JP2015127051A - Separation membrane element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the separation removal performance of a separation membrane element when being operated for a long term.SOLUTION: A separation membrane element provided with a water collection pipe and a membrane leaf wound around the water collection pipe and possessed with a base material and a separation function layer includes: a separation membrane being disposed so as to face the surfaces of a base material side each other; and a sealing part where a space between a plurality of protrusions adhered to the surface of the base material side and the surface of the base material side of the separation membrane is sealed with an adhesive. The sealing part is disposed at least at both end sides of the base material side in a width direction and the range of the variation coefficient of the width of the sealing part is 10-40%.

Description

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

  In the technology for removing ionic substances contained in seawater, brine, and the like, in recent years, the use of separation methods using separation membrane elements is expanding as a process for saving energy and resources. The separation membrane used for the separation membrane element is selectively used depending on the target separation component and separation performance.

  As the separation membrane element, various shapes 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 according to applications and purposes.

  It is known that a spiral separation membrane element uses a leaf formed by folding a series of separation membranes so that the surfaces on the supply water side face each other. According to this, by folding the separation membrane, a flow path material such as a net can be sandwiched between surfaces of the separation membrane on the supply water side with relatively high accuracy. A plurality of the obtained leaves are laminated in a state where the permeate-side surfaces of the separation membrane face each other to form a wound body.

  Each leaf has a fold on one side, and the raw water flow path inside the leaf is closed with respect to the water collecting pipe by this fold. One side in the direction perpendicular to the direction of the crease (one side in the longitudinal direction) faces the upstream end plate, and the other side in the direction perpendicular to the direction of the crease (the other side in the longitudinal direction) is downstream A wound body is formed facing the side end plate. The remaining side of each leaf is closed by adhesion.

  Patent Document 1 describes an example in which the width of the sealing portion is changed as a measure for improving operational stability and manufacturing when a tricot is used as the permeate-side channel material. Patent Document 2 proposes an element in which the amount of water produced by the element is increased by disposing a resin having a high elastic modulus on the permeation side of the separation membrane.

JP 2008-43824 A International Patent Publication No. 2013-047746

  However, it cannot be said that the separation membrane element described above has sufficiently high stability when operated for a long period of time. Accordingly, an object of the present invention is to provide a separation membrane element that can stabilize the separation and removal performance of the separation membrane element when operated for a long period of time.

In order to achieve the above object, a separation membrane element of the present invention is a separation membrane element comprising a water collection pipe and a membrane leaf wound around the water collection pipe,
The membrane leaf is
A separation membrane having a substrate and a separation functional layer, and disposed so that the surfaces on the substrate side face each other;
A sealing portion in which a plurality of protrusions fixed on a base material or a sheet and a surface on the base material side of the separation membrane facing each other by an adhesive are sealed;
The sealing portion is provided at least at both ends in the width direction on the separation membrane permeation side, and the variation coefficient of the width of the sealing portion is in the range of 10 to 40%.

  According to the present invention, stable separation and removal performance can be realized even if the operation is performed for a long time.

It is a disassembled perspective view which shows one form of a separation membrane leaf. It is a top view which shows a separation membrane provided with the protrusion continuously provided in the length direction of the separation membrane. It is a top view which shows the separation membrane provided with the protrusion provided discontinuously in the length direction of the separation membrane. It is sectional drawing of the separation membrane of FIG. 2 and FIG. It is sectional drawing which shows schematic structure of a separation membrane main body. It is a development perspective view showing one form of a separation membrane element. It is a schematic diagram which shows the form of a sealing part. It is a schematic diagram which shows the other form of a sealing part. It is a schematic diagram which shows the other form of a sealing part. It is an example of the method of arrange | positioning the sheet | seat which fixed the protrusion to the film | membrane leaf.

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

I. First Embodiment [1. Separation membrane)
(1-1) Overview of Separation Membrane 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.

  In the present embodiment, protrusions are fixed on the substrate. When the protrusion is fixed to the base material, it is integrated with the separation membrane, so that the protrusion can be regarded as the separation membrane. Therefore, below, in order to distinguish a protrusion and a membrane part, a membrane part may be called a "separation membrane main body." That is, the separation membrane can also be expressed as including a separation membrane main body and a protrusion 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 permeation protrusion 3 as shown in FIG. 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 main body means a surface on the side to which raw water is supplied out of the two surfaces of the separation membrane main body. The “transmission side surface” means the opposite side surface. As will be described later, when the separation membrane main body includes the base material 201 and the separation functional layer 203 as shown in FIG. 5, generally, the surface on the separation functional layer side is the surface on the supply side, Is the surface on the transmission side.

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

  The x-axis, y-axis, and z-axis direction axes are shown in the figure. As shown in FIG. 1 and the like, the separation membrane body 2 is rectangular, and the x-axis direction and the y-axis direction are parallel to the outer edge of the separation membrane body 2. The x direction corresponds to the width direction of the separation membrane, and the y axis direction corresponds to the length direction. From the viewpoint of the direction during film formation, the width direction may be referred to as CD (Cross direction) and the length direction may be referred to as MD (Machine direction).

(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. As shown in FIG. 5, in the composite membrane, a porous support layer 202 may be formed between the separation functional layer 203 and the base material 201.

<Separation function layer>
The thickness of the separation functional layer is not limited to a specific numerical value, but is preferably 5 nm or more and 3000 nm or less in terms of separation performance and transmission performance. In particular, in the case of a reverse osmosis membrane, a forward osmosis membrane, and a nanofiltration membrane, the thickness is preferably 5 nm to 300 nm.

  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.

  In this document, “X contains Y as a main component” means that the Y content in X is 50% by mass, 70% by mass, 80% by mass, 90% by mass, or 95% by mass. 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.

  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 terms of excellent separation performance of components in raw water. 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 constituent component of the separation functional layer is not limited to polyamide, and may be an organic-inorganic hybrid having Si element or the like.

  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. Particularly in terms of interfacial polymerization reactivity and retention of the separation functional layer, the pores on the surface on the side where the separation functional layer is formed in the porous support layer preferably have a projected area equivalent circle diameter of 3 nm 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 force 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 kV 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. The porous support layer is formed by casting a solution of polysulfone in N, N-dimethylformamide (hereinafter referred to as DMF), for example, on a substrate to be described later, for example, a densely woven polyester cloth or non-woven cloth, to a certain thickness And can be produced by wet coagulation 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 ° or more and 25 ° or less, and the fiber orientation in the surface layer on the porous support layer side. It is preferable that the degree of orientation difference with respect to the degree is 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 ° or more and 90 ° or less, 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 the film forming direction (MD) when performing continuous film formation, that is, the angle between the longitudinal direction of the nonwoven fabric substrate and the longitudinal direction of the fibers constituting the nonwoven fabric substrate. Average value. 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 fibers are selected for each sample, and the angle of the fibers in the longitudinal direction when the longitudinal direction of the nonwoven fabric is 0 ° is measured. Here, the longitudinal direction of the nonwoven fabric refers to “Machine direction” at the time of manufacturing the nonwoven fabric. The longitudinal direction of the nonwoven fabric coincides with the film forming direction of the porous support layer. These directions coincide with the length direction in the drawing. The CD direction in the figure corresponds to “Cross direction” at the time of manufacturing the nonwoven fabric. In this way, the angle is measured for a total of 100 fibers per nonwoven fabric. The average value is calculated from the angles in the longitudinal direction for the 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 substrate is preferably in the range of 30 μm to 300 μm, or in the range of 50 μm to 250 μm.

