JPS6125156A - Magnetic toner - Google Patents

Abstract

PURPOSE:To obtain excellent fixability with good spheroidal characteristic by dispersing porous polymer particles into an aq. medium contg. a metallic salt consisting essentially of an iron salt, settling a metal in the form of hydroxide in the polymer particles and forming further a polymer thereof with said particles as seed particles if necessary. CONSTITUTION:The magnetic polymer particles contg. the metallic oxide obtd. by dispersing the porous polymer particles into the aq. medium contg. the metallic salt consisting essentially of the iron salt, settling the metal in the form of the hydroxide and/or oxide in the polymer particles and heating the same if necessary are used as the seed particles and further 1 or >=2 kinds of polymerizable monomers which yield a polymer having 30-80 deg.C glass transition temp. are added thereto at 0.2-4 times by weight of the seeds and are polymerized in the aq. medium. The magnetic toner obtd. in such a manner is thoroughly spherical and is monodisperse system and therefore the said toner does not require classification and spheroidization. The toner has a good long-run characteristic in copying and permits easy maintenance. The resolution in copying is thus improved. Since the toner is encapsulated by the polymer having the low transition temp., the fixability is good.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic toner comprising spherical magnetic particles containing magnetic particles uniformly dispersed therein.

TECHNICAL BACKGROUND The dry type developer mainly used in the past is a so-called two-component toner composed of a coloring agent called a toner and a carrier made of iron powder, glass spheres, etc. In a developing method using such a developer, the toner is charged by friction between the toner and the carrier, and an image is formed on the recording medium by applying electrostatic attraction between the toner and the charges on the drum or recording medium. Form.

A problem with such a developing method is that when the developer is used after being turned over for a long period of time, toner adheres to the periphery of the carrier, resulting in a decrease in image quality. In addition, the carrier needs to be replaced periodically due to deterioration. Furthermore, there are disadvantages such as the large size of the device and high cost.

PRIOR ART Recently, one-component magnetic toners containing magnetic powder in the toner have been developed as a way to overcome these disadvantages. This magnetic toner is composed of magnetite, magnetic powder, adhesive resin, colorant, and other additives, and does not require the use of a carrier, so problems such as carrier contamination and deterioration do not occur. Therefore, there is no need to replace the carrier, the developing machine is simple, and it has many advantages such as being advantageous in terms of cost.

However, magnetic toner has some problems in manufacturing. A typical method that has been proposed or used in the past as a method for manufacturing magnetic toner is to melt and knead magnetic powder together with an adhesive resin and additives such as a colorant and a fluidity improver using a kneader or the like. This is a method of obtaining a magnetic toner by coarsely pulverizing the toner with a jaw crusher or the like, then finely pulverizing it with a jet mill, etc., and performing a spheroidization process after dispersion.

However, with this method, it is extremely difficult to uniformly disperse the magnetic powder and additives such as colorants and fluidity improvers in the adhesive resin, and it also requires a great deal of labor and energy. Problems caused by such toner non-uniformity include uneven magnetic properties and uneven electrical properties, and these phenomena greatly affect toner transportability, causing uneven development and fixing, and as a result, It is difficult to obtain stable and good printing.

For magnetic toner produced by these pulverization methods, for example, Japanese Patent Application Laid-Open No. 54-84730 and Japanese Patent Application Laid-Open No. 54-847
No. 31, JP-A-57-53756, JP-A-Sho 5
As described in Japanese Patent Application Laid-open No. 7-81271, Japanese Patent Application Laid-open No. 58-7646, and Japanese Patent Application Laid-Open No. 58-80650, toners produced by suspension polymerization have been proposed. These toners are produced directly by suspending a mixture of polymerizable monomers, polymerization initiators, magnetic materials, etc. in water and polymerizing them.What these toners have in common is that they all have a spherical shape. One example of this is that a magnetic substance is contained inside the particles.

