JP2021049501A - Supporter for semipermeable membrane for membrane separation activated sludge treatment - Google Patents

Abstract

To provide a supporter for a semipermeable membrane for membrane separation activated sludge treatment which is excellent in solvent resistance, and in which adhesive strength between itself and a semipermeable membrane is high when a coating liquid for formation of the semipermeable membrane is applied thereon, and a roll is hard to get dirty when processing a thermal calendar.SOLUTION: A supporter for a semipermeable membrane for membrane separation activated sludge treatment contains drawn polyester fiber as main fiber, and contains core sheath type polyester composite fiber with a sheath part of crystalline copolymer polyester as binder fiber, and a change ΔH in enthalpy of cold crystallization peak of the core sheath type polyester composite fiber per unit mass of the supporter for semipermeable membrane by differential scanning calorimetry is 0.2 J/g or more.SELECTED DRAWING: None

Description

The present invention relates to a semipermeable membrane support for membrane separation activated sludge treatment.

Semipermeable membranes are widely used in fields such as desalination of seawater, water purifiers, food concentration, wastewater treatment, medical use represented by hemofiltration, and ultrapure water production for semiconductor cleaning. The separating functional layer of the semipermeable membrane is composed of a porous resin such as a cellulosic resin, a polysulfone resin, a polyacrylonitrile resin, a fluorine resin, or a polyester resin. However, since these porous resins alone are inferior in mechanical strength, filtration is a form of a composite in which a semipermeable membrane is provided on one side of a semipermeable membrane support made of a fiber base material such as a non-woven fabric or a woven fabric. A membrane is used. In the semipermeable membrane support, the surface on which the semipermeable membrane is provided is referred to as a "coated surface", and the surface opposite to the coated surface is referred to as a "non-coated surface".

One of the usage forms of these semipermeable membranes and filtration membranes is a membrane separation activated sludge treatment method (Membrane Bioreactor, MBR). The membrane separation activated sludge treatment method is widely used because the quality of treated water is stable and maintenance is easy when treating organic sewage. Membrane separation In the activated sludge treatment method, after removing impurities in the sewage, organic substances in the sewage are decomposed and removed by the activated sludge in the biological treatment tank (aeration tank), and the immersion type membrane separation installed in the biological treatment tank. The mixed solution is solid-liquid separated by the device, and the permeated filtered solution is discharged as treated water. The membrane separation part in such a membrane separation device is subjected to an aeration operation performed to prevent clogging and supply of oxygen to activated sludge, as well as violent collision of inorganic substances such as sand, sludge, and other solid substances during use. Since air bubbles collide violently with the film surface, it is required to have sufficient strength to withstand such an impact.

In addition, the filtration membrane is used modularized. Typical modules in a sheet-shaped filtration membrane are a flat membrane type module and a spiral type module. Typical modules in tubular filtration membranes are hollow fiber type modules and tubular / tubular type modules. The flat film type module is used by adhering and fixing a filter film to a frame material made of a resin such as polypropylene, acrylonitrile, butadiene (Butadiene), styrene (Stylene) copolymer synthetic resin (ABS resin), or the like. Generally, a heat fusion treatment, an ultrasonic fusion treatment, or the like is performed for adhesion / fixing to the frame material.

In all modules, when the film surface becomes dirty during use, a process called "backwashing" is performed to clean the film surface. In backwashing, water is passed through while pressurizing an alkaline cleaning solution or an acidic cleaning solution from the opposite direction of the normal water flow direction. Therefore, the semipermeable membrane support must have alkali resistance and acid resistance, and the interface between the semipermeable membrane support and the semipermeable membrane must have high adhesive strength in order to withstand backwashing. .. In addition, solvent resistance of the semipermeable membrane solution to a solvent is required.

Examples of a general semipermeable membrane support include a semipermeable membrane support containing olefin fibers such as polyethylene and polypropylene. For example, it is formed from a semipermeable membrane support (see, for example, Patent Document 1) obtained by heat-treating a composite fiber having polypropylene as a core material and polyethylene as a sheath material, or a moist heat-adhesive fiber such as vinyl alcohol and the olefin composite fiber. Supports for semipermeable membranes (see, for example, Patent Document 2) and the like have been proposed. These semipermeable membrane supports containing olefin fibers have weak tensile strength and insufficient pressure resistance.

Further, in the tube type / tubular type module, a tubular substrate or a mandrel is used, and the side edges are partially overlapped with each other, and the tape-shaped semipermeable membrane support is spirally wound and overlapped. Is fused by heat fusion treatment, ultrasonic fusion treatment, etc. to produce a support for a tubular semipermeable membrane, and filtration provided with a semipermeable membrane outside or inside the support for a tubular semipermeable membrane. Multiple membranes are bundled and modularized. Since the tape-shaped semipermeable membrane support is spirally wound, the coated surface of the semipermeable membrane support and the non-coated surface opposite to the coated surface are fused at the overlapped portion. Since the semipermeable membrane support containing the olefin fiber is easily fused, the adhesive strength between the coated surface and the non-coated surface of the semipermeable membrane support is excellent, and it is easy to manufacture a tubular semipermeable membrane support. However, since the portion where the semipermeable membrane supports are overlapped and fused is formed into a film, it becomes difficult for the semipermeable membrane to bite into the filmed portion, and the semipermeable membrane and the semipermeable membrane support are adhered to each other. Insufficient properties may cause the semipermeable membrane to peel off.

Another common semipermeable membrane support includes a semipermeable membrane support containing stretched polyester fibers and binder polyester fibers. For example, a semitransparent support containing stretched polyester fiber and core-sheath type polyester composite fiber (see, for example, Patent Document 3), stretched polyester fiber, unstretched polyester fiber, and sheath having a melting point of 125 ° C. or higher and 160 ° C. or lower. A semi-transparent film support (see, for example, Patent Document 4) containing the core-sheath type polyester composite fiber is proposed.

The semipermeable membrane support proposed in Patent Document 3 achieves the effect of improving the strength and formation by containing the drawn polyester fiber and the core-sheath type polyester composite fiber, but is solvent resistant. No studies have been conducted on the properties and the adhesive strength with the semipermeable membrane.

