JPH0211332Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a sealed container for easily preserved foods, etc., whose plastic film lid can be easily peeled off and opened.

[Prior Art] Today, retort sterilization has been adopted as a sterilization method that can maintain the quality of food stored in containers for a relatively long period of time and has good food storage efficiency. Container bodies made of polypropylene resin are increasingly being used as a material suitable for retort sterilization.

Recently, instead of covering the container body with a molded lid, it has become common to cover the container body with a laminated film, which is cheaper and easier to cover than a molded lid.

[Problems to be solved by the invention] By the way, even though the lid body is made of film, it has considerable strength, so if a part of the laminated film breaks when opening the lid, the laminated film covered with the lid will be damaged. Since it takes a considerable amount of effort to remove the remaining portion, it is desirable that the covered laminated film be easily removed at the portion where it is bonded (heat-sealed) to the container opening. To do this, the adhesive part of the bonded laminated film must be easily peeled off at the adhesive surface, but on the other hand, it is required to be completely sealed until the package is opened, and both the maintenance of this seal and the ease of peeling are required. It was difficult to do so.

Polypropylene resin is often used in retort containers, and after food is stored in the container body, the container body is covered and retort sterilized. An adhesive must be selected that can be easily peeled off from the container body, which is a polypropylene resin, and can cover the container body with good sealing adhesion.

[Means for Solving the Problems] The present invention is a container made of a material suitable for retort sterilization that satisfies the above requirements, in which at least the upper surface of the mouth flange 11 of the container body 10 is made of polypropylene, and the mouth flange 11 is made of polypropylene. A linear upper convex portion 1 on the upper side of the portion 11
4, and the cross-sectional shape of at least the outer side 13 of the mouth flange 11 is a curved surface, and for this container body 10, a blend of high-density or medium-density polyethylene and polyisobutylene is used. The polypropylene of the container body 10 and the blend layer of the laminated film 21 are bonded together by using the plastic film 21 including a plastic layer to provide an easily peelable sealed container covered with the plastic film 21.

[Function] As described above, since the present invention adheres the blend layer of the lid 20 to the polypropylene that forms the upper surface of the opening of the container body 10, it is possible to achieve a reliable seal and to provide a slightly stronger seal when desired. The lid body 20 can be easily peeled off by peeling it off, and both sealing performance and ease of peeling can be balanced.

By forming the outer part 13 of the mouth part flange part 11 into a curved surface shape with an R so as to curve it downward, when the outer part 13 is bonded by applying pressure and heat, the outer part 13 is curved downward.
3 gradually descends from the flange 11 on the flat plate, so the adhesive force on the outer side 13 is weaker than on the inside, and when the end 23 of the lid is pulled up for opening, the lid 20 can be easily and reliably moved. It may peel off from the adhesive surface (peelable peeling), and
By forming the linear upper protrusion 14 on the upper surface of the mouth flange 11, the mouth flange 11 and the lid 20 can be firmly and securely bonded to each other.

[Example] As an example of the present invention, the first and third layers are made of polypropylene, the middle layer is made of three layers of ethylene-vinyl alcohol copolymer, and the adhesive between them is made of maleic acid-modified polyolefin. A container body 10 is formed using a laminated sheet bonded with an adhesive, and a lid body 20 made of a laminated plastic film is placed on the container body 10. At this time, a layer of a blend of high-density or medium-density polyethylene and polyisobutylene is applied to the opening of the container body 10 formed from the laminated sheet of polypropylene/ethylene-vinyl alcohol copolymer/polypropylene. A laminated film, which is a plastic film 21, is used as the lid 20, and the blend layer is used as an adhesion surface.

As an example of the structure of the laminated plastic film 21 used as the lid body 20, the first layer is made of nylon or polyester, the second layer is made of aluminum foil,
The third layer is the polyethylene blend layer,
A three-layer laminated film 21 is bonded between them with a urethane adhesive, and the laminated film 21 is used to cover the polypropylene layer of the container with a polyethylene blend layer to provide sealing performance and ease of peeling. I was able to achieve both.

Then, a lid body 20 used for the above-mentioned lid
When blending high-density or medium-density polyethylene and polyisobutylene, which serve as the adhesive surface, the blending ratio of 84 to 92% by weight of polyethylene and 8 to 16% by weight of polyisobutylene was used. However, good adhesion and easy-to-peel adhesion were obtained.

Furthermore, when the above-mentioned laminated film 21 is easily peeled off and covered with the plastic film 21 containing a blend layer of high-density or medium-density polyethylene and polyisobutylene, the polypropylene container body 10 can be easily peeled off. As shown in FIG. 1, the cross section of the upper surface of the mouth flange 11 is such that an upper convex portion 14 is provided on the upper surface of the mouth flange 11.
The outer portion 13 of the outer portion 13 has a curved shape (a shape marked with an R).

