JPH0777842A - Electrostatic charge image developing developer and image forming method - Google Patents

Abstract

PURPOSE:To provide an electrostatic charge image developer excellent in high resolution, high reproducibility of high light and high reproducibility of fine lines. CONSTITUTION:This developer for electrostatic charge image developing contains a toner and a carrier. The carrier has 5-100mum particle size, <=3.0g/cm<3> bulk density, 30-150emu/cm<3> magnetization (sigma10000) for 1000Oe, >=25emu/cm<3> magnetization (residual magnetization sigmar) for 0Oe, and coercive force is <300Oe The toner is directly obtd. by water-base suspension polymn. The mol.wt. distribution of the resin component which constitutes the toner measured by GPC has at least one peak in the range from 5000 to 50000. The resin component contains at least one polar component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an electrophotographic photoreceptor as a latent image carrier to form a latent image, visualizes the latent image with a developer, and transfers the latent image to a transfer material. And a method for forming an image.

[0002]

BACKGROUND OF THE INVENTION Electrophotography is described in US Pat. No. 2,297,
As described in Japanese Patent Application No. 691 etc., a number of methods are known, and generally, a photoconductive substance is used to form an electric latent image on a photoreceptor by various means, and then the latent image is formed. The image is developed with toner and, if necessary, the toner image is transferred to a transfer member such as paper and then fixed by heating, pressure, solvent vapor or the like to obtain a copy. Further, as a method of developing with a toner or a method of fixing a toner image, various methods have been conventionally proposed, and a method suitable for each image forming process is adopted.

Conventionally, toners used for these purposes are generally toners having a desired particle size by a fine pulverizer and a classifier after melt-mixing a colorant consisting of dyes and pigments in a thermoplastic resin and uniformly dispersing them. Has been manufactured.

While this method of manufacture can produce fairly good toners, it does have certain limitations, ie, the choice of toner materials. For example, the resin colorant dispersion must be sufficiently brittle to be comminuted in an economically feasible manufacturing apparatus. However, if the resin colorant dispersion is made brittle in order to satisfy such requirements, the particle size range of the particles formed when actually pulverized at a high speed tends to be wide, and in particular, a relatively large proportion of fine particles is The problem of inclusion arises. Further, such a brittle material is likely to undergo further fine pulverization or pulverization when used for developing such as a copying machine. Further, in this method, it is difficult to completely uniformly disperse solid fine particles such as a colorant in the resin,
Depending on the degree of dispersion, fog may increase, image density may decrease, and color mixture and transparency may be poor. Therefore, attention must be paid to dispersion. In addition, the exposure of the colorant on the fracture surface may cause fluctuations in the developing characteristics.

On the other hand, in order to overcome the problems of toner by the pulverization method, Japanese Patent Publication Nos. 36-10231 and 43-43
A method for producing a toner by a suspension polymerization method has been proposed by 10799 and 51-14895. In the suspension polymerization method, a polymerizable monomer, a colorant, a polymerization initiator and, if necessary, a crosslinking agent, a charge control agent, and other additives are uniformly dissolved or dispersed to obtain a monomer composition. , A continuous phase containing this monomer composition containing a dispersion stabilizer,
For example, it is dispersed in an aqueous phase using a suitable stirrer, and at the same time, a polymerization reaction is carried out to obtain toner particles having a desired particle size.

Since this method does not include a crushing step at all, the toner does not need to be brittle, a soft material can be used, and the colorant is not exposed on the surface of the particles. It has the advantage of having excellent triboelectric charging properties. Further, since the classification process can be omitted, there are great cost reduction effects such as energy saving, time reduction, and process yield improvement.

As described above, the polymerized toner has many advantages, but from the viewpoint of higher image quality and high durability of electrophotography in recent years, sufficient toner has not been obtained yet.

The polymerized toner is characterized by its manufacturing method.
Of the various additives added to the monomer composition, those having polarity are likely to be unevenly distributed on the toner surface and its vicinity. This feature makes it possible to reduce the amount of additives used for imparting various toner characteristics, but on the other hand, in view of improving image quality, especially maintaining high image quality, it can be used as a sleeve, carrier, etc. There is a drawback that deterioration of the toner surface due to the rubbing of the toner greatly affects the toner characteristics.

In general, a carrier which constitutes a two-component developer is a conductive carrier typified by iron powder, an iron powder,
It is roughly classified into a so-called insulating carrier in which the surface of nickel, ferrite, etc. is coated with an insulating resin. When an alternating electric field is applied to achieve high image quality, if the resistance of the developer carrier is low, the carrier leaks the latent image potential and a good image cannot be obtained. When the carrier core is electrically conductive, it is preferably used by coating, and ferrite having a high resistance to some extent is preferably used as the core material.

Since iron powder has a high magnetic force, the developer brush becomes hard in the developing area where the developer toner is developed, and therefore, the developer brush becomes sharp, and the image becomes high in quality. Can't get Therefore, ferrite is also preferably used in order to reduce the magnetic force of the carrier and achieve high image quality.

To form a high quality image, Japanese Patent Laid-Open No. 59-1
No. 04663 discloses that the saturation magnetization value of the carrier is 50 em.
It has been proposed that a satisfactory image free from crimping can be obtained by setting the ratio to u / g or less, but the reproducibility of fine wires is improved by using a carrier whose saturation magnetization value is gradually decreased, but the magnetic pole As the distance from the carrier increases, the phenomenon in which the carrier adheres to the electrostatic image carrier, that is, the so-called photosensitive drum (carrier adhesion) becomes remarkable.

Further, Japanese Patent Publication No. 4-3868 proposes to use a so-called hard ferrite having a coercive force of 300 Gauss or more as a carrier. However, this is a system for making full use of hard ferrite having a high coercive force as a carrier, and an increase in the size of the device cannot be avoided. In order to realize a small-sized high-quality color copying machine, it is preferable to use a developer carrying member using a fixed magnetic core. In this case, a hard carrier having a high coercive force is
Due to the self-aggregating property, there is a problem that the transportability is rather deteriorated.

Further, Japanese Patent Laid-Open No. 2-88429 proposes to use a hard ferrite composed of a spinel phase and a magnet-plumbite phase containing a lanthanoid element as a carrier. Since it has conductivity, in a system in which development is performed by an alternating electric field for obtaining a higher quality image, it is not preferable in that development is disturbed because charges leak through carriers.

Therefore, in the system for developing by an alternating electric field, it is necessary that the resistance of the carrier is higher than a certain level.

As described above, no sufficient developer carrier has been obtained which can prevent the carrier from adhering and satisfy the reproducibility of high image quality, especially highlight.

On the other hand, as a matter of course, the electrophotographic photosensitive member is required to have predetermined sensitivity, electrical characteristics, and further optical characteristics according to the electrophotographic process to which it is applied. However, not only that, the durability of the photoreceptor is also an important property. Even with excellent electrophotographic characteristics at low humidity, it is difficult to obtain a stable and clear image on a photoreceptor in which the surface potential of the photoreceptor significantly decreases under high humidity. In addition, in the electrophotographic process for transferring,
Since the photoconductor is usually used repeatedly, the chemical bond of the surface-forming substance is destroyed by corona discharge, and as a result, it reacts with ionized oxygen, ozone, water, nitric oxide, etc., and the surface becomes low in resistance. In many cases, the electrostatic charge retention in humidity is reduced and the sharpness of the image is impaired. In addition, adhered substances such as paper dust often reduce the charge holding ability of the photoconductor and cause image deletion.

Since the surface of the photoreceptor is coated with a resin, the performance of the resin is particularly important, and a resin having excellent durability has been demanded. Recently, as a resin satisfying these requirements, a polycarbonate resin having bisphenol A as a skeleton (hereinafter referred to as bisphenol A type polycarbonate) has been studied as a binder for a surface layer.

However, firstly, a polycarbonate resin as an engineering plastic generally has a large surface free energy, and a developer (hereinafter abbreviated as toner) is easily attached to the surface. When the image is displayed in this situation,
The phenomenon that many white spots appear on the entire black image (hereinafter abbreviated as solid black) is likely to occur.

Secondly, when a photosensitive member is prepared, a film is formed by dissolving these binder resin and charge transport material in a solvent, coating and drying. The resin formed under such conditions has a residual strain stress in its internal structure, and the polycarbonate resin has a particularly strong tendency, and has a drawback that so-called solvent crack is likely to occur. When handling the photoconductor thus created or mounting it on an electrophotographic apparatus, for example, when the hand of a person touches it or it comes in contact with various oils used in the apparatus, the photoconductor cracks and a defective image is formed. Appears.

Thirdly, since the surface has a large coefficient of friction, the amount of abrasion is increased when cleaning with urethane rubber or the like, which makes it difficult to increase the number of durable sheets.

[0021]

SUMMARY OF THE INVENTION An object of the present invention is to provide a developer and an image forming method which solve the above problems.

That is, an object of the present invention is to provide a developer and an image forming method which are excellent in high resolution, high highlight reproducibility and high fine line reproducibility.

A further object of the present invention is to provide a developer and an image forming method capable of maintaining a high quality image without deterioration in image quality even when a large number of sheets are copied.

A further object of the present invention is to provide a developer having an excellent fixability and an image forming method.

