JP4614064B2 - Method for producing magnetic particles and biochemical carrier - Google Patents

Description

  The present invention relates to a method for producing magnetic particles that are extremely excellent in reproducibility of particle diameter and magnetic separation property, particularly as a biochemical carrier. The magnetic particles can be used in various fields such as paints, paper, electronic materials, electrophotography, cosmetics, pharmaceuticals, agricultural chemicals, foods, and catalysts, as well as biochemical carriers.

  Magnetic particles containing magnetic fine particles in the inside of the particles are particularly desired as biochemical carriers, which are excellent in reproducibility of particle size and magnetic separation property in terms of performance such as improvement in separation and purification accuracy.

  An object of this invention is to provide the manufacturing method of the magnetic particle which was extremely excellent in the reproducibility of a particle diameter and magnetic separation property.

  Another object of the present invention is to provide a biochemical carrier with extremely excellent reproducibility of particle size and magnetic separation.

  The inventor of the present application uses mother particles whose surfaces are treated with an antistatic agent, and adsorbs magnetic fine particles on the surface of the population to form a coating layer, and a polymer layer is formed on the coating layer by polymerization. It has been found that magnetic particles with extremely excellent reproducibility of the particle diameter and magnetic stability can be obtained by forming.

Therefore, the manufacturing method of the magnetic particles of the present invention is:
Forming a coating layer by adsorbing magnetic fine particles on the surface of mother particles treated with an antistatic agent;
Forming a polymer layer by polymerization on the coating layer;
including.

  Here, in the step of forming the coating layer, the magnetic fine particles can be physically adsorbed on the base particles.

  Here, the surface of the magnetic fine particles may be hydrophobic.

  Here, the antistatic agent may be a cationic antistatic agent.

  The biochemical carrier of the present invention is obtained by the above-described method for producing magnetic particles of the present invention.

  According to the present invention, a step of forming a coating layer by adsorbing magnetic fine particles on the surface of the base particles treated with an antistatic agent, and a step of forming a polymer layer on the coating layer by polymerization. By including, magnetic particles with extremely excellent reproducibility of the particle diameter and magnetic separation can be obtained. This magnetic particle is useful, for example, as a biochemical carrier.

1. Magnetic Particle and Method for Producing the Same The magnetic particle production method of the present invention comprises a step of forming a coating layer by adsorbing magnetic fine particles on the surface of a mother particle treated with an antistatic agent, and a polymerization process on the coating layer. Forming a polymer layer.

  Here, the magnetic fine particles can be physically adsorbed on the surface of the base particles by, for example, high-speed stirring. Hereafter, each material used for manufacture of the magnetic particle of this invention is demonstrated in detail.

1.1 Mother Particle The mother particle used in the present invention is basically a non-magnetic substance, and both an organic substance and an inorganic substance can be used, but an organic substance is preferable. As a typical example of the organic substance, for example, a polymer can be mentioned. As such a polymer, a vinyl polymer is particularly preferable, and as a vinyl monomer used for the production thereof, aromatic vinyl monomers such as styrene, α-methylstyrene, halogenated styrene, divinylbenzene, vinyl acetate, propion are used. Vinyl esters such as vinyl acid, unsaturated nitriles such as acrylonitrile, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol diacrylate Ethylenically unsaturated carboxylic acid alkyls such as ethylene glycol dimethacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, etc. It can be exemplified esters and the like. This vinyl polymer may be a homopolymer or a copolymer composed of two or more monomers selected from the vinyl monomers. In addition, the vinyl monomers and conjugated diolefins such as butadiene and isoprene, acrylic acid, methacrylic acid, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, A copolymer with a copolymerizable monomer such as 2-hydroxyethyl methacrylate, diallyl phthalate, allyl acrylate, allyl methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, or the like can also be used.

  The average particle size of the mother particles used in the present invention is preferably 0.1 to 10 μm, more preferably 0.2 to 5 μm, and most preferably 0.3 to 2 μm. If the average particle size of the base particles is less than 0.1 μm, for example, the collision energy due to high-speed stirring of the particles may be insufficient, and it may be difficult to adsorb magnetic fine particles, and the reproducibility of magnetic separation may be inferior. is there. On the other hand, when the average particle diameter of the mother particles exceeds 10 μm, the biochemical carrier may have a small surface area as a reaction field.

