JP2000202251A - Hollow fiber membrane module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber membrane module small in ruggedness on an end part to improve the sticking of a contaminant to the end part or the blood remaining phenomenon in the case of being used for blood treatment. SOLUTION: The hollow fiber membrane module is formed by sticking a hollow fiber membrane on a cylindrical case with a potting agent and the potting agent is compatible with glycerine in concentration of <=3 wt.% glycerine at the time of being mixed with glycerine. As the potting agent, a polyurethane compatible with glycerine in concentration of >=4 wt.% glycerine is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for reducing unevenness at the end of a hollow fiber membrane module.

[0002]

2. Description of the Related Art In recent years, hollow fiber membrane modules using hollow fibers as separation membranes have been used in various fields such as industrial fields such as water treatment membranes and medical fields such as blood treatment. In particular, demand for water purifiers, artificial kidneys, artificial lungs and the like has been extremely increasing.

[0003] In general, in a hollow fiber membrane module, a number of hollow fiber membranes are bundled to form a bundled yarn, the bundled yarn is inserted into a cylindrical case, and the hollow fiber membrane in the bundled yarn is then potted with a potting agent. At the same time, the bonding between the bundled yarn and the cylindrical case is performed, and after the potting agent is solidified, the bundled yarn is cut in a cross-sectional direction at a position where the open end of the hollow fiber membrane is obtained. I have.

However, looking at the end of the hollow fiber membrane module after cutting, there is a step as shown in FIG. 1 between the height of the apex of the hollow fiber membrane and the surface of the potting agent existing between the hollow fiber membranes. When such a level difference occurs, contaminants adhere to the end portion, and when used for blood treatment, the blood coagulation ability is activated when blood flows in, or a stagnant portion is generated and a convex portion is formed. Blood may remain, and residual blood may occur after returning blood.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for improving the disadvantages of the prior art and reducing the irregularities at the end of the hollow fiber membrane module.

[0006]

According to the present invention, there is provided a hollow fiber membrane module comprising a hollow fiber membrane and a cylindrical case bonded to each other with a potting agent. As an agent, a polyurethane having a compatible concentration of glycerin of 3% by weight or more is used.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The means for forming a hollow fiber membrane into a module is not particularly limited, but one example is as follows.
First, the hollow fiber membrane is cut to a required length, bundled in a required number, and then placed in a cylindrical case. After that, temporary caps are put on both ends, and potting agents are put into both ends of the hollow fiber membrane. At this time, a method of adding the potting agent while rotating the module with a centrifuge is a preferable method because the potting agent is uniformly filled. After the potting agent has solidified, cut both ends so that both ends of the hollow fiber membrane are open,
Obtain a hollow fiber membrane module.

[0008] The potting agent used in the present invention is polyurethane. Preferably used polyurethane is
It is a two-component mixed polyurethane in which an isocyanate component and a polyol component are mixed and cured, and as the isocyanate component, methylene diisocyanate (MDI),
Examples include tolylene diisocyanate (TDI) and hexamethylene diisocyanate (HDI), and examples of the polyol component include castor oil derivatives.

By the way, the hollow fiber membrane is often impregnated with a glycerin aqueous solution in order to prevent performance deterioration due to drying of the membrane during the process.

Generally, when glycerin is mixed in polyurethane, phase separation occurs almost without mixing. Glycerin adhering to the hollow fiber membrane is not uniformly mixed with the polyurethane, resulting in a glycerin concentration gradient at the module end where the glycerin concentration is high around the hollow fiber membrane and the glycerin concentration decreases as the distance from the hollow fiber membrane increases. This may affect the height of the unevenness at the end.

In the present invention, by using a polyurethane having good glycerin affinity as a potting agent,
It was found that at the end of the hollow fiber membrane module, the difference between the height of the hollow fiber membrane height and the height of the potting agent bottom surface could be reduced to a height of irregularities with a maximum value of less than 8 μm and an average value of less than 5 μm.

