JPS621895B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a sealing device formed by circumferentially thermally bonding the open end of a container body and the peripheral portion of a lid that contacts the inner wall or outer wall of the open end. Regarding containers.

(Prior Art and its Problems) Conventionally, containers with a sealing structure based on thermal adhesion such as heat sealing have been widely used in the field of packaging foods and the like, but they are still subject to many restrictions. For example, heat sealing can be used to seal the end of a bag-like container, to form a joint between a cylinder, or to seal a flat flange at the open end of a container body and a lid, when the parts to be joined are straight and flat. Although it is relatively easy to operate and a highly reliable seal can be obtained if a relatively large planar sealing surface can be secured, the inner or outer peripheral surface of the opening edge of the container body When the area to be heat-sealed is three-dimensional and a sufficient sealing area cannot be secured, as in the case of the periphery of the lid body, the heat-sealing operation itself is not necessarily easy, and the heat-sealing process itself is difficult. It becomes difficult to form a secure and reliable seal around the entire circumference of the part.

The second problem is that the contents rise up to the heat seal interface. In other words, in order to reliably seal the container body and lid at high speed, it is necessary to fill the container body with the contents, as is conventionally done when double-sealing the can body and can lid. After that, it is advantageous to seal the lid while rotating it. However, when such a sealing method is applied to a heat-sealed container, the contents rise to the interface to be heat-sealed due to centrifugal force, making the heat-sealing uneven and unreliable. Thus, in the conventional heat sealing method, the heat sealing method under rotation has not been adopted for liquid contents except for things such as seaweed and dry powder.

(Object of the Invention) Therefore, the present invention provides a sealed container in which the open end of the container body and the peripheral portion of the lid that contacts the inner wall or outer wall of the open end are circumferentially thermally bonded. In the circumferential and band-shaped part between the lid body and the part to be thermally bonded,
The technical problem is to form a reliable and uniform sealing structure even when liquid contents are attached or filled.

(Structure of the Invention) That is, the sealed container of the present invention has the following features: (i) The inner wall or the outer wall and the lid strongly engage with the peripheral portion of the circumferential lid that is in contact with the inner wall or the outer wall at the open end of the container body. a plurality of grooves to be thermally bonded are formed at small intervals; (ii) a plurality of strongly bonded portions corresponding to the grooves are formed in any direction passing through the circumferential thermally bonded portion between the container body and the lid; The structure is characterized in that a weakly bonded portion or a non-bonded portion exists between the grooves.

In addition, the above-mentioned sealed container includes: (A) engaging the open end of the container body with a lid having a peripheral portion that is in contact with the inner wall or outer wall of the open end; (B) the body-lid assembly; (C) heating the circumferential and band-shaped engagement portion between the three-dimensional lid and the opening end; A plurality of grooves through which the engaging portion passes and are strongly engaged and thermally bonded to the peripheral portion of the lid that contacts the inner wall or outer wall of the body, and weakly bonded portions or non-bonded portions corresponding between the grooves. It is obtained by forming .

(Function) In the sealed container of the present invention, the engagement portion between the lid periphery and the opening end of the body to be sealed includes a strongly bonded portion formed by the groove and a weakly bonded or non-bonded portion between the grooves. Because they are arranged alternately, even if the content adheres to or is filled with the engaging part, the groove part crushes the content at the heat-sealing interface and provides a strong seal when the content is removed. While heat sealing is possible, in the weakly bonded or non-bonded areas,
Since it acts as a preliminary space to receive the contents removed from the heat-sealed interface, it is possible to seal the entire circumference of the engaging portion by reliable and strong heat-sealing.

In addition, since a weakly bonded or non-bonded portion is always formed between the grooves in any direction that traverses the circumferential engagement portion, contents or gas may leak through this weakly bonded or non-bonded portion. will also be effectively prevented.

