Water-soluble filter

Abstract

To provide a water-soluble filter of high durability and particle capture efficiency.SOLUTION: This invention relates to a water-soluble filter which captures fine particles and comprises an unwoven fabric including fibers containing polyvinyl alcohol with an average fiber diameter of 20 to 300 nm for the unwoven fabric.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a water-soluble filter. [Background technology]

[0002] In order to clarify the mechanism by which harmful airborne particles manifest, it is necessary to directly expose cells or organisms to the particles and examine the relationship between their harmfulness and particle characteristics (size, shape, chemical composition, bacterial flora, etc.).

[0003] However, in the field of chemical analysis, air particles are generally collected on filters made of quartz fiber, polytetrafluoroethylene (PTFE), etc. (e.g., Patent Document 1, etc.) before analysis. On the other hand, in the field of biological analysis, air particles are generally collected on water-soluble filters made of gelatin, etc. (e.g., Patent Document 2, etc.) before analysis.

[0004] As a result of the different filters used for chemical and biological analyses of airborne particles, it is difficult to perform chemical and biological analyses across the board, and progress has not been made in elucidating the mechanism by which harmful effects of airborne particles manifest. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-202217 [Patent Document 2] Special Publication No. 2001-523549 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a water-soluble filter that is highly durable and has high particle collection efficiency and that can be used to carry out both chemical analysis and biological analysis. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors conducted extensive research and found that a water-soluble filter including a nonwoven fabric containing polyvinyl alcohol-containing fibers has high durability and high particle collection efficiency. The present invention was completed based on these findings and includes the following broad aspects of the invention. [Section 1] A water-soluble filter for collecting fine particles, A nonwoven fabric including fibers containing polyvinyl alcohol, The water-soluble filter, wherein the average fiber diameter of the fibers of the nonwoven fabric is 20 to 300 nm. [Section 2] The nonwoven fabric has a basis weight of 5 to 50 g / m 2 Item 2. The water-soluble filter according to item 1, having a thickness of 10 to 150 μm. [Section 3] Item 3. The water-soluble filter according to item 1 or 2, wherein the polyvinyl alcohol has a weight average molecular weight of 70,000 to 120,000. [Section 4] 4. The water-soluble filter according to any one of items 1 to 3, which dissolves within 1 hour when 1 part by mass of the water-soluble filter is mixed with 100 parts by mass of water and stirred at 80 to 90°C. [Section 5] 5. The water-soluble filter according to any one of items 1 to 4, which has a pressure loss of 300 Pa or less at a linear air velocity of 0.6 to 0.9 cm / s and a collection efficiency of 95% or more for fine particles having a particle diameter of 0.3 μm to 10 μm. [Section 6] Item 6. The water-soluble filter according to any one of items 1 to 5, which is used for collecting and analyzing fine particles. [Section 7] Item 7. A method for producing the water-soluble filter according to any one of items 1 to 6, which uses an electrospinning method. [Section 8] preparing a 5 to 20 w / v% polyvinyl alcohol solution; Item 8. The method according to item 7, further comprising forming a nonwoven fabric by electrospinning using the solution. [Section 9] Item 7. A method for capturing fine particles, which uses the water-soluble filter according to any one of Items 1 to 6. [Section 10] A step of collecting fine particles using the water-soluble filter according to any one of items 1 to 6; analyzing the particles captured on the filter while they are retained on the filter; A method for analyzing fine particles, comprising: [Section 11] A step of collecting fine particles using the water-soluble filter according to any one of items 1 to 6; a step of dissolving the filter on which the fine particles have been collected in a solvent to obtain a solution or dispersion containing the fine particles; Analyzing the particles in the solution or dispersion; A method for analyzing fine particles, comprising: [Section 12] A step of collecting fine particles using the water-soluble filter according to any one of items 1 to 6; a step of dissolving the filter that has trapped the fine particles in a solvent, thereby dissolving or dispersing the fine particles in the solvent; A method for recovering fine particles in a solvent, comprising: Effect of the Invention

[0008] According to the present invention, a water-soluble filter having high durability and particle collection efficiency can be provided. [Brief description of the drawings]

