JP6415306B2 - Container for electric heating - Google Patents

Description

  The present invention relates to containers for packaging foods such as liquid foods such as soup and noodle soup, cooked foods such as curry, stew and gratin, and dessert foods such as pudding and water candy, and more particularly The present invention relates to a container in which food can be sterilized by energization heating after packaging.

When packaging food to be distributed at room temperature for a storage period of 3 months or more, (1) filling and sealing the pre-sterilized food in a sterilized barrier container in an aseptic environment, or (2 ) It is necessary to sterilize food that has not been sterilized by filling it in a barrier container and then sterilizing it.
The sterilization method of (1) above is that food is sterilized by heating through a heat exchanger such as a plate method, a tube method, or a surface scraping method, or the food's resistance heat (Joule heat) is applied directly to the food. ) And then sterilized by electrical and thermal sterilization, and then filled and sealed in a chemically and physically sterilized container in an aseptic filling line (aseptic line). However, aseptic filling lines are generally limited to liquid foods such as fruit juice and noodle soup, and fluid foods such as jams and soups. It is suitable for mass production, but not suitable for small-scale production.
On the other hand, the sterilization method of (2) described above is to sterilize food by filling it in a container and then sterilizing it by heating and pressurizing with steam or hot water. Many are used. In such a heat and pressure sterilization method, since it is necessary to heat the container for a predetermined time so that the center temperature of the container becomes a predetermined temperature, the time is shortened by setting the temperature to 120 to 130 ° C. and heating. However, there are disadvantages that the nutrients of the food itself are deactivated, and that the color is burnt and the flavor is impaired.
In the sterilization methods (1) and (2), there are disadvantages, but there are also many advantages. For example, in the case of energization and heat sterilization, the food itself is heated and sterilized. The heat and pressure sterilization after packaging can be sterilized regardless of the type of contents packed in the container, so by combining these two methods, It is thought that it can have the advantages of both.

  Patent Document 1 below discloses a combination of a resin-made container body and a conductive lid material as a container capable of conducting heat sterilization of filled and packaged food.

Japanese Patent Laid-Open No. 11-268777

  However, in the energization heating container shown in Patent Document 1, the container body is made of resin because the container needs insulation, but the resin container body is compared with a container including a metal can or metal foil. Since the gas barrier property and the ultraviolet barrier property are inferior, the food is likely to be oxidized and discolored due to long-term storage at normal temperature after sterilization by heating. Further, in the case of the current heating container of Patent Document 1, the combination of the resin container main body and the conductive member is complicated, and its production also requires a complicated process.

  The present invention has been made in view of the above-mentioned problems, and has a high gas barrier property and ultraviolet barrier property in order to enable long-term storage of the food as the contents. The object is to provide a container that can be sterilized by heating with electricity.

  In order to achieve the above object, the present invention comprises the following aspects.

1) A container body made of a laminate in which a resin layer is laminated on both sides of a metal foil and containing food as a content, and a laminate body in which a resin layer is laminated on both sides of the metal foil and on a flange portion of the container body And a metal foil inner surface exposed portion and a metal foil outer surface exposed portion are formed on the container body and the lid material by partially removing the inner resin layer and the outer resin layer, respectively. An electrically conductive heating-compatible container in which the metal foil inner surface exposed portion of the container main body and the metal foil inner surface exposed portion of the lid member are formed at positions that can be electrically connected via food.

2) The metal foil inner surface exposed portion of the lid material is formed in a portion of the lid material covering the opening of the container main body, and the area of the metal foil inner surface exposed portion is 30 to the area of the opening of the container main body. The container for electric heating according to 1), which is 100%.

3) The metal foil inner surface exposed portion of the container main body is formed on the bottom wall portion of the container main body, and the area of the metal foil inner surface exposed portion is 30 to 100% of the area of the bottom wall portion. Or the container for electric heating of 2).

4) Any one of the above 1) to 3), wherein at least the metal foil inner surface exposed portion of the metal foil inner surface exposed portion and the metal foil outer surface exposed portion of each of the container main body and the lid member is covered with a conductive coating. Container for electric heating.

