JP2018108589A - Composite semipermeable membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite semipermeable membrane where the efficiency of the treatment of drainage involving a lot of suspended matter and being easy to clog is high and the efficiency of the treatment is hard to deteriorate even when operating at pressure rising accompanied by continuous high pressure use.SOLUTION: In a composite semipermeable membrane having a polymer porous layer on one surface of a nonwoven fabric layer and a polyamide-based separation function layer on the polymer porous layer, a ratio of the thickness of the polymer porous layer to the thickness of the nonwoven fabric layer is 0.22-0.45.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a composite semipermeable membrane for separating and concentrating a specific substance or the like from various liquids.

  In recent years, attempts have been made to desalinate seawater to desalinate in large coastal cities in dry and semi-arid regions where it is difficult to stably secure water resources. Furthermore, in areas where water resources are scarce, such as China and Singapore, attempts have been made to purify and reuse industrial and domestic wastewater. Furthermore, recently, an attempt has been made to recycle such water by removing oil and salt from wastewater with high turbidity from oilfield plants and the like. It has been found that a membrane method using a composite semipermeable membrane is effective for such water treatment in terms of cost and efficiency. In such a water treatment method, water to be treated is continuously supplied to a membrane module having a spiral type composite semipermeable membrane element at a high pressure of about 1 to 7 MPa. (See Patent Document 1 or 2.)

JP 09-299947 A JP 2006-130497 A

  In particular, with the improvement in energy efficiency accompanying the recent improvement in membrane treatment efficiency, composite semipermeable membranes for efficiently treating wastewater that is turbid and easily clogged are being studied. In the case where such treated water with a large amount of turbid components is subjected to membrane treatment, in many cases, it is necessary to temporarily stop the treatment and perform washing such as reverse flow of water with a cleaning agent such as chlorine. However, in these methods, there is a problem that the processing efficiency is reduced due to the stop and the film is deteriorated by the cleaning agent. In order to reduce the number of washings as much as possible in actual operation for such a problem, there is a case where a method of increasing the pressurizing pressure in accordance with a necessary permeation flow rate is sometimes used.

  An object of the present invention is to provide a composite semipermeable membrane that has a high processing efficiency (particularly flux) even when such a method is used, and the processing efficiency does not easily deteriorate even during a pressure increase operation under a high pressure.

  As a result of intensive studies on permeation flux (Flux) reduction during continuous use of high pressure, the present inventors have found a factor in the change in the membrane state at the initial stage of high pressure use, and a composite semipermeable membrane is configured according to the present invention. It has been found that the problems caused by the use of high pressure can be solved. The present invention will be described below.

  The present invention provides a composite semipermeable membrane having a polymer porous layer on one side of a nonwoven fabric layer and a polyamide-based separation functional layer on the polymer porous layer, the thickness of the polymer porous layer and the thickness of the nonwoven fabric layer. It is related with the composite semipermeable membrane whose ratio which consists of 0.22-0.45.

The composite semipermeable membrane has a permeation flux (F0) of 1.0 m ³ / m ² / d or more when pure water is permeated at a pressure of 1.5 MPa, and further has a pressure of 5.5 MPa. The permeation flux (F1) when pure water is permeated at a pressure of 1.5 MPa is 1.0 m ³ / m ² / d or more after pressure water is passed for 4 hours using The composite semipermeable membrane has a permeation flux ratio before and after water (F1 / F0), that is, a permeation flux retention (F1 / F0 × 100) of 80% or more.

  The thickness of the polymer porous layer in the composite semipermeable membrane is preferably 10 μm or more and 35 μm or less. Further, it is more preferably 32 μm or less, particularly preferably 29 μm or less, and most preferably 23 μm or less. The nonwoven fabric layer preferably has a thickness of 120 μm or less.

  The polyamide-based separation functional layer is preferably composed of a polyfunctional amine component using piperazine or m-phenylenediamine. The function of the present invention can be further enhanced by coating the surface of the polyamide-based separation functional layer with polyvinyl alcohol having a saponification degree of 99% or more.