In the semipermeable membrane support of Patent Document 4, the air permeability of the non-woven fabric is specified while maintaining sufficient strength by containing a core-sheath type polyester composite fiber having a sheath portion having a melting point of 125 ° C. or higher and 160 ° C. or lower. It is possible to set the range, and the effect of suppressing the shrinkage of the width and the occurrence of wrinkles during film formation is achieved. Further, by using the undrawn polyester fiber in combination, the effect of improving the strength is achieved. However, as examined by the inventor of the present invention, a semipermeable membrane support containing a stretched polyester fiber, an unstretched polyester fiber, and a core-sheath type polyester composite fiber having a sheath portion having a melting point of 125 ° C. or higher and 160 ° C. or lower. In some cases, the solvent resistance was insufficient.

Further, by containing the stretched polyester fiber, the unstretched polyester fiber, and the core-sheath type polyester composite fiber having a copolymerized polyester having a glass transition point of 40 to 80 ° C. as a sheath, the adhesive strength and semipermeable membrane to the frame material are provided. A semipermeable membrane support for film separation active sludge treatment, which has excellent adhesive strength between a coated surface and a non-coated surface of a film support and also has excellent adhesive strength with a semipermeable membrane, is disclosed (for example, Patent Documents). See 5, 6 and 7). However, in the semipermeable membrane supports of Patent Documents 5, 6 and 7, when the coating liquid for forming the semipermeable membrane is applied on the semipermeable membrane support, the semipermeable membrane support is included. In some cases, the core-sheath type polyester composite fiber of No. 1 was eluted by the solvent of the coating liquid, and the strength of the semipermeable membrane support was lowered, or the coatability of the semipermeable membrane was lowered. Further, in the semipermeable membrane support of Patent Document 7, even if the basis weight of the semipermeable membrane support is 100 g / m ² or more, the blending ratio of the core-sheath type polyester composite fiber is high, so that the semipermeable membrane support is semipermeable. When the non-woven fabric, which is the base paper of the support for the membrane, is subjected to thermal calendar processing, the sheath portion of the core-sheath type polyester composite fiber melted may stick to the thermal roll and gradually stain the heated metal roll.

In Patent Document 8, the bulk density of the semipermeable membrane support after thermal pressure processing, which contains 10% by weight or more of polyacrylonitrile-based synthetic fibers, is 40 to 75 with respect to the weighted average density of the fibers constituting the non-woven fabric. A support for a semipermeable membrane has been proposed, which has excellent adhesive strength to the semipermeable membrane and can form a uniform semipermeable membrane. Patent Document 9 is a long-fiber non-woven fabric composed of a thermoplastic continuous filament, which includes a high-density portion formed by partial thermocompression bonding and a low-density portion not partially thermocompression-bonded. The fiber density is 0.6 to 1.0, and the fiber density of the low density portion is 0.1 to 0.5, so that the support for a semipermeable membrane having excellent properties and mechanical strength is produced. The body is proposed. However, in the semipermeable membrane supports of Patent Documents 8 and 9, as examined by the inventor of the present invention, the adhesive strength with the semipermeable membrane may be insufficient.

Japanese Unexamined Patent Publication No. 2001-17842 Japanese Unexamined Patent Publication No. 2012-250223 JP-A-2010-194478 Japanese Unexamined Patent Publication No. 2013-220382 Japanese Patent No. 60338369 Japanese Patent No. 6038370 Japanese Unexamined Patent Publication No. 2017-121606 Japanese Patent No. 4499852 Japanese Unexamined Patent Publication No. 2011-5455

The subject of the present invention is excellent solvent resistance, and when a coating liquid for forming a semipermeable membrane is applied on the semipermeable membrane support, the adhesive strength between the semipermeable membrane support and the semipermeable membrane is increased. It is an object of the present invention to provide a semipermeable membrane support for membrane separation active sludge treatment, which is expensive and does not easily stain the roll during thermal calendar processing.

As a result of diligent studies to solve the above problems, the following inventions were found.

(1) In the semipermeable membrane support for membrane separation active sludge treatment, the semipermeable membrane support contains drawn polyester fiber as a main fiber and has a crystalline copolymer polyester as a sheath portion as a binder fiber. The enthalpy change ΔH at the cold crystallization peak of the sheath portion of the core-sheath type polyester composite fiber per unit mass of the support for a semipermeable membrane by a differential scanning calorimeter (DSC) containing the core-sheath type polyester composite fiber is 0. A semipermeable membrane support for membrane separation active sludge treatment, which is characterized by having a concentration of 2 J / g or more.

(2) The semipermeable membrane support for membrane separation active sludge treatment according to (1) above, wherein the temperature of the cold crystallization peak of the sheath portion of the core-sheath type polyester composite fiber is 70 ° C. to 110 ° C.

(3) The semipermeable membrane for membrane separation active sludge treatment according to (1) or (2) above, wherein the support for semipermeable membrane for membrane separation active sludge treatment contains undrawn binder fibers as binder fibers. Support.

The semipermeable membrane support for membrane separation active sludge treatment of the present invention has excellent solvent resistance, and is a semipermeable membrane when a coating liquid for forming a semipermeable membrane is applied on the semipermeable membrane support. The adhesive strength between the support and the semipermeable membrane is high, and the effect that the roll is not easily soiled during thermal calendar processing can be achieved.

The figure which showed the cold crystallization peak shape, the peak area and ΔH when the enthalpy change ΔH at the cold crystallization peak of the sheath part of the crystalline core-sheath type polyester composite fiber per unit mass of the support for semipermeable membrane was measured. Is. The figure which showed the cold crystallization peak shape, the peak area and ΔH when the enthalpy change ΔH at the cold crystallization peak of the sheath part of the crystalline core-sheath type polyester composite fiber per unit mass of the support for semipermeable membrane was measured. Is.

In the present invention, the filtration membrane is a coating liquid (semipermeable membrane liquid) which is a raw material of the separation functional layer is applied to a coating surface which is one side of a semipermeable membrane support for membrane separation active sludge treatment and treated with water. It has the form of a composite in which a semipermeable membrane for use is formed and a semipermeable membrane is provided on one side of the support for semipermeable membrane. Examples of raw materials for the separation functional layer include vinyl chloride resin (PVC) -based, polysulfone (PS) -based, polyvinylidene fluoride (PVDF) -based, polyethylene (PE) -based, cellulose acetate (CA) -based, and polyacrylonitrile (PAN). ) -Based, polyvinyl alcohol (PVA) -based, polyimide (PI) -based and various other polymer materials are used. In particular, PVC-based and PVDF-based membranes have come to be used for semipermeable membranes for membrane separation activated sludge treatment. A coating solution, which is a solution of a polymer material as a raw material, is applied onto a semipermeable membrane support and gelled to form a microporous membrane. The process of applying and forming the separation functional layer on the semipermeable membrane support in this way is called "membrane formation".

