JPH0723967B2 - Magnetic toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a toner used in a method for developing a latent image. The toner for such a purpose is for forming and recording an image. For example, in electrophotography, the toner is disclosed in U.S. Pat. No. 2,297,691 and JP-B-4.
A number of methods are known as described in JP-A-2-23910 and JP-B-43-24748, and generally, a photoconductive substance is used and various methods are used to form an electrical signal on the photoreceptor. After forming a latent image, developing the latent image with toner, and transferring the toner image to a transfer member such as paper, if necessary,
Fix with heat, pressure, hot-press roller or solvent vapor,
A copy is to be obtained. Various methods have been conventionally proposed as a method of developing using a toner, for example, a magnetic brush method described in U.S. Pat.No. 2,874,063, a cascade developing method described in U.S. Pat.No. 2,618,552. In addition to the powder cloud method described in US Pat. No. 2,221,776, a fur brush developing method, a liquid developing method and the like are known. Among these developing methods, a magnetic brush method, a cascade method, a liquid developing method, and the like, which use a developer mainly composed of a toner and a carrier, have been widely put into practical use. All of these methods are excellent methods in which a good image can be obtained relatively stably, but on the other hand, they have common problems associated with two-component developers, such as deterioration of the carrier and fluctuations in the mixing ratio of the toner and the carrier. There is. In order to avoid such a problem, various developing methods using a one-component developer consisting of only toner have been proposed, but among them, many are excellent in the method of using a developer consisting of magnetic toner particles. For example, the so-called induced development method described in JP-B-37-491 is well known.

In this method, a toner having a dielectric property and magnetism is attached to a sleeve in which a magnet is attached to form a magnetic brush of toner, and the magnetic brush is brought into contact with an electrostatic latent image carrier to develop the latent image with the toner. To do. In this developing method, when the magnetic brush is opposed to the electrostatic latent image due to the toner having conductivity, an electric charge having a polarity opposite to that of the electrostatic latent image is induced in the toner, and thus the electric charge is induced in the toner. The latent image is developed based on the electric attraction between the electrostatic latent images. Further, an insulating magnetic toner is attached to a sleeve containing a magnet to form a magnetic brush of the toner, the toner is charged by friction with the sleeve, and the magnetic brush is brought into contact with or close to the electrostatic latent image carrier. There is also known a method of developing a latent image with toner. For example, the developing method is described in detail in JP-A-49-17739 using an encapsulated magnetic toner and JP-A-50-45639 using an insulating magnetic toner.

In the developing method using these one-component type developers, since the developer does not contain a carrier, it is not necessary to adjust the mixing ratio of the carrier and the toner, and the stirring operation for sufficiently uniformly mixing the carrier and the toner is required. Since there is no particular need, there is an advantage that the entire developing device can be configured simply and compactly. Further, there is no inconvenience such as deterioration of the developing chamber due to deterioration of the carrier with time.

In these magnetic toners, a large amount of magnetic fine particles are generally dispersed in the binder resin, but the dispersibility of the magnetic fine particles in the binder resin is poor and it is difficult to obtain a uniform dispersion. Further, even if the particles are dispersed to a certain extent through a sufficient kneading step, in the subsequent pulverizing step, breakage occurs at the interface between the magnetic fine particles and the binder resin, resulting in the presence of the magnetic particles on the toner surface, resulting in an electrical resistance Deterioration and moisture resistance tend to occur. Further, there is a difference in the content of the magnetic particles among the toner particles, so that the hiding power becomes non-uniform.

