JP3131654B2 - Electrostatic image developer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic toner for developing an electrostatic image in electrophotography, electrostatic printing or electrostatic recording, and more particularly to a magnetic toner developer having good fixability and durability.

[0002]

2. Description of the Related Art An electrostatic image developer includes a two-component or one-component developer obtained by adding various characteristic assistants to a toner component of a binder resin containing a colorant. Is fixed to a recording and fixing material (hereinafter, collectively referred to as transfer paper).

[0003] The fixing of a toner image includes fusion by heat and pressure fixing of toner particles between paper fibers by pressure. The advantages of pressure fixing are high cost required for a pressure mechanism,
The shadows have become thinner, offset by the weight gain and imperfect fixability, and fusion fixation is dominant.

[0004] As the fusion fixing, there are a conventional heat roller fixing method and a hot plate fixing method by radiant heating.

The heat roller fixing is superior to the radiant heat fixing in that the heat efficiency is high. However, the heat-up time to the fixing temperature of the heat roller, the fixing temperature holding against the temperature decrease due to the heat dissipation by the transfer paper, or the offset, There is an inherent disadvantage associated with contact such as winding of transfer paper.

In particular, many improvements have been proposed for the offset phenomenon in toners used for fixing with a heat roller.

In the heat fixing, it is known to increase the molecular weight distribution of the resin in order to prevent the fixing roller from being stained by the offset phenomenon. For example, JP-A-56
No. -16144 has a molecular weight distribution of 10 ³ to 8 × 10 ⁴ and 10 ⁵ to 2
By mixing resins having different molecular weight distributions having a maximum value in the area of × 10 ^6, the developer is not pulverized inside the developing device without increasing the fixing temperature, and has low cohesion, high fluidity and high durability. It is possible to get it.

Further, using a resin having three peaks of molecular weight to prevent the offset phenomenon (Japanese Patent Application Laid-Open No. 58-82258), similarly controlling the peak ratio of the resin having three peaks of molecular weight, (Japanese Unexamined Patent Publication No. 60-230666)
No. 62-91960), and partially cross-linking a resin having three peaks in molecular weight with a decomposable metal compound,
A technique has been disclosed in which a reaction with a metal compound causes an increase in molecular weight distribution to improve fixability (offset) (JP-A-62-94854).

Further, regarding the molecular weight of the resin,
A resin having peaks in the 3000 to 5000 and 150,000 to 2,000,000 regions and having a gel content of 1 to 10% is used, and a combination of a low molecular weight and a high molecular weight (for example, a high molecular weight region has a peak area of 40%). 6060%) to lower the fixing temperature and eliminate the occurrence of offset (Japanese Patent Laid-Open No. 1-172284, 1-172844).
Further, regarding the molecular weight distribution, there is also a proposal to improve the fixing property by broadening the distribution as follows: 1000 ≦ Mn ≦ 7000 40 ≦ Mw / Mn ≦ 70 200 ≦ Mz / Mn ≦ 500 -284863).

On the other hand, from a different viewpoint, when the acid value is 3 to 50 and Mw is
Contains a resin obtained by reacting a resin of 7 × 10 ³ or more with a metal compound and a resin having an acid value of 1 or less and Mw of 10 ³ to 10 ⁵ ,
There is an example in which offset is improved by a reaction with a metal compound to enable fixing at a low temperature (JP-A-63-94251).

An acid value of 1 or less and Mw of 8 × 10 ³ -8
× 10 ⁴ styrene copolymer 10-90% by weight and acid value 1-1
A styrene-based copolymer having a Mw of 1 × 10 ⁵ to 1 × 10 ⁶
An example of a developer using a resin mixed with 90% by weight is also disclosed (JP-A-62-9356).

On the other hand, regarding the magnetic toner, there is a known technique for improving the dispersibility of the magnetic powder with respect to the treatment performed with a silane coupling agent, a titanium coupling agent, and various surfactants. However, in a magnetic toner, the technique of improving dispersibility by an additive has a problem that the surface of the magnetic powder is changed by the treatment and the chargeability is affected.

However, at present, a technique for improving the dispersibility of the magnetic toner without affecting the chargeability and further improving the fixability has not yet been completed.

