JP4715733B2 - Manufacturing method of reverse osmosis membrane - Google Patents

Description

  The present invention relates to a dry and wet spinning method for forming a hollow fiber-like reverse osmosis membrane made of a polymer material and excellent in water permeability.

  Conventionally, a dry and wet spinning method has been widely used as a method for forming a hollow fiber membrane. The dry-wet spinning method is a polymer raw material, a solvent and, if necessary, a non-solvent and other additives are added and dissolved to prepare a film-forming stock solution (dope). This is a film forming method in which a coagulation bath is passed after passing through the part. For the nozzle on the left, a C-type nozzle, arc-type nozzle, double-tube type nozzle, etc. are used, and a hollow part is formed by sending gas or liquid into the film-forming stock solution or by accompanying it by self-suction. . The obtained hollow fiber membrane is further subjected to washing, heat treatment and the like as necessary.

  In the dry-wet spinning method, by setting the nozzle temperature high, the temperature of the discharged film-forming stock solution is increased, the solvent evaporation from the surface of the film-forming stock solution in the aerial traveling section is promoted, and the outer surface is dense. A separation active layer can be formed, but on the other hand, the water permeation performance tends to decrease. On the other hand, it is important to form an asymmetric structure in order to improve water permeability. The discharged membrane forming stock solution is cooled to lower the temperature and cause phase separation from the outer surface to form a porous structure in the inner part of the hollow fiber, or to suppress the evaporation of the solvent in the aerial running part and to form a dense layer By reducing the thickness, the water permeability is improved.

By extruding a thermal dope in which cellulose ester is dissolved in a solvent into the evaporation zone (a chimney-like compartment surrounding the spinneret), passing through an ice-water temperature coagulation bath consisting of water and further annealing in a hot water bath, A technique for obtaining a hollow fiber type reverse osmosis membrane is disclosed (see Patent Document 1). By extruding the spinning dope into a solvent-rich atmosphere of cellulose ester, the evaporation of the solvent from the thermal dope is suppressed, the dope extruded by cooling rapidly gels, and faces the hollow area from the outer surface. As a result, an asymmetric structure (outer-core structure) having a density gradient gradually becoming less and denser toward the surface is obtained. Patent Document 1 describes that the thermal dope is rapidly cooled in the evaporation phase, but does not include description or suggestion about positively adjusting the temperature of the evaporation zone. Patent Document 1 discloses only an example of a medium pressure reverse osmosis membrane, and does not disclose a high pressure and high salt removal rate reverse osmosis membrane that can be used for seawater desalination.
JP 47-4010 A

Also disclosed is a method for producing a hollow fiber membrane by a thermally induced phase separation method in which a spinning space between a spinneret and a coagulation bath is surrounded so as to maintain an unsealed state, and a membrane-forming solution is discharged into the spinning space. (See Patent Document 2). The temperature of the space between the spinning nozzle and the coagulation bath (spinning space) and the influence of fluctuations in solvent vapor pressure are suppressed, and the spinning space is filled with saturated solvent vapor and heat is accumulated. As a measure to prevent this, it is said that it is appropriate to enclose it so as to maintain an unsealed state. The main purpose of this enclosure is to suppress changes in the solvent vapor pressure and temperature in the spinning space due to fluctuations in temperature and airflow due to ambient disturbance, and the effect of the invention is to stabilize a hollow fiber membrane with small variations in characteristics. That can be manufactured in the same manner, and that yarn breakage during spinning is suppressed. There is no description or suggestion of actively cooling the spinning space, thereby improving the structure of the hollow fiber membrane and improving the water permeability.
JP 2004-174408 A

Further, a technique is disclosed in which a high-performance hollow fiber separation membrane can be stably manufactured by covering the aerial traveling part with a member having a heat insulating structure in a dry and wet spinning method and blocking outside air. (See Patent Document 3). In this case as well, it is a technical idea to stabilize the hollow fiber membrane characteristics so that the aerial traveling part is not affected by surrounding disturbances, and the performance of the hollow fiber membrane is improved by actively cooling the aerial traveling part. It is not intended to improve water permeability.
JP-A-7-194950

According to Patent Document 4, the gas atmosphere between the spinning nozzle and the coagulation bath is partitioned with a cylindrical object, shielded from the outside air, controlled to be lower than the coagulation bath temperature, and in addition to non-solvent vapor, liquid non-solvent Since the amount of the non-solvent absorbed from the outer surface of the yarn is remarkably increased by generating the mist consisting of, the hole diameter of the outer surface of the hollow fiber membrane is large and the aperture ratio is high. A porous hollow fiber membrane excellent in water permeability can be easily obtained. As it is understood from the fact that this technique is suitable for forming micropores having an outer surface pore diameter of 0.02 to 2 μm, and the disclosed examples are only related to ultrafiltration membranes, It is not suitable for producing a reverse osmosis membrane, particularly a reverse osmosis membrane having a highly dense layer applicable to seawater desalination. In addition, it is exemplified that a constant temperature refrigerant is allowed to flow through the cooling jacket as a temperature control method for the portion partitioned by the cylindrical object, but it is large-scale to cool the cylindrical object by flowing the refrigerant through the jacket, If the length is short, there are problems including workability.
JP-A-3-202131

