JP2020085833A - Method and device for measuring gas permeability - Google Patents

Abstract

To provide a method and a device for measuring a gas permeability capable of increasing the accuracy of the gas permeability, even when there is a change of the differential pressure between a first-side partial space and a second-side partial space of a sample film.SOLUTION: In a first side of a sample film, there is formed a first-side partial space supplied with a measurement gas. In a second side of the sample film, there is formed a second-side partial space, in which the pressure is lower than in the first-side partial space. A pressure Pt in the second-side partial space is measured at each specific measurement time, and the change of the permeation pressure per unit time used for calculating a gas permeability is obtained by using the measurement pressure Pt of each measurement time.SELECTED DRAWING: Figure 8

Description

The present invention relates to a gas permeability measuring method and a gas permeability measuring apparatus using the gas permeability measuring method.

As the gas permeability measuring method, the methods shown in Patent Documents 1 and 2 have been proposed. In Patent Document 1, one side compartment space in which a measurement gas is supplied is secured on one side of the sample membrane as a reference, while on the other side of the sample membrane, the pressure is higher than the pressure of the one side compartment space. It shows that the pressure of the measurement gas that has permeated from the one-side compartment space to the other-side compartment space of the sample film is secured over time with the other-side compartment space kept at a relatively low pressure state. According to this, it is possible to obtain a pressure change with time in the compartment space on the other side of the sample membrane, and it is possible to calculate the gas permeability based on the gradient in the steady state. Patent Document 2 discloses a device that uses water vapor gas as a measurement gas under the same configuration as that of Patent Document 1, and if this is used, the water vapor permeability can be calculated.

Japanese Patent No. 3845055 Japanese Patent No. 5553287

However, in the above-mentioned gas permeability measuring method, the pressure in the other compartment space of the sample film gradually increases with the measurement, and the difference between the one compartment space and the other compartment space of the sample membrane. The pressure (the driving force for gas permeation) decreases, and the gradient formed by the change in pressure increase over time on the other side of the sample membrane gradually becomes gentle. Especially for a sample membrane with a high gas permeability, the pressure difference between the one-side compartment space and the other-side compartment space decreases at a relatively early timing, and on the other side of the sample membrane, with the passage of time. The gradient formed by the pressure change is not constant at an early stage (the gradient begins to turn into a saturation tendency (see FIG. 5)). Therefore, in gas permeability measurement, it is not easy to identify the gradient of the pressure change over time in the steady state. If such a gradient is used, it is either under the condition where the pressure difference between the one-side compartment space and the other-side compartment space changes with time, and based on such a slope, The accuracy and reliability of the calculated gas permeability cannot be said to be high.

The present invention has been made in view of the above circumstances, and a first object thereof is to provide a space between one side compartment space on one side with respect to a sample film and the other side compartment space on the other side with respect to a sample film. It is an object of the present invention to provide a gas permeability measuring method capable of enhancing the accuracy of gas permeability even when the differential pressure changes with the passage of time. A second object is to provide a measuring device used in the gas permeability measuring method.

In order to achieve the first object, the present invention has the following configurations (1) to (4).

(1) One side of the sample film, with reference to the sample film, secures a one-sided partition space in which a measurement gas is supplied, and the other side of the sample film has a pressure greater than that of the one-sided partition space. Also secures the other side compartment space that is in a low pressure state, measures the pressure of the other side compartment space at each predetermined measurement time, and by using the measured pressure at each measurement time point, gas permeation In the gas permeability measurement method for obtaining the change in permeation pressure per unit time used to calculate the
As the permeation pressure at each measurement time point, a correction pressure obtained by a correction process for the measurement pressure at each measurement time point is used,
As a correction process for obtaining the corrected pressure, the differential pressure between the pressure in the one side compartment space and the pressure in the other side compartment space is detected, and the differential pressure at each measurement based on the differential pressure at the start of measurement. By using the change rate of change, the measurement pressure at each measurement time is corrected to a value under the differential pressure at the start of measurement.

According to this configuration, since the measured pressure at each measurement time is corrected to a value under the differential pressure at the start of measurement, the corrected pressure change (gradient) per unit time formed by the corrected pressure at each measurement time is: The linearity is enhanced by strengthening the tendency to have a constant gradient according to the sample film, and the corrected pressure change (gradient) per unit time can be specified easily and accurately. Moreover, if the value per unit differential pressure is calculated using the differential pressure at the start of measurement for this change in corrected pressure per unit time, the calculation method is suitable for measurement (differential pressure at the start of measurement). It is possible to obtain the equivalent value (corrected pressure per unit time) under (divided by the differential pressure at the start of measurement) and the gas permeability with high accuracy.

(2) Under the configuration of (1) above,
As the correction pressure for each measurement time point, for each measurement time point, a value obtained by adding a correction amount to the correction pressure at the measurement time point immediately before each measurement time point is used.
As a correction amount for each measurement time point, the ratio of the differential pressure at the time of measurement to the differential pressure at each measurement time point, between the measurement pressure at each measurement time point and the measurement pressure at the measurement time point immediately before each measurement time point It is configured to use the product of the difference.

According to this configuration, as a specific method for the method (1), the measurement pressure at each measurement time can be corrected to a value under the differential pressure at the start of measurement, and the correction pressure at each measurement time can be corrected. Thus, it is possible to strengthen the uniformity of the correction pressure change (gradient) per unit time and improve the linearity. As a result, the gas permeability can be obtained in a highly accurate state, as in the above (1).

(3) Under the configuration of (1) or (2) above,
The one-side compartment space is open to the atmosphere.