The dispersion of the magnetic powder is improved by improving the affinity with the resin. The magnetic powder is an inorganic material, and for this purpose, it is important that the resin itself has a polar group. However, the mere presence of a polar group in the resin does not provide sufficient orientation of the resin to the magnetic powder during kneading, and does not sufficiently improve dispersion. In order to be oriented with respect to the magnetic powder in kneading, it is necessary to apply a large energy.

In order to improve the offset property, it is necessary to add a so-called release agent which is a low molecular weight polyolefin such as polypropylene or a low molecular weight polyolefin copolymer. In this case, the dispersion of the release agent such as non-polar polypropylene tends to be non-uniform. For this reason, it is important that a non-polarized resin component is present.

In this regard, we have found that in order to improve the dispersibility of the magnetic powder, it is important to include a polar group in the high molecular weight component and depolarize the low molecular weight component.

That is, the high molecular weight component receives a large energy in kneading and gives a large stress.

This energy causes an orientation to the magnetic powder, and the magnetic powder is sufficiently dispersed in the resin.

On the other hand, the presence of the low molecular weight component having no polar group improves the dispersion of the release agent, and enables a uniform kneading state to be formed. The charge amount distribution and the like are sharp and the selective developability is low. A so-called developer having good durability can be obtained. Further, since both the high molecular weight component and the low molecular weight component are present, it is possible to obtain a developer having good fixability.

[0020]

The objects of the present invention are: (1) good fixability, good fixability and no offset; and (2) good dispersion of magnetic powder, no selective developability, and continuous use. An object of the present invention is to provide a highly durable magnetic toner which maintains the composition homeostasis without causing selective consumption of components.

[0021]

The object of the present invention is to provide at least a magnetic powder, a low molecular weight polyolefin or a low molecular weight polyolefin copolymer and a binder resin in a molecular weight range of 1,000 to 30,000 in terms of styrene as measured by GPC. Styrene resin having a peak and 45,000 to 1,000
In a magnetic toner using a mixture of styrene and acrylic resin having a peak in the region of 0000,
A styrene / acrylic resin obtained by copolymerizing a vinyl carboxylate compound as a resin having a peak in a polymer region is used, and the styrene resin and the styrene / acrylic resin are used.
Mixing ratio of the resin is 10-90: 90-10,
Further, it is achieved by an electrostatic image developer, wherein the acid value of the binder resin of the mixture is 1 to 20.

Specific examples of the styrene-acrylic resin obtained by copolymerizing the high molecular weight carboxylic acid-containing component vinyl compound according to the present invention include styrene-based polymerizable monomers such as styrene, α-methylstyrene and chlorostyrene. Acrylates such as methyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate, methacrylic acid Methacrylates such as ethyl acrylate, propyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, dimethylaminoethyl methacrylate,
Vinyl acetate, vinyl esters such as vinyl propionate, acrylonitrile, methacrylonitrile, nitrogen-containing vinyl monomers such as vinylpyridine, etc., and acrylic acid, methacrylic acid, monobutyl maleate, monooctyl maleate, monobutyl fumarate, There is a copolymer with a carboxylic acid-containing vinyl monomer such as monooctyl fumarate.

The ratio in forming these copolymers is regulated by the softening point and acid value of the final resin,
The softening point is in the range of 120 ° C. to 200 ° C., and the copolymer ratio is controlled so that the acid value is 1 to 50. Further, the molecular weight of these resins is 4 in terms of styrene equivalent molecular weight in GPC.
It has a peak at 5,000 to 1,000,000. That is, when the softening point is high, there arises a problem that the fixability deteriorates, the image storability after the fixation decreases, and a high fixing temperature is required to increase power consumption. In addition, when the softening point is low, there is a problem that offset is likely to be severely generated.
Furthermore, by having a peak in this range, energy during kneading is sufficiently imparted, and the magnetic powder is sufficiently dispersed. If the peak has a molecular weight smaller than this range, sufficient energy during kneading cannot be provided, and the magnetic powder does not sufficiently disperse.

The styrene resin is a resin obtained by polymerizing a styrene monomer, and has a molecular weight having a peak in a range of 1,000 to 30,000 in terms of styrene as determined by GPC. If the peak is in a region larger than this range, the molecular weight becomes high, the compatibility with the low molecular weight polyolefin or the low molecular weight polyolefin copolymer becomes poor, and the dispersion becomes poor. On the other hand, when the peak molecular weight is small, the molecular weight itself is too low, resulting in poor fixability and storage stability.

