JPH06219469A - Retort container heat seal method - Google Patents

Abstract

PURPOSE:To prevent a sealed cover member from peeling during retort sterilization and to make it possible for a user to peel the cover member easily, by a method in which a weak bond-strength zone which can be easily peeled is created inside a strong bond-strength zone after the retort sterilization, and then the strong bond-strength zone is cut off. CONSTITUTION:Food 11 is put in a container body 1, the body 1 is covered with a cover member 4, and the cover member 4 is sealed with respect to a flange 3 along the periphery of the flange 3 by the application of heat until it is completely melted so as not to be deformed by heat, thereby creating a strong bond-strength zone 6. Subsequently, the entire container is subjected to retort sterilization under the ordinary process conditions, and, further, a weak bond-strength zone 7 is created inside and along the strong bond-strength zone 6 by sealing the part between the cover member and the flange 3 by the application of heat. The bond strength of the weak bond-strength zone 7 is such that the cover member can be easily peeled with a medium force by holding a projection between finger tips. Then, the part shown by the symbol A is cut, and the part including the strong bond-strength zone 6 is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to fill various kinds of foods into a plastic container body, heat seal the opening of the container body with a lid material made of a plastic sheet, and use a retort sterilizer under pressure. The present invention relates to a heat-sealing method for producing a retort container product by heating at high temperature.

[0002]

2. Description of the Related Art Conventionally, to manufacture retort container food,
After filling a container body made of plastic with a substance to be contained, a plastic sheet is covered on the opening of the container body, and the plastic sheet is heat-sealed and hermetically sealed on a flange formed in the opening. The sealed product is heated and sterilized in a retort sterilizer under high pressure at a high temperature of 100 ° C. or higher, preferably 120 ° C. or higher to obtain a product.

[0003]

In the above-mentioned prior art, the heat sealing of the plastic sheet as the lid to the opening of the container body is performed by the internal pressure generated in the container during the subsequent high pressure and high temperature retort sterilization treatment. It must be heat-sealed with a fairly high contact strength so as not to peel off against. Meanwhile, from retort container products,
When removing the contents, the end of the lid material consisting of a heat-sealed plastic sheet is pinched by the fingertips and pulled, but it is desirable that it can be easily opened especially by children, and the adhesive strength of the heat seal is relatively small. Must be done.

[0004] It is very difficult to satisfy the above-mentioned contradictory demands at the same time, and in order to produce a safe product, the strong adhesive strength between the lid material of the plastic sheet and the container body is given priority, and therefore, It tended to be difficult to open during use. The present invention, during the retort sterilization process for producing a retort container product, the plastic sheet as the sealing lid material does not peel off, and when the end user tries to open the lid material, the lid is a normal fingertip. It is an object of the present invention to provide a method for producing a retort container product that can be easily peeled off by force.

[0005]

The present invention achieves the above object, and the gist of the present invention is to fill a container body made of plastic having a wide flange portion in an opening portion with an object to be contained. After that, at the opening of this container body,
Including the wide flange portion, cover with a lid material made of a plastic sheet of a size that covers the opening, along the outer edge circumference of the wide flange portion, and inside the outer edge circumference, during the retort sterilization process, the lid. The lid material is heat-sealed to the flange of the container body with a strength that does not cause peeling of the material to form a strong adhesive strength zone, and then subjected to retort sterilization treatment
Then, along the inside of the strong adhesive strength zone, at a distance, heat the lid material to the flange portion to form a weak adhesive strength zone that can be easily peeled when pulled with a fingertip in the direction of peeling the heat-sealed lid material. A heat-sealing method for a retort container is characterized by sealing, and thereafter, leaving the above-mentioned weak adhesive strength zone and cutting off the strong adhesive strength zone.

The present invention has two requirements for a retort container, namely, heat-sealing the lid sheet plastic sheet with strong adhesive strength during retort sterilization treatment and the lid sheet plastic sheet during opening of the final product. The weak adhesive strength heat-sealing that satisfies the easy opening property is distinguished by the wide flange on the container body, and the two requirements are met together. That is, in the wide flange in the container body opening,
After forming the strong adhesive strength zone on the outer side, retort sterilization treatment is performed, then the weak adhesive strength zone is formed on the inner side of the adhesive strength zone, and finally the strong adhesive strength zone is cut off.

As the container body used in the present invention, conventionally,
The material used for this kind of container is used. As an example, ethylene-rich gas barrier
The thing which laminated | stacked the layer of polypropylene on both surfaces of the layer of the saponification product of a vinyl acetate copolymer is mentioned. A wide flange is formed in the opening of the container body, but in the present invention, in this wide band, a strong adhesive strength band and a weak adhesive strength band are appropriately spaced (after retort sterilization treatment, weak adhesive strength band). Since the strong adhesive strength band is cut away, there is a sufficient distance for this cutting, for example, punching can be performed). If there is

As a lid material made of a plastic sheet for closing the opening of the container body, one conventionally used as a lid material of this type is used. As a concrete example, a polyethylene terephthalate layer is made of polypropylene. The thing which laminated | stacked the layer is mentioned. In this case, since the lid material is heat-sealed to the flange of the container body, the polypropylene layer is used so as to be in contact with the flange. The lid material may be such that the surface in contact with the flange is a plastic layer heat-sealable to the flange,
Therefore, an aluminum foil having a high gas barrier property may be laminated and used as the other layer. However, aluminum foil should be avoided when microwaved in the final use of retort pouch foods.

