JPS59186606A - Manufacture of separation membrane - Google Patents

Abstract

PURPOSE:To obtain the separation membrane having a high separation performance along with a high permeation velocity by film-forming a soln. of a polymeric material which is filtered with a microfilter having <=6mu maximum bore. CONSTITUTION:The gas separation membrane is manufactured by film-forming a soln. of a polymeric material which is filtered by a microfilter having <=6mu maximum bore and consists especially of a mixture of polyorganosilane and organopolysiloxane. In manufacturing the gas separation membrane, since the floating dust or a foreign matter such as insoluble polymer in the soln. is removed by the above-mentioned microfilter, the generation of defective parts is prevented in the dense layer of an asymmetric membrane which consists of a single layer consisting solely of the dense layer showing a selective gas separation property, or which consists of two layers of the dense layer and a porous layer showing no selective separation property and united to the dense layer. Thus the dense layer having extremely thin thickness can easily be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a separation membrane. Even more tragically, by filtering the film-forming bath liquid through a specific microfilter,
The present invention relates to a method for producing a separation membrane having good permeation rate and separation performance at the same time.

The pre-prepared membrane obtained by this method is a metal material,
Since it exerts its power over 1m of selective gas mixture in %,
The gas component If Mx K will be explained below.

In recent years, continuous methods using synthetic polymer membranes have attracted attention as a means of enriching or separating specific gases from gas mixtures, and are being actively researched for practical use. For example, for combustion by separating and concentrating oxygen or nitrogen from air,
Production of oxygen-enriched air for medical use, wastewater treatment, fermentation, etc., separation and recovery of helium q from natural gas, etc., separation of hydrogen from coke gas, etc.

However, conventional membranes require a large membrane area due to the low gas permeation rate, and require large separation equipment.
) has the disadvantage of becoming

Therefore, while the "magical method of increasing the area of the ringing membrane per ram" has been implemented, the essential membrane that greatly increases the permeation rate while maintaining high selectivity is being implemented. Improvements were desired.

The gas permeation rate R (cc/-·Water·amHg) is expressed as H. However, P is the transmission coefficient 1f (cc/m), S is the membrane area (cfI), and ΔP is the pressure difference between the primary and secondary sides of the membrane. Therefore, if the pressure difference ΔP between the zero gas permeation rate R and the flank f is constant, it depends on the gas permeation coefficient eP and the thickness of the legs. Among these, the permeability coefficient is uniquely determined by the gas C3 and the polymer membrane material used, so as long as the membrane can withstand the pressure difference at d, the maximum permeation rate can be obtained by minimizing the membrane thickness.

Among conventional gas separation membrane materials, Tokko Sho & 7-6/7/J
' No., same pigeon, 2. The polyvinyltriorganosilane described in the /0.2/ publication had good gas separation performance, but its permeability coefficient was small and insufficient. A mixture of polyvinyltriorganosilane and polysiloxane has been proposed as a material to improve the drawback of such low gas permeability, as disclosed in Japanese Patent Application Laid-Open No. It was proposed in Publication No. f.

When the mixture was used as a material for a gas separation membrane, it exhibited improved gas separation performance on the high permeation rate side compared to a polyvinyltriorganosilane membrane. However, if the % permeation rate was still increased, the gas separation performance tended to drop rapidly and significantly.Such drawbacks are common not only to gas separation but also to the separation of liquids and other mixtures. This is a problem that needs to be improved.

Therefore, the present inventors have conducted extensive research into a method of destroying and drying a separation membrane that has as high a permeation rate as possible while maintaining separation performance. We have discovered a method of manufacturing a separation membrane that has improved separation membrane performance and permeation rate, which was previously unobtainable, by forming the membrane using a solution.
We have arrived at the present invention.

The gist of the present invention resides in a method for producing a bulk membrane, which is characterized in that the membrane is formed using a 1ptZ,S solution of polymeric agricultural phase filtered through a microfilter with a maximum pore size of 6μ or less.

Hereinafter, the present invention will be explained in detail by taking as an example a method for manufacturing a gas separation membrane using a mixture of polyvinyltriorganosilane and organopolysiloxane as a polymer membrane material. It is not limited. That is, the present invention is also applicable to the case where films are formed using conventionally known polymer membrane materials, such as celluloses such as cellulose acetate ethyl cellulose, polysulfone, and polyphenylene oxide.
The specific polyvinyltriorganosilane used in the present invention has the formula (1)% (1) (where R1 represents a hydrogen atom, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, and R2 and Rs A size that represents an alkyl group, cycloalkyl group, aryl group, or aralkyl group.

