JP2002062236A - Measuring method and device for gas absorbing performance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide technology with high reliability for easily, quickly measuring the gas absorbing performance of a gas absorber. SOLUTION: This measuring device is equipped with a rigid container 1 having on its inside a chamber 10 for sealing a sample containing an oxygen absorber; a temperature sensor 4 for measuring the temperature within the chamber; a heater and a temperature controller 31 for heating the inside of the chamber at a constant temperature higher room temperature and keeping the constant temperature; a pressure sensor 20 and a pressure gauge 21 for continuously measuring pressure variation within the chamber with the temperature kept constant; and a computing recorder 5 for calculating the maximum oxygen absorbing amount based on the pressure difference between the peak pressure within the chamber soon after heating and the pressure after a certain time elapses from the start of heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a highly reliable technique for easily and quickly measuring the gas absorption performance of a gas absorbent.

[0002]

2. Description of the Related Art Conventionally, various gas absorbents have been used. In particular, oxygen absorbers are widely used in container packaging materials and the like in order to maintain the flavor of food and enable long-term storage of food. Conventionally, when examining the absorption performance of various absorbents such as such oxygen absorbents, the residual gas concentration of oxygen and the like after a certain period of time has elapsed after sealing these absorbents in a closed container. Was. Then, the amount of absorbed gas such as oxygen per unit absorbent was determined from the measured residual gas concentration.

[0003]

However, in the conventional method for measuring gas absorption performance, every time the residual gas concentration is measured, it is necessary to take out the gas from the closed vessel and apply it to a gas concentration measuring device. For this reason, there was a problem that a complicated operation had to be repeated.

In addition, in the conventional method, the residual gas concentration is measured when the gas absorption performance is saturated.
As a result, it took a long time of about one to three days until the measurement result was obtained. For this reason, it was difficult to evaluate gas absorption performance in a short time by the conventional method.

[0005] By the way, as the gas absorption performance, even if the maximum gas absorption after the gas absorption is saturated is not directly obtained,
In principle, it is also possible to estimate the maximum gas absorption amount in a short time by obtaining a gas absorption curve showing a temporal change of the gas absorption amount based on the measurement value after a certain time has elapsed.

[0006] However, the conventional method is a destructive inspection for taking out gas from a closed container when measuring gas concentration. For this reason, the gas concentration could be measured only once for one sample. As a result, in order to measure the gas concentrations after a plurality of elapsed times in order to obtain a gas absorption curve, it is necessary to prepare samples for the number of times of measurement.

Therefore, in the conventional method, it is difficult to increase the number of times of measurement, and the measurement samples at each elapsed time are different from each other, so that it is difficult to obtain an accurate gas absorption curve. For this reason, there is a problem that it is difficult to obtain the maximum gas absorption amount when the gas absorption is saturated with high reliability based on the measurement value after a certain time has elapsed.

The present invention has been made to solve the above problems, and has as its object to provide a highly reliable technique for easily and quickly measuring the gas absorption performance of a gas absorbent.

An example of a technique for measuring the amount of generated gas without measuring the gas concentration is disclosed in Japanese Patent Application Laid-Open No. 10-33256.
No. 6 discloses this. According to the technique disclosed in this publication, a change in volume due to absorption of generated gas is measured as a change in liquid level or liquid weight in a state where the three-way cock is operated to atmospheric pressure. Therefore, in this prior art, pressure is not directly measured.

Furthermore, in this prior art, it is assumed that all the generated gas is absorbed by the absorbent. This is because if all the generated gas is not absorbed, the measured value such as the fluctuation amount of the liquid level does not accurately represent the generated gas amount. Therefore, this prior art has a fundamentally different technical idea from measuring the absorption performance of the gas absorbent as in the present invention.

[0011]

According to a first aspect of the present invention, there is provided a method for measuring gas absorption performance, comprising the steps of: providing a gas absorbent of a specific type in a chamber of a rigid container; A method of enclosing a sample containing the sample, heating the chamber to a constant temperature equal to or higher than room temperature, and continuously measuring the pressure change in the chamber while maintaining the constant temperature, and obtaining the gas absorption performance of the sample from the pressure change. There is.

As described above, according to the method for measuring gas absorption performance of the present invention, the pressure change in the chamber is measured instead of directly measuring the gas concentration. Therefore, there is no need to perform complicated operations such as gas extraction, so that the gas absorption performance can be easily measured.