The magnetic toner obtained by this polymerization method was able to compensate for the drawbacks of the magnetic toner obtained by the above-mentioned pulverization method, but it also had the disadvantage of severe deterioration of the toner due to changes in the amount of charge during continuous copying. A new occurrence has occurred. In other words, in the case of spherical magnetic toner obtained by the polymerization method, the rate at which large particles are selectively used for development during continuous copying is significantly higher than that of amorphous toner made by the pulverization method. This causes a large change in the amount of charge during continuous copying, which is unfavorable in terms of long-run characteristics.

Particularly when recycled toner is used, disadvantages such as a decrease in image density and fog appear.

That is, the spherical magnetic toner produced by the polymerization method is required to have a more uniform particle size than the amorphous magnetic toner produced by the pulverization method. As a method for overcoming these drawbacks in the suspension polymerization method, as described in JP-A-57-102666, a slightly water-soluble inorganic powder is used as a suspension protectant and suspended in a homomixer. There is a method of manufacturing toner with uniform particle size by doing so. However, even with this method, it is difficult to sufficiently control the particle size, and a toner with a uniform particle size cannot be obtained.

FiPOT Publication No. WO 83103920 discloses a method for obtaining a magnetic polymer having spherical particles and uniform particle size.

In this method, an oil-soluble initiator is first absorbed into monodisperse seed particles, and then an inert solvent such as cyclohexanol or toluene and a crosslinking monomer are absorbed and polymerized to obtain porous, monodisperse particles. At this time, a functional group-containing polymerizable monomer is copolymerized, or the porous polymer particles are nitrated71 to add a functional group that easily binds to iron into the polymer. Next, it is dispersed in an aqueous solution containing a salt of divalent iron or other metal and an iron salt of 31i, the pH is raised, and the metal is precipitated in the form of hydroxide, adsorbed on the surface and inside of the polymer particle, if necessary. The magnetic latex is produced by heating.

By this method, it is possible to obtain magnetic polymer particles having an arbitrary size of 1 to 20 microns and having an extremely uniform particle size and in which fine magnetic material is uniformly dispersed in the polymer particles.

In this method, the polymer particles are made porous to increase the content of magnetic material, but in order to make the polymer particles porous, it is necessary to use an extremely large amount of crosslinking agent. It has been impossible to impart properties for toners, such as heat fixing properties and pressure fixing properties, to the resulting polymer.In order to obtain a polymer that has properties suitable for toners, it is necessary to use or do not use a crosslinking agent. As a result, it is difficult to make the particles porous, while the amount of iron that can be adsorbed onto non-porous polymer particles is less than 5% by weight of the polymer, which is sufficient for magnetic toner. cannot have.

OBJECT OF THE INVENTION An object of the present invention is to provide nine magnetic polymer particles in which a magnetic material is dispersed in a high concentration in polymer particles that are almost completely spherical and have an extremely uniform particle size. The object of the present invention is to provide a new magnetic toner for developing electrostatic images that has improved properties and pressure fixability and overcomes all the various drawbacks of existing magnetic toners.

Components of the Invention The magnetic toner of the present invention is produced by dispersing porous polymer particles in an aqueous medium containing metal salts mainly composed of iron salts, and dispersing the polymer particles in the form of metal hydroxides and/or oxides. Magnetic polymer particles containing a metal oxide obtained by precipitating into particles and heating them if necessary, as whole seed particles, and further including a polymer having a glass transition temperature C (hereinafter referred to as T2) of 30 to 80°C. Fixation obtained by adding one type or F12 or more polymerizable monomers giving 0.2 to 4 times the weight of the magnetic polymer particles, and polymerizing the polymerizable monomers in an aqueous medium. The structure of the present invention, which is a magnetic toner with good properties, will be explained in detail below.

Production of porous polymer particles> The porous polymer particles used in the present invention can be produced by the following method.

