JP2012045509A - Method of manufacturing separation membrane support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a separation membrane support, made of a nonwoven fabric which has a superior film-forming property provided when supporting the separation membrane, has a superior processing property provided when manufacturing fluid separation element and, additionally, has an excellent mechanical strength, and to provide a separation membrane and a fluid separation element using the separation membrane support.SOLUTION: The method of manufacturing separation membrane support includes a process of subjecting the nonwoven fabric to thermocompression by the use of at least two flat rollers, wherein the flat rollers consist of a combination of metallic rollers and elastic rollers, the elastic roller has a hardness (Shore D) of 70 to 99 and the nonwoven fabrics stacked in 2 to 5 layers are preferably subjected to thermocompression to be integrated.

Description

  The present invention relates to a method for producing a separation membrane support comprising a nonwoven fabric for supporting separation membranes such as microfiltration membranes, ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes. The present invention also relates to a separation membrane and a fluid separation element using a separation membrane support produced by the production method.

  Membrane technology is applied to water treatment in recent years in many cases. For example, microfiltration membranes and ultrafiltration membranes are used for water treatment at water purification plants, and reverse osmosis membranes are used for desalination of seawater. Also, reverse osmosis membranes and nanofiltration membranes are used for the treatment of semiconductor manufacturing water, boiler water, medical water, laboratory pure water, and the like. Furthermore, a membrane separation activated sludge method using a microfiltration membrane or an ultrafiltration membrane is also applied to the treatment of sewage wastewater.

  These separation membranes are roughly classified into flat membranes and hollow fiber membranes according to their shapes. Among these separation membranes, flat membranes formed mainly from synthetic polymers are generally used integrally with a support such as a nonwoven fabric or woven fabric because a membrane having a separation function is inferior in mechanical strength. There are many cases.

  In general, a membrane having a separation function and a support are integrated by a method of casting and fixing a polymer solution as a raw material for the membrane having a separation function on a support such as a nonwoven fabric or a woven fabric. The Moreover, in a semipermeable membrane such as a reverse osmosis membrane, a solution of a polymer is cast on a support such as a nonwoven fabric or a woven fabric to form a support layer, and then a semipermeable membrane is formed on the support layer. It is integrated by a method of forming.

  Therefore, for non-woven fabrics and woven fabrics that serve as a support, when a polymer solution is cast, it penetrates due to excessive permeation, the film substance peels off, and the support is fluffed, etc. Therefore, an excellent film forming property that does not cause defects such as non-uniform film formation and pinholes is required.

  Examples of the form of the fluid separation element for facilitating the handling of the separation membrane include flat membrane plate frame type, pleat type, and spiral type. For example, in the case of a plate frame type, a process of attaching a separation membrane cut to a predetermined size to the frame is necessary, and in the case of a spiral type, the outer peripheral portions of the separation membranes cut to a predetermined size are bonded together. A process of processing into an envelope and winding it around the water collecting pipe is necessary. Therefore, the separation membrane support is required to have excellent processability so that the membrane is not bent or rounded in these steps.

  Furthermore, in the case of a semipermeable membrane such as a reverse osmosis membrane that is often used for a long time under high pressure, the support is required to have excellent mechanical strength and durability.

Conventionally, as such a separation membrane support, a double structure of a surface layer having a large opening and a large surface roughness using a thick fiber and a back layer having a small structure and a small opening using a thin fiber A separation membrane support made of a nonwoven fabric of a multilayer structure based on the above has been proposed (see Patent Document 1). Further, in the semipermeable membrane support made of a nonwoven fabric for casting a polymer solution for forming a semipermeable membrane to form a membrane, the nonwoven fabric has a low density layer having an air permeability of 5 to 50 cc / cm ² / sec. A non-woven fabric having a two-layer structure in which a high-density layer having an air permeability of 0.1 cc / cm ² / sec or more and less than 5 cc / cm ² / sec is laminated and integrated, and the air permeability as a whole is 0.1 cc / cm semipermeable membrane support ^{2 /sec~4.5cc/cm 2} / sec has been proposed (see Patent Document 2.). Moreover, the average value of the longitudinal direction (MD) and transverse direction (CD) tear length at 5% elongation is 4.0 km or more, and the air permeability is 0.2 to 10.0 cc / cm ² · sec. A semipermeable membrane support made of a nonwoven fabric has been proposed (see Patent Document 3). Moreover, the separation membrane support body by which the long-fiber nonwoven fabric comprised from a thermoplastic continuous filament is laminated | stacked on 2-5 layers is proposed (refer patent document 4).

  However, in these documents, as a method for producing a separation membrane support, hot roll processing, thermal calendering, pressure heat treatment using a calender device composed of a combination of a heated metal roll and an elastic roll, etc. There is a description of the thermocompression bonding method using a roll and an unheated elastic roll, and there is also a description of the temperature and pressure of the hot roll, but there is no description or proposal regarding the hardness of the elastic roll used for hot roll processing etc. . Therefore, when the separation membrane support produced by such a production method is used, there is a problem that excellent mechanical strength when supporting the separation membrane cannot be obtained.

Japanese Patent Publication No. 4-21526 Japanese Patent Publication No. 5-35009 Japanese Patent No. 3153487 JP 2009-61373 A

  In addition to having excellent film forming properties when supporting separation membranes such as microfiltration membranes, ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes, and excellent processability when manufacturing fluid separation elements. Another object of the present invention is to provide a separation membrane support made of a nonwoven fabric having excellent mechanical strength, and a separation membrane and a fluid separation element using the separation membrane support.

The present invention employs the following means in order to solve such problems.
(1) A method for producing a separation membrane support in which a nonwoven fabric is thermocompression bonded by two or more flat rolls, wherein the flat roll is composed of a combination including a metal roll and an elastic roll, and the hardness of the elastic roll (Shore D ) Is 70 to 99. A method for producing a separation membrane support,
(2) The method for producing a separation membrane support according to (1) above, wherein the nonwoven fabrics laminated in 2 to 5 layers are integrated by thermocompression bonding.
(3) A separation membrane obtained by forming a membrane having a separation function on the surface of a separation membrane support produced by the method for producing a separation membrane support according to (1) or (2) above.
(4) A fluid separation element including the separation membrane according to (3) as a constituent element.

  According to the present invention, a separation membrane support made of nonwoven fabric, which has excellent membrane-forming properties when supporting separation membranes such as microfiltration membranes, ultrafiltration membranes, nanofiltration membranes and reverse osmosis membranes, and fluid separation elements In addition to having excellent processability during production, a separation membrane support made of a nonwoven fabric having excellent mechanical strength is obtained.

