JP3374657B2 - Electrophotographic carrier, electrophotographic developer and image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer carrier and a developer used for developing an electric latent image or a magnetic latent image in electrophotography, electrostatic printing, etc. The present invention relates to an electrophotographic carrier having remarkably improved properties and image characteristics, an electrophotographic developer using the carrier, and an image forming method.

[0002]

2. Description of the Related Art Carriers constituting a two-component developer are
Conductive carriers and insulating carriers are roughly divided, and oxidized or unoxidized iron powder is usually used as the conductive carrier, but in a developer containing the iron powder carrier as a component,
There are drawbacks that the triboelectric chargeability of the toner is unstable and that the visible image formed by the developer is apt to cause fogging. That is, as toner particles adhere to and accumulate on the surface of iron powder carrier particles (toner spent) as the developer is used, the electrical resistance of the carrier particles increases, the bias current decreases, and the triboelectric charging property becomes unstable. And as a result,
The image density of the formed visible image is reduced and the fog is increased. Therefore, if the developer containing the iron powder carrier is used to continuously print with the electrophotographic apparatus, the developer deteriorates in a small number of times, so it is necessary to replace the developer at an early stage, resulting in high cost. Becomes

As the insulating carrier, a carrier in which the surface of the core material of a carrier generally made of a ferromagnetic material such as iron, nickel, ferrite is uniformly coated with resin is typical. In the developer using this carrier, toner particles are significantly less fused to the carrier surface than in the case of a conductive carrier, and at the same time, it is easy to control the triboelectric charging property between the toner and the carrier, It is excellent in durability and has a long service life, which is an advantage that it is particularly suitable for a high-speed electrophotographic apparatus.

There are various characteristics required for the insulating carrier, but as particularly important characteristics, suitable chargeability, impact resistance, abrasion resistance, good adhesion between the core and the coating material, and charge distribution. And the like.

In view of the above required characteristics, the conventionally used insulating carrier still has a problem to be improved, and a perfect one is not known so far.
For example, examples in which an acrylic resin or the like is used as a carrier coating material are disclosed in JP-A-47-13954 and JP-A-60-.
Japanese Patent Application Laid-Open No. 5785/1985 discloses an example of using a polyolefin resin as a coating material for a carrier.
It is disclosed in Japanese Patent Application Laid-Open No. 2-154639, Japanese Patent Application Laid-Open No. 54-35735 and the like. Further, what particularly describes the molecular weight is disclosed in JP-A-60-208767, etc., and it is known that the chargeability of the coated carrier is stabilized by controlling the molecular weight to be constant. ing. However, in order to attach the coating resin to the carrier core material, it is easily affected by the environment of the equipment such as the condition of the equipment and the coating environment, and even if the resin is strictly controlled, the resin is stably attached to the core material. At present, there is nothing satisfactory in order to have sufficient chargeability and durability.

Further, in recent years, demands for high definition and high image quality of copying machines have been increasing in the market, and attempts have been made in this technical field to achieve high image quality by making toner particle size fine. When the particle size of the toner becomes small, the surface area per unit weight increases, the charge amount of the toner increases, and the charging speed tends to be slow, and durability deterioration such as low image density, fog, and toner scattering occurs. This is a concern.

That is, in the development of the electrostatic latent image held by the electrostatic latent image holding member, the toner is mixed with a carrier which is a relatively large particle and used as a developer for electrophotography. The composition of both the toner and the carrier is chosen such that due to contact friction between them, for example, the toner will assume the opposite polarity of the charge on the photoconductive layer. As a result of the contact friction between the two, the carrier electrostatically attaches the toner to the surface, conveys it as a developer in the developing device, and supplies the toner onto the photoconductive layer of the electrostatic latent image carrier.

However, using such a developer,
When a large number of continuous copies are made with an electronic copying machine, clear and good-quality images are initially obtained, but as the number of copies increases, fog increases, and images with poor gradation and sharpness appear. Become.

This is because the rapid rise of triboelectric charging between the replenishment toner and the carrier in the developer deteriorates, the toner having an inappropriate charge amount is involved in the development, and the toner spent or the coating material deteriorates. This is because the charge imparting ability of the carrier is lowered, and this phenomenon becomes more remarkable as the particle size of the toner used is smaller.

In view of this, Japanese Patent Application Laid-Open No. 2-281280 proposes a carrier having a narrow particle size distribution in which the amount of fine powder and the amount of coarse powder are controlled, and a carrier having improved developing characteristics is achieved. Further, further attempts have been made to further reduce the diameter of the carrier for the purpose of improving the development efficiency when using a toner having a fine particle diameter. However, such a carrier does not have sufficient quality to cope with a change in the amount of charge due to the environment or durability of the toner, and it is necessary to achieve high image density, high image quality, good fog prevention, and carrier adhesion prevention. The reality is that it is difficult to achieve.

On the other hand, in order to solve the above-mentioned various problems, improvements from the toner side are being actively made.

As means for improving the fluidity of the toner and achieving a rapid rise of triboelectric charging between the replenishing toner and the carrier in the developer, for example, Japanese Patent Laid-Open No. 46-5782.
JP-A-48-47345, JP-A-48-47345
In Japanese Patent No. 47346, it is proposed to add fine silica powder to toner powder.

However, the additive capable of imparting sufficient fluidity to such a toner needs to have a very small particle size, and as a result, carrier contamination such as adhesion of the additive to the carrier coating material (so-called carrier spent). )
The carrier coating material is likely to be abraded by the additives and additives, and the charge imparting ability of the carrier is deteriorated. Therefore, as the number of copies increases, fog increases and the image lacks gradation and sharpness.

In this way, the rapid rise of charging,
The reality is that no developer has yet been obtained that satisfies the control of the carrier spent and sufficiently satisfies the high image density and the high image quality without fog even after long-term use.

[0015]

The main object of the present invention is to:
The electrophotographic carrier and the electrophotographic developer with improved durability, which have been improved in various conventional defects as described above, especially in various environments, charging properties, mechanical strength, adhesion to core material, and spent resistance. And an image forming method.

It is another object of the present invention to provide an electrophotographic developer and an image forming method which have good durability of toner transferability and show no deterioration of image quality in the highlight portion even after long-term use. is there.

Another object of the present invention is to provide an electrophotographic developer and an image forming method in which the surface of the photoreceptor is not scratched even after long-term use.

[0018]

The present invention provides an electrophotographic carrier having magnetic ferrite powder whose surface is coated with a polyolefin resin layer, wherein the ferrite powder is represented by the following formula (1) (Fe ₂ O ₃ ). x (MnO) y (A) z Formula (1) [wherein A represents Na ₂ O, K ₂ O, CaO, SrO or a mixture thereof, and x, y and z represent mole fractions, and The following conditions 0.3 <x <0.8, 0.01 <y <0.5, 0 <z <
0.69 and x + y + z ≦ 1 are satisfied. And a carrier for electrophotography, characterized in that the polyolefin resin layer is directly polymerized and coated on the surface of the carrier, and an electrophotographic developer having the carrier (hereinafter , "Invention 1" means this invention).

Further, the present invention provides an electrophotographic developer comprising at least a toner and a carrier, wherein the carrier has a magnetic ferrite powder whose surface is coated with a polyolefin resin layer, and the ferrite powder is following formula _{(2) (Fe 2 O 3} ) x (a) y (B) z formula (2) wherein, a represents an MgO or Ag ₂ O or MgO + Ag ₂ O, B is Li ₂ O, MnO ₂ , CaO, SrO, Al ₂
Represents one or more metal elements selected from the group consisting of O ₃ and SiO ₂ , x, y and z represent weight ratios, and the following conditions 0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3, x +
It satisfies y + z ≦ 1. ] The polyolefin resin layer is directly polymerized and coated on the surface of the carrier, and the toner has an apparent viscosity of 10 ⁵ poise in the range of 80 to 120 ° C. The present invention relates to a developer for electrophotography (hereinafter,
"Invention 2" means this invention. ).