In Patent Document 5, a hollow fiber spun into a guide pipe that is installed between a spinneret and a coagulation bath and temperature-controlled air is fed inside is brought into contact with the coagulation bath. Thus, a technique for controlling the structure of the porous hollow fiber is disclosed. In this method, the membrane-forming stock solution discharged from the nozzle by air feeding is shaken to cause spots in the stretched state and solidified state of the hollow fiber membrane, resulting in spots in membrane performance. There are problems such as fusing and defects in the hollow fiber membrane. In addition, since air is sent in, the solvent concentration in the aerial traveling part becomes very low, and the volatilization of the solvent from the discharged film forming stock solution tends to be too large. There is a problem that the density and the thickness tend to increase, leading to a decrease in water permeability.
Japanese Patent Laid-Open No. 01-192811

  It is an object of the present invention to provide a dry and wet spinning film forming method for forming a hollow fiber type reverse osmosis membrane having both high water permeability and high removal performance by cooling an aerial traveling part by a simple method.

As a result of intensive studies on the dry and wet spinning method for hollow fiber membranes, the present inventors have reached the present invention. That is, the present invention includes the following configuration.
(1) Drying and wet spinning manufactured by obtaining a hollow fiber type reverse osmosis membrane by discharging a film-forming stock solution containing at least a polymer raw material, a solvent, and a non-solvent from a nozzle, and running in an aerial running part and immersing in a coagulation liquid A method for producing a reverse osmosis membrane, characterized in that an aerial traveling part is surrounded by a heat transfer cooling member having air permeability, and a part of the heat transfer cooling member is immersed in a coagulating liquid.
(2) The method for manufacturing a reverse osmosis membrane according to (1), wherein the aerial traveling unit is partitioned by a non-breathable partition member, and the partitioned aerial traveling unit communicates with the outside.
(3) The method for producing a reverse osmosis membrane according to (1) or (2), wherein the heat transfer cooling member has a thermal conductivity of 10 kcal / (m · h · ° C.) or more.
(4) The heat transfer cooling member is made of a material mainly composed of at least one selected from iron, copper, stainless steel, aluminum, silver, and titanium. The manufacturing method of the reverse osmosis membrane of description.
(5) The method for producing a reverse osmosis membrane according to any one of (1) to (4), wherein the distance between the heat transfer cooling member and the membrane forming stock solution discharged from the nozzle is 5 mm or more and 50 mm or less.
(6) The method for producing a reverse osmosis membrane according to any one of (1) to (5), wherein the length of the aerial traveling unit is 5 mm or more and 50 mm or less.
(7) The method for producing a reverse osmosis membrane according to any one of (1) to (6), wherein the temperature of the nozzle that discharges the membrane-forming stock solution is made 100 ° C. or more higher than the temperature of the coagulation solution.
(8) The method for producing a reverse osmosis membrane according to any one of (1) to (7), wherein the polymer raw material is a cellulose acetate polymer.

  It is possible to provide a dry-wet spinning method capable of forming a hollow fiber type reverse osmosis membrane having high water permeability by cooling an aerial traveling portion by a simple method and suppressing solvent evaporation of a membrane forming stock solution. it can. Further, since the temperature and humidity and the solvent concentration of the aerial traveling section are stabilized, the hollow fiber type reverse osmosis membrane obtained by the present invention is excellent in that the fluctuation of the membrane performance is small.

  The polymer material in the present invention is not particularly limited as long as it is a polymer material that can be dissolved in a solvent and can exhibit reverse osmosis membrane performance. For example, cellulose acetate polymers, polysulfone polymers, polyvinyl alcohol polymers, polyamide polymers, polyacrylonitrile polymers, and chemically modified polymers of these polymers And a polymer mixture and a polymer alloy. Among them, it is preferable to use a cellulose acetate-based, polysulfone-based, or polyamide-based polymer, which is relatively easy to express the high water permeability and salt removal performance required for a reverse osmosis membrane. In particular, cellulose triacetate polymer is preferable from the viewpoint of chemical resistance and bacteria resistance.