Even if R1, R2 and R3 are mutually 1h KP+-,
A polymer compound containing a certain number of structural units represented by
/f or more, good luck 1-<ke/,! ~g, sdl/y. If the intrinsic viscosity of polyvinyltriorganosilane is less than /, Odi/9, the mechanical strength of the gas separation membrane obtained is not only low, but also the separation performance in the high permeation rate region is extremely low, making it impractical. By the way.

The above-mentioned polyvinyltriorganosilanes are generally obtained by polymerizing one or more vinyltriorganosilanes fa using a suitable catalyst. Specific examples of vinyltriorganosilane include vinyltrimethylsilane, vinyltriethylsilane, vinyltripropylsilane, vinyltrimethylsilane, vinyldimethylethylsilane, vinyldiethylmethylsilane, vinyltricyclohexylsilane, vinyldimethylcyclohexylsilane,
Vinyldimethylphenylsilane, vinyldimethylbenzylsilane and vinyldimethylphenylsilane are honored.

In addition, in the polyvinyltriorganosilane in the present invention, the C structural units other than the Pak) position of formula (1) -+, 2
A polymer compound containing a proportion within S*X% is also included.

Is the strength of silane greater than or equal to 2>h? It may also be an M compound.

Next, the organosiloxane used in the present invention is basically a compound consisting of 81-0-81 bond skeletal forces, and has the following general formulas (2), (3), (4) and (5 )
Of / 1 jli or more f repeats 1 glume 9 of the compounds, and their? 1< compound ga magera fl-
Ru.

H4'l('1% ring (in the formula, R4, R5 and a substituted alkyl group, alkenyl group, cycloalkyl group, cycloalkyl group, aryl group, some or all of the hydrogen atoms of these groups)]・Rogen Indicates a functional group such as a group substituted with an atom, a hydrogen atom -r=, a hydrogen atom, an amino group, an amide group, an alkoxy group, and may be the same or different from each other), Further, the organopolyoxane used in the present invention may be a compound of one or more organopolyoxanes.

The organopolysiloxane used in the present invention includes a wide range of compounds, from low-molecular negative compounds to high-molecular dark compounds, but those with a low boiling point C are not preferred as hdL control materials, and those with a boiling point of at least 2 is preferred if the temperature is 200°C or higher. More specifically, the number average molecular month is /, 00
It is preferably 0 or more.

Fourteen examples of organopolysiloxanes include all the compounds described in Japanese Patent Application Laid-Open No. 2003-120001, published by J. Kou, No. 3'62, and No. t.

The mixing ratio of polyvinyltriorganosilane and organopolysiloxane is 0.0 J to 2 parts by weight of polyvinyltriorganosiloxane/, θ
It is selected from the range of the heavy part, preferably 0.7 to 0.
．． 6 Le part, especially favorite [〈keO1/! ~0. Selected from Japan. As the ratio of organoborisiloxane ty2y to polyvinyltriorganosilane increases, the effect of polysiloxane is expected to increase and kill power, but on the other hand, the strength of the membrane decreases, and the membrane becomes more likely to have defects, resulting in a decrease in separation performance. . Conversely, as the mixing ratio of organopolysiloxane decreases, the permeation rate at which the separation performance begins to deteriorate decreases, resulting in a membrane that is brittle and has low elongation.

Gas separation membrane 1-t of the present invention, the above-mentioned specific polyvinyltriorganosilane and organopolysiloxane glue 7
The compound may be used as a membrane material (!--but may contain a third component such as an organic substance or an inorganic substance, as long as the essential properties of the mixture as a membrane are not lost. Polyamide, polyester, etc.) A nonwoven fabric made of synthetic fibers or natural fibers may be included as a reinforcing material.

As a solvent for dissolving the above membrane materials, when manufacturing an asymmetric membrane, the solvent is selected as shown in the table below, and when manufacturing a homogeneous membrane or a composite membrane, solvents such as cyclohexane, benzene, toluene, xylene, aliphatic and aromatic solvents are selected. hydrocarbons, and dichloromethane hydrocarbons. The membrane material concentration in the solution is θ, /~SO weight %, and the residue L is 7 to 70 weight %.

