JP2023183524A - spiral membrane element - Google Patents

Abstract

To provide a spiral membrane element that can improve reliability of a sealing structure around the inner peripheral end of a separation membrane.SOLUTION: A spiral membrane element comprises: a hollow central tube 5; wound bodies wound around the central tube 5 and each including a separation membrane 1 bent at an inner peripheral end so that supply-side surfaces face each other and a supply-side flow path material 2 interposed between the surfaces of the separation membrane 1; and sealing portions 13 that each prevent mixing of a supply-side flow path and a permeation-side flow path. The supply-side flow path material 2 has a thickness adjusting portion 2a that is thinner, at least at the inner peripheral end, than at a center.SELECTED DRAWING: Figure 3

Description

The present invention provides a spiral membrane element (hereinafter sometimes abbreviated as "membrane element") that includes a separation membrane bent at the inner peripheral end and a supply channel material interposed between the separation membrane. Regarding.

A conventional spiral membrane element, for example, as shown in FIG. The side channel material 2, the perforated central tube 5 around which the membrane leaf L and the supply side channel material 2 are wound, and the sealing parts 11 and 12 that prevent mixing of the supply side channel and the permeation side channel. , 13 are common.

Such membrane elements include, for example, as shown in FIGS. 2A and 2B, a separation membrane 1 is bent and a supply side channel material 2 is arranged between the two sides facing each other, and a permeate channel material is arranged between the separation membrane 1 and the supply side. 3, and apply adhesives 4 and 6 for forming both end sealing parts 11 and outer peripheral side sealing part 12 to both ends of the permeation side channel material 3 in the axial direction A1 and the outer peripheral side of the winding. After preparing the separation membrane units U whose ends are coated, as shown in FIG. 2C, after stacking the separation membrane units U, the center tube 5 is rotated in the direction of the arrow to stack the plurality of separation membrane units U. It was manufactured by winding it around the central tube 5.

In addition, as described in Patent Document 1, when bending the separation membrane 1, a protective tape is applied to the supply side of the separation membrane 1 along the inner edge in order to protect the bent part. Sometimes it was pasted.

Patent No. 4563060

However, as shown in FIG. 6, when winding the stack of separation membrane units U around the center tube 5, the bending thickness of the inner circumferential end of the separation membrane 1 depends on the thickness of the supply channel material 2. (for example, the radius of curvature) increases, and accordingly, a triangular step S is likely to occur. As a result, gaps are likely to be formed in the central sealing part 13 around the central tube 5 formed by the adhesive applied to the permeate channel material 3, and around the inner peripheral end of the separation membrane 1. There was a concern that the reliability of the sealing structure would decrease. In particular, when a protective tape or the like is provided at the inner end of the supply side of the separation membrane 1, the bending thickness of the inner end of the separation membrane 1 is further increased due to the protective tape, etc. reliability is likely to become a problem.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a spiral-wound membrane element that can improve the reliability of the sealing structure around the inner peripheral end of the separation membrane.

The above object can be achieved by the present invention as follows.

That is, the spiral type membrane element of the present invention includes a perforated central tube, a separation membrane wound around the central tube, and bent at the inner circumferential end so that the supply side faces face each other, and the separation membrane of the separation membrane. A spiral membrane element comprising: a wound body including a supply side channel material interposed therebetween; and a sealing part that prevents mixing of the supply side channel and the permeation side channel material, the spiral membrane element comprising: The channel material is characterized in that it has a thickness adjustment portion that is thinner at least at the inner circumferential end than the center portion.

According to the spiral membrane element of the present invention, the thickness adjustment part of the supply side channel material having a smaller thickness is interposed at the inner circumference side end where the separation membrane is bent, so that the inner circumference side edge of the separation membrane is bent. Since the thickness (e.g. radius of curvature) is reduced, the level difference at the inner end of the multiple separation membranes arranged around the central tube becomes smaller, improving the reliability of the sealing structure around the inner end. can be improved. In addition, since the thickness adjustment part of the supply side channel material is interposed at the inner circumferential end where the separation membrane is bent, the separation membrane is The tip of the thickness adjusting portion can stably enter the bent inner circumferential end. Therefore, the tip of the supply-side channel material is easily arranged at a uniform position, and variations in the sealing structure are less likely to occur, so that the reliability of the sealing structure can be improved.

