JP6479534B2 - Separation membrane structure and method for producing the same - Google Patents

Description

  The present invention relates to a separation membrane structure and a method of manufacturing the same.

  Conventionally, a separation membrane structure is known that includes a porous support having a plurality of through holes and a carbon membrane formed on the inner surface of each through hole (see, for example, Patent Document 1). The carbon film forming step includes a step of adhering a polyamic acid solution to the inner surface of each through hole, a step of ventilating through each through hole and drying to imidize the polyamic acid to the polyimide film, and an inert atmosphere. Carbonizing the polyimide film by thermal decomposition of

Unexamined-Japanese-Patent No. 2010-110704

  However, in the process of ventilating each through hole, the wind speed in the through hole distant from the central axis is slower than the through hole close to the central axis of the porous support, so the through holes distant from the central axis The adhesion thickness tends to be large. As a result, there is a problem that the carbon film formed in the through hole distant from the central axis becomes thick and cracks and peeling occur. Such problems are significant when the viscosity of the polyamic acid solution is high.

  The above problems are not limited to the case of using a polyamic acid solution for forming a carbon film, but a ceramic sol solution for forming an MF film or a UF film, a seeding slurry for forming a zeolite film, or a silica film The same problem occurs when using a separation membrane forming solution such as silica sol solution for forming

  This invention is made in view of the above-mentioned situation, and it aims at providing the separation membrane structure which can control the crack of a separation membrane, and its manufacturing method.

  The separation membrane structure according to the present invention comprises a porous support and a plurality of separation membranes. The porous support has a plurality of through holes respectively connected to the first end face and the second end face. The plurality of separation membranes are formed on the inner surfaces of the plurality of through holes. The plurality of through holes includes a first through hole located within a predetermined distance from the central axis of the porous support, and a second through hole located outside the predetermined distance from the central axis. The plurality of separation membranes include a first separation membrane formed on the inner surface of the first through hole and a second separation membrane formed on the inner surface of the second through hole. The thickness ratio of the average thickness of the second separation membrane to the average thickness of the first separation membrane is 37.5 or less.

  ADVANTAGE OF THE INVENTION According to this invention, the separation-membrane structure which can suppress the crack of a separation membrane, and its manufacturing method can be provided.

Perspective view of separation membrane structure A-A sectional view of FIG. 1 B-B sectional view of FIG. 1 Figure for explaining the drying process of the separation membrane formation solution

  Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, the drawings are schematic, and ratios of respective dimensions may be different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is needless to say that parts having different dimensional relationships and proportions are included among the drawings.

(Configuration of separation membrane structure 100)
FIG. 1 is a perspective view of the separation membrane structure 100. FIG. FIG. 2 is a cross-sectional view taken along line A-A of FIG.

  The separation membrane structure 100 comprises a porous support 10, a plurality of separation membranes 20, a first seal 30 and a second seal 40. The separation membrane structure 100 is a so-called monolithic structure. The monolith means a shape having a plurality of holes formed in the longitudinal direction, and is a concept including a honeycomb shape.

  The porous support 10 is a rod-shaped member extending in the longitudinal direction centering on the central axis AX1. In the present embodiment, the porous support 10 has a cylindrical shape, but may have a polygonal columnar shape, an elliptical columnar shape, or the like. The length of the porous support 10 in the longitudinal direction can be 150 to 2000 mm, and the diameter of the porous support 10 in the lateral direction can be 30 to 220 mm.

The porous support 10 is made of a porous material. As the porous material, ceramic materials, metal materials, resin materials and the like can be used. As the ceramic material, alumina (Al ₂ O ₃ ), titania (TiO ₂ ), mullite (Al ₂ O ₃ · SiO ₂ ), selben, cordierite (Mg ₂ Al ₄ Si ₅ O ₁₈ ), etc. can be used. .

  The porous support 10 may contain an inorganic binder. As the inorganic binder, at least one of titania, mullite, sinterable alumina, silica, glass frit, clay mineral, and sinterable cordierite can be used.

  The porosity of the porous support 10 can be, for example, 25% to 50%. The average pore size of the porous support 10 can be, for example, 5 μm to 25 μm. The porosity and average pore size of the porous support 10 can be measured by a mercury porosimeter. The average particle size of the porous support 10 can be 10 μm to 100 μm. The average particle diameter of the porous support 10 is an arithmetic mean value of the maximum diameters of the 30 particles to be measured, which are measured by cross-sectional microstructure observation using a scanning electron microscope (SEM).