  The composite semipermeable membrane of the present invention is not particularly limited to this, but is wound around a perforated hollow tube having a plurality of holes on the wall surface by laminating a folded envelope membrane and a channel material. It is preferably used as a spiral composite semipermeable membrane element that is rotated and integrated using an end member and an exterior material. When the composite semipermeable membrane of the present invention is used in such a composite semipermeable membrane element, 30 to 40 sets of the envelope-like membrane can be used, which further contributes to increasing the efficiency of the element.

  In the spiral composite semipermeable membrane element, the thickness of the flow path material provided on the inner surface of the envelope membrane is 0.9 mm or more and 1.3 mm or less, so that the composite semipermeable membrane of the present invention is further used. It has been found that the permeation flux retention of a spiral type composite semipermeable membrane element using a membrane can be increased.

It is a partially cutaway perspective view showing an example of the structure of a spiral type composite semipermeable membrane element that can be used in the present invention.

  In the present invention, a composite semipermeable membrane having a polymer porous layer on one side of a nonwoven fabric layer and further having a polyamide-based separation functional layer thereon, the thickness of the polymer porous layer and the thickness of the nonwoven fabric layer Even if the composite semipermeable membrane is continuously used with a high pressure treatment of about 1 to 7 MPa by setting the ratio (thickness of the polymer porous layer / thickness of the nonwoven fabric layer) to 0.22 to 0.45, The present inventors have found a composite semipermeable membrane in which the permeation flux (Flux) is significantly less than that in the past.

  The composite semipermeable membrane is not particularly limited as long as it has a polyamide-based separation functional layer on the polymer porous layer of the composite semipermeable membrane support composed of a nonwoven fabric and a polymer porous layer. In this case, the thickness is about 40 to 200 μm. If this composite semipermeable membrane is too thin, high-pressure processing becomes difficult, for example, the film surface is missing due to pressure during processing. Therefore, 55 μm or more is preferable, and 75 μm or more is more preferable. On the other hand, as the composite semipermeable membrane is thinner, more membranes can be loaded in a certain element space, so that the performance can be improved. Therefore, it is preferable to set it as 120 micrometers or less, and it is more preferable to set it as 90 micrometers or less. Such composite semipermeable membranes are called RO (reverse osmosis) membranes, NF (nanofiltration) membranes, and FO (forward osmosis) membranes depending on their filtration performance and treatment method, and they are used for ultrapure water production and seawater desalination. It can be used for desalination of brine, reuse of waste water, etc.

  The polyamide-based separation functional layer is generally a homogeneous membrane having no visible pores and has a desired ion separation ability. The separation functional layer is not particularly limited as long as it is a polyamide-based thin film that is difficult to peel off from the polymer porous layer. For example, a polyfunctional amine component and a polyfunctional acid halide component are formed on the porous support membrane. A polyamide-based separation functional layer obtained by interfacial polymerization is well known. Such a polyamide-based separation functional layer is known to have a pleated microstructure, and the thickness of this layer is not particularly limited, but is about 0.05 to 2 μm, preferably 0.1 to 1 μm. It is known that if this layer is too thin, film surface defects are likely to occur, and if it is too thick, the transmission performance deteriorates.

  The method for forming the polyamide-based separation functional layer on the surface of the polymer porous layer is not particularly limited, and any known method can be used. Examples of the method include an interfacial polymerization method, a phase separation method, and a thin film coating method. In the present invention, the interfacial polymerization method is particularly preferably used. In the interfacial polymerization method, for example, the polymer porous layer is coated with a polyfunctional amine component-containing amine aqueous solution, and then an organic solution containing a polyfunctional acid halide component is brought into contact with the amine aqueous solution-coated surface to cause interfacial polymerization. This is a method for forming a skin layer. In this method, it is preferable to proceed by removing the surplus as appropriate after the application of the aqueous amine solution and the organic solution. In this case, as a removal method, a method of inclining a target film, a method of blowing off a gas, a rubber, For example, a method of scraping off a blade by contacting the blade is preferably used.