  The solvent in the present invention is not particularly limited as long as it can dissolve the polymer raw material. The non-solvent is not particularly limited as long as it is a material that cannot dissolve the polymer raw material but dissolves in the solvent. Here, the solvent capable of dissolving the polymer raw material is a solvent capable of dissolving 5% by weight or more of the polymer raw material at a temperature not lower than 60 ° C. and not higher than the melting point of the polymer. For example, when the polymer raw material is cellulose triacetate, examples of the solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide and the like, and examples of the non-solvent include water, ethylene Examples thereof include polyhydric alcohols such as glycol, diethylene glycol, triethylene glycol, and tetraethylene glycol.

The reverse osmosis membrane in the present invention is a separation membrane in a region having a separation characteristic with a molecular weight of several tens of daltons. Specifically, the reverse osmosis membrane is a reverse osmosis membrane module for water supply according to Membrane Separation Technology Promotion Standard AMST-002, and the test solution has a sodium chloride concentration of 500 to 2,000 mg / L and an operating pressure of 0.5. It is defined as a membrane having a sodium chloride removal rate of 93% or more under the evaluation condition of ˜3.0 MPa, and the seawater desalination reverse osmosis membrane used for seawater desalination is a membrane as a seawater desalination reverse osmosis membrane module for water supply. Separation technology promotion association standard AMST-003 5.2 water flow capacity and sodium chloride removal rate obtained by sodium chloride removal performance or TDS removal performance test, the sodium chloride concentration or TDS concentration of the test solution is 3.0 × In the range of 10 ^{4 to} 6.0 × 10 ⁴ mg / L, the average concentration reference removal rate is 99.0% or more under the evaluation conditions of the operating pressure of 5.0 to 10.0 MPa. It is defined as a film having a rate of 98.8% or more.

  In the present invention, the heat transfer cooling member is a member having a temperature lower than that of the aerial traveling unit around the aerial traveling unit, and the heat of the aerial traveling unit is moved and dissipated to the outside of the coagulation bath and the aerial traveling unit by heat transfer. This has the effect of simply lowering the temperature of the running section. Further, since the outside air flowing into the aerial traveling part passes through the air-permeable heat transfer cooling member and reaches the aerial traveling part, it is cooled by heat exchange when passing through the inside of the heat transfer cooling member. The heat transfer cooling member utilizes the low temperature of the coagulation bath and contacts the coagulation bath to transfer heat to the coagulation bath. As a matter of course, it is assumed that the temperature of the coagulation bath is lower than the temperature of the film-forming stock solution, and the temperature of the aerial traveling section does not become lower than the temperature of the coagulation solution. Note that the present invention is applicable even when the length of the aerial traveling unit is short and it is difficult to control the temperature of the aerial traveling unit using a jacket or a device.

  In order to efficiently transfer heat, the heat transfer cooling member is preferably formed of a material having high thermal conductivity, and the thermal conductivity is preferably 10 kcal / (m · h · ° C.) or more, more preferably, 50 kcal / (m · h · ° C.) or more, more preferably 100 kcal / (m · h · ° C.) or more. When the heat transfer cooling member is made of a material having a thermal conductivity of less than 10 kcal / (m · h · ° C.), it is preferable because the effect of moving heat is small and the temperature of the aerial traveling part cannot be effectively reduced. Absent.

  Examples of the material having high thermal conductivity include metal materials, and preferred examples include titanium, iron, aluminum, copper, silver, and alloys containing these as main components. Stainless steel (SUS304, SUS304L, SUS316, SUS316L, SUS317, SUS317L, etc.) is also a typical example of a preferable material. However, since the heat transfer cooling member is in contact with the coagulation liquid in the coagulation bath and the solvent volatilized from the dope, it is necessary to consider insolubility, corrosion resistance, and the like. In addition, material cost and workability are important factors in practical use. Considering these comprehensively, stainless steel, aluminum and copper are particularly preferable.

  The shape of the heat transfer cooling member in the present invention is not particularly limited as long as it satisfies the purpose of heat transfer and has air permeability. Moreover, in order to efficiently carry out the heat transfer around the aerial traveling section, a shape such as a net shape, a lattice shape, a slat shape, or a perforated plate having a high contact efficiency is preferable. Here, the action mechanism of the heat transfer cooling member will be described from the viewpoint of air balance and flow in the vicinity of the aerial traveling section.

  First, considering the air balance in the vicinity of the aerial traveling part, the dissolution of the air into the discharged film-forming solution occurs and is taken away from the vicinity of the aerial traveling part. Occurs. Furthermore, when the nozzle is a C-type nozzle or an arc-type nozzle, the air around the nozzle is continuously sucked into the hollow part and sent out while confined inside the hollow fiber membrane. Is continuously discharged to the outside of the aerial traveling unit, and in order to replenish this, inflow of air from the outside always occurs in the vicinity of the aerial traveling unit. The air that flows in from the outside by these actions is cooled when passing through the inside of the heat transfer cooling member, and as a result, the air in the aerial traveling section is cooled. If the heat transfer cooling member does not have air permeability, such an effect does not occur, and the cooling efficiency of the aerial traveling portion decreases, which is not preferable.