5) The conductive heating-compatible container according to 4) above, wherein the conductive coating is formed of a part of the conductive coating layer formed in advance on the inner surface or outer surface of the metal foil.

6) The conductive heating-compatible container according to 4) above, wherein the conductive film is formed by subjecting only the exposed surface of the metal foil or the exposed surface of the metal foil to the conductive film.

  According to the container for electric heating as described in 1) above, each of the container body and the lid material is made of a laminate including a metal foil, so that high gas barrier properties and ultraviolet barrier properties can be obtained, and food deterioration due to long-term storage hardly occurs. In addition, by energizing the container main body and the exposed portion of the metal foil on the lid member, electricity flows to the food and resistance heat is generated, so that the food can be sterilized in a short time. Moreover, according to the container for electric heating as described in 1) above, the structure necessary for electric heating is such that the inner and outer surfaces of the metal foil are partially exposed by removing a part of the inner and outer resin layers of the container main body and the lid material. Therefore, manufacturing is easy.

  According to the container for electric heating according to 2) above, the area of the exposed portion of the metal foil inner surface of the lid material is 30 to 100% of the area of the opening of the container main body. Sterilization becomes possible, and since the metal foil inner surface exposed portion is not formed in the seal portion, the sealing performance of the container is not impaired.

  According to the container for electric heating according to 3) above, the area of the exposed portion of the inner surface of the metal foil of the container body is 30 to 100% of the area of the bottom wall of the container body. Electric current heating sterilization becomes possible. In addition, when the container body is formed by press-molding a laminated sheet, a rounded portion is usually formed between the bottom wall and the side wall. Since the exposed portion of the metal foil is not formed in the above-mentioned rounded portions, material destruction and pinholes are unlikely to occur during press molding.

  According to the container 4 for energizing and heating described above, since the metal foil inner surface exposed portion of each of the container main body and the lid member, or the metal foil inner surface exposed portion and the metal foil outer surface exposed portion are covered with the conductive film, The exposed portion can be effectively prevented from being corroded by food or the external environment, and the energization function is not impaired.

  According to the container 5 for electric heating as described above, since the conductive coating is formed of a part of the conductive coating layer formed in advance on the inner surface or the outer surface of the metal foil, the coating can be easily formed.

  According to the container for electric heating according to 6), since the conductive coating is formed by conducting the conductive coating only on the exposed portion of the inner surface of the metal foil or the exposed portion of the outer surface of the metal foil, there is no waste in forming the coating. The cost can be reduced, and the properties and thickness of the coating can be finely adjusted.

It is a vertical sectional view of the energization heating correspondence container concerning a 1st embodiment of this invention. It is a top view of the same electricity heating corresponding container. The layer structure of the container main body of the same electricity heating corresponding container is shown, Comprising: (a) is an expanded sectional view of a normal part, (b) is an expanded sectional view of the part from which the metal foil is exposed. The layer structure of the cover material of the same electricity heating corresponding container is shown, Comprising: (a) is an expanded sectional view of a normal part, (b) is an expanded sectional view of the part from which the metal foil is exposed. It is a vertical sectional view of an energization heating correspondence container concerning a 2nd embodiment of this invention. The layer structure of the container main body of the same electricity heating corresponding container is shown, Comprising: (a) is an expanded sectional view of a normal part, (b) is an expanded sectional view of the part from which the metal foil is exposed. The layer structure of the cover material of the same electricity heating corresponding container is shown, Comprising: (a) is an expanded sectional view of a normal part, (b) is an expanded sectional view of the part from which the metal foil is exposed. It is a figure which shows sequentially the manufacturing process of the container main body of the electricity heating container by this invention. It is a figure which shows sequentially the manufacturing process of the cover material of the electricity heating container by this invention.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

<First Embodiment>
1 to 4 show a first embodiment of the present invention.
The container for electric heating according to this embodiment includes, for example, liquid food such as soup and noodle soup, cooked food such as curry and stew, and dessert food such as pudding and water candy. The container can be stored for a long period of time and can be sterilized by energization heating after packaging.
As shown in FIGS. 1 and 2, the energization heating container (1A) includes a cup-shaped container body (2) in which food (C) is stored and a container body so as to cover the opening of the container body (2). The cover member (3) is heat sealed to the flange portion (2a) of (2). The food (C) is filled in the container main body (2) so that the container (1A) is filled without leaving any gaps without being sterilized. The lid member (3) is formed with a knob (3a) that protrudes radially outward from a portion of the outer peripheral edge of the outer circumferential portion and is picked by a finger when the lid member (3) is peeled and opened. Yes.

