JP5195590B2 - Magnetic composite particles, magnetic carrier, and developer - Google Patents

Description

  The present invention relates to a magnetic composite particle, a magnetic carrier, and a developer. More specifically, the present invention relates to a magnetic composite particle that can develop a high-quality image with low environmental load and high durability, a magnetic carrier for electrophotographic development, and a developer.

  Electrophotography is a system that forms a latent image using solid photoconductivity, electrostatically attaches toner, which is colored particles, to the latent image, develops it, and transfers / fixes it to paper or the like It is widely used for copying machines and printers, and recently for printing machines.

  In this development, when the toner does not have magnetism, carrier particles called a magnetic carrier are used. This magnetic carrier imparts an appropriate amount of positive or negative electricity to the toner by frictional charging, and uses a magnetic force to develop a developing area near the surface of the photoreceptor where a latent image is formed via a developing sleeve containing a magnet. It plays the role of transporting toner. (The developer is a mixture of this magnetic carrier and toner that can be developed immediately.) In recent years, colorization has progressed in electrophotography, and the color toner has no magnetism. It has increased dramatically. At the same time, high image quality and high speed have been demanded, and accordingly, further functionalization of magnetic carriers has been demanded.

  Conventionally, as a magnetic carrier, an iron powder carrier, a ferrite carrier, a binder type carrier, or the like has been developed and put to practical use.

The iron powder carrier is a magnetic carrier prepared by pulverizing iron powder, and is often in the form of flakes, sponges, and irregular shapes. Since it is an iron powder, the true specific gravity is as large as 7 to 8 and the bulk density is as large as ³ to 4 g / cm ^{3. In} order to stir in the developing machine, a large driving force is required and the mechanical wear is large. For this reason, the toner tends to be spent and the charge amount of the carrier itself is easily deteriorated, and the function of the carrier is easily deteriorated in a short period of time. There is also concern about damage to the photoreceptor.

The ferrite carrier is a magnetic carrier prepared by pulverizing ferrite having a specific gravity smaller than that of the iron powder, and is more spherical than the iron powder carrier. Since it is a ferrite, the true specific gravity is 4.5 to 5.5, and the bulk density is 2 to ³ g / cm ³ , which is lighter than the iron powder carrier. Therefore, the durability is improved as compared with the iron powder carrier, and the photoreceptor is less damaged. However, metals such as copper-zinc, manganese-magnesium-strontium, and lithium-magnesium-calcium that are not safe for the environment and the human body are used. In addition, since it is prepared by pulverization, it is difficult to finely adjust the shape, it is difficult to reduce the particle size, and it is not very suitable for future high image quality.

The binder type carrier is a magnetic carrier prepared by molding magnetic fine particles with a binder such as a resin, and since the bulk density is as small as about 2.5 g / cm ³ , it shows good durability and damages the photoreceptor. There are few. Further, as a classification among them, there are binder-type carriers prepared by pulverization and granulation. Crushing is difficult to fine-tune the shape, making it difficult to reduce the particle size, and is not very suitable for future high image quality. Since granulation is easy to adjust the particle shape freely, such as spherical or rice grain, it is easy to control fluidity and contact with toner. Furthermore, the particle size distribution is narrow and it is easy to reduce the particle size. Therefore, improvement in durability and high image quality can be realized. From these aspects, it is considered that binder type carriers by granulation will be widely used in the future.

  By the way, as binder resins used for binder-type carriers, thermoplastic resins such as vinyl and polyester, and thermosetting resins such as phenol, melamine, and epoxy are used. Resin derived from underground resources such as coal is used, and the environmental load due to the use of these is not considered.

  In recent years, environmental problems such as depletion of underground resources and global warming have surfaced worldwide. Therefore, for the mid- to long-term prosperity of mankind, it is necessary to suppress the generation of carbon dioxide, which causes global warming, without using underground resources as much as possible. Therefore, there are high expectations for products that use bio-based polymers that can be recycled from plants and the like and that generate less carbon dioxide. In the carrier market, it is used about 9,700 tons (2007 Japanese manufacturer results: according to Data Supply Survey), and it is thought that the market will continue to expand with the future colorization. If some of the resinous components of several thousand tons can be changed to bio-based polymers, it is considered effective in reducing environmental impacts such as securing underground resources and preventing global warming.

  Bio-based polymers are also known to be safe and safe for the human body. Therefore, it is desirable to use a bio-based polymer from the viewpoint of improving safety.

  Some bio-based polymers are biodegradable. (Of course, there are bio-based polymers that do not have biodegradability.) This biodegradability causes deterioration of durability and strength, and is not welcomed in this application. However, there are known techniques (patent documents 1 and 2) using a bio-based polymer that is characterized by this biodegradability and partially biodegradable.

JP-A-7-98520 JP 7-295300 A

  Patent Document 1 describes a magnetic carrier containing a biodegradable substance in a binder resin of a binder type carrier. Strictly speaking, biodegradable substances include those that are bio-based polymers and those that are not bio-based polymers, and the polyphosphazenes and polycyanoacrylates described are not bio-based polymers. Some bio-based polymers may or may not biodegrade. Trimethylene polyterephthalate and poly-α-methylene-γ-butyrolactone are bio-based polymers but are not biodegradable. . That is, the biodegradable substance and the bio-based polymer are completely different in concept. Further, 80% of the binder resin described in this document is a non-biodegradable resin derived from underground resources such as styrene-n-butyl methacrylate copolymer, and is not environmentally friendly. Furthermore, since the glass transition point of the binder resin was as low as 0 ° C. and was already soft at room temperature, it was inferior in durability. Moreover, since what is described in this document is prepared by a kneading and pulverizing method, it is difficult to control the particle shape, and it is difficult to reduce the particle size, which is not suitable for high image quality.

  Patent Document 2 describes a magnetic carrier containing a biodegradable resin in a binder resin binder resin. As described above, the biodegradable resin and the bio-based polymer are completely different from each other in concept. Furthermore, 3-hydroxybutyrate-3-hydroxyvalerate copolymer (glass transition point-1 ° C.), starch and modified polyvinyl alcohol alloy (glass transition point 20 ° C.), polybutylene succinate (glass transition point) −40 ° C.), polycaprolactone (glass transition point−60 ° C.) and glass transition point are low, and it is already soft at room temperature and inferior in fluidity and durability. Further, as described above, since it is prepared by a kneading and pulverizing method, it is difficult to control the particle shape, and it is difficult to reduce the particle size, which is not suitable for high image quality.

