JPH0338221A - Hollow yarn membrane module and manufacture thereof - Google Patents

Abstract

PURPOSE:To enhance wetting properties in case of a high filling density of hollow yarn by means of uncured sealing resin and reducing sealing errors by oxidation treating the outer surface of a contact section with the sealing resin of polyolefin hollow yarn. CONSTITUTION:A hollow yarn membrane 1 composed of polyolefin is mounted on a module case 2, and its end section is sealed with resin. At that time, a section 3 where the hollow yarn membrane 1 is sealed is treated by a surface oxidation using an oxidizer (example: dichromic acid). As a result, wetting properties provided by uncured sealing resin is enhanced to reduce sealing errors in case of high filling density hollow yarn and to increase manufacturing yield.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a hollow fiber separation membrane module, and the wettability of the hollow fiber membrane and the sealing resin is determined before sealing the ends of the hollow fibers with a resin. How to improve manufacturing yield and extend module life by improving adhesion.
The present invention relates to a membrane module that exhibits high performance even in applications where water is introduced outside of hollow fibers. This module is applicable to general membrane processing fields using hollow fiber membranes, such as pervaporation, gas-liquid contact, gas separation, precision filtration, ultrafiltration, reverse osmosis, etc., but is particularly applicable to pervaporation. method, gas-liquid contact method, in which the outside of the hollow fiber separation membrane is liquid,
It is particularly effective when used in contact with water. That is, examples of pervaporation include water purification of tap water, deoxygenation of boiler water, deoxygenation of artificial dialysate, and examples of gas-liquid contact.
Examples include artificial lungs, culture tanks, water purification, and wastewater treatment.

[Conventional technology]

Hollow fiber membranes, which are one form of diaphragm for membrane treatment, are becoming mainstream as diaphragms for separation because they have a large surface area, can make devices compact, and are easy to manufacture as modules. The hollow fiber membrane is usually used in the form of a so-called module, which is incorporated into a hanging. The hollow fiber membrane module is sealed with resin at the end of the hollow fiber in order to separate the fluid that contacts the inside of the hollow fiber from the fluid that contacts the outside of the hollow fiber. As the sealing resin, epoxy resin, urethane resin, silicone resin, etc. are used, but since silicone resin is expensive, epoxy resin and urethane resin are the mainstream.

When sealing hollow fiber membranes using these resins, the first problem is the wettability of the hollow fibers with the sealing resin. Poor wettability makes it difficult for the resin to penetrate into the gaps between the bundles of hollow fibers.
Sealing errors are more likely to occur.

It is well known that wettability is determined by the surface energy of the hollow fiber and the sealing resin, and the smaller the surface energy of the hollow fiber, the worse the wettability. The material for hollow fiber membranes is
Various types are used depending on the purpose and usage conditions, but
When the surface energy is low like polyolefin, wettability with uncured epoxy resin or urethane resin is very poor.

The second problem with resin sealing of hollow fibers is adhesiveness. Generally speaking, polymers with poor wettability also have poor adhesive properties, and polyolefins cannot be chemically bonded with epoxy resins or urethane resins.If hollow fibers and sealing resin are not chemically bonded, hollow fibers and resin Leakage is likely to occur at the interface, which often causes problems when used under high pressure or for long periods of time.

Methods for improving the wettability and adhesion of polyolefins include the use of primers, chemical surface treatment with acids, alkalis, etc., corona discharge treatment, plasma treatment, radiation treatment,
Physical surface treatments and the like are known. If these treatments were to be carried out during membrane production, the hollow fibers would be treated continuously in the length direction, and the entire hollow fiber would be treated. However, depending on the membrane application, it is often necessary to keep the surface energy of the hollow fiber low. For example, in pervaporation or gas-liquid contact, where water comes into contact with the outside of the hollow fiber, the surface energy of the hollow fiber may be kept low. Since the problem of adhesion of microorganisms tends to occur, it is preferable that the membrane is hydrophobic, and in an external perfusion oxygenator, the membrane surface is preferably made of untreated polyolefin from the viewpoint of blood compatibility.

[Problem to be solved by the invention]

In imparting wettability and adhesion to the sealing resin to polyolefin hollow fibers, the present invention effectively oxidizes only the portions that come into contact with the sealing resin, and furthermore, the water introduced into the outside of the hollow fibers during use is effectively oxidized. The object of the present invention is to provide a module in which the part of the polyolefin hollow fiber that is in contact with the polyolefin fiber is left untreated and the part of the oxidized polyolefin hollow fiber is sealed with a resin.

