JPH0410375B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hollow fiber module. More specifically, the adhesive sealing part has a structure in which non-flexible adhesive, flexible adhesive, and non-flexible adhesive are arranged in the order of annual rings from the inner surface of the case toward the center, making it resistant to peeling. This invention relates to a hollow fiber module with significantly improved properties.

The semipermeable membrane module, which is the heart of reverse osmosis and ultrafiltration equipment, is of various types depending on the application, and one of them, the hollow fiber module, is compact and It is widely used in various fields because of its advantages such as a small priming volume.

This hollow fiber module has a length of 300 to 1000 mm,
Several thousand to tens of thousands of hollow fibers with an outer diameter of 0.1 to 1 mmφ are bundled together, inserted into a cylindrical case, and the ends are adhesively sealed using a non-flexible epoxy adhesive. After curing. , cut to open the end face and for trimming, and attach the cap by gluing, welding, or screwing,
Manufactured.

(Prior Art) Conventionally, epoxy adhesives have been used alone to adhesive the ends of hollow fiber modules.

(Problems to be Solved by the Invention) However, since this epoxy adhesive generates a large amount of self-heating during curing, if a large amount is used, temperature distribution will occur, resulting in uneven curing. As a result, strain will accumulate within the cured adhesive.

In addition, epoxy adhesives are inflexible and have a relatively high shrinkage rate, so a large amount of adhesive is used, especially in large-diameter hollow fiber modules, which inevitably leads to large internal distortions. However, there were problems such as peeling between the case and the adhesive.

This kind of peeling between the case and the adhesive occurs not only during module manufacture, but also during use, especially due to temperature changes when heat sterilization is performed or cold water is used to process and clean relatively high-temperature liquids. When exposed to water, peeling often occurred due to the difference in expansion and contraction rates between the case and the adhesive. Such peeling of the hollow fiber type module causes a fatal trouble in practical use.

This is because, in a system that uses many hollow fiber modules, if even one module is in this condition, it will take time to find the problem, and even if the leaking module is replaced, it will not be possible to repair the contaminated system. It will take a long time to clean.

Particularly in liquid processing equipment for the purpose of sterilization, even a small leakage causes a problem because even a small amount of leaked bacteria will multiply, spreading contamination to the entire system.

In view of this situation, the present inventors have completed the present invention as a result of intensive studies.

(Structure of the Invention) That is, the present invention provides a hollow fiber bundle in which a cylindrical case is filled with a hollow fiber bundle, and the ends of the hollow fiber bundle and the case end are adhesively sealed. It is a thread type module, and the adhesive composition of the cross section perpendicular to the module length direction of the adhesive sealing part is composed of non-flexible adhesive, flexible adhesive, and non-flexible adhesive from the inner surface of the cylindrical case toward the center. This is a "hollow fiber module" characterized by the fact that adhesives are arranged in the order of growth rings. The key point of the present invention is to create an annual ring-like structure in which a flexible adhesive is sandwiched between non-flexible adhesives at the adhesive sealing part of the hollow fiber module, especially at the adhesive sealing part with the cylindrical case. The elasticity of the flexible adhesive maintains durability against thermal shock and mechanical shock while maintaining adhesive strength between the hollow fibers and the adhesive layer.

When a thermal shock is applied to a hollow fiber module, the case and adhesive layer expand and contract repeatedly, and even if the adhesive layer has heat resistance, if it is only a non-flexible adhesive, the elasticity of the adhesive layer itself will increase. Since there is almost no shock absorption, the case and adhesive layer eventually peel off. Furthermore, although flexible adhesives can absorb thermal shock, many of them lack adhesive strength with the case, which is a different material, when heated at high temperatures. However, at this high temperature, even if the adhesive is a flexible adhesive that has weak adhesion to the case, even if it is a different adhesive, when adhering to the same type of material (adhesive and adhesive), the adhesive strength will be weaker than the case. Since the adhesive strength is much larger than that when adhering to different types of materials, the adhesion strength at high temperatures is hardly affected. Therefore, a non-flexible adhesive with strong adhesive strength at high temperatures is used to bond the case or hollow fiber, which is a different material from the adhesive layer, and a flexible adhesive is used to bond the adhesives together. The hollow fiber module of the present invention using the adhesive overcomes the drawbacks of both adhesives and takes advantage of the advantages of both, resulting in greatly improved heat resistance and thermal shock resistance.