[0009] [Figure 1] 1 shows a schematic diagram of the electrospinning process. [Diagram 2] 1 shows a schematic diagram of the measurement of collection efficiency and pressure loss in Example 1. [Diagram 3] 1 shows the arrangement of devices for measuring the particle collection efficiency and pressure loss of a filter in Example 1. [Figure 4] 1 shows the installation position of a filter in an aluminum filter holder in Example 1. [Diagram 5]13 is a graph showing the results of a durability confirmation test in Example 2. [Figure 6] Photographs showing the state of the filter after a durability confirmation test in Example 2. [Figure 7] 1 shows a schematic diagram of particle collection in Example 4. [Figure 8] 13 is a graph showing the results of component analysis of collected particles in Example 4. [Figure 9] 13 is a graph showing the collection mass ratio of the water-soluble filter V1 to the PTFE filter in Example 4. [Figure 10] Photograph of the dust collection device used in Example 5. [Figure 11] 1 shows a schematic diagram of the arrangement of the dust collecting device used in Example 5. [Figure 12] FIG. 13 is a schematic diagram showing the configuration of the collection part of the filter in Example 5. [Figure 13] 13 is a graph showing the results of component analysis of collected particles in Example 5. [Figure 14] FIG. 1 shows a schematic diagram of the WST-1 assay in Example 6. [Figure 15] 1 is a graph showing cell viability in a WST-1 assay for a filter that does not trap particles in Example 5. The graph shows that the water-soluble filter does not affect cell viability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In this specification, the term "water-soluble" broadly includes substances that can be dissolved in water, from substances that can be dissolved in cold water (10° C. or less) to substances that can be dissolved in boiling water (about 100° C.), and also includes substances that can be dissolved in water that contains ionic compounds, proteins, other additives, etc.

[0011] In addition, in this specification, the term "microparticles" broadly includes non-biological particles (e.g., sand dust, sea salt particles, mechanical abrasion dust, engine exhaust particles, photochemically generated particles, etc.) and biological particles (e.g., bacteria, viruses, pollen, etc.) in the particle diameter range of about 5 nm to 100 μm.

[0012] The present invention provides a water-soluble filter, which comprises a nonwoven fabric including fibers containing polyvinyl alcohol. The average fiber diameter of the fibers of the nonwoven fabric is 100 to 300 nm.

[0013] (Polyvinyl alcohol) The polyvinyl alcohol used in the present invention can be produced by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer according to a conventionally known method. Examples of the vinyl ester monomer include vinyl formate, vinyl acetate, vinyl propionate, vinyl valerate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, and vinyl versatate. The vinyl ester monomer may be one or more of these. Among these, vinyl acetate is preferred as the vinyl ester monomer.

[0014] In addition, when polymerizing the vinyl ester monomer, it may be copolymerized with other monomers within the scope that does not impair the object and effect of the present invention. Such other monomers include unsaturated acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, etc., or their salts, or mono- or dialkyl esters, etc.; monomers having sulfonic acid groups such as vinyl sulfonic acid, allyl sulfonic acid, acrylamido-2-methylpropanesulfonic acid, etc., or their salts; vinyloxyethyl trimethylammonium chloride, vinyloxybutyl trimethylammonium chloride, vinyloxyethyl dimethylamine, vinyloxymethyl diethylamine, N-acrylamido methyl trimethylammonium chloride, 3-(N-methacrylamido)propyl trimethylammonium chloride, N-acrylamido ethyl trimethylammonium chloride, N- Examples of the monomer include monomers having a cationic group derived from acrylamide dimethylamine, allyl trimethyl ammonium chloride, methallyl trimethyl ammonium chloride, dimethylallyl amine, allyl ethyl amine, etc.; olefins such as ethylene and propylene; nitriles such as acrylonitrile and methacrylonitrile; amides such as acrylamide and methacrylamide; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; hydroxyl group-containing vinyl ethers such as ethylene glycol vinyl ether and 1,3-propanediol vinyl ether; allyl ethers such as propyl allyl ether; hydroxyl group-containing α-olefins such as 3-buten-1-ol and 4-penten-1-ol, etc. These may be used alone or in combination of two or more.

[0015] The content of these monomers is preferably 5 mol % or less, more preferably less than 2 mol %, further preferably less than 1 mol %, and may be less than 0.5 mol %.

[0016] Furthermore, a functional group may be introduced into the polyvinyl alcohol within the scope of not impairing the object and effect of the present invention. Examples of the functional group include a carboxyl group, a carbonyl group, an amino group, a sulfonic acid group, and an acetoacetyl group.

[0017] The polymerization average molecular weight of the polyvinyl alcohol used in the present invention is preferably 70,000 to 120,000, more preferably 80,000 to 110,000, and particularly preferably 85,000 to 100,000. By being in the above range, a filter having good water solubility and high membrane strength can be obtained. The average polymerization degree can be measured in accordance with JIS K 6726-1994.

