Method for producing magnetic polymer particle

Abstract

To provide a method for producing magnetic polymer particles that enables magnetic polymer particles in various particle sizes to be produced at room temperature and in a short time.SOLUTION: The present disclosure relates to a method for producing magnetic polymer particles. The production method includes: an introduction step for swelling polymer particles and introducing magnetic materials into the swollen polymer particles; and a shrinkage step for shrinking the polymer particles with the magnetic material introduced.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for producing magnetic polymer particles. [Background technology]

[0002] Magnetic polymer particles are widely used in the fields of life sciences, such as for the recovery or detection of DNA or viruses, and in the fields of clinical testing using chemiluminescence immunoassays, and research and development of magnetic polymer particles themselves is being actively conducted.

[0003] For example, Patent Document 1 discloses a method for producing magnetic polymer particles by emulsion polymerization. Patent Document 2 discloses a method for producing magnetic polymer particles by mini-emulsion polymerization. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 081917 [Patent Document 2] International Publication No. 2017 / 204209 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the methods for producing magnetic polymer particles disclosed in the above-mentioned prior art documents have limitations on the particle size of the magnetic polymer particles that can be produced. In addition, the magnetic polymer particles need to be heated and stirred during production, which takes a long time to produce.

[0006] An object of one aspect of the present invention is to provide a method for producing magnetic polymer particles, which is capable of producing magnetic polymer particles of various particle sizes at room temperature in a short period of time. [Means for solving the problem]

[0007] As a result of intensive research, the present inventors have found that by introducing a magnetic material into swollen polymer particles, magnetic polymer particles of various particle sizes can be produced in a short time. Furthermore, they have found that magnetic polymer particles can be produced even at room temperature, and have completed the present invention.

[0008] In order to solve the above problems, a method for producing magnetic polymer particles according to one embodiment of the present invention is a method for producing magnetic polymer particles, which includes an introduction step of swelling polymer particles and introducing a magnetic material into the swollen polymer particles, and a contraction step of contracting the polymer particles into which the magnetic material has been introduced. Effect of the Invention

[0009] According to one aspect of the present invention, magnetic polymer particles of various particle sizes can be produced at room temperature and in a short period of time. [Brief description of the drawings]

[0010] [Figure 1] 1 shows the results of observation of the magnetic polymer particles obtained in Example 1 with an electron beam microanalyzer. [Diagram 2] 1 shows the results of elemental analysis of the magnetic polymer particles obtained in Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] One aspect of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to each configuration described below, and various modifications are possible within the scope of the claims. In addition, the embodiments and examples obtained by appropriately combining the technical means disclosed in the embodiments and examples are also included in the technical scope of the present invention. In addition, in this specification, "A to B" indicates A or more and B or less, unless otherwise specified.

[0012] The method for producing magnetic polymer particles according to one embodiment of the present invention (hereinafter, may be referred to as "this production method") includes an introduction step and a shrinking step which will be described later.

[0013] In this specification, the term "magnetic polymer particles" refers to particles in which a magnetic substance is encapsulated in a polymer particle.

[0014] [Introduction process] In the above-mentioned introduction step, the polymer particles are swollen and the magnetic material is introduced into the swollen polymer particles. According to the introduction step, the magnetic material can be introduced into the swollen polymer particles at room temperature (10°C to 40°C) in a short time. The temperature of the introduction step is preferably 15°C to 25°C in terms of operability, etc.

[0015] (Polymer particles) Examples of the polymer particles used in the present manufacturing method include polymer particles containing structural units derived from aromatic vinyl compounds. Examples of aromatic vinyl compounds include styrene, vinylnaphthalene, divinylbenzene, vinyltoluene, vinylnaphthalene, vinylanthracene, and vinylpyridine, or derivatives thereof. These aromatic vinyl compounds may be used alone or in combination of two or more. Among these, styrene-based compounds, which are styrene or styrene derivatives, are preferred because they are easy to manufacture spherical particles.

[0016] Examples of styrene derivatives include alkyl styrenes such as methyl styrene, ethyl styrene, propyl styrene, t-butyl styrene, cyclohexyl styrene, dodecyl styrene, and dimethyl styrene; halogenated styrenes such as monochlorostyrene, dichlorostyrene, monobromostyrene, and dibromostyrene; alkoxy styrenes such as methoxy styrene, ethoxy styrene, propoxy styrene, and butoxy styrene; carboxy styrenes such as carboxy styrene; amino styrenes such as 4-amino styrene, dimethyl amino styrene, and diethyl amino styrene; hydroxy styrenes; and isomers thereof.

