JPH03214034A - Method for inspecting leakage of enclosed container made of synthetic resin - Google Patents

Abstract

PURPOSE:To inspect the minute leaking of a container by pressurizing a tightly closed container made of synthetic resin in a pressurized atmosphere, placing the container in a tightly sealed atmosphere, and detecting the change in atmospheric pressure. CONSTITUTION:In a tightly closed container 1 made of synthetic resin 1 that is an object to be inspected, a drum tube 4 and a bottom wall are formed of polypropylene resin, and a top wall 5 is formed of a laminate film. When a separating piece 11 made of polypropylene resin which is stuck to the peripheral part of the top wall 5 is pulled out, the top wall 5 is opened. When the container 1 which is filled with contents and tightly closed is compressed in a compressing atmosphere 2, air intrudes into the container through a part where leaking occurs when the container 1 leaks. The pressure in the container 1 becomes higher than atmospheric pressure. When the container 1 under this state is placed in tightly sealed atmosphere 3, the air leaks into the atmosphere 3 because the pressure in the container 1 is higher than the atmospheric pressure. Thus the atmospheric pressure becomes high. When the change in atmospheric pressure is detected with a pressure switch 9, whether the leakage occurs from the container 1 or not can be detected.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to leakage of sealed synthetic resin containers, particularly the very small gaps of about 100 μm or less that occur from the seal between the body tube and the top wall. This relates to a method for inspecting leaks from.

[Conventional technology]

Conventionally, as a leak test method for the seal between the barrel and the top wall of a sealed container, the top surface 13 of the single can container 12 is depressurized in a negative pressure atmosphere, as is done in the case of metal can containers 12. The amount of expansion of the top surface 13 due to the reduced pressure is determined by the bottom end 14 of the container.
It is detected by measuring the height from the top to the center of the top surface 13 and inspected by comparing the measured value with a reference value (see Figure 4), and the entire nine-can container 12 is placed in a constant negative pressure atmosphere. There are devices that test based on changes in pressure (see Figure 5).

In the method of measuring the height of the top surface 13, since the top surface 13 of the can container 12 in which the leak occurs swells, the presence of a leak can be detected by this. Further, in the case of pressure-based inspection, if there is a leak in the can 12, the air inside the can 12 leaks and the pressure value increases, so that the presence of a leak can be detected.

[Problem to be solved by the invention]

However, it is impossible to test for leaks in synthetic resin containers, especially trace leaks, using the conventional methods described above. This is because synthetic resin containers have lower rigidity than metal cans and are easily deformed by external pressure or heat.

In particular, the top and bottom walls are usually made thinner than the barrel in order to deform in response to changes in the internal pressure of the container, making them even more susceptible to deformation, making it particularly impossible to apply conventional methods. There is.

When inspecting synthetic resin containers for leaks using the conventional inspection method of reducing the pressure on the top of the can and measuring the height from the bottom edge of the container to the center of the top, the reduced pressure causes the top to be thinner and less rigid. The wall is greatly bulged and deformed. Therefore, the top surfaces of both the leaky container and the leak-free container bulge out to a large extent, making it impossible to obtain a difference in the amount of bulge between the two. Therefore, it is not possible to accurately determine the presence or absence of a leak in a synthetic resin container using this conventional method.

Furthermore, when testing synthetic resin containers for leaks using the conventional method of placing a container in a negative pressure atmosphere and checking for leaks based on pressure changes, the negative pressure caused the top and bottom walls in particular to swell significantly. The volume inside the container increases. This reduces the pressure of the air inside the container, and even if the container actually has a leak, the air becomes difficult to leak and the pressure value does not change, making it difficult to detect the presence or absence of a leak. Synthetic resin containers bulge and deform in slightly different ways even under the same pressure due to uneven thickness, etc., making conventional inspections based on pressure changes even more difficult.

The present invention was devised in view of these problems, and an object of the present invention is to provide a method capable of inspecting even minute leaks in sealed synthetic resin containers.

[Means to solve the problem]

As a means for this purpose, after the sealed synthetic resin container 1 is pressurized in a pressurized atmosphere 2, it is placed in a sealed atmospheric pressure atmosphere 3, and the presence or absence of leakage is inspected based on changes in the atmospheric pressure.

Further, it is preferable to press the sealed synthetic resin container 1 in a sealed atmospheric pressure atmosphere 3.

[Effect]

When a synthetic resin container 1 filled with contents and sealed is pressurized in a pressurized atmosphere 2, if there is a leak in the container 1, air will enter the container 1 from the leakage point, causing the container 1 to leak.
The pressure inside becomes higher than atmospheric pressure. Container 1 in this state
When placed in a sealed atmospheric pressure atmosphere 3, the pressure inside the container 1 is higher than atmospheric pressure, so it leaks into the atmospheric pressure atmosphere, thereby increasing the atmospheric pressure. By detecting this change in atmospheric pressure, it is possible to know whether a leak has occurred in the container 1 or not.

