JPH08276123A - Crosslinked porous membrane - Google Patents

Abstract

PURPOSE: To obtain a membrane with high heat and chemical resistant properties, and excellent in characteristics such as low elution, hydrophilic and strength by using a crosslinked porous membrane consisting of an aromatic polyether ketone with a specific crystallinity and a crosslinking degree. CONSTITUTION: When thermally treating a water-soluble organic solvent, a crystalline aromatic polyether ketone(PEK) porous membrane which has 10 to 50wt.% crystallinity and 0.01 to 99.99% crosslinking degree, is obtained. The membrane having this crosslinking degree has excellent heat-resistant and mechanical properties. In addition, the membrane also is hydrophilic as a water-soluble organic solvent used as 1,4-butanediol works as a crosslinking agent. Further, PEK used here consists of units of repeatability indicated by -O-Ar-(O-Ar'-)n. Ar and Ar' are each an aromatic residue and Ar has at least one diaryl ketone bond. Ar and Ar' each covalently bonds with an ether group through an aromatic carbon atom. n is an integer of 0, 1 or 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinked crystalline aromatic polyether ketone (hereinafter abbreviated as PEK) porous membrane. More specifically, it relates to a crosslinked crystalline PEK porous membrane which is excellent in heat resistance, chemical resistance, low elution property, hydrophilicity and membrane strength and is useful for ultrafiltration membranes and microfiltration membranes.

[0002]

2. Description of the Related Art In recent years, polymer separation membranes have been widely used for ultra-pure water for electronic industries such as semiconductors, filtration and sterilization in medical devices, medicines, food applications and the like. The quantity tends to expand. Among them, higher film performance has been gradually demanded such as improvement in heat resistance and chemical resistance.
For example, in ultrapure water applications for semiconductors, there is little elution of ionic components and organic substances from the film material, and the film has excellent heat resistance and chemical resistance. In thermal power plants and nuclear power plants, it is 10
There is a demand for a film having particularly excellent heat resistance that can stably remove a clad (mainly fine particles containing iron as a main component) in condensate that exceeds 0 ° C. for a long time.

On the other hand, as the material for the separation membrane, conventionally, cellulose derivatives such as cellulose acetate, polyacrylonitrile resin, polyamide resin, polymethylmethacrylate resin, polysulfone resin, polyvinylidene fluoride resin, polyethylene resin, Polymer compounds such as polycarbonate resins are widely used as ultrafiltration membranes and microfiltration membranes. However, as mentioned above, the demand for membrane performance has increased, so these materials have low elution properties,
It was not satisfactory in terms of heat resistance and chemical resistance.

Now, PEK is drawing attention as a resin excellent in heat resistance, chemical resistance, and low elution property, and its application to a separation membrane has been attempted. For example, JP-A-2-2376
No. 28 and Japanese Patent Publication No. 3-47889 disclose PE.
A separation membrane made of a sulfonated material of polyether ether ketone, which is one of K-based resins, has been proposed. However, since sulfonated membranes swell in water,
It is known that its use range is limited (Mac
romolecules 86 p. 18 (1985)
reference).

Therefore, a non-sulfonated PEK membrane has also been proposed. For example, JP-A-2-136229 and JP-A-3-174321 propose a semipermeable thin film using PEKs having a specific structure. However, this film has not been subjected to heat treatment or the like, and its heat resistance level has not been exemplified. Further, there is no description regarding crystallinity and crosslinking.

[0006] Further, JP-A-3-237142, JP-A-3-56129, and JP-A-5-19255.
Japanese Unexamined Patent Publication No. 0 (1999) describes a microporous membrane made of crystalline PEK or an asymmetric membrane and a method for producing the same. However, no mention is made of crosslinking for this membrane either. Further, Japanese Patent Laid-Open No. 6-349 discloses that
It describes a charge-type separation membrane having an asymmetric structure, which has a dense layer cross-linked in the surface layer portion to which a haloalkyl group is bonded, and a method for producing the same. However, in this manufacturing method, a haloalkyl group is introduced into a polymer film material for modification, so that when the polymer is PEK, the crystallinity is lowered and a film having excellent heat resistance cannot be obtained. Further, even in the case of cross-linking only the surface layer portion, it cannot be said to be sufficient for use under the severe conditions as described above, for example. Therefore, a porous film made of crosslinked crystalline PEK has not been obtained.