  Considering the flow of air in the vicinity of the aerial traveling unit, as the discharged film forming solution travels toward the coagulation bath, an accompanying flow is generated in the surrounding air. Is always flowing. When the aerial traveling section is partitioned and the heat transfer cooling member is installed inside, the flowing air comes into contact with the heat transfer cooling member and is cooled, and the circulating flow that circulates again to the film forming stock solution discharge section Arise. High contact efficiency of the heat transfer cooling member is preferable because heat exchange at this time is efficiently performed and the temperature of the aerial traveling unit can be lowered.

  In the present invention, an embodiment in which the aerial traveling unit is partitioned by a non-breathable partition member is preferable. It is possible to reduce the influence of temperature and humidity changes and air flow fluctuations in the aerial traveling part due to environmental changes around the aerial traveling part such as weather conditions, seasonal fluctuations, indoor air conditioning conditions, etc., and stabilize the performance of the produced hollow fiber membrane Because. Even when the aerial traveling part is not partitioned by a non-breathable partition member, the same effect can be obtained to some extent by the breathable heat transfer cooling member. Further, higher stability can be obtained. In addition, when the aerial traveling section is partitioned by a non-breathable partition member, the solvent concentration in the partition increases due to the volatilization of the solvent from the discharged film-forming stock solution, and further volatilization of the solvent from the discharged film-forming stock solution. It is in a tendency to be able to obtain a hollow fiber membrane with high water permeability.

  Of the present invention, in the embodiment in which the aerial traveling unit is partitioned, a non-breathable partition member is used as the partition member. The partition member is preferably a member mainly made of glass. Glass exhibits a low thermal conductivity of about 0.5 to 1 kcal / (m · h · ° C.), and is therefore preferable in that it does not cause excessive cooling of the aerial traveling portion due to heat radiation to the coagulation bath. Further, it is excellent in corrosion resistance and chemical stability, has sufficient durability against a coagulation bath, a discharged film forming solution and a solvent volatilized therefrom, and is excellent in that it can withstand high temperatures. Moreover, since it is transparent, the running state of the hollow fiber membrane can be observed from the outside, and it is also a preferable member because it is inexpensive and easily available, and is excellent in workability. In addition, members mainly composed of polymer materials such as polyethylene and polypropylene are also a combination having durability against the components used in the film-forming stock solution and the coagulation bath because of its low thermal conductivity and chemical stability, and heat resistance. If is not a problem, it can be used as a partition member. In addition, it is also possible to combine with a frame-like metal member as a position fixing means for the partition member, to have a wire mesh for maintaining strength, or to be used in combination with a metal member for other purposes.

  In the present invention, in the embodiment in which the aerial traveling unit is partitioned, the partition needs to be communicated with the outside. As already described, since air in the aerial traveling part is discharged from the vicinity of the aerial traveling part along with the hollow fiber membrane, inflow of air from the outside to the aerial traveling part is essential. If all the openings other than the coagulation bath side of the compartment are to be airtight, if the film formation is continued for a long time, the inside of the compartment becomes a negative pressure and the coagulation bath is sucked up, making the film formation impossible. A method of communicating the partitioned aerial traveling unit and the outside is not particularly limited, but a method of providing a gap in the partition, a hole, or the like can be employed. When the heat transfer cooling member is outside the compartment, the air cooled by the heat transfer cooling member flows into the aerial travel portion from the communication portion of the compartment, and the aerial travel portion is cooled. When the heat transfer cooling member is inside the compartment, the air flowing in from the communication portion of the compartment is cooled by the heat transfer cooling member and then flows into the aerial travel unit, whereby the aerial travel unit is cooled. In addition, if the inflow of air from the communication portion is uneven, the performance of the hollow fiber membrane may vary. The structure of the communication portion is preferably a structure that can ensure an even air inflow and a cooling state.

  The length of the aerial traveling unit in the present invention is the shortest distance from the nozzle surface from which the film-forming stock solution is discharged to the coagulation bath liquid surface. The length of the aerial travel part is preferably 50 mm or less, more preferably 40 mm or less, and even more preferably 30 mm or less. In order to cause the solvent evaporation and the phase separation to proceed in the aerial traveling part, the length of the aerial traveling part is preferably 5 mm or more. If the length of the aerial traveling part is too long, cooling of the aerial traveling part by the heat transfer cooling member becomes insufficient, and the effect of the present invention is not sufficiently exhibited, which is not preferable. In addition to the method of the present application, for example, a cooling method using a jacket or the like is known as a cooling means for the aerial traveling unit, but a facility for adjusting the temperature of the jacket or the like is required, and the equipment cost and operation cost of the production equipment are required. Increase factor. In the present invention, since only the heat transfer cooling member is installed and no control mechanism is required, it has an effect of reducing the equipment cost and the operation cost of the production equipment as compared with the cooling system such as a jacket.

