JPS62119433A - Hydrogen transmission coefficient measuring apparatus for film - Google Patents

Abstract

PURPOSE:To achieve handy, quick measurement at a high accuracy without use of costly hydrogen concentration analyzer, by providing a gas electrode type hydrogen sensor on the side of a measuring chamber divided from a gas chamber containing fixed concentration of hydrogen by a sample film. CONSTITUTION:A measuring chamber 3 is divided from a gas chamber 1 by sample film 5 fixed airtight in the perimeter with flange 7 having a packing 6. As a hydrogen gas flows into the gas chamber 1, with a passage of time, the concentration C of hydrogen in the measuring chamber 3 rises gradually by hydrogen passing through the sample film 5, in response an output voltage E of a gas electrode type hydrogen sensor 8 is inputted into a hydrogen concentration measuring circuit 11 and secular changes in the concentration of hydrogen is recorded with recorder 12. On the other hand, a hydrogen transmission coefficient measuring section 20 computes the hydrogen transmission coefficient P of the sample film from the transmission time of hydrogen gas, capacity of the measuring chamber 3, the thickness of supplied film and the like to be shown on a display unit 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to a device for measuring the gas permeability coefficient of a polymer film, metal thin film, etc., particularly the hydrogen gas permeation coefficient.

[Prior art and its problems]

In recent years, with the development of polymer chemistry, various types of polymer films have been produced, and as the uniformity of mechanical and thermal properties and various functionalities has improved, they have been used for applications that take advantage of various functionalities. . In particular, one of the functions that polymer films have is the ability to concentrate and separate gases using gas permeability.

Among them, research and development of hydrogen concentration and separation technology is being actively conducted along with oxygen concentration and separation technology. The most basic step in developing hydrogen concentration and separation technology is the measurement of the hydrogen permeability coefficient of a film, and there is a need for the development of an apparatus that can easily and quickly determine the permeability coefficient.

FIG. 3 is an explanatory diagram of the principle of a measuring device showing an example of the prior art. sb, the sample film 5 is fixed between the gas chamber 1 and the measuring chamber 5, and the measuring chamber 3 is evacuated in advance or nitrogen or Fill with inert gas such as argon. After that, hydrogen gas of a certain concentration is flowed into the gas chamber 1 through the cocks 2A and 2B, and after a certain period of time, the gas in the measurement chamber B containing hydrogen that has permeated through the test film 5 is collected and analyzed by gas chromatography or mass spectrometry. Measure hydrogen gas concentration.

In this case, the following equation holds between the hydrogen concentration C in the sealed measurement chamber 6, the hydrogen permeability coefficient P, and the time t.

Here, Co: hydrogen concentration in the gas passed through gas chamber 1 A: permeation area of the film vO: volume of measurement chamber 6 d: thickness of film It is a diagram in which the horizontal axis represents time t, and the vertical axis represents hydrogen concentration C in the measurement chamber 6.
This is an illustration of the figure. Therefore, for a certain time t
If the hydrogen concentration C in measurement chamber B is measured at Reeds, generally the cock 4 connected to the measurement chamber B
A method is used to collect gas by attaching a gas sampler to the pipe outside A or 4B.

In this method, when the volume of the measurement chamber 6 is reduced in order to speed up the measurement, the volume of the gas sampler and the connection part and the volume of the measurement chamber 6 vO become the same volume or vO
It is also possible for O to become smaller. In this case, errors due to sampling are likely to occur, resulting in a problem of poor measurement accuracy.

In order to eliminate these drawbacks, a method has been considered in which the hydrogen that has permeated into the measurement chamber 6 is guided directly to a gas colomatograph or mass spectrometer using a carrier gas. Although this method can reduce the problem of errors caused by sampling the analysis gas, it requires the preparation of another expensive measurement means such as a gas chromatograph or mass spectrometer for measurement, and the time required for measurement is Equipment adjustment, column selection, temperature,
There is a problem in that very time-consuming operations such as sensitivity adjustment, standard gas calibration, and warming-up must be performed in advance, and measurement preparation requires a long time. Furthermore, the biggest problem is that only one measurement is required.
The problem is that it is possible to measure only the hydrogen concentration at one point on the characteristic curve shown in the figure.

