JPH0527448B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a hollow fiber membrane and a method for manufacturing the same.
In particular, the present invention provides a hollow fiber membrane which has a suitable separation ability and is excellent in durability as a separation membrane for a liquid mixture by a paper separation method. [Prior art and its problems] Hollow fiber membranes as liquid or gas separation membranes are useful in that they can form compact modules compared to flat membranes, so they are used in various applications such as medical treatment, pharmaceuticals, electronics, food, etc. It is widely used in the field of In addition, the pervaporation method (pervaporation method), which is effective as a separation technique for organic liquid mixtures or solutions of organic compounds, especially compounds with close boiling points, azeotropic mixtures, etc., has good separation ability and is suitable for industrial use. Separation membranes (hollow fiber membranes) with excellent durability are required. In other words, in this paper separation method, an organic liquid mixture is supplied to one side through a separation membrane, and the other side is reduced in pressure or vacuum to vaporize (evaporate) and take out specific liquid components. Therefore, hollow fiber membranes that have not only separation ability but also chemical resistance, heat resistance, mechanical strength, etc. are required. Conventionally, materials for hollow fiber membranes have been proposed such as cellulose, polyvinyl, polyamide, polyester, polysulfone, polycarbonate, polyimide, and other polymers, although they vary depending on the use (purpose). Among these, polymers generally known as engineering plastics have good heat resistance and chemical resistance, but hollow fibers that satisfy separation performance and durability at the same time are used as separation membranes in the paper separation method described above. It is still not enough material to obtain. [Means for Solving the Problems] In view of the above-mentioned problems, the present inventors have conducted intensive research and found that aromatic etherimide polymers subjected to a specific treatment have been found to be suitable for use in hollow fibers for separation, especially in perpaper ration methods. The present invention was completed based on the knowledge that this material is extremely effective as a material for membranes.
That is, the present invention is a hollow fiber membrane made of an aromatic etherimide polymer bonded with a quaternary ammonium base. The present invention also provides a hollow fiber membrane characterized by forming a hollow fiber membrane from an aromatic etherimide polymer into which a halomethyl group has been introduced, and then converting the halomethyl group of the hollow fiber membrane into a quaternary ammonium base using an amine compound. This is a method for producing a thread membrane. The hollow fiber membrane of the present invention has a chemical structure in which the matrix has a skeleton of an aromatic etherimide polymer, and the aromatic ring in the matrix molecule is bonded to a quaternary ammonium base; Preferably, the quaternary ammonium base is crosslinked via a hydrocarbon residue with a quaternary ammonium salt bound to another matrix molecule. The above aromatic etherimide polymer has an average molecular weight of 20,000 or more and has the following formula () It is a polymer skeleton consisting of repeating units, and has an aromatic ether unit and an aromatic imide unit in one molecule. In addition, the crosslinked structure of the aromatic etherimide polymer described above can be expressed by the following formula () (wherein, P is a divalent hydrocarbon residue, X is a halogen or hydroxyl group, and R and R' are each a monovalent hydrocarbon residue). The hollow fiber membrane of the present invention has the above-mentioned chemical structural characteristics, and thus exhibits good separation performance, especially as a separation membrane in the paper separation method, and has excellent heat resistance, chemical resistance, solvent resistance, and It has excellent mechanical strength.