(Operation and Effect) According to the present invention, by applying the above-described heat-seal sealing method to the circumferential engagement portion between the lid and the body, the heat-seal seal can be achieved even when the liquid content rises up. This makes it possible for the first time to place a lid over the body of a container filled with liquid contents, and while rotating in this state, form a seal by heat-sealing the two. This provides extremely great advantages both for the purpose of performing various types of heat sealing and from the standpoint of performing heat sealing at high speed.

(Description of Preferred Embodiments of the Invention) Referring to FIG. 1, which shows the overall structure of an example of a sealed container of the present invention, this sealed container includes a cylindrical body 1 with both ends open, and a cylindrical body 1 that is open at both ends. a lid body 3 which is hermetically engaged with both openings of the body through a heat seal part 2;
It consists of 3.

In FIG. 2, which shows an enlarged cross-section of the heat-sealing part 2, the laminate 4 forming the body part 1 includes a metal foil substrate 5, a heat-sealable resin layer 6a applied to the inner and outer surfaces of the substrate, and It consists of 6b and
On the other hand, the laminate 7 constituting the lid 3 also includes a metal foil substrate 5a, a heat-sealable resin layer 6c applied to the inner surface of the substrate, and a protective resin layer 8 applied to the outer surface.

A U-shaped groove 9 is formed in the periphery of the lid 3, and the open end 10 of the body 1 is inserted into the U-shaped groove 9, thereby sealing the heat-sealable resin layer 6c of the lid 3 and the body. Thermal adhesion by heat sealing is performed between the inner wall side heat sealable resin layer 6c and/or the outer wall side heat sealable resin layer 6b of 1, thereby forming a circumferential and belt-shaped heat sealing portion.

According to the present invention, the U-shaped groove 9 in the peripheral portion of the lid portion in contact with the opening end portion 10 of the body portion, that is, in FIG.
A plurality of grooves 12 are formed at small intervals in the inner wall portion 11 of the lid 3, and the heat-sealable resin layer 6c of the lid 3 and the heat-sealable resin layer 6a of the body 1 are strongly pressed and thermally bonded. At the same time, there is a weakly bonded part or a non-bonded part 1 between these plurality of grooves 12.
3 is formed. Moreover, in the present invention, a plurality of groove portions 1 are necessarily formed in any direction that traverses the circumferential and strip-shaped heat seal portion.
2, 12 and a corresponding weakly bonded portion or non-bonded portion 13 between the grooves.

In the present invention, by adopting the above-described configuration, remarkable advantages in terms of sealing reliability and sealing workability are achieved as described above.

In the present invention, the arrangement of the strongly bonded part by the groove 12 and the weakly bonded or non-bonded part 13 between the grooves can be freely changed within the range that satisfies the above-mentioned restrictions. In the specific example shown in FIG. 2, two ring-shaped grooves 12,
12, and a single circumferential weakly bonded or non-bonded portion 13 is provided between the grooves. From the viewpoint of leakage prevention, it is desirable that this weakly bonded or non-bonded portion 13 be divided into as small parts as possible. In the preferred embodiment shown in FIG. 3, in addition to the two circumferential grooves 12,
A large number of short grooves 12a in the axial direction are provided at small intervals to divide the weakly bonded or non-bonded portion 13 into small regions. Furthermore, in the specific example shown in FIG.
Between the two circumferential grooves 12, 12, a large number of combinations of grooves 12b and 12c are provided at small intervals in a crosshatch pattern.

In the present invention, the depth of the groove may be any depth as long as it crushes or expels the contents existing at the interface to be heat-sealed and allows the heat-sealing resin layers to be firmly fused and integrated. Although this depth varies considerably depending on the layer structure of the laminates 4 and 5, generally speaking, it is 0.1 to 1.0 mm, particularly 0.3 to 1.0 mm.
A depth of 0.7 mm is advantageous for the purposes of the invention. On the other hand, the gap between each groove is 0.5 to 3.0 mm, especially
A range of 1.0 to 2.0 mm is desirable from the standpoint of containing foreign matter present at the heat seal interface.