  The container body (2) includes a metal foil (21), a heat-sealing resin layer (22) laminated on the inner surface of the metal foil (21), and an outer resin layer (23) laminated on the outer surface of the metal foil (21). ) Is formed by press molding. The press forming of the laminated sheet (20) is performed by cold forming such as deep drawing forming or stretch forming. The inner surface of the metal foil (21) is covered with a conductive film (24).

  The lid (3) is a metal foil (31), a heat-sealing resin layer (32) laminated on the inner surface of the metal foil (31), and a heat-resistant resin layer laminated on the outer surface of the metal foil layer (31). It is formed by cutting a laminated sheet (30) made of (33) into a predetermined shape and size. The inner surface of the metal foil (31) is covered with a conductive film (34). The heat resistant resin layer (33) is made of a resin having a melting point of 20 ° C. or more higher than that of the resin constituting the heat sealable resin layer (32).

  The container main body (2) and the lid (3) are partially removed from the heat-sealing resin layers (22) and (32), the outer resin layer (23), and the heat-resistant resin layer (33). The metal foil inner surface exposed portions (21A) (31A) and the metal foil outer surface exposed portions (21B) (31B) are respectively formed. The metal foil inner surface exposed portion (21A) of the container body (2) and the metal foil inner surface exposed portion (31A) of the lid member (3) are formed at positions that can be electrically connected via the food (C). ing.

The metal foil inner surface exposed portion (21A) of the container body (2) needs to be energized and heated while facing the metal foil inner surface exposed portion (31A) of the lid (3) through the food (C). Usually, it is formed in the bottom wall part (2b) of the container body (2).
The shape of the exposed inner surface of the metal foil (21A) is not particularly limited, but the area is as large as possible for the contact area with the food (C), so that efficient heating with less heat unevenness is possible. It is preferably 30 to 100% of the area of the bottom wall portion (2b), and more preferably 80 to 100% in view of the efficiency of current heating.
On the other hand, the metal foil outer surface exposed portion (21B) of the container body (2) may be formed at any position as long as it is the outer surface of the container body (2), and the size and shape thereof are not particularly limited. In the container (1A) shown in FIGS. 1 and 2, a metal foil outer surface exposed part (21B) is formed at the center of the bottom surface (2b) of the container main body (2).
The metal foil inner surface exposed portion (21A) and the metal foil outer surface exposed portion (21B) may be formed at least one on the inner surface and the outer surface of the container body (2), but two or more of each may be formed. It doesn't matter.

The metal foil inner surface exposed portion (31A) of the lid member (3) is formed in the portion of the lid member (3) that covers the opening of the container body (2). Therefore, since the metal foil inner surface exposed portion (31A) is not formed in the seal portion of the lid member (3), the sealing performance of the container (1A) is not impaired.
The shape of the exposed inner surface of the metal foil (31A) is not particularly limited, but the area thereof is as large as possible in contact with the food (C), so that electric heating can be performed efficiently and with less heat unevenness. The area of the opening of the container body (2) is preferably 30 to 100%, and more preferably 80 to 100% in view of the efficiency of current heating.
On the other hand, the metal foil outer surface exposed portion (31B) of the lid member (3) may be formed at any position as long as it is the outer surface of the lid member (3), and the size and shape thereof are not particularly limited. In the container (1A) shown in FIGS. 1 and 2, a metal foil outer surface exposed portion (31B) is formed at the center of the outer surface of the lid member (3).
It is sufficient that at least one metal foil inner surface exposed portion (31A) and metal foil outer surface exposed portion (31B) are formed on the inner surface and the outer surface of the lid member (3), but two or more of each may be formed. I do not care.

