JPS62104970A - Functionating treatment of hollow yarn membrane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for functionalizing porous hollow fiber membranes.

In the present invention, functionalization treatment refers to properties that the original porous hollow fiber membrane has, such as hydrophilicity, antistatic property, biocompatibility, adsorption of specific substances such as dyes, proteins, and lipids, antibacterial properties, and high water repellency. A functional monomer refers to a treatment that imparts a function to the porous hollow fiber membrane that it does not already have, and a functional monomer refers to a monomer that has the ability to impart the above function to the porous hollow fiber membrane when bonded to the porous hollow fiber membrane.

[Conventional technology]

As hollow fiber membranes, membranes made of various materials such as cellulose, polyolefin, and polysulfone have been developed and used in fields depending on the characteristics of each material.

However, as the development of membrane applications progresses, there are an increasing number of applications that require multiple functions such as chemical resistance, hydrophilicity, biocompatibility and adsorption capacity, hydrophilicity and antibacterial properties, heat resistance and hydrophilicity, etc. Some of these functions originally have conflicting properties, so there are problems such as there is no material that satisfies both, or materials that have multiple specific functions are difficult to synthesize, or it is difficult to make into hollow fiber membranes. In addition, there was an economic problem in that selecting materials for each specific application and making them into °C hollow fiber membranes would result in a lot failure and development costs would be too high.

Therefore, functionalized optical surface treatment methods that impart new functions to existing microporous hollow fiber membranes have been actively investigated.

For example, a method of imparting hydrophilicity to a polyolefin film is to apply a surfactant (Japanese Patent Laid-Open No. 47-142
No. 69) and those in which (meth)acrylic acid is graft-polymerized after irradiation with radiation such as γ-rays (Japanese Patent Laid-Open No. 55-10623)
Publication No. 9).

[Problem that the invention seeks to solve]

The former has the problem that the surfactant gradually falls off during use and elutes into the processing solution at ℃, and the latter has the problem that it is difficult to control the radiation source and is not suitable for general industrial use, or the radiation is high energy. Therefore, there was a problem that the hollow fiber membrane material was easily damaged.

Furthermore, the latter is particularly a microporous hollow fiber membrane in which the micropores are formed in the spaces between the fibrils created by the fibrils laminated in multiple layers from the inner wall surface to the outer wall surface of the hollow fibers and the knots that fix both ends of the fibrils. When using a hollow fiber in which micropores are interconnected as spaces between the fibrils and penetrate from the inner wall surface to the outer wall surface of the hollow fiber, a membrane using contour energy rays that cuts the fibrils, which determines the fractionation characteristics of the membrane, is used. The disadvantage was that it was difficult to use because of the large amount of damage.

[Means for solving problems]

In view of the current situation, the inventors of the present invention have conducted intensive studies on a method for functionalizing microporous hollow fiber membranes that has excellent adhesion properties, productivity, and durability, and causes less damage to the membrane.As a result, the present invention has been developed. reached.

That is, the gist of the present invention is to provide a method for functionalizing a hollow fiber membrane, in which a microporous hollow fiber membrane is impregnated with a reaction solution containing a functional 7mer and a photosensitizer, and a cleaning treatment is performed after irradiation with ultraviolet rays. be.

As the functional hexamer used in the present invention, hexamers having various functional groups can be used depending on the function to be imparted.

In order to impart hydrophilicity, biocompatibility, and electrical conductivity, for example, -NH, -OH, -COOH, +OC, H,
80H group, to QC, H6 fortune OH1÷QC, H, sushi OCH
Monomers having hydrophilic groups such as ,,N"f CHI )* groups are used, examples of which include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, acrylic acid, methacrylic acid, acrylamide,
Dimethylaminoethyl acrylate, N-hydroxyethyl-N-methylacrylamide, N-hydroxymethylacrylamide, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate,
Polyglopylene glycol monoacrylate, 2-methacryloyloxyethyl succinate, vinylpyrrolidone,
Examples include vinylpyridine.

In addition, when imparting the function of adsorbing pigments, proteins, lipids, etc., -8o, I (group, -8O3Nm group, -0SO).