  The porosity of the substrate is preferably 20% or more and 90% or less.

(1-3) Protrusion (permeation side channel material)
<Overview>
The permeation side surface of the separation membrane main body has a composition different from that of the base material, and is adhered to the side opposite to the separation functional layer in the thickness direction of the base material so as to form a permeation side flow path. Protrusions are provided. “Provided so as to form a permeate-side flow path” means that when the separation membrane is incorporated into a separation membrane element described later, the permeated fluid that has permeated the separation membrane main body can reach the water collecting pipe. It means that an object is formed. The details of the configuration of the protrusion are as follows.

<Constituent components of protrusion>
The protrusion 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 protrusion 3 is preferably different from the composition of the surface of the separation membrane body 2 on which the protrusion 3 is formed, and may be different from the composition of any layer forming the separation membrane body 2. preferable.

  Although it does not specifically limit as a material which comprises a protrusion, Resin is used preferably. Specifically, from the viewpoint of chemical resistance, ethylene vinyl acetate copolymer resins, polyolefins such as polyethylene and polypropylene, and olefin copolymers are preferable, and polymers such as urethane resins and epoxy resins can also be selected. Or it can use as a mixture which consists of two or more types. In particular, since a thermoplastic resin is easy to mold, a projection having a uniform shape can be formed.

<< Overview >>
A tricot that has been widely used in the past is a knitted fabric, and is composed of three-dimensionally intersecting yarns. That is, the tricot has a two-dimensionally continuous structure. When such a tricot is applied as a permeate-side channel material, the height of the channel is smaller than the thickness of the tricot. That is, the entire thickness of the tricot cannot be used as the height of the flow path.

  On the other hand, as an example of the configuration of the present invention, the protrusions 3 shown in FIG. 1 and the like are arranged so as not to overlap each other. Therefore, all the heights (that is, thicknesses) of the protrusions 3 of the present embodiment are utilized as the heights of the grooves of the flow path. Therefore, when the protrusion 3 of this embodiment is applied, a flow path becomes high rather than the case where the tricot which has the same thickness as the height of the protrusion 3 is applied. That is, since the cross-sectional area of the flow path becomes larger, the flow resistance becomes smaller.

  In the form shown in each drawing, a plurality of discontinuous protrusions 3 are fixed on one separation membrane body 2. “Discontinuous” is a state in which a plurality of protrusions are provided at intervals. That is, when the protrusion 3 in one separation membrane is peeled from the separation membrane body 2, a plurality of protrusions 3 separated from each other are obtained. On the other hand, members such as nets, tricots, and films exhibit a continuous and integral shape even when separated from the separation membrane body 2.

  By providing a plurality of discontinuous protrusions 3, the separation membrane 1 can suppress the pressure loss when incorporated in the separation membrane element 100 described later. As an example of such a configuration, in FIG. 2, the protrusions 3 are formed discontinuously only in the width direction, and in FIG. 3, they are formed discontinuously in both the width direction and the length direction. 2 and 3, a permeate-side flow path 5 is formed between adjacent protrusions 3.

  The separation membrane is preferably disposed so that the length direction of the separation membrane element 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 6 and the length direction is orthogonal to the longitudinal direction of the water collecting pipe 6.

  The protrusions 3 are provided discontinuously in the width direction, and are provided so as to continue from one end to the other end of the separation membrane body 2 in the length direction. That is, when the separation membrane is incorporated into the separation membrane element as shown in FIG. 5, the protrusions 3 are arranged so as to continue from the inner end to the outer end of the separation membrane 1 in the winding direction. 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 projections are continuous in the length direction” means that the projections are provided without interruption as shown in FIG. 2 and there are places where the projections are interrupted as shown in FIG. In which both are substantially continuous. The “substantially continuous” form preferably satisfies that the distance e between the protrusions in the length direction (that is, the length of the portion where the protrusion is interrupted) is 5 mm or less. In particular, the distance e is more preferably 1 mm or less, and further preferably 0.5 mm or less. In addition, the total value of the intervals e included from the beginning to the end of the row of protrusions arranged in the length direction is preferably 100 mm or less, more preferably 30 mm or less, and further preferably 3 mm or less. preferable. In the form of FIG. 2, the interval e is 0 (zero).

  When the protrusions 3 are provided without interruption as shown in FIG. 2, membrane dropping is suppressed during pressure filtration. Membrane sagging is that the membrane falls into the channel and narrows the channel.

  In FIG. 3, the protrusions 3 are discontinuously provided not only in the width direction but also in the length direction. That is, the protrusions 3 are provided at intervals in the length direction. However, as described above, since the protrusions 3 are substantially continuous in the length direction, film sagging is suppressed. Further, by providing the discontinuous protrusions 3 in the two directions as described above, the contact area between the protrusions and the fluid is reduced, so that the pressure loss is reduced. In other words, this form is a configuration in which the flow path 5 includes a branch point. That is, in the configuration of FIG. 3, the permeating fluid is divided by the protrusions 3 while flowing through the flow path 5, and can further merge downstream.

  As described above, in FIG. 2, the protrusion 3 is provided so as to be continuous from one end to the other end of the separation membrane body 2 in the length direction. Further, in FIG. 3, the protrusion 3 is divided into a plurality of portions in the length direction, but these plurality of portions are provided so as to be lined up from one end to the other end of the separation membrane body 2.

  The projection is “provided from one end of the separation membrane body to the other end” means that the projection is provided up to the edge of the separation membrane body 2 and the region where the projection is not provided in the vicinity of the edge. Includes both certain forms.

  In other words, the protrusions only have to be distributed over the entire separation membrane body 2 in the length direction to such an extent that a flow passage on the permeation side can be formed. There may be. For example, it is not necessary to provide a protrusion on the sealing portion with the other separation membrane on the permeate side surface. Moreover, the area | region where a protrusion is not arrange | positioned may be provided in some places, such as the edge part of a separation membrane, for the reason on the other specification or manufacture.

  Even in the width direction, the protrusions 3 can be distributed almost uniformly over the entire separation membrane body 2. However, similar to the distribution in the length direction, it is not necessary to provide a protrusion on the sealing portion of the permeate side surface with another separation membrane. Moreover, the area | region where a protrusion is not arrange | positioned may be provided in some places, such as the edge part of a separation membrane, for the reason on the other specification or manufacture.

<< Dimensions of separation membrane body and protrusions >>
As shown in FIGS. 2 to 4, a to f indicate the following values.

a: Length of the separation membrane body 2 b: Spacing of the projections 3 in the width direction of the separation membrane body 2 c: Height of the projections d: Width of the projections e: Above in the length direction of the separation membrane body 2 Interval of protrusions f: Length of protrusion 3 For measurement of the values a to f, for example, a commercially available shape measurement system or a microscope can be used. Each value is obtained by performing measurement at 30 or more locations on one separation membrane, and calculating an average value by dividing the sum of these values by the number of measurement total locations. Thus, each value obtained as a result of the measurement at at least 30 locations only needs to satisfy the above range.

(Length of separation membrane body a)
The length a is the distance from one end of the separation membrane body 2 to the other end in the length direction. When this distance is not constant, the length a can be obtained by measuring this distance at 30 or more positions in one separation membrane body 2 and obtaining an average value.