[0018] The saponification degree of the polyvinyl alcohol used in the present invention is preferably 95 mol%, more preferably 98 mol%, and particularly preferably 99 mol%. By being in the above range, a filter with good water solubility can be obtained. The saponification degree can be measured according to JIS K 6726-1994.

[0019] In addition, additives may be added to the raw material of the fibers of the nonwoven fabric constituting the water-soluble filter in addition to polyvinyl alcohol, so long as the purpose and effect of the present invention are not impaired. Examples of additives include plasticizers (e.g., polyhydric alcohols such as glycerin, ethylene glycol, and propylene glycol), colorants (e.g., pigments, dyes, etc.), ultraviolet absorbers (e.g., benzophenones, benzotriazoles, triazines, etc.), light stabilizers (e.g., hindered amines, etc.), antioxidants (e.g., phosphorus-based antioxidants, hindered phenol-based antioxidants, thioether-based antioxidants, etc.), antistatic agents (e.g., alkylsulfonates, etc.), flame retardants (e.g., phosphoric acid compounds, metal hydroxides, etc.), lubricants (e.g., wax, glycerin higher fatty acid esters, etc.), etc. These may be used alone or in combination of two or more.

[0020] (Water-soluble filter) The water-soluble filter of the present invention includes a nonwoven fabric containing the above-mentioned polyvinyl alcohol-containing fibers. The water-soluble filter of the present invention may be composed of only the nonwoven fabric, or may have a layer other than the nonwoven fabric, but is preferably composed of only the nonwoven fabric.

[0021] The average fiber diameter of the fibers of the nonwoven fabric is 20 to 300 nm, preferably 50 to 300 nm, more preferably 80 to 250 nm, and particularly preferably 100 to 200 nm. By being in the above range, a filter with high collection efficiency can be obtained. In this specification, the "average fiber diameter" is measured by the method described in the Examples.

[0022] The weight of the nonwoven fabric used in the present invention is 5 to 50 g / m 2 It is preferable that the thickness is 7 to 40 g / m 2 More preferably, the thickness is 10 to 30 g / m 2 It is particularly preferable that the above range is satisfied. By satisfying the above range, a filter having high collection efficiency and low pressure loss can be obtained. In this specification, the "basis weight" is measured by the method described in the Examples.

[0023] The thickness of the nonwoven fabric used in the present invention is preferably 10 to 150 μm, more preferably 20 to 150 μm, further preferably 25 to 120 μm, and particularly preferably 30 to 100 μm. By being in the above range, a filter with high collection efficiency and low pressure loss can be obtained. In this specification, the "thickness" is measured by the method described in the examples.

[0024] The water temperature when dissolving the water-soluble filter of the present invention can be appropriately adjusted depending on the purpose, but the higher the water temperature, the higher the dissolution rate. When dissolving with hot water, the water temperature is preferably 50°C or higher, more preferably 60°C or higher, even more preferably 70°C or higher, and particularly preferably 80°C or higher.

[0025] In one embodiment, the water-soluble filter of the present specification dissolves preferably within 1 hour, more preferably within 45 minutes, and particularly preferably within 30 minutes when 1 part by mass of the water-soluble filter is mixed with 100 parts by mass of water and stirred at 80 to 90° C. By being able to dissolve under the above conditions, the fine particles captured by the water-soluble filter can be easily subjected to biological analysis.

[0026] The water-soluble filter of the present invention preferably has a pressure loss of 300 Pa or less, more preferably 270 Pa or less, more preferably 240 Pa or less, and particularly preferably 210 Pa or less, at a linear air flow velocity of 0.6 to 0.9 cm / s. In this specification, the "pressure loss" is measured by the method described in the Examples.

[0027] The water-soluble filter of the present invention preferably has a collection efficiency of 95% or more, more preferably 97% or more, and particularly preferably 98% or more, for fine particles having a particle diameter of 0.3 μm or more and 10 μm or less at a linear air velocity of 0.6 to 0.9 cm / s. In this specification, the "collection efficiency of fine particles" is measured by the method described in the Examples.

[0028] The water-soluble filter of the present invention has a total collection period from the start of collection until the collection efficiency of fine particles having a particle diameter of 0.3 μm or more and 10 μm or less drops to less than 90% at a linear air velocity of 0.6 to 0.9 cm / s, which is preferably 24 hours or more, more preferably 48 hours or more, even more preferably 96 hours or more, and particularly preferably 168 hours or more. Such a water-soluble filter has excellent durability.

