JPH0422793B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an easily openable sealed container.
More specifically, it has a significantly high pressure-resistant sealing force when opened from the inside of the container, and when opened from one end of the cap, it can be opened easily with finger force, and it is difficult to reseal. Therefore, the present invention relates to a hermetically sealed container that has the function of ensuring that the container has not been opened and assuring the quality of the contents.

(Prior Art) Conventionally, a container called an easy-to-open container is known in which a peelable lid (an easily peelable lid) is heat-sealed to the opening of the container. This container has a protective resin coating layer on the outer surface of metal foil such as aluminum foil, and the seal strength between the mouth and lid is adjusted to a range of 0.05 to 2 kg/15 mm width, which is called peelable adhesive. It is.

(Problems to be Solved by the Invention) However, the above-mentioned peelable lid has flexibility and the mechanical strength of the lid material itself is not sufficient.
If you want to protect it from destructive forces from the outside, you have to cover it with a separate outer cover, which is a hassle.

In addition, the seal strength between the container mouth and the lid changes depending on the heat sealing temperature, and when heat sterilizing the contents, this heat sterilization also changes the seal strength.
There is a problem in that it is difficult to obtain a seal with a constant sealing strength (opening force).

In particular, for rigid containers such as bottles and metal containers, mechanical strength is often required for the lid as well, and even compared to the containers described above, it is difficult to obtain the desired heat seal strength for sealing as is. That's difficult.

In addition, when performing retort sterilization of the contents of a heat-sealed package, 2.3Kg/15mm from the inside
Peelable lids that meet these requirements are required to have a seal strength (peel strength) greater than the width, but peelable lids that can be opened by breaking the heat-sealed part are still not in practical use. has not yet been reached.

Therefore, a container made of glass or glass that has a rigid shell and has a cap applied to the opening of the container so that it can be sealed by heat sealing and can be easily opened with fingers. Metal containers are highly desired in the industry.

Therefore, an object of the present invention is to provide a sealed container whose opening is heat-sealed with a cap having a laminate having a heat-sealing function bonded to the inner surface of a rigid shell, and which is capable of being opened from the inside of the container. It has an extremely high pressure-resistant sealing force against the cap, and can be easily opened from one end of the cap using finger force.Furthermore, since it is difficult to reseal, it is an easy-open seal that also has the function of guaranteeing the quality of the contents. An object of the present invention is to provide a container made of glass or metal that has good safety and sealing properties.

(Means for Solving the Problems) According to the present invention, an outer layer of propylene resin, a metal foil, an inner layer of propylene resin, a blend layer of a propylene homopolymer and a propylene copolymer, and a heat seal layer of a propylene copolymer are used. A cap with a laminate bonded to the inner surface in preparation for this order and in which the thickness of each layer is in the order of inner layer > blend layer > heat seal layer, and a plastic cap whose at least the heat seal surface is made of propylene resin. There is provided an easily openable sealed container characterized in that the container is sealed by heat sealing with a glass or metal container having a ring-shaped inner stopper fitted into the mouth.

In the container of the present invention, the ring-shaped inner stopper is
Preferably, the cap has a circumferential protrusion of small width on its upper surface, and heat sealing is performed between the protrusion and the heat-sealing layer of the cap.

(Function) In FIG. 1 showing an example of an easily openable sealed container of the present invention, a container (glass container or metal container) B has a cylindrical body 1, a bottom 2 at the lower end, and a neck 3 at the upper end. have. An inner plug A is fitted into the upper opening end 4 of the neck portion 3 (see Fig. 2), and a cap C is placed over the inner plug A and heat-sealed.
There is.

In FIG. 2, which shows an enlarged view of the cap C, the inner stopper A, and the container opening, a jaw 5 for engaging the inner stopper is formed on the outer periphery of the container opening. The inner stopper A has an inverted U-shaped cross section, consisting of an inner circumferential portion 10 that engages with the inner circumferential surface of the container mouth, an outer circumferential portion 11 that engages with the outer circumferential surface of the container mouth, and an upper surface portion 12 that connects the two. It is made of an annular member, and the upper surface of the upper surface part 12 has a small-width circumferential protrusion 13 for heat sealing, and the lower surface thereof has a circumferential protrusion 14 for sealing with the container mouth. . Furthermore, an inward engagement projection 15 is formed at the lower end of the outer peripheral portion 11 . By fitting the inner stopper A into the container mouth and engaging the engaging protrusion 15 with the jaw 5 of the container mouth, the sealing circumferential protrusion 14 is pressed against the upper end of the container mouth to seal the container. It will be done.

At least the heat-sealing surface of the inner stopper A, preferably the entirety thereof, is formed of propylene-based resin.