According to this configuration, even if the measurement gas is supplied to the one-side compartment space under a flow condition, the measurement gas is discharged to the atmosphere, so that the pressure state in the one-side compartment space of the sample film is kept constant ( (Atmospheric pressure), and the structure for keeping the pressure state in the one-side compartment of the sample film constant can be simplified. On the other hand, even if the one-side compartment space is under atmospheric pressure, the one-side compartment space and the other-side compartment space of the sample film are There is a possibility that the differential pressure will change between the two, but this will also be understood as the differential pressure change rate based on the differential pressure at the start of measurement, and the pressure in the other compartment space will increase over time. Not only that, even when the atmospheric pressure changes, it is possible to obtain the correction pressure corresponding to the case where the gas permeability measurement is performed under the condition that the differential pressure at the start of measurement is maintained. As a result, even when the atmosphere fluctuates, the pressure change (gradient) in the other space per unit time is strengthened with a gradient according to the sample film regardless of the passage of time, and linearity is increased. Can be increased. As a result, also in this case, the gas permeability can be obtained in a state where the accuracy is increased, as in the above (1) and (2).

(4) Under the configuration of (3) above,
A gas containing water vapor as a measurement gas is supplied to the one-side compartment.

According to this configuration, even when the humidifying gas is used as the measurement gas, it is possible to obtain the gas permeability with a high accuracy.

In order to achieve the second object, the configurations (5) to (9) are adopted.

(5) One side compartment space in which a pair of cells for sandwiching the sample film are provided, and a measurement gas is supplied between one of the pair of cells and the sample film Is formed, between the other cell of the pair of cells and the sample film, the other side partitioned space whose pressure is lower than the pressure of the one side partitioned space is formed, and the other side partitioned space With respect to the gas permeability measuring device associated with the low pressure side pressure sensor for detecting the pressure of the other side compartment space at predetermined measurement time intervals,
A high pressure side pressure sensor for detecting the pressure of the one side compartment space,
Based on the detection information from the high-pressure side pressure sensor and the detection information from the low-pressure side pressure sensor, for the measurement start time point and each measurement time point, between the pressure of the one side compartment space and the pressure of the side compartment space The differential pressure is calculated respectively, and based on the calculated information, the ratio of the differential pressure at the time of measurement to the differential pressure at the time of measurement at each measurement time point is calculated, and the measured pressure at each measurement time point and the measurement time point immediately before each measurement time point are calculated. A correction amount calculation unit that calculates a difference between the measured pressure and the ratio and the difference is calculated as a correction amount.
The correction pressure of the measurement pressure at each measurement time point detected by the low-pressure side pressure sensor is used to calculate the gas permeability, and the correction amount calculation unit is added to the correction pressure at the measurement time point immediately before each measurement time point. A correction pressure calculation unit which is calculated by adding the correction amounts at the respective measurement points calculated by
Is provided.

With this configuration, it is possible to provide a specific device that uses the above-described usage method (2).

(6) Under the configuration of (5) above,
A communication hole that communicates the one-side compartment space with the atmosphere is formed in the one cell.

With this configuration, it is possible to provide a specific device that uses the method (3) described above.

(7) Under the configuration of (6) above,
With respect to the one side compartment space in the one cell, a gas supply path for supplying the measurement gas is connected,
An expansion space is formed in the gas supply path by expanding the gas supply path in the middle thereof.

According to this structure, not only can the gas supply path including the expansion space be used as a passage through which gas flows, but a water tank is formed with the expansion space, water is stored in the water tank, and the gas passes over the water surface. By doing so, the supply gas can also be a humidification gas. Therefore, the gas supply path can be used for multiple purposes.

(8) Under the configuration of (7) above,
The expansion space constitutes a water tank for accumulating water while ensuring the flow of the measurement gas.

According to this configuration, the humidifying gas can be supplied to the one-side compartment in one cell by flowing the gas through the gas supply path, and the gas supply path can be effectively used.

(9) Under the configuration of (8) above,
The expansion space is configured to be contained in any one of the pair of cells.

According to this configuration, even if an expansion space is formed in the gas supply path, the expansion space can be effectively contained by using the internal space of one of the pair of cells, and the gas permeability device can be used. Can be miniaturized as much as possible.

According to the present invention, even when the differential pressure between the one-side compartment space on one side with respect to the sample film and the other-side compartment space on the other side with respect to the sample film changes with the passage of time. It is possible to provide a gas permeability measuring method that can improve the accuracy of gas permeability and a gas permeability measuring device that uses the gas permeability measuring method.

The perspective view which shows the gas permeability measuring apparatus which concerns on embodiment. Explanatory drawing which shows simply the structure of the gas permeability measuring apparatus which concerns on embodiment. FIG. 4 is an explanatory view briefly explaining measurement of gas permeability under the upper cell and the lower cell according to the embodiment. The figure which shows notionally the functional structure of the arithmetic control part in the arithmetic processing unit which concerns on embodiment. Pressure change per unit time when the gas permeability measurement is performed under a constant differential pressure (after correction), and the unit time when the gas permeability measurement is performed under the situation where the differential pressure change occurs (before correction) Explanatory drawing explaining the pressure change per hit. When the gas permeability measurement is performed under a constant differential pressure (after correction), the change in pressure per unit time with time, and when the gas permeability measurement is performed under the condition that the differential pressure change occurs (before correction) Explanatory drawing explaining the time-dependent change of the pressure change per unit time. Pressure change per unit time when gas permeability measurement is performed (before correction) under the condition that differential pressure change occurs, and unit time when gas permeability measurement is performed under constant differential pressure (after correction) Explanatory drawing explaining the relationship with the pressure change per hit. FIG. 8 is an enlarged explanatory diagram of FIG. 7.