After absorbing the oil-soluble polymerization initiator and the crosslinkable multi-vinyl monomer together with an inert solvent into the seed polymer particles, the temperature is raised in an aqueous medium to carry out one reaction, and the polymerization is completely completed. is removed under reduced pressure or the like to produce porous polymer particles.

The seed polymer particles used here are not particularly limited as long as they are swollen by cross-linkable multi-vinyl monomers and monomers used in the next step; for example, styrene polymers, styrene copolymers, etc. Aqueous latexes, emulsions, and dispersions can be used. It is preferable that the particle size of the seed polymer particles be uniform because the particle size of the final product will be uniform.

The oil-soluble polymerization initiator is not particularly limited as long as it has the ability to initiate polymerization at the polymerization temperature, but specific examples include azobisisobutyronitrile, benzoyl peroxide, 2,
4-Dichloropenzoyl-oxy-2, octanoyl-(-oxide, tertiary-butyl-oxy-2)
-Ethylhexanoate, lauroyl peroxide and the like.

When the oil-soluble polymerization initiator is expected to also function as a swelling aid, the water solubility is preferably 10% by weight.
It is desirable that the amount is 4% by weight or less, and for example, octanoyl oxide can be used.

Oil-soluble polymerization initiators that are somewhat water-soluble, such as azobisisobutyronitrile and tert-butylno-oxy-2-ethylhexanoate, can be used in combination with lipophilic substances as initiators and swelling aids. It is possible.

The lipophilic substance has a solubility in water of 10-3% by weight, preferably 10-4% by weight or less, and a molecular weight of 5'000 or less, preferably Fi500 or less. Specifically 1
-Chlordodecane, dioctyl adipate, etc. In order to absorb these into the seed polymer particles, the lipophilic substance may be emulsified and dispersed in water using soap or the like, and the seed polymer particles may be added to the water. At this time, it is also possible to add a water-soluble solvent such as acetone to promote the transfer of the lipophilic substance to the seed particles.

As the crosslinkable multivinyl monomer, aromatic di- or trivinyl monomers such as divinylbenzene, ethylene glycol dimethacrylate, etc. can be used.

Toluene, cyclohexanol, etc. can be used as the inert solvent.

During the polymerization of crosslinkable polyvinyl monobonds, vinylpyridine,
An amino group-containing vinyl monomer such as dimethylaminoether methacrylate or an epoxy group-containing vinyl monomer such as glycidyl methacrylate is simultaneously added to swell the seed polymer particles.

Can be polymerized. In the latter case, amino groups can be added to the polymer particles by further treatment with ethylenediamine or the like. As a result, porous polymer particles with good iron adsorption properties can be obtained.

Furthermore, when the amination treatment is not performed, nitration treatment of the porous polymer is also effective in increasing the adsorption of iron. When a porous polymer contains many aromatic rings such as benzene rings, the aromatic rings can be easily nitrated by dispersing the porous polymer in a mixed acid of concentrated sulfuric acid and concentrated nitric acid. , nitro group-containing porous polymer particles are obtained.

<Production of magnetic polymer particles> Porous polymer particles in an aqueous medium are dispersed in an aqueous medium mainly consisting of water, and metal salts such as iron salt or iron salt, manganese, Coba A), nickel, etc. The pH of the υ system is raised with ammonia or the like, and if necessary, the metal is precipitated as a hydroxide and/or oxide in the pores of the polymer particles and on the surface of the polymer particles under heating. Then, heating is performed to change the metal into an oxide (magnetic ferrite) to obtain magnetic polymer particles.

In the case of nitrated magnetic polymer particles, ferrous sulfate,
Divalent iron salts such as ferrous chloride are preferably used.

In the case of aminated magnetic polymer particles, divalent iron ions and trivalent iron ions are used in a molar ratio of about 1=2, and p
Increase Hk to precipitate iron on the combined particles. Here, part of the divalent iron ions can also be replaced with divalent ions such as manganese, cobalt, and nickel.

