JP2014064973A - Separation membrane and separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a separation membrane element which can improve separation membrane element performance by reducing flow resistance of the separation membrane element.SOLUTION: A separation membrane element includes: a separation membrane main body having at least a base material and a separation function layer; and a flow channel member 3 fixed to a surface of the separation membrane main body on a base material side. A permeating water amount of the separation membrane element is increased by increasing a thickness of the flow channel member on a first end side of the separation membrane in a first direction than a thickness of the flow channel member on a second end side.

Description

  The present invention relates to a separation membrane element used for separating components contained in a fluid such as liquid or gas.

  There are various methods for separating components contained in fluid such as liquid and gas. For example, taking a technique for removing ionic substances contained in seawater, brine, and the like as an example, in recent years, the use of a separation method using a separation membrane element is expanding as a process for saving energy and resources. Separation membranes used in separation methods using separation membrane elements are classified into microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, reverse osmosis membranes, forward osmosis membranes, and the like in terms of their pore diameter and separation function. These membranes are used, for example, in the production of drinking water from seawater, brine, or water containing harmful substances, in the production of industrial ultrapure water, wastewater treatment, recovery of valuable materials, and the like.

  In the separation membrane element, a raw fluid is supplied to one surface of the separation membrane and a permeating fluid is obtained from the other surface. By bundling a large number of separation membranes into a separation membrane element, the membrane area per separation membrane element can be increased, and as a result, the production amount of permeated fluid per separation membrane element can be increased. Can do. Currently, various forms such as a spiral type, a hollow fiber type, a plate and frame type, a rotating flat membrane type, and a flat membrane integrated type have been proposed as separation membrane elements.

  For example, a fluid separation membrane element used for reverse osmosis filtration includes a supply-side channel material that supplies raw fluid to the surface of the separation membrane, a separation membrane that separates components contained in the raw fluid, and a supply fluid that permeates the separation membrane. A permeate-side channel material for guiding the permeated fluid separated from the gas to the central tube is incorporated. As the supply-side channel material, a polymer net or the like is used. Further, as the permeation side channel material, a knitted member called a tricot having a smaller interval than the supply side channel material is used for the purpose of preventing the separation membrane from dropping and forming the permeation side channel. . The separation membrane forms an envelope-like membrane by being laminated and bonded to both surfaces of the permeate-side channel material. The inner side of the envelope membrane constitutes a flow path for the permeating fluid. The envelope-like membrane is alternately laminated with the supply-side channel material, and a predetermined portion on the opening side is bonded to the outer peripheral surface of the water collecting pipe and is wound in a spiral shape.

  In order to improve the performance of the separation membrane element, Patent Document 1 proposes to gradually increase the thickness of the permeate-side channel material from the outer side to the inner side in the winding direction of the separation membrane. Patent Document 2 proposes that a permeation-side flow path material made of a different material from the separation membrane is disposed on the permeation-side surface of the separation membrane.

Japanese Patent Laid-Open No. 2009-195871 Japanese Unexamined Patent Publication No. 2012-40487

  By gradually increasing the thickness of the permeate-side channel material from the outside in the winding direction of the separation membrane to the inside, the flow resistance inside the winding direction where the flow rate increases and the flow resistance increases can be reduced. In the flow channel material, the entire thickness of the permeate side flow channel material cannot be used as the flow channel, so that the effect of reducing the flow resistance by increasing the thickness is not sufficient.

  It is an object of the present invention to provide a separation membrane element that can sufficiently improve the performance of the separation membrane element with respect to the separation membrane element, and that can easily surround the separation membrane body.

  A separation membrane comprising at least a separation membrane main body having a base material and a separation functional layer, and a flow path material fixed to the surface of the separation membrane main body on the base material side, wherein the first separation membrane in the first direction The thickness of the channel material on the end side is larger than the thickness of the channel material on the second end side.

  According to the separation membrane element of the present invention, since the flow resistance on the permeate side can be greatly reduced, the amount of permeated water of the separation membrane element can be increased.

It is a top view which shows the separation membrane provided with the flow-path material provided discontinuously in the width direction of the separation membrane. It is sectional drawing of the separation membrane shown in FIG. It is a development perspective view showing one form of a separation membrane element. It is a disassembled perspective view which shows one form of an envelope-shaped film | membrane. It is sectional drawing which shows an example of thickness distribution of the permeation | transmission side channel material in a length direction. It is sectional drawing which shows the other example of distribution of the thickness of the permeation | transmission side channel material in a length direction. It is sectional drawing which shows the further another example of distribution of the thickness of the permeation | transmission side channel material in a length direction. It is sectional drawing which shows the further another example of distribution of the thickness of the permeation | transmission side channel material in a length direction. It is sectional drawing which shows the further another example of distribution of the thickness of the permeation | transmission side channel material in a length direction. It is sectional drawing which shows the further another example of distribution of the thickness of the permeation | transmission side channel material in a length direction. It is sectional drawing which shows one form of the length direction distribution of the width | variety of the permeation | transmission side channel material. It is sectional drawing which shows one form of the length direction distribution of the width | variety of the permeation | transmission side channel material. It is sectional drawing which shows distribution of the thickness of the permeation | transmission side channel material in a comparative example.

  Hereinafter, an embodiment of the present invention will be described in detail.

  In this document, “X contains Y as a main component” means that the Y content in X is 50% by weight, 70% by weight, 80% by weight, 90% by weight, or 95% by weight. It means that it is more than%. In addition, when there are a plurality of components corresponding to Y, the total amount of these components only needs to satisfy the above range.

[1. Separation membrane)
(1-1) Overview A separation membrane is a membrane that can separate components in a fluid supplied to the surface of the separation membrane and obtain a permeated fluid that has permeated the separation membrane. The separation membrane includes a separation membrane main body and a flow path material disposed on the separation membrane main body.

  As an example of such a separation membrane, the separation membrane 1 of the present embodiment includes a separation membrane body 2 and a flow path member 3 as shown in FIGS. The separation membrane body 2 includes a supply-side surface 21 and a permeation-side surface 22.

  In this document, the “supply-side surface” of the separation membrane body means a surface on the side to which the raw fluid is supplied, of the two surfaces of the separation membrane body. The “transmission side surface” means the opposite side surface. As will be described later, when the separation membrane main body includes a base material and a separation functional layer, generally, the surface on the separation functional layer side is the surface on the supply side, and the surface on the base material side is the surface on the transmission side. .

  The channel material 3 is provided on the transmission side surface 22 so as to form a channel. Details of each part of the separation membrane 1 will be described later.

  In this document, the “length direction” of the separation membrane is the y-axis direction shown in the figure and may be referred to as the first direction. Further, the “width direction” of the separation membrane is the x-axis direction shown in the figure, and may be referred to as the second direction. The z axis corresponds to the thickness direction of the separation membrane.

  As shown in the figure, the separation membrane main body 2 is rectangular, and the length direction and the width direction are parallel to two orthogonal sides of the separation membrane main body 2.

(1-2) Separation membrane body <Overview>
As the separation membrane body, a membrane having separation performance according to the method of use, purpose and the like is used. The separation membrane body may be formed of a single layer or a composite membrane including a separation functional layer and a substrate. In the composite membrane, a porous support layer may be provided between the separation functional layer and the substrate.

<Separation function layer>
The thickness of the separation functional layer is not limited to a specific numerical value, but is preferably 5 to 3000 nm in terms of separation performance and permeation performance. In particular, it is preferably 5 to 300 nm for reverse osmosis membranes, forward osmosis membranes, and nanofiltration membranes.

  The thickness of the separation functional layer can be based on the conventional method for measuring the thickness of the separation membrane. For example, the separation membrane is embedded with resin, and an ultrathin section is prepared by cutting the separation membrane, and the obtained section is subjected to processing such as staining. Thereafter, the thickness can be measured by observing with a transmission electron microscope. Further, when the separation functional layer has a pleat structure, measurement can be made at intervals of 50 nm in the cross-sectional length direction of the pleat structure located above the porous support layer, the number of pleats can be measured, and the average can be obtained. it can.