FIG. 3 shows the layer structure of the container body (2) in detail.
As shown in FIG. 3 (a), the laminated sheet (20) constituting the container body (2) has an adhesive (25) on the inner surface of the metal foil (21) covered with the conductive film (24). ) Through which the heat-sealable resin layer (22) is laminated, and the outer resin layer (23) is laminated through the adhesive (25) on the outer surface of the metal foil (21).
Further, as shown in FIG. 3 (b), a part of the heat-sealing resin layer (22) is removed on the inner side of the bottom wall (2b) of the container body (2), thereby exposing the inner surface of the metal foil. (21A) is formed, and a part of the outer resin layer (23) is removed to form a metal foil outer surface exposed portion (21B). The exposed portion (21A) of the metal foil inner surface is covered with a conductive film (24).
For the metal foil (21), considering barrier properties, formability and workability, softened aluminum foil (including aluminum alloy foil), iron foil, stainless steel foil, copper foil, etc. are used. In consideration of electrical conductivity, thermal conductivity, cost, etc., aluminum foils such as A8079, A8021, A3003, etc. classified by JIS H4160, having a thickness of 50 to 200 μm are suitable. The thing of the range of 70-150 micrometers is preferable.
As the conductive film (24), tin plating, an oxidation treatment film such as boehmite and alumite, a chemical conversion treatment film, and a conductive resin coating film are used. The thickness of the tin plating layer is preferably 1 to 3 μm. Since an oxide film layer such as boehmite or anodized becomes more difficult to conduct electricity as the film thickness increases, the thickness of the boehmite layer should be 0.2 to 1 μm, and the thickness of the anodized layer should be 1 to 3 μm. preferable. Further, the chemical conversion treatment film can use a surface treatment agent for the metal foil (21), and includes, for example, chromate treatment for the metal foil (21) and non-chromium type chemical conversion treatment using a zirconium compound. . In the case of chromate treatment, an aqueous solution of the mixture of any one of 1) to 3) below is applied to the surface of the metal foil (21) that has been degreased and then dried.
1) A mixture containing phosphoric acid, chromic acid, and at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride.
2) Phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium (III) salts , Including a mixture.
3) phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium (III) salts And at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride.
The chemical conversion film preferably has a chromium adhesion amount of 0.1 to 50 mg / m ² , particularly preferably ² to 20 mg / m ² .
Furthermore, it is possible to use conductive resins such as polyacetylene resin, polypyrrole resin, and polyaniline resin, and it is also possible to use general-purpose resins mixed with conductive metals and carbon. That is, polypropylene resin, polyethylene resin, ethylene vinyl acetate copolymer resin, ABS resin, polyamide resin, polyester resin, epoxy resin, acrylic resin kneaded with powders and fibers of aluminum, iron, stainless steel, nickel, copper, carbon, etc. The film can be made of a urethane resin or the like, and the film thickness can be set to 1 to 50 μm. However, the film thickness is preferably set to 5 to 30 μm in consideration of conductivity and corrosion resistance to food.
For the heat-sealing resin layer (22) laminated on the inner surface of the metal foil (21), a versatile film such as a polypropylene resin film or a polyethylene resin film having a thickness of 10 to 200 μm, or a composite film thereof is used. However, in consideration of insulation and thermal efficiency, the thickness is preferably 20 to 100 μm.
For the outer resin layer (23) laminated on the outer surface of the metal foil (21), a polyethylene terephthalate resin film having a thickness of 12 to 50 μm, a polyamide resin film, a polybutylene naphthalate resin film, a polypropylene resin film, a polyethylene resin film, etc. These highly versatile films and composite materials of these are used.
As the adhesive (25), a two-component curable polyester polyurethane resin-based adhesive or a polyether polyurethane resin-based adhesive is used, and each film thickness is about 1 to 15 μm. In consideration of improvement in properties, the film thickness is preferably 2 to 5 μm.