  The porous support 10 has a first end face S1, a second end face S2, a side face S3, and a plurality of through holes 11. The first end face S1 is provided opposite to the second end face S2. The side surface S3 is continuous with the outer edge of the first end surface S1 and the outer edge of the second end surface S2. In the present embodiment, the first end face S1 and the second end face S2 are circular, but may be polygonal or elliptical.

  The plurality of through holes 11 extend from the first end surface S1 to the second end surface S2. The plurality of through holes 11 penetrate the porous support 10. Although the cross-sectional shape of each through hole 11 in the present embodiment is circular, it may be polygonal or elliptical. The inner diameter of each through hole 11 can be 1 to 5 mm. The number of through holes 11 can be set as appropriate.

  Here, as shown in FIG. 2, the plurality of through holes 11 have their centers located within a predetermined distance L from central axis AX 1 in the radial direction centering on central axis AX 1 of porous support 10. And a plurality of second through holes 11B whose centers are located outside the range of a predetermined distance L from the central axis AX1. A portion of the first through hole 11A may be located outside the range of the predetermined distance L from the center axis AX1, but the whole of the first through hole 11A is located within the range of the predetermined distance L from the center axis AX1 Is preferred. A portion of the second through hole 11B may be located within the range of the predetermined distance L from the central axis AX1, but the entire second through hole 11B is located outside the range of the predetermined distance L from the central axis AX1 Is preferred.

  The predetermined distance L can be set according to the size of the mask used in the step of drying the separation membrane forming solution, as described later. In the present embodiment, the first through holes 11A and the second through holes 11B have the same configuration.

  The plurality of separation membranes 20 are formed on the inner surfaces of the plurality of through holes 11. Each separation membrane 20 is formed in a cylindrical shape. A space inside the separation membrane 20 is a cell C for circulating the mixed fluid. The inner diameter of the cell C can be, for example, 0.5 mm to 5 mm.

  As the separation membrane 20, a known MF membrane, UF membrane, gas separation membrane, pervaporation membrane, vapor permeable membrane, or the like can be used. The separation membrane 20 may be any membrane formed using a separation membrane forming solution. Specifically, as the separation membrane 20, a ceramic membrane (for example, see JP-A-3-267129, JP-A-2008-246304), a carbon monoxide separation membrane (for example, see JP4006107), helium Separation membrane (see, for example, patent 3953833), hydrogen separation membrane (see, for example, patent 3933907), carbon membrane (see, for example, JP 2003-286018 A), zeolite membrane ( -66188), silica membrane (see, for example, WO 2008/050812), organic-inorganic hybrid silica membrane (JP 2013-203618), p-tolyl group-containing silica membrane (JP 2013-dan) 226541) and the like.

  Here, the plurality of separation membranes 20 are a plurality of first separation membranes 20A positioned within a predetermined distance L from the central axis AX1 in the radial direction, and a plurality of first separation membranes 20 positioned outside the predetermined distance L from the central axis AX1. And a second separation membrane 20B. The first separation film 20A is disposed in the first through hole 11A. The second separation film 20B is disposed in the second through hole 11B.

  The average film thickness T1 of the first separation film 20A can be set to 0.5 μm or more and 50 μm. The average film thickness T2 of the second separation film 20B can be set to 1 μm or more and 10 μm. The thickness ratio (T2 / T1) of the average thickness T2 of the second separation film 20B to the average thickness T1 of the first separation film 20A is 37.5 or less. The thickness ratio (T2 / T1) is more preferably 0.30 or more and 3.31 or less. By thus reducing the thickness ratio (T2 / T1), it is possible to suppress the occurrence of peeling and cracking in the second separation film 20B.

  In the present embodiment, the “average thickness of the separation film 20” is a value obtained by arithmetically averaging measurement values at four locations separated by 90 degrees around the central axis in a cross section perpendicular to the central axis of the through hole 11. The position in the longitudinal direction to measure “the thickness of the separation membrane 20” is not particularly limited, but is preferably a position close to the first seal 30.