As for the molecular weight distribution of the resin, the high molecular weight component is preferably in the range of 10 ⁵ to 10 ⁶ in terms of weight average molecular weight in terms of styrene by GPC, and the styrene resin is 5 × 10 ^3.
The range of 範 囲 8 × 10 ⁴ is preferred.

The resin is synthesized by using the production method described in JP-A-62-9356.

That is, as a synthesis method, known methods such as solution polymerization and suspension polymerization can be used.

Specifically, for the synthesis of a high molecular weight component, a method capable of increasing the molecular weight, such as suspension polymerization or bulk polymerization, is preferred. In order to obtain a low molecular weight component, solution polymerization and suspension polymerization are preferred. As a method for adjusting the molecular weight, there is a method of adjusting the addition amount of a polymerization initiator, a chain transfer agent, or the like, or a method of controlling by adjusting a reaction temperature and a reaction time. In addition, what is necessary is just to use the material shown by the polymerization method generally known as these polymerization initiators and chain transfer agents. As a method for mixing the high molecular weight component and the low molecular weight component, there are a method of polymerizing the components and mixing the obtained polymers, and a method of synthesizing the high molecular weight component after forming the low molecular weight component.

The high molecular weight component and the low molecular weight component are mixed with each other to form a binder resin, and the mixing ratio of the two is high molecular weight component: low molecular weight component = 10 to 90:90 to 10 by weight. The acid value of the binder resin is 1 to 20. If the ratio of the high molecular weight component in the mixing ratio of the two is 10% or less, the molecular weight distribution itself becomes low in molecular weight, and the fixability becomes poor. Furthermore, since there is little high molecular weight component, there is a problem that the dispersibility of the magnetic powder is reduced. When the high molecular weight component is 90% or more, the molecular weight distribution itself becomes high molecular weight,
Problems such as a decrease in the fixing property and an increase in the fixing temperature and a decrease in the durability of the fixing device occur. Further, there is a disadvantage that the dispersibility of the low-molecular-weight polyolefin and the low-molecular-weight polyolefin copolymer is reduced due to the reduced amount of the nonpolar component.

When the acid value of the resin is 1 or less, the dispersibility of the magnetic powder is reduced due to the small amount of the polar component.

On the other hand, when the acid value is 20 or more, the acid component is excessively present and a large number of hydrophilic groups are present, so that the hydrophilicity of the resin itself increases and the environment, particularly under high temperature and high humidity, As a result, there arises a problem that the developability decreases.

As the magnetic powder used in the present invention, any commonly used magnetic powder can be used. However, in order to improve the dispersibility of the magnetic powder, it is important that a high molecular weight component (having a polar group) is oriented with respect to the magnetic powder. For this reason, a magnetic powder having a small surface area is useful as a magnetic powder for improving dispersibility. For example, spherical magnetic powder is suitable. Spherical means that the ratio of the major axis to the minor axis is 0.9 or more.

Next, the low-molecular-weight polyolefin or low-molecular-weight polyolefin copolymer according to the present invention is obtained by polymerizing olefins such as propylene and ethylene, and polypropylene is particularly preferably used. Further, the softening point measured by the gentle and rapid ring and ball method specified in JIS K2531-1960 is preferably in the range of 100 to 180 ° C, particularly preferably in the range of 120 to 160 ° C. If the softening point exceeds the upper limit, problems such as poor fixability, reduced durability of the fixing device, reduced dispersibility in the toner, and reduced chargeability occur. If the softening point is lower than the lower limit, problems such as occurrence of offset, deterioration of the durability of the fixing device, deterioration of the cleaning property, and deterioration of the durability of the developer occur. I do.

The conventional techniques may be used for the external additives of the developer components, the charge control agent, and the like. Further, all conventionally known materials and methods can be used as long as the object of the present invention is not impaired.

The developing method using the magnetic toner of the present invention is not particularly limited. There are no particular limitations on the mag roll / sleeve dual rotation system, mag roll fixing system, AC bias application system, and the like. It is suitably used in an alternating electric field application system in which the toner layer is made thinner.