  In the above step, the time until the aqueous amine solution and the organic solution come into contact depends on the composition of the aqueous amine solution, the viscosity, and the pore diameter of the surface of the porous support membrane, but is about 1 to 120 seconds, preferably Is about 2 to 40 seconds. If the interval is too long, the aqueous amine solution may permeate and diffuse deep inside the porous support membrane, and a large amount of unreacted polyfunctional amine component may remain in the porous support membrane, resulting in problems. . When the application interval of the solution is too short, an excessive amine aqueous solution remains, so that the film performance tends to be lowered.

  After the contact between the aqueous amine solution and the organic solution, the skin layer is preferably formed by heating and drying at a temperature of 70 ° C. or higher. Thereby, the mechanical strength and heat resistance of the film can be increased. The heating temperature is more preferably 70 to 200 ° C, particularly preferably 80 to 130 ° C. The heating time is preferably about 30 seconds to 10 minutes, more preferably about 40 seconds to 7 minutes.

  The polyfunctional amine component contained in the amine aqueous solution is a polyfunctional amine having two or more reactive amino groups, and examples thereof include aromatic, aliphatic, and alicyclic polyfunctional amines. Examples of the aromatic polyfunctional amine include m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, 1,3,5-triaminobenzene, 1,2,4-triaminobenzene, 3,5- Examples include diaminobenzoic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, N, N′-dimethyl-m-phenylenediamine, 2,4-diaminoanisole, amidol, xylylenediamine and the like. Examples of the aliphatic polyfunctional amine include ethylenediamine, propylenediamine, tris (2-aminoethyl) amine, and n-phenyl-ethylenediamine. Examples of the alicyclic polyfunctional amine include 1,3-diaminocyclohexane, 1,2-diaminocyclohexane, 1,4-diaminocyclohexane, piperazine, 2,5-dimethylpiperazine, 4-aminomethylpiperazine, and the like. It is done. These polyfunctional amines may be used alone or in combination of two or more. In particular, in the present invention, when a high rejection is required in reverse osmosis membrane performance, it is preferable to use m-phenylenediamine as a main component from which a highly functional separation function layer can be obtained, and high flux retention in NF membrane performance. When determining the rate, it is preferable to use piperazine as the main component.

  The polyfunctional acid halide component contained in the organic solution is a polyfunctional acid halide having two or more reactive carbonyl groups, and examples thereof include aromatic, aliphatic, and alicyclic polyfunctional acid halides. Examples of the aromatic polyfunctional acid halide include trimesic acid trichloride, terephthalic acid dichloride, isophthalic acid dichloride, biphenyldicarboxylic acid dichloride, naphthalene dicarboxylic acid dichloride, benzenetrisulfonic acid trichloride, benzenedisulfonic acid dichloride, and chlorosulfonylbenzene. And dicarboxylic acid dichloride. Examples of the aliphatic polyfunctional acid halide include propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, propanetricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, glutaryl halide, azide. Poil halide etc. are mentioned. Examples of the alicyclic polyfunctional acid halide include cyclopropane tricarboxylic acid trichloride, cyclobutane tetracarboxylic acid tetrachloride, cyclopentane tricarboxylic acid trichloride, cyclopentane tetracarboxylic acid tetrachloride, cyclohexane tricarboxylic acid trichloride, and tetrahydro Examples include furantetracarboxylic acid tetrachloride, cyclopentanedicarboxylic acid dichloride, cyclobutanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride. These polyfunctional acid halides may be used alone or in combination of two or more. In order to obtain a skin layer having a high salt inhibition performance, it is preferable to use an aromatic polyfunctional acid halide. Moreover, it is preferable to form a crosslinked structure using a trifunctional or higher polyfunctional acid halide as at least a part of the polyfunctional acid halide component.

  In the interfacial polymerization method, the concentration of the polyfunctional amine component in the aqueous amine solution is not particularly limited, but is preferably 0.1 to 7% by weight, and more preferably 1 to 5% by weight. If the concentration of the polyfunctional amine component is too low, defects are likely to occur in the skin layer, and the salt blocking performance tends to be reduced. On the other hand, when the concentration of the polyfunctional amine component is too high, it becomes too thick and the permeation flux tends to decrease.