In the present invention, the non-flexible adhesive used to bond only the ends of the hollow fiber bundle or only the case may be a conventional epoxy adhesive with high heat resistance. Flexible adhesives for the purpose of absorption include adhesives that are flexible after curing, specifically adhesives with siloxane bonds, epoxy adhesives with natural rubber or synthetic rubber skeletons, and dimer acid skeletons. An epoxy adhesive having a

The flexible adhesive described in the present invention is one that has a hardness of Shore hardness of 65 or less and an elongation rate of 20% or more after curing, and has a hardness of Shore hardness of 50 or less and an elongation rate of 50 to 50%.
Particularly preferred is about 300%. Note that the elongation rate of the epoxy adhesive, which is a non-flexible adhesive, is about 5% at most.

The larger the thickness of this flexible adhesive layer in the cross-sectional direction of the case, the greater its ability to absorb volume changes due to expansion and contraction; however, if it is too large, the pressure resistance in the longitudinal direction of the module case will be affected. It lacks. Therefore, the thickness of the hollow fiber module,
In particular, it is preferably 1 to 5 mm, although it depends on the inner diameter of the case and the filling rate of the hollow fibers.

Further, the thinner the thickness of the non-flexible adhesive layer sandwiched between the case and the flexible adhesive in the cross-sectional direction of the case, the better.

The purpose of this part is simply to improve the adhesive strength between the case and the flexible adhesive layer at high temperatures, so if this layer is thick, it will not easily deform by itself, which is the disadvantage of non-flexible adhesives. Because it comes out strongly, it becomes vulnerable to thermal and mechanical shock, and there is a risk of it separating from the case. Therefore, the thickness of this layer is preferably 2 mm or less, although it depends on the hardness of the adhesive itself.

The structure of the adhesive layer of the hollow fiber module of the present invention will be explained with reference to FIGS. 1 and 2. FIG. 1 is a longitudinal cross-sectional view of a hollow fiber module according to the present invention, showing the end adhesive sealing portion. FIG. 2 shows a cross section taken along line A-A' in FIG. In Figures 1 and 2, 1-1 is a hollow fiber, 2-2 is a non-flexible adhesive, 3-3 is a flexible adhesive, 4-4 is a non-flexible adhesive, and 5-5
is a cylindrical case, and 6-6 is a space between the hollow fiber and the case, and in many ultrafiltration modules, this is the passage for the permeate. 7-7 is inside the end cap of the module and is the bulk solution passageway in many ultrafiltration modules.

Next, a method for manufacturing the hollow fiber module according to the present invention will be described. First, apply an inflexible adhesive (regular epoxy adhesive) that has strong adhesion even at high temperatures to about 30 mm from both ends of the prepared cylindrical case and harden it. .

Next, a rectangular sheet made of a material that does not adhere with any adhesive, such as silicone rubber or Teflon, is fitted into the inner periphery of the end of the case to form an annular body. The rectangular silicone rubber or Teflon sheet used at this time has a width of 40 to 50 mm and a length that is approximately the same as the inner circumference of the cylindrical case, that is, an inner diameter of 100 mm.
In the case of a cylindrical case of about mm size, it is about 314 mm.
The thickness is approximately equal to the thickness of the flexible adhesive layer described later, and a thickness of 1 to 5 mm is selected.

Next, several thousand hollow fibers are bundled together, a bundle of fibers with approximately the same length as the cylindrical case is inserted into the bundle, and temporary caps are attached to both sides. For example, in the case of a centrifugal method, this is set in a centrifugal adhesive sealing device, and a predetermined amount of non-flexible adhesive (ordinary epoxy adhesive) is injected and activated, and the device is continuously cured for a certain period of time.

After stopping, the hollow fiber type module intermediate is taken out, the temporary cap is removed, and the annular strip-shaped sheet is taken out. This strip-shaped sheet can be easily removed without using adhesive.

Next, the temporary cap is attached again and set in the centrifugal adhesive sealing device, and this time the centrifugal device is operated while injecting a predetermined amount of flexible adhesive. The flexible adhesive injected at this time enters the annular gap formed after taking out the aforementioned strip-shaped sheet.
harden.