[0029] (Method of manufacturing water-soluble filters) The method for producing the water-soluble filter of the present invention is not particularly limited as long as it satisfies the above physical properties, but it is preferable to produce the filter by electrospinning, which makes it possible to easily produce a filter with high collection efficiency.

[0030] In one embodiment, the water-soluble filter of the present invention can be produced by a method comprising the following steps (i) and (ii): (i) preparing a 2 to 20 w / v % polyvinyl alcohol solution; (ii) forming a nonwoven fabric by electrospinning the solution.

[0031] In step (i), the concentration of polyvinyl alcohol in the polyvinyl alcohol solution is preferably 5 to 20 w / v%, more preferably 7 to 15 w / v%, and particularly preferably 10 to 12 w / v%. By being in the above range, fibers having a preferred fiber diameter can be obtained, and a filter with high collection efficiency can be obtained.

[0032] In step (i), the solvent for dissolving polyvinyl alcohol may be, for example, water, methanol, ethanol, acetone, acetic acid, etc., but preferably contains at least water. Water may be mixed with another solvent. When water is mixed with another solvent, the ratio of water to another solvent is preferably in the range of 7:3 to 10:0, more preferably in the range of 8:2 to 10:0. By being in the above range, fibers with a preferred fiber diameter can be obtained, and a filter with high collection efficiency can be obtained.

[0033] In the step (i), when preparing the polyvinyl alcohol solution, ultrasonic treatment may be performed. The ultrasonic treatment time is not particularly limited, but may be, for example, about 0.1 to 2 hours.

[0034] In step (ii), the electrospinning method can be carried out, for example, as follows. The polyvinyl alcohol solution is extruded from a spinning nozzle, and at that time, a high voltage is applied to the spinning nozzle side, and an electric field is applied to the solution to stretch it into nanofibers, and the nanofibers are deposited on the counter electrode side. Note that a voltage may be applied to the counter electrode side instead of the spinning nozzle side, and an electric field may be applied between the spinning nozzle and the counter electrode.

[0035] The direction in which the polyvinyl alcohol solution is extruded is not particularly limited, but in order to prevent the solution from dripping, it is preferable that the extrusion direction from the nozzle does not coincide with the direction of gravity, and it is more preferable to extrude the solution in a horizontal direction.

[0036] The inner diameter of the nozzle for extruding the polyvinyl alcohol solution is preferably 0.1 to 5 mm, more preferably 0.2 to 3 mm, and particularly preferably 0.5 to 2 mm. By keeping the inner diameter within the above range, fibers having a preferred fiber diameter can be obtained, and a filter with high collection efficiency can be obtained.

[0037] The extrusion rate of the polyvinyl alcohol solution is preferably 0.2 to 0.8 mL / h, more preferably 0.3 to 0.7 mL / h, and particularly preferably 0.4 to 0.6 mL / h. By keeping the rate within the above range, droplets are less likely to form, and fibers with a uniform fiber diameter can be obtained.

[0038] The distance from the nozzle tip to the collector (collection distance) is preferably 5 to 25 cm, more preferably 10 to 20 cm, and particularly preferably 12 to 18 cm. By being in the above range, a nonwoven fabric with a preferable basis weight can be obtained, and a filter with high collection efficiency can be obtained.

[0039] The applied voltage is preferably 1 to 30 kV, more preferably 5 to 25 kV, and particularly preferably 10 to 20 kV. By keeping the voltage within the above range, fibers having a preferred fiber diameter can be obtained, and a filter with high collection efficiency can be obtained.

[0040] The spinning time is preferably 0.5 to 10 hours, more preferably 1 to 7 hours, and particularly preferably 1 to 3 hours. Within the above range, a nonwoven fabric having a desired thickness is obtained, and water solubility and pressure loss are good.

[0041] The relative humidity during electrospinning is preferably 10 to 70%, and more preferably 20 to 65%. When the relative humidity is within the above range, the drying speed of the fibers is improved, and the fibers can be easily formed.

[0042] The polyvinyl alcohol nanofibers may be directly accumulated on a collector, or may be accumulated on an aggregate such as a substrate placed on the collector. The aggregate is not particularly limited, but examples thereof include conductive materials made of metals or carbon, and non-conductive materials made of organic polymers. The shape is appropriately set depending on the application of the resulting nonwoven fabric, and is not particularly limited, but examples thereof include flat, circular, and annular shapes.