That is, the hollow fiber membrane of the present invention does not exhibit the desired performance as a separation membrane for the paper separation method even if the matrix merely has the skeleton of an aromatic etherimide polymer having a structure as shown in the above formula (). I can't. In the production of hollow fiber membranes in the present invention, a hollow fiber membrane is formed from an aromatic etherimide polymer that has been halomethylated in advance to introduce halomethyl groups into the aromatic ring, and then an amine compound is reacted to convert the halomethyl groups into quaternary A desired hollow fiber membrane can be obtained by converting it into an ammonium base. The most important feature of the hollow fiber membrane manufacturing method of the present invention is that the halomethyl group introduced into the aromatic etherimide polymer is converted into a quaternary ammonium base using an amine compound. In this way, a strongly basic anion exchange group is introduced into the aromatic etherimide polymer, and by further selecting an amine compound, each tertiary amino group of the amine compound is different from the aromatic etherimide polymer molecule. Since the probability of reaction with the halomethyl group of the amine compound is extremely high, a crosslinked structure is formed between the molecules of the polymer via the hydrocarbon residues of the amine compound. Hereinafter, the manufacturing method of the present invention will be explained in detail. The aromatic etherimide polymer used in the present invention is a polymer having an ether bond and an imide bond in the repeating unit molecule, for example, the formula () described above or the formula ( ) (However, Ar ₁ and Ar ₂ represent divalent aromatic groups.) Generally, the average molecular weight is
20,000 or more is preferred. Such an aromatic etherimide polymer resin is commercially available from General Electric Company under the trade name "Ultem", for example. In the production method of the present invention, it is necessary to subject the aromatic etherimide polymer to halomethylation such as chloromethylation to introduce a halomethyl group into the aromatic ring. In the halomethylation reaction, a halomethyl ether such as chloromethyl ether is generally used as the halomethylating agent, and a Friedel-Crafts catalyst such as SnCl ₄ , TiCl ₄ , AlCl ₃ is used as the catalyst, and the halomethylation reaction is carried out by a conventional method. In order to carry out the process uniformly, a halogenated hydrocarbon such as 1,2-dichloroethane or tetrachloroethane is preferably used as a dissolving agent or swelling agent for the aromatic etherimide polymer. The degree of halomethylation in such an aromatic etherimide polymer is extremely important in order to obtain a good hollow fiber membrane, which is the object of the present invention, and it is generally expressed as the halogen content measured by the More method. 3-12
Weight percent is preferred. That is, when the degree of halomethylation described above is less than 3% by weight, the separation ability of the resulting hollow fiber membrane is insufficient. In addition, if the degree of halomethylation is greater than 12% by weight, the dope solution becomes highly viscous, making spinning difficult and resulting in poor molding yield of hollow fiber membranes. hollow fiber membranes with high performance cannot be obtained. The number of halomethyl groups introduced per repeating unit of the aromatic etherimide polymer calculated from the above-mentioned halogen content is generally 0.5 to 2.2. Also, proton
NMR measurements confirm that halomethyl groups have been introduced into the aromatic ring of the aromatic etherimide polymer. Next, in the present invention, a hollow fiber membrane is formed using a dope solution prepared by dissolving the above halomethylated aromatic etherimide polymer in a solvent. The solvent used for preparing this dope solution is not particularly limited as long as it dissolves the halomethylated aromatic etherimide polymer and is compatible with the organic solvent or water used in the coagulation bath described below. For example, Examples include dimethylacetamide, N-methyl-2-pyrrolidone, dimethylformamide, 2-pyrrolidone, and tetrachloroethane. In addition, the concentration of the halomethylated aromatic etherimide polymer in the dope solution is generally 10 to 30% by weight, particularly 15% by weight.
It is preferable to adjust the amount to 25% by weight. That is, if the concentration of the dope solution is less than 10% by weight, not only will the amount of solvent used increase, making it uneconomical, but also the resulting hollow fiber membrane will have a high porosity, and its mechanical strength will be weak, making it difficult to consolidate. The performance of the separation membrane is difficult to stabilize. In addition, if this concentration exceeds 30% by weight, the viscosity of the dope increases and it becomes difficult to flow, which not only makes it difficult to mold the hollow fiber membrane, but also makes defoaming difficult, resulting in residual air bubbles. Good performance such as permeability cannot be obtained from the resulting hollow fiber membrane. In the present invention, as a method for obtaining a hollow fiber membrane from the above-mentioned dope solution, a known method of extruding and molding the dope solution using an annular nozzle for producing hollow fibers is generally employed. For example, when using a tube-in-orifice type nozzle, a tube protrudes from the center of an orifice that opens at the center of the nozzle bed. This method forms hollow fibers by extruding the dope liquid from the tube and simultaneously supplying the core liquid from the inner hole of the tube. This core liquid is made by solidifying the dope liquid from inside the hollow fiber.