On the other hand, as a method for crosslinking a polymer compound,
Although methods of radiating high-energy radiation such as an electron beam and methods of chemical treatment with peroxide etc. are known,
Not generally used for PEKs. By the way, as a method for crosslinking PEK, WO9119752 exemplifies a method for crosslinking the polymer by heat-treating the diarylketone-containing polymer in alcohol or alkoxide, or by subsequently contacting it with a strong acid for dehydration. . But in this way,
When it is applied to a porous membrane, it cannot be used because the membrane structure is destroyed or the membrane performance is severely deteriorated such as a decrease in water permeability.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a low elution property without impairing the heat resistance and chemical resistance inherent in PEK.
It is an object of the present invention to provide a crosslinked crystalline PEK porous film which has excellent film strength and hydrophilicity and can withstand use under severe conditions.

[0009]

[Means for Solving the Problems] The present inventors have been studying a crystallization method of a PEK porous film by heat treatment using a water-soluble organic solvent, and have controlled heat treatment conditions such as temperature and time. By doing so, it was found that the PEK porous film was crosslinked simultaneously with crystallization. Moreover, it has been found that a crystalline PEK porous film having a degree of crosslinking in a specific range has excellent heat resistance and mechanical properties. further,
Since the water-soluble organic solvent used acts as a cross-linking agent, it has been discovered that hydrophilicity can be imparted to the film, and the present invention has been completed.

That is, the present invention is as follows. [1] PEK having a crystallinity of 10 to 50% by weight and a crosslinking rate of 0.01 to 99.99%.
A cross-linked porous membrane made of. [2] The crosslinked porous membrane according to [1], wherein the crosslinking agent is a water-soluble organic solvent. Hereinafter, the present invention will be described in detail.

The PEK used in the present invention comprises a repeating unit represented by the following formula. This repeating unit may be of two or more types. -O-Ar- (O-Ar '-) _n (In the formula, Ar and Ar' are aromatic residues. Ar has at least one diarylketone bond. Ar and A
r'is covalently bonded to the ether group via an aromatic carbon atom. n is 0, 1, or 2. Among these, PEK in which Ar and Ar ′ are groups represented by the following formulas are preferably used in the present invention.

[0012]

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Particularly, in the present invention, the following general formulas (1) to (1)
PEK consisting of the repeating unit of 7) is preferable. These may be a homopolymer or a copolymer of two or more types.

[0014]

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Further, some or all of the hydrogen atoms of the aromatic ring constituting the above repeating unit are replaced with a halogen group, a nitro group,
It may be substituted with a nitrile group, an amino group, a phenoxy group, a phenyl group, a biphenyl group, an alkyl group, a functional group represented by the following formula, or the like.

[0016]

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The terminal of PEK used in the present invention is usually a phenyl group, a halogen group, a nitro group, a nitrile group, a phenoxy group, a biphenyl group, a group represented by the following formula, and the like.

[0018]

[Chemical 4]

Further, a part of the homopolymers or copolymers represented by the general formulas (1) to (17) contains other repeating units within a range that does not significantly deteriorate the original properties of the polymer. You can leave. Examples of such copolymerized units include those shown below.