[0025]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic charge image developing developer having a toner and a carrier, wherein the carrier has a particle size of 5 to 100 μm and a bulk density of 3. 1.0 g / cm ³ or less, and the magnetic characteristics of the carrier are 1 after magnetic saturation as shown in FIG.
The magnetization intensity (σ ₁₀₀₀ ) at 000 oersted is 3
0 to 150 emu / cm ³ or less, and residual magnetization: σ
r is 25 emu / cm ³ or more, the coercive force is less than 300 Oersted, and the following formula is satisfied,

[0026]

[Equation 3]

[Wherein σ ₁₀₀₀ and σ ₃₀₀ represent the magnetization intensity (emu / cm ³ ) at 1000 and 300 oersteds after magnetic saturation, respectively. ]
Further, the toner is directly obtained by an aqueous suspension polymerization method, contains at least a colorant and a resin, and at least one of the peaks of the molecular weight distribution by GPC of the resin component constituting the toner is 5,000. It is achieved by containing at least one or more polar components in the resin component constituting the toner.

Further objects are achieved by the present invention described below.

That is, a latent image is formed using an electrophotographic photosensitive member having a laminated structure of at least a conductive support, a charge generating layer and a charge transporting layer, and the latent image is visualized with a developer. In the image forming method of forming an image on a transfer material by transfer, a substance having fluorine and / or silicon atoms is present in the surface layer of the electrophotographic photosensitive member, and X
A photoconductor in which the ratio of them to carbon atoms by PS measurement is F / C 0.01 to 1.00 Si / C 0.03 to 1.00 is used, and the toner and the carrier are contained as the developer. This is achieved by using a developer.

The present invention will be described in detail below.

As a result of intensive studies to solve the above-mentioned problems of the prior art, the inventors of the present invention have been able to achieve it by setting the carrier magnetization intensity to 30 to 150 emu / cm ³ in the magnetic field at the developing pole. This is because the strength of the magnetic field at the developing pole is generally about 1000 Oersted, and the magnetic strength of the carrier at that time is weak, so that the magnetic brush of the developer becomes short and dense, and the brush becomes soft. Therefore, it is considered that the development faithful to the latent image could be achieved. It is considered that such a magnetic brush is short, dense, and soft, so that the developing efficiency is improved, especially in the development in which an alternating electric field that vibrates the developer is applied, and higher faithful development can be performed. Another advantage of the present invention is that deterioration of image quality can be prevented and high-quality images at the initial stage can be maintained. By using such a carrier with low magnetic force, the developing sleeve is coated with a developer. At this time, the magnetic coupling force of the carrier brush near the regulation member is weak and the brush is soft so that it does not give too much share to the toner, so polar substances on the toner surface are hard to be scraped off, and the initial high image quality is high. This is probably because the image can be maintained for a long time.

Further, as a result of detailed examination, it was found that carrier adhesion is likely to occur at a magnetic field strength of 0 to 300 oersted and does not occur when the carrier magnetization strength at that time is high to some extent. Further, the carrier adhesion depends on the developing bias condition, and particularly when developing by an alternating electric field, the carrier is more easily developed when it has a charge than the DC electric field, and the magnetic force is needed to attract it to the developing sleeve. Is required. Therefore, it is considered that the strength of the magnetization in the magnetic field is required to suppress the carrier adhesion. Therefore, according to the present invention, as shown in the hysteresis curve of FIG. 1, the magnetization intensity σ ₁₀₀₀ at 1000 Oersted is 30 to 150 emu / c.
m ^{3 which} is smaller than the conventional carrier, but 0 to 30
By increasing the strength of magnetization at 0 oersted, it is considered that carrier adhesion can be prevented while achieving high image quality.

Further, in general, a magnetic material having a large residual magnetization also has a large coercive force. It is a magnetic material such as a hard ferrite such as a so-called permanent magnet, and as described above, the mixing property with the toner due to self-aggregation and the developer transportability become poor, and the developer carrying member becomes a magnetic core applicator. As described above, a large and special developing device is required. However, the present invention does not use such a general hard magnetic material, but uses a carrier having a coercive force of less than 300 Oersted, so that even a small-sized developing device using a fixed magnetic core type developer carrier can be used. It is considered that a developer having good mixability with the toner and good developer transportability can be achieved.

The carrier used in the present invention is required to have the following magnetic characteristics of the carrier particles.

That is, 100 after magnetically saturated
The strength of magnetization (σ ₁₀₀₀ ) at 0 Oersted needs to be 30 to 150 emu / cm ³ . To achieve higher image quality, preferably 30 to 12
It is 0 emu / cm ³ . When it is higher than 150 emu / cm ^3, the density of the developer brush at the developing pole is not so different from the conventional one, and it becomes difficult to obtain a high quality image as in the present invention. When it is less than 30, the magnetic binding force at 0 to 300 oersteds is also reduced and carrier adhesion occurs.

The strength of remanent magnetization is 25 emu / c.
It must be m ³ or more. 25 emu / cm ³
If it is less than the above range, carrier adhesion is likely to occur in a developing system that uses a large contrast potential for high image quality or an alternating electric field with large amplitude, and the carrier-adhered portion is not transferred properly in the transfer process after development. As a result, high quality images cannot be obtained.

Furthermore, the coercive force must be less than 300 Oersted. If it is 300 oersteds or more, the carrier itself is self-aggregated, resulting in poor mixing property with the toner. Particularly, the carrier cannot move easily in the developing sleeve including the fixed magnet, and the carrier is transported on the developing sleeve. Therefore, a high quality image cannot be obtained because the coating property of the developer is deteriorated.

Further important in the present invention is the strength of magnetization in the vicinity of a magnetic field of 0 to 300 Oersted. Therefore, it is necessary to satisfy the following formula.

[0039]

[Equation 4]

[Wherein σ ₁₀₀₀ and σ ₃₀₀ represent the magnetization intensity (emu / cm ³ ) at 1000 and 300 oersteds after magnetic saturation, respectively. ]
Preferably, this value is 0.30 or less. Here, the hysteresis curve of FIG. 2 will be described. When it exceeds 0.40, it becomes impossible to achieve both the effect of preventing carrier adhesion while achieving the high image quality of the present invention. That is, σ
_If a value that satisfies ₁₀₀₀ is taken, high image quality can be achieved, but carrier adhesion tends to occur. Further, if a value that satisfies σ ₃₀₀ is taken, carrier adhesion can be prevented, but a large value of σ ₁₀₀₀ makes it impossible to obtain high-quality images as in the present invention.

The measurement of magnetic characteristics in the present invention is
Riken Denshi Co., Ltd. DC magnetization B-H characteristic automatic recording device B
It was performed using HH-50. Since a magnetic material is generally saturated in a magnetic field of 10 kilo Oersted, the saturation magnetization of carriers is set to a value of 10 kilo Oersted in the present invention. Therefore, the magnetic characteristic value was determined from a hysteresis curve at that time when a magnetic field of ± 10 kilo Oersted was created. Regarding the magnetic characteristics in the present invention, the sample was loosely put in a cylindrical plastic container, and then strongly packed and fixed while being magnetized by applying a magnetic field of 10 kilo Oersted, and the magnetic characteristics in that state were measured. This was used as the magnetic property of the present invention. The volume of the sample holder at that time was 0.332 cm ³ , and the strength of the magnetization per unit volume was obtained from this.

The average particle size of the carrier particles of the present invention is 5 to
The range is preferably 100 μm, more preferably 20 to
It is 80 μm. If it is less than 5 μm, carrier adhesion to the photoconductor tends to occur, and if it exceeds 100 μm, the magnetic brush at the developing pole becomes rough and a high quality image cannot be obtained. The particle size of the carrier of the present invention was randomly extracted by 300 or more with an optical microscope, and the horizontal particle size was measured as the carrier particle size by an image processing analyzer Luzex3 manufactured by Nireco.

The bulk density of the carrier of the present invention is 3.0 g /
cm ³ or less is preferable. When it exceeds 3.0 g / cm ³ , the centrifugal force applied to one carrier is large due to the rotation of the developing sleeve as compared with the force that the carrier is magnetically held on the sleeve, and carrier scattering easily occurs. The bulk density of the carrier of the present invention is measured according to JIS Z 250.
According to the method described in 4.

The sphericity of the carrier of the present invention is preferably 2 or less. When the sphericity of the carrier of the present invention exceeds 2, the carrier becomes inferior in fluidity as a developer, and the shape of the magnetic brush is deteriorated at the developing pole, so that a high quality image cannot be obtained. In addition, the sphericity of the carrier of the present invention was measured by using a field emission scanning electron microscope S-800 manufactured by Toshiba Corp. to randomly measure 300 carriers.
Image processing analyzer Luze made by Nireco
It was performed by using x3 to obtain the shape factor derived by the following equation.

[0045]

[Equation 5] MX LNG: maximum diameter of carrier AREA: projected area of carrier Here, the closer SF1 is to 1, the closer it is to a sphere.