[0017] The structural unit derived from the aromatic vinyl compound may have a functional group for surface modification of the produced magnetic polymer particles. Examples of the functional group include a carboxy group, an amino group, a sulfo group, and an epoxy group.

[0018] The polymer particles may be crosslinked or uncrosslinked. For example, depending on the type of aprotic solvent described later, either the crosslinked or uncrosslinked polymer particles may be selected.

[0019] The polymer particles containing structural units derived from aromatic vinyl compounds may contain structural units derived from compounds other than aromatic vinyl compounds.Examples of the other monomers include polymerizable unsaturated carboxylic acids such as itaconic acid, maleic acid, and fumaric acid; polymerizable unsaturated sulfonic acids or their salts such as sodium styrenesulfonate; polymerizable carboxylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, ethylene glycol-di-methacrylic acid ester, and tribromophenyl methacrylate; unsaturated carboxylic acid amides such as methacrylonitrile, methacrylamide, N-methylol methacrylamide, methylene bis methacrylamide, butadiene, isoprene, vinyl acetate, vinylpyridine, N-vinylpyrrolidone, vinyl chloride, vinylidene chloride, and vinyl bromide; polymerizable unsaturated nitriles; vinyl halides; conjugated dienes; and the like.

[0020] The content of the structural unit derived from the aromatic vinyl compound in the polymer particles is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more, based on 100% by mass of the polymer particles, in order to obtain magnetic polymer particles having high strength. The content of the structural unit derived from the aromatic vinyl compound in the polymer particles may be 100% by mass.

[0021] In order to make the magnetic polymer particles usable for various purposes, the number average particle diameter of the polymer particles is preferably within the range of 0.1 to 1.0 μm, more preferably 0.1 to 0.5 μm, and even more preferably 0.1 to 0.3 μm. The number average particle diameter can be measured, for example, by a dynamic light scattering method or a laser diffraction / scattering method.

[0022] The weight average molecular weight of the polymer particles is preferably within a range of 1,000 to 1,000,000, more preferably 5,000 to 800,000, and further preferably 10,000 to 600,000.

[0023] The polymer particles may be commercially available polymer particles or may be polymer particles obtained by a known polymerization method such as microemulsion polymerization, emulsion polymerization, miniemulsion polymerization, dispersion polymerization, soap-free polymerization, seed polymerization, suspension polymerization, etc.

[0024] (magnetic material) The magnetic material used in the present production method may be any of ferromagnetic, paramagnetic, and superparamagnetic magnetic materials. In terms of excellent magnetic collection and redispersibility, the magnetic material is preferably superparamagnetic. Examples of magnetic materials include metals and alloys such as ferrite, iron oxide, iron, manganese oxide, manganese, nickel oxide, nickel, cobalt oxide, and cobalt. In terms of excellent sensitivity to magnetic fields, low cost, and low toxicity, the magnetic material is preferably iron oxide.

[0025] From the viewpoint of dispersibility and ease of introduction into polymer particles, the magnetic material is preferably coated with a long-chain fatty acid. In this specification, the long-chain fatty acid refers to a saturated fatty acid or an unsaturated fatty acid having 6 or more carbon atoms in the entire fatty acid. Examples of the long-chain fatty acid include caprylic acid, lauric acid, myristic acid, palmitic acid, stearic acid, linolenic acid, linoleic acid, oleic acid, and 5-phenylvaleric acid.

[0026] In terms of ease of introduction into polymer particles, the number average particle size of the magnetic material is preferably from 0.1 nm to 50 nm, more preferably from 1 to 40 nm, and even more preferably from 1 to 20 nm.

[0027] In the present production method, the magnetic substance may be a commercially available product. An example of a commercially available magnetic substance coated with a long-chain fatty acid is EMG1400, a magnetic nanoparticle for biomedical use, manufactured by Ferrotec Corporation.