  The first seal 30 covers the first end surface S1 of the porous support 10. However, the first seal 30 is formed so as not to close the opening of the cell C described later. The first seal 30 suppresses the infiltration of the mixed fluid flowing into the cell C into the first end face S1. Although the first seal 30 covers one end of the side surface S3 in the present embodiment, the first seal 30 may not cover the side surface S3. The first seal 30 is made of a glass material, a resin material, or the like.

  The second seal 40 covers the second end face S2 of the porous support 10. However, the second seal 40 is formed so as not to close the opening of the cell C. The second seal 40 suppresses the infiltration of the mixed fluid into the second end surface S2. In the present embodiment, the second seal 40 covers one end of the side surface S3, but may not cover the side surface S3. The second seal 40 is made of a glass material, a resin material, or the like.

(Configuration of first and second seals 30, 40)
The configuration of the first and second seals 30 and 40 will be described. Since the first seal 30 and the second seal 40 have the same configuration, the configuration of the first seal 30 will be described below. Further, since the configuration of the first seal 30 around the first through hole 11A and the periphery of the second through hole 11B is the same, the configuration of the first seal 30 around the second through hole 11B will be described below.

  FIG. 3 is a cross-sectional view taken along line B-B of FIG. The first seal 30 has a main body 31 and an extension 32.

  The main body portion 31 is disposed on the first end surface S1 of the porous support 10, and covers the first end surface S1. The main body portion 31 is located outside the second through hole 11B in a plan view of the first end surface S1.

  The extension portion 32 is integrally formed with the main body portion 31. The extension portion 32 is formed in an annular shape. The extension portion 32 is located inside the second through hole 11B in a plan view of the first end surface S1. The extension portion 32 is not disposed on the first end surface S1 and does not cover the first end surface S1.

  The thickness W1 of the extending portion 32 in the radial direction centering on the central axis AX2 of the second through hole 11B is preferably smaller than 30 μm, and more preferably smaller than 20 μm. As described above, by reducing the thickness W1 of the extending portion 32, the through-air drying is more efficiently performed and the thickening is suppressed, so that peeling and cracking are less likely to occur in the second separation film 20B.

  The depth W2 of the extending portion 32 in the longitudinal direction parallel to the central axis AX2 of the second through hole 11B is preferably greater than 1000 μm, and more preferably greater than 1500 μm. As described above, by increasing the thickness W2 of the extending portion 32, the through-air drying is more efficiently performed, and in particular, the thickening of the interface between the first seal 30 and the film is suppressed. And cracking is less likely to occur.

(Method of manufacturing separation membrane structure 100)
Next, a method of manufacturing the separation membrane structure 100 will be described. FIG. 4 is a schematic view for explaining the method for producing the separation membrane structure 100. As shown in FIG.

  First, a green body including a porous material is used to form a compact of the porous support 10 having a plurality of through holes 11. As a method of producing the molded object of the porous support 10, a press molding method or a cast molding method can be used besides the extrusion molding method using a vacuum extrusion molding machine.

  Next, the molded body of the porous support 10 is fired (for example, 900 ° C. to 1450 ° C., 1 hour to 100 hours) to form the porous support 10.

  Next, water and an organic binder are mixed in a glass frit to prepare a sealing slurry.

  Next, a sealing slurry is applied to the first end face S1 and the second end face S2 of the porous support 10 to form a molded body of the first seal 30 and the second seal 40. At this time, the thickness W1 of the extension portion 32 can be reduced by lowering the viscosity of the sealing slurry, and the depth W2 of the extension portion 32 can be increased by increasing the dip depth of the support to the spray slurry. Can be increased.

  Next, the compact of the first seal 30 and the second seal 40 is fired (800 to 1000 ° C., 1 hour to 100 hours) to form the first seal 30 and the second seal 40.

  Next, the separation membrane 20 is formed on the inner surface of each through hole 11 of the porous support 10. Hereinafter, the case where a titania film (an example of a UF film) is formed as the separation film 20 will be described.

