JPS644829B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous process for producing ultrathin polymer membranes. More specifically, the present invention relates to an industrially advantageous continuous process for producing ultrathin polymers used to concentrate certain gases from gas mixtures. Recently, separation technology using membranes has made remarkable progress in various fields. However, separating gas mixtures using membranes is a relatively recent technology. The technical difficulties in separating a particular gas from a gas mixture, as well as the development of materials capable of permeating the particular gas with sufficient selectivity and sufficient permeation rate, are practical problems. The goal is to establish a technology for producing extremely thin films of uniform thickness and a wide area made of different materials. In other words, the amount of gas that permeates through a homogeneous membrane is generally expressed by the following formula: Here, X is gas permeation rate (CC(STP)/
sec), P is the gas permeability coefficient (CC(STP)・cm/
^cm2 ·cmHg·sec), _P1 - _P2 is the difference in gas partial pressure on both sides of the membrane (cmHg), A is the membrane area ( ^cm2 ), and l is the membrane thickness (cm). Since it is defined by the formula expressed by the following formula, it is clear that once the material of the membrane and the gas to be permeated are specified, the amount of permeation of that gas depends on the membrane thickness and membrane area. It is desirable to make the film thickness as thin as possible and to make the film area as large as possible. Conventionally, in an attempt to produce a membrane with a small thickness and a large membrane area, a solution of a methylpentene polymer and an organopolysiloxane-polycarbonate copolymer in a solvent was dropped onto the surface of water. A batch method for manufacturing ultrathin films that spontaneously expands on the surface is known (see US Pat. No. 4,192,842, specification). As disclosed in the specification, this method makes it possible to spontaneously expand the solution on the surface of water by using an organopolysiloxane-polycarbonate copolymer. The specification of U.S. Pat. No. 4,192,842 also includes a method using a solution of methylpentene polymer alone in a solvent, but according to research by the present inventors, the solution, i.e., organopolysiloxane-polycarbonate copolymer Methods using solutions that do not involve coalescence have not been successful in producing ultrathin films with uniform thickness and large film area. Therefore, although the method using a solvent solution of methylpentene polymer alone as disclosed in the above-mentioned U.S. Pat. At the very least, it is not easy to manufacture an extremely thin film with such a uniform thickness and large film area. Perhaps for this reason, the parent application, U.S. Pat. No. 4,132,824, which is a divisional application of U.S. Pat. No. 4,192,842, claims only an extremely thin film consisting of a blend of methylpentene polymer and organopolysiloxane-polycarbonate. Further, in US Pat. No. 4,155,793, a solvent solution of a polymer is supplied to two reservoirs provided in opposite directions on the surface of an aqueous medium, and each reservoir is provided with a solvent solution on the surface of the aqueous medium. A thin web formed by expanding the solvent solution and penetrating into the aqueous medium at an intermediate position between the two reservoirs is provided on the web, thereby forming a thin web extending from the solvent solution onto the water surface. A method is disclosed for continuously manufacturing a composite membrane having two thin polymeric membranes superimposed on a web that retains two films. This method is unique in that two thin films are continuously formed on a stationary water medium, and these two films are simultaneously held on one web and continuously collected from the surface. It is. Ultrathin membranes produced by such methods as described above are generally used to produce oxygen gas enriched gas mixtures from air, as also disclosed in those specifications. Therefore, an object of the present invention is to provide a method for continuously producing extremely thin membranes from a polymer solution, which have a uniform thickness and exhibit a gas separation coefficient that is almost the same as that inherent to the polymer. It's about doing. Another object of the present invention is to provide an industrial method for continuously producing relatively wide, ultrathin films from polymer solutions. Still another object of the present invention is to provide a continuous method for manufacturing an extremely thin solid membrane having the above-mentioned performance by incorporating it into a porous sheet material. Such objects and advantages of the present invention are such that a polymer solution in which a polymer capable of forming an ultra-thin film is dissolved in a solvent mainly consisting of a substantially water-immiscible organic liquid medium is mixed with a liquid support consisting essentially of water. The polymer is supplied to the liquid surface of the body, allowed to spontaneously expand on the liquid surface to form an ultra-thin film of the polymer, and then the formed film is attached to a sheet-like porous support while being continuously attached to the liquid surface. In the continuous manufacturing method of ultra-thin polymer membranes,
The solution is continuously supplied from the supply means so that the solution and the liquid surface are in contact with each other so that they do not separate, and the liquid support is placed at a distance of 10 cm from the position where the solution contacts the liquid surface.