The specific resistance of the carrier of the present invention is 10 ⁸ to 10
A range of ¹³ Ω · cm is suitable. When it is less than 10 ⁸ Ω · cm, in the developing method in which a bias voltage is applied, a current leaks from the sleeve to the surface of the photoconductor in the developing area, and a good image cannot be obtained. On the other hand, when it exceeds 10 ¹³ Ω · cm, a charge-up phenomenon is caused under a condition such as low humidity, which causes image deterioration such as density distortion, transfer failure, and fog. In the present invention, the measurement of the specific resistance is performed by
The measurement method as described above was used. That is, a method of determining the specific resistance by filling the cell A with a carrier, arranging the electrodes 1 and 2 so as to contact the filled carrier, applying a voltage between the electrodes, and measuring the current flowing at that time is described. Using.
In the above measuring method, since the carrier is a powder, the filling rate may change, and the specific resistance may change accordingly, which requires caution. The measurement condition of the specific resistance in the present invention is that the contact area S between the filled carrier and the electrode S is about 2.3c.
m ² , thickness d = about 1 mm, load 275 g of the upper electrode 2,
The applied voltage was 100V.

In order to achieve the above-mentioned magnetic characteristics, which are the main characteristics of the carrier of the present invention, metal oxide magnetic materials or iron-based alloys such as carbon steel, chromium steel, cobalt-chromium steel, and baicalloy. It is necessary to use Alnico alloy, etc. Preferably, it is made of ferrite, and the ferrite particles have a periodic table of IA, IIA, IIIA, I.
VA, VA, VIA, IB, IIB, IVB, VB, V
A carrier containing at least one element selected from the group consisting of IB, VIIB and VIII and containing less than 1% by weight of other elements can be used. Here, if other elements enter, it becomes difficult to obtain a carrier exhibiting the desired magnetic characteristics of the present invention, and further, the resistance tends to decrease, which is not preferable.

Further, the carrier of the present invention is a spinel structure single phase, a magnet plumbite structure single phase, a composite phase having at least a spinel structure or a magnet planvite structure, and a composite phase of a spinel structure and a magnet planvite structure. At this time, the molar ratio of the spinel phase and the magnetplumbite phase is preferably 1: 1 to 10: 1. Further, it is preferable that the magnetic particles having the spinel structure and the magnet prambite structure do not react much with each other.

By taking such a composition form, the magnetization intensity (σ ₁₀₀₀ ) at 1000 Oersted after magnetically saturated is 30 to 150 emu / cm ³ , and the residual magnetization σr is 25 emu / cm ³ or more. Therefore, it is possible to obtain a carrier having a magnetic property with a coercive force of less than 300 Oersted.

In the present invention, the crystals constituting the carrier were measured by the X-ray diffraction method and the fluorescent X-ray.

The carrier of the present invention can be manufactured by a manufacturing method such as a sintering method or an atomizing method, and if necessary, by mixing and sintering two or more kinds of crystal fine powders, the carrier of the present invention can be manufactured. It is also possible to manufacture carriers with magnetic properties.

Further, the carrier of the present invention, after being magnetically saturated, can easily achieve the characteristic magnetic characteristics of the present invention. As a method of magnetic saturation, there is a method of exposing carrier particles to a magnetic field of ± 10 kilo Oersted with a DC electromagnet.

Further, the carrier of the present invention is used for controlling the specific resistance and improving durability as described above.
The surface of the carrier particles may be coated with an arbitrary resin, if necessary. As the coating resin, a known appropriate resin can be used, and for example, an acrylic resin, a fluorine resin, a silicon resin, an epoxy resin or the like can be used for coating.

On the other hand, in order to obtain a toner having excellent fixability, which is another object of the present invention, at least one of the molecular weight distribution peaks by GPC of the resin component constituting the toner is 5,000 to 50,000. It has been found that it is effective to have at least one polar component in the resin component which is within the range and constitutes the toner.

That is, by adding a resin having a good affinity with paper, the adhesiveness with paper is further increased.

It has also been found that the above toner is a toner directly obtained by the suspension polymerization method, which is preferable as a means for achieving the object of the present invention.

It is considered that the polar component internally added is more likely to be present on the toner surface in the case of production in an aqueous system, and therefore one of the objects of the present invention can be achieved more effectively.

GPC of resin component of toner of the present invention
At least one of the molecular weight distribution peaks by
When it exists in the range of 0 to 50,000, low-temperature fixability can be exhibited.

However, GPC of the resin component of the toner
When the peak of the molecular weight distribution is less than 5,000, the blocking resistance becomes poor, and when there is no peak in the range of the present invention and the peak exceeds 50,000, the low temperature fixability becomes poor. Becomes

More preferably, when the content of 100,000 or less is 50% or less, good fixing property can be exhibited.

In the present invention, the toner resin component THF
The molecular weight distribution of the chromatogram by GPC using (tetrahydrofuran) as a solvent is measured under the following conditions.

That is, the column is stabilized in a heat chamber at 40 ° C., THF as a solvent is caused to flow through the column at a flow rate of 1 ml per minute, and about 100 μl of a THF sample solution is injected for measurement. In measuring the molecular weight of the sample, the molecular weight distribution of the sample was calculated from the relationship between the logarithmic value and the count number of the calibration curve prepared from several kinds of monodisperse polystyrene standard samples. As a standard polystyrene sample for preparing a calibration curve, for example, a standard polystyrene sample having a molecular weight of about 10 ² to 10 ⁷ manufactured by Tosoh Corporation or Showa Denko Corporation is used, and it is appropriate to use a standard polystyrene sample of at least about 10 points. is there. An RI (refractive index) detector is used as the detector. It is preferable to combine a plurality of commercially available polystyrene gel columns, for example, Shodex GPC KF manufactured by Showa Denko KK
-801, 802, 803, 804, 805, 806
Combination of 807,800P and TSK manufactured by Tosoh Corporation
gel G1000H (H _XL ), G2000H
(H _XL ), G3000H (H _XL ), G4000H
(H _XL ), G5000H (H _XL ), G6000H
(H _XL ), G7000H (H _XL ), TSKguard
A combination of columns can be mentioned.

The sample is prepared as follows. Put the sample in THF, leave it for several hours, shake it well, mix well with THF (until the coalescence of the sample disappears), and leave still for 12 hours or more. At this time, the leaving time in THF should be 24 hours or more. Then, a sample-treated filter (pore size 0.45 to 0.5 μm, for example, Maisori Disc H-25-5 manufactured by Tosoh Corp., Excicro Disc 25CR manufactured by Gelman Science Japan Co., Ltd., etc. can be used), Use as a GPC sample. The sample concentration is adjusted so that the resin component is 0.5 to 5 mg / ml.

Further preferably, as the electrophotographic photosensitive member, the surface layer of the electrophotographic photosensitive member has a ratio of fluorine and / or silicon atoms to carbon atoms of F / C 0.01 to 1.00, Si / C 0.03 ~
It has been found that a higher quality image can be obtained by making it exist in the range of 1.00.

The reason for defining F / C and Si / C is that the object of the present invention is more achieved when the surface of the photoreceptor is combined with the present invention. That is, F and Si reduce the surface energy of the photoconductor and reduce the transferability and the adhesion. On the other hand, the presence of carbon atoms is to increase the surface energy. The present inventors have found that by defining this ratio, a toner composition having a large amount of polar components on the toner surface as in the present invention and having a strong adhesive force can have a structure with good transferability and no cleaning failure. .

Here, with respect to the toner of the present invention, F / C and Si / C of the surface layer of the photoreceptor are 0.01 and 0.03, respectively.
When it is less than the range, the surface energy of the photoreceptor is high and the transferability of the toner is deteriorated. On the other hand, when F / C and Si / C exceed 1.00 respectively, the coefficient of friction with the cleaning member decreases, and conversely, toner slips through and cleaning failure occurs.

An even more preferable constitution is that the surface layer in the electrophotographic photosensitive member of the present invention contains a polycarbonate, and even more preferably, the polycarbonate is synthesized from an asymmetric diol. . As a result, an electrophotographic photoreceptor having excellent durability characteristics and good productivity can be obtained. As a more preferable structure, it is desirable that the electrophotographic photosensitive member has a protective layer on the photosensitive layer and that the protective layer contains polycarbonate. This results in additional stability of durability characteristics.

As a more preferable constitution for achieving the object of the present invention, the ratio of fluorine and / or silicon atoms to oxygen atoms in the surface layer of the electrophotographic photosensitive member of the present invention is XPS.
In the measurement, it is preferably F / O 0.01 or more and Si / O 0.03 or more. By defining the amount of oxygen for F and Si as described above, it becomes possible to more preferably control the adhesiveness to the toner containing the resin having the polar component of the present invention.

In the XPS measuring method for the surface of the electrophotographic photosensitive member of the present invention, the XPS measuring device is V
It was performed using an ESCALAB, 200-X type, X-ray photoelectron spectrometer manufactured by G company. The measurement conditions were as follows: X-ray source MgKα (300W) analysis area 2 × 3 mm.

The constituent elements used in the toner of the developer of the present invention will be specifically exemplified below.

The resin containing a polar component in the toner used in the present invention includes a polymer of a nitrogen-containing monomer such as dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate or styrene / unsaturated carboxylic acid ester. Copolymers, nitrile monomers such as acrylonitrile, halogen-containing monomers such as vinyl chloride, unsaturated carboxylic acids such as acrylic acid and methacrylic acid, and other unsaturated dibasic acids and unsaturated dibasic anhydrides , A polymer such as a nitro monomer or a copolymer with a styrene monomer,
Examples thereof include polyester and epoxy resin.

The following method is used as a method of incorporating the polar component into the toner.

In the polymerized toner, as a polymer or a copolymer, it is dissolved in another monomer component and added by polymerizing it, or as a monomer, mixed with another monomer component, It can be added by polymerization.