[0020]

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In the present invention, particularly the general formulas (1) to
The repeating unit represented by (5), that is, PEK,
PEEK called PEEK, PEKK, PEEKK, and PEKEKK are industrially produced, and are easily available, so that they are suitably used as a membrane material. The PEK used in the present invention can be produced by a known polymerization method and is not particularly limited. For example, the Friedel-Crafts method can be mentioned. A related polymerization method is described in US Pat.
Nos. 205, 3442857, 3441538 and 3668057, German Patent Application Publication No. 2
206836 and J. Poly. Soi. , 5
5p. 741 (1961) (US). It can also be produced by a polycondensation method. For example, there are a method of polymerizing an aromatic dihalogen compound and a diphenol in the presence of an alkali salt, and a method of polymerizing an aromatic dihalogen compound and a carbonate. The former method is Japanese Patent Publication Sho 5
7-22938, U.S. Pat. No. 4,113,699, and JP-A-54-90296, and the latter method is described in JP-A-62-85708 and JP-A-62-85709. Has been described.

The PEK used in the present invention is preferably substantially non-sulfonated. The term "substantially non-sulfonated" as used herein means that a PEK polymer has a sulfonated phenylene group repeatedly in the determination of sulfur by nuclear magnetic resonance spectroscopy (NMR) or elemental analysis. It means that the unit is 10% or less. It is particularly preferably 5% or less. When it exceeds 10%, the heat resistance and chemical resistance of the obtained film tend to be lowered.

In the present invention, the "porous film" means
Porosity is in the range of 10-98%, protein in liquid,
It means a membrane having a selective separation ability for microparticles composed of bacteria, colloids, low molecular weight compounds, organic compounds and inorganic compounds, and is preferably used for ultrafiltration membranes and microfiltration membranes. The porosity is determined by the specific gravity method, mercury porosimetry method, or the like. It is also possible to impregnate a film with a non-volatile liquid and obtain the change from the weight of the film.

In the crosslinked porous membrane of the present invention, it is essential that the crystallinity is 10 to 50% by weight and the crosslinking rate is 0.01 to 99.99% as a requirement for exhibiting excellent membrane performance. . Among them, the crystallinity is 15 to 40% by weight and the crosslinking rate is 0.
05-80% is especially preferable. When the crystallinity is less than 10%, heat resistance and chemical resistance tend to decrease, and when it is 50% by weight or more, the toughness of the film tends to decrease, which is not preferable. When the crosslinking rate is less than 0.01%, the film strength is 99.9.
When it is 9% or more, the crystallinity and further the film strength tend to decrease, which is not preferable.

In the present invention, the crystallinity is represented by the weight ratio of the crystalline portion to the film weight. The crystallinity of such PEK is measured by the wide-angle X-ray diffraction method reported by Blundell and Osborn (Poly).
Mer, 24.953 (1983)). In the present invention, the crosslinking rate is represented by the weight ratio of the membrane weight of the insoluble portion of the porous membrane dissolved in concentrated sulfuric acid having a concentration of 96% or more and the membrane weight used for dissolution. In the present invention, the crosslinking rate is determined by the following method. About 1 g of PEK porous membrane was vacuum dried at 120 ° C. for 20 hours or more, dissolved in about 100 g of 96% strength sulfuric acid by stirring for 10 hours or more at room temperature, and then the insoluble portion was filtered with a glass sintered filter. To do. Next, the obtained insoluble portion is washed with water and ethanol to remove sulfuric acid, dried at 120 ° C. for 20 hours, and the film weight thereof is measured.

The crosslinked porous membrane of the present invention is formed by crosslinking with a crosslinking agent. The cross-linking agent has a solubility parameter value of 8 to 1
Organic solvents in the range of 7 are especially preferred. If the solubility parameter value deviates from the above range, the thermal stability and water permeability of the obtained membrane tend to be lowered, which is not preferable. Solubility parameters are described in many scientific literatures and scientific books, and in particular, the Polymer Data Handbook: Basic Edition (Polymer Society of Japan, Baifukan) has a table arranged for each solvent, which is suitable for the present invention. The cross-linking agent can be determined.

