JPS5858104A - Separation membrane for mixed liquid - Google Patents

Abstract

PURPOSE:To separate a mixed liquid such as an azeotropic mixed liquid in an industrially available manner, by constituting a separation membrane from a composite membrane consisting of a hydrophilic high molecular non-porous layer and a hydrophoblic high molecular non-porous layer. CONSTITUTION:A separation membrane for separating a mixed liquid is constituted from a hydrophilic high molecular non-porous layer and a hydrophobic high molecular non-porous layer. The hydrophilic high molecular compound is a mixture of one having an amido group, especially, one having an N-alkylamido group, for example, one or more of polyvinyl pyrrolidone, polyvinyl pyperidone, polyvinyl pylidone, polyvinyl-N-methylacetamide and poly N,N-dialkylacrylamide and polyvinyl alcohol. The hydrophobic molecular compound is polyorganosiloxiane. This separation membrane is suitable for separating an azeotropic mixture and a proximate b.p. mixed liquid.

Description

[Detailed description of the invention] The present invention relates to a mixed liquid separation membrane.

The mixed liquid is placed on one side of the separation membrane, and the other side is evacuated to reduce the pressure, or an inert gas is flowed to maintain a low vapor pressure, and the pressure difference allows the liquid to permeate. So-called pervaporation, which separates a liquid mixture by evaporation, has been studied since the mid-1950s. This separation method was devised for the purpose of separating and purifying chemical liquids (mainly organic solvents, hydrocarbons, etc.) that cannot be separated using normal distillation methods. For example, azeotropes, solvents with close boiling points, isomers (ortho and para, cis and trans)
This is sorting and separation. Other applications include pyrolytic mixed wave bodies, concentration and purification of fruit juice, removal of traces and impurities, and removal of water produced during ester reactions.

Furthermore, U.S. Pat. No. 2,953,502 discloses that vinyl alcohol polymer J[t-
It is possible to separate the co-#i1m mixture by using a styrene-benzene mixture, and US Pat. Furthermore, U.S. Pat. No. 2,960,462 uses a composite membrane of ethyl cellulose and polyethylene or cellulose butyl acetate as a separation membrane that can withstand pressure differences and is durable. , has been reported to separate organic mixtures. However, in these methods, the separation efficiency is low and the separation throughput is not large enough, so the equipment has to be enlarged, which increases the cost.

The present inventors have conducted various studies on membranes that can improve these drawbacks and separate mixed liquids such as azeotropic liquid mixtures in an industrially advantageous manner, and as a result, they have arrived at the present invention.

That is, the present invention is a mixed liquid separation membrane comprising a composite membrane having a hydrophilic polymer non-porous layer and a hydrophobic polymer non-porous layer. The composite membrane of the present invention has very excellent permeation performance, as is clear from the examples described below, and the bridgehead of the liquid that permeates from the front side and the back side of the composite membrane is different, or the separation coefficient is different. It has a unique performance.

The hydrophilic polymer in the present invention refers to a hydrophilic polymer having an amide group, particularly a hydrophilic polymer having an N-alkylamide group, such as polyvinylpyrrolidone, polyvinylpiperidone, polyvinylpyridone, polyvinyl-N-methylacetamide, and polyvinylpyrrolidone. A mixture of at least one substance selected from N,N-dialkyl acrylamide and polyvinyl alcohol (PVA), or PVA, cellulose-based! molecules (cellulose, carbomethoxycellulose, cellulose acetate, etc.).

Among these, in order to more fully exhibit the effects of the present invention, it is necessary to use a hydrophilic polymer having an N-alkylamide group and PVA.
Mixtures of are particularly suitable. Further, as a hydrophilic polymer having an N-alkylamide group, polyvinylpyrrolidone exhibits the best effect.

When a hydrophilic polymer having an N-alkylamide group and PVA are mixed to obtain a non-porous layer, the mixing ratio is PVA20-8.
0% by weight, 80 to 20% by weight of the hydrophilic polymer having N-alkylamide groups, and more preferably 50 to 70% by weight of PVA. When creating such a layer, it is free to add a third component in addition to these components.

The PVA used in the present invention has an average polymerization degree of 50
0 to 5,500, saponification degree of 85 to 100 mol%, more preferably average polymerization degree of 1,500 to 5,500,
saponification degree of 95 to 100 mol%, and ethylene,
Vinyl pyro'JF, saponified copolymers of vinyl chloride, etc. and vinyl esters such as vinyl acetate, or PVA
These include those made by reacting chemical reactants such as aldehydes with aldehydes. a hydrophilic polymer having an N-alkylamide group,
In particular, PVA used in combination with polyvinylpyrrolidone has an average degree of polymerization of 500 to 5,500 and a degree of saponification of 85 to 1.
00 mol X of conventional PVA is more preferred.