[Means to solve the problem]

That is, the gist of the present invention is to provide a module in which a hollow fiber membrane made of polyolefin is loaded into a module case and whose ends are sealed with a resin, in which the hollow fiber membrane is sealed. There is a hollow fiber membrane module whose surface is treated with an oxidizing agent, and after the end of the hollow fiber membrane made of polyolefin is surface treated with an oxidizing agent, the hollow fiber membrane is placed in a module case. The method for manufacturing a hollow fiber membrane module comprises loading the hollow fiber membrane, and then sealing the oxidized portion of the hollow fiber membrane with a resin.

The hollow fiber to which the present invention is applied is made of polyolefin. That is, polyethylene, polypropylene,
Poly 4-methylpentene-1, poly 3-methylbutene-
1 etc. 0 Since the present invention performs surface treatment on the outer surface of the hollow fiber, when the hollow fiber membrane is a composite membrane, the material of the outer surface is polyolefin.

The functions and uses of hollow fiber membranes are not particularly limited, and can be used in general membrane processing fields, such as pervaporation (pervaporation) membranes, gas-liquid contact membranes, precision filtration membranes, ultrafiltration membranes, reverse osmosis membranes, etc. Although membranes can be applied, pervaporation membranes and gas-liquid contact membranes are particularly effective.

There is no need to specifically limit the structure of the membrane module, and the present invention can be applied to all hollow fiber membrane modules. Or, a three-dimensional & I assembly in which hollow fibers are braided into a layered or other sheet shape with other yarns, and the converged or superimposed body is incorporated into a module case, or hollow fibers are twisted around a core. For example, it is built into a module case. A membrane module having a structure depending on the use and purpose of the membrane module can be used.

Hollow fibers are formed into a shape such as a parallel bundle, a stack of sheets, a convergence of sheets, a core of sheets wrapped around a core, or a three-dimensional braid, and then processed with resin. The surface is oxidized by immersing only the end portions to be adhesively sealed in a liquid oxidizing agent. At this time, the length of the part to be surface treated is made slightly shorter than the length to be adhesively sealed with resin, so that the surface treated part is completely buried in the resin after sealing and comes into contact with the liquid introduced to the outside of the hollow fiber when the module is used. It is preferable not to do so.

Furthermore, in order to prevent the oxidizing agent from flowing into the inside of the hollow fibers during immersion in the oxidizing agent, it is also preferable to seal the ends of the hollow fibers with an adhesive, paraffin, or the like.

Liquid oxidizing agents for surface treatment include dichromic acid/l sulfuric acid mixture, potassium permanganate/concentrated sulfuric acid mixture,
Hydrogen peroxide/concentrated sulfuric acid mixed solution, fuming sulfuric acid, concentrated nitric acid, fuming nitric acid, chlorine water, dichromic acid aqueous solution, potassium permanganate aqueous solution, sodium perchlorate aqueous solution, potassium perchlorate aqueous solution, sodium chlorate acidic Aqueous solutions, potassium chlorate acidic aqueous solutions, etc. can be used. Among these, dichromic acid/concentrated sulfuric acid mixture and potassium permanganate/m-sulfuric acid mixture are preferred.

The surface-treated hollow fibers are washed with water and dried, and then loaded into a module case, sealed with resin, and end-faced by standard methods.

The sealing resin used in the present invention includes epoxy resin,
Urethane resins are particularly preferred.

〔Example〕

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Example 1 Poly 4-methylpentene-1 was formed into a hollow fiber shape by melt extrusion according to the method described in JP-A No. 63-274433, and was subjected to heat treatment, cold stretching, hot stretching, and heat setting. Outer diameter 233μm, inner diameter 187μm, oxygen permeation rate 1.51X10-'(cs'/cm", sec
, ca+Hg), and a hollow fiber membrane with an oxygen/nitrogen separation coefficient of 3.97 was obtained.

8,000 of these hollow fiber membranes were made into parallel bundles with a length of 320!1 m, and were mixed with concentrated sulfuric acid containing excess potassium dichromate.
After immersing only 20 parts from the end of the hollow fiber bundle at a temperature of 30°C for 1 minute, the bundle was thoroughly washed with running water and dried. The same operation was performed on the other end of the hollow fiber bundle.

This hollow fiber bundle was placed in a cylindrical housing made of transparent polycarbonate with an inner diameter of 35 mm and a length of 30 mm, and both ends were centrifugally sealed with a two-component polyurethane resin.
A module having a length of 300 mm including the sealing part as shown in FIG. 1 was manufactured by cutting the module. The thickness of the sealing resin was 15+m at the thinnest part. Since 10 m from both ends of the sealed hollow fiber are surface-treated portions, the surface-treated portions are completely buried in the sealing resin.