A flow is formed in the direction of the take-out part of the ultra-thin polymer membrane located at a distance of ~3 m at an average speed of 0.001 m/min or more and 1.2 times or less than the take-out speed of the ultra-thin polymer membrane. This is achieved by a continuous manufacturing method for ultra-thin polymer membranes characterized by the following. In such a method of the present invention, the polymer solution is
The supply means continuously supplies the solution and the liquid surface of the liquid support consisting of water substantially in such a manner that they do not separate from each other to form a continuous film, and in this case,
A gentle flow of the liquid support is formed to produce an ultra-thin film on the surface of the liquid support, and the liquid support is formed by pouring the ultra-thin film onto the sheet-like porous support from the position where the solution contacts the liquid surface. It also flows towards the position where it is taken out from the liquid surface. By doing so, it is possible to produce a wide, continuous, and uniform ultra-thin membrane, and its operation is stable, making it possible to industrially advantageously produce an ultra-thin membrane suitable as a gas separation membrane. The method of the present invention will be explained in more detail below. In the method of the present invention, the supply of the polymer solution to the liquid surface of the liquid support is performed by a solution supply means, and the tip of the supply means is connected so that when the solution is supplied, the solution and the liquid surface do not separate and are continuous. It may be located on the liquid surface, on the surface of the liquid, or in the liquid, as long as a state of contact can be maintained, and it is preferable to supply the liquid in the direction of gravity. In that case, the supply means should be approximately 2 cm above the liquid level.
The separation may be up to 2 mm, preferably about 1 mm, and below the liquid surface, up to about 2 mm, preferably about 1 mm. Further, the supply means may be a supply port, or may be a thin linear object when located above the liquid surface. When it is a thin linear object, the solution is supplied through the linear object. The length of the thin linear object is approx.
The length should be 10 cm or less, preferably about 5 cm or less. When the supply means is a supply port, its shape is capable of continuously supplying the solution at such a rate that the solution supplied above the liquid surface spontaneously expands and produces a solid film of uniform thickness. If so, anything is fine. Since the solvent solution is usually supplied as a dilute solution of the polymer, it is preferable that the supply port has a not too large area. A supply port of any shape, such as a narrow slit, a thin line, a small circular shape, or another polygonal shape, is usually used.
The narrow slit preferably has an opening width of about 0.001 mm to about 1 mm.
As the supply port having a circular or other polygonal shape with a small area, one having an opening area of about 0.01 mm ³ to about 3 mm ³ , preferably 0.05 mm ³ to about 1 mm ³ is preferably used. As the supply means, a circular or polygonal shape (for example, triangular, pentagonal, etc.) having a small area is preferably used. Such feeding means can be the tip of a thin hollow tube, which tip can also be sharp. The solution supplied onto the liquid support rapidly and spontaneously expands on the liquid surface, and simultaneously with or following the expansion, the solvent is gradually released and the solution solidifies. As described above, in the method of the present invention, the solution is continuously supplied to the surface of the liquid support while maintaining contact between the solution and the liquid surface, and a continuous ultra-thin film formed on the liquid support is The liquid support is made to flow in the direction in which it is taken out along the surface of the liquid support, that is, the liquid support forms a gentle flow from the position where it contacts the liquid surface of the solution in the direction in which the ultrathin polymer film is taken out. It is necessary. In this way, a continuous ultra-thin film with a uniform width can be produced with stable operation. The average flow rate of the liquid support in that case is 0.001
m/min to 1.2 times the extraction speed of ultra-thin films,
Preferably a range of 0.01 m/min to 15 m/min is advantageous. Even if it is slower or faster than this range, it is difficult to obtain a wide and uniform continuous film over a long period of time. In addition, in the present invention, the formed ultra-thin film is taken out from the liquid surface while being entrained in a sheet-like porous support, and the speed at which the formed ultra-thin film is taken out (i.e., the taking-out speed of the ultra-thin film) is
is preferably in the range of 0.1 to 20 m/min, preferably 0.5 to 10 m/min. In carrying out the present invention, the temperature of the solution supplied is determined by surface tension or interfacial Although these are factors that influence tension, they are not very important from the viewpoint of tension control. The temperature of the solution at the time of supply is rather meaningful as the temperature at which the solution is supplied. Therefore, from this meaning, about 10 to about 100℃,
