JPH0578835B2 - - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to magnetic carrier particles for electrophotographic development. More specifically, the present invention relates to magnetic carrier particles used particularly in magnetic brush development. Prior Art and its Problems Conventionally, as one of the magnetic carrier particles used in magnetic brush development for electrophotographic development, iron powder or so-called ferrite particles coated with a resin have been used. By the way, such magnetic carrier particles triboelectrically charge the toner to electrostatically adhere the toner and move the toner onto the photoreceptor during development. For this reason, it is required that the carrier particles have a large amount of triboelectric charge, have uniform chargeability, and that the toner can be effectively and uniformly taken up and deposited. In this case, the amount of charge is preferably within the range of 15 to 40 μC/g. Furthermore, even when using various toners, it is desirable to keep the charge amount within the above range, but currently the charge amount is controlled by a charge control agent added to the toner, which results in high cost, poor stability of the charge amount, and Humidity dependence is a problem. On the other hand, carrier particles must have good transportability in a developing machine and are required to exhibit good fluidity as a powder. In this case, it is desirable that the falling speed of 50 g of powder, which is an indicator of fluidity, be as small as possible within the range of 25 to 35 seconds. Furthermore, the carrier particles function as one electrode in the developing area and play a role in making the electrolysis uniform.By changing the composition of the magnetic particles coated with resin, the carrier particles can also be Therefore, it is required to have a desired resistance in the range of 10 ⁵ to 10 ¹² Ω depending on the copying machine. Furthermore, it is desired that this electrical resistance does not decrease under high humidity conditions. Further, the carrier particles are required to have durability in order to stably maintain and exhibit the above-mentioned properties in the developing machine. However, conventional resin coating materials do not satisfy all of these characteristics. Purpose of the Invention The purpose of the present invention is to provide magnetic carrier particles for electrophotographic development that have stable electrical resistance and flow characteristics, can arbitrarily control the amount of triboelectric charge, and have sufficiently high moisture resistance and durability. be. DISCLOSURE OF THE INVENTION Such objects are achieved by the present invention as described below. That is, the present invention provides magnetic carrier particles for electrophotographic development, characterized in that the surface of the magnetic particles is coated with a synthetic resin obtained by emulsion polymerization of a monoethylenic monomer using a polymerizable emulsifier. . Specific Configuration of the Invention The specific configuration of the present invention will be described in detail below. The magnetic carrier particles for electrophotographic development of the present invention are
The magnetic particles have a resin coating on their surface. The coating is formed using a synthetic resin emulsion obtained by emulsion polymerization of a monoethylenic monomer using a polymerizable emulsifier. The polymerizable emulsifier is preferably one or more of allyl alcohol derivatives, acrylic acid derivatives, itaconic acid derivatives, maleic acid derivatives, fumaric acid derivatives, ethylene derivatives, and styrene derivatives. Specific examples of the polymerizable emulsifier are shown below. Allyl alcohol derivative

[Chemical] (Japanese Patent Publication No. 49-46291, JP-A No. 58-203960) R ₁ : Hydrogen or methyl group R ₂ : Hydrocarbon group or hydrocarbon having a substituent or organic group containing oxyalkylene group A: Carbon alkylene group or substituted alkylene group of numbers 2 to 4 n: 0 or a positive number M: alkali or alkaline earth metal, ammonium, organic amine base or organic quaternary ammonium base, etc. m: valence or ion of M Valence −1 n=0, R ₁ =H, R ₂ =C ₁₂ H ₂₅ , M1/m=Na, −2 n=1, A=CH ₂ CH(OH)CH ₂ , R ₁ =H, R ₂ = _C12H25 , M1/m=Na, -3 n=1, A= _CH2CH ( _OH )CH2, _{R1 =} H, _R2 = _{C18H37 ,} M1/m=Na, -4 n=1 _{, A=CH2CH(OH)CH2, R1=H, R2=C18H37 , M1 / m = NH4} , -5 n=0, _R1 =H, R ₂ = CH ₂ CH (C ₉ H ₁₉ ) (C ₇ H ₁₅ ) acrylic acid derivative R ₁ CH=C (R ₂ ) CONH−SO ₃ M (Special Publication No. 12472/1972) R ₁ , R ₂ : Hydrogen atoms or an organic residue having 1 to 10 carbon atoms, preferably a hydrocarbon residue, more preferably an alkyl or aryl group, more preferably a methyl or phenyl group M: alkali metal - preferably potassium -1 R ₁ =H , _R2 = _{C10H21 , M=K, -2 R1=H, R2=C10H21 , M =} Na, -3 _R1 =H _{, R2} = _CH2 , M=K,

