JP2020146652A - Concentration membrane - Google Patents

Abstract

To provide a concentration membrane that concentrates biological particles simply, quickly and efficiently.SOLUTION: A concentrating membrane, used for concentrating biological particles, comprises a hydrophilic composite porous membrane that comprises a porous base material and a hydrophilic resin that coats at least one main surface and the inner pore surfaces of the porous base material, the hydrophilic composite porous membrane being such that the ratio t/x of the membrane thickness t (μm) and the average pore size x (μm) measured by palm porometer is 50-630.SELECTED DRAWING: None

Description

The present invention relates to a thickening membrane used to concentrate biological particles.

Patent Document 1 discloses that a bundle of polyethylene porous hollow fiber membranes coated with an ethylene / vinyl alcohol copolymer on the surface is used for capturing microorganisms.
Patent Document 2 discloses that a filter membrane having a bubble point pore size not exceeding 1.0 μm is used for capturing microorganisms.
Patent Document 3 discloses a method for producing a hydrophilic polymer microporous membrane in which a hydrophilic monomer is subjected to a radiation graft reaction on the surface of the polymer microporous membrane made of a hydrophobic resin.
Patent Document 4 describes a hydrophilic microporous film obtained by copolymerizing a hydrophilic monomer having one vinyl group and a cross-linking agent having two or more vinyl groups by a graft polymerization method. The membrane is disclosed.
Patent Document 5 discloses that a porous hollow fiber membrane in which a polyolefin porous hollow fiber substrate is coated with a glycerin fatty acid ester is used as a membrane for concentrating and separating bacterial cells.
Patent Document 6 contains at least one crystalline component composed of a polyethylene resin having a viscosity average molecular weight of more than 1 million and a melting peak temperature of 145 ° C. or higher, a porosity of 20 to 95%, and an average pore size of 0. A microporous membrane of 0.01 to 10 μm is disclosed.
Patent Document 7 is made of a polyethylene resin, thickness 1mm exceed 25μm or less, an average pore diameter of 0.01 to 10 [mu] m, the structure factor F is 1.5 × 10 ⁷ seconds ^-2 · ^m -1 · ^{Pa -2} A medical separation filter containing the above-mentioned highly permeable microporous membrane is disclosed.
Patent Document 8 discloses a method for removing aggregates present in a fluid containing a biological product through a membrane filter pretreated with a surfactant.
Patent Document 9 discloses a method of capturing and recovering oral microorganisms in a test solution on a filtration membrane.
Patent Document 10 discloses a hydrophilic composite porous membrane composed of a porous structural matrix made of polyolefin and an ethylene-vinyl alcohol-based copolymer coating layer that coats the pore surface of the matrix.

Japanese Unexamined Patent Publication No. 11-090184 Japanese Patent Application Laid-Open No. 2013-531236 JP-A-2009-183804 Japanese Unexamined Patent Publication No. 2003-268152 Special Fairness 06-057143 Japanese Unexamined Patent Publication No. 2004-016930 JP-A-2002-265658 Special Table 2016-534748 Japanese Unexamined Patent Publication No. 2006-71478 JP-A-61-271003

For example, for the purpose of diagnosing an infectious disease, a virus or a bacterium may be isolated from a sample collected from an organism. Centrifugal method is one of the methods for separating viruses or bacteria. In the centrifugal method, the centrifugal force is changed to repeat the centrifugal operation, the sample is placed on a buffer solution having a density gradient and centrifuged, or ultracentrifugation is performed. It is a method that requires equipment, labor, and time. Another method for separating viruses or bacteria is to use a porous membrane, but the conventional method is only for the purpose of completely removing the virus etc. from the filtrate, or the virus etc. is made into a membrane. It is a complicated method of adsorbing and taking out viruses and the like by backwashing, and the viewpoint of efficiently concentrating and recovering viruses and the like in a sample has been lacking.

The embodiments of the present disclosure have been made under the above circumstances.
An object of the present disclosure embodiment is to provide a concentrated film for easily, quickly and efficiently concentrating biological particles, and it is an object of the present invention to solve this.

Specific means for solving the above problems include the following aspects.

[1] A hydrophilic composite porous membrane comprising a porous base material and a hydrophilic resin that covers at least one main surface of the porous base material and the inner surface of pores, and has a thickness t ( A concentrated membrane used for concentrating biological particles, comprising a hydrophilic composite porous membrane having a ratio t / x of μm) to an average pore size x (μm) measured with a palm poromometer of 50 to 630.
[2] The concentrated membrane according to [1], wherein the hydrophilic composite porous membrane has an average pore diameter x of 0.1 μm to 0.5 μm.
[3] The concentrated membrane according to [1] or [2], wherein the hydrophilic composite porous membrane has a bubble point pore diameter y measured by a palm poromometer of more than 0.8 μm and 3 μm or less.
[4] The hydrophilic composite porous membrane has a ratio f / y of the water flow rate f (mL / (min · cm ² · MPa)) to the bubble point pore diameter y (μm) of 100 to 480. The concentrated film according to any one of [1] to [3].
[5] The concentrated film according to any one of [1] to [4], wherein the hydrophilic composite porous film has a film thickness t of 10 μm to 150 μm.
[6] The concentrated film according to any one of [1] to [5], wherein the hydrophilic composite porous film has a surface roughness Ra of 0.3 μm to 0.7 μm.
[7] The hydrophilic resin contains a hydrophilic resin in which the main chain of the polymer consists only of carbon atoms and the side chain has at least one functional group selected from the group consisting of a hydroxy group, a carboxy group and a sulfo group. , [1] to [6].
[8] The hydrophilic resin is polyvinyl alcohol, olefin / vinyl alcohol resin, acrylic / vinyl alcohol resin, methacryl / vinyl alcohol resin, vinyl pyrrolidone / vinyl alcohol resin, polyacrylic acid, polymethacrylic acid, par. The concentrated film according to any one of [1] to [6], which contains at least one hydrophilic resin selected from the group consisting of fluorosulfonic acid-based resins and polystyrene sulfonic acids.
[9] The concentrated film according to any one of [1] to [6], wherein the hydrophilic resin contains an olefin / vinyl alcohol-based resin.
[10] The concentrated membrane according to any one of [1] to [9], wherein the porous substrate is a polyolefin microporous membrane.
[11] The concentrated membrane according to any one of [1] to [10], wherein the biological particles have a size of 10 nm to 1000 nm.
[12] The concentrated membrane according to any one of [1] to [11], wherein the biological particle is a virus, a bacterium or an exosome.

According to the embodiments of the present disclosure, there is provided a concentrated membrane that easily, quickly and efficiently concentrates biological particles.

It is a schematic diagram which showed the instrument and operation of a concentration test.

Embodiments of the invention will be described below. These descriptions and examples exemplify embodiments and do not limit the scope of the invention. The mechanism of action described in the present disclosure includes presumption, and its correctness does not limit the scope of the invention.

When the embodiment is described in the present disclosure with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Further, the size of the members in each figure is conceptual, and the relative relationship between the sizes of the members is not limited to this.

The numerical range indicated by using "-" in the present disclosure indicates a range including the numerical values before and after "-" as the lower limit value and the upper limit value, respectively.

In the numerical range described stepwise in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of another numerical range described stepwise. .. Further, in the numerical range described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

In the present disclosure, the term "process" is included in this term not only as an independent process but also as long as the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes.

In the present disclosure, each component may contain a plurality of applicable substances. When referring to the amount of each component in the composition in the present disclosure, if a plurality of substances corresponding to each component are present in the composition, unless otherwise specified, the plurality of types present in the composition. It means the total amount of substances.

In the present disclosure, "(meth) acrylic" means at least one of acrylic and methacrylic, and "(meth) acrylate" means at least one of acrylate and methacrylate.

In the present disclosure, the "monomer unit" means a component of a polymer, which is a component obtained by polymerizing a monomer.

In the present disclosure, the "mechanical direction" means the long direction in a film, film or sheet manufactured in a long shape, and the "width direction" means a direction orthogonal to the "mechanical direction". In the present disclosure, the "machine direction" is also referred to as the "MD direction", and the "width direction" is also referred to as the "TD direction".