Furthermore, the present invention provides an electrophotographic developer comprising at least a toner and a carrier, wherein the carrier has a surface of a magnetic core material and a polyolefin resin layer coating the surface of the magnetic core material. Has a weight average particle diameter of 3 to 9 μm, contains 10 to 70% by weight of toner particles having a particle diameter of 4.00 μm or less, and contains at least a metal compound capable of forming an anionic polymerization catalyst as an external additive. The toner relates to an electrophotographic developer having an apparent viscosity of 10 ⁵ poise in a range of 80 to 120 ° C. (hereinafter, referred to as “present invention 3”).
Means this invention. ).

Further, according to the present invention, a two-component developer having a toner and a carrier is circulated and conveyed by a developer carrier to develop the electrostatic latent image held on the electrostatic latent image carrier in the developing area. In the image forming method of developing with the toner of the two-component developer carried on the agent carrier, the carrier has a magnetic core material surface and a polyolefin resin layer coating the magnetic core material surface, The toner has a weight average particle diameter of 3 to
1 toner particle having a particle size of 9 μm and a particle size of 4.00 μm or less
0 to 70% by number, containing at least a metal compound that can constitute an anionic polymerization catalyst as an external additive,
The toner contains at least a metal compound capable of forming an anionic polymerization catalyst as an external additive, and the toner has an apparent viscosity of 10 ⁵ poise at a temperature of 80 to 120 ° C.
The present invention relates to an image forming method (hereinafter, "present invention 4" means the present invention).

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the carrier of the present invention 1, a polyolefin resin layer is directly polymerized and formed on the surface of a core material, and the core material composition has a great feature.

[0023] First, Fe ₂ O ₃ is a component necessary for obtaining proper magnetic properties, in particular a magnetic brush developing method can obtain a good image quality.

The inclusion of an oxide of an alkali metal or an alkaline earth metal is effective in controlling the charge imparting ability under high humidity while maintaining the carrier resistance within an appropriate range. When used together, the effect is dramatically increased.

However, according to the detailed study by the present inventors,
It has been clarified that not all alkali metals or alkaline earth metals are effective, but only metal atoms having physical property values within a specific range are effective.

That is, in order for each composition component to form a solid solution with each other to form a crystal lattice and control the electric resistance and the charge amount, an appropriate ionic radius range is required in the contained metal. As a result of diligent studies by the inventors, the ionic radii of Li ⁺ , Be ²⁺ and Mg ²⁺ are smaller than the proper range, and the ionic radii of Rb ⁺ and Cs ⁺ are larger than the proper range. The resistance was lower than the desired carrier resistance range, and it was unsuitable for use as a carrier for electrophotography. Further, in order to control the charge amount, it is necessary that the ionization potential of the metal is low and that a high atomic state exists, and Ba ²⁺
It is also clear that even if a metal having no higher valence is contained, a high charge amount cannot be obtained.

When MnO coexists as described above,
Although the reason why a particularly high effect is obtained is not clear, since Mn oxide and Fe ₂ O ₃ can form a solid solution with each other to form a spinel structure, the resistance can be controlled to some extent, and the ionization potential is low. Moreover, it is considered that one of the causes is that it has a relatively high charging ability because it can assume a high valence state. That is, coexistence of MnO and an alkali metal or an alkaline earth metal causes the lattice structure or the metal valence states to perturb each other, and it is considered that the respective effects are synergistically improved.

As a ferrite carrier containing MnO as an essential component, there is disclosed a ferrite carrier containing MnO and MgO as essential components in JP-A-58-123552, JP-A-59-111159 and JP-B-6-23866. Have been proposed, JP-A-58-215664, JP-A-59-111926, and JP-A-62-2.
Japanese Patent No. 97857 proposes a ferrite carrier containing MnO and Li ₂ O as essential components. However, according to the study by the present inventors, MgO or Li ₂
Even if O coexisted with MnO, the effect was insufficient in terms of resistance adjustment. As described above, this is Li ⁺ or M
It is considered that g ^{2+ and the} like deviate from the range of the ionic radius appropriate for forming a stable and uniform crystal lattice.

Further, Japanese Patent Publication No. 6-23866 proposes that in addition to MnO and MgO, a metal such as Cu, Zn and Co may coexist in the ferrite composition. However, studies by the present inventors have revealed that it is not easy to enhance the charge imparting ability of the carrier even if such a metal is contained.

This is generally understood because there is a correlation between the ionization potential of the metal contained in the carrier and the charge imparting ability of the carrier, and the larger the ionization potential, the more difficult the carrier is to be positively charged. That is, comparing the ionization potentials of the metal contained in the ferrite composition described in JP-B-6-23866 and the metal contained in the magnetic ferrite component in the present invention, the following relations Cu, Zn, Co > Na, K, Ca, Sr (large ← ionization potential → small), and the order of Na, K, Ca, and Sr is smaller than that of Cu, Zn, and Co. When contained, it is considered to act so as to be more positively charged.

The magnetic ferrite component used in the present invention 1 is represented by the following formula (1) (Fe ₂ O ₃ ) x (MnO) y (A) z formula (1) [wherein A is Na ₂ O, K ₂ O, CaO, SrO or a mixture thereof, x, y and z represent mole fractions, and the following conditions 0.3 <x <0.8, 0.01 <y <0.5,0 <z <
0.69 and x + y + z ≦ 1 are satisfied. ] Is shown.

In the above formula (1), x,
y and z satisfy the following conditions 0.3 <x <0.8, 0.01 <y <0.5, 0 <z <
0.69, x + y <1, z = 1-xy, more preferably 0.4 <x <0.8, 0.02 <y <0.3, 0 <z <
It is preferable that 0.3 and x + y + z ≦ 1 be satisfied from the viewpoint of improving the charging ability of the carrier. However, in the present invention, other values within the range of 0.03 mol ratio or less do not hinder the effect of the magnetic ferrite component. For the purpose of adjusting the crystal grain size of the magnetic carrier core material particles, preventing coalescence during firing, or adjusting the particle size distribution, hydroxides, oxides, sulfides, acid compound salts, etc. in the magnetic ferrite component It may be contained in the form of.

In the above formula (1), when x is 0.3 mol ratio or less, the resistance becomes very high, so that it becomes difficult to control the resistance value, and when x is 0.8 mol ratio or more, the magnetic properties are deteriorated. When used in the brush development method, it is difficult to obtain good image quality. When y is 0.01 molar ratio or less, it is difficult to control both the carrier resistance and the magnetic characteristics in an appropriate range,
If y is 0.5 mol ratio or more, the magnetic properties deteriorate.
When z is 0 mol, that is, when (A) is not contained,
In particular, when it is used in combination with a toner having a fine particle diameter, the charging ability is lowered and it becomes difficult to maintain the durability.

Further, in the present invention 1, the carrier core material is combined with a coating method for directly polymerizing and coating a polyolefin resin on the surface of the carrier to remarkably improve the durability of charging characteristics and transferability. Is also a major feature.