In the above, it is preferable that the thickness adjustment portion has a shape that becomes thinner toward the distal end. With this configuration, the bending thickness (for example, radius of curvature) at the inner end of the separation membrane is further reduced, so the step difference at the inner end of the plurality of separation membranes arranged around the central tube can be further reduced. Therefore, the reliability of the sealing structure around the inner peripheral end can be further improved.

Further, it is preferable that the supply side channel material has the thickness adjustment portions at the inner circumferential end and the outer circumferential end. In this manner, by providing the thinner thickness adjusting portion also at the outer peripheral end, it is possible to increase the effective membrane area of the separation membrane filled in a spiral-wound membrane element having a constant outer diameter. In this case, since the vicinity of the outer circumferential end of the supply-side channel material is difficult to contribute to the separation function, even if a thickness adjustment part with a smaller thickness is provided, the disadvantage is small. Moreover, the level difference can also be reduced on the outer circumferential surface of the wound body.

Furthermore, in any of the above cases, it is preferable that the supply side surface of the separation membrane is provided with a protective layer provided along the inner circumferential end. By providing a protective layer, it is possible to prevent damage to the inner peripheral end of the separation membrane and maintain a good sealing structure, but the protective layer prevents damage to the inner peripheral end of the separation membrane (for example Although the radius of curvature is likely to increase, by providing a thickness adjusting section as in the present invention, the bending thickness can be reduced and the reliability of the sealing structure can be further improved.

In the above case, it is preferable that the width of the thickness adjusting portion provided at the inner circumferential end is 0.2 to 2 times the length of half the width of the protective layer. When the width of the thickness adjustment portion has such a ratio, the reliability of the sealing structure around the inner circumferential end of the separation membrane can be improved while sufficiently maintaining the separation function of the separation membrane.

According to the present invention, it is possible to provide a spiral membrane element that can improve the reliability of the sealing structure around the inner peripheral end of the separation membrane.

FIG. 2 is a partially cutaway perspective view showing an example of a wound body in which a membrane leaf and a supply side channel material are wound around a central tube. FIG. 2 is a plan view showing an example of a separation membrane unit used in the spiral-wound membrane element of the present invention. FIG. 2 is a front view showing an example of a separation membrane unit used in the spiral-wound membrane element of the present invention. FIG. 2 is a front view showing an example of a state before the separation membrane units used in the spiral membrane element of the present invention are stacked and wound. 1 is a front sectional view showing an example of a main part of a spiral-wound membrane element of the present invention. FIG. 2 is a front sectional view showing an example of a supply side channel material that can be used in the present invention. FIG. 2 is a front sectional view showing an example of a supply side channel material that can be used in the present invention. FIG. 2 is a front sectional view showing an example of a supply side channel material that can be used in the present invention. FIG. 2 is a front sectional view showing an example of a supply side channel material that can be used in the present invention. It is a photograph which shows the example of the thickness adjustment part of the supply side channel material obtained by changing the hot press conditions. FIG. 2 is a front sectional view showing an example of a main part of a conventional spiral-wound membrane element.

(Spiral type membrane element)
As shown in FIG. 1, for example, the spiral membrane element of the present invention includes a central tube 5 having a hole, and is wound around the central tube 5, and is bent at the inner peripheral end so that the supply side faces face each other. a rolled body R including a separation membrane 1 and a supply channel material 2 interposed between the separation membrane 1; and sealing portions 11 and 12 that prevent mixing of the supply channel and the permeate channel. , 13.

In the spiral-wound membrane element of the present invention, as shown in FIG. 3, for example, the supply side channel material 2 has a thickness adjustment part 2a that is thinner at least at the inner circumferential end than the center part. With respect to the points other than the supply side channel material 2, any structure of a conventional spiral-wound membrane element can be adopted.

1 and 3 show an example in which the permeate side channel material 3 is interposed between the opposing separation membranes 1 in the membrane leaf L, but there are irregularities or grooves on the permeate side surface of the separation membrane 1. It is also possible to provide the permeate side flow path in the separation membrane 1 itself, and in that case, the permeate side flow path material 3 can be omitted.

In this embodiment, an example in which the sealing portion includes both end sealing portions 11 and an outer peripheral side sealing portion 12 is shown. Among the sealing parts, the both-end sealing parts 11 are obtained by sealing two side ends of the membrane leaf L on both sides in the axial direction A1 with an adhesive. The outer circumferential side sealing part 12 is obtained by sealing the outer circumferential tip end of the membrane leaf L with an adhesive.