  The separation function layer may be a layer having both a separation function and a support function, or may have only a separation function. The “separation function layer” refers to a layer having at least a separation function.

  When the separation functional layer has both a separation function and a support function, a layer containing cellulose, polyvinylidene fluoride, polyether sulfone, or polysulfone as a main component is preferably applied as the separation functional layer.

  On the other hand, as the porous support layer separating functional layer, a crosslinked polymer is preferably used in terms of easy control of the pore diameter and excellent durability. In particular, a polyamide separation functional layer obtained by polycondensation of a polyfunctional amine and a polyfunctional acid halide, an organic / inorganic hybrid functional layer, and the like are preferably used in that the separation performance of components in the raw fluid is excellent. These separation functional layers can be formed by polycondensation of monomers on the porous support layer.

  For example, the separation functional layer can contain polyamide as a main component. Such a film is formed by interfacial polycondensation of a polyfunctional amine and a polyfunctional acid halide by a known method. For example, by applying a polyfunctional amine aqueous solution to the porous support layer, removing the excess amine aqueous solution with an air knife or the like, and then applying an organic solvent solution containing a polyfunctional acid halide, the polyamide separation functional layer Is obtained.

Further, the separation functional layer may have an organic-inorganic hybrid structure containing Si element or the like. Examples of the separation functional layer having an organic-inorganic hybrid structure include the following compounds (A) and (B):
(A) a silicon compound in which a reactive group and a hydrolyzable group having an ethylenically unsaturated group are directly bonded to a silicon atom, and (B) a compound other than the compound (A) and having an ethylenically unsaturated group Compounds can be included. Specifically, the separation functional layer may contain a condensate of the hydrolyzable group of the compound (A) and a polymer of the ethylenically unsaturated group of the compounds (A) and / or (B). That is, the separation functional layer is
A polymer formed by condensation and / or polymerization of only the compound (A),
-The polymer formed by superposing | polymerizing only a compound (B), and-At least 1 sort (s) of polymer of the copolymer of a compound (A) and a compound (B) can be contained. The polymer includes a condensate. In the copolymer of the compound (A) and the compound (B), the compound (A) may be condensed through a hydrolyzable group.

  The hybrid structure can be formed by a known method. An example of a method for forming a hybrid structure is as follows. A reaction solution containing the compound (A) and the compound (B) is applied to the porous support layer. In order to condense the hydrolyzable group after removing the excess reaction solution, heat treatment may be performed. As a polymerization method of the ethylenically unsaturated groups of the compound (A) and the compound (B), heat treatment, electromagnetic wave irradiation, electron beam irradiation, and plasma irradiation may be performed. For the purpose of increasing the polymerization rate, a polymerization initiator, a polymerization accelerator and the like can be added during the formation of the separation functional layer.

  For any separation functional layer, the surface of the membrane may be hydrophilized with an alcohol-containing aqueous solution or an alkaline aqueous solution, for example, before use.

<Porous support layer>
The porous support layer is a layer that supports the separation functional layer, and is also referred to as a porous resin layer.

  Although the material used for a porous support layer and its shape are not specifically limited, For example, you may form on a board | substrate with porous resin. As the porous support layer, polysulfone, cellulose acetate, polyvinyl chloride, epoxy resin or a mixture and laminate of them is used, and polysulfone with high chemical, mechanical and thermal stability and easy to control pore size. Is preferably used.

  The porous support layer gives mechanical strength to the separation membrane, and does not have separation performance like a separation membrane for components having a small molecular size such as ions. The pore size and pore distribution of the porous support layer are not particularly limited. For example, the porous support layer may have uniform and fine pores, or the side on which the separation functional layer is formed. It may have a pore size distribution such that the diameter gradually increases from the surface to the other surface. In any case, the projected area equivalent circle diameter of the pores measured using an atomic force microscope or an electron microscope on the surface on the side where the separation functional layer is formed is 1 nm or more and 100 nm or less. preferable. In particular, in terms of interfacial polymerization reactivity and retention of the separation functional layer, the pores on the surface of the porous support layer on the side where the separation functional layer is formed preferably have a projected area equivalent circle diameter of 3 to 50 nm.

  The thickness of the porous support layer is not particularly limited, but is preferably in the range of 20 μm to 500 μm, more preferably 30 μm to 300 μm, for reasons such as giving strength to the separation membrane.

  The form of the porous support layer can be observed with a scanning electron microscope, a transmission electron microscope, or an atomic microscope. For example, when observing with a scanning electron microscope, after peeling off the porous support layer from the substrate, it is cut by the freeze cleaving method to obtain a sample for cross-sectional observation. The sample is thinly coated with platinum, platinum-palladium, or ruthenium tetrachloride, preferably ruthenium tetrachloride, and observed with a high-resolution field emission scanning electron microscope (UHR-FE-SEM) at an acceleration voltage of 3 to 6 kV. A Hitachi S-900 electron microscope or the like can be used as the high-resolution field emission scanning electron microscope. Based on the obtained electron micrograph, the film thickness of the porous support layer and the projected area equivalent circle diameter of the surface can be measured.

  The thickness and pore diameter of the porous support layer are average values, and the thickness of the porous support layer is measured at intervals of 20 μm in a direction perpendicular to the thickness direction by cross-sectional observation, and is an average value of 20 points. Moreover, a hole diameter is an average value of each projected area circle equivalent diameter measured about 200 holes.

  Next, a method for forming the porous support layer will be described. For example, the porous support layer is prepared by pouring an N, N-dimethylformamide (hereinafter referred to as DMF) solution of the above polysulfone into a constant thickness on a substrate to be described later, for example, a densely woven polyester cloth or non-woven cloth. It can be produced by molding and wet coagulating it in water.

  The porous support layer is “Office of Saleen Water Research and Development Progress Report” no. 359 (1968). In addition, in order to obtain a desired form, the polymer concentration, the temperature of the solvent, and the poor solvent can be adjusted.

  For example, a predetermined amount of polysulfone is dissolved in DMF to prepare a polysulfone resin solution having a predetermined concentration. Next, this polysulfone resin solution is applied to a substrate made of polyester cloth or nonwoven fabric to a substantially constant thickness, and after removing the surface solvent in the air for a certain period of time, the polysulfone is coagulated in the coagulation liquid. Can be obtained.

<Base material>
From the viewpoint of the strength and dimensional stability of the separation membrane body, the separation membrane body may have a substrate. As the base material, it is preferable to use a fibrous base material in terms of strength, unevenness forming ability and fluid permeability.

  As a base material, both a long fiber nonwoven fabric and a short fiber nonwoven fabric can be used preferably. In particular, since the long fiber nonwoven fabric has excellent film-forming properties, when the polymer solution is cast, the solution penetrates through the permeation, the porous support layer peels off, and Can suppress the film from becoming non-uniform due to fluffing of the substrate and the like, and the occurrence of defects such as pinholes. In addition, since the base material is made of a long-fiber non-woven fabric composed of thermoplastic continuous filaments, compared to short-fiber non-woven fabrics, it suppresses the occurrence of non-uniformity and film defects caused by fiber fluffing during casting of a polymer solution. be able to. Furthermore, since the separation membrane is tensioned in the film-forming direction when continuously formed, it is preferable to use a long-fiber nonwoven fabric excellent in dimensional stability as a base material.

  In the long-fiber nonwoven fabric, in terms of moldability and strength, it is preferable that the fibers in the surface layer on the side opposite to the porous support layer have a longitudinal orientation than the fibers in the surface layer on the porous support layer side. According to such a structure, not only a high effect of preventing membrane breakage by maintaining strength is realized, but also a laminate comprising a porous support layer and a substrate when imparting irregularities to the separation membrane The moldability is improved, and the uneven shape on the surface of the separation membrane is stabilized, which is preferable.

  More specifically, the fiber orientation degree in the surface layer on the side opposite to the porous support layer of the long fiber nonwoven fabric is preferably 0 ° to 25 °, and the fiber orientation degree in the surface layer on the porous support layer side. And the orientation degree difference is preferably 10 ° to 90 °.