[0028] For example, the polymer particles can be swollen by absorbing a solvent into the polymer particles and expanding the volume of the polymer particles. The solvent absorbed into the polymer particles can be appropriately selected depending on the type of the polymer particles, and examples of the solvent include aprotic solvents described below. The swollen polymer particles have a volume expanded by, for example, 50 to 800% compared to the polymer particles before swelling.

[0029] The present manufacturing method preferably further includes a magnetic material dispersion preparation step of dispersing a magnetic material in an aprotic solvent to prepare a magnetic material dispersion, and a polymer particle dispersion step of dispersing polymer particles in a protic solvent to prepare a polymer particle dispersion. By contacting the magnetic material dispersion prepared in the magnetic material dispersion preparation step with the polymer particle dispersion prepared in the polymer particle dispersion step, the polymer particles come into contact with the aprotic solvent, which is the dispersion medium of the magnetic material dispersion. Then, the polymer particles swell by absorbing the aprotic solvent. Furthermore, at the interface between the aprotic solvent and the protic solvent, the magnetic material is introduced into the swollen polymer particles. By these steps, magnetic polymer particles can be manufactured easily and in a short time. Note that the specific method of the introduction step of the present manufacturing method is not limited to such a form. For example, a method such as using pre-swollen polymer particles can be adopted.

[0030] (Magnetic dispersion) The aprotic solvent used in the magnetic material dispersion liquid preparation step is preferably a hydrophobic aprotic solvent in terms of affinity with polymer particles and dispersibility of the magnetic material. Examples of hydrophobic aprotic solvents include aromatic hydrocarbon solvents such as toluene; halogenated hydrocarbon solvents such as chlorobenzene, chloroform, and dichloromethane; aliphatic hydrocarbon solvents such as cyclohexane; esters such as ethyl acetate; ethers such as tetrahydrofuran; ketones such as cyclohexanone and acetone; and the like. These aprotic solvents may be used alone or in combination of two or more. In terms of ease of introduction of the magnetic material into the polymer particles, the hydrophobic aprotic solvent is more preferably an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, or a halogenated hydrocarbon, and more preferably an aromatic hydrocarbon solvent.

[0031] The concentration of the magnetic material in the magnetic material dispersion is preferably 0.1 to 1000 mg / mL, more preferably 1.0 to 500 mg / mL, and even more preferably 10 to 200 mg / mL, from the viewpoints of ease of introduction of the magnetic material into polymer particles and dispersibility of the magnetic material.

[0032] (Polymer particle dispersion) The protic solvent used in the polymer particle dispersion process is preferably an aqueous solvent, an alcoholic solvent, or a mixed solvent of an aqueous solvent and an alcoholic solvent, from the viewpoint of ease of introduction of the magnetic material into the swollen polymer particles at the interface between the aprotic solvent and the protic solvent, and is more preferably an aqueous solvent.

[0033] Examples of aqueous solvents include water and buffer solutions. Examples of buffer solutions include MES (2-(N-morpholino)ethanesulfonic acid), Bis-Tris (bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane), ADA (N-(2-acetamido)iminodiacetic acid), PIPES (piperazine-1,4-bis(2-ethanesulfonic acid) sesquisodium salt monohydrate), ACES (N-(2-acetamido)-2-aminoethanesulfonic acid), MOPSO (2-hydroxy-3-morpholinopropanesulfonic acid), BES (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid), MOPS (3-morpholinopropanesulfonic acid), TES (N-tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid), HEPES (2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid), TAPSO (N- [tris(hydroxymethyl)methyl]-3-amino-2-hydroxypropanesulfonic acid), POPSO (piperazine-1,4-bis(2-hydroxy-3-propanesulfonic acid) dihydrate), HEPSO (2-hydroxy-3-[4-(2-hydroxyethyl)-1-piperazinyl]propanesulfonic acid) monohydrate), EPPS (3-[4-(2-hydroxyethyl)-1-piperazinyl]propanesulfonic acid), Tricine (N-[tris(hydroxymethyl)methyl]glycine), Bicine (N,N-bis(2-hydroxyethyl)glycine), TAPS (N-tris(hydroxymethyl)methyl-3-aminopropanesulfonic acid), CHES (N-cyclohexyl-2-aminoethanesulfonic acid), CAPS ((3-cyclohexylamino)-1-propanesulfonic acid), and the like. These aqueous solvents may be used alone or in combination of two or more.