Moreover, in the present invention, the pressure in the chamber is continuously measured. As a result, substantially innumerable measurement points can be obtained for one sample. Therefore, gas absorption performance can be measured easily and in a short time with high reliability.

According to the second aspect of the present invention, when obtaining gas absorption performance from a pressure change, the peak pressure in the chamber immediately after the heating and the pressure in the chamber after a certain period of time immediately after the heating are obtained. This is a method for obtaining gas absorption performance based on a pressure difference. As described above, if the gas absorption performance is obtained based on the pressure difference after the lapse of a certain time, the gas absorption performance can be measured in a short time.

According to the third aspect of the present invention, when obtaining the gas absorption performance based on the pressure difference ΔP, the gas absorption amount A is obtained by the following equation (1): A = V (ΔP / P) (1) where V: chamber volume, P: atmospheric pressure In this way, the gas absorption amount A can be easily obtained from the pressure difference ΔP, and the gas absorption performance can be easily measured in a short time. be able to.

According to the fourth aspect of the present invention, when obtaining the gas absorption performance based on the pressure difference, the gas absorption amount A is converted to the maximum gas absorption amount a by the following approximate expression (2).
There is a way to ask. a = A (1-e- ^{b (tc)} ) (2) where t: elapsed time after the start of heating, b: absorption rate coefficient, c: reaction start delay time

As described above, by using the approximate expression, the maximum gas absorption amount when the gas absorption is saturated can be easily obtained based on the measured value after a lapse of a predetermined time immediately after the heating. In the present invention, since the pressure is continuously measured, the degree of coincidence between the measured value and the approximate curve can be easily determined.

According to a fifth aspect of the present invention, there is provided a method of using a specific type of gas absorbent as an oxygen absorbent. In this way, the oxygen absorbing performance of the oxygen absorbent is
Measurement can be performed easily and in a short time with high reliability.

According to a sixth aspect of the present invention, there is provided a method for sealing water in a chamber together with the sample when the sample is mainly composed of iron powder. In this way, the water triggers the oxidation reaction of the iron powder, and the oxygen absorption performance can be measured.

According to a seventh aspect of the present invention, when a sample is sealed in a chamber, the chamber is filled with a specific type of gas. By filling the gas of the characteristic type in this manner, the concentration of the specific type of gas in the chamber can be increased, so that the gas absorption rate can be increased and the gas absorption amount can be saturated in a shorter time.

Further, according to the gas absorption performance measuring apparatus of the present invention, a rigid container having a chamber for enclosing a sample containing a specific type of gas absorbent therein, and a temperature in the chamber are determined. Temperature measuring means for measuring, and heating the inside of the chamber to a constant temperature equal to or higher than room temperature, and heating means for maintaining the constant temperature, while maintaining the constant temperature,
It is configured to include a pressure measuring means for continuously measuring a pressure change in the chamber and an arithmetic means for obtaining a gas absorption performance of the sample from the pressure change.

As described above, according to the gas absorption performance measuring device of the present invention, the pressure change in the chamber is measured instead of directly measuring the gas concentration. Therefore, there is no need to perform complicated operations such as gas extraction, so that the gas absorption performance can be easily measured.

In addition, the present invention continuously measures the pressure in the chamber. As a result, substantially innumerable measurement points can be obtained for one sample. Therefore, the degree of coincidence with the approximate curve can be easily determined, and the gas absorption performance can be easily and quickly measured with high reliability.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, in which an example of measuring the absorption performance of an oxygen absorbent is described.

[First Embodiment] First, referring to FIG.
The configuration of the oxygen absorbing device as the gas absorbing device of the first embodiment will be described. As shown in FIG. 1, the oxygen absorbing apparatus includes a rigid container 1, a pressure sensor 20 and a pressure gauge 21 as pressure measuring means, and a heater 30 as heating means.
And a temperature controller 31, a temperature sensor 4 as temperature measuring means, and an operation recorder 5 as arithmetic means.

The rigid container 1 has a chamber 1 having a capacity of 90 ml.
It has 0 inside. The chamber 10 is configured to be sealed by the main body 12 of the rigid container 1 and the lid 11. Then, the temperature controller 31 heats the inside of the chamber 10 to a constant temperature equal to or higher than room temperature by the heater 30,
The temperature inside the chamber 10 is monitored at the tip of the temperature sensor 4 to maintain the constant temperature. Although the temperature sensor 4 is illustrated over the heater 30 for convenience in FIG. 1, the temperature sensor 4 and the heater 30 are separated in an actual apparatus.