  The present invention is effective for reducing environmental loads such as securing underground resources and preventing global warming, is safe for the human body, has high durability, and is capable of developing high-quality images. It is an object of the present invention to provide a magnetic carrier and developer for use.

  The technical problem can be achieved by the present invention as follows.

  That is, the present invention is a magnetic composite particle comprising at least a magnetic fine particle and a bio-based polymer, wherein the magnetic composite particle has an average particle size of 10 to 100 μm, and the content of the magnetic fine particle in the magnetic composite particle is It is a magnetic composite particle characterized by being 50 to 99% by weight (Invention 1).

  The present invention also provides the magnetic composite particle according to the present invention 1 (invention 2), wherein the glass transition point of the biobase polymer is 35 ° C. or higher.

  The present invention also provides a polymer in which the bio-based polymer is selected from polylactic acid, polyglycolic acid, trimethylene polyterephthalate, ethyl cellulose, poly-α-methylene-γ-butyrolactone, or a copolymer containing monomer units of these polymers. The magnetic composite particle according to the first or second aspect of the invention (Invention 3), which is a polymer or a polymer mixture containing at least one of them (Invention 3).

  Further, the present invention is the magnetic composite particle according to any one of the present inventions 1 to 3, wherein the bio-base polymer has a molecular weight of 2,000 to 1,000,000 (Invention 4).

  Further, the present invention is a magnetic carrier comprising the magnetic composite particle according to any one of the present inventions 1 to 4 (Invention 5).

  Further, the present invention is a magnetic carrier in which a coating layer is formed on the surface of the magnetic composite particle according to any one of the present inventions 1 to 4 or the magnetic carrier according to the present invention 5 (Invention 6).

  Further, the present invention is a developer comprising the magnetic composite particle according to any one of the present inventions 1 to 4 or the magnetic carrier according to the present invention 5 or 6 (Invention 7).

  The magnetic composite particles according to the present invention are composed of a bio-based polymer and magnetic fine particles, are effective in reducing environmental burdens such as securing underground resources and preventing global warming, are safe for the human body, have high durability, Since a high-quality image can be developed, it is suitable for magnetic carriers and developers.

  Since the magnetic carrier according to the present invention is composed of magnetic composite particles having the characteristics as described above, it is effective in reducing environmental burdens such as securing underground resources and preventing global warming, and is safe for the human body and durable. It is suitable for magnetic carriers and developers because it has high properties and can develop high-quality images.

  Since the developer according to the present invention comprises magnetic composite particles and magnetic carriers having the characteristics as described above, it is effective in reducing environmental burdens such as securing underground resources and preventing global warming, and is safe for the human body. It is suitable for a developer because it has high durability and can develop a high-quality image.

  The configuration of the present invention will be described in more detail as follows.

  First, the magnetic composite particles according to the present invention will be described.

  The magnetic composite particles according to the present invention are magnetic composite particles in which at least magnetic fine particles and a biobase polymer are assembled. The average particle size of the magnetic composite particles is 10 to 100 μm. If it is less than 10 μm, the fluidity cannot be exhibited. When the average particle size of the magnetic composite particles is larger than 100 μm, high image quality cannot be exhibited. The average particle size of the preferred magnetic composite particles is 10 to 90 μm, more preferably 10 to 70 μm. The shape of the magnetic composite particles may be any shape such as spherical, granular, plate-like, or needle-like, but is preferably spherical or granular.

  The content of the magnetic fine particles contained in the magnetic composite particles according to the present invention is 50 to 99% by weight. When the content of the magnetic fine particles is less than 50% by weight, sufficient magnetism cannot be exhibited. When the content of the magnetic fine particles is more than 99% by weight, the binder does not function and the form of the composite particles cannot be maintained. The content of the magnetic fine particles is preferably 65 to 97% by weight, more preferably 65 to 95% by weight.

  The glass transition point of the biobase polymer in the present invention is 35 ° C. or higher. If the glass transition point is less than 35 ° C., the glass transition point may be lowered at room temperature, the magnetic composite particles become soft, and the durability when used for a magnetic carrier or a developer cannot be exhibited. Preferably, the glass transition point is 38 ° C. or higher, and more preferably, the glass transition point is 40 ° C. or higher.

  The bio-based polymer in the present invention is a polymer selected from polylactic acid, polyglycolic acid, trimethylene polyterephthalate, ethyl cellulose, poly-α-methylene-γ-butyrolactone, or a copolymer containing monomer units of these polymers Or it is preferable that it is a polymer mixture containing 1 or more types of them. Copolymers containing monomer units of bio-based polymers exist indefinitely. For example, polylactic acid-polyglycolic acid copolymer, polylactic acid-poly-ε-caprolactone copolymer, polylactic acid-polyglycolic acid-poly -Ε-caprolactone copolymer, polylactic acid-poly (dioxepanone) copolymer, polylactic acid-poly (ethylene oxalate) copolymer, polylactic acid-polymalic acid copolymer, polylactic acid-polymandelic acid copolymer , Poly-DL-lactic acid copolymer, and poly-α-methylene-γ-butyrolactone-poly-α-acetoxymethyl acrylate copolymer, etc. Even if a monomer or polymer that lowers is included, it can be used as long as the glass transition point is 40 ° C. or higher. There are an infinite number of polymer mixtures, for example, a mixture of L-polylactic acid and D-polylactic acid (including a stereo complex), a mixture of L-polylactic acid and poly-α-methylene-γ-butyrolactone, etc. Can be mentioned. These are prepared from biobases, are effective in reducing environmental impacts such as securing underground resources and preventing global warming, and are safe for the human body.

  When an optical isomer exists in the biobase polymer, any of L-form, D-form, racemic form, meso-form, and a stereocomplex that is a DL complex can be used. In addition, bio-based polymers include inorganic particles such as silica, titanium oxide, clay, talc, carbon black, and alumina, dibenzoylhydrazine octamethylene dicarboxylate, melamine, N, N ′, N ″ -tricyclohexyl-1,3. , 5-benzenetricarboxamide, carbodiimide, glycerol monostearate, glycerol, monopalmitate, glycerol monobehenate, glycerol monooleate, glycerol diacetomonolaurate, and other organic substances can be added.

  The molecular weight of the biobase polymer is 2,000 to 1,000,000. When the molecular weight of the biobase polymer is less than 2,000, the strength as a binder cannot be maintained. If the molecular weight of the biobase polymer is larger than 1,000,000, it is difficult to mold and composite particles cannot be formed. Preferably, the molecular weight of the biobase polymer is 4,000 to 800,000, more preferably 4,500 to 500,000.