Before describing an embodiment of the present invention, a gas permeability measuring apparatus using the method will be described prior to the description of the gas permeability measuring method.

In FIG. 1, reference numeral 1 indicates a gas permeability measuring device in which the gas permeability measuring method is used. The gas permeability measuring apparatus 1 includes an upper cell 2 as one cell for holding the sample film 5 and a lower cell 3 as the other cell. The upper cell 2 is supported so that it can be laid down with respect to the lower cell 3, and when the upper cell 2 falls down with respect to the lower cell 3, the support surface 3a of the lower cell 3 and the upper cell 2 Of the upper cell 2 and the lower cell 3 form a chamber 4.

The gas permeability measuring apparatus 1 can be simply shown in FIGS. 2 and 3. The supporting surface 3a of the lower cell 3 is a surface on which the sample film 5 whose gas permeability is to be measured is to be placed, and the supporting film 3a is placed on the supporting surface 3a of the lower cell 3. In this state, when the upper cell 2 is laid down with respect to the lower cell 3, the lower cell 3 and the upper cell 2 sandwich the sample film 5 (states shown in FIGS. 2 and 3). Recesses 6 and 7 are formed on the pressing surface 2a of the upper cell 2 and the supporting surface 3a of the lower cell 3, and when the upper cell 2 and the lower cell 3 hold the sample film 5 therebetween. The recess 6 forms a one-sided partition space (hereinafter, the same reference numeral as that of the recess 6 is used) by closing the opening with the sample film 5, and the recess 7 has the opening with the sample film 5. By being closed, a partition space on the other side (hereinafter, the same reference numeral as that of the recess 7 is used) is formed. A seal ring 8 is provided on the peripheral wall of the recess 6 of the upper cell 2, and a filter paper 9 is housed in the recess 7 of the lower cell 3. As a result, when the upper cell 2 is laid down with respect to the lower cell 3, the seal ring 8 in the upper cell 2 has the sample film 5 arranged on the support surface 3 a in which the filter paper 9 is housed in the recess 7. Is pressed against the supporting surface 3a of the lower cell 3, and between the supporting surface 3a of the lower cell 3 and the pressing surface 2a of the upper cell 2, the radial inner side of the seal ring 8 is the radial direction. Airtightness is secured to the outside. In FIG. 1, reference numeral 10 denotes an annular shape formed on the pressing surface 2a of the upper cell 2 in order to attach a seal ring having a smaller diameter than the seal ring 8 in order to measure the sample film 5 having a small area. The groove 10. Reference numeral 53 is a holder for holding the upper cell 2 pressed against the lower cell 3 when the upper cell 2 is laid down with respect to the lower cell 3.

As shown in FIGS. 2 and 3, a gas supply path 12 and an atmosphere communication hole 13 are opened in the one-side compartment space 6 of the upper cell 2. The gas supply passage 12 has a role of supplying the measurement gas from the outside to the one-side compartment space 6 of the upper cell 2, and the gas supply passage 12 has a processing hole formed inside thereof in the upper cell 2. 14 (simply shown). The atmosphere communication hole 13 has a role of communicating the one-side compartment space 6 of the upper cell 2 and the atmosphere, and even if the measurement gas is supplied to the one-side compartment space 6 of the upper cell 2. The atmosphere communication hole 13 discharges the excess measurement gas, and the one-side compartment space 6 of the upper cell 2 is maintained at the atmospheric pressure. A humidity sensor 50 faces the atmosphere communication hole 13, and the humidity sensor 50 detects the relative humidity in the one-side compartment 6 under atmospheric pressure.

As shown in FIGS. 2 and 3, a passage 15 is opened in the other compartment space 7 of the lower cell 3. When the gas permeability is measured, the passage 15 has a role as a passage for evacuation to evacuate the other compartment space 7 of the lower cell 3 to a predetermined depressurized state (predetermined vacuum state). , Has a role as a pressure lead-out passage for detecting the pressure of the other-side compartment space 7 in the lower cell 3 during the measurement of the gas permeability. Therefore, as shown in FIG. 3, a vacuum pump 17 is associated with the passage 15 via a valve 16, and a low pressure side pressure sensor 18 for detecting the pressure of the other side partitioned space 7 in the lower cell 3 is provided. Are associated with.

As shown in FIG. 2, the upper cell 2 and the lower cell 3 have a temperature control circulation passage (circulation path) filled with circulating water of a constant temperature as a temperature control medium so that they are always kept at a constant temperature. )20 is incorporated. The temperature control circulation passage 20 includes an internal circulation space 21 formed inside the lower cell 3, an internal circulation space 22 formed inside the lower cell 3, and a connecting pipe (flexible pipe) for connecting them as a circulation passage. Sex connection hoses) 23 and 24. The connection pipe 23 (see FIG. 1), which is one of the connection pipes 23 and 24, is provided with a circulation pump (not shown) and a temperature adjusting device for keeping the temperature of the circulating water constant, By the circulation pump, the circulating water circulates in the temperature control circulation passage 20 as shown by the arrow in FIG.

As shown in FIG. 2, the gas supply passage 12 passes from a gas source (not shown) through the lower cell 3 and the connection pipe 24, and then the processed hole 14 (one side) in the upper cell 2. It is connected to the compartment space 6).