The filtration membrane is modularized and used. A typical module in a tubular filtration membrane is a tubular / tubular module. Typical modules in a sheet-shaped filtration membrane are a flat membrane type module and a spiral type module.

In the flat film type module, the non-coated surface opposite to the coated surface of the semitransparent support is used as the frame material adhesive surface, and polypropylene, acrylonitrile, butadiene, and styrene synthetic resin (ABS) are used. It is used by adhering and fixing a filtration film to a frame material made of resin such as resin). Generally, a heat fusion treatment, an ultrasonic fusion treatment, or the like is performed for adhesion / fixing to the frame material.

The semitransparent support for film separation active sludge treatment of the present invention contains drawn polyester fiber as a main fiber and core-sheath type polyester composite fiber having a crystalline copolymer polyester as a sheath as a binder fiber. , The enthalpy change ΔH of the cold crystallization peak of the sheath portion of the crystalline core-sheath type polyester composite fiber per unit mass of the support for semitransparent film by DSC is 0.2 J / g or more. In the present specification, "core-sheath type polyester composite fiber having a crystalline copolymer polyester as a sheath portion" may be referred to as "crystalline core-sheath type polyester composite fiber".

The sheath portion of the crystalline core-sheath type polyester composite fiber according to the present invention is a crystalline copolymer polyester, and is difficult to elute even when immersed in a solvent such as methyl ethyl ketone or dimethylformamide used for a semipermeable membrane solution. Does not reduce the strength of the permeable membrane support. Further, by containing the crystalline core-sheath type polyester composite fiber, the core portion of the crystalline core-sheath type polyester composite fiber does not melt even after the production of the non-woven fabric (base paper) and the subsequent thermal calendering treatment are completed. Since the fiber shape can be maintained and voids can be secured, the semipermeable membrane penetrates into the inside of the semipermeable membrane support when the semipermeable membrane is applied. Then, it becomes possible to obtain a semipermeable membrane support having excellent adhesive strength between the semipermeable membrane support and the semipermeable membrane.

However, in the semipermeable membrane support for membrane separation active sludge treatment of the present invention, the sheath portion of the crystalline core-sheath type polyester composite fiber is cooled per unit mass of the semipermeable membrane support by a differential scanning calorimeter (DSC). The enthalpy change ΔH of the crystallization peak is 0.2 J / g or more. ΔH is more preferably 0.25 J / g or more, and further preferably 0.3 J / g or more. Further, ΔH is preferably 5 J / g or less, and more preferably 4.5 J / g or less. As a result of examination by the inventor of the present invention, in order for the semipermeable membrane support to exhibit excellent adhesive strength with the semipermeable membrane, the sheath portion is melted in the process of manufacturing the semipermeable membrane support. It has been found that the core-sheath type polyester composite fiber needs to be contained in a certain amount or more. Further, as a means for specifying the amount of the crystalline core-sheath type polyester composite fiber whose sheath is melted by the heat given at the time of manufacture, the crystalline core-sheath type polyester composite fiber per unit mass of the semipermeable membrane support by DSC is used. The enthalpy change ΔH of the cold crystallization peak of the sheath portion of the sheath is effective, and when ΔH is 0.2 J / g or more, the semipermeable membrane support exhibits good adhesion to the semipermeable membrane. I found it. The reason why the adhesive strength between the semipermeable membrane support and the semipermeable membrane is improved by melting the sheath of the crystalline core-sheath type polyester composite fiber is not clear, but the melting of the sheath causes the sheath to melt. It is considered that the anchor effect of the semipermeable membrane was improved by changing the surface structure of the crystalline core-sheath type polyester composite fiber and increasing the specific surface area. When ΔH is less than 0.2 J / g, there are few crystalline core-sheath type polyester composite fibers whose sheath is melted in the process of manufacturing the semipermeable membrane support, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane is high. descend. If ΔH exceeds 5 J / g, the amount of the crystalline core-sheath type polyester composite fiber whose sheath is melted during the thermal calendering process becomes excessive, which may stain the roll.

In the present invention, the temperature of the cold crystallization peak (cold crystallization temperature) of the sheath portion of the crystalline core-sheath type polyester composite fiber is preferably 70 to 110 ° C, more preferably 80 to 100 ° C. When the cold crystallization temperature is less than 70 ° C., the sheath portion of the crystalline core-sheath type polyester composite fiber melted when the non-woven fabric, which is the base paper of the semipermeable membrane support, is heat-calendered easily adheres to the heat roll. , May stain the gradually heated metal roll. If the cold crystallization temperature exceeds 110 ° C, the metal roll temperature during thermal calendering and the amount of heat given to the non-woven fabric may not be sufficient, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane may decrease. ..

FIG. 1 shows the shape and peak area of the cold crystallization peak and the peak area and ΔH when the enthalpy change ΔH of the cold crystallization peak of the sheath portion of the crystalline core-sheath type polyester composite fiber per unit mass of the support for the semipermeable membrane was measured. It is a figure which showed. ΔH is 1.30 J / g, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane is at a very good level so as not to peel off at the interface between the semipermeable membrane support and the semipermeable membrane. It was.

FIG. 2 shows the shape and peak area of the cold crystallization peak and the peak area and ΔH when the enthalpy change ΔH of the cold crystallization peak of the sheath portion of the crystalline core-sheath type polyester composite fiber per unit mass of the support for the semipermeable membrane was measured. It is a figure which showed. ΔH was 0.31 J / g, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane was at a usable level. In FIGS. 1 and 2, ΔH is a negative value, and this negative value indicates an exothermic peak.

In the present invention, "crystalline" means that when the temperature of the fiber is raised to the temperature of the molten state and then lowered, the temperature is slowly lowered although it is entangled with molecular motion in the molten state. It means that it has the property of partially aligning and crystallization at the crystallization temperature while the molecular motion slowly subsides by (slow cooling). Further, if the temperature of the fiber is raised to the temperature of the molten state and then the temperature is lowered rapidly (quenched), the crystalline state is reduced and the amorphous portion is increased even if the fiber has crystallinity.

In the present invention, "cold crystallization" is a phenomenon in which the molecule becomes able to move a little beyond the glass transition temperature in the process of raising the temperature of the fiber containing a large amount of amorphous portion, and the amorphous portion begins to crystallize. To say. That is, the more amorphous portions contained in the fiber, the higher ΔH. Since the amorphous portion is contained in a large amount in the fiber by raising the temperature of the fiber beyond the temperature in the molten state and then quenching, it is a crystalline core-sheath type per unit mass of the support for semitransparent film by DSC. By measuring the ΔH of the sheath portion of the polyester composite fiber, the amount of the crystalline core-sheath type polyester composite fiber whose sheath portion is melted by the heat given at the time of production can be estimated.