In the present invention, the laminate 4 constituting the container body
In view of the shape retention properties of the body, it is particularly desirable that the body be a laminate that also includes a paper substrate. In FIG. 5 showing this specific example, a trunk forming laminate 4a
includes a paper substrate 14 in addition to the metal foil 5, and heat-sealable resin layers 6a and 6b are provided on both surfaces of the paper substrate 14. In the laminate 4a shown in this specific example, the paper substrate 14 and the metal foil 5 are bonded together via a heat-sealable resin layer 6d.

In the body of this type of sealed container, from the viewpoint of preserving the contents, the metal foil 5 is arranged on the inside of the container and the paper substrate 14 is on the outside of the container.
Thus, in the specific example shown in FIG. 5, the layer structure of the heat-sealable resin layer 6a, the metal foil 5, the heat-sealable resin layer 6d, the paper substrate 14, and the heat-sealable resin layer 6b is arranged from the inside to the outside. It's summery.

In the sealed container of the present invention, the body opening end 10
can also have any structure. For example, the second
In the container shown in the figure, the open end 10 has a single layer structure, but in the specific example shown in FIG. It is bent so that it is on the inside, and its cut edge 15 is wrapped around this folded part.

In the present invention, a heat-sealable thermoplastic resin, particularly a thermoplastic resin heat-sealable at a temperature of 90 to 300° C., is used as the heat-sealable resin layer. Suitable examples thereof include, but are not limited to, olefin resins such as low-, medium- and high-density polyethylene, crystalline polypropylene, crystalline propylene-ethylene copolymers, propylene-butene-1 Copolymer, ethylene-vinyl acetate copolymer, 4-methylpentene-
1 polymer, ionically crosslinked olefin copolymer, and acid-modified olefin resin. In addition, homo- or co-polyesters and homo- or co-polyamides can also be used for the purpose of the present invention, as long as their heat-sealing temperature is within the above range.

The thickness of the metal foil for the laminate for the cylindrical body is 7.
Aluminum foil in the range of 30 to 30 microns, especially 9 to 15 microns, is preferably used, but steel foil, iron foil, tin foil, etc. can also be used if desired. The surface of the metal foil may be chemically treated with phosphoric acid and/or chromic acid. The metal foil for the lid may be thicker than the metal foil for the body, for example, a metal foil with a thickness of 30 to 150 microns.

If there is poor adhesion between the metal foil and the heat-sealable resin, they may be bonded together using an isocyanate adhesive, an epoxy adhesive, or an acid-modified olefin resin.

The protective resin layer that protects the outer surface of the lid may include plastic films such as biaxially oriented polyester film, biaxially oriented nylon film, biaxially oriented polypropylene film, epoxy-phenol paint, epoxy-amino paint, epoxy-
Examples include resin coatings of polyester paints such as acrylic paints.

In addition, the paper substrate is one that can provide shape retention to the cylindrical body in combination with metal foil and heat-sealable resin, and generally has a basis weight of 100.
Container base paper, such as cup base paper, is used in the range from 500 g/m ² to 500 g/m ² , especially from 200 to 350 g/m 2 .

In the present invention, the formation of the cylindrical body and the lid includes:
This can be done by any means known per se. For example, the cylindrical body can be easily formed by rolling the above-mentioned laminate 4 or 4a into a cylindrical shape and joining or butt-joining the opposite end edges, and the lid can be formed by rolling the laminate 4 or 4a into a cylindrical shape, and forming the lid by overlapping or butt-joining the laminate. 7 is punched out into a predetermined shape and press-molded into the shape shown in FIG. Of course, this lid body can also be provided with a known easy-open mechanism.

The present invention is applicable not only to the above-mentioned cylindrical body with openings at both ends, but also to sealing with a lid of a so-called cup-shaped straight or tapered container body with a bottom plate fitted in one end. It is.