  The concentration of the polyfunctional acid halide component in the organic solution is not particularly limited, but is preferably 0.01 to 5% by weight, and more preferably 0.05 to 3% by weight. If the concentration of the polyfunctional acid halide component is too low, the unreacted polyfunctional amine component is increased, and defects are likely to occur in the skin layer. On the other hand, if the concentration of the polyfunctional acid halide component is too high, the amount of unreacted polyfunctional acid halide component increases, so that the skin layer becomes too thick and the permeation flux tends to decrease.

  The organic solvent containing the polyfunctional acid halide is not particularly limited as long as it has low solubility in water and does not deteriorate the porous support membrane, and can dissolve the polyfunctional acid halide component. For example, cyclohexane, Examples thereof include saturated hydrocarbons such as heptane, octane and nonane, and halogen-substituted hydrocarbons such as 1,1,2-trichlorotrifluoroethane. Preferred is a saturated hydrocarbon having a boiling point of 300 ° C. or lower, more preferably a boiling point of 200 ° C. or lower.

You may add the additive for the purpose of the improvement of various performance and a handleability to the said amine aqueous solution and organic solution. Examples of the additive include polymers such as polyvinyl alcohol, polyvinyl pyrrolidone and polyacrylic acid, polyhydric alcohols such as sorbitol and glycerin, and surfactants such as sodium dodecylbenzenesulfonate, sodium dodecylsulfate, and sodium laurylsulfate. A basic compound such as sodium hydroxide, trisodium phosphate, and triethylamine that removes hydrogen halide produced by polymerization, an acylation catalyst, and a solubility parameter described in JP-A-8-224452 is 8 to 14 (cal / Cm ³ ) _1/2 compound and the like.

  A coating layer made of various polymer components may be provided on the exposed surface of the polyamide-based separation functional layer. The polymer component is not particularly limited as long as it does not dissolve the separation functional layer and the porous support membrane and does not elute during the water treatment operation. For example, polyvinyl alcohol, polyvinyl pyrrolidone, hydroxypropyl cellulose, polyethylene Examples thereof include glycols and saponified polyethylene-vinyl acetate copolymers. Among these, it is preferable to use polyvinyl alcohol, in particular, by using polyvinyl alcohol having a saponification degree of 99% or more, or by crosslinking polyvinyl alcohol having a saponification degree of 90% or more with the polyamide-based resin of the skin layer, It is preferable to use a structure that does not easily dissolve during water treatment. By providing such a coating layer, the charge state of the film surface is adjusted and hydrophilicity is imparted, so that the adhesion of contaminants can be suppressed, and further, the flux retention effect is achieved by a synergistic effect with the present invention. Can be further enhanced.

The nonwoven fabric layer is not particularly limited as long as it provides an appropriate mechanical strength while maintaining the separation performance and permeation performance of the composite semipermeable membrane, and a commercially available nonwoven fabric can be used. As this material, for example, a material made of polyolefin, polyester, cellulose or the like is used, and a material in which a plurality of materials are mixed can also be used. In particular, it is preferable to use polyester in terms of moldability. In addition, a long fiber nonwoven fabric or a short fiber nonwoven fabric can be used as appropriate, but a long fiber nonwoven fabric can be preferably used from the viewpoint of fine fuzz that causes pinhole defects and uniformity of the film surface. In addition, the air permeability of the nonwoven fabric layer at this time is not limited to this, but can be about 0.5 to 10 cm ³ / cm ² · s, and 1 to ⁵ cm ³ / Those having a size of about cm ² · s are preferably used.

  The thickness of the nonwoven fabric layer is preferably 120 μm or less, more preferably 100 μm or less, and particularly preferably 78 μm or less. If this thickness is too thick, the permeation resistance becomes too high and the flux tends to decrease. On the other hand, if it is too thin, the mechanical strength as a composite semipermeable membrane support will decrease, making it difficult to obtain a stable composite semipermeable membrane. Therefore, it is preferably 30 μm or more, and more preferably 45 μm or more.

  The polymer porous layer is not particularly limited as long as it can form the polyamide-based separation functional layer, but is usually a microporous layer having a pore diameter of about 0.01 to 0.4 μm. Examples of the material for forming the microporous layer may include various materials such as polysulfone, polyarylethersulfone exemplified by polyethersulfone, polyimide, and polyvinylidene fluoride. In particular, it is preferable to form a polymer porous layer using polysulfone or polyarylethersulfone because it is chemically, mechanically and thermally stable.