(Space b between protrusions in the width direction)
The interval b between the protrusions 3 in the width direction corresponds to the width of the flow path 5. When the width of one flow path 5 is not constant in one cross section, that is, when the side surfaces of two adjacent protrusions 3 are not parallel, the maximum value and the minimum width of one flow path 5 are within one cross section. The average value is measured and the average value is calculated. As shown in FIG. 4, in the cross section perpendicular to the length direction, when the protrusion 3 has a trapezoidal shape with a thin top and a thick bottom, first, the distance between the upper portions of the two adjacent protrusions 3 and the lower portion The distance is measured and the average value is calculated. In any 30 or more cross sections, the interval between the protrusions 3 is measured, and an average value is calculated in each cross section. And the space | interval b is calculated by calculating further the arithmetic mean value of the average value obtained in this way.

  As the distance b increases, the pressure loss decreases, but the film falls easily. Conversely, the smaller the distance b, the less likely the film will drop, but the greater the pressure loss. Considering the pressure loss, the interval b is preferably 0.05 mm or more, 0.2 mm or more, or 0.3 mm or more. Further, in terms of suppressing film sagging, the interval b is preferably 5 mm or less, 3 mm or less, 2 mm or less, or 0.8 mm or less.

  These upper and lower limits can be combined arbitrarily. For example, the interval b is preferably 0.2 mm or more and 5 mm or less, and within this range, the pressure loss can be reduced while suppressing the film sagging. The distance b is more preferably 0.05 mm or more and 3 mm or less, 0.2 mm or more and 2 mm or less, and further preferably 0.3 mm or more and 0.8 mm or less.

(Projection height c)
The height c is a difference in height between the protrusion and the surface of the separation membrane main body. As shown in FIG. 4, the height c is a difference in height between the highest portion of the protrusion 3 and the permeation side surface of the separation membrane main body in a cross section perpendicular to the length direction. That is, in the height, the thickness of the portion impregnated in the base material is not considered. The height c is a value obtained by measuring and averaging the heights of the protrusions 3 at 30 or more locations. The height c of the protrusion may be obtained by observing the cross section of the protrusion in the same plane, or may be obtained by observing the cross section of the protrusion in a plurality of planes.

  The height c can be appropriately selected according to the use condition and purpose of the element, but may be set as follows, for example.

  The larger the height c, the smaller the flow resistance. Therefore, the height c is preferably 0.03 mm or more, 0.05 mm or more, or 0.1 mm or more. On the other hand, the smaller the height c, the larger the number of films filled per element. Therefore, the height c is preferably 0.8 mm or less, 0.4 mm or less, or 0.32 mm or less. These upper limits and lower limits can be combined. For example, the height c is preferably 0.03 mm or more and 0.8 mm or less, preferably 0.05 mm or more and 0.4 mm or less, and 0.1 mm or more. More preferably, it is 0.32 mm or less.

  Moreover, it is preferable that the difference in height between two adjacent protrusions is small. If the difference in height is large, the separation membrane is distorted during pressure filtration, so that defects may occur in the separation membrane. The height difference between two adjacent protrusions is preferably 0.1 mm or less, more preferably 0.06 mm or less, and further preferably 0.04 mm or less.

  For the same reason, the maximum height difference of all the protrusions provided on the separation membrane is preferably 0.25 mm or less, particularly preferably 0.1 mm or less, and further preferably 0.03 mm or less.

(Projection width d)
The width d of the protrusion 3 is measured as follows. First, the average value of the maximum width and the minimum width of one protrusion 3 is calculated in one cross section perpendicular to the length direction. That is, in the protrusion 3 with a thin upper part and a thick lower part as shown in FIG. 4, the width of the lower part and the upper part of the protrusion are measured, and the average value is calculated. By calculating such an average value in at least 30 cross-sections and calculating the arithmetic average thereof, the width d per film can be calculated.

  The width d of the protrusion 3 is preferably 0.2 mm or more or 0.3 mm or more. When the width d is 0.2 mm or more, the shape of the protrusion can be maintained even when pressure is applied to the protrusion 3 during operation of the separation membrane element, and the permeation side flow path is stably formed. The width d is preferably 2 mm or less or 1.5 mm or less. When the width d is 2 mm or less, a sufficient flow path on the permeate side can be secured.

  When the width of the protrusion is wider than the protrusion interval b, the pressure applied to the protrusion can be dispersed.

  The protrusion 3 is formed so that its length is larger than its width. Such a long protrusion 3 is also referred to as a “wall-like object”.

(Distance e between protrusions in the length direction)
The distance e between the protrusions 3 in the length direction is the shortest distance between the protrusions 3 adjacent in the length direction. As shown in FIG. 2, the protrusion 3 is provided continuously from one end to the other end of the separation membrane body 2 in the length direction (in the separation membrane element, from the inner end to the outer end in the winding direction). The distance e is 0 mm. Moreover, as shown in FIG. 3, when the protrusion 3 is interrupted in the length direction, the interval e is preferably 5 mm or less, more preferably 1 mm or less, and further preferably 0.5 mm or less. . When the distance e is within the above range, the mechanical load on the film is small even when the film is dropped, and the pressure loss due to the blockage of the flow path can be relatively small. In addition, the minimum of the space | interval e is 0 mm.

(Projection length f)
The length f of the protrusion 3 is the length of the protrusion 3 in the length direction of the separation membrane body 2. The length f is obtained by measuring the length of 30 or more protrusions 3 in one separation membrane 1 and calculating the average value. The length f of the protrusion may be equal to or less than the length a of the separation membrane body. When the length f of the protrusion is equal to the length a of the separation membrane body, it means that the protrusion 3 is continuously provided from the inner end to the outer end in the winding direction of the separation membrane 1. The length f is preferably 10 mm or more or 20 mm or more. Since the length f is 10 mm or more, the flow path is secured even under pressure.

(shape)
The shape of the protrusion is not particularly limited, but a shape that reduces the flow resistance of the flow path and stabilizes the flow path 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 protrusion may be a straight column shape, a trapezoidal shape, a curved column shape, or a combination thereof.

When the cross-sectional shape of the protrusion is trapezoidal, if the difference between the length of the upper base and the length of the lower base is too large, membrane drop during pressure filtration is likely to occur at the membrane in contact with the smaller one. For example, when the upper base of the protrusion is shorter than the lower base, the upper width is wider than the lower width in the flow path therebetween. Therefore, the upper film tends to drop downward. Therefore, in order to suppress such a drop, the ratio of the length of the upper base to the length of the lower base of the projection is preferably 0.6 or more and 1.4 or less, and more preferably 0.8 or more and 1.2 or less. preferable.
From the viewpoint of reducing flow resistance, it is preferable that the columnar shape is perpendicular to the later-described separation membrane surface. In addition, the protrusion may be formed so that the width becomes smaller at a higher portion, or conversely, the protrusion may be formed so that the width becomes wider at a higher portion, or the height from the surface of the separation membrane. However, it may be formed to have the same width.

  However, the upper side may be rounded in the cross section of the protrusion as long as the protrusion is not significantly crushed during pressure filtration.

  If the protrusion is a thermoplastic resin, the shape of the protrusion can be adjusted freely so that the required separation characteristics and permeation performance conditions can be satisfied by changing the processing temperature and the type of thermoplastic resin selected. be able to.

  Further, the shape of the projections in the planar direction of the separation membrane may be linear as a whole as shown in FIGS. 2 and 3, and other shapes are, for example, curved, sawtooth, and wavy. May be. Further, in these shapes, the protrusions may be broken lines or dots. From the viewpoint of reducing the flow resistance, a dot shape or a broken line shape is preferable. However, since the protrusions are interrupted, the number of places where film sagging occurs during pressure filtration increases.

