JPH04250829A - Filter module and its production - Google Patents

Abstract

PURPOSE:To obtain such a filter module containing lots of hollow fiber membranes to be used for purifying water that the module can be used without causing breaking or fracture of the membranes even under high external pressure and to decrease the length of filter where filtering is impossible and to increase the effective the membrane area and filtering efficiency. CONSTITUTION:The one end of a bundle of hollow fiber membranes 1 is sealed with a thermoplastic resin 3 and each membrane is fixed to one another, while the other end is opened and fixed with an adhesive. The thermoplastic resin has higher viscosity than a thermosetting resin and can be cured rapidly, so that the area where filtering is impossible due to the resin sucked by the membrane 1 can be decreased.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is used for purification of tap water and various types of industrial filtration, etc. Specifically, an assembly of a large number of hollow fiber membranes is used for filtration of liquids under external pressure. The present invention relates to a filtration module and a method for manufacturing the same.

0002

[Prior Art] Conventionally known filtration modules of this type include a number of hollow fiber membranes bent into a substantially U-shape, both ends of which are fixed to each other with a thermosetting resin, and each Both ends of the hollow fiber membranes are open, and the central part of each hollow fiber membrane is loop-shaped, so-called loop type. Along with being there,
A so-called end-free type in which the other end of each hollow fiber membrane is sealed with a thermosetting resin, and one end of a large number of hollow fiber membranes is fixed with a thermosetting resin and is open. At the same time, three types of so-called batch seal type, in which the other end of each hollow fiber membrane is sealed and fixed all at once with a thermosetting resin, and both ends of a large number of hollow fiber membranes in the longitudinal direction are fixed, respectively. In addition, there are four types in total, with both ends open and a double-end open type normally used for internal pressure circulation filtration used under external pressure.

0003

[Problem to be Solved by the Invention] Among the four types of filtration modules described above, the loop type type cannot have the radius of curvature of the bent portion very small in terms of the thickness and strength of the hollow fiber membrane. Furthermore, since the effective membrane area per unit volume cannot be made sufficiently large and the pressure resistance of the bent portion is lower than that of the straight portion, there are restrictions on the operating pressure.

[0004] In addition, in the case of the end-free type, the other ends of the many hollow fiber membranes are loose and move freely one by one, so during filtration, the hollow fiber membranes move against each other as the liquid to be treated flows. When entangled, the hollow fiber membranes are easily cut, or the hollow fiber membranes are easily broken due to a prying force acting on one end of the hollow fiber membranes fixed with the thermosetting resin, and productivity is also low.

[0005] In addition, in the batch sealing type, during the process of collectively sealing the other end of each hollow fiber membrane with a thermosetting resin, there is a phenomenon in which the thermosetting resin liquid wicks up into the hollow fiber membrane. cannot be avoided. In other words, in this batch seal type, the other ends of multiple hollow fiber membranes are immersed in a liquid thermosetting resin solution, and the immersion solidifies the resin portion impregnated at the other ends of the hollow fiber membranes. A bulk sealing method is used, but at this time, the resin liquid is sucked up by capillary action inside the thin hollow fiber membrane, and
The end portion of the hollow fiber membrane, which extends over a length of m, is covered with a thermosetting resin and becomes a non-filterable portion. As a result, the effective membrane area is reduced, which is a major problem especially when manufacturing short length filtration modules.

[0006] In addition, when using a double-end open type for internal pressure circulation filtration under external pressure, the opening at one end of the hollow fiber membrane, that is, the side from which the liquid to be treated is not taken out, must be made so that it can withstand the external pressure. It must be sealed, which requires a large cover, which tends to increase the size of the entire filtration device, which is not preferred in practice.

Furthermore, in the above-mentioned end-free type and batch-sealed type, a thermosetting resin is used to seal the other end of each hollow fiber membrane, so the sealing device including the dipping means is simple. Although no liquid stringing phenomenon occurs, it takes time for the thermosetting resin to harden, which causes the above-mentioned wicking phenomenon and creates long unfilterable areas. Moreover, after a certain period of time, the resin liquid solidifies, so it is necessary to discard the solidified resin and refill with new resin liquid, which has been a bottleneck in the automation and continuous production of filtration modules.

[0008] This invention was made in view of the above circumstances, and even when used under high pressure, it does not increase the size of the filtration device or cause the hollow fiber membrane to break or break, and it also reduces the effective membrane area. It is an object of the present invention to provide a filtration module that can be made sufficiently large to improve filtration efficiency, and a method for manufacturing a filtration module that can simplify and manufacture such a filtration module with high productivity.

[0009]

[Means for Solving the Problems] In order to achieve the above object, a filtration module according to the invention as set forth in claim 1 is provided in which one end of a large number of hollow fiber membranes is closed with a thermoplastic resin, and one end of each hollow fiber membrane is closed with a thermoplastic resin. are fixed to each other, the other ends are open, and the other ends are fixed to each other with adhesive.

