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WO2018021545A1 - Membrane de séparation et son procédé de fabrication - Google Patents

Membrane de séparation et son procédé de fabrication Download PDF

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Publication number
WO2018021545A1
WO2018021545A1 PCT/JP2017/027491 JP2017027491W WO2018021545A1 WO 2018021545 A1 WO2018021545 A1 WO 2018021545A1 JP 2017027491 W JP2017027491 W JP 2017027491W WO 2018021545 A1 WO2018021545 A1 WO 2018021545A1
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Prior art keywords
separation membrane
membrane
weight
porosity
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PCT/JP2017/027491
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English (en)
Japanese (ja)
Inventor
皓一 高田
山村　剛平
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Toray Industries Inc
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Toray Industries Inc
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Priority to JP2017541122A priority Critical patent/JPWO2018021545A1/ja
Publication of WO2018021545A1 publication Critical patent/WO2018021545A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/48—Polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/08—Hollow fibre membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/08—Polysaccharides
    • B01D71/12—Cellulose derivatives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/56—Polyamides, e.g. polyester-amides
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out

Definitions

  • the present invention relates to a separation membrane mainly composed of a hydrophilic polymer and a method for producing the same.
  • Separation membrane removes turbidity and ions from rivers, seawater and sewage wastewater, water treatment membrane to produce industrial water and drinking water, medical membranes such as artificial kidney and plasma separation, food concentrate such as fruit juice It is used in a wide range of fields such as membranes for the beverage industry and gas separation membranes for separating carbon dioxide and the like.
  • Patent Document 2 discloses a technique for obtaining a porous film by immersing a molten film-forming sheet of polymethyl methacrylate and polylactic acid in an aqueous potassium hydroxide solution and hydrolyzing and removing polylactic acid.
  • Patent Literature 3 a resin composition comprising a cellulose ester and a plasticizer is melt-kneaded, and then a plasticizer is eluted from a hollow fiber that is discharged from the die into the air and wound up to obtain a hollow fiber membrane. Is disclosed.
  • a so-called asymmetric membrane is obtained in which the pore diameter varies greatly in the film thickness direction.
  • An asymmetric membrane has a dense layer with a small pore diameter that exhibits separation performance near the surface layer of the membrane.
  • it is necessary to sufficiently reduce the thickness of the dense layer and it is necessary to sufficiently increase the pore diameter other than the dense layer. Due to the former, there is a problem that the film is likely to be defective during manufacture and use, and the latter causes a problem that the film strength is low. That is, a separation membrane that satisfies all of the permeability, stability of membrane performance, and membrane strength could not be obtained.
  • the present invention provides a separation membrane mainly composed of a hydrophilic polymer having excellent permeability and stability of membrane performance and high membrane strength, and a method for producing the same. is there.
  • the present inventors have a hydrophilic polymer as a main component, a phase having the hydrophilic polymer and a co-continuous structure having a structure period of a constant size, and And in the cross section of the thickness direction, it has been found that a separation membrane that can solve the problem can be provided by setting the ratio of the porosity of the surface layer portion and the inner layer portion within a certain range, and has completed the present invention.
  • the separation membrane of the present invention is a separation membrane mainly comprising a hydrophilic polymer, Having a co-continuous structure in which the structural period of the phase having the hydrophilic polymer and the pores is 0.001 ⁇ m or more and 10 ⁇ m or less;
  • the thickness of the separation membrane is 10 ⁇ m or more and 500 ⁇ m or less, In the cross section in the thickness direction, the porosity of the region a having a depth of 1 to 4 ⁇ m from any one surface (A surface) is Ha, and the porosity of the region b having a depth of 1 to 4 ⁇ m from the other surface (B surface).
  • Hb is the porosity of the region c having a thickness of 3 ⁇ m and the same depth from both surfaces.
  • an average porosity calculated by a simple average of the porosity Ha, the porosity Hb, and the porosity Hc is 20% or more and 80% or less.
  • the hydrophilic polymer is at least one selected from the group consisting of polyester, polyamide and cellulose ester.
  • the separation membrane has a hollow fiber shape.
  • the hollow fiber has an outer diameter of not less than 50 ⁇ m and not more than 2500 ⁇ m.
  • a method for producing a separation membrane having a hydrophilic polymer as a main component wherein the separation membrane is produced by performing at least the following steps 1 to 5.