  In addition, according to the present invention, it is possible to obtain a separation membrane and a fluid separation element using the above-described separation membrane support.

  The separation membrane support of the present invention is a separation membrane support that forms a membrane having a separation function on the surface thereof.

  The method for producing a separation membrane support according to the present invention comprises thermocompression bonding with two or more flat rolls, the flat roll comprising a combination including a metal roll and an elastic roll, and the hardness (Shore D) of the elastic roll is 70 to 99. It is important to be. This flat roll is a roll having no irregularities on the surface of the roll, and by using a combination of a metal roll and an elastic roll, the fusion of fibers on the surface of the nonwoven fabric can be suppressed and the form can be maintained. Examples of the material of the elastic roll include so-called paper rolls such as paper, cotton, and aramid paper, and resin rolls such as urethane resin, epoxy resin, silicon resin, polyester resin, and hard rubber.

  The present inventors have found that the hardness of the elastic roll has a great influence on the mechanical strength and membrane adhesion strength of the separation membrane support that contributes to the durability of the separation membrane and fluid separation element. If the hardness (Shore D) of the elastic roll is 70 or more, it is possible to obtain a separation membrane support excellent in mechanical strength by firmly bonding the fibers constituting the nonwoven fabric and increasing the density of the nonwoven fabric. If the hardness (Shore D) of the elastic roll is 99 or less, in the film forming process of casting and fixing the polymer solution as a raw material for the separation membrane and the support layer, excessive nonwoven fabric surface fibers By suppressing the fusion, the polymer solution can easily penetrate into the nonwoven fabric, and a separation membrane support excellent in membrane adhesive strength can be obtained. The preferable range of the hardness (Shore D) of the elastic roll is 75 to 95, and the more preferable range is 80 to 91.

  In addition, two or more flat rolls are composed of two rolls × two pairs, two rolls × three pairs, in which two or more combinations of metal / elastic rolls are used continuously or discontinuously in the manufacturing process. Alternatively, a three-roll system such as elasticity / metal / elasticity, elasticity / metal / metal, metal / elasticity / metal, and the like can also be preferably used.

  In the case of the two-roll × two-set system, heat and pressure can be applied twice to the nonwoven fabric, so that the properties of the nonwoven fabric can be easily controlled, and the production speed can be increased. Since the reversal of the contact surfaces of the first and second elastic rolls is easy, it becomes easy to control the surface properties of the front and back surfaces of the nonwoven fabric.

  On the other hand, in the case of the three-roll system, for example, if a nonwoven fabric thermocompression bonded between elastic 1 / metal / elastic 2 elastic 1 / metal roll is folded back and further thermocompression bonded between metal / elastic 2 rolls, the 2 rolls × Heat and pressure can be applied twice to the nonwoven fabric in the same manner as the two-set method, and the facility cost can be reduced and the space can be saved as compared with the continuous two-roll × two-set method.

  In the production method using two or more of these elastic rolls, the hardness (Shore D) of the elastic roll that contacts the nonwoven fabric and the first stage and the elastic roll that contacts the second stage is changed in the range of 70 to 99. It doesn't matter.

  The surface temperature of the metal roll is preferably 20 to 90 ° C., more preferably 30 to 70 ° C. lower than the melting point of the polymer constituting at least the surface of the fibers constituting the nonwoven fabric. If the surface temperature of the metal roll is 20 ° C. or more lower than the melting point of the polymer constituting at least the surface of the fibers constituting the nonwoven fabric, excessive fusion of the nonwoven fabric surface fibers can be suppressed. The solution can easily penetrate and a separation membrane support excellent in membrane adhesive strength can be obtained. On the other hand, if the difference between the surface temperature of the metal roll and the melting point of the polymer constituting at least the surface of the fibers constituting the nonwoven fabric is 90 ° C. or less, the fibers constituting the nonwoven fabric are firmly bonded together, By increasing the density, it is possible to obtain a separation membrane support having excellent mechanical strength, and it is possible to obtain good film-forming properties with less permeation during casting of the polymer solution.

  Furthermore, it is also a preferable aspect to provide a temperature difference between the metal roll and the elastic roll so that the surface temperature of the elastic roll is 10 to 120 ° C. lower than the surface temperature of the metal roll.

  As the heating method of the metal roll, an induction heat generation method, a heat medium circulation method, or the like can be preferably used, but since a separation membrane support excellent in uniformity can be obtained, the temperature difference in the nonwoven fabric width direction becomes a central value. On the other hand, it is preferably within ± 3 ° C., more preferably within ± 2 ° C.

  The heating method for the elastic roll is a contact heating method that is heated by contact with a metal roll heated during pressurization, or a non-contact heating method that uses an infrared heater or the like that can control the surface temperature of the elastic roll more strictly. Etc. can be preferably used. The temperature difference in the nonwoven fabric width direction of the elastic roll is preferably within ± 10 ° C., more preferably within ± 5 ° C. with respect to the center value. In order to more strictly control the temperature difference in the width direction of the nonwoven fabric of the elastic roll, an infrared heater or the like may be divided and installed in the width direction, and the respective outputs may be adjusted.

  Moreover, it is preferable that the linear pressure of a flat roll is 196-4900 N / cm. The linear pressure of the flat roll is more preferably 490 to 4900 N / cm, and further preferably 980 to 4900 N / cm. If the linear pressure of the flat roll is 196 N / cm or more, a separation membrane support excellent in mechanical strength can be obtained by firmly bonding the fibers constituting the nonwoven fabric and increasing the density of the nonwoven fabric. In addition, it is possible to obtain a good film forming property with less permeation and the like during casting of the polymer solution. On the other hand, if the linear pressure of the flat roll is 4900 N / cm or less, excessive fusion of the non-woven fabric surface fibers can be suppressed, and the penetration of the polymer solution into the non-woven fabric is not hindered, and the film adhesion strength is increased. An excellent separation membrane support can be obtained.

  In the method for producing a separation membrane support of the present invention, it is preferable to integrate two to five layers of laminated nonwoven fabrics by thermocompression bonding. If the number of laminated layers is two or more, the texture is improved as compared with a single layer, and sufficient uniformity can be obtained. Moreover, if the number of laminated layers is 5 or less, it is possible to suppress wrinkling during lamination and to suppress delamination between layers.