More specifically, as shown in FIG. 1, the gas supply path 12 includes a connecting pipe 31 from a gas source (not shown) to the lower cell 3. The connection pipe 31 is connected to the lower cell 3, and a gas having a predetermined dryness is supplied to the connection pipe 31 from a gas source (not shown). It can be adjusted by the mounted flow rate adjusting valve 33. In this case, various gases such as air, oxygen and nitrogen can be used as the gas supplied from the gas source.

In the lower cell 3, the gas supply path 12 forms a water tank 34 for storing water W by expanding the gas supply path 12 as shown in FIG. The water tank 34 is formed so as to open from the upper surface of the lower cell 3 to the outside so that water can be supplied from the outside, and the opening of the water tank 34 is covered with a lid 35. Inside the lower cell 3, a processing hole 36 (simply shown) connected to the connection pipe 31 is formed, and the processing hole 36 is formed in the water tank 34 more than the water surface Ws in the water tank 34. A gas from a gas source (not shown) is opened at a high position and is supplied onto the water surface Wa of the water tank 34. Further, a processing hole 38 (simply shown) is formed inside the lower cell 3, and one end opening of the processing hole 38 is located in the water tank 34 at a position higher than the water surface Ws in the water tank 34. Is opened in. As a result, the gas supplied from a gas source (not shown) is humidified by passing over the water surface of the water tank 33, and the humidified gas is supplied to the processed hole 38. At this time, since the gas has a predetermined dryness, the humidification (relative humidity) of the gas can be adjusted only by adjusting the flow rate of the gas by the flow rate adjusting valve 33. As a result, by adjusting the flow rate of the flow rate adjusting valve 33 manually or automatically based on the detection result of the humidity sensor 50, the humidification (relative humidity) of the measurement gas can be made desired.

In this case, the inside of the connection pipe 24 is connected to the internal circulation space 22 of the lower cell 3, and the circulating water is to be introduced into the connection pipe 24.

As shown in FIG. 2, the gas supply path 12 is configured with a connecting pipe 41 from the lower cell 3 to the upper cell 2. One end side of the connection pipe 41 is connected to the processing hole 38 of the lower cell 3, while the other end side of the connection pipe 41 is formed with an annular space 42 inside the connection pipe 24. It is stored in the opened state. Thereby, the circulating water at the predetermined temperature in the internal circulation space 22 in the lower cell 3 flows from the lower cell 3 to the upper cell 2 in the annular space 42 in the connecting pipe 24, and the upper cell 2 and the lower cell 3 are discharged. Not only is the temperature kept constant, but the humidified state of the humidified measurement gas flowing from the lower cell 3 to the upper cell 2 in the connecting pipe 41 is prevented from changing under the influence of the external temperature.

As shown in FIG. 2, the other end of the connection pipe 41 extends beyond the connection pipe 24 and is connected to the processed hole 14 of the upper cell 2. As a result, the humidifying gas as the measurement gas is supplied from the processing hole 14 to the one-side compartment space 6 in the upper cell 2.

As shown in FIG. 3, the gas permeability measuring apparatus 1 includes an arithmetic processing unit 51 in order to calculate the gas permeability GTR with respect to the sample film 5. Therefore, the pressure information from the low pressure side pressure sensor 18 and the atmospheric pressure information from the high pressure side pressure sensor 55 are input to the arithmetic processing unit 51. The arithmetic processing device 51 is provided with a storage unit 51A, an arithmetic control unit 51B, and a display unit 51C such as a display in order to ensure the function as a computer. The storage unit 51A is configured with storage elements such as a ROM (Read Only Memory) and a RAM (Random Access Memory), and the storage unit 51A calculates the gas permeability GTR as necessary information in the following (Equation 1) formula. , (Equation 2), constants and fixed values used in the equations (1) and (Equation 2) are stored.

(Equation 1)
GTR=V×(1/R)×(1/A)×(1/T)×(1/Pdo)×(dPp/dt)
Here, GTR: gas permeability [mol/(m ² ·S·Pa)]
V: Cell volume of lower cell 3 [m ³ ]
R: Gas constant [m ³ ·Pa/(K·mol)]
A: Transmission area (m ² )
T: Test temperature [K]
Pdo: Differential pressure [Pa] at the start of measurement (Pdo=Pho-Pto)
Ph: Atmospheric pressure [Pa] at the time of measurement
Pto: Pressure at measurement start [Pa] in the lower cell 3
Pho: Atmospheric pressure [Pa] at the start of measurement
Pp: Corrected pressure [Pa] of the measured pressure in the lower cell 3
dPp/dt: Change in corrected pressure per unit time [Pa/s]

(Equation 2)
_{Pp n = Pp n-1 +} 1 / (1-α) × (Pt n -Pt n-1)
_{= Pp n-1 + (Pdo} / Pd) × (Pt n -Pt n-1)
Where n=1, 2, 3,... (Sampling count)
Pp: Corrected pressure [Pa] of the measured pressure in the lower cell 3
Pt: Measured pressure in the lower cell 3 [Pa]
Ph: Atmospheric pressure [Pa] at the time of measurement
Pto: Pressure at measurement start [Pa] in the lower cell 3
Pho: Atmospheric pressure [Pa] at the start of measurement
Pd: Differential pressure at the time of measurement (Pd=Ph-Pt)
Pdo: Differential pressure at the start of measurement (Pdo=Pho-Pto)
α: Rate of differential pressure change (α=(Pdo-Pd)/Pdo)

As the required program, the correction amount calculation (differential pressure calculation (Pd = Ph-Pt, Pdo = Pho-Pto), the percentage calculation (Pdo / Pd), difference operation _{(Pt n -Pt n-1)} , corrected The amount calculated (Pdo / Pd) × (Pt n -Pt n-1)), the correction pressure calculating _{(Pp n = Pp n-1} + (Pdo / Pd) × (Pt n -Pt n-1)), the gradient calculation (Correction pressure change calculation per unit time: dPp/dt), gas permeability calculation (GTR), and the like are stored in the storage unit 51A.

