JP2001235417A - Pore size distribution measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide pore size distribution measuring instrument capable of accurately measuring the sizes of pores ranging from a meso-pore to a micropore provided in an object to be inspected and the distribution state of them without using an expensive apparatus, and collapsing the shape of the object to be inspected. SOLUTION: The pore size distribution measuring instrument is equipped with a holding means 3 for holding the object 5 to be inspected having pores so that one ends of the pores communicate with a primary chamber 2 and the other ends of them communicate with a secondary chamber 3, an inspection gas supply means 7 for supplying inspection gas mixed with non-condensible gas and condensible gas to primary chamber 2, the regulation means 14, 16 provided in the inspection gas supply means 7 and regulating the mixing ratio of the non-condensible and condensible gases supplied to the primary chamber 2, and the measuring means 40 connected to the secondary chamber 3 and measuring the amount of the inspection gas passed through the object 5 to be inspected with the elapse of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pore size distribution measuring device for measuring the size of fine pores such as a filter, a membrane, a hollow fiber and the like and the distribution thereof.

[0002]

2. Description of the Related Art As conventional means for measuring the diameter of fine pores such as a filter and the distribution thereof, there are known, for example, a nitrogen adsorption method and a mercury intrusion method in which a specimen is crushed and measured as a powder sample. ing.

[0003] In addition, a dry-wet flow method which is an improvement of the bubble point method, which is a transmission method, is known as a method capable of measuring an object in its original form.
M is standardized, and measuring devices are also commercially available.

[0004] Further, as a capillary condensation method, a condensable gas such as nitrogen gas is caused to flow on the upstream side of the subject, and oxygen is caused to flow on the downstream side of the subject, and the pore diameter of the subject is measured from the diffusion rate. Some have tried to do so.

[0005]

However, according to the nitrogen adsorption method or the mercury intrusion method, the specimen must be crushed into a powder sample, and the pore diameter which does not contribute to the permeation, for example, the diameter of the support hole or the diameter of the penetrating hole. It is difficult to accurately measure the diameter of only the pores related to the original function as a filter, etc.

In the dry-wet flow method, the limit of the measurable pore diameter is about 50 nm (50 × 10 ⁻⁹ m), and a mesopore (2 to 50 n) exhibiting separation selectivity as a filter.
The measurement in the microbore (2 nm or less) region cannot be performed from m).
Therefore, it is desired to realize a pore size distribution measuring apparatus by a transmission method that can accurately measure a region from a mesopore to a microbore without changing the shape of the subject.

[0007] In the above-mentioned measuring means by the capillary condensation method, an expensive apparatus such as gas chromatography must be used, and the mechanism of permeation in the pores has not been clearly elucidated. Is difficult.

The present invention has been made in consideration of the above-mentioned problems of the conventional technology, and has been developed without using an expensive apparatus and without losing the shape of a subject. It is an object of the present invention to provide a pore diameter distribution measuring device capable of accurately measuring the diameter of a pore and its distribution state.

In addition, it is possible to reduce and stabilize fluctuations in the amount and ratio of condensable gas in the test gas passing through the subject and fluctuations in temperature due to the fluctuations.
It is another object of the present invention to provide a pore size distribution measuring device that can be adjusted accurately.

[0010]

According to the present invention, the above-mentioned problem is solved as follows. (1) holding means for holding a subject, such that one end of the pore communicates with the primary chamber and the other end of the pore communicates with the secondary chamber, and Test gas supply means for supplying a test gas, which is a mixture of a non-condensable gas and a condensable gas, to the next chamber; and a non-condensable gas and a condensate provided in the test gas supply means and supplied to the primary chamber. And a measuring means connected to the secondary chamber and measuring the amount of the test gas that has passed through the subject over time.

(2) In the above item (1), it is assumed that the test gas supply means has a non-condensable gas supply system and a bypass system branched from the non-condensable gas supply system. A gas supply means is provided.

(3) In the above item (2), the means for supplying the condensable gas contains a liquid which becomes a condensable gas by vaporization, and a non-condensable gas passes through the liquid. It has a bubbler in which the condensable gas is mixed into the condensable gas.