By the above procedure, a hollow fiber module of the present invention in which non-flexible adhesive-flexible adhesive-non-flexible adhesive is arranged in the shape of tree rings is manufactured.

The steps of cutting the ends of the hollow fibers for opening and trimming and attaching caps at both ends are the same as for ordinary hollow fiber modules.

The inner periphery of the end of the cylindrical case used in manufacturing the hollow fiber module of the present invention may be appropriately roughened.
104128, which has a recessed portion or a through hole, may also be used.

Furthermore, the method of the present invention can be applied to both dynamic adhesive sealing methods such as a centrifugal method, and static attachment and sealing methods such as a vacuum or pressure method.

(Effects of the Invention) In the hollow fiber module of the present invention, there was no peeling at the inner periphery of the case end, where peeling is most likely to occur.

The effects of the present invention will be explained below using Examples and Comparative Examples.

Example: A thin layer of heat-resistant, non-flexible epoxy adhesive was applied to a polysulfone case with an inner diameter of 82 mmφ, an outer diameter of 90 mmφ, and a length of 320 mm to approximately 30 mm from both ends, and after it was completely cured, the thickness was 2
A rectangular silicone rubber sheet with a width of 40 mm and a length of 257 mm was wrapped around the adhesive part of the case to form a ring shape, completely hiding the adhesive part.

Next, a bundle of 7,500 polyethersulfone hollow fibers with an inner diameter of 500 μm and an outer diameter of 700 μm was passed through a ring of silicone rubber and inserted into the case. Set this in a centrifugal adhesive sealing device and heat it to 55°C.
Centrifugal adhesive sealing was performed using epoxy adhesive at a rotation speed of 800 rpm so that the adhesive length on one side was 25 mm. When this is taken out and the annular silicone rubber sheet is removed, a 2 mm annular gap is created between the case and the adhesively sealed hollow fiber bundle, and a flexible epoxy adhesive containing dimer acid is injected into this gap. After gluing the case and the epoxy adhesive part and cutting the end of the case, we performed a leak test on the module, but there was no leakage.

90°C hot water is passed through this hollow fiber module for 30 minutes, and after the hot water is removed, 10°C cold water is immediately applied.
The 30-minute permeation operation was repeated five times, but no peeling occurred between the case and the adhesive.

Comparative example A fiber bundle consisting of 7500 polyethersulfone hollow fibers with an inner diameter of 500 μm and an outer diameter of 700 μm was inserted into a polysulfone case with an inner diameter of 82 mmφ, an outer diameter of 90 mmφ, and a length of 320 mm, and this was set in a centrifugal sealing machine. Epoxy adhesive was injected at a temperature of 55°C and a rotational speed of 800 rpm so that the length between the case and the adhesive layer was 25 mm, and was centrifugally sealed and cured. After taking it out and cutting off the end of the case, I inspected the module for leaks, but there were no leaks.

After 80°C hot water was passed through this hollow fiber module for 30 minutes, the hot water was immediately removed and 10°C cold water was passed through it, causing separation between the case and the adhesive.

There were also modules that peeled off simply by passing hot water at 80°C. Furthermore, when we inspected the module for leakage after cutting the end of the case, we found that some hollow fiber modules had already leaked from the case and the adhesive seal.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a cross section in the length direction of the module of the end adhesive-sealed portion of a hollow fiber type module according to the present invention, and FIG. 2 is a schematic cross-sectional diagram taken along the line A-A' in FIG. .

Claims (1)

[Claims] 1. A hollow fiber type module in which a cylindrical case is filled with a hollow fiber bundle, and the ends of the hollow fiber bundle and the case end are adhesively sealed, and the ends of the hollow fibers are sealed with adhesive. In this case, the adhesive composition in the cross section perpendicular to the module length direction of the adhesive sealing part is composed of non-flexible adhesive, flexible adhesive, and non-flexible adhesive from the inner surface of the cylindrical case toward the center. A hollow fiber module characterized by being arranged in a tree-ring pattern. 2. The hollow fiber module according to claim 7, wherein the flexible adhesive is an adhesive having a siloxane bond. 3. The hollow fiber module according to claim 1, wherein the flexible adhesive is an epoxy adhesive having a natural rubber or synthetic rubber skeleton. 4. The hollow fiber module according to claim 1, wherein the flexible adhesive is an epoxy adhesive having a dimer acid skeleton.