Monomers having Na groups are used, examples of which include 2
-acrylamido-2-methylpropanesulfonic acid, sulfoethyl acrylate, sulfopropyl acrylate, sulfophenyl acrylate, etc.
When imparting an antibacterial function as well as an adsorption function for pigments, proteins, lipids, etc., -NmoCH, ), CH, SO, - group,
Monomers having a -N (CHs)sC/- group are used; examples of such monomers include acryloyloxytrimethylammonium chloride and methyl sulfate of trimethylaminoethyl methacrylate.

On the other hand, for example, 3,3,3,2.2-pentafluoropropyl acrylate, 1,1,1,3,3.3-hexafluoroglobyl methacrylate, 22,33°44.5
÷CF of 5-octafluoropentyl acrylate, etc.
) Monomers having perfluoroalkyl groups such as F groups provide a high degree of water repellency.

In addition, acryloyloxyethyl phosphate, methacryloyloxyethyl 7 phosphate, etc.
OH), a monomer having a group imparts hydrophilicity and antistatic properties.

These functional monomers can be used alone or in a mixture of two or more to the extent that they can function together.

In addition, in consideration of the graft activity upon irradiation with ultraviolet rays, the functional monomer is preferably a monomer having an acryloyloxy group, a methacryloyloxy group, or an acrylamide group as a polymerizable group.

The photosensitizer used in the present invention is one that can absorb and excite photons, extract hydrogen from the material constituting the microporous hollow fiber membrane that is the base material, and form radical active sites on the base material. Examples of such photosensitizers include benzophenone, 3°3', 4,4'-benzophenone tetracarboxylic anhydride, 4,4'-dimethoxybenzophenone, 4-chlorobenzophenone, and 2,4-dichlorobenzophenone. , 4,4'-dichlorobenzophenone, 4-
Fluorobenzophenone, 4-trifluoromethylbenzophenone, 4-methoxybenzophenone, 4-methylbenzophenone, 4.4'-dimethylbenzophenone, 4
- benzophenone photosensitizers such as cyanobenzophenone and Q-pensoylbenzophenone, benzyl photosensitizers such as benzyl and dibenzyl ketone, 2-methylthioxanthone, 2-ethylthioxanthone, thioxanthone,
Thioxanthone photosensitizers such as 2-isopropylthioxanthone, anthraquinone photosensitizers such as anthraquinone, 2-ditylanthraquinone, 2-chloroanthraquinone, 2-t-butylanthraquinone, benzaldehyde, 4-methoxybenzaldehyde, Benzaldehyde photosensitizers such as 4-methylbenzaldehyde and 1-nataldehyde, diion photosensitizers such as 2,3-butanedione and 2,3-pentanedione, dibenzosuberone, methyl-〇-pensoylbenzoate , 9-fluorenone, 3,4-benzofluorene, l-acetylnaphthalene, benzanthrone, 9,10-phenanthrenequinone, 2-benzoylnaphthalene, 3,5-dimethylacetophenone, 4-bromoacetophenone, and the like.

Conventionally, a combination of a photosensitizer such as benzophenone, benzyl, or 2-methylthioxanthone and a compound that easily releases hydrogen such as jetanolamine or diethylamine has been used as a photopolymerization initiator. However, the radicals generated by exciting such a combination with light have a low hydrogen abstraction ability, and even if such a combination is used as a photosensitizer of the present invention, it will have a very low hydrogen abstraction ability. It is not possible to form radical active sites in the porous hollow fiber membrane, and even if a functional monomer coexists in the system, only a homopolymer from the functional monomer is generated, making the porous hollow fiber membrane functional. I can't process it. Therefore, the photosensitizer of the present invention is used without the coexistence of a compound that easily abstracts hydrogen, such as an amine.

In the present invention, the material of the microporous hollow fiber membrane to be functionalized is not particularly limited;
Polyolefins such as polyethylene and polypropylene are preferred because they are relatively inexpensive materials, easy to process, and have excellent chemical resistance.