Other polymerizable monomers that can be used in the polymerized toner of the present invention include styrene such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene. -Based monomers, methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic Acrylic acid esters such as 2-chloroethyl acid, phenyl acrylate, etc., methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, methacrylic acid Acid 2-ethylhexyl - monomers include methacrylic acid esters of phenyl methacrylate, stearyl methacrylate and the like. These monomers may be used alone or in combination. Among the above-mentioned monomers, it is preferable to use styrene or a styrene derivative alone or in combination with other monomers, from the viewpoint of developing characteristics and durability of the toner.

As the colorant used in the present invention, known colorants can be used. Examples thereof include carbon black and iron black, and C.I. I. Direct Red 1, C.I. I. Direct Red 4, C.I. I. Acid Red 1, C.I. I. Basic Red 1, C.I. I. Mordant Red 30, C.I.
I. Direct Blue 1, C.I. I. Direct Blue 2, C.I. I. Acid Blue 9, C.I. I. Acid Blue 15, C.I. I. Basic blue 3, C.I. I. Basic Blue 5, C.I. I. Modant Blue 7, C.I. I.
Direct Green 6, C.I. I. Basic green 4, C.I. I. Dyes such as Basic Green 6, Yellow Lead, Cadmium Yellow, Mineral Fast Yellow, Navel Yellow, Naphthol Yellow S, Hansa Yellow G, Permanent Yellow NCG, Tartrazine Lake, Molybdenum Orange, Permanent Orange GT
R, benzidine orange G, cadmium red, permanent red 4R, watching red calcium salt,
Brilliant Carmine 3B, Fast Violet B,
Pigments such as methyl violet lake, navy blue, cobalt blue, alkali blue lake, Victoria blue lake, quinacridone, rhodamine lake, phthalocyanine blue, fast sky blue, pigment green B, malachite green lake, and final yellow green G are available. In the present invention, since the toner is obtained by using the polymerization method, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the colorant. It is better to apply chemical treatment. In particular, since many dyes and carbon black have a polymerization inhibitory property, caution is required when using them. A preferred method of surface-treating a dye system is a method of polymerizing a polymerizable monomer in the presence of these dyes in advance, and the obtained colored polymer is added to the monomer system. In addition to carbon black, the carbon black may be treated with a substance that reacts with the surface functional groups of carbon black, such as polyorganosiloxane.

When the toner is used as a magnetic toner, it may contain magnetic powder. As such magnetic powder, a substance that is magnetized when placed in a magnetic field is used.
There are powders of ferromagnetic metals such as iron, cobalt and nickel, and compounds such as magnetite and ferrite. In particular, in the present invention, since a toner is obtained by using a polymerization method, it is necessary to pay attention to the polymerization inhibitory property and the water phase transfer property of the magnetic material, and preferably surface modification, for example, there is no polymerization inhibitory property. It is better to give a hydrophobic treatment with a substance.

In the present invention, for the purpose of improving the releasability at the time of heat roll fixing, waxes generally used as a releasing agent such as a hydrocarbon compound may be added to the toner. The waxes used in the present invention include paraffin / polyolefin wax and modified products thereof,
For example, in addition to oxides and graft-treated products, higher fatty acids and their metal salts, amide waxes, ester waxes such as alcohol compounds having tertiary or / and quaternary carbons and having two or more functional groups, or carvone. A polyfunctional polyester compound obtained from an acid compound, having a primary or / and secondary carbon, a polyfunctional polyester compound obtained from a difunctional or higher functional alcohol compound or a carboxylic acid compound, and a tertiary or / and quaternary carbon However, monofunctional ester compounds and the like can be mentioned. These waxes have a softening point of 40 to 13 according to the ring and ball method (JIS K 2531).
Those having a temperature of 0 ° C., preferably 50 to 120 ° C. are desirable. If the softening point is less than 40 ° C., the blocking resistance and shape retention of the toner are insufficient, and if it exceeds 130 ° C., the effect of releasability is insufficient. Becomes

These releasing agents may be used alone or in combination, and the addition amount is preferably 0.1 to 50% by weight.

In the present invention, it is desirable to add a charge control agent to the toner material in order to control the chargeability of the toner. As these charge control agents, among known ones, those having almost no polymerization inhibitory property / water phase transfer property are used. For example, as positive charge control agents, nigrosine dyes, triphenylmethane dyes, quaternary ammonium salts, guanidines are used. Derivatives, imidazole derivatives, amine-based and polyamine-based compounds, and the like. As a negative charge control agent, metal-containing salicylic acid-based compounds, metal-containing monoazo-based dye compounds, urea derivatives, styrene-acrylic acid copolymers, styrene-methacrylic Examples thereof include acid copolymers.

The addition amount of these charge control agents is 0.
1 to 10% by weight is preferable.

As the polymerization initiator, any suitable polymerization initiator, for example, 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1, 1'-azobis (cyclohexane-1-
Carbonitrile), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobis or diazo polymerization initiators such as azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide,
Examples thereof include peroxide-based polymerization initiators such as diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide and lauroyl peroxide. These polymerization initiators are preferably added in an amount of 0.5 to 20% by weight of the polymerizable monomer, and may be used alone or in combination.

In the present invention, a known crosslinking agent or chain transfer agent may be added in order to control the molecular weight, and the preferable addition amount is 0.001 to 15% by weight.
Is.

As an additive for imparting various toner characteristics, from the viewpoint of durability in the toner or when added to the toner, the particle diameter is 1/10 or less of the volume average diameter of the toner particles. Is preferred. What is the particle size of this additive?
It means the average particle size of the toner particles obtained by observing the surface of the toner particles with an electron microscope. As the additives for imparting these characteristics, for example, the following ones are used.

1) Flowability-imparting agents: metal oxides (silicon oxide, aluminum oxide, titanium oxide, etc.), carbon black, fluorinated carbon, etc. Those subjected to a hydrophobic treatment are more preferable.

2) Abrasive: Metal oxide (strontium titanate, cerium oxide, aluminum oxide, magnesium oxide, chromium oxide, etc.), nitride (silicon nitride, etc.), carbide (silicon carbide, etc.), metal salt (calcium sulfate, etc.) , Barium sulfate, calcium carbonate, etc.).

3) Lubricants: Fluorine-based resin powders (vinylidene fluoride, polytetrafluoroethylene, etc.), fatty acid metal salts (zinc stearate, calcium stearate, etc.), etc.

4) Charge controllable particles: metal oxides (tin oxide, titanium oxide, zinc oxide, silicon oxide, aluminum oxide, etc.), carbon black, etc.

These additives are used in an amount of 0.1 to 10 parts by weight, preferably 0.1 to 5 parts by weight, based on 100 parts by weight of toner particles. These additives are
They may be used alone or in combination.

Any suitable stabilizer is used for the dispersion medium used in the polymerization method of the present invention. For example, as an inorganic compound, tricalcium phosphate, magnesium phosphate, aluminum phosphate, zinc phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, calcium sulfate, barium sulfate. , Bentonite, silica, alumina and the like. As organic compounds, polyvinyl alcohol, gelatin, methyl cellulose, methyl hydroxypropyl cellulose, ethyl cellulose,
Sodium salt of carboxymethyl cellulose, polyacrylic acid and its salt, starch and the like can be used by dispersing in an aqueous phase. It is preferable to use 0.2 to 20 parts by weight of these stabilizers with respect to 100 parts by weight of the polymerizable monomer.

When an inorganic compound is used among these stabilizers, a commercially available product may be used as it is, but the inorganic compound may be produced in a dispersion medium in order to obtain fine particles. For example, in the case of tricalcium phosphate, it is advisable to mix the sodium phosphate aqueous solution and the calcium chloride aqueous solution under high stirring.

For fine dispersion of these stabilizers, 0.001 to 0.1 part by weight of a surfactant may be used. This is to promote the desired action of the above dispersion stabilizer, and specific examples thereof include sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, and sodium octyl sulfate.
Examples thereof include sodium oleate, sodium laurate, potassium stearate, calcium oleate and the like.

The polymerized toner used in the present invention is obtained by the following method. That is, the release agent in the polymerizable monomer
A monomer system in which a colorant, a charge control agent, a polymerization initiator, and other additives are added, and the mixture is uniformly dissolved or dispersed by a homogenizer or an ultrasonic disperser is usually stirred in an aqueous phase containing a dispersion stabilizer. Disperse using a machine or homomixer / homogenizer. Granulation is preferably carried out by adjusting the stirring speed and time so that the monomer droplets have a desired toner particle size, generally 30 μm or less. After that, stirring may be performed to the extent that the particle state is maintained and the particles are prevented from settling due to the action of the dispersion stabilizer. The polymerization temperature is set to 40 ° C. or higher, generally 50 to 90 ° C. to carry out the polymerization. In addition, the temperature may be raised in the latter half of the polymerization reaction, and further in the latter half of the reaction or the end of the reaction in order to remove unreacted polymerizable monomers and by-products that may cause odor during toner fixing. The aqueous medium may be partially distilled off later. After the reaction is completed, the produced toner particles are collected by washing and filtration and dried. In the suspension polymerization method, it is usually preferable to use 300 to 3000 parts by weight of water as a dispersion medium with respect to 100 parts by weight of the monomer system.

The constitution of the electrophotographic photosensitive member used in the present invention is shown below.

The photoconductor of the present invention has a laminated structure having a charge generation layer and a charge transport layer on a conductive substrate. Further, in the present invention, a structure in which a protective layer is provided on the charge transport layer may be used.

