JP4968990B2 - Manufacturing method of inorganic separation membrane - Google Patents

Description

【００４８】
試料Ｎｏ．２〜６、８〜１７、１９〜２１及び２４は、水の透過流速が４３ｍｌ／（ｍ^２・ｈ・ｋＰａ）以上、阻止率が６１％以上であった。
【００４９】
一方、焼成温度が３００℃と低く、細孔容積が０．１２ｍｌ／ｇと小さい試料Ｎｏ．１は、水の透過流速が１３ｍｌ／（ｍ^２・ｈ・ｋＰａ）と低い値であった。
【００５０】
また、焼成温度が１１００℃と高く、細孔容積が０．０３ｍｌ／ｇと小さい試料Ｎｏ．７は、水の透過流速が４．４ｍｌ／（ｍ^２・ｈ・ｋＰａ）と低い値であった。
【００５１】
さらに、溶媒に水を用いた試料Ｎｏ．１８は、アルコキシド混合物を作製する際に沈殿が生じ、加水分解工程を行えず、ゾルを作製することが出来なかった。
【００５２】
さらにまた、カルボン酸無水物を入れない試料Ｎｏ．２２は、２Ｄ以下の細孔を有する細孔容積が全容積の７２％であり、ＰＥＧ４００の阻止率が４８％、ＰＥＧ２０００の阻止率が５９％と低い値であった。
【００５３】
また、カルボン酸無水物の代わりにＮ，Ｎジメチルエタノールアミンを加えた試料Ｎｏ．２３及び加水分解温度が８０℃と高い試料Ｎｏ．２５は、ゾルの合成段階で白濁し、沈殿物が生じ、均一なゾルの作製が出来ず膜を付与することが出来なかった。
【００５４】
さらに、粉末を用いて成膜した試料Ｎｏ．２６は、平均細孔径が２３ｎｍと大きく、ＰＥＧ阻止率が５９％以下と低かった。
【００５５】
【発明の効果】
本発明の無機分離膜の製造方法では、平均細孔径、細孔容積及び細孔容積の分布を制御した無機分離膜が得られ、このような無機分離膜は、ポリマー除去を高い分離精度で行うことができ、耐薬品性、耐圧性に優れかつ高い透過、分離（阻止率）の両性能を有する無機分離膜として用いることができる。
【図面の簡単な説明】
【図１】本発明の限外濾過膜の構造を示す概略断面図である。
【図２】実施例で用いた透過流速測定装置の構造を示す概略断面図である。
【符号の説明】
１１・・・限外濾過膜
１２・・・無機分離膜
１３・・・支持体
１４・・・ハウジング
１５・・・供給口
１６・・・排出口
１７・・・透過出口[0001]
BACKGROUND OF THE INVENTION
The present invention, ultrafiltration is relates to the manufacture how the inorganic separation membrane with excellent separation performance utilized in microfiltration or the like.
[0002]
[Prior art]
Conventionally, filtration membranes and separation membranes made of porous materials made of various materials including organic materials have been used for ultrafiltration and microfiltration.
[0003]
In recent years, there has been an increasing demand for simplification of treatment of waste liquid containing a polymer such as photoetching waste liquid and reuse of the solvent, and the need for a filtration membrane for removing the polymer dissolved in the solvent is increasing.
[0004]
However, as the demand for chemical resistance, pressure resistance, wear resistance, heat resistance, and the like for the porous body is gradually increased, various inorganic materials composed of ceramics having excellent chemical, mechanical, and thermal stability. Porous separation membranes have attracted attention and have been studied in various ways.
[0005]
As a result, various performances obtained with the above-mentioned conventional filtration membranes and separation membranes made of porous materials are also increasing in inorganic porous separation membranes, and particularly high separation accuracy, filtration accuracy and permeation flow rate are required. Yes.
[0006]
As a separation membrane and a filtration membrane made of this kind of inorganic porous material, for example, in Japanese Patent Application Laid-Open No. 5-146648, a metal oxide, a metal carbide, a metal nitride, or a mixture thereof is formed on a support material by thermal evaporation using an electron beam. Describes an inorganic film in which at least 90% of the pores of the inorganic film have a pore diameter of 1.2 nm or less.
[0007]
In JP-A-4-160073, the ratio R / r between the maximum pore diameter R and the average pore diameter r produced by firing a ceramic molded product is 5 or less, and the maximum pore diameter is 0.8. A filter made of porous ceramics of 1 μm or less is described.