(4) In the above item (3), the condensable gas supply means has a plurality of bubblers connected in series to a bypass system path.

(5) In the above item (2), the supply means for the condensable gas supplies the liquid which becomes the condensable gas by vaporization to the bypass system by a small amount and the pump in the bypass system. And an evaporator for evaporating the liquid.

(6) In any one of the above items (1) to (5), the test gas supply means is provided with a temperature maintaining means for maintaining the temperature of the test gas at a set temperature.

(7) In any one of the above items (1) to (6), a pressure adjusting means for maintaining the secondary chamber at substantially the atmospheric pressure and maintaining the primary chamber at a value higher than the atmospheric pressure is provided.

(8) In any one of the above items (1) to (7), the non-condensable gas is nitrogen and the condensable gas is steam.

[0018]

An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows the appearance of the measuring device. This measuring device has an upper case (A) with a door (A1).
And the lower case (B). In the upper case (A),
A main body (1) and a heat bath (34) described later are provided, and other piping systems described later, a nitrogen gas source (10) and a water source (28) are provided in the lower case (B). . Control means (not shown) are provided inside the upper case (A) and the lower case (B), respectively, and these are connected to a computer (D) via a cable (C), and the computer (D) Is controlled by the

FIG. 2 is a view schematically showing a schematic configuration of a main body of the measuring apparatus and a piping system. A sealed chamber (2), which is a primary chamber, is formed inside the main body (1), and a cylindrical holder () that protrudes horizontally into the chamber (2) is provided on the right end wall of the main body (1). The base end of 3) is detachably mounted with a cap 4. The holder (3) serves as holding means for the subject (5), and the inside thereof is a secondary chamber (not shown).

In this example, the subject (5) has numerous pores.
(Not shown) is a cylindrical filter formed radially, and one end of a pore thereof is a primary chamber (2).
And the other end of the pore communicates with the inside of the holder (3), which is a secondary chamber, so that one end is
At the tip of (3), it is slightly fitted and held so as to maintain airtightness. The other end of the subject (5) is a closing member
(6) It is closed to keep the airtight.

The holder (3) is appropriately replaced according to the shape of the subject (5). For example, when the subject (5) is a flat membrane, as shown in FIG. 3, a cylindrical holder having an enlarged diameter step (3a ') at the tip end is used.
(3 '), a flat membrane-shaped subject (5) is attached to the opening end of the enlarged diameter step (3a') in the same manner as the drum skinning, and the periphery thereof is appropriately sealed. Is good.

A test gas supply pipe (7) and a surplus gas discharge pipe (8) are connected to the chamber (2), and a passing gas discharge pipe (9) is connected to the holder (3).

A mixed gas of a non-condensable gas and a condensable gas is supplied to the test gas supply pipe (7). As the non-condensable gas, an inert gas such as a nitrogen gas, an argon gas, and a helium gas can be used. Here, a nitrogen gas is used. As the condensable gas, steam, ethanol, carbon tetrachloride, hexane and the like can be used,
Here, steam is used.

A nitrogen gas source (10) is connected to the inspection gas supply pipe (7).
Is connected to the main supply pipe (11), and a bypass pipe (12) is connected to the main supply pipe (11).

On the nitrogen gas source (10) side of the connection portion of the bypass pipe (12) in the main supply pipe (11), the main supply pipe (11), and furthermore, the bypass pipe (12) and the chamber (2) are connected. A regulator (13) is provided as pressure adjusting means for maintaining the pressure slightly higher than the atmospheric pressure. The pressure in the chamber (2) is accurately adjusted by an automatic pressure controller (36) described later.

In the part of the main supply pipe (11) parallel to the bypass pipe (12), a flow controller (14) and one solenoid valve (1) are provided.
5) is provided. On the upstream side of the bypass pipe (12),
A flow controller (16) is provided, and two solenoid valves (17) and (18) are provided downstream thereof. The non-condensable gas and the condensable gas supplied to the chamber (2) by the flow controllers (14) (16), the solenoid valves (15) (17) (18), the solenoid valve (26) described later, and the like. And an adjusting means for adjusting the mixing ratio with.

Two solenoid valves (17) in the bypass pipe (12)
Solenoid valves (17) (1) are provided on the upstream and downstream sides of (18), respectively.
The number corresponding to the number 8), that is, here, the inlet pipe (21) and the outlet pipe (22) of the two bubblers (19) and (20) are connected respectively. The bubblers (19) and (20) serve as a means for supplying condensable gas.

Each inlet pipe (21) is provided with a solenoid valve (23), and the lower end thereof is provided in a closed vessel (24) in each bubbler (19) (20).
It is open to a liquid contained in the liquid, which becomes a condensable gas by vaporization, that is, water (25).

Each outlet pipe (22) is provided with a solenoid valve (26), and its lower end is opened to a space above the level of water (25) in each closed vessel (24).

(27) is a water supply pipe connected to the water source (28),
By opening an electromagnetic valve (29) provided at the end connected to the closed vessel (24) of each of the bubblers (19) and (20), water can be supplied to each closed vessel (24).

Each of the solenoid valves (29) is opened when the water level reaches a predetermined lower limit position by a limit switch (30) for detecting the water level in each closed container (24), and is also moved to the upper limit position. The valve is controlled to close when it reaches.

A drain pipe (32) having an electromagnetic valve (31) is connected to the bottom of each closed vessel (24). A temperature sensor (33) for detecting the temperature of water (24) is provided in each closed container (24).
Are arranged.

The above-mentioned two bubblers (19) and (20), the main supply pipe
(11), a bypass pipe (12) and the like are provided in a heat bath (34) which is a kind of temperature maintaining means for maintaining a temperature at a preset temperature of, for example, about 40 ° C., and a test gas supply pipe (7 ) To keep the temperature of the test gas supplied to the chamber (2) constant.

During normal operation of the device, the solenoid valves (17) (18)
(31) (32) is closed, the solenoid valves (15), (23) and (26) are opened, and two bubblers (19) and (20) are connected in series to the bypass pipe (12). And keep it.

A trap (35) for removing steam, an automatic pressure controller (36), and a solenoid valve are provided in the excess gas discharge pipe (8).
(37) are sequentially provided, and the downstream end thereof is connected to the exhaust port (38).

The passing gas discharge pipe (9) has the trap
A trap (39) similar to (35) and a flow meter (4) which is a measuring means for measuring the amount of test gas passing through the subject (5) with time.
0) and an electromagnetic valve (41) are sequentially provided, and the downstream end thereof is connected to an exhaust port (38) together with an excess gas discharge pipe (8), and is released to the atmospheric pressure. The drain ports of both traps (35) and (39) are connected to the above-mentioned drain pipe (32) via solenoid valves (42) and (43).

A thermo-hygrometer (RH) for detecting temperature and humidity is provided in the main body (1). In addition, besides this,
The body (1) and the passing gas discharge pipe (9) extending to the right in FIG. 1 therefrom are also provided with means for keeping the temperature and pressure constant and sensors for detecting them. , For simplicity of description, illustration and detailed description are omitted.

According to this embodiment, the flow controller
(14) According to (16), the amount of dry nitrogen gas flowing through the main supply pipe (11) and the amount of moist nitrogen gas flowing through the bypass pipe (12) are adjusted to supply them to the test gas. The flow rate of nitrogen gas supplied from the pipe (7) to the chamber (2) of the main body (1), passed through the subject (5) in the centripetal direction, and flowed out of the holder (3) to the passing gas discharge pipe (9). Is measured over time by a flow meter (40), and the measured data is input to a computer (D).
Compared with the comparison data of the known so-called Kelvin diameter (Kelvin diameter) and the cumulative dimensionless transmission coefficient, the subject (5)
It is possible to know how many specific diameters in the range of 0.5 to 30 nm (10 ^-9 m) exist.