Moreover, any liquid that does not dissolve the halomethylated aromatic etherimide polymer of the dope liquid may be used, and water is generally used. Next, the thus formed hollow fiber membrane (uncoagulated) is quickly immersed in a predetermined coagulating liquid and coagulated from the outside of the hollow fiber, thereby obtaining a coagulated hollow fiber membrane. . The coagulating liquid may be water or an organic solvent that does not dissolve the halomethylated aromatic etherimide polymer and is compatible with the solvent of the dope liquid, such as methanol, ethanol, isopropyl alcohol, etc. Alcohols, ketones such as acetone and methyl ethyl ketone, ethers such as tetrahydrofuran and dioxane, and glycols such as ethylene glycol, and water (pure water), methanol aqueous solution, isopropanol aqueous solution, etc. are particularly preferred, and these two
Mixtures of more than one species can also be used. Furthermore, in the present invention, the hollow fiber membrane obtained above is immersed in a solution of an amine compound dissolved in water or a predetermined solvent to convert the halomethyl group of the hollow fiber membrane into a tertiary amino group of the amine compound. It is extremely important to convert the base into a quaternary ammonium base and form a crosslinked structure as necessary in order to obtain the desired hollow fiber membrane. The amine compounds used in the present invention include, for example, aliphatic tertiary amines such as trimethylamine, triethylamine, triethanolamine, and tributylamine, as well as primary and secondary amines, preferably generally aliphatic polyamines, or aromatic Any of the group polyamines may be used. In particular, polyamine compounds are preferred because they can easily form a crosslinked structure upon conversion of the quaternary ammonium base in the present invention.
Examples of such polyamine compounds include ethylenediamine, triethylenediamine, tetraethylenepentamine, polyethyleneimine,
NNN′N′-tetramethyldiaminomethane,
NNN′N′-tetramethylethylenediamine,
NNN'N'-tetramethyl-1,3-propanediamine, NNN'N'-tetramethyl-1,6-hexanediamine, NNN'N'-tetramethyl-1,
4-phenylenediamine, NNN'N'-tetramethylpenzidine, NNN'N'-tetramethyl-1,
Examples include 3-diamino-2-propanol. Among these, if it is not a tertiary amine,
After reacting with a halomethyl group, quaternary ammonium salting may be performed. Such amination and quaternization are also included in the quaternary ammonium salt in the present invention. Such a solution of an amine compound may be used by adjusting the amine concentration to generally 0.1 to 1.0 mol/ml using water, acetone, ethanol, methanol, isopropyl alcohol, benzene, toluene, etc. as a solvent. Furthermore, in the present invention, the reaction conditions for converting a halomethyl group into a quaternary ammonium base using a solution of an amine compound are generally room temperature to 80°C.
This is achieved by immersion treatment for 30 seconds to 100 hours. [Effects of the Invention] The hollow fiber membrane made of a charged (crosslinked) aromatic etherimide polymer provided in the present invention has the following properties:
Excellent as a separation membrane for paper separation,
In addition, it has good durability in terms of heat resistance, chemical (solvent) resistance, and mechanical strength, so it is particularly suitable for separating, concentrating, and purifying mixtures containing non-aqueous liquids such as mixtures of organic liquids or solutions of organic compounds. It is industrially useful in a wide range of fields including electronics, biochemistry, medicine, and food. Furthermore, specific non-aqueous liquids to which the hollow fiber membrane of the present invention can be applied include alcohols such as methanol, ethanol, isopropanol, and ethylene glycol, ketones such as acetone and methyl ethyl ketone, and aromatic liquids such as benzene, toluene, and xylene. group hydrocarbons, esters such as ethyl acetate and butyl acetate, methylene chloride, chloroform, trichlene,
Examples include halogenated hydrocarbons such as chlorobenzene. Of course, it can also be preferably applied to separation of the above-mentioned mixture of non-aqueous liquid and water. [Examples] Examples of the present invention will be shown below, but the present invention is not limited to these Examples. Example 1 Repeating unit represented by the following formula Aromatic etherimide polymer (trade name:
Ultem 1000 (manufactured by GE) 100g dichloroethane
After uniformly dissolving the mixture in 832 g at 50° C. under a nitrogen atmosphere while heating and stirring, 67 g of chloromethyl ether and 11 g of zinc chloride were added, and the mixture was reacted at 50° C. for 8 hours with stirring. Next, the reaction solution was cooled to 30° C., precipitated in a large amount of methanol, dried under reduced pressure, and then dissolved in a chloroform-methanol system and repurified. The obtained chloromethylated aromatic etherimide polymer had a chlorine content of 6.6% by weight as measured by the Mohr method, and the amount of chlorine introduced per repeating unit of the polymer calculated from this chlorine content was 6.6% by weight. The number of chloromethyl groups is 1.2. Furthermore, this chloromethylated aromatic etherimide polymer was evaluated using proton NMR method.