  • Melt-kneading step of obtaining a resin composition by melt-kneading 20% by weight to 80% by weight of hydrophilic polymer and 20% by weight to 80% by weight of a structure-forming agent.
  • Heat treatment step of heating the stretched film obtained in the stretching step at 50 ° C. or more and 300 ° C. or less.
  • An elution step of eluting the structure-forming agent from the film obtained in the heat treatment step
  • a separation membrane having excellent permeability and membrane performance stability and high membrane strength is provided.
  • the separation membrane of the present invention can be preferably used for applications that require permeation performance and high membrane strength.
  • water treatment membranes for removing turbidity from river water, seawater, brine, sewage, drainage, medical membranes such as artificial kidneys and plasma separation, membranes for food and beverage industries such as fruit juice concentration It can be used for gas separation membranes for separating exhaust gas, carbon dioxide gas, etc., and membranes for electronic industries such as fuel cell separators.
  • the type of the water treatment membrane can be preferably used for microfiltration, ultrafiltration and the like.
  • FIG. 1 is a cross-sectional view of a separation membrane and an enlarged view thereof.
  • the separation membrane of the present embodiment is a separation membrane containing a hydrophilic polymer as a main component, Having a co-continuous structure in which the structural period of the phase having the hydrophilic polymer and the pores is 0.001 ⁇ m or more and 10 ⁇ m or less;
  • the thickness of the separation membrane is 10 ⁇ m or more and 500 ⁇ m or less, In the cross section in the thickness direction, the porosity of the region a having a depth of 1 to 4 ⁇ m from any one surface (A surface) is Ha, and the porosity of the region b having a depth of 1 to 4 ⁇ m from the other surface (B surface).
  • the separation membrane of the present invention may contain a liquid such as water in order to maintain its shape. However, in the following description, these liquids for maintaining the shape are not considered as components of the separation membrane.
  • the separation membrane of the present invention can contain the components shown in the following (1) to (5).
  • the separation membrane of the present invention contains a hydrophilic polymer as a main component.
  • the main component refers to a component that is contained most in weight among all the components of the resin composition constituting the separation membrane.
  • the hydrophilic polymer means a polymer containing a hydrophilic group as a constituent component of the polymer and having a contact angle with water of 60 ° or less with respect to the polymer film.
  • the hydrophilic group is a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, or an amide group.
  • hydrophilic polymer examples include polyester, polyamide, polymethyl acrylate, polyvinyl acetate, cellulose ester, polyester, and the like. Among these, it is preferable that it is at least 1 sort (s) chosen from the group which consists of polyester, polyamide, and a cellulose ester.
  • polyamide examples include nylon 6 and nylon 11.
  • cellulose ester examples include cellulose esters such as cellulose acetate, cellulose propionate, and cellulose butyrate, and cellulose mixed esters such as cellulose acetate propionate and cellulose acetate butyrate.
  • the weight average molecular weight (Mw) of the cellulose ester is preferably 50,000 to 250,000.
  • Mw is 50,000 or more, the thermal decomposition of the cellulose ester when melted during the production of the separation membrane is suppressed, and the membrane strength of the separation membrane can reach a practical level.
  • Mw is 250,000 or less, the melt viscosity does not become too high, so that stable melt film formation is possible.
  • Mw is more preferably 60,000 to 220,000, and further preferably 80,000 to 200,000.
  • the weight average molecular weight (Mw) is a value calculated by GPC measurement. The calculation method will be described in detail in Examples.
  • Each illustrated cellulose mixed ester has an acetyl group and another acyl group (propionyl group, butyryl group, etc.).
  • the average degree of substitution between the acetyl group and other acyl groups preferably satisfies the following formula. 1.0 ⁇ (average degree of substitution of acetyl group + average degree of substitution of other acyl groups) ⁇ 3.0 0.1 ⁇ (Average degree of substitution of acetyl group) ⁇ 2.6 0.1 ⁇ (average degree of substitution of other acyl groups) ⁇ 2.6
  • the average degree of substitution refers to the number of chemically bonded acyl groups (acetyl group + other acyl groups) among the three hydroxyl groups present per glucose unit of cellulose.
  • hydrophilic polymer Only one kind of hydrophilic polymer may be contained, or two or more kinds thereof may be contained.
  • the content of the hydrophilic polymer in the resin composition constituting the separation membrane is preferably from 70 to 100% by weight, and preferably from 80 to 100% by weight, assuming that all components of the resin composition constituting the separation membrane are 100% by weight. % Is more preferable, and 90 to 100% by weight is particularly preferable.
