JP2539072B2 - Plastic container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plastic container which can be retort processed and whose contents can be stored for a long period of time.

“Prior Art” Metal cans have been widely used as containers for long-term storage of foods and the like. However, the metal can has a problem that it requires a force when opened and there is a risk of cutting a finger.

The present inventors have proposed an easily openable plastic container that can solve the above-mentioned problems and is also excellent in terms of design freedom (for example, JP-A-61-203335 and JP-A-2).
-109844).

As shown in FIG. 9, this easily openable sealed container is composed of a container body 1 and a lid 2. The container body 1 is formed by laminating a gas barrier material 4 on the inner surface of a thermoplastic resin outer layer portion 3 having rigidity. Further, a flange portion 13 extending outward is formed at an end portion on the opening side of the container body 1. The gas barrier material 4 is laminated from the inner peripheral surface 1a of the container body 1 to the upper surface 13a of the flange 13. As shown in FIG. 10, the gas barrier material 4 is formed by laminating thermoplastic resin 6, 6 made of an unstretched polypropylene film on both sides of an aluminum foil 5 having a gas barrier property.

The lid 2 is formed by laminating a gas barrier material 8 having a gas barrier property on the inner surface of an outer layer portion 7 made of a thermoplastic resin. As the gas barrier material 8, the same material as the gas barrier material 4 of the container body 1 is used. The lid 2 is formed of a central portion 2a that is dropped into the opening of the container body 1 and a flange portion 2b that fits into the opening-side end of the container body 1. The flange portion 2b is formed in a U-shaped cross section so as to wrap the flange portion 13 of the container body 1 in close contact with the flange portion 2b, and the outer peripheral portion serves as the escape prevention portion 2c. A weakening line 9 exposing the gas barrier material 8 is formed at a position along the outer peripheral edge of the central portion 2a of the lid 2.

In order to close the container body 1 of this easily openable sealed container with the lid 2, the flange portion 2b of the lid 2 is fitted to the flange portion 13 of the container body 1 after filling the contents, and this is then subjected to high-frequency welding using a high-frequency welding device. It is sandwiched between the oscillation coil 15 and the push-up plate 16 and welded at high frequency. At this time, the container body 1 is deformed so that the opening portion expands in diameter, but in this container, the escape prevention portion 2c of the flange portion 2b of the lid 2 is brought into contact with the outer peripheral surface 13c of the collar portion 13 to prevent the opening portion from expanding in diameter. To be done.

FIG. 11 is an enlarged view of the actual welded portion of the welded portion between the container body 1 and the lid 2 of this container.
The gas barrier material 4 and the thermoplastic resin layers 6 of the gas barrier material 8 of the lid 2 are linearly pressed and fused along the inner peripheral edge 13b of the flange 13 of the container body 1. As a result, the container body 1 is sealed by the lid 2.

[Problems to be Solved by the Invention] The conventional plastic container has a problem to be solved in that if the content is viscous, defective sealing is likely to occur.

That is, when a part of the content adheres to the upper surface 13a of the collar portion 13 of the container body 1 when the container body 1 is filled with the content, the content is viscous even if it is removed by an end surface cleaner or the like. If it is one, it cannot be completely removed. When the lid 2 is attached to the container body 1 and sealed in such a state, the container body 1 and the lid 2 cannot be brought into close contact with each other in the portion where the residual contents are present, resulting in poor sealing. As a result, the contents are corrupted.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plastic container capable of reliably sealing even if the content is viscous.

"Means for Solving the Problem" In the present invention, a chamfered portion is formed on the outer peripheral edge of the flange portion of the container body, and when the flange portion and the flange portion of the lid are fused, the chamfered portion is extruded from this portion. The molten polypropylene is flown into the outer peripheral side of the collar portion and the inner peripheral surface of the collar portion to form a resin pool seal portion in these portions.

Further, when the flange portion of the container body is wide, the outer peripheral portion of the flange portion is bent by the extruded molten polypropylene without forming the above-mentioned chamfered portion, thereby forming a similar resin pool seal portion. To be done. At this time, the outer peripheral portion of the wide brim portion may be pressed and heated while avoiding the application of force.