FIG. 4 shows the layer structure of the lid member (3) in detail.
As shown in FIG. 4 (a), the laminated sheet (30) constituting the lid (3) has an adhesive (35) on the inner surface of the metal foil (31) covered with the conductive film (34). ), And a heat-resistant resin layer (33) is laminated on the outer surface of the metal foil (31) via an adhesive (35). The heat-sealing resin layer (32) is preferably composed of an easily openable resin.
Further, as shown in FIG. 4 (b), a part of the heat sealable resin layer (32) is removed from the container body opening covering portion of the lid (3) to expose the inner surface of the metal foil (31A). ) And a part of the heat-resistant resin layer (33) is removed to form the metal foil outer surface exposed portion (31B). The exposed portion (31A) of the metal foil inner surface is covered with a conductive film (34).
The metal foil (31) is made of a softened aluminum foil (including aluminum alloy foil), iron foil, stainless steel foil, copper foil, etc. in consideration of barrier properties, flexibility and workability. However, considering electric conductivity, thermal conductivity, cost, etc., aluminum foils of 8079, 8021, 3003, etc. classified by JIS H4160, with a thickness of 7 to 150 μm are suitable. Is preferably in the range of 30-100 μm.
As the conductive coating (34), an oxidation treatment film such as tin plating, boehmite, or alumite, a chemical conversion treatment film, or a conductive resin coating film is used. The thickness of the tin plating layer is preferably 1 to 3 μm. Since an oxide-treated film such as boehmite or anodized becomes difficult to conduct electricity as the film thickness increases, the thickness of the boehmite layer should be 0.2 to 1 μm, and the thickness of the anodized layer should be 1 to 3 μm. preferable. Further, the chemical conversion treatment film can use a surface treatment agent for the metal foil (31), and includes, for example, chromate treatment for the metal foil (31) and non-chromium type chemical conversion treatment using a zirconium compound. . In the case of chromate treatment, an aqueous solution of any one of the following 1) to 3) is applied to the surface of the metal foil (31) subjected to the degreasing treatment and then dried.
1) A mixture containing phosphoric acid, chromic acid, and at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride.
2) Phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium (III) salts , Including a mixture.
3) phosphoric acid, at least one resin selected from the group consisting of acrylic resins, chitosan derivative resins and phenolic resins, and at least one compound selected from the group consisting of chromic acid and chromium (III) salts And at least one compound selected from the group consisting of a metal salt of fluoride and a nonmetal salt of fluoride.
The chemical conversion film preferably has a chromium adhesion amount of 0.1 to 50 mg / m ² , particularly preferably ² to 20 mg / m ² .
Furthermore, it is possible to use conductive resins such as polyacetylene resin, polypyrrole resin, and polyaniline resin, and it is also possible to use general-purpose resins mixed with conductive metals and carbon. That is, polypropylene resin, polyethylene resin, ethylene vinyl acetate copolymer resin, ABS resin, polyamide resin, polyester resin, epoxy resin, acrylic resin kneaded with powders and fibers of aluminum, iron, stainless steel, nickel, copper, carbon, etc. The film can be made of a urethane resin or the like, and the film thickness can be set to 1 to 50 μm. However, the film thickness is preferably set to 5 to 30 μm in consideration of conductivity and corrosion resistance to food.
For the heat-sealing resin layer (32) laminated on the inner surface of the metal foil (31), a versatile film such as a polypropylene resin film or a polyethylene resin film having a thickness of 10 to 200 μm, or a composite film thereof is used. However, in consideration of insulation and thermal efficiency, the thickness is preferably 20 to 100 μm.
The heat-resistant resin layer (33) laminated on the outer surface of the metal foil (31) has a polyethylene terephthalate resin film, polyamide resin film, polybutylene naphthalate resin film, polypropylene resin film, polyethylene resin film having a thickness of 12 to 50 μm. A highly versatile film such as these and composite materials thereof are used.
As the adhesive (35), a two-component curable polyester polyurethane resin-based adhesive or a polyether polyurethane resin-based adhesive is used, and each film thickness is about 1 to 15 μm. In consideration of improvement in properties, the film thickness is preferably 2 to 5 μm.