[Chemical formula] (JP-A No. 54-144317) R ₁ , R ₂ : Hydrogen atom or methyl group R ₃ : Alkyl group or alkenyl group having 7 to 21 carbon atoms M: Alkali metal or ammonium group -4 R ₁ =H , R ₂ = H, R ₃ = C ₇ H ₁₅ , M = Na −5 R ₁ = H, R ₂ = CH ₃ R ₃ = C ₂₁ H ₄₃ , M = NH ₄ −6 R ₁ = H, R ₂ =H, _{R3 = C18H35} , M=Na

[Chemical] (JP-A-55-11525) R ₁ , R ₂ : Hydrogen atom or methyl group R ₃ : Saturated or unsaturated aliphatic hydrocarbon group having 1 to 21 hydrogen atoms M: Alkali metal or ammonium group -7 _R1 =H, _R2 = _CH3 , _{R3 = C12H25} , M=Na, -8 _R1 =H, _R2 = _H , _R3 = _C12H25 , M=K, -9R ₁ = _CH3 , _R2 = _CH3 , _R3 = _C18H37 , M= _{NH4 ,}

[C] (JP-A No. 56-28208) R ₁ , R ₂ : Hydrogen atom or methyl group X, Y, Z: 0 or an integer of 100 or less,
The following function holds: 1≦X+Y+Z≦100 −10 R ₁ =H, R ₂ =CH ₃ , X=20, Y=20, Z=30, −11 R ₁ =H, R ₂ =H, X=30 , Y=30, Z=40 −12 R ₁ =H, R ₂ =CH ₃ , X=30, Y=20, Z=30

[Chemical] (JP-A No. 55-41684) R ₁ : Hydrogen, lower alkyl, phenyl or halogen R ₂ : Hydrogen or lower alkyl n: Integer from 5 to 25 -13 R ₁ = CH ₃ , R ₂ = H, n=2 −14 R ₁ =CH ₃ , R ₂ =H, n=5 −15 R ₁ =CH ₃ , R ₂ =H, n=9 icotanic acid derivative

[C] (Japanese Patent Publication No. 46-34894) R: Alkyl group having 1 to 22 carbon atoms, group having the structure CH ₂ (CF ₂ ) _X H (where x is an even integer from 2 to 10) Structure

[Formula] (where z is an integer from 1 to 40) M: hydrogen or alkali metal m: an integer from z to 4 n: 1 or 2 -1 R=, x=10, M=K, m= 3, n=1 -2 R=, x=5, M=K, m=3, n=1 -3 R=, z=12, M=Na, m=3, n=1

[C] (Special Publication No. 51-44157) R: Hydrocarbon group having 8 to 22 carbon atoms M: Alkali metal or ammonium group -4 R=C ₁₂ H ₂₅ , M=Na, -5 R=C ₁₈ H _{37 ,} M=Na, -6 R= _C12H25 , M= _NH4 ,

[C] (JP-A No. 51-30284) R ₁ : Hydrogen or an alkyl group having 1 to 4 carbon atoms R ₂ : Hydrogen or an alkyl group having 1 to 22 carbon atoms m: An integer of 1≦m≦150 R ₃ : When H, n=1 to 3 When methyl group, n=2 M: Monovalent cation such as an alkali metal or ammonium base -7 R ₁ = H, R ₂ = C ₁₂ H ₂₅ , R ₃ = H, M = Na, m=5, n=3 −8 R ₁ =H R ₂ =C ₁₈ H ₃₇ , R ₃ =H, M=Na, m=3, n=1 −9 R ₁ =H, R ₂ =C ₁₂ H ₂₅ , R ₃ = H, M = NH ₄ , m = 5, n = 3 maleic acid derivative

[C] (Special Publication No. 51-44157) R: Hydrocarbon group having 8 to 22 carbon atoms M: Alkali metal or ammonium group -1 R=C ₁₂ H ₂₅ , M=Na, -2 R=C ₁₈ H ₃₇ , M=K −3 R=C ₁₈ H ₃₇ , M=NH ₄