"Action" Contaminants that intervene when the molten polypropylene is extruded ride on this flow and are removed from the fused portion.

Further, the flange portion and the flange portion are bonded with polypropylene having a high melting point and high strength, and moreover, the two resin reservoir seal portions are bonded together, so that the adhesive strength between the flange portion and the flange portion is increased. Even if a large external force is applied, the container body and the lid will not be separated.

[Examples] Hereinafter, the plastic container of the present invention will be described in detail with reference to the drawings. The same components as those of the conventional example are designated by the same reference numerals to simplify the description.

(Example 1) FIG. 1 and FIG. 2 show a first example of the plastic container of the present invention.

This plastic container is composed of a cup-shaped container body 20 and a lid 2 having a flange portion 2b. On the inner surface side of the container body 20 and the lid 2, gas barrier materials 4, 8
Are stacked. The gas barrier materials 4 and 8 are made by laminating and integrating layers 6 and 6 made of polypropylene on both surfaces of the aluminum foil 5 as in the conventional case.

A flange portion 23, which bulges slightly outward, is formed at the opening side end of the container body 20 of this plastic container. The chamfered portion 31 that is obliquely cut is provided on the outer peripheral edge portion of the collar portion 23.
The container body 20 is formed by the chamfered portion 31.
When the lid 2 and the lid 2 are combined, a resin escape space 32 is formed between the flange portion 23 of the container body 20 and the flange portion 2b of the lid 2.

In this plastic container, the portion between the inner peripheral edge 23b of the upper surface 23a of the collar portion 23 of the container body 20 and the resin escape space 32 is the lid 2.
It was fused with the flange portion 2b in a pressure contact state, and this portion was the pressure contact fusion portion 33. In addition, the inner peripheral surface 23c of the collar portion 23
In the resin escape space 32, the container main body 20 is formed by the molten polypropylene extruded when the pressure welding portion 33 is formed.
A resin pool seal portion 34, 35 made of polypropylene, to which the lid 2 is adhered, is formed.

Next, this plastic will be specifically described by its sealing method.

In this container sealing method, the container body 20 filled with the contents is first covered with the lid 2, and the flange portion 23 of the container body 20 and the flange portion 2b of the lid 2 are fitted together. Next, this assembly is used as a flat-plate high-frequency oscillation coil 15 and a push-up plate for the high-frequency welding device.
It is sandwiched between 16 and pressurized while applying high frequency. Then, the polypropylene layers 6 and 6 of the gas barrier materials 4 and 8 are heated and melted at the upper surface 23a of the flange portion 23 of the container body 20 and the flange portion 2b of the lid 2. Further, a portion between the inner peripheral edge 23b of the collar portion 23 and the chamfered portion 31 is pressed against the flange portion 2b of the lid 2. When the container main body 20 and the lid 2 are pressed against each other in this manner, a force for expanding the opening portion acts on the container main body 20, but the deformation of the opening portion is caused by the escape prevention portion 2c provided on the flange portion 2b of the lid 2. Collar 23 of container body 20
The outer peripheral surface 23d is prevented from contacting.

This high-frequency welding process is performed until the thickness of the polypropylene layers 6, 6 of the gas barrier materials 4, 8 becomes about 1/2 or less of the thickness before fusion at the pressure welding portion 33. During this treatment, the polypropylene layers 6, 6 are melted and the polypropylene is extruded from the pressed portion,
The resin escape space 32 formed by the chamfered portion 31 and the inner peripheral surface 23c of the collar portion 23 of the container body 20 flow.

After this, when heating with high frequency is stopped and the molten polypropylene is cooled, the upper surface 23 of the container body 20 is brought into contact with the pressure contact portion.
A pressure welding portion 33 is formed in which a and the flange portion 2b of the lid 2 are pressure welded with a predetermined width over the entire circumference. Further, resin pool seals 34 and 35 made of polypropylene are adhered to the container body 20 and the lid 2 by molten polypropylene extruded on the inner peripheral side and the outer peripheral side of the pressure welding portion 33.