<Second Embodiment>
5 to 7 show a second embodiment of the present invention.
The energization heating container (1B) according to this embodiment is the same as the energization heating container (1A) of the first embodiment shown in FIGS. 1 to 4 except for the following points.
That is, in the energization heating container (1B) of the second embodiment, the conductive film is not formed in advance on the inner surface of the metal foil (21) of the container body (2), and the exposed portion of the inner surface of the metal foil. Only (21A) is subjected to the conductive film treatment to form a conductive film (240). As the conductive coating (240), an oxidation treatment film such as tin plating, boehmite, or alumite is used. The thickness of the tin plating layer is preferably 1 to 3 μm. Since an oxide film layer such as boehmite or anodized becomes more difficult to conduct electricity as the film thickness increases, the thickness of the boehmite layer should be 0.2 to 1 μm, and the thickness of the anodized layer should be 1 to 3 μm. preferable.
Further, in the electric heating and heating container (1B) of this embodiment, the conductive film is not formed in advance on the inner surface of the metal foil (31) of the lid (3), and only the exposed portion of the metal foil inner surface (31A). In addition, a conductive coating (340) is formed by conducting a conductive coating treatment. As the conductive coating (340), an oxidation-treated film such as tin plating, boehmite, or alumite is used. The thickness of the tin plating layer is preferably 1 to 3 μm. Since an oxide-treated film such as boehmite or anodized is difficult to conduct electricity as the film thickness increases, the thickness of the boehmite layer should be 0.2 to 1 μm, and the thickness of the anodized layer should be 1 to 3 μm. preferable.

  Next, specific examples of the present invention will be described, but the present invention is not limited to these examples.

<Example 1>
In accordance with the processing procedure shown in FIG. 8, a container body (2) of the container for electric heating according to the present invention was produced.
That is, first, an A8079 annealed aluminum alloy foil (21) classified by JIS H4160 with a thickness of 120 μm, in which a conductive coating (not shown) is formed on both sides by performing a non-chromium chemical conversion treatment containing a zirconium compound (21). Was cut into a 300 mm square, and a polyester resin adhesive tape (4) cut to 40 mmφ with a thickness of 50 μm was affixed to the center of one side of the aluminum alloy foil (21) (see FIG. 8A).
Next, as shown in FIG. 8 (b), a two-component curable polyester polyurethane resin adhesive (not shown) is applied to the entire surface of the aluminum foil (21) to which the polyester resin adhesive tape (4) is attached. The coating was applied at a coating amount of 3 g / m ² , a polyester resin film (23) having a thickness of 25 μm was bonded, and left in a constant temperature bath at 40 ° C. for 3 days to cure the adhesive.
Next, cut the polyester resin film (23) around the part where the polyester resin adhesive tape (4) is pasted with a cutter knife and peel the polyester resin adhesive tape (4) together with the polyester resin film (23). Then, one surface of the chemically treated aluminum alloy foil (21) was partially exposed to form an exposed portion (21B) (see FIG. 8C).
Next, as shown in FIG. 8 (d), a polyester resin adhesive tape (5) having a thickness of 50 μm and cut to 60 mmφ is attached to the center of the other surface of the aluminum alloy foil (21). A liquid curable polyester polyurethane resin adhesive (not shown) is applied at an application amount of 3 g / m ² , a 30 μm-thick polypropylene resin film (22) is bonded together, and it is left still in a constant temperature bath at 40 ° C. for 3 days. The laminated sheet (20) having a three-layer structure was obtained by placing and curing the adhesive (see FIG. 8 (e)).
Next, as shown in FIG. 8 (f), the polypropylene resin film (22) around the portion where the polyester resin adhesive tape (5) is attached is cut with a cutter knife, and the polypropylene resin film (22) The polyester resin adhesive tape (5) was peeled off, and the other surface of the chemically treated aluminum alloy foil (21) was partially exposed to form an exposed portion (21A).
Then, the laminated sheet (20) was trimmed to 175 mmφ so that the exposed portions (21A) and (21B) on both surfaces of the aluminum alloy foil (21) were at the center (see FIG. 8 (g)).
Next, the trimmed laminated sheet (20) is placed between the male mold (61) and female mold (62) of the deep drawing mold (6) (see FIG. 8 (h)), and the laminated sheet (20) By pressing the male mold (61) into the female mold (62) while pressing the peripheral edge of the sheet with the wrinkle pressing mold (63), the laminated sheet (20) is formed (see FIG. 8 (h)), and the opening diameter A cup-shaped container body (2) having a diameter of 100 mm, an inner surface diameter of 80 mm, a depth of 40 mm, a flange width of 5 mm, and a capacity of 220 cc was produced (see FIG. 8 (i)).

