JPH05301030A - End shrinkage treatment of selectively permeable hollow fiber - Google Patents

Abstract

PURPOSE:To provide a method for shrinkage (diametral reduction) of the ends of selectively permeable hollow fibers consisting of a polymer of an arom. polyamide system in such a manner that the ends of these fibers are diametrally reduced while bundling the fibers to a high density, thereby forming the gaps into which the resin for adhering and sealing can be penetrated. CONSTITUTION:After the ends of the selectively permeable hollow fibers are subjected to an immersion treatment with a treating liquid of a water-soluble org. compd. system having a b.p. of <=105 deg.C and an m.p. of <=20 deg.C, the ends of the selectively permeable hollow fibers subjected to the immersion treatment are dried and the org. solvent, etc., deposited thereon are removed. The outside diameter of the selectively permeable hollow fibers of these parts is then reduced by 5 to 15%. Then, the water in the selectively permeable hollow fibers (membranes) and the org. compd. are substd. by immersing the fibers into the treating liquid of the org. compd. system and act as a plasticizer to the arom. polyamide constituting the selectively permeable hollow fibers. The molecules of the arom. polyamide flocculate and the required diametral reduction is attained. In addition, the structure of the fibers changes to the stable structure and, therefore, the resin is liable to be penetrated into the ends and the dense adhesion is attained.

Description

Detailed Description of the Invention

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION The present invention relates to a method of impregnating an end surface portion of a selectively permeable hollow fiber bundle used for separating or concentrating components in a mixed fluid such as filtration, gas separation and reverse osmosis with an adhesive resin. The present invention relates to an end contraction method of a selectively permeable hollow fiber which is suitable for tightly sealing and integrating, and more specifically, a gap between the selectively permeable hollow fibers is enlarged, and a permeation of a selectively permeable hollow fiber bundle by injecting a resin is performed. TECHNICAL FIELD The present invention relates to a method for shrinking end portions of a selectively permeable hollow fiber, which makes it possible to easily and liquid-tightly bond and integrate the end portions.

[0003]

2. Description of the Related Art Membrane separation methods for separating components in a mixed fluid using a membrane having selective permeability include gas permeation, liquid permeation, dialysis, ultrafiltration and reverse osmosis. The reverse osmosis method is used, for example, for desalination of seawater, production of pure water for the semiconductor industry and pharmaceutical industry, treatment of domestic wastewater, concentration of fruit juice, recovery of valuables from various wastewater.

In the membrane separation device using such a permselective membrane, since the effective membrane area per unit volume is large and the separation by the membrane is generally performed at a high pressure, the membrane and the membrane supporting portion have the above-mentioned structure. It is required to have a structure that can withstand pressure. These problems are solved to some extent by making the separation membrane into a hollow fiber shape, and are being put to practical use. For example, as shown in cross section in FIG.
The permselective hollow fibers 1 made of an aromatic polyamide polymer are collectively arranged on the outer peripheral surface of the core tube 2, and a liquid to be treated or the like is directed to an arrow 3a through a hole provided in a wall surface of the core tube 2. As shown, the wall surface (membrane) of the selectively permeable hollow fiber 1 is made to enter the side of the selectively permeable hollow fiber 1 arranged in a bundle.
There is known a means for selectively permeating the liquid to be treated to the hollow passage side, separating and purifying it, and taking it out as shown by an arrow 3b. Since the permselective membrane is formed in an annular shape in cross section, it is possible to retain the shape of the membrane or the supporting structure capable of exhibiting a required function even when a relatively high pressure is applied.
In the figure, 4 is a case, 2a is a closing body for allowing the liquid to be treated to flow out from the wall surface of the core tube 2, and 5 is a resin adhesive that seals and integrates the end portions of the selectively permeable hollow fiber bundle (layer). The filling areas are shown respectively.