[0034] In order to improve the dispersibility of the polymer particles, the pH of the aqueous solvent may be appropriately adjusted. The pH can be adjusted using an inorganic base, an inorganic acid, an organic base or an organic acid. The pH of the aqueous solvent is preferably in the range of 3 to 12, more preferably 5 to 10, and even more preferably 6 to 8. When the pH of the aqueous solvent is in the range of 6 to 8, it is suitable for application in life science applications.

[0035] Examples of the alcohol-based solvent include methanol, ethanol, propanol, butanol, heptanol, hexanol, glycerin, etc. These alcohol-based solvents may be used alone or in combination of two or more kinds.

[0036] The aqueous solvent contained in the mixed solvent of the aqueous solvent and the alcoholic solvent may be 60% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more.

[0037] The protic solvent used in the polymer particle dispersion process preferably contains a surfactant in order to improve the dispersibility of the polymer particles. Examples of surfactants include nonionic surfactants. In order to increase the dispersion stability of the polymer particles, hydrocarbon-based nonionic surfactants are preferred. Examples of hydrocarbon-based nonionic surfactants include Pluronic (registered trademark) F-127 (PF-127, containing 0.025% 2,6-di(tert-butyl)-p-cresol, manufactured by Sigma Aldrich) manufactured by Biotium.

[0038] The surfactant concentration in the protic solvent may be, for example, 1 to 5% by mass.

[0039] The concentration of polymer particles in the polymer particle dispersion is preferably 1.0 to 1000 mg / mL, more preferably 1.0 to 500 mg / mL, and even more preferably 1.0 to 200 mg / mL, from the viewpoints of ease of introduction of the magnetic material into the swollen polymer particles and dispersibility.

[0040] For example, the magnetic material dispersion liquid and the polymer particle dispersion liquid can be contacted by mixing or stirring the magnetic material dispersion liquid and the polymer particle dispersion liquid. The contact time between the magnetic material dispersion liquid and the polymer particle dispersion liquid can be appropriately selected depending on the type and particle size of the magnetic material and the type and particle size of the polymer particles, and may be, for example, 5 minutes to 6 hours.

[0041] [Shrinkage process] In the shrinking step, the polymer particles having the magnetic material introduced therein obtained in the introducing step are shrunk. By shrinking the polymer particles having the magnetic material introduced therein, it is possible to prevent the magnetic material introduced in the polymer particles from being released outside the polymer particles and to allow the magnetic material to be encapsulated in the polymer particles.

[0042] The polymer particles into which the magnetic material has been introduced may be shrunk by contacting the polymer particles into which the magnetic material has been introduced with an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol-based solvent. By contacting the polymer particles into which the magnetic material has been introduced with an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol-based solvent, hydrophobic interactions are formed in the polymer constituting the polymer particles, and the polymer particles into which the magnetic material has been introduced can be easily shrunk. For example, the polymer particles into which the magnetic material has been introduced can be contacted with an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol-based solvent by replacing the solvent after the introduction step with an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol-based solvent, recovering the polymer particles into which the magnetic material has been introduced after the introduction step and dispersing them in an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol-based solvent, or the like.

[0043] Specific examples of the aqueous solvent or the mixed solvent of the aqueous solvent and the alcohol-based solvent used in the shrinking step are the same as those of the aqueous solvent or the mixed solvent of the aqueous solvent and the alcohol-based solvent used in the polymer particle dispersion preparation step. The aqueous solvent or the mixed solvent of the aqueous solvent and the alcohol-based solvent used in the shrinking step may be the same as or different from the aqueous solvent or the mixed solvent of the aqueous solvent and the alcohol-based solvent used in the polymer particle dispersion preparation step.

[0044] This production method can produce magnetic polymer particles at room temperature in a short time (eg, 1 hour or less) through the above-mentioned introduction step and contraction step, and therefore has good operability and is easy to scale up.

[0045] [Other steps] The present production method may include other steps in addition to the above-mentioned introducing step and shrinking step, such as a step of removing the solvent by centrifugation, magnetic separation, dialysis, or the like after the introducing step.