The iron salt and other metal salts may be water-soluble salts such as chlorides, sulfates, and nitrates, as long as they can precipitate hydroxides when the H content of the aqueous solution is increased.

The content of the magnetic material, that is, the oxide of metals including iron, in the magnetic polymer particles is usually in the range of 10 to 60% by weight.

<Manufacture of magnetic toner> Using magnetic polymer particles containing metal such as iron as seed particles, polymerize one type of polymerizable monomer with an original length of 2 m or more to give a polymer with a Tf of 30 to 80''b. , Tf is 30-80
℃ polymer is formed on the surface of magnetic polymer particles, or on the surface and inside of magnetic polymer particles to produce a magnetic toner. The amount of the polymerizable monomer used is 0.2 to 4 times the weight of the magnetic polymer particles.

Specific examples of polymerizable monomers include styrene, α-methylstyrene, p-methylstyrene, halogenated styrene,
Aromatic vinyl monomers such as divinylbenzene, vinyl esters such as vinyl acetate and vinyl zolopionate, unsaturated nitrites such as acryl tetranitrile, methyl acrylate,
Methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate), 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, etc. Examples include ethylenically unsaturated cardinic acid alkyl esters. Conjugated diolefins such as sitadiene and isoprene can also be used1, including acrylamide, methacrylamide, glycidyl acrylate, glycidyl methacrylate, N-methylolacrylamide, N-methylolmethacrylamide, 2-hydroxyethyl Acrylate, 2-hydroxyethyl methacrylate, etc., diallyl phthalate, allyl acrylate,
Allyl methacrylate and the like can also be used depending on the purpose.

These monomers are used individually or in combination of two or more so that the Tf of the polymerization edge is in the range of 30 to 80°C.

A particularly preferred monomer is a mixture of styrene and ethyl acrylate.

The amount of the polymerizable monomer to be used is 0.000% relative to the magnetic polymer particles.
It is 2 to 4 times (weight ratio). If it is less than 0.2 times, it is difficult to impart film-forming properties as a toner, while if it exceeds 4 times, the magnetic substance content in the magnetic toner decreases, and in either case, the performance as a magnetic toner is impaired. becomes difficult to grant.

The seed polymerization method is not particularly limited as long as it can achieve the above objective, but the following two are preferred embodiments.

<Example 1 of seed polymerization> A polymerizable monomer in which an oil-soluble polymerization initiator is dissolved in advance is brought into contact with magnetic polymer particles to cause swelling and absorption, and polymerization is carried out by heating in an aqueous medium while stirring. As the oil-soluble polymerization initiator, those exemplified in the production of the porous polymer can be used, and it is used in an amount of 0.5 to 5 parts by weight per 100 parts by weight of the polymerizable monomer. 1μm of polymerizable monomer to promote swelling absorption
The particles may be made into fine particles using a homogenizer and then brought into contact with magnetic polymer particles. The polymerization temperature is usually 50 to 90°C, although it depends on the type of polymerization initiator. As the emulsifier, conventional emulsifiers such as anionic emulsifiers such as sodium lauryl sulfate and sodium dodecylbenzenesulfonate, and nonionic emulsifiers such as polyoxyethylene alkyl ether and polyoxyethylene alkylphenyl ether can be used. Also polyvinyl alcohol, polyvinylpyrrolidone, gelatin, cardixymethyl cell 0
It is also possible to prevent fusion between particles by using a protective colloid or a dispersant such as -sodium salt or sodium polyacrylate. After the polymerization is completed, the magnetic toner is separated from the water and dried.

<Example 2 of seed polymerization> Magnetic polymer particles and polymerizable monomers are heated in an aqueous medium in the substantial absence of an emulsifier using persulfate as a polymerization initiator while stirring. Polymerize.

