JP2010194438A - Method of removing moisture from liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of removing moisture, by which moisture can be suitably selectively removed even from a liquid having a small molecule size, e.g., EtOH. <P>SOLUTION: An inorganic material film 10 is used in which a ratio of He gas permeation flow rate F<SB>He</SB>to SF<SB>6</SB>gas permeation flow rate F<SB>SF6</SB>, namely, F<SB>He</SB>/F<SB>SF6</SB>, is 100-10,000 and in which the SF<SB>6</SB>gas permeation flow rate F<SB>SF6</SB>is 1×10<SP>-11</SP>to 1×10<SP>-8</SP>mol/(m<SP>2</SP>Pa sec). This method is effective particularly in the case where the liquid has a molecule size of ≥0.36 nm such as ethanol and isopropyl alcohol. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for removing moisture from a liquid using an inorganic material film.

A technique for removing moisture contained in a liquid other than water such as an organic liquid by using a film has been studied.
Such technologies include, for example, water removal from electrolytes of lithium ion secondary batteries; dehydration of industrial ethanol and methanol; water removal from lubricating oils; water removal from light oils and heavy oils; water from insulating oils used in transformers. It is expected to be used for removal; moisture removal of liquid crystal sealed in a vacuum between glass substrates; and it is required to be able to remove a minute amount of moisture.

As a technique for removing moisture from an organic liquid using an inorganic material film, for example, Non-Patent Document 1 uses a silica-zirconia film having pores having a diameter of 1 nm or less and having a molecular sieve function, A technique for selectively separating and removing water from a mixed solution of ethanol (hereinafter referred to as EtOH) and water and a mixed solution of isopropyl alcohol (hereinafter referred to as IPA) and water is described. Yes.
Table 1 shows the molecular size (molecular diameter) of typical molecules such as H ₂ O, He, CO ₂ , N ₂ , CH ₃ OH, EtOH, and IPA.

The molecular sizes listed in Table 1 are quoted values from the following references, which are the kinetic diameters in References 1 and 3, and the numerical values of Lennard-Jones potential diameter σ at Lennard-Jones potential in References 2.
[Reference 1]
“Material science of membranes for gas and vapor separation” edited by Yu. Yampolskii, I. Pinnau & BD Freeman, P.6, (2006), John Wiley & Sons Ltd.
[Reference 2]
“Molecular theory of gases and liquids”, Joseph O. Hirschfelder, Charles F. Curtiss, R. Byron Bird. John Wiley & Sons, Inc. (1954) P.1212-1214
[Reference 3]
“On the combination of different transport mechanisms for the simulation of steady-state mass transfer through composite systems using H ₂ / SF ₆ permeation through stainless steel supported silicalite-1 membranes as a model system” M. Hanebutha, R. Dittmeyera, GTP Mabandeb and W. Schwiegerb, Catalysis Today, Volume 104, Issues 2-4, 30 June 2005, Pages 352-359

J. Yang et al., Pervaporation characteristics of aqueous-organic solutions with microporous SiO2-ZrO2 membranes: Experimental study on separation mechanism ”, Journal of membrane science vol.284, P.205-213 (2006)

  However, in the technique described in Non-Patent Document 1, a mixed solution of IPA having a molecular size (molecular diameter) of about 0.464 nm and water having a molecular size of 0.265 nm (hereinafter also referred to as IPA / water). In the case of removing the water from (2), EtOH having a molecular size of about 0.431 nm can be selectively permeated while keeping the amount of IPA permeating the silica-zirconia membrane low. In the case of removing water from a mixed solution with water (hereinafter sometimes referred to as EtOH / water), the amount of EtOH that permeates the silica-zirconia membrane cannot be sufficiently suppressed, and the moisture permeation selectivity is lowered. did.

Specifically, as shown in FIG. 6 of Non-Patent Document 1, for example, when removing moisture from IPA / water having an IPA concentration of 60%, the membrane permeation amount of IPA is about 2 mol / m ² · hr. However, when water is removed from EtOH / water with an EtOH concentration of 60%, the amount of EtOH permeated through the membrane increases to about 22 mol / m ² · hr, and the liquid molecular size is slightly smaller. It becomes difficult to selectively permeate moisture only by getting close to the molecular size of water.
When removing moisture in a liquid using a membrane, it is desirable to use a membrane that does not allow liquid to penetrate as much as possible in addition to the large amount of moisture permeated. According to such a film, even when the liquid is, for example, a mixed liquid composed of a plurality of types of liquids, moisture can be selectively removed while keeping the change in the liquid composition low.

  The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a moisture removal method capable of satisfactorily selectively removing moisture even from a liquid having a small molecular size such as EtOH.