To accurately measure the hydrogen permeability coefficient, the concentration C in gas chamber 1 is
o It is inappropriate if the measured concentration C is too small or too close to (the saturated concentration of the measurement chamber 6), and it is appropriate that the measured concentration range is 30% to 90% with respect to the saturated concentration Co. . However, when measuring the hydrogen concentration of the test film 5 with an unknown permeability coefficient, it is not always possible to measure the concentration within the optimum concentration range by sampling at an appropriate time and measuring the concentration. Therefore, there is a risk of large errors occurring. Therefore, if it is determined that it is appropriate after the measurement, the measurement must be taken again, which requires extra time. As described above, in the conventional method, the measuring device itself is expensive, there are many factors that cause measurement errors, and K to perform accurate measurement requires a lot of time.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide an apparatus that can easily and accurately measure the hydrogen permeability coefficient of a test film in a short time.

[Key points of the invention]

The present invention focuses on the fact that a gas electrode type (electrochemical) hydrogen sensor (hereinafter simply referred to as a hydrogen sensor) outputs a voltage corresponding to the hydrogen concentration even at room temperature. A hydrogen sensor is installed in the measurement chamber side that is separated from the gas chamber containing hydrogen, and the hydrogen concentration measuring section installed on the output circuit side of the hydrogen sensor measures and records the change in hydrogen concentration over time, and the output of the hydrogen concentration measuring section is An example of a configuration including a hydrogen permeability coefficient measurement section that receives the signal and the output signal of the timer and condition setting circuit, calculates the hydrogen permeability coefficient of the test film based on a predetermined formula, and displays the calculation result. Furthermore, the hydrogen permeability coefficient of a test film can be easily, quickly, and accurately measured and displayed in the optimum hydrogen concentration range without using an expensive hydrogen concentration analyzer.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention. In the figure, 1 is a gas chamber in which hydrogen gas of a certain concentration is sealed or circulated, 6 is a measurement chamber, and the compartment is a polymer film or metal foil that is airtightly fixed around the 7 flange 7 having a backing 6. It is divided by the test film 5.

8 is a hydrogen sensor housed in the measurement chamber B, for example, a hydrogen electrode-metal/metal salt (metal oxide) electrode type hydrogen sensor (Japanese Patent Application Laid-Open No. 57-14
A gas electrode type (electrochemical) hydrogen sensor such as a hydrogen electrode-hydrogen electrode type hydrogen sensor (see Japanese Patent Laid-Open No. 57-145528) can be used.

Sensors that can detect hydrogen gas include catalytic combustion gas sensors and semiconductor gas sensors, but these sensors bring a catalyst electrode into contact with hydrogen in the presence of air to cause a combustion or oxidation reaction. However, since it requires the presence of oxygen and generates high temperatures, it is unsuitable for application to this device.

In the hydrogen concentration detection section configured as described above, the following relationship holds between the output voltage E of the hydrogen sensor 8 and the hydrogen concentration C in the measurement chamber 6.

T EwEo 1 - Σ Ding = ifLC・・・・・・・・・・(2
) However, EO is the reference voltage determined for each type of reference electrode of the hydrogen sensor, R is the gas constant, T is the absolute temperature, and F is 7
The reference voltage is set by flowing hydrogen gas with a known concentration of Co into the measurement chamber 6 and measuring the hydrogen gas temperature. It can be easily determined by measuring the output voltage E of -8. The measurement chamber 3 housing the hydrogen sensor 8 whose relationship between the hydrogen concentration C and the output voltage E has been calibrated in this way is brought into a vacuum state or filled with an inert gas, and is then turned off by the cock 4A.