In the thin layer forming and developing method, a toner layer is formed in a thin layer and is carried into a developing area. Here, the term “thin layer” means that the thickness of the toner layer carried into the developing area is 20 to 500 μm.
As a method of forming such a thin layer, there are a method of forming a toner layer using a magnetic blade and a method of pressing a toner layer regulating rod, a plate or the like against the surface of the developing sleeve.

[0037]

【Example】

(Preparation of resin ) Resin preparation example 1 A styrene monomer was polymerized in a xylene solvent using azobisisobutyronitrile as a polymerization initiator to obtain a resin having a peak molecular weight of 5 × 10 ³ and a weight average molecular weight of 1 × 10 ⁴ . Obtained. This is called resin (low 1). Also, 80 parts of styrene, 15 parts of butyl acrylate, and 5 parts of acrylic acid are mixed, polymerized by bulk polymerization, and then polymerized in the presence of a xylene solvent to give a peak molecular weight of 8 × 10 ⁴ and a weight average molecular weight of 8 × 10 ⁵ . A resin was obtained. This is called resin (high 1). These resins (Low 1)
And (High 1) were mixed at a weight ratio of 40:60 to obtain a resin having an acid value of 15. This is referred to as “resin 1”.

Resin Preparation Example 2 A styrene monomer was polymerized in xylene solvent with azobisisobutyronitrile as a polymerization initiator to obtain a resin having a peak molecular weight of 8 × 10 ³ and a weight average molecular weight of 3 × 10 ⁴ . . This is called resin (low 2). Also, 56 parts of styrene, 40 parts of butyl methacrylate, and 4 parts of methacrylic acid were mixed, polymerized by bulk polymerization, and then polymerized in the presence of a xylene solvent to give a peak molecular weight of 5 × 10 ⁵ and a weight average molecular weight of 9 × 10 ⁵ . A resin was obtained. This is called resin (high 2). These resins (Low 2) and (High 2) were mixed at a weight ratio of 50:50 to obtain a resin having an acid value of 8. This is referred to as “resin 2”.

Resin Preparation Example 3 A styrene monomer was polymerized in xylene solvent with azobisisobutyronitrile as a polymerization initiator to obtain a resin having a peak molecular weight of 5 × 10 ³ and a weight average molecular weight of 1 × 10 ⁴ . . This is called resin (low 3). Also, 85 parts of styrene, 13 parts of butyl acrylate, and 2 parts of acrylic acid are mixed, polymerized by bulk polymerization, and then polymerized in the presence of a xylene solvent to have a peak molecular weight of 5 × 10 ⁵ and a weight average molecular weight of 9 × 10 ⁵ . A resin was obtained. This is called resin (high 3). These resins (Low 3)
And (High 3) were mixed at a weight ratio of 50:50 to obtain a resin having an acid value of 5. This is referred to as “resin 3”.

Comparative Resin Preparation Example 1 A styrene monomer was polymerized in xylene solvent with azobisisobutyronitrile as a polymerization initiator to obtain a resin having a peak molecular weight of 5 × 10 ³ and a weight average molecular weight of 1 × 10 ^4. Was. This is designated as resin (Comparative Low 1). Also, 85 parts of styrene and 15 parts of butyl acrylate were mixed, polymerized by bulk polymerization, and then polymerized in the presence of a xylene solvent to obtain a resin having a peak molecular weight of 5 × 10 ⁵ and a weight average molecular weight of 9 × 10 ⁵ . This is called resin (comparative height 1). These resins (Comparative Low 1) and (Comparative High 1) were mixed at a weight ratio of 50:50, and the acid value was 0.
Resin was obtained. This is designated as “Comparative Resin 1”.

Comparative Resin Preparation Example 2 A styrene monomer was polymerized in xylene solvent with azobisisobutyronitrile as a polymerization initiator to obtain a resin having a peak molecular weight of 4 × 10 ⁴ and a weight average molecular weight of 8 × 10 ^4. Was. This is designated as resin (Comparative Low 2). Also, 85 parts of styrene, 13 parts of butyl acrylate, and 2 parts of acrylic acid are mixed, polymerized by bulk polymerization, and then polymerized in the presence of a xylene solvent to have a peak molecular weight of 5 × 10 ⁵ and a weight average molecular weight of 9 × 10 ⁵ . A resin was obtained. This is called resin (comparative height 2). These resins (Comparative Low 2) and (Comparative High 2) were mixed at a weight ratio of 50:50,
A resin having an acid value of 5 was obtained. This is designated as “Comparative Resin 2”.

