JP7493075B2 - Molded containers and packaging - Google Patents

Description

The present invention relates to a molded container for hermetically packaging food and the like, and a package formed by applying a lid to the molded container filled with contents, and more specifically, to a molded container and package having a matte outer surface .

For example, as a container for packaging mizu-yokan (azuki bean jelly), jelly, baby food, nursing care food, etc. for long-term storage, a molded container is known that is made by molding a laminate having a metal foil layer made of aluminum foil or the like and a single or multiple outer resin film layers laminated on both sides of the metal foil layer that will become the outside of the container into a cup shape (see Patent Document 1 below, etc.).

In the field of packaging, containers having a matte (frosted) outer surface are sometimes used to give a luxurious appearance.
For example, the following Patent Document 2 discloses the use of an embossed polypropylene resin film to produce a stationery file or the like having a matte outer surface.
Furthermore, the following Patent Document 3 discloses a hard coat film for molding in which a hard coat layer having a matte outer surface is formed as the outermost layer.

Japanese Patent Application Laid-Open No. 6-345123 Japanese Patent Application Laid-Open No. 5-320376 JP 2011-148301 A

However, when a laminate having an outer resin film layer constituted by an embossed film as in Patent Document 2 is molded into a cup shape, the embossed film may be stretched during molding, causing spots on the matte outer surface, which may impair the appearance. In addition, the use of an embossed film has the problem of increased costs.
Furthermore, when a laminate in which an outer resin film layer is constituted by a film having a matte coating layer as in the above-mentioned Patent Document 3 is molded into a cup shape, there is a problem that the coating layer cracks or peels off. In addition, when a matte coating layer is formed, there is also a problem that the cost increases.

This invention was made in consideration of the above problems, and aims to provide a container made by molding a laminate having a metal foil layer and an outer resin film layer, which has a matte outer surface with a good appearance, at a low cost.

To achieve the above objective, this invention comprises the following aspects:

1) A molded container for filling and packaging food , which is formed into a cup shape by molding a laminate for a molded container, the laminate comprising a metal foil layer and a single or multiple outer resin film layers laminated on the surfaces of the metal foil layer that will become the outer surfaces of the container ,
the forming container has a bottom wall, a peripheral wall rising from the peripheral edge of the bottom wall, and a flange formed on the peripheral edge of the opening, and has a corner portion at the boundary between the bottom wall and the peripheral wall;
The laminate for a molding container has a single outer resin film layer or an outermost layer among a plurality of outer resin film layers, the outermost layer being made of a resin composition containing a polyolefin resin and an olefin-based elastomer as main components,
The molded container has an outer surface of the outer resin film layer that has a matte finish and a glossiness of 0.5 to 30%.

2) The laminate for a molded container according to 1) above , in which a layer containing a coloring component is formed between the metal foil layer and the single outer resin film layer or the outermost layer among the multiple outer resin film layers .

3 ) A package comprising the above-mentioned molded container 1) or 2) filled with food as the content, and a lid joined to the flange of the molded container so as to cover the opening of the molded container.

In the molded container of 1) or 2) , the single-layer outer resin film layer of the laminate for molded containers , or the outermost layer of the multiple outer resin film layers, is made of a resin composition mainly composed of a polyolefin resin and an olefin-based elastomer, and the gloss of the outer surface of the outer resin film layer is set to 0.5 to 30%, so that the outer surface is matte. In the case of the molded container of 1) or 2) , the laminate for molded containers does not have spots on the outer surface caused by stretching during molding, as in a laminate in which the outer surface of the outer resin film layer is constituted by an embossed film, and does not have cracks in the coating layer or peeling off, as in a laminate in which the outer surface of the outer resin film layer is constituted by a film having a matte coating layer, and is also inexpensive.
Therefore, according to the above-mentioned molded container 1) or 2) , a molded container having a matte outer surface with a good appearance can be obtained at low cost.
Here, the "glossiness" is measured in accordance with JIS Z8741-1997 (Specular glossiness--measuring method, Method 3 (incident angle 60 degrees)).