[C] (JP-A No. 51-30284) R ₁ : Hydrogen or an alkyl group having 1 to 4 carbon atoms R ₂ : Hydrogen or an alkyl group having 1 to 22 carbon atoms m: An integer of 5≦m≦150 R ₃ : When H, n = 1 to 3 When methyl group, n = 2 M = monovalent cation such as an alkali metal or ammonium base -4 R ₁ = H, R ₂ = C ₁₂ H ₂₅ , R ₃ = H, m = 5, n=2, M=Na −5 R ₁ =H, R ₂ =C ₁₈ H ₃₇ , R ₃ =H, m=5, n=2, M=Na −6 R ₁ =H, R ₂ = _C12H25 , _R3 =H, m=5, _n =2, M= _NH4

[Chemical] (Special Publication No. 56-29657) R ₁ : Residue of aliphatic alcohol, aromatic alcohol, or ether alcohol having 6 to 22 carbon atoms R ₂ : When H, n=2,3 When methyl group, n = 2 M: monovalent cation such as hydrogen, alkali metal or ammonium -7 R ₁ = C ₈ H ₁₇ , R ₂ = H, n = 3, M = Na -8 R ₁ = C ₁₂ H ₂₅ , R ₂ =H, n=3 _, M=K-9 _R1 = _C16H33 , _R2 =H, n=3, M= _NH4fumaric acid derivative

[C] (JP-A-51-30285) R ₁ : Residue of aliphatic alcohol, aromatic alcohol, or ether alcohol having 1 to 22 carbon atoms R ₂ : When H, n=1 to 3; When methyl group, n =2 M: Monovalent cation such as alkali metal or ammonium base -1 R ₁ = C ₈ H ₁₇ , R ₂ = H, M = Na, n = 2 -2 R ₁ = C ₁₂ H ₂₅ , R ₂ = H, M=Na, n=2 −3 R ₁ =C ₁₆ H ₃₃ R ₂ =H, M=Na, n=2

[C] (JP-A No. 51-30284) R ₁ : Hydrogen or an alkyl group having 1 to 4 carbon atoms R ₂ : Hydrogen or an alkyl group having 1 to 22 carbon atoms m: An integer of 5≦m≦150 R ₃ : When H, n=1 to 3 When methyl group, n=2 M: Monovalent cation such as an alkali metal or ammonium base -4 R ₁ = H, R ₂ = C ₁₂ H ₂₅ , R ₃ = H, m = 5, n=2, M=Na −5 R ₁ =H, R ₂ =C ₁₈ H ₃₇ , R ₃ =H, m=5, n=2, M=Na −6 R ₁ =H, R ₂ = C ₁₂ H ₂₅ , R ₃ = H, m = 5, n = 2, M = NH ₄ styrene derivative

[Formula] M: 1 such as an alkali metal or ammonium group
valent cation -1 M=NH ₄ -2 M=Na ethylene derivative