Further, in the present invention, as shown in FIG. 1, it is preferable to have a central sealing part 13 in which both sides of the central tube 5 and the proximal end of the membrane leaf L in the axial direction A1 are sealed with an adhesive. The membrane element of this embodiment has a wound body R in which the membrane leaf L and the supply side channel material 2 are wound around the central tube 5 via such a central sealing part 13.

The membrane element having the wound body R as described above can be manufactured, for example, by the steps shown in FIGS. 2A to 2C. FIG. 2A is a plan view of the separation membrane unit U, FIG. 2B is a front view of the separation membrane unit U, and FIG. 2C is a front view showing a state before the separation membrane units U are stacked and wound.

First, as shown in FIGS. 2A and 2B, the separation membrane 1 is folded in half and bent so that the supply sides face each other, and the supply side channel material 2 is disposed between them, and the permeate side channel material 3 is separated. Stack. Next, adhesives 4 and 6 for forming the both end sealing parts 11 and the outer peripheral side sealing part 12 were applied to both ends of the permeation side channel material 3 in the axial direction A1 and the tip of the winding. Prepare a separation membrane unit U. At this time, a protective layer may be provided by, for example, attaching a protective tape to the folded portion of the separation membrane 1.

The adhesives 4 and 6 are not particularly limited, and conventionally known adhesives can be used. Specifically, any conventionally known adhesives such as urethane adhesives and epoxy adhesives can be used.

Next, as shown in FIG. 2C, the same number of separation membrane units U as the membrane leaves L are stacked on the permeate side flow path material 3 having a portion extending from the other ones, and the separation membrane units U are stacked. Prepare your body. At this time, the central sealing portion 13 can be formed by applying adhesive to both ends in the axial direction A1 of the extended portion of the lowermost permeation-side channel material 3.

Next, as shown in FIG. 2C, the perforated central tube 5 is rotated in the direction of the arrow to wind the plurality of separation membrane units U around the central tube 5. At this time, the adhesives 4 and 6 adhere the opposing separation membrane 1 and permeation side channel material 3, thereby forming a membrane leaf L having both end sealing parts 11 and an outer peripheral side sealing part 12. Ru.

As a result, as shown in FIG. 1, a wound body R is formed in which the membrane leaf L and the supply side channel material 2 are wound around the central tube 5. After sealing, the wound body R may be trimmed at both ends in order to adjust the length in the axial direction A1.

If necessary, an upstream end member such as a seal carrier is provided on the upstream side of the wound body R of the membrane element, and a downstream end member such as an anti-telescope material is provided on the downstream side. Furthermore, it is also possible to provide an exterior material for the purpose of improving pressure resistance.

The exterior material is not particularly limited and may include various sheets, films, tapes, etc., and fiber reinforced resin (FRP) or the like may be used for reinforcement if necessary. As a method for forming the fiber-reinforced resin, it is preferable to use a roving in which fibers are impregnated with a curable resin, and to wrap the roving around the outer periphery of the wound body R.

In a typical spiral-type membrane element with a diameter of 8 inches, about 15 to 30 sets of membrane leaves L are wound, but in the present invention, the center part at least at the inner circumferential end is wound as the supply side channel material 2. Since the thickness adjustment part 2a is used, which is smaller than that of the thickness adjustment part 2a, the effective membrane area per unit volume can be increased. In particular, by using the supply-side channel material 2 having the thickness adjusting portions 2a at the inner circumferential end and the outer circumferential end, the effective membrane area can be further increased.

When the membrane element is used, it is housed in a pressure vessel (vessel), and a supply liquid is supplied from one end surface side of the membrane element. The supplied liquid flows along the supply side channel material 2 in a direction parallel to the axial direction A1 of the central tube 5, and is discharged from the other end surface side of the membrane element as a concentrated liquid. In addition, the permeate that permeates the separation membrane 1 while the supply liquid flows along the supply side channel material 2 flows along the permeate side channel material 3 and then flows into the center pipe 5 from the opening 5a. It flows in and is discharged from the end of this central tube 5.

(Supply side channel material)
As the supply side channel material 2, there is no particular difference from the conventional material except for the provision of the thickness adjustment part 2a, and any conventional material can be used. The supply side channel material 2 generally has the role of ensuring a gap for evenly supplying fluid to the membrane surface. For example, a net, a knitted fabric, a textured sheet, etc. can be used as the supply side channel material 2, and a material having an appropriate thickness can be used as appropriate. In addition, although it is preferable to install channel materials on both sides of the separation membrane 1, different channel materials are used for the supply side channel material 2 provided on the feed liquid side and the permeate side channel material 3 provided on the permeate side. It is common to use It is preferable that the supply side channel material 2 uses a coarse and thick net-like channel material, while the permeation side channel material 3 uses a channel material of fine woven or knitted material.