This matched the methylene group concentration appearing at 4.56 ppm, confirming that it was chloromethylated. From these analysis results, the structure of the chloromethylated aromatic etherimide polymer is identified as the following formula. (In the formula, a + b = 0.2 to 2.0) The above chloromethylated aromatic etherimide polymer was dissolved in a solvent of N-methylpyrrolidone to approx.
A homogeneous dope solution with a concentration of 20% by weight was prepared. Using this dope solution, a hollow fiber membrane is extruded from an annular nozzle for manufacturing hollow fibers, water is used as a coagulating liquid, and the hollow fiber membrane is coagulated from the inside and outside of the membrane.
A hollow fiber membrane with an outer diameter of 1.1 mm was obtained. Next, the above hollow fiber membrane was coated with N, N, N', N'-
Tetramethylethylenediamine (hereinafter referred to as
By immersing it in an acetone solution of each concentration shown in Table 1 of TMEDA (abbreviated as TMEDA) and performing a reaction treatment at the temperature and time shown in Table 1, a hollow structure made of a cross-linked charged modified aromatic etherimide polymer is formed. A thread membrane was obtained. Isopropyl alcohol (IPA) with an isopropyl alcohol concentration of 98% by weight was used as the liquid to be treated using a paper separation method fabricated by modularizing 100 hollow fiber membranes with a length of 150 mm obtained above. A separation test was conducted on a mixture of H 2 O and water (H ₂ O). The liquid to be treated was supplied inside the hollow fiber membrane at a liquid temperature of 60°C, and the degree of vacuum on the external permeation gas chamber side was 10 Torr. From the separation results, the amount of liquid permeated through the hollow fiber membrane Q (Kg/ ^m2・
hr) and separation coefficient α = (P _H2O /P _IPA ) / (F _H2O /
F _IPA ) are shown in Table 1. However, P _H2O = Water concentration on the permeate gas chamber side P _IPA = Isopropyl alcohol concentration on the permeate gas chamber side F _H2O = Water concentration in the liquid to be treated F _IPA = Isopropyl alcohol concentration in the liquid to be treated In addition, the above-mentioned chloromethylated aromatic The etherimide hollow fiber membrane was made into a module in the same manner as above without being subjected to the reaction treatment with TMEDA, and was subjected to a separation test of an IPA-H ₂ O mixture. The results were used as a comparative example (hereinafter abbreviated as ratio). It is shown in Table 1.

[Table] Example 2 In the chloromethylation reaction of Example 1, except that the reaction time was changed as shown in Table 2,
A chloromethylated aromatic etherimide polymer was obtained in the same manner as in Example 1. The chlorine content of the obtained chloromethylated aromatic etherimide polymer was measured by the Mohr method. Next, a hollow fiber membrane was formed in the same manner as in Example 1, and then subjected to a reaction treatment under the same conditions as No. 3 in Table 1. Each of the obtained hollow fiber membranes was made into a module in the same manner as in Example 1, and subjected to a separation test of an IPA-H ₂ O mixture. The results are shown in Table 2.

[Table] Example 3 A hollow fiber membrane was obtained in the same manner as in Example 1 except that the quaternization reaction conditions in Example 1 were changed, and the membrane was made into a module and used for a separation test of an IPA-H ₂ O mixture. The results are shown in Table 3.

[Table] In addition, when the performance was measured after a 24-hour continuous separation test, no change was observed in Q and α for Nos. 3 and 4, but about 20% of the change was observed for Nos. 1 and 2. α
A decrease was observed. This difference is presumed to be due to the effect of the crosslinked structure between polymer chains caused by the diamine. (Note) TMEDA...N,N,N',N'-tetramethylethylenediamine TMHDA...N,N,N',N'-tetramethyl-1,6-hexanediamine

Claims (1)

[Scope of Claims] 1. A hollow fiber membrane made of an aromatic etherimide polymer bonded with a quaternary ammonium base. 2. The hollow fiber membrane according to claim 1, comprising an aromatic etherimide polymer crosslinked by hydrocarbon residues bonded to quaternary ammonium bases. 3. The hollow fiber membrane according to claim 1 or 2, which is a separation membrane of the paper separation method. 4 Production of a hollow fiber membrane characterized by forming a hollow fiber membrane from an aromatic etherimide polymer into which a halomethyl group has been introduced, and then converting the halomethyl group into a quaternary ammonium base by reacting with an amine compound. Method. 5. The method for producing a hollow fiber membrane according to claim 4, wherein the amine compound is a polyamine compound.