As the crosslinking agent used in the present invention, a water-soluble organic solvent having a solubility parameter in the above range is particularly preferable. The water-soluble organic solvent referred to here is 25 ° C., 100 g
Means an organic solvent soluble in water of 0.1 g or more. Preferred water-soluble organic solvents in the present invention include n-butanol, isobutanol, sec-butyl alcohol, t-butyl alcohol, n-pentanol, n-hexanol, 2-ethylbutanol, n-octanol, ethylhexanol, 1 -Dodecanol, 3,5
5, -trimethylhexanol, cyclohexanol,
Methylisobutylcarbimol, n-amyl alcohol, allyl alcohol, lauryl alcohol, benzyl alcohol, furfuryl alcohol, n-heptanol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, ethylene glycol , Diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, tetraethylene glycol, neophenyl glycol, 1,5-
Pentanediol, 2,4-pentanediol, 2,5
-Alcohols such as pentanediol, glycerin, polyethylene glycol, polypropylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, tri Ethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, propylene glycol dimethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, propylene glycol Glycol monoethyl ether, ethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, propylene glycol diethyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, triethylene glycol monoisopropyl ether, tetra Ethylene glycol monoisopropyl ether, propylene glycol monoisopropyl ether, ethylene glycol diisopropyl ether, diethylene glycol diisopropyl ether, triethylene glycol diisopropyl ether, tetraethylene glycol diisopropyl ether, propylene glycol diisopropyl ether Propyl ether, methyl-2-pentanediol 1,3, methyl -
Ethers such as 2-pentanediol-2,4, ethylhexanediol-1,3, 1,4-dioxane, 1,
Acetals such as 3-dioxolane, furan, furfural, and tetrahydrofuran, acetone, methyl ethyl ketone, methyl propyl ketone, methyl-n-butyl ketone, methyl amyl ketone, diethyl ketone, diisobutyl ketone, diisopropyl ketone, methyl isoamyl ketone, ethyl amyl ketone, methyl Isobutyl ketone,
Ketones such as methyl isopropyl ketone, formamide, N-methylformamide, N-ethylformamide, methylacetamide, N-ethylacetamide,
N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, pyridine, piperidine, N-acetylpiperidine, N-formylpiperidine, N-acetylpiperidine, N, Examples thereof include nitrogen compounds such as N-diacetylpiperidine, hydrazine, phenylhydrazine and ε-caprolactam, and mixtures thereof.

Among them, 1,4-butanediol, 1,
3-butanediol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, glycerin, polyethylene glycol, polypropylene glycol, N,
N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and mixtures thereof are particularly preferably used. Polyethylene glycol,
When polypropylene glycol is used, its molecular weight is not particularly limited, but the weight average molecular weight is 100 to 2000.
It is desirable that

In the present invention, when the above water-soluble organic solvent is used for cross-linking, hydrophilicity is imparted to the obtained membrane, and the fouling of the membrane is less likely to occur due to reduced adsorption of proteins and the like. Most preferred because it can prolong the life. In particular, for medical device applications, pharmaceutical manufacturing applications, etc., hydrophilized separation membranes with less adsorption of proteins and the like are required, and the membrane of the present invention can be preferably used.

In the present invention, the crosslinking point in the PEK molecule is not particularly limited. Further, the PEK molecules may be crosslinked to each other's ends or to each other's phenylene groups in the molecular chain so long as the crosslinkage ratio is satisfied. Further, in the film, there are no particular restrictions on the cross-linked part such as the film surface, the inside of the film, and the wall surface of pores, but the entire film is uniformly cross-linked because the heat resistance and mechanical properties are improved. Is preferred.

The crosslinked porous membrane of the present invention can remove a substance having a size of 0.001 to 10 μm dissolved or dispersed in a liquid such as water. The water permeability is 1 to 20,000.
The range is liter / m ² · hr · kg / cm ² . The water permeation amount is obtained by converting the volume of water obtained per unit time when distilled water at 25 ° C. is permeated through the membrane at a pressure of 1 kg / cm ² .