On the other hand, in order to overcome the problems of the toner by the pulverization method, a method for producing the toner by the suspension polymerization method has been proposed. In the suspension polymerization method, a polymerizable monomer, a magnetic substance,
Polymerization initiator Further, if necessary, a monomer system in which a crosslinking agent, a charge control agent, a colorant and other additives are uniformly dissolved or dispersed is dispersed in an aqueous phase containing a dispersion stabilizer by using an appropriate stirrer. At the same time, a polymerization reaction is carried out to obtain toner particles having a desired particle size. Since the suspension polymerization method does not include a mechanical crushing step, it does not cause the inconvenience caused by the crushing as seen in the crushing method, but since the monomer system containing magnetic particles is dispersed in the aqueous phase, this dispersion -In the polymerization step, generally hydrophilic magnetic fine particles are unevenly distributed on the surface of the toner particles, which causes the same problem as the pulverization method. In order to improve the dispersibility of the magnetic fine particles in the polymerizable monomer and the binder resin, treatment of various magnetic particles has been proposed. For example, a magnetic powder is treated with an aliphatic compound (see Japanese Patent Laid-Open No. 50-139745, etc.), a treatment with a silane coupling agent (see Japanese Laid-Open Patent Publication No. 54-127329, etc.), and a titanium coupling agent (Japanese Laid-Open Patent Publication No. Sho. 55-26519, etc.) has been proposed. However, even these treatments are not enough to uniformly disperse the magnetic particles in the polymerizable monomer or the binder resin, and there are also insufficient points in the bond strength between the magnetic particles and the binder resin. Furthermore, the silane coupling agent and the titanium coupling agent may generate impurities due to hydrolysis, which may adversely affect the characteristics of the toner.

An object of the present invention is to provide a magnetic toner that solves the above problems.

An object of the present invention is to provide a magnetic toner having a high image density and capable of obtaining a clear image.

A further object of the present invention is to provide a magnetic toner having good fixing properties and excellent developability.

Further, an object of the present invention is to provide a spherical magnetic toner in which the particle size can be easily controlled, the particle size is uniform, and almost no classification is required.

A further object of the present invention is to provide a magnetic toner that has good fluidity and does not cause aggregation.

Specifically, the present invention relates to a suspension polymerization magnetic toner,
The following formula having at least two vinyl groups and one or more hydroxyl groups [In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ₂ represents a linear or branched alkylene group which may have a hydroxyl group having 1 to 12 carbon atoms, R ₃ is a group having at least one phenylene group, Or a —R ₄ —O— group (in the formula, R ₄ represents an alkylene group which may have a hydroxyl group), m represents an integer of 0 to 6,
n represents 0 or 1, but m and n are not 0 at the same time.] and a polymer of a polymerizable monomer suspension polymerized in the presence of magnetic particles. And a magnetic toner.

In the present invention, by using the vinyl compound as a cross-linking agent, in the suspension particles immediately after the initiation of polymerization, a polar group such as a hydroxyl group, an ester group or an ether group contained in the vinyl compound as a cross-linking agent and a magnetic property It is considered that affinity such as hydrogen bond and electric attraction force is generated between particles, and as a result, the dispersibility of magnetic particles in suspended particles is improved. That is, the obtained toner particles are uniformly dispersed without magnetic particles being aggregated or localized.

In the present invention, the viscosity at the beginning of the polymerization is the same as that of the conventional one and there is usually no difference in the granulation property at the time of suspension, but as the polymerization proceeds, the thickening effect becomes large, and The retention property is improved and the stability of the toner particles is increased, the reaction time is shortened, and a toner having a sharp particle size distribution is obtained.

For example, a vinyl compound represented by the following formula can be exemplified.

[In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ₂ represents a linear or branched alkylene group which may have a hydroxyl group having 1 to 12 carbon atoms, R ₃ is small, Group or —R ₄ —O— (R ₄ represents an alkylene group which may have a hydroxyl group) represents a group having one phenylene group, m represents an integer of 0 to 6, and n represents 0. Or indicates 1,
However, m and n are not 0 at the same time.] More specifically,
The following can be listed as typical examples.

When the amount of the vinyl compound having a function of a cross-linking agent is too large, the melting temperature of the toner rises, it does not dissolve sufficiently at a normal fixing temperature, the fixing property is lowered, and when the amount is small, The dispersibility of the magnetic particles is poor, and the blocking resistance and durability are also inferior. Therefore, the amount of the compound having a function of a crosslinking agent is based on the total amount of the polymerizable monomer (monomer). 0.01-10% by weight, more preferably 0.
It is recommended to use it at 05-5% by weight.