[0009]

EXAMPLES The present invention will be described in more detail by way of examples, which should not be construed as limiting the invention. Example FIG. 1 is a schematic vertical sectional view of an example of an intermediate product in the process of manufacturing a retort container product by carrying out the method of the present invention, and FIG. 2 is a schematic bottom view of the intermediate product of FIG.

In the figure, reference numeral 1 is a container body made of plastic which constitutes food in a retort container. This container body 1 is, for example, a layer of polypropylene (thickness of 0.15 to 0.7 mm) laminated on both sides of a layer of saponified product of ethylene-vinyl acetate copolymer (thickness of 0.05 to 0.15 mm). The laminated body is formed by thermoforming a sheet laminated by dry lamination or coextrusion. Reference numeral 2 denotes a polypropylene layer inside the container body 1, which can be heat-sealed with a lid member 4 described later.
Reference numeral 3 denotes a wide flange portion at the opening of the container body 1. Reference numeral 4 is a lid member made of a plastic sheet. This lid member 4 is a layer of polyethylene terephthalate (thickness 10 to 10).
30μ) layer of polypropylene (thickness 50-100μ)
In the laminated sheet, the polypropylene layer 5 of this sheet is in contact with the polypropylene layer 2 of the container body 1, and the lid member 4 is covered on the opening of the container body 1.

Reference numeral 11 denotes, for example, cooked food contained in the container body 1. After putting the food 11 in the container body 1 and covering the opening of the container body 1 with the lid member 4, 6 in FIG.
At the position indicated by, that is, at the band portion along the peripheral edge of the flange portion 3 of the container body 1 and inside the outer peripheral edge.
Is heat-sealed to the flange portion 3 and completely fused to the extent that it is not thermally deformed to form a strong adhesive strength zone 6.
The adhesive strength in this zone 6 is
The lid member 4 has such strength that it does not peel when subjected to high temperature sterilization treatment under pressure in a retort sterilization apparatus. A suitable strength for this is 2.3 kg / 15 mm width or more.

The adjustment of the adhesive strength by the heat sealing can be achieved by adjusting the heating temperature and the pressing degree during the heat sealing. Next, the entire container is subjected to retort sterilization treatment under a generally adopted treatment condition, and the lid member 4 of the container that has undergone this treatment is further heat-sealed with the flange portion 3 to obtain a weak adhesive strength band. Form 7.
The device for forming the weak adhesion strength zone 7 is inside the position of the strong adhesion strength zone 6 and substantially along the band of the braces. However, as shown in FIG. 2, the weak adhesive strength zone 7 does not project at a portion where a knob piece 9 described later is formed, and has a circular shape.

The adhesive strength in the weak adhesive strength zone 7 is smaller than that in the strong adhesive strength zone 7, and the knob piece 9 is pinched with a fingertip so that it can be easily peeled off by a normal force. That is, its strength is 0.7
A range of up to 1.5 kg / 15 mm width is preferable, and a range of 1 to 1.3 kg / 15 mm width is particularly preferable.

Next, between the strong adhesive strength zone 6 and the weak adhesive strength zone 7, the portion indicated by A in FIGS. 1 and 2 is cut (punching), leaving the weak adhesive strength zone 7 and The portion including the adhesive strength zone 6 is removed. This cutting line of A is shown in FIG.
Inside, as shown by the dotted line, it projects outward at the position where the knob piece 9 is formed. In order to form this knob piece 9, the flange portion 3 of the opening of the container body 1 and the lid member 4 are also formed in advance with a portion protruding outward (a portion indicated by reference numeral 8 in FIG. 2). As described above, a retort container product that can be easily opened by pinching with a fingertip is obtained.

[0015]

According to the method of the present invention, the lid material for sealing the container body does not peel off during the retort sterilization process, and can be easily opened when the end user of the product tries to peel off the lid material. A container is obtained.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an example of an intermediate product when a retort container product is manufactured by carrying out the method of the present invention.

2 is a bottom schematic view of the intermediate product of FIG. 1. FIG.

[Explanation of symbols]

 1 Container Main Body 3 Wide Flange 4 Lid 6 Strong Adhesion Strength Band 7 Weak Adhesion Strength Band

Claims (1)

[Claims] 1. A container main body made of plastic having a wide flange portion at the opening is filled with an object to be contained, and then the opening of the container main body includes the wide flange portion,
Covering a lid material made of a plastic sheet of a size that covers the opening, along the outer peripheral edge of the wide flange portion, and inside the outer peripheral edge, the strength that does not cause peeling of the lid material during retort sterilization treatment. Heat seal the lid material to the flange of the container body to form a strong adhesive strength zone, and then subject it to retort sterilization treatment, and then heat it along the inner side of the strong adhesive strength zone at intervals. The flange is heat-sealed with the lid material so as to form a weak adhesive strength zone that can be easily peeled off when pulled with a fingertip in the peeling direction of the sealed lid material. A method for heat-sealing a retort container, which comprises cutting a zone.