JPS6246412B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to food containers. Specifically, the present invention relates to a food container that enables retort sterilization and allows for a significantly wider variety of filling materials.

In recent years, containers for foods such as liquid beverages, which are mainly made of cylinders made by laminating and bonding synthetic resin, paper, and aluminum foil as appropriate, are rolled up and stacked, and welded together at both ends. It is being used in large numbers because it is lightweight, has excellent display properties as a container, is printable, and is easily incinerated.

However, most of these food containers use low-density polyethylene resin, which has good sealing properties, for both outer layers of the cylindrical body, which is the main part of the container, and no special measures are taken at the joints of the cylindrical bodies. Not done.

On the other hand, retort sterilization is known as a relatively inexpensive equipment and severe sterilization treatment under high temperature and pressure.

However, if retort sterilization is performed at around 120°C with a conventional container configured as described above, the low-density polyethylene resin on the surface of the container will melt, and if the outer surface of the container is When they are placed side by side and sterilized, they fuse together, and when they are separated after sterilization, the film peels off. On the other hand, on the inner surface of the container, rough skin and pinholes occur, causing problems in terms of appearance and food hygiene. In addition, the strength of the joints between the main body of the container and the joint between the lid and the main body of the container is extremely reduced due to melting of the low-density polyethylene resin, and slight pressure fluctuations inside and outside the container during retort sterilization can cause damage to the joints. , easily caused the joint to shift or break the bag. Furthermore, water was absorbed from the edges of the container-based laminated material simply stacked and bonded, causing ink applied to the paper layer to bleed and the paper layer to peel off.

Therefore, when conventional containers are used for distribution at room temperature, heat sterilization at about 90° C. is the limit, and the types of contents to be filled are extremely limited.

Therefore, in order to increase the variety of filling materials, it is necessary to increase the heat sterilization conditions, and the general indicator for this is Fo value of 4 or more.

The Fo value represents the heating time required to kill a certain concentration of bacteria (spores) at a certain temperature, and is the lethal time in minutes at 250°C (121°C). Other temperatures are also expressed in terms of 250〓. It is said that the cl.bothlinum bacterium will die in 4 minutes at 250°C in a phosphate buffer.
It is expressed as Fo=4.

The present inventors have solved these drawbacks of the conventional technology, and by using a laminated material made of synthetic resin, paper, and aluminum foil as the main body of the container, the effects of the container can still be achieved, and retort sterilization is possible. As a result of intensive studies aimed at providing a food container with a significantly wider variety of filling materials, it was discovered that the objective could be achieved by paying particular attention to the joints of the container body, and the present invention was achieved based on this finding.

That is, the gist of the present invention is to form a cylindrical body by welding both ends of rolled and overlapping laminated materials made of synthetic resin, paper, and aluminum foil with both outer layers made of polyethylene resin or polypropylene resin excluding low-density polyethylene resin. A container in which both the upper and lower openings of the obtained cylinder are closed with a lid made of aluminum foil whose inner surface is coated with the same synthetic resin as the synthetic resin in the laminated material, One end in the width direction of a tape-shaped aluminum foil coated on both sides with the same synthetic resin as the synthetic resin is inserted between the overlapping both ends of the laminated material, and the other end is placed inside the overlapping part. The material is wrapped around the laminated material located on the outside of the cylinder, the tip of which is bent inward and welded, and the overlapping member that appears on the outside of the cylinder is covered with adhesive tape or a sealant is applied to the food container. Exists.

The present invention will be explained in more detail below.

As shown in FIG. 1, the food container of the present invention basically consists of a cylindrical body 1 and upper and lower lids 3.