In the present invention, the charge transport layer and / or the protective layer, which is the surface layer of the photoreceptor, contains a fluorine compound and / or a fluorine compound.
Alternatively, it is characterized by containing a silicon compound. Furthermore, as a means for more effectively achieving the object of the present invention, it is preferable to include polycarbonate in the charge transport layer and / or the protective layer. Further, in the present invention, it is preferable that the polycarbonate contains a polycarbonate synthesized by using an asymmetric diol.

The materials used for the photoconductor of the present invention are exemplified below.

Specific examples of the fluorine-based compound include known fluororesins, such as tetrafluoroethylene, trifluoroethylene chloride, tetrafluoroethylene, hexafluoropropylene,
One or more kinds are appropriately selected from vinyl fluoride, vinylidene fluoride, ethylene difluoride dichloride and copolymers thereof. Further, carbon fluoride or the like can also be used.

In the present invention, a block or graft polymer containing a fluorine-containing segment, which is synthesized by polymerization / copolymerization with a fluorine-containing polymerizable monomer or a non-fluorine-containing polymerizable monomer, a surfactant, a macromolecule. The monomers and the like can be used alone or in combination with the above-mentioned fluororesins.

In particular, the combined use with a fluorine-based graft polymer having continuous fluorine-based segments is preferable from the viewpoint of facilitating the dispersion of the fluorine-based resin and the control of the surface F / C ratio which is a feature of the present invention.

Preferred specific examples of the above-mentioned fluorine-based polymerizable monomer are shown below, but the range of compounds that can be used is not limited to the range given here.

[0101]

[Chemical 1]

(In the above compounds, R ₁ represents a hydrogen atom, a halogen atom or a methyl group, R ₂ represents a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group or a nitrile group, and a combination of several kinds thereof may be used. Is an integer of 1 to 4, m is an integer of 1 to 5, k + m = 5, and Rf
Represents an alkyl group substituted with at least one fluorine atom. ) Examples of the non-fluorine-based polymerizable monomer include low molecular weight linear unsaturated hydrocarbons, vinyl halides, vinyl esters of organic acids, vinyl aromatic compounds, acrylic acid and methacrylic acid esters, N-vinyl compounds, One or more of vinyl silicon compounds, maleic anhydride, esters of maleic acid and fumaric acid can be used, and the formed fluorine-based graft polymer is added to the charge transport layer and / or It is preferable to select one that is compatible with the resin layer of the protective layer, or that has a similar structure even if it is not completely compatible and that has a slight affinity between the two.

Specific examples of the silicon compound include monomethylsiloxane three-dimensional crosslinked products and dimethylsiloxane-
A monomethylsiloxane three-dimensional crosslinked product, an ultrahigh molecular weight polydimethylsiloxane, a block polymer containing a polydimethylsiloxane segment, a graft polymer, a surfactant, a macromonomer, a terminal-modified polydimethylsiloxane, etc. are used. In the case of a three-dimensional crosslinked product, the particle size used in the form of fine particles can be used in the range of 0.01 to 5 μm. In the case of a polydimethylsiloxane compound, its molecular weight can be used in the range of 3,000 to 5,000,000. The fine particles are dispersed as a photosensitive layer composition together with a binder resin. As a dispersing method, a sand mill, a ball mill, a roll mill, a homogenizer, a nanomizer, a paint shaker, an ultrasonic wave or the like is used. At the time of dispersion, it is preferable to use the above-mentioned graft, block polymer or surfactant as a dispersion aid, and it is also preferable to use them in combination for controlling the Si / C ratio which is a feature of the present invention.

The aromatic hydrocarbon solvent-soluble or halogenated aromatic hydrocarbon-based polycarbonate used in the charge transport layer and / or protective layer of the present invention can be obtained by reducing the crystallinity. Specifically, for example, 1) bisphenol A and one or more asymmetric diol compounds 2) One or more asymmetric diol compounds can be obtained by a general polycarbonate synthesis method such as the phosgene method. it can. It can also be obtained by using a diol compound having a side chain with a substituent having 3 or more carbon atoms.

Typical specific examples of the asymmetric diol compound used in the present invention are shown below, but the present invention is not limited thereto.

[0106]

[Chemical 2]

[0107]

[Chemical 3]

[0108]

[Chemical 4]

[0109]

[Chemical 5]

[0110]

[Chemical 6]

The ratio of the asymmetric diol compound in the above-mentioned copolymerized polycarbonate with bisphenol A is preferably 20% by weight or more, and particularly preferably 50% by weight or more in the diol compound. 20% by weight of asymmetric diol compound
When it is less than, solubility in an aromatic hydrocarbon solvent or a halogenated aromatic hydrocarbon solvent becomes insufficient,
The stability of the coating liquid over time also deteriorates. Solubility of polycarbonate soluble in the above-mentioned aromatic hydrocarbon solvent or halogenated aromatic hydrocarbon solvent (solution 10 at a temperature of 25 ° C.
The number of g of polycarbonate in 0 g) is 1 g or more, especially 5
It is preferably g or more. When the solubility is less than 1 g, for example, when the coating solution for the charge transport layer is prepared, the viscosity of the coating solution is too low to obtain an appropriate film thickness required for the charge transport layer.

The effect of the polycarbonate used in the present invention can be enhanced particularly when it is used as a binder resin for the charge generation layer or the charge transport layer.

Examples of the aromatic hydrocarbon solvent include benzene, toluene and xylene, and examples of the halogenated aromatic hydrocarbon solvent include monochlorobenzene and dichlorobenzene.

When producing the electrophotographic photosensitive member of the present invention,
As the conductive substrate, a metal such as aluminum or stainless steel, a cylindrical cylinder such as paper or plastic, or a film is used. An undercoat layer (adhesive layer) having a barrier function and an undercoat function can be provided on these substrates.

The subbing layer is for improving the adhesion of the photosensitive layer, improving the coating property, protecting the substrate, covering defects on the substrate, improving the charge injection property from the substrate, protecting the photosensitive layer against electrical breakdown, etc. It is formed. Known materials for the subbing layer include polyvinyl alcohol, poly-N-vinylimidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, casein, polyamide, copolymerized nylon, glue and gelatin. These are dissolved in a solvent suitable for each and coated on the substrate. The film thickness is about 0.2 to 2 μm.

In the function-separated type photoreceptor, selenium-tellurium, pyrylium, thiapyrylium dyes, phthalocyanine pigments, anthanthrone pigments, dibenzpyrenequinone pigments, pyranthrone pigments, trisazo pigments, diazo pigments, azo pigments are used as charge generating substances. , Indigo pigment,
A quinacridone pigment, an asymmetric quinocyanine, a quinocyanine, or amorphous silicon described in JP-A-54-143645 can be used, and as the charge-transporting substance, pyrene, N-ethylcarbazole, N-
Isopropylcarbazole, N-methyl-N-phenylhydrazino-3-methylidene-9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-
9-ethylcarbazole, N, N-diphenylhydrazino-3-methylidene-10-ethylphenothiazine,
N, N-diphenylhydrazino-3-methylidene-10
-Ethylphenoxazine, P-diethylaminobenzaldehyde-N, N-diphenylhydrazone, P-diethylaminobenzaldehyde-N-α-naphthyl-N-phenylhydrazone, P-pyrrolidinobenzaldehyde-
Hydrazones such as N, N-diphenylhydrazone, 1,3,3-tramethylindolenine-ω-aldehyde-N, N-diphenylhydrazone, P-diethylbenzaldehyde-3-methylbenzthiazolinone-2-hydrazone, 2,5-bis (P-diethylaminophenyl)-
1,3,4-oxadiazole, 1-phenyl-3-
(P-Diethylaminostyryl) -5- (P-diethylaminophenyl) pyrazoline, 1- [quinolyl (2)]
-3- (P-diethylaminostyryl) -5- (P-diethylaminophenyl) pyrazoline, 1 [pyridyl (2)]-3- (P-diertiaminostyryl) -5-
(P-diethylaminophenyl) pyrazoline, 1- [6
-Methoxy-pyridyl (2)]-3- (P-diethylaminostyryl) -5- (P-diethylaminophenyl)
Pyrazoline, 1- [pyridyl (3)]-3- (P-diethylaminostyryl) -5- (P-diethylaminophenyl) pyrazoline, 1- [lepidyl (2)]-3- (P
-Diethylaminostyryl) -5- (P-diethylaminophenyl) pyrazoline, 1- [pyridyl (2)]-3
-3 (P-diethylaminostyryl) -4-methyl-5
-(P-diethylaminophenyl) pyrazoline, 1-
[Pyridyl (2)]-3- (α-methyl-P-diethylaminostyryl) -5- (P-diethylaminophenyl) pyrazoline, 1-phenyl-3- (P-diethylaminostyryl) -4-methyl-5- ( P-Diethylaminophenyl) pyrazoline, 1-phenyl-3- (α-benzyl-P-diethylaminostyryl) -5- (P-diethylaminophenyl) pyrazoline, pyrazolines such as spiropyrazoline, 2- (P-diethylaminostyryl) -6 -Diethylaminobenzoxazole, 2-
Oxazole compounds such as (P-diethylaminophenyl) -4- (P-dimethylaminophenyl) -5- (2-chlorophenyl) oxazole, thiazole compounds such as 2- (P-diethylaminostyryl) -6-diethylaminobenzothiazole , Bis (4-diethylamino-2-methylphenyl) -phenylmethane and other triarylmethane compounds, 1,1-bis (4-N, N-diethylamino-2-methylphenyl) heptane, 1,1,
2,2-Tetrakis- (4-N, N-dimethylamino-
Polyarylalkanes such as 2-methylphenyl) ethane can be used.