  The content of the biobase polymer is 1 to 50% by weight. When the content of the biobase polymer is less than 1% by weight, the function as a binder does not work and composite particles cannot be formed. When the content of the biobase polymer is more than 50% by weight, sufficient magnetism cannot be exhibited. The content of the bio-based polymer is preferably 3 to 35% by weight, more preferably 5 to 35% by weight.

  Magnetic fine particles include iron oxide fine particles such as magnetite and maghemite, spinel ferrite fine particles containing one or more of Co, Ni, Zn and Cu, hexagonal ferrite fine particles containing Ba and Sr, garnet containing rare earths. Ferrite fine particles and fine particles of iron or iron alloy having an oxide film on the surface can be used. Preferably, it is iron oxide fine particles such as magnetite. The average particle diameter of the magnetic fine particles is 20 nm to 10 μm. Considering the strength of the magnetic composite particles, the average particle size of the magnetic fine particles is preferably 50 to 500 nm. More preferably, it is 50 nm-400 nm. Moreover, as a shape, any of spherical shape, a granular form, and a needle shape may be sufficient.

  Nonmagnetic fine particles can be added to the magnetic fine particles in order to adjust the magnetic properties and specific gravity of the magnetic composite particles. Nonmagnetic fine particles include Mg, Ca, Ba, Ti, Zr, Ta, V, Nb, Cr, Mo, W, Mn, Co, Ni, Cu, Ag, Au, Zn, Al, Ga, Si, and Ge. Compounds composed of oxides, hydroxides, carbonates and sulfates of one or more selected elements are preferred. For example, silicon oxide fine particles such as silica, titanium oxide fine particles such as rutile and anatase, aluminum compound fine particles such as alumina and boehmite, magnesium compound fine particles such as calcium carbonate fine particles, magnesia and hydrotalcite, zinc oxide fine particles, barium sulfate fine particles, Carbon-based fine particles such as carbon black and lamp black, preferably carbon-based fine particles, silicon oxide fine particles, titanium oxide fine particles, and aluminum compound fine particles. Considering the strength of the magnetic composite particles, the average particle size of the nonmagnetic fine particles is preferably 50 to 500 nm. More preferably, it is 50 nm-300 nm. Moreover, as a shape, any of spherical shape, a granular form, and a needle shape may be sufficient.

  The surface of the magnetic fine particle is preferably subjected to a hydrophobic surface treatment. The hydrophobic surface treatment is performed for the purpose of improving the adhesion between the magnetic fine particles and the bio-based polymer and forming strong magnetic composite particles. It also serves the purpose of exhibiting environmental stability such as moisture resistance after the formation of the magnetic composite particles.

Hydrophobic surface treatments include silane-based surface treatment agents, titanium-based surface treatment agents, organic compounds that bind to the surface through organic reactions, or hydrophobic surface treatments such as surfactants and hydrophobic resins. It may be made of any material, and may be one or a mixture of two or more.

Silane surface treatment agents include methyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, dimethyldiethoxysilane, trimethyltrimethoxysilane, triethylethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, and decyltrimethoxy. Silane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, triphenylethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, methacryloxypropyltriethoxysilane, trifluoropropyltrimethoxysilane, Methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, hexamethyldisilazane, hexaphenyldisilazane, Limethylsilane, allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, triorganosilane mercaptan, trimethylsilyl Examples include mercaptan, triorganosilyl acrylate, vinyldimethylacetoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane.
Titanium surface treatment agents include isopropoxy titanium / triisostearate, isopropoxy titanium / dimethacrylate / isostearate, isopropoxy titanium / tridodecylbenzene sulfonate, isopropoxy titanium / trisdioctyl phosphate, isopropoxy titanium / tris N-ethylaminoethylaminato, titanium bisdioctyl pyrophosphate oxyacetate, bisdioctyl phosphate ethylene dioctyl phosphite, di-n-butoxy bistriethanolaminato titanium and the like.

  Examples of organic compounds that bind to the surface of the magnetic fine particles through an organic reaction include caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, behenic acid, beef tallow fatty acid, castor fatty acid, Fatty acids such as soybean fatty acid, palmitoleic acid, oleic acid, linoleic acid, α-linolenic acid, γ-linolenic acid and their salts or esters or acid chlorides thereof, lauryl alcohol, myristyl alcohol, cetyl alcohol, octyl alcohol, decyl alcohol, Higher alcohols such as cetostearyl alcohol, stearyl alcohol, 2-octyldodecanol and behenyl alcohol, hydrophobic amino acids such as glycine, alanine, phenylalanine, leucine, isoleucine and valine, hydrophobic Peptides and proteins containing a large number of functional amino acids, thiophenol, butanethiol, pentanethiol, hexanethiol, heptanethiol, octanethiol, decylcyol, dodecylthiol and other thiols, ethyl chloride, butyl chloride, pentyl chloride, hexyl chloride, benzyl chloride And alkyl chlorides such as benzoyl chloride and hexyl carboxychloride.

  As the surfactant, glyceryl monostearate, glyceryl monooleate, glyceryl monocaprylate, propylene glycol monostearate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan dioleate, Examples include sorbitan trioleate, sorbitan sesquioleate, coconut fatty acid sorbitan, sorbitan monopalmitate, isostearyl glyceryl ether, lauryl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride and the like. Hydrophobic resins include the above-mentioned biobase polymers, biopolymers of styrene, homopolymers of styrene such as polystyrene and polyvinyltoluene, and substituted products thereof; styrene-propylene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene Copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer Styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-vinyl methyl ether copolymer, styrene- Vinylethyl Styrene copolymers such as ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester copolymer Combined; polymethyl methacrylate, polybutyl methacrylate, polyvinyl acetate, polyethylene, polypropylene, polyvinyl butyral, silicone resin, polyester resin, polyamide resin, epoxy resin, polyacrylic acid resin, rosin, modified rosin, terpene resin, phenol resin, fat Aromatic or alicyclic hydrocarbon resins, aromatic petroleum resins, paraffin wax, carnauba wax and the like.

  The treatment amount of the hydrophobic surface treatment agent is preferably from 0.1 to 20% by weight, more preferably from 0.1 to 10% by weight, based on the magnetic fine particles.

The bulk density of the magnetic composite particles according to the present invention is preferably 2.5 g / cm ³ or less, more preferably 1.5~2.5g / cm ^3.

  The specific gravity of the magnetic composite particles according to the present invention is preferably 2.5 to 5.2, more preferably 2.5 to 4.5.

BET specific surface area of the magnetic composite particles according to the present invention, 0.1~1.0m ² / g and is more preferably 0.1~0.9m ² / g.