  The polymer particles as the mother particles having an average particle diameter in the above-described range can be obtained, for example, by suspension polymerization of the above-mentioned vinyl monomer or pulverization of a polymer bulk. Examples of a method for producing mother particles having a uniform particle size include swelling polymerization described in JP-B-57-24369, polymerization described in Journal of Polymer Science, Polymer Letter Edition (J. Polym. Sci., Polymer Letter Ed.). It can be easily produced by the method, JP-A Nos. 61-215602, 61-215603, and 61-215604.

  As the mother particles of the present invention, in addition to the above polymer particles, particulate pharmaceuticals, agricultural chemicals, foods, fragrances, dyes, pigments, metals and the like can also be used. Further, after absorbing or adsorbing a liquid substance or solid substance fine powder on the porous particles, the porous particles can be used as mother particles. By using such mother particles, magnetic particles containing the liquid substance or solid substance inside can be obtained. The absorption or adsorption of the substance means absorption, adsorption or adhesion on the particle surface and inside the pores, and this absorption and adsorption can be carried out by a conventionally known method such as impregnation. .

1.2 Antistatic Agent The surface of the mother particles used for the production of the magnetic particles of the present invention is treated with an antistatic agent. Examples of the antistatic agent used in the present invention include poly (oxyethylene) alkylamine, poly (oxyethylene) alkylamide, poly (oxyethylene) alkyl ether, poly (oxyethylene) alkylphenyl ether, glycerin fatty acid ester, Nonionic antistatic agents such as sorbitan fatty acid esters; anionic antistatic agents such as alkyl sulfonates, alkyl benzene sulfonates, alkyl sulfates, polyoxyethylene polycyclic phenyl ether sulfates, alkyl phosphates, polyisoprene sulfonic acids; alkyl pyridinium chlorides, Cationic antistatic agent such as alkylamine acetate, alkylammonium chloride, polymer having amino group; alkylbetaine, alkylimid Gelsolin and amphoteric antistatic agents such as alkyl alanine and the like. Among these, particularly preferred are anionic antistatic agents such as alkylbenzene sulfonate and polyoxyethylene polycyclic phenyl ether sulfate; and cationic antistatic agents such as alkylpyridinium chloride and alkylammonium chloride, most preferably Polyoxyethylene polycyclic phenyl ether sulfate (trade name, for example, Newcol 707SF (manufactured by Nippon Emulsifier), Eleminol BS20 (manufactured by Sanyo Kasei)), alkylammonium chloride (trade name, for example, Cotamine 24P (manufactured by Kao) Arcade 16-25 (made by Lion Akzo).

  The amount of the antistatic agent is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 5 parts by weight, and most preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the solid content of the mother particles to be treated. When the amount is less than 0.001 part, the effect of improving the reproducibility of the particle size and magnetic separation property may not be obtained. When the amount exceeds 10 parts by weight, foaming and polymerization stability are inferior in the subsequent step of forming a polymer layer by polymerization. There is.

  As a treatment method using an antistatic agent, (1) a method of adding at the time of polymerization of mother particles, (2) a method of adding an aqueous solution of the antistatic agent to purified or unpurified mother particles and drying, (3) A method in which an aqueous solution of the antistatic agent is added to purified or unpurified mother particles and then centrifuged, and the supernatant is discarded and dried. (4) Dry blending of the antistatic agent powder to the dried mother particle powder is performed. The method etc. are mentioned. When an anionic antistatic agent is used, the preferred method is the method (1), and when a cationic antistatic agent is used, the preferred methods are the methods (2) and (3).

1.3 Magnetic Fine Particles As the magnetic fine particles used for the production of the magnetic particles of the present invention, those having a hydrophobic surface can be used. For example, as the magnetic fine particles, those whose surfaces have been subjected to a hydrophobic treatment can be used from the viewpoint of the affinity and compatibility between the mother particles and the monomer monomer used in the subsequent step. Thus, the surface of the magnetic fine particles can be made hydrophobic by subjecting the surface of the magnetic fine particles to a hydrophobic treatment.