In the case of a carrier obtained by directly polymerizing a polyethylene resin layer on the surface of a core material, although the spent resistance is improved, there are no sites for trapping charges in the polyethylene resin layer, and therefore, it is used for an electrophotographic developer. In this case, since the charge imparting ability to the toner is small and the charging speed is slow, the charge amount distribution of the toner is broadened, the transferability of the toner is deteriorated, and the image quality of the highlight portion becomes rough,
Furthermore, problems such as fogging tend to occur during long-term use. In addition, when the resin used as the coating material has a certain degree of crystallinity, the adhesion with the carrier core material is insufficient,
With long-term use, peeling of the resin layer easily occurs,
Since the charge transfer speed between the core material and the resin is slow, it is inevitable that long-term durability and deterioration of the charging characteristics will occur.

However, when the polyolefin resin layer is directly polymerized on the surface of the carrier core material having the above-mentioned ferrite composition, not only the spent resistance but also the abrasion and peeling of the coating layer, the charge imparting ability, the charging speed, And, it becomes possible to greatly improve the distribution of the charge amount.

The reason for this is presumed as follows. It is considered that the carrier of the present invention 1 has a strong reducing action due to the high negative charge imparting ability. Therefore,
When the reduction polymerization reaction proceeds on the surface of the carrier, the ability of the catalyst is more activated, and the formed coating resin may have a molecular weight distribution that is resistant to abrasion and peeling.

Further, since the carrier core material itself has a high charge imparting ability, it is considered that the charge injecting ability into the toner through the polymerization catalyst and the polyolefin resin layer is also high.

Furthermore, the above-mentioned effects were particularly remarkable when A in formula (1) was Ca or Sr.

The present inventors consider the reason for this as follows. In the present invention 1, Ti ⁴⁺ , M is ^contained in the polyolefin polymerization catalyst used for treating the surface of the carrier.
g ²⁺ is contained. When an alkaline earth metal is contained in the composition of the carrier core material described above, the affinity with Mg atom which is the same alkaline earth metal is improved in the surface treatment of the carrier, or the substitution of some atoms occurs. ,
As a result, it is considered that the adhesion of the polymer-coated polyolefin resin to the surface of the carrier core material was significantly improved, and the charge transfer rate between the coating layer and the carrier core material was also significantly improved.

In addition, the interaction with the core material constituents further changes the catalytic ability during polymerization, and the molecular weight distribution of the polyolefin resin formed is such that the adhesion to the surface of the core material, the abrasion resistance, and the resistance to abrasion. It is also speculated that it became appropriate due to the spent nature.

The developer of the present invention 2 has at least a toner and a carrier. In the carrier, the polyolefin resin layer is directly polymerized and formed on the surface of the core material, and the core material composition has a great feature. is there.

The magnetic ferrite component used in the present invention 2 is represented by the following formula (2) (Fe ₂ O ₃ ) x (A) y (B) z formula (2) [wherein A is MgO or Ag ₂ O or Represents MgO + Ag ₂ O, B is Li ₂ O, MnO ₂ , CaO, SrO, Al ₂
Represents one or more metal elements selected from the group consisting of O ₃ and SiO ₂ , x, y and z represent weight ratios, and the following conditions 0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3, x +
It satisfies y + z ≦ 1. ] Is shown.

First, Fe ₂ O ₃ is a component necessary for obtaining appropriate magnetic characteristics and resistance characteristics, and particularly in the magnetic brush developing method, good image quality can be obtained.

In the above formula (2), when x is less than 0.2, the magnetic properties are deteriorated, carrier adhesion during development and scratches on the surface of the photoreceptor are likely to occur, and when x exceeds 0.95. In, the resistance of the ferrite core material is likely to be low, and the charge amount and the image quality are deteriorated. When y is less than 0.005, it is difficult to obtain appropriate resistance and magnetic properties, and when y is more than 0.3, homogenization and spheroidization may not be achieved on the carrier particle surface. Also, x + y + z
Does not necessarily have to be 1, and other metal oxides or compounds may be contained in the carrier core material as long as the characteristics of the carrier core material are not impaired.

Component A preferably used in the present invention 2 is ferrite particles containing MgO having a solubility of 0.62 mg / 100 ml and Ag ₂ O having a solubility of 1.74 mg / 100 ml, and more preferably, the core material. From the viewpoint of resistance stability, ferrite particles containing at least 0.5 to 30% by weight of MgO in terms of oxides are preferable because they can be easily surface homogenized and spheroidized and contain an appropriate amount of water.

The B component preferably used in the present invention 2 includes Li ₂ O, MnO ₂ , CaO, SrO, Al ₂
O ₃ and SiO ₂ can be mentioned, but more preferably, MnO ₂ , CaO, and Al ₂ exhibiting a small resistance decrease even when a high voltage is applied.
Examples thereof include O ₃ and SiO ₂ , and MnO ₂ and CaO are more preferable from the viewpoint of compatibility with the replenishment toner.

Further, the present invention 2 is also characterized in that the carrier core material is combined with a coating method of directly polymerizing and coating a polyolefin resin on the carrier surface.

In the case of a carrier obtained by directly polymerizing a polyethylene resin layer on the surface of a core material, although the spent resistance is improved, there are no sites for trapping charges in the polyethylene resin layer, and therefore, it is used in an electrophotographic developer. In this case, it is difficult to uniformly charge the individual additives because the charge imparting ability to the toner and the ultrafine powder is small and the charging speed is slow, and a large amount of untransferred additives are generated at the time of transfer. Occurrence of scratches on the body surface is unavoidable.

However, when the polyolefin resin layer is directly polymerized on the surface of the carrier core material composed of the above-mentioned ferrite composition, the charge imparting ability to the metal oxide is improved and the untransferred additive is drastically reduced. It is possible to suppress the occurrence of scratches on the body surface.

The reason for this is currently being clarified,
One reason is that the metal element constituting the ferrite component according to the second aspect of the present invention has a fast charge transfer reaction with the metal oxide added to the toner. Furthermore, the effect of hygroscopicity of the constituent metal elements can be considered. That is, since MgO or Ag ₂ O contained in the ferrite particles has an appropriate hygroscopicity, when the carrier core material surface is treated with a polyolefin polymerization catalyst, the catalytic activity is moderately relaxed by the adsorbed water, and the coated polyolefin The molecular weight of the resin or the gap between the polymer chains is appropriate for the transfer of charges between the carrier surface and the additive for toner, and the adsorbed moisture accelerates the charge transfer reaction rate between the core surface and the coating layer. Therefore, there is a possibility that the charging rate of the toner additive is improved.

In Japanese Patent Laid-Open No. 2-33159,
Although it is described that a part of the above-mentioned general formula (2) is contained as a carrier constituent component, in the present invention 2,
By containing a specific amount of a metal oxide having a specific solubility,
Characterized by directly polymerizing and forming a polyolefin resin layer on the surface of the carrier core material, as a result, not only the durability of the carrier but also the life of the photoreceptor can be significantly improved, and the invention described above. It is different.

Further, as a ferrite carrier containing MgO, for example, JP-A-59-111159,
JP-A-58-123551, JP-A-55-654
However, these are not intended to interact with the surface coating resin and are different from the second invention.

Further, JP-A-2-33159 describes that MgO may be contained, but the present invention 2
As described above, there is no suggestion of positively adopting MgO to control the surface of the carrier core material to enhance the reactivity, which is also different from the second aspect of the present invention.

The developer of the present invention 3 has at least a toner and a carrier, the carrier has a magnetic core material surface and a polyolefin resin layer coating the magnetic core material surface, and the toner is A metal compound that can form at least an anionic polymerization catalyst is contained as an external additive.