In the present invention, "good glycerin affinity" means that the compatible concentration of glycerin is 3% by weight or more. Glycerin compatible concentration is 4% by weight
More preferably, it is the above. Here, the compatible concentration of glycerin is the upper limit of the concentration of glycerin that can be added to polyurethane while maintaining compatibility, and if glycerin is added beyond this concentration, a phase separation occurs between the two. Say

In the present invention, the compatibility was measured as follows. That is, a predetermined amount of glycerin is added to a predetermined amount of a curing agent and a main agent, mixed, and placed in a cell for measuring absorbance (polystyrene, 12.4 × 12.4 × 45 mm, optical path length 10 mm) and centrifuged at 3000 rpm for 10 minutes. After defoaming, it was cured at a predetermined temperature. Thereafter, the absorbance at 400 nm was measured. A: 0.5 or less (transparency, compatibility ◎), B: more than 0.5 and 1.0 or less (slightly transparent, compatibility 、), C: 1.
0 to 2.0 (opaque, compatible), D:
Classified as greater than 2.0 (cloudiness, compatibility x), rank A
In the case of B or B, compatibility was determined, and when the rank was C or D, phase separation was determined. The measuring device includes a Shimadzu UV-210
0 was used. The presence or absence of the phase-separated glycerin particles may be evaluated by microscopic observation.

To improve the affinity with glycerin, it is useful to use an aliphatic isocyanate component. However, aliphatic isocyanates have a low curing rate and affect the productivity, so that aliphatic isocyanates are not used. Aromatic isocyanates may be used to such an extent that the affinity of the isocyanate is not affected.

The curing time is preferably sufficiently cured until the hardness reaches the final hardness in consideration of the subsequent shrinkage due to the progress of the reaction.
Within hours is preferred.

The blade for cutting the potting agent may be a guillotine blade or a circular round blade.
Since spilling of the blade and the angle of the cutting edge affect slippage at the time of cutting, it is necessary to perform sufficient management.

The hardness at the time of cutting may be such that it does not adhere to the blade at the time of cutting or the potting agent is scratched by the blade. That is, the value when the JIS-A hardness is measured at room temperature (28 ° C.) is 35 or more, and the temperature at the time of cutting may be 40 ° C. or less.

In the present invention, the height of the unevenness at the end of the hollow fiber membrane module was evaluated as follows. The center of the end with the potting agent injection nozzle up and 3
At four points around the hour, 9 o'clock and 12 o'clock directions (FIG. 2), between the hollow fiber membranes parallel to the cutting direction and between the hollow fiber membranes perpendicular to the cutting direction (FIG. 3), a total of 8 points The points were scanned with a laser using a surface shape measuring microscope (VF-7500, manufactured by Keyence Corporation, laser confocal method) to obtain a concavo-convex profile of the site. The measurement was performed at room temperature (28 ° C.).

The hollow fiber membrane module of the present invention is used for manufacturing various separation membranes such as dialysis membranes, and is particularly suitable for manufacturing separation membranes using polysulfone hollow fiber membranes. Further, it is used for applications such as artificial kidneys, water treatment membranes, gas separation membranes, adsorbents, etc., and is particularly suitably used for blood treatment applications that come into contact with blood.

[0020]

EXAMPLES Example 1 Polysulfone hollow fiber membrane (outer diameter 28
A bundle of 10600 pieces having a thickness of 0 mm, a thickness of 40 mm, and a length of 248 mm) is placed in a cylindrical storage container, and a two-part mixed polyurethane potting agent A containing hexamethylene diisocyanate (HDI) as a main component (compatibility: glycerin) A centrifugal force (centrifugal force of 1600 rpm for a module having a length of 225 mm, 300 G in a potting portion) was applied at room temperature while applying a centrifugal force even at a concentration of 3% by weight. First, a small amount of a potting agent is injected at the first stage to fill the opening of the hollow fiber membrane, and after 30 minutes, a predetermined amount of the potting agent is injected at the second stage. Bonding between the yarn and the cylindrical case was performed simultaneously. It was taken out after 30 minutes, cured at 25 ° C. for 7 hours, and then cut at 25 ° C. J at this time
The IS-A hardness was 37. The obtained module was washed with water and then subjected to γ-ray irradiation. The difference between the apex of the hollow fiber membrane at the end of the module after the end of the γ-ray irradiation and the height of the bottom surface of the polyurethane part (irregularity) was 5.4 mm at the maximum, and the average was 3.3 mm.

(Example 2) Polysulfone hollow fiber membrane (outer diameter
280 mm, film thickness 40 mm, length 248 mm), bundled 10600 pieces are put into a cylindrical storage container, and a two-component mixed type polyurethane potting agent B containing methylene diisocyanate (MDI) and HDI as main components (compatibility: Bonding was carried out in the same manner as in Example 1 except that ○ was used even at a glycerin concentration of 3% by weight. The JIS-A hardness at this time was 59. The obtained module was washed with water and then subjected to γ-ray irradiation. The difference (irregularity) between the height of the hollow fiber membrane at the end of the module after γ-ray irradiation and the height of the polyurethane part bottom surface was 7.6 mm at the maximum, and the average was 4.3 mm.