  • hydrophilic polymer is preferably contained in an amount of 20% by weight to 80% by weight, based on 100% by weight of the total components constituting the raw material for film formation.
  • the content When the content is 20% by weight or more, the membrane strength of the separation membrane is improved. When the content is 80% by weight or less, the thermoplasticity and permeation performance of the separation membrane are improved.
  • the content is more preferably 25% by weight or more, and further preferably 30% by weight or more. Further, the content is more preferably 70% by weight or less, and further preferably 60% by weight or less.
  • the resin composition constituting the separation membrane of the present invention may contain a plasticizer for hydrophilic polymer.
  • the plasticizer for the hydrophilic polymer is not particularly limited as long as it is a compound that thermoplasticizes the hydrophilic polymer. Moreover, not only one type of plasticizer but also two or more types of plasticizers may be used in combination.
  • hydrophilic polymer plasticizers include polyalkylene glycol compounds such as polyethylene glycol and polyethylene glycol fatty acid esters, glycerin compounds such as glycerin fatty acid esters and diglycerin fatty acid esters, citrate ester compounds, and phosphate esters. And fatty acid ester compounds such as adipic acid esters, caprolactone compounds, and derivatives thereof.
  • polyalkylene glycol compound examples include polyethylene glycol, polypropylene glycol, and polybutylene glycol having a weight average molecular weight of 400 to 4,000.
  • the hydrophilic polymer plasticizer may remain in the separation membrane after the separation membrane is formed or may be eluted from the separation membrane. In the case of elution, traces from which the plasticizer has fallen may become pores in the film, and as a result, the permeation performance is improved.
  • the hydrophilic polymer plasticizer is preferably contained in an amount of 5% by weight to 40% by weight, based on 100% by weight of the total components constituting the raw material for film formation.
  • the content is 5% by weight or more, the thermoplasticity of the hydrophilic polymer and the permeation performance of the separation membrane are improved. By setting the content to 40% by weight or less, the membrane strength of the separation membrane is improved.
  • the content of the plasticizer of the hydrophilic polymer is more preferably 10 to 35% by weight, still more preferably 15 to 30% by weight.
  • the resin composition constituting the separation membrane of the present invention preferably contains an antioxidant.
  • the antioxidant it is preferable to contain a phosphorus-based antioxidant, and a pentaerythritol-based compound is more preferable.
  • a pentaerythritol-based compound include bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite.
  • the content of the antioxidant is preferably 0.005 to 0.500% by weight when the total of the components constituting the raw material for film formation is 100% by weight.
  • the resin composition constituting the separation membrane of the present invention may contain a structure-forming agent.
  • the structure-forming agent refers to a compound that is partially compatible with a mixture of a hydrophilic polymer and a plasticizer. Partially compatible means that two or more substances are completely compatible under certain conditions but phase-separated under other conditions.
  • the structure-forming agent is a substance that undergoes phase separation from the hydrophilic polymer by being placed under specific conditions in the below-described co-continuous structure forming step.
  • the structure-forming agent in the present invention is preferably hydrophilic, and refers to a resin that dissolves in water or has a smaller contact angle with water than the main hydrophilic polymer.
  • the structure-forming agent examples include polyvinylpyrrolidone (PVP), PVP / vinyl acetate copolymer, PVP-based copolymers such as PVP / methyl methacrylate copolymer, polyvinyl alcohol, and polyester compounds. can give. These can be used alone or in combination.
  • the weight average molecular weight is 20,000 from the viewpoint that intermolecular crosslinking is relatively difficult to proceed and can be eluted even after crosslinking.
  • the following is preferable. It is also preferable to use the PVP-based copolymer described in the previous paragraph because thermal crosslinking is suppressed.
  • the structure forming agent is eluted from the separation membrane after the separation membrane is formed.
  • traces from which the structure-forming agent has been removed may become pores in the film, resulting in good permeation performance.
  • a structure formation agent may remain
  • the content of the structure-forming agent is preferably 20% by weight or more and 80% by weight or less when the total of the components constituting the film-forming raw material is 100% by weight.
  • the content of the structure forming agent is more preferably 30% by weight or more, and still more preferably 40% by weight. Further, the content of the structure forming agent is more preferably 75% by weight or less, and still more preferably 70% by weight or less.
  • the resin composition constituting the separation membrane of the present invention may contain additives other than those described in (1) to (4) as long as the effects of the present invention are not impaired.