  The separation membrane manufacturing process and the element manufacturing process include a heating process, but a phenomenon occurs in which the porous support layer or the separation functional layer contracts due to the heating. In particular, the shrinkage is remarkable in the width direction where no tension is applied in continuous film formation. Since shrinkage causes problems in dimensional stability and the like, a substrate having a small rate of thermal dimensional change is desired. In the nonwoven fabric, when the difference between the fiber orientation degree on the surface layer opposite to the porous support layer and the fiber orientation degree on the porous support layer side surface layer is 10 ° to 90 °, the change in the width direction due to heat is suppressed. Can also be preferred.

  Here, the fiber orientation degree is an index indicating the direction of the fibers of the nonwoven fabric substrate constituting the porous support layer. Specifically, the fiber orientation degree is an average value of angles between the film forming direction when continuous film formation is performed, that is, the longitudinal direction of the nonwoven fabric base material, and the fibers constituting the nonwoven fabric base material. That is, if the longitudinal direction of the fiber is parallel to the film forming direction, the fiber orientation degree is 0 °. If the longitudinal direction of the fiber is perpendicular to the film forming direction, that is, if it is parallel to the width direction of the nonwoven fabric substrate, the degree of orientation of the fiber is 90 °. Accordingly, the closer to 0 ° the fiber orientation, the longer the orientation, and the closer to 90 °, the lateral orientation.

  The degree of fiber orientation is measured as follows. First, 10 small piece samples are randomly collected from the nonwoven fabric. Next, the surface of the sample is photographed at 100 to 1000 times with a scanning electron microscope. In the photographed image, 10 samples are selected for each sample, and the angle when the longitudinal direction (longitudinal direction, film forming direction) of the nonwoven fabric is 0 ° is measured. That is, the angle is measured for a total of 100 fibers per nonwoven fabric. An average value is calculated from the angles of 100 fibers thus measured. The value obtained by rounding off the first decimal place of the obtained average value is the fiber orientation degree.

  The thickness of the base material is set so that the total thickness of the base material and the porous support layer is within a range of 0.03 to 0.3 mm, or within a range of 0.05 to 0.25 mm. Is preferred.

(1-3) Permeation-side channel material A channel material is provided on the permeation-side surface of the separation membrane main body so as to form a permeation-side channel. “Provided to form a flow path on the permeate side” means that the permeated fluid that has permeated through the main body of the separation membrane can reach the water collecting pipe when the separation membrane is incorporated in a separation membrane element described later. It means that the road material is formed.

  The channel material 3 is preferably formed of a material different from that of the separation membrane body 2. The different material means a material having a composition different from that of the material used in the separation membrane body 2. In particular, the composition of the flow path member 3 is preferably different from the composition of the surface of the separation membrane body 2 on which the flow path material 3 is formed, and is different from the composition of any layer forming the separation membrane body 2. It is preferable.

  Although it does not specifically limit as a component which comprises a flow-path material, Resin is used preferably. Specifically, from the viewpoint of chemical resistance, polyolefins such as ethylene vinyl acetate copolymer resin, polyethylene, and polypropylene, and copolymerized polyolefins are preferable, and polymers such as urethane resins and epoxy resins can be selected. It can be used as a mixture comprising two or more types. In particular, since a thermoplastic resin is easy to mold, a channel material having a uniform shape can be formed.

  Such a channel material is preferably discontinuous at least in the width direction in that a channel on the permeate side is formed. “Discontinuous” refers to a structure in which a plurality of flow path materials 3 are separated from each other when the flow path material 3 is separated from the separation membrane body 2. On the other hand, members such as nets, tricots, and films have a continuous shape even when separated from the separation membrane body 2.

  The separation membrane is preferably arranged in the separation membrane element such that the first direction coincides with the winding direction. That is, in the separation membrane element, the separation membrane is preferably arranged so that the width direction is parallel to the longitudinal direction of the water collecting pipe 9 and the first direction is orthogonal to the longitudinal direction of the water collecting pipe 9.

  In the example shown in FIG. 1, the flow path material 3 is provided discontinuously in the width direction, and is provided so as to be continuous from one end to the other end of the separation membrane body 2 in the first direction. That is, when the separation membrane is incorporated in the separation membrane element as shown in FIG. 3, the flow path material 3 in FIG. 2 is arranged so as to continue from the inner end to the outer end of the separation membrane 1 in the winding direction. Is done. The inner side in the winding direction is the side close to the water collecting pipe in the separation membrane, and the outer side in the winding direction is the side far from the water collecting pipe in the separation membrane.

  The shape of the channel material is not particularly limited, but a shape that reduces the flow resistance of the channel and stabilizes the channel when permeated can be selected. In these respects, in any cross section perpendicular to the surface direction of the separation membrane, the shape of the flow path material may be a straight column shape, a trapezoidal shape, a curved column shape, or a combination thereof.

  For example, when the cross-sectional shape of the channel material is trapezoidal, if the difference between the lengths of the upper and lower bases is too large, membrane drop during pressure filtration tends to occur in the wider groove width. The ratio of the length of the upper base to the length is preferably 0.6 or more and 1.4 or less, and more preferably 0.8 or more and 1.2 or less.

  The shape of the channel material is preferably a straight column shape perpendicular to the separation membrane surface described later from the viewpoint of reducing flow resistance. Further, the channel material may be formed so that the width becomes smaller at a higher location, or conversely, the channel material may be formed so that the width becomes wider at a higher location, or the height from the surface of the separation membrane. Regardless, it may be formed to have the same width.

  However, the upper side of the cross-section of the flow path material may be rounded as long as the flow path material is not significantly crushed during pressure filtration.

  If the flow path material is a thermoplastic resin, the shape of the flow path material can be freely changed to satisfy the required separation characteristics and permeation performance conditions by changing the processing temperature and the type of thermoplastic resin to be selected. Can be adjusted.

  Further, the shape of the separation membrane of the flow path material in the planar direction may be, for example, a straight line as shown in FIG. 1, a curved line, or a wavy line.

  Further, when the shape of the separation membrane of the flow path material in the planar direction is a straight line, the adjacent flow path materials may be arranged substantially parallel to each other. “Disposed substantially in parallel” means, for example, that the channel material does not need to intersect on the separation membrane, and preferably the angle formed by the longitudinal direction of two adjacent channel materials is 0 ° or more and 30 ° or less. More preferably, the angle is 0 ° to 15 °, and more preferably the angle is 0 ° to 5 °.

  Further, the angle formed by the longitudinal direction of the flow path material and the longitudinal direction of the water collecting pipe is preferably 60 ° or more and 120 ° or less, more preferably 75 ° or more and 105 ° or less, and 85 ° or more and 95 °. More preferably, it is as follows. When the angle formed by the longitudinal direction of the flow path material and the longitudinal direction of the water collecting pipe is within the above range, the permeated water is efficiently collected in the water collecting pipe.

  In order to stably form the flow path, it is preferable that the separation membrane body can be prevented from dropping when the separation membrane body is pressurized in the separation membrane element. For this purpose, it is preferable that the contact area between the separation membrane main body and the flow path material is large, that is, the area of the flow path material relative to the area of the separation membrane main body (projected area on the membrane surface of the separation membrane main body) is large. On the other hand, in order to reduce pressure loss, it is preferable that the cross-sectional area of a flow path is wide. The cross-sectional shape of the flow path is a concave lens shape in order to ensure a large contact area between the separation membrane body perpendicular to the longitudinal direction of the flow path and the flow path material and a wide cross-sectional area of the flow path. Preferably there is. Further, the flow path member 3 may have a straight column shape having no change in width in a cross-sectional shape in a direction perpendicular to the winding direction. Moreover, as long as the separation membrane performance is not affected, the cross-sectional shape in the direction perpendicular to the winding direction has a trapezoidal wall-like object having a change in width, an elliptic cylinder, an elliptic cone, four A shape like a pyramid or a hemisphere may be sufficient.