The calculation control unit 51B is configured by a CPU (Central Processing Unit), and the calculation control unit 51B, based on the program read from the storage unit 51A, as shown in FIG. The correction pressure calculation unit 62, the gradient calculation unit 63, the gas permeability calculation unit 64, and the like function as the correction amount calculation unit 61. The correction amount calculation unit 61 further includes a differential pressure calculation unit 61A, a ratio calculation unit 61B, and a difference calculation unit 61C. It serves as the correction amount calculation unit 61D.

In order to improve the accuracy of the gas permeability GTR, the processor 51 corrects the pressure (hereinafter, lower cell internal pressure) Pt of the other compartment space 7 in the lower cell 3, and then the gas permeability. Calculate GTR. The gas permeability measuring method according to the embodiment is reflected in the processing of the arithmetic processing device 51, and the processing of the arithmetic processing device 51 will be specifically described together with the gas permeability measuring method.

For the calculation of the gas permeability GTR, the following formula (Equation 3) is used as a general standard calculation formula. In using the formula (3), regarding the change in dP/dt (pressure in the lower cell 3 per unit time) (Pa/s) in the formula (3), the lower cell 3 with respect to the elapsed time is It is obtained by measuring the internal pressure (creating a gas permeation curve) and obtaining the slope (gradient) of the straight line showing the steady state of gas permeation, and substituting it into the equation (3) Degree GTR is derived.
(Equation 3)
GTR=V×(1/R)×(1/A)×(1/T)×(1/Pd)×(dP/dt)
Here, GTR: gas permeability [mol/(m ² ·S·Pa)]
V: Cell volume of lower cell 3 [m ³ ]
R: Gas constant [m ³ ·Pa/(K·mol)]
A: Transmission area (m ² )
T: Test temperature [K]
Pd: Differential pressure at the time of measurement (high pressure side pressure Ph-low pressure side pressure Pt)
dP/dt: Pressure change per unit time [Pa/s]

However, when the pressure in the lower cell 3 with respect to the elapsed time is measured (a gas permeation curve is created), the pressure in the lower cell 3 increases with the lapse of time, and as a result, the atmospheric pressure Ph and the inside of the lower cell 3 are increased. The differential pressure Pd=Ph-Pt decreases. Therefore, the pressure in the lower cell 3 gradually approaches the saturation value (pressure) according to the individual situation as shown in FIG. 5 (see before correction) with the passage of time, and per unit time. The temporal change in the pressure change dP/dt (gradient) in the lower cell 3 tends to monotonically decrease as shown in FIG. 6 (before correction). As a result, under the condition that the differential pressure at the start of measurement is the same, the dP/dt (gradient) in the case where the differential pressure decreases with time in the gas permeability measurement, the differential pressure Pd is a constant value. It tends to be smaller than dP/dt (gradient) in a certain case, and the linearity also decreases, and not only is its identification difficult, but even if the identification is performed, the dP/ dt (gradient) cannot be said to be highly accurate. Further, the atmospheric pressure Ph, which is the pressure inside the upper cell 2, fluctuates due to climate change, difference in measurement location, etc., and thus gives a differential pressure Pd=Ph-Pt (see FIGS. 7 and 8), unit. The pressure change dP/dt (gradient) in the lower cell 3 per time is also influenced by the change in the atmospheric pressure. Therefore, this also lowers the ease of specifying the dP/dt (gradient) and the accuracy of the dP/dt (gradient) obtained by the specification. In addition, in FIGS. 5 to 8, exaggerated display is provided for easy understanding. Furthermore, Pd used in the equation (3) is a differential pressure (variation value) at the time of measurement, and using this Pd to calculate the gas permeability GTR under the equation (3) is a calculation process. Increase the load on the device.

Therefore, in the present embodiment, the arithmetic processing unit 51 corrects the lower cell inner pressure Pt with respect to the elapsed time to obtain the corrected pressure Pp with respect to the elapsed time (creating a gas permeation straight line), and the slope of the straight line portion. From the (gradient), dPp/dt is obtained. This is because an accurate dPp/dt can be derived easily and accurately as described later.

In correcting the pressure Pt in the lower cell 3, the arithmetic processing unit 51 is proportional to the gradient value (gradient value) of the pressure increase in the lower cell 3 to the differential pressure Pd (the gas permeability is proportional to the differential pressure). The increase gradient value of the pressure in the lower cell 3 after correction is corrected (added) to the gradient value of the pressure increase in the lower cell 3 by the change rate (decrease rate) of the differential pressure change. It is supposed to have been done. That is, as shown in FIG. 7, if there is a true pressure (correction pressure) Pp (characteristic line) with respect to the pressure Pt (characteristic line) in the lower cell 3 with respect to the elapsed time, then in the lower cell 3 Since it is considered that the pressure gradient dPt/dt of the pressure Pt becomes smaller than the pressure gradient dPp/dt of the true pressure Pp by the change rate α of the differential pressure change (α×dPt/dt), dPp/dt= The relationship of dPt/dt+α×dPt/dt is established. If this is arranged, it becomes the following (Formula 4) formula.
(Equation 4)
dPp/dt=(1/(1-α))×dPt/dt