  In the present invention, the thickness of the polymer porous layer is preferably 35 μm or less, and more preferably 32 μm or less. It has been found that if it is too thick, the flux retention after pressurization tends to decrease. Furthermore, 29 μm or less is particularly preferable, and 23 μm or less is most preferable. By forming the thin film to this extent, the stability of the flux retention rate can be further increased. Moreover, since it will become easy to produce a defect when it is too thin, 10 micrometers or more are preferable and 15 micrometers or more are more preferable.

  An example of the production method when the polymer of the polymer porous layer is polysulfone will be described. The polymer porous layer can be produced by a method generally called a wet method or a dry wet method. First, a solution preparation step in which polysulfone, a solvent and various additives are dissolved, a coating step in which the nonwoven fabric is coated with the solution, a drying step in which the solvent in the solution is evaporated to cause microphase separation, a water bath, etc. The polymer porous layer on the nonwoven fabric can be formed through an immobilization step of immobilization by dipping in a coagulation bath. The thickness of the polymer porous layer can be set by adjusting the solution concentration and the coating amount after calculating the ratio of impregnation into the nonwoven fabric layer.

  In the present invention, the ratio of the thickness of the polymer porous layer and the thickness of the nonwoven fabric layer of the composite semipermeable membrane support thus obtained (the thickness of the polymer porous layer / the thickness of the nonwoven fabric layer) In a range of 0.22 to 0.45, pure water is used at a pressure of 1.5 MPa using a composite semipermeable membrane before and after being pressurized and passed for 4 hours using pure water at a pressure of 5.5 MPa. It has been found that the permeation flux retention when water is permeated is 80% or more. This is presumed that the flux retention varies greatly depending on the thickness balance between the porous polymer layer and the nonwoven fabric layer, and the flow around the separation functional layer is influenced by the correlation of the compression degree of each layer. It is done. This range is more preferably 0.23 to 0.38.

In the present invention, the non-woven fabric layer and the polymer porous layer have the above thickness ratio, and the polyamide-based separation functional layer is formed so that the initial permeate flow when pure water is permeated at a pressure of 1.5 MPa. A composite semipermeable membrane having a bundle of 1.0 m ³ / m ² / d or more, preferably 1.3 m ³ / m ² / d or more, more preferably 1.5 m ³ / m ² / d or more can be obtained. The permeation flux preferably retains the permeation flux even in the composite semipermeable membrane after pressurized water flow. In particular, in the present invention, the initial permeation flux (F0) when pure water is permeated at a pressure of 1.5 MPa is 1.0 m ³ / m ² / d or more, and the pure water is supplied at a pressure of 5.5 MPa. After passing under pressure for 4 hours, the permeation flux (F1) measured by allowing pure water to permeate at a pressure of 1.5 MPa was 1.0 m ³ / m ² / d or more, and the ratio (F1) A composite semipermeable membrane having a / F0) of 0.8 or more, more preferably 0.85 or more can be obtained.

  The composite semipermeable membrane is usually processed into the form of a membrane element and is used by being loaded into a pressure vessel (vessel). The form of the membrane element is not particularly limited, and examples include a flat membrane type such as a frame and plate type, a spiral type, and a pleat type. Generally, a spiral type composite semipermeable membrane element is used due to the relationship between pressure and flow efficiency. Can be preferably used. The spiral type composite semipermeable membrane element has a plurality of wall surface holes in a state in which a channel material on the inner surface side (concave surface) and a channel material on the outer surface side of the folded composite semipermeable membrane are laminated. It is wound around a central tube (a perforated hollow tube) and further fixed with an end member or an exterior material.

  In such a spiral composite membrane element, the envelope-shaped membrane is usually wound about 20 to 30 sets. However, when the present invention is used, 30 to 40 sets of envelope-shaped membrane can be wound. . As a result, a larger amount of processing is possible, and it has been found that the processing efficiency is remarkably increased.