  In the present invention, being surrounded by the heat transfer cooling member in the aerial traveling section means that the heat transfer cooling member is arranged around the discharged film forming stock solution, and does not mean shutting off from the outside in a sealed state. . Rather, it is preferable to have air permeability and also use convective heat transfer. When there are a plurality of film-forming stock solutions to be discharged, they may be enclosed individually, or the entire plurality of film-forming stock solutions may be enclosed by one heat transfer cooling member. The shape of the heat transfer cooling member is not particularly limited as long as it satisfies the purpose of heat transfer.

  The distance between the film-forming stock solution discharged from the nozzle in the aerial traveling unit and the heat transfer cooling member in the present invention refers to the shortest distance between the film-forming stock solution discharged from the nozzle in the aerial traveling unit and the heat transfer cooling member, and from the nozzle In the case where there are a plurality of discharged film forming stock solutions, the average distance of values related to each film forming stock solution is used. The shorter the distance, the greater the cooling effect of the heat transfer cooling member, preferably 50 mm or less, more preferably 40 mm or less, and even more preferably 30 mm or less. The film-forming stock solution discharged from the nozzle travels with a slight fluctuation width in the aerial travel section. The distance between the film forming stock solution and the heat transfer cooling member is preferably 5 mm or more so as not to come into contact with the heat transfer cooling member within the range of the swing width and to cause temperature unevenness of the aerial traveling portion.

  By using the heat transfer cooling member of the present invention, it is possible to easily cool the aerial traveling unit, and therefore, even when the nozzle temperature is high and the aerial traveling unit length is short, evaporation of the solvent in the aerial traveling unit can be suppressed. By reducing the thickness of the dense layer, water resistance can be reduced and water permeability can be increased. Furthermore, by discharging the membrane-forming solution into an atmosphere rich in low-temperature polymer solvent, it can be rapidly gelled, causing phase separation from the outer surface and making the hollow fiber inner layer part as porous as the inner layer part. A highly porous structure can be formed, and a reverse osmosis membrane exhibiting high water permeability can be realized. In the film-forming method in which the surrounding air is sucked into the hollow portion, such as a C-type nozzle or arc-type nozzle, the shape of the nozzle from which the film-forming stock solution is discharged, the temperature and humidity and the solvent concentration of the air in the aerial traveling part are It affects the structure formation of the inner layer of the hollow fiber membrane. The lower the temperature of the sucked air and the lower the solvent concentration, the faster the phase separation of the inner layer part, so that it is easy to form a highly porous structure. In this respect, there is an advantage of using the heat transfer cooling member in the aerial traveling part. Also, by promoting cooling of the film-forming stock solution after nozzle discharge, the diffusion of the polymer solvent in the film-forming stock solution is reduced, and the density gradient from the outer surface toward the surface facing the hollow region is increased. be able to. By increasing the density gradient, it is possible to obtain a highly water-permeable hollow fiber membrane with a thin dense layer and low permeation resistance.

  As specific temperature conditions during film formation, for example, when the membrane material is cellulose triacetate, the nozzle temperature is 180 to 100 ° C. and the coagulating liquid temperature is preferably 50 to 0 ° C., more preferably the nozzle temperature is 160 to The coagulating liquid temperature is 20 to 5 ° C at 120 ° C. If this coagulating liquid temperature is high, the amount of heat transfer through the heat transfer cooling member is small and it is difficult to obtain a cooling effect, and if the coagulating liquid temperature is low, the amount of heat transfer is large and the cooling effect is large, which is preferable. The nozzle temperature is preferably at least 100 ° C. higher than the coagulation bath temperature.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Reference Example 1)
(Film formation of hollow fiber type reverse osmosis membrane for seawater desalination)
40 parts by weight of commercially available cellulose triacetate (manufactured by Daicel Chemical Industries, Ltd., 61.5% acetylation), 18 parts by weight of ethylene glycol (manufactured by Mitsui Toatsu Chemical Co., Ltd.) and N-methyl-2-pyrrolidone (Mitsubishi Chemical) (Made by Co., Ltd.) After mixing a solution consisting of 42 parts by weight, the temperature was raised to obtain a film-forming stock solution. After this solution was degassed under reduced pressure, the film-forming stock solution was discharged from a three-part arc type nozzle at about 145 to 155 ° C. After passing through an aerial traveling part with a distance L3 = 25 mm, which is partitioned by a glass tube in communication with the outside, 60 parts by weight of water, 12 parts by weight of ethylene glycol and 28 parts by weight of N-methyl-2-pyrrolidone A hollow fiber membrane was obtained by being led into a coagulating liquid cooled to 13 to 15 ° C. composed of parts. The temperature difference between the nozzle temperature and the coagulating liquid was about 131-141 ° C. Subsequently, the hollow fiber membrane was sufficiently washed with water and then subjected to hydrothermal treatment at 95 ° C. to 98 ° C. for 20 minutes to obtain a high-pressure hollow fiber type reverse osmosis membrane having an outer diameter of 137 μm and an inner diameter of 53 μm and compatible with seawater desalination. The reverse osmosis performance of the hollow fiber membrane was measured under the conditions of an operating pressure of 5.4 MPa, a sodium chloride concentration of 35,000 mg / L in the feed water, a recovery rate of 5% or less, and a feed water temperature of 25 ° C.