On the other hand, the true pressure Pp can be expressed by the following (Equation 5) using the differential amount at the n-th sampling time and the (n-1)th sampling time.
(Equation 5)
_{Pp n = Pp n-1 +} (dPp / dt) × dt

By substituting the equation (4) into the equation (5), the following equation (6) is obtained.
(Equation 6)
_{Pp n = Pp n-1 +} (dPp / dt) × dt
=Ppn _-1 +(1/(1-[alpha]))*(dPt/dt)*dt
_{= Pp n-1 + (1} / (1-α)) × (Pt n -Pt n-1)
_{= Pp n-1 + (Pdo} / Pd) × (Pt n -Pt n-1)

From the above equation (6), corrected pressure (true pressure) Pp _n below the side cell 3 pressure Pt at the measurement time t _n is the corrected pressure Pp _n-1 in the preceding measurement time point t _n-1 be obtained by adding the correction amount, the difference Pt _n as the amount of correction, the lower cell 3 within the pressure Pt _n-1 of the lower cell 3 within the pressure Pt _n and the measurement time t _n-1 of the measurement time point t _n -Pt _n-1 is obtained by multiplying the ratio Pdo/Pd between the measurement start time point and each measurement time point (Pdo/Pd)×(Pt _n -Pt _n-1 ). In this case, as Pd, the average value of t _n time and t _n-1 time can be used. That is, if the Pd at the time t _n and _{Pd n, Pd n = [(} Ph n -Pt n) + (Ph n-1 -Pt n-1)] is / 2.

From the above contents, in the arithmetic processing unit 51, when the pressure information is input from the high pressure side pressure sensor 55 and the low pressure side pressure sensor 18, the correction amount calculation unit 61 causes the respective elements 61A to 61D (see FIG. 4) to operate. The correction amount is derived by performing the processing described above. That is, at each measurement time point, the differential pressure calculation unit 61A calculates the differential pressures Pd=Ph-Pt and Pdo=Pho-Pto at the measurement start time point and each measurement time point, respectively, and the ratio calculation unit 61B determines the measurement time point. In, the ratio Pdo/Pd at each measurement time point is calculated based on the information from the differential pressure calculation unit 61A. Difference calculation section 61C, at each measurement time point, and calculates the difference Pt _n -Pt _n-1 and Pt _n of the respective measurement point and its Pt _n-1 of the measurement point in one before each measurement time point, correct The amount calculation unit 61D corrects the value (Pdo/Pd)×(Pt _n −Pt _n−1 ) obtained by multiplying the ratio Pdo/Pd at each measurement time by the difference Pt _n −Pt _n−1 at each measurement time. Calculate as quantity. The correction pressure calculating unit 62, a corrected pressure Pp _n of the pressure Pt _n in the lower cells 3 of each measurement time point, at each measurement time point in the corrected pressure Pp _n-1 of the measurement point in one before each measurement time point The sum of the correction amounts (Pdo/Pd)×(Pt _n −Pt _n−1 ) is calculated. Specifically, when t ₀ , the correction pressure Pp ₀ =0, when t ₁ , the correction pressure Pp ₁ =(Pd0/Pd)×Pt ₁ , and when t ₂ , the correction pressure Pp ₂ =Pp ₁ +(Pd0/Pd )*(Pt2-Pt1).

Next, in the calculation processing device 51, the gradient calculation unit 63 calculates the correction pressure change (gradient dPp/dt) per unit time using the correction pressure Pp at each measurement time calculated by the correction pressure calculation unit 62, The gas permeability calculating unit 64 calculates the gas permeability GTR with respect to the sample film 5 from the corrected pressure change dPp/dt per unit time calculated by the gradient calculating unit 63 and the above formula (Equation 1).

At this time, in calculating the correction pressure change per unit time (gradient dPp/dt), the correction pressure Pp calculated by the correction pressure calculation unit 62 is used, and the calculation of the Pp is based on the lower side of the differential pressure decrease. Since the decrease in the pressure gradient (dPt/dt) in the cell 3 is eliminated, the rate of change in the pressure difference (α=(Pdo−Pd)/ A value obtained by multiplying the slope dPp/dt when the differential pressure at the start of measurement is maintained is recognized, which is used to derive the equation (4) as described above. Therefore, as the differential pressure change between the upper cell 2 and the lower cell 3, whether the differential pressure change is based on the pressure increase in the lower cell 3 or based on the atmospheric pressure fluctuation (Fig. 7 and FIG. 8), any of them can be understood as a rate of change of the differential pressure change based on the differential pressure Pdo at the start of measurement, and gas permeation under the state where the differential pressure Pdo at the start of measurement is maintained. The correction pressure Pp corresponding to the case where the degree measurement is performed can be obtained. As a result, the gradient dPp/dt according to the sample film 5 under the differential pressure Pdo at the start of measurement is maintained constant regardless of the passage of time, and exhibits high linearity. The unit 63 easily and accurately derives an accurate dPp/dt used in the equation (1).

In addition, the gas permeability calculation unit 64 uses dPp/dt in the formula (1) when it corresponds to the one that maintains the differential pressure Pdo at the start of measurement as the gas permeability measurement, and in the formula (1), The value per unit differential pressure is obtained by using the differential pressure Pdo at the measurement start time, and the method that is suitable for the formula (1) (equivalent value under the differential pressure Pdo at the measurement start time (corrected pressure per unit time) (dPp/dt) is divided by the differential pressure Pdo at the start of measurement). Therefore, it is possible to calculate the gas permeability GTR with a highly accurate value. Moreover, in this case, the measurement start differential pressure Pdo (constant value) is used to obtain the value per unit differential pressure, and the processing load of the arithmetic processing device 51 is reduced.

