied to the parts corresponding to the parts to which the contents come into contact. To develop a method for manufacturing a sealed food container for reheating with a flange, which comprises laminating resins, punching the laminated material into a predetermined shape, and then deep-drawing so that the resin laminating surface faces inward. The above object was achieved by.

In the present invention, the thickness of the aluminum foil used is preferably 40 to 150 μm. If it is less than 40 μm, the shape retention as a container is insufficient, while
This is because if it exceeds 0 μm, not only the cost becomes high but also the formability is deteriorated. There is no need to limit the type of the epoxy resin as a constituent component of the adhesive resin as long as it has low toxicity and heat resistance. For example, in addition to bisphenol A type epoxy resin obtained from epichlorohydrin and bisphenol A, bisphenol F type epoxy resin , Reaction products with polyhydric phenols such as novolac type epoxy resins and fatty acid modified epoxy resins. As a curing agent for the epoxy resin, a polyisocyanate compound that does not generate toxic formalin is preferable, and specific examples thereof include paraphenylene diisocyanate, 2,4- or 2,6-toluene diisocyanate, 4,4-diphenylmethane diisocyanate, Examples include hexamethylene diisocyanate, adducts thereof, block type isocyanates, and polymers thereof.

The polyolefin resin modified with unsaturated carboxylic acid or its anhydride is a polypropylene resin graft-copolymerized with itaconic acid, maleic acid, fumaric acid or itaconic anhydride, maleic anhydride, From the viewpoint of adhesion to aluminum, maleic anhydride containing 0.05 to 5% is preferable. As the polyolefin resin, polyethylene resin is preferably used in addition to polypropylene resin. The compounding ratio of the polyolefin resin modified with the unsaturated carboxylic acid or its anhydride to the epoxy resin is preferably 50 to 90% by weight of the former and 5 to 50% by weight of the latter. This is because if the epoxy resin content is less than 50% by weight, the adhesive resin coating layer is likely to be discolored or melted when reheated at a high temperature, while if the modified polyolefin content is less than 5% by weight, the thermal adhesiveness becomes insufficient.

As the heat-resistant resin, considering the coating property, for example, a heat-resistant resin is used, which is based on polyamide imide having a molecular weight of 4,000 to 5,000 and which is mixed with 5 to 20% by weight of an epoxy resin. In producing the container body, for example, 2 to 10 g of a heat resistant resin is applied to the other side of an aluminum foil (one side may be coated with a heat resistant polyamide imide resin or a polyester resin or the like). m ² coating, and then ² to 10 g / m ^{2 of} adhesive resin was applied over the entire circumference corresponding to the flange when the container was formed (applied to the entire circumference of the flange and up to about 5 mm inside the container). ) Dried. This was punched into a blank, and deep drawing was performed so that the coating layer was on the inside of the container, whereby a reheated food sealed container could be manufactured.

It should be noted that, after coating the entire surface with an adhesive resin, a sealed food container in which the inner surface of the container is coated with a heat-resistant resin, or the heat-resistant resin is coated only in the contact portion when the contents are filled in the container. The food-sealed container in which the flange portion and the non-contact portion of the contents are coated with the adhesive resin can be manufactured according to the above method.

[0011]

The sealed food container with a flange of the present invention is an aluminum foil container whose inner surface is coated with a heat-resistant resin and whose flange portion is coated with an adhesive resin having high heat resistance. It has heat resistance not only to the toaster but also to high temperatures such as when using direct fire or reheating. Furthermore, since a resin coating based on polyamide-imide with good releasability is applied, it is a container that allows easy removal of gratin and curry that are difficult to remove after reheating.

Since the flange of the container is coated with an adhesive resin having a good heat-sealing property, the container filled with the cooked food can be sealed by heat-sealing the lid, and the container can be opened. Even if the cooked food is reheated to a high temperature by direct fire or electric oven, not only the heat-resistant resin coating layer on the entire inner surface of the container but also the adhesive resin coating layer on the flange is discolored or melted. It does not spoil the aesthetics.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. Example A container is composed of a container body and a flange provided at the upper end of its peripheral wall. This container has 4 g / m ^{2 of} a γ-butyrolactone-xylene solution of a highly heat-resistant resin in which 10 wt% of an epoxy resin containing a curing agent in a polyamideimide having a molecular weight of 4500 is mixed on one surface of an aluminum foil 1 having a thickness of 40 μm.
It was painted (in terms of solid content) and the other surface was coated with an anticorrosion coat.
On the coated surface, an epoxy resin containing a block-type isocyanate as a curing agent and a maleic anhydride 1.0% by weight graft polymerization over the entire surface of a portion which becomes a flange when a container is formed and a portion 5 mm below the side surface from the flange. Modified Polypropylene Resin Mixture (70: 3
0) was applied at 4 g / m ² , dried and punched out to produce a blank.