The polymerizable monomer applicable to the present invention includes styrene, o
-Methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p
-Ethylstyrene, 2,4-dimethylstyrene, pn-
Butyl styrene, p-tert-butyl styrene, pn-
Hexyl styrene, pn-octyl styrene, pn
-Nonylstyrene, pn-decylstyrene, pn-
Styrene and its derivatives such as dodecylstyrene; Ethylenically unsaturated monoolefins such as ethylene, propylene, butylene, isobutylene: Vinyl chloride, vinylidene chloride, vinyl halides such as vinyl bromide, vinyl fluoride: Vinyl acetate, propion Vinyl esters such as vinyl acrylate and vinyl benzoate; methyl methacrylate,
Ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl methacrylate, methacrylic acid. Α-Methylene aliphatic monocarboxylic acid esters such as diethylaminoethyl acid ester; methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-acrylate
Acrylic esters such as octyl, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate, phenyl acrylate: vinyl methyl ether, vinyl ethyl ether,
Vinyl ethers such as vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; N-vinyl compounds such as N-vinyl pyrrole, N-vinyl carbazole, N-vinyl indole and N-vinyl pyrrolidone Vinyl naphthalenes; Vinyl monomers such as acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide.

Further, a polymer may be added as an additive during the polymerization, and the monomer may be polymerized in the presence of the polymer.

In the present invention, a polymerizable monomer system to which a polar polymer or a cyclized rubber is added at the time of polymerization is suspended and polymerized in an aqueous phase in which a dispersant having an opposite charge to the polar polymer is dispersed. It is preferable. That is, the cationic or anionic polymer contained in the polymerizable monomer system is the oppositely charged anionic or cationic dispersant dispersed in the aqueous phase and the particle surface to be a toner in the course of polymerization. It attracts electrostatically and prevents the particles from coalescing by covering the surface of the particles with a dispersant, which stabilizes the particles and the polar polymer added at the time of polymerization gathers on the surface layer of the particles that become toner. The resulting particles become pseudo capsules. Uses a relatively high molecular weight polar polymer, copolymer, or cyclized rubber to give toner particles excellent blocking properties, developability, and abrasion resistance, while internally fixing properties are relatively low molecular weight. By performing the polymerization so as to contribute to the improvement, it is possible to obtain a toner satisfying the contradictory requirements of the fixing property and the blocking property. The polar polymers (including copolymers) and the reversely chargeable dispersants that can be used in the present invention are exemplified below.

(I) Examples of the cationic polymer include polymers of nitrogen-containing monomers such as dimethylaminoethyl methacrylate and diethylaminoethyl acrylate, and copolymers of styrene and unsaturated carboxylic acid esters with the nitrogen-containing monomers. .

(Ii) Anionic polymers include nitrile monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid, unsaturated dibasic acids, and unsaturated dibasic acids. There are polymers of anhydrides and nitro monomers.

(Iii) As the anionic dispersant, a water-soluble polymer such as partially saponified vinyl acetate polymer or Aerosil # 20
There are colloidal silica such as 0, # 300 (manufactured by Nippon Aerosil Co., Ltd.).

(Iv) Examples of the cationic dispersant include fine particles of hydrophilic positively charged silica such as aluminum oxide, magnesium hydroxide and aminoalkyl-modified colloidal silica.