[0043] (Uses of water-soluble filters, etc.) In one embodiment, a method for collecting fine particles using the water-soluble filter of the present invention is provided. The method for collecting fine particles is not particularly limited, but examples thereof include (i) a method in which the water-soluble filter of the present invention is placed in an environment in which the fine particles to be collected are present, and the fine particles in the environment are attached to the water-soluble filter to collect them; (ii) a method in which the water-soluble filter of the present invention is connected to a pump or the like in an environment in which the fine particles to be collected are present, and the fine particles in the environment are collected by colliding with the water-soluble filter; (iii) a method in which the water-soluble filter of the present invention is attached to an electrode plate and placed in an environment in which the fine particles to be collected are present, and the fine particles in the environment are collected by electrical force; and (iv) a method in which the water-soluble filter of the present invention is connected to a pump or the like in an environment in which the fine particles to be collected are present, and the fine particles in the environment are collected by filtering them with the water-soluble filter. By using the water-soluble filter of the present invention, fine particles with a particle diameter of 0.3 μm to 10 μm can be collected with a collection efficiency of 95% or more at an air flow linear velocity of 0.6 to 0.9 cm / s.

[0044] In another embodiment, there is provided a method for analyzing fine particles using the water-soluble filter of the present invention.

[0045] In one embodiment, the method for analyzing microparticles comprises the following steps (a1) and (a2). (a1) A step of collecting fine particles using the water-soluble filter of the present invention. (a2) A step of analyzing the particulate matter captured on the filter while it is retained on the filter.

[0046] The step (a1) includes a collection step under the conditions described above for the method of collecting fine particles using a water-soluble filter.

[0047] Step (a2) includes a step of performing a non-destructive particle analysis of the filter, such as X-ray fluorescence analysis (XRF) or microscopic analysis, while the particles are retained on the filter.

[0048] In another embodiment, the method for analyzing microparticles comprises the following steps (b1), (b2) and (b3). (b1) A step of collecting fine particles using the water-soluble filter of the present invention. (b2) A step of dissolving the filter that has collected the fine particles in a solvent to obtain a solution or dispersion containing the fine particles. (b3) Analyzing the particles in the solution or dispersion.

[0049] Step (b1) includes a collection step under the conditions described above for the method of collecting fine particles using a water-soluble filter.

[0050] In step (b2), the solvent for dissolving the filter that has captured the fine particles preferably contains water. The solvent may contain, in addition to water, other organic solvents (e.g., ethanol, DMSO, etc.) and medium components (e.g., αMEM medium, Neurobasal medium, Neural Progenitor Basal medium, NS-A medium, BME medium, BGJb medium, CMRL 1066 medium, Minimum Essential Medium (MEM), GMEM medium, Dulbecco's Modified Eagle Medium (DMEM), Glasgow MEM medium, Improved MEM Zinc Option medium, IMDM medium, Medium 199 medium, DMEM / F12 medium, StemPro-34SFM medium, Ham's medium, RPMI 1640 medium, HTF medium, etc.), additives (for example, growth factors, polyamines, minerals, sugars, organic acids, amino acids, reducing agents, vitamins, steroids, antibiotics, buffering agents, nutritional additives, etc.), electrolytes (sodium ions, ammonium ions, potassium ions, magnesium ions, calcium ions, chloride ions, nitrate ions, sulfate ions, etc.), inorganic acids (hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, hydrofluoric acid, etc.), alkalis (sodium hydroxide, potassium hydroxide, etc.), etc.

[0051] The concentration of the filter that collects the microparticles in the above solvent is appropriately selected depending on the analysis method in step (b3) and is not particularly limited, but is preferably, for example, 0.1 to 6 w / v%, and more preferably 0.2 to 4 w / v%.

[0052] When dissolving the filter that has collected the fine particles in the solvent, the solution may be heated as necessary. When the temperature of the solvent is 50 to 90° C., preferably 70 to 90° C., the time required to dissolve the filter in the solvent can be shortened.

[0053] Step (b3) includes, for example, analytical steps such as a cell exposure test, a microbial culture experiment, a nucleic acid extraction experiment, atomic spectrometry (atomic absorption spectrometry (AAS), inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS), etc.), ion chromatography, etc. In particular, in a cell exposure test, etc., since the water-soluble filter of the present invention has no cytotoxicity, the cytotoxicity, etc. of the fine particles captured by the filter can be evaluated.

[0054] In another embodiment, a method for recovering fine particles in a solvent using the water-soluble filter of the present invention is provided.

[0055] In one embodiment, the method for recovering microparticles into a solvent comprises the following steps (c1) and (c2). (c1) A step of collecting fine particles using the water-soluble filter of the present invention. (c2) A step of dissolving or dispersing the fine particles in a solvent by dissolving the filter that has collected the fine particles in the solvent.