Fi, potassium salt, sodium salt, ammonium salt, etc. can be used as the persulfate. The amount of persulfate used is at least the amount necessary to complete the polymerization, but if it is too large, new particles (not containing magnetic material) that are stable in the aqueous phase are formed, which is not preferable. In the case of potassium persulfate, the amount is 0.5 to 5 parts by weight per 100 parts by weight of the polymerizable monomer. Further, before polymerization, a protective colloid or dispersant such as polyvinyl alcohol, calxoxymethylcellulose, or sodium polyacrylate may be used for the purpose of improving the dispersibility of the magnetic polymer particles.

After the polymerization is completed, the magnetic toner is separated from the water and dried. The magnetic toner obtained in this way can be used as is, but
It is preferably colored with a dye or Kazen black by a known method, and if necessary, a charge control agent, an antiblocking agent, etc. can be added to further enhance the performance as a magnetic toner.

Effect of the invention The effects of the present invention are listed below.

(1) Since a completely spherical and extremely monodisperse magnetic toner can be obtained by polymerization, there is no need for classification or spheronization treatment, unlike currently practiced pulverization methods.

(2) The copier has good long-run characteristics and is easy to maintain.

(3) Higher resolution in copying.

(4) Since the single electric current that provides a low Tf polymer is completely absorbed and polymerized, and is encapsulated with a low Tf polymer, it has good fixability as a magnetic toner.

EXAMPLES The present invention will be explained in more detail based on Examples below. In the following description, parts and parts are by weight, respectively.

Example 1 5 parts of octanoyl peroxide (G-Royl 0; NOF) were added to 42.5 parts of water, 7.5 parts of acetone, and 0.15 parts of sodium lauryl sulfate using a Manton Galarin homogenizer (model 15M). Gold used 0.15~0.35μ
1 piece distributed over m. Sail 9 here as a seed polymer particle
2 parts of 1 μm monodisperse polymer polystyrene particles (solid content)
and 16.5 parts of water were added, and the mixture was slowly stirred at 5° C. for 20 hours, so that the octanoyl peroxide was absorbed into all the Boristine particles. Remove acetone by vacuum;
Transferred to a 3t sepa2 pull flask, added 800 parts of water and 3.25 parts of sodium lauryl sulfate, added 40 parts of dimethylaminoether methacrylate, 90 parts of ethylene glycol dimethacrylate, and 200 parts of cyclohexanol, and stirred for 2 hours. It was absorbed into the seed particles. Another 800 parts of water was added, the temperature was raised to 60°0, and the polymerization was completed in 8 hours.

Wash with water and isopropyl alcohol to obtain 120 parts of monodispersed porous particles of 5.0 μm.

A mixture of 2026 parts of Fe0136H dissolved in 1000 parts of water and 2011 parts of Fe(J24H) dissolved in 1000 parts of water were mixed at 10°O, then 50 parts of the above porous particles were added, and the pressure was reduced to 10 mmHy. and mixed.

Next, 400 parts of 25% ammonia water was added, and 3
Heated for 0 minutes ◇ As a result, 5,0 containing 18% by weight as Fe3O4
Monodisperse polymer particles of μm were synthesized. Next, 177,741 parts (of magnetic polymer particles), 9 parts of butyl acrylate, and 1 part of azoisobutyronitrile (AIBN) were mixed, and water was heated at 40°C.
5°C in a solution of 5 parts of sodium lauryl sulfate.
It was dispersed to 0.2 to 0.4 μm. 050 parts of the magnetic polymer particles described above were added to this mixture, and the monomers and oil-soluble initiator were absorbed into the magnetic polymer. 600 more water
part was added and polymerized at 70°C for 8 hours. The obtained magnetic polymer particles were extremely monodisperse particles of 6.1 .mu.m in which magnetic material was uniformly dispersed, and were excellent as a one-component magnetic toner.

Table 1 shows the results of investigating the performance of the obtained magnetic polymer particles as a magnetic toner.