The moisture removal method of the present invention is a method for selectively removing moisture contained in a liquid such as EtOH or IPA using an inorganic material film.
In general, when the pore size is larger than several nanometers, the pore size of the membrane can be determined by, for example, Kelvin's capillary condensation equation (see, for example, JP-A-62-33521). The film characteristics can be judged from the values. However, as described in Non-Patent Document 1 and the like, when the pore size is less than 1 nm, this method cannot accurately determine the pore size. Therefore, for membranes with a pore size smaller than 1 nm, conventionally, it is only possible to judge the characteristics of the membrane by an indirect method such as actually transmitting gas molecules of known size and comparing the permeation flow rate. It was.
Against this background, as a result of intensive studies, the present inventor has determined that a certain film has a characteristic that can selectively remove moisture even from a liquid having a small molecular size such as EtOH. Focusing on the gas permeation flow rate F _He and SF ₆ (sulfur hexafluoride) gas permeation flow rate F _SF6 , it was found that this can be used as an index, and the present invention has been completed. Since the molecular size of He is 0.26 nm and the molecular size of water is close to 0.265 nm, the He gas permeation flow rate F _He is an indicator of the amount of water permeation, and the molecular size of SF ₆ is 0.550 nm. Since it is close to liquids such as EtOH having a molecular size of 0.431 nm and IPA having 0.464 nm, the SF ₆ gas permeation flow rate F _SF6 is considered to be an index of the liquid permeation amount. SF ₆ is a gas at normal temperature.

The method for removing moisture from a liquid according to the present invention is a method for removing moisture from a liquid by using an inorganic material film, and the inorganic material film is formed of a He gas permeation flow rate F _He and a SF ₆ gas permeation flow rate F _SF6 . Ratio: F _He / F _SF6 is 100 to 10,000, and SF ₆ gas permeation flow rate F _SF6 is 1 × 10 ⁻¹¹ to 1 × 10 ⁻⁸ mol / (m ² · Pa · sec).
The molecular size of the liquid is preferably 0.36 nm or more.
When the liquid is ethanol and / or isopropyl alcohol, water can be removed very effectively.
The inorganic material film preferably includes a silica film or a silica-zirconia film.

  According to the present invention, moisture can be selected and removed very well even from a liquid having a small molecular size such as EtOH.

It is sectional drawing which shows an example of an inorganic material film | membrane. It is a figure which shows a silica membrane typically. It is a schematic block diagram which shows an example of a gas permeation | transmission flow rate measuring apparatus. It is a schematic block diagram which shows an example of a pervaporation measuring apparatus. It is the graph which plotted the measurement result of the gas permeation | transmission flow volume with respect to the permeation | transmission molecule | numerator size.

Hereinafter, the present invention will be described in detail.
In the method of removing moisture from the liquid of the present invention, an inorganic material film that satisfies the following conditions (1) and (2) is used.
Condition (1): Ratio of He gas permeation flow rate F _He to SF ₆ gas permeation flow rate F _SF6 : F _He / F _SF6 is 100 to 10,000. More preferably, it is 300-1500.
Condition (2): SF ₆ gas permeation flow rate F _SF6 is 1 × 10 ⁻¹¹ to 1 × 10 ⁻⁸ mol / (m ² · Pa · sec). More preferably, it is 1 × 10 ⁻¹⁰ to 1 × 10 ⁻⁸ mol / (m ² · Pa · sec).

  By using such an inorganic material film and supplying the liquid to be treated to one side (primary side) of the film, in particular, moisture in the liquid selectively permeates the inorganic material film and allows moisture to pass through the other side. Can be removed from the side (secondary side).

In addition, each gas permeation | transmission flow rate in the said conditions (1) and (2) is a value in the measurement temperature of 200 degreeC. If the gas permeation flow rate is measured at a low temperature such as room temperature, an interaction occurs between the pore surface of the inorganic material film and the molecules of liquid or moisture, and the association between the permeation phenomenon and the pore size is complicated. Become. Therefore, in order to suppress such an interaction to a negligible level, a measured value at a high temperature of 200 ° C. was adopted. The gas supply pressure at the time of measurement is in the range of 0.1 to 0.4 MPa. While increasing the pressure, confirm that the permeate flow rate is proportional to the pressure, and at the gas permeate flow rate at unit pressure. The value was converted to “mol / (m ² · Pa · sec)”.

The liquid to be treated by the water removal method of the present invention may be any liquid as long as it is liquid at normal temperature and pressure. Specifically, alcohols such as EtOH (molecular size: 0.431 nm), IPA (molecular size: 0.464 nm), methanol (molecular size: 0.367 nm), 2-butanol (molecular size: 0.464 nm), etc. An organic liquid such as acetone (molecular size: 0.467 nm) can be exemplified, and water can be removed from a mixed liquid composed of one or more of them. Furthermore, examples of the liquid include oils such as light oil, heavy oil, lubricating oil, and insulating oil; lithium-ion secondary battery electrolyte; and liquid crystal.
In addition, the molecular size of EtOH, IPA, methanol, and acetone is the numerical value quoted from the above-mentioned reference 2, and the value of Lennard-Jones potential diameter σ in the Lennard-Jones potential is described in [nm] units.