The pressure sensor 20 continuously outputs a pressure change in the chamber 10 maintained at a constant temperature as a voltage value. Then, the pressure gauge 21 measures the voltage value output from the pressure sensor 20 as pressure. Then, the arithmetic recorder 5 calculates the gas absorption performance of the sample from the pressure change measured by the pressure sensor 20.

Next, a measurement example of the oxygen absorption performance of the sample 6 in the form of a film containing an oxygen absorbent containing iron as a main component will be described. This film-shaped sample 6 has a thickness of 12 μm.
Polyethylene terephthalate film, 15 μm-thick nylon film, 30 μm-thick polypropylene (PP) film, 25 μm-thick PP film containing iron powder, and 30 μm-thick P film
It has a configuration in which P films are sequentially stacked. Then, in the present embodiment, three films having the above configuration and having a size of 15 mm × 120 mm are sealed in the chamber 10. Therefore, the total area of the film-shaped sample 6 is 90 cm ² .

Then, the film-shaped sample 6 is sealed together with water 7 in the chamber 10. Water 7 is stored at the bottom of the chamber 10.

In measuring the oxygen absorption performance, first,
By the heater 30 controlled by the temperature controller 31,
The temperature in the chamber 10 is raised to a constant temperature equal to or higher than room temperature. Here, as a constant temperature, heating is performed to, for example, 70 ° C. in a range of 70 to 80 ° C. With this heating,
The water vapor pressure of the enclosed water 7 increases, and this water 7 triggers an oxidation reaction of the iron powder.

The temperature controller 31 is connected to the temperature sensor 4
Based on the temperature monitored by, the heater 30 maintains the inside of the chamber 10 at a constant temperature. Then, in this state, a pressure change in the chamber 10 is continuously measured by the pressure sensor 20. The water vapor pressure in the chamber 10 is substantially constant during the pressure measurement.

Here, the time change of the pressure in the chamber 10 will be described with reference to FIG. The horizontal axis of the graph in FIG. 2 represents the elapsed time (hour; Hour) after the start of heating, and the vertical axis represents the pressure (kPa) in the chamber 10.
A curve Ia in the graph indicates a measured value of a time change of the pressure in the chamber 10 immediately after the heating. As shown by the curve Ia, the pressure in the chamber 10 reaches a peak about 10 minutes after the start of heating. Then, the pressure subsequently decreases over time. The rate of pressure decrease is the highest immediately after heating, and decreases with time.

Then, in order to obtain the maximum gas absorption as the gas absorption performance of the sample 6 from the time change of the pressure, the arithmetic recorder 5 calculates the time change of the gas absorption. here,
A method for obtaining the gas absorption amount from the pressure change amount will be described. First, assuming that the volume of the chamber is V, the constant temperature represented by the absolute temperature is T, the initial oxygen partial pressure is n ₁ , and the initial pressure is P ₁ , the initial state equation is expressed by the following equation (3). Given. P ₁ V = n ₁ RT (3)

Further, the oxygen partial pressure after the elapse of a predetermined time is set to n ₂ ,
Assuming that the pressure is P ₂ , the state equation after a certain time is given by the following equation (4). P ₂ V = n ₂ RT (4) Therefore, the following expression (5) is derived from the above expressions (3) and (4). n ₂ = n ₁ (P ₂ / P ₁ ) (5)

Further, the amount of change Δn in the number of moles due to the absorption of oxygen is given by the following equation (6). Δn = n ₁ −n ₂ = n ₁ −n ₁ (P ₂ / P ₁ ) = n ₁ (P ₁ −P ₂ ) / P ₁ = ΔP · n ₁ / P ₁ = ΔP / P ₁ · (P ₁ V / RT) = VΔP / RT (6)

Here, when the change rate Δn of the number of moles is converted into a change amount ΔV into the volume of the chamber, it is given by the following equation (7). ΔV = ΔnRT / P = V (ΔP / RT) (RT / P) = V (ΔP / P) (7) In the above equation (7), P is not a gauge pressure but a gauge pressure. It is the pressure to which the atmospheric pressure (101.3 kPa) is applied.

Therefore, the total oxygen absorption amount A absorbed by the sample 6 is given by the following equation (8). A = V (ΔP / P) (8) Further, the oxygen absorption amount A1 per unit area of the film-shaped sample 6 having the area S is given by the following equation (9). A1 = (V / S) (ΔP / P) (9) Therefore, in the arithmetic recorder 5, the oxygen absorption amount A1 per unit area is obtained using the above equation (9).