4B is closed. In addition, depending on the state of the measurement chamber 3, hydrogen gas with a known concentration Co (pressure) or an inert gas such as nitrogen or argon containing hydrogen with a known concentration CO is supplied to the gas chamber IK via cocks 2A and 2B. be swept away.

However, if the volume of the gas chamber 1 is sufficiently larger than the volume vO of the measurement chamber 3 (for example, 100 times or more), the gas chamber 1 may be filled with gas having a hydrogen concentration of CO. As time t elapses in this state, the hydrogen concentration C in the measurement chamber 5 gradually increases due to the hydrogen that has passed through the sample film 5, and correspondingly, the output voltage E of the output terminal 8AK of the hydrogen sensor 8 increases. occurs.

10 is a hydrogen concentration measuring section provided on the output side of the hydrogen sensor 8, which converts the output voltage E of the hydrogen sensor 8 into the hydrogen concentration C.
Changes in the hydrogen concentration over time are recorded on the recorder 12 via the hydrogen concentration measurement circuit 11 which converts the hydrogen concentration into output. 20 is a hydrogen permeability coefficient measurement unit of the sample film 5, a timer 21 for measuring the permeation time t of hydrogen gas, (the hydrogen concentration C0 in the gas chamber 1 necessary to obtain the hydrogen permeability coefficient C in equation 11, the sample A condition setting circuit 22 for inputting predetermined constants such as the effective permeation area A of the film 5, the volume vO2 of the measurement chamber 3, the thickness d of the test film, and the hydrogen concentration measuring section 10.
The timer 219 receives the output signals from the condition setting circuit 22 and calculates the hydrogen permeability coefficient P of the test film based on equation (1).
It is composed of an arithmetic circuit 26 that calculates and outputs the arithmetic circuit 26, and a display 24 that displays the arithmetic results of the arithmetic circuit 23. Activate the switch built into the timer 9 after reaching a predetermined level within the optimal measurement range of 60% to 90% of the saturation value Go (hydrogen concentration CoK on the gas chamber 1 side is equal). After one or several calculations, the hydrogen permeability coefficient P of the test film can be measured with high accuracy. Furthermore, it is also possible to continuously operate the arithmetic circuit 23 to obtain the temporal change characteristics of the hydrogen permeability coefficient.

Figure 2 is a side cross-sectional view of the main parts of an example of a hydrogen sensor according to an embodiment, and shows an example of a hydrogen electrode-metal/metal salt (metal oxide) electrode type gas electrode electrochemical hydrogen sensor. It is something that In the figure, reference numeral 31 denotes a container made of an insulating material having seven lunges, a hydrogen electrode 62 is placed on the side that comes into contact with the gas in the measurement chamber 6, and a silver electrode, for example,
A counter electrode 36 such as a silver chloride electrode or a silver/silver phosphate electrode, and a porous layer partitioned between the two electrodes 32 and 33 by a partition wall 34 that does not allow silver ions to pass through, each having a porosity of 50% or more. The hydrogen sensor main part consisting of IJ socks 5 and 66 and their respective laminates is housed in a plate impregnated with an electrolytic solution such as a hydrochloric acid aqueous solution or a cynic acid aqueous solution, and an electrical terminal 37 is connected from the counter electrode 33 side. However, the hydrogen electrode 32
From the side, an electrical terminal 69 is provided on a conductive metal fitting 58 that also serves as a suppression plate. Further, the hydrogen electrode 52 is an electrode made of graphite with platinum black as a catalyst, the counter electrode 63 is a molten or silver-plated electrode, and the matrix 36 is an electrolytic solution containing saturated silver chloride or silver phosphate. is impregnated with
The partition wall 64 is configured so that silver ions do not move toward the matrix 55 and inhibit the conductivity of the matrix.