As the magnetic particles that can be used in the present invention, substances that are magnetized by being placed in a magnetic field are used. For example, powders of ferromagnetic metals such as iron, cobalt and nickel, or alloys and compounds such as magnetite, hematite and ferrite. Powder. Particle size is 0.05-5μ, preferably 0.1-1
Magnetic microparticles with μ are used. The content of the magnetic particles is 10 to 60% by weight, preferably 25 to 60% by weight based on the weight of the toner.
50% by weight is good. Further, these magnetic fine particles may be treated with a treating agent such as the above-mentioned silane coupling agent, titanium coupling agent or the like, or an appropriate reactive resin or the like.
In this case, depending on the surface area of the magnetic fine particles and the density of hydroxyl groups existing on the surface, sufficient dispersibility can be obtained with a treatment amount of 5% or less, and the physical properties of the toner are not adversely affected. If necessary, a charge control agent, a colorant, and a fluidity modifier may be added to the toner. The charge control agent and the fluidity modifier may be used as a mixture (external addition) with toner particles. As the charge control agent, there are metal-containing dyes, nigrosine and the like, as the colorant, conventionally known dyes and pigments can be used, and as the fluidity modifier, there are colloidal silica and fatty acid metal salts. Further, for the purpose of increasing the amount, a filler such as calcium carbonate or fine powder silica may be blended in the toner in the range of 0.5 to 20% by weight. Further, in order to prevent aggregation of the toner particles and improve fluidity, a fluidity improver such as Teflon fine powder may be added. Further, for the purpose of improving the releasability at the time of fixing with a hot roll, waxes generally used as a releasing agent such as a hydrocarbon compound and carnauba wax may be added to the toner. For example, in the case of a hydrocarbon compound, since it is hydrophobic and has a low molecular weight, it is generally difficult to mix with a polymer formed by crosslinking with a polar cross-linking agent after polymerization, so it is less likely to appear on the surface compared to an added polar polymer. It will be pushed into the toner. Then, during fixing, it is exposed from the inside to remarkably improve the fixing property and the offset property. At that time, the hydrocarbon compound is considered to act as a plasticizer, a lubricant, and an oil-like function.

Hydrocarbon compounds used in the present invention include paraffins having a carbon number of ₆ or more, polyolefins, and the like, for example, paraffin wax (manufactured by Nippon Oil Co., Ltd.), paraffin wax (manufactured by Nippon Seiro Co., Ltd.), microwax (Nippon Oil Co., Ltd.). Made), Micro Listerine Wax (made by Nippon Seiro Co., Ltd.), PE-130
(Manufactured by Hoechst), Mitsui Hiwax 110P (manufactured by Mitsui Petrochemical), Mitsui Highwax 220P (manufactured by Mitsui Petrochemical), Mitsui Highwax 660P (manufactured by Mitsui Petrochemical), and the like. Particularly preferred are low-molecular-weight polyethylene, low-molecular-weight polypropylene, and paraffin. Is.

As the polymerization initiator, any suitable polymerization initiator, for example, azobisisobutyronitrile (AIBN), benzoyl peroxide, methyl ethyl ketone peroxide, isopropyl peroxycarbonate, quinene hydroperoxide, 2,4-dichlorylbenzoyl The polymerizable monomer (monomer) can be polymerized by using peroxide, lauroyl peroxide or the like. Generally, about 0.5-5% by weight of monomer of initiator is sufficient.

The suspension method is a method in which a polymerization initiator, a colorant, a monomer, an additive, and the like are uniformly dissolved or dispersed in a water phase (that is, a continuous phase) containing a suspension stabilizer. Disperse with an ordinary stirrer, homomixer, homogenizer or the like. Preferably, the stirring speed and time are adjusted so that the monomer droplets have the desired toner particle size, generally 30 μm or less, and then the stirring is performed so that the dispersion stabilizer acts to maintain almost that state. May be performed to such an extent that sedimentation of particles is prevented. Polymerization temperature is 50 ℃ or more, generally 70
Polymerization is carried out at a temperature of ~ 90 ° C. After completion of the reaction, the produced toner particles are collected and dried by an appropriate method such as washing, filtration, decantation and centrifugation.

In the suspension polymerization method, usually 300 to 3000 parts by weight of water is used as a dispersion medium with respect to 100 parts by weight of the polymerizable monomer.