Preferably temperatures of about 20 to about 70°C can be employed. It is thought that the temperature of the solution supplied onto the liquid support quickly approaches the temperature of the liquid support as described above. Therefore, the temperature of the liquid support influences the surface tension of the solution and the liquid support as well as the interfacial tension between them, as well as the rate of spontaneous expansion or expansion of the solvent solution on the liquid support. It greatly affects the degree. In other words, if the temperature of the liquid support is too high, the volatilization of the solvent from the solution will be too large, making it difficult to obtain the desired expansion rate and degree of expansion.On the other hand, if the temperature of the liquid support is too low, the opposite will occur. Because the solvent evaporates too slowly, the rate at which it solidifies becomes slow. According to the method of the invention, the temperature is generally about 0° to 80°C, preferably about 1° to about 50°C, more preferably about 3° to about 30°C.
A temperature in °C is taken as the temperature of the liquid support. The method of the present invention in a continuous mode comprises continuously applying a solution of a polymer to the liquid surface of a liquid support consisting essentially of water from a supply means for the solution so that the solution does not leave the liquid surface. to cause the solution to spontaneously expand above the liquid surface, thereby continuously removing the solvent in the solution to an amount sufficient to form a solid film, and then This is carried out by continuously drawing an extremely thin solid membrane onto the liquid surface while entraining it in a porous sheet. The solvent solution of the present invention method, which has such good scalability, can first be used to continuously produce a wide solid film using a supply means, preferably a circular or polygonal supply port with a small opening area. highly desirable for A second feature of the continuous method of the present invention is that the solution is supplied from a supply means for the solvent solution so that the solution does not leave the surface of the liquid support. When the solvent solution is separated from the liquid surface and supplied to the liquid surface in the form of droplets, for example, the formed solid film has a striped pattern of non-uniform thickness resulting from each drop. It is difficult to obtain a solid membrane having a desired gas separation coefficient. For such a desirable supply of the solution, it is necessary to bring the supply means into contact with the liquid surface of the liquid support or to provide it near the liquid surface, as described above. The feeding speed of the solvent solution varies depending on the type of feeding means, the volatility of the solvent, etc., but when feeding from a preferably used feeding port with a small opening area, such as a circular or polygonal shape, it is, for example, about 0.1 to about 20 cm. .c./min,
The rate is preferably about 0.3 to about 10 c.c./min. In the method of the present invention, the liquid support is flowing from the solution supply means toward the position where the solid film formed from the liquid support is separated. By causing the liquid support to flow, the solvent solution rides the flow of the liquid support and expands spontaneously, so the continuous state change from the solvent solution to the formation of a solid film is extremely rapid. A solid membrane is formed which proceeds smoothly and therefore has a more uniform thickness and desired gas separation coefficient. The solid film formed on the liquid support is removed from the liquid surface of the support while being continuously entrained in the porous sheet. The porous sheet usually moves at a constant speed and moves along the liquid support so as to come out onto the liquid surface again. The porous sheet material can move so as to separate the solid membrane from the liquid surface when it runs along the liquid surface or when it emerges from the liquid surface. It is preferable that the rate is approximately equal to the rate of formation of the solid film at the liquid surface. That is, the speed is preferably set so that a large tension is not applied to the solid film when the solid film is separated from the liquid surface, and so that the solid film does not sag. According to the research conducted by the present inventors, the determination of such an appropriate speed can be carried out by moving the solid film formed on the liquid surface to the flow rate of the liquid support before the solid film is incorporated into the porous sheet-like material. The liquid surface of the liquid support is forcibly drawn in the direction at a substantially constant speed, thus forming a substantially stable flow of the solid film in advance, and then the porosity is It has been found that this can be done smoothly by moving the sheet-like material. The method for producing a solid film using a continuous method according to the present invention will be explained in more detail with reference to the accompanying drawings. FIG. 1 is a partial schematic plan view of an apparatus suitably used in the continuous solid film manufacturing method of the present invention. FIG. 2 is a schematic cross-sectional view of the apparatus of FIG. 1 taken along line A--A', further showing the porous sheet and other members necessary for its movement. In FIGS. 1 and 2, the liquid support 15
A smooth liquid surface 11 of the liquid support is formed in the liquid support tank 9 containing the liquid support. The liquid support can typically be water. The water supply pipe 3 provided in the tank 9 has a plurality of water supply ports 4, and water is continuously supplied from the water supply ports 4. The height of the liquid level 11 in the tank 9 is defined by the height of the tank 7. In other words, water overflows beyond Seki 7. In the drawing, water is supplied from water supply port 4 to 7.