  Moreover, when the shape of the separation film in the planar direction of the separation membrane is a straight line, the adjacent protrusions may be arranged substantially parallel to each other. “Arranged substantially parallel” means, for example, that the projections do not intersect on the separation membrane, the angle formed by the longitudinal direction of two adjacent projections is 0 ° or more and 30 ° or less, and the angle is It includes that it is 0 ° or more and 15 ° or less, and that the angle is 0 ° or more and 5 ° or less.

  Further, the angle formed by the longitudinal direction of the projection 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 ° or less. More preferably. When the angle formed between the longitudinal direction of the protrusion 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 drop of the separation membrane body is suppressed even when the separation membrane body is pressurized during use of the separation membrane element. For this purpose, it is preferable that the contact area between the separation membrane main body and the projection is large, that is, the area of the projection 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 section of the flow path is a cross section perpendicular to the longitudinal direction of the flow path (in the example of FIG. 1 and the like, a cross section perpendicular to the winding direction). In order to ensure a large contact area between the separation membrane main body and the protrusion and to ensure a wide cross-sectional area of the flow path, the side surface of the protrusion is concave or the shape of the protrusion in the cross section of the flow path. Is preferably trapezoidal. That is, the cross-sectional shape of the flow path itself is preferably an ellipse, a semicircle, a trapezoid, or the like.

  In addition, the cross-sectional shape of the protrusion may be a rectangle with no change in width. As long as the separation membrane performance is not affected, the cross-sectional shape in the direction perpendicular to the winding direction may be a shape having a change in width. Examples of such cross-sectional shapes include triangles and hemispheres other than those described above.

  The shape of the protrusion is not limited to the shape illustrated. When placing protrusions on the permeate side surface of the separation membrane body by fixing a molten material, for example, as in the hot melt method, the processing temperature and the type of hot melt resin to be selected can be changed. The shape of the protrusion can be freely adjusted so that the required separation characteristics and permeation performance conditions can be satisfied.

  In FIGS. 1 to 3, the shape of the protrusion 3 in the planar direction (the shape in the xy plan view) is a linear shape whose longitudinal direction is parallel to the winding direction. However, the protrusion 3 can be changed to another shape as long as it protrudes from the surface of the separation membrane body 2 and does not impair the desired effect as the separation membrane element. That is, the shape in the plane direction may be a curved line, a wavy line, or the like. In addition, a plurality of protrusions having at least one of width and length different from each other may be formed on one separation membrane.

(Projected area ratio)
The projected area ratio of the projections to the permeation side surface of the separation membrane may be 0.03 or more and 0.85 or less, particularly in terms of reducing the flow resistance of the permeation side flow path and forming the flow path stably. Preferably, it is 0.15 or more and 0.85 or less, more preferably 0.2 or more and 0.75 or less, and further preferably 0.3 or more and 0.6 or less. The projected area ratio is a value obtained by dividing the projected area of the protrusion obtained when the separation membrane is cut out at 5 cm × 5 cm and projected onto a plane parallel to the surface direction of the separation membrane by the cut-out area (25 cm ² ). is there. This value can also be expressed by the above-described equation df / (b + d) (e + f).

[2. Separation membrane element)
(2-1) Overview As shown in FIG. 6, the separation membrane element 100 includes the water collecting pipe 6 and any one of the above-described configurations, and includes the separation membrane 1 wound around the water collecting pipe 6. The separation membrane element 100 further includes a member such as an end plate (not shown).

(2-2) Separation membrane <Overview>
The separation membrane 1 is wound around the water collecting pipe 6 and is arranged so that the width direction is along the longitudinal direction of the water collecting pipe 6. As a result, the separation membrane 1 is disposed such that the length direction is along the winding direction.

  Accordingly, the protrusions 3 that are wall-like objects are discontinuously arranged at least in the longitudinal direction of the water collecting pipe 6 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 winding direction” and “Outside in winding direction” are as shown in FIG. That is, the “inner end portion in the winding direction” and the “outer end portion in the winding direction” correspond to the end portion closer to the water collecting pipe 6 and the far end portion in the separation membrane 1, respectively.

  As shown in FIG. 1, the separation membrane 1 forms a membrane leaf 4 (sometimes simply referred to as “leaf” in this document). In the leaf 4, the separation membrane 1 is disposed so that the supply-side surface 21 faces the supply-side surface 71 of another separation membrane 7 with a supply-side flow path material (not shown) interposed therebetween. In the separation membrane leaf 4, a supply-side flow path is formed between the supply-side surfaces of the separation membranes facing each other.

  Further, in one leaf 4, the space between the supply-side surfaces of the separation membrane 1 facing each other is closed by folding or sealing at the winding direction inner end (portion indicated by a one-dot chain line).

  When the supply side surface of the separation membrane is sealed instead of being 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 when encircling and the occurrence of leakage due to the voids are suppressed. When the separation membrane leaf is formed by folding, the longer the leaf (that is, the longer the original separation membrane), the longer the time required for folding the separation membrane. However, by sealing the supply side surface of the separation membrane instead of folding, an increase in manufacturing time can be suppressed even if the leaf is long.

  As shown in FIG. 1, a plurality of membrane leaves 4 are stacked. Between the surfaces on the permeate side facing each other, in the rectangular shape of the separation membrane, only one side on the inner side in the winding direction is opened and the other three sides are sealed so that the permeate flows into the water collection pipe 6 (see FIG. (Indicated by a two-dot chain line). The permeated water is isolated from the raw water by the sealing portion 41. The two separation membranes sealed through the permeation side surface are called envelope-like membranes and are denoted by reference numeral “52”.

  As the form of the sealing portion on the surface on the transmission side, there are adhesion by a resin such as an adhesive (including hot melt), fusion by heating or laser, sealing by sandwiching a rubber sheet, etc. Can be mentioned. Sealing by adhesion is particularly preferable because it is the simplest and most effective. These techniques may also be applied to sealing the supply side surface. However, the sealing method may be the same or different between the transmission side surface and the supply side surface.

  As described above, since the supply side surface of the separation membrane is sealed rather than folded, bending at the end of the separation membrane hardly occurs. As a result, the occurrence of leak is suppressed.

  A specific air leak test method is as follows. The end of the central pipe of the separation membrane element is sealed, and air is injected from the other end. The injected air passes through the holes of the water collection pipe and reaches the permeation side of the separation membrane. However, as described above, the separation membrane is not sufficiently folded and the surface on the permeation side is bent near the crease. When air gaps exist in the sealed portion, air moves to the separation membrane supply side. Then, air leaks into the water from the end of the separation membrane element, that is, from between the surfaces on the supply side. The air leak at this time can be confirmed as the generation of bubbles.

  In the separation membrane leaf, the separation membranes facing each other (separation membranes 1 and 7 in FIG. 1) 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.

<Sealing part>
(Form of sealing part)
Hereinafter, the leaf sealing portion will be described with reference to FIGS. 7, 8, and 9. It is preferable that at least a part of the sealing portion for sealing between the permeation side surfaces of the separation membrane is disposed outside the projection in the membrane surface direction (xy plane direction).

  As described above, the sealing portion is provided on the three sides of the leaf. Therefore, a sealing part contains the part provided in the winding direction outer side edge part, and the part provided in the both ends of the width direction. Hereinafter, when particularly distinguishing, the sealing portion at the outer end portion in the winding direction is referred to as a first sealing portion 411, and the portions provided on both sides in the width direction are referred to as second sealing portions (412, 413). . Moreover, since the 2nd sealing part is each provided in an upstream edge part and a downstream edge part in the supply direction of raw | natural water, each is called the upstream sealing part 412 and the downstream sealing part 413.