  The fluidity of the magnetic composite particles according to the present invention is preferably 20 sec / 50 g or more.

The electric resistance of the magnetic composite particles according to the present invention is preferably 1 × 10 ⁷ to 1 × 10 ¹⁵ Ωcm, more preferably 5.0 × 10 ⁷ to 1 × 10 ¹² Ωcm.

The saturation magnetization value of the magnetic composite particles according to the present invention is preferably 20 to 80 Am ² / kg (20 to 80 emu / g), more preferably 40 to 80 Am ² / kg (40 to 80 emu / g).

  Next, a method for producing magnetic composite particles according to the present invention will be described.

  The magnetic composite particles according to the present invention can be obtained through each step of a surface treatment step, a dispersion step, a granulation step, and a post-treatment step.

  In the present invention, first, a hydrophobic surface treating agent is reacted or adsorbed on the surface of magnetic fine particles to obtain hydrophobic magnetic fine particles (surface treatment step). The hydrophobized magnetic fine particles are mixed and dispersed with an organic solvent in which a biobase polymer or the like is dissolved or dispersed to form a dispersed phase (dispersing step). This dispersed phase is added to and suspended in a continuous phase or a continuous phase containing a suspension stabilizer to prepare a droplet suspension of a desired size. Heat is applied to this suspension, and the organic solvent in the droplets is dried and granulated without drying the continuous phase to obtain a magnetic composite particle slurry (granulation step). This slurry is sufficiently washed and dried to obtain magnetic composite particles (post-treatment step). Moreover, you may classify as needed.

  The surface treatment step is a step in which the above-described hydrophobic surface treatment agent is reacted or adsorbed on the magnetic fine particles to make the surface hydrophobic, thereby improving the adhesion with the biobase polymer.

  The surface treatment may be dry or wet. In the case of the dry type, a wheel-type kneader, a blade-type kneader, a ball-type kneader, a roll-type kneader, or the like can be used. In the case of a wet process, a ball mill, a sand mill, an attritor, a roll mill, a bead mill, a colloid mill, an ultrasonic homogenizer, a high pressure homogenizer, or the like can be used.

  The dispersion step is a step of preparing a dispersed phase by dispersing hydrophobic surface-treated magnetic fine particles in an organic solvent in which a biobase polymer or the like is dissolved or dispersed.

  The organic solvent needs to be a solvent that can dissolve or disperse the biobase polymer and does not dissolve in the continuous phase. Specifically, dichloromethane, chloroform, carbon tetrachloride, chloroethane, 1,2-dichloroethane, 1,1-dichloroethylene, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, trichloroethylene, tetrachloroethylene, 1,2 -Dichloroethyl ether, dibromomethane, bromoform, carbon tetrabromide, bromoethane, 1,2-dibromoethane, 1,1-dibromoethylene, 1,2-dibromoethyl ether, hexane, cyclohexane, benzene, toluene, xylene, chlorobenzene , Methyl ethyl ketone, ethyl acetate, diethyl ether, dibutyl ether, tetrahydrofuran, 1,4-dioxane, supercritical carbon dioxide and the like.

  Examples of the apparatus that performs dispersion include a ball mill, a sand mill, an attritor, a roll mill, a bead mill, a colloid mill, an ultrasonic homogenizer, and a high-pressure homogenizer.

  In the granulation step, the dispersed phase prepared in the dispersing step is added to and suspended in the continuous phase or the continuous phase containing the suspension stabilizer to prepare a droplet suspension of the desired size. In this step, the organic solvent in the droplets is dried and granulated without applying heat or the like to dry the continuous phase to obtain magnetic composite particles.

  As the suspension stabilizer, colloidal silica, a silane coupling agent, a surfactant and the like can be used.

  Examples of colloidal silica include those in which silica is colloidally dispersed in water, and those that are acidic, neutral, and basic are dispersed.

  As silane coupling agents, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycid Xylpropyldiethoxysilane, styryloxymethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3- Acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (amino Ethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl -3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane sulfate, 3-ureidopropyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3- Mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, methyltriethoxy Silane, dimethyl diethoxy silane, phenyl triethoxy silane, hexamethyldisilazane, hexyltrimethoxysilane, decyltrimethoxysilane, etc. fluoropropyl trimethoxysilane.

  As the surfactant, glyceryl monostearate, glyceryl monooleate, glyceryl monocaprylate, propylene glycol monostearate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, sorbitan monooleate, sorbitan dioleate, Examples include sorbitan trioleate, sorbitan sesquioleate, coconut fatty acid sorbitan, sorbitan monopalmitate, isostearyl glyceryl ether, lauryl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride and the like.

  The continuous phase needs to be a medium that can be sufficiently suspended without dissolving the dispersed phase. Specifically, water, methanol, ethanol, 2-propanol, butanol, ethylene glycol, glycerin, polyethylene glycol and the like.

  Examples of the suspension apparatus include a homomixer, a homogenizer, a high-pressure homogenizer, an ultrasonic homogenizer, a stirrer, an internal circulation type stirrer, an external circulation type stirrer, and a thin film swirl type stirrer.

  In the present invention, the concentration of the suspension and the stirring conditions of the apparatus for performing the suspension may be set so as to obtain a desired droplet.

  In the present invention, the heat treatment may be performed in a temperature range where the organic solvent volatilizes.

  In the post-treatment process, to remove the suspension stabilizer added in the granulation process and impurities generated by the preparation, washing with water, adding sodium hydroxide, potassium hydroxide, acetic acid, hydrochloric acid, sulfuric acid, etc. as necessary, washing with water. In this process, the magnetic composite particles are purified, separated, and finally dried. Further, classification may be performed in order to obtain a target particle size and particle size distribution.

  Washing and separation are performed by filtration such as centrifugal separation, suction filtration, pressure filtration, ultrafiltration, and reverse osmosis membrane filtration.

  In drying, it may be taken out using a conventional method such as ventilation drying, vacuum drying, spray drying, freeze drying and the like.

  Classification is performed using a classification device such as an electromagnetic sieve, a turbo screener, or a turbo crash fire.

  Next, the magnetic carrier according to the present invention will be described.

  Magnetic composite particles can be used as they are for the magnetic carrier according to the present invention. Furthermore, in order to control the charge amount and the electric resistance, a coat layer can be formed on the particle surface of the magnetic composite particles.

  Examples of the coating layer include coupling agents, inorganic fine particles, and resins. They may be used alone or in combination. The coat layer is preferably coated on the magnetic composite particles in an amount of 0.5 to 2.5% by weight.