The water that overflows the drain 7 is discharged from the water outlet 8 to the outside of the tank 9. The temperature of the water is constantly controlled by a temperature control device (not shown). In this case, the water does not necessarily have to overflow beyond the drain 7, and may be circulated within the tank so as to form the flow described above. The solution supply port 1 located in contact with the liquid surface 11 is located at the tip of a hollow tube extending from the reservoir 20 for the solvent solution. The reservoir 20 includes a heater 16 for heat retention or heating to maintain the temperature of the solution at a desired temperature, and continuously supplies the solvent solution from the reservoir 20 to the melting surface 11 through the supply port 1 at a constant rate. It is equipped with a plunger 19 for The solvent solution that is continuously supplied to the liquid level 11 at a constant rate is passed through the guide plate 2 that protrudes above the liquid level 11.
and guided by the water flow, it expands spontaneously along with the water flow, both perpendicular to and in the water flow direction. The information board 2 is
In addition to preventing the solution supplied from the supply port 1 to the liquid surface 11 from spreading in the direction opposite to the flow direction of the water,
Helps the solution spread in a direction perpendicular to the direction of water flow. Therefore, the guide plate 2 is preferably curved with its center on the side where the supply port 1 is located, and particularly preferably has a radius of curvature of about 10 cm to about 1 m. Further, the supply port 1 is preferably located on the center line of the arc of the guide plate 2 and at a distance of about 0.2 cm to about 10 cm from the guide plate 2. A solid film 15 is thus formed on the liquid surface 11.
is supplied from the supply roller 13 of the porous sheet-like material 12 and is taken up via the shaft 5 and the guide roller 14. When the porous sheet-like material 12 is placed in water, the be done. In this way, a solid membrane 15 supported on a porous sheet is obtained. In the figure, 6 is a preliminary winding roller;
Before incorporating the solid membrane into the porous sheet,
It is used to preform a stable and constant flow of solid film on the liquid surface. The supply port side of the guide plate 2, the solid film forming area of the water tank 9, and the side wall of the area from the guide plate 2 to the shaft 5 are made of a material to which a solid film does not adhere or a material whose surface has been treated with such a material. It is good that it is done. For example, fluororesins such as polytetrafluoroethylene, copolytetrafluoroethylene-hexafluoropropylene, etc. are used as materials that do not adhere to solid films, and silicone oils such as dimethylpolysiloxane are used as surface treatment materials that have similar effects. used as. According to the continuous method of the present invention, the width is about 70 cm.
Continuous solid membranes up to approximately 1 m in width can be easily produced, and under optimal conditions even up to about 1 m in width. In addition, the formed ultra-thin polymer film should be 10 cm or more, preferably 15 cm to 3 cm from the position where the solution contacts the liquid surface.