The present invention is characterized in that, as shown in FIG. 3, for example, as the supply side channel material 2, a material having a thickness adjusting part 2a having a smaller thickness at least at the inner peripheral end than the central part is used. shall be. For example, as shown in FIG. 3, the thickness adjusting part 2a of the supply side channel material 2 is interposed at the inner circumferential end where the separation membrane 1 is bent, so that the bending thickness of the inner circumferential edge of the separation membrane 1 can be adjusted. (For example, the radius of curvature) is reduced, so the step S at the inner peripheral end of the plurality of separation membranes 1 arranged around the central tube 5 becomes smaller, and voids such as adhesives are less likely to occur. , it is possible to improve the reliability of the sealing structure (central sealing part 13) around the inner circumferential end.

In addition, after forming the central sealing part 13 with the adhesive applied before winding, the reliability of the sealing structure can be further improved by applying adhesive or the like to the end face of the wound body R. It is also possible. Even in that case, the reliability of the sealing structure can be further improved by having the thickness adjusting portion 2a at the inner circumferential end.

Here, as shown in FIG. 4D, for example, the thickness adjustment portion 2a may have a portion having a smaller thickness Ta than the thickness T of the central portion of the supply side channel material 2. In the present invention, the "center" of the supply channel material 2 refers to the center between the inner circumferential end and the outer circumferential end of the supply channel material 2, and the center position in the axial direction A1. ing. The area other than the thickness adjustment part 2a of the supply side channel material 2, including the center part of the supply side channel material 2, usually has the same thickness T, but in the present invention, the thickness adjustment part 2a is at least It is sufficient that it is provided at the inner circumferential end, and the thickness T of the supply side channel material 2 may vary in areas other than the thickness adjustment part 2a.

Further, depending on the structure of the supply-side channel material 2, the measured value of the thickness T may differ depending on which part is measured. For example, when the intersection of the wire rods constituting the supply-side flow path material 2 has the maximum thickness of the supply-side flow path material 2, the thickness tends to become smaller in portions other than the intersection. Therefore, in the present invention, the thickness is determined by comparing the same constituent parts in the repeating structure of the supply-side channel material 2. For example, if the maximum thickness part of the supply side channel material 2 in the repeating structure is an intersection part, the thickness of the intersection part of the part that can correspond to the thickness adjustment part 2a is measured, and the part with the smaller thickness is measured. Determine whether it has.

Therefore, in the case of the supply-side channel material 2 having the above-mentioned intersection, the part having the intersection of the wires, which has a smaller thickness than the thickness of the intersection in the center part, becomes the thickness adjustment part 2a. Equivalent to. Further, even when the wire material constituting the supply side flow path material 2 has a wire material having a smaller thickness than the wire material in the central portion, the portion of the wire material having the smaller thickness is in the thickness adjusting portion 2a. corresponds to That is, in the present invention, if there is a portion with a smaller thickness in any of the repeating structures in the supply-side channel material 2, this corresponds to the thickness adjustment portion 2a.

In the present invention, it is sufficient to have such a thickness adjusting part 2a at least at the inner circumferential end, and the shape of the cross section in front view and the repeating structure of the supply side channel material 2 may be any. good. For example, as shown in FIG. 4D, the thickness Ta of the thickness adjustment portion 2a may be constant, but as shown in FIGS. 4A to 4C, it is preferable that the thickness is thinner toward the tip end A2 for the reasons described above. .

Moreover, as shown in FIG. 4A, the tip of the supply side channel material 2 may have a sharp shape, or as shown in FIG. 4B, the tip of the supply side channel material 2 may have a shape consisting of a curved surface. When comparing the two, it is more preferable that the tip of the supply-side channel material 2 has a curved shape from the viewpoint of arranging the tip of the supply-side channel material 2 at a uniform position.

Furthermore, the shape of the thickness adjustment part 2a may be vertically asymmetrical as shown in FIG. 4C, but from the viewpoint of process control of the manufacturing process, it is preferable that the shape of the thickness adjustment part 2a be vertically symmetrical. preferable.