  • additives include resins such as cellulose ether, polyacrylonitrile, polyolefin, polyvinyl compound, polycarbonate, poly (meth) acrylate, polysulfone, polyethersulfone, organic lubricant, crystal nucleating agent, organic particles, inorganic particles, terminal Blocking agent, chain extender, ultraviolet absorber, infrared absorber, anti-coloring agent, matting agent, antibacterial agent, antistatic agent, deodorant, flame retardant, weathering agent, antistatic agent, antioxidant, ion exchange Agents, antifoaming agents, color pigments, fluorescent brighteners, dyes and the like.
  • resins such as cellulose ether, polyacrylonitrile, polyolefin, polyvinyl compound, polycarbonate, poly (meth) acrylate, polysulfone, polyethersulfone, organic lubricant, crystal nucleating agent, organic particles, inorganic particles, terminal Blocking agent, chain extender, ultraviolet absorber, infrared absorb
  • the shape of the separation membrane of the present invention is not particularly limited, but a hollow fiber-shaped separation membrane (hereinafter also referred to as a hollow fiber membrane) or a planar membrane (hereinafter also referred to as a flat membrane) is preferably employed.
  • the hollow fiber membrane is more preferable because it can be efficiently filled into the module and the effective membrane area per unit volume of the module can be increased.
  • a hollow fiber membrane is a filamentous membrane having a hollow.
  • the thickness of the separation membrane is preferably 10 ⁇ m or more and 500 ⁇ m or less from the viewpoint of achieving both permeation performance and membrane strength.
  • the thickness of the separation membrane is more preferably 20 ⁇ m or more, further preferably 30 ⁇ m or more, and particularly preferably 40 ⁇ m or more.
  • the thickness of the separation membrane is more preferably 400 ⁇ m or less, further preferably 300 ⁇ m or less, and particularly preferably 200 ⁇ m or less.
  • the outer diameter of the hollow fiber membrane is 50 ⁇ m or more and 2500 ⁇ m or less from the viewpoint of achieving both effective membrane area when the module is filled and membrane strength.
  • the outer diameter of the hollow fiber membrane is more preferably 100 ⁇ m or more, further preferably 200 ⁇ m or more, and particularly preferably 300 ⁇ m or more. Further, the outer diameter of the hollow fiber membrane is more preferably 2000 ⁇ m or less, further preferably 1500 ⁇ m or less, and particularly preferably 1000 ⁇ m or less.
  • the hollow ratio of the hollow fiber is preferably 15 to 70%, more preferably 20 to 65%, from the relationship between the pressure loss of the fluid flowing through the hollow part and the buckling pressure. Preferably, it is 25 to 60%.
  • the method of setting the outer diameter and hollow ratio of the hollow fiber in the hollow fiber membrane in the above range is not particularly limited.
  • the separation membrane of the present invention it is important to have a co-continuous structure in which the structure period of the phase having the hydrophilic polymer and the pores is 0.001 ⁇ m or more and 10 ⁇ m or less.
  • the co-continuous structure means, for example, a phase and pores having a hydrophilic polymer when a cross section obtained by applying stress to a separation membrane sufficiently cooled in liquid nitrogen and observing it with a scanning electron microscope (SEM) or the like.
  • SEM scanning electron microscope
  • the measuring method of a structure period is described in an Example.
  • the width of the structural period is sometimes simply referred to as the hole diameter.
  • the structural period is preferably 0.005 ⁇ m or more, more preferably 0.010 ⁇ m or more, further preferably 0.015 ⁇ m or more, and particularly preferably 0.020 ⁇ m or more.
  • the structural period is preferably 5.0 ⁇ m or less, more preferably 1.0 ⁇ m or less, further preferably 0.5 ⁇ m or less, particularly preferably 0.3 ⁇ m or less or 0.2 ⁇ m or less, and most preferably 0.1 ⁇ m or less.
  • the method of setting the structural period in the above range is not particularly limited, it is possible to employ stretching under the conditions described later and then heat treatment under the conditions described later when manufacturing the separation membrane.
  • Ha / Hc is preferably 1.05 or more, more preferably 1.10 or more, and even more preferably 1.15 or more. It is especially preferable that it is 20 or more. Further, Ha / Hc is preferably 1.45 or less, more preferably 1.40 or less, further preferably 1.35 or less, and particularly preferably 1.30 or less. Similarly, Hb / Hc is preferably 1.10 or more, more preferably 1.15 or more, further preferably 1.20 or more, and particularly preferably 1.25 or more. . Further, Ha / Hc is preferably 1.45 or less, more preferably 1.40 or less, further preferably 1.35 or less, and particularly preferably 1.30 or less.