(Reference Example 2)
(Membrane production of hollow fiber reverse osmosis membrane for desalination of canned water)
Commercially available cellulose triacetate (Daicel Chemical Industries, Ltd., acetylation degree 61.5%) 38 parts by weight ethylene glycol (Mitsui Toatsu Chemical Co., Ltd.) 19 parts by weight and N-methyl-2-pyrrolidone (Mitsubishi Chemical) (Made by Co., Ltd.) A solution consisting of 43 parts by weight was mixed and then heated to obtain a film-forming stock solution. After this solution was degassed under reduced pressure, the film-forming stock solution was discharged from a three-part arc type nozzle at about 145 to 155 ° C. After passing through an aerial traveling part with a distance L3 = 20 mm, which is partitioned by a glass tube in communication with the outside, 60 parts by weight of water, 12 parts by weight of ethylene glycol and 28 weights of N-methyl-2-pyrrolidone A hollow fiber membrane was obtained by being led into a coagulating liquid cooled to 12 to 14 ° C. composed of parts. The temperature difference between the nozzle temperature and the coagulating liquid was about 132-142 ° C. Next, the hollow fiber membrane was washed thoroughly with water and then subjected to hot water treatment at 80 ° C. to 83 ° C. for 20 minutes to obtain a hollow fiber type reverse osmosis membrane having an outer diameter of 175 μm and an inner diameter of 85 μm and suitable for brine desalination. . The reverse osmosis performance of the hollow fiber membrane was measured under conditions of supply water pressure of 2.9 MPa, supply water sodium chloride concentration of 1500 mg / L, recovery rate of 5% or less, and supply water temperature of 25 ° C.

(Production of fluid separator)
The obtained hollow fiber type reverse osmosis membrane was bundled and inserted into a plastic sleeve, and then a thermosetting resin was poured into the sleeve, cured, and sealed. An end surface of the hollow fiber type reverse osmosis membrane cured with the thermosetting resin was cut to obtain an opening surface of the hollow fiber membrane, and a test module was prepared. This test module was connected to a membrane performance test facility consisting of a feed water tank, a low pressure pump, and a high pressure pump to obtain a fluid separation device.

(Measurement of reverse osmosis performance)
After the fluid separator was operated for 2 hours or longer with a saline solution having a supply pressure of 5.4 MPa, a supply liquid temperature of 25 ° C., and a supply concentration of 35000 mg / L, a permeate was collected from the opening surface of the hollow fiber membrane for a predetermined time. And the permeate salt concentration was measured. Water permeation performance and salt removal rate were calculated according to the following formula.
Water permeation performance [L / m ² / day] = collected permeate volume [L] / membrane area [m ² ] / (collection time [min] / 1440)
Salt removal rate [%] = (1-permeate salt concentration [mg / L] / feed salt concentration [mg / L]) × 100

Example 1
A cylindrical object made of 20 mesh SUS304 stainless steel wire mesh as a heat transfer cooling member around the outer periphery of the glass tube that divides the aerial traveling part has an average distance L2 = 30 mm from the film forming stock solution, and a coagulation liquid immersion depth L4 = 20 mm. A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Reference Example 1 except that the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The thermal conductivity of SUS304 stainless steel was 14 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 62 L / m ² / day and 99.9%, respectively.

(Example 2)
A cylindrical object made of 20 mesh SUS304 stainless steel wire mesh as a heat transfer cooling member around the outer periphery of the glass tube that divides the aerial traveling section has an average distance L2 = 30 mm from the film forming stock solution, and a coagulation liquid immersion depth L4 = 20 mm. A hollow fiber membrane for canned water desalting and a fluid separation device were produced in the same manner as in Reference Example 2 except that the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 133 ° C. The thermal conductivity of SUS304 stainless steel was 14 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 240 L / m ² / day and 99.0%, respectively.