First, a coating solution (ceramic sol solution) 20a for forming a UF film is prepared. The coating solution 20a can be obtained by diluting the sol stock solution with isopropyl alcohol or an aqueous solution thereof. The sol stock solution is mixed with water while maintaining a mixture of metal alkoxide (for example, titanium tetraisopropoxide) and nitric acid or hydrochloric acid at 2 ° C to 10 ° C, and the holding temperature is further adjusted to 10 ° C to 40 ° C. It is obtained by mixing with isopropyl alcohol which has been mixed. The viscosity of the coating liquid 20 a can be 4.0 × 10 ⁻⁴ Pa · s or more.

  Next, the coating solution 20 a is poured into each through hole 11. The coating liquid 20a adheres to the inner surface of each through hole 11 while flowing down by its own weight. Excess coating solution 20 a flows out from each through hole 11.

  Next, the through holes 11 are ventilated to dry the coating solution 20 a. The drying step includes a first drying step of making the wind speed in the second through hole 11B faster than that of the first through hole 11A, and a second drying step of making the wind speed in the first through hole 11A faster than the first drying step. .

  In the first drying step, as shown in FIG. 4, the openings (entrances) of the plurality of first through holes 11A are covered with a mask 50 and ventilated. As a result, the wind velocity in the second through hole 11B becomes faster than the wind velocity in the first through hole 11A, and the excess coating liquid 20a attached to the inner surface of the second through hole 11B is efficiently discharged.

  The feed air velocity in the first drying step is preferably faster than 2 m / sec and slower than 30 m / sec. By making the wind speed faster than 2 m / sec, it is possible to suppress that the pore diameter becomes too large because the film is densified. By making the wind speed slower than 30 m / sec, it is possible to suppress the occurrence of cracks on the film surface. The temperature of the wind is preferably about 10 ° C to 60 ° C. By setting the temperature of the wind to 10 ° C. or higher, the membrane is densified, and it is possible to suppress an excessively large pore diameter. By setting the temperature of the wind to 60 ° C. or less, generation of cracks on the film surface can be suppressed. Ventilation time can be about 0.5 hours to 15 hours. The ventilation direction may be the same as the flow direction of the coating solution 20a, or may be opposite to the flow direction of the coating solution 20a.

  The mask 50 may be in close contact with the first seal 30 or may be slightly separated from the first seal 30. The coverage by the mask 50 is preferably 50% or more of the total opening area of the plurality of through holes 11, and more preferably 70% or more. The coverage by the mask 50 is preferably 90% or less of the total opening area. The coverage by the mask 50 is a value obtained by dividing the area of the opening overlapping the mask 50 among the total openings by the total opening area when the first end face S1 or the second end face S2 of the porous support 10 is viewed in plan. It is. In the present embodiment, since 19 first through holes 11A of the 37 through holes 11 are closed, the coverage by the mask 50 is 51%.

  The material of the mask 50 is not limited as long as it becomes wind resistance and does not deform and deteriorate due to air temperature, but it is preferable to have acid resistance and alkali resistance. As the mask 50, for example, a Teflon (registered trademark) sheet, a stainless steel plate, a composite in which silicon or viton rubber is attached to a stainless steel plate, or the like is preferable.

  The form of the mask 50 is not limited to the dense form which can completely block the wind, but may be a part of the wind such as a porous form or a mesh form. When the porous or mesh mask 50 is used, the wind speed in each of the first and second through holes 11A and 11B can be adjusted independently.

  In the second drying step, the mask 50 is removed and ventilated. As a result, the air velocity in the first through hole 11A is faster than in the first drying step, and the coating liquid 20a attached to the inner surface of the first through hole 11A is efficiently dried. At this time, the wind speed in the second through holes 11B is slower than in the first drying step, but a wind speed sufficient to dry the sol 20a is maintained.

  Next, the temperature is raised to 350 ° C. to 950 ° C. at 100 ° C./hr and held for 1 hour, and then the temperature is lowered at 100 ° C./hr. When the size of the porous support 10 is large, the temperature increase rate and the temperature decrease rate may be reduced.

  The titania film is formed by repeating the above-described operations of pouring the coating solution 20a, drying, temperature raising and temperature lowering one to five times.

(Other embodiments)
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

  In the above embodiment, the mask 50 closes all the through holes within the range of the predetermined distance L from the central axis AX1 of the porous support 10 and blocks all the through holes outside the range of the predetermined distance L. There is no, but it is not limited to this.