The cylinder 1 is made of a composite material consisting of synthetic resin, paper, and aluminum foil, and both outer layers thereof are polyethylene resin or polypropylene resin except for low-density polyethylene resin. Here, low-density polyethylene resin refers to a resin with a density of 0.925 or less, as usual. The composite form of the composite material is, for example, from the inner surface of the cylinder: polyethylene resin or polypropylene resin excluding low-density polyethylene resin / adhesive layer / aluminum foil / adhesive layer / paper / polyethylene resin or polypropylene excluding low-density polyethylene resin. Although it is a resin, it is of course not limited to this, and aluminum foil and paper may be replaced, or a composite form with more layers may be used, and may be changed as desired. Here, the adhesive layer refers to polyethylene resin, excluding the low-density polyethylene resin that serves as both outer layers, or polypropylene resin and aluminum foil, the same resin and paper, and the adhesive layer that is interposed between the aluminum foil and paper to ensure good adhesion between each layer. For this purpose, low density polyethylene can be used as the adhesive layer.

In addition, paper is paperboard in the JIS terminology, and is a general term for thick paper made mainly of wood chemical pulp, ground wood pulp, straw pulp, waste paper, etc., and is made using a paperboard machine. This paper is hard and stiff, so it is often used as a packaging material, and there are cardboard base paper, yellow paperboard, and white paperboard, but white paperboard made by combining white paper stock is particularly preferred. used. The paper weight is usually
It is about 180 to 400 g/ ^m2 .

Furthermore, aluminum foil is a common material often used for packaging materials, etc., and its thickness is 5 to 150 μm.
That's about it. In particular, the cylindrical main body of the container is 70
~80μ, and about 150μ for the lid.

A laminated material made of such materials is molded by an appropriate molding method such as an extrusion lamination method.

In order to obtain the container of the present invention, first, the laminated material is rolled up and overlapped, and both ends are welded to form a cylinder. At this time, both sides are coated with a synthetic resin similar to the synthetic resin in the laminated material. Use tape-shaped aluminum foil. As shown in FIG. 2, one end of the aluminum foil is sandwiched between the overlapping ends of the laminated materials, and the other end wraps around the end of one of the laminated materials. The tip is bent inward to cover the overlapping portion, and the laminated material is welded and integrated at the same time as both end portions are welded.

In this way, the end portion of the laminated material located inside the overlapping portion of the obtained cylinder is completely quenched, and the inconvenience caused by water absorption from the inside of the cylinder (from the water content of the filling) is eliminated.

Both the upper and lower openings of the cylindrical body are welded and closed in a conventional manner with a guard made of aluminum foil whose inside is coated with a synthetic resin similar to the synthetic resin in the laminated material.

In the container of the present invention, an adhesive tape or a sealant is applied to the outer portion of the overlapping portion of the laminated materials to cover the portion.

The adhesive tape must continue to adhere to the packaging material even in hot water of about 120°C, and must be safe against hot water. Adhesive tapes that meet this requirement include, for example, commercially available adhesive tapes based on plastics such as polyester, polypropylene, cellulose triacetate, titrafluoroethylene, and polycarbonate.

Furthermore, the sealant is one that is cured by reaction through heating, moisture absorption, catalysts, etc., and must be safe for food use. Therefore, it is desirable to use one that does not use organic solvents or the like.

After the sealant has hardened, its adhesive strength with the outer surface of the container remains strong even in hot water at around 120°C, and the sealant itself does not crack or change in any way when exposed to hot water. things are applied. To meet this requirement,
Silicone sealant is used.

The food container of the present invention has such a configuration,
After filling the contents with food such as liquid drinks,
Applicable to normal retort sterilization.

As detailed above, the container of the present invention not only exhibits the effects of using a laminated material mainly composed of polyolefin resin, paper, and aluminum foil, but also can be sterilized by retort.
Therefore, the variety of filling materials is greatly increased, and the container is extremely useful as a food container.

Hereinafter, the present invention will be further explained based on Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 A laminated material for forming a cylindrical body, a tape-shaped aluminum foil for covering the joint of the laminated material, and a lid material were manufactured by extrusion lamination to have the following configuration.

