JPH02656B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for detecting liquid leakage in a sealed liquid container for hot filling, and in particular, by the depressurization phenomenon that occurs inside the container after cooling after hot filling. The object is a container in which the variable bottom that constitutes the container deforms toward the inside of the container, and if there is a cause of leakage such as a pinhole in this container, the variable bottom will not cause the specified deformation.
It is intended to detect liquid leakage or air leakage by detecting the presence or absence of deformation. [Prior Art] One method for long-term preservation of drinking liquids is to sterilize the liquid at high temperatures, and then fill and seal the liquid in containers. Such a method is generally referred to as "hot filling," and the present invention is a method for detecting leakage in containers used for hot filling, and is based on a detection method previously proposed by the present inventor (Japanese Patent Application No. 58-97986 (Japanese Unexamined Patent Publication No. 59-224536))
However, with further improvements, even if the liquid level fluctuates during detection, regardless of whether or not there is a fluctuation,
This makes it possible to reliably detect liquid leaks. That is, in the prior invention, in the above-mentioned sealed liquid container for hot filling, liquid leakage is detected by a change in the height of the liquid level in the container after filling the liquid. However, as the container is transferred, the liquid surface may ripple or slope for some other reason, so in that case, even if the container actually leaks, , there is a risk that it will be determined that there is no liquid leakage, making it difficult to detect with high accuracy. Furthermore, the detection accuracy may be affected by variations in the amount of liquid filled into the container. The present invention has developed a novel detection method that does not suffer from the above-mentioned difficulties. [Object of the invention] The present invention aims to provide a method that can reliably detect liquid leakage in a liquid-tight container with a variable bottom. It is intended to be able to detect liquid leaks with high accuracy even if there are variations in the amount, without being affected by these variations. [Structure of the Invention] The present invention utilizes the fact that the variable bottom of a sealed liquid container for hot filling, which is equipped with a variable bottom, does not deform when there is liquid leakage, to determine whether or not the variable bottom is deformed. The presence or absence of liquid leakage and air leakage can be easily and reliably detected by determining the amount of transmission of light beams or X-rays irradiated from the side in a substantially diametrical direction. [Example] An example of a liquid-tight container used in the present invention is shown in FIG.
For a container body of 54 mm and height 130 mm, as an example, paper 11a with a thickness of 450μ and aluminum foil 11b with a thickness of 10μ
and a polyethylene film 11c on both sides.
The container is laminated with a thickness of 30μ, preferably at least the surface that contacts the contents is water resistant, and is made of a material mainly consisting of highly rigid paper. The same applies to the lid 12, but the thickness
It may be made of only aluminum foil of about 120 μm.
At the bottom of the container 11, there is an inner bottom plate 1 which has plasticity and is deformable as shown in FIGS.
3 and a rigid outer sole plate 14 is attached. In other words, as an example, 60μ on one side of a 40μ thick aluminum foil.
As shown in the figure, the inner bottom plate 13 made of a polyethylene laminated material is attached to the container body 11 in a bowl shape so as to be curved downward (as an example, the radius of curvature is 54 mm), and with the adhesive margin 15 facing upward, they are attached to each other. The opposing polyethylene surfaces are fixed by thermal bonding. A ventilation hole 16 is provided in the outer sole plate 14 that does not have a vent hole 16. In FIG. 2, the inner bottom plate 13a has the same form as in FIG.
This is an example in which the direction of a is downward. Note that the cross-sectional shape of the inner sole plate is not limited to a bowl shape, and in some cases, annular or lattice-shaped folds may be formed in advance on the inner sole plate itself. Note that the inner bottom plate deforms as the volume of the contents decreases as described later, and is therefore referred to as a variable bottom plate in this specification. By the way, when hot filling the contents, for example, the liquid heated to about 93°C is filled into the container 11.