When the F _He / F _SF6 of the inorganic material film is less than the lower limit value of the condition (1), the moisture selective permeability is low, and the moisture and the liquid cannot be sufficiently separated. On the other hand, the film itself exceeding the upper limit is substantially difficult to manufacture.
Further, even in a range _F He _{/ F SF6} condition of _(1), is less than the lower limit of _{F SF6} condition (2), but can suppress permeation of liquid, moisture permeation is suppressed, practical Lack of sex. Even if F _He / F _SF6 is within the range of the condition (1), if F _SF6 exceeds the upper limit value of the condition (2), the liquid permeates too much, which is not practical.

In this way, by using F _He and F _SF6 of the inorganic material film as indexes, even if liquid is prepared and water is not actually removed by the inorganic material film, the inorganic material film has a small molecular size of EtOH, It can be determined whether or not moisture can be selectively removed from a liquid such as IPA. This is because the molecular size of He is 0.26 nm and the molecular size of water is close to 0.265 nm, so that F _He is an indicator of the amount of water permeation, and the molecular size of SF ₆ is 0.550 nm. molecular size EtOH or 0.431Nm, closer and liquids such as IPA in _0.464Nm, presumably _{because F SF6} is an index of the liquid permeation amount. Therefore, it is considered that the behavior of removing moisture from the liquid can be appropriately determined by adopting such an index.

  The inorganic material film used in the present invention is not limited in material and form as long as the above conditions (1) and (2) are satisfied. For example, as shown in FIG. An amorphous molecular sieve having a thin thickness is coated on a porous substrate 11 such as a material by hot coating using at least one colloidal sol selected from silica colloidal sol, zirconia colloidal sol, and titania colloidal sol as a permeable membrane material, followed by baking. A suitable example is an inorganic material film 10 in the form of a composite film on which a permeable film 12 as a functional layer is formed.

As an example of such an inorganic material film 10, a manufacturing method thereof will be described by taking a composite film in which a permeable film 12 made of an amorphous silica film is formed on a tubular ceramic base material.
First, for example, an α-alumina porous tube is prepared as a ceramic substrate, and α-alumina particles are deposited on the outer peripheral surface of the ceramic substrate to make the outer peripheral surface of the ceramic substrate smooth. In addition, relatively large pores formed on the outer peripheral surface are sealed. Specifically, α-alumina particles are coated on the outer peripheral surface of the ceramic base material using silica colloid sol as a binder, and heated and fired at, for example, 450 to 550 ° C. This can also prevent pinhole defects when a permeable membrane material colloidal sol is coated thereon in the next step.

As the ceramic substrate, those having a pore diameter of about several hundred nm to several tens of μm, more preferably several μm are used. This depends on the size of the α-alumina particles to be used, but it is easy to smooth the substrate surface by filling the pores with particles by using particles having the same pore size as the alumina particles. Because. The wall thickness is preferably about 0.1 to 5 mm.
As the α-alumina particles, those having a particle size of 0.2 to 2.0 μm are preferably used, and using a plurality of types of particles having different particle sizes is preferable in that respect because it is easy to smooth the ceramic substrate. .

  Next, this ceramic substrate is heated to 170 to 190 ° C. in advance. Then, the colloidal silica sol as the permeable membrane material is brought into contact with the heated ceramic substrate, and the solvent in the sol is instantaneously evaporated. Then, by baking this, the condensation of the sol is completed, and a silica film in which pores are formed can be formed.

  For example, silica colloidal sol is prepared by dissolving tetraethoxysilane, which is a raw material of silica, in ethanol, adding hydrochloric acid or nitric acid as an acid catalyst, and adjusting the pH of the solution to around 1 to 3 at 50 to 100 ° C. for 1 to 24 hours. Can be prepared by a method of hydrolysis and condensation.

In this way, an extremely thin film can be easily formed by contacting the colloidal silica sol, which is the raw material of the permeable membrane, with the preheated ceramic substrate and evaporating the solvent in the sol instantaneously. Can be formed. Moreover, although baking is performed after such hot coating, the film thickness can be increased by repeating the subsequent hot coating and baking appropriately.
In order to form the inorganic material film under the conditions (1) and (2), it is preferable to repeat the hot coating-firing step and perform it 2 to 10 times in total. Moreover, by repeating in this way, a silica film having a thickness of about 10 to 300 nm can be finally formed.