  As the nonwoven fabric constituting the separation membrane support of the present invention, nonwoven fabrics such as spunbond nonwoven fabrics, melt blown nonwoven fabrics, dry short fiber nonwoven fabrics and papermaking nonwoven fabrics, and composite nonwoven fabrics obtained by laminating these can be used.

  As a method of laminating nonwoven fabrics, in the case of spunbond nonwoven fabrics, fiber webs that have been extruded and fiberized in order from a plurality of spunbond nozzles arranged at the top of the collection conveyor are collected and laminated in sequence. A method of pressure bonding or a method of stacking a plurality of layers of spunbond nonwoven fabric once wound and then integrating them by thermocompression bonding is preferably used. Another preferred method is to unwind the spunbond nonwoven fabric once wound up, and then to extrude the spunbond nonwoven fabric from the spunbond nozzle, collect the fiberized fiber web, and perform thermocompression bonding.

  In the case of melt blown non-woven fabric, a method of collecting and laminating fiber webs that are extruded from a plurality of melt blow nozzles arranged on the upper part of a series of collection conveyors in order, and a plurality of melt blown non-woven fabrics once wound After layering, it is possible to use a method of integrating by thermocompression, or a method of unwinding a melt blown nonwoven fabric that has been wound up and then collecting the fiber web that has been extruded from a melt blow nozzle and then fiberized. However, since melt blown nonwoven fabric generally has low mechanical strength such as tensile strength, a method of laminating and integrating with a spunbond nonwoven fabric or the like is preferably used.

  As a composite nonwoven fabric in which a melt blown nonwoven fabric and a spunbond nonwoven fabric are laminated, a laminate having a three-layer structure in which a meltblown nonwoven fabric is disposed between two layers of a spunbond nonwoven fabric is preferably used. As its manufacturing method, a spunbond nozzle, a melt blow nozzle and a spunbond nozzle arranged on the upper part of a series of collection conveyors are each collected and laminated in order, and thermocompression bonded. And a method in which the melt-blown nonwoven fabric produced in a separate line is sandwiched between two layers of the spunbond nonwoven fabric once wound up and then integrated by thermocompression bonding.

  In the case of a dry short fiber nonwoven fabric or a papermaking nonwoven fabric, a method of stacking a plurality of wound nonwoven fabrics and then integrating them by thermocompression bonding can be preferably used.

  The nonwoven fabric constituting the separation membrane support of the present invention is preferably a long fiber nonwoven fabric. By using a long-fiber non-woven fabric composed of thermoplastic filaments, it is possible to suppress non-uniformity and membrane defects during casting of a polymer solution caused by fuzz, which is likely to occur when a short-fiber non-woven fabric is used. . Furthermore, among long fiber nonwoven fabrics, a spunbonded nonwoven fabric is a more preferred embodiment because it has high mechanical strength and can exhibit excellent durability as a separation membrane support.

  As a method for producing a spunbonded nonwoven fabric, a molten thermoplastic polymer is extruded from a nozzle, and after drawing and spinning with a high-speed suction gas, fibers are collected on a moving conveyor to form a fiber web, and further continuous. In particular, it can be manufactured by a so-called spunbond method in which a sheet is integrated by thermocompression bonding or entanglement. At that time, the spinning speed is preferably 3000 m / min or more, more preferably 3700 m / min or more, since the constituent fibers can be highly oriented and crystallized to obtain a nonwoven fabric excellent in mechanical strength. Yes, more preferably 4400 m / min or more. When making a thermoplastic filament into composite forms, such as a core-sheath type | mold, a normal composite method is employable.

  Moreover, as a thermocompression bonding method for spunbonded nonwoven fabric, a two-stage thermocompression bonding method including preliminary thermocompression bonding is used to control the properties of the nonwoven fabric more precisely than to thermocompress the nonwoven fabric with only one set of flat rolls. Can also be adopted. That is, the nonwoven fabric was preliminarily thermocompression bonded with a pair of flat rolls or preliminarily thermocompression bonded between a collection roll used for collecting one flat roll and a fiber web to obtain a temporarily bonded nonwoven fabric. Thereafter, a two-stage thermocompression bonding method in which a non-woven fabric in a continuous process or a temporarily bonded state is wound up and then further heat-compressed with another set of flat rolls can be preferably used.

In the first-stage preliminary thermocompression bonding in this two-stage thermocompression bonding method, since the nonwoven fabric can be densified at the time of the second-stage thermocompression bonding, the filling density of the nonwoven fabric in the temporarily bonded state is 0.1-0. .3 is preferable. In this case, the surface temperature of the flat roll used for the first stage pre-thermocompression bonding is preferably 20 to 120 ° C. lower than the melting point of the fibers constituting the nonwoven fabric, and the linear pressure is preferably 49 to 686 N / cm. In the present invention, the packing density refers to the basis weight (g / m ² ) and thickness (mm) obtained in (4) and (5) of Examples below, and the polymer density (polyethylene terephthalate: 1.38 g). / Cm ³ ), which is calculated using the following formula and rounded to the first decimal place.
・ Packing density = basis weight (g / m ² ) ÷ thickness (mm) ÷ 10 ³ ÷ polymer density (g / cm ³ )
The fiber constituting the nonwoven fabric constituting the separation membrane support of the present invention may be a single component fiber or a composite fiber composed of a plurality of components. It is a preferred embodiment that the union is composed of a composite fiber in which a low-melting polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high-melting polymer is disposed around the coalescence. When a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting point polymer is disposed around the high melting point polymer, a nonwoven fabric is formed by thermocompression bonding and used as a separation membrane support. In addition, since the fibers constituting the nonwoven fabric are firmly bonded to each other, nonuniformity and film defects during casting of the polymer solution due to fluffing can be suppressed, and a nonwoven fabric excellent in mechanical strength can be obtained.

  Further, by using such a composite fiber, the fibers constituting the nonwoven fabric are firmly bonded to each other, and in addition, a so-called mixed material obtained by mixing fibers composed only of a high melting point polymer and fibers composed only of a low melting point polymer. Since the number of adhesion points is larger than that of the fine fiber, a separation membrane support having better mechanical strength and durability can be obtained. If the melting point difference between the high melting point polymer and the low melting point polymer is 10 ° C. or more, the desired thermal adhesiveness can be obtained. If the melting point difference is 140 ° C. or less, the low melting point is applied to the thermocompression bonding roll during thermocompression bonding. It can suppress that a polymer component fuse | melts and productivity falls. A more preferable range of the melting point difference between the high melting point polymer and the low melting point polymer is 20 to 120 ° C, and a more preferable range is 30 to 100 ° C.