In the present invention, the hydrophobic polymer is not particularly limited as long as it is a polyorganosiloxane that can be formed into a film, but from the viewpoint of solvent resistance, silicone rubber is preferable, and furthermore, when a silicone rubber film is formed, it is hydrophilic. A material that has excellent adhesion to a non-porous polymeric membrane is preferable. Silicone rubber is mainly composed of a linear structure represented by the general formula Ra8i0-, - (the formula 凰 means at least 5'
0! A substituted or unsubstituted monovalent organic group in which X is a methyl group, including methyl group, ethyl group, propyl group, vinyl group, phenyl group, mercaptopropyl group, 5°3.5
-) Examples include organic groups containing a lifluoropropyl group, an r-cyanopropyl group, a mercapto group, a cyano group, an amino group, and the island is a positive number from 1.99 to 2.02). This siloxane is crosslinked into an elastomer by a well-known curing reaction.

The curing reaction suitable for the present invention is a condensation reaction by selecting the terminal or side chain functional group of the linear polyorganosiloxane represented by Ra 8102-, a crosslinking agent, and a catalyst.
Addition reaction, organic peroxide vulcanization, sulfur-based vulcanization, radiation curing reaction (UV, electron beam curing), and oxygen curing are employed.

In the present invention, it is also possible to use modified silicone rubber obtained by modifying polyorganosiloxane with other organic compounds such as olefin monomers. Incidentally, various commonly used fillers (additives) for improving physical properties may be mixed with these silicone rubbers.

If the adhesion between the hydrophilic polymer non-porous membrane and the polyorganosiloxane is not very good, or if stronger adhesion is required, the hydrophilic polymer non-porous membrane can be pre-coated with a brimer, carbon fan or glue. In the invention, the silicone rubber used is preferably 200,000C98 or less in terms of workability and processability before curing, but it can be diluted with a solvent if necessary, so that it does not stick to the cured film. In order to eliminate holes, etc., extreme care must be taken to avoid contamination with foreign matter.

In the present invention, a composite membrane having a hydrophilic polymer non-porous layer and a hydrophobic polymer non-porous layer is a membrane in which a hydrophobic polymer is attached to a hydrophilic polymer non-porous membrane, or a hydrophobic polymer non-porous membrane. A hydrophilic polymer is attached to a hydrophilic polymer, a hydrophilic polymer non-porous membrane and a hydrophobic polymer non-porous membrane are laminated together, or a hydrophobic polymer and a hydrophilic polymer are integrated by co-extrusion. For example, it is molded into Furthermore, it is free to use such a composite membrane by attaching it to a porous membrane, or by providing a porous membrane between a non-porous polymer layer and a non-porous hydrophobic polymer layer. What is the "non-porous layer" of a hydrophilic polymer non-porous layer and a hydrophobic supramolecular non-porous layer? A non-porous homogeneous layer in which the entire layer is a non-porous layer, or a part of the layer (one or both sides of the layer) is a non-porous layer, and the other is a porous layer, meaning a non-porous heterogeneous layer. When creating a composite membrane by attaching unrestricted layers or one homogeneous layer and the other non-homogeneous layer, it is preferable to attach the non-porous layers to each other. When the surfaces of non-porous layers are attached to each other, since the surfaces to be attached are non-porous layers, the generation of bottle balls is not observed as in the case where the layers are attached on top of a porous layer.

The thickness of the composite membrane of the present invention is between 1μ and 500μ, preferably between 5 and 200μ. If the film thickness is thinner than this, the strength of the film will be insufficient or the durability will be insufficient. Furthermore, if the membrane thickness is thicker than this, the amount of liquid mixture that permeates through the membrane will be small, making it impractical. Furthermore, the composite membrane is a porous membrane (
When used by adhering it to a microporous membrane (such as a microporous membrane), the composite membrane can be sufficiently durable even if the thickness of the composite membrane is reduced. The thickness of the composite membrane in this case can be 0.1 to 50μ. The shape of the composite membrane is usually a flat membrane (flat membrane), but it can also be used in other shapes, such as a cylindrical shape or a hollow fiber shape, which increases the area of responsibility.

