JP3773837B2 - Barrier property inspection method for paper containers - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for inspecting barrier properties of a paper container used in a sealed state.
[0002]
[Prior art]
Paper containers are often used as containers to store liquids, but if the contents are juice, liquor or soy sauce that deteriorates when exposed to oxygen, the contents must be stored in order to preserve the contents for a long period of time. In the space of the housed and sealed paper container, for example, in the case of a gobeltop type paper container, a means is taken to perform gas replacement by filling the top space with nitrogen gas.
[0003]
However, if the gas container is not sufficiently gas-barrier even if the gas container is filled and filled with nitrogen gas to replace the gas, the nitrogen gas filled in the paper container will be While passing through the container and leaking into the atmosphere, oxygen in the atmosphere may enter the voids, and nitrogen gas and oxygen may be replaced over time, making it impossible to achieve long-term storage of the contents. . This is due to the barrier properties of the container material itself, the presence of minute pinholes that occur during paper container molding, the sealing characteristics of the paper container seal part, the area and shape of the anti-adhesive applied to the paper container opening part, etc. .
[0004]
For this reason, in order to obtain a paper container having a barrier property required for long-term storage of contents, the container material having a barrier property, the heat seal temperature of the paper container seal part and / or the area of the anti-adhesive applied to the opening part Various shapes and the like are examined, and in selecting and determining these, inspections are performed to determine the influence of these on the barrier properties of the paper container. As a method for inspecting the barrier property of a paper container, conventionally, for a paper container sealed with nitrogen gas filled in a gap of the paper container, the oxygen concentration in the gap is measured over time, and the increase rate of the oxygen concentration is determined. I went by asking.
[0005]
[Problems to be solved by the invention]
However, in the above-described barrier property inspection method for a paper container, the nitrogen gas in the gap of the paper container is replaced with oxygen in the atmosphere, and the oxygen concentration that has entered the paper container is measured. There are some problems.
[0006]
Since both nitrogen and oxygen to be substituted have a large molecular weight, it takes some time to work even if nitrogen gas escapes from the paper container to the atmosphere or oxygen enters the paper container from the atmosphere. The nature is bad. Further, both nitrogen and oxygen to be substituted are present in the atmosphere, and particularly nitrogen is present in about 80% in the atmosphere. On the other hand, oxygen is dissolved in the contents of the paper container, and when the oxygen concentration in the paper container is low, it is considered that a part of the dissolved oxygen is vaporized and moves to the gap. For this reason, the difference in oxygen concentration due to the quality of the barrier property does not appear so large, and accuracy is lacking. Therefore, it is difficult to detect barrier differences due to minute pinholes generated during paper container molding or slight differences in the sealing characteristics of the paper container seal part, and it is possible to determine the effect of these on the barrier properties. Can not.
[0007]
The objective of this invention is providing the barrier property inspection method of a paper container which can test | inspect the barrier property of a paper container in a short time correctly and precisely.
[0008]
[Means for Solving the Problems]
To achieve the above object, the barrier property inspection method of a paper container according to the present invention, the paper container gap portion of the gable-top type filled with contents were sealed and filled with helium gas at a pressure greater than or equal to 3 kPa, After sealing, the helium gas concentration (replacement rate) in the paper container gap is measured over time, and the barrier property of the paper container is inspected using the helium gas concentration as an index.
[0009]
From such a configuration, the helium gas filled in the gap of the paper container has a low molecular weight and smoothly escapes from the paper container to the atmosphere, so that the inspection can be performed in a short time, and its workability is improved. Since helium gas is hardly present in the atmosphere, the difference in helium gas concentration due to the quality of the barrier is large, enabling accurate inspections, and even minute pinholes and paper container seals that are generated during paper container molding It is also possible to detect a difference in the barrier due to a slight difference in the sealing characteristics of the portions, and it is possible to easily determine the influence of these on the barrier property. Moreover, since helium gas is an inert gas, it is safe.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the paper container barrier property inspection method according to the present invention will be described. In the present invention, first, helium gas is blown into the gap immediately before sealing the paper container, and the air in the gap of the paper container is replaced with helium gas and sealed.
[0011]
When the paper container is sealed in this way, the concentration of helium gas filled in the gap is measured and recorded as the initial value of helium gas concentration, with as little time as possible. After that, after a predetermined time has passed, the concentration of helium gas in the gap portion of the paper container which is prepared under the same conditions and filled with helium gas under the same conditions is measured, and the initial value of helium gas concentration is measured. The barrier property of the paper container is determined using a decrease in the helium gas concentration after a predetermined time as an index.