In the plastic container of this embodiment, the container body
The polypropylene layers 6 and 6 existing on the upper surface 23a of the collar portion 23 of 20 and the flange portion 2b of the lid 2 are applied with a predetermined width over the entire circumference to extrude the melted polypropylene to the inner peripheral side and the outer peripheral side, Since the container body 20 and the lid 2 are integrated,
The collar portion 23 of the container body 20 when the container body 20 is filled with contents.
Even if the viscous content remains on the upper surface 23a of the above, the residual content rides on the flow of the molten polypropylene at the time of high frequency welding and is removed to the inner peripheral side or the outer peripheral side of the pressure welding portion 33.
As a result, the pressure welding portion 33 can be welded without the contents remaining.

The present inventors consider this phenomenon as follows. That is, when the polypropylene layers 6 and 6 of the gas barrier materials 4 and 8 are melted and pressure is applied at the portion where the upper surface 23a of the container body 20 and the flange portion 2b of the lid 2 are in contact, the melted polypropylene is in contact with the interface. The part is pushed farther inward or outward. Therefore, the contents remaining at the interface portion are smoothly pushed inward or outward along the flow of polypropylene. Then, a new interface of polypropylene is gradually formed at the portion where the upper surface 23a of the container body 20 and the flange portion 2b of the lid 2 are pressed against each other.

Therefore, the container body 20 and the lid 2 can be surely brought into close contact with each other over the entire circumference, and the reliability of the seal of the plastic container can be improved.

Further, polypropylene extruded from the pressure welding portion 33 forms resin pool seal portions 34 and 35 made of polypropylene inside and outside the pressure welding portion 33, and the container body 20 and the lid 2 are integrated in this portion as well. Therefore, the container body 20
The adhesive strength between the lid and the lid 2 increases, and the sealing performance of the container can be improved in this respect as well.

Further, since pressure is applied to a portion having a predetermined width outward from the inner peripheral edge 23b of the collar portion 23 of the container body 20, one of the polypropylene melted during high frequency welding has moved to the collar portion of the container body 20. The inner peripheral surface 23c of 23 is extruded. Therefore, it is possible to prevent the lid 2 from being pushed upward by the resin pool seal portion 34 on the inner side formed of the extruded polypropylene. Therefore, according to this sealing method, the container body 20 and the lid 2 can be more reliably sealed.

In the plastic container of this embodiment, the container body 20
Since the chamfered portion 31 is formed on the outer peripheral edge portion of the collar portion 23 and the resin escape space 32 is provided between the upper surface 23a of the container body 20 and the flange portion 2b of the lid 2, the collar portion 23 of the container body 20 is formed. Even if is surrounded by the flange portion 2b of the lid 2 having a U-shaped cross section, the outward flow of the melted polypropylene is not hindered. Therefore, in this plastic container, the contents remaining on the upper surface 23a of the container body 20 are pressure welded to each other at the time of high frequency welding.
It can be smoothly removed from the outside, and highly reliable sealing can be performed.

(Example 2) FIGS. 3 and 4 show a second example of the present invention. In this example, the container main body 50 is different from the container main body 20 illustrated in the first embodiment, and the collar portion 53 is provided. Is widely formed,
Correspondingly, the width of the flange portion 2b is also widened.

When sealing the container body 50 with the lid 51,
In the usual method, it has been necessary to dispose the push-up plate 16 under the collar portion 53 in order to perform uniform pressurization. In this embodiment, after the flange portion 53 of the container body 50 and the flange portion 52 of the lid 51 are overlapped with each other, the flange portion is formed by applying pressure from the container body bottom portion with the high frequency oscillation coil 15 and the push-up plate 16 of the high frequency welding device.
The inner peripheral portion of the flange portion 53 and the flange portion 52 were pressed in a state where force was not applied to the outer peripheral portion of 53. As a result, Tsubabe
The polypropylene between the barrier materials 4 and 8 in the inner part of 53 was extruded inward and outward. Then, the polypropylene extruded outward displaces the outer peripheral portion of the unpressed collar portion 53 downward, and accumulates in this portion.