The cap C has a rigid shell 20, and the shell 20 has a top plate portion 21, a peripheral portion 22, and an opening flange or tab 23 provided on at least a portion of the peripheral portion. (Figure 2 is an example of a flange). A laminate 24 is bonded to the inner surface of the top plate 21 of the shell 20.

As shown in FIG. 3, this laminate 24 includes, from the shell side to the container side, an outer layer 25 of propylene resin, a metal foil 26, and an inner layer 2 of propylene resin.
7. It is important to include a blend layer 28 of propylene homopolymer and propylene copolymer and a heat seal layer 29 of propylene copolymer, and the thickness of each layer is in the order of inner layer 27 ≧ blend layer 28 > heat seal layer 29 It is.

The reason why the blend layer 28 of propylene homopolymer and propylene copolymer is provided is that this part has a structure weakened by the blend.
This is to cause cohesive failure to occur selectively in this portion.

The reason why the heat sealing layer 29 of propylene copolymer is provided to this blend layer 28 is to obtain a heat seal with the ring-shaped inner stopper provided at the open end 4 of the container B, and also. By using a propylene copolymer, heat sealing can be reliably performed even at relatively low heat sealing temperatures. Moreover, since the thickness of the heat seal layer 29 is made thinner than that of the blend layer 28, the heat seal layer 29 is easily broken in response to a peeling force (moment) from one end of the cap.

Note that the inner layer 27 of propylene resin located on the blend layer 28 prevents cohesive failure of the blend layer 28 from spreading to other parts of the laminate 24.

The laminated body 24 is connected to the cap C via the outer layer 25.
It is joined to the inner surface side of the top plate part 21 of the shell body 20, and is joined to the ring-shaped inner stopper A provided at the open end of the container via a heat-sealing layer 29 of propylene copolymer.

When opening the sealed container of the present invention, an extremely large opening force of 10 kg or more is required to pull the cap uniformly around the entire circumference and open the cap. In this way, an extremely high pressure-resistant sealing force can be obtained against opening from the inside of the container.

On the other hand, as shown in FIG. 2 (enlarged view), place your finger on the opening flange 23 of the cap,
When the cap is pushed upward, the applied moment causes the heat seal layer 29 on the opening start side to break first from the container side to the shell side, then causes cohesive failure of the blend layer 28, and finally causes the heat seal layer 29 to break again. A break occurs from the shell side toward the container side. Since the cap shell 20 is made of a rigid material, the heat-sealed portion breaks down substantially all at once over the entire circumference of the sealing mouth. Further, since the heat-sealed portion is destroyed in the above-mentioned order, an advantage is achieved in that the cap can be opened easily with fingers.

By providing a circumferential protrusion 13 with a small width on the upper surface of the inner plug A and heat sealing between it and the heat sealing layer 29, the cohesive failure width of the blend layer 28 can be made relatively small. It is possible to easily open the package and prevent feathering from occurring when the package is opened.

Furthermore, the inner diameter of the peripheral portion 22 of the shell 20 of the cap C is made larger than the outer diameter of the mouth of the container (the mouth of the container provided with the ring-shaped inner stopper).
Since this cap C cannot be resealed after being opened, the fact that it has been opened becomes obvious.
A guarantee function will be provided to determine whether or not the contents have been touched.

(Preferred Embodiment of the Invention) In the present invention, as long as the shell 20 of the cap C is made of a rigid material, rigid resin such as polypropylene or polyethylene, ceramic,
It can be made of any material such as metal. Here, the rigidity of the cap refers to a property that allows the cap to be lifted all at once without being substantially bent when the cap is opened. In terms of heat sealability,
The shell is made of isotactic polypropylene.
It is preferably made of synthetic resin such as high-density polyethylene or propylene-ethylene copolymer.

The shell of the cap can be formed by injection molding or press molding. The thickness of the top plate is generally 0.5 to
The diameter is preferably in the range of 3.0 mm, and the diameter is between 10 and 200 mm.
A range of mm is desirable from the viewpoint of ease of opening. Also, the height of the peripheral part of the cap shell varies depending on the diameter of the top plate, but is 0.1 to 0.3 of the diameter of the top plate.
It is desirable to have double the height.

As the heat seal layer of the laminate, propylene-ethylene copolymer, acid-modified propylene resin, etc. can be used. The heat-sealing layer should have a thickness as thin as possible in order to perform the above-mentioned function of opening, and preferably has a thickness of generally 2 to 30 μm, particularly 3 to 10 μm. The base material of the laminate consists of an inner layer of propylene resin. The inner layer adheres the blend layer and facilitates the breakage of the heat seal layer from the outside of the shell to the container side when the package is opened.If the adhesion of the blend layer to the base material is insufficient, after opening The heat-sealing layer remains in the form of a film at the container opening (ring-shaped inner stopper). The thickness of the inner layer is generally 10 to
Preferably it is 80 μm, particularly in the range of 15 to 50 μm.