(Example 3)
Instead of the wire mesh around the outer periphery of the glass tube that divides the aerial traveling part, an 18 mesh mesh is formed on the inner periphery of the glass tube so that the average distance L1 = 25 mm from the film forming stock solution and the coagulation liquid immersion depth L4 = 20 mm. A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 1 except that a SUS304 stainless steel wire mesh was installed, and reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The thermal conductivity of SUS304 stainless steel was 14 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 63 L / m ² / day and 99.9%, respectively.

Example 4
18 mesh on the inner periphery of the glass tube so that the average distance L1 = 25 mm from the film-forming stock solution and the coagulation liquid immersion depth L4 = 20 mm, instead of the wire mesh around the outer periphery of the glass tube that divides the air travel section A hollow fiber membrane for canned water desalting and a fluid separator were prepared in the same manner as in Example 2 except that the SUS304 stainless steel wire mesh was installed, and the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 133 ° C. The thermal conductivity of SUS304 stainless steel was 14 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 245 L / m ² / day and 99.0%, respectively.

(Example 5)
18 mesh SUS304 stainless steel wire mesh on the outer and inner perimeters of the glass tube that divides the aerial traveling part, the average distance from the film forming stock solution is L2 = 30 mm, L1 = 25 mm, and the coagulation liquid immersion depth L4 is 20 mm. A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 1 except that they were installed so that the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 135 ° C. The thermal conductivity of SUS304 stainless steel was 14 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 64 L / m ² / day and 99.9%, respectively.

(Example 6)
An 18 mesh SUS304 stainless steel wire mesh is placed on the outer and inner perimeters of the glass tube that divides the aerial traveling section. The average distance from the film forming stock solution is L2 = 30 mm, L1 = 25 mm, and the coagulation liquid immersion depth L4 is A hollow fiber membrane for canned water desalting and a fluid separation device were prepared in the same manner as in Example 2 except that the thickness was set to 20 mm, and the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The thermal conductivity of SUS304 stainless steel was 14 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 247 L / m ² / day and 99.0%, respectively.

(Example 7)
A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 3 except that the inner wire mesh of the glass tube that divides the air travel unit was a 20 mesh aluminum wire mesh. The penetration performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 132 ° C. The thermal conductivity of aluminum was 190 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 65 L / m ² / day and 99.9%, respectively.

(Example 8)
A hollow fiber membrane for canned water desalination, a fluid separation device was prepared in the same manner as in Example 4 except that the inner peripheral wire mesh of the glass tube that divides the aerial traveling unit was a 20 mesh aluminum wire mesh, Reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 133 ° C. The thermal conductivity of aluminum was 190 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 249 L / m ² / day and 99.0%, respectively.

Example 9
A hollow fiber membrane for seawater desalination and a fluid separation device were produced and reverse osmosis in the same manner as in Example 3 except that the inner peripheral wire mesh of the glass tube that divides the air travel part was a 20 mesh copper wire mesh. Performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 131 ° C. The thermal conductivity of copper was 340 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 65 L / m ² / day and 99.9%, respectively.

(Example 10)
A hollow fiber membrane for canned water desalination and a fluid separation device were produced in the same manner as in Example 4 except that the inner metal mesh of the glass tube that divides the aerial traveling unit was a 20-mesh copper metal mesh. The penetration performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 132 ° C. The thermal conductivity of copper was 340 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 249 L / m ² / day and 99.0%, respectively.

(Comparative Example 1)
In the same manner as in Reference Example 1, a hollow fiber membrane for seawater desalination and a fluid separation device were produced without a heat transfer cooling member, and reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 135 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 58 L / m ² / day and 99.9%, respectively.

(Comparative Example 2)
In the same manner as in Reference Example 2, a hollow fiber membrane for canned water desalting and a fluid separation device were produced without a heat transfer cooling member, and reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The water permeation performance and salt removal rate of the hollow fiber membrane were 220 L / m ² / day and 99.0%, respectively.

(Comparative Example 3)
A hollow fiber membrane for seawater desalination and a fluid separation device were prepared in the same manner as in Example 1 except that the distance between the heat transfer cooling member on the outer periphery of the glass tube defining the aerial traveling unit and the membrane forming stock solution was 60 mm. Prepared and measured reverse osmosis performance. The temperature difference between the nozzle temperature and the coagulation liquid was about 133 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 59 L / m ² / day and 99.9%, respectively.

(Comparative Example 4)
A hollow fiber membrane for canned water desalting and a fluid separation device in the same manner as in Example 2 except that the distance between the heat transfer cooling member on the outer periphery of the glass tube that divides the aerial traveling section and the membrane forming stock solution is 60 mm The reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 133 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 230 L / m ² / day and 99.0%, respectively.

(Comparative Example 5)
A hollow fiber membrane for seawater desalination and a fluid separation device were prepared in the same manner as in Example 1 except that the distance between the heat transfer cooling member on the outer periphery of the glass tube defining the aerial traveling unit and the membrane forming stock solution was 100 mm. Prepared and measured reverse osmosis performance. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 58 L / m ² / day and 99.9%, respectively.