Then, after this, when the molten polypropylene was cooled, the collar portion 53 of the container body 50 was attached to the inner peripheral portion of the pressed collar portion 53.
The upper surface 53a and the flange portion 52 of the lid 51 are welded to form a pressure welding portion 33, and the container body 50 and the lid 51 are bonded together by polypropylene extruded in and out of the pressure welding portion 33 from polypropylene. The resin pool seal portions 34 and 35 were formed.

In this case, the wide collar portion 53 provided on the container body 50
Since high frequency welding is performed in a state in which the pressing force is not applied to the outer peripheral portion of the, the melted polypropylene displaces the outer peripheral portion of the collar portion 53 downward and flows into it. Therefore, as in the case of the first embodiment, the melted polypropylene can be smoothly pushed outward, and the residual contents can be smoothly removed from the pressure welding portion 33 during the high frequency welding.

When the push-up plate is placed under the flange as in the conventional method that has been conventionally performed, the pressure is evenly applied, so there is almost no discharge of resin from the press-welding section, and therefore the resin pool 3
4,35 does not occur.

Example 3 FIG. 5 shows a plastic container of Example 3.

This plastic container differs from that of the first embodiment in that the gas barrier material 4 is not laminated on the container body 20, and the plastic outer layer portion 3 of the container body 20 is directly attached by the polypropylene of the gas barrier material 8 of the lid 2. It is the point that is welded.

Even in such a plastic container, a highly airtight seal can be provided as in the first embodiment.

"Example" (Example 1) The plastic container of Example 1 was prototyped and subjected to a pressure leak test. For comparison, the same test was performed on the conventional plastic container shown in FIG.

 The test method is as follows.

First, as shown in FIG. 6, attach an air gun to the lid 2 of the container.
Insert 60 nozzles, and then as shown in FIG. 7, blow air into the water tank to pressurize. The pressure at the time of air leakage was defined as the internal pressure resistance strength.

As a result of this test, the example 1 showed an internal pressure resistance strength of 2.3 kg, while the conventional example showed an internal pressure resistance strength of 1.7 kg.

(Example 2) Next, the lid 2 with the crab meat (having a diameter of 0.3 mm and a linear shape) placed on the upper surface 23a of the collar portion 23 of the container body 20 of Example 1
Was sealed and subjected to a penetrant (red check) test.
For comparison, the same test was performed on a conventional plastic container.

 The test method of the penetrant test is as follows.

First, the bottom of the container is sliced with a cutter as shown in FIG. 8, and then the contents and the like are removed from the container and washed.
Then, after making sure that there is no water inside the container,
The penetrant is sprayed from the inside to the portion where the lid 2 and the lid 2 are in contact with each other. In this state, it is left for 1 hour or more, and then dried in a dryer for 4 hours or more. After confirming that the penetrant has dried,
The part of the crab meat sandwiched is cut out with a cutter, and enlarged and observed. After conducting a 100-can test, the number of permeated liquids that had permeated the pressure welding portion 33 was defined as the number of leaks.

As a result, the number of leaks generated in Example 1 was 0, whereas in the conventional example, the crab meat remained in the pressure welding portion, and the number of leaks was 45 cans.

From these results of Examples 1 and 2, it was confirmed that the seal of Example 1 had high reliability.

(Embodiment 3) With respect to the plastic container of Embodiment 3 shown in FIG. 5 in which the gas barrier material 4 was not laminated on the inner peripheral surface of the container body 50, the internal pressure resistance was examined. For comparison, the same applies to a conventional container using a container body in which the gas barrier material is not laminated (the conventional container shown in FIG. 9 in which the gas barrier material 4 is not laminated in the container body 1). The internal pressure resistance strength was examined.