  The method of hydrophobizing the surface of the magnetic fine particles is not particularly limited. For example, a compound having a magnetic fine particle, a portion having extremely high affinity, and a hydrophobic portion in the molecule is brought into contact with the magnetic fine particle to be bonded. A method can be mentioned. Examples of such compounds include silane compounds represented by silane coupling agents and surfactants represented by long-chain fatty acid soaps. Hydrophobization with silane compounds is excellent in chemical resistance, especially alkali resistance, and peeling of the magnetic material due to dropping of the hydrophobized layer during use, problems of deterioration of magnetic performance, or detached magnetic material and surface activity It is possible to effectively prevent the occurrence of a problem that contaminants enter the system due to the floating agent.

  Further, in the present invention, it can be said that the magnetic fine particles whose surface is hydrophobized are sufficiently hydrophobized, for example, when they can be well dispersed in toluene.

  Examples of silane compounds represented by silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltris (β-methoxyethoxy) silane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and γ-glycid. Oxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, dodecyltrimethoxysilane, Hexyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, dodecyltrichlorosilane, hexyltrichlorosilane, methyltrichlorosilane, phenyltrichlorosilane, etc. The

  As a method for bonding these silane compounds to magnetic fine particles, for example, magnetic fine particles and a silane compound are mixed in an inorganic medium such as water or an organic medium such as alcohol, ether, ketone, ester, and stirred. After heating, the magnetic fine particles are separated by decantation or the like and the inorganic medium or the organic medium is removed by drying under reduced pressure. Alternatively, the magnetic fine particles and the silane compound may be directly mixed and heated to bond them together. In these means, the heating temperature is usually 30 to 100 ° C., and the heating temperature is about 0.5 to 2 hours. The amount of the silane compound used is appropriately determined depending on the surface area of the magnetic fine particles, but is usually 1 to 50 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the magnetic fine particles.

  As surfactants represented by long-chain fatty acid soaps, stearic acid (salt), oleic acid (salt), linoleic acid (salt), linolenic acid (salt), ricinoleic acid (salt), erucic acid (salt), In addition to palmitic acid (salt) and myristic acid (salt), water repellents such as pyridium salt type water repellents and methylolamide type water repellents can be exemplified.

  As a method of binding to the magnetic fine particles with these surfactants, for example, the magnetic fine particles and the surfactant are mixed in an organic solvent such as alcohol, ether, ketone, ester, alkane, and heated with stirring. After that, a means for removing the organic medium by drying under reduced pressure after the magnetic fine particles are molecularized by decantation or the like can be mentioned. In these means, the heating temperature is usually 30 to 100 ° C., and the heating temperature is about 0.5 to 2 hours. The amount of the surfactant used is appropriately determined according to the surface area of the magnetic fine particles, but is usually 1 to 50 parts by weight, preferably 2 to 30 parts by weight with respect to 100 parts by weight of the magnetic fine particles.

  In the present invention, the ratio of the mother particles to the magnetic fine particles (mother particles: magnetic fine particles) is preferably 75:25 to 20:80 by weight. When the amount of magnetic fine particles is less than this range, the composite effect is reduced. When the amount of magnetic fine particles is larger than this range, the amount of the mother particles becomes excessive, and the number of magnetic fine particles that are not combined increases.

1.4 Coating Layer In the method for producing magnetic particles of the present invention, a coating layer is formed by adsorbing magnetic fine particles on the surface of the mother particle. Here, the magnetic fine particles can be physically adsorbed on the surface of the mother particles. More specifically, it is preferable to form the coating layer by physically adsorbing the magnetic fine particles on the surface of the base particle by high-speed stirring.

  In the present invention, “physical adsorption” refers to an adsorption method and a bonding method that do not involve a chemical reaction. In principle, hydrophobic / hydrophobic adsorption, melt bonding or adsorption, fusion bonding or adsorption, hydrogen bonding , Van der Waals combination and so on. Examples of using hydrophobic / hydrophobic adsorption include dry blending the surface of the base particle and the surface of the magnetic fine particles, or a well-dispersed solvent such as toluene, without affecting both the base particles and the magnetic fine particles. An example is a method in which the solvent is volatilized under mixing conditions after sufficiently dispersing in hexane. It is also possible to make a composite using fusion bonding or adsorption, fusion bonding or adsorption by selecting a material or solvent that slightly dissolves the surface of the mother particle and the surface of the magnetic fine particles and / or selecting the temperature conditions during mixing. is there.