  Further, the separation membrane support of the present invention is composed of a composite type fiber in which a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting point polymer is arranged around the high melting point polymer. The melting point of the high-melting polymer in the case of a long-fiber nonwoven fabric has a good membrane-forming property when a separation membrane is formed on a separation membrane support to obtain a separation membrane with excellent mechanical strength and durability. Therefore, the temperature is preferably in the range of 160 to 320 ° C. When the melting point of the high-melting polymer is 160 ° C. or higher, when the nonwoven fabric is formed and used as the separation membrane support, the morphological stability is excellent even if it passes through the process of applying heat during the production of the separation membrane or fluid separation element. Moreover, if melting | fusing point is 320 degrees C or less, it can suppress that the heat energy for fuse | melting a thermoplastic polymer at the time of manufacture of a nonwoven fabric and the fiber used as the raw material is consumed greatly, and productivity falls. The more preferable range of the melting point of the high melting point polymer is 170 to 300 ° C, and the more preferable range is 180 to 280 ° C. Further, the melting point of the low melting point polymer is preferably 120 ° C. or higher, and more preferably 140 ° C. or higher.

  The proportion of the low melting point polymer in the composite fiber is preferably 10 to 70% by mass because a nonwoven fabric suitable for the separation membrane support can be obtained. If the proportion of the low-melting polymer is 10% by mass or more, desired thermal adhesiveness can be obtained, and if the proportion is 70% by mass or less, the low-melting polymer component is added to the thermocompression-bonding roll during thermocompression bonding. Can be prevented from being fused and the productivity is lowered. A more preferable range of the proportion of the low melting point polymer is 15 to 60% by mass, and a further preferable range is 20 to 50% by mass.

  About the composite form of a composite type fiber, the nonwoven fabric suitable for a separation membrane support can be obtained, for example, a concentric core sheath type, an eccentric core sheath type, a sea island type, etc. are mentioned. In addition, examples of the fiber cross-sectional shape include a circular cross-section, a flat cross-section, a polygonal cross-section, a multi-leaf cross-section, and a hollow cross-section. Among them, the fibers can be firmly bonded to each other by thermocompression bonding to obtain a nonwoven fabric excellent in mechanical strength. Further, the thickness of the obtained separation membrane support can be reduced, and separation per fluid separation element unit can be achieved. Since the membrane area can be increased, it is preferable to use a concentric core-sheath type for the composite form and a circular cross section or a flat cross section as the fiber shape.

  Further, a non-woven fabric composed of composite fibers comprising polymers having different melting points, and a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting point polymer around the high melting point polymer. In the case of thermocompression bonding with a flat roll, the surface temperature of the metal roll is preferably 20 to 90 ° C. lower than the melting point of the low-melting polymer, more preferably 30 to 70 ° C.

  In the present invention, the raw material of the fibers constituting the nonwoven fabric can be obtained as a nonwoven fabric suitable for the separation membrane support. For example, a polyester polymer, a polyamide polymer, a polyolefin polymer, or a mixture thereof. Polyester copolymer is preferably used because a separation membrane support having excellent durability such as mechanical strength, heat resistance, water resistance and chemical resistance can be obtained. .

  The polyester polymer used in the present invention is a polyester composed of an acid component and an alcohol component. Examples of the acid component include aromatic carboxylic acids such as terephthalic acid, isophthalic acid and phthalic acid, aliphatic dicarboxylic acids such as adipic acid and sebacic acid, and alicyclic dicarboxylic acids such as cyclohexanecarboxylic acid. Further, as the alcohol component, ethylene glycol, diethylene glycol, polyethylene glycol, or the like can be used.

  Examples of the polyester polymer include polyethylene terephthalate resin, polybutylene terephthalate resin, polytrimethylene terephthalate resin, polyethylene naphthalate resin, polylactic acid resin, and polybutylene succinate resin. Examples include coalescence.

  Further, a low melting point polymer having a melting point lower by 10 to 140 ° C. than the melting point of the high melting point polymer is disposed around the high melting point polymer. Combinations (high-melting point polymer / low-melting point polymer) can also be used to obtain a nonwoven fabric suitable for a separation membrane support. For example, polyethylene terephthalate resin / polybutylene terephthalate resin, polyethylene terephthalate resin / polytrimethylene terephthalate. Examples thereof include combinations of resin, polyethylene terephthalate resin / polylactic acid resin, polyethylene terephthalate resin / copolymerized polyethylene terephthalate resin, and polyethylene terephthalate resin / copolymerized polybutylene terephthalate resin. In addition, isophthalic acid or the like is preferably used as a copolymerization component of a copolymerized polyethylene terephthalate resin or a copolymerized polybutylene terephthalate resin.

  Furthermore, when the separation membrane support is discarded after use, biodegradable resin is also preferably used as a raw material for the fibers constituting the nonwoven fabric because it is easy to discard and has a low environmental impact. Examples of the biodegradable resin used in the present invention include polylactic acid resin, polybutylene succinate resin, polycaprolactone resin, polyethylene succinate resin, polyglycolic acid resin, and polyhydroxybutyrate resin. Above all, it is a plant-derived resin that does not deplete petroleum resources, has relatively high mechanical properties and heat resistance, and has recently attracted attention as a biodegradable resin with low production costs. The polylactic acid resin used is preferably used as a raw material for fibers constituting the nonwoven fabric.

  The polylactic acid resin used in the present invention is preferably poly (D-lactic acid), poly (L-lactic acid), a copolymer of D-lactic acid and L-lactic acid, or a blend thereof.

  In the nonwoven fabric constituting the separation membrane support of the present invention, crystal nucleating agents, matting agents, lubricants, pigments, antifungal agents, antibacterial agents, flame retardants, hydrophilic agents, etc. Additives may be added. In particular, during thermocompression molding of nonwoven fabrics, metal oxides such as titanium oxide that have the effect of improving the adhesion of nonwoven fabrics by increasing thermal conductivity, and releasability between thermocompression rolls and webs are increased. It is preferable to add an aliphatic bisamide such as ethylenebisstearic acid amide and / or an alkyl-substituted aliphatic monoamide, which has an effect of improving the adhesion stability. In addition, when forming a separation membrane by a wet coagulation method, it is also a preferable aspect to add a hydrophilic agent such as a surfactant that has an effect of promptly proceeding with solvent replacement inside the support.