The supply side channel material 2 only needs to have a thickness adjusting part 2a at least at the inner end, and may have a thickness adjusting part 2a only at the inner end, at the inner end and the outer end, or at the inner end. It may be one or both of the section, the outer circumferential end, and both ends in the axial direction A1. In particular, for the reasons mentioned above, it is preferable to have the thickness adjusting portions 2a at the inner circumferential end and the outer circumferential end.

Although the width W and the shape of the front view cross section of the thickness adjustment portion 2a may vary somewhat, it is preferable that the width W and the shape of the cross section in front view be constant or approximately constant from the viewpoint of making it difficult to cause variations in the sealing structure.

The width W of the thickness adjusting portion 2a at the inner circumferential end is preferably 3 mm or more, more preferably 5 mm or more, from the viewpoint of the bending thickness reduction effect and the stability of the sealing structure. Further, the width W of the thickness adjustment portion 2a is preferably 30 mm or less, more preferably 20 mm or less, from the viewpoint of maintaining a good separation function.

The width W in the case where the thickness adjustment portion 2a is provided at the outer circumferential end is preferably 3 mm or more, and more preferably 5 mm or more, from the viewpoint of reducing the level difference on the outer circumferential surface. Further, the width W of the thickness adjustment portion 2a at the outer peripheral end is preferably 30 mm or less, more preferably 20 mm or less, from the viewpoint of maintaining a good separation function. Note that the width W of the thickness adjusting portion 2a at the outer peripheral end and the width W of the thickness adjusting portion 2a at the inner peripheral end may be the same or different.

For example, in the case of applications such as seawater desalination and wastewater treatment using RO membranes and NF membranes, it is preferable to use as the supply side channel material 2 a material with a mesh structure in which linear objects are arranged in a lattice pattern. .

Although the constituent material is not particularly limited, polyethylene, polypropylene, etc. are used. These resins may contain bactericides and antibacterial agents. The thickness of the supply channel material 2 is generally 0.3 to 3.0 mm, preferably 0.5 to 1.0 mm. If the thickness is too thick, the amount of permeation will decrease as well as the effective membrane area that can be accommodated in the membrane element, while if it is too thin, contaminants will easily adhere to it, which will likely cause deterioration in permeation performance.

From the viewpoint of further improving the reliability of the sealing structure, the thickness adjusting part 2a of the supply side channel material 2 has a thickness of at least 50% or less of the thickness of the supply side channel material 2. It is preferable to have a thickness of 30% or less in at least a part, it is more preferable to have a thickness of 20% or less in at least a part.

As a method of forming the thickness adjustment part 2a in the supply side channel material 2, a method of forming the thickness adjustment part 2a when manufacturing the supply side channel material 2 of a constant width may be used, but from the viewpoint of manufacturing efficiency, A preferred method is to cut the supply-side channel material 2 having a constant thickness into a constant width or a predetermined shape, and then form the thickness adjusting portions 2a at one or more target ends. After cutting the supply side channel material 2 to a certain width, it is also possible to form the thickness adjustment portion 2a at one or both ends by continuous processing.

The thickness adjustment portion 2a may be formed by any method such as heating and pressing, heating and deformation, grinding, polishing, and ultrasonic treatment, but heating and pressing such as heating and roll pressing, ultrasonic pressing, etc. may be used. Ultrasonic treatment is preferred.

Specifically, as shown in FIG. 5, for example, the thickness adjustment portions 2a having different thicknesses can be formed by heating pressing a mesh-structured net under various conditions. The example shown in Fig. 5 uses a diamond-shaped net made of polypropylene (PP) (thickness at the intersection part: 0.86 mm), and the conditions for hot pressing are a press load of 80 kgf, a press width of 15 mm, and temperature and time. Instead, it is heated and pressed.

As shown in FIG. 5, it can be seen that the intersection points are crushed and the thickness becomes smaller, and it can be confirmed that the longer the time at high temperature, the thinner the thickness becomes. In other words, the thickness adjustment portion 2a having a desired thickness can be formed by changing the hot pressing conditions depending on the material and structure of the supply side channel material 2. For example, the thermal deformation onset temperature of polypropylene is 60 to 65°C, but in the case of polyethylene, it is 30 to 50°C, so the thickness adjustment portion 2a can be formed by heating and pressing at a lower temperature.

In addition, after hot pressing, the end sides are cut and trimmed so that the end sides become straight, or the length of the tip of the thickness adjustment part 2a is adjusted to obtain the supply side channel material having the desired width. It is also possible to set it to 2.

