JP5737319B2 - Method for producing spun yarn reinforced porous hollow fiber membrane - Google Patents

Description

  The present invention relates to a method for producing a spun yarn-reinforced porous hollow fiber membrane. More specifically, the present invention relates to a method for producing a spun yarn reinforced porous hollow fiber membrane excellent in mechanical strength.

  Porous hollow fiber membranes are used in various fields such as water purification treatment by membrane filtration, wastewater treatment, dehumidification or humidification.

Water purification and wastewater treatment using membrane filtration has been widely used in the water treatment field in recent years because it is easier to maintain and manage operation and has better quality compared to conventional filtration methods for coagulation and precipitation. It has been. For example, as a membrane used for membrane separation treatment of the membrane reactor method [MBR] combining activated sludge treatment and membrane separation treatment, high strength, durability and chemical resistance are required. the listed polyvinylidene fluoride prepared by thermally induced phase separation method [PVDF] membrane is often used.

However, the PVDF membrane prepared by the thermally induced phase separation method has a strength of about 8 to 22 MPa, and among them, many are about 11 MPa in practical use, although some strength is shown, Compared with a membrane prepared by a non-solvent induced phase separation method, it does not necessarily have sufficient strength. In addition, the thermally induced phase separation method has a complicated process and requires cleaning with a large number of solvents, so that it is difficult to say that it is expensive and environmentally friendly.

On the other hand, the non-solvent induced phase separation method Polysulfone and PVDF or the like which is prepared using a membrane module (membrane area of about 10 to 100 m ²⁾ of the fixed structure with an adhesive in the resin case to wastewater treatment and water purification Many are used. Such a membrane module is supplied with water in an amount of several tens of liters to several hundreds of liters per minute. At that time, since the chemical cleaning or the peristaltic cleaning for the purpose of recovering the flow rate is periodically performed, the hollow fiber membrane may be broken at the time of use or cleaning.

Moreover, the method of dehumidifying or humidifying by the hollow fiber membrane system has many advantages such as not requiring maintenance and not requiring a power source for driving. As such a dehumidifying film or humidifying film, a film-forming resin material such as polyimide, polysulfone, or polyphenylsulfone is used ( for example, Patent Document 3 ). Although dehumidifying membranes using these materials are used in many industrial fields, they are porous, so the absolute strength of the membrane is weak. There is a possibility that the hollow fiber membrane is broken. On the other hand, in recent years, humidification membranes are often used to humidify diaphragms of fuel cell stacks, but in this case as well, for example, a large amount of air of about 4000 NL / min flows in in-vehicle applications. Therefore, there is a risk of the hollow fiber membrane being cut.

A porous membrane in which spun yarn as a reinforcing material is embedded in the membrane has been proposed as means for preventing the hollow fiber membrane from being broken and improving the mechanical strength (Patent Document 4). ). Here, as a method for embedding the spun yarn in the hollow fiber membrane, a method for producing a porous hollow fiber membrane by a production method using a known double annular nozzle by mixing a reinforcing material in the spinning dope can be considered. . However, the air contained within the reinforcement of the spun yarn, etc. in such a way is gradually accumulated in the spinning dope inside the nozzle, as a result of involving the bubbles during spinning, the deformation of the film shape as shown in later comparative example occurrence of and pinholes, there is a fear such turn cutting the film occurs.

Japanese Patent No. 5,062,798 JP 2008-105016 A Japanese Patent Application Laid-Open No. 2004-290751 JP 2002-166141 A

  An object of the present invention is a porous hollow fiber membrane in which all or a part of the spun yarn is embedded in the membrane, and improves the mechanical strength without impairing the original function of the porous hollow fiber membrane. An object of the present invention is to provide a method for producing a spun yarn-reinforced porous hollow fiber membrane with a reduced defect rate.