[0010] Furthermore, in the method for manufacturing a filtration module according to the invention described in claim 2, one end of a large number of hollow fiber membranes is
After being immersed in a molten thermoplastic resin liquid on a hot plate, it is taken out and cooled to solidify, thereby closing one end of the hollow fiber membrane with the thermoplastic resin and fixing the ends to each other. After filling the other ends, fixing the other ends with adhesive, and cutting the part near the other end of the adhesive part and removing it together with the packing part, the other end of the hollow fiber membrane is opened. It is something that makes you

[0011]

[Operation] According to the invention described in claim 1, one end of a large number of hollow fiber membranes is closed with a thermoplastic resin and fixed to each other, and the thermoplastic resin has a higher viscosity than a thermosetting resin. It is possible to obtain a filtration module with a large effective membrane area by shortening the length of the unfilterable part due to the wicking phenomenon.

According to the second aspect of the invention, one end of a large number of hollow fiber membranes is immersed in a thermoplastic resin liquid melted on a hot plate, and then taken out and cooled to solidify, thereby making the resin liquid hollow. It is allowed to sufficiently penetrate into the inside of the fiber membrane, and after being taken out, it is rapidly cured, thereby making it possible to reliably close the opening at one end of each hollow fiber membrane while shortening the length of the non-filterable portion.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a longitudinal side view of the filtration module of the present invention. In the figure, 1 is a polysulfone hollow fiber membrane, and a large number of them are bundled into a cylindrical shape and loaded into a container 2. One ends of the large number of hollow fiber membranes 1 are closed with thermoplastic resin 3, and the ends are fixed to each other. In addition, the above-mentioned large number of hollow fiber membranes 1
As shown in FIG. 2, the other end has an opening 1a, and these other ends are fixed to each other with a thermosetting resin 4 serving as an adhesive.

[0014] The hollow fiber membrane 1 used here may be one that is commercially available, and the materials for the thermoplastic resin 3 and the thermosetting resin 4 may also be commercially available.
In particular, as for the thermoplastic resin, the material may be selected depending on the intended use of the filtration module. For example, if the operating temperature of the filtration module is 70°C, the thermal deformation temperature of the thermoplastic resin material under a load of 4.6 kg/cm2 is 70°C.
If the above-mentioned filtration module is used for processing an aqueous solution, a material with excellent water resistance may be selected.

Next, a method for manufacturing a filtration module having the above-mentioned configuration will be explained. First, as shown in FIG. 3, the hollow fiber membrane bundle 1 is formed by forming the hollow fiber membrane 1 into a bundle, securing the vicinity of both ends with rubber bands 5, 5, and trimming both end surfaces.
Prepare A. On the other hand, the required amount of thermoplastic resin liquid is melted on a hot plate 7 maintained at a predetermined temperature by a heater 6, or the thermoplastic resin liquid 3A melted in a melting tank (not shown) is melted at a predetermined temperature. Hot plate 7 held at temperature
One end of the hollow fiber membrane bundle 1A is immersed in the molten thermoplastic resin liquid 3A for 0.5 to 1.0 seconds, and the thermoplastic resin liquid is applied to one end of each hollow fiber membrane 1. Fill with 3A.

Next, the hollow fiber membrane bundle 1A is taken out and, as shown in FIG. 4, is transferred onto a plate coated with a mold release agent or a fluorine-based plate 8 having mold release properties, and allowed to cool naturally and solidify. As a result, a hollow fiber membrane bundle 1A is obtained in which one end of each hollow fiber membrane 1 is closed and the ends are collectively fixed to each other. The hollow fiber membrane 1A may be placed horizontally as shown in FIG. 4, or may be placed vertically so that the part to which the thermoplastic resin liquid is applied is in contact with the fluorine-based plate 8.

Next, the other end of each hollow fiber membrane 1 on the other end side of the hollow fiber membrane bundle 1A in which one end of each hollow fiber membrane 1 is collectively sealed is packed 11 with a filler. As shown in FIG. 5, the adhesive is loaded into a cylindrical container 2 and an adhesive pot 9, and the container 2 and pot 9 are rotated at high speed around the axis a in FIG. A thermosetting resin liquid 4A is injected into the cylindrical container 2 and the pot 9, and the other ends of each hollow fiber membrane 1 are fixed with the thermosetting resin 4.

After that, after releasing the mold and performing post-curing, as shown in FIG. 6, the unnecessary part formed by centrifugal adhesion is cut and removed together with the filling part 11, so as to form a mold as shown in FIG. , the other end of each hollow fiber membrane 1 is an opening 1a
Obtain a filtration module.

In the filtration module manufactured through the above-described steps, the thickness of the thermoplastic resin 3 at one end of each hollow fiber membrane 1 shown in FIG. 1 is usually 0.5 to 2 mm.
Therefore, the portion not involved in filtration can be greatly reduced.

The hot plate 7 shown in FIG. 3 used in the manufacturing method shown in the above embodiment is preferably coated with a fluorine-based resin for release from the mold during subsequent cleaning. If the thermoplastic resin liquid 3A on the hot plate 7 is likely to deteriorate or crosslink due to oxygen in the air, it is desirable to supply an inert gas such as nitrogen onto the hot plate 7 to keep the oxygen concentration low.