[Formula] M: Monovalent cation such as an alkali metal or ammonium group -1 M=NH ₄ Among the above polymerizable emulsifiers, allyl alcohol derivatives are particularly preferred. These polymerizable emulsifiers are used singly or in combination, and the amount used is 1 to 1 to 1 to 100% of the monoethylenically monomer in the synthetic resin emulsion.
The content is 15 wt%, preferably 1 to 10 wt%. If it is less than 1wt%, there is no effect, and if it exceeds 15wt%, the humidity dependence of resistance becomes large and the amount of charge further decreases, causing problems. Note that it is also possible to use a general non-polymerizable emulsifier. Non-polymerizable emulsifiers used in combination include sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium dodecylbenzenesulfonate, sodium dioctyl sulfosuccinate, and polyoxyethylene nonyl phenyl ether. Specific examples of the main monoethylenic monomers used include the following. A Styrenic vinyl monomers Styrene; α- or β-alkyl substituted styrenes such as α-methylstyrene and β-ethylstyrene;
4-methylstyrene, 2-ethylstyrene, 4-
Nuclear alkyl-substituted styrenes such as hexylstyrene; nuclear halogen-substituted styrenes such as chlorostyrene, dichlorostyrene, fluorostyrene, bromostyrene; nuclear alkoxy-substituted styrenes such as methoxystyrene; nuclear acyl-substituted styrenes such as acetylstyrene; Styrene etc. B Acrylic vinyl monomers (meth)acrylic acid; esters of (meth)acrylic acid with alcohols such as alkyl alcohols, halogenated alcohols, alkoxy alcohols, aralkyl alcohols, and alkenyl alcohols (specific examples of the above alcohols include methyl alcohol) , ethyl alcohol, propyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, amyl alcohol, hexyl alcohol, 2-ethyl-hexyl alcohol, heptyl alcohol, octyl alcohol, nonyl alcohol, dodecyl alcohol, tetradecyl alcohol , alkyl alcohols such as hexadecyl alcohol; halogenated alkyl alcohols obtained by partially halogenating these alkyl alcohols; alkoxyalkyl alcohols such as methoxyethyl alcohol, ethoxyethyl alcohol, ethoxyethoxyethyl alcohol, methoxypropyl alcohol, and ethoxypropyl alcohol ;benzyl alcohol,
Examples include aralkyl alcohols such as phenylethyl alcohol and phenylpropyl alcohol; alkenyl alcohols such as allyl alcohol and crotonyl alcohol. ) C cyanide vinyl monomer acrylonitrile; methacrylonitrile, α-
α-alkylacrylonitrile such as ethyl acrylonitrile; α-chloroacrylonitrile;
α-halogenated acrylonitriles such as α-bromoacrylonitrile; vinylidene cyanide and the like. These monoethylenic monomers are used singly or in combination, and more preferably methyl methacrylate-acrylonitrile, styrene-acrylonitrile, methyl methacrylate-acrylonitrile,
Good combination of styrene. In addition to the main monoethylenic monomer, other vinyl monomers, oligomers, etc. are used as necessary for purposes such as adjusting the glass transition point Tg and improving adhesion to magnetic particles. The amount used is preferably 50wt% or less. Such vinyl monomers include fatty acid vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, butylene, and butadiene; vinyl chloride, vinyl bromide, vinyl fluoride, vinylidene chloride, and bromide. Examples include halogenated olefins such as vinylidene and vinylidene fluoride; amides such as acrylamide and methacrylamide. Furthermore, for the purpose of adjusting the charge amount of the magnetic particles, a charge control agent such as an azine compound, a quaternary ammonium salt, or a polyamine resin may be used as necessary. The amount used is preferably 15wt% or less. The synthetic resin emulsion used to coat the magnetic particles is produced by emulsion polymerization. As the emulsion polymerization method, a batch polymerization method, a drop polymerization method (monomer or emulsion monomer), a seed polymerization method, and a multistage polymerization method that is an advanced type of these methods are employed depending on the purpose. The synthetic resin emulsion thus produced has a synthetic resin content of 5 to 60 wt%. The particle size of synthetic resin emulsion is 0.01 to 10μm,
Preferably it is about 0.02 to 1 μm. The solvent is water, an alcohol type such as methyl alcohol, ethyl alcohol, isopropyl alcohol, or a mixture thereof. The glass transition point Tg of the synthetic resin in such a synthetic resin emulsion is below 130°C, especially between 20 and 130°C.
It is preferable that it is ℃. When Tg exceeds 130°C, it becomes industrially costly to uniformly coat magnetic particles with synthetic resin emulsion, and it is difficult for the formed film to be uniform. When the Tg is less than 20°C, the fluidity of the magnetic carrier particles becomes very poor, and the humidity dependence of the electrical resistance increases. The coating made of such a synthetic resin is
Formed as a continuous film with a thickness of 10 μm. In order to form such a coating on the surface of the magnetic particles, an emulsion solution may be coated with a nozzle spray under heating in a container provided with a fluidized bed or a rolling layer, and then dried. The heating temperature is about 70 to 90°C, and the drying temperature is about 70 to 100°C. Furthermore, by adding a film-forming agent, a more uniform continuous film can be formed. In this case, the film forming aids used include diethylene glycol monobutyl ether acetate, butyl carbitol acetate, cellosolve, cellosolve acetate, butyl cellosolve, butyl cellosolve acetate,