[0005]

However, in the case of the separation device having the above-mentioned permselective hollow fiber (membrane) 1, the permselectivity is increased in order to increase the effective membrane area per unit volume of the separation device. Increasing the packing density of the hollow fibers 1 is inevitably required. As a countermeasure against this, if the end region 5 for sealing / integrating one bundle (layer) of the selectively permeable hollow fibers is made dense, the resin hardly penetrates when the end region is adhered / sealed with resin. Therefore, the blockage of the gap between the selectively permeable hollow fibers 1 tends to be incomplete. Therefore, as a pretreatment for the step of adhering and sealing, the end portions of the selectively permeable hollow fibers 1 to be bundled are selectively contracted in advance to make the gap between the selectively permeable hollow fibers 1 larger than the central portion, and Need to penetrate well. That is, if there is a part where the blockage due to the adhesion is incomplete, the fluid leaks through the part where the blockage is incomplete, and the function as the separation device cannot be achieved.

[0006] In order to solve such a problem, in the process of producing a permselective hollow fiber made of cellulose ester,
A heat-drying method using dry nitrogen gas removes water from the end of the selectively permeable hollow fiber, and shrinks the end to provide a shrinkage rate sufficient for resin bonding and sealing (blocking). 5-10% in the length direction of flexible hollow fiber, 5 in outer diameter
It is disclosed in Japanese Patent Laid-Open No. 57-35907. However, compared with the above-mentioned cellulose ester-based permselective hollow fiber, a mixed component of diamine compounds represented by the following formulas (1) and (2) having a good separation function and durability (molar ratio: 95 / 5- 35/65) and general formula, XOC
An aromatic dicarboxylic acid halide compound represented by -R-COX (wherein X represents a halogen atom and R represents an organic group having 2 to 15 carbon atoms which may contain a hetero atom) as a reaction component; In the case of a selectively permeable hollow fiber made of a group polyamide polymer, the application of the method for end shrinkage treatment with the dry nitrogen gas does not provide sufficient shrinkage, so that the selectively permeable hollow fiber when arranged in a bundle or in a layered state. Since the gap between the fibers is small and the resin does not easily penetrate in the bonding / sealing process, the resin may partially break, and the bonding / sealing (blocking) is not liquid-tight and cannot be achieved confidentially. There's a problem. Therefore, in the case of configuring a membrane separation device using the permselective hollow fibers composed of the aromatic polyamide-based polymer, the packing density of the permselective hollow fibers is lowered and the gap between the permselective hollow fibers is increased. However, it is unavoidable that the resin permeates easily to enhance the adhesiveness, but the permeation flow rate per membrane separation device decreases, which is not efficient.

[0007]

[Chemical 1]

(Wherein R ¹ and R ² are hydrogen atoms or hydrocarbon groups having 1 to 12 carbon atoms, R ³ and R ⁴ are hydrogen atoms or monovalent organic groups having no active hydrogen,
n ₁ and n ₂ represent a natural number of 0 or 1 to 3. )
(Below margin)

[0009]

[Chemical 2]

(However, R ⁵ , R ⁶ , R ⁷ , R ⁸ ,
R ⁹ , R ¹⁰ , R ¹¹ , R ¹² hydrogen atom or carbon atom 1
~ 12 hydrocarbon groups are shown. ) The present invention has been made to solve the above-mentioned problems, and it is possible to easily and surely reduce the diameter of an end portion of a selectively permeable hollow fiber made of an aromatic polyamide polymer. While focusing on a high density, forming a gap at the end that can easily penetrate resin for adhesion or sealing,
It is an object of the present invention to provide a method for end shrinkage (diameter reduction) treatment of a selectively permeable hollow fiber capable of finally forming a dense adhesion / sealing.

[Constitution of the Invention]

[0012]

The method of shrinking (reducing) the edge of a permselective hollow fiber according to the present invention is a method for shrinking the end of a permselective hollow fiber made of an aromatic polyamide polymer. The step of subjecting the end of the selectively permeable hollow fiber to a water-soluble organic compound having a boiling point of 105 ° C. or lower and a melting point of 20 ° C. or lower or an aqueous solution containing the organic compound as a treatment liquid, and the selective permeability subjected to the immersion treatment The method comprises the step of drying the end portion of the hollow fiber to remove the organic solvent and water that have adhered to shrink the outer diameter of the selectively permeable hollow fiber in this portion by 5 to 15%. here,
The end of the selectively permeable hollow fiber is the length of the entire length
~ 15%.