Furthermore, when the container 1 is pressed in the sealed atmospheric pressure atmosphere 3, the internal pressure of the container 1 is further increased, so if there is a leak in the container 1, the air inside the container 1 is more likely to leak into the atmospheric pressure atmosphere 3. As a result, changes in atmospheric pressure become more pronounced. Therefore, the presence or absence of a leak can be known more accurately.

Note that when there is no leak in the container 1, no change in atmospheric pressure occurs in the atmospheric pressure atmosphere 3 because outside air does not enter or exit the container 1.

〔Example〕

1 to 3 show two embodiments of the present invention.

The container 1 to be inspected here has a barrel 4 and a bottom wall made of polypropylene resin, and a top wall 5 made of a laminate film. A breakaway piece 11 made of polypropylene resin is attached to the peripheral end of the top wall 5, and the top wall 5 is opened by pulling out the breakaway piece 11. The container 1 is filled with high-temperature contents, sealed, and then sterilized by heating with pressurized hot liquid or steam.

In the present invention, the pressurized atmosphere 2 is formed by a closed frame 6 having a pressurizing hole 7 on the bottom surface. After the sealed synthetic resin container 1 is placed inside the sealed frame 6, the air pressure inside the sealed frame 6 is increased by feeding outside air through the pressurizing hole 7. Although this external air pressure is not limited, good results were obtained in an experiment when a pressure of 4 kg/cffl was applied for 30 seconds (see Fig. 1).

The container 1 pressurized in the pressurized atmosphere 2 is first placed in a sealed atmospheric pressure atmosphere 3. In this embodiment, this atmospheric pressure atmosphere 3 is formed by a sealed box body 8, and this sealed box A pressure switch 9 is connected to the upper surface of the body 8. This pressure switch 9 is activated when the pressure inside the sealed box body 8 increases and exceeds a set pressure value. By operating this pressure switch 9, it is possible to know whether or not a leak has occurred in the container 1. In addition to the pressure switch 9, a pressure gauge or the like may be used as a means for detecting this pressure change.

Existing common instruments and devices that respond to pressure changes can be used (see Figure 2).

In order to more accurately determine the presence or absence of a leak, it is preferable to press the container 1 in the atmospheric pressure atmosphere 3; however, in this embodiment, a pair of press rods 10 are installed movably back and forth from opposite side walls of the sealed box body 8. , the container barrel 4 is pressed by this pressing rod 10 (see FIG. 3).

〔Effect of the invention〕

As described above, the present invention provides a method for pressurizing a sealed synthetic resin container in a pressurized atmosphere, and then placing it in a sealed atmospheric pressure atmosphere.
The presence or absence of leaks is tested based on changes in atmospheric pressure, and unlike conventional leak testing methods for cans and containers, it is possible to accurately test even the slightest leak that occurs from a gap of 100 μm or less in a synthetic resin container. It is possible.

In addition, by pressing the container in a sealed atmospheric pressure atmosphere, it is possible to make it easier for the air inside the container to leak out, which makes it possible to perform more accurate inspections. It has excellent effects.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. 2 is a sectional view showing the container placed in a pressurized atmosphere, and FIG. 2 is a sectional view showing the container placed in an atmospheric pressure atmosphere. 31st! l
is a cross-sectional view showing a state in which the container is pressed in an atmospheric pressure atmosphere,
FIGS. 4 and 5 are cross-sectional views showing the conventional method. Explanation of symbols 1: Sealed synthetic resin container, 2: Pressurized atmosphere. 3: Atmospheric pressure atmosphere, 4: Trunk cylinder, 5: Ceiling wall. 6 sealed frames, 7: pressure holes, 8: sealed box. 9: Pressure switch, 10: Press rod, 11 detachable pieces. 12: Can container 1 13: Top surface, 14: Bottom end. -Meji 7 / 9-Scene n Sweet I now 1 o-Press rod 11-・-rga#11 company date force

Claims (2)

[Claims] (1) After pressurizing the sealed synthetic resin container (1) in a pressurized atmosphere (2), place it in a sealed atmospheric pressure atmosphere (3) and check for leaks based on changes in atmospheric pressure. A leak testing method for sealed synthetic resin containers. (2) The method for inspecting leaks in a sealed synthetic resin container according to claim 1, wherein the sealed synthetic resin container (1) is pressed in a sealed atmospheric pressure atmosphere (3).