As a method for confirming the presence or absence of crystallinity, a differential scanning calorimeter (manufactured by PerkinElmer, device name: DSC8500) is used to raise the temperature of the semipermeable membrane support (sample amount: about 12 mg) at 10 ° C./ After raising the temperature from 0 ° C to 230 ° C in minutes, continuously cool to 0 ° C at a cooling rate of 10 ° C / min, check for the presence or absence of an exothermic peak due to crystallinity, and if an exothermic peak is observed, Judged to be crystalline.

As a method for measuring ΔH of the sheath portion of the crystalline core-sheath type polyester composite fiber per unit mass of the support for the semipermeable membrane, a differential scanning calorimeter (manufactured by Perkin Elmer Co., Ltd., device name: DSC8500) is used for crystallization. By raising the temperature of the semipermeable membrane support for membrane separation active sludge treatment (sample amount: about 12 mg) containing the core-sheath type polyester composite fiber from 0 ° C to 300 ° C at a temperature rise rate of 10 ° C / min. A cold crystallization peak can be confirmed, and it is a 5-fold average value of ΔH (J / g) obtained by dividing the cold crystallization peak area by the mass of the actually measured sample.

In the present invention, the content ratio of the main synthetic fiber to the binder fiber is preferably 50:50 to 80:20, more preferably 55:45 to 75:25, and 60:40 to 60:40 on a mass basis. It is more preferably 70:30. When the content ratio of the binder fibers is less than 20% by mass, the adhesive strength between the fibers tends to be insufficient, the surface of the semipermeable membrane support tends to fluff, and the coatability of the semipermeable membrane may be impaired. On the other hand, when the content ratio of the binder fiber exceeds 50% by mass, the surface of the semipermeable membrane support is likely to be filmed due to the melting of the binder fiber, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane is lowered. There is.

In the present invention, the copolymerized polyester of the sheath portion of the crystalline core-sheath type polyester composite fiber used as the binder fiber contains a terephthalic acid component and an ethylene glycol component, and contains an isophthalic acid component, an adipic acid component, and a sebacic acid. Examples thereof include copolymerized polyesters containing at least one component selected from the group of components, naphthalenedicarboxylic acid components, 1,4-butanediol components, tetraethylene glycol components, ε-caprolactone components and aliphatic lactone components.

In the present invention, the blending ratio of the crystalline core-sheath type polyester composite fiber is preferably 5% by mass or more, more preferably 10% by mass or more, and 15% by mass or more with respect to the total fibers. Is even more preferable. Further, it is preferably 50% by mass or less, more preferably 40% by mass or less, further preferably 30% by mass or less, particularly preferably 25% by mass or less, and 20% by mass or less. There may be. When the compounding ratio of the crystalline core-sheath type polyester composite fiber is less than 5% by mass, ΔH tends to be less than 0.2 J / g, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane may decrease. .. On the other hand, if it exceeds 50% by mass, the surface of the semipermeable membrane support tends to be filmed, the adhesive strength between the semipermeable membrane support and the semipermeable membrane tends to decrease, or ΔH tends to exceed 5 J / g. The roll may be soiled during thermal calendar processing.

In the present invention, it is preferable to contain undrawn polyester fiber as a part of the binder fiber. When the crystalline core-sheath type polyester composite fiber is used alone as a binder fiber, the sheath portion of the crystalline core-sheath type polyester composite fiber melted when the non-woven fabric which is the base paper of the semitransparent film support is subjected to thermal calendering is formed. It becomes easy to stick to the heat roll and may stain the gradually heated metal roll. In the present invention, it has been found that the combined use of undrawn polyester fiber as the binder fiber has an effect of suppressing stains on the metal roll during thermal calendering.

Examples of the unstretched polyester fiber include unstretched fibers obtained by spinning polyesters such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate and a copolymer containing the same at a spinning speed of 800 to 1,200 m / min. By heat-press fusion of these unstretched polyester fibers by thermal calendering treatment, a high-strength semipermeable membrane support can be obtained.

The blending ratio of the unstretched polyester fiber is preferably 0 to 30% by mass, more preferably 0 to 25% by mass, based on the total fiber. If it exceeds 30% by mass, the surface of the semipermeable membrane support tends to be filmed, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane may decrease.

In the present invention, the fiber diameter of the binder fiber is preferably 2 to 30 μm, more preferably 5 to 27 μm, still more preferably 7 to 25 μm. When a binder fiber having a fiber diameter of less than 2 μm is used, the strength of the semipermeable membrane support may be insufficient. On the other hand, when a binder fiber having a fiber diameter of more than 30 μm is used, the fiber dispersion during papermaking becomes poor, the texture of the semipermeable membrane support tends to be uneven, and the semipermeable membrane film-forming property is improved. It may be damaged.

In the present invention, the fiber length of the binder fiber is preferably 1 to 15 mm, more preferably 3 to 12 mm, still more preferably 3 to 10 mm. If the fiber length is less than 1 mm, the strength of the semipermeable membrane support may decrease, and if it exceeds 15 mm, the fiber dispersibility tends to decrease, and the formation of the semipermeable membrane support may decrease. It tends to be non-uniform and may impair the film-forming property of the semipermeable membrane.

The semipermeable membrane support for membrane separation activated sludge treatment of the present invention contains drawn polyester fibers as main fibers. When the non-woven fabric contains binder fibers, the step of raising the temperature to the softening point or melting temperature (melting point) or higher of the binder fibers is incorporated into the method for producing a semipermeable membrane support for membrane separation active sludge treatment. Binder fibers improve the mechanical strength of the semipermeable membrane support for membrane separation active sludge treatment. In this step of raising the temperature, the drawn polyester fiber does not soften or melt, and forms the skeleton of the semipermeable membrane support as the main fiber. Examples of the drawn polyester fiber include polyester having an alkylene terephthalate as the main repeating unit, and polyethylene terephthalate having high heat resistance is preferable. Further, the cross-sectional shape of the fiber is preferably circular. However, fibers having irregular cross sections such as T-type, Y-type, and triangular can also be contained within a range that does not impair other characteristics in order to prevent strike-through and smoothness of the coated surface.