  These various additives may be present in the fiber by kneading in the raw material in advance, or may be present on the surface of the fiber by an application process after manufacturing the fiber or the nonwoven fabric.

  In the separation membrane support of the present invention, the average fiber diameter of the fibers (single fibers) constituting the nonwoven fabric is preferably 3 to 30 μm, more preferably 5 to 25 μm, and further preferably 7 to 20 μm. .

  If the average fiber diameter of the fibers constituting the nonwoven fabric is 3 μm or more, the spinnability is less likely to deteriorate during the production of the nonwoven fabric and the fibers used as the raw material, and the air permeability of the separation membrane support can be maintained. Excess fusion can be suppressed, the polymer solution can easily penetrate during casting, and a separation membrane support excellent in membrane adhesive strength can be obtained. On the other hand, if the average fiber diameter of the fibers constituting the nonwoven fabric is 30 μm or less, a nonwoven fabric and a separation membrane support excellent in uniformity can be obtained, and the separation membrane support can be densified. There is little over-penetration etc. at the time of casting of a solution, and favorable film forming property can be obtained.

The basis weight of the nonwoven fabric constituting the separation membrane support of the present invention is preferably ²⁰ to 150 g / m ² , more preferably 30 to 120 g / m ² , and further preferably 40 to 90 g / m ² . . If the basis weight of the nonwoven fabric is 20 g / m ² or more, a separation membrane excellent in mechanical strength and durability can be obtained with less permeation at the time of casting of the polymer solution and with good film forming properties. Can be obtained. On the other hand, when the basis weight of the nonwoven fabric is 150 g / m ² or less, the thickness of the separation membrane can be reduced, and the separation membrane area per fluid separation element unit can be increased.

  The thickness of the nonwoven fabric constituting the separation membrane support of the present invention is preferably 0.03 to 0.20 mm, more preferably 0.04 to 0.16 mm, and even more preferably 0.05 to 0. .12 mm. If the thickness of the nonwoven fabric is 0.03 mm or more, it is possible to obtain a good film-forming property with little over-penetration during casting of the polymer solution, and excellent mechanical strength and durability. Obtainable. On the other hand, if the thickness of the nonwoven fabric is 0.20 mm or less, the thickness of the separation membrane can be reduced, and the separation membrane area per fluid separation element unit can be increased.

  The separation membrane of the present invention is a separation membrane formed by forming a membrane having a separation function on the above-mentioned separation membrane support. Examples of such separation membranes include microfiltration membranes, ultrafiltration membranes, and semipermeable membranes such as nanofiltration membranes and reverse osmosis membranes. As a method for producing the separation membrane, a method of forming a membrane having a separation function by casting a polymer solution on at least one surface of the above-mentioned separation membrane support is preferably used. When the separation membrane is a semipermeable membrane, the membrane having a separation function may be a composite membrane including a support layer and a semipermeable membrane layer, and the composite membrane may be laminated on at least one surface of the separation membrane support. This is a preferred form.

  The polymer solution cast on the separation membrane support of the present invention has a separation function when it becomes a membrane. For example, polyarylethersulfone such as polysulfone and polyethersulfone, polyimide, polyfluoride, and the like. Solutions such as vinylidene chloride and cellulose acetate are preferably used. In particular, a solution of polysulfone and polyarylethersulfone is preferably used in terms of chemical, mechanical and thermal stability. The solvent can be appropriately selected according to the film-forming substance. As the semipermeable membrane when the separation membrane is a composite membrane comprising a support layer and a semipermeable membrane layer, a crosslinked polyamide membrane obtained by polycondensation of a polyfunctional acid halide and a polyfunctional amine is preferably used.

  The fluid separation element of the present invention is a fluid separation element in which the separation membrane is housed in a housing for easy handling. Examples of the form include flat membrane plate frame type, pleated type and spiral type, and in particular, the separation membrane is spirally formed around the water collecting pipe together with the permeate channel material and the supply fluid channel material. A spiral type wound around is preferably used. A plurality of fluid separation elements can be connected in series or in parallel to form a separation membrane unit.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited by these Examples. Further, the above-described separation membrane support, the nonwoven fabric constituting the separation membrane support, the characteristic values of the fibers constituting the nonwoven fabric, and the characteristic values in the following examples are measured by the following methods.

(1) Melting point (° C)
Using a differential scanning calorimeter DSC-2 manufactured by Perkin Elma Co., Ltd., measurement was performed under the condition of a temperature rising rate of 20 ° C./min, and the temperature giving an extreme value in the obtained melting endotherm curve was defined as the melting point. Further, for a resin whose melting endotherm curve does not show an extreme value in a differential scanning calorimeter, the resin was heated on a hot plate, and the temperature at which the resin was completely melted by microscopic observation was taken as the melting point.

(2) Intrinsic viscosity IV
The intrinsic viscosity IV of the polyethylene terephthalate resin was measured by the following method. 8 g of a sample was dissolved in 100 ml of orthochlorophenol, and the relative viscosity η _r was determined by the following formula using an Ostwald viscometer at a temperature of 25 ° C.
η _r = η / η ₀ = (t × d) / (t ₀ × d ₀ )
Where η: viscosity of the polymer solution
η ₀ : viscosity of orthochlorophenol
t: Dropping time of solution (second)
d: density of the solution (g / cm ³ )
t ₀ : Fall time of orthochlorophenol (seconds)
d ₀ : Orthochlorophenol density (g / cm ³ )
Then, from the relative viscosity η _r , the following formula:
IV = 0.0242η _r +0.2634
Was used to calculate the intrinsic viscosity IV.

(3) Average fiber diameter (μm)
Ten small sample samples were taken at random from the non-woven fabric, photographed at 500 to 3000 times with a scanning electron microscope, 10 fibers from each sample were measured, and the diameter of 100 fibers in total was measured. Calculated by rounding off the first decimal place.

(4) Fabric weight of nonwoven fabric (g / m ² )
Three non-woven fabrics of 30 cm × 50 cm were collected, the weight of each sample was measured, the average value of the obtained values was converted per unit area, and the first decimal place was rounded off.

(5) Non-woven fabric thickness (mm)
Based on 5.1 of JIS L 1906 (2000 version), using a pressurizer with a diameter of 10 mm, measure the thickness in units of 0.01 mm at 10 points at equal intervals per 1 m in the width direction of the nonwoven fabric with a load of 10 kPa, The average value was rounded to the second decimal place.