In the present disclosure, the "main surface" of a film, film or sheet means a wide outer surface other than the outer surface extending in the thickness direction among the outer surfaces of the film, film or sheet. The film, film or sheet has two main surfaces. In the present disclosure, the "side surface" of the film, film or sheet means the outer surface of the film, film or sheet that extends in the thickness direction.

In the present disclosure, the side where the liquid composition flows in is referred to as "upstream" and the side where the liquid composition flows out is referred to as "downstream" with respect to the concentrated membrane or the hydrophilic composite porous membrane.

<Concentrated membrane>
The present disclosure provides a thickening membrane used to concentrate biological particles. The concentrated membrane of the present disclosure is an aqueous composition in which a liquid composition containing water (hereinafter referred to as an aqueous liquid composition), which may contain biological particles, is treated, and the concentration of biological particles is increased. Concentrate into a liquid composition.

The biological particles referred to in the present disclosure include particles possessed by living organisms, particles emitted by living organisms, particles parasitizing living organisms, minute organisms, vesicles having a lipid as a membrane, and fragments thereof. .. The biological particles referred to in the present disclosure include viruses, parts of viruses (for example, enveloped viruses deenveloped), bacteriophages, bacteria, spores, spores, fungi, molds, yeasts, cysts, and protozoa. Animals, unicellular algae, plant cells, animal cells, cultured cells, hybridomas, tumor cells, blood cells, platelets, organelles (eg cell nuclei, mitochondria, vesicles), exosomes, apoptotic bodies, lipid bilayer particles , Lipid bilayer particles, liposomes, protein aggregates, fragments of these. The biological particles referred to in the present disclosure also include artificial objects.

There is no limitation on the size of the biological particles to be concentrated by the concentrated membrane of the present disclosure. The diameter or major axis length of the biological particles is, for example, 1 nm or more, 5 nm or more, 10 nm or more, 20 nm or more, for example, 100 μm or less, 50 μm or less, 1000 nm or less. , 800 nm or less.

When the porous substrate of the hydrophilic composite porous membrane provided in the concentrated membrane of the present disclosure is a polyolefin microporous membrane (details will be described later), the biological particles to be concentrated by the concentrated membrane are nano-order. The size is appropriate. In this case, the diameter or major axis length of the biological particles is, for example, 10 nm or more and 20 nm or more, for example, 1000 nm or less, 800 nm or less, and 500 nm or less.

When the porous substrate of the hydrophilic composite porous membrane provided in the concentrated membrane of the present disclosure is a polyolefin microporous membrane, the concentrated membrane is suitable for concentrating viruses, bacteria or exosomes.

Aqueous liquid compositions that serve as samples for the concentrated membranes of the present disclosure include body fluids of animals (particularly humans) (eg, blood, serum, plasma, spinal fluid, tears, sweat, urine, pus, nasal discharge, sputum); animals. Dilutes of body fluids (especially humans); liquid compositions in which excrement (eg, feces) of animals (especially humans) are suspended in water; mouthwash of animals (especially humans); organs of animals (especially humans), Buffer solution containing extracts from tissues, mucous membranes, skin, squeezed specimens, swabs, etc .; fish and shellfish tissue extracts; water collected from fish and shellfish farming ponds; plant surface wipes or tissue extracts; soil Extracts; extracts from plants; extracts from foods; raw materials for pharmaceuticals: and the like.

The concentrated film of the present disclosure includes a hydrophilic composite porous film including a porous base material and a hydrophilic resin that covers at least one main surface of the porous base material and the inner surface of pores. The concentrated membrane of the present disclosure may include members other than the hydrophilic composite porous membrane. As a member other than the hydrophilic composite porous membrane, a sheet-like reinforcing member arranged in contact with a part or all of the main surface or side surface of the hydrophilic composite porous membrane; the concentrated membrane is mounted on the concentrating device. Guide member for the purpose; etc.

In the hydrophilic composite porous membrane provided in the concentrated membrane of the present disclosure, at least the main surface on the upstream side during the concentration treatment needs to be coated with the hydrophilic resin, and both main surfaces are coated with the hydrophilic resin. Is preferable.

The form of covering the main surface of the porous base material with the hydrophilic resin in the hydrophilic composite porous film is, for example, a form in which a part or all of the main surface of the porous base material is covered with the hydrophilic resin, or porous. A form in which a part or all of the opening of the quality substrate is filled with the hydrophilic resin, a part of the main surface of the porous substrate is covered with the hydrophilic resin, and a part of the opening is filled with the hydrophilic resin. There is a form. When the openings of the porous base material are filled with the hydrophilic resin, it is preferable that the hydrophilic resin forms a porous structure. Here, the porous structure means a structure having a large number of micropores inside and connecting these micropores so that a gas or a liquid can pass from one side to the other. ..

As a form of coating the inner surface of the pores of the porous base material with the hydrophilic resin in the hydrophilic composite porous film, for example, a part or all of the wall surface of the pores of the porous base material is covered with the hydrophilic resin. A form in which a hydrophilic resin fills a part or all of the pores of the porous base material, and a part of the pores of the porous base material covered with a hydrophilic resin. Is filled with a hydrophilic resin. When the pores of the porous base material are filled with the hydrophilic resin, it is preferable that the hydrophilic resin forms a porous structure. Here, the porous structure means a structure having a large number of micropores inside and connecting these micropores so that a gas or a liquid can pass from one side to the other. ..

Concentration of biological particles using the concentrated membranes of the present disclosure results in an aqueous liquid composition when the aqueous liquid composition is passed from one main surface of the hydrophilic composite porous membrane to the other main surface. Aqueous liquids in at least one of the upstream, upstream main surfaces and pores of the hydrophilic composite porous membrane, where some or all of the biological particles contained do not pass through the hydrophilic composite porous membrane. This is done by remaining in the composition. Comparing the aqueous liquid composition before the concentration treatment with the aqueous liquid composition recovered from at least one of the upstream and upstream main surfaces and the pores of the hydrophilic composite porous membrane after the concentration treatment. If the concentration of the biological particles contained in the latter is high, it can be said that the biological particles have been concentrated. The concentration rate of biological particles (according to the following formula) realized by the concentrated film of the present disclosure is more than 100%, preferably 200% or more, and more preferably 300% or more.
Concentration rate = "Biological particle concentration of aqueous liquid composition recovered from at least any of the upstream, upstream main surface and pores of the hydrophilic composite porous film after concentration treatment" ÷ "concentration treatment" Biological particle concentration of previous aqueous liquid composition "x 100

Although the detailed mechanism is not always clear, the hydrophilic composite porous membrane provided in the concentrated membrane of the present disclosure has a hydrophilic resin on the main surface on the upstream side and the inner surface of the pores, so that the hydrophilic composite porous membrane is hydrophilic. It is presumed that the biological particles remaining on at least one of the main surface on the upstream side of the quality membrane and the pores are easily recovered, and the concentration rate of the biological particles is improved.

The hydrophilic composite porous film included in the concentrated film of the present disclosure includes a porous base material and a hydrophilic resin that covers at least one main surface of the porous base material and the inner surface of pores, and has a thickness t ( The ratio t / x of μm) to the average pore diameter x (μm) measured by the palm porometer is 50 to 630.
If the t / x of the hydrophilic composite porous membrane is less than 50, the film thickness t is too thin for the size of the average pore size x, or the average pore size x is large for the thickness of the film thickness t. Because it is too much, the biological particles easily pass through the hydrophilic composite porous membrane, and the remaining biological particles remain in at least one of the main surface and the pores on the upstream side and the upstream side of the hydrophilic composite porous membrane. The rate (hereinafter simply referred to as "residual rate of biological particles") is inferior, and as a result, the enrichment rate of biological particles is inferior. From this point of view, t / x is 50 or more, preferably 80 or more, and more preferably 100 or more.
When the t / x of the hydrophilic composite porous membrane is more than 630, the film thickness t is too thick for the size of the average pore size x, or the average pore size x is small for the thickness of the film thickness t. Because it is too much, it is difficult for the aqueous liquid composition to pass through the hydrophilic composite porous membrane, and it takes time for the aqueous liquid composition to pass through the hydrophilic composite porous membrane (that is, it takes time to concentrate the aqueous liquid composition. It takes.). From this point of view, t / x is 630 or less, preferably 600 or less, more preferably 500 or less, and even more preferably 400 or less.