For the production of the gas separation membrane of the present invention, 1 of the above membrane charges shall be
1! ! The membrane solution has a maximum pore size of 6μ or less, preferably Zμ.
It is necessary to perform FJ using the following microfilter to remove foreign substances such as floating dust or insoluble polymers in the solution. for example,
If the 0' overtreatment is not carried out during the production of the asymmetric membrane described below, the selective fractionation will decrease as the permeation rate increases. As the permeation rate increases, that is, as the thickness of the dense layer of asymmetric Mk becomes smaller, the separation property decreases significantly. 41. It is said that it is to make it easier for him. Therefore, in the method of the present invention, the # membrane solution is
By treating with a fixed micro filter, the densified layer,
It has become possible to prevent the occurrence of defective areas and maintain the selective separation property of the sieve on the permeation rate side. The characteristics of the present invention (the microfilter is inert to the solvent forming the membrane-forming solution and the molecular cavity I material, and maintains its performance and performance as a sapon filter during the application of power, heat, and heat). There is no restriction as long as it is compatible with both inorganic and organic materials.

The membrane obtained by the above method may be a monolayer consisting only of a dense layer with selective separation property of gas C'', but it may be a single membrane consisting of only a dense layer with selective separation property of gas C'', or a membrane with a dense layer with selective separation property of In an asymmetric membrane composed of a porous layer that does not exhibit separation properties and a C double layer, it is relatively easy to form an extremely thin dense layer without defects, and therefore, it simultaneously achieves high permeation rate and separation performance. In the gas separation group of the present invention, defects are extremely difficult to occur even when the Jq of the dense layer is made small, and therefore high separation performance is maintained.
: It has the characteristic of being able to obtain a good permeation rate. Here, a dense layer is strictly non-porous and exhibits substantially the same selective permeability to gas or vapor as the material constituting the layer (mainly composed of the above-mentioned mixture); Zeng and Vi
It is formed from the same constituent material as the single layer, has open pores and a spongy structure through which gas can freely pass, and has no permeability due to the mere movement of gas or vapor along the pores. Examine the inert layer that shows no signs of aggressiveness. Considering the permeation rate through the thickness of the dense layer, it is preferable that θ, Q /~/μ.
It can be seen that even in this range of l-m, in the present invention, there is almost no decrease in gas selectivity, and a strong and stable dense layer is completely formed. on the other hand. The thickness of the porous layer is 10μ or more considering the mechanical strength of the membrane and ease of handling.
'C100~/θθθμ is preferably 11, but when reinforcing with another third component or using another porous membrane as a support for the membrane of the present invention, the thickness is less than 10μ. K
I can do it when I do.

An asymmetric membrane consisting of a dense layer and a porous layer as described above can be dipped, for example, by the following method. In other words, it has a boiling point lower than that of the more volatile solvents (hereinafter referred to as "light solvents") among the two types of solvents and the two types of solvents, and has a boiling point lower than that of the 11 intermediates. - Dissolve organopolysiloxane and hypolyvinyltriorganosilane in a three-component mixed solution of citron, which has a negative solubility, and pour the solution onto a support. 2fΦ class solvent e] Among them, the more nonvolatile solvent is hereinafter referred to as "heavy solvent". ), (b) mainly by removing part or all of the light solvent, C) treating the produced film with a coagulating solution (poor solvent), and (d) drying the film. Ru.

Light and heavy solvents include aliphatic and aromatic hydrocarbons such as cyclohexane, benzene, toluene and xylene;
and halogenated hydrocarbons such as dichloromethane, dichloroethane, butrachloroethylene, chloroform, chlorobenzene and hiscyclobenzene.

Poor solvents include water, methanol, ethanol, primary,
Alcohols such as two-string and three-ferment butanol are included. Specific examples of combinations of ternary mixtures consisting of light solvents, heavy solvents, and light solvents include toluene-dichloromethane-isobutanol, benzene-dichloromethane-isobutanol, monochlorobenzene-chloroform-isobutanol, and toluene-chloroform. Examples include -isobutanol, toluene, dichloromethane, and 2M butanol. Here, organopolysiloxane and polyvinyl triorganosine were dissolved in the 717 compound of the three-component yarn.
In order to prepare the first solution M, the order in which the respective substances and solvents are added is not particularly limited.

On the other hand, the selection of supports used in casting - %K
'JB constant, but batchwise operation f [and continuous m ft-
In this case, a stainless steel or aluminum belt is used, but a td-/j system belt can also be used in a batch type.

The opportunity to manufacture an asymmetric cam with a film thickness of 10θμ or more is
After the surface has been plated, stainless steel or aluminum plates with a flat surface are plated as supports 1.
- It is suitable for use in - and a good gas separation membrane can be obtained! Soil. Depending on the shape of the support, it is possible to produce flat or tubular membranes.