(6) Tensile strength (N / 5cm) and tensile elongation (%) of nonwoven fabric
Based on JIS L 1906 (2000 edition) 5.3.1, 5 cm × 30 cm nonwoven fabric sample is strong at 5 points each in the machine direction and the transverse direction at a gripping distance of 20 cm and a tensile speed of 10 cm / min. Elongation was measured, the strength and elongation at break were read, and the values rounded to the first decimal place were taken as the tensile strength and tensile elongation in the longitudinal and transverse directions of the nonwoven fabric, respectively.

(7) Young's modulus of non-woven fabric (MPa)
Based on JIS L 1906 (2000 edition) 5.3.1, 5 cm x 30 cm nonwoven fabric samples were measured at 5 points each in the machine direction and the transverse direction under the conditions of a grip interval of 20 cm and a tensile speed of 10 cm / min. Then, the initial tensile resistance (value at the time of 100% elongation at the initial slope) is read from the obtained strength elongation curve, and the value obtained by rounding off the first decimal place is the sample width (5 cm) and the above (5). The value obtained by dividing by the thickness of the obtained nonwoven fabric and rounding off the first decimal place was taken as the Young's modulus in the longitudinal and lateral directions of the nonwoven fabric.

(8) Penetration of cast liquid during membrane formation [Reverse osmosis membrane for seawater desalination]
Each separation membrane support having a width of 50 cm was unwound at a speed of 12 m / min, and a 15% by weight dimethylformamide solution (casting solution) of polysulfone (“Udel” (registered trademark) -P3500 manufactured by Solvay Advanced Polymers) was further formed thereon. ) With a cast width of 46 cm and a thickness of 50 μm, cast at room temperature (20 ° C.), immediately immersed in pure water at room temperature (20 ° C.) for 10 seconds, and then immersed in pure water at a temperature of 75 ° C. for 120 seconds, Subsequently, it was immersed in pure water at a temperature of 90 ° C. for 120 seconds, and wound with a tension of 100 N / full width to produce a polysulfone membrane.

Next, the back surface of the produced polysulfone membrane was visually observed, and the penetration of the cast liquid was evaluated in the following five stages.
5 points: There is no see-through of cast liquid.
4 points: Slightly see-through of casting solution is observed (area ratio is less than 5%).
3 points: See-through of casting solution is observed (area ratio: 5 to 50%).
2 points: The cast-through of the cast liquid is observed in the majority (area ratio 51 to 80%).
1 point: The cast liquid can be seen through almost the entire surface.

  Further, the produced polysulfone membrane was dipped in a 1.5% by mass aqueous solution of m-phenylenediamine and pulled up, and subsequently a 0.06% by mass n-decane solution of trimesic acid chloride was applied to form a crosslinked polyamide separation functional layer. A reverse osmosis membrane for seawater desalination was formed.

(9) Separation membrane sagging amount (μm) and membrane adhesion state Effective using a feed liquid channel material made of mesh fabric, the above-mentioned reverse osmosis membrane for seawater desalination, a pressure-resistant sheet, and the following permeate channel material A spiral fluid separation element (element) having a membrane area of 40 m ² was produced.

[Permeate channel material]
A polyester single tricot having a groove width of 200 μm, a groove depth of 150 μm, a groove density of 15.7 pieces / cm, and a thickness of 200 μm was used.

Next, the manufactured fluid separation element was subjected to a durability test under conditions of a reverse osmotic pressure of 7 MPa, a seawater salt concentration of 3% by mass, and an operating temperature of 40 ° C. After dismantling, the amount of separation membrane dropped into the permeate channel material was measured. The amount of sagging is measured by taking 500-3000 times photographs with a scanning electron microscope (unit: μm) for any three cross sections of the separation membrane in one fluid separation element. Calculated by rounding to the first place. The direction in which the separation membrane support and the permeate flow path material overlap each other was such that the nonwoven fabric width direction (lateral direction) of the separation membrane support was orthogonal to the groove direction of the permeate flow path material.
Moreover, the disassembled separation membrane surface was visually observed, and the membrane adhesion state was evaluated in the following five stages, and those having an evaluation score of 4 or more were regarded as acceptable.
5 points: No film peeling is observed.
4 points: Slight film peeling is observed (area ratio is less than 1%).
3 points: Delamination is observed (area ratio: 1 to 10%).
2 points: Much film peeling is observed (area ratio of 11 to 30%).
1 point: Much film peeling is observed (area ratio of 31% or more).

(10) Hardness of elastic roll Along the surface length direction of the elastic roll surface, a hardness tester (Shore D) was measured by pressing three points at a position of 5 cm and a center position from both ends of the effective portion of the roll, and the average value thereof. The first decimal place was rounded off.

Example 1
The intrinsic viscosity IV dried to a water content of 50 ppm or less is 0.65, the melting point is 260 ° C., a polyethylene terephthalate resin containing 0.3% by mass of titanium oxide, and the intrinsic viscosity IV dried to a water content of 50 ppm or less is 0.00. 66, a copolymerized polyester resin having an isophthalic acid copolymerization ratio of 11 mol%, a melting point of 230 ° C., and containing 0.2% by mass of titanium oxide was melted at a temperature of 295 ° C. and 270 ° C., respectively. After spinning from pores at a base temperature of 300 ° C. and a sheath component ratio of 20% by mass using a resin as a core component and a copolyester resin as a sheath component, a spinning speed of 4400 m / min is obtained by a rectangular ejector having slits in the nonwoven fabric width direction. To form concentric core-sheath filaments (circular cross section), and the filaments are sprayed 15 ° backward with respect to the perpendicular. It was collected as a fibrous web on a moving net conveyor. The collected fiber web is passed between two metal flat rolls, each metal roll surface temperature is 140 ° C., pre-pressure bonding is performed at a linear pressure of 588 N / cm, the fiber orientation degree is 28 °, and the fiber diameter is 10 μm. Thus, a temporarily bonded spunbond (SB) nonwoven fabric (a) having a basis weight of 35 g / m ² and a thickness of 0.15 mm was produced.

Next, except that the spray angle of the filament group was 0 ° with respect to the perpendicular, the same conditions as in the spunbonded nonwoven fabric (a) were used, the fiber orientation was 40 °, the fiber diameter was 10 μm, and the basis weight was 35 g / m ^2. Thus, a temporarily bonded spunbond nonwoven fabric (b) having a thickness of 0.15 mm was produced.