By using the concentrated membrane of the present disclosure, biological particles can be concentrated easily and quickly as compared with the centrifugation method. By using the concentrated membrane of the present disclosure, biological particles can be concentrated quickly and efficiently as compared with the conventional porous membrane.

Hereinafter, the hydrophilic composite porous membrane, the porous base material, and the hydrophilic resin provided in the concentrated membrane of the present disclosure will be described in detail.

[Hydrophilic composite porous membrane]
The hydrophilic composite porous membrane preferably has a water contact angle of 90 degrees or less measured under the following measurement conditions on one side or both sides, and the smaller the water contact angle, the more preferable. The hydrophilic composite porous membrane is more hydrophilic on one side or both sides so that when the contact angle of water is measured under the following measurement conditions, water droplets permeate the inside of the membrane and cannot be measured. preferable.
Here, the contact angle of water is a value measured by the following measuring method. After leaving the porous membrane in an environment with a temperature of 25 ° C. and a relative humidity of 60% for 24 hours or more to adjust the humidity, 1 μL of ion-exchanged water is injected onto the surface of the porous membrane under the same temperature and humidity environment. Drop water droplets and measure the contact angle after 30 seconds by the θ / 2 method using a fully automatic contact angle meter (Kyowa Interface Science Co., Ltd., model number Drop Master DM500).

The thickness t of the hydrophilic composite porous membrane is preferably 10 μm or more, more preferably 15 μm or more, and more preferably 20 μm from the viewpoint of increasing the strength of the hydrophilic composite porous membrane and increasing the residual rate of biological particles. The above is more preferable, and 30 μm or more is further preferable. The thickness t of the hydrophilic composite porous membrane is 150 μm from the viewpoint of shortening the time required for the aqueous liquid composition to pass through the hydrophilic composite porous membrane (hereinafter, referred to as the treatment time of the aqueous liquid composition). The following is preferable, 100 μm or less is more preferable, 80 μm or less is further preferable, and 70 μm or less is further preferable.

The thickness t of the hydrophilic composite porous membrane is determined by measuring 20 points with a contact-type film thickness meter and averaging them.

The average pore size x measured by the palm poromometer of the hydrophilic composite porous membrane is from the viewpoint of shortening the treatment time of the aqueous liquid composition, and the biological particles remaining in the pores of the hydrophilic composite porous membrane. From the viewpoint of easy recovery, 0.1 μm or more is preferable, 0.15 μm or more is more preferable, and 0.2 μm or more is further preferable. The average pore size x measured by the palm poromometer of the hydrophilic composite porous membrane is preferably 0.5 μm or less, more preferably 0.45 μm or less, and 0.4 μm or less from the viewpoint of increasing the residual rate of biological particles. More preferred.

The average pore size x measured with a palm porometer of a hydrophilic composite porous membrane was measured by using a palm porometer (PMI, model: CFP-1200-AEXL) to soak the liquid in Galwick (surface tension 15) manufactured by PMI. .9 dyn / cm), determined by the half-dry method specified in ASTM E1294-89. When only one main surface of the hydrophilic composite porous membrane is coated with the hydrophilic resin, install the main surface coated with the hydrophilic resin toward the pressurized part of the palm poromometer and measure. Do.

The bubble point pore diameter y measured by the palm poromometer of the hydrophilic composite porous membrane is from the viewpoint of shortening the treatment time of the aqueous liquid composition and the biological remaining in the pores of the hydrophilic composite porous membrane. From the viewpoint of easy recovery of particles, more than 0.8 μm is preferable, 0.9 μm or more is more preferable, and 1.0 μm or more is further preferable. The bubble point pore diameter y measured by the palm poromometer of the hydrophilic composite porous membrane is preferably 3 μm or less, more preferably 2.5 μm or less, and 2.2 μm or less from the viewpoint of increasing the residual rate of biological particles. More preferred.

The bubble point pore diameter y measured by the palm porometer of the hydrophilic composite porous membrane is determined by the bubble point method (ASTM F316-86, JIS K3832) using the palm porometer (PMI, model: CFP-1200-AEXL). : 1990). However, it is a value obtained by changing the immersion liquid at the time of the test to Galwick (surface tension 15.9 din / cm) manufactured by PMI. When only one main surface of the hydrophilic composite porous membrane is coated with the hydrophilic resin, install the main surface coated with the hydrophilic resin toward the pressurized part of the palm poromometer and measure. Do.

The bubble point pressure of the hydrophilic composite porous membrane is, for example, 0.01 MPa or more and 0.20 MPa or less, and 0.02 MPa to 0.15 MPa.
In the present disclosure, the bubble point pressure of the hydrophilic composite porous film is such that the hydrophilic composite porous film is immersed in ethanol and the liquid temperature at the time of the test is 24 ± 2 ° C. according to the bubble point test method of JIS K3832: 1990. It is a value obtained by performing a bubble point test while boosting the applied pressure at a boosting speed of 2 kPa / sec. When only one main surface of the hydrophilic composite porous membrane is coated with the hydrophilic resin, the main surface coated with the hydrophilic resin is installed toward the pressure portion of the measuring device to perform the measurement. ..

The water flow rate f (mL / (min · cm ² · MPa)) of the hydrophilic composite porous film is preferably 20 or more, more preferably 50 or more, and 100 or more from the viewpoint of shortening the treatment time of the aqueous liquid composition. Is more preferable. The water flow rate f (mL / (min · cm ² · MPa)) of the hydrophilic composite porous film is preferably 1000 or less, more preferably 800 or less, and 700 or less from the viewpoint of increasing the residual rate of biological particles. More preferred.

The water flow rate f of the hydrophilic composite porous membrane is such that 100 mL of water is permeated through a sample set in a liquid-permeable cell having a constant liquid-permeable area (cm ² ) at a constant differential pressure (20 kPa), and 100 mL of water is obtained. The time (sec) required for permeation is measured and converted into units. When only one main surface of the hydrophilic composite porous membrane is coated with the hydrophilic resin, water is allowed to permeate from the main surface coated with the hydrophilic resin to the main surface not coated with the hydrophilic resin. And measure.

In the hydrophilic composite porous membrane, the ratio f / y of the water flow rate f (mL / (min · cm ² · MPa)) to the bubble point pore diameter y (μm) shortens the treatment time of the aqueous liquid composition. From the viewpoint, it is preferably 100 or more, more preferably 150 or more, and further preferably 200 or more. In the hydrophilic composite porous film, the ratio f / y of the water flow rate f (mL / (min · cm ² · MPa)) to the bubble point pore diameter y (μm) increases the residual rate of biological particles. Therefore, it is preferably 480 or less, more preferably 400 or less, and further preferably 350 or less.

From the viewpoint of increasing the recovery rate of residual biological particles, the hydrophilic composite porous membrane preferably has a surface roughness Ra of 0.3 μm or more, at least on the main surface on the upstream side during the concentration treatment. , 0.4 μm or more is more preferable.
From the viewpoint of increasing the residual rate of biological particles, the hydrophilic composite porous membrane preferably has a surface roughness Ra of 0.7 μm or less, at least on the main surface on the upstream side during the concentration treatment, and is 0. It is more preferably 1.6 μm or less.

The surface roughness Ra of the hydrophilic composite porous film was evaluated by randomly measuring the surface of the sample at three points in a non-contact manner using a light wave interference type surface roughness meter (Zygo, NewView5032). Use the analysis software for this.

The galley value (seconds / 100 mL · μm) per unit thickness of the hydrophilic composite porous membrane is, for example, 0.001 to 5, 0.01 to 3, and 0.05 to 1. The Gale value of the hydrophilic composite porous membrane is a value measured according to JIS P8117: 2009.