  • the method of setting Ha / Hc and Hb / Hc in the above ranges is not particularly limited, but it is possible to use stretching under the conditions described later and then heat treatment under the conditions described later when manufacturing the separation membrane.
  • the average porosity calculated by the simple average of the porosity Ha, Hb, Hc is 20% or more and 80% or less.
  • the average porosity is more preferably 25% or more, further preferably 30% or more, and particularly preferably 35% or more.
  • the average porosity is more preferably 75% or less, further preferably 70% or less, and particularly preferably 65% or less.
  • the method for setting the average porosity in the above range is not particularly limited, but a method for setting the content of the structure forming agent in the whole components constituting the raw material for film formation in the above preferable range can be used.
  • the polymer phase and the pores have a co-continuous structure having a constant structural period in the cross section in the thickness direction, and In the cross section in the film thickness direction, there is a relationship that the porosity in the vicinity of at least one surface layer is larger than the porosity in the central portion in the thickness direction.
  • the former co-continuous structure makes it possible to develop high film strength. Further, the latter relationship between the porosity in the thickness direction of the film makes it possible to express high permeability and stability of the film performance.
  • the separation membrane of the present invention preferably has a membrane permeation flux at 50 kPa and 25 ° C. of 0.1 m 3 / m 2 / h or more and 10 m 3 / m 2 / h or less.
  • the membrane permeation flux is more preferably 0.3 m 3 / m 2 / h or more, and further preferably 0.5 m 3 / m 2 / h or more.
  • the separation membrane of the present invention preferably has a tensile strength in the longitudinal direction of 30 MPa or more in order to exhibit membrane strength against tensile in the longitudinal direction.
  • the conditions for measuring the tensile strength will be described in detail in Examples.
  • the tensile strength is more preferably 50 MPa or more, further preferably 70 MPa or more, and particularly preferably 90 MPa or more. Higher tensile strength is preferable, but it is preferably 300 MPa or less from the viewpoint of balance with elongation.
  • the method for producing the separation membrane of the present invention comprises: 1. Melt-kneading step of obtaining a resin composition by melt-kneading 20% by weight to 80% by weight of hydrophilic polymer and 20% by weight to 80% by weight of a structure-forming agent. 2. A film forming process for forming a film by discharging and cooling the resin composition from a die. 3. Stretching process for stretching the film at a stretch ratio of 1.1 to 5.0. 4. Heat treatment step of heating the stretched film obtained in the stretching step at 50 ° C. or more and 300 ° C. or less. An elution step of eluting the structure-forming agent from the film obtained in the heat treatment step.
  • the method for producing the separation membrane of the present invention will be specifically described by taking a case where the separation membrane is a hollow fiber membrane as an example, but is not limited thereto.
  • a method of melt-kneading 20% by weight to 80% by weight of a hydrophilic polymer and 20% by weight to 80% by weight of a structure forming agent is used. It is done. If necessary, a hydrophilic polymer plasticizer, antioxidant, and additive of the above-described types and contents can be contained.
  • the apparatus to be used is not particularly limited, and a known mixer such as a kneader, roll mill, Banbury mixer, single-screw or twin-screw extruder can be used.
  • a known mixer such as a kneader, roll mill, Banbury mixer, single-screw or twin-screw extruder
  • twin screw extruder from the viewpoint of improving the dispersibility of the structure forming agent and the plasticizer, it is preferable to use a twin screw extruder.
  • a twin screw extruder From the viewpoint of removing volatiles such as moisture and low molecular weight substances, it is more preferable to use a twin screw extruder with a vent hole.
  • the obtained resin composition may be once pelletized and melted again and used for melt film formation, or may be directly guided to a die and used for melt film formation. Once pelletized, it is preferable to use a resin composition in which the pellet is dried to have a moisture content of 200 ppm (weight basis) or less.
  • a hollow fiber membrane is formed by discharging the resin composition melted by the above method into the air from a spinneret having a double annular nozzle having a gas flow path at the center, and cooling with a cooling device.
  • the draft ratio that can be calculated by the winding speed / discharge speed is preferably 50 or more and 500 or less.
  • the draft ratio is more preferably 400 or less, and further preferably 300 or less.
  • the formed hollow fiber membrane may be wound up once, unwound again and used for stretching, or may be directly guided to a stretching process for stretching.
  • the stretching process is not only preferable in terms of improving the film strength by increasing the orientation of the hydrophilic polymer, but is also important in controlling the internal structure and porosity of the film formed by the subsequent heat treatment within the above-mentioned range. is there.
  • the stretching method is not particularly limited, for example, the temperature may be increased to a temperature at which stretching is performed by conveying the hollow fiber membrane before stretching on a heated roll, and a method of stretching using a peripheral speed difference between the rolls may be used, A method may be used in which the hollow fiber membrane before stretching is heated to a temperature at which stretching is performed by transporting it in a dry heat oven, and stretched using a peripheral speed difference between rolls. In addition, the stretching may be performed in one stage, or may be performed in two or more stages.
  • the preferable range of the temperature of the hollow fiber membrane in the stretching step is 40 to 180 ° C, more preferably 60 to 160 ° C, still more preferably 80 to 140 ° C.
  • the total draw ratio is preferably 1.2 times or more, more preferably 1.4 times or more, and further preferably 1.6 times or more.
  • the total draw ratio is preferably 5.0 times or less, more preferably 4.5 times or less, and further preferably 4.0 times or less.
  • the hollow fiber membrane (stretched membrane) is heat-treated by heating at 50 to 300 ° C.
  • phase separation between the hydrophilic polymer and the structure forming agent is induced.
  • the heat treatment may be carried out on a heated roll, may be carried in a dry heat oven, or may be put into a dry heat oven in a roll wound around a bobbin or a paper tube. .
  • the heat treatment temperature is preferably 80 to 300 ° C, more preferably 100 to 250 ° C, and further preferably 120 to 250 ° C.
  • the heat treatment time is preferably 10 to 600 seconds, more preferably 20 to 480 seconds, and further preferably 30 to 360 seconds.
  • the hollow fiber membrane after the heat treatment is immersed in water, an acid aqueous solution, an alkaline aqueous solution, an alcohol, or an alcohol aqueous solution, and the step of eluting the structure-forming agent, and then the separation membrane (hollow fiber membrane) of the present invention To do. Since the present invention is a method of eluting the structure-forming agent after inducing phase separation by performing heat treatment, voids exceeding 10 ⁇ m are not easily formed on the resulting separation membrane.
  • the separation membrane thus obtained can be used as it is, it is preferable to hydrophilize the surface of the membrane with, for example, an alcohol-containing aqueous solution or an alkaline aqueous solution before use.
  • the separation membrane of the present invention having a hydrophilic polymer as a main component can be produced.
  • the separation membrane of the present invention may be incorporated into a separation membrane module at the time of use.
  • the separation membrane module includes, for example, a membrane bundle composed of a plurality of hollow fiber membranes and a housing that accommodates the membrane bundle.
  • Average substitution degree of cellulose mixed ester The calculation method of the average substitution degree of the cellulose mixed ester in which an acetyl group and an acyl group are bonded to cellulose is as follows. After 0.9 g of cellulose ester mixed for 8 hours at 80 ° C. was weighed and dissolved by adding 35 ml of acetone and 15 ml of dimethyl sulfoxide, 50 ml of acetone was further added. While stirring, 30 ml of 0.5N sodium hydroxide aqueous solution was added and saponified for 2 hours. After adding 50 ml of hot water and washing the side of the flask, it was titrated with 0.5 N sulfuric acid using phenolphthalein as an indicator.
  • the film cross section was observed with the center in the film thickness direction as the center of the microscope field.
  • the obtained scanning electron microscope image was subjected to Fourier transform, and the presence or absence of a maximum peak when the wave number was plotted on the horizontal axis and the intensity was plotted on the vertical axis was confirmed.
  • the image size of the scanning electron microscope image was a square with one side having a length of 10 to 100 times the hole diameter.
  • Measurement method 2 When the periodic structure is not measured by the measurement method 1, the structural period is measured by the following method. After the separation membrane immersed in a 50% aqueous solution of glycerin for 1 hour was frozen with liquid nitrogen, it was cleaved by applying stress so that a section perpendicular to the longitudinal direction of the separation membrane and a thickness direction of the membrane appeared. At this time, if the longitudinal direction of the separation membrane is unknown, it is cleaved in an arbitrary direction. Moreover, when cleaving, a razor or a microtome is used as necessary.