Laminated material for cylinder formation: outer layer side, HDPE ¹ (25
μ) / Paperboard with gravure printing (270g /
m ² ) / LDPE ² (22μ) / Aluminum foil (12μ) /
LDPE ² (22μ) / HDPE ¹ (66μ), inner layer tape aluminum foil (width 20mm): HDPE ¹ (50
μ) / Aluminum foil (25μ) / HDPE ¹ (50μ) Lid material: Inner layer side, HDPE ¹ (50μ) / LDPE ² (30
μ)/Aluminum foil (130μ) 1 High-density polyethylene resin (Novatec
JV040, ρ = 0.968, Novatec is a registered trademark of Mitsubishi Chemical Industries, Ltd.) 2 Low density polyethylene resin (Novatec is a registered trademark of Mitsubishi Chemical Industries, Ltd.)
L300, ρ = 0.922, Novatec is Mitsubishi Chemical
(Registered Trademark of Co., Ltd.) From these materials, a container with lids on the top and bottom as shown in Figure 1 was manufactured, which was filled with 700 ml of water instead of food. (manufactured by F.L. Hetselmaschinenfabrik AG, HYPA system equipment) The joints of the cylinders of the resulting containers were made as shown in Figure 2, and silicone sealant (KE42RTV, trade name, Shin-Etsu Co., Ltd. (manufactured by Kagaku Kogyo Co., Ltd.) was applied uniformly to cover the surface and left at room temperature for 24 hours.
In this way, a food container of the present invention was obtained.

This container was sterilized by retort under the following conditions, assuming that the contents were a liquid food. The sterilizer used was an STR-100 test machine (steam and air heating method, manufactured by Fujimori Industries Co., Ltd.).

Retort sterilization conditions: Raise the temperature from the initial product temperature of 23°C to 120°C in 3 minutes, and hold at 120°C for 20 minutes. Set pressure: 1.3 to 1.5 Kg/cm ² (gauge pressure), cooling for 9 minutes (same set pressure), and draining for 5 minutes. After retort sterilization, the container has no shape abnormalities such as bag breakage or deformation, and the cylinder is No water seepage or ink bleeding due to pinholes was observed from the paper on the edge of the body joint.

The weight increase of the container after sterilization was 0.9 g (most likely due to heat absorption by the outer polyethylene layer).

In addition, the Fo value at the time of main sterilization was 6.9.

Comparative Example 1 A container filled with water was obtained in exactly the same manner as in Example 1, except that no sealant was applied to the outer surface of the joint of the cylindrical body of the container, and was further sterilized in the same manner.

After sterilization, the container maintained its normal appearance, but water was absorbed from the paper on the end surface of the joint of the cylinder, and printing ink had smeared over the entire packaging material.

The weight increase of the container after sterilization was 5.6 g.

Example 2 Polyester adhesive tape (Myrap, registered trademark, Nichiban Co., Ltd.) was applied to the outer surface of the joint of the cylinder of the container.
(manufactured by Knorr, Ajinomoto Co., Inc.) and paste the contents to prevent wrinkles.
A container was manufactured in the same manner as in Example 1, except that the liquid temperature was 80° C. during filling. The obtained container was subjected to retort sterilization under the following conditions.

Retort sterilizer: Rotorzwerg hot water rotary retort (manufactured by Stock, West Germany) Retort sterilization conditions: Temperature rise time 1 from initial product temperature 80℃
The temperature was reached to 120°C in minutes and held at 120°C for 19 minutes. Set pressure 2Kg/cm ² (gauge pressure), cooling 12 minutes (same set pressure), draining 4 minutes, rotation speed of the container holding cage in the retort pot 8 r.pm After sterilization, containers should not be broken or deformed. There was no abnormality or roughness on the outer surface, and there was no bleeding of printing ink due to water seepage from the paper on the end surface of the joint of the cylinder.

Furthermore, the inner surface of the container was also good.

The weight increase of the container after sterilization was 1.1 g.

In addition, the Fo value at the time of main sterilization was 5.1.