The object of the present invention is to discharge the core liquid from the inner nozzle of the double annular nozzle and the spinning stock solution from the outer nozzle, respectively, and perform spinning inside the outer nozzle that discharges the spinning stock solution when performing wet spinning or dry-wet spinning. This is achieved by a method for producing a spun yarn-reinforced porous hollow fiber membrane by simultaneously supplying yarn from a spun yarn introduction pipe.

According to the method of the present invention, since a spun yarn reinforced porous hollow fiber membrane is produced by simultaneously supplying spun yarn to a spinning dope using a spun yarn pipe, the spun yarn which is an aggregate of short fibers, That is, the air contained between the fibers is discharged outside through the spun yarn introduction pipe, so that it is not caught in the spinning dope, and as a result, the spinning failure caused by the air in the spun yarn or There exists an effect of avoiding the defect of the obtained hollow fiber membrane.

1 is a schematic half-cut sectional view showing an example of a double annular nozzle used in a method for producing a spun yarn-reinforced porous hollow fiber membrane according to the present invention.

Production of spun yarn reinforced porous hollow fiber membrane, spun core liquid from the inside nozzle of the double annular nozzle, also Upon each ejecting spinning solution from the outer nozzle, the spun yarn inside outer nozzle for discharging the spinning dope It is performed by supplying simultaneously from the yarn introduction pipe.

As the double annular nozzle, a known one that has been used conventionally, that is, an inner nozzle and an outer nozzle having a diameter corresponding to a desired hollow fiber membrane size are arranged so as to be double. It can be used without particular limitation. In the present invention, preferably as illustrated in Figure 1, a spinning dope inlet 6, the inner nozzle 2, the double annular nozzle 1 in which the hollow fiber membrane-like material discharge opening 7 is formed of an annular body 3 is provided with It is done. In this nozzle embodiment, annular body 3 having a hollow fiber membrane-like material discharge opening 7 constitutes the outer nozzle of the double annular nozzle 1, and the tip portion of the hollow fiber membrane-like material discharge opening 7 and the inner nozzle 2 Are arranged so as to form a double tubular shape capable of forming a hollow fiber membrane having a desired film thickness.

Inside the outer nozzle (circular body) 3 are disposed in a state in which the spun yarn introduction pipe 4 for introducing the spun yarn 9 in the spinning solution is passed through the side portion of the outer nozzle 3. The spun yarn introduction pipe 4 penetrates the side surface of the outer nozzle 3 so that one end located outside the outer nozzle 3 is located above the upper portion of the outer nozzle 3 and the other end is located inside the outer nozzle 3. Provided. This is because if the one end of the spun yarn introduction pipe 4 located outside the outer nozzle 3 is positioned below the level of the spinning solution in the outer nozzle, the spinning dope is fed from the spun yarn introduction port of the spun yarn introduction pipe 4. This is because it will overflow.

  As the spun yarn introduction pipe 4, one having an inner diameter of 1.5 to 2.0 times, preferably 1.6 to 1.8 times the outer diameter (thickness) of the spun yarn is used. Since the spinning dope is pressurized in the outer nozzle (annular body 3 in FIG. 1), if the inner diameter of the spun yarn introduction pipe 4 is smaller than this, the air discharged from the spun yarn is not properly discharged, and bubbles are generated in the nozzle. If the inner diameter of the spun yarn introduction pipe 4 is larger than this, the spinning dope will flow backward through the spun yarn introduction pipe and will be outside as a result. It may leak out of the nozzle. The length of the spun yarn introduction pipe 4 is not particularly limited because the position where the spinning stock solution stays varies depending on the thickness of the spun yarn, the diameter of the spun yarn introduction pipe, and the viscosity of the spinning stock solution, but generally the outer diameter of the spun yarn ( The thickness is about 200 to 250 times, preferably about 220 to 230 times.

