JPH0569507A - Sealed container - Google Patents

Abstract

PURPOSE:To provide a container, which has excellent keeping quality and sealing properties and does not spoil flavors of various kinds of food as contents. CONSTITUTION:Sealant layer A is made of one selected from the group consisting of polycarbonate, polybutylene terephthalate and polyethylene terephthalate. As gas barrier layer B, aluminum foil or steel foil is employed. Base material layer C is made of polypropylene. The container concerned is produced by laminating the above-mentioned layers to one another in the order of A-C-B-C under the condition that the thickness of the base material layer is set to be not less than 30% and not more than 70%. The container is sealed with a lid having gas barrier properties.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetically sealed container having excellent storability and physical properties against contents.

[0002]

2. Description of the Related Art Conventionally, a metal can has been the most excellent storage container for storing food. However, in recent years, there are problems such as its designability and that the container is easily deformed when it is impacted, and the demand for it is decreasing in some food applications, and consumers desire a container that solves these problems. It was rare. On the other hand, Toyo Seikan Co., Ltd. "Highlet Flex" (see FOOD PACKAGING 1988/3)
64-70, "Aluminic can" manufactured by Showa Aluminum Co., Ltd. (see Japan Food Science 1988/869).
-75), Showa Denko's "NP can" (reference Japan Food Science 1989/2 61-66), as shown in the plastic (polyolefin) flexibility, deformation resistance, design and metal (steel foil, A polyolefin-metal composite container that combines the storability of aluminum foil) was put on the market, and as a storage container to replace the conventional metal can,
It came to be used. However, in recent years, as researches such as alteration of contents proceed, in containers containing polyolefin in the inner layer, the innermost layer adsorbs the flavor of the contents,
It was found that the odorous component of the resin layer of the innermost layer was transferred to the contents, and the innermost layer other than polyolefin was required.

As containers having these flavor characteristics, containers having polyethylene terephthalate or ethylene vinyl alcohol copolymer as an inner layer have been proposed (JP-A-3-244 and JP-B-55-13907). However, the gas barrier layer was incomplete, or there was a problem in terms of formability, etc. structurally.

[0004]

The present invention has been made as a result of various studies in order to solve these problems of the conventional hermetically sealed containers, and the object is various foods whose contents are different depending on the container. The purpose of the present invention is to provide a container that is excellent in storability and hermeticity without impairing the flavor of.

[0005]

The present invention has one of polycarbonate, polybutylene terephthalate and polyethylene terephthalate as a sealant layer (A) and a gas barrier layer (B) having an aluminum foil or a steel foil as a base material. The layer (C) is polypropylene and those layers are A-
C-B-C are laminated in this order, and the base material layer is 30% of the total thickness.
As described above, the container of 70% or less is hermetically sealed with a lid having a gas barrier property.

Any polycarbonate can be used as the polycarbonate used in the present invention. Also, a mixture of a small amount of polyethylene terephthalate or the like can be used as long as the flavor characteristics are not affected.

The polybutylene terephthalate and polyethylene terephthalate used in the present invention can be obtained by solution polymerization of a low polymer obtained from terephthalic acid and ethylene glycol or butylene glycol by a usual esterification reaction or an exchange reaction. Or a solid-state polymerized product thereof. In addition to these, various acid components and polyhydric alcohol components can be used as copolymerization components.

The aluminum foil or steel foil used in the present invention may be a usual one. The foil thickness is preferably 50 microns or more for aluminum foil and 25 microns or more for steel foil.

As the polypropylene used in the present invention, various polypropylenes such as homo, copoly and random can be used. Further, other resin such as polyethylene can be mixed to improve moldability and spreadability.

As a method for laminating these resins, known laminating techniques such as a coextrusion laminating method, an extrusion laminating method and a dry laminating method are used. Further, in order to bond the resins to each other for stacking them, an adhesive suitable for the individual resins or an adhesive resin is used.

As a method for molding these multilayer sheets into a container, cold working is used by setting a male mold and a female mold that match the container shape so that there is an appropriate space.

As the lid material used in the present invention, any material can be used as long as it can seal the innermost layer and has a gas barrier property. For example, there is a three-layer film in which the sealant layer is polycarbonate, the barrier layer is vinylidene chloride copolymer, the outermost layer is nylon, the sealant layer is heat-sealable polyethylene terephthalate, the barrier layer is aluminum foil, and the outermost layer is polyethylene terephthalate. Further, the lid is not limited to the film shape, and a molded article form may be used. For example, the sealant layer is a heat-sealable polyethylene terephthalate, the barrier layer is an ethylene vinyl alcohol copolymer, the outer layer is a polypropylene multi-layer sheet by vacuum forming,
It is possible to mold and use it in the shape of a drop lid, or to mold and use the same structure as the main body container into a shallow molded product. As a method for welding these lid and main body container, known heat sealing method, ultrasonic sealing method, and high frequency sealing method are used.

[0013]

The function of the present invention will be described. The polycarbonate, polybutylene terephthalate and polyethylene terephthalate layers of the sealant layer used in the container of the present invention are used for flavor protection of the contents. Further, these sealant layers have excellent heat resistance among thermoplastic resins and can be used for foods that require retort sterilization.

In order to prepare the container of the present invention, it is necessary to consider the ratio of resin constituting the container. When the polypropylene as the base material layer is 30% or less, the deformation resistance after molding the container is poor, and deformation is caused by a small impact, and the merit of compounding cannot be obtained. In addition, when the thickness is 70% or more, the strength of the metal layer as the barrier layer is lower than the strength of the base material layer, and there is a defect that the residual stress of the base material layer causes deformation after cold forming. If it is not within the range of the present invention, a good molded product cannot be obtained. The polypropylene layer used in the present invention is used as a layer for preventing deformation caused by impact and a layer for improving design.

[0015]

EXAMPLES The effects of the present invention will be described with reference to the following examples. Table 1 shows the configurations of the three types of multilayer sheets used for comparison with Example 3 used in the present invention. These multilayer sheets were prepared by the dry lamination method. These multi-layer sheets are made by cold-working male and female molds to make a container with a diameter of 80 mmφ, a height of 50 mm and a bottom diameter of 40 mmφ. Hot filling at 60 ° C, the latter is stored at 120 ° C for 30 minutes after retort sterilization, and then stored for 1 month at room temperature.
The flavor suitability was compared. In addition, a comparative evaluation was performed on the formability during cold forming. The results are shown in Table 2. or,
Although not shown in the table, a container having a base layer thickness ratio of 20% and a gas barrier layer of aluminum foil filled with the same contents as above, packed in 50 pieces of cardboard, and subjected to a transportation test between Tokyo and Osaka. , All the containers were deformed and were not commercial products.

[0016]

[Table 1]

[0017]

[Table 2]

[0018]

According to the present invention, as compared with the conventional plastic-metal composite container, a container which does not change the flavor of the contents is obtained, and a container having excellent storability is obtained.

Claims (1)

[Claims] 1. A sealant layer (A) comprising one of polycarbonate, polybutylene terephthalate and polyethylene terephthalate, and an aluminum foil or a steel foil as a gas barrier layer (B), and a base material layer (C) comprising polypropylene. A container in which those layers are laminated in the order of A-C-B-C and the base material layer is 30% or more and 70% or less of the total thickness is sealed with a lid having gas barrier properties. Sealed container to do.