In the above description, the silica film is exemplified as the permeable membrane 12 that selectively permeates moisture, but other examples include a silica-zirconia film, a zirconia film, a titania film, and the like.
For example, in the case of forming a silica-zirconia film, tetrabutoxyzirconia, which is a raw material of zirconia, is similarly dissolved in ethanol, and hydrochloric acid or nitric acid is added as an acid catalyst so that the pH of the solution is around 1 to 3. , Condensation is performed to obtain a zirconia colloidal sol. Then, this is mixed with a silica colloidal sol separately prepared by the method described above. Next, using the obtained silica-zirconia colloidal sol, a silica-zirconia film can be formed by appropriately repeating the above hot coating and baking.
The silica-zirconia colloidal sol is prepared by adding hydrochloric acid or nitric acid as an acid catalyst as described above while simultaneously adding tetraethoxysilane and tetrabutoxyzirconia to ethanol, and adjusting the pH of the solution to around 1 to 3. It can also be prepared by a method of decomposing and condensing.

Further, when forming a zirconia film or a titania film, a colloidal sol corresponding to these, that is, using a zirconia colloidal sol, a titania colloidal sol or the like as a permeable membrane material, can be formed in the same manner as the case of a silica film Good.
Furthermore, in the above description, the composite membrane in which the permeable membrane 12 such as a silica membrane is formed on the tubular porous substrate 11 is exemplified. However, the membrane may not be provided with the porous substrate 11 and may not be tubular. May be. However, as described above, the composite film provided with the porous substrate 11 is easy to manufacture. Moreover, since it is excellent also in strength (pressure resistance), the inorganic material film 10 is immersed in the liquid when removing water from the liquid, the liquid is supplied under a pressurized condition, and one surface side is sucked to a reduced pressure, It is possible to remove moisture under a large pressure difference. In addition, in a liquid having high viscosity, such as liquid crystal, moisture can be removed under a large pressure difference after the temperature is lowered from room temperature to lower the viscosity.

In the production of such an inorganic material film 10, the properties of the formed inorganic material film 10 are affected by the colloidal particle diameter in the used colloidal sol, the coating method, the firing temperature, and the firing time.
A suitable colloid particle diameter for producing the inorganic material film 10 having the above conditions (1) and (2) is in the range of 10 to 20 nm. In order to set the colloidal particle diameter in such a range, the mass ratio of the acid catalyst such as film raw material compound such as tetraethoxysilane: water: nitric acid at the time of hydrolysis described above is, for example, 7.5 to 10 : 100: 0.5 is preferable.
The firing temperature is preferably in the range of 300 to 600 ° C, more preferably 400 to 500 ° C, and the firing time is appropriately set in the range of 30 minutes to several days.

Inorganic material film 10 thus formed is a silica film will be exemplified schematically in Figure 2, particles constituting the film, i.e. silica particles P _S distance A between in this example is controlled appropriately Although it is possible for moisture and He to permeate the gap A, it is considered that a solution such as EtOH and IPA and SF ₆ are hardly allowed to pass. Therefore, such an inorganic material film 10 satisfies the above conditions (1) and (2), and as a result, it is considered that moisture can be selectively removed even from a liquid having a small molecular size such as EtOH. . In addition, even EtOH having a small molecular size can effectively remove the water contained therein, so that the water can naturally be removed from various liquids having a molecular size larger than that of EtOH.
Usually, in the interior of the silica particles P _S, as shown in FIG. 2, -Si-O-Si- network is formed, water and, although He is permeable, EtOH, molecules such as IPA is Cannot penetrate. Therefore, as described above, it is important to control the interval A in sieving between moisture and liquid molecules.

Next, a method for measuring the gas permeation flow rate of the inorganic material film 10 and a method for removing moisture from the liquid using the inorganic material film 10 and measuring the water permeation amount and the liquid permeation amount at that time will be described.
FIG. 3 shows a preferred example of the gas permeation flow rate measuring device 20, and measures gas permeation flow rates such as He gas permeation flow rate F _He and SF ₆ gas permeation flow rate F _SF6 for the tubular inorganic material film 10. To do.
The gas permeation flow rate measuring device 20 includes a heater 21 for heating the inorganic material film 10 and the gas supplied to the inorganic material film 10. The heater 21 has a cylindrical shape, and a gas introduction pipe 23 for introducing the gas from the gas cylinder 22 into the heater 21 is connected to one end 21a thereof. A gas exhaust pipe 24 through which gas that has not permeated through the inorganic material film 10 disposed in the heater 21 is connected to the other end 21 b side, and an inorganic material disposed in the heater 21. A permeated gas discharge pipe 25 through which the gas that has permeated the membrane 10 is discharged is provided. The heater 21 is connected to a temperature controller 26 provided with a thermocouple 26a for measuring the temperature in the inorganic material film 10, and the gas permeation flow rate of the inorganic material film 10 can be measured in a temperature range of 25 to 300 ° C. It is like that.