The charge generating layer contains the above charge generating pigment in an amount of 0.
It is formed by well dispersing with a binder resin and a solvent in an amount of 3 to 4 times and a solvent by a method such as a homogenizer, ultrasonic wave, ball mill, vibrating ball mill, sand mill, attritor, or roll mill, and coating and drying. Its thickness is 0.1
It is about 1 μm.

When the above-mentioned polycarbonate resin is used for the charge generation layer, the charge generation substance is dissolved together with the polycarbonate in an aromatic hydrocarbon solvent or a halogenated aromatic hydrocarbon solvent alone or in a mixed solvent thereof, or It is formed by applying a coating liquid obtained by dispersing a charge generating substance to a solution obtained by dissolving the above polycarbonate resin in the above solvent. The proportion of the charge generating material in the charge generating layer can be 30% by weight or more, preferably 80% by weight or more. As the solvent, toluene,
Xylene or monochlorobenzene are particularly useful. As a method of applying this coating solution, for example, a dip coating method, a spray coating method, a spinner coating method, a curtain coating method or the like can be used.

When the above-mentioned polycarbonate resin is used for the charge-transporting layer, the charge-transporting substance and the above-mentioned polycarbonate are used as the above-mentioned aromatic hydrocarbon solvent or halogenated aromatic hydrocarbon solvent alone or in a mixed solvent thereof. It is obtained by applying a coating solution prepared by dissolving. The charge transport material and the above-mentioned polycarbonate resin used as the binder are mixed in a weight ratio of 2: 1 to 1: 2.
It is a degree. Toluene, xylene or monochlorobenzene are particularly useful as the solvent.

As a method for applying this solution, for example, a dip coating method, a spray coating method, a spinner coating method, a curtain coating method and the like are known. The dip coating method is the best for efficient and accurate mass production of electrophotographic photoreceptors, and the pot life in the dip coating method can be greatly improved by using the above-mentioned polycarbonate. The productivity of manufacturing using the coating method can be significantly improved. After coating and forming the charge transport layer, 10 ° C to 200 ° C (preferably 20 ° C to 150 ° C)
At a temperature of 5 minutes to 5 hours (preferably 10 minutes to 2 hours) by blast drying or static drying, 5 to 20 μm
Of the charge transport layer is obtained.

[0121]

The present invention will be described below with reference to examples.
These do not limit the invention in any way. The toner, carrier, and drum manufacturing examples, physical property tables, and evaluation methods used in Examples and Comparative Examples of the present invention are listed below.

[Production Example A of Polymerized Toner] Ion-exchanged water 7
To 10 g, was charged 0.1M-Na ₃ PO ₄ aqueous solution 450 g, followed by heating to 60 ° C., using a TK-type homomixer (manufactured by Tokushu Kika Kogyo), and stirred at 12000 rpm. 68 g of 1.0 M-CaCl ₂ aqueous solution was gradually added to this to obtain an aqueous medium containing Ca ₃ (PO ₄ ) ₂ .

On the other hand, styrene 165 g n-butyl acrylate 35 g phthalocyanine pigment 10 g di-t-butyl salicylate metal compound 1 g styrene-methacrylic acid copolymer (molar ratio 95: 5, Mw 50,000) 10 g paraffin wax (mp 70) ℃) 40g

The above formulation was heated to 60 ° C., and 12000 rpm was obtained using a TK homomixer (made by Tokushu Kika Kogyo).
Were uniformly dissolved and dispersed. In addition to this, the polymerization initiator 2,
2'-azobis (2,4-dimethylvaleronitrile) 1
0 g was dissolved to prepare a polymerizable monomer composition. The polymerizable monomer composition was added to the aqueous medium, and the temperature was 60 ° C.
100 in a TK homomixer under N ₂ atmosphere
The polymerizable monomer composition was granulated by stirring at 00 rpm for 20 minutes. Then, while stirring with a paddle stirring blade, the temperature was raised to 80 ° C. and the reaction was performed for 10 hours.

After completion of the polymerization reaction, a part of the aqueous medium was distilled off under reduced pressure, the mixture was cooled, hydrochloric acid was added to dissolve calcium phosphate, and the mixture was filtered, washed with water and dried to give a weight average diameter of about 8 μm.
m sharp colored suspended particles were obtained.

BE was added to 100 parts by weight of the obtained particles.
0.8 parts by weight of hydrophobic silica having a specific surface area according to the T method of 200 m ² / g was externally added to obtain a suspension-polymerized toner.

[Polymerized Toner Production Example B] According to Production Example A, except that the phthalocyanine pigment as the colorant of Production Example A was changed to carbon black and the paraffin wax as the release agent was changed to the ester wax having the following structural formula. A polymerized toner B was obtained.

[0128]

[Chemical 7]

[Polymerized Toner Production Examples C and D] Polymerized toners C and D having different molecular weight distribution peaks were obtained by adjusting the amount of polymerization initiator and the polymerization temperature according to Production Example A.

Table 1 shows the physical properties of Polymerized Toners A to D.

[0131]

[Table 1]

With respect to Toner C, some blocking occurred during drying during the manufacturing process, and it was not evaluated.

[Production Example A of Carrier] In molar ratio, Fe ₂ O
₃ = 60 mol%, CuO = 20 mol%, ZnO = 20 mol%, while Fe ₂ O ₃ = 82 mol%, SrCO ₃ = 10 mol%, ZnO = 8 mol% Were weighed and mixed using a ball mill. After calcination of each of these, pulverization is performed with a ball mill, the above formulations are mixed at a ratio of 2: 1 respectively, polyvinyl alcohol, a defoaming agent and a dispersant are added to form a slurry, and granulation drying is performed using a spray dryer. Then, sintering was performed. Further classification results in an average particle size of 55 μm
To obtain carrier particles. The shape of the carrier obtained at that time was almost spherical. In addition, X-ray diffraction and fluorescence X
As a result of the line analysis, the ratio of the spinel phase (Cu-Zn-ferrite) and the magnet plumbundite phase (Sr ferrite) was 2: 1 which was almost the same as the charged amount. The bulk density was 2.32 g / cm ³ . Also, the resistance of the carrier particles was measured to be 6.2 × 10 ⁹ Ω
・ It was cm. After saturating this carrier with a magnetic field of 10 kilo Oersted, magnetic measurement was performed. As a result, the magnetic characteristics were σ ₁₀₀₀ = 142 emu / cm ³ , σr
= 104 emu / cm ³ , σ ₃₀₀ = 122 emu / cm
³ , Hc = 260 oersted. At that time,
It was (sigma) _{1000- (} sigma) ₃₀₀ | / (sigma) ₁₀₀₀ = 0.14.

Further, the surface of this carrier was coated with a styrene-2-ethylhexyl methacrylate (45/55) copolymer by a fluidized bed coating method. The specific resistance of the carrier at that time was 9.5 × 10 ¹² Ω · cm.

[Production Example B of carrier] In molar ratio, Fe ₂ O
₃ = 50 mol%, CuO = 20 mol%, ZnO = 30 mol%, while Fe ₂ O ₃ = 85 mol%, BaO = 12 mol%, ZnO = 3 mol% Weighed and mixed using a ball mill.
After calcination of each of these, the mixture was pulverized with a ball mill, the above formulations were mixed at a ratio of 1.5: 1, polyvinyl alcohol, an antifoaming agent and a dispersant were added to form a slurry, which was then produced using a spira coater. The particles were dried and sintered. Further classification was performed to obtain carrier particles having an average particle size of 45 μm. The shape of the carrier obtained at that time was almost spherical. As a result of X-ray diffraction measurement and fluorescent X-ray measurement, the spinel phase and the magnet-plumbite phase (B
The ratio with (a ferrite) is almost the same as the charged amount (1.
6: 1). The bulk density is 2.30 g / cm.
^{Was 3} . Further, the resistance of the carrier particles was measured and found to be 9.2 × 10 ⁹ Ω · cm. After saturating this carrier with a magnetic field of 10 kilo Oersted, magnetic measurement was carried out. As a result, the magnetic characteristic was σ ₁₀₀₀ = 67e.
mu / cm ³ , σr = 36 emu / cm ³ , σ ₃₀₀ = 5
It was 2 emu / cm ³ and Hc = 170 oersted. At that time, | σ ₁₀₀₀ −σ ₃₀₀ | / σ ₁₀₀₀ = 0.22
Met.

The surface of the obtained carrier was coated in the same manner as in Carrier Production Example A. The specific resistance of the carrier at this time was 1.3 × 10 ¹² Ω · cm.