The porosity of the hydrophilic composite porous membrane is, for example, 70% to 90%, 72% to 89%, and 74% to 87%. The porosity of the hydrophilic composite porous membrane is determined according to the following calculation method. That is, the constituent materials are a, b, c, ..., N, the mass of each constituent material is Wa, Wb, Wc, ..., Wn (g / cm ² ), and the true density of each constituent material is da, When db, dc, ..., Dn (g / cm ³ ) and the film thickness is t (cm), the porosity ε (%) is calculated by the following formula.
ε = {1- (Wa / da + Wb / db + Wc / dc + ... + Wn / dn) / t} × 100

From the viewpoint of handleability, the hydrophilic composite porous membrane is preferably hard to curl. From the viewpoint of suppressing curling of the hydrophilic composite porous membrane, it is preferable that both main surfaces of the hydrophilic composite porous membrane are coated with a hydrophilic resin.

[Porous medium]
In the present disclosure, the porous base material means a base material having pores or voids inside. Examples of the porous substrate include a microporous membrane; a porous sheet made of a fibrous material such as a non-woven fabric and paper; and the like. As the porous substrate, a microporous film is preferable from the viewpoint of thinning and strength of the concentrated film of the present disclosure. A microporous membrane means a membrane that has a large number of micropores inside and has a structure in which these micropores are connected so that a gas or liquid can pass from one surface to the other. To do.

The material of the porous base material may be either an organic material or an inorganic material.

The porous substrate may be either hydrophilic or hydrophobic. The concentrated film of the present disclosure exhibits hydrophilicity by coating the porous substrate with a hydrophilic resin even if the porous substrate is hydrophobic.

One embodiment of the porous substrate is a microporous membrane made of resin. Resins constituting the microporous film include polyesters such as polyethylene terephthalate; polyolefins such as polyethylene and polypropylene; heat-resistant resins such as total aromatic polyamide, polyamideimide, polyimide, polyethersulfone, polysulfone, polyetherketone, and polyetherimide. ; And so on.

One embodiment of the porous substrate includes a porous sheet made of a fibrous material, and examples thereof include non-woven fabric and paper. As the fibrous material constituting the porous sheet, polyester fibrous material such as polyethylene terephthalate; polyolefin fibrous material such as polyethylene and polypropylene; total aromatic polyamide, polyamideimide, polyimide, polyethersulfone, polysulfone, poly Fibrous materials of heat-resistant resins such as ether ketone and polyetherimide; cellulose; and the like can be mentioned.

The surface of the porous base material may be subjected to various surface treatments for the purpose of improving the wettability of the coating liquid used for coating the porous base material with the hydrophilic resin. Examples of the surface treatment of the porous substrate include corona treatment, plasma treatment, flame treatment, ultraviolet irradiation treatment and the like.

[Physical properties of porous substrate]
The thickness of the porous substrate is preferably 10 μm or more, more preferably 15 μm or more, still more preferably 20 μm or more, from the viewpoint of increasing the strength of the porous substrate and increasing the residual ratio of biological particles. The thickness of the porous substrate is preferably 150 μm or less, more preferably 120 μm or less, still more preferably 100 μm or less, from the viewpoint of shortening the treatment time of the aqueous liquid composition. The method for measuring the thickness of the porous substrate is the same as the method for measuring the thickness t of the hydrophilic composite porous membrane.

The average pore size measured by the palm poromometer of the porous substrate is from the viewpoint of shortening the treatment time of the aqueous liquid composition, and it is easy to recover the biological particles remaining in the pores of the hydrophilic composite porous film. From the viewpoint, 0.1 μm or more is preferable, 0.15 μm or more is more preferable, and 0.2 μm or more is further preferable. The average pore size measured with a palm poromometer of a porous substrate is preferably 0.8 μm or less, more preferably 0.7 μm or less, still more preferably 0.6 μm or less, from the viewpoint of increasing the residual rate of biological particles. The average pore size measured by the palm porometer of the porous base material is a value obtained by the half-dry method specified in ASTM E1294-89 using the palm porometer, and the details of the measurement method are as follows: hydrophilic composite porous film. It is the same as the measuring method relating to the average pore diameter x of.

The bubble point pore size measured by the palm poromometer of the porous substrate is from the viewpoint of shortening the treatment time of the aqueous liquid composition and recovers the biological particles remaining in the pores of the hydrophilic composite porous membrane. From the viewpoint of easy easiness, more than 0.8 μm is preferable, 0.9 μm or more is more preferable, and 1.0 μm or more is further preferable. The bubble point pore diameter measured with a palm poromometer of a porous substrate is preferably 3 μm or less, more preferably 2.8 μm or less, still more preferably 2.5 μm or less, from the viewpoint of increasing the residual rate of biological particles. The bubble point pore diameter measured with a palm porometer of a porous base material is a value obtained by the bubble point method specified in ASTM F316-86 and JIS K3832 using a palm porome, and the details of the measurement method are hydrophilic. It is the same as the measuring method relating to the bubble point pore diameter y of the sex composite porous membrane.

The water flow rate (mL / (min · cm ² · MPa)) of the porous substrate is preferably 20 or more, more preferably 50 or more, still more preferably 100 or more, from the viewpoint of shortening the treatment time of the aqueous liquid composition. .. The water flow rate (mL / (min · cm ² · MPa)) of the porous substrate is preferably 1000 or less, more preferably 800 or less, still more preferably 700 or less, from the viewpoint of increasing the residual rate of biological particles. The method for measuring the water flow rate of the porous substrate is the same as the method for measuring the water flow rate f of the hydrophilic composite porous film. However, if the porous substrate is hydrophobic, use the porous substrate immersed in ethanol and then dried at room temperature as a sample, and use a small amount (0.5 mL) of ethanol for the sample set on the liquid permeable cell. The measurement is performed after wetting.

The surface roughness Ra of the porous substrate is preferably 0.3 μm or more, and more preferably 0.4 μm or more on one side or both sides.
The surface roughness Ra of the porous substrate is preferably 0.7 μm or less, and more preferably 0.6 μm or less on one side or both sides.
The method for measuring the surface roughness Ra of the porous substrate is the same as the measuring method for the surface roughness Ra of the hydrophilic composite porous film.

The galley value (seconds / 100 mL · μm) per unit thickness of the porous substrate is, for example, 0.001 to 5, 0.01 to 3, and 0.05 to 1. The galley value of the porous substrate is a value measured according to JIS P8117: 2009.

The porosity of the porous substrate is, for example, 70% to 90%, 72% to 89%, and 74% to 87%. The porosity of the porous substrate is determined according to the following calculation method. That is, the constituent materials are a, b, c, ..., N, the mass of each constituent material is Wa, Wb, Wc, ..., Wn (g / cm ² ), and the true density of each constituent material is da, When db, dc, ..., Dn (g / cm ³ ) and the film thickness is t (cm), the porosity ε (%) is calculated by the following formula.
ε = {1- (Wa / da + Wb / db + Wc / dc + ... + Wn / dn) / t} × 100

BET specific surface area of the porous substrate, for ^example, a 1m ² / g~40m 2 / ^g, a 2m ² / g~30m 2 / ^g, a 3m ² / g~20m 2 / g. The BET specific surface area of the porous substrate is set by the nitrogen gas adsorption method under liquid nitrogen temperature using a specific surface area measuring device (model: BELSORP-mini) manufactured by Microtrac Bell Co., Ltd. It is a value obtained by measuring the adsorption isotherm of × 10 ^{-3 to} 0.35 and analyzing it by the BET method.

[Polyolefin microporous membrane]
One embodiment of the porous substrate includes a microporous membrane containing a polyolefin (referred to as a polyolefin microporous membrane in the present disclosure). The polyolefin contained in the polyolefin microporous membrane is not particularly limited, and examples thereof include polyethylene, polypropylene, polybutylene, polymethylpentene, and a copolymer of polypropylene and polyethylene. Among these, polyethylene is preferable, and high-density polyethylene, a mixture of high-density polyethylene and ultra-high molecular weight polyethylene, and the like are preferable. One embodiment of the polyolefin microporous membrane is a polyethylene microporous membrane in which only polyethylene is contained.