(Width of sealing part)
When the adhesive is applied to surround the separation membrane, the adhesive spreads between the separation membranes. If the variation coefficient of the width of the second sealing portion (412, 413) is 10% or more, the sealing portion is well spread, so that the sealing performance is improved. That is, since the adhesive spreads well when wrapped, the height of the adhesive becomes uniform, and the sealing performance of the entire leaf becomes uniform. Moreover, sufficient effective film area is securable by being 40% or less. For these reasons, the variation coefficient of the width of the second sealing portions 412 and 413 is preferably 10% or more and 40% or less, and more preferably 15% or more and 30% or less. The variation rate of the width can be measured by the method described in Examples described later.

  However, if the number of leaves is multiple, such as a 4-inch element, 8-inch element, or 16-inch element, even if some leaves are outside this range, the effect on the whole will be reduced, so loading Forty percent or less of the number of leaves may be out of this range. In addition, although the width | variety of a sealing part is not specifically limited, The effect of this invention can be heightened by setting it as the range of 5-55 mm.

  Further, since the rigidity of the separation membrane is higher in the portion where the protrusion is fixed to the separation membrane than in the portion where the protrusion is not fixed, the leaf having the fixed protrusion is likely to have non-uniform rigidity. However, by utilizing the rigidity of the adhesive that bonds the leaves together, it is possible to compensate for the non-uniform rigidity of the separation membrane to which the protrusions are fixed. The greater the adhesive application width (that is, the width of the sealing portion), the higher the rigidity. On the other hand, the sealing portion may be destroyed by the load applied when the element is actually operated or shearing due to the flow of water. In some cases, the effective membrane area may be reduced by applying the adhesive. Therefore, the ratio of the width of the inner peripheral end to the width of the outer end in the winding direction in the second sealing portions 412 and 413 is preferably in the range of 0.4 to 3.5, and is in this range. This solves the above problem.

  The width L412 of the second sealing portion 412 at the outer end in the winding direction is the shortest distance from the intersection x412 between the first sealing portion 411 and the second sealing portion 412 to the widthwise end of the separation membrane. The width L413 of the second sealing portion 413 on the outer side in the winding direction is the shortest distance from the intersection point x413 between the first sealing portion 411 and the second sealing portion 413 to the end portion in the width direction of the separation membrane.

  In addition, when the corner | angular inside the sealing part 41 swells like FIG.7, FIG.8, the place where it swells is contained in the 2nd sealing parts 412 and 413. FIG.

  The widths W412 and W413 of the inner peripheral portions of the second sealing portions 412 and 413 at the inner ends in the winding direction are the second sealing in the range of 40 ± 10 mm from the inner end to the outer side in the winding direction of the separation membrane. This is the average value of the widths of the parts 412 and 413. The average value is a value obtained by measuring the adhesive width every 10 mm in the length direction of the envelope-like film and dividing the total of the measurement results by the population (that is, the number of measurement points). That is, it is expressed by (total measured adhesive width / parameter) of the inner peripheral portion of the second sealing portion.

  In FIG. 7, the two second sealing portions 412 and 413 swell at the outer end and the inner end in the winding direction. As a result, the widths L412 and 413 of the two second sealing portions 412 and 413 at the outer end in the winding direction are the same size as the widths W412 and W413 at the inner end in the winding direction. In FIG. 8, the widths L412 and L413 at the outer end in the winding direction are larger than the widths W412 and W413 at the inner end in the winding direction. In contrast, in FIG. 9, the widths L412 and L413 at the outer end in the winding direction are smaller than the widths W412 and W413 at the inner end in the winding direction.

  The variation coefficient of the width of the first sealing portion 411 is not particularly limited.

(Formation of sealing part)
As a method for providing the sealing portion, a conventionally known method such as a method in which the adhesive is discharged while moving the discharge nozzle along the end in the winding direction, and the adhesive is cured after being wound is cited. It is done. As a method of changing the width of the adhesive, there are a method of gradually changing the discharge amount while moving the discharge nozzle at a constant speed, and a method of changing the moving speed while keeping the discharge amount constant. It can also be achieved by a method of moving the discharge nozzle away from the end, a method of moving it closer, or a combination thereof.

  As a sealing process, when laminating and enclosing a leaf, an adhesive is applied so that the width on the outer peripheral side is wider than the inner peripheral side, and then a sealing part can be obtained by bonding and curing. . As the adhesive, any conventionally known adhesives such as urethane adhesives, epoxy adhesives and hot melt adhesives can be used.

  The viscosity of the adhesive is preferably in the range of 15 Pa · s or less, and more preferably 12 Pa · s or less. When the viscosity is 15 Pa · s or less, wrinkles are unlikely to occur when the leaf is wrapped around the water collecting pipe. Further, since the separation membrane can be sufficiently impregnated with the adhesive, the adhesive can fill the voids in the base material at the peripheral edge of the separation membrane, and can prevent the inflow of raw water. And it is preferable that the viscosity of an adhesive agent is 4 Pa.s or more or 5 Pa.s or more. When the viscosity is 4 Pa · s or more, the outflow of the adhesive from the end portion of the leaf can be suppressed, and as a result, the adhesive can be prevented from adhering to unnecessary portions other than the portion to be sealed.

  As such an adhesive, for example, a mixture of isocyanate as a main agent and polyol as a curing agent in a ratio of isocyanate: polyol = 1: 1 to 1: 5 is preferable. The viscosity of the adhesive can be 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.

  If the protrusions are continuous from the inner peripheral side to the outer peripheral side of the leaf, the protrusions become walls even if the sealing material is crushed by the surroundings, and the expansion of the sealing material can be suppressed. This leads to uniform thickness of the stopper. That is, since the thickness of the sealing material can be made uniform, the outer diameter of the element tends to be uniform, and the element is not damaged even when the pressure vessel is filled for actual operation.

(2-3) Permeation-side flow path As described above, the separation membrane 1 includes the permeation-side protrusion 3. The permeation-side protrusion 3 forms a permeation-side flow path inside the leaf, that is, between the permeation-side surfaces of the opposing separation membranes.

(2-4) Supply side channel (channel material)
The separation membrane element 100 includes a channel material (not shown) having a projected area ratio with respect to the separation membrane 1 exceeding 0 and less than 1 between the surfaces on the supply side of the overlapping separation membranes. The projected area ratio of the supply-side channel material is preferably 0.03 or more and 0.50 or less, more preferably 0.10 or more and 0.40 or less, and particularly preferably 0.15 or more and 0.35 or less. . When the projected area ratio is 0.03 or more and 0.50 or less, the flow resistance can be suppressed to be relatively small. The projected area ratio refers to the projected area obtained when the separation membrane and the supply-side channel material are cut out at 5 cm × 5 cm, and the supply-side channel material is projected onto a plane parallel to the surface direction of the separation membrane. Divided value.

  As will be described later, the height of the supply-side channel material is preferably more than 0.5 mm and not more than 2.0 mm, more preferably not less than 0.6 mm and not more than 1.0 mm, in consideration of the balance of each performance and operation cost.

  The shape of the supply-side channel material is not particularly limited, and may have a continuous shape or a discontinuous shape. Examples of the channel material having a continuous shape include members such as a film and a net. Here, the continuous shape means that it is continuous over the entire range of the flow path material. The continuous shape may include a portion where a part of the flow path material is discontinuous to such an extent that a problem such as a decrease in the amount of water produced does not occur. The definition of “discontinuity” is as described for the passage-side channel material. 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.