Using the double annular nozzle having the above-described configuration, the inner nozzle 2 is filled with the core liquid supplied from the core liquid inlet 5 and the outer nozzle 3 is filled with the spinning raw liquid and pressurized, and the spun yarn is fed from the spun yarn introduction pipe 4. A porous hollow fiber membrane in which all or part of the spun yarn is buried can be obtained by a wet spinning method or a dry-wet spinning method by simultaneously discharging the spinning stock solution while supplying it to the inside of the outer nozzle 3. In FIG. 1, only one spun yarn introduction pipe 4 is used. However, a plurality of spun yarn introduction pipes 4 can be used. Generally, 1 to 8 spun yarn introduction pipes 4 are provided. manner as to equip the double annular nozzle disposed circumferentially above the like are also included.

The spun yarn can be used without particular limitation as long as it is a commonly used spun yarn, and preferably spun yarn such as polyethylene terephthalate and polyphenylene sulfide is used, and specifically the outer diameter thereof is 0.1 to Those having a thickness of 0.5 mm, preferably 0.25 to 0.35 mm are used.

The spinning dope contains a material for producing a hollow fiber membrane and a solvent. As a manufacturing material of the hollow fiber membrane, any of known hollow fiber membrane-forming materials (polymers) can be used, for example, cellulose-based materials such as cellulose acetate, cellulose propionate, cellulose butyrate, regenerated cellulose, or a mixture thereof, Examples thereof include hydrophobic polymers such as polysulfone resins, polyethersulfone resins, polyvinylidene fluoride resins, polyacrylonitrile resins, polyetherimide resins, aramid resins , polypropylene resins, and polyethylene resins. As a soluble solvent for the film-forming resin, an aprotic polar solvent such as alcohol, dimethylformamide, diethylformamide, dimethylacetamide, diethylacetamide, dimethylsulfoxide, N-methyl-2-pyrrolidone is preferably used. As the core liquid, water or a non-solvent of a film-forming resin is used.

Spun yarn 9, from the viewpoint to bury all or part of the spun yarn across the hollow fiber membranes entire length, and preferably pre-out of the hollow fiber membrane material discharge port prior to eject the core liquid and the spinning solution to the nozzle outside deep. Further, the core solution and the spinning dope are preferably used after evacuation from the viewpoint of preventing the mixing of unnecessary air.

  The spun yarn preferably has 50% by volume or more of the cross section of the spun yarn, more preferably 60% by volume or more, and particularly preferably 70% by volume or more embedded in the hollow fiber membrane. By disposing at a position that does not exceed 90% of the hollow fiber membrane thickness when viewed from the hollow fiber membrane surface on the non-side, the mechanical properties can be further improved while keeping the permeation performance and separation performance high.

Yarn reinforced porous hollow fiber membrane, wet spinning or coagulation spun yarn reinforced porous hollow fiber membrane-like material is spun by a dry-wet spinning method using a coagulating liquid, washing is manufactured by performing a drying .

  Next, the present invention will be described with reference to examples.

Example Using the double annular nozzle 1 shown in FIG. 1 (outer nozzle inner diameter 1.15 mm, inner nozzle outer diameter 0.6 mm, inner diameter 0.4 mm), the spun yarn (outer diameter: 0.2 mm) was spun from the spun yarn inlet 8. A polyethylene terephthalate spun yarn as the spun yarn 9 is passed through the inside of the yarn introduction pipe (tube inner diameter: 1.67 times the spun yarn outer diameter, tube length: 225 times the spun yarn outer diameter) through the gap between the outer nozzle 3 and the inner nozzle 2. in a state of out beforehand about 1 m, the water as a core solution from the inside nozzle 2, also respectively ejected by pressurizing the spinning solution from the outer nozzle 3, which was coagulated in a water temperature 50 ° C. water (coagulating liquid) As a result, a spun yarn-reinforced hollow fiber membrane was obtained. Here, as the spinning dope, a solution comprising 20% by weight of polyetherimide and 80% by weight of dimethylacetamide was used, and the spinning dope and water (core solution) were each evacuated with a vacuum pump for 12 hours to remove bubbles. It was prepared and used in a free state. In this spinning process, the hollow fiber was not broken during spinning, and the defect rate due to cutting was 0%. In addition, when the double annular nozzle 1 after spinning was disassembled and observed, no bubbles were observed in the spinning dope.