Such a gas permeability measuring device 1 performs the measurement in the following order. First, as shown in FIG. 3, after the sample film 5 is sandwiched between the upper cell 2 and the lower cell 3, the other side partitioned space 7 in the lower cell 3 is lower than the atmospheric pressure by the vacuum pump 17. The reduced pressure state (predetermined vacuum state) is set. Then, the supply of gas having a predetermined dryness is started from the gas source, and the flow rate of the gas is adjusted by the flow rate adjusting valve 33, whereby the humidity of the gas on the water tank 34 is adjusted. At this time, the humidified gas is continuously supplied to the one-side partitioned space 6 in the upper cell 2, but the supplied humidified gas is exhausted from the atmosphere communication hole 13 and the one-side partitioned space 6 is discharged. In the inside of 6, the measurement gas in the humidified state adjusted by the flow rate adjusting valve 33 exists under the atmospheric pressure.

When the decompressed state of the other divided space 7 in the lower cell 3 becomes a predetermined state and the humidification of the gas reaches a desired relative humidity by the flow rate adjusting valve 33, the valve 16 is closed and the gas permeability of the sample film 5 is reduced. The measurement is started. At the time of measuring the gas permeability, the low-pressure side pressure sensor 18 detects the pressure of the other-side compartment space 7 in the lower cell 3 as the measurement pressure and the high-pressure side pressure sensor 55 in the upper cell 2 at every predetermined measurement timing. The pressure (atmospheric pressure) in the one-side compartment 6 is detected. The both pressure detection information is input to the arithmetic processing unit 51, and the arithmetic processing unit 51 obtains a permeation pressure change (gradient: dP/dt) per unit time based on them, and the permeation pressure change per unit time. Based on the above, the gas permeability GTR is obtained.

In this case, when calculating the permeation pressure change (gradient: dP/dt) per unit time, the arithmetic processing unit 51 determines the permeation pressure at each measurement time point as the correction pressure obtained by the correction process for the measurement pressure Pt at each measurement time point. In order to obtain the correction pressure Pp using Pp, by using the change rate (Pdo-Pd)/Pdo of the differential pressure change Pdo-Pd at each measurement based on the differential pressure Pdo at the start of measurement, The measurement pressure Pt at the time of measurement is corrected to the value Pp under the differential pressure Pdo at the start of measurement. As a result, as described above, as the permeation pressure change per unit time, the corrected pressure change per unit time dPp/dt that is easy to specify and has high accuracy can be used, and further, the measurement start differential pressure Pdo can be used. By using this, the value per unit pressure difference can be made accurate, and the gas permeability GTR becomes highly accurate.

When the gas permeability is measured for a predetermined time, the supply of gas from the gas source is stopped, the valve 16 and the like are opened, and the vacuum pump 17 exhausts the residual gas. When the residual gas is exhausted in the gas permeability measuring device 1 by this exhaust, the gas permeability measurement ends.

Therefore, in the present embodiment, the lower cell at each measurement point is considered in consideration of the decrease in the differential pressure between the inner pressure of the upper cell 2 and the inner pressure of the lower cell 3 as the pressure in the lower cell 3 increases. Since the internal pressure Pt is corrected to the value Pp under the differential pressure at the start of measurement, the corrected pressure change dPp/dt (gradient) per unit time can be specified easily and accurately, and this unit The value per unit differential pressure can be calculated using the differential pressure Pdo at the start of measurement for the corrected pressure change dPt/dt per time, and the gas permeability GTR can be set to a value with higher accuracy.

Also, the fluctuation of the atmospheric pressure can be grasped as the rate of change of the differential pressure Pd based on the differential pressure Pdo at the time of measurement as in the case of the pressure Pt increase in the lower cell 3, and the one side partition of the upper cell Even in the structure in which the space 6 is open to the atmosphere, the gas permeability GTR can be set to a value with high accuracy.

Further, in such a gas permeability measuring apparatus 1, the pressure in the one-side compartment 6 is set to atmospheric pressure, and the differential pressure at the start of measurement is adjusted only by adjusting the pressure in the other-side compartment 7. Therefore, it is not necessary to provide a piping for vacuuming from the vacuum pump 17 to the one-side compartment space 6 in the upper cell 2. Further, since the water tank 34 is housed inside the lower cell 3, the internal space of the lower cell 3 can be effectively used. Thereby, the gas permeability measuring device 1 can be miniaturized as much as possible. Moreover, in this case, since the water tank 34 is built in the lower cell 3 which is not tilted, not in the upper cell 2 which is tilted up and down, the shaking of the water in the water tank 34 due to the tilting movement of the upper cell 2 and the like are prevented. Since it is not necessary to consider it, it is possible to prevent the gas permeability measurement from being hindered. Furthermore, the differential pressure at the start of the measurement can be adjusted only by adjusting the pressure (vacuum evacuation) of the other compartment space 7, and the preparation time before measuring the gas permeability can be shortened.

Furthermore, even if the water tank 34 as a humidifier is built in the lower cell 3, the connection pipe 41 (gas supply path 12) is at least in the connection pipe 24 between the water tank 34 and the upper cell 2, It is accommodated while forming an annular space 42 between the connecting pipe 24 and the connecting pipe 41, and when supplying the measurement gas from the lower cell 3 to the one-side compartment space 6 in the upper cell 2, The change in the humidity state due to the temperature can be suppressed by the circulating water flowing through the annular space 42 in the connecting pipe 24. Therefore, it is possible to accurately measure the permeability of the measurement gas in a desired humidified state (relative humidity).