  • the separation membrane having a cross-section was vacuum-dried at 25 ° C. for 8 hours, and the obtained cross-section was observed with a scanning electron microscope. At this time, the film cross section was observed with the center in the film thickness direction as the center of the microscope field. In the obtained image, the diameters of 20 pores were measured and number averaged to obtain the structural period. At this time, the image size of the scanning electron microscope image is a square with one side having a length of 10 to 100 times the hole diameter.
  • both surfaces A region c having a thickness of 3 ⁇ m having the same depth from the center was observed and photographed at arbitrary five points with a scanning electron microscope.
  • a transparent film or sheet was overlaid on the obtained photograph, and the portion corresponding to the gap was painted with oil-based ink or the like. Next, the ratio of the area corresponding to the air gap is obtained using an image analyzer.
  • the image size of the scanning electron microscope image is a square with one side having a length of 10 to 100 times the hole diameter.
  • Tensile strength The tensile strength in the longitudinal direction of the separation membrane that was vacuum-dried at 25 ° C. for 8 hours was measured using a tensile tester (Orientec Tensilon UCT-100) in an environment of 20 ° C. and 65% humidity. . Specifically, measurement was performed under the conditions of a sample length of 100 mm and a tensile speed of 100 mm / min, and the tensile strength (breaking strength) (MPa) was calculated from the tensile strength. The number of measurements was 5, and the average value was used.
  • Membrane permeation flux (m 3 / m 2 / h)
  • the separation membrane was a hollow fiber membrane
  • a small module having an effective length of 200 mm consisting of four hollow fiber membranes was produced.
  • the amount of permeated water (m 3 ) obtained by feeding distilled water over 30 minutes to the module at a temperature of 25 ° C. and a filtration differential pressure of 16 kPa was measured, and the unit time (h) and unit membrane area (m 2 ) were measured.
  • Per unit value, and further converted into pressure (50 kPa) to obtain permeation performance of pure water (unit m 3 / m 2 / h).
  • Cellulose ester (A1) Cellulose acetate propionate obtained by the following method To 100 parts by weight of cellulose (cotton linter), 240 parts by weight of acetic acid and 67 parts by weight of propionic acid were added and mixed at 50 ° C. for 30 minutes. After the mixture was cooled to room temperature, 172 parts by weight of acetic anhydride cooled in an ice bath and 168 parts by weight of propionic anhydride were added as an esterifying agent, and 4 parts by weight of sulfuric acid was added as an esterification catalyst, followed by stirring for 150 minutes. An esterification reaction was performed. In the esterification reaction, when it exceeded 40 ° C., it was cooled in a water bath.
  • Plasticizer (B) Polyethylene glycol, weight average molecular weight 600
  • Structure forming agent (C) Structure forming agent (C1): PVP / vinyl acetate copolymer (Kollidon VA 64 (BASF Japan Ltd.)) Structure forming agent (C2): Polyvinylpyrrolidone (PVP K17)
  • Antioxidant (D) Antioxidant (D1): Bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite
  • Example 1 45% by weight of the hydrophilic polymer (A1), 24.9% by weight of the plasticizer (B1), 30% by weight of the structure forming agent (C1) and 0.1% by weight of the antioxidant (D1) in a twin screw extruder The mixture was melt-kneaded at 220 ° C., homogenized and then pelletized to obtain a resin composition for melt spinning. This resin composition was vacuum-dried at 80 ° C. for 8 hours.
  • the dried resin composition is supplied to a twin screw extruder, melted and kneaded at 220 ° C., and then introduced into a melt spinning pack having a spinning temperature of 220 ° C.
  • a double tube type, a discharge hole diameter of 8.3 mm, and a slit width of 1.1 mm was spun downward from the outer annular portion of the die having one hole.
  • the spun hollow fiber was guided to a cooling device, cooled with cooling air at 25 ° C. and a wind speed of 1.5 m / sec, and wound with a winder so that the draft ratio was 60.
  • the spun yarn was heated to 100 ° C. by passing through a dry heat oven, and wound up at a draw ratio of 1.3 times using a difference in peripheral speed between rolls.
  • the separation membrane was immersed in a 50% ethanol aqueous solution for 12 hours to elute the plasticizer and the structure forming agent.
  • Table 1 shows the physical properties of the obtained separation membrane. The structure period was measured using the method described in Measurement Method 1 above.