(central tube)
The center tube 5 may be of any type as long as it has an opening 5a around the tube, and any conventional type can be used. Generally, when used in seawater desalination, wastewater treatment, etc., permeated water that has passed through the separation membrane 1 enters the central pipe 5 through the holes in the wall surface, forming a permeate side flow path. Although the length of the central tube 5 is generally longer than the axial length of the wound body R, the central tube 5 may have a connected structure, such as being divided into a plurality of parts. The material constituting the central tube 5 is not particularly limited, but thermosetting resin or thermoplastic resin is used.

(Permeation side channel material)
As the permeation side channel material 3, any conventional material can be used. When using RO membranes or NF membranes in applications such as seawater desalination or wastewater treatment, the permeation side channel material 3 is inserted between opposing separation membranes 1 in the membrane leaf L, as shown in FIG. 1, for example. It is set up so that This permeate-side channel material 3 is required to support the pressure applied to the membrane from the back side of the membrane and to secure a channel for the permeate.

In order to ensure such a function, it is preferable that the permeation side channel material 3 is formed of a tricot knitted fabric, and more preferably a tricot knitted fabric that has been subjected to resin reinforcement or fusion treatment after the knitted fabric is formed.

Examples of the constituent threads of the permeation side channel material 3 include polyesters such as polyethylene terephthalate and polyethylene naphthalate, and polyolefins such as polyethylene and polypropylene. Among these, polyethylene terephthalate is particularly preferably used from the viewpoint of processability and productivity.

When reinforcing with resin after forming the knitted fabric, examples include methods of impregnating the fibers with a resin and curing them, or coating the fiber surfaces with a resin and curing them. Examples of resins used for reinforcement include melamine resins and epoxy resins.

The constituent threads of the permeation side channel material 3 may be monofilament or multifilament, but the constituent threads of a certain thickness form a tricot knitted fabric. Among tricot knits, half knits and double denby knits, which have a clear structure of continuous linear grooves, are preferred.

The thickness of the permeation side channel material 3 is preferably 0.10 to 0.40 mm, more preferably 0.15 to 0.35 mm, and even more preferably 0.20 to 0.30 mm. When the thickness is 0.10 mm or more, a sufficient flow path is ensured and the pressure loss of the permeate can be reduced. Moreover, when the thickness is 0.40 mm or less, the effective membrane area of the separation membrane in the membrane element becomes large, making it easier to increase the flow rate of the permeate. The constituent threads of the permeation side channel material 3 are preferably 0.1 to 0.15 mm in order to form a tricot knitted fabric with the above-mentioned thickness.

Although the permeation side channel material 3 may be arranged in any direction in the membrane element, it is preferable that the direction of the linearly continuous grooves be wound in the direction along the circumferential direction.

(separation membrane)
As the separation membrane 1, any conventional membrane can be used. For example, various porous membranes can be used, but a composite semipermeable membrane having a separation functional layer on the surface of a porous support is preferred. The porous support preferably has a nonwoven fabric layer and a porous polymer layer on one side. The thickness of the separation membrane, especially the composite semipermeable membrane, is preferably about 70 to 160 μm, more preferably 85 to 130 μm.

These composite semipermeable membranes are called RO (reverse osmosis) membranes, NF (nano filtration) membranes, and FO (forward osmosis) membranes depending on their filtration performance and processing method, and are used in ultrapure water production and seawater desalination. It can be used for desalination of brine, reuse of wastewater, etc.

Examples of the separation functional layer include polyamide-based, cellulose-based, polyether-based, and silicone-based separation functional layers, and those having a polyamide-based separation functional layer are preferred. The polyamide-based separation functional layer is generally a homogeneous membrane without visible pores and has a desired ion separation ability. This separation functional layer is not particularly limited as long as it is a polyamide thin film that is difficult to peel off from the porous polymer layer. Polyamide-based separation functional layers formed by polymerization are well known.

The method for forming the polyamide-based separation functional layer on the surface of the polymer porous layer is not particularly limited, and any known method can be used. Examples include methods such as interfacial polymerization, phase separation, and thin film coating, and interfacial polymerization is particularly preferably used in the present invention. In the interfacial polymerization method, for example, after a porous polymer layer is coated with an amine aqueous solution containing a polyfunctional amine component, interfacial polymerization occurs by bringing an organic solution containing a polyfunctional acid halide component into contact with the surface coated with the amine aqueous solution. This is a method of forming a skin layer.