For the developer of the present invention 3, it is one of the preferable modes to use the carrier described in the above inventions 1 and 2, but it is not necessarily limited to these carriers.

In the present invention, it is preferable to use a carrier in which a polyolefin resin layer is directly polymerized and formed on the surface of a carrier core material, because the durability as a developer is remarkably improved. This is because not only the spent resistance but also the wear and peeling of the coating layer are prevented because the entire surface of the carrier is uniformly coated with resin,
Further, it is because the charge imparting ability and the charging speed are greatly improved.

This effect is due to the GP of the polyolefin resin layer.
In the molecular weight distribution obtained from C molecular weight measurement, the molecular weight is 5,000 or more, more preferably 70 or more.
00-700000, and further 30,000-70000
It is particularly remarkable in the case of a high molecular weight of 0, more preferably 50,000 to 500,000. Further, at that time, the number average molecular weight is preferably in the range of 2000 to 30,000 from the viewpoint of the adhesion of the polyolefin resin to the surface of the carrier core material.

That is, when a polyolefin resin having a weight average molecular weight of 5000 or more is formed into a film, the strength of the film is high and the releasability is excellent. Therefore, when it is applied to the surface of a carrier, the durability and the spent resistance are further improved. Although it is expected to be improved, in general, a polyolefin resin having a weight average molecular weight of 5000 or more is difficult to dissolve in an organic solvent, and if this solution is wet-coated on the surface of a carrier to form a coating layer, the coating layer will not be formed. It tends to be uniform. However, when the polymerization is carried out directly on the surface of the carrier, the high molecular weight polyolefin resin layer can be formed uniformly, so that the durability is remarkably improved.

The number average molecular weight of the polyolefin resin is 20
If it is less than 00, the strength of the formed film is lowered and the releasability is also lowered. Therefore, when applied on the surface of a carrier, the durability and the spent resistance are easily lowered, and the number average molecular weight is When it exceeds 30,000, the adhesion of the polyolefin resin to the surface of the carrier core material is lowered, and the coating layer of the polyolefin resin coated on the surface of the carrier core material is likely to be peeled off.

In the present invention, a method for producing a carrier is, for example, JP-A-60-1068.
The method described in JP-A No. 08 or JP-A-60-106809 can be used. Further, by appropriately adjusting the molecular weight from the production conditions, it is also possible to further enhance the adhesion between the polyolefin resin layer and the carrier core material, and further, the carrier after coating should be used after being spheroidized by heat treatment. Is also one of the preferable usage forms.

On the other hand, it has also been clarified that the polyolefin resin-coated carrier of the present invention exhibits excellent charging characteristics especially when the carrier particle size is small. Generally, when the particle size of the carrier is small, the surface area of the carrier is increased, so that triboelectric charging with the toner or the additive is advantageous, but on the contrary, it is difficult to uniformly coat the entire surface of the carrier with resin, and transfer due to partial charging failure is caused. Deterioration and fog tend to occur. However, in the carrier of the present invention, it is possible to uniformly coat the entire surface of the carrier, so that even if the carrier particle size is small, good charging characteristics are exhibited. Therefore, even when it is difficult to uniformly charge the individual additive particles as in the case of using a toner having a large particle size that contains a large amount of additives, the occurrence of particles with poor charging and high-definition images are obtained. It is possible.

As described above, the carrier of the present invention exhibits excellent charging characteristics even when used with a small particle size, and therefore can be used in combination with a toner with a small particle size having a large specific surface area.

As described above, when a toner having a small particle diameter is used, high image quality can be achieved, but on the other hand, the toner specific surface area increases, the toner charge amount increases, and the charging speed decreases. There is a tendency that deterioration in durability such as low image density, fog, and toner scattering easily occurs. In addition, since the specific surface area of the toner increases, the contact time with the carrier becomes long, and the carrier spent is likely to occur.

However, by combining with a carrier having a small particle size, which has the constitution of the present invention, no carrier spent is observed and individual toner particles are uniformly charged, resulting in low image density, fog and toner scattering. Durability deterioration can be prevented, and high-definition images can be obtained for a long period of time.

As the appropriate carrier particle size, a volume median diameter of 10 to 60 μm is preferable, and 10 to 40 μm.
More preferred is m. If it is smaller than this range, the fluidity of the developer is lowered, and the load when the developer is circulated in the developing device is increased, so that the developer is easily deteriorated. Sometimes it is difficult to obtain a sufficient charging speed. Furthermore, 27.5μ
It is more preferable that the particles of m or less are contained in an amount of 1.0 to 80% by weight. With this particle size distribution configuration, good charging characteristics can be maintained even when the carrier surface is spent to some extent, and durability is further improved. If the content of particles of 27.5 μm or less is less than 1.0%, it is difficult to significantly improve durability.
If it exceeds 0% by weight, carrier adhesion is likely to occur during development, and the apparent density of the developer increases, so the load during circulation of the developer in the developing device also increases and the developer deteriorates. Easier to do.

Furthermore, in the carrier of the present invention,
The resistance value under the voltage of 0.5 kV to 1 kV is 10 ⁶ to
10 ¹¹ Ωcm and 79.6 kA / m (1000
The saturation magnetization is 15 to 85 with respect to the applied magnetic field of Oersted.
When it has a value of Am ² / kg, the durability as a developer is further improved. If the carrier resistance is higher than 10 ¹¹ Ωcm, selective development of toner that is easily developed due to the drop in the developing electric field between the photoconductor and the developer carrying body is liable to occur, and thus toner that is difficult to develop accumulates. However, if a person stays on the carrier for a long time, re-carrier spent is likely to occur. On the other hand, when the carrier resistance is lower than 10 ⁶ Ωcm, the obtained image quality is significantly deteriorated, and the effect of improving the image quality is not sufficiently exhibited even if the toner having a small particle size is used. Also, 79.6 kA / m
When the saturation magnetization with respect to an applied magnetic field of (1000 Oersteds) is larger than 85 Am ² / kg, the durability is deteriorated because the developer is easily deteriorated when the developer is stirred in the vicinity of the developer carrier, and 15 Am ² / kg or more When it is small, the mixing of the replenishment toner becomes insufficient, the durability of the charging property is deteriorated, and carrier development, that is, carrier adhesion occurs.

As a means for obtaining a carrier having the above resistance range, any adjustment such as adjustment with a carrier core material, adjustment from the coating amount of the coating material, or addition of a conductive additive in the coating layer is possible. Techniques can be used. As the conductive additive, carbon black, TiO ₂ , SnO ₂ or the like can be arbitrarily selected as long as the material can reduce the resistance of the recarrier by adding the conductive additive.

As the form of the magnetic particles used for the core material of the carrier in the present invention, ferrite particles of various shapes, magnetic powder-dispersed carriers made of a mixture of various resins and magnetic powder, and the like can be used.

The carrier of the present invention thus obtained can be used as a magnetic brush developer for electrophotography by mixing it with a known toner, but such a toner has a weight average particle diameter of 3 to 9 μm, When a compound composed of a metal capable of forming an anionic polymerization catalyst is externally added and mixed as an additive for the purpose of improving the fluidity or charging characteristics of the toner, the developer of the present invention composed of these carrier and toner It has been revealed that (particularly the present invention 3) shows very excellent durability characteristics that a high-definition image is provided for a long period of time without wear or peeling of the coating layer on the carrier surface. The reason for this is not clear, but when abrasion or peeling of the coating layer by the external additive occurs during durability, the cut portion is immediately repaired by the metal for anionic polymerization catalyst which is a component of the external additive. Conceivable.