It is removed from the liquid surface at intervals of m. If this distance is shorter than 10 cm, the film will not solidify sufficiently and it will be difficult to spread uniformly. The polymer suitable for use in the production of the ultrathin film of the method of the present invention is composed of at least one of a hydrocarbon monomer having ethylenically unsaturated condensation and a hydrocarbon monomer having a conjugated unsaturated bond. The obtained addition polymer is suitable, and preferred examples thereof will be described later. The polymer is then supplied to the liquid surface of the liquid support as a solution obtained by dissolving the polymer in a solvent mainly consisting of a substantially water-immiscible organic liquid medium. In particular, in the continuous production method of the present invention, the polymer solution is an additive obtained from at least one of a hydrocarbon monomer having an ethylenically unsaturated bond and a hydrocarbon monomer having a conjugated unsaturated bond. The polymeric polymer is dissolved in a solvent consisting primarily of a volatile and substantially water-immiscible organic liquid medium capable of dissolving the addition polymer, the solvent having a partition coefficient as shown below in addition to the organic liquid medium. k k = 0.5 to 35 where k is the ratio of the concentration of the other organic compound in the organic liquid medium to the concentration in water. may contain other organic compounds having
In addition, the solvent has the following formula C ₁ − (a ₁ + b ₁ )≧25, where C ₁ is the surface tension of water (dyne/cm), and a ₁ is the surface of the solvent solution in which the addition polymer is dissolved in this solvent. Tension (dyne/cm) and b ₁ are the interfacial tensions (dyne/cm) between the solvent solution and water. It is desirable that it also satisfy the following. One of the preferred embodiments of the present invention is that the substantially water-immiscible organic liquid medium is volatile and capable of dissolving the hydrocarbon-based addition polymer, and The solvent mainly consists of the following formula (1)-a C ₁ -(a ₁ +b ₁ )≧25 ...(1)-a Preferably, the following formula (1)-b C ₁ -(a ₁ +b ₁ )≧35 ...(1)-b In the above formula, C ₁ is the surface tension of water (dyne/cm), a ₁
is the surface tension (dyne/cm) of a solvent solution in which the addition polymer is dissolved in this solvent, and b ₁ is the interfacial tension (dyne/cm) between the solvent solution and water. The purpose is to use a medium that has liquid surface characteristics that satisfy the following. By using a medium having such liquid surface characteristics, the obtained solvent solution spreads spontaneously, uniformly, and rapidly on the liquid surface of the liquid support consisting essentially of water. According to the research of the present inventors, the solvent mainly consisting of a medium having such liquid surface characteristics is a certain type of medium as described above, and the following distribution coefficient k k = 0.5 to 35, preferably 1.0 to 25. However, k is the ratio of the concentration of this other organic compound in the organic liquid medium to the concentration in water. It has been found that mixtures with other organic compounds having . The hydrocarbon addition polymer used in the present invention is an addition polymer obtained from at least one of a hydrocarbon monomer having an ethylenically unsaturated bond and a hydrocarbon monomer having a conjugated unsaturated bond. It is a polymerized polymer. Such hydrocarbon monomers have 2 to 2 carbon atoms.
Particularly preferred are 4 to 10 aliphatic or alicyclic compounds. Hydrocarbon monomers having ethylenically unsaturated bonds, such as, for example, ethylene, propylene, puran, isopran, pentene, methylpentene, hexene, methylhexene, heptene, cyclohexylpentene, styrene, α-methylstyrene, or mixtures thereof. Preferred compounds include hydrocarbon monomers having a conjugated unsaturated bond such as butadiene, isoprene, cyclooctadiene, or mixtures thereof. Methods for preparing addition polymers from such monomers are themselves well known to those skilled in the art. Such addition polymers used in the process of the invention may be homopolymers or copolymers of the monomers described above, and may be random, graft or block copolymers. Preferably a homopolymer is used. Examples of such homopolymers include, for example, polyethylene, polypropylene, polybutyne, polyisobutene, polyheptene, polymethylpentene, polyhexene, polymethylhexene, polyheptene, polycyclohexylpentene, polystyrene, polyα-methylstyrene; poly1,4-butadiene. , poly1,2
-butadiene, polyisoprene, polycyclooctadiene, etc. These addition polymers can be used alone or in combination of two or more. Particularly preferred are polybutene, polypentene, polymethylpentene, polyhexene, polymethylhexene, polybutadiene and polyisoprene;
Among these, polymethylpentene is preferred. These particularly preferred polymers have, among other things, relatively high gas permeability, do not soften at room temperature, and have pressure resistance. In the method of the present invention, a solution is used in which such a polymer is dissolved in the solvent as described above.