[Manufacturing example C of carrier] In molar ratio, Fe = 6
1 mol%, Al = 9 mol%, Ni = 15 mol%, Co =
It was mixed so as to have a content of 15 mol%, and carrier particles were obtained from the melt by a water atomizing method. The obtained carrier was heat-treated and further classified by an air classifier to obtain carrier particles having an average particle size of 42 μm. The shape of the carrier obtained at that time was almost spherical. The bulk density was 2.96 g / cm ³ . Further, the resistance of the carrier particles was measured and found to be 2 × 10 ⁹ Ω · cm. As a result of magnetic measurement of this carrier, the magnetic characteristics at that time were σ ₁₀₀₀ = 89 emu / cm ³ and σr = 37.
emu / cm ³ , σ ₃₀₀ = 60 emu / cm ³ , Hc =
It was 165 Oersted. At that time, | σ ₁₀₀₀ −σ
_{It was 300} | / (sigma) ₁₀₀₀ = 0.33.

The obtained carrier was coated with the resin used in Carrier Production Example A in the same manner as in Carrier Production Example A.
The specific resistance of the carrier obtained at this time is 2 × 10 ⁹ Ω ・
It was cm.

[Manufacturing Example D of Carrier] In molar ratio, Fe ₂ O
₃ = 85 mol% and SrCO ₃ = 15 mol% were weighed and mixed using a ball mill. The mixed powder was calcined and then pulverized. The crushed sample was made into a slurry, and the slurry was granulated with a spray dryer to sinter the granulated powder. The obtained sintered powder was classified by an air classifier to obtain carrier particles having an average particle size of 59 μm. The shape of the carrier obtained at that time was almost spherical. The bulk density was 2.01 g / cm ³ .
The specific resistance of the carrier particles was measured to be 9.5.
It was × 10 ⁸ Ω · cm. As a result of magnetic measurement of this carrier in a magnetic field of 10 kilo Oersted, the magnetic characteristics at that time were σ ₁₀₀₀ = 101 emu / cm ³ , σ
r = 76 emu / cm ³ , σ ₃₀₀ = 89 emu / cm
³ , Hc = 2040 Oersted. then,
It was | (sigma) _1000- (sigma) ₃₀₀ | / (sigma) ₁₀₀₀ = 0.12.

The surface of the obtained carrier was coated in the same manner as in Carrier Production Example A. The specific resistance of the carrier at this time was 3.5 × 10 ¹² Ω · cm.

[Carrier Production Example E] Carrier Production Example A except that the mixing ratio of the spinel phase (Cu-Zn-ferrite) and the magnet planvite phase (Sr ferrite) used in Carrier Production Example A was changed to 1: 2. Similarly, a carrier was prepared to obtain carrier particles having an average particle size of 52 μm.
The shape of the carrier obtained at that time was almost spherical. In addition, as a result of X-ray diffraction and fluorescent X-ray analysis, the ratio of the spinel phase (Cu-Zn-ferrite) to the magnet plumbundite phase (Sr ferrite) was 1: 2, which was almost the same as the charged amount. It was The bulk density is 2.07 g.
/ Cm ³ . Further, the resistance of the carrier particles was measured and found to be 5.1 × 10 ⁹ Ω · cm. After saturating this carrier with a magnetic field of 10 kilo Oersted, magnetic measurement was performed, and the magnetic characteristics at that time were σ ₁₀₀₀ =
117 emu / cm ³ , σr = 94 emu / cm ³ , σ
_{It was 300} = 106 emu / cm ³ and Hc = 1090 oersted. At that time, | σ ₁₀₀₀ −σ ₃₀₀ | / σ ₁₀₀₀
= 0.09.

The surface of the obtained carrier was coated in the same manner as in Carrier Production Example A. The specific resistance of the carrier at this time was 7.5 × 10 ¹² Ω · cm.

[Production Example F of carrier] The molar ratio of Fe ₂ O
₃ = 62 mol%, ZnO = 16 mol%, CuO = 22 mol% were weighed and mixed using a ball mill. In the same manner as in Carrier Production Example D, carrier particles having an average particle diameter of 50 μm were obtained. The shape of the carrier obtained at that time was almost spherical. The bulk density is
It was 2.77 g / cm ³ . The resistance of the carrier particles was measured and found to be 4.0 × 10 ⁹ Ω · cm. As a result of magnetic measurement of this carrier in a magnetic field of 10 kilo Oersted, the magnetic characteristic at that time is σ
₁₀₀₀ = 214 emu / cm ³ , σr = 2 emu / cm
³ , σ ₃₀₀ = 113 emu / cm ³ , and Hc = 10 oersted. At that time, | σ ₁₀₀₀ −σ ₃₀₀ | / σ
It was ₁₀₀₀ = 0.47.

The surface of the obtained carrier was coated in the same manner as in Carrier Production Example A. The specific resistance of the carrier at this time was 3.2 × 10 ¹² Ω · cm.

[Carrier Production Example G] The molar ratio of Fe ₂ O
₃ = 60 mol%, SrCO ₃ = 3 mol%, ZnO = 21
Mol% and CuO = 16 mol% were weighed and mixed using a ball mill. This is Carrier Production Example D
Similarly to the above, carrier particles having an average particle diameter of 52 μm were obtained. The shape of the carrier obtained at that time was almost spherical. As a result of the X-ray diffraction measurement and the fluorescent X-ray measurement, the molar ratio of the spinel phase (Cu-Zn ferrite) and the magnet prambitite phase (Sr ferrite) was about 15: 1. The bulk density was 2.32 g / cm ³ . Moreover, when the resistance of the carrier particles was measured, it was 1 ×
It was 10 ⁹ Ω · cm. As a result of magnetic measurement of this carrier, the magnetic characteristic at that time is σ ₁₀₀₀ = 58 emu
/ Cm ³ , σr = 6 emu / cm ³ , σ ₃₀₀ = 20 em
It was u / cm ³ and Hc = 60 oersted. At that time, | σ ₁₀₀₀ −σ ₃₀₀ | / σ ₁₀₀₀ = 0.66.

The surface of the obtained carrier was coated in the same manner as in Carrier Production Example A. The specific resistance of the carrier at this time was 1.5 × 10 ¹² Ω · cm.

Table 2 shows the physical properties of the carriers A to G.

[0148]

[Table 2]

[Production Example A] 10 parts by weight of conductive titanium oxide (tin oxide coat, average primary particle size 0.4 μm), 10 parts by weight of phenol resin precursor (resole type), 10 parts by weight of methanol, and 10 parts by weight of butanol. Was dispersed in a sand mill, dip-coated in an aluminum cylinder having an outer diameter of 80 mm and a length of 360 mm and cured at 140 ° C., and then a conductive layer having a volume resistance of 5 × 10 ⁹ Ωcm and a thickness of 20 μm was provided.

Next, 10 parts by weight of the following methoxymethylated nylon (the degree of methoxymethylation is about 30%):

[0151]

[Chemical 8]

Then, 150 parts by weight of isopropanol and 150 parts by weight of isopropanol were mixed and dissolved, and then dip-coated on the conductive layer to form an undercoat layer of 1 μm.

Next, 10 parts by weight of the following azo pigment,

[0154]

[Chemical 9]

5 parts by weight of the following polycarbonate resin (bisphenol A molecular weight 30,000):

[0156]

[Chemical 10]

Then, 700 parts by weight of cyclohexanone was dispersed by a sand mill, and the dispersion was dip-coated on the undercoat layer to obtain a charge generation layer of 0.05 μm.

Next, 10 parts by weight of the following triphenylamine,

[0159]

[Chemical 11]

10 parts by weight of a polycarbonate resin having the following structure (bisphenol Z type, molecular weight 20000)

[0161]

[Chemical 12]

50 parts by weight of monochlorobenzene and 15 parts by weight of dichloromethane were mixed by stirring, and then dip-coated on the charge generation layer. The coated cylinder was dried with hot air to form a 20 μm charge transport layer.

Next, 1 part by weight of carbon fluoride fine powder (average particle size 0.23 μm, manufactured by Central Glass Co., Ltd.) and the following polycarbonate resin (bisphenol Z molecular weight 80
000) 6 parts by weight,

[0164]

[Chemical 13]

The following perfluoroalkyl acrylate-
Methyl methacrylate block copolymer (molecular weight 300
00) 0.1 parts by weight

[0166]

[Chemical 14]

120 parts by weight of monochlorobenzene and 80 parts by weight of dichloromethane were dispersed and mixed in a sand mill. And 3 parts by weight of the following triphenylamine

[0168]

[Chemical 15] Was mixed and dissolved, and was applied on the charge transport layer by spray coating to provide a protective layer of 5 μm to obtain a photosensitive drum.

<F / C Ratio XPS Measurement> After peeling off the surface of the photoreceptor, ESCALAB200-X type manufactured by VG.
The surface elements were fixed by an X-ray photoelectron spectrometer. Using MgCa (300 W) as an X-ray source, measurement was carried out at a depth of several Å in a region of 2 × 3 mm. The surface of the photoconductor of Production Example A had an F atom content of 5.2% and a C atom content of 81.3%.
The ratio was 0.064.

[Production Example B] In the photoreceptor of Production Example A,
A photoconductor drum was produced by replacing the protective layer with the following formulation.

That is, true spherical three-dimensional crosslinked polysiloxane fine particles (average particle diameter 0.29 μm, manufactured by Toshiba Silicone Co.) 1
Parts by weight, the following polycarbonate resin (bisphenol Z
Molecular weight 80,000) 6 parts by weight,

[0172]

[Chemical 16]

The following polydimethylsiloxane methacrylate-methyl methacrylate block copolymer (molecular weight 5
0000, Si content 12 wt%) 0.1 parts by weight

[0174]

[Chemical 17]

120 parts by weight of monochlorobenzene and 80 parts by weight of dichloromethane were dispersed and mixed in a sand mill. And 3 parts by weight of the following triphenylamine

[0176]

[Chemical 18] Was mixed and dissolved, and was applied onto the charge transport layer by spray coating to provide a 3 μm protective layer to obtain a photosensitive drum.