As the metal that can constitute the anionic polymerization catalyst, one having an excessively small atomic radius is not preferable. This is because when the atomic radius is small, the interaction between the metal and the coating resin becomes large, and the cleavage reaction, which is the reverse reaction of the polymerization reaction, is promoted, and the abrasion and peeling of the coating layer during durability deteriorate. Be done.

As a guideline for the preferable atomic radius of the metal contained in this external additive, refer to the data of interatomic bond distances in Chemical Handbook (Chemical Society of Japan), Basic Edition, page II-714, Tables 15 and 21. For reference, it was found that those having a value of 1.7 Å or more as a bond distance with oxygen when forming a metal oxide give preferable results.

Further, as the compound made of a metal which can form the anionic polymerization catalyst externally added to the toner, a metal oxide having an average particle size of 0.005 to 0.2 μm whose surface is hydrophobized. Is preferred. The hydrophobic treatment prevents the aggregation of the primary particles and improves the charging characteristics under high humidity. Therefore, when externally mixed with the toner, a toner having high fluidity and good charging characteristics can be obtained. Here, the hydrophobicity of the metal oxide is preferably 40 to 75%. If it is less than 40%, the amount of electrification under high humidity decreases and the durability becomes poor, and if it exceeds 75%, the one subjected to a hydrophobic treatment hinders the interaction between the metal oxide and the carrier coating resin, so that the coating resin The restoration effect is lowered and the durability is lowered, and at the same time, the charge amount is easily increased at the time of durability under low humidity.

The average particle size of the metal oxide is 0.2 μm.
If it is larger, the fluidity-imparting ability is low and 0.005 μm
If it is less than the above range, the toner tends to be embedded in the toner at the time of durability and the durability as a developer is deteriorated.

Further, it is also important to use one having a large surface area in order to enhance the repairing action of the carrier coating resin by such a metal oxide. Specifically, when a metal oxide having a BET specific surface area of 90 m ² / g or more is used, a very preferable result is obtained. Further, the addition amount to the toner is also important, and the addition amount is A% by weight to the toner, and the BET specific surface area of the metal oxide is Bm ²
/ G, it is preferable to use so that A × B = 50 to 300. If it is less than 50, the repair action of the coating resin is insufficient, and if it exceeds 300, the repair reaction is oppositely balanced, so that the coating resin may be easily scraped or peeled.

As specific compounds of these metal oxides, hydrophobized alumina or titanium oxide is preferably used in terms of both fluidity imparting ability and charging characteristics. The crystal structure of the metal oxide is also important in the repairing action of the coating resin, and γ-alumina or amorphous titanium oxide has a particularly high repairing action. These compounds can be used alone, in combination, or in a mixture with other external additives.

It is also an essential technique to use a toner having a weight average particle diameter of 3 to 9 μm as the toner according to the present invention. Thereby, a high quality image can be stably obtained for a long period of time. The reason for this is that, by allowing the carrier of the present invention to uniformly charge individual toner particles having a small particle size, a high-definition image can be obtained with less occurrence of poorly charged toner, and a toner having a small particle size can be obtained. It is considered that selective development is unlikely to occur because the particle size distribution width is narrow. At that time, 10 particles having a particle diameter of 4.00 μm or less were used.
When a toner containing about 70% by number is used, the selective developability is further suppressed, and it becomes possible to obtain a higher definition image for a long period of time. If the toner particles having a particle diameter of 4.00 μm or less is less than 10% by number, the fine toner particles, which are an essential component for high image quality, are few, and the toner particles necessary for reproducing the high image quality by long-term use are small. The amount of the component decreases, the balance of the particle size distribution of the toner is lost, and the image quality tends to deteriorate. On the other hand, if it exceeds 70% by number, the toner particles are likely to aggregate with each other to easily form a lump of toner, resulting in a rough image quality or a reduction in resolution.
Or, the density difference between the edge of the latent image and the inside becomes large,
The image tends to be hollow.

As the particle size of the toner becomes finer,
Generally, it is necessary to increase the addition amount of the fluidity improver and the like, but as a result, the abrasion of the carrier surface coating resin by such additive fine powder is likely to be deteriorated, and the durability is likely to be deteriorated.

However, as in the present invention, by using a carrier having a specific surface constitution and a toner containing a specific external additive in combination, the deterioration of durability is significantly reduced.

Further, the acid value is 1 to 30 KOHmg /
It is more preferable to use a toner having a value of g. When a toner having an acid value of less than 1 KOHmg / g is used, the charging speed is likely to decrease, durability characteristics under low humidity are also deteriorated, and when the acid value exceeds 30 KOHmg / g, the charge on the toner surface is likely to leak, The charging characteristics deteriorate with durability.

It is even more preferable to use a toner having a glass transition temperature in the range of 45 to 70 ° C. and a temperature in which the apparent viscosity of 10 ⁵ poise is in the range of 80 to 120 ° C. The glass transition temperature is lower than 45 ° C or the temperature showing an apparent viscosity of 10 ⁵ poise is 80.
If the temperature is lower than ℃, carrier spent is liable to occur during long-term use of the developer, the glass transition temperature is higher than 70 ℃, or the temperature showing an apparent viscosity of 10 ⁵ poise is 120 ℃.
When it is higher, it becomes difficult to maintain the fixing property of the toner on the toner transfer body while maintaining the durability of the developer.

The binder resin for toner is not particularly limited, but preferably contains a polar group consisting of atoms other than C and H. This is because the affinity between the polyolefin resin having low polarity and the toner is lowered, and the carrier spent by the toner is further suppressed. As a specific index, when a polymer having a solubility parameter value of 17.0 (J / cm ³ ) ^1/2 or more is used as a binder resin for toner, good durability can be obtained.

Here, the solubility parameter of the polymer can be estimated by the following procedure. The polymer to be measured is added to a series of solvents and mixed solvents having slightly different solubility parameter values, and the solubility parameter of the most solvable solvent is used as the polymer solubility parameter. For a polymer that is difficult to dissolve, the solubility parameter of the solvent that maximizes the swelling amount is used as the solubility parameter of the polymer.

Further, addition of a wax-like substance such as polyethylene or polypropylene to the toner according to the present invention for use gives more preferable results. Such additives are generally used for the purpose of improving releasability at the time of heat roll fixing, but in the present invention, the durability of the developer is further improved. Although the reason is unknown, it is considered that such a wax-like substance is used for repairing a scraped portion or a peeled portion of the coating material on the carrier surface. The amount of the wax-like substance added is preferably 0.1 to 20.0% by weight. 0.1
If it is less than 10% by weight, the durability of the carrier due to the repairing action is not improved, and if it exceeds 20.0% by weight, the affinity between the toner and the carrier is improved and the carrier spent by the toner is deteriorated. On the contrary, the sex tends to decrease.

When the carrier according to the present invention and the toner are mixed to prepare the two-component developer according to the present invention, the mixing ratio is preferably 2.0 to 15% by weight as the toner concentration in the developer. Preferably 3.0 to 14% by weight
Very good results are obtained. If the toner concentration is less than 2.0% by weight, the image density is low, and the image quality during durability is significantly deteriorated, making it unusable. If it exceeds 15% by weight, fog and in-machine scattering are increased, and the useful life of the developer is increased. It will be shortened.

Next, the present invention 4 using the above two-component type developer
The image forming method will be described.

In the image forming method of the present invention, a two-component type developer having a toner and a carrier is circulated and conveyed on a developer carrier to hold a latent image on the latent image carrier and the development area of the developing carrier opposite thereto. The latent image held on the body is developed with the toner of the two-component developer on the developer carrier.