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

The polyfunctional acid halide component contained in the organic solution is a polyfunctional acid halide having two or more reactive carbonyl groups, and includes aromatic, aliphatic, and alicyclic polyfunctional acid halides. Examples of the aromatic polyfunctional acid halides include trimesic acid trichloride, terephthalic acid dichloride, isophthalic acid dichloride, biphenyldicarboxylic acid dichloride, naphthalene dicarboxylic acid dichloride, benzenetrisulfonic acid trichloride, benzenedisulfonic acid dichloride, and chlorosulfonylbenzene. Examples include dicarboxylic acid dichloride. Examples of the aliphatic polyfunctional acid halides include propanedicarboxylic acid dichloride, butanedicarboxylic acid dichloride, pentanedicarboxylic acid dichloride, propanetricarboxylic acid trichloride, butanetricarboxylic acid trichloride, pentanetricarboxylic acid trichloride, glutaryl halide, Examples include poil halide. Examples of the alicyclic polyfunctional acid halides include cyclopropanetricarboxylic acid trichloride, cyclobutanetricarboxylic acid tetrachloride, cyclopentanetricarboxylic acid trichloride, cyclopentanetricarboxylic acid tetrachloride, cyclohexanetricarboxylic acid trichloride, and tetrahydrocarboxylic acid trichloride. Examples include furantetracarboxylic acid dichloride, cyclopentanedicarboxylic acid dichloride, cyclobutanedicarboxylic acid dichloride, cyclohexanedicarboxylic acid dichloride, and tetrahydrofurandicarboxylic acid dichloride. These polyfunctional acid halides may be used alone or in combination of two or more. In order to obtain a skin layer with high salt blocking performance, it is preferable to use an aromatic polyfunctional acid halide. Further, it is preferable to form a crosslinked structure by using a trivalent or higher valence polyfunctional acid halide as at least a part of the polyfunctional acid halide component.

The organic solvent containing the polyfunctional acid halide is not particularly limited as long as it has low solubility in water and dissolves the polyfunctional acid halide component without deteriorating the porous support membrane, such as cyclohexane, Examples include saturated hydrocarbons such as heptane, octane, and nonane, and halogen-substituted hydrocarbons such as 1,1,2-trichlorotrifluoroethane. Saturated hydrocarbons preferably have a boiling point of 300°C or lower, more preferably 200°C or lower.

Additives may be added to the amine aqueous solution or organic solution for the purpose of improving various performances and handling properties. Examples of the additive include polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid, polyhydric alcohols such as sorbitol and glycerin, and surfactants such as sodium dodecylbenzenesulfonate, sodium dodecylsulfate, and sodium laurylsulfate. , a basic compound such as sodium hydroxide, trisodium phosphate, and triethylamine for removing hydrogen halide produced by polymerization, an acylation catalyst, and a solubility parameter of 8 to 14 (cal) as described in JP-A-8-224452. /cm ³ ) ^1/2, and the like.

A coating layer made of various polymer components may be provided on the exposed surface of the separation functional layer. The polymer component is not particularly limited as long as it does not dissolve the separation functional layer and the porous support membrane and does not dissolve during water treatment operations, and includes, for example, polyvinyl alcohol, polyvinylpyrrolidone, hydroxypropyl cellulose, and polyethylene. Examples include glycol and saponified polyethylene-vinyl acetate copolymer. Among these, it is preferable to use polyvinyl alcohol, and in particular, by using polyvinyl alcohol with a saponification degree of 99% or more, or by crosslinking polyvinyl alcohol with a saponification degree of 90% or more with the polyamide resin of the skin layer, It is preferable to have a structure that makes it difficult to elute during water treatment. By providing such a coating layer, the charge state of the membrane surface is adjusted and hydrophilicity is imparted, so that it is possible to suppress the adhesion of contaminants, and furthermore, due to the synergistic effect with the present invention, the flux retention effect is improved. can be further increased.

The nonwoven fabric layer used in the present invention is not particularly limited as long as it maintains the separation performance and permeation performance of the composite semipermeable membrane and provides appropriate mechanical strength, and commercially available nonwoven fabrics may be used. be able to. As this material, for example, a material made of polyolefin, polyester, cellulose, etc. is used, and a mixture of a plurality of materials can also be used. Particularly from the viewpoint of moldability, it is preferable to use polyester. Further, a long fiber nonwoven fabric or a short fiber nonwoven fabric can be used as appropriate, but a long fiber nonwoven fabric can be preferably used from the viewpoint of fine fuzz that causes pinhole defects and uniformity of the film surface.