The weight average molecular weight (Mw) of the polyolefin contained in the polyolefin microporous membrane is, for example, 100,000 to 5,000,000. When the Mw of the polyolefin is 100,000 or more, sufficient mechanical properties can be imparted to the microporous membrane. When the Mw of polyolefin is 5 million or less, it is easy to form a microporous film.

As one embodiment of the polyolefin microporous membrane, a polyolefin composition (in the present disclosure, means a mixture of polyolefins containing two or more kinds of polyolefins, and when the contained polyolefin is only polyethylene, it is referred to as a polyethylene composition). Examples thereof include microporous membranes. The polyolefin composition has the effect of forming a network structure with fibrillation during stretching and increasing the porosity of the polyolefin microporous film.

The polyolefin composition, the ultra-high molecular weight polyethylene having a weight-average molecular weight is 9 × 10 ⁵ or more, relative to the total amount of polyolefin, preferably a polyolefin composition comprising 5 to 40 wt%, 10 wt% to 35 wt A polyolefin composition containing% is more preferable, and a polyolefin composition containing 15% by mass to 30% by mass is further preferable.

Polyolefin composition, and ultra high molecular weight polyethylene having a weight-average molecular weight is 9 × 10 ⁵ or more, the weight average molecular weight of the density at 2 × ^{10 5} ~8 × ¹⁰ 5 is 920kg ^{/ m 3} ~960kg ^/ m 3 high It is preferable that the density polyethylene is a polyolefin composition mixed in a mass ratio of 5:95 to 40:60 (more preferably 10:90 to 35:65, still more preferably 15:85 to 30:70).

The polyolefin composition preferably has a total weight average molecular weight of 2 × 10 ⁵ to 2 × 10 ⁶ .

The weight average molecular weight of the polyolefin constituting the polyolefin microporous film is determined by heating and dissolving the polyolefin microporous film in o-dichlorobenzene and performing gel permeation chromatography (system: Waters Co., Ltd. Alliance GPC 2000 type, column: GMH6-HT and It is obtained by measuring with GMH6-HTL) under the conditions of a column temperature of 135 ° C. and a flow velocity of 1.0 mL / min. Molecular weight monodisperse polystyrene (manufactured by Tosoh Corporation) is used for molecular weight calibration.

As one embodiment of the polyolefin microporous film, a microporous film containing polypropylene can be mentioned from the viewpoint of having heat resistance that does not easily break the film when exposed to a high temperature.

One embodiment of the polyolefin microporous membrane is a polyolefin microporous membrane in which at least polyethylene and polypropylene are mixed and contained.

One embodiment of the polyolefin microporous membrane includes a polyolefin microporous membrane having a laminated structure of two or more layers, at least one layer containing polyethylene and at least one layer containing polypropylene.

[Method for producing microporous polyolefin membrane]
The polyolefin microporous membrane can be produced, for example, by a production method including the following steps (I) to (IV).

Step (I): A step of preparing a solution containing the polyolefin composition and a volatile solvent having a boiling point of less than 210 ° C. at atmospheric pressure.
Step (II): A step of melt-kneading the solution, extruding the obtained melt-kneaded product from a die, and cooling and solidifying to obtain a first gel-like molded product.
Step (III): A step of stretching (primary stretching) the first gel-like molded product in at least one direction and drying the solvent to obtain a second gel-like molded product.
Step (IV): A step of stretching (secondary stretching) the second gel-like molded product in at least one direction.

Step (I) is a step of preparing a solution containing the polyolefin composition and a volatile solvent having a boiling point of less than 210 ° C. at atmospheric pressure. The solution is preferably a thermoreversible sol-gel solution, and the polyolefin composition is dissolved by heating in a solvent to form a sol to prepare a thermoreversible sol-gel solution. The volatile solvent having a boiling point of less than 210 ° C. at atmospheric pressure is not particularly limited as long as it can sufficiently dissolve polyolefin. Examples of the volatile solvent include tetralin (206 ° C. to 208 ° C.), ethylene glycol (197.3 ° C.), decalin (decahydronaphthalen, 187 ° C. to 196 ° C.), toluene (110.6 ° C.), and xylene. (138 ° C to 144 ° C), diethyltriamine (107 ° C), ethylenediamine (116 ° C), dimethyl sulfoxide (189 ° C), hexane (69 ° C) and the like, and decalin or xylene is preferable (the temperature in parentheses is: It is the boiling point at atmospheric pressure.). The volatile solvent may be used alone or in combination of two or more.

The polyolefin composition used in the step (I) (in the present disclosure, means a mixture of polyolefins containing two or more kinds of polyolefins, and when the polyolefin contained is only polyethylene, it is referred to as a polyethylene composition) contains polyethylene. It is preferable, and a polyethylene composition is more preferable.

The solution prepared in the step (I) preferably has a polyolefin composition concentration of 10% by mass to 40% by mass, preferably 15% by mass to 35% by mass, from the viewpoint of controlling the porous structure of the polyolefin microporous film. Is more preferable. When the concentration of the polyolefin composition is 10% by mass or more, the occurrence of cutting can be suppressed in the film forming process of the polyolefin microporous film, the mechanical strength of the polyolefin microporous film is increased, and the handleability is improved. When the concentration of the polyolefin composition is 40% by mass or less, pores of the polyolefin microporous film are likely to be formed.

The step (II) is a step of melt-kneading the solution prepared in the step (I), extruding the obtained melt-kneaded product from a die, and cooling and solidifying to obtain a first gel-like molded product. In step (II), for example, the polyolefin composition is extruded from a die in a temperature range of melting point to melting point + 65 ° C. to obtain an extruded product, and then the extruded product is cooled to obtain a first gel-like molded product. The first gel-like molded product is preferably shaped into a sheet. Cooling may be performed by immersion in water or an organic solvent, by contact with a cooled metal roll, and generally by immersion in the volatile solvent used in step (I). Will be done.

Step (III) is a step of stretching the first gel-like molded product in at least one direction (primary stretching) and drying the solvent to obtain a second gel-like molded product. The stretching step of the step (III) is preferably biaxial stretching, and may be sequential biaxial stretching in which longitudinal stretching and transverse stretching are performed separately, or simultaneous biaxial stretching in which longitudinal stretching and transverse stretching are simultaneously performed. The draw ratio (product of the longitudinal draw ratio and the transverse draw ratio) of the primary stretch is preferably 1.1 times to 3 times, preferably 1.1 times to 2 times, from the viewpoint of controlling the porous structure of the polyolefin microporous membrane. More preferred. The temperature during stretching of the primary stretching is preferably 75 ° C. or lower. The drying step of the step (III) is carried out without particular limitation as long as the temperature at which the second gel-like molded product is not deformed, but it is preferably carried out at 60 ° C. or lower.

The stretching step and the drying step of the step (III) may be performed simultaneously or stepwise. For example, the primary stretching may be performed while pre-drying, and then the main drying may be performed, or the primary stretching may be performed between the pre-drying and the main drying. The primary stretching can be performed even in a state where drying is controlled and the solvent remains in a suitable state.

Step (IV) is a step of stretching (secondary stretching) the second gel-like molded product in at least one direction. The stretching step of the step (IV) is preferably biaxial stretching. In the stretching step of step (IV), longitudinal stretching and transverse stretching are carried out separately; sequential biaxial stretching; longitudinal stretching and transverse stretching are carried out at the same time; simultaneous biaxial stretching; after stretching a plurality of times in the longitudinal direction, the transverse direction A step of stretching in the vertical direction and a step of stretching in the horizontal direction a plurality of times; a step of sequentially biaxially stretching and then further stretching once or in the horizontal direction once or a plurality of times;

The draw ratio (product of the longitudinal draw ratio and the transverse draw ratio) of the secondary stretch is preferably 5 times to 90 times, more preferably 10 times to 60 times, from the viewpoint of controlling the porous structure of the polyolefin microporous membrane. It is double. The stretching temperature of the secondary stretching is preferably 90 ° C. to 135 ° C., more preferably 90 ° C. to 130 ° C. from the viewpoint of controlling the porous structure of the polyolefin microporous membrane.