In the middle of the gas introduction pipe 23, a flow rate controller 27 such as a mass flow controller for controlling the flow rate of gas supplied from the gas cylinder 22 into the heater 21 and a pressure control valve 28 for controlling the pressure are provided. The gas permeation flow rate can be measured in a gas supply pressure range of 1 to 0.4 MPa.
The downstream end of the permeate gas discharge pipe 25 is introduced into a gas flow meter 29 such as a soap film flow meter, and the permeate flow rate of the gas that has passed through the inorganic material film 10 is measured.
In FIG. 3, P is a pressure gauge, S is a stop valve, N is a needle valve, and C is a three-way cock.

In the case of measuring the gas permeation flow rate using this gas permeation flow rate measuring device 20, first, a tubular inorganic material film 10 having one end sealed and the other end open is prepared. This is disposed in the heater 21. Next, the upstream end of the permeate gas discharge pipe 25 is connected to the open end. The heater 21 is heated to a predetermined temperature (200 ° C. in this example), the gas cylinder 22 is opened, the flow controller and the pressure control valve 27 are adjusted, and the gas in the gas cylinder 22 is supplied to a predetermined gas supply pressure. (In this example, 0.1 to 0.4 MPa) is introduced into the heater 21.
Then, the gas which permeate | transmitted from the outer peripheral side of the inorganic material film | membrane 10 to the inner peripheral side among the gas introduce | transduced in the heater 21 is guide | induced to a soap film | membrane flowmeter, and a gas permeation | transmission flow rate can be measured.

FIG. 4 shows an example of a pervaporation measuring device 30 that is preferably used when water is removed from a liquid using the inorganic material film 10, and the tubular inorganic material film 10 is used. It is used when removing moisture from the liquid.
The measuring device 30 includes a glass container 31 into which a liquid that is a target for moisture removal is charged. The glass container 31 includes a first cylindrical portion 31a and a second cylindrical portion 31b that are communicated with each other at both end side coupling portions and are capable of passing each other. A stirring blade 32 having a stirring motor 32a is inserted and disposed in the first cylinder portion 31a, and a heater 33 is provided so that the liquid in the first cylinder portion 31a can be heated while being stirred. The heater 33 is connected to a temperature controller 33a having a thermocouple 33b for measuring the liquid temperature. On the other hand, the inorganic material film 10 is arranged in the second cylindrical portion 31b. Further, on the inner peripheral side of the inorganic material film 10, the upstream end of the decompression pipe 35 having a decompression means 34 such as a vacuum pump connected to the downstream end is connected by a connecting jig 36, and the vacuum pump is operated, The pressure on the inner peripheral side of the inorganic material film 10 can be made lower than that on the outer peripheral side. In the middle of the decompression pipe 35, two cold traps 37 having a refrigerant such as liquid nitrogen are arranged in series in this example, and moisture and liquid that have permeated through the inorganic material film 10 are cooled and condensed solids. It is supposed to be collected as.

When the moisture is removed from the liquid using the measuring device 30 and the moisture permeation amount (water vapor permeation amount) and liquid permeation amount (liquid vapor permeation amount) of the inorganic material film 10 at that time are measured, The tubular inorganic material film 10 is disposed in the second cylindrical portion 31b, and the connection jig 36 is inserted on the inner peripheral side of the inorganic material film 10. Next, a liquid is put into the glass container 31 and the stirring blade 32 is operated at a rotational speed of 500 to 1000 rpm by the stirring motor 32a, and the temperature (feed temperature) of the liquid is set to room temperature or about 30 to 60 ° C. by the heater 33. Heat. Here, the stirring by the stirring blade 32 is performed for the purpose of giving a flow to the liquid supplied to the inorganic material film 10 and the purpose of making the liquid temperature in the glass container 31 uniform. The purpose of heating the liquid in the above temperature range is to facilitate the diffusion of dissolved water. If the liquid is a highly viscous liquid, the viscosity is lowered and the liquid is made of an inorganic material film. This is also for facilitating the supply to 10. It has been confirmed that under such a stirring condition, the moisture permeation amount and the liquid permeation amount do not depend on the rotational speed of the stirring blade 32.
And a vacuum pump is operated and the inner peripheral side of the inorganic material film | membrane 10 is pressure-reduced. Then, due to the pressure difference between the inner peripheral side and the outer peripheral side of the inorganic material film 10, the liquid and moisture permeate from the outer peripheral side (primary side) to the inner peripheral side (secondary side) of the inorganic material film 10, and the cold trap 37. To be collected. Subsequently, the collected condensed solid is returned to room temperature to form a liquid, and the composition of the liquid is analyzed by a gas chromatograph, whereby the moisture permeation amount and the liquid permeation amount of the inorganic material film 10 can be obtained. In addition, the code | symbol P in FIG. 4 is a pressure gauge.