The membrane structure of the crosslinked porous membrane of the present invention is
There is no particular limitation as long as it has a known membrane structure suitable for use as an ultrafiltration membrane or a microfiltration membrane. For example, there is an opening on the surface of the film, a symmetric film in which the pore diameter inside the film is uniform in the film thickness direction, a dense skin layer on the film surface, and the pore size is different in the film thickness direction. A film or the like. Further, it may have a cylindrical hole penetrating both sides of the film.

In the present invention, the shape of the film is not particularly limited,
A flat membrane, a tube, a hollow fiber, a capillary, etc. are preferably used. The film thickness is not particularly limited, but usually 10
Those having a range of up to 5,000 μm are used. Further, the crosslinked porous membrane of the present invention may contain a water-absorbing polymer in a range that does not significantly deteriorate the original characteristics of PEK such as heat resistance, chemical resistance and low elution property. For example, polyethylene glycol, polypropylene glycol, polyethylene glycol alkyl ether, polyvinyl alcohol, polyamide, polyvinyl alkyl ether, dextrin, polyacrylic acid and its derivatives, polystyrene sulfonic acid and its derivatives, alginic acid and its derivatives, cellulose and its derivatives, ethylene- Vinyl alcohol copolymer, polyvinylpyrrolidone, sulfonated polyether ether ketone, sulfonated polyether sulfone, sulfonated polyether ether sulfone,
Alternatively, a mixture thereof may be used. These may be copolymerized as long as the membrane performance is not impaired.

The method for producing the crosslinked porous membrane of the present invention will be described below. The PEK crosslinked porous membrane of the present invention can be produced by a known method. For example, a method of forming PEK which has been crosslinked in advance into a porous film, a method of forming PEK into a porous film and then performing a crosslinking operation, and the like can be mentioned. Particularly in the present invention, a method in which an uncrosslinked PEK porous membrane is prepared in advance as a crosslinked porous membrane precursor and then a crosslinking operation is performed is preferable because it is easy to control the membrane performance such as the crosslinking rate.

This crosslinked porous membrane precursor can be produced by a known method. For example, PEK and a plasticizer or another thermoplastic polymer compound are mixed and melted, molded into a desired shape, cooled, and the plasticizer and the like are extracted with a solvent or the like to obtain a crosslinked porous membrane precursor. be able to. This manufacturing method is disclosed in, for example, JP-A-1-81832 and JP-A-3-237.
142, JP-A-3-174228, JP-A-3-106424, and JP-A-4-293533, which are particularly suitable for obtaining a symmetrical structure having a uniform pore size throughout the membrane. . It is also possible to mix the fine particles with PEK, melt-shape and then stretch to obtain a porous film, and this method is described in JP-A-7-776.

When the crosslinked porous membrane used in the present invention has an asymmetric structure in which the pore diameter is nonuniform in the thickness direction, the crosslinked porous membrane precursor obtained by the phase inversion method is usually crosslinked. It can be obtained by operating. The phase inversion method is
Developed by Leob and Sourirajan (Adv, Chem. Ser. 38, 117, 1963).
See) A general method for producing asymmetric membranes. Specifically, it is a method in which a stock solution for film formation in which a polymer compound is uniformly dissolved in a solvent is formed into a desired shape and then precipitated and solidified in a non-solvent for the polymer compound under specific conditions. In the case of a PEK porous film, PEK and a film-forming stock solution containing a solvent for the PEK as a main component are molded into a desired shape, and then immersed in a non-solvent for the PEK to precipitate and coagulate and remain in the film. Obtained by washing away the solvent. This method is described in, for example, JP-A-2-136229, JP-A-3-56129, and JP-A-3-174231.