Suitable dispersion media used in the present invention include, for example, any suitable stabilizer such as polyvinyl alcohol, gelatin, metal cellulose, methyl hydropropyl cellulose, ethyl cellulose, sodium salt of carboxymethyl cellulose, polyacrylic acid and Their salts, starch, gum alginate, zein, casein,
It is possible to use those in which the aqueous phase contains tricalcium phosphate, talc, barium sulfate, bentonite, aluminum hydroxide, ferric hydroxide, titanium hydroxide, thorium hydroxide and the like. This stabilizer is used in a stabilizing amount in the continuous phase, preferably in the range of about 0.1 to 10% by weight. It is also possible to use a surfactant within the range of 0.001 to 0.1% by weight for finely dispersing the inorganic dispersant. This is for promoting the intended action of the above dispersion stabilizer, and specific examples thereof include sodium dodecylbenzenesulfonate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, and allyl-alkyl-poly. Sodium ether sulfonate, sodium oleate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, 3,3-disulfone diphenylurea-4,4-diazo-bis- Amino-8-naphthol-6-sulfonate sodium sodium, ortho-carboxybenzene-azo-dimethylaniline, 2,
2,5,5-tetramethyl-triphenylmethane-4,4-diazo-bis-β-naphthol-sodium disulfonate,
Others can be mentioned.

Further, a water-soluble monomer simultaneously undergoes emulsion polymerization in water and contaminates the resulting suspension polymer with small emulsion-polymerized particles.Therefore, a water-soluble polymerization inhibitor, such as a metal salt, is added to the suspension to form an aqueous phase. It is also good to prevent emulsion polymerization. In addition, glycerin, glycol or the like may be added to water in order to increase the viscosity of the medium and prevent the particles from coalescing. It is also possible to use salts such as NaCl, KCl and Na ₂ SO ₄ in order to reduce the solubility of the easily soluble monomer in water.

Hereinafter, the present invention will be described in detail based on examples.

Example 1 The above formulation was heated to 70 ° C. in a container, dissolved, and dispersed. Mix in a container equipped with a TK homomixer (manufactured by Tokushu Kika Kogyo) having a high shearing force for about 5 minutes while maintaining at 70 ° C, and further add 6 g of azobisisobutyronitrile to dissolve. Then, a monomer system was prepared.

Separately, 2 flasks containing an aqueous dispersion liquid in which 4 g of Aerosil 200 (manufactured by Nippon Aerosil) were dispersed were heated to 70 ° C., the above monomer system was charged, and the mixture was stirred at 7,000 rpm for 20 minutes. The mixture was further stirred at a low rotation speed to complete the polymerization. After removing the dispersant, filtration, washing with water and drying were carried out to obtain a toner. The obtained toner had an average particle size of 11 μ and had a sharp particle size distribution. Further, it was confirmed from the cross-sectional photograph that the individual magnetic particles were uniformly distributed inside. The appearance was a black toner. When the particle size of the toner obtained by a Coulter counter was measured, the particles having a particle size of 25.4 μ or more were 5% or less.

To 100 g of this toner, 0.4 g of Nipsyl ER (manufactured by Nippon Silica) was added to prepare a developer. Commercially available copying machine PC-20 (made by Canon)
When an image was printed using, a good image was obtained, and the offset property and the fixing property were also good. Also, in the durability test of 3,000 sheets, deterioration of image quality and density was not observed.

Comparative Example 1 Polymerization was performed in the same manner as in Example 1 except that the same amount of divinylbenzene was used instead of the compound example (3) in Example 1 to obtain a toner having an average particle size of 11 μm. When the particle size distribution of the obtained toner was measured by a Coulter counter, it was found that 10% or more of particles having a particle size of 25.4 μ or more were present. In addition, a group of magnetic substances that are aggregated inside the obtained toner particles was found, and it was found that the magnetic substances were locally unevenly distributed. Since the particle size distribution was broader than that of the toner of Example 1, classification was performed using an air classifier.
The toner has an equivalent distribution. Incidentally, some of the pre-classified toner particles contained no magnetic substance. When this toner was used to perform image formation in the same manner as in Example 1, deterioration in image quality and density was observed on the 1700th sheet in the durability test.

Example 2 The above-mentioned formulation was subjected to a polymerization reaction in a container in the same manner as in Example 1 to obtain a formal blue magnetic color toner having an average particle diameter of 12 μm. The obtained toner had good dispersibility of the magnetic particles contained therein and had a sharp particle size distribution.
When an image was formed in the same manner as in Example 1, it was a good image, and the offset property and the fixing property were also good. Also 3,
Even in the 000-sheet durability test, no deterioration in image quality or density was observed.