As a result, the internal pressure resistance of the container of Comparative Example was 1.1 kg. On the other hand, the product of Example 3 exhibited an internal pressure resistance strength of 1.6 kg. From the results of this test, according to the sealing method of the present invention, even when the gas barrier material 4 is not laminated,
It was confirmed that the container body 20 and the lid 2 could be firmly welded together.

[Advantages of the Invention] As described above, according to the present invention, the resin reservoir seal portion made of polypropylene is formed on the outer peripheral portion and the inner peripheral surface of the collar portion, and the flange portion and the flange portion are pressure welded to each other. The molten polypropylene is extruded from the attachment part to the outer peripheral side and the inner peripheral side of the collar part, and the foreign matter adhering to the upper surface of the collar part is swept away by the extruding flow of this molten polypropylene and is eliminated, and the seal at this part is completely You can do it.

Further, since the flange portion and the flange portion are in a state of being fused and fused with polypropylene having a high melting point and high rigidity, the adhesive strength of this portion is increased and the sealing property between the container body and the lid is extremely good.

Also, if the flange is wide, even if the chamfer of the flange is not formed, the extruded molten polypropylene causes the outer peripheral portion of the flange to bend and the molten polypropylene to flow. Excluded from the department.

Furthermore, a resin pool seal portion made of polypropylene is formed on the inside and the outside of this pressure welding portion, and the container body and the lid are adhered to each other also in this portion, so that the joint strength between the container body and the lid is increased, The sealing performance of is improved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a portion A in FIG. 2, FIG. 2 is a sectional view showing a plastic container of Example 1, and FIG. 3 is a state before sealing the plastic container of Example 2. Sectional drawing shown in FIG. 4, FIG. 4 is a sectional view showing a plastic container of Example 2, FIG. 5 is a sectional view showing a plastic container of Example 3, and FIGS. 6 and 7 explain a pressure leak test method. FIG. 8 is a schematic diagram for explaining the method of the penetrant test, FIG. 9 is a sectional view showing a conventional plastic container, FIG. 10 is a sectional view showing a gas barrier material, and FIG.
FIG. 11 is a cross-sectional view showing an enlarged part B in FIG. 2 ... Lid, 2b ... Flange part, 20 ... Container body, 23 ...
Collar part, 23a …… upper surface, 23b …… inner peripheral edge, 23c …… inner peripheral surface, 3
1 …… Chamfer, 32 …… Resin escape space, 33 …… Pressure welding section, 34,35 …… Resin pool seal section, 50 …… Container body, 5
1 …… Lid, 52 …… Flange part, 53 …… Collar part, 53a …… Top surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 62-28355 (JP, A) JP 62-260684 (JP, A) Actual 57-167058 (JP, U)

Claims (2)

(57) [Claims] 1. A cup-shaped container body having a flange portion formed at an end portion on the opening side, and a flange portion having a U-shaped cross section that abuts on an outer peripheral surface, an upper surface and an inner peripheral surface of the collar portion of the container main body. It further comprises a lid having a weakening line formed on the outer peripheral edge of its central portion, and the container body and the lid are integrated by pressure welding the flange portion of the container body and the flange portion of the lid, A plastic container for cutting and opening the weakening line of the lid, wherein a chamfered portion is formed on the outer peripheral edge of the flange portion of the container body, and polypropylene is provided on the outer peripheral side between the flange portion and the flange portion of the lid. A plastic container sealing portion is formed, and a plastic container sealing portion made of polypropylene is further formed on the inner peripheral surface of the collar portion. 2. A cup-shaped container body having an opening-side end portion formed with a wide brim portion extending outwardly, and an outer peripheral surface, an upper surface and an inner peripheral surface of the wide brim portion of the container body. A container having a flange portion having a U-shaped cross section and further having a weakening line formed on the outer peripheral edge of the central portion thereof, and the container is formed by pressure welding the wide flange portion of the container body and the flange portion of the lid. A plastic container in which a main body and a lid are integrated and is opened by cutting the weakening line of the lid, wherein a resin pool made of polypropylene is provided on the outer peripheral portion of the wide collar portion and the inner peripheral surface of the wide collar portion of the container body. A plastic container having a seal portion.