[0008]
[Problems to be solved by the invention]
However, as disclosed in JP-A-5-146648, an inorganic membrane having a pore size of 1.2 nm or less and having a pore size of 90% or more has a very narrow pore size distribution. In order to use it as an ultrafiltration membrane, the pore diameter is too small and the pore volume is generally small, so the permeation flow rate is significantly reduced, and in some cases even the solvent to be permeated is permeated. There was a problem of not getting.
[0009]
On the other hand, as in JP-A-4-160073, in a filter produced by molding and firing inorganic ceramic powder, there is a technique for narrowing the pore size distribution, but the ratio R / r is 5 or less. The pore size distribution cannot be controlled narrowly, and the pore size becomes large, and even if finely controlled, the limit is about 0.01 μm, so the purpose is to remove the polymer with a molecular weight cut off of 100 to 10,000. However, it does not function as an ultrafiltration membrane, and there is a problem that almost no blocking rate representing the polymer removal performance is obtained.
[0010]
An object of the present invention, a polymer such fractional molecular weight 100 to 10000 that dissolved in the solvent can be removed with high separation accuracy is that the permeation rate of the solvent is to provide a manufacturing how high the inorganic separation membrane.
[0011]
[Means for Solving the Problems]
The present invention is based on the knowledge that by performing hydrolysis at low temperature, a uniform sol without aggregation can be produced. An inorganic separation membrane produced using this is suitable for separation and removal of polymers, Excellent chemical and pressure resistance and high permeation flow rate.
[0013]
The method for producing an inorganic separation membrane of the present invention comprises a mixture of an aluminum alkoxide having a purity of 95% or more, an alcohol having a purity of 99.5% or more, and a carboxylic acid anhydride having a purity of 97% or more at a temperature of 60 ° C. or less. The sol is prepared by hydrolyzing with, and the obtained sol is applied to the outer surface and / or inner surface of the porous support tube, dried, and then fired at a temperature of 400 to 1000 ° C. Is. As a result, the dispersibility of alkoxide in water can be improved and a uniform hydrolysis reaction can be promoted, so that the particle size distribution of the formed boehmite sol made of aluminum hydroxide (AlOOH) can be narrowed, and after firing. The resulting alumina also has a narrow alumina particle size distribution, resulting in a very narrow pore size distribution.
[0014]
In particular, the mixture is preferably prepared so that the molar ratio of the carboxylic acid anhydride to the alkoxide is 0.1 to 6. Thereby, the reactivity with the water of an alkoxide is reduced, and a carboxylic anhydride can be utilized without waste.
[0015]
In the hydrolysis, the molar ratio of water to the alkoxide is preferably 100 or more. Thereby, the dispersibility at the time of adding an alkoxide mixture to water can be improved, and aggregation of the alkoxide mixture and aggregation of aluminum hydroxide (AlOOH) particles after hydrolysis can be suppressed.
[0016]
Furthermore, it is preferable to prepare the sol so that the pH is 0.5 to 5. Thereby, aggregation of aluminum hydroxide (AlOOH) particles obtained after hydrolysis is suppressed, and it becomes easy to obtain sol particles of aluminum hydroxide (AlOOH) with a uniform particle diameter in a monodispersed state . Furthermore, the carboxylic acid anhydride is a carboxylic acid anhydride represented by R—CO—O—CO—R ′ (wherein R is C _n H _m , R ′ is C _a H _b , a and n are 1 to It is preferable that the integer of 5 and b and m are integers of 3-11. Thereby, the solubility with aluminum alkoxide and alcohol is high, and a uniform alkoxide mixture can be produced.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Inorganic separation membrane made of the alumina porous body has an average pore diameter D is less fine 2D relative to the average pore diameter D along with it is 0.2 ml / g or more and and a total pore volume 1.5nm~20nm the volume of pores having a pore Ru Tei accounts for over 90 percent of the total pore volume.
[0019]
Here, if the average pore diameter is smaller than 1.5 nm, the ultrafiltration membrane intended for polymer removal is too small to prevent the permeation of the solvent, and generally the pore volume is also small. The permeation flow rate is significantly reduced.
[0020]
On the other hand, when the average pore diameter is larger than 20 nm, the separation accuracy is remarkably lowered when the polymer is removed as an ultrafiltration membrane. In particular, for an ultrafiltration membrane intended to remove a polymer having a molecular weight cut off of 100 to 10000, the average pore diameter D is preferably 1.5 to 10 nm from the viewpoint of improving separation accuracy and polymer rejection.