The fiber diameter of the stretched polyester fiber is preferably 2 to 30 μm, more preferably 5 to 27 μm, still more preferably 7 to 25 μm. When a fiber having a fiber diameter of less than 2 μm is used, the strength of the semipermeable membrane support may be insufficient. On the other hand, when fibers having a fiber diameter of more than 30 μm are used, the fiber dispersion during papermaking becomes poor, the texture of the semipermeable membrane support tends to be uneven, and the film forming property of the semipermeable membrane is impaired. In some cases.

The fiber length of the drawn polyester fiber is not particularly limited, but is preferably 1 to 15 mm, more preferably 3 to 12 mm, and further preferably 3 to 10 mm. If the fiber length is less than 1 mm, the strength of the semipermeable membrane support may decrease, and if it exceeds 15 mm, the fiber dispersibility tends to decrease, and the formation of the semipermeable membrane support may decrease. It tends to be non-uniform and may impair the film-forming property of the semipermeable membrane.

In the present invention, the fiber diameter is a cross section of 50 fibers randomly selected from the fibers forming the non-woven fabric base material by scanning electron microscope observation of the cross section of the support for the semipermeable membrane for membrane separation active sludge treatment. It is the diameter of the fiber that is converted into a perfect circle by measuring the area of.

In the semipermeable membrane support for membrane separation activated sludge treatment of the present invention, fibers other than the drawn polyester fibers and binder fibers described above may be added, if necessary. Specific examples of the synthetic fiber include polyolefin-based, polyamide-based, polyacrylic-based, vinylidene, polyvinyl chloride, benzoate, polychlar, and phenol-based fibers. As natural fibers, hemp pulp, cotton linter, lint with less film; as regenerated fibers, lyocell fiber, rayon, cupra; as semi-synthetic fibers, acetate, triacetate, promix; as inorganic fibers, alumina Examples thereof include fibers, alumina / silica fibers, rock wool, glass fibers, microglass fibers, zirconia fibers, potassium titanate fibers, alumina whisker, aluminum borate whisker and the like. In addition to the above fibers, wood pulps such as softwood pulp and hardwood pulp, wood pulps such as straw pulp, bamboo pulp, and kenaf pulp and herbaceous plants can also be used as plant fibers. Further, the above fibers may be fibrillated as long as they do not impair liquid permeability and air permeability. Further, pulp fibers obtained from used paper, waste paper and the like can also be used. Further, a fiber having a modified cross section such as T-shaped, Y-shaped, or triangular cross-section can also be contained.

The basis weight of the membrane separation activated sludge process for semipermeable membrane support of the present invention is preferably from 30 to 250 g / ^{m 2,} more preferably ^{40~230g / m 2, 50~200g / m} 2 is more preferable. If it is less than 30 g / m ² , the strength of the semipermeable membrane support may be insufficient. Further, when it exceeds 250 g / m ² , the liquid passage resistance becomes high, or the thickness of the semipermeable membrane support increases, and the module is enlarged in order to store a specified amount of the semipermeable membrane. Need to be done.

The thickness of the semipermeable membrane support for membrane separation activated sludge treatment of the present invention is preferably 50 to 300 μm, more preferably 70 to 270 μm, and even more preferably 80 to 250 μm. If the thickness exceeds 300 μm, the area of the semipermeable membrane that can be incorporated into the unit becomes small, and as a result, the life of the semipermeable membrane may be shortened. On the other hand, if the thickness is less than 50 μm, sufficient strength may not be obtained.

Density of the membrane separation activated sludge treatment for semipermeable membrane support of the present invention is preferably 0.30~1.00g / cm ^3, more preferably 0.35~0.98g / cm ^3, 0 .40 to 0.95 g / cm ³ is more preferred. When the density is ^{less than 0.30 g / cm 3} , when the semipermeable membrane is provided on the semipermeable membrane support, the coating liquid permeates into the semipermeable membrane support becomes large, and the semipermeable membrane becomes semipermeable. It may impair the uniformity of the membrane. On the other hand, when the density is ^{larger than 1.00 g / cm 3} , there are few voids in the semipermeable membrane support, and the semipermeable membrane support and the semipermeable membrane are due to insufficient penetration when the semipermeable membrane solution is applied. Adhesive strength may decrease.

The nonwoven fabric related to the semipermeable membrane support for membrane separation activated sludge treatment of the present invention can be produced by a dry method or a wet papermaking method. In the present invention, a wet non-woven fabric formed by a wet papermaking method is preferable.

In the wet papermaking method, first, the main fiber and the binder fiber are uniformly dispersed in water, and then the final fiber concentration is 0.01 to 0.50% by mass through a process such as a screen (removal of foreign matter, lumps, etc.). The slurry adjusted to the above is made by a paper machine to obtain wet paper. In order to make the dispersibility of fibers uniform, chemicals such as dispersants, defoamers, hydrophilic agents, antistatic agents, polymer thickeners, mold release agents, antibacterial agents, and bactericides may be added during the process. is there.

Examples of the paper machine include a paper machine in which a paper machine such as a long net, a circular net, and an inclined wire is installed independently, a combination paper machine in which two or more types of paper machines of the same type or different types are installed online. Can be used. Further, when the semipermeable membrane support of the present invention has a multi-layer structure of two or more layers, a laminating method of laminating wet papers made by each paper machine or after forming one layer. Any method may be used in which a slurry in which fibers are dispersed on the layer is cast and laminated. When the slurry in which the fibers are dispersed is cast, the previously formed layer may be in a wet paper state or a dry state. Further, two or more layers can be heat-sealed to form a multilayer structure non-woven fabric.

In the semipermeable membrane support for membrane separation active sludge treatment of the present invention, when the non-woven fabric has a multilayer structure, it may have a multilayer structure in which the fiber composition of each layer is the same, and the semipermeable membrane for membrane separation active sludge treatment For the purpose of controlling the permeability of the liquid in the thickness direction in the support body, a multi-layer structure in which the fiber composition of each layer is different may be used. In the case of a multi-layer structure, the fiber concentration of the slurry can be lowered by lowering the basis weight of each layer, so that the texture of the non-woven fabric is improved, and as a result, the smoothness and uniformity of the coated surface are improved. Further, even if the formation of each layer is uneven, it can be compensated by laminating. Furthermore, the papermaking speed can be increased and the operability is improved.