Manufacture of Container In Figures 6-A to 6-C showing the manufacturing process of the sealed container of the present invention, first, the U-shaped groove 9 of the lid 3 is engaged with the open end 10 of the container body 1 (the sixth ―
Figure A). The assemblies 1 and 3 are supported on a rotationally driven support 16, and a heating mechanism 18 such as a high-frequency induction heating coil is disposed close to the engaging portion 17 between the open end 10 and the U-shaped groove 9. (6th
-Figure B). By rotating the support 16 in this state, the metal foils 5 and 6a (see FIG. 2) of the engaging portion are heated by induction, and the adjacent heat-sealable resin layers 6a, 6b, 6c (see FIG. 2) are heated by induction. ) is also heated to a heat-sealable temperature.

Next, in FIG. 6-C, the heated engaging portion 17 is forcibly engaged with the protruding roller 18 and the pressing roller 19 that are rotationally driven. On the surface of the protruded roller 18, protrusions 20 corresponding to the grooves 11 to be formed in the engaging portion 17 are formed at small intervals.
The clearance between the heat-sealable resin layer and the heat-sealable resin layer is adjusted so that it is possible to crush or eliminate foreign matter such as contents and firmly fuse the heat-sealable resin layers together at the heat-sealing interface corresponding to the protrusion 20. .

Thus, according to the present invention, it is possible to reliably form a reliable seal even under conditions where the contents adhere to the portion to be heat-sealed or where the contents rise. Heat seal seals can be formed at high speeds.

Note that the clearance between the protrusion-equipped roller 18 and the pressure roller 19 is smaller than the total thickness of each laminate existing in the engagement portion, and therefore It goes without saying that the existing heat-sealing resin may be weakly bonded between the grooves 12 or may protrude into the non-bonded portions 13.

The present invention can be modified in many ways other than those shown in the drawings, and the groove described above may be provided on the outer wall side of the U-shaped groove of the lid body, or may be provided on both the inner wall side and the outer wall side. good.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of the sealed container of the present invention, FIG. 2 is an enlarged partial sectional view of the engaging seal portion of the container of FIG. 1, and FIG. 3 is a groove in the engaging seal portion. FIG. 4 is a partially enlarged cross-sectional perspective view showing another example of the groove; FIG.
The figures are enlarged cross-sectional views showing other examples of the laminated structure and the open end structure of the container body;
FIG. B and FIG. 6-C are explanatory diagrams showing the steps of the method of the present invention. 1 is the body part, 2 is the heat seal part, 3 is the lid body, 6
a, 6b, 6c, 6d are heat-sealable resin layers,
12 is a groove, 13 is a weakly bonded or non-bonded portion, 18 is a roller with a protrusion, and 20 is a protrusion.

Claims (1)

[Scope of Claims] 1. In a sealed container formed by circumferentially thermally bonding the open end of the container body and the peripheral part of the lid that is in contact with the inner wall or outer wall of the open end, the circumferential part that is in contact with the inner wall or outer wall. A plurality of grooves are formed at small intervals around the lid portion of the lid portion so that the inner wall or the outer wall and the lid portion are strongly engaged and thermally bonded, and in any direction passing through the circumferential thermal bonding portion,
A sealed container by thermal bonding, characterized in that there are a plurality of strongly bonded parts corresponding to the grooves and weakly bonded parts or non-bonded parts corresponding to the grooves. 2. Engaging the open end of the container body with a lid having a peripheral portion that should be in contact with the inner or outer wall of the open end, so that the circumferential shape of the lid and the open end of this body-lid assembly A lid part that contacts the inner or outer wall of the body by heating a band-shaped engaging part and passing the engaging part between a plurality of rollers each having a plurality of protrusions at small intervals on at least one surface thereof. A method for producing a heat-adhesive sealed container, which comprises forming a plurality of grooves in the peripheral portion that are strongly engaged and thermally bonded, and forming weakly bonded portions or non-bonded portions corresponding to the grooves. .