  The channel material generally has a role of ensuring a gap for uniformly supplying fluid to the membrane surface. As such a channel material, for example, a net, a knitted fabric, a concavo-convex processed sheet or the like can be used, and a material having a maximum thickness of about 0.1 to 3 mm can be appropriately used as necessary. In such a channel material, it is preferable that the pressure loss is low, and further, a material that causes an appropriate turbulent flow effect is preferable. In addition, the channel material is installed on both sides of the separation membrane, but it is common to use different channel materials as the supply side channel material on the supply liquid side and the permeate side channel material on the permeate side. . The supply-side channel material uses a coarse and thick net-like channel material, while the permeate-side channel material uses a fine woven or knitted channel material.

  When the RO membrane or NF membrane is used in applications such as seawater desalination and wastewater treatment, the supply-side channel material is provided on the inner surface side of the composite semipermeable membrane folded in half. As the structure of the supply-side channel material, a network structure in which linear objects are generally arranged in a lattice can be preferably used. Although it does not specifically limit as a material to comprise, Polyethylene, a polypropylene, etc. are used. These resins may contain bactericides and antibacterial agents. The thickness of the supply side channel material is generally 0.2 to 2.0 mm, preferably 0.5 to 1.0 mm. If the thickness is too thick, the amount of permeation decreases with the amount of film that can be accommodated in the element. Conversely, if the thickness is too thin, contaminants tend to adhere, and the permeation performance is likely to deteriorate. In particular, in the present invention, when combined with a 0.9 to 1.3 mm supply-side flow path material, contaminants are less likely to accumulate and biofouling is less likely to occur. Can be suppressed.

  When the RO membrane or NF membrane is used in applications such as seawater desalination and wastewater treatment, the permeate-side channel material is provided on the outer surface side of the bi-folded composite semipermeable membrane. This permeation side channel material is required to support the pressure applied to the membrane from the back side of the membrane and secure a permeate channel. In general, a net or tricot knitted fabric made of polyethylene or polypropylene is used. In particular, a tricot knitted fabric made of polyethylene terephthalate is particularly preferably used.

  The central tube is not particularly limited as long as it is a perforated hollow tube having a plurality of small holes on the wall surface of the pipe (hollow tube). In general, when used in seawater desalination, wastewater treatment, etc., the permeated water that has passed through the composite semipermeable membrane enters the hollow tube from the hole in the wall surface to form a permeated water channel. The length of the central tube is generally longer than the length of the element in the axial direction, but a central tube having a connection structure such as a plurality of divisions may be used. Although it does not specifically limit as a material which comprises a center pipe | tube, A thermosetting resin or a thermoplastic resin is used.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples.

Example 1
A polymer porous layer having a thickness of 21.1 μm is formed by applying and coagulating a mixed solution of polysulfone and dimethylformamide on the surface of a commercially available polyester nonwoven fabric for water treatment membrane support having a thickness of 61.0 μm. A composite semipermeable membrane support was prepared. After contacting the surface of the porous polymer layer of the composite semipermeable membrane support with a solution A in which 3.6% by weight of piperazine hexahydrate and 0.15% by weight of sodium lauryl sulfate are mixed, an excess solution A is added. Removed to form a coating layer of solution A. Next, a solution B containing 0.4% by weight of trimesic acid chloride in a hexane solvent was brought into contact with the surface of the solution A coating layer. Then, the separation functional layer was formed by drying in an environment of 120 ° C. to obtain a composite semipermeable membrane.

(Example 2)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that a composite semipermeable membrane support having a 27.2 µm thick polymer porous layer formed on the surface of a polyester non-woven fabric having a thickness of 114.0 µm was used. did.

(Example 3)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that a composite semipermeable membrane support having a 31.2 µm thick polymer porous layer formed on the surface of a 109.8 µm thick polyester nonwoven fabric was used. did.

Example 4
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that a composite semipermeable membrane support having a 31.8 µm thick polymer porous layer formed on the surface of a 107.6 µm thick polyester nonwoven fabric was used. did.

(Comparative Example 1)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that a composite semipermeable membrane support having a porous polymer layer having a thickness of 19.1 µm formed on the surface of a polyester nonwoven fabric having a thickness of 96.0 µm was used. did.