(Comparative Example 6)
A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 1 except that the distance of the aerial running portion of the membrane-forming stock solution was 60 mm, and reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 53 L / m ² / day and 99.9%, respectively.

(Comparative Example 7)
A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 1 except that the distance of the aerial traveling part of the membrane-forming stock solution was 100 mm, and the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 45 L / m ² / day and 99.9%, respectively.

(Comparative Example 8)
A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 1 except that the nozzle temperature was 145 ° C. and the temperature of the coagulation liquid was 55 ° C., and the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulating liquid was about 90 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 35 L / m ² / day and 98.0%, respectively.

(Comparative Example 9)
A hollow fiber membrane for seawater desalination and a fluid separation device were prepared in the same manner as in Example except that the heat transfer cooling member was a cylindrical body made of SUS304 stainless steel plate having no air permeability, and reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The water permeability and salt removal rate of the hollow fiber membrane were 50 L / m ² / day and 99.9%, respectively.

(Comparative Example 10)
A hollow fiber membrane for seawater desalination and a fluid separation device were produced in the same manner as in Example 1 except that the heat transfer cooling member was a cylindrical body made of a polyethylene mesh, and the reverse osmosis performance was measured. The temperature difference between the nozzle temperature and the coagulation liquid was about 134 ° C. The thermal conductivity of polyethylene was 0.26 kcal / (m · h · ° C.). The water permeability and salt removal rate of the hollow fiber membrane were 58 L / m ² / day and 99.9%, respectively.

  As is apparent from Examples 1 to 10 and Reference Examples, a hollow fiber type reverse osmosis membrane having high water permeability and salt removal rate can be provided by the dry and wet spinning membrane forming method of the present invention.

  The hollow fiber type reverse osmosis membrane obtained by the dry-wet spinning membrane forming method of the present invention and the hollow fiber type reverse osmosis membrane module obtained thereby have high water permeability, and therefore, seawater desalination, water purification, medical treatment, pharmaceutical water It can be widely used for endotoxin-free water production and the like, and contributes greatly to the industry.

It is a schematic diagram which shows the state of the cross section of an example of the embodiment of the air travel part vicinity in this invention.

Explanation of symbols

1: Nozzle 2: Discharged film forming stock solution 3: Heat transfer cooling member (when installed inside a non-breathable partition member)
3 ': Heat transfer cooling member (when installed outside the non-breathable partition member)
4: Coagulation bath 4 ′: Coagulation bath surface 5: Hollow fiber membrane 6: Aerial running part 7: Non-breathable partition member L1: Distance between the membrane forming raw solution and the heat transfer cooling member (inside of non-breathable partition member If installed)
L2: Distance between the film forming stock solution and the heat transfer cooling member (when installed outside the non-breathable partition member)
L3: Air travel distance L4: Solidification bath immersion depth of heat transfer cooling member

Claims (8)

  A dry-wet spinning film-forming method that obtains a hollow fiber type reverse osmosis membrane by discharging a film-forming stock solution containing at least a polymer raw material, a solvent, and a non-solvent from a nozzle, and running in an aerial running section and then immersing in a coagulation liquid. A method for producing a reverse osmosis membrane, wherein the aerial traveling part is surrounded by a heat transfer cooling member having air permeability, and a part of the heat transfer cooling member is immersed in a coagulating liquid.   The method for producing a reverse osmosis membrane according to claim 1, wherein the aerial traveling part is partitioned by a non-breathable partition member, and the partitioned aerial traveling part communicates with the outside.   The method of manufacturing a reverse osmosis membrane according to claim 1 or 2, wherein the heat transfer cooling member has a thermal conductivity of 10 kcal / (m · h · ° C) or more.   The reverse osmosis membrane according to any one of claims 1 to 3, wherein the heat transfer cooling member is made of a material mainly composed of at least one selected from iron, copper, stainless steel, aluminum, silver, and titanium. Manufacturing method.   The method for producing a reverse osmosis membrane according to any one of claims 1 to 4, wherein the distance between the heat transfer cooling member and the membrane forming stock solution discharged from the nozzle is 5 mm or more and 50 mm or less.   The method for producing a reverse osmosis membrane according to any one of claims 1 to 5, wherein the length of the aerial traveling part is 5 mm or more and 50 mm or less.   The method for producing a reverse osmosis membrane according to any one of claims 1 to 6, wherein the temperature of the nozzle that discharges the membrane-forming stock solution is made 100 ° C or more higher than the coagulation solution temperature. The method for producing a reverse osmosis membrane according to any one of claims 1 to 7, wherein the polymer raw material is a cellulose acetate polymer.