Comparative Example 2 Polymerization was performed in the same manner as in Example 2 except that divinylbenzene was used instead of the compound example (1) in Example 2 to obtain a toner having an average particle size of 13 μ. In the obtained toner particles, there were aggregates of magnetic particles, it was observed that they were not uniformly dispersed, and the distribution was broad, so classification was performed,
A toner having the same distribution as in Example 2 was used. When an image was formed using this toner in the same manner as in Example 1,
The durability test showed that the image quality and density were deteriorated around the 2200th sheet.

Example 3 The above formulation was heated to 70 ° C. in a container to dissolve / disperse it. This is mixed for about 5 minutes while maintaining at 70 ° C in a container equipped with a mixer having high shearing force such as TK homomixer (made by Tokushu Kika Kogyo), and 6 g of azobisisobutyronitrile is further added. Added and dissolved.

On the other hand, silica that has been previously treated with aminoalkylsilane in water
2 flasks with 10g dispersed were heated to 70 ° C,
The above monomer system was charged and stirred at 7,000 rpm for 20 minutes. The mixture was further stirred at a low rotation speed to complete the polymerization. After removing the dispersant, filtration, washing with water and drying were carried out to obtain a toner. This toner had an average particle size of 10 μm and had a sharp particle size distribution. The magnetic particles in the toner particles were uniformly distributed, and the appearance was black.

To 100 g of this toner was added 0.4 g of TARANOX 500 (Tarco Co.) to obtain a developer. When a commercially available copying machine NP-270RE (manufactured by Canon Inc.) was used for image formation, a good image was obtained, and it was also manufactured by offset and had good fixability. Also 3,00
No deterioration in image quality or density was observed in the 0-sheet durability test.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 3 except that the same amount of divinylbenzene was used instead of the compound example (4) in Example 3 to obtain a toner having an average particle diameter of 11 μm. Aggregates of magnetic particles were observed in the obtained toner particles, and the particle size distribution was broad. Image formation was performed by classifying the particles to have the same particle size distribution as that of the toner of Example 3, and it was found that the image had a low density, and the image quality and the density were deteriorated at about 2,000th sheet in the durability test.

Example 4 The above formulation was heated to 70 ° C. in a container to dissolve / disperse it.
This is mixed for about 5 minutes while maintaining at 70 ° C in a container equipped with a mixer having high shearing force such as TK homomixer (made by Tokushu Kika Kogyo), and 6 g of azobisisobutyronitrile is further added. Added and dissolved.

On the other hand, silica that has been previously treated with aminoalkylsilane in water
2 flasks with 10g dispersed were heated to 70 ° C,
The above monomer system was charged and stirred at 7,000 rpm for 20 minutes. The mixture was further stirred at a low rotation speed to complete the polymerization. After removing the dispersant, filtration, washing with water and drying were carried out to obtain a toner. This toner had an average particle size of 10 μm and had a sharp particle size distribution. The magnetic particles in the toner particles were uniformly distributed, and the appearance was black.

To 100 g of this toner was added 0.4 g of TARANOX 500 (Tarco Co.) to obtain a developer. When images were printed using a commercially available copying machine NP-270RE (manufactured by Canon Inc.), the images were good, and the offset property and fixing property were also good. Also 3,000
No deterioration in image quality or density was observed in the durability test of the sheets.

Claims (2)

[Claims] 1. A suspension polymerization magnetic toner having the following formula having at least two vinyl groups and one or more hydroxyl groups: [In the formula, R ₁ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, R ₂ represents a linear or branched alkylene group which may have a hydroxyl group having 1 to 12 carbon atoms, R ₃ is a group having at least one phenylene group, Or a —R ₄ —O— group (in the formula, R ₄ represents an alkylene group which may have a hydroxyl group), m represents an integer of 0 to 6,
n represents 0 or 1, but m and n are not 0 at the same time.] and a polymer of a polymerizable monomer suspension polymerized in the presence of magnetic particles. And magnetic toner. 2. The magnetic toner according to claim 1, wherein the polymer is crosslinked with the vinyl compound.