The heat fixing treatment may be performed after the step (IV). The heat fixing temperature is preferably 110 ° C. to 160 ° C., more preferably 120 ° C. to 150 ° C. from the viewpoint of controlling the porous structure of the polyolefin microporous membrane.

After the heat fixing treatment, an extraction treatment and an annealing treatment of the solvent remaining on the microporous polyolefin membrane may be further performed. The residual solvent extraction treatment is performed, for example, by immersing the sheet after the heat-fixing treatment in a methylene chloride bath to elute the residual solvent in methylene chloride. The microporous polyolefin membrane immersed in the methylene chloride bath is preferably withdrawn from the methylene chloride bath and then dried to remove methylene chloride. The annealing treatment is carried out by transporting the microporous polyolefin membrane on a roller heated to, for example, 100 ° C. to 140 ° C. after the extraction treatment of the residual solvent.

By controlling the conditions of steps (I) to (IV), a polyolefin microporous film having a ratio t / x of the film thickness t (μm) and the average pore diameter x (μm) of 50 to 630 is produced. Becomes possible. For example, the ratio t / x can be controlled to 50 or more by reducing the longitudinal stretching ratio. For example, the ratio t / x can be controlled to 630 or less by increasing the longitudinal stretching ratio.

[Hydrophilic resin]
The hydrophilic resin is not particularly limited, and examples thereof include resins having a hydrophilic group such as a hydroxy group, a carboxy group, and a sulfo group.

From the viewpoint of preventing the hydrophilic resin from falling off from the porous substrate and the concentration rate of biological particles, the main chain of the polymer consists only of carbon atoms and the side chains consist of hydroxy groups, carboxy groups and sulfo groups. A resin having at least one functional group selected from the above group is preferable.
Examples of the hydrophilic resin include resins in which not only carbon atoms but also oxygen atoms are contained in the main chain of the polymer (for example, polyethylene glucol, cellulose, etc.), but hydrophilic resins in which the main chain of the polymer contains oxygen atoms. Is relatively easy to fall off from the porous substrate. From the viewpoint of preventing the polymer from falling off from the porous substrate, a resin in which the main chain of the polymer consists only of carbon atoms is preferable, and a group in which the main chain of the polymer consists only of carbon atoms and the side chains consist of hydroxy groups, carboxy groups and sulfo groups. A resin having at least one functional group selected from the above is more preferable.

Hydrophilic resins include polyvinyl alcohol, olefin / vinyl alcohol resin, acrylic / vinyl alcohol resin, methacryl / vinyl alcohol resin, vinylpyrrolidone / vinyl alcohol resin, polyacrylic acid, polymethacrylic acid, and perfluorosulfonic acid. It preferably contains at least one hydrophilic resin selected from the group consisting of resins and polystyrene sulfonic acids. Above all, it is more preferable to contain an olefin / vinyl alcohol-based resin.

Examples of the hydrophilic resin include a hydrophilic resin obtained by graft-polymerizing a hydrophilic monomer on the surface of a porous substrate. In this case, the hydrophilic resin is in the form of being directly chemically bonded to the surface of the porous substrate. Examples of the hydrophilic monomer graft-polymerized on the surface of the porous substrate include acrylic acid, methacrylic acid, vinyl alcohol, N-vinyl-2-pyrrolidone, vinyl sulfonic acid and the like. From the viewpoint of the manufacturability of the hydrophilic composite porous film, the hydrophilic resin is made porous by a coating method or the like, rather than the form in which the hydrophilic resin is directly chemically bonded to the surface of the porous substrate as in graft polymerization. A form adhered to the surface of the base material (a form in which the hydrophilic resin is not chemically bonded to the surface of the porous base material) is preferable.

The hydrophilic resin may be one kind or two or more kinds.

The hydrophilic resin is an olefin from the viewpoint of less irritation to biological particles and from the viewpoint of easily recovering biological particles remaining in the main surface and pores on the upstream side of the hydrophilic composite porous membrane. Vinyl alcohol-based resins are preferred.

Examples of the olefin constituting the olefin / vinyl alcohol-based resin include ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, and decene. As the olefin, an olefin having 2 to 6 carbon atoms is preferable, an α-olefin having 2 to 6 carbon atoms is more preferable, an α-olefin having 2 to 4 carbon atoms is further preferable, and ethylene is particularly preferable. The olefin unit contained in the olefin / vinyl alcohol-based resin may be one kind or two or more kinds.

The olefin / vinyl alcohol-based resin may contain a monomer other than olefin and vinyl alcohol as a constituent unit. As the monomer other than olefin and vinyl alcohol, for example, at least one acrylic monomer selected from the group consisting of (meth) acrylic acid, (meth) acrylic acid salt, and (meth) acrylic acid ester; styrene, metachlorostyrene. , Parachlorostyrene, parafluorostyrene, paramethoxystyrene, meta-tert-butoxystyrene, para-tert-butoxystyrene, baravinylbenzoic acid, styrene-based monomers such as paramethyl-α-methylstyrene; and the like. One type of these monomer units may be contained in the olefin / vinyl alcohol-based resin, or two or more types may be contained.

The olefin / vinyl alcohol-based resin may contain a monomer other than olefin and vinyl alcohol as a constituent unit, but it remains in the pores of the hydrophilic composite porous film from the viewpoint of less irritation to biological particles. From the viewpoint of easy recovery of the biological particles, the total ratio of the olefin unit and the vinyl alcohol unit is preferably 85 mol% or more, more preferably 90 mol% or more, and 95 mol% or more. Is more preferable, and 100 mol% is particularly preferable. As the olefin / vinyl alcohol-based resin, a binary copolymer of olefin and vinyl alcohol is preferable (here, the preferred embodiment of the olefin is as described above), and a binary copolymer of ethylene and vinyl alcohol is preferable. Is more preferable.

The ratio of the olefin unit in the olefin / vinyl alcohol-based resin is preferably 20 mol% to 55 mol%. When the ratio of the olefin unit is 20 mol% or more, the olefin / vinyl alcohol-based resin is difficult to dissolve in water. From this viewpoint, the ratio of the olefin unit is more preferably 23 mol% or more, further preferably 25 mol% or more. When the ratio of the olefin unit is 55 mol% or less, the hydrophilicity of the olefin / vinyl alcohol-based resin is higher. From this viewpoint, the ratio of the olefin unit is more preferably 52 mol% or less, further preferably 50 mol% or less.

Examples of commercially available olefin / vinyl alcohol-based resins include "Soanol" manufactured by Nippon Synthetic Chemical Industry Co., Ltd. and "Eberle" manufactured by Kuraray Co., Ltd.

Adhesion amount of the hydrophilic resin to the porous substrate, for example, a ^{0.01g / m 2 ~5g / m 2} , was ^{0.02g / m 2 ~2g / m 2} , 0.03g / m 2 ~ It is 1 g / m ² . The amount of the hydrophilic resin adhered to the porous base material is the value obtained by subtracting the texture Wb (g / m ² ) of the porous base material from the texture Wa (g / m ² ) of the hydrophilic composite porous membrane (Wa-Wb). ).

[Method for manufacturing hydrophilic composite porous membrane]
The method for producing the hydrophilic composite porous membrane is not particularly limited. As a general manufacturing method, a coating liquid containing a hydrophilic resin is applied to a porous base material, the coating liquid is dried, and the porous base material is coated with the hydrophilic resin; the porous base material is coated. A method of graft-polymerizing a hydrophilic monomer and coating a porous substrate with a hydrophilic resin;

The coating liquid containing the hydrophilic resin can be prepared by dissolving or dispersing the hydrophilic resin in the solvent by mixing the hydrophilic resin with a solvent heated to a temperature higher than the melting point of the hydrophilic resin and stirring. it can. The solvent is not particularly limited as long as it is a solvent that is a good solvent for the hydrophilic resin, but specifically, for example, a 1-propanol aqueous solution, a 2-propanol aqueous solution, an N, N-dimethylformamide aqueous solution, and a dimethyl sulfoxide aqueous solution. , Ethanol aqueous solution and the like. The proportion of the organic solvent in these aqueous solutions is preferably 30% by mass to 70% by mass.