Further, according to the processing procedure shown in FIG. 9, a cover material (3) for the container for electric heating according to the present invention was produced.
That is, first, an annealed aluminum alloy foil of A1N30 classified according to JIS H4160 with a thickness of 20 μm, on which a conductive coating (not shown) is formed on both sides by performing a non-chromium chemical conversion treatment containing a zirconium compound (31) Was cut into A4 size, and a polyester resin adhesive tape (7) cut to 40 mmφ with a thickness of 50 μm was attached to the central part of one side of the aluminum alloy foil (31) (see FIG. 9A).
Next, as shown in FIG. 9 (b), a two-component curable polyester polyurethane resin adhesive (not shown) is applied to the entire surface of the aluminum alloy foil (31) to which the polyester resin adhesive tape (7) is attached. Was applied at a coating amount of 3 g / m ² , and a polyester resin film (33) having a thickness of 12 μm was bonded thereto and allowed to stand in a constant temperature bath at 40 ° C. for 3 days to cure the adhesive.
Next, cut with a cutter knife into the polyester resin film (33) around the part where the polyester resin adhesive tape (7) is attached, and peel the polyester resin adhesive tape (7) together with the polyester resin film (33). One surface of the chemically treated aluminum alloy foil (31) was partially exposed to form an exposed portion (31B) (see FIG. 9C).
Next, as shown in FIG. 9 (d), a polyester resin adhesive tape (8) having a thickness of 50 μm and cut to 80 mmφ is attached to the center of the other surface of the aluminum alloy foil (31). A liquid-curing type polyester polyurethane resin adhesive (not shown) was applied at an application amount of 3 g / m ² , and a 30 μm-thick CPP (polypropylene resin) film (32) (Okamoto Co., Ltd., Aroma TP9) ), And left in a constant temperature bath at 40 ° C. for 3 days to cure the adhesive, thereby obtaining a laminated sheet (30) having a three-layer structure (see FIG. 9 (e)).
Next, as shown in FIG. 9 (f), the CPP film (32) around the portion where the polyester resin adhesive tape (8) is attached is cut with a cutter knife, and the polyester together with the CPP film (32). The resin adhesive tape (8) was peeled off, and the other surface of the chemically treated aluminum alloy foil (31) was partially exposed to form an exposed portion (31A).
Then, the laminated sheet (30) was trimmed to 150 mmφ so that the exposed portions (31A) and (31B) on both surfaces of the aluminum alloy foil (31) were in the center, and the lid material (3) was produced (FIG. 9). (See (g)).
Thus, the container of Example 1 comprising the container body (2) and the lid material (3) was obtained.

<Example 2>
As the material of the laminated sheet constituting the container body (2) and the lid material (3), an aluminum alloy foil that has not been subjected to chemical conversion treatment on both sides is used, and both the surfaces of the aluminum alloy foil formed by the same procedure as in Example 1 are used. A container body (2) and a lid material (3) were produced in the same manner as in Example 1 except that tin plating was applied only to the exposed portions to form a conductive film, and a container of Example 2 was obtained.

<Comparative Example 1>
As the material of the laminated sheet constituting the container main body and the lid material, an aluminum alloy foil whose both surfaces are not subjected to chemical conversion treatment is used, and the exposed portions on both surfaces of the aluminum alloy foil formed by the same procedure as in Example 1 are electrically conductive. A container body and a lid were prepared in the same manner as in Example 1 except that the coating treatment was not performed, and the container of Comparative Example 1 was obtained.

<Comparative example 2>
A container body and a lid were produced in the same manner as in Example 1 except that the exposed portions on both sides of the aluminum alloy foil were not formed, and a container of Comparative Example 2 was obtained.

