JP2000279771A - Production of fluid separation element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the damage of separation membranes in a production process and to exhibit stable desalting performance by imparting a lubricant to at least either of a feed flow passage and the separation membranes when superposing and wrapping a feed flow passage material, the separation membranes and a permeate flow passage material to a water collecting pipe. SOLUTION: The fluid separation element is constituted by inserting the permeate flow passage material 5 between the two separation membranes 3 and 4. The feed 10 supplied from one end face 7 of the fluid separation element is treated with both separation membranes 3 and 4. Part of the permeate 11 permeated through the separation membranes 3 and 4 is taken out of the water collecting pipe 1 and on the other hand, the feed 10 failing to permeate the separation membranes 3 and 4 is discharge as concentrated water 12 from the other end face 8. In such a case, the lubricant capable of lowering the coefficient of friction to the separation membranes 3 and 4 of the feed flow passage material 6 is imparted to at least either thereof to lower the friction between both when the separation membranes 3 and 4 holding the permeate flow passage material 5 and the feed flow passage material 6 are superposed and wrapped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a fluid separation element, and more particularly, to a method for manufacturing a fluid separation element suitably used in a reverse osmosis device, an ultrafiltration device, a microfiltration device, and the like.

[0002]

2. Description of the Related Art In recent years, in seawater desalination and ultrapure water production in the semiconductor field, a single or plural membrane units including a separation membrane sandwiching a permeate flow path material and a supply liquid flow path material have been developed. A fluid separating element spirally wound around the collecting pipe is used. In general, the supply liquid flow path material of the fluid separation element is required to have a low flow resistance for uniformly supplying the supply liquid to the membrane surface, and a plastic net is used. However, since the feed liquid flow path material is in contact with the separation membrane, friction occurs between the feed liquid flow path material and the separation membrane in the above-mentioned winding step, and the feed liquid flow path material damages the separation membrane, and the As a result, there has been a problem that the fluid separation element cannot provide stable desalination performance.

[0003] For this reason, in order to prevent damage to the separation membrane, attempts have been made to change the material of the net and the cross-sectional shape and thickness of the yarns constituting the net. Even the types of nets have some differences in shape, etc. between lots at the time of purchase, so that stability cannot be obtained and sufficient effects cannot be obtained. In addition, a change in the material reduces heat resistance, chemical resistance, and the like, which may cause a change in characteristics and performance of the fluid separation element.

On the other hand, JP-A-8-192033 discloses that a protective film is provided on a separation film itself to prevent damage. However, in this method, when the thickness of the protective film is large, the resistance between the net and the film surface is large, so that it is difficult to surround the film, and wrinkles are generated in the separation film at the time of the surrounding. Therefore, it is necessary to form the protective film thinly.
There is a problem that it is also difficult to form the film uniformly.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for easily manufacturing a fluid separation element capable of exhibiting stable desalination performance by reducing damage to a separation membrane in a manufacturing process.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a method for supplying a supply liquid flow path material, a separation membrane and a permeate flow path material to a water collecting pipe in a superposed manner. And a method for manufacturing a fluid separation element in which a lubricant is applied to at least one of the separation membranes.

[0007] At this time, it is preferable to use a surfactant as a lubricant, and more preferably an anionic surfactant.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fluid separation element according to the present invention has a structure in which a permeated liquid channel material 5 is sandwiched between a first separation membrane 3 and a second separation membrane 4, as shown in FIG. The first separation membrane 3 and the second separation membrane 4 are adhered to each other at three sides so as to open only in the direction of the water collecting pipe 1, and are formed in an envelope shape. Then, the envelope membrane and the supply liquid flow path material 6 in which the permeate liquid flow path material 5 is interposed are formed as one unit, and one or a plurality of the units are spirally wound around the water collecting pipe to form the fluid separation element. Form. Such a fluid separation element is provided with a supply liquid 1 supplied from an end face 7 of the fluid separation element.
0 is treated with the first separation membrane 3 and the second separation membrane 4.
Part of the permeated liquid 11 that has passed through the separation membranes 3 and 4
The supply liquid 10 that has been taken out of the separation membrane 3 and has not passed through the separation membranes 3 and 4 is discharged from the other end face 8 of the fluid separation element as the concentrated liquid 12.

Here, in the present invention, when the separation membrane sandwiching the permeate flow path material and the supply liquid flow path material are superposed and wound, the friction coefficient of the supply liquid flow path material with respect to the separation membrane is reduced. The lubricant that can be applied is applied to at least one of the supply liquid flow path material and the separation membrane to reduce friction between the membrane surface and the supply liquid flow path material.