Comparative Example 2 A container filled with soup was obtained in exactly the same manner as in Example 2, except that no adhesive tape was applied to the outer surface of the joint of the cylindrical body of the container, and the container was sterilized in the same manner. After sterilization, the container maintained its normal appearance, but
Water was absorbed from the paper on the end surface of the joint of the cylinder, causing printing ink to bleed throughout the packaging material.

The weight of the container after sterilization increased by 15.2g.

Example 3 A laminated material for forming a cylindrical body, a tape-shaped aluminum foil for covering the joint of the laminated material, and a lid material were manufactured by extrusion lamination to have the following configuration.

Laminated material for cylinder formation: Inner layer side, PP ¹ (40μ)/
LDPE ² (20μ) / Aluminum foil (12μ) / LDPE ²
(22μ) / Paperboard with gravure printing (270g /
m ² )/LDPE ² (15μ)/PP ¹ (35μ) Tape-shaped aluminum foil (width 20mm): PP ¹ (35μ)/
LDPE ² (15μ) / Aluminum foil (25μ) / LDPE ²
(15μ) / PP ¹ (35μ) Supervision material: Inner layer side, PP ¹ (65μ) / LDPE ² (15μ) /
Aluminum foil (130μ) 1 Polypropylene resin [Polypropylene prototype (propylene-ethylene random copolymer)
MFI=7, ρ=0.899, ethylene content 2.5~4wt
%] 2 Low density polyethylene resin [Novatec]
L300, ρ=0.922, Novatec is Mitsubishi Chemical Corporation
(registered trademark of Co., Ltd.)] A container filled with water was obtained in the same manner as in Example 1 except that these members were used, and the container was further sterilized by retort under the following conditions.

Retort sterilization conditions: Temperature rise time 8 from initial product temperature 80℃
The temperature was reached to 140°C in minutes and held at 140°C for 10 minutes. Set pressure: 3Kg/cm ² (gauge pressure), cooled for 9 minutes (same set pressure), and drained for 5 minutes After sterilization, the container had no abnormalities such as breakage, deformation, or roughness on the outer surface. There was no bleeding of printing ink due to water seepage from the paper on the end surface of the joint.

Furthermore, the inner surface of the container was also good.

The weight increase of the container after sterilization was 1.1 g.

In addition, the Fo value at the time of main sterilization was 34.8.

Comparative Example 3 A container filled with water was obtained in the same manner as in Example 1, except that the members used in Example 3 were used, and no treatment was applied to the outer surface of the joint of the cylinder of the container. Sterilization was carried out under conditions.

After sterilization, the container absorbed water from the paper on the end surface of the joint of the cylinder, resulting in bleeding of printing ink and partial peeling of the film, resulting in loss of commercial value as a container.

The weight of the container after sterilization increased by 14.1g.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of the container of the present invention, and FIG. 2 is an enlarged partial cross-sectional view of the joint of the container cylinder. 1: Cylindrical body, 2: Laminated material constituting the cylinder, 3:
Lid material, 4: Tape-shaped aluminum foil, 5: Adhesive tape or sealant.

Claims (1)

[Claims] 1 A cylindrical body is obtained by rolling and overlapping a laminated material consisting of a synthetic resin, paper, and aluminum foil with outer layers of polyethylene resin (excluding low-density polyethylene resin) or polypropylene resin (excluding low-density polyethylene resin), and welding the ends on both sides to form a cylinder. A container in which both the upper and lower openings of a cylinder are closed with a lid made of aluminum foil whose inner surface is coated with the same synthetic resin as the synthetic resin in the laminated material, the container being made of the same synthetic resin as the synthetic resin in the laminated material. One end in the width direction of a tape-shaped aluminum foil coated on both sides with is inserted between the overlapping both ends of the laminated material, and the other end covers the laminated material located inside the overlapping part. A food container that is wrapped, the tip is bent inward and welded, and the overlapping portion that appears on the outside of the cylinder is covered with adhesive tape or a sealant.