Next, with reference to FIG. 3, a description will be given of the time change of the oxygen absorption amount obtained based on the measured value of the pressure shown in FIG. The horizontal axis of the graph in FIG. 3 represents the elapsed time (hour; Hour) after the start of heating, and the vertical axis represents the amount of oxygen absorbed per unit area (ml / cm ² ). A curve Ib in the graph indicates a measured value of a temporal change in the oxygen absorption based on the absorption at the time when the pressure is peaked. As shown in the curve Ib, the oxygen absorption amount increases with time. The rate of increase in the amount of oxygen absorbed is the highest immediately after heating, and slows down over time.

In this embodiment, the maximum oxygen absorption is measured as the oxygen absorption performance of the sample. The maximum oxygen absorption amount corresponds to the oxygen absorption amount after the oxygen absorption amount shown in the curve Ib is saturated. However, it takes time until the oxygen absorption amount is saturated. Therefore, here, the pressure difference between the peak pressure in the chamber immediately after heating and the pressure in the chamber after a certain period of time from the start of heating is measured, and the gas absorption amount A1 per unit area is calculated from the pressure difference. (9).

Table 1 below shows the elapsed time and the amount of oxygen absorbed per unit area at that time.

[0041]

[Table 1]

Then, based on the data shown in Table 1 above, the maximum gas absorption amount a1 per unit area is obtained by the following approximate expression (10). a1 = A1 (1-e- ^{b (tc)} ) (10) where t in the above equation (10) represents the elapsed time after the start of heating, b represents the absorption rate coefficient, and c represents the reaction start. Indicates the delay time.

Here, for example, the absorption rate coefficient b = 0.
31 (1 / Hour), reaction start delay time c = 0.06
(Hour) is obtained as a maximum oxygen absorption amount a1 = 0.103 ml / cm ² per unit area.

Therefore, in the present embodiment, the pressure difference between the peak pressure in the chamber immediately after heating and the pressure in the chamber after a certain period of time from the start of heating is measured.
Further, by using the approximate expression, the maximum oxygen absorption amount when the oxygen absorption is saturated can be obtained easily and in a short time based on the measurement value after a lapse of a certain time immediately after the heating.

[Second Embodiment] Next, a second embodiment of the present invention will be described. In the second embodiment, a description will be given of an example of measuring the oxygen absorption performance of a sheet-like sample including an oxygen absorbent containing iron as a main component in the apparatus configuration shown in FIG. This sheet-like sample is made of a polypropylene (PP) film having a thickness of 70 μm,
Film, 10 μm thick adhesive (AD) layer, 30 μm thick ethylene vinyl alcohol copolymer, 10 μm thick AD
It has a configuration in which layers and PP films having a thickness of 280 μm are sequentially laminated.

In the present embodiment, 30
A sheet having a size of 30 mm × 30 mm
Enclose sheets. The total weight of the sheet sample to be enclosed is 7.
It becomes 5 g. Further, also in the present embodiment, a sheet-like sample is sealed in the chamber 10 together with the water 7.

FIG. 4 shows the result of measuring the pressure change by heating the inside of the chamber 10 to 70 ° C. in the same manner as in the first embodiment. The horizontal axis of the graph in FIG. 4 represents the elapsed time (hour; Hour) after the start of heating, and the vertical axis represents the pressure (kPa) in the chamber 10. A curve IIa in the graph indicates a measured value of a time change of the pressure in the chamber 10 immediately after the heating. As shown by the curve IIa, the pressure in the chamber 10 reaches a peak in about 10 minutes from the start of heating. Then, the pressure subsequently decreases over time. The rate of pressure decrease is the highest immediately after heating, and decreases with time.

Then, in order to obtain the maximum oxygen absorption as the oxygen absorption performance of the sample from the time change of the pressure, the arithmetic recorder 5 calculates the time change of the oxygen absorption in the same manner as in the first embodiment. . However, in the second embodiment, the oxygen absorption amount A2 per unit mass of the sheet sample of mass M
Is calculated by the following equation (11) instead of the above equation (9). A2 = (V / M) (ΔP / P) (11)

Next, with reference to FIG. 5, a description will be given of the time change of the oxygen absorption amount obtained based on the measured value of the pressure shown in FIG. The horizontal axis of the graph of FIG. 5 represents the elapsed time (hour; Hour) after the start of heating, and the vertical axis represents the amount of oxygen absorbed per unit mass (ml / g). A curve IIb in the graph indicates a measured value of a temporal change in the oxygen absorption based on the absorption at the time when the pressure is at a peak. As shown in the curve IIb, the oxygen absorption increases with the passage of time. The rate of increase in the amount of oxygen absorbed is the highest immediately after heating, and slows down over time.