In the present invention, when the crosslinked porous film precursor obtained as described above is subjected to the crosslinking operation, the crosslinking method is not particularly limited. Examples thereof include methods such as irradiation with electron beams and the like, heating, and chemical reaction with a crosslinking agent. Among them, a method of crosslinking the crosslinked porous membrane precursor by heat-treating it at a temperature not lower than the glass transition point of PEK and not higher than the melting point thereof in the crosslinking agent composed of the above water-soluble organic solvent is particularly preferable. When the heat treatment temperature is lower than the glass transition point, crystallization tends to be insufficient, and when the heat treatment temperature is higher than the melting point, severe film deformation is likely to occur, which is not preferable.

The glass transition point and melting point of PEK are
K means a temperature measured with a differential thermal analyzer at a temperature rising rate of 10 ° C./min. This depends on the structure of the repeating unit of PEK, but the glass transition point is generally 140-
200 degreeC and melting | fusing point are the ranges of 260-400 degreeC. Therefore, in the present invention, it is preferable to perform heat treatment in the range of 150 ° C to 330 ° C. To obtain a higher crosslinking rate and crystallinity, it depends on the heating time, but it is 200 to 330 ° C.
Is preferable, and the range of 240 to 300 ° C. is particularly preferable.

The heat treatment time is not particularly limited as long as the desired crosslinking rate is obtained, and is usually 10
The range is from seconds to 500 hours. In the present invention, the heat treatment during the crosslinking operation is preferably performed in a state where the crosslinked porous membrane precursor is immersed in the crosslinking agent. Further, the atmosphere for the heat treatment may be air or an inert gas such as nitrogen, argon or helium. When the cross-linking agent is thermally deteriorated by oxygen in the air during the heat treatment and the performance of the obtained film is deteriorated, the heat treatment under the inert gas is preferable.

Further, when the above heat treatment is carried out, when the film contains a low boiling point solvent such as water that boils at the heat treatment temperature, it is preferable to remove it in advance. Examples of the removal method include a method of immersing the membrane in a cross-linking agent and substituting it at a temperature below the glass transition point of PEK and below the boiling point of the low boiling point solvent to be removed. When the film contains a low-boiling point solvent during the heat treatment, the solvent may be vigorously vaporized on the surface and inside the film, which may deform or damage the porous film, which is not preferable.

In the present invention, it is preferable to carry out a washing treatment after the above heat treatment in order to remove the excess crosslinking agent remaining in the film. For example, it is desirable to wash with an organic solvent such as water, alcohols, and ketones such as acetone.

[0042]

EXAMPLES Examples of the present invention will be shown below. First, the measuring method of each physical property of the film will be described. Wide-angle X-ray diffraction of crystallinity An X-ray diffractometer MXP-18 manufactured by Mac Science Co. was used, and an X-ray generated by an accelerating voltage of 50 kv, an accelerating current of 200 mA and a Cu target was monochromated by a Ni monochromator and used. When the sample was a hollow fiber, the measurement was carried out by a transmission method, particularly using a fiber sample table. The scattered X-ray generated from the sample is scanned from 12 ° to 32 °,
50 points were taken per degree, and 1.2 seconds were measured per point. Blun to the obtained diffraction image
The crystallinity was determined by the method reported by Dell and Osborn (Polymer, 24.P.953 (1983)). Water permeation amount (when the membrane shape is a hollow fiber membrane) When distilled water at 25 ° C was applied at a pressure of 1 kg / cm ² to the inside of a hollow fiber single yarn having a length of 30 cm, it permeated to the outside of the membrane. The volume of distilled water was measured for 10 minutes, and the value was converted to liter / m ² · hr · kg / cm ² to obtain the value. Tensile strength Tensilon (Miebea Co., TCM-20) measured,
It was calculated by the following formula.