  Examples of coupling agents include silane and titanium. Examples of silane coupling agents include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, and 2- (3,4-epoxycyclohexyl) ethyltrimethoxy. Silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyldiethoxysilane, styryloxymethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyl Methyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3-Dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane sulfate, 3-ureido Propyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, teto Silane, tetraethoxy silane, methyl triethoxy silane, dimethyl diethoxy silane, phenyl triethoxy silane, hexamethyldisilazane, hexyltrimethoxysilane, decyltrimethoxysilane, fluoroethyl triethoxysilane, and the like. Titanium coupling agents include isopropoxy titanium / triisostearate, isopropoxy titanium / dimethacrylate / isostearate, isopropoxy titanium / tridodecyl benzene sulfonate, isopropoxy titanium / trisdioctyl phosphate, isopropoxy titanium / tris N-ethylaminoethylaminato, titanium bisdioctyl pyrophosphate oxyacetate, bisdioctyl phosphate ethylene dioctyl phosphite, di-n-butoxy bistriethanolaminato titanium and the like.

  As inorganic fine particles, Mg, Ca, Ba, Ti, Zr, Ta, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Ag, Au, Zn, Al, Ga, Si, Ge A compound comprising an oxide, hydroxide, carbonate, or sulfate of one or more elements selected from the above is preferred. For example, silicon oxide fine particles such as silica, titanium oxide fine particles such as rutile and anatase, aluminum compound fine particles such as alumina and boehmite, magnesium compound fine particles such as calcium carbonate fine particles, magnesia and hydrotalcite, zinc oxide fine particles, barium sulfate fine particles, Iron oxide fine particles such as hematite, magnetite and goethite, and carbon fine particles such as carbon black and lamp black, preferably silicon oxide fine particles, titanium oxide fine particles and aluminum compound fine particles.

  Examples of the resin include the aforementioned bio-based polymer. Moreover, saccharides, such as chitin, chitosan, alginic acid, amylose, and cellulose, are also mentioned. Furthermore, an acrylic resin, a styrene acrylic resin, a silicone resin, a polyester resin, a urethane resin, or a copolymer obtained by copolymerizing two or more of them is preferable. Specifically, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, α-methylstyrene, chlorostyrene, bromostyrene, divinylbenzene, trivinylbenzene, 4-methoxystyrene, Polymers of monomers selected from styrene monomers and derivatives thereof such as 4-cyanostyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 2-vinylphenanthrene, and styrene macromer, or acrylic acid, methyl acrylate, acrylic acid Ethyl, propyl acrylate, butyl acrylate, ethyl hexyl acrylate, octyl acrylate, stearyl acrylate, lauryl acrylate, acrylonitrile, acrylamide, dimethylaminoethyl acrylate, methacrylic acid, methacrylic acid Chill, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethyl hexyl methacrylate, octyl methacrylate, stearyl methacrylate, lauryl methacrylate, glycidyl methacrylate, methacrylonitrile, methacrylamide, dimethylaminoethyl methacrylate, itaconic acid, Acrylic acid series such as methyl itaconate, ethyl itaconate, fumaric acid, dimethyl fumarate, diethyl fumarate, maleic acid, dimethyl maleate, diethyl maleate, crotonic acid, methyl crotonic acid, ethyl crotonic acid, methyl methacrylate macromer Polymer of monomer selected from monomers and derivatives thereof, or styrene-vinyltoluene copolymer, styrene-vinylnaphthalene copolymer, styrene-methyl acrylate copolymer Styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-dimethylaminoethyl acrylate copolymer, styrene-methyl methacrylate copolymer, styrene- Ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-dimethylaminoethyl methacrylate copolymer, styrene-maleic acid copolymer, styrene-maleic acid half ester copolymer, styrene-maleic acid diester Copolymer, acrylic acid-methacrylic acid copolymer, acrylic acid-methacrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-methyl methacrylate-acrylic acid copolymer, styrene- Such as methacrylic acid-acrylic acid copolymer Styrene acrylic resin such as block copolymer, random copolymer or graft copolymer polymerized from more than one kind of monomers, straight methyl silicone resin, methylphenyl silicone resin, epoxy modified silicone resin, alkyd modified silicone Resin, polyester-modified silicone resin, acrylic-modified silicone resin, and other silicone resins such as side chain, single-end, double-end, and side-chain double-end modified silicone oil, terephthalic acid, isophthalic acid, orthophthalic acid, 2 , 6-Naphthalenedicarboxylic acid, sodium sulfoisophthalate, succinic acid, adipic acid, azelaic acid, sebacic acid, 1,10-decanedicarboxylic acid, dimer acid and other divalent carboxylic acids, trimellitic acid, pyromellitic acid, etc. A polyvalent carboxylic acid such as a carboxylic acid having a valency or higher and ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol 1,9-nonanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene glycol, polytetraethylene glycol, 1,4-cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, etc. Polyesters of polyhydric alcohols such as trihydric alcohols such as dihydric alcohols, trimethylolpropane and pentaerythritol, or polyesters such as block copolymers, random copolymers and graft copolymers thereof Tree Polypropylene glycol, polyethylene glycol, polytetramethylene glycol, poly (ethylene adipate), poly (diethylene adipate), poly (propylene adipate), poly (tetramethylene adipate), poly (hexamethylene adipate), poly-ε-caprolactone , Polyols such as poly (hexamethylene carbonate) and silicone polyol, and tolylene diisocyanate, 4,4-diphenylmethane diisocyanate, xylylene diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated 4,4-diphenylmethane Of isocyanates such as diisocyanate, isophorone diisocyanate, tetramethylxylylene diisocyanate Polymers with urethane bonds, or urethane resins such as block copolymers, random copolymers, graft copolymers, styrene acrylic resins-polyester resin copolymers, styrene acrylic resins-urethane resin copolymers, etc. Examples include copolymers between resins.

The electric resistance of the magnetic carrier according to the present invention is preferably 1 × 10 ⁷ to 1 × 10 ¹⁷ Ωcm, more preferably 1 × 10 ⁷ to 1 × 10 ¹⁶ Ωcm.

  Next, a method for producing a magnetic carrier according to the present invention will be described.

  Magnetic composite particles can be used as they are for the magnetic carrier according to the present invention. In order to control the charge amount and the electrical resistance, a coat layer can be formed on the surface. In that case, the coupling agent, inorganic fine particles, and resin are used as they are, or suspended or dissolved in water or an organic solvent, and mixed agitator, universal agitator, wheel-type kneader, blade-type kneader, ball-type kneader. Surface coating can be performed using a machine, a roll-type kneader, a rolling fluidized bed coating apparatus, or the like. In addition, after coating, drying, baking, and classification can be performed as necessary.