According to the present invention, the end portion of the permselective hollow fiber made of the aromatic polyamide polymer is
For example, acetone, 1,4-dioxane, methanol, ethanol, iso-propanol, 2-methyl-2-propanol, etc., whose boiling point is 105 ° C or less, and whose solubility in water is infinite due to easy substitution with water. A water-soluble organic compound or an aqueous solution containing these organic compounds in a concentration of 20 to 50% by weight is used as a treatment liquid. The treatment liquid is immersed in the treatment liquid for about 30 minutes and air-dried, and then the end portions are dried at 105 ° C for about 2 hours. In this case, the end of the selectively permeable hollow fiber is selectively contracted (reduced in diameter), the resin is easily impregnated and penetrated, and it is possible to realize adhesive integration with the resin and precise sealing structure. It is based.

[0014]

[Function] The selectively permeable hollow fiber (membrane) is acetone, 1,
4-dioxane, methanol, shrinks by an organic compound such as ethanol, by immersing the permselective hollow fiber in the organic compound, the water in the permselective hollow fiber membrane is replaced with an organic compound, It is considered that this acts as a plasticizer for the aromatic polyamide that constitutes the selectively permeable hollow fiber, and the molecules of the aromatic polyamide aggregate to change into a more stable structure.

[0015]

EXAMPLES The present invention will be described in more detail below by showing examples of the present invention and comparative examples for the present invention.

First, the following equation (3)

[0017]

[Chemical 3]
(3)

A permselective hollow fiber having an outer diameter of 175.3 μm, an inner diameter of 85.5 μm, and a water content of 151.9%, which is composed of an aromatic copolyamide represented by the formula (1), was prepared. Such a selectively permeable hollow fiber can be manufactured as follows. For example, diamine compound component consisting of anhydrous piperazine and 4,4'diaminophenyl sulfone, pyridine (acid scavenger), and N-methylpyrrolidone (reaction solvent) were made into a uniform solution under a nitrogen stream, and then this was cooled on ice. Then, for example, an isophthalic acid dichloride component is added, and the reaction is performed at ice-cooling temperature for about 30 minutes and then at room temperature for about 1 hour. Next, this reaction solution is poured into methanol to precipitate and precipitate the produced polymer, which is crushed and washed with water to remove unreacted components, and dried in vacuum to be a solution in a mixed solvent of N-methylpyrrolidone-anhydrous glycerin. To do. Thereafter, the solution is introduced into water at room temperature from an arc type nozzle to obtain hollow fibers, and the hollow fibers are immersed in water to remove residual solvent and the like, thereby obtaining selectively permeable hollow fibers. A method for producing this type of selectively permeable hollow fiber is disclosed in, for example, Japanese Patent Application Laid-Open No. 2-63535.

The selectively permeable hollow fiber having an outer diameter of 175.3 μm, an inner diameter of 85.5 μm and a moisture content of 151.9% has an operating pressure of 30 kg / c.
In reverse osmosis separation using 1500 ppm saline at m ² at room temperature (25 ° C) as the water to be treated, the performance was evaluated at a recovery rate of 5%, and a salt removal rate of 99% and a water permeability of 200 l / m ² · D were obtained. there were. The salt removal rate is represented by the following equation.

Salt removal rate = FP / F × 100 (%) F: Salt concentration in feed liquid P: Salt concentration in permeate Also, the outer diameter is 175.3 μm, the inner diameter is 85.5 μm, and the water content is 151.
3.5% by weight at room temperature on the end side of 9% permselective hollow fiber
After being soaked in the saline solution for 5 minutes and then spin-dried, the treatment liquids shown in Table 1 and Table 2 are treated with various treatment solutions under various temperature conditions.
Soaked for a minute. After this immersion treatment, air-dry, and the length (cm), outer diameter (μm), and inner diameter of the treated part of those permselective hollow fibers.
(μm) was measured. Next, after drying these permselective hollow fibers for 2 hours at a temperature of 105 ° C, again measure the length (cm, outer diameter (μm), inner diameter (μm)) of the treated part of the permselective hollow fibers. The results are shown in Tables 1 and 2 (Examples 1 to 12), but except Examples 8 and 9, a high shrinkage ratio was exhibited.