In the next step of removing the light solvent, the proportion of the light solvent ρν removed has a significant influence on the thickness of the dense layer formed → -0, i.e., the proportion of the light solvent removed The smaller the pestle, the wider and denser the eaves layer will be. Although it is desirable to have a suitable removal rate of lightly dissolved W, d/θ to soX, although it depends on the evaporation conditions including evaporation time and temperature, it is possible to deviate from this range. In the present invention, by using polyvinyltriorganosilane having a specific solid viscosity, gas separation performance can be achieved even at a removal rate of 70% or less. MK? Since the gas ladle velocity depends on the precise flow rate, the step of removing the light spray is the most important step in controlling the gas permeation rate. Ijl, lchi,
Gas C] Permeation rate C] In order to obtain a dog-like membrane, the amount of light solvent removed should be small and the thickness of the dense layer σ should be made as small as possible. This is undesirable because a defective portion (defects and υ here refer to a state in which the membrane gives the same permeation rate to all gases and loses its ability to separate gases) is undesirable.

Therefore, it is desirable to control the amount of light solvent removed to such an extent that such defects do not occur.

The coagulation (l!iJg) is used for the purpose of gelling the polymer solution, or serves the purpose of completing the formation of this gel if the formation of G/I- is initiated by evaporation of the light solvent. Therefore, a solvent that can group together with the light, heavy, and poor solvents mentioned above in the coagulation solution U is selected, and this gelation process is continued until as much of the solvent as possible is eluted from the i% + - solid film and IL. This can be carried out continuously or intermittently.Specific examples of the coagulating liquid include U, methanol, ethanol, methanol-ethanol mixture, water-methanol, water-dioxane mixture. The immersion time is not particularly limited, as long as it is long enough to elute most of the solvent that composes the polymer solution.In general, an immersion time of 0.7 to 1 hour at a historical temperature is sufficient. That's enough.

Drying of the coagulated film can be carried out at ambient temperatures of 100°C or higher, but if necessary lower than 100°C. 00
The heat treatment can also be carried out at temperatures below 0.degree. C., preferably between .theta.0 and 0.degree.

The membrane obtained by the method of the present invention has excellent selectivity, especially at high gas permeation rates, and has practical mechanical strength and ease of handling. It can be used in many fields for the purpose of separating and concentrating a certain gas at a higher rate.

Fields where such membranes can be used include recovery of helium 2+ from natural gas, concentration of hydrogen in hydrogenated gases, combustion by diversion of oxygen in the air, medical use and wastewater treatment, etc. Gaseous distillates containing oxygen, nitrogen, hydrogen, carbon dioxide, carbon oxide, helium, argon, methane, and other gases are being used to separate large amounts of gases.

Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to the specific materials, methods, etc. shown in these Examples.

Polyvinyltrimethylsilane was polymerized at room temperature using n-butyllithium as a catalyst to obtain polyvinyltrimethylsilane with an intrinsic viscosity of /, s, and 2 dl/f in cyclohexane at 2 J'°C. .

The above polyvinyltrimethylsilane '1. Of) Luene-θ, and chloroform 62.3? and - rule/
, 2. /f was added to obtain a homogeneous solution. Next, the obtained homogeneous solution was filtered through a G-41 (pore size/θ ~ 76 μ) glass filter, then cast onto a ferro plate to a thickness of 50 μ, and left in the air at Kv humidity and temperature for a predetermined period of time. After mainly 1 chloroform was evaporated, the membrane was immersed in a room temperature methanol bath together with 72 plates. After about 7.5' minutes,
The membrane was taken out and air-dried. Method for measuring the gas permeation rate (hereinafter referred to as KR) of the obtained membrane i-1' The membrane of the present invention was fixed on a membrane mount, and 2. A predetermined gas was pressurized to 7.0 klj/d gauge on one side of the membrane, and the amount of gas permeating through the other side of the membrane over a certain period of time was measured using a gas burette.

The results of the evaporation φ and gas permeation performance in the above film formation are shown in Table 1d-7. As you can see from the table, RO2
(indicating oxygen permeation rate) is approximately /θ-3CC (STP)
/(d, sec -crnHf/ around 75-
The ratio of 17Ro2/Ry2 begins to decrease rapidly, and when the homogeneous solution is filtered through the glass filters a to g, the selective separation decreases on the high permeation rate side of d1.