Although the embodiments have been described above, the present invention includes the following modes.
(1) When the humidifying gas is not generated as the measurement gas, the inside of the water tank 34, which is the expansion space, is kept in the space without storing water.
(2) The water tank 34, which is an expansion space, is built in the upper cell 2.
(3) The gas should include not only a dry gas but also a humidifying gas such as steam gas, nitrogen gas containing steam, and oxygen gas.

The present invention relates to a case where the differential pressure Pd between the one-side compartment space 6 on one side with respect to the sample film 5 and the other-side compartment space 7 on the other side with respect to the sample film 5 changes with the passage of time. Even if it exists, it can be used to improve the accuracy of the gas permeability GTR.

1 Gas permeability measuring device 2 Upper cell (one cell)
3 Lower cell (other cell)
5 Sample Membrane 6 One Side Partition Space 7 Other Side Partition Space 12 Gas Supply Channel 13 Atmosphere Communication Hole 18 Low Pressure Side Pressure Sensor 34 Water Tank (Expansion Space)
55 High-pressure side pressure sensor Pp Corrected pressure Ph Upper cell pressure (pressure in one side compartment)
Pt lower cell pressure (pressure in the other compartment space, measured pressure)
Pdo differential pressure at measurement start Pd differential pressure at measurement (Pdo-Pd)/Pdo Change rate of differential pressure change at each measurement based on differential pressure at measurement start Pdo/Pd relative to differential pressure at each measurement time the difference between the measured pressure of the measurement points in previous one measurement pressure and respective measurement points in the ratio Pt _n -Pt _n-1 time each measurement of a measurement start time difference pressure

Claims (9)

On one side of the sample film with reference to the sample film, one side compartment space in which a measurement gas is supplied is secured, and on the other side of the sample film, a pressure lower than the pressure of the one side compartment space. Calculating the gas permeability by securing the other-side compartment space in the state, measuring the pressure of the other-side compartment space at each predetermined measurement time, and using the measured pressure at each measurement time point. In the gas permeability measuring method for obtaining the change of permeation pressure per unit time used for
As the permeation pressure at each measurement time point, a correction pressure obtained by a correction process for the measurement pressure at each measurement time point is used,
As a correction process for obtaining the corrected pressure, the differential pressure between the pressure in the one side compartment space and the pressure in the other side compartment space is detected, and the differential pressure at each measurement based on the differential pressure at the start of measurement. By using the change rate of change, the measurement pressure at each measurement time is corrected to a value under the differential pressure at the start of measurement,
A method for measuring gas permeability, which is characterized in that In claim 1,
As the correction pressure for each measurement time point, for each measurement time point, a value obtained by adding a correction amount to the correction pressure at the measurement time point immediately before each measurement time point is used.
As the correction amount for each measurement time point, the ratio of the differential pressure at the start of measurement to the differential pressure at each measurement time point is defined as the measured pressure at each measurement time point and the measured pressure at the measurement time point immediately before each measurement time point. Use the product of the difference,
A method for measuring gas permeability, which is characterized in that In claim 1 or 2,
The one-side compartment space is open to the atmosphere,
A method for measuring gas permeability, which is characterized in that In claim 3,
The one-side compartment is supplied with a measurement gas containing water vapor,
A method for measuring gas permeability, which is characterized in that A pair of cells for sandwiching the sample film is provided, and a one-side compartment space in which the measurement gas is supplied is formed between one of the pair of cells and the sample film. , Between the other cell of the pair of cells and the sample film, the other side partitioned space whose pressure is lower than the pressure of the one side partitioned space is formed, with respect to the other side partitioned space. In a gas permeability measuring device associated with a low pressure side pressure sensor for detecting the pressure of the other compartment space at predetermined time intervals,
A high pressure side pressure sensor for detecting the pressure of the one side compartment space,
Based on the detection information from the high-pressure side pressure sensor and the detection information from the low-pressure side pressure sensor, for the measurement start time point and each measurement time point, between the pressure of the one side compartment space and the pressure of the side compartment space The differential pressure is calculated respectively, and based on the calculated information, the ratio of the differential pressure at the time of measurement to the differential pressure at the time of measurement at each measurement time point is calculated, and the measured pressure at each measurement time point and the measurement time point immediately before each measurement time point are calculated. A correction amount calculation unit that calculates a difference between the measured pressure and the ratio and the difference is calculated as a correction amount.
The correction pressure of the measurement pressure at each measurement time point detected by the low-pressure side pressure sensor is used to calculate the gas permeability, and the correction amount calculation unit is added to the correction pressure at the measurement time point immediately before each measurement time point. A correction pressure calculation unit which is calculated by adding the correction amounts at the respective measurement points calculated by
Is equipped with,
A gas permeability measuring device characterized in that In claim 5,
In the one of the cells, a communication hole that connects the one-side compartment space and the atmosphere is formed.
A gas permeability measuring device characterized in that In claim 6,
With respect to the one side compartment space in the one cell, a gas supply path for supplying the measurement gas is connected,
In the gas supply path, an expansion space is formed by expanding the gas supply path in the middle thereof.
A gas permeability measuring device characterized in that In claim 7,
The expansion space constitutes a water tank for accumulating water in a state where the flow of the measurement gas is secured,
A gas permeability measuring device characterized in that In claim 8,
The expansion space is contained in any one of the pair of cells,
A gas permeability measuring device characterized in that

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