The major differences between the composite membrane of the present invention and conventional membranes are that the separation coefficient is very similar when separating mixed liquids, or that the type of liquid that permeates from the front side and the back side of the composite membrane is different. The difference is that the separation coefficients are different. In other words, when the side of the composite membrane that comes into contact with the liquid to be separated is a hydrophilic polymer non-porous layer, what passes through the membrane is less polar; If the side that is exposed is a non-porous layer of hydrophobic polymer, what passes through the membrane is more polar.

In the present invention, the "mixed liquid" which is the liquid to be separated is
The method of the present invention is particularly effective in separating organic mixed liquids. Among organic mixtures, azeotropic mixtures include methyl acetate/methyl alcohol,
Ethyl acetate/ethyl alcohol, benzene/cyclohexane, methanol/acetone, benzene/methanol,
Examples include benzene/ethanol, acetone/chloroborum, methanol/acetone, etc. In addition, the close boiling point mixed liquids include ethylbenzene/styrene, parachloroethylbenzene/parachlorostyrene, toluene/methylcyclohexane, butadiene/butenes, butadiene/
Examples include butanes.

In addition to the above-mentioned azeotropic mixture, examples of "mixed liquids" include liquid mixtures that are difficult to separate, such as water-acetic acid, and liquid mixtures that can be separated by ordinary distillation (such as water-methanol, water-acetone, etc.). ) etc. However, in this case, the concentration of water is preferably low, for example, 20% by weight or less.

First about the separation method actually using the composite membrane of the present invention
This will be explained with reference to FIG. This device is divided by the composite membrane 1 into a mixed liquid chamber 2 and an exhaust chamber 5. A mixed liquid to be separated or concentrated is introduced into the mixed liquid chamber 2 through an inlet 5, and an outlet 4
Take it out. On the other hand, the exhaust chamber 5 may be reduced in pressure by a suitable method, or other liquid or gas may be circulated therein. Note that 6 in the figure indicates that the pressure on the opposite side of the membrane, that is, the exhaust chamber, must be lower than the mixed liquid chamber, and the larger the pressure difference, the more effective it is, but industrially it is 0.01 ~50 atm is good, more preferably 0.5~1 atm. In addition, the pressure on the side in contact with 1 mixed liquid is 1 (atmospheric pressure) to 100
The pressure is good, preferably at or near atmospheric pressure.

On the other hand, the pressure on the opposite side is less than 50 atm, preferably less than atmospheric pressure, more preferably less than 40 logg, and even more preferably 10071
It is best to maintain a vacuum of g or higher. The substance that has permeated through the membrane may be taken out in either a gaseous or gaseous state on the low-pressure side, but it is better to evaporate it on the low-pressure side and take it out in a gaseous form for better separation efficiency and permeability.

Therefore, it is preferable to maintain the low pressure side at a pressure lower than the vapor pressure of the substance passing through the membrane. There are two ways to maintain the pressure at a low level: by drawing a vacuum to reduce the pressure, or by flowing an inert gas to maintain a low vapor pressure.

Furthermore, there is no need to flow liquid or the like on the low pressure side.

Methods for separating mixed liquids using the composite membrane of the present invention include, in addition to the above-mentioned bar vaporage method, variations thereof such as the steam sweep parvare sheen method, the thermopervaporation method, and the osmodity method. In addition to these methods, methods such as the Resi extraction method, the Parbodiesta Resi extraction method, and the Verbo Cryogenics method can also be used, as well as the Osmosis extraction method and the Forward Osmosis method.

Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Polyvinyl alcohol (PVA) (manufactured by Kuraray Co., Ltd.,
PVA117, average degree of polymerization 1700, degree of saponification 99.8
mol%) and polyvinylpyrrory (PVr) from Tokyo Kasei Co., Ltd. I! ! A 10% by weight aqueous solution having an average molecular weight of 560,000 + 1:2 weight ratio was prepared, and this was cast onto a glass plate and air-dried at room temperature to obtain a non-porous homogeneous membrane with a thickness of 50 μm.

On the other hand, the viscosity at 25°C is 200000.8. Dimethylpolysiloxane 1 with both ends of the molecule capped with hydroxyl groups
00 parts, formula CMs8 i (ONO(OH,)(C2H
s)) A silicone rubber composition was prepared by combining 8 parts of the 4 parts silicon compound and 1-0.1 m of dibutyltin dilaure. Dilute this composition with toluene (silicone composition @: toluene -1 + 10) l, 5.
It was cast onto a 0μ non-porous homogeneous membrane and left at room temperature for 24 hours to form a silicone rubber non-porous layer.
5μ) was obtained.