  Examples of a method of forming a coating layer by physically adsorbing magnetic fine particles on the surface of the mother particle by high-speed stirring include a method of realizing a composite by applying a physically strong force from the outside. For example, a mortar, an automatic mortar, a ball mill, a blade pressurizing powder compression method, a mechanochemical effect such as a mechanofusion method, or a jet mill or a hybridizer using a high-speed airflow impact method. It is desirable that the physical adsorption force is strong in order to efficiently and firmly perform the composite. The method includes stirring in a vessel with a stirring blade preferably at a peripheral speed of the stirring blade of 40 to 150 m / sec. If the peripheral speed of the stirring blade is lower than 40 m / sec, sufficient energy for forming the coating layer may not be obtained. In addition, although there is no restriction | limiting in particular about the upper limit of the circumferential speed of a stirring blade, It determines automatically from points, such as an apparatus to be used and energy efficiency. In addition, when using the impact method in a high-speed air current, it is preferable to dry-blend the mother particles and the magnetic fine particles in advance with a Henschel mixer or the like.

  Further, if necessary, a nonmagnetic substance other than the magnetic fine particles may be added as a substance for forming the coating layer of the mother particles at the time of compounding. There are no particular restrictions on the type of such a non-magnetic substance, and it can be appropriately selected from an organic substance or an inorganic substance depending on the purpose of compositing the mother particles.

  For example, when imparting conductivity to the mother particles, non-magnetic substances include carbon black, various metal powders such as copper and aluminum, inorganic materials such as copper iodide and ruthenium oxide, and conductive materials such as polyacetylene, polypyrrole, and polythienylene. Can be used.

  On the other hand, when the mother particles are conductive and it is desired to increase the electrical resistance by surface modification to impart chargeability, a polymer, preferably a thermoplastic polymer, is preferably used as the nonmagnetic substance. The thermoplastic polymer can be appropriately selected from the vinyl polymers according to the purpose. The thermoplastic polymer particles preferably have a particle size of 1 to 60% of the particle size of the mother particles, a weight average molecular weight of 10,000 to 1,000,000, and an acrylic material. As the nonmagnetic substance particles used in the present invention (hereinafter referred to as “nonmagnetic fine particles”), it is preferable to use particles having a uniform particle diameter as in the case of the mother particles.

  The nonmagnetic substance (nonmagnetic fine particles) for forming the coating layer is not limited to a single species, and two or more species can be used in combination. In particular, when using non-magnetic fine particles that are difficult to melt, such as inorganic substances, it is preferable to mix these inorganic substance particles and thermoplastic polymer particles for better formation of the coating layer. Also, mixed particles of two or more kinds of synthetic polymers can be used. In this case also, at least one of them is preferably a thermoplastic polymer particle. The amount of these nonmagnetic fine particles added is desirably 100 parts by weight or less with respect to 100 parts by weight of the base particles.

  Further, when coloring the particles, the following pigments can be used as the non-magnetic fine particles.

Black pigment Carbon black, acetylene black, lamp black, aniline black, magnetite Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel swallow, naphthol yellow S, Hanser yellow G , Hanser Yellow 10G, Benzine Yellow G, Benzine Yellow Yellow GR, Quinoline Yellow Lake, Permanentero Yellow NCG, Tartra Gin Brown Color Red Pigment Yellow Lead, Molybdenum Orange, Permanent Range GTR, Pyrazolone Orange, Vulcan Orange, Indanthren Brilliant Orange RK , Benzidine Orange G, Indanthren Brilliant Orange GK
Red Pigment Bengala, Cadmium Red, Red Plum, Mercury Cadmium, Permanent Red 4R, Risor Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine JB
Purple Pigment Manganese Purple, Fast Violet B, Methyl Violet Lake Blue Pigment Bitumen, Cobalt Blue, Alkaline Blue Lake, Metal Phthalocyanine Blue, Phthalocyanine Blue Partial Chlorides, Fast Sky Blue, Indanthrene Blue BC
Green pigment Chrome green, chromium oxide, pigment green B, malachite green lake, final yellow green White pigment Zinc white, titanium oxide, antimony white, zinc sulfide Body pigment Barite powder, barium carbonate, clay, silica, white carbon, talc, alumina For the purpose of controlling the chargeability of the white mother particles, various dyes such as nigrosine, methylene blue, rose bengal, quinoline yellow, and ultra blue can be used as the nonmagnetic fine particles.