The obtained temporarily bonded spunbond nonwoven fabric (a) and the temporarily bonded spunbond nonwoven fabric (b) are superposed one by one so that the temporarily bonded spunbond nonwoven fabric (b) is on top. The upper is an elastic roll made of polyester resin having a hardness (Shore D) 91 (surface length: about 1.4 m), the inside is a metal roll, and the lower is an elastic roll made of polyester resin having a hardness (Shore D) of 75 (surface length: approximately 1.4 m) of a set of three in the flat-rolled - thermocompression bonding passed between lower, upper further folded nonwoven - thermocompression bonding through an intermediate basis weight in the 70 g / m ^2, A spunbond nonwoven fabric having a thickness of 0.09 mm was produced to obtain a separation membrane support. The surface temperature of the three flat rolls at this time was 100 ° C. on the top, 180 ° C. on the inside, 140 ° C. on the bottom, and the linear pressure was 1667 N / cm. The results are shown in Tables 1 and 2.

(Example 2)
A temporarily bonded spunbond nonwoven fabric (c) was produced under the same conditions as the temporarily bonded spunbond nonwoven fabric (b) of Example 1 except that the basis weight was 70 g / m ² and the thickness was 0.25 mm. .

One piece of the temporarily bonded spunbond nonwoven fabric (c) obtained was thermocompression bonded under the same conditions as in Example 1 to produce a spunbonded nonwoven fabric having a basis weight of 70 g / m ² and a thickness of 0.09 mm. A separation membrane support was obtained. The results are shown in Tables 1 and 2.

(Example 3)
The temporarily bonded spunbond nonwoven fabric (a) and the temporarily bonded spunbond nonwoven fabric (b) of Example 1 were superposed one by one so that the temporarily bonded spunbond nonwoven fabric (b) was on top, The three flat rolls are thermocompression bonded under the same conditions as in Example 1 except that the hardness (Shore D) is 80 on the top and the hardness (Shore D) is 91 on the bottom, the basis weight is 70 g / m ² , and the thickness is Produced a spunbonded nonwoven fabric having a thickness of 0.08 mm to obtain a separation membrane support. The results are shown in Tables 1 and 2.

(Examples 4 to 7)
The temporarily bonded spunbond nonwoven fabric (a) and the temporarily bonded spunbond nonwoven fabric (b) of Example 1 were superposed one by one so that the temporarily bonded spunbond nonwoven fabric (b) was on top, Between the two flat rolls of a pair of elastic rolls (surface length: about 1.4 m) made of polyester resin having a metal roll on the top and hardness (Shore D) 70, 75, 80, 97 on the bottom. Through thermocompression bonding, a spunbonded nonwoven fabric having a basis weight of 70 g / m ² and thicknesses of 0.11 mm, 0.10 mm, 0.10 mm, and 0.08 mm was manufactured to obtain a separation membrane support. The surface temperature of the two flat rolls at this time was 180 ° C. on the top, 130 ° C. on the bottom, and the linear pressure was 1667 N / cm. The results are shown in Tables 1 and 2.

(Example 8)
The temporarily bonded spunbond nonwoven fabric (a) and the temporarily bonded spunbond nonwoven fabric (b) of Example 1 were superposed one by one so that the temporarily bonded spunbond nonwoven fabric (b) was on top, Is thermocompression-bonded between a pair of two flat rolls (surface length: about 1.4 m) of an elastic roll made of a polyester resin having a metal roll on the top and a hardness (Shore D) 75 on the bottom. Bond nonwoven fabric (A) was obtained.
The obtained spunbonded nonwoven fabric (A) is turned upside down, and an elastic roll (surface length: about 1.4 m) made of a polyester resin having a metal roll on the upper side and a hardness (Shore D) 75 on the lower side. A thermobonding was conducted between a pair of two flat rolls to produce a spunbonded nonwoven fabric having a basis weight of 70 g / m ² and a thickness of 0.09 mm to obtain a separation membrane support. The surface temperature of the two flat rolls at this time was 180 ° C. on the top, 130 ° C. on the bottom, and the line pressure was 1667 N / cm in both thermocompression bonding. The results are shown in Tables 3 and 4.

Example 9
A temporarily bonded spunbond nonwoven fabric (d) was produced under the same conditions as in the temporarily bonded spunbond nonwoven fabric (a) of Example 1 except that the spinning speed was 3600 m / min.

  Next, the spunbond nonwoven fabric (e) in the temporarily bonded state was manufactured under the same conditions as the temporarily bonded spunbond nonwoven fabric (b) in Example 1 except that the spinning speed was 3600 m / min.

The obtained temporarily bonded spunbond nonwoven fabric (d) and the temporarily bonded spunbond nonwoven fabric (e) are superposed one by one so that the temporarily bonded spunbond nonwoven fabric (e) is on top. Then, thermocompression bonding was performed under the same conditions as in Example 1 to produce a spunbonded nonwoven fabric having a basis weight of 70 g / m ² and a thickness of 0.09 mm to obtain a separation membrane support. The results are shown in Tables 3 and 4.

(Example 10)
A temporarily bonded spunbond nonwoven fabric (f) was manufactured under the same conditions as those of the temporarily bonded spunbond nonwoven fabric (a) of Example 1 except that the basis weight was 23 g / m ² and the thickness was 0.13 mm. .

Next, except that the basis weight is 23 g / m ² and the thickness is 0.13 mm, the conditions are the same as the temporarily bonded spunbond nonwoven fabric (b) of Example 1, and the temporarily bonded spunbond nonwoven fabric (g) Manufactured.

One piece of the temporarily bonded spunbond nonwoven fabric (f) and two pieces of the temporarily bonded spunbond nonwoven fabric (g) so that the temporarily bonded spunbond nonwoven fabric (f) is at the bottom. And bonded to each other under the same conditions as in Example 1 to produce a spunbond nonwoven fabric having a basis weight of 69 g / m ² and a thickness of 0.09 mm to obtain a separation membrane support. The results are shown in Tables 3 and 4.

(Example 11)
A polyethylene terephthalate resin dried at a moisture content of 50 ppm or less and having an intrinsic viscosity IV of 0.65, a melting point of 260 ° C. and containing 0.3% by mass of titanium oxide at a temperature of 295 ° C. is melted at a die temperature of 300 ° C. After spinning from the fine pores, a rectangular conveyor with slits in the width direction of the nonwoven fabric is spun at a spinning speed of 4400 m / min. It was collected as a fiber web on top. The discharge amount was adjusted so that the basis weight of the spunbond nonwoven fabric layer (A) was 30 g / m ² .