This composite membrane was installed in the apparatus shown in Fig. 1 (
An effective membrane area of 25.8 am") was set, an organic mixture (1:1 M2 ratio) was circulated and supplied under 259C1 atmospheric pressure, and the exhaust chamber was suctioned to 55 mmtiH to conduct a separation experiment.

The liquid permeation IQ per unit membrane area and unit time, and the permeate composition are shown in Table 1.

Table 1 Organic liquid-liquid (1:1 weight ratio) separation example 6 using a composite membrane [Keybropha 2 (manufactured by Enca [150 parts MJ dialysis, membrane thickness 11 μm]) was used as a hydrophilic polymer non-porous membrane. This membrane was coated with silicone rubber in the same manner as in Example 1.2. The silicone rubber layer had a thickness of 109μ, and the composite membrane had a thickness of 109μ.
20μ) was obtained, and the same separation experiment as in Example 1.2 was conducted. The results are shown in Table 2.

Table-! Organic liquid-liquid (+ +311 quantitative ratio) separation examples 4 to 5 using a composite membrane Exactly the same as Example 6 except that Keyprofan containing activated carbon (manufactured by ENKA) was used as the hydrophilic polymer non-porous membrane. A membrane was formed using the same method, and a separation experiment was conducted. The results are shown in Table 6.

Table - Organic liquid by sw element membrane - [(11 weight ratio) Separation Examples 6 to 8 Using the same non-porous homogenizing membrane as in Example 1, the following silicone rubber compositions (A, B . The results are shown in Table 4.

0 Silicone rubber composition Dimethylpolysiloxane 10 having a viscosity of 20,000 c, s at 25°C and capped at both ends of the molecule with hydroxyl groups
A silicone rubber composition was prepared by mixing 0 parts of dibutyltin laurate, 0.1 parts of dibutyltin laurate, and 5 parts of methyltriacetoxysilane.

0 Silicone Rubber Composition B 100 parts of dimethylpolysiloxane whose viscosity at 25°C is s o o oc, s, both ends of the molecule are capped with hydroxyl groups, 2.5 parts of ethyl polysilicate, and Me.

8 Specific surface area 200m with surface treatment in i0+ units
(3) 35 parts of 7 g of silica filler were uniformly mixed using a triple roll, and 0.5 part of dibutyl dilaurate was further mixed to prepare a silicone rubber composition.

and the viscosity at 256C is about s o o o c,
s, dimethylpolysiloxane 94 parts, 8 parts 02 units 1
．． 0 mol, ((3H:2-O2-0n) i00 parts 0.
05 mol, Me, 8 parts 0 units 0.044% L, (OH,
-CH)Me, 8i (h unit 0.1 mol, Me,
An organoorganic compound consisting of 8 parts 0 + 0.7 moles of units 1.0 parts of siloxane 0.25 parts of siloxane containing 0.25 parts of chloroplatinic acid in butanol (platinum concentration 2%) 0.02
A silicone rubber composition was prepared by mixing 5 parts.

In addition, compositions M, B, and C were diluted with toluene, toluene:silicone rubber composition-10: 1) # cast onto a porous homogeneous membrane, and A and B were left at temperature in a factory (24 Hrs);
3/I Hrs f Cured at 120°C/6 Hrs.

Table 4 Organic liquid - g: (11 weight ratio) separation on composite membrane From the above examples, the composite membrane of the present invention has excellent permeation performance, and the substances that permeate on the front and back sides are different or the separation coefficient is different. You can see that they are different.