After filling the container with a lid 12 and performing a so-called top seal, the container is forcedly cooled until the temperature inside the container reaches around 30°C, for example, by water cooling with shearing at around 10°C. When the container is cooled in this manner, the volume of the contents decreases due to volumetric contraction of the liquid within the container, solidification of vapor within the container, volumetric contraction of air, etc. As the volume of the contents decreases, the inside of the container becomes under reduced pressure, which causes the inner bottom plate 13 or 13a to curve (deform) upward. However, if there is a pinhole, etc. on the wall of the container, or in the adhesive area between the container body and bottom plate, or the container body and lid plate, liquid or air leakage will occur from that area. As a result, a reduced pressure state does not occur, so the internally deforming bottom 13 or 13a does not deform and maintains its original shape after filling. This is illustrated in Figures 3A to 3D, where Figure A shows the state of the variable bottom when filling with liquid.
Figure B shows the state in which the container is attached to the lid after filling. In this case, when there is no liquid leakage, the variable bottom 13 deforms upward as shown in Figure C, but when there is liquid leakage, the variable bottom 13 does not deform as shown in Figure D. The present invention is of course capable of detecting not only liquid leaks but also air leaks (strictly speaking, air inflows) caused by pinholes or the like in the container itself. By the way, whether or not the variable bottom 13 deforms as the volume of the contents changes has nothing to do with the presence or absence of the outer bottom plate 14 as shown in FIGS. 1 and 2. Therefore, as shown in FIG. Container 1 that is not attached
The present invention can also be applied to 1a. By the way, in the present invention, the presence or absence of liquid leakage is determined by detecting the presence or absence of deformation of the variable bottom by the following means, targeting a liquid-tight container having a variable bottom as described above. It's a gift. For example, a commercially available X-ray level checker (MLS, manufactured by Hitachi Medico)
5A and P) to detect the presence or absence of deformation of the variable bottom. As shown in Fig. 5, this level checker includes an X-ray generator 1 having a high voltage transformer 17.
8 and an X-ray detector 19 corresponding to this generator, and this X-ray generator 18 and X-ray detector 19
As shown in FIGS. 1 and 2 and FIG. 4, the
The variable area in 13a is irradiated.
When the variable bottom portion of the container is irradiated with the X-ray beam horizontally, the beam passes straight through the container and reaches the detector 19. At this time, depending on whether or not the variable bottom is deformed, the The output voltage of 19 changes as shown in FIG. That is, variable base 1
When 3 or 13a is turned upward due to deformation, the detector detects a voltage Q _B that has passed through the air layer inside the container. If there is a liquid leak in the container and the variable bottom does not deform, the X-ray beam will pass through the liquid layer, so the amount of X-rays Q _A that has passed through it will be detected, Q _B > Q _A The relationship is By the way, there are cases where the variable bottom is irregularly deformed, and the deformation becomes insufficient or irregular as shown by symbols B and C in FIG.
Since the value of Q _K is the intermediate value between Q _A and Q _B , this Q _K
If is set to an appropriate value as described below, this value becomes a reference and it is possible to very easily determine the presence or absence of liquid leakage in the container, in other words, the suitability of the leakage. This will now be explained in detail based on FIGS. 7 and 8. X-ray generator 1 that irradiates a 6mm X-ray spot
Figure 8 plots the change in signal voltage when the position of the apex of the variable bottom 13 in the container 11 is changed with the spot center K of the container 11 set at a height of 15 mm from the bottom of the container 11. This is a graph of If no liquid leakage is observed in the container and the variable bottom 13 is deformed in a normal manner, the distance A in FIG. 7 is 18.7.