The He gas permeation flow rate F _He and the SF ₆ gas permeation flow rate F _SF6 measured by the gas permeation flow rate measuring apparatus 20 illustrated in FIG. 3 become the inorganic material film 10 satisfying the above conditions (1) and (2). According to this, when moisture is removed from the liquid by the pervaporation measuring apparatus 30 illustrated in FIG. 4, even if the liquid is a liquid having a small molecular size such as EtOH, the inorganic material film 10 is permeated. The amount of liquid to be kept can be kept low, while moisture can be selectively permeated.
Specifically, according to the inorganic material film 10 that satisfies the above conditions (1) and (2), the liquid permeation amount at 50 ° C. (feed temperature) can be suppressed to 3 mol / (m ² · hr) or less. Has been revealed.
Therefore, water removal using such an inorganic material film 10 is, for example, water removal from the electrolyte of a lithium ion secondary battery; dehydration of industrial ethanol and methanol; water removal from lubricating oil; water in light oil and heavy oil Removal; Moisture removal of insulating oil used in transformers; utilization of liquid crystal sealed in vacuum between glass substrates is expected.

In particular, when the amount of liquid permeation can be suppressed in this way, even when the liquid to be processed is a mixed liquid, the composition change can be suppressed as much as possible, and moisture can be removed. Therefore, when the liquid to be processed is a liquid crystal used for a display device, such moisture removal by the inorganic material film 10 is very effective.
That is, when a liquid crystal is enclosed between two glass substrates to produce a display device, the encapsulation is performed under a high vacuum between the glass substrates. Is essential to eliminate. In the case of using a mixture of many kinds of expensive liquid materials such as liquid crystals, if a specific component permeates through the membrane, the liquid crystal blending balance is lost, leading to liquid crystal loss. In this respect, the inorganic material film 10 satisfying the conditions (1) and (2) can suppress the permeation amount even if it is a liquid having a small molecular size. Is practical.

In addition, as shown in the examples described later, according to such an inorganic material film 10, it is possible to suppress transmission of a liquid having a molecular size of 0.36 nm or more in particular. Therefore, when such an inorganic material film 10 is used, a particularly excellent effect is exhibited in removing moisture from a liquid having a molecular size of 0.36 nm or more.
Liquid molecules having a molecular size of 0.36 nm or more include (C ₂ H ₅ ) ₂ O (0.55 nm), CH ₃ COOCH ₃ (0.51 nm), CH ₃ COOC as well as various alcohols and acetone already exemplified. ₂ H ₅ (0.52 nm) can be exemplified. The value in parentheses is the molecular diameter value. The molecular diameter shown here is a value quoted from page 1214 of the above-mentioned Reference 2.

[Example 1]
(Preparation of silica film (Si-1 film))
(1) Preparation of silica colloidal sol Using tetraethoxysilane (TEOS) as a silica source, a silica colloidal sol as a permeable membrane raw material was obtained by the following procedure.
Water as a solvent and dilute nitric acid as an acid catalyst were added to an Erlenmeyer flask, and TEOS was further added thereto. This mixed solution was hydrolyzed while stirring with a stirrer at 25 ° C. for 1 hour to prepare a TEOS hydrolyzed solution. This was hydrolyzed and condensed with a hot stirrer for 12 hours while heating and stirring (liquid temperature: 180 ° C.) to prepare a silica colloid sol.
The particle size of the colloidal particles is obtained by using a dynamic light scattering method (a method in which the particle is irradiated with laser light to determine the speed at which the particles make Brownian motion, and the particle size is calculated based on the value). be able to. The colloidal particle size determined by this measurement was in the range of 10 to 20 nm.
(2) Preparation of Ceramic Base Material As the ceramic base material, an α-alumina porous tube having a length of 70 to 100 mm, an outer diameter of 10 mm, a wall thickness of 1 mm, and a nominal average pore diameter of 1 μm was used. A soft glass tube having an outer diameter of 8 mm was connected to both ends with glass frit powder, and the soft glass tube connected to one end was closed with a burner flame. In this way, a ceramic substrate with one end sealed was prepared.
Next, in order to smooth the surface of the ceramic substrate, two kinds of α-alumina fine particles having different particle diameters using silica colloid sol as a binder (high purity alumina: Sumitomo Chemical; average particle diameter 1) .84 μm and 0.2 μm) were coated and fired at 450-550 ° C.
(3) Hot coating and firing Next, the silica colloidal sol (solid content concentration: 2% by mass) prepared in the above (1) is hot coated on the ceramic substrate of the above (2) that has been heated to 180 ° C. in advance. The procedure of baking at 450 to 550 ° C. was repeated, and the hot coating-baking process was performed four times in total. In this way, an Si-1 film in which a silica film (a permeable film which is a molecular sieve functional layer) was formed on a ceramic substrate was produced. Moreover, the film thickness of the formed silica film was 150 nm. The film thickness was determined by observing the cross section of the composite film with a scanning electron microscope (SEM).