A sheet (base paper) is obtained by drying the wet paper produced by the papermaking net with a Yankee dryer, an air dryer, a cylinder dryer, a suction drum type dryer, an infrared type dryer, or the like. When the wet paper is dried, it is brought into close contact with a heat roll such as a Yankee dryer and heat-pressure dried, so that the smoothness of the adhered surface is improved. Hot pressure drying means drying by pressing wet paper against the hot roll with a touch roll or the like. The surface temperature of the heat roll is preferably 100 to 180 ° C., more preferably 105 to 170 ° C., and even more preferably 110 to 160 ° C. The pressure is preferably 5 to 100 kN / m, more preferably 10 to 80 kN / m.

In the present invention, it is preferable that the non-woven fabric (base paper) is further subjected to a thermal calender treatment (thermal pressure processing). In the thermal calendar processing, a calendar unit having a roll structure such as a metal roll-metal roll, a metal roll-elastic (resin) roll, a metal roll-cotton roll, and a metal roll-silicon roll can be used alone or in combination. At least one metal roll of the calendar unit is heated. In the present invention, it is preferable to use a metal roll-elastic roll calendar unit because a sufficient amount of heat can be applied to the non-woven fabric and a high-strength semipermeable membrane support can be obtained.

The metal roll temperature during the thermal calendering treatment is preferably + 10 to + 100 ° C., more preferably + 20 to + 90 ° C. with respect to the melting point of the sheath portion of the crystalline core-sheath type polyester composite fiber. When the temperature of the metal roll is less than + 10 ° C with respect to the melting point of the sheath of the crystalline core-sheath type polyester composite fiber, the strength of the semipermeable membrane support cannot be sufficiently obtained, or the semipermeable membrane by DSC is used. The ΔH of the sheath portion of the crystalline core-sheath type polyester composite fiber per unit mass of the support for use may be less than 0.2 J / g, and the adhesive strength between the support for semipermeable membrane and the semipermeable membrane is lowered. In some cases. If the temperature of the metal roll exceeds + 100 ° C. with respect to the melting point of the sheath portion of the crystalline core-sheath type polyester composite fiber, the metal roll may be easily soiled.

The nip pressure of the nip during the thermal calendering process is preferably 19 to 180 kN / m, more preferably 39 to 150 kN / m. If it is less than 19 kN / m, the strength of the semipermeable membrane support may decrease, or the amount of the semipermeable membrane liquid that strikes through the non-coated surface may increase, resulting in a decrease in membrane performance. If it exceeds 180 kN / m, the surface of the semipermeable membrane support tends to be filmed, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane may decrease. The processing speed is preferably 5 to 150 m / min, more preferably 10 to 80 m / min. If it is less than 5 m / min, the surface of the semipermeable membrane support tends to be filmed, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane may decrease. If it exceeds 150 m / min, the amount of semipermeable membrane liquid that strikes through the non-coated surface increases and the membrane performance deteriorates, or if the semipermeable membrane support by DSC is a crystalline core-sheath type per unit mass. The ΔH of the sheath portion of the polyester composite fiber may be less than 0.2 J / g, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane may decrease.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the present examples. Unless otherwise specified, all parts and percentages in the examples are based on mass.

≪Main fiber≫
<Stretched PET fiber 1>
A stretched polyester fiber having a fiber diameter of 10 μm and a fiber length of 5 mm made of polyethylene terephthalate was designated as stretched PET fiber 1.

≪Binder fiber≫
<Core sheath PET fiber 1>
Crystalline with a fiber diameter of 15 μm and a fiber length of 5 mm, with a crystalline copolymer polyester having a core of polyethylene terephthalate (melting point: 260 ° C.), a melting point of 220 ° C., and a cold crystallization temperature of 115 ° C. as a sheath. The core-sheath type polyester composite fiber was designated as core-sheath PET fiber 1.

<Core sheath PET fiber 2>
Crystalline with a fiber diameter of 15 μm and a fiber length of 5 mm, with a crystalline copolymer polyester having a core of polyethylene terephthalate (melting point: 260 ° C.), a melting point of 180 ° C., and a cold crystallization temperature of 98 ° C. as a sheath. The core-sheath type polyester composite fiber was designated as core-sheath PET fiber 2.

<Core sheath PET fiber 3>
Crystalline with a fiber diameter of 15 μm and a fiber length of 5 mm, with a crystalline copolymer polyester having a core of polyethylene terephthalate (melting point: 260 ° C.), a melting point of 159 ° C., and a cold crystallization temperature of 84 ° C. as a sheath. The core-sheath type polyester composite fiber was designated as core-sheath PET fiber 3.

<Core sheath PET fiber 4>
Crystalline with a fiber diameter of 15 μm and a fiber length of 5 mm, with a crystalline copolymer polyester having a core of polyethylene terephthalate (melting point: 260 ° C.), a melting point of 153 ° C., and a cold crystallization temperature of 89 ° C. as a sheath. The core-sheath type polyester composite fiber was designated as core-sheath PET fiber 4.

<Core sheath PET fiber 5>
Crystalline with a fiber diameter of 15 μm and a fiber length of 5 mm, with a crystalline copolymer polyester having a core of polyethylene terephthalate (melting point: 260 ° C.), a melting point of 137 ° C., and a cold crystallization temperature of 67 ° C. as a sheath. The core-sheath type polyester composite fiber was designated as core-sheath PET fiber 5.

<Core sheath PET fiber 6>
A core-sheath polyester composite fiber having a fiber diameter of 15 μm and a fiber length of 5 mm, which has an amorphous copolymer polyester having a core portion of polyethylene terephthalate (melting point: 260 ° C.) and a softening temperature of 75 ° C. as a sheath portion. The core sheath PET fiber 6 was used.

<Core sheath PET fiber 7>
A core-sheath polyester composite fiber having a fiber diameter of 13 μm and a fiber length of 5 mm, which has a core of polyethylene terephthalate (melting point: 260 ° C.) and a core of polyethylene (PE) having a melting point of 130 ° C., is used as a core-sheath PET fiber. It was set to 7.

<Unstretched PET fiber 1>
An undrawn polyester fiber (melting point: 260 ° C.) having a fiber diameter of 11 μm and a fiber length of 5 mm made of polyethylene terephthalate was designated as undrawn PET fiber 1.

The semipermeable membrane supports for membrane separation activated sludge treatment of Examples 1 to 12 and Comparative Examples 1 to 6 were produced under the following conditions.

