JP2788974B2 - Food sealed packaging containers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

TECHNICAL FIELD The present invention relates to a container for hermetically sealed packaging used for storing and selling retort foods such as pudding and jelly, and frozen frozen foods such as gratin and hamburger. The present invention relates to a container for hermetically closed packaging of food that can be cooked in an electric oven or the like while containing frozen frozen food and the like.

[Prior art]

The following two functions are required for a food sealed packaging container for storing and selling retort foods, cooked frozen foods, and the like. The first is a function called easy peeling, which allows a container lid made of a laminate of an aluminum foil and a non-oriented polypropylene film to be easily peeled off from the container body. The second is the function of heat sterilization with the container lid sealed. The third function is that the food can be cooked in an electric oven or the like while the food is stored in the container body. In order to impart the function of easy peeling to the container body, an acid-modified polypropylene resin may be provided as a heat sealing material on the inner side of the aluminum foil which is a material constituting the container body, that is, on the side in contact with the stored food. . However, the acid-modified polypropylene resin is inferior in heat resistance, and sometimes cannot be cooked in an electric oven or the like while storing food. That is, the acid-modified polypropylene resin is softened or melted and leached into the stored food. In order to overcome this drawback, it has been proposed to use a mixed material of an acid-modified polypropylene resin and a thermosetting resin as a heat sealing material (Japanese Utility Model Laid-Open No. 63-94173). This is to improve the heat resistance of the entire heat sealing material by mixing a thermosetting resin having excellent heat resistance. However, as is well known, a thermosetting resin is formed by binding polymer chains like a network, and therefore has poor fluidity, in other words, poor moldability. Therefore, a laminated material in which a heat sealing material using a thermosetting resin is provided inside an aluminum foil is formed into a certain container shape by cold press molding.
In other words, when molded into a shape consisting of a storage section for storing food and a flange for heat sealing the container lid, the thermosetting resin does not flow sufficiently, and cracks and pinholes occur in the heat sealing material. I had to do it. When cracks or pinholes occur in the heat sealing material, components in the stored food, for example, organic acids such as acetic acid, rice vinegar, and citric acid, come into contact with the aluminum foil through the cracks and corrode the aluminum foil. Finally, there is a fear that holes may be formed in the aluminum foil.

[Problems to be solved by the invention]

In order to avoid this fear, it is considered that an anticorrosion layer made of a zirconium compound may be provided between the aluminum foil and the heat sealing material. However, as described above, since a thermosetting resin having poor moldability is compounded in the heat sealing material, cracks and pinholes may occur when cold press molding is performed. Further, since the corrosion-resistant layer is also made of an inorganic substance, the moldability is poor, and cracks and pinholes may be generated when cold press molding is performed. Therefore, when cracks or the like are generated in both the heat sealing material and the corrosion-resistant layer, there arises a drawback that holes may be formed in the aluminum foil as a constituent material of the container as described above. Therefore, the present invention aims to eliminate all of the above-mentioned disadvantages by providing a material having good adhesion and good moldability between the heat sealing material and the anticorrosion layer. .

[Means for Solving the Problems]