In addition, the structure of the microporous hollow fiber membrane is such that the micropores are formed in the spaces between the fibrils, which are formed by the fibrils laminated in multiple layers from the inner wall surface to the outer wall surface of the hollow fibers, and the knots that fix both ends of the fibrils. It is preferable that the micropores are connected to each other as spaces between the fibrils and penetrate from the inner wall surface to the outer wall surface of the hollow fiber, since it is possible to prevent relatively small particle diameters and increase the 1 excess amount. However, the method of the present invention causes less damage, and the hydrogen-drawing photosensitizer allows hydrogen to be easily drawn from hollow fiber membranes. This is suitable because it can easily form a radically active part that can be extracted and grafted with a functional monomer.

Such a hollow fiber membrane has the above-mentioned structure, and (b) the average thickness (dM) and average length (A'M) of the fibrils are ctM=0.02-0.3μ JM= 0.5 to 3.0μ, and (b) the average length of the knot in the fiber length direction A'K)
is Jx = 0.1 to 1.0 μ, and (/-1 average width of pores formed between fibrils (
Self V) and average length Jv) are 1vldv
A preferable example is a polyethylene hollow fiber having a porosity of 30 to 90 mo1%, in which the relationship between dv and ctM is dv/9=0.3 to 5.

Polypropylene hollow fibers as shown in Japanese Patent Publication No. 56-52123 are also preferably used.

In the method of the present invention, a microporous hollow fiber membrane is impregnated with a reaction solution containing a functional monomer and a photosensitizer as described above. If the sensitizer is soluble in the functional monomer, only the two can be used as the reaction solution, but if the system has high viscosity at room temperature, the photosensitizer is not sufficiently soluble, or is solid. In this method, a reaction solution prepared by dissolving both a functional monomer and a photosensitizer in a solvent capable of dissolving them is used. Examples of such solvents include acetone, methyl ethyl ketone, ethyl acetate, and the like.

The molar ratio of the functional monomer and photosensitizer is preferably 1000-1/1, preferably 100-1.
More preferably, it is 5/1. If the molar ratio of the two is greater than 1000/1, the functionality will be expressed, but the filtration rate will tend to decrease, and if the molar ratio is less than 1/1, the usage efficiency of the photosensitizer will deteriorate, The degree of polymerization of the grafted functional monomer does not increase sufficiently, and functionality tends to be insufficient.

The microporous hollow fiber membrane can be impregnated with the reaction liquid by applying the reaction liquid to the hollow fibers in a shower or curtain form, but it is better to use the dipping method, which allows the reaction liquid to be impregnated more uniformly. It is preferable because it can be done. Furthermore, when using the dipping method, by making the opening of the reaction liquid impregnating tank through which the hollow fibers pass small, it is possible to impregnate the hollow fibers with the reaction liquid under pressure or reduced pressure.

In the present invention, the microporous hollow fiber membrane impregnated with the reaction solution is irradiated with ultraviolet rays to carry out graft polymerization. It is preferable that the proportion of monomer to X child is 0.1 to 1001 it%, and 0.
More preferably, it is 5 to 50% by weight. Even if the grafting rate exceeds 100% by weight, there is no improvement in functionality;
This results in a reduction in overspeed and a grafting rate of o,1! If it is less than t%, it is difficult to obtain sufficient functionality.

Another way to set the grafting ratio within a preferable range is to adjust the amount of functional monomer with which the hollow fiber membrane is impregnated, the energy of ultraviolet irradiation, etc.

The amount of functional monomer impregnated is 0.1 to 50% based on the weight of the hollow fiber.
It is preferable to set it to 0% by weight, and the ultraviolet irradiation energy is measured at a wavelength of around 365 nm, and I
0 Joule/cm” is preferable, and 5
More preferably, it is 10 to 1 joule/crrL'.

Considering the polymerization inhibiting effect of oxygen, the atmosphere during ultraviolet irradiation is preferably an inert gas such as carbon dioxide, nitrogen, or helium.

For ultraviolet irradiation, ultraviolet rays emitted from xenon lamps, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, etc. can be used, but in consideration of productivity, it is preferable to use ultraviolet rays that have as high irradiation efficiency as possible and generate as little heat as possible. From this point of view, a high-pressure mercury lamp with an electrical input of about 10 W/cwt to 300 W/cm is preferably used.