According to the above package 3 ), the container has a matte outer surface with a good appearance, which gives it a luxurious feel.

FIG. 2 is a partially enlarged cross-sectional view showing the layer structure of a laminate for a forming container according to an embodiment of the present invention. 1A to 1C are vertical cross-sectional views showing a method for manufacturing a package according to an embodiment of the present invention in the order of steps. FIG. 2 is a perspective view of a package manufactured by the method.

An embodiment of the present invention will be described below with reference to Figures 1 to 3.

Figure 1 shows the layer structure of a laminate for a molded container according to an embodiment of the present invention. The laminate (10) shown in the figure comprises a metal foil layer (11) and an outer resin film layer (12) laminated on one of both sides of the metal foil layer (11) that will become the outer side of the container (2). The laminate (10) of this embodiment also comprises an inner resin layer (13) laminated on one of both sides of the metal foil layer (11) that will become the inner side of the container (2).

The metal foil constituting the metal foil layer (11) may be aluminum foil, iron foil, stainless steel foil, copper foil, etc., but aluminum foil is preferably used. In the case of aluminum foil, either pure aluminum foil or aluminum alloy foil may be used, and either soft or hard, but for example, annealed soft material (O material) of A8000 series (especially A8079H or A8021H) classified by JIS H4160 with an iron content of 0.3 to 1.5 mass% is preferably used because it has excellent formability.
One or both sides of the metal foil layer (11) may be subjected to a surface treatment such as a chemical conversion treatment, if necessary. Specifically, for example, the surface of the metal foil that has been degreased may be subjected to the following treatment:
1) phosphoric acid;
Chromic acid,
at least one compound selected from the group consisting of metal salts of fluorides and non-metal salts of fluorides; 2) an aqueous solution of a mixture containing phosphoric acid;
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins;
3) an aqueous solution of a mixture containing phosphoric acid and at least one compound selected from the group consisting of chromic acid and chromium (III) salts;
At least one resin selected from the group consisting of acrylic resins, chitosan derivative resins, and phenolic resins;
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 non-metal salt of fluoride. A coating is formed by applying a chemical conversion treatment to the surface of the substrate using an aqueous solution of any one of 1) to 3) above and then drying the applied solution.
The coating formed on the surface of the metal foil layer (11) by the above chemical conversion treatment has a chromium deposition amount (per side) of preferably 0.1 mg/m ² to 50 mg/m ² , and more preferably 2 mg/m ² to 20 mg/m ² .
The thickness of the metal foil layer (11) is preferably 30 to 200 μm, more preferably 50 to 150 μm, in order to obtain sufficient barrier properties and moldability.

The outer resin film layer (12) may be a single layer or multiple layers (shown as a single layer in FIG. 1).
The layers constituting the outer surface of the molded container (2), i.e., the single-layer outer resin film layer (12) or the outermost layer of the multiple outer resin film layers (12), are made of a resin composition mainly composed of polyolefin resin and olefin-based elastomer. The outer surface (12a) of the outer resin film layer (12) constituted by the above layers has a gloss value (gloss value) of 0.5 to 30%. In the above resin composition, examples of the polyolefin resin include block polypropylene resin (PP-B), homopolypropylene resin (PP-H), random polypropylene resin (PP-R), high density polyethylene resin (HDPE), linear low density polyethylene resin (LLDPE), low density polyethylene resin (LDPE), etc. Examples of the olefin-based elastomer include ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-propylene-1-butene copolymer, etc. The content of monomers other than ethylene is 5 to 40 mass %, and the melting point is less than 90°C. The above layer may also contain a polyolefin component having a melting point of not less than 135° C. Furthermore, in order to adjust the gloss of the outer surface of the molded container (2), an organic or inorganic particulate filler may be added to the above layer, if necessary.
When the outer resin film layer (12) is a multi-layer structure, the layers other than the outermost layer are made of polyolefin resins such as polypropylene resin (PP) and polyethylene resin (PE), polyamide resins (PA) such as nylon 6 (PA6), nylon 66 (PA66), and MXD nylon, and polyester resins (PEs) such as polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), and polyethylene naphthalate resin (PEN), etc.
The thickness of the outer resin film layer (12) is preferably 5 to 100 μm, and more preferably 15 to 80 μm.
A lubricant may be added to the outer resin film layer 12 in order to obtain a molded container 2 with an appropriate depth. Instead of or in addition to the addition of a lubricant, a lubricating oil such as silicone oil or rapeseed oil may be applied to the surface of the laminate 10 during molding.
The metal foil layer (11) and the outer resin film layer (12) are laminated by a dry lamination method via an adhesive layer (14). For example, a two-component curing type polyester-polyurethane resin adhesive or a polyether-polyurethane resin adhesive is used for the adhesive layer (14).

A printed layer (15) is formed entirely or partially on the inner surface of the outer resin film layer (12) by gravure printing or the like. This printed layer (15) provides a predetermined display or decoration on the outer surface of the molded container (2). The printed layer (15) is not particularly limited, but it is preferable that the background color be a dark color such as black in order to emphasize the matte outer surface (12a) and give a sense of luxury.
Instead of the printed layer (15), a coloring component such as a pigment may be added to the outer resin film layer (12).

The inner resin layer (13) constitutes the inner surface of the container (2) (including the upper surface of the flange portion (23)) and is composed of, for example, a general-purpose film such as a polypropylene resin (PP) film or a polyethylene resin (PE) film having heat-sealing properties, or a composite sheet made by bonding these together.
The thickness of the film or composite sheet constituting the inner resin layer (13) is preferably 100 to 500 μm, and more preferably 200 to 400 μm.
The metal foil layer (11) and the film or composite sheet constituting the inner resin layer (13) are laminated by a dry lamination method via an adhesive layer (16). For example, a two-component curing type polyester-polyurethane resin adhesive or a polyether-polyurethane resin adhesive is used for the adhesive layer (16).
The inner resin layer (13) may be formed of a coating layer of epoxy resin, shellac resin, or the like, instead of the above-mentioned film or composite sheet.

Figure 2 shows the steps of a method for producing a package in which the contents, such as food, are sealed and packaged using a molded container and a lid formed from the laminate.

First, the laminate (10) is cut to a predetermined shape and size, and then molded into a cup shape. The laminate (10) is molded by cold forming such as deep drawing or stretch forming. In this way, a molded container (2) as shown in Figure 2(a) is obtained.
The forming container (2) has a bottom wall (21), a peripheral wall (22) rising from the peripheral edge of the bottom wall (21), and a horizontal annular flange (23) extending radially outward from the upper edge of the peripheral wall (22).
Here, a part of the outer surface of the molded container (2) after molding, particularly the corner part at the boundary between the bottom wall (21) and the peripheral wall (22), may become cloudy, and the surface color of the metal foil layer (11) or the marking of the printed layer (15) may be hidden and not visible. This is thought to be because, by molding the laminate (10), voids (air gaps) are generated at the interface between the polyolefin resin matrix and the olefin-based elastomer in the single-layer outer resin film layer (12) or in the outermost layer of the multiple outer resin film layers (12), and therefore, due to the difference in refractive index between the resin part and the void, the corner part of the outer surface of the molded container (2) that is greatly deformed by molding appears cloudy.

Next, as shown in FIG. 2(b), the formed container (2) is filled with the contents (C) such as food, and then the peripheral portion of the lower surface of the lid (3) is heat-sealed to the upper surface of the flange (23) of the formed container (2).
Here, the lid (3) may comprise, for example, a metal foil layer made of aluminum foil or the like, a heat-sealable resin film layer made of polypropylene resin (PP) film, polyethylene resin (PE) film or the like and laminated on the lower surface of the metal foil layer, and an outer resin film layer made of polyester resin (PS) film, polyamide resin (PA) film or the like and laminated on the upper surface of the metal foil layer. Also, an opening tab (31) is integrally formed on a part of the outer periphery of the lid (3) so as to protrude outward beyond the flange (23) of the molded container (2) (see FIG. 3).
The means for heat-sealing the lid (3) to the flange (23) of the molded container (2) is not particularly limited, but for example, the lid (3) can be placed on the upper surface of the flange (23) by overlapping the lower peripheral portion of the lid (3) and heating the overlapped portions for a predetermined time while applying a predetermined pressure using a hot plate heated to a predetermined temperature (e.g., about 180°C).