Also in the second embodiment, the pressure difference between the peak pressure in the chamber immediately after heating and the pressure in the chamber after a certain period of time from the start of heating is measured. Is obtained by the above equation (11).

Table 2 below shows the elapsed time and the amount of oxygen absorbed per unit area at that time.

[0052]

[Table 2]

In the second embodiment, the maximum oxygen absorption amount a2 per unit mass can be obtained by using the following approximate expression (12) in the same manner as in the first embodiment. a2 = A2 (1-e- ^{b (tc)} ) (12) where t in the above equation (12) represents the elapsed time after the start of heating, b represents the absorption rate coefficient, and c represents the reaction start. Indicates the delay time.

Here, for example, the maximum oxygen absorption amount per unit mass a2 = 1.96 ml / g and the absorption rate coefficient b =
0.125 (1 / Hour), reaction start delay time c =
0.05 (Hour) is obtained.

[Third Embodiment] Next, a third embodiment of the present invention will be described. In the third embodiment, an example of measuring the oxygen absorption performance when the initial oxygen concentration in the chamber 10 is changed will be described with reference to FIG.

The horizontal axis of the graph in FIG. 6 represents the elapsed time (hour: Hour) after the start of heating, and the vertical axis represents the chamber 10.
Represents the internal pressure (MPa). And the curve I in the graph
IIa shows a measurement result when the inside of the chamber 10 is set to an oxygen concentration equivalent to the atmosphere. The curve II in the graph
Ib indicates a measurement result when the chamber 10 is filled with only oxygen gas.

As shown by curve IIIb, immediately after heating,
When only oxygen gas is charged, the pressure drops more sharply than curve IIIa. However, as time passes, the curves IIIa and IIIb approach each other, and the pressure at the time of saturation is almost the same. Therefore, it can be understood that the maximum oxygen absorption amount of the oxygen absorbent can be measured regardless of the initial oxygen amount. If only oxygen gas is filled, the oxygen absorption rate can be increased and the oxygen absorption amount can be saturated in a shorter time. Further, the maximum oxygen absorption can be predicted earlier before the oxygen absorption reaches saturation.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, an example of measuring oxygen absorption performance when a sample is deactivated will be described with reference to FIG.

The horizontal axis of the graph in FIG. 7 represents the elapsed time (hour: Hour) after the start of heating, and the vertical axis represents the chamber 10.
Represents the internal pressure (kPa). And the curve I in the graph
V indicates a measurement result of a normal sample that has not been deactivated, measured under the same conditions as the measurement conditions in the above-described first embodiment. The curve V in the graph is the curve IV
2 shows the results of measurement on a sample in which 20% of the maximum oxygen absorption capacity of a normal product was inactivated under the same measurement conditions as in FIG.

As shown by the curve V, the pressure drop rate when the inactivated sample is sealed is slower than the pressure drop rate when the uninactivated normal sample is enclosed as shown by the curve IV. When the initial oxygen concentrations are equal to each other, the pressure drop rate is sharper as the maximum oxygen absorption amount is larger, and the pressure reduction rate is slower as the maximum oxygen absorption amount is smaller. Therefore, it can be seen that the maximum oxygen absorption of the inactivated sample is lower than that of the normal sample.

Further, the graph of FIG. 8 shows the relationship between the deactivation time and the amount of oxygen absorption. The horizontal axis of the graph in FIG. 8 represents the elapsed time (hour; Hour) after the start of heating, and the vertical axis represents 7 hours.
It represents the amount of oxygen absorbed per unit area (ml / cm ² ) measured 2 hours after heating to 0 ° C.

The broken line VI in the graph is 50 ° C.
3 shows changes in the amount of oxygen absorbed when the time of heating and deactivation was changed. As shown by the broken line VI, the longer the time of deactivation is, the lower the oxygen absorption amount tends to be.
Therefore, in the present invention, as the oxygen absorption performance,
In addition to the maximum oxygen absorption, it can be determined whether the sample has been deactivated or the sample has been deactivated and the maximum oxygen absorption has decreased.