The obtained spun yarn reinforced hollow fiber membrane was washed in a washing tank having a water temperature of 45 ° C. and then subjected to high-pressure sterilization treatment for 121 hours at 121 ° C. And dried for 12 hours or more to obtain a spun yarn reinforced porous polyetherimide hollow fiber membrane by a wet spinning method. When a pinhole inspection and a cross-sectional dimension inspection were performed on the porous hollow fiber membrane, no pinhole or deformation occurred in any of the hollow fiber membranes, and the defect rate was 0%. The obtained porous polyetherimide hollow fiber membrane has an outer diameter of 1000 μm, an inner diameter of 700 μm, a water vapor transmission rate at 25 ° C. of 0.36 g / cm ² / min / MPa, and a pure water transmission rate of 0 g / cm ² / hour. / MPa, the air permeation rate was 0 ml / cm ² / min / MPa. Further, a tensile test was conducted at a distance between marked lines of 50 mm and a test speed of 20 mm per minute, and the breaking stress was calculated to be 27 MPa.

Comparative Example In the embodiment, the spun yarn is introduced into the nozzle not from the spun yarn introduction port 8 but from the spinning dope introduction port 6, and the polyethylene terephthalate spun yarn which is the spun yarn 9 is previously introduced from the gap between the outer nozzle 3 and the inner nozzle 2. A hollow fiber membrane- like product was obtained with about 1 m protruding. In such a spinning process, one film break and two pinholes (core liquid blows out to the outside of the film) occurred for one spinning. Also, as a result of disassembling and observing the double annular nozzle after spinning, it was found that a large number of bubbles were found in the spinning dope, and defects were caused by these bubbles.

1 Double annular nozzle 2 Inner nozzle 3 Outer nozzle (annular body)
4 Spinning yarn introduction pipe 5 Core fluid introduction port 6 Spinning stock solution introduction port 7 Hollow fiber membrane- like material outlet 8 Spinning yarn introduction port 9 Spinning yarn

Claims (6)

The core liquid from the inside nozzle of the double annular nozzle, also ejected respectively spinning solution from the outer nozzle, when wet spinning or dry-wet spinning, from the spun yarn introducing pipe spun yarn inside outer nozzle for discharging the spinning dope A method for producing a spun yarn-reinforced porous hollow fiber membrane, characterized by being supplied simultaneously . The method for producing a spun yarn-reinforced porous hollow fiber membrane according to claim 1 , wherein a spun yarn introduction pipe having an inner diameter of 1.5 to 2.0 times the outer diameter of the spun yarn is used . The method for producing a spun yarn-reinforced porous hollow fiber membrane according to claim 1 , wherein a spun yarn introduction pipe having a length 200 to 250 times the outer diameter of the spun yarn is used . The method for producing a spun yarn-reinforced porous hollow fiber membrane according to claim 1, wherein the core solution and the spinning dope are evacuated . 2. The method for producing a spun yarn-reinforced porous hollow fiber membrane according to claim 1, wherein the spun yarn is discharged in advance from the hollow fiber membrane discharge port to the outside of the nozzle, and the core solution and the spinning stock solution are discharged . A spun yarn introduction pipe is equipped on a double annular nozzle composed of an outer nozzle and an inner nozzle, one end located outside the outer nozzle of the spun yarn introduction pipe is located above the upper part of the outer nozzle, and the spun yarn introduction The spun yarn-reinforced porous hollow according to any one of claims 1 to 5, wherein the spun yarn introduction pipe is provided through the side surface of the outer nozzle so that the other end of the pipe is positioned inside the outer nozzle. A double annular nozzle used in a method for producing a yarn membrane.

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