[0021]
Further, if the total pore volume is lower than 0.2 ml / g, the permeation flow rate is lowered, and the membrane area of the separation membrane module is increased. Therefore, it is necessary to be 0.2 ml / g or more, particularly 0.3 ml / g. g or more is desirable.
[0022]
In addition, when the pore volume having pores of 2D or less with respect to the average pore diameter D is lower than 90% of the total pore volume, the separation performance as an ultrafiltration membrane is lowered, and a high polymer blocking rate of 90% or more is obtained. I can't get it. The pore volume having the pores of 2D or less is desirably 95% or more of the total pore volume from the viewpoint of particularly high separation performance and improvement of the polymer blocking rate.
[0023]
By adopting this structure, it is possible to remove a polymer having a fractional molecular weight of 100 to 10000 dissolved in the solvent with high separation accuracy, a high permeation flow rate of the solvent, and an inorganic that can be suitably used for ultrafiltration, microfiltration, etc. A separation membrane can be realized.
[0024]
Next, a method for producing the inorganic separation membrane of the present invention will be described.
[0025]
First, an aluminum alkoxide, a carboxylic acid anhydride, and an alcohol are prepared. These purities are preferably 95% or more, 97% or more, and 99.5% or more, respectively, in order to form a boehmite (AlOOH) sol that forms fine particles. When the purity is low, Al (OH) ₃ , Al salts, and the like are formed, which inhibits the uniform formation of AlOOH particles, precipitation occurs, and it is difficult to produce a uniform sol.
[0026]
As the alkoxide of aluminum, for example, ethoxide, isopropoxide, n-propoxide, n-butoxide, sec-butoxide, t-butoxide and the like can be used. In particular, solubility in alcohol, water of alcohol generated after hydrolysis It is desirable that they are isopropoxide, n-propoxide, n-butoxide, and sec-butoxide.
[0027]
Examples of the alcohol include methanol, ethanol, propanol, butanol, 2 methoxyethanol, and 2 ethoxyethanol, which have good compatibility with water, and particularly have a low boiling point in consideration of the drying process after deposition as a separation membrane. A lower alcohol is desirable.
[0028]
Moreover, carboxylic acid anhydride, when the R _C n _H m, the R _'C a _H b, an integer of 1 to 5 a and n, b and m an integer of 3 to 11, the general formula R- It is represented by CO—O—CO—R ′. Specific examples of the carboxylic acid anhydride include acetic anhydride, 2-butenoic anhydride, isopentanoic anhydride, maleic anhydride and the like.
[0029]
Next, an aluminum alkoxide, a carboxylic acid anhydride, and an alcohol are mixed. At this time, it is preferable to add 0.1 to 6 mol, particularly 1 to 5 mol, and further 2 to 4 mol of carboxylic acid anhydride with respect to 1 mol of aluminum alkoxide. Thus, by adjusting the ratio of alkoxide to carboxylic anhydride, it becomes easy to reduce the reactivity of alkoxide and improve the dispersibility during hydrolysis.
[0030]
Next, water is added to the above mixture for hydrolysis to produce a sol made of aluminum hydroxide. It is important to set the hydrolysis temperature to 60 ° C. or lower, and 50 ° C. or lower is particularly preferable from the viewpoint of promoting a uniform hydrolysis reaction. When the temperature exceeds 60 ° C., the hydrolysis proceeds rapidly, and the sol particles composed of the generated aluminum hydroxide particles are aggregated to prevent the formation of uniform sol particles. Therefore, by making it 60 degrees C or less, the rapid hydrolysis of an alkoxide can be suppressed and a dispersibility can be improved.
[0031]
The sol made of aluminum hydroxide is preferably boehmite (AlOOH) sol. Boehmite sol is soluble and can be uniformly dispersed without agglomeration of fine particles. When a porous film is formed from boehmite sol, fine and uniform pores can be easily formed. It is.
[0032]
The water used for the hydrolysis is preferably 100 mol or more, particularly 150 mol or more, and more preferably 200 mol or more with respect to 1 mol of aluminum alkoxide. Thereby, it becomes further easy to suppress the rapid hydrolysis of the alkoxide and to improve the dispersibility by preventing aggregation.