A cap 4 for providing an inlet is glued to this module, and tap water is introduced into the hollow fiber from the inlet 5 under pressure using a pump, and the flow rate is adjusted to 30 L/hr using a valve connected to the outlet 6. The water pressure at the inlet 5 was 4.0 kgf/c1aG.

At this time, a leak test was conducted to observe water leaking from the gas outlet 7 or 7' which was released to the atmosphere, and none of the 30 modules was found to have leaked water.

30% of clean water with a dissolved oxygen concentration of 7.8 ppm is placed inside the hollow fiber.
From the gas outlets 7 and 7' while flowing at a rate of L/hr,
The space in contact with the outside of the hollow fibers is vacuum pumped to approximately 3 Q t.
When the pressure was reduced to orr, the dissolved oxygen concentration of the water discharged from the outlet 6 was 0.5 ppm.

Comparative Example 1 Example 1 except that the surface treatment of the hollow fibers was not performed.
A hollow fiber membrane module was fabricated in the same manner. Water leaks were observed in two of the 10 units of this module.

Example 2 The same hollow fiber membrane used in Example 1 was fabricated using a chain knitting method using polyester yarns of 12 filaments (30 denier/filament) at a hollow fiber density of 25 pieces/cie.
A sheet having a warp density of 1 warp/cta71i was formed. A porous vibrator made of vinyl chloride with many holes made of this sheet 8
After the ends of the hollow fibers were surface-treated in the same manner as in Example 1, they were assembled into a housing and the ends were sealed with epoxy resin to obtain a hollow fiber length of 500 mm as shown in FIG. module. At this time, the polyester warp in the portion immersed in dichromic acid/concentrated sulfuric acid during the surface treatment process dissolved and disappeared, but the sealing was continued.

In the sealed module, the surface-treated portions of the hollow fibers, even at the thinnest portion of the epoxy resin, were located within the resin at least 5 degrees below the meniscum, and were completely buried in the resin. The effective membrane area (hollow fiber outer surface area) of the module was 8.81.

Tap water was introduced at a rate of 400 L/hr from the inlet 5 so as to be in contact with the outside of the hollow fibers of this module, and the gas outlet 7
．． 7' was depressurized with a water ring vacuum pump, the dissolved oxygen concentration of the water coming out of the outlet 6 was 0.41)l)-.Even after this test was continued for 3 months, no water was discharged. There was no change in the dissolved oxygen concentration of the water. Further, after 3 months had passed, this module was disassembled and the hollow fiber surface was observed, and no trace of microorganisms was observed at all.

〔Effect of the invention〕

By oxidizing the outer surface of the polyolefin hollow fibers in contact with the sealing resin, the module of the present invention improves the wettability of the uncured sealing resin, even when the hollow fibers have a high packing density. Stopping errors are reduced and manufacturing yields are increased. In addition, by improving the adhesion between the hollow fiber and the sealing resin, leakage at the interface between the hollow fiber and the resin is eliminated, increasing durability when used under high pressure or for long periods of time. In this case, the oxidized part of the hollow fiber does not come into contact with the fluid introduced during use, which poses a problem when the outside of the hollow fiber is exposed to water, for example in pervaporation or gas-liquid contact. The adhesion of microorganisms to the membrane surface is suppressed, and cleaning becomes easy.

In addition, in the external perfusion type oxygenator, an oxygenator having excellent blood compatibility can be manufactured with a high yield.

[Brief explanation of drawings]

FIG. 1 is a partially vertical sectional front view of the module used in Example 1, and FIG. 2 is a vertical sectional front view of the module used in Example 2. The symbols in the figure are as follows. DESCRIPTION OF SYMBOLS 1... Hollow fiber, 2... Housing, 3... Resin sealing part, 4... Cap, 5... Inlet port, 6... Outlet port, 7.7'... Gas Outlet, 8... Porous pipe, 9... Net.

Claims (1)

[Scope of Claims] 1. In a module in which a hollow fiber membrane made of polyolefin is loaded into a module case and its end portion is sealed with resin, the sealed portion of the hollow fiber membrane A hollow fiber membrane module characterized in that the surface of the module is treated with an oxidizing agent. 2. The hollow fiber membrane module according to claim 1, wherein the surface-treated portion of the hollow fiber membrane does not come into contact with the introduced liquid. 3. After surface-treating the end of the hollow fiber membrane made of polyolefin with an oxidizing agent, loading the hollow fiber membrane into a module case, and then sealing the oxidizing agent-treated portion of the hollow fiber membrane with a resin. A method for manufacturing a hollow fiber membrane module characterized by: