JP2784668B2 - Method of forming partition wall in hollow fiber membrane module - Google Patents

Description

The present invention relates to a method for forming a resin partition at an end of a hollow fiber membrane module.

<Prior art> Separation of solids from a stock solution, separation of a specific liquid from a stock solution, separation of a gas from a liquid, or separation of a specific gas from a mixed gas, using a permeable membrane (MF, UF or RO
) Is known, and hollow fiber membranes, which can take a large membrane area per unit volume, have attracted attention.
Various types of modules using hollow fiber membranes have been proposed.In a general hollow fiber membrane module, a hollow fiber membrane bundle is housed in a cylindrical cover, and at least one end of both ends of the cover is provided. It is indispensable to cast a high pressure-resistant resin partition wall, for example, an epoxy resin partition wall.

By the way, in a module, it is often necessary to flow cold water immediately after hot water flow (for example, cold and cold water cooling after hot water disinfection), but in the above hollow fiber membrane module, Peeling is likely to occur between the cover and the outward wall, and under such peeling, the occurrence of a leak between the transmission side and the raw water side is inevitable. As a cause of such peeling, conventionally, the distortion remains due to heat generation of the casting resin during casting, etc., due to a difference in thermal expansion coefficient between the cover and the casting resin, etc. This is considered to be the result of excessive stress being generated under a rapid temperature change. As a countermeasure, a flexible resin portion in the shape of an annual ring is provided on the partition wall between the i-cover and the hollow fiber membrane bundle. To absorb stress (Japanese Patent Laid-Open Nos. 61-141904 and 61-15309), to use the multi-stage casting method for ii casting, and to make the thermal expansion coefficient of the cover and casting resin equal. It is known.

<Problem to be solved> However, according to the experience of the present inventor, if the thermal condition becomes severe, it is difficult to prevent separation between the cover end portion and the resin partition even by using these means, It was presumed that there were causes other than the above, and when the cause was searched for, it was found that the heat-shrinkability of the plastic cover end was also a serious cause (third cause). .

That is, the thermal expansion of the header is distorted due to the heat shrinkability of the cover end (unless there is an amorphous portion at the cover end, and the uneven thickness of the header member constituting the cover end in the circumferential direction). In some cases, the cover may behave as if it exhibits heat shrinkage), but even if the cover edge and the partition have the same coefficient of thermal expansion, a shrinkage force is generated in the cover when heated, and the strain based on this shrinkage force As a result, a peeling force is generated between the end of the cover and the partition.

As described above, the present inventor has found that there are at least the three reasons described above as causes of the separation between the plastic cover and the resin partition.

Thus, in order to completely prevent the peeling, the total sum of the respective solving means for each cause is ideal. However, in the above-described configuration in which the flexible resin portion is provided in the shape of an annual ring on the partition wall, the flexibility is generally high. The resin is unsuitable because it exhibits an elution property at a high temperature and lowers the quality of permeated water. Ultrapure water especially for semiconductor manufacturing,
Not applicable for the production of water for injection.

The object of the present invention is to take into account the third cause, and
It is an object of the present invention to provide a partition wall forming method for a hollow fiber membrane module that can maintain the sealing property between a case and a resin partition even under a severe temperature change without depending on a stress absorbing action of a flexible resin.

<Means for Solving the Problems> In the method for forming a partition wall in the hollow fiber membrane module according to the present invention, the end of the cylindrical plastic cover is heated, and under the heating, the curable resin is coated on the inner periphery of the end of the cover. The method is characterized by forming a coating layer, storing the hollow fiber membrane bundle in the cover, and then casting a curable resin partition in the end of the cover.

<Description of Example> Hereinafter, an example of the present invention will be described with reference to the drawings.

The drawing shows a partition part of a hollow fiber membrane module prepared according to the present invention. In the figure, reference numeral 1 denotes a plastic cylindrical cover, which is formed by extruding plastic into a pipe shape and cutting the same into fixed lengths. The cover end may be formed of a separate member and a header, and the header may be joined to the cover body. Reference numeral 2 denotes a curable resin (hereinafter referred to as curable resin A) coating layer provided on the inner peripheral surface of the cover end. 3 is a hollow fiber membrane bundle housed in the cover. Reference numeral 4 denotes a partition wall of a curable resin (hereinafter, referred to as a curable resin B) cast into an end of the cover.

The above-mentioned curable resins A and B include those capable of withstanding the operating temperature of the module, for example, a heat-resistant epoxy resin,
Urethane resin or the like can be used. The curable resins A and B may be the same or different.

To form a partition according to the present invention, the edge of the cover is heated (the entire cover may be heated). The heating temperature is preferably set to the maximum operating temperature of the hollow fiber membrane module (around 95 ° C.), but may be slightly lower (60 ° C. or higher). Next, the curable resin A is coated on the inner periphery of the cover end, and is heated again to the above temperature to cure and after cure the resin A. The coating thickness of the curable resin A is preferably as thick as possible, but there is a limit in storing the hollow fiber membrane bundle. However, a thickness of 2 mm or more is required.

After the coating layer of the curable resin A is provided, the hollow fiber membrane bundle is stored in the cover, and the curable resin B is provided in the end of the cover.
To form a partition wall. It is desirable to use a centrifugal method for this casting. The inner surface of the partition wall does not create a dead space for the undiluted solution flow in the undiluted solution space in the cover,
It is desirable to have an inclined concave curved surface.

As described above, in the partition wall forming method according to the present invention, since the cover end portion is heated at a temperature close to the operating temperature of the module and then the resin partition wall is cast, the module is subjected to severe thermal conditions. Even when used below, the peeling force acting between the cover and the partition can be well suppressed, and peeling therebetween can be prevented.

That is, the inner diameter of the cover or the outer diameter of the partition is R, the thickness of the cover is t, the thermal expansion coefficients of the cover and the partition are both α, the Young's modulus of the cover is E ₁ , the Young's modulus of the partition is E ₂ , and the thermal contraction of the end of the cover is performed. If the rate is β and the temperature rise during use is T, the hoop stress f acting on the cover edge is The end of the cover extends at a rate of kf, and a peeling force P expressed by the following equation is exerted between the end of the cover and the partition wall at the time of cooling to the original temperature.

Thus, in the present invention, since the cover end is preheat-treated, the heat shrinkage β of the cover end is set to substantially zero,
The peeling force P can be made substantially zero.

Further, in the present invention, the resin partition walls are divided into a part of the curable resin A and a part of the curable resin B, and are molded.
Since the step casting is used, the strain associated with the resin curing can be sufficiently reduced.

<Effects of the Invention> As described above, according to the present invention, the peeling between the cover end and the partition wall can be prevented even under the severe temperature use condition of the module by eliminating the peeling force P and the two-step casting method. A highly reliable hollow fiber membrane module can be provided. This is clear from the comparison between the following examples and comparative examples.

Example 1 A polysulfone cover was previously heated to 100 ° C.
A heat-resistant epoxy resin composition (a mixture of Yuka Ciel Co., Ltd. product Epicoat 828 and Sanwa Chemical Co., Ltd. product DA-100) was coated on the inner peripheral surface of the end at a thickness of 5 mm,
The coating layer was heated again to 100 ° C. to cure the coating layer. After that, 3000 hollow fiber membranes with an outer diameter of 1 mm are stored in the cover,
Next, partition walls were cast using the same heat-resistant epoxy resin composition as above.

Example 2 The preheating temperature of the cover and the heating temperature of the coating layer were set to 60
The same as Example 1 except for the temperature.

Comparative Example Same as Example 1 except that the cover was not preheated and the coating layer was cured at room temperature.

For each of the Example and Comparative Example products, when a cooling / heating cycle test in which hot water flow and normal temperature water flow were repeated was performed, in the Comparative Example product, the space between the cover and the partition wall peeled off at the third cycle. However, in Example product 1, no peeling occurred even at the 50th cycle, and in Example 2, there was no abnormality up to the 36th cycle.

[Brief description of the drawings]

The drawing is an explanatory view showing a partition wall portion of the hollow fiber membrane module formed according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Cover 2 ... Coating layer of curable resin 3 ... Bunch of hollow fiber membranes 4 ... Partition wall of curable resin

Claims (1)

(57) [Claims] 1. An end of a cylindrical plastic cover is heated,
Under the heating, a coating layer of a curable resin is formed on the inner periphery of the cover end, and the hollow fiber membrane bundle is stored in the cover,
Thereafter, a method of forming a partition in a hollow fiber membrane module, comprising casting a curable resin partition into the end of the cover.