Next, the package (4) obtained in the above step is introduced into a retort sterilization device (5) and subjected to a retort sterilization treatment. This retort sterilization treatment step also serves as a heat treatment step for removing the cloudiness that has occurred in part of the outer surface of the formed container (2).
The heating temperature of the package (4) in this step is set to a temperature equal to or higher than the softening point of the single-layer outer resin film layer (12) of the laminate (10) or the resin of the outermost layer of the multiple-layer outer resin film layers (12). More preferably, the heating temperature is set to a temperature equal to or higher than the softening point and lower than the melting point of the resin. By setting the heating temperature to a temperature equal to or higher than the softening point of the resin, the distortion of the laminate (10) caused by molding is alleviated, and voids are easily filled. In addition, by setting the heating temperature to a temperature lower than the melting point of the resin, the shape of the molded container (2) can be maintained even after heating. Specifically, the heating temperature is set to about 80°C or higher, preferably about 100 to 180°C. The heating time is set to about 5 minutes to 3 hours.
The heat treatment step may of course be other than the retort sterilization step, and may be, for example, a heat treatment in an oven, a immersion treatment in hot water, etc. In the case of a heat treatment other than the retort sterilization step, only the formed container (2) may be heat treated in a step before it is made into the package (4).

Fig. 3 shows the package (4) after retort sterilization. The opacity that had appeared in the corners of the outer surface of the formed container (4) has disappeared. This is thought to be because the formed container (2) is sufficiently heated by the retort sterilization, which relieves the distortion of the laminate (10) caused by molding and fills the voids.
Thus, the package (4) is provided with a molded container (2) having a matte outer surface with a good overall appearance, which gives consumers a sense of luxury.

Next, an embodiment of the present invention will be described. However, the present invention is not limited to the following embodiment.

Example 1
As the metal foil layer, a 120 μm thick aluminum foil was prepared, which was made of A8021H-O classified by JIS H4160, and was coated on both sides with a chemical conversion treatment solution consisting of polyacrylic acid, a trivalent chromium compound, water and alcohol, and dried at 180 ° C. to give a chromium deposition amount of 10 mg / m ^2. As the outer resin film layer, a single layer of non-stretched polypropylene resin film (CPP) with a thickness of 50 μm was prepared, and a plain printing layer was formed on the entire surface of one side using a gravure printing machine with black ink (manufactured by DIC Graphics, product name: Panasia CVL-SP Tokuboku 805). In addition, as the inner resin layer, a composite sheet (layer ratio: 50 μm / 250 μm) of a high density polyethylene resin film (HDPE) and a polypropylene resin film (PP) with a thickness of 300 μm was prepared.
For the non-oriented polypropylene resin film (CPP), a resin composition was used in which 10% by mass of ethylene-butene-1 copolymer rubber was added to block polypropylene resin (PP-B) (softening point: 97° C.).
Then, a non-oriented polypropylene resin film (CPP) was dry laminated to one side of the aluminum foil using a two-component curing polyester-polyurethane resin adhesive with the printed layer facing inward, and the composite sheet was dry laminated to the other side of the aluminum foil using a two-component curing polyester-polyurethane resin adhesive with the polypropylene resin film side facing inward, and the resulting laminate was cured in an environment of 40°C for 5 days to produce a laminate for a molded container.

Next, a small amount of siloxane was applied to both sides of a blank obtained by cutting the laminate for molded containers into a specified shape, and then the blank was deep-drawn using a mold consisting of a male and female mold to produce a round cup-shaped container with a flange (bottom diameter 52 mmφ, opening diameter 65 mmφ, height 30 mm, flange width 8 mm).

