JPH0419890B2 - - Google Patents

Description

[Detailed description of the invention]

<Summary> The present invention relates to a hollow fiber membrane made of polyphenylene sulfide resin, more specifically, a polyphenylene sulfide hollow fiber membrane having a dense surface layer on the inner surface and a spongy texture layer in contact therewith. It relates to its manufacturing method. An object of the present invention is to industrially advantageously obtain a hollow fiber membrane with a small inner pore diameter and less clogging. Polyphenylene sulfide was originally developed as an engineering plastic, so it has excellent heat resistance, is not attacked by acids or alkalis, has excellent chemical resistance, and has excellent mechanical properties and flame retardancy. ing. Focusing on these points, the present inventors conducted intensive research on polyphenylene sulfide hollow fiber membranes and methods for producing the same, and as a result, arrived at the present invention. <Industrial Application Field> The hollow fiber membrane of the present invention can be incorporated into a module in large numbers and used for diaphragm separation in ultrafiltration and microfiltration. In particular, it has excellent heat resistance and chemical resistance, so it can be used for electrodeposition coating of automobiles, home appliances, etc., recovery of valuables from chemical products, pulp, dye wastewater, reuse of water, plating, pickling, surface treatment wastewater, etc. Industrial wastewater treatment, such as recovery of metals and inorganic salts and water reuse, as well as protein, enzyme, and
Rationalization of manufacturing processes such as separation and purification of sugars, production of ultra-pure water in the electronics industry, concentration, brine removal, and clarification filtration in the food industry, as well as solvent recovery in paint, painting, and paint factories, and production of ultrapure water in the electronics industry. Chemistry/
It can demonstrate its characteristics in organic solvent processing in the chemical industry. Further, the polymer used in the present invention has polyphenylene sulfide (hereinafter abbreviated as PPS) as a main component, and PPS has unpaired electrons in the sulfur in the main chain. Using this, it can be chemically modified or used as a complex. For example, enzymes can be immobilized on microporous hollow fibers to form highly functional membranes such as those used in bioreactors as enzyme-immobilized membranes. Also, _AsF5 ,
Electron acceptors such as SbF ₅ , I ₂ , H ₂ SO ₄ , SO ₃ , Li,
When the hollow fiber membrane of the present invention is doped with an electron donor such as K, sodium naphthalene, N(C ₄ H ₉ )/CIO ₄ , etc., the effect of dramatically increasing the membrane area due to the microporous structure and the benzene ring and sulfur is present in the main chain, the electrical conductivity is improved to more than 10 ^-8 mho/cm (25℃), which can be used for the recovery of precious metals and heavy metals, electrodialysis membranes, electrolyte aqueous solutions, and electrolytes. Selective permeation membranes that separate specific substances from solutions consisting of non-electrolytes, separation of specific gases from polar and non-polar mixed gas systems, and applications that utilize changes in electrical resistance and electromotive force; for example, humidity sensors, gas Can be used for sensors, etc. Further, the hollow fiber membrane of the present invention is used as a support for a separation membrane, and the hollow fiber membrane of the present invention is immersed in a solution of a polymer such as polysulfone, taken out, dried, and the solvent removed. 1.5μ
If a composite membrane is prepared in which a dense skin layer with a thickness of m is formed on the surface of the hollow fiber of the present invention, it can be used as a reverse osmosis membrane or a gas separation membrane. Polymer solutions that can be used for these purposes include polydimethyl silicone, polydiphenyl silicone, polyladder organosiloxane, polydimethyl silicone carbonate, polycarbonate,
Cellulose acetate, polyvinyl alcohol,
It can be selected from solutions of at least one polymer selected from polysulfone, polyethersulfone, polyimide, polymethacrylate, polyarylene oxide, and protein. The fabric woven by cutting the hollow fiber membrane of the present invention into short fibers can be used as sweat-absorbing clothing, medical bandages, firefighting clothing, and work clothes for hot work sites due to its sweat-absorbing, heat-insulating properties,
You can take advantage of its heat resistance. In addition, it has a large ability to absorb and hold oil, so it can be used as an oil fence. As detailed above, the hollow fiber membrane of the present invention is
By taking advantage of its excellent heat resistance and chemical resistance, as well as the fact that its sulfur atom has an unpaired electron, it can be used in a wider range of applications in addition to its conventional application fields. Of course, the hollow fiber membrane of the present invention is not limited to the above examples. <Structure of the Invention> The first aspect of the present invention is a hollow fiber membrane made of polyphenylene sulfide resin, which has a dense layer having micropores with a pore diameter of 0.025μ or less on its inner surface, and It is a hollow fiber membrane having a spongy tissue layer in contact with this dense layer, which contains about 20% or more by volume of cavities with a diameter of 1 μ or more. The polyphenylene sulfide resin that makes up the membrane has the general formula