The time until the hollow fiber membrane impregnated with the reaction solution is irradiated with ultraviolet rays can be left for a long time if the functional monomer has good adhesion to the hollow fiber membrane, but if the functional monomer has poor adhesion, When using a 7-mer, the hollow fiber membrane of the base material repels the functional monomer, making it impossible to obtain the desired performance.

In particular, when using a polyolefin material such as polyethylene or polypropylene as the material for the hollow fiber membrane, it is easy to repel functional nitrates, so it is preferably within 30 minutes, more preferably 10 minutes after impregnating the hollow fiber with the reaction solution. irradiate with ultraviolet light within

The microporous membrane irradiated with ultraviolet rays is then washed to remove by-products such as homopolymers and photosensitizers. For cleaning, a homopolymer of functional monomers, a photosensitizer,
A liquid is used that can dissolve or disperse the decomposed products and does not substantially damage the hollow fibers. As the liquid, various bath agents such as water and organic solvents can be used depending on the type of functional monomer and photosensitizer, and surfactants, wetting agents, etc. may be added to improve the cleaning effect.

Although the cleaning may be carried out by extraction using the above-mentioned cleaning solution, it is preferable to use ultrasonic waves during cleaning to improve cleaning efficiency and shorten cleaning time.

The strength of the ultrasound is 0.01 to 2. It is preferable to adjust the ultrasonic wave at O atmospheric pressure to hit the hollow fibers from 0.05 to 1.
．． More preferably, the strength is 0 atmospheres. If the strength of the ultrasonic waves is less than the lower limit, there will be little improvement in cleaning efficiency, and if it exceeds the upper limit, there is a risk of deterioration of the hollow fibers.

It is preferable that the time from the end of ultraviolet irradiation to washing is not more than 30 minutes, and more preferably less than 10 minutes. If this time exceeds 30 minutes, effective cleaning cannot be performed, and as a result, the C overrate of the hollow fiber membrane decreases due to insufficient cleaning, and cleaning takes a long time.

〔Example〕

The present invention will be explained in more detail below using Examples.

In addition, hydrophilicity as one of the functionalities was evaluated using the water permeability pressure described below.

Hydraulic pressure measurement method A hollow fiber bundle was prepared in which one end was focused and fixed with a sealing member, and the other end was focused and fixed with the opening of the hollow fiber end left open, and this was used as a test specimen for hydraulic pressure.

0.2 every 30 seconds from Oyu/crrL” to this hollow fiber bundle.
The hollow fiber bundle was visually observed while water was injected from the open end of the hollow fibers so that the pressure increased by 9/an'. While this pressure is low, water does not come out from the east side of the hollow fiber, but
When the pressure exceeds a certain level, water begins to seep out, and when the pressure is increased further, water starts to seep out from the entire hollow fiber above a certain pressure. The pressure at which water begins to seep out from the entire hollow fiber is defined as the water permeability pressure of the hollow fiber.

Since the higher the hydrophilicity of the hollow fiber, the lower the water permeability pressure, this water permeability pressure can be used as a measure of hydrophilicity.

Ultrasonic intensity ultrasonic meter UTK-30 type (Nippon Tokushu Kogyo Co., Ltd.) #
).

Membrane area 20crIL using water flux hollow fiber! After creating a mini-module and filling this module with ethyl alcohol to make the hollow fibers hydrophilic, the ethyl alcohol was replaced with water, and then water was removed by applying a water pressure of 0.01 to 0.2 Y/α8. It was determined by the amount of permeated water per unit area under unit pressure and unit time.