(2-5) Water Collection Pipe The water collection pipe 6 is not particularly limited as long as it is configured so that permeated water flows therethrough. As the water collecting pipe 6, for example, a cylindrical member having a side surface provided with a plurality of holes is used.

(2-6) End Plate As shown in FIG. 6, the separation membrane element 100 includes end plates 81 and 82 attached to both ends of the wound body of the separation membrane 1 in the longitudinal direction of the water collecting pipe 6.

  In FIG. 6, the shape of the end plate 81 and the shape of the end plate 82 are the same, but in one element, the shapes of the two end plates may be different from each other. In FIG. 6, the end plate 81 is disposed on the upstream side, and the end plate 82 is disposed on the downstream side.

[3. Method for manufacturing separation membrane element]
(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.

  In addition, before or after the chemical treatment, unevenness may be formed on the separation membrane main body by embossing or the like.

(3-2) Arrangement of Permeation Side Channel Material A method for manufacturing a separation membrane includes a step of providing discontinuous protrusions on the permeation side surface of the separation membrane main body. This step may be performed at any time during the manufacture of the separation membrane. For example, the protrusion may be provided before the porous support layer is formed on the base material, or after the porous support layer is provided and before the separation functional layer is formed. Alternatively, after the separation functional layer is formed, it may be performed before or after the above-described chemical treatment is performed.

  The method for arranging the protrusions includes, for example, a step of placing a soft material on the separation membrane and a step of curing it. Specifically, ultraviolet curable resin, chemical polymerization, hot melt, drying, or the like is used for the arrangement of the protrusions. In particular, hot melt is preferably used. Specifically, a step of softening a material such as resin by heat (that is, heat melting), a step of placing the softened material on the separation membrane, and curing the material by cooling. A step of fixing on the separation membrane.

  Examples of the method for arranging the protrusions include coating, printing, spraying, and the like. Examples of the equipment used include a nozzle type hot melt applicator, a spray type hot melt applicator, a flat nozzle type hot melt applicator, a roll type coater, an extrusion type coater, a printing machine, and a sprayer.

(3-3) Formation of Separation Membrane Leaf As described above, the separation membrane leaf may be formed by folding the separation membrane so that the surface on the supply side faces inward, or two separate sheets It may be formed by attaching a separation membrane.

  The manufacturing method of the separation membrane element preferably includes a step of sealing the inner end portion in the winding direction of the separation membrane on the surface on the supply side. In the sealing step, the two separation membranes are overlapped so that the surfaces on the supply side face each other. Further, the inner end in the winding direction of the stacked separation membranes, that is, the left end in FIG. 5 is sealed.

  Examples of the method of “sealing” include adhesion by an adhesive or hot melt, fusion by heating or laser, and a method of sandwiching a rubber sheet. Sealing by adhesion is particularly preferable because it is the simplest and most effective.

  At this time, a supply-side channel material formed separately from the separation membrane may be disposed inside the overlapped separation membrane. As described above, the arrangement of the supply-side flow path material can be omitted by providing a height difference in advance on the supply-side surface of the separation membrane by embossing or resin coating.

  Either the supply-side sealing or the transmission-side sealing (leaf formation) may be performed first, or the supply-side sealing and transmission may be performed while stacking separation membranes. The sealing of the side surface may be performed in parallel. However, in order to suppress the generation of wrinkles in the separation membrane during winding, the adhesive or hot melt at the end in the width direction is allowed to allow the adjacent separation membranes to shift in the length direction due to winding. It is preferable to complete the solidification or the like, that is, the solidification for forming the leaf, after the winding is completed.

(3-4) Separation membrane winding For manufacturing the separation membrane element, a conventional element manufacturing apparatus can be used. 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.

  When the separation membrane is wound around the water collecting pipe, the separation membrane is arranged so that the closed end of the leaf, that is, the closed portion of the envelope-shaped membrane faces the water collecting pipe. By winding the separation membrane around the water collecting pipe in such an arrangement, the separation membrane is wound in a spiral shape.

  If a spacer such as a tricot or base material is wound around the water collection pipe, the adhesive applied to the water collection pipe will not flow easily when the element is wrapped, leading to suppression of leakage, and the flow path around the water collection pipe is stable. Secured. The spacer may be wound longer than the circumference of the water collecting pipe.

  When the tricot is wound around the water collecting pipe, the adhesive applied to the water collecting pipe is difficult to flow when the element is wrapped, leading to suppression of leakage, and further, the flow path around the water collecting pipe is stably secured. The tricot may be wound longer than the circumference of the water collecting pipe.

(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 separation membrane element may be further 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 to obtain water that meets the purpose.

  The higher the operating pressure of the fluid separator, the higher the removal rate, but the energy required for operation also increases, and considering the retention of the separation membrane element supply channel and permeation channel, the membrane module The operating pressure when passing through the water to be treated is preferably 0.2 MPa or more and 5 MPa or less. As the raw water temperature increases, the salt removal rate decreases. However, as the raw water temperature decreases, the membrane permeation flux also decreases. Moreover, when the pH of the raw water is in a neutral region, even if the raw water is a high salt concentration liquid such as seawater, the generation of scales such as magnesium is suppressed, and the deterioration of the membrane is also suppressed.

  The fluid to be treated by the separation membrane element is not particularly limited, but when used for water treatment, as raw water, TDS (Total Dissolved Solids: total dissolved solids) of 500 mg / L or more and 100 g / L or less such as seawater, brine, drainage, etc. For example). In general, TDS indicates the total dissolved solid content, and is expressed by “mass / volume”, but 1 L may be expressed as 1 kg and may be expressed by “weight ratio”. According to the definition, the solution filtered through a 0.45 μm 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 the practical salt content (S). .

II. Second Embodiment (1) Element Configuration In the element of this embodiment, the permeation-side flow path member is the first except that a sheet-like member is provided instead of the protrusion fixed to the base material of the separation membrane body. The same configuration as the element of one embodiment is applied. Similarly, the description of the first embodiment is also applied to the second embodiment for the manufacturing method and the usage method other than the configuration of the element.

  Specifically, as shown in FIG. 10, the element of the present embodiment includes, as an envelope-like membrane 522, a separation membrane having the same configuration as that of the separation membrane body 2 of the first embodiment, and a sheet-like flow path member 131. With. The flow path member 131 is disposed between the permeation side surfaces 22 of the separation membrane.

  In other words, in the present embodiment, the sheet-shaped permeation-side flow path member 131 is inserted between the separation membrane leaves (a set of separation membranes stacked with the supply-side surface 21 inside). In other words, the separation membrane stacked with the permeation-side surface 22 on the inside and the sheet-like permeation-side flow path member 131 inserted therebetween form an envelope-like membrane 522.

(2) Channel material A sheet-like channel material is a member provided with sheet 13 and projection 3 adhering to the sheet.

  As the protrusion 3, the protrusion of the first embodiment is applied. As shown in FIG. 10, the protrusion 3 is disposed so as to face the surface 22 on the permeation side of the separation membrane. The permeated water can flow between the protrusions 3, that is, through the grooves.

  The sheet 13 is preferably present up to a region where the permeation side surfaces of the separation membrane are bonded to each other. That is, the two separation membranes are preferably bonded via the sheet 13 which is a component of the flow path member 131. In other words, it is preferable that the sheet is present between the separation membranes in at least a part of the adhesion portion on the permeation side surface of the separation membrane.