Refers to a polymer containing 90 mol% or more of the structural unit represented by the formula. If the copolymerization component is less than 10 mol%, the meta bond

[Formula] Ortho bond

[Formula] Ether bond

[Formula] Sulfone bond

[Formula] biphenyl join

[Formula] Substituted Feni Rensulfide bond

[Formula] Here, R represents an alkyl group, a nitro group, a phenyl group, an alkoxy group, a carboxylic acid group, or a metal base of a carboxylic acid), trifunctional bond

[Formula] can be exemplified. In particular, when trifunctional or more functional phenyl, biphenyl, naphthyl sulfide bonds, etc. are selected for copolymerization, the amount is preferably 3 mol% or less, more preferably 1 mol% or less. Furthermore, the polyphenylene sulfide resin of the present invention may be a composition partially containing other components; for example, it is possible to blend other resins within a range that does not affect moldability. Other polymers that can be blended include polyethylene terephthalate, polybutylene terephthalate, nylon-6, nylon-66, polycarbonate, polyoxymethylene, polyphenylene oxide, poly-
Examples include crystalline polymers such as 4-methylpentene-1, polypropylene, polytetrafluoroethylene, and polyetheretherketone, and amorphous polymers such as polysulfone and polyethersulfone. Further, such raw material resin may contain appropriate amounts of additives such as antioxidants, antistatic agents, antibacterial materials, lubricants, flame retardants, and surfactants, as required. The second invention of the present invention is a method for producing such a hollow fiber membrane, in which a solution containing PPS as described above is extruded from an annular nozzle, and a good solvent for PPS is added to the core of the annular nozzle. It is characterized in that a coagulable liquid consisting of a non-solvent mixture is introduced and then coagulated. As a solvent for forming the PPS solution, a good solvent described below is used, but a mixed solvent containing a portion of a non-solvent may also be used. The coagulating liquid introduced from the core of the annular nozzle coagulates the hollow fiber membrane from its inner surface, so it is called internal coagulating liquid for convenience.Coagulation involves introducing a shaped hollow body to coagulate the hollow fiber membrane from its outer surface. The baths are referred to as external coagulation liquids for convenience, and the extruded hollow fiber membranes are coagulated by these coagulation liquids. Of course, the coagulated membrane then undergoes a water washing process and the like. The present inventors found that it does not dissolve in organic solvents at room temperature.
As a result of intensive research on good solvents for PPS, we found that N-methyl-2-pyrrolidone, N,
N-dimethylformamide, N,N-dimethylacetamide, N-ethyl-2-pyrrolidone, N-
Organic amide solvents such as methyl-ε-caprolactam and hexamethylphosphoramide, as well as α
- It was discovered that aromatic solvents such as chlornaphthalene are good solvents. Particularly preferred is N-methyl-2-pyrrolidonga. These can be used alone or in combination of two or more.
The boiling point of these solvents is around 200℃ at normal pressure.
Naturally, it acts as a good solvent under pressure. In addition, suitable non-solvents include water, methanol, ethanol, etc., and polyhydric alcohols having 2 to 4 carbon atoms. Examples of polyhydric alcohols include ethylene glycol, propylene glycol, glycerin, butanediol, allyl alcohol, etc. There is. These and water can be used alone or in combination of two or more. As the non-solvent to be contained in the PPS solution serving as the spinning dope, the above-mentioned polyhydric alcohols may be used alone or in combination with water. The spinning stock solution contains PPS2-40% by weight, non-solvent 0-35%
% by weight mixed with a good solvent can be used. As the external coagulating liquid used in the coagulating bath, non-solvents for PPS such as water, methanol, ethanol, ethylene glycol, propylene glycol, glycerin, and butanediol can be used alone or in combination. As the internal coagulating liquid introduced into the hollow part of the fiber membrane, a mixed solvent of a PPS good solvent and a non-solvent is used. Among them, non-solvents with a viscosity of 0.7 to 2 cps (centipoise) (referred to as non-solvent A) and those with a viscosity of 3
~50 cps (referred to as non-solvent B) is preferably used in combination. Furthermore, such an internal coagulation liquid is treated with a non-solvent, so that its coagulation value is 12 to 18 and the viscosity is 3 to 40 cps.
It is preferable to mix three types of non-solvents A and B. The coagulation value referred to here refers to a solution of PPS dissolved in N-methyl-2-pyrrolidone to a concentration of 1% by weight.
This is the amount of coagulation solution required to turn ml cloudy, expressed in ml. (The viscosity is the value at 30°C, and the coagulation value is the value at 240°C.) By the way, regarding the coagulation value, that of non-solvent A is 4 to 4.