Next, the developer according to the present invention will be described.

  For the developer according to the present invention, magnetic composite particles and magnetic carriers can be used as they are. Furthermore, various magnetic toners and non-magnetic toners can be mixed and used as a developer.

  Next, a method for producing the developer according to the present invention will be described.

  For the developer according to the present invention, magnetic composite particles and magnetic carriers can be used as they are. Further, when various magnetic toners and non-magnetic toners are mixed and used as a developer, they can be prepared using a ball mill, a paint conditioner, a stirring mixer, a tumbler, a shaker, or a mixer.

<Action>
The magnetic composite particle according to the present invention is a composite particle that is coated with a bio-based polymer and becomes a binder, whereby magnetic fine particles form an aggregate. Further, since the magnetic composite particles have a small bulk density and excellent fluidity as compared with iron powder and ferrite, they have high durability as themselves or as magnetic carriers and developers. Moreover, since it is prepared by granulation, it is suitable for reducing the particle size, and a high-quality image can be developed. In addition, because it uses a bio-based polymer, it is effective in reducing environmental impacts such as securing underground resources and preventing global warming, and is safe for the human body.

  Since the magnetic carrier according to the present invention is composed of magnetic composite particles having the characteristics as described above, it has high durability and can develop high-quality images. It is also effective in reducing environmental burdens and is safe for the human body.

  Since the developer according to the present invention comprises magnetic composite particles or magnetic carriers having the characteristics as described above, it has high durability and can develop high-quality images. It is also effective in reducing environmental burdens and is safe for the human body.

  Next, the present invention will be described in more detail with reference to examples. In the text, “parts” and “%” are based on mass. The present invention is not limited to the following examples.

  The infrared absorption spectrum is data measured by a Shimadzu Fourier transform infrared spectrophotometer FTIR-8700.

  The average particle diameters of the magnetic fine particles and the magnetic composite particles are data on a volume basis by a laser diffraction particle size distribution analyzer LA-750 manufactured by Horiba.

  The BET specific surface area is data by Monosorb MS-21 manufactured by Yuasa Ionics.

  The weight average molecular weight (Mw) of the polymer is data measured by a GPC method using Hitachi High Performance Liquid Chromatograph LaChrom Elite, Tosoh SEC column TSKgelMultiporeHXL-M.

  The saturation magnetization is a measurement value of a vibrating sample magnetometer VSM-3S-15 manufactured by Toei Industry Co., Ltd., an external magnetic field 795.8 kA / m (10 kOe).

  True specific gravity is a value measured with a multi-volume density meter made by Micromeritics.

  The bulk density followed the method described in JIS K 5101.

  The electric resistance value (volume specific resistance value) is a value (applied voltage of 100 V) measured by a high resistance meter 4329A made by Yokogawa Hewlett-Packard.

  The fluidity was measured according to the method described in JIS Z 2502, and the fluidity was measured. The fluidity of 20 (sec / 50 g) or more was evaluated as ◯, and the fluidity of less than 20 (sec / 50 g) was evaluated as ×.

  The glass transition point was measured using a differential scanning calorimeter DSC6200 manufactured by Seiko Instruments.

  Detection of the residual organic solvent (1,2-dichloroethane, etc.) of the magnetic composite particles was quantified using a gas chromatograph, Claus 500, manufactured by Perkin Elmer.

  X-ray diffraction was measured by an X-ray diffractometer RINT2500 manufactured by Rigaku Corporation.

  The environmental load reduction was evaluated as ○ when using a material with low environmental load, and × when using a material with environmental load such as petroleum-derived polymer.

  The safety to the human body was evaluated as ◯ when a polymer safe for the human body was used, and x when a polymer that was not safe for the human body was used.

  For durability, the magnetic composite particles were put into a tumbler shaker mixer T2F made by Shinmaru Enterprises, shaken at 101 rpm for 2 hours, and the surface of the magnetic composite particles before and after shaking was scanned by Hitachi scanning electron microscope S-4800. When the particles were observed to be deteriorated such as binding, deformation, and peeling, “x” was given, and those without change were marked with “◯”.

(Toner Production Example 1)
Polyester resin 100 parts by weight Copper phthalocyanine 5 parts by weight Charge control agent (quaternary ammonium salt) 4 parts by weight Low molecular weight polyolefin 3 parts by weight Preliminarily mixed with a Henschel mixer and melted with a twin screw extruder kneader The mixture was kneaded, cooled, and pulverized and classified using a hammer mill to obtain a positively charged blue powder having a weight average particle diameter of 7 μm.

  100 parts by weight of the positively charged blue powder and 1 part by weight of hydrophobic silica were mixed with a Henschel mixer to obtain a positively charged cyan toner a.

(Toner Production Example 2)
Polyester resin 100 parts by weight Copper phthalocyanine 5 parts by weight Charge control agent (di-tert-butylsalicylic acid zinc compound) 3 parts by weight Wax 9 parts by weight The above materials are sufficiently premixed in a Henschel mixer, and a twin-screw extrusion kneader The mixture was melt-kneaded, and after cooling, pulverized and classified using a hammer mill to obtain a negatively charged blue powder having a weight average particle diameter of 7 μm.

  100 parts by weight of the negatively charged blue powder and 1 part by weight of hydrophobic silica were mixed with a Henschel mixer to obtain a negatively charged cyan toner b.

<Surface treatment process>
(Surface treatment example 1)
After 100 parts by weight of spherical magnetite fine particles (average particle size 230 nm) are placed in a flask, the atmosphere is purged with nitrogen and sufficiently stirred, 1.5 parts by weight of stearic acid is added, the temperature is raised to 80 ° C., and the temperature is increased to 30 under a nitrogen atmosphere. By stirring well, hydrophobic magnetic fine particles 1 coated with stearyl groups were obtained.

(Surface treatment example 2)
Hydrophobic magnetic fine particles 1 except that 100 parts by weight of hexahedral magnetite fine particles (average particle size 230 nm) are placed in a flask, purged with nitrogen, sufficiently stirred, and then 1.2 parts by weight of decyltrimethoxysilane is added. An operation under the same conditions was performed to obtain hydrophobic magnetic fine particles 2 coated with a decylsilyl group.

(Surface treatment example 3)
The hydrophobic magnetic fine particles 3 coated with a decylsilyl group were prepared under the same conditions as the hydrophobic magnetic fine particles 2 except that 100 parts by weight of the hexahedral magnetite fine particles were changed to octahedral magnetite fine particles (average particle size 300 nm). Obtained.