The principle of measurement is based on the fact that condensable gas is capillary-condensed in fine pores and blocks the permeation of non-condensable gas. Specifically, a test gas that is a mixture of a condensable gas and a non-condensable gas
When supplied to (5), the capillary condenses in the small diameter pores even in a state where the relative pressure of the condensable gas is low, thereby preventing the permeation of the non-condensable gas. On the other hand, in the case of large-diameter pores, a higher relative pressure of the condensable gas is required to prevent permeation of the non-condensable gas by capillary condensation.

Based on this principle, the permeation count of the non-condensable gas is measured while changing the partial pressure of the condensable gas, that is, the ratio of the condensable gas to the non-condensable gas.
It is possible to measure the size of the pores and the distribution thereof. If there is a sample whose pore size and its distribution are already known, the sample is used as a master and applied to this measuring device, and the difference between the measured value and the known value is used as a correction value for other measured values. May be corrected.

In this embodiment, the interior of the holder (3), which is the secondary chamber, is released to the atmospheric pressure through the passing gas discharge pipe (9), and the chamber (2), which is the primary chamber, is opened.
Is maintained at a pressure slightly higher than the atmospheric pressure. In principle, the pressure in the primary chamber only needs to be higher than the pressure in the secondary chamber. May be maintained at about atmospheric pressure, and the pressure in the secondary chamber may be reduced below atmospheric pressure. However, if the secondary chamber side is released to the atmospheric pressure as in the above embodiment, the condensable gas condensed by the capillary vaporizes again as in the case where the secondary chamber is depressurized, and the measurement accuracy deteriorates. It is possible to eliminate the possibility of causing the measurement and the like, and to improve the measurement accuracy.

In this embodiment, however, a plurality of, in this example, two bubblers (19) (20) are provided in the bypass pipe (12).
Are connected in series, the humidity of the nitrogen gas supplied to the downstream end of the bypass pipe (12) is set to a value close to the saturated state, for example,
It can be stably maintained at about 95%, and its fluctuation can be almost eliminated, and the accompanying fluctuation in temperature can be suppressed, so that highly accurate measurement is possible.

In order to further stabilize the above-mentioned humidity, it is desirable to connect three or more bubblers in series. However, in consideration of economy and efficiency, it is considered that two bubbles are optimal.

FIG. 4 shows another embodiment of the means for supplying condensable gas. In this embodiment, the supply means for the condensable gas provided in the bypass pipe (12) is a so-called syringe pump, which supplies a liquid that becomes a condensable gas by vaporization, that is, water, to the bypass system path in small quantities. Pump (4
4) and an evaporator (45) provided downstream of the pump (44) in the bypass pipe (12) and evaporating a liquid, that is, water. Even in this case, the same operation and effect as described above can be obtained.

[0045]

According to the present invention, the following effects can be obtained. According to the first aspect of the present invention, the diameter of the pores from the mesopore to the microbore region of the subject and the distribution thereof can be accurately measured without using an expensive apparatus and without losing the shape of the subject. can do.

According to the second aspect of the present invention, by adjusting the flow rate of the non-condensable gas flowing through the non-condensable gas supply system (main supply pipe) and the bypass system branched therefrom, The mixing ratio between the non-condensable gas and the condensable gas can be easily adjusted.

According to the third aspect of the present invention, the condensable gas can be stably supplied to the non-condensable gas flowing through the bypass system in a state close to a substantially saturated state, and the condensable gas supply means can be supplied. The configuration can be simplified and the device can be manufactured at low cost.

According to the fourth aspect of the present invention, the supply state of the condensable gas supplied to the bypass system can be made more stable than when a single bubbler is used, which contributes to improvement in measurement accuracy. be able to.

According to the fifth aspect of the invention, the means for supplying the condensable gas can have a simple structure comprising a pump and an evaporator.

According to the sixth aspect of the present invention, the provision of the temperature maintaining means can prevent the disturbance of the measured value due to the temperature fluctuation, thereby contributing to the improvement of the measurement accuracy.