[0012]
As described above, helium gas is blown immediately before sealing the paper container, and the concentration of helium gas in the gap immediately after sealing is set to the initial helium gas concentration, but the helium gas concentration in the gap due to the filling pressure of helium gas. Since the initial value of the gas becomes different, it is necessary to verify the filling pressure of helium gas as a preparation.
[0013]
That is, since the molecular weight of helium itself is small, when the gap is filled with helium gas, the gap is not filled with helium gas unless the pressure is higher than the conventional filling pressure of nitrogen gas. For example, if the paper container is gate blanking Rutoppu type, when filling helium gas into the top gap portion, the initial value of the density of the helium gas within the gap portion does not at least 3KPa about the pressure, i.e. the helium gas and air In some cases, the replacement ratio of the resin is 40% or less, and such a concentration is not necessarily suitable for the inspection of the barrier property of the paper container.
[0014]
In the inspection of the barrier property of the paper container, the concentration of helium gas filled in the gap is preferably at least 50% or more. In particular, when filling a paper container having a gap of about 30% with respect to the container capacity, a pressure of about 7 KPa is preferable, and thereby the concentration of helium gas in the gap reaches about 70%.
[0015]
After filling the paper container with helium gas, the helium gas concentration in the paper container can be measured by destroying the paper container in water and collecting the gas in water using a sealed plastic container. A method of measuring the concentration of helium in the gas collected in this plastic container, or affixing rubber or the like on the outer surface of the paper container corresponding to the gap filled with helium gas, It is carried out by a method such as piercing from above to suck the gas in the paper container and measuring the concentration of helium in the collected gas, but is not limited thereto.
[0016]
Time-lapse measurement of the helium gas concentration in the gap of the paper container by the measurement method described above is a trial production under the same conditions, preparing a plurality of paper containers filled with helium gas, and the helium gas concentration in the gap in each paper container May be measured at different predetermined times.
[0017]
According to the paper container barrier property inspection method performed as described above, helium gas filled in the paper container gap has a low molecular weight and smoothly escapes from the paper container into the atmosphere. Permeated through the paper container in a much shorter time than the nitrogen gas or oxygen paper container permeation time that has been used for property inspection, thereby shortening the barrier property inspection time of the paper container and improving workability . In addition, since helium gas is hardly present in the atmosphere, the difference in helium gas concentration due to good or bad barrier properties is large, enabling accurate inspections. Furthermore, minute pinholes and paper that are generated when paper containers are molded Differences in barriers due to slight differences in the sealing characteristics of the container seal portion can also be detected, and the influence of these on the barrier properties can be easily determined. In particular, if the concentration of helium gas in the gap of the paper container immediately after sealing is 50% or more, the difference in helium gas concentration due to the quality of the barrier property becomes larger, and more accurate and precise inspection is possible. Moreover, since helium gas is an inert gas, it is safe.
[0018]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
Example 1
A paper container material 4 having a laminated structure shown in FIG. 1 in which low-density polyethylene layers 2 and 3 are arranged on both sides of the paperboard layer 1, and a gable-top type paper container 5 having a capacity of 1050 ml is molded by a conventional method. As shown in FIG. 2, 500 ml of water was filled, and after helium gas was blown into the gap 7 from the nozzle 6 at a pressure of 7 KPa, the top seal opening 8 was used at 330 ° C. or 350 ° C. using the top seal bar 9. The top was sealed by heat sealing at 0 ° C. At this time, the initial value of the concentration of helium gas filled in the gap 7 of the paper container 5 was 50%.
[0019]
For the two types of paper containers 5 obtained, the concentration of helium gas 12 hours after filling the gap 7 in the paper container 5 with helium gas was measured. Heat sealing at 350 ° C. was 8%. This difference is caused by a difference in adhesive force of the top seal opening portion 8 caused by a difference in seal temperature for sealing the top seal opening portion 8, and a difference in barrier property of the paper container 5 is caused by a difference in seal temperature. Was detected.
[0020]
Example 2
A paper container material 15 having a laminated structure shown in FIG. 3 in which a low density polyethylene layer 11 is arranged on the outer surface side of the paperboard layer 10 and a low density polyethylene layer 12, an aluminum foil layer 13 and a low density polyethylene layer 14 are arranged on the inner surface side. , A 1050 ml gable top type paper container was prototyped as three types of paper containers A, B, and C (not shown) having different areas of anti-adhesive applied to the top seal opening portion. , B and C were filled with 800 ml of water, and in the same manner as in Example 1, helium gas was blown into the gaps of the respective paper containers A, B and C at a pressure of 7 KPa, and then the top seal opening portion was The top was sealed by heat sealing with a seal bar. At this time, the initial value of the concentration of helium gas filled in the gaps of the paper containers A, B, and C was 75%.
[0021]
For these three types of paper containers A, B, and C, the concentration of helium gas measured three days after filling the gap with helium gas was 28% for paper container A, 45% for paper container B, and paper. Container C was 60%. This difference is caused by the difference in the adhesive property of the top seal opening portion caused by the difference in the area of the antiadhesive agent applied to the top seal opening portion, and the difference in the area of the antiadhesive agent applied to the top seal opening portion. It was detected that the difference in the barrier property of the paper container was caused by the difference.
[0022]
Comparative Example 1
A paper having a laminated structure in which the low density polyethylene layer 11 is disposed on the outer surface side of the paperboard layer 10 and the low density polyethylene layer 12, the aluminum foil layer 13, and the low density polyethylene layer 14 are disposed on the inner surface side used in Example 2. A prototype of the container material 15 with a capacity of 1050 ml, filled with 1000 ml of water in three types of paper containers A, B and C with different areas of anti-adhesive applied to the top seal opening. In the same manner as in Example 1, nitrogen gas was blown into the gaps of the paper containers A, B, and C at a pressure of 7 KPa, and then the top seal opening was heat sealed to seal the top. At this time, the initial value of the oxygen concentration in the gaps of the paper containers A, B, and C was 9.5%.
[0023]
For these three types of paper containers A, B, and C, the oxygen concentration was measured 3 days after filling the gap with nitrogen gas. The paper container A was 13%, the paper container B was 12%, and the paper container C. Measured 12%, oxygen concentration after one week, 15% for paper container A, 14% for paper container B, 12% for paper container C, and measured oxygen concentration after three weeks, paper container A was 17%, paper container B was 16%, and paper container C was 16%. Although the difference in oxygen concentration in the paper container gap can be detected in this way, the numerical value change remains small compared to helium, and the subtlety of the barrier property of the paper container caused by the difference in the area of the anti-adhesive applied to the top seal panel This difference was difficult to detect.
[0024]
Comparative Example 2
800 ml of water was put into a 1050 ml gable top type paper container molded in the paper container material 4 having a laminated structure in which the low density polyethylene layers 2 and 3 are arranged on both sides of the paperboard layer 1 used in Example 1. After filling and nitrogen gas was blown into the gap at a pressure of 5 KPa, the top seal opening was heat sealed at 330 ° C. or 350 ° C. in the same manner as in Example 1 to seal the top. At this time, the initial value of the oxygen concentration in the gap of the paper container was 11%.
[0025]
For the two types of paper containers obtained, the oxygen concentration was measured 12 hours after filling the gap with nitrogen gas, and 17% heat sealed at 330 ° C and 17% heat sealed at 350 ° C. 17%. Thus, there is no difference in the oxygen concentration in the paper container gap, and a subtle difference in the barrier property of the paper container due to the difference in the sealing temperature when heat-sealing the top seal panel is detected when left for at least 12 hours. could not.
[0026]
【The invention's effect】
As described above, according to the barrier property inspection method for a paper container according to the present invention, the paper container gap is filled with helium gas and sealed, and after sealing, the helium gas concentration in the paper container gap is measured over time. The barrier property of the paper container is inspected by using the decrease in the helium gas concentration as an index. The helium gas filled in the gap of the paper container has a low molecular weight and smoothly escapes from the paper container into the atmosphere, so the time required for inspection of the barrier of the paper container can be shortened and workability improved. Because there is almost no difference in the helium gas concentration due to the good or bad barrier properties, it enables accurate inspection, and furthermore, the sealing characteristics of minute pinholes and paper container seals that occur during paper container molding It is also possible to detect a difference in barriers due to a slight difference between them, and it is possible to easily determine the influence of these on the barrier properties. Further, since helium gas is an inert gas, there is an effect that it is safe.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a paper container material used in an embodiment of a paper container barrier property inspection method according to the present invention.
FIG. 2 is an explanatory view showing a step of blowing helium gas into the paper container in the embodiment of the paper container barrier property inspection method according to the present invention.
FIG. 3 is a cross-sectional view showing an example of a paper container material used in another embodiment of the paper container barrier property inspection method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Paperboard layer 2 Low density polyethylene layer 3 Low density polyethylene layer 4 Paper container material 5 Paper container 6 Nozzle 7 Cavity part 8 Top seal opening part 9 Top seal bar 10 Paperboard layer 11 Low density polyethylene layer 12 Low density polyethylene layer 13 Aluminum foil Layer 14 Low density polyethylene layer 15 Paper container material

Claims (1)

The contents of the paper container gap portion of the gable-top type filled with the helium gas is filled at a pressure greater than or equal to 3KPa was sealed, after sealing, over time to measure the helium gas concentration of paper containers gap portion, the helium gas concentration A method for inspecting the barrier property of a paper container, wherein the barrier property of the paper container is inspected by using as an index.

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