  The method for forming the flow path material 3 is not particularly limited, but for example, a flow path material having a predetermined height difference and width can be obtained by using a gravure roll engraved with a predetermined uneven shape. In addition, a method of arranging the material constituting the permeation side flow path material directly on the permeation side of the separation membrane by printing, spraying, applicator application, hot melt processing or the like is used.

  If the height difference between the flow path material 3 and the separation membrane body base material side surface is large, the flow resistance of the permeation side flow path is reduced, but the enveloping membrane area is reduced. If it is small, the membrane area that can be surrounded increases, but the flow resistance of the permeate-side channel increases. The height difference between the flow path member 3 and the separation membrane body base material side surface is preferably 10 μm or more and 800 μm or less, and more preferably 200 μm or more and 400 μm or less. Within these ranges, a stable permeate flow path can be secured.

  In the present embodiment, the thickness of the permeate side channel material on the first end side in the length direction of the separation membrane is formed to be larger than the thickness of the permeate side channel material on the second end side. Further, in the element, the separation membrane is arranged so that the thick side is the inner side in the winding direction.

  Since the permeated water of the separation membrane moves so as to be collected in the water collecting pipe, the flow rate of the permeated fluid is larger on the inner side in the winding direction than on the outer side. As a result, the flow resistance tends to increase on the inner side in the winding direction. Therefore, if the thickness of the flow path material is large on the inner side in the winding direction, the height difference between the apex of the flow path material and the surface of the separation membrane main body increases, and as a result, the cross-sectional area of the flow path increases, The flow resistance inside the direction is reduced. On the other hand, since the flow rate of the permeating fluid is small on the outer side in the winding direction, the flow resistance is hardly increased even if the height difference is small.

  In addition, since the separation membrane in which the flow path material made of a different material from the separation membrane main body is installed on the permeation side surface of the separation membrane has higher rigidity than the separation membrane main body, especially when the element is surrounded, It becomes difficult to enclose easily on the inner side in the winding direction where the curvature is high.

  In addition, since the permeation-side channel material is thicker on the inner side in the winding direction than on the outer side, the curve of the separation membrane at the time of winding becomes loose, so that there is an advantage that winding can be performed easily.

  The thickness of the flow path member 3 indicates the difference in height between the surface of the separation membrane on the base material side and the highest portion of the flow path material 3 and does not include the thickness of the portion impregnated in the base material. .

“The thickness of the permeate-side channel material on the first end side in the length direction of the separation membrane is larger than the thickness of the permeate-side channel material on the second end side”
(I) When the projection image of the flow path material 3 on a plane perpendicular to the film surface and parallel to the film length direction is divided by a straight line that bisects the flow path material in the length direction, The area of the region A is larger than the area of the region B on the second end side, and (ii) the thickness of the flow path material 3 at the first end is compared with the thickness of the flow path material 3 at the second end. Sometimes the thickness at the first end is large,
It is sufficient to satisfy at least one of the following.

  Examples of the form (i) include the forms shown in FIGS. 5, 6, 7, 8, and 10. Examples of the form (ii) include FIGS. 5, 6, 7, 8, 9, and 10. FIG.

  The channel material may be discontinuous in the length direction. As a form of such a flow path material, the form obtained by dividing the flow path material of FIG. 5 to FIG. 12 into a plurality of portions in the length direction, for example. That is, it is only necessary that a series of flow path materials arranged in the length direction satisfy the above condition (i) as a whole. In addition, among the series of flow path materials arranged in the length direction, the flow path material disposed closest to the first end is formed thicker than the flow path material disposed closest to the second end. Then, the series of flow path materials satisfies the above condition (ii).

  The thickness of the flow path member 3 may increase monotonically from the second end to the first end in the length direction. “Monotonically increasing” is a graph obtained by plotting the thickness of the channel material against the distance from the second end in the length direction (a line indicating the upper surface of the channel material in the yz plane in the figure). It indicates that the thickness does not decrease, that is, the slope does not become negative. Therefore, in the graph in which the thickness is plotted with respect to the distance from the second end as in the form shown in FIG. 5, when the thickness increases with a constant inclination with respect to the distance; the inclination increases as shown in FIG. 6. And the case where the thickness increases stepwise as shown in FIG. 8 is included in the “monotonically increasing” form. As the thickness increases monotonously in this way, the surrounding becomes easier. In particular, as shown in FIG. 5 or FIG. 6, it is preferable that the thickness gradient with respect to the distance from the second end is always greater than zero.

  In addition, the thickness of the flow path material may include one or more inflection points as long as the effects of the present invention are not impaired. That is, there may be a portion where the thickness gradient with respect to the distance from the second end is negative.

  Moreover, it is preferable that the location where the thickness of the flow path member 3 is maximum in the length direction of the separation membrane is within 30% from the one end in the length direction of the separation membrane with respect to the length direction. When the portion having the maximum thickness is within 30% from one end, the flow resistance can be greatly reduced when the separation membrane element is formed. More preferably, it is within 15%, more preferably within 5%.

  The difference between the maximum value and the minimum value of the thickness of the flow path material 3 in the length direction of the separation membrane is preferably 1 μm or more and 600 μm or less. If it is this range, even if the thickness of the flow-path material 3 differs in a length direction, inconvenience does not arise in manufacture of a separation membrane element and an operation | movement. When the difference is 600 μm or less, even when the operation is repeated, the separation membrane body and the adhesive are unlikely to peel off at the adhesion portion between the permeation sides of the separation membrane, and the degradation of the separation membrane element performance can be suppressed. .

The thickness of the flow path member 3 can be continuously measured by using a commercially available thickness measuring device, for example, in the lengthwise distribution in increments of 100 μm.

The interval b of the flow path material 3 corresponds to the width of the flow path 5. When the interval is large, the flow path becomes wide, and there is an advantage that the pressure loss becomes small. On the other hand, if the interval is small, there is an advantage that film drop hardly occurs. From these balances, the interval is preferably 200 to 1500 μm. If it is within this range, it is possible to prevent the film from dropping and to reduce the pressure loss. More preferably, it is 300-1000 micrometers, More preferably, it is 400-800 micrometers.

  When the width d of the flow path material 3 is large, the shape of the flow path material can be maintained even when pressure is applied to the flow path material 3 during operation of the separation membrane element, and the permeation side flow path is stably formed. . If it is small, the width of the flow path for the permeating fluid becomes relatively large, and the flow velocity of the permeating fluid can be reduced, so that the flow resistance can be reduced. The width is preferably 10 μm or more and 1000 μm or less. When the width is 1000 μm or less, a sufficient flow path on the permeation side can be secured.

  The channel material 3 is provided substantially parallel to the length direction. Further, when the sum of the distance b between the flow path materials 3 and the width d of the flow path materials 3 is substantially constant, the distance b between the adjacent flow path materials 3 decreases as the width d of the flow path materials 3 increases. When the width d of the flow path material 3 is reduced, the width d of the adjacent flow path material 3 is increased. That is, if the width d of the flow path material 3 is reduced and the interval b between the adjacent flow path materials 3 is increased, the flow path is increased and the flow resistance is reduced, but the shape retaining property against pressure is lowered.

  In the separation membrane element of the present embodiment, the width of the flow path material 3 on the first end side in the length direction of the separation membrane may be smaller than the width on the second end side. That is, when the separation membrane element is wrapped, the width inside of the flow path material may be smaller on the outer side in the winding direction. By doing so, the space | interval b of the adjacent flow-path material 3 becomes larger inside the winding direction outer side, and the inner area | region where there is much flow volume of a permeated fluid, maintaining the shape retainability with respect to the pressure of a flow-path material. The flow resistance can be reduced.

  Examples of such configurations are shown in FIGS. 11 and 12. 11 and 12, the width of the flow path material monotonously increases from the first end to the second end. Further, in FIG. 11, the width of the flow path material gradually changes from the first end to the second end, and in FIG. 12, the width of the flow path material changes in a step shape.