Comparative Resin Preparation Example 3 In Resin Preparation Example 3, resins (Low 3) and (High 3) were mixed at a weight ratio of 5:95 to obtain a resin having an acid value of 15. This is designated as “Comparative Resin 3”.

Comparative Resin Preparation Example 4 In Resin Preparation Example 1, resins (low 1) and (high 1) were mixed at a weight ratio of 95: 5 to obtain a resin having an acid value of 2. This is designated as “Comparative resin 4”.

(Example of Toner Production) A magnetic toner was produced using the resin obtained above.

Preparation Example 1 of Magnetic Toner 100 parts by weight of "Resin 1", 50 parts by weight of magnetic powder (average particle diameter by electron microscopy = 0.2 μm, spherical magnetite = ratio of major axis to minor axis = 0.95), low molecular weight polypropylene (Viscol 660P: Sanyo Chemical Co., Ltd.) was mixed with 3 parts by weight, and kneaded, crushed and classified under ordinary conditions to obtain colored particles having an average particle size (volume average particle size by a coulter counter) of 10.5 μm. . At this time, the kneading plate was collected. This kneading plate is referred to as “kneading plate 1”. 0.4% of hydrophobic silica was added to the colored particles and mixed with a turbula mixer to obtain the toner of the present invention. This is referred to as “magnetic toner 1”.

Magnetic Toner Preparation Example 2 A magnetic toner of the present invention was obtained in the same manner as in Magnetic Toner Preparation Example 1, except that “Resin 2” was used instead of “Resin 1”. Similarly, a kneading plate is collected, and this kneading plate is referred to as “kneading plate 2”. This is referred to as “magnetic toner 2”.

Magnetic Toner Preparation Example 3 The magnetic toner of the present invention was obtained in the same manner as in Magnetic Toner Preparation Example 1, except that “Resin 3” was used instead of “Resin 1”. Similarly, a kneading plate is collected, and this kneading plate is referred to as “kneading plate 3”. This is referred to as “magnetic toner 3”.

Preparation Example 4 of Magnetic Toner 100 parts by weight of “Resin 1”, 50 parts by weight of magnetic powder (average particle diameter by observation with an electron microscope = 0.2 μm, hexahedral magnetite: ratio of major axis to minor axis = 0.75), low molecular weight polypropylene (Viscol 660P: Sanyo Kasei) was mixed with 3 parts by weight, kneaded, pulverized, and classified under ordinary conditions to obtain colored particles having an average particle size (volume average particle size by a coulter counter) of 10.5 μm. . At this time, the kneading plate was collected. This kneading plate is referred to as “kneading plate 4”. 0.4% of hydrophobic silica was added to the colored particles and mixed with a turbula mixer to obtain a toner of the present invention. This is referred to as “magnetic toner 4”.

Comparative Toner Preparation Example 1 A comparative magnetic toner was obtained in the same manner as in Magnetic Toner Preparation Example 1, except that “Resin 1” was used instead of “Resin 1”. Similarly, a kneading plate is collected, and this kneading plate is referred to as “comparative kneading plate 1”. This is referred to as “Comparative Toner 1”.

Comparative Toner Preparation Example 2 A comparative magnetic toner was obtained in the same manner as in Magnetic Toner Preparation Example 1, except that “Resin 1” was used instead of “Resin 1”. Similarly, a kneading plate is collected, and this kneading plate is referred to as “comparison kneading plate 2”. This is referred to as “Comparative Toner 2”.

Comparative Toner Preparation Example 3 A comparative magnetic toner was obtained in the same manner as in Magnetic Toner Preparation Example 1, except that “Resin 1” was used instead of “Resin 1”. Similarly, a kneading plate is collected, and this kneading plate is referred to as “comparison kneading plate 3”. This is referred to as “Comparative Toner 3”.

Comparative Toner Preparation Example 4 A comparative magnetic toner was obtained in the same manner as in Magnetic Toner Preparation Example 1, except that “Resin 1” was used instead of “Resin 1”. Similarly, a kneading plate is collected, and this kneading plate is referred to as “comparison kneading plate 4”. This is referred to as “Comparative Toner 4”.