The magnetic characteristics of the carrier are affected by the magnet roller incorporated in the developing sleeve, and greatly affect the developing characteristics and the transportability of the developer.

In the image forming method of the present invention, of the developing sleeve (developer carrying member) and the magnet roller incorporated therein, for example, the magnet roller is fixed and the developing sleeve is rotated by itself to be composed of magnetic particles. A two-component developer composed of a carrier and an insulating color toner is circulated and conveyed on a developing sleeve, and the two-component developer develops the electrostatic latent image held on the surface of the electrostatic latent image carrier. is there.

In the image forming method of the present invention, in particular, the magnet roller has a five-pole structure having a repulsive pole,
The magnetic flux density in the developing region is 500 to 1200 Gauss, and the saturation magnetization of the carrier is 20 to 70 Am ² / k.
When it is g, the uniformity and gradation reproducibility of the image are excellent in color copying, which is preferable.

In the image forming method of the present invention, it is preferable to apply a developing bias in the developing area to develop the electrostatic latent image with the toner of the two-component developer.

An image forming apparatus capable of carrying out the image forming method of the present invention will be described with reference to FIG.

In FIG. 3, the image forming apparatus has a photosensitive drum 1 as an electrostatic latent image holding member, and a developing device 4
The interior of the developing container 66 is separated by a partition 67 into the developing chamber (first
Room) R ₁ and agitation room (second room) R _2
A toner storage chamber R ₃ is formed above _{2 with} a partition wall 67 therebetween. A developer 69 is contained in the developing chamber R ₁ and the stirring chamber R ₂ , and a replenishment toner (non-magnetic toner) 68 is contained in the toner storage chamber R ₃ . A replenishment port 70 is provided in the toner storage chamber R ₃ , and an amount of replenishment toner 68 commensurate with the toner consumed through the replenishment port 70 is dropped and replenished into the stirring chamber R ₂ .

[0094] A conveying screw 63 in the developing chamber R ₁ is formed, the developer 69 in the developing chamber R ₁ by the driving rotation of the conveying screw 63 is conveyed toward the longitudinal direction of the developing sleeve 61 . Similarly, a conveying screw 64 is provided in the storage chamber R ₂ , and the conveying screw 64
The toner dropped from the replenishing port 70 into the stirring chamber R ₂ is conveyed along the longitudinal direction of the developing sleeve 61.

The developer 69 is a two-component developer containing a non-magnetic toner and a magnetic carrier.

An opening is provided at a portion of the developing container 66 near the photosensitive drum 1, and the developing sleeve 6 is opened from the opening.
1 protrudes to the outside, and a gap is provided between the developing sleeve 61 and the photosensitive drum 1. Bias applying means 80 for applying a bias is disposed on the developing sleeve 61 formed of a non-magnetic material.

As described above, the magnet roller fixed to the developing sleeve 61 as the magnetic field generating means, that is, the magnet 62, includes the developing magnetic pole S ₂ and the magnetic pole N ₂ located downstream thereof.
And magnetic poles N ₃ , S ₁ and N ₁ for carrying the developer 69. The magnet 62 is arranged in the developing sleeve 61 so that the developing magnetic pole S ₂ faces the photosensitive drum 1.
The developing magnetic pole S ₂ forms a magnetic field in the vicinity of the developing portion between the developing sleeve 61 and the photosensitive drum 1, and the magnetic field forms a magnetic brush.

The regulating blade 65 which is arranged above the developing sleeve 61 and regulates the layer thickness of the developer 69 on the developing sleeve 61 is an end portion of the non-magnetic blade 65 made of a non-magnetic material such as aluminum or SUS316. And the surface of the developing sleeve 61 is 300 to 2000 μm, preferably 400 to 1500 μm. This distance is 300 μm
If it is smaller, the magnetic carrier is clogged during this and unevenness is likely to occur in the developer layer, and the developer necessary for good development cannot be applied, and only a developed image with a thin density and a large unevenness can be obtained. There is a problem. In order to prevent uneven coating (so-called blade clogging) due to unnecessary particles mixed in the developer, 400 μm or more is preferable. If it is larger than 1000 μm, the amount of the developer applied on the developing sleeve 61 increases and the predetermined developer layer thickness cannot be regulated, so that the magnetic carrier particles adhere to the photosensitive drum 1 more and the developer circulates or does not flow. There is a problem that the regulation of development by the magnetic blade 65 is weakened, toner tribo is insufficient, and fogging easily occurs.

The angle θ1 is -5 ° to 35 °, preferably 0.
The angle is 25 °. When θ1 <−5 °, the thin developer layer formed by the magnetic force, mirroring force, cohesive force, etc. acting on the developer becomes sparse and uneven, and when θ> 35 °, a non-magnetic blade is used. The amount of developer applied increases, and it is difficult to obtain a predetermined amount of developer.

This magnetic carrier particle layer is composed of the sleeve 61.
Even when is driven to rotate in the direction of the arrow, the movement becomes slower as it moves away from the sleeve surface due to the balance between the restraining force based on the magnetic force and gravity and the conveying force in the moving direction of the sleeve 61.
Of course, some of them fall under the influence of gravity.

Therefore, by appropriately arranging the positions of the magnetic poles N ₁ and N ₂ and the fluidity and magnetic characteristics of the magnetic carrier particles, the magnetic carrier particle layer is conveyed in the direction of the magnetic pole N _{1 as} it is closer to the sleeve to form a moving layer. To do. Due to the movement of the magnetic carrier particles, the developer is conveyed to the developing area with the rotation of the developing sleeve 61 and is provided for development. Reference numeral 71 is an upstream side toner scattering suppressing section, and 72 is a downstream side toner scattering suppressing section. The upstream side toner scattering suppressing section 71 and the downstream side toner scattering suppressing section 72 suppress the occurrence of toner scattering.

The measuring method in the present invention will be described below.

(1) The carrier particle size distribution measuring device is a laser diffraction type particle size distribution measuring device HELOS.
(Made by JEOL Ltd.) is equipped with a dry dispersion device RODOS (made by JEOL Ltd.), and the range of 0.05 μm to 200 μm is 3
By dividing into two logarithms, the measurement was performed three times under the condition of a dispersion pressure of 300 kPa, and the average thereof was taken as the volume particle size distribution of the carrier. From there, the carrier particle size according to the present invention and the content of particles having a particle size of 27.5 μm or less were determined. The particle size in the present invention is the median size (50% average particle size).

(2) A BHU-60 type magnetization measuring device (manufactured by Riken Keisoku Co., Ltd.) was used as a measuring device for the magnetic properties of the carrier. About 1.0 g of the measurement sample is weighed and packed in a cell having an inner diameter of 7 mmφ and a height of 10 mm and set in the above-mentioned device. The maximum magnetic field is 238.8 kA / m by gradually applying an applied magnetic field.
Change to (3000 Oersted). Next, the applied magnetic field is reduced to finally obtain the hysteresis curve of the sample on the recording paper. From this, the saturation magnetization, remanent magnetization, and coercive force are obtained.

(3) Method for Measuring Electric Resistance of Carrier Particles The resistance value of carrier particles was measured using the cell shown in FIG. That is, the cell A is filled with carrier particles, the electrodes 11 and 12 are arranged so as to be in contact with the filled carrier particles, a DC voltage of 0.5 to 1 kV is applied between the electrodes, and the current flowing at that time is measured. Sought by. The measurement conditions are as follows: Contact area of the filled carrier particles with the cell S = 2 cm ² , thickness d = 3 mm, upper electrode load 1
It is 5 kg. In addition, 13 is an insulator, 14 is an ampere meter, 15 is a voltmeter, 16 is a voltage stabilizer, 17 is a carrier particle, and 18 is a guide ring.