(Measurement of pure gas permeation flow rate of Si-1 film)
The gas permeation flow rate of the obtained Si-1 film was measured using the gas permeation flow rate measuring device 20 shown in FIG. In addition to He and SF ₆ , the gas is measured for a total of five types of CO ₂ , N ₂ , and C ₃ H ₈ , the measurement temperature is 200 ° C., and the gas supply pressure is 0.1 to 0.4 MPa. The permeate flow rate was measured while increasing the pressure, and the measured value was converted to a value in unit pressure.
The molecular size of each gas is as already shown in Table 1. The molecular sizes of other gases are also exemplified in Table 1 for reference.
The measured gas permeation flow rates are shown in FIG.
In Table 2, the numerical values in parentheses are values of the permeation flow rates of other gases when SF _{SF6 is set} to 1.

(Measurement of water permeation and liquid permeation through Si-1 membrane)
Further, moisture was removed from the liquid using the obtained Si-1 film, and the moisture permeation amount and the liquid permeation amount at that time were measured by the pervaporation measuring device 30 of FIG.
As the liquid, organic solvents (EtOH, IPA, 2-butanol (2-BuOH)) each containing a small amount of water were used. Table 2 shows the composition and feed temperature of these liquids.
The amounts of water and liquid collected by the cold trap were analyzed by gas chromatography, and the water permeation amount, that is, the water vapor permeation amount F _H2O, and the liquid permeation amount, that is, the liquid vapor permeation amount F _sol were obtained. The results are shown in Table 2.

Further, Table 3 shows vapor permeance, vapor permeation amount and liquid vapor permeation amount described in Table 2 as liquid and water vapor vapor pressure at the measurement temperature (feed temperature: 50 ° C.) (Feed side water vapor pressure V _{feed). , H 2 O 2} , solution vapor pressure V _{feed, sol} ) and converted into units of mol / (m ² · sec · Pa).
Then, from these values, the ratio of the water vapor permeation flow rate F _H2O and the liquid vapor permeation flow rate F _sol : F _H2O / F _sol was determined and listed in Table 3 as the water vapor selective permeability. If this ratio exceeds 1, it means that moisture permeates more selectively than liquid. When this ratio is 2 or more, it can be determined that the ability to selectively remove moisture from the liquid is excellent.

[Examples 2 and 3]
(Preparation of silica-zirconia film (SZ-1 film, SZ-4 film))
(1) Preparation of silica-zirconia colloidal sol In this example, TEOS having a slow hydrolysis reaction rate is hydrolyzed first, and then zirconium tetrabutoxide (ZrTB) is added and hydrolyzed to hydrolyze. Silica-zirconia colloidal sol as a raw material for the permeable membrane was obtained from alkoxides having different reaction rates.
A specific method for preparing a colloidal sol will be described in order.
In the present example, the composition ratio of Si / Zr was set to 1: 1.

[1] TEOS was put in an Erlenmeyer flask, ethanol was added, and then a lid was placed so that water did not enter to prepare a TEOS mixed solution.
[2] Pipette the required amount of water required to hydrolyze TEOS into test tube A, and stir it thoroughly while adding 1N hydrochloric acid (a few drops with a pipette) to this water. A pH 2-3 aqueous solution for hydrolysis was prepared.
[3] The TEOS hydrolysis solution prepared in [2] was added to [1], and TEOS was hydrolyzed while stirring at room temperature.
[4] Ethanol and zirconia-tetrabutoxide (ZrTB) were added to an Erlenmeyer flask to make a mixed solution, which was added to the TEOS hydrolyzed solution prepared in [3] above.
[5] Ethanol, water necessary for hydrolysis of ZrTB, and 1N-hydrochloric acid (a few drops with a pipette) were mixed in test tube B to prepare a ZrTB hydrolysis solution.
[6] The solution prepared in [5] above was added to the solution in [4] above, and the mixture was sufficiently stirred to hydrolyze ZrTB.
[7] In the test tube C, a solution in which water and 1N hydrochloric acid (a few drops of pipette) were mixed was prepared. This solution is an acid catalyst solution for condensation polymerization.
[8] The acid catalyst solution of [7] was added to the solution of [6] above, and the state was maintained for 10 hours while heating with a heater until boiling, and condensation polymerization was performed.
[9] When 10 hours had elapsed, the heater was turned off and stirring was continued until the solution cooled to room temperature.
Two types of silica-zirconia (1: 1) colloidal sols of 1.0% by mass and 2.0% by mass were prepared by the procedure as described above.
The colloidal particle diameter of the obtained colloidal sol was in the range of 10 to 20 nm.