[0056] Step (c1) includes a collection step under the conditions described above for the method of collecting fine particles using a water-soluble filter.

[0057] Step (c2) includes the steps described above in step (b2).

[0058] As described above, the water-soluble filter of the present invention is suitable for use in capturing and analyzing fine particles. Since the water-soluble filter of the present invention has excellent durability and is water-soluble, the fine particles captured by the water-soluble filter of the present invention can be subjected to a wide range of analyses, including chemical analyses and biological analyses. EXAMPLES

[0059] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0060] [Evaluation items and evaluation methods] (1) Filter thickness measurement After the filter was coated with osmium for conductive treatment, the filter was measured at 10 points around its periphery using an environmentally controlled scanning electron microscope (ESEM, FEI, Inspect S50), and the average value was calculated to obtain the film thickness.

[0061] (2) Measurement of average fiber diameter The filter was cut into approximately one-eighth of a sector using scissors, and was then coated with osmium for electrical conductivity. It was then photographed using a field emission scanning electron microscope (FE-SEM, JEOL Ltd., JSM-7600F). The fiber diameters at 10 points were measured using ImageJ, and the average value was calculated to obtain the average fiber diameter.

[0062] (3) Metsuke The filter was cut into 20 mm square pieces with scissors, and the weight was measured three times using a precision balance (A&D, BM-252) to calculate the average weight, which was used as the basis weight.

[0063] <Production Example 1> Production of water-soluble filter V1 A polypropylene clear file was cut with a compass cutter into a ring with an outer diameter of 46 mm and an inner diameter of 40 mm to create a frame.

[0064] 1.1 g of polyvinyl alcohol (Sigma-Aldrich, weight average molecular weight 89,000 to 98,000, saponification degree 99.0 to 99.8 mol%) was added to 10 mL of a solvent of water:ethanol=9:1 and dissolved by stirring at 87° C. for 30 minutes.

[0065] Using the above solution, a water-soluble filter V1 was produced by electrospinning. A schematic diagram of the electrospinning method is shown in Figure 1. The frame produced above was placed on the collector 1, and the above solution was placed in a 1.5 mL syringe 2. The electrospinning method was carried out with a solution extrusion speed of 0.5 mL / h, a syringe nozzle diameter of 20 gauge, a collection distance (distance from the nozzle tip to the collector 1) of 15 cm, an applied voltage of 15.0 kV, and a spinning time of 3 hours.

[0066] The obtained water-soluble filter V1 had a film thickness of 49.4±13.1 μm, a fiber diameter of 162±49 nm, and a basis weight of 19.4±8.4 g / m 2 It was.

[0067] <Production Example 2> Production of water-soluble filter V2 Except for changing the spinning time to 6 hours, a water-soluble filter V2 was produced in the same manner as in Production Example 1. The obtained water-soluble filter V2 had a film thickness of 89.6±26.4 μm and a fiber diameter of 149±50 nm.

[0068] <Production Example 3> Production of water-soluble filter V3 Except for changing the spinning time to 9 hours, a water-soluble filter V3 was produced in the same manner as in Production Example 1. The obtained water-soluble filter V3 had a film thickness of 126±10 μm and a fiber diameter of 217±89 nm.

[0069] Example 1: Collection efficiency measurement The collection efficiency and pressure loss of the water-soluble filter V1 were measured (n=15). A schematic diagram of the collection efficiency and pressure loss measurement is shown in Figure 2. Figure 3 shows the layout of the device, and Figure 4 shows the details of the filter installation position. (Experimental Equipment) Light scattering particle counter: Rion Co., Ltd., airborne particle counter KC-01E (flow rate 0.5 L / min, particle size 0.3-10 μm, 20 sec count) Mini pump for flow control: Nitto Kohki VP0125 (ultimate vacuum level -33.3 kPa, discharge air volume 7 L / min) Mass flow controller: KOFLOC 8500MC (flow rate 0.5 L / min (20℃ 1 atm)) Mass flow meter: Bronkhost, Mass-Stream (flow rate 0.1~20 L / min) Differential pressure gauge: Yamamoto Electric Works, Manostar WO81FN200D (maximum differential pressure 200 Pa (change range as necessary)) ·Thermohygrometer: Manufactured by T&D, TR-72wb Filter holder: Tokyo Dylec MCI holder (filter diameter 47 mm, effective diameter 40.5 mm) Introduced particles: Particles in the air in the laboratory

[0070] (Measuring procedure for collection efficiency and pressure loss) (1) The instrumental difference between two light scattering particle counters was measured three times. (2) The filter to be measured (water-soluble filter V1) was cut to 47 mmΦ and set in the holder. (3) The flow rate and differential pressure at the inlet were measured in the (2) condition. (4) Two light scattering particle counters were started and three measurements were recorded for 20 seconds each. (5) Replace the filter and perform steps (2) to (4) in sequence. (6) Finished after all filters were tested.