Furthermore, if the viscosity of the molten thermoplastic resin liquid 3A is high, the sealing of one end of the hollow fiber membrane 1 may become incomplete or a stringy state may occur, which is not preferable. It is desirable that the viscosity of the molten resin liquid 3A is low, and JIS K-721
MFR (
It is preferable to raise the temperature to a temperature at which the melt flow rate (melt flow rate) value becomes 20 or more.

Furthermore, even if the operating temperature of the thermoplastic resin liquid 3A exceeds the heat deformation temperature or melting temperature of the hollow fiber membrane 1,
Since the contact portion of one end of the hollow fiber membrane 1 with the thermoplastic resin liquid 3A is local and the contact time is very short,
No particular problems occur.

[0023] Below, the results of an experiment conducted on a filtration module actually produced as a prototype by the present inventor will be explained. 2000 polysulfone hollow fiber membranes having an inner diameter of 450 μm and an outer diameter of 570 μm were bundled together, lightly tied with a rubber band, and then cut with a knife to prepare a hollow fiber bundle with one end aligned and open. At the same time, thermoplastic polyurethane with ether bonds (Kuraray Co., Ltd., Kuramiron #9180) was heated to 260°C on a frying pan coated with fluorine-based resin.
The tips of the aligned openings of the hollow fiber bundle were immersed in the molten polyurethane solution for 1 second, then transferred to a Teflon plate and taken out after 1 minute to obtain a hollow fiber bundle with one end sealed at once. . The thickness of the portion sealed with thermoplastic polyurethane was 1 mm on average. The MFR value of this thermoplastic polyurethane measured at 260°C was 30. The other end of the hollow fiber bundle with one end sealed at once is packed with a filler and loaded into a container with an inner diameter of 35 mm and an adhesive pot, and then centrifugal adhesive is applied using thermosetting polyurethane. The membrane area was reduced to 0.35m2 by cutting off the unnecessary part of the centrifugal adhesive part after mold release and post-curing.
A filtration module with a length of 12 cm was obtained. As a result of a pressure test of this filtration module at 7 kg/cm2 for 24 hours, no leakage occurred and it was found that it was sufficiently durable for practical use.

[0024]

As described above, according to the invention as set forth in claim 1, one end of a large number of hollow fiber membranes is closed with a thermoplastic resin and fixed to each other to be collectively sealed. There is no entanglement caused by the flow of liquid, and cutting and breakage of the hollow fiber membrane can be minimized, and it also has excellent pressure resistance and can be used effectively at sufficiently high working pressures. Furthermore, compared to conventional methods that use thermosetting resin as the resin for closing and fixing one end of the hollow fiber membrane, the curing time is shorter, reducing the length of the unfilterable part due to the resin wicking phenomenon. Can be made smaller. Therefore, in a filtration module configured by loading hollow fiber membranes of the same diameter into a container of the same length as conventional ones, it is possible to increase the effective membrane area and thereby improve the filtration efficiency.

[0025] Furthermore, according to the invention as claimed in claim 2,
By immersing one end of a large number of hollow fiber membranes in a thermoplastic resin liquid melted on a hot plate, and then taking it out and cooling it to solidify, it is a very simple and easy to automate and continuous operation method.
A filtration module with fewer unfilterable parts can be manufactured with high productivity.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal side view of a filtration module of the present invention.

FIG. 2 is an enlarged rear view of the filtration module of FIG. 1;

[Fig. 3] Among the manufacturing steps of the filtration module of the present invention,
FIG. 3 is a diagram showing a step of dipping one end of a hollow fiber membrane bundle into a thermoplastic resin liquid.

FIG. 4 is a diagram showing a cooling solidification process after immersion in a resin liquid.

FIG. 5 is a diagram schematically showing a centrifugal adhesion process.

FIG. 6 is a diagram showing a process of cutting unnecessary parts after centrifugal adhesion.

FIG. 7 is an enlarged side view of one end side of the manufactured filtration module.

[Explanation of symbols]

1...Hollow fiber membrane, 3...Thermoplastic resin, 4...Thermosetting resin (
adhesive), 7... hot plate, 11... filling part.

Claims (2)

[Claims] Claim 1: A filtration system in which one end of a large number of hollow fiber membranes is closed with a thermoplastic resin, one end is fixed to each other, the other end is open, and the other ends are fixed to each other with an adhesive. module. [Claim 2] One end of a large number of hollow fiber membranes is immersed in a thermoplastic resin liquid melted on a hot plate, and then taken out and cooled to solidify, thereby closing one end of the hollow fiber membrane with the thermoplastic resin. , one end is fixed to each other, and the other end of each hollow fiber membrane is packed, the other ends are fixed with adhesive, and the part near the other end of the bonded part is cut to form the above-mentioned stuffed part. A method for manufacturing a filtration module, in which the other end of the hollow fiber membrane is opened by removing the same.