10, and that of non-solvent B is 15-20. <Function> The reason why a mixed solvent of three types is used in this way is that it is particularly preferable to form a sponge layer and a skin layer at the same time without making the membrane structure uniform, and to improve the permeability of gases, liquids, etc. . Furthermore, if the proportion of the good solvent is lowered, there are problems such as the spinning not being perfectly circular and the spinning speed decreasing. Non-solvent A is involved in the formation of the internal skin,
The smaller the coagulation value and viscosity, the better;
If the coagulation value is 10 or more and the viscosity is 2 cps or more, it is difficult to form an internal skin. Examples of such non-solvents include water, methanol, and ethylene glycol. Non-solvent B adjusts the coagulation value and viscosity of the internal coagulation liquid and is involved in the formation of voids. Non-solvents that correspond to this include saturated polyhydric alcohols having 2 to 4 carbon atoms, ethylene glycol, and propylene. Examples include glycol, glycerin, butanediol, and the like. The spinning of the present invention employs a dry-wet method, and normally in this method, a draft is created in the yarn section immediately after it is extruded from the nozzle, allowing high-speed spinning. However, if a highly coagulating liquid is used as the internal coagulating liquid, The extruded spinning stock solution gels and coagulates instantaneously, causing thread breakage and the like, resulting in insufficient spinning speed. When the internal coagulation liquid viscosity is 1 cps or more, preferably 3 cps or more,
Since it has the effect of delaying the gelation and coagulation portion in time, drafting is likely to occur, and therefore, an improvement in the spinning speed is observed. By doing this, the outer diameter is 30 μm to 5 mm.
A hollow fiber membrane is obtained. This membrane has a spongy tissue layer on the outside and a compact layer on the inside.The compact layer has micropores with a pore diameter of about 0.025μ or less on the inner surface, and the spongy tissue layer constitutes a sponge. The volume ratio of cavities with diameters of 1μ or more along with microporous
20% or more. It should be noted that the hollow fiber membrane of the present invention can also be obtained with a skin layer on the outer surface by appropriately changing the spinning conditions, but it goes without saying that such a membrane may also be used. <Examples> Examples of the present invention are shown below, but the present invention is not limited thereto. Example 1 Using a Koka-type flow tester, the base was 1 mmφ×
17 parts polyphenylene sulfide resin with a melt viscosity of 7900 poise measured at 10 mm L, temperature 300°C, and shear rate 200 sec ^-1 , diethylene glycol 10 parts, N
- 73 parts of methylpyrrolidone was uniformly dissolved at 250°C under pressure to obtain a spinning stock solution. The spinning dope is extruded from the sheath of the sheath-core nozzle at 235°C, and diethylene glycol 40 is extruded from the core.
57 parts of N-methylpyrrolidone, and 3 parts of water were simultaneously extruded into the air to a depth of 22 mm.
After running, it was introduced into an external coagulating solution consisting of a 60% aqueous solution of N-methylpyrrolidone, washed with water, and then wound up at a speed of 50 m/min. The obtained hollow fiber membrane has an inner diameter of 180μ, an outer diameter of 250μ, and a thickness of approx.
It has a dense layer of 0.25μ inside, and a spongy structure with a maximum pore diameter of 1.5μ is in contact with this dense layer, and
This spongy tissue contained 40% cavities with a diameter of 6μ. This hollow fiber membrane has a resistance of 60000 under a pressure of 1Kg/ ^cm2
It had a water permeability rate of /m ² ·Hr. Also, the elimination rate of 500ppm of ovalbumin (molecular weight 45000) is 2
It was 74% under a pressure of Kg/cm ² .

Claims (1)

[Claims] 1. It is made of polyphenylene sulfide resin, has a dense layer having micropores with a pore diameter of about 0.025 μm or less on the inner surface, and has cavities with a diameter of 1 μm or more in contact with this dense layer in terms of volume ratio. A hollow fiber membrane with a layer consisting of approximately 20% or more spongy tissue. 2 A solution containing polyphenylene sulfide resin is extruded from an annular nozzle, and a coagulable liquid consisting of a mixture of a good solvent and a non-solvent of polyphenylene sulfide is introduced into the core of the annular nozzle, and then solidified. A method for producing a polyphenylene sulfide hollow fiber membrane, the method comprising: 3. The method according to claim 2, wherein the polyphenylene sulfide non-solvent in the coagulable liquid is a mixture of a polyhydric alcohol having 2 to 4 carbon atoms and water.