That is, the present invention is a food sealed packaging container in which a storage portion for storing food and a flange portion for thermally sealing the container lid are formed by cold press molding. From the outside, formed of a laminate in which an aluminum foil, an anticorrosion layer, an adhesive layer, and a heat sealing layer are laminated in this order. The anticorrosion layer is made of an anticorrosion material containing at least a zirconium compound, and the adhesive layer is made of an acid. The present invention relates to a food sealed packaging container comprising a modified polypropylene resin, wherein the heat sealing layer is composed of a mixed material of a thermosetting resin and an acid-modified polypropylene resin. The food packaging container according to the present invention can be obtained by using a laminate as shown in the drawings and cold-pressing the laminate. (1) is an aluminum foil, which is conventionally known. The aluminum foil (1) having a length of about 100 to 200 μm is used. (2) is a corrosion-resistant layer. The anticorrosion layer (2) is composed of an anticorrosion material containing at least a zirconium compound. As the zirconium compound, zirconium oxide is generally used. Other examples include zirconium halide, zirconium nitrate, zirconium sulfate, zirconium silicate, and zirconium organic acid. The anticorrosion layer (2) can be formed of a zirconium compound alone. However, in order to improve the film forming property of the anticorrosion layer (2), a thermoplastic resin such as polyethylene, polypropylene or polyvinyl chloride is mixed in addition to the zirconium compound. Or a water-soluble resin such as polypinyl alcohol, polyacrylic acid, or hydroxyethyl cellulose. Further, a thermoplastic resin and a water-soluble resin may be used in combination. When using a thermoplastic resin,
Heat is applied to the resin to melt or soften it, uniformly mixed with the zirconium compound, and applied to an aluminum foil to obtain the corrosion-resistant layer (2). When a water-soluble resin is used, the corrosion-resistant layer (2) can be obtained by dissolving the resin in water, mixing a zirconium compound, and applying the mixture to an aluminum foil. When a thermoplastic resin and a water-soluble resin are used in combination, a suspension in which the water-soluble resin and the zirconium compound are dissolved in water and thermoplastic resin particles are dispersed therein is obtained, and this suspension is applied to an aluminum foil. For example, a corrosion-resistant layer (2) can be obtained. When the zirconium compound is mixed with a thermoplastic resin or a water-soluble resin, the amount of the latter is preferably about 0.5 to 10 parts by weight based on 1 part by weight of the former. When the amount of the thermoplastic resin or the like is less than 0.5 part by weight, the amount of the zirconium compound relatively increases, and the film-forming property tends to decrease. On the other hand, when the amount of the thermoplastic resin or the like exceeds 10 parts by weight, the amount of the zirconium compound becomes relatively small, and the anticorrosion effect tends to decrease. Corrosion layer applied to an aluminum foil (1) (2) is in, it is preferable that the zirconium compound is contained in an amount of 10 to 25 mg / m ^2. The amount of zirconium compound is 10
If it is less than mg / m ² , the anticorrosive effect tends to decrease.
Also, the amount of zirconium compound exceeds the 25 mg / m ^2,
There is a tendency that no further improvement in the anticorrosion effect is observed. A heat sealing layer (4) is adhered to the corrosion-resistant layer (2) via an adhesive layer (3). The adhesive layer (3) is made of an acid-modified polypropylene resin. Here, the acid-modified polypropylene resin is
It is obtained by adding dicarboxylic acid to the side chain of polypropylene, and generally, maleic acid or maleic anhydride is added to the side chain. Specifically, Unistor R100, R120, manufactured by Mitsui Petrochemical Industries, Ltd.
R200, Riofrex 4000 manufactured by Toyo Ink Mfg. Co., Ltd. or Mol Prime manufactured by Toyo Morton Co., Ltd. is used. The acid-modified polypropylene resin used as the adhesive layer (3) may be in the form of a film or a solution such as an organosol. In the case of a film form, heat is applied to soften or melt to bond the anticorrosion layer (2) and the heat sealing layer (4). In the case of a solution,
After applying to the anticorrosion layer (2) or the heat-sealing layer (4), the heat-sealing layer (4) or the anticorrosion layer (2) is bonded and dried to bond both layers (2) and (4). be able to. Acid-modified polypropylene resin constituting the adhesive layer (3) is preferably used in a proportion of about 0.1~1000mg per 1 m ^2. When the amount of the acid-modified polypropylene resin is less than 0.1 mg / m ² , the adhesive strength between the anticorrosion layer (2) and the heat sealing layer (4) tends to be insufficient, and after cold press molding,
Cracks and pinholes also tend to occur in the adhesive layer (3). In addition, the amount of the acid-modified polypropylene resin is 1000 mg / m
If it exceeds ² , the acid-modified polypropylene resin melted during cooking in an electric oven or the like tends to leach into food through cracks and pinholes in the heat sealing material. The heat sealing layer (4) is composed of a mixed material of a thermosetting resin and an acid-modified polypropylene resin. As the thermosetting resin, epoxy resin, urea resin, melamine resin, phenol resin, unsaturated polyester resin and the like can be used. Generally, an epoxy resin is used. The same acid-modified polypropylene resin as that used for the adhesive layer (3) is used. Since the acid-modified polypropylene resin needs to be uniformly mixed with the thermosetting resin, a solution such as an organosol is used. The mixing ratio of the thermosetting resin to the acid-modified polypropylene resin is preferably about 0.05 to 1 part by weight of the acid-modified polypropylene resin per 1 part by weight of the thermosetting resin. When the amount of the acid-modified polypropylene resin is less than 0.05 part by weight, the heat sealing property with the container lid, that is, the sealing property with the container lid tends to be insufficient. On the other hand, when the amount of the acid-modified polypropylene resin exceeds 1 part by weight, the amount of the thermosetting resin becomes relatively small, and the heat resistance tends to be poor. As described above, a laminate in which the aluminum foil (1), the anticorrosion layer (2), the adhesive layer (3), and the heat sealing layer (4) are laminated in this order from the outside is obtained. On the other surface of the aluminum foil (1) of this laminate (the surface opposite to the surface on which the anticorrosion layer (2) is laminated), a heat-resistant resin is laminated for printability and for preventing corrosion of the aluminum foil (1). (Not shown). As the heat-resistant resin, the above-described thermosetting resin or the like can be used. Such a laminate is cold-pressed to form a storage portion for storing food and a flange portion for thermally sealing the container lid, and form a book-shaped, bowl-shaped or pot-shaped book. The food sealed packaging container according to the invention can be obtained.