(Evaluation) Evaluation of Dispersibility The above “Example 1 of preparing magnetic toner” to “Example 3 of preparing magnetic toner”
And "Comparative Toner Preparation Example 1" to "Comparative Toner Preparation Example 4"
The kneaded plate obtained by kneading was thinly sliced (thickness of about 0.5 μm) with a microtome, and the sliced pieces were observed with an optical microscope to evaluate the dispersibility of the low molecular weight polypropylene and the magnetic powder. Observation magnification is 60
The photograph was photographed and the dispersibility was visually determined. The evaluation criteria were ranked as "good" when the dispersed particles of the polypropylene were uniformly dispersed, and "bad" when the dispersed particles were non-uniform and large. The same evaluation was performed for the magnetic powders, and a sample in which no aggregate of the magnetic powder was present was evaluated as “good”, and a sample in which an aggregate was present was evaluated as “bad”. The result of ranking is shown.

* Dispersion order of polypropylene (Good) "Kneading plate 1" = "Kneading plate 2" = "Kneading plate 3" =
“Kneading plate 4” = “Comparative kneading plate 2” = “Comparative kneading plate 4”>
"Comparative kneading plate 1">"Comparative kneading plate 3" (bad) * Dispersibility order of magnetic powder (Good) "Kneading plate 1" = "Kneading plate 2" = "Kneading plate 3" =
"Comparative kneading plate 1" = "Comparative kneading plate 3">"Kneading plate 4">
"Comparative kneading plate 2">"Comparative kneading plate 4" (poor) As described above, it is understood that the dispersibility of polypropylene becomes poor in the low molecular weight component in the region outside the present invention.
It is also understood that the dispersibility of the magnetic powder is similarly poor if a high molecular weight component is present in a region outside the present invention.

Evaluation of Developability The toner obtained as described above was evaluated for developability. The evaluation was performed using a laser printer "LP-3015" (manufactured by Konica Corporation), equipped with an organic photoconductive photoreceptor and a developing device fixed to a magnet roller, and using a contact developing method applying an AC bias. Was.

As a thin layer forming method, a toner layer regulating method of a magnetic blade type is adopted, and the thickness of the toner layer is set to 150 μm.
And The developing device has a developing sleeve having a diameter of 25 mm and a four-pole magnet roller inside. The magnet roller is fixed and only the developing sleeve rotates. The gap between the developing sleeve and the surface of the photoconductor was set to 100 μm. In addition, the polarity of the photoreceptor is negatively charged, and is a method of performing exposure corresponding to an image using a laser.

DC of -250V under the condition of photoconductor potential -500V
Bias is applied, frequency 2kHz, voltage -50 ~ -4
An AC bias with a 50 V peak was applied. Also,
The environmental conditions for the evaluation were 30 ° C. and 80% RH, and printing was performed 20,000 times, and the image density was measured. The concentration is Macbeth densitometer RD-91
4 was used to measure the reflection density. In addition, fog was also evaluated. Change in concentration, change in fog (initial ~
Table 1 shows the results of the evaluation (after 20,000 times).

[0058]

[Table 1]

As described above, it can be understood that the magnetic toner of the present invention has a stable density transition and a fog transition at a low value.

[0060]

According to the constitution of the present invention, the dispersion of the polyolefin and the magnetic powder in the magnetic toner is good, the fixing performance of the developed image is good, the density is high, the fog is low, the stability is good, and the fixing performance is good. Thus, a magnetic toner having good durability can be obtained.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-311851 (JP, A) JP-A-3-177847 (JP, A) JP-A-2-161465 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G03G 9/08-9/087

Claims (1)

(57) [Claims] 1. At least a magnetic powder, a low-molecular-weight polyolefin or a low-molecular-weight polyolefin copolymer, and a binder resin having a molecular weight of 1,1 in terms of styrene in GPC measurement.
In a magnetic toner using a mixture of a styrene resin having a peak in the region of 000 to 30,000 and a styrene / acryl resin having a peak in the region of 45,000 to 1,000,000, using the styrene-acrylic resin obtained by copolymerizing a free carboxylic acid vinyl compound as a resin having a peak, the styrene
The mixing ratio of the acrylic resin and the styrene / acrylic resin is 10
To 90:90 to 10, and an acid value of the binder resin of the mixture is from 1 to 20.