[0071] The linear air flow rates were as follows: Effective filter area: 12.88 cm 2 , 40.5mmΦ ·Flow rate 0.5 L / min Linear air velocity: 0.65 cm / s The collection efficiency was calculated according to the following formula.

[0072]

number

[0073] The results are shown in Table 1.

[0074] It was revealed that the water-soluble filter V1 had a high collection efficiency of nearly 100% for all particle ranges.

[0075] [Table 1]

[0076] <Example 2> Durability confirmation test The durability of the water-soluble filter V1, gelatin filter (Type 126, manufactured by Sartorius), and PTFE filter (PM2.5 PTFE Membrane Filter 7592-104, manufactured by Cytiva) was confirmed.

[0077] Specifically, the collection efficiency (on the first day) of each filter in the particle diameter range of 0.3 to 10 μm was measured, and then the filter was stored in a plastic bag with a zipper (Unipack, manufactured by Seisan Nippon Sha) for 24 hours, after which the collection efficiency (on the second day) in the particle diameter range of 0.3 to 10 μm was measured again (n=3). The measurement of the collection efficiency was performed in the same manner as in Example 1. The linear air flow velocity was 0.52 to 0.65 cm / s, and the filter area was 12.88 cm. 2 The results are shown in Table 2 and Figure 5.

[0078] On the second day of measurement, damage was confirmed in the gelatin filter, but no damage was confirmed in the water-soluble filter V1 or the PTFE filter (Figure 6). It was revealed that the water-soluble filter V1, unlike the gelatin filter, has the same durability as the PTFE filter.

[0079] [Table 2]

[0080] <Example 3> Solubility test One water-soluble filter V1 was divided into two, one of which was added to a 10 mL centrifuge tube with 5 mL of water, and the other was added to a 10 mL centrifuge tube with 2.5 mL of water. Then, each centrifuge tube was placed in a hot water bath and shaken, and the temperature at which dissolution was confirmed visually was recorded. The temperature of the hot water bath was started at 60°C and was raised at a rate of about 4°C / min. The same procedure was carried out for water-soluble filters V2 and V3, and the temperatures were also recorded. The results are shown in Table 3.

[0081] From these results, it was clear that all of the water-soluble filters V1 to V3 were soluble in water, which is a major difference from insoluble filters such as PTFE filters.

[0082] [Table 3]

[0083] <Example 4> Chemical analysis of collected dust Using a constant flow multi-sampler (SilVy-5, Asian Journal of Atmospheric Environment, 2021, 15(1), 52-67), water-soluble filter V1 and PTFE filter were placed as shown in Figure 7, and particles were collected outdoors at a flow rate of 12 to 13 L / min from 16:00 on November 17, 2022 to 11:00 on November 24, 2022. The filter was then subjected to component analysis of the particles collected using an energy dispersive X-ray fluorescence analyzer (EDXRF, Rigaku Corporation, EDXL300). The results are shown in Figures 8 and 9. Figure 8 shows the average amount of elements in the particles collected by the water-soluble filter and the average amount of elements in the particles collected by the PTFE filter in the total volume of ventilated air. Figure 9 also shows the results of comparing the average amount of elements in the particles collected by the water-soluble filter with the average amount of elements in the particles collected by the PTFE filter.

[0084] These results demonstrate that the water-soluble filter V1 can be used for chemical analysis in the same manner as a PTFE filter, and that it has the same particle collection capacity as a PTFE filter.

[0085] <Example 5> Chemical analysis of collected dust 2 JIS test powder 1 (Kanto loam, type 11) was scattered every 5 minutes at a location about 30 cm downwind from the outlet of an electric fan (Vornado Circulator 293HD-JP) and collected in a water-soluble filter V1 for 20 minutes (Figure 10). A schematic diagram of the device layout is shown in Figure 11 (space volume 8 m 3The outline of the filter collection section is shown in Figure 12. The pump flow rate was 16 L / min.

[0086] The particles collected from the filter were then analyzed for components using an energy dispersive X-ray fluorescence analyzer (EDXRF, Rigaku Corporation, EDXL300). The results are shown in Figure 13.