  For the interval b of the channel material 3, the average value of the maximum value and the minimum value of the width of one channel 5 is measured in one cross section at a certain position in the width direction of the separation membrane, and the average value is calculated. As shown in FIG. 2, in the cross section perpendicular to the length direction, when the channel material 3 has a trapezoidal shape with a thin top and a thick bottom, first, the distance between the upper parts of the two adjacent channel materials 3 and the lower part The distance between them is measured and the average value is calculated. In each cross-section of the section equally divided into 30 in the length direction of the separation membrane, the distance between the flow path materials 3 is measured to calculate this average value, and the arithmetic average value of the values of the inner 15 positions and the outer 15 positions is calculated. To do.

  For the width d of the flow path material 3, the average value of the maximum width and the minimum width of one flow path material 3 is calculated within one cross section at a certain position in the width direction of the separation membrane. That is, in the channel material 3 having a thin upper part and a thick lower part as shown in FIG. 2, the width of the lower part and the upper part of the channel material are measured and the average value is calculated. In each cross section of the portion equally divided into 30 in the length direction of the separation membrane, the width of the flow path material 3 is measured to calculate the average value, and the arithmetic average value of the values of the inner 15 locations and the outer 15 locations is calculated. To do.

  The interval b and the width d of the transmission side flow path material 3 can be measured with a microscope or the like.

  The thickness, width, and shape of the flow path material 3 provided on the permeate side can be determined by, for example, engraving a gravure roll into a predetermined shape, hot melt processing method, processing temperature, hot melt resin, and clearance. By changing the discharge amount, etc., it is possible to freely adjust so as to satisfy the required separation characteristics and permeation performance conditions.

  When the flow path material 3 provided on the permeate side is incorporated into the separation membrane element, the permeate flow path is provided from one end of the separation membrane 1 to the other end in order to obtain a good recovery rate of the permeate You may provide so that it may continue. As an example of such a configuration, the flow path 5 is formed continuously in the length direction. Such a flow path 5 is formed by discontinuously arranging a plurality of flow path materials 3 in the width direction.

  Since the conventional channel material such as a tricot is knitted, the entire height difference cannot be used as a groove. However, in the channel material 3, all the height differences can be used as a channel groove. Even if the thickness of the flow path material 3 is the same, the flow path in the thickness direction becomes wider and the pressure loss becomes smaller, so the amount of water produced by the separation membrane element increases.

  The channel material 3 may be impregnated with the components of the channel material 3 in the separation membrane, more specifically in the base material. When the flow path material 3 is arranged on the base material side of the separation membrane, that is, the permeation side, the impregnation of the flow path material 3 proceeds from the back side to the front side of the separation membrane. As the impregnation progresses, the adhesion between the flow path material 3 and the base material becomes stronger, and the flow path material 3 becomes difficult to peel off from the base material even by pressure filtration.

  However, if the components of the flow path material 3 penetrate into the base material and are impregnated to the vicinity of the separation functional layer of the porous support layer, the impregnated flow path material 3 breaks the separation functional layer when pressure filtered. There are things to do. Therefore, when the component of the channel material 3 is impregnated in the base material, the ratio of the thickness of the channel material impregnation to the thickness of the base material (that is, the impregnation rate) is preferably in the range of 5 to 95%. A range of 10 to 80% is more preferable, and a range of 20 to 60% is more preferable. The impregnation thickness means the maximum value of the thickness of the impregnation portion corresponding to one flow path material 3 in one cross section.

  The impregnation thickness of the flow path material 3 can be adjusted by changing the type of material (more specifically, the type of resin) and / or the amount of material constituting the flow path material 3, for example.

  In addition, if the peak resulting from the component of the flow-path material 3 is obtained separately from a base material by providing the base material containing the impregnation part of the flow-path material 3 to thermal analysis called differential scanning calorimetry, the flow-path material 3 It can be confirmed that the substrate is impregnated.

  The rate of impregnation of the channel material 3 into the base material is determined by observing the cross section of the separation membrane where the channel material 3 is present with a scanning electron microscope, a transmission electron microscope, or an atomic force microscope. And the substrate thickness can be calculated. For example, when observing with a scanning electron microscope, the separation membrane is cut in the depth direction together with the flow path material 3, and the cross section is observed with a scanning electron microscope to measure the impregnation thickness and the substrate thickness. And it can calculate from the ratio of the maximum impregnation thickness which the flow-path material has most impregnated with the base material, and the base material thickness. The “base material thickness” when calculating the impregnation depth is the thickness of the base material corresponding to the portion where the maximum impregnation thickness is measured.

[2. Separation membrane element)
(2-1) Overview As shown in FIG. 3, the separation membrane element 100 includes the water collecting pipe 9 and any of the above-described configurations, and includes the separation membrane 1 wound around the water collecting pipe 9. The separation membrane element 100 further includes a member such as an end plate (not shown).

(2-2) Separation membrane The separation membrane 1 is wound around the water collecting pipe 9 and is arranged so that the width direction is along the longitudinal direction of the water collecting pipe 9. As a result, the separation membrane 1 is disposed such that the length direction is along the winding direction.

  Therefore, the flow path member 3 is discontinuously disposed at least in the longitudinal direction of the water collecting pipe 9 on the permeation side surface 22 of the separation membrane 1. That is, the flow path 5 is formed to be continuous from the outer end to the inner end of the separation membrane in the winding direction. As a result, the permeated water can easily reach the central pipe, that is, the flow resistance is reduced, so that a large amount of fresh water is obtained.

  “Inside in the winding direction” and “Outside in the winding direction” are as shown in FIG. That is, the “inner end in the winding direction” and the “outer end in the winding direction” correspond to the end closer to the water collection tube 9 and the far end in the separation membrane 1, respectively.

  As described above, since the flow path material does not have to reach the edge of the separation membrane, for example, at the outer end of the envelope membrane in the winding direction and the end of the envelope membrane in the longitudinal direction of the water collecting pipe, The channel material may not be provided.

  As shown in FIG. 4, the separation membrane forms a leaf. A leaf is a set of two separation membranes cut to a length that facilitates winding. In the leaf, the separation membrane 1 supply-side surface 21 is disposed so as to face the supply-side surface 71 of another separation membrane 7 with the supply-side flow path member 6 interposed therebetween. In the separation membrane element 100, a supply-side flow path is formed between the supply-side surfaces of the separation membranes facing each other, and a permeation-side flow path is formed between the permeation-side surfaces.

  Further, the leaf 4 is overlapped so that the separation membrane 1 and the separation membrane 7 of the other leaf 4 facing the permeation side surface 22 of the separation membrane 1 form an envelope-like membrane. In the envelope-shaped membrane, between the opposite permeate side surfaces, in the rectangular shape of the separation membrane, only one side inside the winding direction is opened, and the other three sides are sealed so that the permeate flows into the water collecting pipe 9. Stopped. The permeate is isolated from the supply water by this envelope membrane.

  Examples of the sealing include a form bonded by an adhesive or hot melt, a form fused by heating or laser, and a form in which a rubber sheet is sandwiched. Sealing by adhesion is particularly preferable because it is the simplest and most effective.

  In addition, on the surface on the supply side of the separation membrane, the inner end in the winding direction is closed by folding or sealing. Since the supply side surface of the separation membrane is sealed rather than folded, bending at the end of the separation membrane hardly occurs. By suppressing the occurrence of bending in the vicinity of the crease, the generation of voids between the separation membranes and the occurrence of leaks due to the voids are suppressed when wound.

  Note that the separation membranes facing each other may have the same configuration or different configurations. That is, in the separation membrane element, at least one of the two permeate-side surfaces facing each other only needs to be provided with the above-described permeation-side flow path material, and therefore the separation membrane element does not include the permeation-side flow path material. Separation membranes may be alternately stacked. However, for convenience of explanation, in the separation membrane element and the explanation related thereto, the “separation membrane” includes a separation membrane that does not include the permeate-side flow path material (for example, a membrane that has the same configuration as the separation membrane main body).