In Comparative Example 1, an example was shown in which magnetic polymer particles were directly used as a toner. Although this product was used in an image format, the fusing ability by heat or pressure was very poor, resulting in poor fixing.

The particle size was measured by optical microscope photography, and the particle size of 50 or more particles was measured on the photo to determine the average particle size.

The glass transition temperature (T?) was measured by the DSO method.

The resolution is the facsimile test chart of the Institute of Image Electronics Engineers of Japan)
Evaluation was made using Nol-R.

Powder contamination was determined by the contamination in the blank areas of the above chart.

The fixability was judged by rubbing the copy by hand immediately after it came out of the copying machine, and checking the fixed state of the image.

For blocking properties, put 100 tons of toner in a paper bag and
A load of t7 cm2 was applied to the bag, and the state of the toner was judged after 24 hours at 30°C.

The magnetic substance content was determined from the ash content after baking a portion of the polymer at 80° C. in an electric furnace.

Table 1 (Note) ○ indicates excellent, Δ indicates slightly poor, and × indicates poor.

Example 2 Magnetic polymer particles (■) were used as seed particles, and the monomer composition was changed to styrene to butyl acrylate (8T/BA (!).
: Abbreviation: A magnetic toner was produced in the same manner as in Example 1 except that f = 75/25.

Its temperature was 45°C.

Example 3 A magnetic toner was produced in the same manner as in Example 1, except that magnetic polymer particles (1) were used as seed particles and the monomer composition was ST/BA=90/10. Its temperature is 74℃
Met.

Comparative Example 2 A magnetic toner was produced in the same manner as in Example 1 except that magnetic polymer particles (1) were used as seed particles and the monomer composition was ST/BA=60/40. Its temperature is 19℃
Met.

Comparative Example 3 Example 1 except that magnetic polymer particles ■ were used as seed particles and the monomer composition was 8T/BA=95,15.
A magnetic toner was produced in the same manner as described above. That Tf92c
It was b.

Table 2 shows the performance of the magnetic toners obtained in Example 2 and Example 3, and Table 3 shows the performance of the magnetic toners obtained in Comparative Example 2 and Comparative Example 3. Example 2 had a slight defect in blocking properties, and Example 3 had a slight defect in fixing properties, but both could be used as magnetic toners. On the other hand, Comparative Example 2 showed severe blocking, and Comparative Example 3 had poor fixing properties, so both could not be used.

Table 2 (Note) ○ indicates excellent, Δ indicates slightly poor, and × indicates poor.

Table 3 (Note) ○ indicates excellent, Δ indicates slightly poor, and × indicates poor.

Example 4 A magnetic toner was produced in the same manner as in Example 1, except that magnetic polymer particles (1) were used as seed particles and the magnetic polymer particle/monomer ratio was set to 1/0.5.

Example 5 A magnetic toner was produced in the same manner as in Example 1 except that magnetic polymer particles (1) were used as seed particles and the magnetic polymer particle/monomer ratio was 1/1.8.

Comparative Example 4 A magnetic toner was produced in the same manner as in Example 1, except that magnetic polymer particles (1) were used as seed particles and the magnetic polymer particle/monomer ratio was 1/0.1.

Comparative Example 5 Example 1 except that magnetic polymer particles were used as seed particles and the magnetic polymer particle/monomer ratio was set to t-1/6.
A magnetic toner was produced in the same manner as described above.

The performances of the magnetic toners obtained in Examples 4 and 5 are shown in Table 4, and the performances of the magnetic toners obtained in Comparative Examples 4 and 5 are shown in Table 5. Comparative Example 4 had poor fixing properties, and Comparative Example 5 could not be developed as it was due to the small amount of magnetic material f.

Table 4 (Note: O indicates excellent, Δ indicates slightly poor, and × indicates poor.

Table 5 (Note) 0 indicates excellent, Δ indicates slightly poor, and × indicates poor.

