JPH02205575A - Cooked food sealing container - Google Patents

Abstract

PURPOSE:To obtain a container capable of retort sterilization of even the cooked food requiring a high temperature reheating in as-sealed condition by forming a synthetic resin layer consisting mainly of epoxy resins and the polypropylene resins modified with unsaturated carboxylic acid or its acid anhydride on a linear copolymerized polyester resin layer. CONSTITUTION:The synthetic resin layer 6 consisting mainly of epoxy resins and the polypropylene resins modified with unsaturated carboxylic acid or its acid anhydride is formed entirely over the inner surface of the container body 2 of an aluminum foil container 1 and the upper surface of its flange 3 with a linear copolymerized polyester resin layer 5 interposed therebetween. A container 1 filled with cooked food can be closed by a lid 7 which is heat sealed to the flange 3 and, even when the container is unpacked and the food ia reheated at a high temperature by an electric oven, etc., the resin layer 6 will not discolor. The resin layer 5 has good adhesive property to the aluminum foil and epoxy resins and, therefore, the occurrence of pinholes and cracks can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION This invention relates to a container for sealing cooked food that is to be reheated and eaten.

BACKGROUND ART Conventionally, retort foods have been well known in which cooked foods such as curry stew are placed in a plastic bag such as polyethylene, sealed, and heated and sterilized in a retort to make it completely sterile. This retort food is reheated in the bag in boiling water immediately before being served at the dining table.

By the way, among cooked foods, there are some foods such as gratin and hamburgers that need to be heated to the extent that the surface is slightly browned when reheating. Such foods must be heated to a high temperature of around 250°C in an electric oven or toaster oven, so even if plastic bags such as those used for retort food can withstand the temperature of boiling water, It does not have heat resistance against. For this reason, gratin, hamburgers, etc. have traditionally been placed in metal containers such as aluminum. However, since it cannot be sealed like a plastic bag, retort sterilization cannot be performed, and the product has no choice but to be frozen for long-term storage. Foods frozen in this way must be kept frozen during the product distribution process and even after purchase, and must be thawed before consumption.Furthermore, they tend to taste worse than retort foods. be.

Therefore, the present applicant first proposed a sealed container for cooked food that can be sealed and retort sterilized without freezing even if the cooked food requires high-temperature reheating (Utility Application No. 61-1).
No. 88944).

This proposed container is an aluminum foil container with a flange, and a synthetic resin coating layer made of epoxy resin and polypropylene resin modified with an unsaturated carboxylic acid or its acid anhydride is formed over the entire inner surface of the container body and the top surface of the flange. It is something that is given to us.

Problems to be Solved by the Invention Flanged aluminum foil containers are formed by deep drawing, but if they have a synthetic resin coating layer as described above, there is a risk that this will peel off during forming. It shouldn't be.

The same thing can also be said during heat sterilization using a retort.

Although there is no problem with the above point in the proposed container, the epoxy resin contained in the synthetic resin coating layer has good moldability, but it hardens the coating layer, so it is difficult to find it in order to mold the container. Doing so may cause pinholes or cracks.

An object of the present invention is to provide a sealed container for cooked food that can be sealed and retort sterilized without freezing even if the cooked food requires high-temperature reheating, and that has improvements in the above points. be.

Means for Solving the Problems In order to achieve the above object, the sealed container for cooked food according to the present invention is a container made of aluminum foil with a flange. A synthetic resin coating layer made of a composition whose main components are an epoxy resin and a polypropylene resin modified with an unsaturated carboxylic acid or its acid anhydride is formed through the ground layer.

In this specification, parts are by weight.

The thickness of the aluminum foil is preferably 40 to 150J.

This is because if the strength is less than 40IIIN, the strength is insufficient, and if it exceeds 150q, it becomes difficult to mold and increases the cost.

In the linear copolymerized polyester resin, 95 to 50 mol% of the acid component is terephthalic acid residue, and 20 to 50 mol% of the alcohol component is terephthalic acid residue.
70 mol% is ethylene glycol residue. The remaining 5 to 50 mol% of the acid components are residues of adipic acid, sebacic acid, other aliphatic dibasic acids, isophthalic acid, orthophthalic acid, diphenyl dicarboxylic acid, and other aromatic dibasic acids. The remaining 80 to 30 mol% of the alcohol component is 1,2-
These are glycol residues such as propylene glycol, 1°3-propylene glycol, 1,3-butanediol, diethylene glycol, triethylene glycol, dipropylene glycol, and neopentyl glycol.

Note that an oxy residue such as oxybenzoic acid may be present. The linear copolymerized polyester resin uses polyethylene terephthalate as a starting material, adds triethylene glycol and other diols, and performs depolymerization and recondensation reactions by transesterification with the diols, resulting in polyethylene. Also included are modified ether type polyesters in which ethylene glycol in terephthalate is partially replaced with diols, and linear block copolymerized polyesters.

The method for forming the linear copolyester resin base layer is as follows:
Any method such as gravure coating or roll coating may be used.

Specific examples of epoxy resins include reaction products of epichlorohydrin and polyhydric phenols such as bisphenol A. Polyisocyanates are preferred as curing agents for epoxy resins, and specific examples include xylene diisocyanate, 2,4- or 2,6-dolylene diisocyanate, 4,4-diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, or these. Examples include adducts of isocyanates, block-type isocyanates, and polymers thereof.