[0010] As the lubricant, a surfactant which can be easily washed away by washing after molding the fluid separation element is preferable. As long as the lubricant is applied to the supply liquid flow path material even at the time of winding, damage to the separation membrane can be prevented. Also,
After forming the fluid separation element, the lubricant is washed away by simple washing, so that the adverse effect of the lubricant during fluid separation can be prevented.

In general, the solute to be separated has an anionic property, and an anionic property is imparted to the membrane in order to separate the solute. cause. Therefore, in order to maintain the anionicity of the film, it is preferable to use an anionic surfactant. More preferably, it is an anionic surfactant having a long-chain alkyl group, and further preferably, sodium dodecyl sulfate. On the other hand, if the solute to be separated is a cationic solute, it imparts cationicity to the separation membrane.
It is desirable to use a cationic surfactant in order to maintain the cationicity of the membrane.

The surfactant is preferably diluted with pure water for use, and its concentration is preferably 0.01 to 10% by weight. More preferably, it is 0.05 to 5% by weight, and still more preferably 0.1 to 1% by weight. If the amount is less than 0.01% by weight, the surface of the feed liquid channel material cannot be sufficiently covered with the surfactant,
If it exceeds 10% by weight, it takes time to wash out the surfactant used after molding the fluid separation element.

The supply liquid flow path material is preferably a plastic net, more preferably a net of polypropylene, polyester, polyethylene, nylon or the like, which is available at a low cost. The shape of the net has a thickness of 0.5 to 0.5 in order to reduce the flow path resistance to the supply liquid.
It is preferable that the distance is in the range of 1.0 mm and the pitch of the entanglement points of the net is 1.5 to 4.5 mm.

[0014]

EXAMPLE 1 100 kg of a 1% by weight sodium dodecyl sulfate solution containing 1 kg of sodium dodecyl sulfate in pure water was entangled at a pitch of 3.8 × 3.8 mm and net thickness 0.8 mm.
Was immersed for 5 seconds. Next, as shown in FIG. 2, the net 31 is placed on a reverse osmosis membrane 30 (for example, a separation membrane used for SU-720 manufactured by Toray Industries, Inc.), and a 329 g weight 32 is placed thereon. Was. A thread 33 was attached to the net 31 and pulled in the horizontal direction by a spring 34, and the scale at the time when the net 31 first moved was read to measure the static friction coefficient μ.
As a result, the coefficient of static friction μ = 0.27.

Next, the performance of the fluid separation element using the polyethylene net treated as described above as a feed liquid flow path material was measured. The raw water was 1500 ppm of NaCl.
And the operation pressure was 15 kg / cm ² . As a result, the desalting rate was 99.0% and the flux was 22 m ³ /
It was a day. Table 1 shows the results. Comparative Example The same measurement as in Example 1 was performed except that the polyethylene net was not immersed in a 1% by weight aqueous solution of sodium dodecyl sulfate. As a result, the friction coefficient μ = 0.69, the desalting rate was 98.0%, and the flux was 22 m ³ / day. Table 1 shows the results.

[0016]

[Table 1]

As described above, by dipping the net in the aqueous solution of sodium dodecyl sulfate, the static friction coefficient of the net is
It was possible to reduce the size of the net not immersed in the aqueous sodium dodecyl sulfate solution to about 40%.

[0018]

According to the present invention, when the supply liquid flow path material, the separation membrane and the permeate flow path material are superposed and wound around the water collecting pipe, a lubricant is applied to at least one of the supply liquid flow path material and the separation membrane. Since it is applied, friction between the supply liquid flow path material and the membrane surface of the separation membrane can be reduced, and damage to the membrane surface can be prevented.

At this time, if a surfactant is used as the lubricant, it can be easily washed away after the formation of the fluid separation element, and the adverse effect of the lubricant at the time of fluid separation can be prevented. When an anionic surfactant is used as the lubricant, the anionicity and desalting performance of the membrane can be maintained.

[Brief description of the drawings]

FIG. 1 is a schematic partial development view of a fluid separation element manufactured according to an embodiment of the present invention.

FIG. 2 is a schematic model diagram showing a method of measuring a static friction coefficient in an example.

[Explanation of symbols]

 1: Water collecting pipe 3: First separation membrane 4: Second separation membrane 5: Permeate flow path material 6: Supply liquid flow path material 7: End face 8: End face 10: Supply liquid 11: Permeate liquid 12: Concentrate 30: reverse osmosis membrane 31: net 32: weight 33: thread 34: spring only

Claims (3)

[Claims] When a supply liquid flow path material, a separation membrane and a permeate flow path material are superposed and wound around a water collection pipe, a lubricant is applied to at least one of the supply liquid flow path material and the separation membrane. A method for manufacturing a fluid separation element. 2. The method according to claim 1, wherein a surfactant is used as the lubricant. 3. The method according to claim 1, wherein an anionic surfactant is used as the lubricant.