  Depending on the purpose, various functional materials such as a fluorescent substance, hydroxyapatite, and zirconia can also be used as non-magnetic fine particles for forming the coating layer. The nonmagnetic fine particles for forming the coating layer are not limited to single species, and can be used in combination of two or more. In particular, when using non-magnetic fine particles that are difficult to melt, such as inorganic substances, it is preferable to mix these inorganic substance particles and thermoplastic polymer particles for better formation of the coating layer. Also, mixed particles of two or more kinds of synthetic polymers can be used. In this case also, at least one of them is preferably a thermoplastic polymer particle. The amount of these nonmagnetic fine particles added is desirably 100 parts by weight or less with respect to 100 parts by weight of the base particles.

  In addition, the magnetic particles including the coating layer having a multilayer structure composed of a plurality of coating layers can be produced by performing a plurality of composites using the same type or different types of magnetic fine particles and / or non-magnetic fine particles. . For example, after forming a first coating layer using mother particles and magnetic fine particles, polymer particles are further added and physically adsorbed on the first coating layer to form a second coating layer. And a several coating layer can be formed by repeating this as needed. As described above, polymer particles, preferably thermoplastic polymer particles, are preferably used as components of the non-magnetic fine particles used when forming the coating layer having a multilayer structure. The thermoplastic polymer particles can be appropriately selected from the vinyl polymers according to the purpose. The thermoplastic polymer particles preferably have a particle size of 1 to 60% of the particle size of the mother particles, a weight average molecular weight of 10,000 to 1,000,000, and an acrylic material. The addition amount of these polymer components is preferably 100 parts by weight or less with respect to 100 parts by weight of the base particles. In this case, if the type of the polymer that is non-magnetic fine particles is changed to the mother particles, it becomes easy to adhere by frictional charging and the formation of the coating layer becomes easier.

1.5 Polymer Layer In the method for producing magnetic particles of the present invention, a polymer layer is further formed on the coating layer. This polymer layer (hereinafter also referred to as “coating polymer layer”) is formed for coating.

  In the presence of particles having a coating layer formed on the surface of the mother particles (hereinafter referred to as “magnetic material-coated particles”), the polymer layer is composed of a copolymerizable monomer as a main material and a polymerization initiator as a sub-material, An emulsifier, a dispersant, a surfactant, an electrolyte, a cross-linking agent, a molecular weight regulator and the like are added as necessary, and polymerization can be performed in a liquid. By forming the coating polymer layer by polymerization in this way, a surface useful as a biochemical carrier can be provided, for example, a desired functional group can be introduced on the surface of the polymer layer. Further, when a cationic antistatic agent is used as the antistatic agent, it also has an effect of preventing this from bleeding out to the outermost surface of the particle and adversely affecting the biochemical reaction.

  As a component of the polymer layer, a vinyl polymer is particularly preferable, and vinyl monomers used for the production thereof are aromatic vinyl monomers such as styrene, α-methylstyrene, halogenated styrene, divinylbenzene, vinyl acetate, Vinyl esters such as vinyl propionate, unsaturated nitriles such as acrylonitrile, methyl acrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol di Ethylenically unsaturated carboxylic acid alkyls such as acrylate, ethylene glycol dimethacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, etc. It can be exemplified esters and the like. This vinyl polymer may be a homopolymer or a copolymer composed of two or more monomers selected from the vinyl monomers.

  In addition, the vinyl monomers and conjugated diolefins such as butadiene and isoprene, acrylic acid, methacrylic acid, acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, N-methylol acrylamide, N-methylol methacrylamide, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, diallyl phthalate, allyl acrylate, allyl methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, styrenesulfonic acid and its sodium salt, 2-acrylamido-2-methylpropanesulfonic acid and its sodium salt, Copolymers with copolymerizable monomers such as isoprene sulfonic acid and its sodium salt should also be used. Can.

  As the polymerization initiator, an oil-soluble initiator and a water-soluble initiator can be used.

  Examples of oil-soluble polymerization initiators include benzoyl peroxide, lauroyl peroxide, tertiary butyl peroxy 2-ethylhexanate, 3,5,5-trimethylhexanoyl peroxide, azobisisobutyronitrile and other peroxide compounds and azo compounds. Can be mentioned.