On the other hand, a 12 μm thick polyethylene terephthalate resin (PET) film was dry laminated as an outer resin layer to one side of a 20 μm thick aluminum foil made of A1N30H-O classified under JIS H4160 using a two-component curing polyester-polyurethane resin adhesive, and a 30 μm thick linear low density polyethylene resin (LLDPE) film was dry laminated as a heat-sealable resin layer to the other side of the aluminum foil using a two-component curing polyester-polyurethane resin adhesive, and the resulting product was cured in an environment of 40° C. for 5 days to produce a lid laminate.
The resulting laminate was cut to the required shape and size to fit the flange, creating a lid with a tear tab.

After pouring 70 ml of water into the container, the lid was placed on the upper surface of the flange of the container so that the linear low-density polyethylene resin (LLDPE) film surface was in contact with the lid, and a donut-shaped hot plate (outer diameter 90 mmφ, inner diameter 74 mmφ) heated to 200°C was pressed against the polymerized surfaces with a pressure of 150 kgf for 3 seconds to perform heat sealing (thermal fusion).
In this way, the package of Example 1 was obtained.

<Comparative Example 1>
As the outer resin film layer of the laminate for molded containers, a 30 μm-thick three-layered non-oriented polypropylene resin film (CPP) formed by laminating a random polypropylene resin (PP-R) film, a block polypropylene resin (PP-B) film, and a random polypropylene resin (PP-R) film in that order was used. A package was otherwise prepared in the same manner as in Example 1, and this was designated Comparative Example 1.

The gloss of the outer surface of the container for the packages of Example 1 and Comparative Example 1 was measured using a gloss meter (BYK Gardner Micro Trigloss S), and was 6% for Example 1 and 100% for Comparative Example 1.

The appearance of the molded containers of the packages of Example 1 and Comparative Example 1 was visually observed. In Example 1, severe whitening was observed on the outer surface of the molded container at the corners of the boundary between the bottom wall and the peripheral wall. On the other hand, in Comparative Example 1, no whitening was observed on the outer surface of the molded container.

Next, the package of Example 1 was heat-treated at a heating temperature of 100°C for 60 minutes in a constant temperature and humidity oven (PL-1J type manufactured by Espec Corporation). After that, it was removed from the oven and the outer surface of the molded container was visually observed. Although some whitening remained in the corners, most of the whitening had disappeared.
In addition, the package of Example 1 was heat-treated at a heating temperature of 120° C. for 30 minutes using a retort sterilization treatment device (RCS-40RTGN, manufactured by Hisaka Works, Ltd.). After that, it was removed from the device and the outer surface of the molded container was visually observed. As a result, the whitening of the corners had completely disappeared.

This invention can be used effectively for molded containers that are intended for hermetically packaging food and the like and have a matte outer surface with a good appearance.

(2): Molded container
(23): Flange
(3): Lid
(4) Package
(5): Retort sterilization equipment
(10): Laminate for molding containers
(11): Metal foil layer
(12): Outer resin film layer
(12a): Outer surface of the outer resin film layer
(15): Printing layer
(C): Contents

Claims (2)

A molded container for filling and packaging food, which is formed into a cup shape by molding a laminate for a molded container, the laminate comprising a metal foil layer and a single or multiple outer resin film layers laminated on the surfaces of the metal foil layer that will be the outer surfaces of the container,
the forming container has a bottom wall, a peripheral wall rising from the peripheral edge of the bottom wall, and a flange formed on the peripheral edge of the opening, and has a corner portion at the boundary between the bottom wall and the peripheral wall;
The laminate for a molding container has a single outer resin film layer or an outermost layer among a plurality of outer resin film layers, the outermost layer being made of a resin composition containing a polyolefin resin and an olefin-based elastomer as main components,
The molded container has an outer surface of the outer resin film layer that has a matte finish and a glossiness of 0.5 to 30%. 2. A package comprising the formed container according to claim 1 , filled with food as the content, and a lid joined to the flange of the formed container so as to cover the opening of the formed container.

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