[0033]
Furthermore, allowed lowering the reactivity of the alkoxide, 0.1 to 6 moles of carboxylic anhydride relative to alkoxide 1 mole of aluminum in order to improve the dispersibility at the time of hydrolysis, in particular 1 to 5 mol, and more It is preferable to mix in the ratio of 2-4 mol . When the amount is less than 0.1 mol, the effect of improving the dispersibility tends to be small. When the amount is more than 6 mol, the reactivity of the aluminum alkoxide is remarkably lowered and the hydrolysis reaction does not proceed and a uniform sol is obtained. There is a tendency to become difficult.
[0034]
In addition, the pH of the sol prepared by hydrolysis of the aluminum alkoxide is important to be 0.5 to 5 from the viewpoint of suppressing the sol stability and aggregation between the sol particles. Is desirably 3 to 5. If the pH exceeds 5, aggregation of the sol particles proceeds and precipitation occurs, and there is a tendency that a uniform sol cannot be obtained. Also, when the pH is lower than 0.5, aggregation of the sol particles proceeds and the viscosity of the sol increases. There is a tendency that gelation proceeds and a stable sol cannot be obtained.
[0035]
The particle size of the obtained sol can be measured by a particle size analyzer using a light scattering photometer. Considering the average pore diameter of the alumina membrane, the sol particle diameter is desirably 10 nm to 100 nm.
[0036]
Next, a porous support tube is prepared. The porous support tube is porous having an average pore diameter of about 0.01 to 10 μm and serves as a substrate on which the alumina film is formed, and is preferably excellent in chemical resistance and pressure resistance. And those made of α-alumina, zirconia, silica, silicon nitride, glass, etc. are used. Among these, α-alumina is particularly desirable in terms of close thermal expansion to the alumina film.
[0037]
A sol is deposited on at least one surface of the porous support tube. As the deposition method, methods such as dip coating and spray coating can be used.
[0038]
It is important that the separation membrane precursor is baked after drying at a temperature of 400 ° C. to 1000 ° C. Particularly, the baking at 400 ° C. to 800 ° C. is desirable from the viewpoint of a large pore volume and an increased permeation flow rate. Note that, at a firing temperature lower than 400 ° C., the crystallization of alumina is low, the chemical resistance is lowered, and organic substances remain and uniform pores are not formed. In addition, when the firing temperature exceeds 1000 ° C., the alumina transitions to the α phase, the sintering of the alumina particles proceeds, the pore volume is significantly reduced, and the permeation flow rate is significantly reduced.
[0039]
The separation membrane thus produced has a total pore volume of 0.2 ml / g or more, an average pore diameter D of 1.5 to 20 nm, and a pore volume having pores of 2D or less of the total pore volume. It can be 90% or more.
[0040]
As shown in FIG. 1, limited outside the filtration membrane 11 is an inorganic separation membrane 12 made according to the present invention is provided in the housing 14 so as to be held on the support member 13, at least two of the mixed fluid, such as water The polymer fluid flows in from the supply port 15, contacts the inorganic separation membrane 12, and the polymer having a molecular number of 100 to 10000 is discharged as it is from the discharge port 16, but water passes through the inorganic separation membrane 12. It can be taken out from the permeation outlet 17. Thus, limited outside the filtration membrane 11 can be separated efficiently polymer molecular number 100 to 10,000.
[0041]
【Example】
First, aluminum alkoxide, alcohol, carboxylic acid anhydride, and ion exchange distilled water were prepared. In an N ₂ flow glove box, an alkoxide mixture was prepared by mixing an aluminum alkoxide with an alcohol and a carboxylic acid anhydride in the ratio shown in Table 1.
[0042]
After the alkoxide mixture was taken out of the glove box, the alkoxide mixture was added at a time while vigorously stirring water maintained at the temperature shown in Table 1, and hydrolysis was performed under the conditions shown in Table 1 to obtain an alumina precursor. A sol was obtained.
[0043]
Next, a small amount of each sol is collected, dried and fired under the same conditions for imparting a film, and the average pore diameter D and the total pore volume V are measured by the N ₂ adsorption method (ASAP2000 manufactured by Micromeritics) The ratio of the pore volume having pores of 2D or less to the total pore volume V was calculated.
[0044]
In addition, a separation membrane evaluation sample was prepared. That is, an α-alumina porous tube having an average pore diameter of 0.15 μm, a porosity of 38%, a length of 200 mm, an outer diameter of 3 mm, and an inner diameter of 2.2 mm was immersed in an alumina precursor sol for 30 seconds and dried at room temperature for 1 hour. Then, it kept at 500 degreeC continuously for 1 hour, and cooled to room temperature after that. This series of operations of dipping, drying, and firing was repeated four times, and an alumina membrane was deposited on the α-alumina porous tube to produce an inorganic separation membrane.