Example 6 Tertiary buteroxy 2-ethelhexanoate ()zo-butyl 0; NOF) 2 parts, lauryl chloride 2 parts, sodium lauryl sulfate 0.15 parts, water 50 parts,
210 parts of acetate was emulsified using ultrasonic waves to give a concentration of 0.1 to 0.
It was dispersed to 3 μm. Two monodispersed polystene particles of 0.80 μm in solid content were added thereto, and the mixture was gently stirred at 30°C for 12 hours to swell the swelling aid and oil-soluble initiator in the polymer particles and remove the acetone. A seed solution was prepared.

Next, 1,450 parts of water and 2.5 parts of sodium lauryl sulfate were placed in a 217-grumble flask, and the above seed solution was added thereto.

35 parts of 4-vinylpyridine, divinylbenzene (
551s) and 165 parts of toluene were added, the monomer was absorbed into the seed particles, and polymerized at 70°C for 8 hours.

Toluene was extracted with acetone to obtain 80 parts of monodisperse porous particles with a particle size of 4.0 μm.

2026 parts of FeO, 6H dissolved in 1000 parts of water, and 2026 parts of FeO, 4H dissolved in too many parts of water.
One part of the solution was mixed at 0°C, and then 40 parts of the above porous particles were added and mixed under reduced pressure to 10 mmH9.

Next, 400 parts of 25% ammonia water was added, and 3
Heated for 0 minutes. As a result, monodispersed polymer particles of 4 μm containing 23 tritium as Pe304 were synthesized (magnetic polymer particles ①).

Next, to 050 parts of the magnetic polymer particles, 41 parts of styrene, 9 parts of butyl acrylate, 0.5 parts of potassium persulfate, and 5 parts of water.
00 parts were added and soap-free emulsion polymerization was carried out at 60 °C for 20 hours, and the magnetic polymer particles were encapsulated with a polymer with Tf = 60 °C. The obtained magnetic polymer particles were extremely monodisperse particles of 5 μm in which magnetic material was uniformly distributed, and were excellent as a magnetic toner.

Table 6 shows the performance of the obtained magnetic polymer particles as an 8-character toner.

Table 6 (Note) Q indicates excellent, Δ indicates slightly poor, and × indicates poor.

Comparative Example 6 A magnetic toner was produced in the same manner as in Example 6 except that 050 parts of magnetic polymer particles were used as seed particles and 0.2 parts of potassium persulfate was added.

Comparative Example 7 A magnetic toner was produced in the same manner as in Example 6 except that 050 parts of magnetic polymer particles were used as seed particles and 6 parts of potassium persulfate was added.

In Comparative Example 6, only a low L polymerization conversion rate of 40% or less was obtained, and the yield was poor.

In Comparative Example 7, 0.2 to 0 is stable as latex in the aqueous phase.
．． A large amount of new particles of 4 μm were generated.

Very little polymer encapsulated the magnetic polymer particles ■.

Claims (3)

[Claims] (1) Porous polymer particles are dispersed in an aqueous medium containing metal salts mainly composed of iron salts, and the metals are mixed with hydroxide and/or
or precipitated into polymer particles in oxide form, if necessary;
Magnetic polymer particles containing a metal oxide obtained by heating this are used as seed particles, and one or more types of polymerizable monomers are added to give a polymer having a glass transition temperature of 30 to 80°C. 0.2 by weight relative to the magnetic polymer particles
A magnetic toner with good fixability obtained by adding up to 4 times the polymerizable monomer and polymerizing the polymerizable monomer in an aqueous medium. (2) The magnetic toner according to claim 1, which is obtained by polymerizing a polymerizable monomer in an aqueous medium in the presence of an oil-soluble polymerization initiator. (3) A patent claim obtained by adding a polymerizable monomer in the substantial absence of an emulsifier and polymerizing the polymerizable monomer in an aqueous medium in the presence of a persulfate. The magnetic toner according to scope 1.