When the coating liquid containing the hydrophilic resin is applied to the porous substrate, the concentration of the hydrophilic resin in the coating liquid is preferably 0.01% by mass to 5% by mass. When the concentration of the hydrophilic resin in the coating liquid is 0.01% by mass or more, hydrophilicity can be efficiently imparted to the porous substrate. From this point of view, the concentration of the hydrophilic resin in the coating liquid is more preferably 0.05% by mass or more, further preferably 0.1% by mass or more. When the concentration of the hydrophilic resin in the coating liquid is 5% by mass or less, the water flow rate in the produced hydrophilic composite porous film is large. From this point of view, the concentration of the hydrophilic resin in the coating liquid is more preferably 3% by mass or less, further preferably 2% by mass or less.

The coating liquid can be applied to the porous substrate by a known coating method. Examples of the coating method include a dipping method, a knife coater method, a gravure coater method, a screen printing method, a Meyer bar method, a die coater method, a reverse roll coater method, an inkjet method, a spray method, and a roll coater method. By adjusting the temperature of the coating liquid at the time of coating, the hydrophilic resin layer can be stably formed. The temperature of the coating liquid is not particularly limited, but is preferably in the range of 5 ° C to 40 ° C.

The temperature at which the coating liquid is dried is preferably 25 ° C to 100 ° C. When the drying temperature is 25 ° C. or higher, the time required for drying can be shortened. From this viewpoint, the dry concentration is more preferably 40 ° C. or higher, further preferably 50 ° C. or higher. When the drying temperature is 100 ° C. or lower, the shrinkage of the porous substrate is suppressed. From this point of view, the drying temperature is more preferably 90 ° C. or lower, further preferably 80 ° C. or lower.

The hydrophilic composite porous film may contain a surfactant, a wetting agent, a defoaming agent, a pH adjusting agent, a coloring agent and the like.

The concentrated film of the present disclosure will be described in more detail with reference to Examples below. The materials, amounts used, proportions, treatment procedures, etc. shown in the following examples can be appropriately changed without departing from the spirit of the present disclosure. Therefore, the scope of the concentrated membranes of the present disclosure should not be construed as limiting by the specific examples set forth below.

<Preparation of hydrophilic composite porous membrane>
[Example 1]
-Preparation of polyethylene microporous membrane-
Ultra-high molecular weight polyethylene with a weight average molecular weight of 4.6 million (hereinafter referred to as "UHMWPE") 3.75 parts by mass and high-density polyethylene with a weight average molecular weight of 560,000 and a density of 950 kg / m ³ (hereinafter referred to as "HDPE") 21. A polyethylene composition mixed with 25 parts by mass was prepared. A polyethylene solution was prepared by mixing the polyethylene composition and decalin so that the polymer concentration was 25% by mass.

The above polyethylene solution was extruded from a die into a sheet at a temperature of 147 ° C., and then the extruded product was cooled in a water bath having a water temperature of 20 ° C. to obtain a first gel-like sheet.

The first gel-like sheet was pre-dried in a temperature atmosphere of 70 ° C. for 10 minutes, then primary stretched 1.8 times in the MD direction, and then the main drying was performed in a temperature atmosphere of 57 ° C. 5 After a minute, a second gel sheet (base tape) was obtained (the residual amount of the solvent in the second gel sheet was less than 1%). Next, as secondary stretching, the second gel-like sheet (base tape) was stretched in the MD direction at a temperature of 90 ° C. at a magnification of 4 times, then in the TD direction at a temperature of 125 ° C. at a magnification of 9 times, and then. Immediately, heat treatment (heat fixation) was performed at 144 ° C.

The decalin in the sheet was extracted while continuously immersing the heat-fixed sheet in a methylene chloride bath divided into two tanks for 30 seconds each. After removing the sheet from the methylene chloride bath, methylene chloride was dried and removed in a temperature atmosphere of 40 ° C. In this way, a polyethylene microporous membrane was obtained.

− Hydrophilization treatment of polyethylene microporous membrane −
As the hydrophilic resin, an ethylene / vinyl alcohol binary copolymer (manufactured by Nippon Synthetic Chem Industry Co., Ltd., Soanol DC3203R, ethylene unit 32 mol%) (hereinafter referred to as EVOH) was prepared. EVOH was dissolved in a mixed solvent of 1-propanol and water (1-propanol: water = 3: 2 [volume ratio]) so that the concentration of EVOH was 0.2% by mass to obtain a coating liquid.

The polyethylene microporous membrane fixed to the metal frame was immersed in the coating liquid to impregnate the pores of the polyethylene microporous membrane with the coating liquid, and then pulled up. Next, excess coating liquid adhering to both main surfaces of the polyethylene microporous membrane was removed, and the polyethylene was dried at room temperature for 2 hours. Then, the metal frame was removed from the polyethylene microporous membrane. In this way, a hydrophilic composite porous membrane in which both the main surfaces and the inner surfaces of the pores of the polyethylene microporous membrane were coated with a hydrophilic resin was obtained.

[Examples 2 to 7]
-Preparation of polyethylene microporous membrane-
A polyethylene microporous membrane was prepared in the same manner as in Example 1 except that the composition of the polyethylene solution or the manufacturing process of the polyethylene microporous membrane was changed as shown in Table 1. In Examples 3 to 6, after the sheet was carried out from the methylene chloride bath, methylene chloride was dried and removed in a temperature atmosphere of 40 ° C., and annealing treatment was performed while transporting the sheet on a roller heated to 120 ° C.

− Hydrophilization treatment of polyethylene microporous membrane −
EVOH was applied to the polyethylene microporous membrane in the same manner as in Example 1 to prepare a hydrophilic composite porous membrane. However, in Examples 5 to 6, the EVOH concentration of the coating liquid was set to 1% by mass.

[Comparative Example 1]
-Preparation of polyethylene microporous membrane-
A polyethylene microporous membrane was prepared in the same manner as in Example 1 except that the composition of the polyethylene solution and the manufacturing process of the polyethylene microporous membrane were changed as shown in Table 1. In Comparative Example 1, after the sheet was carried out from the methylene chloride bath, methylene chloride was dried and removed in a temperature atmosphere of 40 ° C., and annealing treatment was performed while transporting the sheet on a roller heated to 120 ° C.

− Hydrophilization treatment of polyethylene microporous membrane −
One side of the polyethylene microporous membrane was subjected to plasma treatment (AP-300 manufactured by Nordson MARCH: output 150 W, treatment pressure 400 mTorr, gas flow rate 160 sccm, treatment time 45 seconds) to obtain a hydrophilic composite porous membrane.

[Comparative Example 2]
-Preparation of polyethylene microporous membrane-
A polyethylene microporous membrane was prepared in the same manner as in Example 1 except that the manufacturing process of the polyethylene microporous membrane was changed as shown in Table 1.

− Hydrophilization treatment of polyethylene microporous membrane −
One side of the polyethylene microporous membrane was subjected to plasma treatment (AP-300 manufactured by Nordson MARCH: output 150 W, treatment pressure 400 mTorr, gas flow rate 160 sccm, treatment time 45 seconds) to obtain a hydrophilic composite porous membrane.

[Comparative Example 3]
-Preparation of polyethylene microporous membrane-
A polyethylene microporous membrane was prepared in the same manner as in Example 1 except that the manufacturing process of the polyethylene microporous membrane was changed as shown in Table 1.

− Hydrophilization treatment of polyethylene microporous membrane −
EVOH was applied to the polyethylene microporous membrane in the same manner as in Example 1 to prepare a hydrophilic composite porous membrane.

[Comparative Example 4]
As Comparative Example 4, a syringe filter, SYNN0601MNXX104 manufactured by mdi Corporation, was prepared. The porous membrane included in this syringe filter is made of nylon.

[Comparative Example 5]
As Comparative Example 5, CA025022 manufactured by Membrane Solutions, which is a syringe filter, was prepared. The porous membrane included in this syringe filter is made of cellulose acetate.