When the hydrogen sensor 8 formed as described above is installed in the measurement chamber 3, as the hydrogen concentration C in the measurement chamber 6 increases, the hydrogen is ionized by the hydrogen electrode 32 and is dissolved in the electrolyte in the matrix 65. The potential difference between the electrodes 52 and 66 changes. In this way, a small change in the hydrogen concentration in the measurement chamber 6 can be detected as a change in the voltage signal using the small hydrogen sensor.

Note that the counter electrode 66 is not limited to the metal-metal salt (metal oxide) electrode described above; for example, the counter electrode 32
It may be constructed with a pair of hydrogen electrodes similar to the above, or an electrolyte bath may be used in place of the matrices 35 and 36.

〔Effect of the invention〕

As described above, the present invention provides a hydrogen sensor in the form of a gas electrode on the measurement chamber side of the permeated hydrogen gas of the test film, which is separated from the gas chamber containing gas with a known hydrogen concentration in the test film. The hydrogen concentration measurement unit placed on the output side continuously measures and records the hydrogen concentration, and is equipped with a trap, timer, and condition setting circuit, and receives these output signals and hydrogen concentration signals and calculates the hydrogen concentration based on a predetermined formula. It was configured to include a hydrogen permeability coefficient measuring section that calculates and displays the hydrogen permeability coefficient of the test film. As a result, the measurement error of hydrogen concentration due to sampling of analysis gas, which was a problem with conventional technology,
Problems such as long measurement preparation time and measurement repeat time are eliminated, and the hydrogen concentration in the measurement chamber can be continuously measured and recorded with high accuracy without using special analyzers. We have developed a film hydrogen permeability coefficient measuring device that can easily, quickly, and accurately measure the hydrogen permeability coefficient of a sample film by operating the hydrogen permeation coefficient measuring section at the point when the concentration reaches the optimal measurement concentration range. It can be provided economically.

In addition, it is possible to easily and continuously measure and record the hydrogen concentration in a d:11 fixed chamber, making it ideal for polymer films and metal films with a wide range of permeability coefficients, or for measurement chambers with a permeation area suitable for them. Not only can you easily know the measurement concentration range, but also the calculation conditions related to the above conditions can be stored in the condition setting circuit and timer. It has the advantage of being well measurable.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing a device according to an embodiment of the present invention, Fig. 2 is a sectional side view of essential parts showing an example of a hydrogen sensor according to an embodiment, and Fig. 3 is a principle explanation showing an example of a conventional device. FIG. 4 is a characteristic diagram of the change in hydrogen concentration over time in the measurement chamber. 1... Gas chamber, filter... measurement chamber, 5... test film, 8... gas electrode type hydrogen sensor (hydrogen sensor)
, 10... Hydrogen concentration measuring section, 11... Hydrogen concentration measuring circuit 12... Recorder, 20... Hydrogen permeability coefficient measuring section, 21... Timer, 22... Condition setting circuit, 23
... Arithmetic circuit, 24 ... Display device, 32 ... Gas electrode, 33 ... Counter electrode, 34 ... Partition wall, 35.36.
··matrix. Figure 2 Figure 3 Figure 4 Time ″-1

Claims (1)

[Claims] 1) A gas chamber that is partitioned by a test film and stores gas containing a certain concentration of hydrogen, a measurement chamber for hydrogen that has passed through the test film, a gas electrode type hydrogen sensor placed in this measurement chamber, and a gas chamber that stores gas containing a certain concentration of hydrogen. It is equipped with a hydrogen concentration measuring section that converts the output voltage signal of the electrode type hydrogen sensor into a hydrogen concentration and outputs it, a timer and a condition setting circuit, and receives each output signal and the output signal of the hydrogen concentration measuring section based on a predetermined formula. 1. A hydrogen permeability coefficient measurement device for a film, comprising: a hydrogen permeation coefficient measurement unit that determines the hydrogen permeation coefficient of a test film and displays the calculation result.