  The separation membranes facing each other on the permeate side surface or the supply side surface may be two different separation membranes, or one membrane folded.

(2-3) Water Collection Pipe In FIG. 3, the water collection pipe 9 only needs to be configured so that permeated water flows therethrough, and the material, shape, size, and the like are not particularly limited. As the water collection pipe 9, for example, a cylindrical member having a side surface provided with a plurality of holes is used.

(2-4) Supply Side Channel Material The separation membrane element may include a supply side channel material arranged so as to face the supply side surface of the separation membrane body. The supply-side flow path material only needs to be formed so as to form a flow path for supplying the raw fluid to the separation membrane main body 2, and in order to suppress the concentration polarization of the raw fluid, the flow of the raw fluid is disturbed. It is preferable to be provided.

  The supply-side channel material may be a member having a continuous shape such as a film or a net, or has a discontinuous shape showing a projected area ratio that is greater than 0 and less than 1 with respect to the separation membrane body. It may be a thing. Further, the supply-side channel material may be a member provided separately from the separation membrane, or may be formed integrally with the separation membrane.

  The material of the supply side channel material is not particularly limited, and may be the same material as the separation membrane or a different material.

  In the supply side flow path, it is important to form the flow path stably, but since the amount of fluid passing therethrough is larger than that of the permeation side flow path, it is most important to reduce the pressure loss. Therefore, the projected area ratio of the supply-side channel material is preferably 0.03 to 0.5, more preferably 0.1 to 0.4, and still more preferably 0.15 to 0.35.

  However, if the height difference on the supply side surface of the separation membrane is too deep, the pressure loss is reduced, but the membrane area that can be filled in the vessel is reduced when the element is formed. If the height difference is small, the pressure loss of the flow path will increase, and the separation characteristics and water permeation performance will deteriorate. Therefore, the fresh water generation capacity of the element is reduced, and the operation cost for increasing the fresh water generation amount is increased. Therefore, in consideration of the balance of each performance and the operating cost described above, in the separation membrane, the difference in height on the supply side surface of the separation membrane may be 80 to 2000 μm, preferably 200 to 1000 μm.

  The difference in height on the supply side surface of the separation membrane can be obtained by the same method as in the case of the above-described difference in height on the permeation side of the separation membrane.

  For the same reason, the groove width is preferably 0.2 mm or more and 10 mm or less, more preferably 0.5 mm or more and 3 mm or less, and the pitch is appropriately designed between 1/10 times and 50 times or less of the groove width. good. The groove width is the part that sinks on the surface where the height difference exists, and the pitch is the horizontal from the highest point of the high part to the highest part of the adjacent high part on the surface where the height difference exists. It is distance.

  The projected area ratio of the portion that becomes convex by embossing is preferably 0.03 or more and 0.5 or less, more preferably 0.10 or more and 0.40, for the same reason as in the case of the supply-side channel material. Hereinafter, it is particularly preferably 0.15 or more and 0.35 or less.

(2-5) Permeation side flow path As described above, the permeation side flow path is formed by the permeation side flow path material provided on the separation membrane main body.

[3. Method for manufacturing separation membrane element]
A conventional element manufacturing apparatus can be used for manufacturing the separation membrane element. In addition, as an element manufacturing method, a method described in a reference (Japanese Patent Publication No. 44-14216, Japanese Patent Publication No. 4-11928, Japanese Patent Laid-Open No. 11-226366) can be used. Details are as follows.

(3-1) Manufacture of separation membrane body The manufacturing method of the separation membrane body has been described above, but it is summarized as follows.

  The resin is dissolved in a good solvent, and the resulting resin solution is cast on a substrate and immersed in pure water to combine the porous support layer and the substrate. Thereafter, as described above, a separation functional layer is formed on the porous support layer. Furthermore, chemical treatment such as chlorine, acid, alkali, nitrous acid, etc. is performed to enhance separation performance and permeation performance as necessary, and the monomer is washed to produce a continuous sheet of the separation membrane body.

(3-2) Arrangement of supply-side flow path material When the supply-side flow path material is a continuously formed member such as a net, supply is performed by overlapping the separation membrane and the supply-side flow path material. A side flow path can be formed.

  Moreover, the supply side channel material which has a discontinuous or continuous shape can be formed by apply | coating resin directly to a separation membrane. Even when the supply side flow path member is fixed to the separation membrane main body, the arrangement of the supply side flow path material may be regarded as a part of the method of manufacturing the separation membrane.

  Moreover, you may form a flow path by carrying out uneven | corrugated processing of the separation membrane main body. Examples of the concavo-convex processing method include methods such as embossing, hydraulic forming, and calendering. The embossing conditions, the embossed shape, and the like can be changed according to the required performance of the separation membrane element. This concavo-convex processing may be regarded as a part of the method for manufacturing the separation membrane.

(3-3) Formation of Permeation-side Channel As described above, the permeation-side channel is formed by the permeation-side channel material provided on the separation membrane main body. The method for arranging the flow path material is not particularly limited, but roll type coater, nozzle type hot melt applicator, spray type hot melt applicator, flat nozzle type hot melt applicator, gravure method, extrusion type coater, printing, spraying, etc. Can be used.

  The permeate-side channel material is formed and arranged so that the side with the large height difference between the permeate-side channel material and the base material side surface of the separation membrane main body is the inner side in the winding direction of the separation membrane.

(3-4) Lamination and winding of separation membranes Folding and bonding one separation membrane so that the permeation side faces inward, or stacking two separation membranes so that the permeation side faces inward By attaching them together, an envelope-like film is formed. As described above, the envelope film is sealed on three sides. Sealing can be performed by bonding with an adhesive or hot melt, or by fusion with heat or laser.

  The adhesive used for forming the envelope-shaped film preferably has a viscosity in the range of 40 PS to 150 PS, more preferably 50 PS to 120 PS. When wrinkles occur in the separation membrane, the performance of the separation membrane element may deteriorate, but when the adhesive viscosity is 150 PS or less, wrinkles are less likely to occur when the separation membrane is wrapped around the water collection pipe. . Moreover, when the adhesive viscosity is 40 PS or more, the outflow of the adhesive from between the separation membranes is suppressed, and the risk that the adhesive adheres to unnecessary portions is reduced.

  The amount of the adhesive applied is preferably such that the width of the portion to which the adhesive is applied after the separation membrane is wound around the water collecting pipe is 10 mm or more and 100 mm or less. As a result, the separation membrane is securely bonded, and the inflow of the raw fluid to the permeate side is suppressed. Also, a relatively large effective membrane area can be secured.

  The adhesive is preferably a urethane-based adhesive, and the main component isocyanate and the curing agent polyol are mixed in a ratio of isocyanate: polyol = 1: 1 to 1: 5 in order to make the viscosity in the range of 40 PS to 150 PS. The ones made are preferred. The viscosity of the adhesive is measured with a B-type viscometer (JIS K 6833) by measuring the viscosity of the main agent, the curing agent alone, and a mixture in which the blending ratio is defined in advance.

  The separation membrane thus coated with the adhesive is arranged so that the closed portion of the envelope-like membrane is located on the inner side in the winding direction, and the separation membrane is wound around the water collecting pipe. Thus, the separation membrane is wound in a spiral shape.

(3-5) Other steps The method of manufacturing a separation membrane element may include further winding a film, a filament, and the like around the outer periphery of the wound membrane of the separation membrane formed as described above. Further steps such as edge cutting for aligning the end of the separation membrane in the longitudinal direction of the water collecting pipe, attachment of an end plate, and the like may be included.

4). Use of Separation Membrane Element The raw fluid supplied to the separation membrane element 100 is supplied to the surface 21 on the supply side of the separation membrane 1. When a part of the raw fluid permeates the separation membrane 1, the raw fluid is separated into a permeated fluid and a concentrated fluid. The permeated fluid flows inside the envelope-shaped membrane, that is, between the two permeate-side surfaces 22 facing each other, and reaches the water collecting pipe 9. The permeated fluid that has flowed through the water collection pipe 9 is discharged from the end of the water collection pipe 9 to the outside of the separation membrane element 100. The concentrated fluid flows between the two supply-side surfaces 21 facing each other and flows out from the end of the separation membrane element 100.