[0046] This manufacturing method can use polymer particles with various particle sizes, so that magnetic polymer particles with desired particle sizes can be manufactured according to the purpose.The average particle size of the magnetic polymer particles manufactured by this manufacturing method is preferably 0.1 μm or more and 5.0 μm or less, more preferably 0.1 μm or more and 1.0 μm or less, even more preferably 0.1 μm or more and 0.5 μm or less, and even more preferably 0.1 μm or more and 0.3 μm or less.In this specification, the average particle size of the magnetic polymer particles is the number average particle size.

[0047] 〔summary〕 The method for producing magnetic polymer particles according to aspect 1 of the present invention includes an introduction step of swelling polymer particles and introducing a magnetic material into the swollen polymer particles, and a contraction step of contracting the polymer particles into which the magnetic material has been introduced.

[0048] The method for producing magnetic polymer particles according to aspect 2 of the present invention, in accordance with aspect 1 of the present invention, further includes a magnetic material dispersion preparation step of dispersing the magnetic material in an aprotic solvent to prepare a magnetic material dispersion, and a polymer particle dispersion step of dispersing the polymer particles in a protic solvent to prepare a polymer particle dispersion, and the introduction step may be a step of swelling the polymer particles by contacting the magnetic material dispersion with the polymer particle dispersion, and introducing the magnetic material into the swollen polymer particles.

[0049] A method for producing magnetic polymer particles according to a third aspect of the present invention may be such that, in the second aspect of the present invention, the aprotic solvent is a hydrophobic solvent.

[0050] A fourth aspect of the present invention relates to a method for producing magnetic polymer particles, in the second or third aspect of the present invention, wherein the protic solvent is an aqueous solvent, an alcoholic solvent, or a mixed solvent of an aqueous solvent and an alcoholic solvent.

[0051] In the method for producing magnetic polymer particles according to aspect 5 of the present invention, in any one of aspects 1 to 4 of the present invention, in the shrinking step, the polymer particles into which the magnetic material has been introduced may be contacted with an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol solvent.

[0052] In the method for producing magnetic polymer particles according to a sixth aspect of the present invention, in any one of the second to fifth aspects of the present invention, the protic solvent may contain a surfactant.

[0053] In the method for producing magnetic polymer particles according to a seventh aspect of the present invention, in any one of the first to sixth aspects of the present invention, the magnetic substance may be coated with a long-chain fatty acid.

[0054] In the method for producing magnetic polymer particles according to aspect 8 of the present invention, in any one of aspects 1 to 7 of the present invention, the polymer particles may be polymer particles containing structural units derived from an aromatic vinyl compound.

[0055] In the method for producing magnetic polymer particles according to a ninth aspect of the present invention, in any one of the first to eighth aspects of the present invention, the average particle size of the magnetic polymer particles may be 0.1 μm or more and 5.0 μm or less.

[0056] The following examples are provided to further explain the embodiments of the present invention. Of course, the present invention is not limited to the following examples, and various modifications are possible in detail. Furthermore, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The embodiments obtained by appropriately combining the technical means disclosed herein are also included in the technical scope of the present invention. In addition, all of the documents described in this specification are incorporated by reference. EXAMPLES

[0057] In the examples, % means % by mass unless otherwise specified. The average particle sizes of the polymer particles and the magnetic polymer particles were measured by dynamic light scattering.

[0058] [Example 1] Preparation of magnetic polymer particles (Synthesis of polystyrene particles) Polystyrene particles were synthesized by soap-free polymerization. Soap-free polymerization was carried out by the following procedure. 5.4 mL of styrene and an aqueous solution of K2S2O8 (82.8 mg / 240 mL) were added to a 1 L three-neck flask. Next, N2 replacement was performed while stirring at 200 rpm for 30 minutes. Next, the mixture was heated and stirred at 70°C for 16 hours. The reaction mixture was allowed to cool, and the polystyrene particles were purified by dialysis. The average particle size of the synthesized polystyrene particles was 0.3 μm.

[0059] (Preparation of polymer particle dispersion) In a 1.5 mL Eppendorf tube, 0.9 mL of a 2.5% PF-127 aqueous dispersion of polystyrene particles (polymer particle dispersion) was prepared (8 mg / mL).

[0060] (Preparation of magnetic material dispersion) The magnetic material used was iron oxide nanoparticles (EMG1400, d=10 nm / coating agent: long-chain fatty acid) manufactured by Ferrotec Corp. The magnetic material was dispersed in toluene to prepare a magnetic material dispersion of 4 mg / 100 μL.