This is because when the upper side of the mouth flange 11 of the container body 10 is flat as shown in FIG. 2, the sealing area becomes large and a large amount of pressure is required for bonding. A thin wall portion 22 is formed in the laminated film 21 bonded at the outer end of the lid 11, and when the lid end 23 is pulled up to open the package, the lid 20 is removed before the adhesive surface on the upper surface of the mouth flange 11 peels off. Frequently, the thin wall portion 22 broke at the end, making it difficult to open.

Therefore, as in the present invention, the outer part 1 of the mouth flange 11 is
3 is curved downward to form a curved surface with an R mark, so that when the laminated film 21 is bonded to the mouth flange 11 by pressure heating, the outer portion 13 is more easily attached to the flange 11 on the flat plate. Since it is gradually lowered, not only does the adhesive force in the outer part 13 gradually become weaker as it goes outward, but also the outer part 13 of the lid body 20 has a thinner part 22 as shown in FIG. Since no edges are formed, the lid 20 can be easily and reliably peeled off from the adhesive surface (peelable peeling) when the lid end 23 is pulled up during unsealing.

Furthermore, when the upper protrusion 14 is provided on the upper surface of the mouth flange 11 of the container body 10 and the outer part 13 is curved, the adhesive strength at the upper protrusion 14 is further strengthened, but the adhesive strength of the outer part 13 is further increased. The adhesive strength can be further weakened, and even if the lid 20 and the mouth flange 11 are firmly bonded with the upper protrusion 14, the upper protrusion 14 has a narrow linear shape. The force required to peel off the lid body 20 is small, and the effect of further ensuring both strong sealing and easy peeling can be achieved.

In addition, the laminated film 21 used as the lid body 20 has a first layer, a second layer, and a third layer each made of polyester/
A similar effect was obtained with the three-layer laminated film 21 made of an aluminum foil/polyethylene blend, a nylon/aluminum foil/polyethylene blend, and a polyester/EVAL/polyethylene blend.

Furthermore, it will be described that similar effects were obtained in the laminated film 21 consisting of two layers in which the first layer is made of polyester and the second layer is made of a polyethylene blend.

In addition, in any of the above-mentioned laminated films 21, the blend layer of high-density or medium-density polyethylene and polyisobutylene of the laminated film 21 is used as the adhesive surface for the polypropylene single-layer or multi-layer container body 10, and the polypropylene By pressurizing and heating the opening flange 11 of the container body 10, which is made of aluminum, it was possible to create a bond that was easily removable while ensuring a reliable seal.

Although the container bodies 10 described above were all made of polypropylene, they are suitable for retort sterilization.
For example, even if the container has two or more layers of polypropylene and a resin made of ethylene-vinyl alcohol copolymer polyester, nylon, etc., the adhesive surface may be made of polypropylene.

In short, the adhesive surface of the mouth flange 11 of the container body 10 to the lid 20 is made of polypropylene resin,
In addition, both the polypropylene of the container opening and the polyethylene blend layer of the lid 20 are bonded together, and an upper convex portion 14 is formed on the upper surface of the opening flange 11.
By forming the upper corner portion of the outer portion 13 in a curved shape, good effects as shown in the above-mentioned embodiments could be obtained.

[Effects of the invention] As described above, in the present invention, the plastic film 21 is covered with a blend layer of polyisobutylene to the polypropylene of the container flange 11, so that the relationship between the lid 20 and the container body 10 is good. In addition, when unsealing, the lid body 20, which is a laminated plastic film 21, can be reliably peeled off and opened on the adhesive surface. Upper convex part 14 on the side
In addition, since the shape of the upper corner of the outer part 13 is a curved surface, when the plastic film 21 is adhered to the flange part 11 of the container body 10, the thin part 22 is formed on the lid body 20 made of the plastic film 21. The adhesive strength at the outer periphery of the adhesive portion between the container body 10 and the lid body 20 is weakened, and
The upper convex portion 14 firmly brings the lid 20 and the flange 11 of the container body 10 into close contact while preventing an increase in the force required for peeling, making it easier to peel and open the lid 20 and sealing. This is a sealed container that is suitable for retort sterilization and has both properties and ease of peeling.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part showing the lid of a container according to the present invention, and FIG. 2 is a sectional view of a main part of a conventional container in a covered state. 10...container, 11...mouth flange, 13...1
1 outer part, 14...11 upper convex part, 20...
Lid body, 21... Laminated film, 22... Lid body thin part, 23... Lid body end part.

Claims (1)

[Scope of utility model registration request] A container having a flange at the mouth of the container body,
In a container covered with a plastic film, the container body is mainly made of polypropylene, and at least the upper surface of the mouth flange of the container body is made of polypropylene, and the upper surface of the mouth flange is made of polypropylene. forming a linear upper convex portion, and
The outer upper corner of the mouth flange has a curved shape that is curved downward, and the plastic film covering the upper surface of the polypropylene mouth flange is made of high-density or medium-density polyethylene and polyisobutylene. 1. A sealed container for a retort that is easy to peel and is characterized by a structure in which a blend layer containing 8 to 16% by weight of the following is adhered to the mouth flange as an adhesive surface.