[Example 1] (Magnetic composite particles using polylactic acid)
<Dispersing process>
Hydrophobic magnetic fine particle 1 10 parts by weight L-polylactic acid (Mw = 86,000) 2 parts by weight 1,2-dichloroethane 38 parts by weight The above materials were sufficiently dispersed using a Branson ultrasonic homogenizer S-250D.
<Granulation process>
This dispersion was poured into 1000 parts by weight of water and suspended at 3,000 rpm with a special mixer made by Homomixer to obtain a droplet suspension of about 40 μm. The suspension was stirred with a stirring blade while bubbling nitrogen gas, and heated to 90 ° C. to evaporate 1,2-dichloroethane in the droplets. (All steam was recovered and 1,2-dichloroethane was recovered and reused.)
<Post-processing process>
This slurry was washed with water and vacuum dried, and fine particles and coarse particles were removed using a sieve having openings of 25 μm and 100 μm to obtain magnetic composite particles in the present invention. The obtained magnetic composite particles had an average particle size of 34 μm, a bulk density of 1.9 g / cm ³ , a specific gravity of 3.2 g / cm ³ and a saturation magnetization of 70 Am / kg. The electric resistance value was 3.8 × 10 ⁸ Ωcm, and the BET specific surface area was 0.3 g / m ² . (Residual 1,2-dichloroethane was not detected in the magnetic composite particles.)

The composition analysis of the obtained magnetic composite particles was performed as follows. 1.00 parts by weight of magnetic composite particles were collected and subjected to Soxhlet extraction using 1,2-dichloroethane, and the dissolved component was extracted into 1,2-dichloroethane. The remaining insoluble component was 0.82 parts by weight. From the X-ray diffraction of this insoluble component, it was identified as magnetite. The particle size was 220 nm. Further, when the fine particles were floated on water, they were not mixed with water, and thus were found to be hydrophobic.
Next, when methanol was added to the 1,2-dichloroethane extract, a white precipitate was generated. When this white precipitate was dried and weighed, it was 0.18 part by weight. When the infrared absorption spectrum of this white precipitate was measured, it was identified as polylactic acid. The weight average molecular weight of this polylactic acid was measured and found to be 86,000. The content of magnetic fine particles was 82% by weight. Moreover, the glass transition point was 56 degreeC.

[Example 2] to [Example 12]
Magnetic composite particles were obtained in the same manner as in Example 1, except that the type and amount of hydrophobic magnetic fine particles, the type and amount of biobase polymer, the type and amount of organic solvent, and the suspension speed were changed.

[Comparative Example 1] (When petroleum-derived polymer is used)
Magnetic composite particles were obtained in the same manner as in Example 1 except that styrene-methyl methacrylate copolymer (weight average molecular weight 80,000) was used instead of L-polylactic acid. The average particle size of the obtained magnetic composite particles was 30 μm. However, since petroleum-derived polymers are used, environmental impact is not taken into consideration, and the effect on reducing environmental impacts such as securing underground resources and preventing global warming is low.

[Comparative Example 2] (When the particle size of the magnetic composite particles is small)
Magnetic composite particles were obtained in the same manner as in Example 1 except that the suspension speed in the homomixer was 12,000 rpm. The average particle size of the obtained magnetic composite particles was 8 μm. With this particle size, the fluidity of the particles could not be obtained, and it was not suitable for electrophotographic development.

[Comparative Example 3] (When the content of magnetic fine particles is small)
Hydrophobic magnetic fine particles 1 5 parts by weight Polylactic acid (Mw = 86,000) 7 parts by weight 1,2-dichloroethane 38 parts by weight Magnetic composite particles were obtained in the same manner as in Example 1 except that the blending of the above materials was performed. . The average particle size of the obtained magnetic composite particles was 35 μm. With this magnetic fine particle content, sufficient magnetism could not be obtained and it was not suitable for electrophotographic development.

[Comparative Example 4] (When petroleum-derived polymer and natural polymer polysaccharide are used)
Styrene-butyl methacrylate copolymer (70 parts of styrene component) 40 parts by weight Polysaccharide of natural polymer as biodegradable substance “Ebara Kogyo brand name ECOSTAR” 10 parts by weight Iron trioxide (made by Toda Kogyo Co., Ltd.) Name MTA-740) 60 parts by weight Carbon black (BPL manufactured by Cabot Corporation) 3.5 parts by weight The above was melt-kneaded, cooled and ground to obtain a magnetic fine powder. This fine powder was classified with an air classifier to obtain a magnetic fine powder carrier having an average particle size of 40 μm. However, since petroleum-derived polymers are used, environmental impact is not taken into consideration, and the effect on reducing environmental impacts such as securing underground resources and preventing global warming is low. Further, with the content of the magnetic fine particles, sufficient magnetism cannot be obtained, and it is not suitable for electrophotographic development. The glass transition point of the polymer was 0 ° C.

[Comparative Example 5] (When 3-hydroxybutyrate-3-hydroxyvalerate copolymer is used)
3-hydroxybutyrate-3-hydroxyvalerate copolymer (average molecular weight = 40,000)
100 parts by weight Magnetite 400 parts by weight The above was mixed with a Henschel mixer, melt-kneaded with two rolls, pulverized and classified to obtain a binder-type carrier having an average particle size of 50 μm. However, the obtained particles were soft and inferior in durability. The glass transition point of the polymer was -1 ° C.

[Comparative Example 6] (When an alloy of starch and polyvinyl alcohol is used)
Alloy of starch and modified polyvinyl alcohol (average molecular weight = 30,000) 100 parts by weight Magnetite 400 parts by weight Except that the material was changed as described above, it was prepared in the same manner as in Comparative Example 6 to obtain a binder type carrier having an average particle size of 40 μm. It was. However, the obtained particles were soft and inferior in durability. The glass transition point of the polymer was 20 ° C.

[Comparative Example 7] (When using butylene polysuccinate)
Butylene polysuccinate (average molecular weight 50,000) 100 parts by weight Magnetite 400 parts by weight A binder-type carrier having an average particle size of 60 μm was prepared in the same manner as in Comparative Example 6 except that the material was changed as described above. However, the obtained particles were soft and inferior in fluidity. The glass transition point of the polymer was −40 ° C.