[0087] These results also demonstrated that the water-soluble filter V1 can be subjected to chemical analysis similar to that of a PTFE filter, and that it has the same particle collection ability as a PTFE filter.

[0088] Example 6: Cell exposure experiment of water-soluble filter To confirm whether the water-soluble filter V1 affects cell viability, a cell exposure experiment (WST-1 assay) was performed using the filter dissolution solution. A schematic diagram of the WST-1 assay is shown in Figure 14.

[0089] First, A549 cells were seeded in a 96-well plate at a concentration of 2,500 cells / well, and the samples were exposed after 72 hours. The filter dissolution solution was prepared as follows.

[0090] (1) One water-soluble filter V1 was placed in a centrifuge tube, and 2.5 mL of medium (Ham's F-12K (Kaighn's) Medium, Thermo Fisher Scientific) was added. (2) Vortex for approximately 15 seconds. (3) The centrifuge tube was placed in a 65°C water bath and heated for 30 minutes, after which the temperature of the water bath was set to 85°C and heated for an additional 30 minutes to dissolve the water-soluble filter V1. (4) The same procedures as in (1) to (3) were carried out on another water-soluble filter V1, and a WST-1 assay was performed (n=2).

[0091] As a blank sample, 2.5 mL of medium alone was placed in a centrifuge tube, and the solution was prepared in the same manner as above. As a control, only cell medium was added. At this time, a 96-well plate without cells was also prepared, and samples were added under the same conditions as the plate with cells, and incubated in the same manner as the plate with cells.

[0092] After 24 hours of exposure, the absorbance was measured. First, 10 μL of WST-1 reagent was added to each well of both the plate with cells and the plate without cells. The plate without cells was used as a blank plate, and one hour after adding the WST-1 solution, the absorbance was measured at 450 nm / 630 nm using the Premix WST-1 Cell Proliferation Assay System (RaKaRa Bio). The formula for calculating cell viability is as follows:

[0093]

number

[0094] The statistical software "EZR" was used to test the significance of the results using the Dunnett method. The control group was compared with the other sample groups, and a significant difference was determined when P<0.05. The results are shown in Figure 15.

[0095] These results demonstrate that the water-soluble filter V1, which does not trap particles, has almost no effect on cell viability. [Explanation of symbols]

[0096] 1. Collector 2 Syringes 3. Pump 4 Power supply

Claims

1. A water-soluble filter for collecting fine particles, A nonwoven fabric including fibers containing polyvinyl alcohol, The water-soluble filter, wherein the average fiber diameter of the fibers of the nonwoven fabric is 20 to 300 nm.

2. The nonwoven fabric has a basis weight of 5 to 50 g / m ２ 2. The water-soluble filter according to claim 1, having a thickness of 10 to 150 μm.

3. 2. The water-soluble filter according to claim 1, wherein the weight-average molecular weight of the polyvinyl alcohol is from 70,000 to 120,000.

4. The water-soluble filter according to claim 1, which dissolves within 1 hour when 1 part by mass of the water-soluble filter is mixed with 100 parts by mass of water and stirred at 80 to 90°C.

5. 2. The water-soluble filter according to claim 1, which has a pressure loss of 300 Pa or less at a linear air velocity of 0.6 to 0.9 cm / s and a collection efficiency of 95% or more for fine particles having a particle diameter of 0.3 μm or more and 10 μm or less.

6. 2. The water-soluble filter according to claim 1, which is used for collecting and analyzing fine particles.

7. A method for producing the water-soluble filter according to claim 1 , which comprises using an electrospinning method.

8. preparing a 5-20 w / v % polyvinyl alcohol solution; The method according to claim 7 , further comprising forming a nonwoven fabric by electrospinning the solution.

9. A method for collecting fine particles, which uses the water-soluble filter according to claim 1.

10. A step of collecting fine particles using the water-soluble filter according to claim 1; analyzing the particles captured on the filter while they are retained on the filter; A method for analyzing fine particles, comprising:

11. A step of collecting fine particles using the water-soluble filter according to claim 1; a step of dissolving the filter on which the fine particles have been collected in a solvent to obtain a solution or dispersion containing the fine particles; Analyzing the particles in the solution or dispersion; A method for analyzing fine particles, comprising:

12. A step of collecting fine particles using the water-soluble filter according to claim 1; a step of dissolving the filter that has collected the fine particles in a solvent, thereby dissolving or dispersing the fine particles in the solvent; A method for recovering fine particles in a solvent, comprising:

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