  The mask 50 closes at least one through hole 11 of the plurality of through holes 11 and does not close the through hole 11 located at a position farther from the central axis AX1 than the closed through holes 11. Good. In this case, the through holes 11 closed by the mask 50 correspond to the first through holes 11A within a predetermined distance from the central axis AX1, and the through holes 11 not closed by the mask 50 are predetermined from the central axis AX1. It corresponds to the second through hole 11B outside the distance. Even in this case, the wind speed of the second through hole 11B can be made faster than that of the first through hole 11A in the first drying step.

  Therefore, a notch or a hole may be formed in the mask 50, and the mask 50 may have a shape other than a perfect circle. For example, in the case where the first and second end faces S1 and S2 are non-circular, the mask 50 may be similar in shape to the first and second end faces S1 and S2.

  In the above embodiment, in the first drying step, the opening at the entrance of the second through hole 11B is closed by the mask 50, but the opening at the exit may be closed by the mask 50. Even in this case, the wind speed in the second through hole 11B can be reduced.

  Although the coating liquid for forming a titania film was mentioned as an example and demonstrated in the said embodiment as a solution for separation film formation, it is not restricted to this. As a solution for forming a separation membrane, it is used for forming a seeding slurry (suspension containing a seed crystal) used for forming a zeolite membrane, a silica sol solution (coating liquid) used for forming a silica membrane, and a carbon membrane A polyamic acid solution, a sol solution for forming an organic-inorganic hybrid silica, a sol solution used for forming a p-tolyl group-containing silica film, and the like can be mentioned.

  In the above embodiment, the coating solution for forming the titania film is deposited by the flow-down method, but the dip method or the like may be used.

  Although not particularly mentioned in the above embodiment, the separation membrane structure 100 may have an intermediate layer between the porous support 10 and the separation membrane 20. The middle class is described in detail in WO 2013/059146. When the separation membrane structure 100 has an intermediate layer, the inside of the intermediate layer is the through hole 11.

  Examples of the present invention will be described below. However, the present invention is not limited to the embodiments described below.

(Preparation of sample Nos. 1 and 2)
As in the following, sample no. The separation membrane structure concerning 1, 2 was produced.

  First, a porous support (diameter 30 mm × length 160 mm, average pore diameter 0.10 μm) in which 55 through holes were formed was prepared.

  Next, water and an organic binder were mixed in a glass frit to prepare a sealing slurry.

  Next, the sealing slurry was attached to both end surfaces of the support, and then dried (30 ° C., 12 hours) to form a pair of sealed compacts.

  Next, the compact of the pair of seals was fired at 950 ° C. to form a pair of seals.

Next, mix titanium tetraisopropoxide and nitric acid with water while maintaining the temperature at 5 ° C, and further mix with isopropyl alcohol (IPA) previously mixed with nitric acid in a state where the holding temperature is 20 ° C. Thus, a sol stock solution containing titania was prepared.

Next, the sol stock solution was diluted with IPA to obtain a coating solution with an IPA concentration of 99 wt%. The viscosity of the coating liquid was 1.5 × 10 ⁻⁴ Pa · s.

  Next, the coating solution was poured into a wide-mouthed funnel disposed above the vertically placed support, and the coating solution was poured into each through hole.

  Next, air at 25 ° C. was ventilated at a wind speed of 10 m / sec for 30 minutes (first drying step). Sample No. In No. 1, ventilating in a state where the openings of all through holes are open, sample No. In the case of No. 2, the area around the center was closed with a mask so that the coverage area ratio was 50%, and ventilation was performed.

  Next, air was blown at 25 ° C. for 30 minutes at a wind speed of 10 m / sec (second drying step). Sample No. In the case of No. 1, the area around the center is closed with a mask so that the coverage area ratio is 50%, and ventilation is performed. In 2, the air was ventilated in a state in which the openings of all the through holes were opened.

  Next, after standing-drying at 80 ° C., baking was performed at 500 ° C. to form a titania film as a separation film.

(Preparation of samples No. 3 to 21)
First, sample no. The same support as 1 and 2 was prepared.

  Next, water and an organic binder were mixed in a glass frit to prepare a sealing slurry.