In the above-described embodiment, an example in which the present invention is configured under specific conditions has been described. However, the present invention can be variously modified. For example, in the above-described embodiment, an example of an iron-based oxygen absorbent has been described. However, in the present invention, when the gas absorbent is an oxygen absorbent, the oxygen-absorbing performance of the organic oxygen absorbent is also measured. be able to. As an organic oxygen absorber, for example, M
A combination of X nylon and cobalt or a combination of diene and cobalt can be used.
When measuring the oxygen absorption characteristics of the organic oxygen absorbent, it is not necessary to enclose water with the sample.

In the above-described embodiment, an example of the oxygen absorbent has been described. However, in the present invention, the specific type of gas to be absorbed is not limited to oxygen. Further, in the above-described embodiment, an example in which only one type of gas is absorbed has been described. However, the present invention can also be applied to measurement of the absorption performance of a gas absorbent that absorbs a plurality of types of gases.

[0065]

As described in detail above, according to the present invention, the pressure change in the chamber is measured instead of directly measuring the gas concentration. Therefore, there is no need to perform complicated operations such as gas extraction, so that the gas absorption performance can be easily measured.

Moreover, in the present invention, the pressure in the chamber is continuously measured. As a result, substantially innumerable measurement points can be obtained for one sample. Therefore, gas absorption performance can be measured easily and in a short time with high reliability.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an oxygen absorption performance measuring device according to a first embodiment.

FIG. 2 is a measurement graph of a time change of pressure in the first embodiment.

FIG. 3 is a measurement graph of a time change of an oxygen absorption amount in the first embodiment.

FIG. 4 is a measurement graph of pressure change over time in the second embodiment.

FIG. 5 is a measurement graph of a time change of an oxygen absorption amount in the second embodiment.

FIG. 6 is a graph showing a temporal change in pressure according to a difference in oxygen concentration in the third embodiment.

FIG. 7 is a graph showing a time change of an oxygen absorption amount of a deactivated oxygen absorbent in a fourth embodiment.

FIG. 8 is a graph showing the relationship between the degree of deactivation and the amount of oxygen absorption in the fourth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rigid container 4 Temperature sensor 5 Operation recorder 6 Sample 7 Water 10 Chamber 11 Cover 12 Main body 20 Pressure sensor 21 Pressure gauge 30 Heater 31 Temperature controller

Claims (8)

[Claims] 1. A sample containing a gas absorber of a specific type is sealed in a chamber of a rigid container, and the inside of the chamber is heated to a constant temperature equal to or higher than room temperature. A method for measuring the gas absorption performance of the sample, wherein a pressure change in the sample is continuously measured, and a gas absorption performance of the sample is obtained from the pressure change. 2. In obtaining the gas absorption performance from the pressure change, based on a pressure difference between a peak pressure in the chamber immediately after the heating and a pressure in the chamber after a lapse of a certain time immediately after the heating. 2. The method for measuring gas absorption performance according to claim 1, wherein the gas absorption performance of the sample is determined. 3. The method for measuring gas absorption performance according to claim 2, wherein, when obtaining the gas absorption performance based on the pressure difference ΔP, a gas absorption amount A is calculated by the following equation (1). A = V (ΔP / P) (1) where V: volume of chamber, P: atmospheric pressure 4. The method according to claim 3, wherein, in obtaining the gas absorption performance based on the pressure difference, a maximum gas absorption amount a is obtained from the gas absorption amount A by the following approximate expression (2). Gas absorption performance measurement method. a = A (1-e- ^{b (tc)} ) (2) where t: elapsed time after the start of heating, b: absorption rate coefficient, c: reaction start delay time 5. The method for measuring gas absorption performance according to claim 1, wherein the absorbent for the specific type of gas is an oxygen absorbent. 6. When the sample contains iron powder as a main component,
The method for measuring gas absorption performance according to claim 5, wherein water is sealed in the chamber together with the sample. 7. The method for measuring gas absorption performance according to claim 1, wherein when the sample is sealed in the chamber, the specific type of gas is filled in the chamber. . 8. A rigid container having therein a chamber for enclosing a sample containing a specific type of gas absorbent, a temperature measuring means for measuring a temperature in the chamber, and a constant temperature in the chamber equal to or higher than room temperature. Heating means for heating and maintaining the constant temperature; pressure measuring means for continuously measuring a pressure change in the chamber while maintaining the constant temperature; gas absorption performance of the sample from the pressure change And a calculating means for determining the gas absorption performance.