Suitable polymer concentrations range from about 0.5 to about
15 wt%, preferably about 1 to about 10 wt%. Such a dilute solution expands the selection of water-immiscible organic liquid media that can be used in the present invention that satisfy formula (1)-a above, and provides a liquid support consisting essentially of water. spontaneously and uniformly on the liquid surface,
And expand quickly. Being dilute does not prevent the medium from being removed mostly by volatilization at the liquid level and forming very thin solid films on the liquid level. In the process of the invention, as said water-immiscible organic liquid medium capable of forming the solvent used to provide such a solution, for example hydrocarbons or halogenated hydrocarbons can be used. These are preferably alicyclic or aromatic compounds. For example, cyclohexene, cyclohexane, trichlorethylene, tetrachloroethylene, trichloroethylene, trichloropropane or mixtures thereof. These water-immiscible organic liquid media are volatile and capable of dissolving the hydrocarbon addition polymers described above;
It does not have liquid level characteristics that satisfy the relationship expressed by -a. Such a water-immiscible organic liquid medium has a partition coefficient k of 0.5 to 35, preferably 1.0, as already mentioned above.
The above formula (1)- used in the method of the present invention by mixing with ~25 other organic compounds
Provide a solvent that satisfies a. In the method of the present invention, a solvent consisting of a water-immiscible organic liquid medium containing such other organic compounds is preferably used. As such other organic compounds, for example, alicyclic or aromatic alcohols, ketones, amines, aldehydes, carboxylic acids, peroxides, and mixtures thereof can be used. For example, cyclohexenol, cyclohexanol, phenol, cyclohexenone, cyclohexylamine,
Aniline, furftere, benzoic acid, cyclohexenyl peroxide, or mixtures thereof are particularly preferably used. These other organic compounds are contained in an amount of about 0.1 to about 15% by weight, preferably about 0.5 to about 10% by weight, based on the solvent used in the present invention. The presence of these other organic compounds in the solvent
Although it is volatile and dissolves the addition polymer used in the present invention, it does not by itself have a uniform film thickness, which is the goal of the present invention, and a gas separation coefficient that is almost equivalent to the inherent gas separation coefficient of the polymer. Converting water-immiscible organic liquid media which cannot be used in the process of the invention to produce solvents suitable for use in the process of the invention to produce extremely thin solid membranes with gas separation coefficients or large membrane areas. . It is believed that such other organic compounds are removed from the solution of the polymer on a liquid support consisting essentially of water by dissolving the majority thereof into the liquid support. Therefore, in the method of the present invention, most of the water-immiscible organic liquid medium in the solvent solution is removed by volatilization on the liquid support. This is a method for producing extremely thin solid films using a solvent consisting of a compound that dissolves in the liquid support and a water-immiscible organic liquid medium that volatilizes into the surrounding atmosphere. The extremely thin solid film obtained by the method of the present invention therefore does not contain substantially any appreciable amount of the other organic compounds without any special treatment after being separated from the liquid support. Consists of polymers. The solid membrane provided by the method of the present invention is extremely thin and has uniform thickness and excellent gas separation ability. In particular, the solid membrane supported by a porous sheet and produced by the continuous method of the present invention has the above-mentioned properties and can also be obtained as having a wide area. It can be used to produce a mixture of gases, such as air, enriched with certain gases, such as oxygen gas. The porous sheet material is used to compensate for the lack of autonomy of the solid membrane due to its thinness, and has virtually no effect on the gas separation ability of the solid membrane of the present invention. . Examples of such porous sheet materials include Japanese paper, nonwoven fabric, synthetic paper, paper, cloth, wire mesh, membrane,
Many small pores such as ultrafiltration membrane porous film,
Any sheet-like material that is smooth and self-supporting can be used. In particular, polyethylene porous films (e.g.