Example 1 The micropores are formed in the spaces between the fibrils, which are formed by the fibrils laminated in multiple layers from the inner wall surface to the outer wall surface of the hollow fiber and the knots that fix both ends of the fibrils. A microporous polyethylene hollow fiber having the characteristics shown in the column of Example 1 of Table 1, which is interconnected as a space between the hollow fibers and penetrates from the inner wall surface to the outer wall surface, is made of acrylamide 1421 and benzophenone 73. and acetone 10001, and slowly immersed in a reaction solution consisting of 4 to 5 cIIL/81! The hollow fibers were pulled up at a speed of 100 m to impregnate the hollow fibers with the reaction solution. The amount of acrylamide attached to the hollow fibers was 60% by weight. After air-drying this for 3 minutes, it was irradiated with ultraviolet rays for 2 seconds in a nitrogen atmosphere using a 2KW standard high-pressure mercury lamp. The amount of UV irradiation is 0.09
Then, within 10 minutes after UV irradiation, while applying ultrasonic waves at an intensity of 0.4 atm, the hollow fibers were washed with a cleaning solution of butyric acid/water = 1/1 weight ratio. Washed 4 times, changing to fresh washing solution every minute.

Table 1 shows the results of examining the performance of the washed hollow fibers after air-drying them overnight.

Incidentally, the performance of the hollow fiber before the treatment is shown in Reference Example 1 in Table 1.

Examples 2 and 3 The procedure was the same as in Example 1, except that polyethylene hollow fibers having the same structure and having the properties shown in the columns of Example 2 and Example 3 in Table 1 were used.

The performance of the obtained hollow fibers is shown in Table 1, and the performance of the hollow fibers before treatment is shown in Reference Examples 2 and 3 of Table 1.

In addition, the amount of acrylamide attached was 20% by weight in Example 2,
Example 3 had a content of 5% by weight.

Table 1! 1 σ As is clear from Table 1, the water permeability pressure is reduced by the treatment of the present invention. In particular, it can be seen that in the membrane of Example 1, the water permeability pressure decreased significantly, and the water flux also improved.

Examples 4 to 6 The average inner diameter is 88-270 tt, the average film thickness is 70 am, and the porosity is 63%, and the micropores are numerous from the inner wall surface to the outer wall surface of the hollow fiber. The micropores formed in the spaces between the fibrils created by the R-layered fibrils and the knots that fix both ends of the fibrils are interconnected as spaces between the fibrils and penetrate from the inner wall surface to the outer wall surface of the hollow fiber. Yes, "/cLm = 0.8 and Jv/d
Example 1 except that a microporous polyethylene hollow fiber having the characteristics v = 5 (7) was used, a reaction solution having the composition shown in Table 2 was used, and the ultrasonic intensity was 0.5 atm.
I did the same thing.

The amount of functional monomer (acrylamide, acrylic acid, or 2-hydroxyethyl acrylate) adhered after impregnating with the reaction solution was 30 fUm%, 30 weight%, and 40 weight percent, respectively.
%Met.

The performance of the treated hollow fiber is compared with that of the untreated hollow fiber (Reference Example 4)
) are shown in Table 2.

Table 2 Example 7 A microporous polypropylene hollow fiber having an extremely thick distribution of micropore radii of 1100A, an average inner diameter of 200μ, an average membrane thickness of 22μ, and a porosity of 45% was prepared using acrylamide 71T, Benzophenone 73J' and acetone 100
An experiment was conducted in the same manner as in Example 1 except that a reaction solution consisting of OJ' was used. The amount of acrylamide deposited was 20% by weight. Further, the grafting rate of acrylamide was 5% by weight.

The permeability pressure and water flux of untreated polypropylene hollow fibers are 20 kg/crn' or more and 0.21/crn', respectively.
hr, rn', +smHg, but the water permeability pressure of the acrylamide photografted material was 18.5 kg/cr.
n', the water flux is 0.22 sentences/hr, r
n', msHg.

Comparative Example 1 An experiment was conducted in the same manner as in Example 1 except that the same hollow fibers as used in Example 1 were used and benzophenone was not used.

The obtained hollow fibers were not grafted with any functional monomer, and the performance of Example 7 was the same as that of Reference Example 1.