Therefore, for example, the mixed liquid is treated from the hydrophobic polymer non-porous layer side of the first composite membrane, and then the permeated liquid is separately prepared from the hydrophilic polymer of the second composite membrane (or 1liI composite membrane). If the treatment is performed from the non-porous layer side, a liquid with a high concentration of one of the components in the mixed liquid can be obtained as a non-permeated liquid.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a separation device used in the present invention. 1...Composite membrane 2...Mixed liquid chamber 5...Exhaust chamber 4...Mixed liquid outlet 5...Mixed liquid inlet 6...・・Membrane support 7・・・・・Steam outlet Patent applicant: RiRa Co., Ltd. Agent - Patent attorney - Mizukaki Tate/Kinuta 1 Procedural amendment (voluntary) Patent dated November 2, 1981 Agency Commissioner Haruki Shimada 1, Indication of the case, Patent Application No. 154455/1982, Name of the invention: Mixed liquid separation membrane (108) RiRa Co., Ltd. Representative Director Tsugu Okabayashi, Male 4, Agent: Tokyo 03 (277) 31 B Part 2 Contents of amendment (1) The scope of claims is amended as shown in the attached sheet. (2) Specification, page 10, line 12 [03, It is expensive. ” and line 15 [In the present invention, the following items are inserted between . Furthermore, in the case of a single-layer film made of a hydrophobic polymer such as silicone rubber, the film thickness cannot be made very thin because the strength of the silicone rubber is not sufficient. When attached to the above-mentioned non-porous layer consisting of a mixture of a hydrophilic polymer having an N-alkylado group and PV rubber, this hydrophilic polymer non-porous layer serves as a base film to reinforce the silicone rubber. I will do it. Therefore, even if the thickness of the silicone rubber layer to be adhered is made thinner, it will not be destroyed, and therefore the amount of permeated liquid can be increased. Further, in this case, since the surface to which the silicone rubber is attached is a non-porous layer of hydrophilic polymer, no pinholes are observed, unlike when the silicone rubber is attached onto a porous layer. In this case, if the liquid to be separated is treated from the hydrophilic polymer non-porous layer side, the hydrophilic polymer non-porous layer will swell with the liquid to be separated, so the liquid to be separated will flow through the hydrophilic polymer non-porous layer. It easily penetrates into the silicone rubber layer. Therefore, if the liquid to be separated is treated with such a composite membrane, the separation coefficient will not be reduced at all, but rather the amount of permeated liquid can be increased by the thinner silicone rubber layer compared to a silicone membrane alone. can. (3) "ENKmu" in the third line from the bottom of page 15 is corrected to "enka". (4) From the 18th purchase to the 10th bank “50℃/I
Hr 8+b 120°C/6 hours”. 2. Claims (1) A mixed liquid separation membrane consisting of a composite membrane having a hydrophilic polymer non-porous layer and a hydrophobic polymer non-porous layer. (2) The mixed liquid separation membrane according to claim 1, wherein the hydrophilic polymer is a mixture of polyvinyl alcohol and a hydrophilic polymer having an amide group. (3) The mixed liquid separation layer membrane according to claim 2, wherein the hydrophilic polymer having an amide group is a hydrophilic polymer having an N-alkyl amide group. (4) Claim 3, wherein the hydrophilic polymer having an N-alkylamide group is selected from polyvinylpyrrolidone, polyvinylpiperidone, polyvinylpyridone, IP ribinyl-N-methylacetamide, and polyN,N-dialkyl acrylamide. Mixed liquid separation membrane of war. (5) The mixed liquid separation membrane according to claim 3 or 4, wherein the hydrophilic polymer having an N-alkylamide group is polyvinylpyrrolidone. (6) The mixed liquid separation membrane according to any one of claims 1 to 5, wherein the hydrophobic polymer is a polyorganosiloxane. (7) The mixed liquid separation membrane according to claim 6, wherein the polyorganosiloxane is a room temperature-curable, heat-curable, radiation-curable, or oxygen-curable silicone rubber. (8) The mixed liquid separation membrane according to any one of claims 1 to 7, wherein the mixed liquid is an organic mixed liquid.

Claims (1)

[Scope of Claims] (1) A mixed liquid separation membrane comprising a composite membrane having a hydrophilic polymer non-porous layer and a hydrophobic polymer non-porous layer. (2) The mixed liquid separation membrane according to claim 1, wherein the hydrophilic polymer is a mixture of polyvinyl alcohol and a hydrophilic polymer having an amide group. (5) The hydrophilic polymer having an amide group is a hydrophilic polymer having an N-alkylamide group! A mixed liquid separation membrane according to claim 2. (4) The hydrophilic polymer having an N-alkylamide group is selected from polyvinylpyrrolidone, polyvinylpiperidone, polyvinylpyridone, polyvinyl-N-methylacetamide, and polyN,N-dialkyl acrylamide. mixed liquid separation membrane. (5) The mixed liquid separation membrane according to claim 5 or 4, wherein the hydrophilic polymer having an N-fulkylamide group is polyvinylpyrrolidone. (6) The mixed liquid separation membrane according to claims 1111 to 5, wherein the hydrophobic monomolecule is a polyorganosiloxane. (7) The mixed liquid separation membrane according to claim 6, wherein the polyorganosiloxane is a room temperature-curable, heat-curable, radiation-curable, or oxygen-curable silicone rubber. (8) A mixed liquid separation membrane according to any one of claims 1 to 7, wherein the mixed liquid is an organic mixed liquid.