[0045]
Next, as shown in FIG. 2, the obtained tubular samples for evaluation 21 are attached to a permeation flow rate measuring device 22, an aqueous solution in which polyethylene glycol (PEG) is dissolved is introduced from the supply inlet 23, and the inorganic separation membrane 24 is introduced. A back pressure valve is provided at the supply outlet 25 so that a pressure of 1 MPa is applied to the outside, and the amount of water permeated inside the inorganic separation membrane 24 is measured at the permeation outlet 26 to determine the permeation flow rate (ml / (m ² · h · kPa)). Asked.
[0046]
As PEG, polyethylene glycol having molecular weights of 400, 2000, and 6000 was used. Moreover, the blocking rate measured the polyethyleneglycol density | concentration of the water of the permeated solution, and made this into blocking rate. The results are shown in Table 1.
[0047]
[Table 1]

[0048]
Specimen No. In Nos. 2 to 6, 8 to 17, 19 to 21 and 24, the water permeation flow rate was 43 ml / (m ² · h · kPa) or more, and the rejection was 61% or more.
[0049]
On the other hand, the firing temperature is as low as 300 ° C., a pore volume of 0.12 ml / g and small I試 fee No. 1 had a low water permeation flow rate of 13 ml / (m ² · h · kPa).
[0050]
The firing temperature is as high as 1100 ° C., a pore volume of 0.03 ml / g and small I試 fee No. In No. 7, the water permeation flow rate was a low value of 4.4 ml / (m ² · h · kPa).
[0051]
Moreover, specimen using water as a solvent No. In No. 18, precipitation occurred when producing the alkoxide mixture, the hydrolysis process could not be performed, and the sol could not be produced.
[0052]
Furthermore, I試 charges such put carboxylic acid anhydride No. No. 22 had a pore volume having pores of 2D or less of 72% of the total volume, PEG400 blocking rate was 48%, and PEG2000 blocking rate was as low as 59%.
[0053]
Also, specimen was added N, N-dimethylethanolamine in place of the carboxylic acid anhydride No. 23 and hydrolysis temperature is 80 ° C. and high I試 fee No. No. 25 became cloudy at the synthesis stage of sol, and a precipitate was formed, so that a uniform sol could not be produced and a film could not be formed.
[0054]
Moreover, specimen was formed using powder No. No. 26 had a large average pore diameter of 23 nm and a low PEG rejection of 59% or less.
[0055]
【Effect of the invention】
The method of producing an inorganic separation membrane of the present invention, a flat HitoshiHoso pore size, inorganic separation membrane is obtained with controlled distribution of pore volume and pore volume, the inorganic separation membranes, high separation precision polymer removal And can be used as an inorganic separation membrane having excellent chemical resistance and pressure resistance and high permeation and separation (rejection rate) performance.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing the structure of an ultrafiltration membrane of the present invention.
FIG. 2 is a schematic cross-sectional view showing the structure of a permeation flow velocity measuring apparatus used in Examples.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Ultrafiltration membrane 12 ... Inorganic separation membrane 13 ... Support body 14 ... Housing 15 ... Supply port 16 ... Discharge port 17 ... Permeation outlet

Claims (5)

A mixture of an aluminum alkoxide having a purity of 95% or more, an alcohol having a purity of 99.5% or more, and a carboxylic acid anhydride having a purity of 97% or more is hydrolyzed at a temperature of 60 ° C. or less to produce a sol, A method for producing an inorganic separation membrane, wherein the obtained sol is deposited on the outer surface and / or inner surface of a porous support tube, dried and then fired at a temperature of 400 to 1000 ° C. Method of producing an inorganic separation membrane of claim 1 wherein the molar ratio of carboxylic acid anhydride to said alkoxide is characterized in that to produce the mixture so as to 0.1-6. The method for producing an inorganic separation membrane according to claim 1 or 2 , wherein in the hydrolysis, a molar ratio of water to the alkoxide is 100 or more. The method for producing an inorganic separation membrane according to any one of claims 1 to 3 , wherein the sol is prepared so as to have a pH of 0.5 to 5. The carboxylic acid anhydride is a carboxylic acid anhydride represented by R—CO—OCO—R ′ (where R is C _n H _m , R ′ is C _a H _b , a and n are integers of 1 to 5, b And m is an integer of 3 to 11). The method for producing an inorganic separation membrane according to any one of claims 1 to 4 , wherein:

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