Subsequently, after a polyethylene terephthalate resin having an intrinsic viscosity IV of 0.50 and a melting point of 260 ° C. dried to a moisture content of 50 ppm or less was melted at a temperature of 295 ° C. and spouted from the pores at a die temperature of 300 ° C. The melt blown nonwoven fabric layer (b) was collected on the spunbonded nonwoven fabric layer (b) on the moving net conveyor by spinning and spraying with heated air of 1000 Nm ³ / hr / m. The discharge amount was adjusted so that the basis weight of the melt blown (MB) nonwoven fabric layer (b) was 10 g / m ² .

Furthermore, the spunbond nonwoven fabric layer (c) was collected on the melt blown nonwoven fabric layer (b) under the same conditions as the spunbond nonwoven fabric layer (b). The discharge amount was adjusted so that the basis weight of the spunbond nonwoven fabric layer (c) was 30 g / m ² .

The collected laminated fiber web is passed between a metal flat roll and a net conveyor, and the surface temperature of the flat roll is 180 ° C., the linear pressure is 294 N / cm, preliminarily thermocompression bonded, the basis weight is 70 g / m ² , A 0.35 mm temporarily bonded spunbond / meltblown / spunbond composite nonwoven fabric was produced.

A pair of two flat rolls of an elastic roll (surface length: about 1.4 m) made of a polyester resin having a metal roll on the top and a hardness (Shore D) of 75 on the composite nonwoven fabric in the temporarily bonded state. A composite non-woven fabric having a basis weight of 70 g / m ² and a thickness of 0.09 mm was manufactured to obtain a separation membrane support. The surface temperature of the two flat rolls at this time was 235 ° C. on the top, 140 ° C. on the bottom, and the linear pressure was 1471 N / cm. The results are shown in Tables 3 and 4.

(Example 12)
Made of a polyethylene terephthalate resin having a melting point of 260 ° C., a fiber diameter of 10 μm, a basis weight of 35 g / m ² and a thickness of 0.15 mm, and a polyethylene terephthalate resin having a melting point of 260 ° C. A papermaking nonwoven fabric (B) having a fiber diameter of 13 μm, a basis weight of 35 g / m ² and a thickness of 0.17 mm was prepared.

The prepared papermaking nonwoven fabric (former) and papermaking nonwoven fabric (former) are stacked one by one so that the papermaking nonwoven fabric (former) is on top, and the top is a metal roll and the bottom is hardness (Shore D) 85 A paper-made non-woven fabric with a basis weight of 70 g / m ² and a thickness of 0.09 mm is produced by thermocompression bonding between a pair of two flat rolls of cotton paper elastic roll (surface length: about 1.4 m). As a result, a separation membrane support was obtained. The surface temperature of the two flat rolls at this time was 230 ° C. on the top, 130 ° C. on the bottom, and the linear pressure was 1177 N / cm. The results are shown in Tables 3 and 4.

  The characteristics of the obtained separation membrane support are as shown in Tables 1 to 4, and when the reverse osmosis membrane for seawater desalination was prepared using the separation membrane support of Examples 1 to 12, both were No film defects due to over-penetration or fluffing of the film-forming stock solution were observed, and the film-forming property was good. Furthermore, when a fluid separation element was produced using this reverse osmosis membrane, the workability was good, and as a result of evaluating the durability of the produced fluid separation element, the reverse osmosis membrane sagging amount was 50 μm or less. Yes, the film adhesion was good, and the durability was excellent.

(Comparative Example 1)
The temporarily bonded spunbond nonwoven fabric (a) and the temporarily bonded spunbond nonwoven fabric (b) of Example 1 were superposed one by one so that the temporarily bonded spunbond nonwoven fabric (b) was on top, Is thermocompression-bonded between a pair of two flat rolls of a polyester resin elastic roll (surface length: about 1.4 m) with a metal roll on the top and a hardness (Shore D) of 65 on the bottom. There at 70 g / ^{m 2,} thickness to produce a spunbonded nonwoven fabric of 0.12 mm, to obtain a separation membrane support. The surface temperature of the two flat rolls at this time was 180 ° C. on the top, 130 ° C. on the bottom, and the linear pressure was 1667 N / cm. The results are shown in Tables 3 and 4.

(Comparative Example 2)
The temporarily bonded spunbond nonwoven fabric (a) and the temporarily bonded spunbond nonwoven fabric (b) of Example 1 were superposed one by one so that the temporarily bonded spunbond nonwoven fabric (b) was on top, Are bonded by thermo-compression between a pair of two flat rolls of metal rolls on the upper and lower sides to produce a spunbonded nonwoven fabric having a basis weight of 70 g / m ² and a thickness of 0.08 mm to obtain a separation membrane support It was. The surface temperature of the two flat rolls at this time was 180 ° C. on the top, 130 ° C. on the bottom, and the linear pressure was 1667 N / cm. The results are shown in Tables 3 and 4.

  The characteristics of the obtained separation membrane support are as shown in Tables 3 and 4. When a reverse osmosis membrane for seawater desalination was produced using the separation membrane support of Comparative Example 1, Membrane defects due to over-osmosis and fluffing are not seen, and the film-forming property is good. Furthermore, when a fluid separation element was produced using this reverse osmosis membrane, the workability was good. As a result of the durability evaluation, the amount of the reverse osmosis membrane sagging exceeded 50 μm, and the durability was poor. Moreover, when the reverse osmosis membrane for seawater desalination was produced using the separation membrane support of Comparative Example 2, the polysulfone membrane was peeled off partially without permeation of the membrane-forming stock solution, and the membrane-forming property was poor. A reverse osmosis membrane for desalination could not be produced.

Claims (4)

  A method for producing a separation membrane support in which a nonwoven fabric is thermocompression bonded by two or more flat rolls, wherein the flat roll is composed of a combination including a metal roll and an elastic roll, and the hardness (Shore D) of the elastic roll is 70. A method for producing a separation membrane support, characterized by being -99.   The method for producing a separation membrane support according to claim 1, wherein 2 to 5 layers of non-woven fabric are integrated by thermocompression bonding.   A separation membrane obtained by forming a membrane having a separation function on the surface of a separation membrane support produced by the method for producing a separation membrane support according to claim 1 or 2.   A fluid separation element comprising the separation membrane according to claim 3 as a constituent element.