Comparative Example 2 Using the same hollow fiber as used in Example 1, without using benzophenone, in a nitrogen atmosphere instead of ultraviolet irradiation, 20M
The same procedure as in Example 1 was carried out except that rad electron beam was irradiated. The graft ratio of the obtained hollow fiber was 0.1, and the permeation water pressure was slightly lower to 5.8, but the elongation at break was 5% and the strength at break was 150 g/fil, which was the same as that obtained in Example 1. Hollow fiber elongation at break is 17% and strength at break is 260g/fit
The strength and elongation were lower than that of the original.

Patent applicant: Mitsubishi Rayon Co., Ltd. Agent, Patent attorney: Toshio Yoshizawa (Retest procedure amendment filed on February 13, 1986, Director General of the Patent Office, Michibe Uga, 1, Indication of case: 1986-243697, 2, Invention) Name of Hollow Fiber Membrane Functionalization Treatment Method 3, Relationship with the Person Making the Amendment Case 2-3-19 Kyobashi, Chuo-ku, Tokyo (603) Mitsubishi Rayon Co., Ltd. President and Director Akio Kawasaki 4, Representative Tokyo 2-3-19 Kyobashi, Chuo-ku, Tokyo (visual correction) 6. Subject of amendment (1) Add the following sentence in its entirety to the arrow on line 6 of member 26 of the specification.

"Examples 8 to 11 Using the same polyethylene hollow fibers as in Example 1 and 9,
A reaction solution having the composition shown in Table 3 was used. 1 After the reaction solution was impregnated, the air drying time was 2 minutes, the ultraviolet irradiation time was 2 seconds (ultraviolet irradiation amount CL 12 joule/crnz), and the weight ratio of acetic acid/ice and snow was 171. Instead of washing 4 times for 3 minutes each with a cleaning solution of
The procedure was the same as in Example 1 except for the following.

Table 3 shows the performance of the hollow fibers obtained.

Table 3 Examples 12 to 15 Using the same polyethylene hollow fibers as those used in Example 5,
The reaction solution was treated in the same manner as in Example 8 except for the reaction solution having the composition shown in Table 4. The performance of the obtained hollow fibers is shown in Table 4.Table 4 Example fl116 The same procedure as in Example 5 was carried out except that the same polypropylene hollow fibers as used in Example 7 were used as the hollow fibers. obtained n
The hollow fiber graft force was &5 fold, and the permeability pressure was 14.6 K! ? /1M”, water flux is α18
L/hr-m"mmHg."

Claims (7)

[Claims] (1) A method for functionalizing a hollow fiber membrane, in which a microporous hollow fiber membrane is impregnated with a reaction solution containing a functional monomer and a photosensitizer, and a cleaning treatment is performed after irradiation with ultraviolet rays. (2) The method for functionalizing a hollow fiber membrane according to claim 1, wherein the microporous hollow fiber membrane is made of polyolefin. (3) The microporous hollow fiber membrane has micropores formed in the spaces between the fibrils, which are formed by the fibrils laminated many times from the inner wall surface to the outer wall surface of the hollow fibers and the knots that fix both ends of the fibrils. Functionalization of the hollow fiber membrane according to claim 1 or 2, characterized in that the pores are interconnected as spaces between the fibrils and penetrate from the inner wall surface to the outer wall surface of the hollow fiber. Processing method. (4) The average thickness (@d@_M) and average length (@l@_M) of fibrils are @d@_M=0.02 to 0.
3 μm, @l@_M = 0.5 to 3.0 μm, and the average length of the node in the fiber length direction (@l@_K) is @l@_
K = 0.1 to 1.0 μm, and the average width (@d@_V) and average length (
The relationship of @l@_V) is @l@_V/@d@_V=3~5
0, and the relationship between @d@_V and @d@_M is @d@_V
4. The method for functionalizing a hollow fiber membrane according to claim 3, wherein /@d@_M=0.3 to 5. (5) The method for functionalizing a hollow fiber membrane according to claim 1, wherein the functional monomer is a monomer having an acryloyloxy group, a methacryloyloxy group, or an acrylamide group. (6) The method for functionalizing a hollow fiber membrane according to claim 1, wherein the photosensitizer is a benzophenone compound. (7) The method for functionalizing a hollow fiber membrane according to claim 1, wherein the cleaning treatment is a cleaning treatment using ultrasonic waves.