(4) Particle size distribution of toner (weight average particle size)
The average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II type or a Coulter Multisizer (manufactured by Coulter Co.). In the present invention, a Coulter Multisizer (manufactured by Coulter Co.) is used. An interface (manufactured by Nikkaki Co., Ltd.) that outputs a number distribution and a volume distribution and a PC9801 personal computer (manufactured by NEC) are connected, and a 1% NaCl aqueous solution is prepared using primary sodium chloride as an electrolytic solution. For example, IS
OTON R-II (manufactured by Coulter Scientific Japan) can be used. As a measuring method, a surfactant, preferably an alkylbenzene sulfonate, as a dispersant was added to 100 to 150 ml of the electrolytic aqueous solution in an amount of 0.1%.
Add 1 to 5 ml, and further add 2 to 20 mg of the measurement sample.
The electrolytic solution in which the sample is suspended is subjected to a dispersion treatment for about 1 to 3 minutes by an ultrasonic disperser, and the Coulter Multisizer uses a 100 μm aperture as an aperture to obtain 2 μm.
The volume distribution and the number distribution of the toner of m or more were calculated by measuring the volume and the number of the toner for each channel. Then, the number% of particles having a particle size of 4.00 μm or less according to the present invention.
And the volume-based weight average particle diameter (D ₄ ) determined from the volume distribution was determined.

(5) Measurement of number average particle diameter of external additive (metal compound) The number average particle diameter on the toner particles was observed at 50,000 times using a scanning electron microscope, and 100 particles in the visual field were observed. The particles were qualitatively analyzed by an X-ray microanalyzer (XMA), and the particle size was measured to determine the number average particle size.

(6) Acid value measuring method 2 to 10 g of the sample is weighed in a 200 to 300 ml Erlenmeyer flask, and about 50 ml of a mixed solvent of methanol: toluene = 30: 70 is added to dissolve the resin. If the solubility seems to be poor, a small amount of acetone may be added. Using a mixed indicator of 0.1% bromthymol blue and phenol red, titration was carried out with a previously standardized N / 10 alkaline potassium hydroxide alcohol solution, and the acid value was calculated by the following calculation from the consumption amount.

[0109]     Acid value = KOH solution consumption (ml) × N × 56.1 / sample weight (g) (However, N is a factor of N / 10KOH)

(7) Measurement of glass transition temperature Tg In the present invention, measurement is carried out using a differential thermal analysis measuring device (DSC measuring device), DSC-7 (manufactured by Perkin Elmer Co.). The measurement sample is 5 to 20 mg, preferably 10 mg
Weigh accurately. Put this in an aluminum pan and use an empty aluminum pan as a reference.
The measurement is performed under normal temperature and normal humidity at a temperature rising rate of 10 ° C./min between 200 ° C. and 200 ° C. During this temperature raising process, the temperature is 40 to 100 ° C.
The endothermic peak of the main peak in the range is obtained.
The intersection point between the line at the midpoint of the baseline and the differential heat curve before and after the endothermic peak appears at this time is the glass transition temperature Tg in the present invention.

(8) Measurement of toner viscosity A flow tester CFT-500 type (manufactured by Shimadzu Corporation) is used. A sample weighs about 60 g of a 60 mesh pass product. Using a molding machine, this is pressed for 1 minute with a load of 100 kg / cm ² . This pressurized sample under the following conditions
Under normal temperature and humidity (Temperature approx. 20-30 ° C, Humidity 30-70% R
H) is used for flow tester measurement, and apparent viscosity is approximately vs.
Obtain the temperature curve. From the obtained smooth curve, the sample is 1
The temperature at which a viscosity of 0 ⁵ poise is exhibited is determined.

RATE TEMP 6.0 D / M (° C./min) SET TEMP 50.0 DEG (° C.) MAX TEMP 180.0 DEG (° C.) INTERVAL 3.0 DEG PREHEAT 300.0 SEC (sec) LOAD 20. 0 KGF (kg) DIE (DIA) 1.0 MM (mm) DIE (LENG) 1.0 MM (mm) PLUNGER 1.0 CM ² (cm ² )

(9) Measurement of charge amount FIG. 2 is an explanatory view of an apparatus for measuring the charge amount of toner.
First, in a metal measuring container 22 having a 500 mesh screen 23 on the bottom, about 0.5 to 1.0 g of a mixture of toner and carrier (developer) whose triboelectric charge amount is to be measured.
And put on the lid 24 made of metal. At this time, the total weight of the measurement container 22 is weighed and set as W ₁ (kg). Next, in the suction device 21 (at least the portion in contact with the measurement container 22 is an insulator), suction is performed from the suction port 27 to adjust the air volume control valve 26 to adjust the pressure of the vacuum gauge 25 to 2450 Pa (250 mm.
Aq). In this state, the toner is sucked sufficiently, preferably for about 2 minutes to suck and remove the toner. Electrometer 29 at this time
Is set to V (volt). Here, 28 is a capacitor, and the capacity is C (mF). The weight of the entire measuring container after suction is weighed and is W ₂ (kg). The triboelectric charge amount (mC / kg) of the toner at this time is calculated by the following formula.

Toner triboelectric charge amount (mC / kg) = (C × V) / (W ₁ −W ₂ ).

(10) Measurement of Fog Density The evaluation of fog was conducted by REFLECTOME manufactured by Tokyo Denshoku Co., Ltd.
It was measured with a green filter using TER MODEL TC-6DS and calculated from the following formula. The smaller the number, the less fog.

[0116]

[Equation 1]

(11) Measurement of Hydrophobicity The hydrophobicity defined in this specification is measured by the following methanol titration test. Compound for external addition 0.
2 g are added to 500 ml water in a container. Methanol is measured from the burette until the total amount of external compound is wet. At this time, the solution in the container is constantly stirred with a magnetic stirrer. The end point is observed by suspending the total amount of the external additive compound in the liquid, and the degree of hydrophobicity is expressed as the weight% of methanol in the liquid mixture of methanol and water when the end point is reached.

(12) Measurement of BET Specific Surface Area The BET specific surface area was measured by a BET multipoint method using a fully automatic gas adsorption amount measuring device, Autosorb 1, manufactured by Yuasa Ionics Co., Ltd., using nitrogen as an adsorption gas. Ask. The sample is pretreated by degassing at 50 ° C. for 10 hours.

(13) Measurement of molecular weight of polyolefin resin The molecular weight was measured by Gel Permeation Chromatography (GPC) measuring device manufactured by Waters Co., GPC-15.
It was measured under the following conditions using 0C. Column: GMH-HT 30 cm 2 series (manufactured by Tosoh Corp.) Temperature: 145 ° C. Solvent: o-dichlorobenzene (addition of 0.1% ionol) Flow rate: 1.0 ml / min Sample: 0.15% sample In the case of measuring the molecular weight of 0.4 ml of injected carrier-coated resin, Soxhlet extraction is performed for 20 hours using a toluene solvent, toluene is removed from the extract by an evaporator, etc., and the solid content obtained is used as a sample. The molecular weight of the sample is calculated by using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample.

[0120]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. "Parts" means "parts by weight".