【Example】

Example 1 The following anticorrosive material was made into an aqueous solution (concentration: 1% by weight) and applied to one surface of an aluminum foil having a thickness of 130 μm using a gravure coater. Zirconium oxide 1 part by weight Polyvinyl alcohol 5 parts by weight After coating, the coating was dried to form an anticorrosion layer. This anticorrosion layer contained zirconium (in terms of zirconium) at a rate of 18 mg / m ² . An organosol of acid-modified polypropylene (Unistol, manufactured by Mitsui Petrochemical Industry Co., Ltd.) was applied on the anticorrosion layer with a gravure coater and dried to form an adhesive layer made of 200 mg / m ² of acid-modified polypropylene. Then, a mixed material having the following composition was coated with toluene (concentration: 20% by weight), applied on the adhesive layer with a roll coater, and dried to provide a heat sealing layer composed of a dry film of 10 g / m ² . . Epoxy resin 90 parts by weight Acid-modified polypropylene resin 10 parts by weight The same acid-modified polypropylene resin as that used in forming the above-mentioned anticorrosion layer was used. The laminate thus obtained was cold-pressed into a container having a food storage section and a flange. In this container, the height from the bottom of the storage section to the flange was 3 cm. The container was heat-sterilized at 120 ° C. for 30 minutes, but no decrease in the adhesion between the layers was observed. In addition, an immersion test of a copper sulfate solution (a mixed solution of 10% HCl and 20% CuSO ₄ ) was performed, and almost no copper precipitation due to cracks or pinholes in each layer was observed. Further, 100 ml of salad oil was put in this container, and heated with an electric oven toaster for 20 minutes to raise the temperature of the salad oil to about 250 ° C., but no turbidity due to elution of each layer was observed. Comparative Example 1 A mixed material having the following composition was formed on one side of a 130 μm-thick aluminum foil with toluene (concentration: 20% by weight).
It was applied with a roll coater and dried to provide a heat sealing layer consisting of a dried film of 10 g / m ² . Epoxy resin 90 parts by weight Acid-modified polypropylene resin 10 parts by weight The same acid-modified polypropylene resin as that used in Example 1 was used. The laminate thus obtained was cold-pressed into a container having a food storage section and a flange. In this container, the height from the bottom of the storage section to the flange was 3 cm. As a result of heat-sterilizing the container at 120 ° C. for 30 minutes, a decrease was observed in the adhesion between the aluminum foil and the heat sealing layer. In addition, as a result of immersion test of a copper sulfate solution (a mixed solution of Hcl 10% and CuSO ₄ 20%), copper deposition due to cracks and pinholes in the heat sealing layer was observed. Example 2 On the other side of a two-layer laminated aluminum foil in which a heat-resistant resin layer made of epoxy resin is provided on one side of an aluminum foil having a thickness of 130 μm, the following anticorrosive material was applied in the form of an aqueous solution (concentration: 0.5% by weight) ) And coated with a gravure coater. Zirconium nitrate 5 parts by weight Ethylene-acrylic acid copolymer resin 5 parts by weight After coating, it was dried to form an anticorrosion layer. This anticorrosion layer contained zirconium (in terms of zirconium) at a rate of 12 mg / m ² . An organosol of acid-modified polypropylene (Rioflex, manufactured by Toyo Ink Mfg. Co., Ltd.) was applied on the anticorrosion layer using a roll coater, dried, and an adhesive layer made of 500 mg / m ² of acid-modified polypropylene was provided. After that, a mixed material having the following composition was made into a paint with a mixed solvent of toluene and ethylene cellosolve (concentration 25% by weight).
Then, the resultant was coated on the adhesive layer and dried to form a heat sealing layer composed of a dried film of 10 g / m ² . 70 parts by weight of epoxy resin 30 parts by weight of acid-modified polypropylene resin The same acid-modified polypropylene resin as that used in Example 1 was used. The laminate thus obtained was cold-pressed into a container having a food storage section and a flange. In this container, the height from the bottom of the storage section to the flange was 3 cm. The container was heat-sterilized at 120 ° C. for 30 minutes, but no decrease in the adhesion between the layers was observed. An immersion test of a copper sulfate solution (a mixed solution of 10% of Hcl and 20% of CuSO ₄ ) was carried out, but almost no copper deposition due to cracks or pinholes in each layer was observed. Further, 100 ml of salad oil was put in this container, and heated with an electric oven toaster for 20 minutes to raise the temperature of the salad oil to about 250 ° C., but no turbidity due to elution of each layer was observed. Comparative Example 2 On the other side of a two-layer laminated aluminum foil in which a heat-resistant resin layer made of epoxy resin is provided on one side of a 130-μm-thick aluminum foil, the following anticorrosive material is in an aqueous solution state (concentration: 0.5% by weight). ) And coated with a gravure coater. Zirconium nitrate 5 parts by weight Ethylene-acrylic acid copolymer resin 5 parts by weight After coating, it was dried to form an anticorrosion layer. This anticorrosion layer contained zirconium (in terms of zirconium) at a rate of 12 mg / m ² . Next, a mixed material having the following composition was made into a paint with a mixed solvent of toluene-ethyl cellosolve (concentration: 25% by weight).
Then, the resultant was coated on the corrosion-resistant layer and dried to provide a heat sealing layer composed of a dried film of 10 g / m ² . 70 parts by weight of epoxy resin 30 parts by weight of acid-modified polypropylene resin The same acid-modified polypropylene resin as that used in Example 1 was used. The laminate thus obtained was cold-pressed into a container having a food storage section and a flange. In this container, the height from the bottom of the storage section to the flange was 3 cm. The container was heat-sterilized at 120 ° C. for 30 minutes, but no decrease in the adhesion between the layers was observed. However, as a result of a copper sulfate solution (mixed solution of Hcl 10% and CuSO ₄ 20%) immersion test, copper deposition due to cracks and pinholes in each layer was observed. Furthermore, put 100 ml of salad oil in this container,
The mixture was heated in an electric oven toaster for 20 minutes, and the temperature of the salad oil was set to about 250 ° C. As a result, some turbidity due to elution of each layer was observed.