(Manufacturing of base paper 1)
After pouring ^{water into a 2 m 3} dispersion tank, mix at the raw material mixing ratio (%) shown in Table 1, disperse at a dispersion concentration of 0.2% by mass for 5 minutes, and use a tilt / circular net composite paper machine. A second surface layer wet paper is formed on the inclined wire, a first surface layer wet paper is formed on the circular mesh wire, and both wet papers are laminated before being dried, and then the surface temperature is 130 ° C. It was hot-pressure dried with a Yankee dryer to obtain wet non-woven fabrics (base paper) of Examples 1 to 10 and Comparative Examples 1 to 6 having a width of 1000 mm with the target basis weight shown in Table 1.

(Manufacturing of base paper 2)
After pouring ^{water into a 2 m 3} dispersion tank, mix at the raw material mixing ratio (%) shown in Table 1, disperse at a dispersion concentration of 0.2% by mass for 5 minutes, and use a circular net paper machine to make a wet papermaking method. Was made and dried by hot pressure with a Yankee dryer set at 130 ° C. to obtain a wet non-woven fabric (base paper) of Example 11 having a width of 1000 mm with the target basis weight shown in Table 1.

(Manufacturing of base paper 3)
After pouring ^{water into a 2 m 3} dispersion tank, mix at the raw material mixing ratio (%) shown in Table 1, disperse at a dispersion concentration of 0.2% by mass for 5 minutes, and use a tilted wire paper machine to make a wet papermaking method. Was made and dried by hot pressure with a Yankee dryer set at 130 ° C. to obtain a wet non-woven fabric (base paper) of Example 12 having a width of 1000 mm with the target basis weight shown in Table 1.

(Thermal calendar processing 1)
The obtained base papers of Examples 1 to 9 and Comparative Examples 1 to 6 were subjected to a thermal calender treatment under the conditions shown in Table 2, and the membrane separation activated sludge treatment of Examples 1 to 9 and Comparative Examples 1 to 6 was performed. A support for a semipermeable membrane was obtained. In the first treatment, the surface of the inclined layer hits the metal roll (JR), and in the second treatment, the surface of the circular net layer hits the metal roll. The inclined layer is the coated surface layer, and the circular net layer is the non-coated surface. Layered.

(Thermal calendar processing 2)
The obtained base paper of Example 10 was subjected to a thermal calender treatment under the conditions shown in Table 2 to obtain a semipermeable membrane support for membrane separation activated sludge treatment of Example 10. In the first treatment, the surface of the circular net layer hits the metal roll, and in the second treatment, the surface of the inclined layer hits the metal roll. ..

(Thermal calendar processing 3)
The obtained base paper of Example 11 was subjected to a thermal calender treatment under the conditions shown in Table 2 to obtain a semipermeable membrane support for membrane separation activated sludge treatment of Example 11. In the first treatment, the surface of the wire surface hits the metal roll, and in the second treatment, the surface of the felt surface hits the metal roll. The wire surface was designated as the coated surface layer and the felt surface was designated as the non-coated surface layer.

(Thermal calendar processing 4)
The obtained base paper of Example 12 was subjected to a thermal calender treatment under the conditions shown in Table 2 to obtain a semipermeable membrane support for membrane separation activated sludge treatment of Example 12. In the first treatment, the felt surface surface hit the metal roll, and in the second treatment, the wire surface surface hit the metal roll. The felt surface was designated as a coated surface layer, and the wire surface was designated as a non-coated surface layer.

The semipermeable membrane supports obtained in Examples and Comparative Examples were measured and evaluated as follows, and the results are shown in Table 3.

Measurement 1 (density)
Density was measured according to JIS P8118: 2014 "Paper and Paperboard-Thickness and Density Test Method". The unit is g / cm ³ .

Measurement 2 (Measurement of ΔH)
A semipermeable membrane support (sample mass: about 12 mg) is set in a differential scanning calorimeter (PerkinElmer, device name: DSC8500), and the temperature rises from 0 ° C to 300 ° C at a heating rate of 10 ° C / min. The enthalpy change ΔH (J / g) of the cold crystallization peak of the sheath portion of the crystalline core-sheath type polyester composite fiber when warmed was calculated. ΔH is a 5-fold average value obtained by dividing the cold crystallization peak area by the measured value of the mass of the sample.

Evaluation 1 (Metal roll stains during thermal calendar processing)
In the thermal calendering process of the semipermeable membrane support, the state of dirt on the metal roll was evaluated by the following indexes. Practically, the usable level is "B" or higher.

A: No dirt is found on the metal roll.
B: There is a slight transfer stain on the surface of the metal roll, but long-run operation can be performed without any manufacturing problems.
C: Long-run operation is not possible due to severe transfer stains on the surface of the metal roll and sticking of the semipermeable membrane support to the metal roll.

Evaluation 2 (Solvent resistance of semipermeable membrane support)
The semipermeable membrane support is immersed in N-methyl-2-pyrrolidone (solvent, manufactured by Genuine Chemical Co., Ltd., special grade) for 10 seconds, washed with pure water, and in an atmosphere of 23 ° C. and 50% relative humidity. The support was dried for 24 hours and treated with a solvent to prepare a semipermeable membrane support. Desktop material testing machine (trade name: STA-1150, Orientec Co., Ltd.) for the MD direction (longitudinal direction, flow direction) and CD direction (horizontal direction, width direction) of the semipermeable membrane support before and after solvent treatment. The maximum load when the upper chuck is pulled up until the semipermeable membrane support breaks under the conditions of a grip interval of 100 mm and a tensile speed of 100 mm / min, and the maximum load in each of the MD and CD directions is measured. The total of the above was taken as the strength of the support for the semipermeable membrane, and the solvent resistance was evaluated by the following indexes.

(Strength of semipermeable membrane support after solvent treatment / Strength of semipermeable membrane support before solvent treatment) x 100

A: 80% or more.
B: Less than 80%, 70% or more.
C: Less than 70%.

Evaluation 3 (Adhesive strength between semipermeable membrane support and semipermeable membrane (membrane adhesive strength))

(1) Preparation of Semipermeable Membrane Solution Polyvinylidene fluoride (trade name: SOLEF (registered trademark) 6010/0001, manufactured by Solvay) to N-methyl-2-pyrrolidone (manufactured by Junsei Chemical Co., Ltd., special grade) at 80 ° C. After dissolving to a concentration of 16% while heating with, a semipermeable membrane solution was prepared by stirring at a temperature setting of 25 ° C. for half a day.