The blank was subjected to deep drawing so that the coating layer was on the inner surface of the container body to obtain a sealing container body having an internal volume of 200 cc. Separately from this, a lid material was prepared by laminating an unstretched polypropylene film having a thickness of 60 μm on an aluminum foil having a thickness of 60 μm. The container was filled with gratin using a white sauce almost completely in the high heat resistant resin coating portion, and the lid member was heat-sealed. This is 120 ℃, 3
The retort sterilization was performed for 0 minutes, and it was left at room temperature for about 1 month. The result did not change the contents. This product was heated for 3 minutes on a gas stove to remove a lid, and the kog was easily peeled off, and a highly sticky gratin sauce could be easily taken out without easily adhering. In particular, although the gratin had a burnt eye, no bad odor was generated from the container, and no yellowing of the resin surface was observed.

Comparative Example An epoxy resin containing a block-type isocyanate as a curing agent and a modified polypropylene resin graft-polymerized with 1.0% by weight of maleic anhydride were formed on the other surface of an aluminum foil, which was anticorrosion coated on the same surface as in Example. Mixture (70: 3
0) was used as a blank coated with 4 g / m ²
Put the contents in the same way as in the example, sterilize by retort, and
It was left at room temperature for a month, but the contents did not change. When this was heated with a gas stove to the extent that a little burnt was generated, no foul odor was generated from the container and the resin surface did not change, but the burnt part adhered to the container and became difficult to peel off.
The highly sticky gratin sauce also adhered to the wall of the container and was difficult to remove.

[0016]

EFFECTS OF THE INVENTION In the hermetically sealed food container for reheating according to the present invention, the inner surface of the container to be heated is coated with a heat-resistant resin composition based on polyamideimide having good heat resistance and peelability, and a lid material is used. Since the upper surface of the flange to be heat-sealed is coated with an adhesive resin layer whose main component is a resin composition composed of a highly heat-resistant epoxy resin and a heat sealant such as polyolefin and a highly adhesive modified polyolefin resin, In addition, the container can be reheated not only in an electric oven but also in an open flame, which simplifies the heating means, and such reheating also causes an offensive odor and discoloration of the resin coating layer. There is no such thing.

Further, since heat sealing with a lid material capable of sterilizing the retort is also possible and the cooked food can be distributed at room temperature, it does not require freezing and thawing as compared with frozen food and is easy to handle. Not only that, but it also has the advantage of little change in taste. In addition, the heat seal has high productivity as a simple package and has an easy peeling property of the packaged product, which can sufficiently meet the demands of the producer and the consumer. A further major feature of the container of the present invention is that even a highly sticky filling material can be easily taken out, which is a great advantage in that it can be reheated by an open flame.

[Brief description of drawings]

FIG. 1 is a sectional view of an example corresponding to claim 1 of the present invention.

FIG. 2 is a sectional view of an example corresponding to claim 2 of the present invention.

FIG. 3 is a sectional view of an example corresponding to claim 3 of the present invention.

[Explanation of symbols]

1 Aluminum foil 2 Heat-resistant resin layer based on polyamide-imide 3 Adhesive resin layer containing epoxy resin and modified polyolefin resin as main components 4 Filled contents

Claims (5)

[Claims] 1. The entire inner surface of the aluminum foil container body,
A resin composition which is coated with a heat-resistant resin based on polyamide-imide, and when the upper surface of the flange and the contents are further filled, an epoxy resin and an unsaturated carboxylic acid or an acid anhydride thereof at the upper surface and above. A sealed food container for reheating with a flange, which is laminated and coated with a synthetic resin layer containing as a main component. 2. The entire inner surface of the aluminum foil container body,
Epoxy resin and is coated with a synthetic resin layer whose main component is a resin composition composed of a polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof, and the content when the content is further filled is A sealed food container for reheating with a flange that is laminated and coated with a heat-resistant resin based on polyamide-imide up to the part that comes into contact. 3. The content of the inner surface of the aluminum foil container main body when the content is filled is coated with a heat-resistant resin based on polyamide-imide up to a portion slightly above the contacting portion, and slightly polymerized with it. The upper part and the flange part are coated with a synthetic resin layer whose main component is a resin composition consisting of an epoxy resin and a polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof. container. 4. A resin composition in which an epoxy resin is mixed in an amount of 5 to 20% by weight with respect to a polyamide-imide resin, which is a heat-resistant resin as a base, and a synthetic resin layer has an epoxy resin of 50 to 50% by weight.
The flanged reheating food product according to claim 1, which is a synthetic resin mainly composed of a resin composition comprising 95% by weight of a polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof in an amount of 50 to 5% by weight. Sealed container. 5. A synthetic resin layer mainly comprising a resin composition comprising an epoxy resin and a polyolefin resin modified with an unsaturated carboxylic acid or an acid anhydride thereof is formed on one surface of an aluminum foil, and the contents are A heat-resistant resin based on polyamide-imide is laminated on the portion corresponding to the portion where the contents come in contact with each other when filled, and the laminated material is punched into a predetermined shape, and then the resin laminated surface is deepened so that it is on the inside. A method for manufacturing a sealed food container for reheating with a flange, which comprises drawing.