Example: Vinyltrimethylsilane was polymerized using n-butyllithium as a catalyst, and the intrinsic viscosity in cyclohexane at 26°C was /,
KF manufactured by Shin-Etsu Chemical Co., Ltd. as polyvinyl tri of t7di/y
i#13RTV O, /J-f f addition, next m toluene z, op, chloroporm! After adding and dissolving 2 ml of inbutanol, 30.2 ml of inbutanol was added to form a homogeneous solution. Next, millibore diameter RAWP (pore diameter/1.
After filtering the solution through 2±o, 3p), a membrane was formed on a 7-layer plate to obtain an asymmetric membrane. The evaporation time when the loaf was heated was 5 minutes.

The thickness of the obtained membrane is 26/μ, and the permeation rate is Ro2.
= ,2. /X/θ-”c(sTP)/7-crown-o
nH,.

RN2-7.7 ×10-' CC(STP) /7-
sec -BHI and speed ratio Ro2/RN,
= 2.7.

It is clearly seen that the reverse refraction separation performance is high even on the high permeation rate side, and cuff loss appears.

Example - 2! The solid viscosity in cyclohexane is 7.7 di.
/f polyvinyltrimethylsilane3. KE/θ3RTVθ manufactured by Shin-Etsu Chemical Co., Ltd. as Of and organopolysiloxane
, ri, jyK toluene/j9 and chloroporum,/7
．． After adding and dissolving the mixture, isobutanol and 6 pieces were added to form a homogeneous solution.

[Next Sudeko e] Uniform melt g, Example / and total < lT5.1
The gas vapor permeability of the membrane obtained is shown in Table 2.
It was shown to.

Example j, 2! ℃ q) Intrinsic viscosity in cyclohexane /, 6di
A uniform bath was prepared in exactly the same manner as in Example 1, except that polyvinyltrimethylsilane with a concentration of 9 was used, and then a film was formed in the same manner. Gas permeability of the obtained membrane/In Example 4, the organopolysiloxane was θ, -! 7
Exactly the same except that a homogeneous solution was prepared using K1. film formation [ta]. The gas permeability of the obtained cavity is shown in Table 2VC.

Example 2 The solution was cast onto a 7-layer plate to a thickness of Moon - obtained performance.

The resulting film had a thickness of 72 μm and had sufficient mechanical strength, making it very easy to handle. Moreover, the selective separation performance was almost the same as that of the membrane obtained in Example 2 even though the membrane thickness was about - times larger.

Example? , Ri, 2! The solid viscosity in cyclohexane is 3. Yo2dll
A homogeneous solution obtained in the same manner as in Example 2 using polyvinyltrimethylsilane of T was cast onto a ferro plate to a thickness of 100θμ, and a film was formed in the same manner as Iij. The results are shown in Table-
Shown in 3. The membrane had high selective separation performance similar to that of Example 7. Therefore, it can be seen that there is a strong relationship between membrane thickness and gas selective permeability.

Example / θ, 2j °C Intrinsic viscosity in cyclohegizan /, 22 dl
A homogeneous solution was prepared and prepared in exactly the same manner as in Example except that polyvinyltrimethylsilane having the following properties was used: The obtained removal performance is shown in Cloth-3.

Example// In Example/θ, vaporization [1, minute//min] was used, and A is a film formed using the same homogeneous solution in exactly the same manner (
- I measured the 4 months of transparent excitement U ↓ 纒 R with 1 A of gas R (all units are cc (S
TP)/c+I・9UC-cmH? )■(0
□=7. /X/θ-4 HN2-2.6x/θ-4 Rco2=/, and x/θ-3 RH2=, 2. j X 1O-3 ROH4=3. / x 10-' On the other hand, the speed ratio is Ro2/kh+2=+2.7 Rco,/hill N2=6.9 R1-1,/R++2=7.6 RO)+4/Rt+2=896 Tepaatsu TZ.

/ / 7./ /′ / / 7/ /

Claims (3)

[Claims] (1) A method for producing a separation membrane that has a 7% characteristic when it is produced using a solution of a polymer membrane material that has been filtered through a microfilter with a maximum pore size of 6 p or less. (2) The separation membrane 9 is an asymmetric membrane composed of a dense layer exhibiting gas selectivity and a porous layer exhibiting gas selectivity. (3) The polymer membrane material is polyvinyltriorganosilane/
λ amount part and organopolysiloxane 0. The wholesaler of the patent claim which is a mixture of θri~/heavy plate part [f14 paragraph 1 and paragraph