Comparative Example Using ion-exchanged water as the treatment liquid, the shrinkage percentage was measured under various temperature conditions as shown in Table 3 in the same manner as in Examples 1 to 12 above. The contraction rate in the length direction of the treated part was small. Table 1 Measured values after immersion treatment Treatment liquid Boiling point Treatment liquid Example Example Outer diameter in outer diameter Outer diameter Inner diameter (℃) Temperature) shrinkage Shrinkage (μm) (μm) (℃) (%) (%) Acetone 56.1 10 1 6.17 9.58 158.5 81.3 〃 〃 20 2 7.78 9.41 158.8 81.3 〃 〃 25 3 9.63 10.15 157.5 78.9 〃 〃 35 4 8.09 9.24 159.1 80.5 1,4-dioxane 101.3 25 5 6.15 11.43 156.4 77.4 Methanol 64.5 25 5.5 6.05 5.59 83.9 Ethanol 78.3 25 7 4.93 5.36 165.9 83.4 iso-propanol 82.4 25 8 0.98 3.45 170.5 83.2 2-Methyl-2-82.5 25 9 1.00 3.86 174.2 86.4 Propanol 20wt% Acetone-25 10 0.40 6.85 164.5 83.1 Aqueous solution 30wt% Acetone-25 11 1.05 1.64 173.7 84.4 Aqueous solution 50wt% Acetone-12 4.01 7.13 164.0 78.1 Aqueous solution Table 2 Measured values after drying treatment Treatment liquid Boiling treatment liquid Example Longitudinal outer diameter Outer diameter Inner diameter (° C) Temperature shrinkage rate Shrinkage rate ( μm) (μm) (℃) (%) (%) Acetone 56.1 10 1 10.93 11.29 155.5 77.3 〃 20 2 12.06 13.06 152.4 77.9 〃 〃 25 3 12.32 13.40 151.4 76.1 〃 〃 35 4 11.16 9.98 157.8 79.4, 1,4-dioxane 101.3 25 5 10.57 13.19 153.3 78.2 Methanol 64.5 25 6 9.45 11.07 155.9 80.0 Ethanol 78.3 25 7 8.75 8.04 161.2 81.7 iso-propanol 82.4 25 8 4.51 4.93 167.9 78.8 2-methyl-2-82.5 25 9 3.72 7.56 167.9 84.3 propanol 20wt% acetone-25 10 7.69 8.10 162.3 81.3 aqueous solution 30wt% acetone-25 11 8.22 12.29 162.3 81.3 aqueous solution 50wt% acetone -12 10.44 11.38 156.5 77.9 Aqueous solution Table 3 Measured value after immersion treatment Treatment liquid Comparative example Treatment liquid Length outside diameter Outer diameter Inner diameter Temperature shrinkage rate Shrinkage rate (μm) (μm) (℃) (%) ( %) 1 85 0.10 − 175.6 86.6 Ion-exchanged water 2 92 0.20 0.29 174.8 85.5 3 98 0.24 2.45 171.0 85.2 Table 4 Measured values after drying treatment Comparative treatment liquid Treatment liquid length direction outer diameter outer diameter inner diameter temperature) shrinkage Shrinkage (μm) (μm) (℃) (%) (%) 185 5.17 6.50 163 .9 85.2 Ion-exchanged water 2 92 5.10 9.24 159.1 84.2 3 98 4.88 10.95 156.1 83.9 Shrinkage = Xo−X / Xo × 100 (%) Xo: Length or outer diameter of the selectively permeable hollow fiber membrane before immersion treatment X : Length or outer diameter of permselective hollow fiber membrane after dipping treatment or drying treatment As described above, acetone, 1,4-dioxane,
The shrinkage rate at the end of the selectively permeable hollow fiber (membrane) when an organic compound such as methanol or ethanol and an aqueous solution containing these organic compounds at a concentration of 20 to 50% by weight is used. ) 7-12% in the length direction,
The outer diameter of the selectively permeable hollow fiber (membrane) shows a large value of 8 to 13%.