(2) Preparation of Ceramic Base Material A ceramic base material was obtained in the same manner as (2) of Example 1.
(3) Hot coating and baking Next, the two types of silica-zirconia colloidal sols (solid content concentration: 1.0% by mass and 2.0% by mass) prepared in the above (1) were each heated to 180 ° C. in advance. The above (2) ceramic substrate was hot-coated and baked at 450 to 550 ° C. This procedure was repeated, and the hot coating-firing process was performed four times in total. Thus, SZ-1 membrane and SZ-4 membrane in which a silica-zirconia membrane (a permeable membrane which is a molecular sieve functional layer) was formed on a ceramic substrate were produced. The formed silica-zirconia film had a thickness of 200 to 250 nm.
The solid content concentration of the colloidal sol used in Examples 2 and 3 was 1.0% by mass in Example 2, and 2.0% by mass in Example 3. Moreover, the film thickness of the silica-zirconia film in the obtained SZ-1 film and SZ-4 film is as shown in Table 2.

(Measurement of pure gas permeation flow rate of SZ-1 membrane and SZ-4 membrane)
The same operation as in Example 1 was performed. However, measurement of the gas permeation flow rate was omitted for C ₃ H ₈ . The results are shown in FIG. 5 and Tables 2 and 3.

(Measurement of water permeation and liquid permeation through SZ-1 and SZ-4 membranes)
The same operation as in Example 1 was performed. The results are shown in Tables 2 and 3.

[Comparative Example 1]
(Preparation of silica film (Si-2 film))
In the same manner as in Example 1, a silica colloid sol was prepared. However, after the preparation, this sol was allowed to stand at room temperature for 2 weeks to increase the colloidal particle diameter of the silica colloid sol until it exceeded 20 nm.
In the subsequent steps, a Si-2 film was prepared in the same manner as in Example 1, and various similar measurements were performed on this film. The results are shown in FIG. 5 and Tables 2 and 3.

[Discussion]
As is clear from the above results, in each example using an inorganic material film satisfying the conditions (1) and (2), F _H2O / F _sol is 10 to 60, and moisture can be selectively removed very well. It has been shown.
From the graph of FIG. 5, it can be understood that in Examples 1 to 3, the gas permeation flow rate increases as the liquid molecular size decreases. And the tendency becomes remarkable with a molecular size of 0.36 nm as a boundary. Therefore, it can be understood that the gas permeation flow rate of the liquid can be more effectively suppressed when the molecular size of the liquid is 0.36 nm or more.
In Comparative Example 1 using an inorganic material film that does not satisfy the conditions (1) and (2), a large amount of all the five gases permeated in this example permeated, and F _H2O / F _sol was a small value.
In addition, when the film described in Non-Patent Document 1 was made on a trial basis and the gas permeation flow rates of He, SF ₆ , and N ₂ were measured in the same manner as in the examples of the present specification, it was as shown in FIG. Conditions (1) and (2) were not satisfied.

DESCRIPTION OF SYMBOLS 10 Inorganic material film | membrane 11 Porous base material 12 Permeation | transmission film | membrane P _s silica particle A Spacing between silica particles 20 Gas permeation flow rate measuring device 21 Heater 21a One end portion 21b of heater The other end portion 22 of the heater Gas cylinder cylinder 23 Gas introduction Pipe 24 Gas exhaust pipe 25 Permeate gas exhaust pipe 26 Temperature controller 26a Thermocouple 27 Flow controller 28 Pressure control valve 29 Gas flow meter P Pressure gauge S Stop valve N Needle valve C Three-way cock 30 Pervaporation measuring device 31 Glass container 31a First cylindrical portion 31b of glass container Second cylindrical portion 32a of glass container Stirring blade 32a Stirring motor 33 Heater 33a Temperature controller 33b Thermocouple 34 Decompressing means 35 Depressurizing pipe 36 Connecting jig 37 Cold trap

Claims (4)

A method of removing moisture from a liquid using an inorganic material film,
The inorganic material film has a ratio of He gas permeation flow rate F _He and SF ₆ gas permeation flow rate F _SF6 : F _He / F _SF6 is 100 to 10,000,
The method for removing moisture from a liquid, wherein the SF ₆ gas permeation flow rate F _SF6 is 1 × 10 ⁻¹¹ to 1 × 10 ⁻⁸ mol / (m ² · Pa · sec).   The water removal method according to claim 1, wherein the molecular size of the liquid is 0.36 nm or more.   The water removal method according to claim 2, wherein the liquid is ethanol and / or isopropyl alcohol.   The water removal method according to any one of claims 1 to 3, wherein the inorganic material film includes a silica film or a silica-zirconia film.

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