The blending ratio of the epoxy resin and the polypropylene resin modified with an unsaturated carboxylic acid or its acid anhydride is preferably 30 to 90 parts for the former and 5 to 50 parts for the latter. If the amount of epoxy resin is less than 30 parts, the synthetic resin coating layer will melt upon reheating at high temperatures, and if it exceeds 90 parts, the thermal adhesion will be insufficient. On the other hand, if the amount of modified polypropylene is less than 5 parts, thermal adhesion will be insufficient and the sealability of the container will be impaired, and if it exceeds 50 parts, problems will arise in heat resistance.

Examples of polypropylene resins modified with unsaturated carboxylic acids or acid anhydrides include polypropylene resins graft copolymerized with maleic anhydride.

A composition of an epoxy resin and a polypropylene resin modified with an unsaturated carboxylic acid or its acid anhydride is made into a paint using cellosolve acetate, cellosolve, methyl ethyl ketone, toluene, etc. as a solvent, and is applied to a linear copolyester polyester base layer. By applying the resin, a synthetic resin coating layer is formed.

Note that some foods contain salt, acidic seasonings, or spices that easily corrode aluminum, so a zirconium-containing synthetic resin base layer is interposed between the aluminum foil and the linear copolymerized polyester resin base layer. It is preferable to let

Function According to the present invention, since the container is made of aluminum foil, it has heat resistance to high temperatures when used in an electric oven or toaster oven.

In addition, a synthetic resin coating layer made of a composition mainly composed of epoxy resin and polypropylene resin modified with unsaturated carboxylic acid or its acid anhydride is formed on the entire inner surface of the container body and the upper surface of the flange. By heat-sealing the lid to the flange of the container, it is possible to seal the container filled with cooked food, and even if the container is opened and the cooked food is reheated at high temperature in an electric oven, the synthetic resin coating remains intact. The layer will not discolor or melt and will not spoil the beauty of the food container. This is because epoxy resin has high heat resistance, and polypropylene resin modified with unsaturated carboxylic acid or its acid anhydride has excellent heat adhesive properties, so the synthetic resin coating layer has both of these properties. This is because it has both.

Linear copolymerized polyester resin is soft and has good adhesion to both aluminum foil and epoxy resin, so it prevents pinholes and cracks from forming during searching.

Example Embodiments of the invention will be described below with reference to the drawings.

The container (1) consists of a container body (2) and a flange (3) provided at the upper end of its peripheral wall. This container (1) consists of 60 parts of epoxy resin, 30 parts of modified polypropylene resin as main components, and a linear copolymerized polyester resin base layer (5) on one side of aluminum foil (4) with a thickness of 120 μm. A laminated material having a synthetic resin coating layer (6) formed by applying 4 g/m2 (in terms of solid content) of a composition consisting of 3 parts of polyisocyanate resin to a substrate is punched into a predetermined shape, and then the synthetic resin coating layer is (6) is the container body (2
) is formed by deep drawing so that it is on the inside.

As the modified polypropylene resin, maleic anhydride 0.
A maleic anhydride modified polypropylene resin containing 8 parts was used.

The lid (7) is made of a laminated material in which an unstretched polypropylene film (9) with a thickness of 50/ff is laminated as a heat sealing material to an aluminum foil (8) with a thickness of 70/ff.

The following experiment was conducted on the container (1). In other words, 180μ of cooked gratin is placed in the container body (2).
After filling, cover the lid (7) and cover the periphery with the container (1).
The flange (3) was heat sealed. Next, this container containing gratin (1) was subjected to retort sterilization treatment at 120° C. for 30 minutes.

Thereafter, M (7) was removed, and the container containing gratin (1) was placed in a toaster oven and heated at about 250°C for 15 minutes. As a result, the surface of the gratin had dark brown marks, but no change was observed in the synthetic resin coating layer (6) of the container (1).

Effects of the Invention According to the sealed container for cooked foods of the present invention, even cooked foods that require high-temperature reheating can be sealed and retort sterilized without freezing, and the container has good moldability. Therefore, pinholes and cracks do not occur when digging.

[Brief explanation of the drawing]

The drawing is a vertical sectional view of a container and a lid showing an embodiment of the invention. (1)... Container, (2)... Container body, (3)...
・Flange, (4)...Aluminum foil, (5)...
- Linear copolymerized polyester resin base layer, (6)...synthetic resin coating layer. Above 1: Container 2: Container body 6: Synthetic resin coating layer Procedural amendment case representation 1999 Patent No. 26286 2 Name of invention Container for sealing cooked food (method) % formula % Contents of amendment 1, On page 11 of the specification, lines 14-15, “The drawings are...
1(a) is a vertical sectional view of a container showing an embodiment of the present invention, and FIG. 1(b) is a vertical sectional view of a lid placed on the container of FIG. 1(a). ” he corrected. 3 Relationship with the case of the person making the amendment

Claims (1)

[Claims] In the flanged aluminum foil container (1), the entire inner surface of the container body (2) and the top surface of the flange (3) are covered.
A synthetic resin coating layer (6) consisting of a composition mainly composed of an epoxy resin and a polypropylene resin modified with an unsaturated carboxylic acid or its acid anhydride is formed through a linear copolymerized polyester resin base layer (5). A sealed container for cooked food.