  The separation membrane element can be used as a separation membrane module by being connected in series or in parallel and housed in a pressure vessel.

  In addition, the separation membrane element and module described above can be combined with a pump that supplies fluid to them, a device that pretreats the fluid, and the like to form a fluid separation device. By using this separation device, for example, raw water can be separated into permeated water such as drinking water and concentrated water that has not permeated through the membrane, and water suitable for the purpose can be obtained.

  The higher the operating pressure of the fluid separator, the better the salt removal, but the energy required for operation also increases, and considering the durability of the composite semipermeable membrane, water to be treated is added to the composite semipermeable membrane. The operating pressure at the time of permeation is preferably 0.2 MPa or more and 5 MPa or less. The operating pressure is a so-called transmembrane pressure. As the feed water temperature increases, the salt removability decreases, but as it decreases, the membrane permeation flux also decreases. In addition, when the pH of the feed water becomes high, scales such as magnesium may be generated in the case of feed water with a high salt concentration such as seawater, and there is a concern about deterioration of the membrane due to high pH operation. Is preferred.

Examples of raw water to be treated by the composite semipermeable membrane include liquid mixtures containing TDS (Total Dissolved Solids) of 500 mg / L to 100 g / L, such as seawater, brine, and drainage. Generally, TDS refers to the total amount of dissolved solids and is expressed as “mass / volume”, or expressed as “weight ratio” by regarding 1 L as 1 kg. According to the definition, the solution filtered with a 0.45 micron filter can be calculated from the weight of the residue by evaporating at a temperature of 39.5 to 40.5 ° C., but more simply converted from practical salt content.

  The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to these examples.

(Thickness of channel material)
The thickness distribution in the length direction of the channel material was measured using a thickness measuring instrument (KG601A). Specifically, while transporting the separation membrane in the length direction at a speed of 1000 μm / s, the permeation-side flow path material at a constant position in the width direction and in increments of 0.1 s (that is, in increments of 100 μm). The thickness was measured. Similarly, the thickness was measured in increments of 0.1 s in the length direction at 10 different positions in the width direction. The distribution of thickness in the length direction was represented by the average value obtained from the measurement results obtained in 10 places.

Furthermore, the average value of the thickness for the number of measurement points obtained in the two regions equally divided into two in the separation membrane length direction is calculated, and the average value of the outer and inner thicknesses in the separation membrane surrounding direction did. The maximum value and the minimum value indicate the maximum value and the minimum value of the thickness in each region. The difference between the larger one of the maximum values and the smaller one of the minimum values in the two regions is shown as the maximum difference.

(Position of the thickest part)
In the height difference between the flow path material and the base material side surface of the separation membrane body, the position with the largest height difference in the membrane length direction extends from the inner side to the outer side in the lengthwise direction, and the position from the inner end is determined. Expressed as a percentage. That is, 0% at the inner end, 50% at the position where the film length is divided into two, and 100% at the outer end.

(Inner projected area ratio)
The projected area ratio of the inner region is that of the flow path material with respect to a plane perpendicular to the film surface and parallel to the film length direction on the inside and outside of the straight line that bisects the length of the flow path material in the film length direction. The area of the projected image is calculated and calculated by (inner area) / ((inner area) + (outer area)). The area of the projected image of the channel material is calculated by integrating the thickness of the channel material calculated by the above method in the film length direction.

(Distance and width of channel material)
Using a scanning electron microscope (S-800) (manufactured by Hitachi, Ltd.), a cross section of an arbitrary transmission side channel material was photographed at a magnification of 500 times. In the photographed photograph, the width of the transmission side channel material and the interval in the width direction were measured. The average value of 15 points in each of the two regions divided equally into 30 in the length direction of the separation membrane and equally divided into two in the length direction of the separation membrane is shown. Furthermore, the maximum value and the minimum value of the width in each region are shown. In addition, the difference between the larger one of the maximum width values and the smaller one of the minimum values in each of the two regions is shown as the maximum difference.

(Long-term driving performance)
The cycle of 3 minutes of operation and 3 minutes of stop is repeated, and is the ratio of the desalting rate between the first time and the 10,000th time, (100- (first desalting rate)) / (100- (10000th desalting rate) )), The smaller the value, the smaller the decrease in the desalination rate.

(Water production)
One day obtained by one separation membrane element when operating under the conditions of an operating pressure of 0.75 MPa and an operating temperature of 25 ° C. using saline with a concentration of 1500 mg / L and pH 6.5 as the feed water The permeated water amount was expressed as a water production amount (m ³ / day).

(Desalination rate (TDS removal rate))
The electric conductivity of the permeated water obtained by the same operation as that for measuring the amount of water produced was measured, and the TDS concentration was calculated. The TDS removal rate was calculated by applying the TDS concentration of the permeated water and the TDS concentration of the feed water to the following equation.
TDS removal rate (%) = 100 × {1− (TDS concentration in permeated water / TDS concentration in feed water)}
Example 1
Non-woven fabric obtained by a papermaking method from polyethylene terephthalate fibers (thread diameter is 1 dtex, thickness: 90 μm, air permeability: 0.9 cc / cm ² / sec, fiber orientation: 40 ° on the porous support layer side surface layer, The surface layer on the opposite side of the porous support layer is 20 °.) A 15.0 wt% DMF solution of polysulfone is cast at a room temperature (25 ° C.) to a thickness of 180 μm and immediately immersed in pure water. Then, a fiber reinforced polysulfone supporting membrane roll having a thickness of 130 μm was produced by allowing it to stand for 5 minutes.

  Thereafter, the support membrane roll is unwound, 1.6% by weight of m-PDA and 4.5% by weight of ε-caprolactam are applied onto the polysulfone surface, and nitrogen is blown from an air nozzle to remove excess aqueous solution from the surface of the support membrane. After removal, an n-decane solution at 25 ° C. containing 0.06% by weight of trimesic acid chloride was applied so that the surface was completely wetted. Then, the excess solution was removed from the membrane by air blow, washed with hot water at 80 ° C., and drained by air blow to obtain a separation membrane roll.

  Next, using a gravure roll engraved with a groove width and a line width of 400 μm and different groove heights in the circumferential direction, an ethylene vinyl acetate copolymer resin (703A) is applied at a resin temperature of 125 ° C. and a running speed of 3 m. The coating was applied to the permeation side surface of the separation membrane main body at / min.

  Permeation that is perpendicular to the longitudinal direction of the water collection pipe and is applied in a straight line from the inner end to the outer end in the winding direction so that the cross-sectional shape parallel to the width direction is trapezoidal. A side channel material was formed. The member thus obtained is referred to as a “wall member” in the table.

  The thickness of the obtained channel material changed linearly in the winding direction as shown in FIG. 5, and was 80 μm at one end and 480 μm at the other end, and the interval and width were constant at 400 μm.

The net (thickness: 800 μm, pitch: 5 mm × 5 mm, fiber diameter: 380 μm, so that the effective area of the separation membrane element is 37 m ² by folding the separation membrane so that the surfaces on the supply side face each other. Twenty-six leaf-shaped objects having a leaf length of 850 mm and a leaf width of 930 mm were produced using a projected area ratio of 0.15) as a supply-side channel material.

  Twenty-six leaf-like materials thus obtained were spirally wound around an ABS water collecting tube (width: 1020 mm, diameter: 30 mm, number of holes 40 × 1 linear line). Furthermore, after winding a film around the outer periphery and fixing with a tape, edge cutting, end plate attachment, and filament winding were performed to produce an 8-inch element.

When this element was put in a pressure vessel and operated under the above-mentioned conditions, the amount of water produced and the desalting rate were 44.9 m ³ / day and 98.5%. The recovery rate of the above operation was 15%.

  Tables 1 and 2 collectively show the element configurations and element performances of the examples and comparative examples.