The polymer porous layer is not particularly limited as long as it can form the polyamide separation functional layer, but it is usually a microporous layer having a pore diameter of about 0.01 to 0.4 μm. Examples of the material for forming the microporous layer include various materials such as polysulfone, polyarylethersulfone exemplified by polyethersulfone, polyimide, and polyvinylidene fluoride. In particular, it is preferable to form a polymer porous layer using polysulfone or polyarylether sulfone from the viewpoint of chemical, mechanical, and thermal stability.

(protective layer)
It is preferable that the supply side surface of the separation membrane 1 is provided with a protective layer provided along the inner circumferential end (bending part). Such a protective layer makes it possible to make the separation membrane 1 less likely to be damaged than when the separation membrane 1 at the bent portion is exposed to the supply side.

The protective layer is preferably formed such that both ends of the protective layer are parallel to the center line of the bent part on the supply side of the separation membrane 1, and the center line of the bent part is arranged at the center of the protective layer. It is more preferable.

The width of the protective layer is, for example, 25 to 50 mm. In the present invention, the width W of the thickness adjusting portion 2a provided at the inner peripheral end is preferably 0.2 to 2 times, and 0.3 to 1.5 times, the length of half the width of the protective layer. The amount is more preferably 0.5 to 1 times, even more preferably 0.5 to 1 times. When the width W of the thickness adjustment portion 2a has such a ratio, the reliability of the sealing structure around the inner peripheral end of the separation membrane 1 is improved while the separation function of the separation membrane 1 is sufficiently maintained. be able to.

Examples of such a protective layer include adhesive tape, film adhesion, resin coating, etc., but it is preferable to use adhesive tape from the viewpoint of simplicity of the forming process and elution property of the material.

The thickness of the protective layer is, for example, 25 to 100 μm, but the thicker the protective layer is, the more the effect of reducing the bending thickness (for example, radius of curvature) by the thickness adjustment part 2a provided at the inner peripheral end becomes more effective. validate.

(Another embodiment of spiral-wound membrane element)
In the above description, the most preferred embodiment of the present invention has been described. However, the present invention is not limited to this embodiment, and various modifications can be made within the technical idea described in the claims of the present invention.

That is, in the embodiment described above, as shown in FIGS. 2A to 2C, the permeate side channel material 3 is stacked on top of the separation membrane 1 which is folded in half so as to sandwich the supply side channel material 2. An example in which adhesives 4 and 6 are applied has been described. However, in the present invention, it is also possible to stack the separation membrane 1 folded in half on the permeation side channel material 3 and apply the adhesives 4 and 6 thereon. Furthermore, the outer peripheral side sealing part 12 may be made unnecessary by using the continuous separation membrane 1.

According to the present invention, it is possible to provide a spiral membrane element that can improve the reliability of the sealing structure around the inner peripheral end of the separation membrane. Therefore, the spiral-wound membrane element of the present invention can be suitably used in various applications such as ultrapure water production, seawater desalination, brine desalination treatment, and wastewater reuse treatment.

1: Separation membrane 2: Supply side channel material 2a: Thickness adjustment section 3: Permeate side channel material 5: Center tube 13: Center side sealing section (sealing section)
A1: Axial direction R: Wound body T: Thickness of supply side channel material Ta: Thickness of thickness adjustment section W: Width of thickness adjustment section S: Step

Claims (5)

A perforated central tube, a separation membrane wound around the central tube and bent at the inner peripheral end so that the supply sides face each other, and a supply side channel material interposed between the separation membrane. A spiral-wound membrane element comprising: a wound body including a wound body; and a sealing part that prevents mixing of a supply side flow path and a permeation side flow path,
The supply side channel material is a spiral type membrane element having a thickness adjustment portion that is thinner at least at the inner end portion than the center portion. The spiral-wound membrane element according to claim 1, wherein the thickness adjustment portion has a shape that becomes thinner toward the tip end. The spiral-wound membrane element according to claim 1, wherein the supply side channel material has the thickness adjustment portion at the inner peripheral end and the outer peripheral end. The spiral-wound membrane element according to any one of claims 1 to 3, wherein the supply side of the separation membrane is provided with a protective layer provided along the inner circumferential end. The spiral-wound membrane element according to claim 4, wherein the width of the thickness adjustment portion provided at the inner peripheral end is 0.2 to 2 times the length of half the width of the protective layer. .