Phenyl cellosolve, carbitol, carbitol acetate, butyl carbitol, diethyl carbitol, dibutyl carbitol, hexylene glycol, texanol, sierzol, 3-
Examples include monohydric or polyhydric alcohols such as methoxybutyl acetate, ethylene glycol acetate, benzyl alcohol, and furfuryl alcohol, and derivatives thereof; and aromatic hydrocarbons such as toluene and xylene. The amount of the film forming aid used is preferably 1 to 20 wt%. By using a film-forming agent, the resin component swells in the emulsion, making it possible to coat with a synthetic resin having a high glass transition point. On the other hand, the material of the magnetic particles used in the present invention is not particularly limited, but is usually iron powder or oxide powder having a spinel structure or hexagonal structure. The oxide having a spinel structure may be soft ferrite such as so-called 2-3 spinel or 1-3 spinel, magnetite (Fe ₃ O ₄ ), or maghemite (γ-Fe ₂ O ₃ ). In addition, soft ferrites include Ni, Mn,
It may be any material containing one or more of Mg, Zn, Cu, Co, etc. The oxide having a hexagonal crystal structure may be Ba ferrite, Sr ferrite, Ba or Sr ferrite in which part of Ba or Fe is replaced with another metal, or the like. These magnetic powders are produced as particles having an average particle diameter of 10 to 200 μm by a known method. Note that there are no particular restrictions on the particle size distribution. Such magnetic carrier particles of the present invention have a particle size of 15 to
It has a charge amount of 40μC/g. Moreover, the flow rate per 50 g shows a value of 28 to 34 seconds. In this case, the flow rate is the falling speed of 50 g of carrier, which was determined using a powder rheometer after weighing 50 g of carrier. Furthermore, the electrical resistance exhibits a value of approximately 10 ¹² to 10 ⁵ Ω in the range of 100 to 500V. In this case, the measurement of the electrical resistance of the carrier particles is
The method is modeled after the magnetic brush development method and is carried out as follows. That is, with a magnetic pole gap of 7 mm, the N pole and S
Opposite poles. In this case, the surface magnetic flux density of the magnetic pole is 1500 Gauss, and the opposing magnetic pole area is 10 x 30 mm.
A non-magnetic parallel plate electrode was placed between the magnetic poles with an inter-electrode gap of 5 mm, and 200 mg of the sample was placed between the electrodes.
Holds by magnetic force. Then, the resistance may be measured using an insulation resistance meter or an ammeter. The saturation magnetization of carrier particles is 40~
It should be about 80emu/g. Specific Effects of the Invention The magnetic carrier particles of the present invention are used in electrophotographic development in combination with toner. There are no restrictions on the type of toner used. Note that there are no restrictions on the magnetic brush development method used, the type of photoreceptor, etc. in obtaining an electrostatically copied image. Specific Effects of the Invention The present invention provides the following effects. By using a polymerizable emulsifier and adjusting its type and amount added, the amount of charge on magnetic carrier particles can be controlled, and the control range is
It is large at 15-35μC/g. In this way, by being able to control the amount of charge on the magnetic carrier particles themselves, the amount of charge is stabilized. Furthermore, it is almost unnecessary to add an expensive charge control agent to the toner, and it is possible to reduce the cost of the developer. The flow rate shows a good value of 34 seconds or less per 50g. Electrical resistance does not depend on the amount of charge and is 10 ⁵
~10 ¹² Ω can be controlled. Furthermore, the humidity dependence of electrical resistance is small, and high humidity (85%RH) is better than low humidity (30%RH).
The electrical resistance below is 1/10 ² to 5/10 ³ for magnetic carrier particles without resin coating, and 1/10 2 to 5/10 ³ for magnetic carrier particles using a non-polymerizable emulsifier.
Compared to this, magnetic carrier particles using a polymerizable emulsifier have a decrease of ^1/103 .
The decline has remained at 10 to ^5/102 . Therefore, it can be used as an optimal resistance for various types of copying machines, and furthermore, it can resist changes in the external environment.
Stable and good image quality can be obtained. By using a polymerizable emulsifier, the durability of the coating layer is also sufficient. Since it uses a water-based emulsion, it is less polluting and less expensive than conventional solvent-based resins. Specific Examples of the Invention Specific examples of the present invention will be shown below to explain the present invention in further detail. Example 1 Ferrite particles with a particle size of approximately 60 μm as magnetic particles (composition: NiO 20 mol%, ZnO 28 mol%, Fe ₂
O ₃ 52 mol%, σ _n = 50 emu/g, Hc = 2.0 Oe)
was used. The ferrite particles were placed in a container in which a fluidized bed was formed and preheated to 80° C. for about 15 minutes. Thereafter, synthetic resin emulsions A1 to A8 shown in Table 1 below were sprayed using a two-fluid nozzle and dried. The drying humidity was 60 to 100°C. Note that butyl carbitol acetate was used as a film forming aid. The amount used is 5wt%. A uniform continuous film of 3 to 5 μm was formed on the ferrite surface.