(Example 2)
A separation membrane element was produced and operated in the same manner as in Example 1 except that the flow path material was formed to have a thickness of 20 μm at the outer end and 540 μm at the inner end. The amount of water produced and the desalting rate were 44.4 m ³ / day and 98.5%.

(Example 3)
As in Example 1, using a gravure roll with different groove heights in the circumferential direction, the film was applied to the permeate side surface of the separation membrane, and the thickness of the obtained flow path material was wound as shown in FIG. It increases monotonically from the outside to the inside.
It changed linearly, and was 160 μm at one end and 400 μm at the other end.

Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 44.8 m ³ / day and 98.5%, respectively.

Example 4
As in Example 1, using a gravure roll with a different groove height in the circumferential direction, the film was applied to the permeate side surface of the separation membrane, and the thickness of the obtained flow path material was wound as shown in FIG. It changed linearly in the direction, 220 μm at one end and 340 μm at the other end.

Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 44.7 m ³ / day and 98.5%, respectively.

(Example 5)
As in Example 1, using the gravure rolls with different groove heights in the circumferential direction, it was applied to the permeation side surface of the separation membrane, and the thickness of the obtained channel material was a curve as shown in FIG. The average thickness of the outer region (region A) when divided into two equal parts in the length direction was 250 μm, and the average thickness of the inner region (region B) was 310 μm.

Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 44.9 m ³ / day and 98.5%, respectively.

(Example 6)
Using a gravure roll having a different groove height at a certain point in the circumferential direction, as in Example 1, it was applied to the permeation side surface of the separation membrane, and the thickness of the obtained flow path material is shown in FIG. Thus, the thickness of the inner region was 380 μm and the thickness of the outer region was 180 μm when equally divided into two in the winding direction. A separation membrane element was produced and operated in the same manner as in Example 1 except that the operating pressure was 0.5 MPa. The amount of water produced and the desalting rate were 29.2 m ³ / day and 98.3%.

(Example 7)
Using a gravure roll engraved with a groove width and a line width of 400 μm and different groove heights in the circumferential direction, it was applied to the permeation side surface of the separation membrane. The thickness of the obtained channel material was as shown in FIG. Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 44.8 m ³ / day and 98.5%.

(Example 8)
Using a gravure roll engraved with a groove width and a line width of 400 μm and different groove heights in the circumferential direction, it was applied to the permeation side surface of the separation membrane. The thickness of the obtained flow path material was as shown in FIG. Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 44.3 m ³ / day and 98.5%.

Example 9
Using a gravure roll engraved so that the groove width and line width change continuously in the circumferential direction and the groove height is different in the circumferential direction, apply to the permeate side surface of the separation membrane. The thickness of the obtained channel material changed linearly in the winding direction as shown in FIG. 5, and was 80 μm at one end and 480 μm at the other end. The width of the flow path material linearly changed in the winding direction as shown in FIG. 11, and was 500 μm at one end and 300 μm at the other end. Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 45.1 m ³ / day and 98.5%.

(Example 10)
Using a gravure roll engraved so that the groove width and line width change at a certain point in the circumferential direction, and the groove height is different in the circumferential direction, it was applied to the permeate side surface of the separation membrane. . The thickness of the obtained channel material changed linearly in the winding direction as shown in FIG. 5, and was 80 μm at one end and 480 μm at the other end. As shown in FIG. 12, the width of the channel material changes in a stepped manner with a certain point as a boundary. The thickness of the outer region when divided equally into two in the first direction is 450 μm, and the thickness of the inner region is 350 μm. there were. Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 45.0 m ³ / day and 98.5%.

(Comparative Example 1)
Using a gravure roll having a groove width and a line width of 400 μm and a groove height of 280 μm, respectively, ethylene vinyl acetate copolymer resin (703A) was passed through the separation membrane body at a resin temperature of 125 ° C. and a running speed of 3 m / min. Applied to the surface. The thickness of the obtained flow path material was 280 μm, and the groove width and line width were 400 μm. Otherwise, the separation membrane element was produced and operated in the same manner as in Example 1. The amount of water produced and the desalting rate were 44.0 m ³ / day and 98.5%.

(Comparative Example 2)
It applied to the permeation | transmission side surface of a separation membrane similarly to Example 1 using the gravure roll from which groove height differs in a certain point of the circumferential direction. As shown in FIG. 13, the thickness of the obtained permeation-side channel material 103 changes in a stepped manner at a certain point, and the thickness of the inner region when equally divided into two in the first direction is 180 μm, The thickness of the outer region was 380 μm. A separation membrane element was produced and operated in the same manner as in Example 1 except that the operating pressure was 0.5 MPa. The amount of water produced and the desalting rate were 28.1 m ³ / day and 98.3%, and the long-term operability was 5.1, and sufficient performance as an element was not obtained.

(Comparative Example 3)
Separation membrane element in the same manner as in Example 1 except that a tricot (thickness: 280 μm, groove width: 200 μm, ridge width: 300 μm, groove depth: 105 μm) having a uniform thickness was used as the permeation side channel material. Preparation and operation were performed. The amount of water produced and the desalting rate were 37.4 m ³ / day and 98.1%.

(Comparative Example 4)
As the permeate-side channel material, a tricot having a thickness of 340 μm, a groove width: 200 μm, a groove width: 300 μm, and a groove depth: 175 μm is used on the outside, and a thickness: 220 μm, groove width: 200 μm, groove width: 300 μm, groove Depth: A separation membrane element was produced and operated in the same manner as in Example 1 except that a tricot having a thickness of 105 μm was used in combination. The amount of water produced and the desalting rate were 37.8 m ³ / day and 98.1%.

  Tables 1 and 2 summarize the results. As can be seen from these results, according to the present invention, the flow resistance on the permeate side can be reduced, and the performance of the separation membrane element can be sufficiently improved.

A 1st end side area
B 2nd end side region 1,7 Separation membrane 2 Separation membrane body 3, 103 Permeation side flow path material 4 Separation membrane leaf 5 Permeation side flow path 6 Supply side flow path material 9 Water collecting pipe 21, 71 Supply side surface 22 Permeation Side surface 100 Separation membrane element

Claims (12)

A separation membrane body having at least a base material and a separation functional layer;
A separation membrane comprising a flow path member fixed to the base material side surface of the separation membrane body,
The separation membrane in which the thickness of the flow path material on the first end side of the separation membrane in the first direction is larger than the thickness of the flow path material on the second end side. The projection image of the channel material with respect to a plane perpendicular to the membrane surface of the separation membrane body and parallel to the first direction is divided by a straight line that bisects the length of the channel material in the first direction. When
In the projected image, the area of the region located on the first end side with respect to the straight line is larger than the area of the region located on the second end side,
The separation membrane according to claim 1. In the channel material, the thickest part in the first direction is located within 30% of the length of the separation membrane in the first direction from the first end of the separation membrane.
The separation membrane according to claim 1 or 2. The thickness of the channel material monotonously increases from the second end to the first end.
The separation membrane according to any one of claims 1 to 3. The flow path material is continuous in the first direction,
The separation membrane according to any one of claims 1 to 4. The channel material is provided discontinuously in the second direction.
The separation membrane according to any one of claims 1 to 5. The maximum value of the difference in the thickness of the flow path material in the entire first direction is 1 μm or more and 600 μm or less,
The separation membrane according to any one of claims 1 to 6. The thickness of the channel material is 10 μm or more and 800 μm or less,
The separation membrane according to any one of claims 1 to 7. The width of the flow path material on the first end side of the separation membrane in the first direction is smaller than the width of the flow path material on the second end side,
The separation membrane according to claim 1. The difference between the maximum value and the minimum value of the width of the channel material is 1 μm or more and 300 μm or less,
The separation membrane according to claim 9. The width of the channel material is 10 μm or more and 1000 μm or less.
The separation membrane according to claim 9 or 10. A water collecting pipe, and the separation membrane according to any one of claims 1 to 11 wound around the water collecting pipe,
The separation membrane element is arranged such that the first end is on the inner side in the winding direction.

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