  Water-soluble initiators include potassium persulfate, ammonium persulfate, persulfates such as sodium persulfate, hydrogen peroxide, 2-2 azobis (2-aminopropane) mineral acid salt, azobiscyanovaleric acid and its alkali metal salts, and Examples thereof include ammonium salts, and redox initiators in which persulfate, hydrogen peroxide salt and sodium bisulfite, sodium thiosulfate, ferrous chloride, etc. are combined. Among them, persulfate is preferably used. . The ratio of these polymerization initiators to the whole monomer is preferably in the range of 0.01 to 8% by weight.

  From the viewpoint of solubility in water, oil-soluble polymerization initiators are preferred. When a water-soluble polymerization initiator is used, there is a tendency that not only polymerization on the surface of the magnetic material-coated particles but a large amount of new particles in which only a hydrophobic polymerization monomer not containing the magnetic material-coated particles is polymerized.

  As the emulsifier, a commonly used anionic surfactant or nonionic surfactant can be used alone or in combination. For example, reactive anionic surfactants include alkali metal salts of higher alcohol sulfates, alkali metal salts of alkylbenzene sulfonic acids, alkali metal salts of succinic acid dialkyl ester sulfonic acids, alkali metal salts of alkyl diphenyl ether disulfonic acids, In addition to anionic surfactants such as sulfuric acid ester salt of oxyethylene alkyl (or alkylphenyl) ether, phosphoric acid ester salt of polyoxyethylene alkyl (or alkylphenyl) ether, formalin condensate of sodium naphthalene sulfonate, etc. S-180A (manufactured by Kao Corporation), Eleminol JS-2 (manufactured by Sanyo Chemical Co., Ltd.), Aqualon HS-10, KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SE-10N, SR-10 (Asahi Denka) Co., Ltd.), and the like.

  Examples of the nonionic surfactant include polyoxyethylene alkyl ether and polyoxyethylene alkyl phenyl ether, as well as Aqualon RS-20 (Daiichi Kogyo Seiyaku Co., Ltd.), Adekari Soap NE-20, A reactive nonionic surfactant such as RN-20 (Asahi Denka Kogyo Co., Ltd.) can be used.

  The method for adding the monomer to the polymerization system in the formation of the coating polymer layer is not particularly limited, and may be any of a batch method, a division method, or a continuous addition method. The polymerization temperature varies depending on the polymerization initiator, but is usually 10 to 90 ° C, preferably 30 to 85 ° C, and the time required for the polymerization is usually about 1 to 30 hours.

1.6 Applications The main use of the magnetic particles of the present invention is biochemical carriers. In the use as a biochemical carrier, it is not desirable to elute impurities from particles, or magnetic particles themselves or impurities from magnetic particles, but the magnetic material obtained by the preferred production method of the present invention described above. Since the particles do not have such inconvenience, they are particularly suitable for carrier particles for diagnostic agents. In the use of such diagnostic agent carrier particles, the surface characteristics of the coating polymer layer can be selected according to the purpose.

  The magnetic particles of the present invention are not limited to the above-mentioned applications, and can be used in various fields such as paints, paper, electronic materials, electrophotography, cosmetics, pharmaceuticals, agricultural chemicals, foods, and catalysts.

2. Examples Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In addition, the particle diameter and magnetic separation property of the particles obtained in Examples and Comparative Examples were measured by the following methods.

2.1 Measuring method 2.1.1. Measurement of Particle Size Using a transmission electron microscope (100SX manufactured by JEOL Ltd.), 300 particles were photographed, the particle size was measured with a ruler, and the average was obtained to obtain the average particle size.

2.1.2 Evaluation of magnetic separation property A test solution containing 0.01% by weight of the obtained magnetic particles in water as a dispersion medium was prepared. Disperse this test solution well, put it in a square optical cell with an optical path length of 1 cm, set it in a spectrophotometer (V-550, manufactured by JASCO Corporation), and place a magnet with a surface magnetic density of 2900 gauss beside this cell holder. The time until the absorbance at 550 nm was attenuated to 1/10 of the initial time was measured, and this time was used as an index for evaluating magnetic separation.

2.2 Example 1
With reference to the polymerization method described in JP-A-07-238105, a styrene / divinylbenzene = 80/20 copolymer (average particle size 1.5 μm) was polymerized and washed three times by centrifugation. To 100 g of this water-containing slurry (in terms of solid content), 100 g (as an aqueous solution) of a 1% aqueous solution of the cationic antistatic agent “Cotamine 24P” (manufactured by Kao, lauryltrimethylammonium chloride) is added, and ultrasonically dispersed, and then centrifuged. The supernatant was separated and discarded, and the lower layer slurry was dried with a dryer at 60 ° C. for 24 hours to obtain powder of mother particles treated with an antistatic agent.