Sekisui Chemical Co., Ltd. (trade name: Celpore), polypropylene porous film (for example, Celanese Co., Ltd. (trade name: Celguard)), cellulose-based ultrafiltration membrane (for example, Fuji Film Co., Ltd. (trade name: Fuji Microfilter)),
Polycarbonate porous film (Nomura Mike
A polysulfone-based ultrafiltration membrane (trade name: Nucleipore, manufactured by Science Co., Ltd.) or a polysulfone-based ultrafiltration membrane (trade name: Toyo Ultrafilter, manufactured by Toyo Shisha Co., Ltd.) is preferably used, and polypropylene porous film is particularly suitable because it has good adhesion with the solid membrane of the present invention. preferable. The solid membrane produced by the method of the present invention can be supported on the porous sheet by stacking one or more layers on top of each other. In particular, the solid membrane of the present invention is
The solid membranes are stacked and supported on a porous sheet material (in this case, the thickness of the solid membranes is about 50 to about
5000 Å) exhibits excellent gas separation ability when used for gas separation, and in many cases has a gas separation coefficient that is almost equivalent to the original gas separation coefficient of the addition polymer that forms the solid membrane. shows. The resulting solid membranes therefore rarely require stacking in more than two layers to obtain the desired gas separation performance. In order to stack a plurality of solid membranes on a porous sheet-like material, for example, in the continuous method of the present invention as described above, a porous sheet-like material supporting the solid membrane of the present invention can be used instead of the porous sheet-like material. It can be manufactured in exactly the same manner using . The porous sheet-like material supporting the solid membrane of the present invention (hereinafter sometimes referred to as composite film) can be used for gas separation in the state already produced as described above, Also,
Before use in such applications, the solid film should be prepared under such temperature and time conditions that it will not melt (e.g., in the case of atmospheric heating, for example, 60° to 300°
°C, preferably 80° to 200°C, for example 3 seconds to 50°C.
It is also possible to further improve the adhesion between the solid membrane and the porous sheet material by heat treatment for a period of time (preferably from 5 seconds to 20 hours), and then use the solid membrane. The solid membrane produced by the method of the present invention typically has a molecular weight of about 50 to about 3000
It has a thickness of Å. The obtained solid membrane is used to obtain a gas enriched with a certain specific gas from a mixture of two or more gases, as described above. For example, production of oxygen-enriched air from the atmosphere, production of _H2- enriched gas from a gas mixture containing _H2 and CO, removal of _H2O from a gas mixture containing _H2O , _SO2 and/or or SO ₂ and/or from a gas mixture containing nitrogen oxide gas (NOx).
or removal of NOx, from mixed gases containing He.
Used in the production of He-enriched gas, etc. It is particularly preferably used for producing oxygen-enriched air (eg, oxygen content of about 30 to about 45%) from the atmosphere. Examples 1 to 4, Comparative Examples 1 to 3 Poly 4-methylpentene-1 (Mitsui Petrochemical
A polymer solution was prepared by dissolving 5.0 parts by weight of TPX DX-810 (trade name, manufactured by Co., Ltd.). The surface tension of the polymer solution (a ₁ ), the surface tension of water (c ₁ ), and the interfacial tension of the polymer in water (b ₁ ) at 25°C are 17.8 dyn/cm, 72.0 dyn/cm, and 8.2 dyn/cm, respectively. It was hot. The value of {c ₁ − (a ₁ + b ₁ )} obtained from this is
It is 46.0dyn/cm. Also, the partition coefficient of cyclohexene hydroperoxide (concentration in cyclohexene/concentration in water) is
It was 2.6. The ultrathin polymer membrane of the present invention was continuously produced from this polymer solution using the apparatus shown in FIGS. 1 and 2 by changing the flow rate of the liquid support and other factors. The polymer solution was maintained at 30°C at a temperature of 20°C, and was continuously fed from the supply port 1 in contact with the water surface to the water surface 11 at 61°C.