(Comparative Example 2)
A composite semipermeable membrane was prepared in the same manner as in Example 1 except that a composite semipermeable membrane support having a 28.3 µm thick polymer porous layer formed on the surface of a 61.8 µm thick polyester nonwoven fabric was used. did.

(Comparative Example 3)
A composite semipermeable membrane was produced in the same manner as in Example 1 except that a composite semipermeable membrane support having a 30.9 µm thick polymer porous layer formed on the surface of a polyester nonwoven fabric having a thickness of 65.9 µm was used. did.

  The following evaluation was performed about the sheet | seat obtained by the Example and the comparative example. The results are shown in Table 1.

(Measurement of permeation flux (Flux))
The obtained composite semipermeable membrane was set in a test unit (manufactured by Nitto Denko Corporation: C40-B), and the initial permeation flux at an operating pressure of 1.5 MPa was measured using pure water at a temperature of 25 ° C. . Next, after pressurized water was passed for 4 hours at an operating pressure of 5.5 MPa, the permeation flux was measured at an operating pressure of 1.5 MPa using pure water at a temperature of 25 ° C. as in the initial stage, and the permeation before and after pressurization was measured. The flux ratio was calculated.

(Thickness measurement)
Thickness measurement was performed using a commercially available thickness measuring instrument (manufactured by Ozaki Mfg. Co., Ltd .: Dial Thickness Gauge G-7C). For the measurement of the thickness of the nonwoven fabric layer and the polymer porous layer, the thickness of the nonwoven fabric layer is measured in advance, and the thickness of the entire composite semipermeable membrane support is formed with the polymer porous layer formed on the nonwoven fabric layer. Was measured. Thereafter, the difference between the thickness of the composite semipermeable membrane support and the thickness of the non-woven fabric was determined to obtain the thickness of the polymer porous layer. In each thickness measurement, an average value of arbitrary ten points measured values on the same film surface was used.

  As shown in Table 1 above, Examples 1 to 4 according to the configuration of the present invention have a permeation flux (Flux) retention of 80% or more, and the effect is good. On the other hand, Comparative Examples 1 to 3 deviating from the configuration of the present invention have a significantly reduced permeation flux (Flux) retention rate.

  As described above, since the present invention has a high flux performance, the energy efficiency can be remarkably improved, and a high flux can be maintained even before and after high-pressure processing. This can effectively contribute to wastewater treatment in oil fields and factories where the turbidity of the supply liquid is particularly high.

1 Spiral type composite semipermeable membrane element
2 Composite semipermeable membrane 3 Permeate side channel material
4 Envelope-shaped membrane 5 Center tube 6 Supply-side channel material 7 Supply water 8 Permeated water 9 Concentrated water

Claims (6)

  In a composite semipermeable membrane having a polymer porous layer on one side of the nonwoven fabric layer and having a polyamide-based separation functional layer on the polymer porous layer, the ratio consisting of the thickness of the polymer porous layer and the thickness of the nonwoven fabric layer is A composite semipermeable membrane that is 0.22 to 0.45. The initial permeation flux (F0) when pure water permeates at a pressure of 1.5 MPa is 1.0 m ³ / m ² / d or more, and the pure water is further pressurized for 4 hours at a pressure of 5.5 MPa. After the water is passed, the permeation flux (F1) when pure water is permeated at a pressure of 1.5 MPa is 1.0 m ³ / m ² / d or more, and the ratio (F1 / F0) is 0. The composite semipermeable membrane according to claim 1, which is 8 or more.   The composite semipermeable membrane according to claim 1 or 2, wherein the polymer porous layer has a thickness of 10 µm to 35 µm.   The composite semipermeable membrane according to any one of claims 1 to 3, wherein the nonwoven fabric layer has a thickness of 120 µm or less, and the polymer porous layer has a thickness of 10 µm or more and 29 µm or less.   The composite semipermeable membrane according to any one of claims 1 to 4, wherein the polyamide-based separation functional layer is a separation functional layer composed of a polyfunctional amine component using piperazine or m-phenylenediamine.   The composite semipermeable membrane according to any one of claims 1 to 5, wherein the surface of the polyamide-based separation functional layer is coated with polyvinyl alcohol having a saponification degree of 99% or more.

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