[Action and effect of the invention]

As described above, the food-sealing packaging container according to the present invention contains an acid-modified polypropylene resin in the heat-sealing layer, and the container lid is adhered to the container using this. Can be easily peeled off, that is, it has an effect of being excellent in easy peelability. Further, since the food sealed packaging container according to the present invention has an adhesive layer made of an acid-modified polypropylene resin having excellent moldability between the heat sealing layer and the anticorrosion layer, when cold-pressed, Even if cracks or pinholes occur in the heat sealing layer or the anticorrosion layer, no cracks or the like occur in the adhesive layer, so that the aluminum foil is not exposed inside the container.
Therefore, even if food is stored in this container, it is possible to prevent the aluminum foil from being corroded by acid components in the food. Furthermore, since the food-sealed packaging container according to the present invention uses an acid-modified polypropylene resin as the adhesive layer, the adhesion between the heat-sealing layer and the anticorrosion layer is improved, and even if cold press molding is performed, It is possible to prevent the sealing layer and the corrosion-resistant layer from peeling off and the heat sealing layer from floating. Therefore, the adhesion of the container lid by the heat sealing layer can be made tight, and an effect that an excellent sealing property between the container and the container lid can be obtained is obtained.

[Brief description of the drawings]

The drawing shows, by a schematic cross-sectional view, an example of a laminate used for obtaining the food-sealed packaging container according to the present invention. (1) ... aluminum foil, (2) ... corrosion-resistant layer, (3) ... adhesive layer, (4) ... heat sealing layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuhiko Fujita 61-8 Sasaya, Yamadera-cho, Kusatsu-shi, Shiga Japan-made Foil Co., Ltd. Shiga Factory (56) References Japanese Utility Model 2-40018 (JP, U) (58 ) Surveyed field (Int.Cl. ⁶ , DB name) B65D 81/34 B65D 77/20

Claims (1)

(57) [Claims] 1. A food sealed packaging container in which a storage portion for storing food and a flange portion for thermally sealing a container lid are formed by cold press molding, wherein the food sealed packaging container comprises: From the outside, it is formed of a laminate in which an aluminum foil, an anticorrosion layer, an adhesive layer, and a heat sealing layer are laminated in this order. The anticorrosion layer is composed of an anticorrosion material containing at least a zirconium compound, and the adhesive layer is acid-modified. A container for hermetically sealed packaging of food, wherein the container is made of a polypropylene resin, and the heat sealing layer is made of a mixed material of a thermosetting resin and an acid-modified polypropylene resin.