According to the seventh aspect of the present invention, since the measurement can be performed in a state close to the equilibrium state, the condensable gas condensed by the capillary is vaporized again as in the case where the pressure in the secondary chamber is reduced, and
It is possible to eliminate the risk of deteriorating measurement accuracy, etc.
Measurement accuracy can be improved.

According to the invention of claim 8, since inexpensive and harmless nitrogen gas and water vapor are used as the non-condensable gas and the condensable gas, it is excellent in economy and safety, and there is no possibility of generating pollution.

[Brief description of the drawings]

FIG. 1 is an external view of an embodiment of the present invention.

FIG. 2 is a view schematically showing a schematic configuration of a main body and a piping system.

FIG. 3 is an enlarged vertical sectional view showing another example of the holder.

FIG. 4 is a piping diagram showing another example of the supply means.

[Explanation of symbols]

 (1) Main body (2) Chamber (Primary chamber) (3) (3 ') Holder (holding means) (Inside is secondary chamber) (3a') Enlarged step (4) Cap (5) Subject ( 6) Blocking member (7) Inspection gas supply pipe (inspection gas supply means) (8) Excess gas discharge pipe (9) Passing gas discharge pipe (10) Nitrogen gas source (11) Main supply pipe (supply line) (12 ) Bypass pipe (bypass system path) (13) Regulator (pressure adjusting means) (14) Flow controller (adjusting means) (15) Solenoid valve (16) Flow controller (adjusting means) (17) (18) Solenoid valve (19 (20) Bubbler (supply means) (21) Inlet pipe (22) Outlet pipe (23) Solenoid valve (24) Sealed vessel (25) Water (26) Solenoid valve (27) Water supply pipe (28) Water source (29) Solenoid valve (30) Limit switch (31) Solenoid valve (32) Drain pipe (33) Temperature sensor (34) Heat bath (temperature maintaining means) (35) Trap (36) Automatic pressure controller (37) Solenoid valve (38) Exhaust Mouth (39) Trap (40) Flow meter (measuring means) (41) Solenoid valve (42) (43) Solenoid valve (44) Pump (45) Evaporation (A) an upper case (A1) Door (B) a lower case (C) cable (D) Konbyuta (RH) Hygrometer

Claims (8)

[Claims] 1. A holding means for holding a subject such that the subject having a pore is connected to the primary chamber at one end of the pore and to the secondary chamber at the other end of the pore. A test gas supply means for supplying a test gas which is a mixed gas of a non-condensable gas and a condensable gas to the primary chamber; a non-condensable gas provided in the test gas supply means and supplied to the primary chamber A pore size distribution comprising adjusting means for adjusting the mixing ratio of the gas and the condensable gas, and measuring means connected to the secondary chamber and measuring the amount of the test gas passing through the subject over time. measuring device. 2. The test gas supply means has a supply path of a non-condensable gas and a bypass path branched therefrom,
2. The pore size distribution measuring device according to claim 1, wherein condensable gas supply means is provided in the bypass system. 3. The condensable gas supply means contains a liquid that becomes a condensable gas by vaporization, and the non-condensable gas passes through the liquid, thereby condensing the condensable gas into the non-condensable gas. 3. The pore size distribution measuring device according to claim 2, further comprising a bubbler in which is mixed. 4. The condensable gas supply means has a plurality of bubblers connected in series to a bypass line.
The pore size distribution measuring device according to the above. 5. A condensable gas supply means, which is provided on a pump that supplies a liquid that becomes condensable gas by evaporating into a bypass system by a small amount, and a pump that is provided downstream of the pump in the bypass system. The pore size distribution measuring device according to claim 2, further comprising an evaporator for vaporizing the liquid. 6. The test gas supply means is provided with a temperature maintaining means for maintaining the temperature of the test gas at a set temperature.
The pore size distribution measuring device according to any one of the above. 7. The pore size distribution measurement according to claim 1, further comprising pressure adjusting means for maintaining the secondary chamber at substantially atmospheric pressure and maintaining the primary chamber at a value higher than atmospheric pressure. apparatus. 8. The pore size distribution measuring apparatus according to claim 1, wherein the non-condensable gas is nitrogen, and the condensable gas is water vapor.