<Measurement of physical properties of hydrophilic composite porous membrane>
The following physical property measurements were carried out using the hydrophilic composite porous membranes or porous membranes of Examples 1 to 7 and Comparative Examples 1 to 5 as samples. For each of the hydrophilic composite porous membranes of Comparative Examples 1 and 2, the physical properties of the main surface subjected to plasma treatment were measured. For each of the porous membranes of the syringe filters of Comparative Examples 4 to 5, the porous membrane was taken out from the syringe filter, and the physical properties of the main surface on the inlet side of the syringe filter were measured. The results are shown in Table 2.

[Film thickness]
The thickness of the hydrophilic composite porous film or the porous film was determined by measuring 20 points with a contact-type film thickness meter (manufactured by Mitutoyo Co., Ltd.) and averaging them. As the contact terminal, a columnar terminal having a bottom surface of 0.5 cm in diameter was used. The measured pressure was 0.1 N.

[Average hole diameter x]
For the average pore size x (μm) of the hydrophilic composite porous membrane or the porous membrane, a Palm Polometer (model: CFP-1200-AEXL) manufactured by PMI was used, and Galwick (surface tension 15) manufactured by PMI was used for immersion. It was determined by the half-dry method specified in ASTM E1294-89 using .9 dyn / cm). The measurement temperature was 25 ° C., and the measurement pressure was changed in the range of 0 to 600 kPa.

[Bubble point pore diameter y]
The bubble point pore diameter y (μm) of the hydrophilic composite porous membrane or the porous membrane is determined by the bubble point method (ASTM F316-86, JIS K3832) using a palm porometer (model: CFP-1200-AEXL) manufactured by PMI. : 1990). However, the immersion liquid at the time of the test was changed to Galwick (surface tension 15.9 din / cm) manufactured by PMI. The measurement temperature was 25 ° C., and the measurement pressure was changed in the range of 0 to 600 kPa.

[Bubble point pressure]
The hydrophilic composite porous membrane or the porous membrane is immersed in ethanol, and according to the bubble point test method of JIS K3832: 1990, however, the liquid temperature at the time of the test is changed to 24 ± 2 ° C., and the applied pressure is increased at a step-up rate of 2 kPa /. It was obtained by performing a bubble point test while boosting in seconds.

[Water flow rate f]
The hydrophilic composite porous membrane was cut out in an MD direction of 10 cm and a TD direction of 10 cm, and set in a stainless steel circular liquid permeable cell having a liquid permeable area of 17.34 cm ² . 100 mL of water was permeated at a differential pressure of 20 kPa, and the time (sec) required for 100 mL of water to permeate was measured. The measurement was performed in a temperature atmosphere at room temperature of 24 ° C. The water flow rate f (mL / (min · cm ² · MPa)) was determined by converting the measurement conditions and the measured values into units.

[Surface Roughness Ra]
The arithmetic average height under the following conditions was measured using a light wave interference type surface roughness meter (Zygo, NewView 5032) to determine the surface roughness Ra.
-Objective lens: 20x Mirau type (Mirau type)
・ Image zoom: 1.0 ×
-FDA Res: Normal or Low
-Analysis conditions: Stich, which is a standard application of Zygo. After acquiring the data of 3 places of each sample in a non-contact manner using the application, Advance Texture, which is an optional application for roughness evaluation,. The surface roughness was analyzed using the application.

<Performance evaluation of concentrated membrane>
A concentration test was conducted using each of the hydrophilic composite porous membranes or porous membranes of Examples 1 to 7 and Comparative Examples 1 to 5 as a concentration membrane. When each of the hydrophilic composite porous membranes of Comparative Examples 1 and 2 was used as the concentrated membrane, the main surface subjected to the plasma treatment was on the upstream side. When each of the porous membranes of the syringe filters of Comparative Examples 4 to 5 was used as a concentrated membrane, the porous membrane was taken out from the syringe filter and the main surface on the inlet side of the syringe filter was set to the upstream side. Table 2 shows the results of the concentration test. The details of the enrichment test are as follows.

A virus suspension in which dengue virus was suspended in a buffer solution was prepared. The virus unit was 1 × 10 ⁴ FFU / mL. The dengue virus is a spherical virus having an envelope and having a diameter of about 40 nm to 60 nm.

The hydrophilic composite porous membrane or the porous membrane was punched into a circle having a diameter of 13 mm with a punch and installed in the housing of a filter holder (manufactured by Merck Millipore, Swinex 35). 10 mL of virus suspension was collected in a 10 mL volume syringe (manufactured by Terumo). The tip of the syringe was connected to the filter holder and the virus suspension was passed through the filter holder. The pressure applied to the plunger was about 30 N. When the plunger did not move under the pressure, the applied pressure was gradually increased to apply the minimum pressure for the plunger to move.

[processing time]
The time (seconds) from the time when the plunger was started to be pushed to the time when the plunger was completely pushed was measured.

[Concentration rate]
After pushing the plunger completely, the plunger was reciprocated several times with the filter device up and the syringe down, and the virus suspension remaining upstream of the concentrated membrane was collected. Using the recovered virus suspension as a sample, total RNA was extracted using Viral RNA Mini Kit (QIAGEN). Using RiverTra Ace® (Toyobo), the extracted total RNA was reverse transcribed to prepare cDNA. QRT-PCR was performed using a primer that specifically binds to dengue viral RNA and SYBR Green I (Takara Bio) (SYBR is a registered trademark) to quantify the viral RNA in the sample. The concentration rate (%) = Cb ÷ Ca × 100 was calculated from the virus RNA concentration Ca of the virus suspension before passing the liquid and the virus RNA concentration Cb of the recovered virus suspension.

FIG. 1 is a schematic view showing an instrument and an operation of a concentration test. In FIG. 1 (a), the arrow indicates the direction in which the virus suspension flows. In FIG. 1 (b), the arrow indicates the direction in which the virus suspension remaining upstream of the concentrated membrane is collected.

Claims (12)

A hydrophilic composite porous film comprising a porous base material and a hydrophilic resin that covers at least one main surface of the porous base material and the inner surface of pores.
A hydrophilic composite porous membrane in which the ratio t / x of the film thickness t (μm) to the average pore diameter x (μm) measured by a palm poromometer is 50 to 630.
Concentrating membrane used to concentrate biological particles, including. The concentrated membrane according to claim 1, wherein the hydrophilic composite porous membrane has an average pore diameter x of 0.1 μm to 0.5 μm. The concentrated membrane according to claim 1 or 2, wherein the hydrophilic composite porous membrane has a bubble point pore diameter y measured by a palm poromometer of more than 0.8 μm and 3 μm or less. The hydrophilic composite porous membrane has a ratio f / y of water flow rate f (mL / (min · cm ² · MPa)) to bubble point pore diameter y (μm) measured with a palm poromometer of 100 to 480. The concentrated membrane according to any one of claims 1 to 3. The concentrated film according to any one of claims 1 to 4, wherein the hydrophilic composite porous film has a film thickness t of 10 μm to 150 μm. The concentrated film according to any one of claims 1 to 5, wherein the hydrophilic composite porous film has a surface roughness Ra of 0.3 μm to 0.7 μm. Claimed that the hydrophilic resin contains a hydrophilic resin in which the main chain of the polymer consists only of carbon atoms and the side chain has at least one functional group selected from the group consisting of a hydroxy group, a carboxy group and a sulfo group. The concentrated film according to any one of 1 to 6. The hydrophilic resin is polyvinyl alcohol, olefin / vinyl alcohol resin, acrylic / vinyl alcohol resin, methacryl / vinyl alcohol resin, vinylpyrrolidone / vinyl alcohol resin, polyacrylic acid, polymethacrylic acid, perfluorosulfonic acid. The concentrated film according to any one of claims 1 to 6, which contains at least one hydrophilic resin selected from the group consisting of a based resin and polystyrene sulfonic acid. The concentrated film according to any one of claims 1 to 6, wherein the hydrophilic resin contains an olefin / vinyl alcohol-based resin. The concentrated film according to any one of claims 1 to 9, wherein the porous substrate is a microporous polyolefin membrane. The concentrated membrane according to any one of claims 1 to 10, wherein the biological particles have a size of 10 nm to 1000 nm. The concentrated membrane according to any one of claims 1 to 11, wherein the biological particle is a virus, a bacterium, or an exosome.