Porous film and method for producing porous film

Abstract

To provide a porous film in which adsorption of protein is suppressed.SOLUTION: A porous film contains at least two kinds of polyether ketone-based polymers. The polyether ketone-based polymer contains a sulfonic acid group or its salt. The porous film has at least one through hole.SELECTED DRAWING: None

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to porous membranes and methods for making porous membranes. [Background technology]

[0002] Porous membranes have traditionally been used as filtration membranes. Patent Document 1 discloses a porous membrane having a skeleton made of a polymer selected from the group consisting of polysulfone and polyethersulfone, and further containing polyvinylpyrrolidone.

[0003] On the other hand, aromatic polyether ketones containing sulfonic acid groups (for example, 5,5'-carbonylbis(sodium 2-fluorobenzenesulfonate)) are used as raw materials for ion exchange membranes that do not have through-holes (non-porous membranes) (see Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-31626 [Patent Document 2] Patent Publication No. 2021-123648 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the porous membrane disclosed in Patent Document 1 may not be able to sufficiently suppress protein adsorption.

[0006] The embodiments of the present disclosure have been made in view of the above, and an object of the present disclosure is to provide a porous membrane in which protein adsorption is suppressed, and a method for manufacturing the porous membrane. [Means for solving the problem]

[0007] The means for solving the above problems include the following embodiments. <1> Contains at least two types of polyetherketone polymers, the polyether ketone polymer contains a sulfonic acid group or a salt thereof, A porous membrane having at least one through hole. <2> The mean flow pore size is 0.1 μm to 10.0 μm. <1> The porous membrane according to claim 1. <3> The mean flow pore size is 0.5 μm to 1.7 μm. <2> The porous membrane according to claim 1. <4> The dry film thickness is 50 μm to 300 μm, The mean flow pore size is 0.4 μm to 1.3 μm. <2> The porous membrane according to claim 1. <5> It has at least two peak tops in a GPC chart obtained by gel permeation chromatography (GPC) measurement, the logarithm (logM) of the molecular weight at the peak top is 3 or more; <1> ~ <4> 10. The porous membrane according to any one of the preceding items. <6> The sulfonic acid equivalent is 100 g / mol to 5000 g / mol. <1> ~ <5> 10. The porous membrane according to any one of the preceding items. <7> The polyether ketone polymer has a structural unit represented by the following formula (a1) or a structural unit represented by the following formula (a2): <1> ~ <6> 10. The porous membrane according to any one of the preceding items. [ka] [In formula (a1) and formula (a2), R 1 ~R 10 are each independently H, Cl, F, CF3 or C m H 2m+1 (m represents an integer from 1 to 10.) R 1 ~R 10 may be present in two or more aromatic rings. m H 2m+1 If there are two or more C m H 2m+1may be the same or different. 1 ~A 6 are each independently a direct bond, -CH2-, -C(CH3)2-, -C(CF3)2-, -O-, or -CO-. 1 ~A 3 At least one of X is -CO-. 1 ~X 5 are each independently H, Cl, F, CF3, a sulfonic acid group, or a salt of a sulfonic acid group, and X 1 ~X 5 At least one of X is a sulfonic acid group or a salt of a sulfonic acid group. 1 ~X 5 may be present in two or more in an aromatic ring, and when two or more sulfonic acid groups are present in one aromatic ring, the respective sulfonic acid groups may be the same or different. i, j, k, and l each independently represent 0 or 1.] <8> the polyether ketone polymer contains a polymer (A1) and a polymer (A2), The sulfonic acid equivalent of the polymer (A1) is higher than the sulfonic acid equivalent of the polymer (A2). <7> The porous membrane according to claim 1. <9> The above-mentioned method is used to capture microorganisms. <1> ~ <8> 10. The porous membrane according to any one of the preceding items. <10> The aforementioned <8> A method for producing the porous membrane according to claim 1, preparing a solution containing the polymer (A1), the polymer (A2), and an organic solvent; forming a coating film using the solution, and immersing the coating film in water or a poor solvent for the polymer (A1) and the polymer (A2) (non-solvent induced phase separation method), or exposing the coating film to a water vapor atmosphere or a gas atmosphere of the poor solvent, thereby forming the porous film. [Effects of the Invention]

[0008] According to an embodiment of the present disclosure, a porous membrane in which protein adsorption is suppressed and a method for manufacturing the porous membrane are provided. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the present disclosure, the symbol "to" indicating a range of values ​​is used to mean that the values ​​before and after it are included as the lower limit and upper limit. In the present disclosure, in the numerical ranges described in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with the value shown in the examples. In the present disclosure, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved. In the present disclosure, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, it means the total amount of the multiple substances present in the composition, unless otherwise specified.

[0010] (1) Porous membrane The porous membrane of the present disclosure comprises at least two types of polyetherketone polymers. The polyetherketone polymers contain a sulfonic acid group (—SO3H) or a salt thereof. The porous membrane of the present disclosure has at least one through-hole.

[0011] The term "polyetherketone polymer" refers to a polymer containing an ether bond (-O-) and a ketone bond (-CO-) in the constituent repeating unit.

[0012] The porous membrane of the present disclosure has the above-described configuration, and therefore, protein adsorption is suppressed. This effect is presumably due to, but not limited to, the following reasons. Compared with conventional porous membrane materials such as polysulfone and polyethersulfone, the porous membrane made of the "polyetherketone polymer" of the present disclosure has a structure in which a sulfonic acid group or its salt is present in the side chain. The presence of sulfonic acid groups or their salts in the side chains allows many sulfonic acid groups or their salts to be localized on the surface of the porous membrane, thereby suppressing protein adsorption to a greater extent than conventional membranes.

[0013] (1.1) Overall The porous membrane has at least one through-hole. The shape and number of the through-hole are not particularly limited and are appropriately selected depending on the application of the porous membrane.

[0014] The dry thickness of the porous membrane is not particularly limited and is appropriately selected depending on the application of the porous membrane, etc. From the viewpoint of water permeability and membrane strength, the dry thickness of the porous membrane is preferably 10 μm to 1000 μm, more preferably 20 μm to 500 μm, and even more preferably 50 μm to 300 μm. The method for measuring the dry thickness is the same as that described in the examples.

[0015] The mean flow pore size of the porous membrane is not particularly limited, but is preferably 0.1 μm to 10.0 μm, which suppresses protein adsorption to the porous membrane more than when the mean flow pore size is outside the range of 0.1 μm to 10.0 μm. The mean flow pore size of the porous membrane is more preferably 0.5 μm to 1.7 μm, which suppresses protein adsorption to the porous membrane more than when the mean flow pore size is outside the range of 0.5 μm to 1.7 μm. The method for measuring the mean flow pore size is the same as that described in the Examples. The smaller the mean flow pore size of the porous membrane, the smaller the pore size of the porous membrane.

[0016] The dry thickness of the porous membrane is preferably 50 μm to 300 μm, and the mean flow pore size of the porous membrane is preferably 0.4 μm to 1.3 μm, which improves the mechanical strength of the porous membrane and suppresses protein adsorption to the porous membrane.

[0017] In a GPC chart obtained by gel permeation chromatography (GPC) measurement, the porous membrane preferably has at least two peak tops, and the logarithm (logM) of the molecular weight of the peak tops is 3 or more. The logarithm (logM) of the molecular weight of at least two peak tops being 3 or more indicates that the porous membrane contains two or more types of polymer (A) described below that form the porous membrane, and has a molecular weight sufficient to form the porous membrane. This allows the formation of a porous membrane having one or more pores, while a single peak top or 3 or less does not allow the formation of a porous membrane. "Peak top" refers to the maximum point on the molecular weight distribution curve. "Molecular weight distribution curve" refers to the relationship between the logarithm of molecular weight (logM) and elution time. From the viewpoint of forming a porous film, the logarithm (logM) of the molecular weight at the peak top may be 3 or more, or may be 4 or more. The logarithm (logM) of the molecular weight at the peak top may be 7 or less, or may be 6 or less. The method for measuring the peak top is the same as that described in the Examples.

[0018] The sulfonic acid equivalent of the porous membrane is preferably 100 g / mol to 5000 g / mol. This allows the porous membrane to be produced more easily than when the sulfonic acid equivalent of the porous membrane is outside the range of 100 g / mol to 5000 g / mol. That is, when the sulfonic acid equivalent is less than 100 g / mol, the porous membrane may become a gel. When the sulfonic acid equivalent is more than 5000 g / mol, the porous membrane does not dissolve uniformly in the solvent, making it difficult to form the membrane. The sulfonic acid equivalent weight of the porous membrane may be 100 g / mol or more, or 300 g / mol or more, and may be 5000 g / mol or less, or 2000 g / mol or less.

[0019] (1.2) Polyether ketone polymer The porous membrane contains at least two types of polyether ketone polymers.

[0020] The number of types of polyether ketone polymers is not particularly limited as long as it is 2 or more, and may be 2, 3, or 4 or more. The blend ratio of the at least two types of polyether ketone polymers is appropriately selected depending on the application of the porous membrane, etc.

[0021] The polyether ketone polymer contains a sulfonic acid group or a salt thereof. The term "salt of a sulfonic acid group" refers to a salt compound in which the hydrogen atom of the sulfonic acid group is replaced with a salt. The salt is not particularly limited, and examples thereof include salts of Group 1 elements (e.g., lithium, sodium, potassium, etc.), Group 2 elements (e.g., calcium, magnesium, barium, etc.), and ammonium salts.

[0022] The polyetherketone polymer may be a copolymer, such as a block copolymer, a random copolymer, an alternating copolymer, or a graft copolymer.

[0023] (1.2.1) Building blocks The polyether ketone polymer comprises a structural unit represented by the following formula (a1) (hereinafter also referred to as "structural unit (a1)") or a structural unit represented by the following formula (a2) (hereinafter also referred to as "structural unit (a2)").

[0024] [ka]

[0025] In the above formula (a1) and formula (a2), R 1 ~R 10 are each independently H, Cl, F, CF3, or C m H 2m+1 (m represents an integer from 1 to 10.) R 1 ~R 10 may be present in two or more aromatic rings. m H2 m+1 If there are two or more C m H 2m+1may be the same or different. 1 ~A 6 are each independently a direct bond, -CH2-, -C(CH3)2-, -C(CF3)2-, -O-, or -CO-. 1 ~A 3 At least one of X is -CO-. 1 ~X 5 are each independently H, Cl, F, CF3, a sulfonic acid group, or a salt of a sulfonic acid group, and X 1 ~X 5 At least one of X is a sulfonic acid group or a salt of a sulfonic acid group. 1 ~X 5 may be present in two or more in an aromatic ring, and when two or more sulfonic acid groups are present in one aromatic ring, the respective sulfonic acid groups may be the same as or different from one another. i, j, k, and l each independently represent 0 or 1.

[0026] The content of sulfonic acid groups or salts of sulfonic acid groups in the polyether ketone polymer is preferably 8 mol% to 70 mol%, more preferably 10 mol% to 50 mol%, and even more preferably 25 mol% to 30 mol%, based on all structural units contained in the polyether ketone polymer.

[0027] The structural unit (a1) may be a structural unit (a1-1) represented by the following formula (a1-1), a structural unit (a1-2) represented by the following formula (a1-2), or a structural unit (a1-3) represented by the following formula (a1-3).

[0028] [ka]

[0029] The structural unit (a2) may be a structural unit (a2-1) represented by the following formula (a2-1), a structural unit (a2-2) represented by the following formula (a2-2), or a structural unit (a2-3) represented by the following formula (a2-3).

[0030] [ka]

[0031] (1.2.2) Preferred embodiment the polyether ketone polymer contains a polymer (A1) (hereinafter also referred to as a "low-polarity polymer (A1)") and a polymer (A2) (hereinafter also referred to as a "high-polarity polymer (A2)"); The sulfonic acid equivalent of the low polarity polymer (A1) is preferably higher than the sulfonic acid equivalent of the high polarity polymer (A2). This allows the porous film to have at least one through-hole.

[0032] Each of the low polarity polymer (A1) and the high polarity polymer (A2) preferably has a structural unit represented by the following formula (A).

[0033] [ka]

[0034] In formula (A), m and n represent a copolymerization ratio on a molar basis, and m / n is 0.99 / 0.01 or more and 0.01 / 0.99 or less. m is represented by the following formula (iv). n is represented by the following formula (v). Formula (iv): m(mol%)=(m / (m+n))×100 Formula (v) :n(mol%)=(n / (m+n))×100

[0035] The polymer (A1) (i.e., the low-polarity polymer (A1)) preferably has a sulfonic acid equivalent of 500 g / mol to 5,000 g / mol, and the polymer (A2) (i.e., the high-polarity polymer (A2)) preferably has a sulfonic acid equivalent of 300 g / mol to 3,000 g / mol, thereby enabling the membrane to maintain its shape and to be porous with at least one through-hole. The sulfonic acid equivalent of the low polarity polymer (A1) may be 700 g / mol to 4000 g / mol, or 800 g / mol to 3000 g / mol. The sulfonic acid equivalent of the highly polar polymer (A2) may be 150 g / mol to 2000 g / mol, or may be 200 g / mol to 1500 g / mol.

[0036] (1.2.2.1) Low polar polymer (A1) In the formula (A) of the polymer (A1) (i.e., the low-polarity polymer (A1)), m is preferably 80 mol % to 60 mol % and n is preferably 20 mol % to 40 mol %, which allows the membrane to maintain its shape and to be porous with at least one through-hole. The m of the low polarity polymer (A1) may be 80 mol % to 60 mol %, or may be 75 mol % to 70 mol %. The n of the low polarity polymer (A1) may be 20 mol % to 40 mol %, or may be 25 mol % to 30 mol %.

[0037] From the viewpoint of forming a matrix of a porous membrane, the weight average molecular weight Mw of the low polarity polymer (A1) is preferably 70,000 to 300,000, more preferably 100,000 to 250,000, and even more preferably 110,000 to 200,000. The method for measuring the weight average molecular weight Mw is the same as that described in the Examples.

[0038] From the viewpoint of forming a matrix for a porous membrane, the softening temperature of the low-polarity polymer (A1) is preferably 60° C. to 200° C., more preferably 80° C. to 190° C., and even more preferably 100° C. to 180° C. The softening temperature can be measured by the same method as described in the Examples.

[0039] The blend ratio of the low-polarity polymer (A1) is not particularly limited, and from the viewpoint of forming a matrix of the porous membrane, the blend ratio of the low-polarity polymer (A1) is preferably 50% by mass or more, more preferably 50% by mass to 80% by mass, and even more preferably 60% by mass to 70% by mass, based on the total amount of the low-polarity polymer (A1) and the high-polarity polymer (A2).

[0040] (1.2.2.2) Highly polar polymer (A2) In the formula (A) of the polymer (A2) (i.e., the highly polar polymer (A2)), m is preferably 20 mol % to 50 mol % and n is preferably 50 mol % to 80 mol %, which allows the membrane to maintain its shape and to be porous with at least one through-hole. The content m of the highly polar polymer (A2) may be 20 mol % to 50 mol %, or may be 30 mol % to 40 mol %. The content n of the highly polar polymer (A2) may be 50 mol % to 80 mol %, or may be 60 mol % to 70 mol %.

[0041] From the viewpoint of forming through-holes by the non-solvent induced phase separation method (hereinafter also referred to as the "NIPS method") described later, the weight average molecular weight Mw of the highly polar polymer (A2) is preferably 100 to 100,000, more preferably 1,000 to 70,000, and even more preferably 2,000 to 60,000. The method for measuring the weight average molecular weight Mw is the same as that described in the Examples.

[0042] From the viewpoint of sufficient film strength, the softening temperature of the highly polar polymer (A2) is preferably 80° C. to 250° C., more preferably 100° C. to 220° C., and even more preferably 120° C. to 190° C. The softening temperature can be measured by the same method as described in the examples.

[0043] The blend ratio of the high-polarity polymer (A2) is not particularly limited, and from the viewpoint of forming through-holes by the NIPS method, the blend ratio of the high-polarity polymer (A2) is preferably less than 50% by mass, more preferably 20% to 50% by mass, and even more preferably 30% to 40% by mass, based on the total amount of the low-polarity polymer (A1) and the high-polarity polymer (A2).

[0044] (1.3) Purpose The use of the porous membrane is not particularly limited. The porous membrane is suitably used as a filtration membrane required for specific applications. Examples of specific applications include the production of drugs in the pharmaceutical industry, the production of alcoholic beverages (e.g., beer) in the food industry, fine processing in the electronics industry, the production of purified water, and wastewater treatment (membrane separation activated sludge method).

[0045] The porous membrane is preferably used to capture microorganisms, such as yeasts, bacteria, or molds.

[0046] (2) Manufacturing method of porous membrane The method for producing a porous membrane of the present disclosure is a method for producing a porous membrane of the present disclosure. The method includes preparing a solution (hereinafter also referred to as a "polymer solution") containing the polymer (A1) (i.e., the low-polarity polymer (A1)), the polymer (A2) (i.e., the high-polarity polymer (A2)), and an organic solvent (hereinafter also referred to as a "polymer solution") (hereinafter also referred to as a "preparation step"); and forming a coated membrane using the solution (i.e., the polymer solution), and immersing the coated membrane in water or a poor solvent for the polymers (A1) and (A2) (non-solvent-induced phase separation method), or exposing the coated membrane to a water vapor atmosphere or a gas atmosphere of the poor solvent, thereby forming the porous membrane (hereinafter also referred to as a "membrane formation step"). The preparation step and membrane formation step are performed in this order.

[0047] The "NIPS method" refers to a membrane-making method in which a homogeneous polymer solution is formed into a membrane, the resulting membrane is brought into contact with a non-solvent, and phase separation is induced by the incorporation of the non-solvent, thereby forming a porous membrane.

[0048] The method for producing a porous membrane according to the present disclosure has the above-described configuration, and therefore can produce a porous membrane in which protein adsorption is suppressed.

[0049] (2.1) Preparation process In the preparation step, a polymer solution containing a low-polarity polymer (A1), a high-polarity polymer (A2), and an organic solvent is prepared.

[0050] The method for preparing the polymer solution is not particularly limited and may be a known method. For example, the polymer solution may be prepared by dissolving a low-polarity polymer (A1) in an organic solvent to prepare a first varnish, dissolving a high-polarity polymer (A2) in an organic solvent to prepare a second varnish, and mixing the first varnish and the second varnish.

[0051] Examples of the low-polarity polymer (A1) include the same low-polarity polymer (A1) as exemplified as a preferred embodiment of the porous membrane. Examples of the high-polarity polymer (A2) include the same high-polarity polymer (A2) as exemplified as a preferred embodiment of the porous membrane. The methods for preparing the low-polarity polymer (A1) and the high-polarity solvent (B) are not particularly limited and may be known methods (e.g., methods described in Patent Document 1 and WO 2003 / 33566).

[0052] The organic solvent is not particularly limited as long as it dissolves the low-polarity polymer (A1) and the high-polarity polymer (A2). Examples of the organic solvent include nitrogen-containing polar solvents (e.g., N,N-dimethylformamide, N-methylpyrrolidone, or N,N-dimethylacetamide), ethers (e.g., methyl cellosolve, methyl cellosolve acetate, or diethylene glycol dimethyl ether), sulfur-containing polar solvents (e.g., dimethyl sulfoxide), fatty acid esters (e.g., ethyl lactate or butyl lactate), lactone-based polar solvents (e.g., β-propiolactone, γ-butyrolactone, or γ-valerolactone), and phenol-based solvents (e.g., cresols). One organic solvent may be used alone, or two or more organic solvents may be used in combination. The blending ratio of the organic solvents is not particularly limited and may be appropriately selected depending on the fluidity of the polymer solution. The method for preparing the organic solvent is not particularly limited and may be a known method.

[0053] (2.2) Film forming process In the film-forming step, a polymer solution is used to prepare a coated film using the solution (i.e., polymer solution), and the porous film is formed by immersing the coated film in water or a poor solvent for the polymer (A1) and the polymer (A2) (non-solvent induced phase separation method), or by exposing the coated film to a water vapor atmosphere or a gas atmosphere of the poor solvent.

[0054] Hereinafter, "water or a poor solvent" may also be referred to as "non-solvent." A "water vapor atmosphere or a gas atmosphere of the poor solvent" may also be referred to as "non-solvent atmosphere."

[0055] The method for applying the polymer solution is not particularly limited and may be a known method. The dry film thickness of the porous film can be adjusted by adjusting the amount of the polymer solution applied.

[0056] The method for immersing the coating film in the non-solvent may be any known method. For example, a substrate-attached coating film may be immersed in the non-solvent. The substrate-attached coating film comprises a substrate and a coating film formed on the substrate. The time for immersing the coating film in the non-solvent is not particularly limited, and is preferably 0.1 to 60 minutes, more preferably 1 to 10 minutes, from the viewpoint of adjusting the mean flow pore size of the porous film to a value suitable for the intended use. Examples of poor solvents for the polymer (A1) and the polymer (A2) include alcohols (e.g., methanol, ethanol, etc.), aldehydes (e.g., acetone, etc.), and carboxylic acids (e.g., acetic acid, etc.).

[0057] The method for exposing the coating film to a non-solvent atmosphere is not particularly limited, and any known method may be used.

[0058] The coating film after immersion in the non-solvent or after exposure to the non-solvent atmosphere may be dried. The drying method is not particularly limited and may be a known method.

[0059] Before drying the coated film after immersion in the non-solvent, the coated film after immersion in the non-solvent may be exposed to a non-solvent atmosphere. This allows the mean flow pore size of the porous film to be adjusted. When the non-solvent is water, the temperature of the non-solvent atmosphere (hereinafter also referred to as a "high humidity atmosphere") may be 10°C to 90°C, and the relative humidity of the high humidity atmosphere may be 50%RH to 90%RH. The time for exposing the coated film to the high humidity atmosphere after contact may be 0.1 minutes to 60 minutes. [Example]

[0060] The present disclosure will be explained in more detail below based on examples, but the present disclosure is not limited to these examples in any way.

[0061] [1] Abbreviation The abbreviations used in the present examples and comparative examples are as follows:

[0062] [1.1] Solvent DMSO: dimethyl sulfoxide DMF: N,N-dimethylformamide NMP: N-methylpyrrolidone MC: Methyl cellosolve

[0063] [1.2] Aromatic polyether components DFBP: 4,4'-difluorobenzophenone DSDFBP: 5,5'-carbonylbis(sodium 2-fluorobenzenesulfonate)

[0064] DSDFBP is represented by the following formula (X).

[0065] [ka]

[0066] [2]Measurement method [2.1] Pores Scanning electron microscope (SEM) photographs of the surface and cross section of the porous membrane were taken in the usual manner using an electron microscope (JEOL Ltd., "JSM-6380") The presence or absence of through-holes in the porous membrane was observed using the SEM photographs.

[0067] [2.2] Average flow pore diameter The mean flow pore size of the porous membrane was calculated by the bubble point method using a perm porometer ("PMI Perm Porometer" manufactured by Porous Materials, Inc.). Specifically, the porous membrane was cut into a 5 cm x 5 cm size to obtain a measurement sample. The lid of the measurement chamber was removed, and the measurement sample was placed in the measurement chamber. The lid of the measurement chamber was then attached to the measurement chamber. This set the measurement sample in the measurement chamber. The measurement sample was then subjected to bubble point measurement under dry conditions. After the measurement was completed, the measurement sample was removed and immersed in a humidity-controlling solvent to moisten the measurement sample. This was then set in the measurement chamber again, and the measurement sample was subjected to bubble point measurement under wet conditions. The mean flow pore diameter of the measurement sample was calculated from a correlation graph between the measured gas permeability and the measured gas pressure under dry and wet conditions. This calculated value was designated as the "mean flow pore diameter of the porous membrane."

[0068] [2.3] Dry film thickness The dry film thickness was measured using a contact-type film thickness measuring device (F20 thin-film analyzer manufactured by FILMETRICS.inc.) in a constant temperature and humidity environment of 25°C and 55%RH. The center, left, and right of the porous film were measured, and the average of the three points was calculated.

[0069] [2.4] Sulfonic acid equivalent Sulfonic acid equivalent weight (EW: weight per mole of sulfonic acid group [g / mol]) Approximately 50 mg of porous membrane (approximately 100-300 μm thick) was taken, crushed, and dried under reduced pressure at 100°C for 2 hours. It was then weighed and placed in a sealed container. An excess amount of sodium chloride solution was added and the container was left overnight. The generated hydrogen chloride was titrated with 0.01 N sodium hydroxide standard solution using phenolphthalein indicator to calculate the EW. The sulfonic acid equivalent was simply calculated by weighing the polymer and using the following formula: Sulfonic acid equivalent of polymer (g / mol) = Weight of polymer (g) / Amount of sulfonic acid groups in polymer (mol)

[0070] [2.5] Weight average molecular weight (Mw) The weight average molecular weight (Mw) was measured by gel permeation chromatography (GPC). Specifically, a sample solution was prepared by dissolving polymer powder of polymer (A1) or polymer powder of polymer (A2) in DMF (concentration: 100 mg / ml). This was sent to a GPC column set at a column temperature of 40°C, and the GPC chart was measured using a detector. The flow rate of the sample solution was 1.0 ml / min. The weight average molecular weight (Mw) of polymer (A1) was measured using a calibration curve (integral molecular weight distribution curve). The weight average molecular weight (Mw) of polymer (A2) was measured in the same manner as for the weight average molecular weight (Mw) of polymer (A1). The following apparatus was used to measure the weight average molecular weight (Mw).

[0071] ·Device name: Shodex GPC-101 Manufacturer: Shoko Science Co., Ltd. Columns: Shodex GPC "KD-802.5" (1 tube), Shodex GPC "KD-806M" (2 tubes), Shodex GPC "KD-806M" (1 tube) ·Mobile phase: 10mM LiBr / DM Instrument calibration: Monodisperse polystyrene (Shoko Science Co., Ltd.)

[0072] [2.6] Softening point temperature The porous membrane was cut into 5 mm x 5 mm pieces to obtain test samples. Using a thermal analyzer (TA Instruments Japan, Inc., "TMA Q400"), a load of 0.4905 N was applied to the test sample, and the temperature was raised at a rate of 5°C per minute from 20°C to 300°C. The softening point of the test sample was measured based on the change in thermal elongation.

[0073] [2.7] Protein adsorption test The porous membrane was cut into a size of 25 mm in diameter to obtain a measurement sample. A BSA (bovine serum albumin) aqueous solution (BSA concentration: 1000 ppm) was passed through this measurement sample. "BSA concentration" indicates the ratio (mass %) of the mass of BSA to the total amount of the BSA aqueous solution. Then, a phosphate buffer solution was passed through. After passing the solution, the measurement sample was vacuum dried at room temperature. After drying, the solution was passed through an aqueous sodium dodecyl sulfate solution, and the BSA adsorbed on the measurement sample was recovered. The BSA concentration in the recovered solution was measured. The measured BSA concentration was used as the "protein adsorption capacity (μg / cm 2 )"

[0074] [3] Preparation [3.1]Low polar polymer (A1-1) A five-neck reactor equipped with a nitrogen inlet tube, thermometer, reflux condenser, and stirrer was prepared. Raw material (A1-1) was weighed into the five-neck reactor. Raw material (A1-1) consisted of 40.1 g (0.095 mol) of DSDFBP, 62.2 g (0.285 mol) of DFBP, 97.4 g (0.380 mol) of TMBPF, and 65.7 g (0.475 mol) of potassium carbonate. DSDFBP was obtained by the method described in Synthesis Example 1 of JP 2014-533 A. Solvent (A1-1) was added to raw material (A1-1), stirred under a nitrogen atmosphere, and heated at 130°C for 12 hours. The resulting water was removed from the system, and the toluene was then distilled off. Solvent (A1-1) consisted of 783.4 g of DMSO and 261.1 g of toluene.

[0075] The reaction was continued at 160°C for 12 hours to obtain a viscous polymer solution. The obtained polymer solution was diluted with 570g of toluene and then poured into 2400g of methanol. The precipitated polymer powder was filtered, washed, and then dried at 150°C for 4 hours. This yielded 171.6g (yield 95%) of a polyether ketone polymer powder (low polarity polymer (A1-1)).

[0076] The low-polarity polymer (A1-1) had a structural unit (a1-1) (sulfonic acid unit) represented by the following formula (a1-1) and a structural unit (a2-1) (sulfonic acid unit) represented by the following formula (a2-1). The copolymerization ratio (n) of the structural unit (a1-1) in all structural units of the low-polarity polymer (A1-1) was 25 mol%. The copolymerization ratio (m) of the structural unit (a2-1) in all structural units of the low-polarity polymer (A1-1) was 75 mol%. The low-polarity polymer (A1-1) contained a sulfonate salt. The weight-average molecular weight (Mw) and softening temperature of the low-polarity polymer (A1-1) are shown in Table 1.

[0077] [ka]

[0078] [ka]

[0079] [3.2] Highly polar polymer (A2-1) A polyether ketone polymer powder (high polarity polymer (A2)) weighing 88.7 g (yield 40%) was obtained in the same manner as for the low polarity polymer (A1-1), except that the resin raw material (A1-1) was changed to the following raw material (A2-1) and the solvent (A1-1) was changed to the following solvent (A2-1). The raw material (A2-1) consisted of 96.3 g (0.228 mol) of DSDFBP, 33.2 g (0.152 mol) of DFBP, 107.1 g (0.418 mol) of TMBPF, and 72.2 g (0.522 mol) of potassium carbonate. The solvent (A2-1) consisted of 946.4 g of DMSO and 365.53 g of toluene.

[0080] The highly polar polymer (A2-1) had the structural unit (a1-1) (i.e., sulfonic acid unit) and the structural unit (a2-1) (i.e., sulfonic acid unit). The copolymerization ratio (n) of the structural unit (a1-1) in all structural units of the highly polar polymer (A2-1) was 40 mol%. The copolymerization ratio (m) of the structural unit (a2-1) in all structural units of the highly polar polymer (A2-1) was 60 mol%. The highly polar polymer (A2-1) contained a sulfonate salt. The weight average molecular weight (Mw) and softening temperature of the highly polar polymer (A2-1) are shown in Table 1.

[0081] [3.3] Highly polar polymer (A2-2) A polyether ketone powder (high polarity polymer (A2-2)) of 173.6 g (yield 82%) was obtained in the same manner as for the low polarity polymer (A1-1), except that the resin raw material (A1-1) was changed to the following raw material (A2-2) and the solvent (A1-1) was changed to the following solvent (A2-2). The raw material (A2-2) consisted of 96.3 g (0.228 mol) of DSDFBP, 33.2 g (0.152 mol) of DFBP, 97.4 g (0.380 mol) of TMBPF, and 65.7 g (0.475 mol) of potassium carbonate. The solvent (A2-2) consisted of 907.5 g of DMSO and 302.5 g of toluene.

[0082] The highly polar polymer (A2-2) had the structural unit (a1-1) (i.e., sulfonic acid unit) and the structural unit (a2-1) (i.e., sulfonic acid unit). The copolymerization ratio (n) of the structural unit (a1-1) in all structural units of the highly polar polymer (A2-2) was 40 mol%. The copolymerization ratio (m) of the structural unit (a2-1) in all structural units of the highly polar polymer (A2-2) was 60 mol%. The highly polar polymer (A2-2) contained a sulfonate salt. The weight average molecular weight (Mw) and softening temperature of the highly polar polymer (A2-2) are shown in Table 1.

[0083] [4] Examples and Comparative Examples [4.1] Example 1 A low-polarity polymer (A1-1) was dissolved in NMP to prepare a varnish (A1-1) with a solids content of 15%. Subsequently, a high-polarity polymer (A2-1) was dissolved in a mixed solvent of NMP and MC to prepare a varnish (A2-1) with a solids content of 30%. The varnishes (A1-1) and (A2-1) were mixed so that the mass ratio of the low-polarity polymer (A1-1) to the high-polarity polymer (A2-1) (low-polarity polymer (A1-1):high-polarity polymer (A2-1)) was 70:30, thereby preparing a coating varnish.

[0084] In the GPC chart of the coating varnish, peak top 1 and peak top 2 were confirmed. The logarithm of the molecular weight (logM) of peak top 1 was 6.1. That is, the weight average molecular weight Mw of peak top 1 was 130,000. The logarithm of the molecular weight (logM) of peak top 2 was 6.15. That is, the weight average molecular weight Mw of peak top 2 was 150,000.

[0085] A general coating applicator with a micrometer was placed on a glass substrate. The distance between the glass substrate and the applicator (hereinafter also referred to as "applicator distance") was set to 200 mm using the micrometer. Coating varnish was dropped onto the glass substrate, and the coating varnish was applied to the glass substrate at a speed of 5 m / min using the micrometer-equipped applicator. This formed a coating film on the glass substrate.

[0086] Next, the coated film with the glass substrate was immersed in water for 5 minutes, and the film peeled off from the glass substrate was scooped out. After washing the film several times with water, it was placed in a constant temperature and humidity atmosphere (25°C, 55% RH) and dried overnight. This resulted in a porous film. Observation of the SEM photograph of the porous film revealed that the porous film of Example 1 had multiple through-holes. Two peaks were observed in the GPC chart of the coating varnish of Example 1. The larger of the two peaks in the GPC chart of the resulting varnish had a log M of 5.1, confirming a weight average molecular weight M of 130,000.

[0087] [4.2] Example 2 A porous membrane was obtained in the same manner as in Example 1, except that the mass ratio (low polarity polymer (A1-1):high polarity polymer (A2-1)) was changed to 63:37. Observation of the SEM photograph of the porous membrane revealed that the porous membrane of Example 2 had a plurality of through-holes.

[0088] Two peaks were observed in the GPC chart of the coating varnish of Example 2. The larger of the two peaks in the GPC chart of the resulting varnish had a log M of 5.1, confirming a weight average molecular weight M of 130,000.

[0089] [4.3] Example 3 A porous membrane was obtained in the same manner as in Example 2, except that the applicator interval was changed to 600 mm. As a result of observing the SEM photograph of the porous membrane, it was found that the porous membrane of Example 3 had a plurality of through-holes.

[0090] In the GPC chart of the coating varnish of Example 3, peak top 1 and peak top 2 were confirmed. In the GPC chart of the coating varnish, two peak tops were confirmed. In the GPC chart of the obtained varnish, the larger of the two peak tops had log M = 5.1. In other words, the weight average molecular weight Mw = 130,000 was confirmed.

[0091] [4.4] Example 4 A porous membrane was obtained in the same manner as in Example 1, except that the mass ratio (low polarity polymer (A1-1):high polarity polymer (A2-1)) was changed to 60:40 and the applicator interval was changed to 600 mm. Observation of the SEM photograph of the porous membrane revealed that the porous membrane of Example 4 had a plurality of through-holes.

[0092] In the GPC chart of the coating varnish of Example 4, peak top 1 and peak top 2 were confirmed. In the GPC chart of the coating varnish, two peak tops were confirmed. In the GPC chart of the obtained varnish, the larger of the two peak tops had log M = 5.1. In other words, the weight average molecular weight Mw = 130,000 was confirmed.

[0093] [4.5] Example 5 A porous membrane was obtained in the same manner as in Example 1, except that the mass ratio (low polarity polymer (A1-1):high polarity polymer (A2-1)) was changed to 55:45 and the applicator interval was changed to 600 mm. Observation of the SEM photograph of the porous membrane revealed that the porous membrane of Example 5 had a plurality of through-holes.

[0094] In the GPC chart of the coating varnish of Example 5, peak top 1 and peak top 2 were confirmed. In the GPC chart of the coating varnish, two peak tops were confirmed. In the GPC chart of the obtained varnish, the larger of the two peak tops had log M = 5.1. In other words, the weight average molecular weight Mw = 130,000 was confirmed.

[0095] [4.6] Example 6 A porous film was obtained in the same manner as in Example 2, except that the applicator interval was changed to 600 mm and the coated film with the glass substrate was allowed to stand in a booth (ambient temperature: 25°C, relative humidity: 95% RH) for 1 hour before being immersed in water. Observation of SEM photographs of the porous film revealed that the porous film of Example 6 had multiple through-holes.

[0096] In the GPC chart of the coating varnish of Example 6, peak top 1 and peak top 2 were confirmed. In the GPC chart of the coating varnish, two peak tops were confirmed. In the GPC chart of the obtained varnish, the larger of the two peak tops had log M = 5.1. In other words, the weight average molecular weight Mw = 130,000 was confirmed.

[0097] [4.7] Comparative Example 1 A porous membrane was obtained in the same manner as in Example 1, except that the low-polarity polymer (A1-1) was dissolved in NMP, and then the varnish with a solid content of 18% was used as the coating varnish without mixing with the high-polarity polymer (A2-1). As a result of observing the SEM photograph of the porous membrane, it was found that the porous membrane of Comparative Example 1 did not have through-holes.

[0098] Only one peak top was confirmed in the GPC chart of the coating varnish of Comparative Example 1. The logarithm of the molecular weight (logM) at the peak top was 5.1. That is, the weight average molecular weight Mw at peak top 1 was 130,000.

[0099] [4.8] Comparative Example 2 A porous membrane was obtained in the same manner as in Example 1, except that the following high-polarity polymer (A2-2) was dissolved in NMP, and then a varnish with a solid content of 18% was used as the coating varnish without mixing with the low-polarity polymer (A1-1). As a result of observing the SEM photograph of the porous membrane, it was found that the porous membrane of Comparative Example 2 had no through-holes.

[0100] In the GPC chart of the coating varnish of Comparative Example 2, peak top 1 was confirmed. Only one peak top was confirmed. The logarithm of the molecular weight (logM) at the peak top was 5.2. That is, the weight average molecular weight Mw at peak top 1 was 160,000.

[0101] [Table 1]

[0102] The porous membranes of Comparative Examples 1 and 2 did not have through-holes. Therefore, the protein adsorption performance of Comparative Examples 1 and 2 was 10 μg / cm 2 As a result, it was found that the porous membranes of Comparative Examples 1 and 2 were not "porous membranes with reduced protein adsorption."

[0103] The porous membranes of Examples 1 to 6 contained a low-polarity polymer (A1) and a high-polarity polymer (A2). The porous membranes of Examples 1 to 6 had a plurality of through-holes. Therefore, the protein adsorption capacity of Examples 1 to 6 was 10 μg / cm 2 As a result, it was found that the porous membranes of Examples 1 to 6 were "porous membranes with reduced protein adsorption."

[0104] The porous membranes of Examples 1 to 6 had pore structures with mean flow pore diameters of 8.3 μm or less, as shown in Table 1. On the other hand, the porous membranes of Comparative Examples 1 and 2 did not have pore structures.

[0105] As shown in Table 1, the porous membranes of Examples 1 to 6 have less protein adhesion than those of Comparative Examples 1 and 2. Therefore, when the porous membranes of Examples 1 to 6 are used as filters for activated sludge phases, they have high fouling resistance.

Claims

1. Contains at least two types of polyetherketone polymers, the polyether ketone polymer contains a sulfonic acid group or a salt thereof, A porous membrane having at least one through hole.

2. 10. The porous membrane of claim 1, wherein the mean flow pore size is from 0.1 μm to 10.0 μm.

3. 3. The porous membrane of claim 2, wherein the mean flow pore size is from 0.5 μm to 1.7 μm.

4. The dry film thickness is 50 μm to 300 μm, 3. The porous membrane of claim 2, wherein the mean flow pore size is from 0.4 μm to 1.3 μm.

5. It has at least two peak tops in a GPC chart obtained by gel permeation chromatography (GPC) measurement, The porous membrane according to claim 1, wherein the logarithm (log M) of the molecular weight at the peak top is 3 or more.

6. 2. The porous membrane of claim 1, wherein the sulfonic acid equivalent weight is from 100 g / mol to 5000 g / mol.

7. The porous membrane according to claim 1, wherein the polyether ketone polymer has a structural unit represented by the following formula (a1) or a structural unit represented by the following formula (a2): 【Chemical 1】 [In formula (a1) and formula (a2), R １ ~R １０ are each independently H, Cl, F, or CF ３ or C ｍ H ２ｍ＋１ (m represents an integer of 1 to 10). １ ~R １０ may be present in two or more aromatic rings. ｍ H ２ｍ＋１ If there are two or more C ｍ H ２ｍ＋１ may be the same or different. １ ~A ６ are each independently a direct bond, —CH ２ -, -C(CH ３ ) ２ -, -C(CF ３ ) ２ -, -O- or -CO-. １ ~A ３ At least one of X is —CO—. １ ~X ５ are each independently H, Cl, F, or CF ３ , a sulfonic acid group or a salt of a sulfonic acid group, and X １ ~X ５ At least one of X is a sulfonic acid group or a salt of a sulfonic acid group. １ ~X ５ may be present in two or more in an aromatic ring, and when two or more sulfonic acid groups are present in one aromatic ring, the respective sulfonic acid groups may be the same or different. i, j, k, and l each independently represent 0 or 1.]

8. the polyether ketone polymer contains a polymer (A1) and a polymer (A2), The porous membrane according to claim 7, wherein the sulfonic acid equivalent of the polymer (A1) is higher than the sulfonic acid equivalent of the polymer (A2).

9. The porous membrane of claim 1 for use in capturing microorganisms.

10. 9. A method for producing the porous membrane of claim 8, comprising: preparing a solution containing the polymer (A1), the polymer (A2), and an organic solvent; forming a coating film using the solution, and immersing the coating film in water or a poor solvent for the polymer (A1) and the polymer (A2) (non-solvent induced phase separation method), or exposing the coating film to a water vapor atmosphere or a gas atmosphere of the poor solvent, thereby forming the porous film.

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