  Next, the sealing slurry was attached to both end surfaces of the support, and then dried (30 ° C., 12 hours) to form a pair of sealed compacts. At this time, sample no. In 15, 16, the thickness W 1 of the extension 32 was made larger than that of the other samples by increasing the viscosity of the sealing slurry. Sample No. At 17 and 18, the depth W2 of the extension 32 was made smaller than that of the other samples by reducing the dip depth of the support into the sealing slurry.

  Next, the pair of seals was formed by firing the pair of seals at 950 ° C.

  Next, titanium isopropoxide was added to deionized water to hydrolyze at a temperature of about 85 ° C. for 0.5 hours.

  Next, nitric acid was added to the hydrolyzed solution to obtain a sol solution in which titania was used as colloidal particles.

  Next, the sol solution was heated to disperse isopropyl alcohol and diluted to prepare a sol solution.

Next, using the sol solution as a stock solution, a coating solution of water, raw material particles, polyvinyl alcohol as an organic binder, and n-octyl alcohol as an antifoamer was prepared. The viscosity of the coating solution was 4.0 × 10 ⁻⁴ Pa · s.

  Next, the coating solution was poured into a wide-mouthed funnel disposed above the vertically placed support, and the coating solution was poured into each through hole.

  Next, air at 25 ° C. was ventilated for 30 minutes at the wind speed shown in Table 1 (first drying step). Sample No. In 4,21, ventilation was carried out in a state in which the openings of all the through holes were open, and sample Nos. In 3 and 5 to 20, the area around the center was covered with a mask and ventilated so as to obtain the coverage area ratio shown in Table 1.

  Next, air was blown at 25 ° C. for 30 minutes at a wind speed of 10 m / sec (second drying step). Sample No. In No. 4, the area around the center was closed with a mask and ventilated so that the coverage area ratio was 70%. In 3, 5 to 21, ventilation was performed with the openings of all through holes opened.

  Next, the temperature was raised to 500 ° C. at 100 ° C./hr and held for 1 hour, and then the temperature was lowered at 100 ° C./hr.

  Then, the operation of pouring the coating solution, drying, and temperature raising and lowering was repeated twice to form a titania film as a separation film.

(Measurement of thickness of separation membrane)
As in the following, sample no. The thickness of the separation membrane of 3, 4, 9 to 16, 21 was measured. Here, the thickness of the separation membrane (hereinafter referred to as "the outermost circumference separation membrane") located at the outermost periphery where the thickness difference tends to be the largest and the thickness of the separation membrane (hereinafter referred to as the "central separation membrane") located at the center are described. It measured and compared.

  First, the whole support was cut at a position close to the extension of the seal in the separation membrane.

  Next, the cut surface is observed with a scanning electron microscope, and one separation film located at the outermost periphery (hereinafter referred to as "the outermost periphery separation film") is separated by 90 degrees around the central axis of the through hole The arithmetic mean value of the measured values at four locations was calculated as the average thickness.

  Next, the cut surface is observed with a scanning electron microscope, and in one central separation film (hereinafter referred to as “central separation film”), four points separated by 90 degrees around the central axis of the through hole The arithmetic mean value of the measured values in was calculated as the average thickness.

(Measurement of the size of the extension of the seal)
Sample No. For each of 1 to 21, the support was cut along the central axis of one through hole located at the outermost periphery, and the thickness and depth (see FIG. 3) of the extension of the seal were measured.

  The extension of the seal is a portion located inside the through hole in a plan view of the end face of the support.

(Measurement of degree of vacuum)
In order to check the amount of defects in the separation membrane, the degree of vacuum of the cell was measured.

First, from one end of the cell to a vacuum pump (manufactured by ULVAC KIKO, Inc .: direct-coupled oil rotary vacuum pump, model number: G-20DA, exhaust speed 24 L / min, ultimate pressure 1.3 × 10 ^-1 Pa, two-stage type) The final vacuum degree in the cell was measured with a vacuum gauge (manufactured by GE Sensing, Inc .: calibrator, model number: DPI 800) connected to the other end of the cell.

  Those with a degree of vacuum greater than -25 kPa are evaluated as x (improper), those with -25 kPa or less greater than -40 kPa are evaluated as Δ (acceptable), those with a degree of vacuum less than -40 kPa are evaluated as ○ (good). And those below -70 kPa were evaluated as ◎ (excellent).

As shown in Table 1, sample nos. In 1 and 2, since the viscosity of the coating liquid was as low as 1.5 * 10 <^-4> Pa.s, the favorable result was obtained irrespective of the presence or absence of a mask.