Comparative Example 1 Polysulfone hollow fiber membrane (outer diameter
280 mm, film thickness 40 mm, length 248 mm), bundled 10600 pieces are put into a cylindrical storage container, and a two-part mixed polyurethane potting agent C containing MDI as a main component (compatibility: glycerin concentration of 1% by weight) Δ) was injected at room temperature while applying a centrifugal force (centrifugal force of 1600 rpm to a module having a length of 225 mm). First, a small amount of a potting agent is injected at the first stage to fill the opening of the hollow fiber membrane, and after 30 minutes, a predetermined amount of the potting agent is injected at the second stage. Bonding between the yarn and the cylindrical case was performed simultaneously. Take out after 30 minutes, 5 hours at 60 ° C, 2 hours at 25 ° C
After curing for an hour, the end was cut at 25 ° C.
The JIS-A hardness at this time was 89. The obtained module was washed with water and then subjected to γ-ray irradiation. The difference between the top of the hollow fiber membrane at the end of the module after gamma irradiation and the height of the bottom of the polyurethane part (irregularity) is 8.5 mm at the maximum, and 5.5 mm on average.
Met.

(Comparative Example 2) A two-part mixed polyurethane potting agent D containing MDI and tolylene diisocyanate (TDI) as main components (compatibility: glycerin concentration 1% by weight)
Bonding was carried out in the same manner as in Comparative Example 1 except that the above (1) was used. The JIS-A hardness was 85. The difference (irregularity) between the height of the hollow fiber membrane at the end of the module after γ-ray irradiation and the height of the polyurethane portion bottom surface was 9.0 mm at the maximum, and the average was 6.4 mm.

(Comparative Example 3) Adhesion was carried out in the same manner as in Example 1 except that a two-part mixed polyurethane potting agent E containing HDI as a main component (compatibility: up to a glycerin concentration of 1% by weight) was used. . The JIS-A hardness was 81.
The difference between the top of the hollow fiber membrane at the end of the module after γ-ray irradiation and the height of the bottom of the polyurethane part (irregularity) is a maximum value of 13.5.
mm, average 8.5 mm.

Example 3 Two-part mixed polyurethane potting agent F containing MDI and HDI as main components (compatible:
Bonding was carried out in the same manner as in Comparative Example 1 except that glycerin concentration of 4% by weight was used. The JIS-A hardness was 88. The difference (irregularity) between the height of the height of the hollow fiber membrane at the end of the module after γ-ray irradiation and the height of the bottom surface of the polyurethane portion was 6.7 mm at the maximum, and was 4.2 mm on average.

[0026]

[Table 1]

[0027]

The present invention is useful in that irregularities at the end of the hollow fiber membrane module can be reduced, and contaminants can be attached to the end and the residual blood phenomenon when used for blood treatment can be improved. That is, when looking at the end after cutting, there is a step between the height of the apex of the hollow fiber membrane and the surface of the polyurethane existing between the hollow fiber membranes, but according to the present invention, the height of the unevenness is reduced. This can improve the adhesion of contaminants to the ends and the residual blood phenomenon when used for blood treatment.

[Brief description of the drawings]

FIG. 1 is a sectional view of an end of a hollow fiber membrane module.

FIG. 2 is a diagram showing a portion for measuring unevenness of a cut surface at an end of a hollow fiber membrane module.

FIG. 3 is an enlarged view showing a portion for measuring unevenness of a cut surface at an end of a hollow fiber membrane module.

[Explanation of symbols]

 1: hollow fiber membrane 2: potting agent 3: module end 4: hollow fiber membrane bundle and potting agent 5: cylindrical container 6: potting agent injection nozzle 7: unevenness measurement point

Claims (4)

[Claims] 1. A hollow fiber membrane module in which a hollow fiber membrane and a cylindrical case are bonded with a potting agent, wherein a compatible concentration of glycerin as the potting agent is 3% by weight.
A hollow fiber membrane module using the polyurethane described above. 2. The hollow fiber membrane module according to claim 1, wherein a polyurethane having a compatible concentration of glycerin of 4% by weight or more is used as the potting agent. 3. The hollow fiber membrane module according to claim 1, wherein the hollow fiber membrane is made of polysulfone. 4. The hollow fiber membrane module according to claim 1, wherein the module is used for blood treatment.