mm, the top of the variable bottom 13 is at the highest position, and its output signal voltage shows 5V. Similarly, B shows 3.6V, and C and D show 1V. In the illustrated example, when the apex of the deformed part of the variable bottom is at position B, the deformed state is slightly insufficient compared to position A, but it is judged to be "appropriate" for practical purposes in terms of liquid leakage. On the other hand, it can be determined that the deformation in case C is too insufficient and there is obvious liquid leakage. In other words, if the output signal voltage from the X-ray detector 19 is 2.5V or higher, it can be determined that the product is non-defective with respect to liquid leakage. The above value corresponds to Q _k in Figure 6, but this value can be set as appropriate depending on whether or not it will cause problems when the container is placed in the actual distribution process. It is operated to distinguish between good and defective products based on the following criteria. Incidentally, the horizontal axis in the graph of Fig. 8 shows the degree of deformation of the top of the variable bottom 13 between the normal deformed state (position at a distance of 18.7 mm from the bottom) and the reference value (0).
Distances are shown when measured as mm). The above example deals with determining liquid leakage using an X-ray beam, but if the container and its variable bottom are made of a transparent material and the contents are filled with an opaque liquid, the same method as described above can be used. Depending on the method, the presence or absence of liquid leakage can also be determined using light beams. [Test Example, Comparative Example] Orange juice heated to 93°C is filled in the container shown in the figure, and after cooling in a sealed state, the liquid level method is carried out in a stationary state (detection method according to the invention of the above-mentioned Japanese Patent Application No. 58-97986). 50 cans with no liquid leakage and 50 cans with liquid leakage (see Figure 9 C and D) were taken out, and as shown in Figure 9 A and B, these cans were subjected to the method of the present invention. Upon selection, almost the same results were obtained as shown in the table on the next page. When measuring and sorting the same objects as above on a conveyor moving at a speed of 20 m/min, it was found that with the method of the prior invention, the liquid level in the container waved as it was transferred, causing a so-called liquid shaking phenomenon. There were many. On the other hand, since the method of the present invention is not affected by liquid shaking, almost the same results as when the liquid was stationary were obtained.

[Table] [Effects of the Invention] As explained in detail above, the present invention provides a variable bottom of a liquid sealed container for hot filling due to a depressurization phenomenon.
By utilizing the deformation, X-rays or light beams are irradiated to this variable bottom part, and the presence or absence of liquid leakage can be determined based on the amount of radiation transmitted, so compared to the previous invention, liquid leakage inside the container is reduced. It is possible to determine the presence or absence of liquid leakage or air inflow without being affected by the amount of liquid being filled, and without being affected by variations in the amount of liquid filled, making it possible to detect on a conveyor that is constantly moving. , exhibits industrial utility.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a container applied to the present invention, Fig. 2 is a sectional view of the bottom of the container showing another application example of the same, and Figs. 3 A to D are leakage of liquid in a container with a variable bottom. 4 is a side view showing a state in which the variable bottom part is irradiated with an X-ray beam, and FIG. 5 is a diagram showing the principle of measurement using an X-ray beam. Figure 6 is a graph showing the correlation between the output value and the degree of deformation of the variable bottom, Figure 7 is a detailed diagram showing the state in which the variable bottom of the container is irradiated with the X-ray beam, and Figure 8 is the X-ray detector. FIG. 9 is a graph showing the relationship between the output value and the deformed height of the variable bottom, and FIG. 9 is an explanatory diagram showing the relationship between the example of the present invention and the comparative example. 11: Container body, 12: Lid, 13: Variable bottom, 1
4: Outer bottom plate, 15: Adhesive part, 17: Transformer, 1
8: X-ray generator, 19: X-ray detector.

Claims (1)

[Claims] 1. Targeted at containers that are hot-filled with contents in a hot-filling liquid sealed container equipped with a variable bottom, then sealed, and the variable bottom is deformed by utilizing the depressurization phenomenon caused by the temperature drop after cooling. A hot filling method characterized in that an X-ray or light beam is irradiated from the outside of the container at the variable bottom portion of the container approximately in the diametrical direction, and liquid leakage from the container is detected based on the amount of transmitted light. A method for detecting liquid leaks in sealed liquid containers.