Tensile strength (kg / cm ² ) = load at break of film / cross-sectional area of film

[0044]

Example 1 920.0 g of concentrated sulfuric acid having a concentration of 88.2%
And PEK (glass transition point 150 ° C., melting point 372) having a reduced viscosity of 1.01 dl / g and comprising the repeating unit of the formula (1).
80.0 g) was added, and the mixture was stirred and dissolved in a closed-bottom separable flask having a volume of 1 liter for 10 hours in a closed system, and defoamed by a decompression method to obtain a uniform solution. The solution was used as a hollow fiber membrane-forming stock solution, and the membrane-forming stock solution was simultaneously discharged while discharging water at 26 ° C. as an internal coagulant from a hollow fiber manufacturing spinneret of a coaxial double tube. The stock solution for film formation is 10c from the spinneret.
It was dipped in a water bath of 24 ° C. provided below and solidified, and then wound up. The wound hollow fiber membrane was immersed in water at 40 ° C. for 12 hours and in ethanol at 25 ° C. for 10 hours so as not to be dried, to wash residual sulfuric acid. The obtained hollow fiber membrane has an inner diameter of 0.54 mm and an outer diameter of 0.97 m.
m and the crosslinking rate was 0%.

Then, the obtained hollow fiber membrane was treated with triglyceride at 60 ° C.
Add ethylene glycol for 3 hours, and add 240
A heat treatment was carried out by immersing in ethylene glycol for 2 hours.
After cooling to 30 ° C for 30 minutes, the hollow fiber membrane was
Take it out, immerse it in ethanol at 26 ° C, and
The glycol was washed off. The obtained hollow fiber membrane is a membrane
It has a dense skin layer on the surface and finger voids inside the film.
It was a porous membrane. Also, the porosity is 78% and the crystallinity is
Crosslinked porous membrane having a crosslinking rate of 0.2% at 25% by weight
Met. Water permeability of this membrane is 85 liters / m ²・ Hr
・ Kg / cm²Met.

[0046]

[Example 2] Except that heat treatment was performed at 260 ° C
The same operation as in Example 1 was performed. The obtained hollow fiber membrane has a membrane surface
Has a dense skin layer on the surface and has finger-like voids inside the film
It was a porous membrane. Also, the porosity is 78% and the crystallinity is 2
A cross-linked porous membrane having a cross-linking rate of 2.6% at 7% by weight.
there were. Water permeability of this membrane is 88 liters / m ²・ Hr ・
kg / cm²Met.

[0047]

[Example 3] The same operation as in Example 1 was carried out except that the heat treatment was carried out at 280 ° C. The obtained hollow fiber membrane was a porous membrane having a dense skin layer on the membrane surface and finger-shaped voids inside the membrane. In addition, the porosity is 76% and the crystallinity is 3
The crosslinked porous membrane had a crosslinking rate of 34% at 2% by weight. The water permeability of this membrane is 82 liters / m ² · hr · k.
It was g / cm ² . Furthermore, when the obtained hollow fiber membrane was pulled by hand, it had sufficient strength.

[0048]

Comparative Example 1 The same operation as in Example 1 was performed except that the heat treatment was carried out at 130 ° C. The obtained hollow fiber membrane was a porous membrane having a dense skin layer on the membrane surface and finger-shaped voids inside the membrane. In addition, the porosity is 78% and the crystallinity is 6
When the solution was dipped in 96% concentrated sulfuric acid at a weight ratio of 0% and the cross-linking rate was 0% and stirred, it was completely dissolved.

[0049]

Comparative Example 2 The same operation as in Example 1 was carried out except that the heat treatment was carried out at 390 ° C. in a closed system using an autoclave. The obtained hollow fiber membrane was severely deformed and was not a porous membrane suitable for a separation membrane.

[0050]

Example 4 Propylene was used instead of triethylene glycol.
Heat treatment at 250 ° C for 3 hours using ren glycol
The same operation as in Example 1 was carried out except that In the obtained
The hollow fiber membrane has a dense skin layer on the surface of the membrane and has a finger inside the membrane.
It was a porous film having a void shape. In addition, the porosity is 77
%, With a crystallinity of 31% by weight and a crosslinking rate of 2.8%
It was a crosslinked porous membrane. The water permeability of this membrane is 90 liters
/ M ²・ Hr ・ kg / cm²Met. In addition, obtained
The hollow fiber membrane has sufficient strength when pulled by hand.
I was