  In FIG. 10, the size of the sheet 13 constituting the permeate-side channel material and the size of the separation membrane are shown to be the same, but actually, the sheet may be larger or the separation membrane is larger. May be.

  The porosity of the sheet 13 is preferably 20% or more and 90% or less, and particularly preferably 45% or more and 80% or less.

  Here, the porosity means the ratio of the voids per unit volume of the substrate, and the weight when the substrate is dried is subtracted from the weight when pure water is included in the substrate having a predetermined apparent volume. The value obtained by dividing the obtained value by the apparent volume of the substrate is expressed as a percentage (%).

When the porosity of the sheet 13 is 20% or more, the sheet is easily impregnated with the adhesive that seals the protrusion 3 and the film. As a result, the protrusion 3 is difficult to peel from the sheet 13. Further, when the sheet 13 is sufficiently impregnated with the adhesive, the supply water is less likely to flow into the permeate side flow path. Further, since the permeated water easily permeates the sheet 13, the accuracy of the arrangement of the protrusions 3 on the sheet 13 is insufficient, and even if the grooves between the protrusions 3 are blocked, the permeated water passes through the sheet. Can move to another groove.
The permeated water can pass through the sheet 13, and as a result, the amount of water produced by the separation membrane element is improved.

  On the other hand, since the porosity is 90% or less, the impregnation of the protrusions 3 can be appropriately suppressed, so that the resin constituting the protrusions 3 hardly reaches the back of the sheet. As a result, the thickness of the sheet 13 is suppressed from becoming uneven. In addition, since it is possible to suppress the spread of the adhesive that bonds the surfaces on the permeate side of the separation membrane, in the completed separation membrane element, the region where the adhesive is not applied, that is, the region where pressure filtration functions effectively A large (effective membrane area) can be secured. As a result, it is possible to ensure the amount of water produced by the separation membrane element.

  It is preferable that the thickness of the sheet | seat which comprises a permeation | transmission side channel material is 0.2 mm or less. This is because the sheet is preferably impregnated with an adhesive in order to seal between the permeation side surfaces of the two separation membranes. However, even if the thickness of the sheet constituting the permeate-side channel material exceeds 0.2 mm, the separation membrane can be sealed with an adhesive as long as the porosity of the sheet is 80% or more. Moreover, since the strength of the sheet can be ensured when the thickness of the sheet constituting the permeate-side flow path material is 0.02 mm or more, damage to the sheet can be suppressed.

  In particular, if the thickness of the sheet constituting the permeate-side channel material is 0.02 mm or more and 0.2 mm or less, the porosity is preferably 20% or more and 80% or less, and the thickness of the sheet exceeds 0.02 mm. If it is 0.4 mm or less, the porosity is more preferably 30% or more and 90% or less.

  The relationship between the height c of the projection and the thickness H1 of the sheet will be described. The ratio (c / H0) of the height c of the protrusions to the sum H0 of the sheet thickness H1 and the height c of the protrusions is preferably 0.05 or more. This is because a wide flow path can be secured. On the other hand, it is preferable that the ratio (c / H0) is 0.7 or less because the sheet can be prevented from being broken or damaged by the protrusions when the sheet is wound while applying a tension. This is because the larger the ratio (c / H0), the greater the load on the sheet of protrusions and the lower the physical durability of the sheet.

  When the ratio (c / H0) is 0.13 or less, the porosity of the sheet is preferably 30% or more and 90% or less. When the ratio (c / H0) exceeds 0.13 (or 0.15 or more) and is 0.7 or less, the porosity of the sheet is 20% or more and 80% or less. Is preferred.

III. Other Embodiments In any of the first and second embodiments, a sheet having a gap such as a tricot or a porous sheet is wound around the water collecting pipe 2 inside the separation membrane. preferable. As the porous sheet, the above-described separation membrane substrate or a sheet in a sheet-like flow path material is preferably used.

  Since such a member is wound around the water collecting pipe, the adhesive applied to the water collecting pipe 2 at the time of surrounding the element becomes difficult to flow from the applied position. The flow path around the water collection pipe is secured stably.

  In addition, what is necessary is just to wind the sheet | seat which has a space | gap longer than the circumference of a water collection pipe | tube. That is, it is preferable that the sheet is wound around the water collecting pipe more than once.

  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.

(Coefficient of variation of sealing part width)
The width of the sealing portion at both sides in the width direction on the permeate side surface of the separation membrane is obtained by disassembling the obtained separation membrane element and setting the width of the sealing portion at each end to 1 mm in the membrane length direction. Measured with a measure, the arithmetic average value and deviation were calculated, and the average value / deviation was taken as the coefficient of variation of the sealing portion width.

(Width L of the outer peripheral portion of the second sealing portion)
The obtained separation membrane element is disassembled, and from the inner peripheral corners (positions x412 and x413) formed by the second sealing portions 412 and 413 and the first sealing portion 411, both ends in the width direction on the separation membrane permeation side The shortest distance to was measured with a measure.

(Width W of the inner periphery of the second sealing portion)
The obtained separation membrane element was disassembled, and the width of the adhesive at both ends in the width direction on the separation membrane permeation side of each leaf loaded in the element was measured. Specifically, in the range of 40 ± 10 mm in the length direction from the inner end in the winding direction, the adhesive width is measured every 10 mm in the length direction of the envelope-like film using a measure, and the total of these is measured. Divided by the number of places. The average value thus obtained was used as the width W of the inner periphery for the following examination.

(Ratio of the width W of the inner peripheral portion to the width L of the outer peripheral portion of the second sealing portion)
The measured width L of the outer peripheral portion and width W of the inner peripheral portion of the second sealing portion were obtained by calculation using W / L.

(Water production)
The separation membrane or separation membrane element was operated for 10 hours under the conditions of 2,000 ppm salt as raw water, an operating pressure of 1.5 MPa, an operating temperature of 25 ° C., and a pH of 6.5 (recovery rate of 15%). Thereafter, permeated water was obtained by operating for 10 minutes under the same conditions. From the volume of permeated water obtained by the operation for 10 minutes, the water permeation amount (cubic meter) per unit area of the separation membrane and per day was expressed as water production amount (high pressure) (m ³ / day).

(Desalination rate (TDS removal rate))
For the raw water and the sampled permeate used in the operation for 10 minutes in measuring the amount of water produced, the TDS concentration was determined by conductivity measurement, and the TDS removal rate was calculated from the following formula.
TDS removal rate (%) = 100 × {1− (TDS concentration in permeated water / TDS concentration in raw water)}.

(Initial stability)
Five separation membrane elements that had finished measuring the amount of water produced were immersed in water and pressurized air (0.1 MPa) was supplied, and a case where bubbles were generated for 3 minutes or more was regarded as a leak (air leak test). The number of leaves in which leakage occurred was counted, and a value of 1- (number of leaves in which air leakage occurred / number of leaves contained in the element used for evaluation) was calculated to obtain initial stability. And this operation was implemented 10 batches as 1 batch, and the initial stage stability of each batch was compared.

(Long-term stability)
About the element which implemented initial stability evaluation, the cycle (start / stop) which drive | operates for 1 minute and complete | finishes operation on the same conditions was repeated 5000 times. And the air leak test was implemented, long-term stability per batch was computed, this operation was implemented 10 batches, and the long-term stability of each batch was compared.