<Electrical heating aptitude evaluation test>
About the container of Example 1, after filling the container main body (2) with tap water as a content, the cover material (3) is exposed to the inner surface of the aluminum alloy foil (31A) of the container main body (2). The aluminum alloy foil inner surface exposed portion (21A) is arranged so as to face the flange portion (2a) of the container body (2) and the peripheral portion of the lid member (3) superimposed on the lid member (3 ) Was heat-sealed at 0.2 MPa for 2 seconds with a hot plate heated to 200 ° C. from the upper part, and sealed.
Next, an alternating current of 100 W and 5 A was applied to the aluminum alloy foil outer surface exposed portions (21B) and (31B) of the container body (2) and the lid material (3) through a copper plate, and immediately after 1 minute the lid material ( 3) was opened, and the temperature of tap water at the center of the container body (2) was measured.
Moreover, the temperature of the tap water in the central part of the container body (2) was also measured in the same manner when the lid (3) was opened 3 minutes and 5 minutes after application of the alternating current.
And the test similar to the above was done also about the container of Example 2 and Comparative Examples 1 and 2. FIG.
The results are shown in Table 1 below.

Moreover, about the containers of Examples 1 and 2 and Comparative Examples 1 and 2, a commercially available retort curry was filled in the container body as the contents, and the same test as described above was performed.
The results are shown in Table 2 below.

As shown in Tables 1 and 2, in the case of the container of Example 1, it was possible to raise the temperature to near 100 ° C. in 5 minutes with tap water and 3 minutes with retort curry.
Further, after the test, when the container body (2) and the lid material (3) in a state where the tap water and the retort curry were taken out were observed, no change in the external appearance was observed compared to before the test.
Also in the container of Example 2, almost the same result as in Example 1, that is, the temperature of the contents was increased, and there was no change in appearance.
On the other hand, in the container of Comparative Example 1, the exposed portion of the inner surface of the aluminum alloy foil that had been in contact with tap water or the retort curry turned white after applying an alternating current. In the case of the container of Comparative Example 2, no heat generation was observed.

  The present invention can be used for packaging liquid foods such as soup and noodle soup, cooked foods such as curry, stew and gratin, and dessert foods such as pudding and water candy, etc. It can be suitably used as a storage container for heating.

(1A) (1B): Container for electric heating
(2): Container body
(2a): Flange
(2b): Bottom wall
(20): Laminated sheet (laminate)
(21): Metal foil
(21A): Metal foil inner surface exposed part
(21B): Exposed part of metal foil outer surface
(22): Heat-sealing resin layer
(23): Outer resin layer
(24): Conductive coating
(3): Cover material
(31): Metal foil
(31A): Metal foil inner surface exposed part
(31B): Metal foil outer surface exposed part
(32): Heat-sealing resin layer
(33): Heat-resistant resin layer
(C): Food

Claims (6)

  The container body consists of a laminate with resin layers laminated on both sides of the metal foil and contains food as contents, and the laminate consists of a resin layer laminated on both sides of the metal foil and is sealed to the flange of the container body A metal foil inner surface exposed portion and a metal foil outer surface exposed portion are formed on the container main body and the lid material by partially removing the inner resin layer and the outer resin layer, respectively. And the metal foil inner surface exposed part of a container main body and the metal foil inner surface exposed part of a cover material are the electric heating heating corresponding | compatible containers formed in the position which can be electrically connected through a foodstuff.   The metal foil inner surface exposed portion of the lid material is formed in a portion of the lid material covering the opening of the container main body, and the area of the metal foil inner surface exposed portion is 30 to 100% of the area of the container main body opening. The container for electric heating according to claim 1, wherein   The metal foil inner surface exposed portion of the container body is formed on the bottom wall portion of the container main body, and the area of the metal foil inner surface exposed portion is 30 to 100% of the area of the bottom wall portion. The container for electric heating as described.   The metal foil inner surface exposed portion and at least the metal foil inner surface exposed portion of the container main body and the cover material, respectively, of the metal foil inner surface exposed portion and the metal foil outer surface exposed portion are covered with a conductive film. Container for electric heating.   The container for electric heating according to claim 4, wherein the conductive coating is formed of a part of a conductive coating layer formed in advance on the inner surface or outer surface of the metal foil.   The electrically conductive heating-compatible container according to claim 4, wherein the conductive coating is formed by subjecting only the exposed inner surface of the metal foil or the exposed outer surface of the metal foil to the conductive coating.

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