[0051]

[Example 5] Instead of triethien glycol, weight average
Using polyethylene glycol having an average molecular weight of 400, 26
Same as Example 1 except that the heat treatment was performed at 0 ° C. for 3 hours.
The operation was performed. The obtained hollow fiber membrane has a dense surface.
Porous membrane with skin layer and finger voids inside the membrane
Met. Also, the porosity is 75%, and the crystallinity is 29% by weight.
It was a crosslinked porous membrane having a crosslinking rate of 2.1%.
The water permeability of this membrane is 92 liters / m ²・ Hr ・ kg / c
m²Met. Furthermore, pull the obtained hollow fiber membrane by hand.
As a result, it had sufficient strength.

[0052]

Comparative Example 3 The same operation as in Example 1 was performed except that distilled water was used instead of triethylene glycol and the heating treatment was performed at 280 ° C. for 3 hours. The obtained hollow fiber membrane had a porosity of 73%, a crystallinity of 25% and a crosslinking rate of 0%, and was completely dissolved in 96% concentrated sulfuric acid. The water permeability of this membrane is 2 liters /
It was very low at m ² · hr · kg / cm ² or less. The tensile strength was 70% of that of the hollow fiber membrane obtained in Example 1.

[0053]

Comparative Example 4 P-xylene glycol at 100 ° C. was impregnated into the hollow fiber membrane before heat treatment obtained in Example 1 and then heat-treated in an oven at 360 ° C. for 15 minutes in a nitrogen atmosphere. . The obtained hollow fiber membrane was severely deformed and was not suitable for use as a separation membrane.

[0054]

Example 6 PEK comprising a repeating unit of formula (5)
The same operation as in Example 1 was performed except that (BASF Corporation, Ultrapec A2000) was used. The obtained hollow fiber membrane had a porosity of 81% and a crystallinity of 28% by weight and had a porosity of 0.3.
It was a cross-linked porous membrane having a cross-linking rate of%. Furthermore, when the obtained hollow fiber membrane was pulled by hand, it had sufficient strength.

[0055]

Example 7 The hollow fiber membrane before heat treatment obtained in Example 1 was sufficiently vacuum-dried until the weight did not change, and then the weight was measured. Then, the hollow fiber membrane is
It heat-processed in the triethylene glycol of (degreeC) for 5 hours.
After that, the hollow fiber membrane was subjected to Soxhlet washing with methanol for 50 hours, vacuum-dried, and the weight was measured. As a result, the membrane weight increased by 6%. Further, the membrane is subjected to Soxhlet cleaning for 50 hours using acetone for 50 hours,
When the weight was measured after vacuum drying, it was the same as that after washing with methanol. The crosslinking rate of the membrane was 42%, and triethylene glycol was present in the PEK porous membrane by bonding.

[0056]

EFFECT OF THE INVENTION The crosslinked porous membrane of the present invention is made of a PEK porous membrane having excellent heat resistance and chemical resistance and has a specific crystallinity and a cross-linking rate. It is possible to provide a porous membrane that has excellent low elution properties and strength and has improved hot water resistance and hydrolysis resistance. Further, hydrophilicity is imparted by crosslinking with a water-soluble organic solvent.

Since the crosslinked porous membrane obtained in the present invention has the above-mentioned excellent performance, it is suitable for ultrapure water for electronic industries such as semiconductors, filtration and sterilization in medical devices, pharmaceuticals, food applications, etc. It can be preferably used. Further, in a thermal power plant or a nuclear power plant, condensate water having a temperature of 100 ° C. or even 150 ° C. can be stably filtered for a long time.

Claims (2)

[Claims] 1. A crosslinked porous membrane made of aromatic polyetherketone having a crystallinity of 10 to 50% by weight and a crosslinking rate of 0.01 to 99.99%. 2. The cross-linking agent is a water-soluble organic solvent.
The crosslinked porous membrane described.