Sample No. 1 in which the thickness ratio of the average thickness of the central separation membrane to the average thickness of the outermost separation membranes is 40 or more. In 4, 21, the degree of vacuum was low because the outermost peripheral separation film had a defect. This is because, although the viscosity of the solution for film formation was as high as 4.0 × 10 ⁻⁴ Pa · s, ventilation was performed without using a mask in the first drying step, so extra coating adhered to the outermost through holes It is because the liquid could not be blown away.

  On the other hand, sample No. 3 with a thickness ratio of 37.5 or less. In 3, 9 to 16, since the defect of the outermost peripheral separation film was suppressed, the degree of vacuum could be improved. This is because the mask was used to ventilate in the first drying step, so that the excess coating liquid attached to the outermost through holes could be blown away. In particular, sample No. 1 in which the thickness ratio was 0.30 or more and 3.31 or less. For 3, 10, 15, and 16, the degree of vacuum could be further improved.

  Also, for sample no. From the comparison of 3, 9 to 16, it was found that the average thickness of the outermost peripheral separation membrane is preferably 1 μm to 10 μm.

  Also, for sample no. From the comparison of 3, 5, and 6, it was found that in the first drying step, it is preferable to close 50% or more of the total opening area with a mask, and it is more preferable to close 70% or more with a mask.

  Also, for sample no. From the comparison of 3, 7, and 8, it was found that the wind speed of the air supplied in the first drying step is preferably faster than 2 m / sec and slower than 30 m / sec.

  Also, for sample no. From the comparison of 3, 17 and 18, it was found that the thickness of the extension of the seal is preferably less than 30 μm, and more preferably less than 20 μm.

  Also, for sample no. From a comparison of 3, 19, 20, it was found that the depth of the extension of the seal is preferably greater than 1000 μm, and more preferably greater than 1500 μm.

100 separation membrane structure 10 porous support 11 through hole 11A first through hole 11B second through hole 20 separation membrane 20A first separation membrane 20B second separation membrane 30 first seal 31 main body portion 32 extension portion 40 second portion seal

Claims (6)

A support forming step of forming a porous support having a plurality of through holes respectively connected to the first end face and the second end face;
^{Attaching a} solution for forming a separation membrane having a viscosity of 4.0 × 10 ⁻⁴ Pa · s or more on the inner surface of each of the plurality of through holes;
A drying step of ventilating the plurality of through holes to dry the separation membrane forming solution;
Equipped with
The drying step is
The wind speed in the second through hole located outside the predetermined distance from the central axis is made faster than the first through hole located in the predetermined distance from the central axis of the porous support among the plurality of through holes A first drying step,
After the first drying step, a second drying step in which the wind speed in the first through hole is made faster than in the first drying step;
including,
Method for producing separation membrane structure. In the first drying step, the supplied wind speed is made faster than 2 m / s and slower than 30 m / s,
The manufacturing method of the separation membrane structure according to claim 1 . In the first drying step, by covering the opening of the through hole within the predetermined distance from the central axis among the plurality of through holes with a mask, 50% or more of the total opening area of the plurality of through holes is closed.
The manufacturing method of the separation membrane structure of Claim 1 or 2 . In the first drying step, by covering the opening of the through hole within the predetermined distance from the central axis among the plurality of through holes with a mask, 70% or more of the total opening area of the plurality of through holes is closed.
The manufacturing method of the separation membrane structure of Claim 1 or 2 . Between the support forming step and the attaching step, a seal having a main body portion covering the first end surface and an extending portion positioned inside the second through hole in plan view of the first end surface is formed. Seal forming process,
In the seal forming step, an average thickness of the extension in a radial direction centering on a central axis of the second through hole is made smaller than 30 μm.
The manufacturing method of the separation membrane structure according to any one of claims 1 to 4 . Between the support forming step and the attaching step, a seal having a main body portion covering the first end surface and an extending portion positioned inside the second through hole in plan view of the first end surface is formed. Seal forming process,
In the seal formation step, the average depth of the extension in an axial direction parallel to the central axis of the second through hole is made larger than 1000 μm.
A manufacturing method of the separation membrane structure according to any one of claims 1 to 5 .

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