On the other hand, when ion-exchanged water is used as a treatment liquid for comparison and the treatment liquid is treated in the same manner at a temperature of 85 to 98 ° C., the shrinkage ratio of the end portion of the selectively permeable hollow fiber (membrane). Shows a result of 4 to 5% in the length direction of the selectively permeable hollow fiber membrane and 6 to 11% in outer diameter. When ion-exchanged water is used as the treatment liquid as described above, an organic compound such as acetone, 1,4-dioxane, methanol or ethanol and an aqueous solution containing 20 to 50% by weight of these organic compounds are treated as the treatment liquid. Although the shrinkage rate of the outer diameter of the permselective hollow fiber membrane is similar, the shrinkage rate in the length direction is as low as about half. Here, the greater the shrinkage ratio in the lengthwise direction of the end of the permselective hollow fiber (membrane), the more the so-called “twist” is applied to the permselective hollow fiber (membrane) at the end subjected to the contraction treatment. Since the fineness is improved, the resin easily penetrates and the adhesiveness is improved. Also, if the edge of the selectively permeable hollow fiber (membrane) contracts only in the length direction, the edge will bulge and adversely affect the adhesion. It is desired that the contraction of the above occurs in a balanced manner.

To meet these demands, organic compounds such as acetone, 1,4-dioxane, methanol and ethanol, and their organic compounds are made to have a concentration of 20 as a processing liquid.
When an aqueous solution containing up to 50% by weight is used, good effects are exhibited. Further, it was found that among the organic compounds, the shrinkage rate was the maximum when acetone was used as the treatment liquid, and the treatment liquid temperature was optimally 20 to 25 ° C. Furthermore, the effect of dipping time on shrinkage is small, and 30 minutes is sufficient. In addition to such effects, there is an advantage that the drying time can be shortened by using a low boiling point organic compound such as acetone as a treatment liquid.

The shrinkage treatment according to the present invention is effective not only when it is applied to a relatively small amount of permselective hollow fibers, but also when the permselective hollow fibers (membrane) as shown in FIG. It is applied to the end of the element before adhesion, which is made by stacking a number of stacks, and the length of the shrink-treated portion is 7 to 13% compared to that before the shrinking treatment, and the outer diameter of the element is 5 to 13%.
It was also confirmed that the film shrank by%.

Before being immersed in the treatment liquid, the permselective hollow fibers (membrane) and the end of the element are immersed at room temperature for about 5 minutes in a saline solution of about 3.5% by weight, and then centrifugally dehydrated to obtain permselective hollow fibers. It is preferable that the water content of the membrane is 200% or less, and this pretreatment promptly replaces the water in the selectively permeable hollow fiber (membrane) with the organic compound in the treatment liquid.

[0026]

As can be seen from the above examples and explanations, according to the method for edge shrinkage treatment of permselective hollow fibers (membranes) made of an aromatic polyamide polymer according to the present invention, the edge can be easily and accurately produced. It is possible to selectively shrink and reduce the diameter of the portion. Therefore, even when it is applied to, for example, a reverse osmosis separation device, it is relatively easy to permeate the resin that is sealed and bonded and integrated at the end while maintaining a high density arrangement at the center. Since the voids are held and formed, the end portions of the selectively permeable hollow fibers (membranes) are also closely sealed and adhered, and liquid leakage or gas leakage is completely avoided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of a reverse osmosis separation device showing an example of use of a selectively permeable hollow fiber (membrane) according to the present invention.

[Explanation of symbols]

1 ... Yarn bundle of the selectively permeable hollow fiber (membrane) 2 ... Core tube
2a ... Core tube blocker 3a ... Treatment liquid permeation direction 3b ... Treatment liquid outflow direction 4 ...
Case 5: Resin adhesive sealing area (end of permselective hollow fiber)

Claims (1)

[Claims] 1. A method for shrinking the end portion of a permselective hollow fiber made of an aromatic polyamide polymer, wherein the end portion of the permselective hollow fiber has a boiling point of 105 ° C. or lower and a melting point.
A step of immersing a water-soluble organic compound or an aqueous solution containing the organic compound at 20 ° C. or less as a treatment liquid, and drying the end of the immersion-treated selectively permeable hollow fiber to remove an organic solvent and water deposited on the end. And a step of shrinking the outer diameter of the selectively permeable hollow fiber in this portion by 5 to 15%, the end shrinking method of the selectively permeable hollow fiber.