(2) Preparation of filtration membrane A mount is set on a constant-speed coating device (trade name: Automatic Film Applicator, manufactured by Yasuda Seiki Co., Ltd.), and the coating width is 100 mm x coating length is 180 mm on the set mount. The semipermeable membrane support cut in this way was fastened with OPP tape (manufactured by 3M, trade name: BK-24N) with the coated surface facing up. Using a baker-type applicator (manufactured by Yasuda Seiki Co., Ltd., coating width 100 mm) that can adjust 5 to 6 g of the semipermeable membrane liquid to a constant clearance, the coating amount (dry mass) is 28 ± 3 g / m ² . The coating was applied at a coating speed of 250 mm / sec, and 15 seconds after the start of coating, the coating was immersed in tap water at 20 ° C. to solidify. After washing with water for 3 hours, it was dried to prepare a filtration membrane.

(3) Measurement of peeling strength between the semipermeable membrane support and the semipermeable membrane One day after preparation of the filtration membrane, the sample is cut into a width of 25 mm (cross direction with respect to the coating direction) x a length of 100 mm (coating direction). Double-sided tape (manufactured by Nichiban Co., Ltd., trade name: Nystack (registered trademark) NW-25) cut to a width of 25 mm and a length of 100 mm is attached to the coated surface of the cut semipermeable membrane support on the entire coated surface. At the interface between the permeable membrane support and the semipermeable membrane to which the tape is attached, only 30 mm in length is peeled off, and the remaining 70 mm in length is left unpeeled as a sample (at this time, the release paper of the double-sided tape is not peeled off. Leave it in).

Double-sided tape (including release paper) with a semipermeable membrane support and a semipermeable membrane attached to the peeled part of the sample using a desktop material tester (trade name: STA-1150, manufactured by Orientec). Are fixed to the chucks, and under the conditions of a grip length of 25 mm and a tensile speed of 100 mm / min, the load when the part that has not yet been peeled off is continuously measured while moving by 60 mm, and the average load during that period is measured. The two-time average value was evaluated as the adhesive strength between the semipermeable membrane support and the semipermeable membrane. The adhesive strength is in units of N / 25 mm, and the "adhesive strength between the semipermeable membrane support and the semipermeable membrane" was evaluated according to the following evaluation criteria.

A: In both cases, the tape did not peel off except at the interface between the semipermeable membrane and the semipermeable membrane support, and the double-sided tape or the semipermeable membrane support was damaged. Very good level.
B: Only once out of two times does not peel off except at the interface between the semipermeable membrane and the semipermeable membrane support, the double-sided tape or the semipermeable membrane support is damaged, and the semipermeable membrane and the semipermeable membrane support The adhesive strength of the sample peeled off at other than the interface with was 9N / 25 mm or more. Good level.
C: Both times, the sample was peeled off at the interface between the semipermeable membrane and the semipermeable membrane support, and the average value of the adhesive strength of the peeled sample was 6 N / 25 mm or more. Available level.
D: Both times, the sample was peeled off at the interface between the semipermeable membrane and the semipermeable membrane support, and the average value of the adhesive strength of the peeled sample was 4N / 25 mm or more and less than 6N / 25 mm. Available level.
E: Both times, the sample was peeled off at the interface between the semipermeable membrane and the semipermeable membrane support, and the average value of the adhesive strength of the peeled sample was less than 4N / 25 mm. Practical level.

As shown in Table 3, the semipermeable membrane supports for film separation active sludge treatment of Examples 1 to 12 contain drawn polyester fibers as main fibers and crystalline copolymer polyester as a binder fiber as a sheath. It contains core-sheath type polyester composite fiber, and the ΔH of the sheath of the crystalline core-sheath type polyester composite fiber per unit mass of the support for semipermeable membrane by the differential scanning calorimeter is 0.2 J / g or more. Therefore, the solvent resistance was excellent, and the adhesive strength between the semipermeable membrane support and the semipermeable membrane was high.

From the comparison of Examples 1 to 12 and Comparative Examples 2 to 4, of Examples 1 to 12 in which ΔH of the sheath portion of the core-sheath type polyester composite fiber per unit mass of the support for semipermeable membrane is 0.2 J / g or more. The semipermeable membrane support had a higher adhesive strength with the semipermeable membrane than the semipermeable membrane supports of Comparative Examples 2 to 4 having ΔH of less than 0.2 J / g. Further, in Comparative Example 1, Comparative Example 5 and Comparative Example 6 in which the crystalline core-sheath type polyester composite fiber was not included, the adhesive strength between the semipermeable membrane support and the semipermeable membrane was insufficient.

From the comparison of Examples 1, 3 and 4, the semipermeable membrane of Examples 1 and 3 in which the temperature of the cold crystallization peak (cold crystallization temperature) of the sheath portion of the crystalline core-sheath type polyester composite fiber is 70 ° C. or higher. The metal roll of the support was less likely to be soiled than the semipermeable membrane support of Example 4 in which the cold crystallization temperature was less than 70 ° C. Further, from the comparison of Examples 5 and 6, the semipermeable membrane support of Example 6 having the cold crystallization temperature of 110 ° C. or lower is half of Example 5 having the cold crystallization temperature of more than 110 ° C. The adhesive strength between the semipermeable membrane support and the semipermeable membrane was superior to that of the semipermeable membrane support.

From the comparison between Example 2 and Example 6, the semipermeable membrane support of Example 2 in which the crystalline core-sheath polyester composite fiber and the undrawn binder fiber are used in combination as the binder fiber is crystallized as the binder fiber. The metal roll was less likely to be soiled than the semipermeable membrane support of Example 6 in which only the core-sheath type polyester composite fiber was used.

The present invention can be used in fields such as desalination of seawater, water purifiers, food concentration, wastewater treatment, medical use represented by hemofiltration, and ultrapure water production for semiconductor cleaning.

Claims (3)

In the semipermeable membrane support for membrane separation active sludge treatment, the semipermeable membrane support contains a drawn polyester fiber as a main fiber and a core sheath type having a crystalline copolymer polyester as a sheath portion as a binder fiber. It contains polyester composite fiber, and the enthalpy change ΔH at the cold crystallization peak of the sheath of the core-sheath type polyester composite fiber per unit mass of the support for semipermeable membrane by the differential scanning calorimeter is 0.2 J / g or more. A semipermeable membrane support for membrane separation active sludge treatment. The semipermeable membrane support for membrane separation active sludge treatment according to claim 1, wherein the temperature of the cold crystallization peak temperature of the sheath portion of the core-sheath type polyester composite fiber is 70 ° C. to 110 ° C. The semipermeable membrane support for membrane separation active sludge treatment according to claim 1 or 2, wherein the semipermeable membrane support for membrane separation active sludge treatment contains undrawn binder fibers as binder fibers.

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