[Comparative Example 8] (When polybutylene succinate and styrene acrylic copolymer are used)
Butylene polysuccinate (average molecular weight 50,000) 60 parts by weight Styrene acrylic copolymer 40 parts by weight Magnetite 400 parts by weight A binder having an average particle diameter of 60 μm was prepared in the same manner as in Comparative Example 6 except that the materials were changed as described above. A mold carrier was obtained. However, the obtained particles were soft and inferior in fluidity. The glass transition point of the polymer was −40 ° C.

  The production conditions of the obtained magnetic composite particles are shown in Table 1, and various properties are shown in Table 2.

  As shown in Tables 1 and 2, since the magnetic composite particles according to the present invention use a bio-based polymer, they are effective in reducing environmental burdens such as securing underground resources and preventing global warming. It is inevitable that it is very safe and highly durable. Further, it has a small bulk density and excellent fluidity, and when used as a magnetic carrier raw material, magnetic carrier or developer, it is clear that it is very excellent. Moreover, it is prepared by granulation and is suitable for high image quality.

[Magnetic carrier]
[Example 13] to [Example 24], [Comparative Example 9] to [Comparative Example 16]
The magnetic composite particles and the toner are blended at the following blending ratio, shaken for a predetermined time with a tumbler, shaker, and mixer T2F made by Shinmaru Enterprises, and the charge amount of the toner is measured. The performance as a carrier was evaluated.
Magnetic carrier (magnetic composite particles) 92 parts by weight Toner 8 parts by weight

  The charge amount of the toner was measured using a blow-off charge amount measuring device TB-200 manufactured by Kyocera Chemical. Then, the rate of change in the charge amount is obtained by dividing the charge amount value after shaking for 1 minute by the initial charge amount value and dividing the difference from the charge amount value after shaking for 2 hours by the initial charge amount value. The value was multiplied by 100 and expressed as a percentage. The results are shown in Table 3.

[Magnetic carrier] (formation of surface coat layer)
[Example 25]
100 parts by weight of magnetic composite particles (Example 1) were placed in a Dalton mixing stirrer 5XDML-03-r and stirred at 40 ° C. A solution prepared by dissolving 1 part by weight of ethyl cellulose (Mw = 30,000) in 20 parts by weight of ethyl acetate was added thereto, followed by stirring at 40 ° C. for 2 hours under a nitrogen stream. (All the ethyl acetate vapor was recovered, and ethyl acetate was recovered and reused.) After that, the temperature was raised to 80 ° C. and stirred for 2 hours. The magnetic particles (surface coat layer formation) in the present invention were obtained by removing fine particles and coarse particles from the obtained particles using sieves with openings of 25 μm and 100 μm. The electric resistance of the magnetic carrier was 4.0 × 10 ¹² Ωcm. In the same manner as described above, the charge amount of the toner was measured by mixing with the toner, and the change rate of the charge amount of the toner was 5%.

[Example 26]
The same as in Example 25 except that 0.1 part by weight of carbon black (average particle size 20 nm) was further added to a solution obtained by dissolving 1 part by weight of ethyl cellulose in 20 parts by weight of ethyl acetate, and a liquid sufficiently dispersed with an ultrasonic homogenizer was used. Thus, the magnetic carrier (surface coat layer formation) in the present invention was obtained. The electric resistance of the magnetic carrier was 2.0 × 10 ¹¹ Ωcm. The change rate of the toner charge amount was 7%.

[Example 27] to [Example 35]
Magnetic properties were the same as in Examples 26 and 27 except that the type and amount of magnetic carrier (magnetic composite particles), the type and amount of resin, the type and amount of inorganic fine particles, and the type and amount of organic solvent were changed. A carrier (surface coat layer formation) was obtained. The results are shown in Table 4.

  As shown in Tables 3 and 4, it is clear that the magnetic carrier according to the present invention has high durability. In addition, since bio-based polymers are used, it is clear that it is effective in reducing environmental impacts such as securing underground resources and preventing global warming, and is safe for the human body.

[Developer]
A magnetic carrier and a toner were blended in the following blending ratio and mixed with a universal ball mill UB-32 manufactured by Yamato to obtain a developer.
Magnetic composite particles 92 parts by weight Toner 8 parts by weight

  Using this developer and toner, a printing test of characters and solids was performed with LS-C5016N manufactured by Kyocera Mita. As the image clarity, the first image with a beautiful image quality was marked with ◯, and the first image with a blurred character or solid portion was marked with x. Further, as image durability, ○ was printed with 1000 sheets without deterioration, Δ was printed with 500 sheets without deterioration, and X was printed with less than 500 sheets. The results are shown in Table 5.

  As shown in Table 5, it is clear that the developer according to the present invention has high image sharpness and image durability. In addition, since bio-based polymers are used, it is clear that it is effective in reducing environmental impacts such as securing underground resources and preventing global warming, and is safe for the human body.

  The magnetic composite particles according to the present invention are composed of a bio-based polymer and magnetic fine particles, are effective in reducing environmental burdens such as securing underground resources and preventing global warming, are safe for the human body, have high durability, Since a high-quality image can be developed, it is suitable for magnetic carriers and developers.

  Since the magnetic carrier according to the present invention is composed of magnetic composite particles having the characteristics as described above, it is effective in reducing environmental burdens such as securing underground resources and preventing global warming, and is safe for the human body and durable. It is highly suitable for developing high-quality images and is suitable for magnetic carriers and developers.

  Since the developer according to the present invention comprises magnetic composite particles and magnetic carriers having the characteristics as described above, it is effective in reducing environmental burdens such as securing underground resources and preventing global warming, and is safe for the human body. Yes, it is highly durable and can develop high-quality images, and is suitable as a developer.

Claims (5)

Magnetic composite particles comprising at least magnetic fine particles and a bio-based polymer, wherein the magnetic composite particles have an average particle size of 10 to 100 μm, and the content of the magnetic fine particles in the magnetic composite particles is 50 to 99% by weight. The bio-based polymer is a polymer selected from polylactic acid, polyglycolic acid, trimethylene polyterephthalate, poly-α-methylene-γ-butyrolactone, a copolymer containing monomer units of these polymers, or a polymer mixture comprising one or more thereof, the magnetic composite particles having a glass transition point of the bio-based polymer, characterized in der Rukoto 45 ° C. or higher. Magnetic composite particles according to claim 1 Symbol placement molecular weight of bio-based polymer is characterized by a 2,000 to 1,000,000. Magnetic carrier which comprises magnetic composite particles according to claim 1 or 2. A magnetic carrier having a coat layer formed on the surface of the magnetic composite particle according to claim 1 or 2 , or the magnetic carrier according to claim 3 . A developer comprising the magnetic composite particle according to claim 1 or 2 or the magnetic carrier according to claim 3 or 4 .