(Uniformity of sealing part thickness)
The obtained separation membrane element was disassembled, and the height of arbitrary 100 locations was measured using a Keyence high-precision shape measurement system KS-1100 for the leaf cross section including the sealing portion. Then, the average value and the deviation were calculated, and the average value / deviation was regarded as the uniformity of the sealing portion thickness.

(Production of separation membrane and separation membrane element)
On a non-woven fabric made of polyethylene terephthalate fiber (yarn diameter: 1 dtex, thickness: about 90 μm, air permeability: 1 cc / cm ² / sec, density: 0.80 g / cm ³ ), a 17.0 wt% DMF solution of polysulfone is 180 μm. Cast at room temperature (25 ° C.), immediately immersed in pure water for 5 minutes, and immersed in warm water at 80 ° C. for 1 minute to form a porous support layer comprising a fiber-reinforced polysulfone support membrane ( A thickness of 130 μm) was produced.

  Thereafter, the surface of the polysulfone layer of the porous support membrane was immersed in a 2.2 wt% aqueous solution of m-PDA for 2 minutes, and then slowly pulled up in the vertical direction. Furthermore, the excess aqueous solution was removed from the surface of the support film by blowing nitrogen from the air nozzle.

  Thereafter, an n-decane solution containing 0.08% by weight of trimesic acid chloride was applied so that the surface of the film was completely wetted, and then allowed to stand for 1 minute. Thereafter, excess solution was removed from the membrane by air blowing, and washed with hot water at 80 ° C. for 1 minute.

Example 1
A protrusion was formed as a permeate side channel material over the entire permeate side of the separation membrane. That is, using a gravure roll while adjusting the temperature of the backup roll to 15 ° C., a saponified ethylene-vinylacetic acid copolymer (6820 manufactured by Tosoh Corporation, compression elastic modulus: 1 GPa) is applied to the permeation side surface of the separation membrane. Applied. The resin temperature was 180 ° C. and the processing speed was 10 m / min.

  The obtained protrusion shape was as shown in Table 1.

  Here, the pitch is an average value of the horizontal distances from the vertexes of the convex portions of the separation membrane to the vertexes of the neighboring convex portions, measured at 200 locations on the transmission side surface.

The obtained separation membrane was folded and cut so that the effective area at the separation membrane element was 37.0 m ^2, and the net (thickness: 0.68 mm, pitch: 3 mm × 3 mm, fiber diameter: 0.34 m, projection) Twenty-six leaves having a width of 900 mm and a leaf length of 800 mm were prepared using an area ratio of 0.13) as a supply-side channel material.

  The leaf thus obtained was spirally wound around a water collecting pipe made of ABS (width: 1,020 mm, diameter: 30 mm, number of holes 40 × 1 linear line), and a film was further wound around the outer periphery, and then fixed with tape. . The sealing between the leaves was performed by discharging and curing the epoxy adhesive while adjusting the moving speed of the nozzle. The form of the obtained sealing part was as shown in Table 1.

  Thereafter, edge cutting, end plate attachment, and filament winding were performed to produce an 8-inch element. Both end plates were perforated end plates.

  When the separation membrane element was placed in a pressure vessel and operated under the conditions described above, the element performance was as shown in Table 1.

(Examples 2 to 8)
A separation membrane element was produced in the same manner as in Example 1 except that the formation conditions of the sealing part were changed and the form of the sealing part was changed as shown in Tables 1 to 3.

  When the separation membrane element was placed in a pressure vessel and operated under the conditions described above, the element performance was as shown in Tables 1 to 3.

(Examples 9 and 10)
All the conditions for the formation of protrusions were implemented except that the resin was applied linearly to the permeate side surface of the separation membrane body so that it was parallel to the longitudinal direction of the separation membrane body (that is, the longitudinal direction of the nonwoven fabric as the base material). A separation membrane element was produced in the same manner as in Example 7.

  When the separation membrane element was placed in a pressure vessel and operated under the conditions described above, the element performance was as shown in Table 3.

(Example 11)
Instead of forming the protrusions on the base material side of the separation membrane, the sheet was made of papermaking nonwoven fabric (yarn diameter: 1 dtex, thickness: about 0.03 mm, porosity 25%), and the height of the protrusions was 0.24 mm. A separation membrane element was produced in the same manner as in Example 9 except that the permeate-side channel material was disposed.

  When this element was put in a pressure vessel and operated under the above conditions to obtain permeated water, the element performance was as shown in Table 3.

(Comparative Example 1)
A separation membrane element was produced in the same manner as in Example 1 except that the formation conditions of the sealing portion were changed and the form of the sealing portion was changed as shown in Table 3.

  When the separation membrane element was placed in a pressure vessel and operated under the conditions described above, the element performance was as shown in Table 3.

(Comparative Example 2)
A separation membrane element was produced in the same manner as in Example 1 except that the protrusion was not fixed to the permeation side of the separation membrane, and the change was made.

  When the separation membrane element was placed in a pressure vessel and operated under the conditions described above, the element performance was as shown in Table 3.

  As is clear from the results, the separation membrane and the separation membrane element of the examples have high water production performance, stable operation performance, and excellent removal performance.

  The membrane element of the present invention can be suitably used particularly for brine or seawater desalination.

DESCRIPTION OF SYMBOLS 1 Separation membrane 2 Separation membrane main body 21 Supply side surface 22 Permeation side surface 201 Base material 202 Porous support layer 203 Separation functional layer 3 Protrusion 4 Separation membrane leaf 5 Permeation side flow path 6 Water collecting pipe 7 Separation membrane 13 Sheet 71 Supply side surface 72 Permeation side surface 81, 82 End plate 100 Separation membrane element a Separation membrane (leaf) length b Protrusion width direction c Protrusion height difference d Protrusion width e Protrusion length Interval in direction f Projection length L412, 413 Width of outer peripheral portion of second sealing portion W412, 413 Width of inner peripheral portion of second sealing portion x412, 413 Width of adhesive support portion and first sealing portion The position of the inner circumference formed by

Claims (4)

A separation membrane element comprising a water collection pipe and an envelope membrane wound around the water collection pipe and opening toward the water collection pipe,
The envelope film is
A separation membrane main body having a base material and a separation functional layer, and disposed so that the surfaces on the base material side face each other;
A plurality of protrusions fixed to the base material side surface of the separation membrane;
A sealing portion that seals between the surfaces of the separation membranes facing each other by an adhesive; and
With
A separation membrane element in which the variation coefficient of the width of the sealing portion at both ends in the width direction of the separation membrane is in the range of 10 to 40%. Consists of a water collecting pipe, an envelope membrane wound around the water collecting pipe and opening toward the water collecting pipe, a sheet disposed on the permeation side surface of the separation membrane, and a plurality of protrusions fixed to the sheet A separation membrane element comprising:
The envelope film is
A separation membrane main body having a base material and a separation functional layer, and disposed so that the surfaces on the base material side face each other;
The permeate-side channel material disposed between the base-side surfaces of the separation membrane;
A sealing portion that seals between the surfaces of the separation membranes facing each other by an adhesive; and
With
A separation membrane element in which the variation coefficient of the width of the sealing portion at both ends in the width direction of the separation membrane is in the range of 10 to 40%.   The separation membrane element according to claim 1 or 2, wherein a ratio of the width of the inner end portion to the width of the outer end portion in the winding direction of the membrane leaf of the sealing portion is 0.4 to 3.5. The separation membrane element according to any one of claims 1 to 3, wherein the protrusions are continuous from the inner peripheral side to the outer peripheral side of the separation membrane.