  After adding acetone to oily magnetic fluid “EXP series” (manufactured by Ferrotec Co., Ltd.) to precipitate and precipitate particles, the particles are dried to obtain ferrite-based magnetic fine particles having a hydrophobized surface ( Average particle diameter: 0.02 μm) was obtained. The magnetic fine particles have a surface that has been hydrophobized with a silane coupling agent and a surfactant. Next, the obtained magnetic fine particles were added to toluene / water (weight ratio 1: 1), and after sufficiently stirring, the magnetic fine particles were dispersed only in toluene, and the surface was hydrophobized. It has been confirmed.

15 g of the mother particle powder treated with the antistatic agent and 15 g of the hydrophobized magnetic fine particles are mixed well with a mixer, and this mixture is mixed with a hybridization system NHS-O type (Nara Machinery Co., Ltd.). )) For 5 minutes at a peripheral speed of 100 m / sec (16200 rpm) of the blade (stirring blade). Next, an aqueous solution containing 30 g of the obtained magnetic material-coated particles, 0.5% of a nonionic emulsifier “Emulgen 150” (manufactured by Kao) and 0.5% of an anionic emulsifier “Emar 0” (manufactured by Kao) as a dispersant. 750 g was put into a 1 L separable flask and sufficiently dispersed. In a separate container, 150 g of an aqueous solution containing 0.5% of a nonionic emulsifier “Emulgen 150” (manufactured by Kao) and 0.5% of an anionic emulsifier “Emar 0” (manufactured by Kao) is placed, and 15 g of cyclohexyl methacrylate as a monomer, A monomer emulsion was prepared by adding and mixing 4 g of methacrylic acid and 0.5 g of tertiary butyl peroxy 2-ethylhexanate (manufactured by NOF Corporation; Perbutyl O) as a polymerization initiator. The temperature of the separable flask was raised to 60 ° C. while purging with N ₂ gas under stirring at 200 rpm with a stirring blade at 200 rpm, and then the monomer emulsion was continuously added to the separable flask over 2 hours. After completion of the continuous addition, stirring was continued at 80 ° C. for 2 hours to complete the reaction. The obtained aqueous dispersion of magnetic particles was subjected to magnetic purification and gravity sedimentation purification. According to the above production method, magnetic particles were independently produced 10 times (Experiment Nos. 1 to 10). Table 1 shows the measurement results of the particle size and magnetic separation property of the particles of each experiment number produced in this example.

2.3 Comparative Example 1
Instead of adding 100 g (as an aqueous solution) of a 1% aqueous solution of lauryltrimethylammonium chloride (“Cootamine 24P” manufactured by Kao Corporation), the production of magnetic particles was independently carried out in the same manner as in Example 1 except that 100 g of water was added. The test was performed 10 times (experiment numbers 1 to 10). Table 1 shows the measurement results of the particle diameter and magnetic separability of the particles of each experiment number produced in this comparative example.

  It was confirmed that the magnetic particles of Example 1 are excellent in reproducibility of the particle diameter and magnetic separation property. In contrast, the particles of Comparative Example 1 were inferior to the magnetic particles of Example 1 in both the particle diameter and the reproducibility of the magnetic separation property. From the above results, the magnetic particles of Example 1 were compared with the particles of Comparative Example 1 in which the surface of the mother particles was not treated with the antistatic agent by using the mother particles whose surface was treated with the antistatic agent. Thus, it was confirmed that the reproducibility of the particle size and magnetic separation was extremely excellent.

Claims (5)

Forming a coating layer by adsorbing magnetic fine particles on the surface of mother particles treated with an antistatic agent;
Forming a polymer layer by polymerization on the coating layer;
A method for producing magnetic particles, comprising: In claim 1,
The method for producing magnetic particles, wherein in the step of forming the coating layer, the magnetic fine particles are physically adsorbed on the base particles. In claim 1 or 2,
The method for producing magnetic particles, wherein the surface of the magnetic fine particles is hydrophobic. In any of claims 1 to 3,
A method for producing magnetic particles, wherein the antistatic agent is a cationic antistatic agent.   A biochemical carrier comprising magnetic particles obtained by the production method according to claim 1.