[0061] (Swelling of polymer particles and introduction of magnetic material into polymer particles) 100 μL of the magnetic material dispersion was added to the polymer particle dispersion in the Eppendorf tube, and the mixture was stirred at room temperature for 1 hour using a shaker. After stirring, the mixture was centrifuged (5000 g, 15 minutes) and the supernatant was removed.

[0062] (Solvent Replacement) After centrifugation, 1000μL of water was added to the collected polymer particles to disperse the polymer particles in water. Further, centrifugation (5000g, 15 minutes) was performed, and 1000μL of water was added to the collected polymer particles to disperse the polymer particles in water. This operation was repeated twice, and the polymer particles were washed with water to obtain the desired magnetic polymer particles. The average particle size of the magnetic polymer particles was 0.1-0.3μm.

[0063] Example 2 Except for changing the solvent used in preparing the magnetic material dispersion liquid from toluene to chlorobenzene, magnetic polymer particles were prepared in the same manner as in Example 1. The average particle size of the obtained magnetic polymer particles was 0.3 to 2.0 μm.

[0064] Example 3 Except for changing the polystyrene particles synthesized in Example 1 to cyclohexane, magnetic polymer particles were prepared in the same manner as in Example 1. The average particle size of the obtained magnetic polymer particles was 0.3 to 0.5 μm.

[0065] [Evaluation Example 1] Observation of magnetic polymer particles The magnetic polymer particles obtained in Example 1 were observed with an electron probe microanalyzer (EMPA). The results of the observation with EMPA are shown in FIG. 1, and the results of elemental analysis are shown in FIG.

[0066] The upper figure in Fig. 1 is a secondary electron image. The lower figure in Fig. 1 is a backscattered electron image, and the white particles indicate magnetic polymer particles into which a magnetic material has been introduced. As shown in Figs. 1 and 2, it was confirmed that a magnetic material had been introduced into the magnetic polymer particles prepared in Example 1.

[0067] Moreover, the magnetic polymer particles prepared in Examples 2 and 3 were also observed by EMPA, and it was confirmed that a magnetic material was introduced into the prepared magnetic polymer particles. [Industrial Applicability]

[0068] The magnetic polymer particles produced by the method of the present invention can be used in the field of life sciences, such as recovery or detection of DNA or viruses, or in the field of clinical testing using chemiluminescence immunoassays, etc.

Claims

1. an introduction step of swelling the polymer particles and introducing a magnetic material into the swollen polymer particles; A shrinking step of shrinking the polymer particles into which the magnetic material has been introduced. A method for producing magnetic polymer particles.

2. a magnetic material dispersion preparation step of dispersing the magnetic material in an aprotic solvent to prepare a magnetic material dispersion; The method further includes a polymer particle dispersion step of dispersing the polymer particles in a protic solvent to prepare a polymer particle dispersion, The method for producing magnetic polymer particles described in claim 1, wherein the introduction step is a step of swelling the polymer particles by contacting the magnetic material dispersion liquid with the polymer particle dispersion liquid, and introducing the magnetic material into the swollen polymer particles.

3. The method for producing magnetic polymer particles according to claim 2 , wherein the aprotic solvent is a hydrophobic solvent.

4. The method for producing magnetic polymer particles according to claim 2 , wherein the protic solvent is an aqueous solvent, an alcoholic solvent, or a mixed solvent of an aqueous solvent and an alcoholic solvent.

5. The method for producing magnetic polymer particles according to claim 1 or 2, wherein in the shrinking step, the polymer particles having the magnetic material introduced therein are contacted with an aqueous solvent or a mixed solvent of an aqueous solvent and an alcohol solvent.

6. The method of claim 2 , wherein the protic solvent comprises a surfactant.

7. The method for producing magnetic polymer particles according to claim 1 or 2, wherein the magnetic material is a magnetic material coated with a long-chain fatty acid.

8. The method for producing magnetic polymer particles according to claim 1 or 2, wherein the polymer particles are polymer particles containing structural units derived from an aromatic vinyl compound.

9. The method for producing magnetic polymer particles according to claim 1 or 2, wherein the average particle size of the magnetic polymer particles is 0.1 μm or more and 5.0 μm or less.

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