[Table] For each of these carrier particles, commercially available toner and carrier particles were mixed at a ratio of 5:100 (weight ratio), triboelectrically charged, and the amount of charge was measured using a blow-off charge measuring device manufactured by Toshiba Chemical Corporation. did. The results are shown in Figure 1. In the figure, the curve and
These correspond to samples A1 to A4 and A5 to A8, respectively. Furthermore, the results of measuring the electrical resistance of each carrier particle at 30°C and 50% are shown in Figure 2. In the figure, curves and are samples A1 to A4 and A5 to A8, respectively.
This corresponds to Further, 50 g of each carrier particle was weighed, and the falling speed of 50 g of the carrier particle was measured using a powder rheometer manufactured by Tsutsui Rikagaku Kiki Co., Ltd. to determine the fluidity. The results are shown in Table 2. Table 2 also shows the ratio (%) of the electrical resistance at 30° C. and 85% to the electrical resistance at 30° C. and 30%.

[Table] From these results, according to the present invention, by adjusting the amount of polymerizable emulsifier added, it is possible to control the amount of charge while maintaining the electrical resistance and fluidity of the carrier particles at favorable values. Recognize. It is also found that the moisture resistance is also extremely good. Example 2 Using the same magnetic particles as in Example 1,
Similarly, the resin coating shown in Table 3 was applied. Note that butyl carbitol acetate was used as a film forming aid. The amount used is 5wt%. Figure 3 shows the amount of charge on each of these carrier particles.
Figure 4 shows the electrical resistance at ℃ and 50%RH. In addition, low humidity (30%RH) of each carrier particle
Table 4 shows the ratio of the electrical resistance under high humidity (80% RH) to the electrical resistance below and the charge amount control range when changing the amount of emulsifier added.

【table】

【table】

[Table] From these results, according to the present invention, by changing the type of polymerizable emulsifier, it is possible to control the amount of charge while maintaining the characteristics such as electrical resistance of the carrier particles in a good state, and further, It can be seen that the carrier particles have stable electrical resistance with little humidity dependence. Example 3 The coatings shown in Table 5 were formed in the same manner as in Example 2, and the properties were measured. The results are shown in Table 6.

【table】

[Table] From the results shown in Table 6, the effects of the present invention are clear.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the amount of polymerizable emulsifier added and the amount of charge. FIG. 2 is a graph showing the relationship between the amount of polymerizable emulsifier added and electrical resistance. FIG. 3 is a graph showing the relationship between the type of emulsifier and the amount of charge. FIG. 4 is a graph showing the relationship between the type of emulsifier and electrical resistance.

Claims (1)

[Scope of Claims] 1. Magnetic carrier particles for electrophotographic development, characterized in that the surface of the magnetic particles is coated with a synthetic resin obtained by emulsion polymerization of a monoethylenic monomer using a polymerizable emulsifier. . 2. Claim 1, wherein the polymerizable emulsifier is one or more of allyl alcohol derivatives, acrylic acid derivatives, itaconic acid derivatives, maleic acid derivatives, fumaric acid derivatives, ethylene derivatives, and styrene derivatives. magnetic carrier particles for electrophotographic development. 3. The electrophotography according to claim 1 or 2, wherein the monoethylenic monomer contains one or more of a styrene vinyl monomer, an acrylic vinyl monomer, and a cyan vinyl monomer. Magnetic carrier particles for development. 4. Magnetic carrier particles for electrophotographic development according to any one of claims 1 to 3, wherein the polymerizable emulsifier is contained in an amount of 1 to 15 wt% based on the monoethylenically monomer. 5. Magnetic carrier particles for electrophotographic development according to any one of claims 1 to 4, wherein the synthetic resin coating is formed using a synthetic resin emulsion. 6. Magnetic carrier particles for electrophotographic development according to claim 5, wherein the synthetic resin content is 5 to 60 wt%. 7. Magnetic carrier particles for electrophotographic development according to any one of claims 1 to 6, wherein the synthetic resin has a glass transition point of 130°C or lower. 8. Magnetic carrier particles for electrophotographic development according to any one of claims 1 to 7, wherein the coating has a thickness of 2 to 10 μm. 9. Magnetic carrier particles for electrophotographic development according to any one of claims 1 to 8, wherein the magnetic particles are made of iron or an oxide with a spinel structure or a hexagonal structure. 10 Coating agent added to synthetic resin emulsion
Magnetic carrier particles for electrophotographic development according to any one of claims 5 to 9, in which 20 wt% is added. 11. Magnetic carrier particles for electrophotographic development according to claim 10, wherein the film-forming auxiliary agent is one or more of alcohols, derivatives thereof, and aromatic hydrocarbons.