  • Examples 2 to 13, Comparative Example 1 A separation membrane was obtained in the same manner as in Example 1 except that the production conditions were as shown in Table 1. Table 1 shows the physical properties of the obtained separation membrane. The structural period was measured using Examples 2 to 10 and Example 13 using the method described in Measurement Method 1 above, and Examples 11 and 12 using the method described in Measurement Method 2 above. .
  • the present invention is a separation membrane mainly composed of a hydrophilic polymer having excellent permeability and membrane performance stability and high membrane strength.
  • the separation membrane of the present invention is a water treatment membrane for producing industrial water, drinking water, etc. from seawater, brine, sewage, drainage, etc., a medical membrane such as an artificial kidney or plasma separation, and a food / beverage such as fruit juice concentrate It can be used for industrial membranes, gas separation membranes for separating exhaust gas, carbon dioxide gas, etc., and membranes for electronic industries such as fuel cell separators.
  • the water treatment membrane can be preferably used for microfiltration membranes, ultrafiltration membranes, and the like.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)

Abstract

La membrane de séparation de la présente invention comprend un polymère hydrophile en tant que composant principal, a une structure co-continue dans laquelle une phase comprenant le polymère hydrophile et les pores a une période structurale de 0,001 à 10 µm, et présente une épaisseur de 10 à 500 µm. La membrane de séparation a une section transversale dans le sens de l'épaisseur qui satisfait la relation (1) et la relation (2), où Ha est la porosité de la région a qui s'étend de 1 µm à 4 µm en termes de distance dans le sens de profondeur à partir de l'une des surfaces, Hb représente la porosité de la région b qui s'étend de 1 µm à 4 µm en termes de distance dans le sens de la profondeur à partir de l'autre surface, et Hc est la porosité de 3 µm d'épaisseur c située à la même distance des deux surfaces. (1) 1,00 ≤ Ha/Hc ≤ 1,50 (2) 1,05≤Hb/Hc≤1,50
PCT/JP2017/027491 2016-07-29 2017-07-28 Membrane de séparation et son procédé de fabrication Ceased WO2018021545A1 (fr)

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Cited By (1)

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JP2011078920A (ja) * 2009-10-08 2011-04-21 Toyobo Co Ltd 選択透過性中空糸膜
JP2014073487A (ja) * 2012-09-11 2014-04-24 Toray Ind Inc 多孔質膜、多孔質膜を内蔵する浄水器および多孔質膜の製造方法
WO2015041286A1 (fr) * 2013-09-18 2015-03-26 三菱レイヨン株式会社 Membrane à fibre creuse poreuse et son procédé de fabrication
WO2016052675A1 (fr) * 2014-09-30 2016-04-07 東レ株式会社 Membrane de séparation
WO2016113964A1 (fr) * 2015-01-16 2016-07-21 旭化成メディカル株式会社 Membrane poreuse de fibres creuses
WO2017057766A1 (fr) * 2015-09-30 2017-04-06 東レ株式会社 Film de séparation, composition de résine à base de cellulose, et procédé de fabrication de film de séparation
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JPH01148305A (ja) * 1986-04-28 1989-06-09 Asahi Chem Ind Co Ltd 高文子多孔質中空糸及びそれを利用したウイルスの除去方法
JP2008272636A (ja) * 2007-04-26 2008-11-13 Asahi Kasei Corp 多層微多孔膜
JP2011078920A (ja) * 2009-10-08 2011-04-21 Toyobo Co Ltd 選択透過性中空糸膜
JP2014073487A (ja) * 2012-09-11 2014-04-24 Toray Ind Inc 多孔質膜、多孔質膜を内蔵する浄水器および多孔質膜の製造方法
WO2015041286A1 (fr) * 2013-09-18 2015-03-26 三菱レイヨン株式会社 Membrane à fibre creuse poreuse et son procédé de fabrication
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WO2017131209A1 (fr) * 2016-01-29 2017-08-03 東レ株式会社 Membrane de séparation

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Publication number Priority date Publication date Assignee Title
JPWO2021132399A1 (fr) * 2019-12-23 2021-07-01
WO2021132399A1 (fr) * 2019-12-23 2021-07-01 東レ株式会社 Membrane de séparation et procédé de production d'une membrane de séparation
JP7078171B2 (ja) 2019-12-23 2022-05-31 東レ株式会社 分離膜及び分離膜の製造方法
US11794150B2 (en) 2019-12-23 2023-10-24 Toray Industries, Inc. Separation membrane and method for producing separation membrane

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