<Si / C Ratio XPS Measurement> After peeling off the surface of the photoreceptor, the surface elements were fixed by an ESCALAB200-X type X-ray photoelectron spectroscope manufactured by VG. X
Using MgCa (300 W) as a radiation source, measurement was performed at a depth of several Å in a region of 2 × 3 mm. The surface of the photoreceptor of Production Example B had 10.2% Si atoms and 69.3% C atoms, and the Si / C ratio was 0.147.

[Production Example C] In the photoreceptor of Production Example A,
The photoreceptor coated with the charge transport layer without the protective layer was used as the photoreceptor drum of Production Example C.

The values of the surface layers F / C, F / O or Si / C, Si / O of the photoconductors A to C are summarized in Tables 3 and 4.

[0180]

[Table 3]

[0181]

[Table 4]

Examples 1 to 4 and Comparative Examples 1 to 6 Carriers were saturated and magnetized in a magnetic field of 10 kilo Oersted, and then the carrier and toner were mixed so that the toner concentration was 5% by weight, and the combinations shown in Table 5 were used. To obtain a developer.

Canon full color laser copier CL
The C-500 was remodeled and an image was printed using each developer in a copying machine equipped with the above-mentioned photosensitive drum. The distance between the developing sleeve and the developer regulating member is 400 μm, the peripheral speed ratio between the developing sleeve and the photosensitive drum is 1.3: 1, and the developing condition is that the magnetic field strength of the developing pole is 1000 oersted. Alternating electric field 2000V _PP , frequency 3000
Hz, and the distance between the sleeve and the photosensitive drum is 500 μm
And At this time, the spikes of the developing brush near the developing pole on the developing sleeve were observed with a microscope to evaluate the image formation.
Further, the developing device was idly rotated at a speed of 200 rpm for 30 minutes to evaluate the image formation.

Regarding the brushing of the developing brush, paying attention to the compactness (density) and the brush length, a total of 4 stages (⊚, ○,
△, ×) evaluated.

Regarding the image quality evaluation, paying attention to the roughness in the halftone portion, the reproducibility of fine lines, the density uniformity in the solid portion, and the carrier adhesion, a comprehensive evaluation was made in four levels (⊚, ◯, Δ, ×).

A method of evaluating fixability in the examples of the present invention will be described.

As a recording material, commercially available copying machine paper Canon New Dry Paper (Canon Sales Company 54 g / m ²
Paper) to obtain an unfixed image and a commercial copying machine Canon
The fixing machine of FC-1 (Canon) was remodeled, the fixing temperature was modulated every 5 ° C. (120 to 200 ° C.), and the fixing start temperature and the offset temperature were observed.

Here, the fixing start temperature was determined by rubbing the obtained fixed image with sillbon paper 10 times in a reciprocating manner under a load of about 100 g, and peeling of the image was reduced by 10 at a reduction rate (%) of reflection density.
The temperature was set to be not more than%.

Examples 1 to 4 of the present invention and Comparative Examples 1 to 6
Table 5 shows the configuration and the evaluation results thereof.

[0190]

[Table 5]

[0191]

As described above, according to the present invention, it is excellent in high resolution, high highlight reproducibility and high fine line reproducibility, and it is possible to maintain a high quality image without deterioration in image quality even when copying a large number of sheets. A developer having fixability and an image forming method can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram schematically showing a magnetic characteristic curve (hysteresis curve). The horizontal axis represents the external magnetic field (Oersted), and the vertical axis represents the strength of magnetization of the carrier per unit volume.

FIG. 2 is a schematic diagram schematically showing a magnetic characteristic curve (hysteresis curve). The numbers shown in the box are (σ
The value is ( ₁₀₀₀ − σ ₃₀₀ ) / σ ₁₀₀₀ .

FIG. 3 is a schematic view schematically showing an electric resistance measuring device.

[Explanation of symbols]

 1 Lower Electrode 2 Upper Electrode 3 Insulator 4 Ammeter 5 Voltmeter 6 Constant Voltage Device 7 Carrier 8 Guide Ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Inaba 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Takehiko Chiba 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non non corporation

Claims (13)

[Claims] 1. A developer for developing an electrostatic charge image comprising a toner and a carrier, wherein a) the carrier has a particle size of 5 to 100 μm,
The bulk density is 3.0 g / cm ³ or less, and the strength of magnetization (σ ₁₀₀₀ ) at 1000 Oersted after the magnetic properties of the carrier are magnetically saturated is 30 to 150 emu /
cm ³ and the strength of magnetization (remanent magnetization: σr) in a magnetic field of 0 Oersted is 25 emu / cm ³ or more,
The coercive force is less than 300 Oersted, at which time the following formula is satisfied: [Wherein σ ₁₀₀₀ and σ ₃₀₀ represent the magnetization intensity (emu / cm ³ ) at 1000 and 300 oersteds after magnetic saturation, respectively. B) The toner is directly obtained by an aqueous suspension polymerization method and contains at least a colorant and a resin, and at least one of the peaks of the molecular weight distribution by GPC of the resin component constituting the toner is 5, A developer for developing an electrostatic charge image, which is in the range of 000 to 50,000 and contains at least one polar component in a resin component constituting the toner. 2. The developer for developing an electrostatic charge image according to claim 1, wherein the carrier has a substantially spherical shape and sphericity ≦ 2. 3. The carrier is made of ferrite, and the ferrite particles have a periodic table of IA, IIA, IIIA, I.
VA, VA, VIA, IB, IIB, IVB, VB, V
The electrostatic charge according to claim 1 or 2, which contains at least one element selected from the group consisting of IB, VIIB, and VIII, and the content of other elements is less than 1% by weight. Developer for image development. 4. The carrier is a spinel-structure single phase, a magnet-plumbite structure single-phase, a composite phase having at least a spinel structure or a magnet-plumbite structure, a composite phase of a spinel structure and a magnet-plumbite structure, and The developer for developing an electrostatic charge image according to any one of claims 1 to 3, wherein a molar ratio of the spinel phase and the magnetplumbite phase is 1: 1 to 10: 1. 5. The specific resistance of the carrier is 10 ⁸ to 10 ¹³ Ω.
The developer for electrostatic charge image development according to any one of claims 1 to 4, wherein the developer is cm. 6. A latent image is formed using an electrophotographic photoreceptor having a laminated structure including at least a conductive support, a charge generation layer and a charge transport layer, and the latent image is visualized with a developer. In an image forming method of forming an image on a transfer material by image formation, a) a substance having fluorine and / or a silicon atom is present in a surface layer of the electrophotographic photosensitive member, and a substance having carbon atoms and those by a XPS measurement are present. Using a photoreceptor having a ratio of F / C 0.01 to 1.00 Si / C 0.03 to 1.00, b) as a toner of the developer, directly obtained by an aqueous suspension polymerization method, At least one of the peaks of the molecular weight distribution by GPC of the resin component constituting the toner, containing at least the colorant and the resin, is 5,000 to 50,000.
0, and at least one or more polar components are contained in the resin component constituting the toner, and c) the carrier of the developer has a particle size of 5 to 100.
μm, the bulk density is 3.0 g / cm ³ or less, and the magnetization strength (σ ₁₀₀₀ ) at 1000 Oersted after the magnetic characteristics of the carrier are magnetically saturated is 30 to 1
50 emu / cm ³ , and the strength of magnetization (remanent magnetization: σr) in a magnetic field of 0 Oersted is 25 emu / cm ^3.
And above, the coercive force is less than 300 Oersted,
Then the following formula [Wherein σ ₁₀₀₀ and σ ₃₀₀ represent the magnetization intensity (emu / cm ³ ) at 1000 and 300 oersteds after magnetic saturation, respectively. ] The image forming method characterized by using the carrier which satisfy | fills these. 7. The surface layer of the electrophotographic photosensitive member,
7. Polycarbonate is contained.
The image forming method described in 1 .. 8. The surface layer of the electrophotographic photosensitive member,
The image forming method according to claim 6, further comprising a polycarbonate synthesized using an asymmetric diol. 9. The image forming method according to claim 6, wherein a protective layer is provided on the charge transport layer of the electrophotographic photosensitive member, and the protective layer contains polycarbonate. 10. The carrier is substantially spherical,
10. The image forming method according to claim 6, wherein sphericity ≦ 2. 11. The carrier is made of ferrite,
The ferrite particles are periodic tables IA, IIA, IIIA,
IVA, VA, VIA, IB, IIB, IVB, VB,
11. At least one element selected from the group consisting of VIB, VIIB and VIII is contained, and the content of the other elements is less than 1% by weight. Image forming method. 12. The carrier comprises a spinel structure single phase, a magnet plumbite structure single phase, and a composite phase having at least a spinel structure or a magnet prambite structure.
11. A composite phase of spinel structure and magnet-plumbite structure, wherein the molar ratio of spinel phase to magnet-plumbite phase is 1: 1 to 10: 1. The image forming method described in 1 .. 13. The carrier has a specific resistance of 10 ⁸ to 10 ¹³
The image forming method according to claim 6, wherein the image forming method is Ω · cm.