The metal foil acts as a heating element by high-frequency induction heating during heat sealing, and the cap provides barrier properties against gases, scents, and the like. Metal foils include aluminum foil, steel plate, iron foil,
Tin foil, etc. is used, and its thickness is 5 to 50 μm.
In particular, it is desirable that the thickness be in the range of 7 to 30 μm.

The outer layer is for bonding the laminate to the shell, and can be bonded by thermal bonding, urethane adhesive, or epoxy adhesive. The blend layer used in the present invention is made of a blend of propylene homopolymer and propylene copolymer, and by using this blend, the resin layer itself becomes weaker than when using a single resin, making it difficult to peel off. Cohesive failure becomes easy to occur.

The blend ratio of the propylene copolymer P _C and the propylene homopolymer P _H is desirably P _C :P _H =20:80 to 60:40, particularly 30:70 to 45:55.

The thickness of the blend layer should generally be in the range 5 to 40 μm, especially 10 to 20 μm.

The thickness ratio of the inner layer C ₁ :blended layer C ₂ :heat seal layer C ₃ is approximately (2-20):1.2-3):1 to give the most desirable results. In addition, the seal strength P of each layer is determined by the formula P _C1-C2 ＞P _C2-C3 ……(1) P _C3-C4 ＞P _C2-C3 ……(2) P _C1-C2 ≧P _C3-C4 ……(3 ) In the formula, P _C1-C2 represents the seal strength between the C ₁ and C ₂ layers, and the same applies hereafter, and P _C3-C4 represents the seal strength between the C ₃ layer and the mouth of the container.
It is desirable that the strength T of each layer satisfies the following expressions: T _C3 < T _C1 ( ₄ ) T _C2 < T _C1 (5).

To seal a container with a cap, the laminated body is punched into a disc shape, this is fitted into the shell of the cap, this assembly is placed over the container mouth, and the state is pressed against the container mouth with a constant pressing force. This is done by high frequency induction heating. The appropriate pressing force is generally in the range of 0.5 to 2 kg, and heat sealing is performed at a temperature above the melting point or softening point of the resin.

The ring-shaped inner stopper fitted into the container opening is preferably made of a rigid material, and synthetic resin such as polypropylene or polyethylene is preferable from the viewpoint of moldability and heat sealability. It is more preferable to be present.

The ring-shaped inner plug can be molded by injection molding or the like.

Small width circumferential protrusions are 0.3 to 3 mm, especially 0.5
It is preferable to provide a width of 1.5 mm to 1.5 mm.

(Effects of the Invention) The easy-to-open container according to the present invention has a rigid outer shell and a cap with a heat-sealing function that is tightly attached to the inside of the outer shell, which is heat-sealed to the opening of the container. It has a significantly high pressure-resistant sealing force against opening, and since it can be easily opened using finger force from one end of the cap, and is difficult to reseal, it also has a quality assurance function for the contents. This advantage is achieved.

This sealed container is useful as a container for soft drinks, alcoholic drinks, milk drinks, fruit juice containers, infusion containers, and the like.

[Brief explanation of drawings]

FIG. 1 is a plan view of the present invention, FIG. 2 is a sectional view of the main part of FIG. 1, and FIG. 3 is an enlarged view of the main part of FIG. 2.
FIG. 4 is an enlarged view of the main parts of the cap shown in FIG. 3 in an unsealed state. A...Inner stopper, B...Container, C...Cap, 4
... upper opening end, 13 ... circumferential container part for heat sealing, 20 ... rigid shell, 23 ... flange or tab for opening, 24 ... laminate, 25 ... outer layer of propylene resin, 26...metal foil, 27...
... Inner layer of propylene resin, 28 ... Blend layer with propylene homopolymer, 29 ... Heat seal layer of propylene copolymer.

Claims (1)

[Scope of Claims] 1. An outer layer of propylene resin, a metal foil, an inner layer of propylene resin, a blend layer of propylene homopolymer and propylene copolymer, and a heat seal layer of propylene copolymer are provided in this order, and the thickness of each layer is , a cap in which a laminate in the order of inner layer > blend layer > heat seal layer is bonded to the inner surface, and a plastic ring-shaped inner stopper whose at least heat seal surface is made of propylene resin forms a mouth portion. An easy-to-open sealed container characterized by being formed by heat-sealing a glass or metal container fitted into the container. 2. Claim 1, wherein the ring-shaped inner plug has a circumferential protrusion with a small width on its upper surface, and heat sealing is performed between the protrusion and the heat-sealing layer of the cap. container.