It was supplied at a rate of cc/hr. The radius of curvature of the guide plate 2 in the example is 30 cm, the arc length of the guide plate is 40 cm, and the distance from the center of the guide plate to the solution supply port is 20 cm. In the embodiment, the material of the guide plate 2 and the side wall of the water tank 9 is a sheet of tetrafluoroethylene, and the surface of the guide plate is treated with silicone oil to prevent attachment of an extremely thin polymer film. The water supply pipe 3 provided in the water tank 9 has a plurality of water supply ports 4, and water is continuously supplied from the water supply ports 4. In the drawing, water flows from the water supply port 4 toward the drain 7, and the water that overflows the drain 7 is discharged from the water outlet. Note that the water supplied from the water supply port 4 is controlled at 4°C, and the water in the water tank is controlled within the temperature range of 4 to 5°C. At the beginning of the continuous production of the ultra-thin polymer film, the ultra-thin polymer film was wound up by the pre-winding roller 6 for about 3 minutes until it was confirmed that the ultra-thin polymer film was being stably manufactured. . Next, a polypropylene porous membrane 12 having a thickness of 25 μm and a width of 30 cm is fed into the water from a winding roller 13 at a predetermined speed via a guide roller 5 to entrain the ultra-thin polymer membrane, and then driven. It was taken over via roller 14. In this example, the average velocity of the flow of the liquid support is defined as the volume per minute of the liquid support discharged by overflowing the tank 9, which is obtained by cutting the volume per minute in the direction perpendicular to the winding direction of the ultrathin polymer film. The value is expressed as the cross-sectional area of the liquid support. In addition, the membrane performance of the ultrathin polymer membrane in the examples is expressed as the ratio of the oxygen permeability coefficient to the nitrogen permeability coefficient (hereinafter referred to as selectivity), and these permeability coefficients were measured using a gas permeability measuring device (Rika Co., Ltd.). Measured using a Ki-made 3BR-SSS). The results are shown in Table 1. 【table】

[Brief explanation of the drawing]

The attached drawings schematically show an apparatus for continuously producing ultrathin polymer membranes of the present invention. That is, FIG. 1 shows a schematic plan view of a part of the manufacturing apparatus, and FIG. 2 is a schematic sectional view taken along the line A-A' of the apparatus in FIG. 1, and further shows the porous sheet material and its operation. Other parts required for this are shown.
To explain in more detail using FIGS. 1 and 2, the ultra-thin film continuous device of the present invention has the following structure. (1) Polymer solution supply system Polymer solution supply means 1 set so as not to leave the liquid surface of the liquid support; metering pump 19 for supplying polymer solution; polymer solution temperature control section 20; Control devices 16, 17. (2) Ultra-thin polymer film forming section guide plate 2; liquid support 2 consisting essentially of water
1; Supply parts 3, 4 for the liquid support; Weir 7 for overflow of the liquid support and its drainage part 8; Tank 9 for the liquid support. (3) Ultra-thin polymer membrane winding system Sheet-like porous support unwinding section 13; guide rollers 5, 14 for the porous support; preliminary winding roller 6 for the ultra-thin membrane at the start of membrane production.

Claims (1)

[Claims] 1. A polymer solution in which a polymer capable of forming an ultra-thin film is dissolved in a solvent mainly consisting of a substantially water-immiscible organic liquid medium is supplied to the liquid surface of a liquid support consisting essentially of water. A series of ultra-thin polymer films that are made to expand spontaneously on the liquid surface to form an ultra-thin film of the polymer, and then are continuously taken out from the liquid surface while being accompanied by a sheet-like porous support. In the manufacturing method, the solution is continuously supplied from the supply means in such a way that the solution and the liquid surface are in contact with each other so that they do not separate, and the liquid support is placed at a distance of 10 cm to 10 cm from the position where the solution contacts the liquid surface. 0.001 m/min or more in the direction of the take-out part of the ultra-thin polymer membrane located at a distance of 3 m,
A method for continuously producing an ultra-thin polymer membrane, characterized in that a flow is formed at an average speed of 1.2 times or less than the take-out speed of the ultra-thin polymer membrane.