<Invention 1> Carrier Production Example 1 Purified n-heptane (100 ml), magnesium stearate (10 g) and titanium tetrachloride (0.33 g) were placed in a 500 ml flask which had been purged with argon. A contained catalyst component was obtained. 30 prepared separately
1000 ml of purified n-heptane in a 00 ml flask,
600 g of ferrite fine powder having the content shown in Table 1 dehydrated and dried at 150 ° C. under reduced pressure and 0.6 g of titanium-containing catalyst component
(Corresponding to 0.1 mmol) was added, the temperature was raised, and heat treatment was carried out under reflux for 1 hour to obtain a mixture (1). Next, the mixture (1) was placed in an autoclave having a volume of 3000 ml which was replaced with argon, and purified n-heptane was added to bring the total amount to 150.
After adjusting the volume to 0 ml, triethylaluminum (10 mmol) and diethylaluminum monochloride (10 mmol) were added, and the temperature was raised to 80 ° C., then hydrogen was added at 392 kPa (4 kPa).
g / cm ² G) and the total pressure is 882 kPa (9 k
Polymerization reaction was carried out for 30 minutes while continuously supplying ethylene gas so as to maintain g / cm ² G) to obtain a polyolefin resin-coated carrier (1).

Carrier Production Examples 2 to 5 Carrier core materials having the contents shown in Table 1 were used,
Polyolefin resin-coated carriers 2 to 5 were obtained in the same manner as in Carrier Production Example 1.

[0123]

[Table 1]

Black Powder Production Example 1 100 parts of polyester resin obtained by condensing propoxylated bisphenol / ethoxylated bisphenol (molar ratio 1: 1) and fumaric acid / trimellitic acid (molar ratio 19: 1) 5 parts of carbon black ・ 3 parts of chromium compound of di-tert-butylsalicylic acid is sufficiently premixed with a Henschel mixer, melt-kneaded with a twin-screw extruder, cooled, and roughly crushed to about 1 mm with a hammer mill. Then, it was pulverized by an air jet pulverizer. Further, the finely pulverized product obtained was subjected to air classification to obtain a black powder (1) having a weight average particle diameter of 7 μm.

Toner Production Example 1 100 parts of black powder (1) and 1.5 parts of titanium oxide fine powder having a hydrophobic surface (average particle diameter of 0.05 μm) were mixed with a Henschel mixer to prepare toner (1 ) Got.

Toner Production Example 2 100 parts of black powder (1) and 1.5 parts of alumina fine powder having a hydrophobic surface (average particle size 0.04 μm) were mixed with a Henschel mixer to prepare toner (2). Got

According to the above-described analysis method, the physical properties of the toners (1) and (2) are 13 KOHmg / acid value.
g, Tg = 64 ° C., a value showing an apparent viscosity of 10 ⁵ poise was 114 ° C.

Example 1 Toner (1) and carrier (1) were mixed at a toner concentration of 13% to prepare a developer, and the rotation speed of the developer carrying member (sleeve) in the image forming apparatus shown in FIG. A printing durability test was conducted using a color copying machine CLC-500 (manufactured by Canon Inc.) modified so that the peripheral speed ratio was 0.7 times the rotational speed of the photoconductor. First, set the developing device containing the developer at 30 ° C / 9
After performing idle rotation for 2 hours in an environment of 0%, the developing device was returned to the main body of the copying machine and 10000 images were printed using an original document having an image area ratio of 30%. The results are shown in Table 2 together with the following experimental examples. As shown in Table 2, the above-mentioned developers show very good highlights due to little deterioration of charge amount and deterioration of image characteristics in a deterioration test due to idle rotation and a printing durability test, and good transferability can be maintained. Partial image quality was always given, and a result showing very good durability with no spent or toner scattering was obtained.

Example 2 The same experiment as in Example 1 was carried out by changing the toner (1) to the toner (2), and as shown in Table 2, very good transferability (image quality in highlight portion) and durability were obtained. The result showing the sex was obtained.

Example 3 Carrier (1) was changed to carrier (2), and toner density 1
When a developer was prepared by mixing at 0% and the same experiment as in Example 1 was conducted, some toner scattering was observed in the machine after running. It is considered that the carrier surface area was small due to the large carrier particle size and the charging characteristics were deteriorated, but it was at a level where there was no problem in practical use, and there were no problems with other characteristics.

Example 4 When the carrier (1) was changed to the carrier (3) and the same experiment as in Example 1 was carried out, as shown in Table 2, very good transferability (image quality in highlight portion) and durability were obtained. The result showing the sex was obtained.

Examples 5, 6 When the same experiment as in Example 1 was conducted by changing the carriers (1) to the carriers (4) and (5), a slight amount of toner spent was observed on the surface of the carrier after the durability test. It was This may be because the adhesion or the catalytic activity of the polymerization catalyst is somewhat insufficient because the core material component does not contain an alkaline earth metal, but there is no problem in practical use, and other durability characteristics are also shown in Table 2. As a result, no particular problem was obtained.

[0133]

[Table 2] In the table, ◯: Very good △: No problem in practical use ×: Problem (not practical)

<Invention 2> Carrier Production Example 6 Purified n-heptane (100 ml), magnesium stearate (10 g) and titanium tetrachloride (0.33 g) were placed in a 500 ml flask which had been purged with argon. A contained catalyst component was obtained. 30 prepared separately
1000 ml of purified n-heptane in a 00 ml flask,
600 g of ferrite fine powder having the composition shown in Table 3 dehydrated and dried at 150 ° C. under reduced pressure and titanium-containing catalyst component 0.6
g (corresponding to 0.1 mmol) was added, the temperature was raised, and heat treatment was carried out under reflux for 1 hour to obtain a mixture (6). Next, the mixture (6) was placed in an autoclave having a volume of 3000 ml which was replaced with argon, and purified n-heptane was added to bring the total amount to 15 ml.
After adjusting the volume to 00 ml, triethyl aluminum (10 mmol) and diethyl aluminum monochloride (10 mmol) were added, and the temperature was raised to 80 ° C.
kg / cm ² G) and the total pressure is 882 kPa (9
Polymerization reaction was carried out for 40 minutes while continuously supplying ethylene gas so as to maintain the content at kg / cm ² G) to obtain a polyolefin resin-coated carrier (6) having the physical properties shown in Table 3.

Carrier Production Examples 7 to 11 Carrier core materials having the contents shown in Table 3 were used,
The polyolefin resin-coated carriers (7) to (11) shown in Table 3 were obtained in the same manner as in Carrier Production Example 6.

[0136]

[Table 3]

Black Powder Production Examples 2 and 3 Polyester resin obtained by condensing propoxylated bisphenol / ethoxylated bisphenol (molar ratio 1: 1) and fumaric acid / trimellitic acid (molar ratio 19: 1) 100 Part-carbon black 4 parts-di-tert-butylsalicylic acid chromium compound 3 parts were sufficiently premixed by a Henschel mixer, melt-kneaded by a twin-screw extruder kneader, and cooled to about 1 mm using a hammer mill. Coarse pulverization was performed, and then fine pulverization was performed by a fine pulverizer using an air jet system. Further, the obtained finely pulverized product was subjected to air classification to obtain a black powder (2) having a weight average particle diameter of 7 μm and a black powder (3) having a weight average particle diameter of 10 μm.

Toner Production Example 3 100 parts of black powder (2) and 3.0 parts of finely powdered titanium oxide (average particle size 0.05 μm) whose surface was hydrophobized were mixed with a Henschel mixer to prepare toner (3 ) Got.

Toner Production Example 4 100 parts of black powder (2) and 3.0 parts of alumina fine powder whose surface was treated to be hydrophobic (average particle size 0.04 μm) were mixed with a Henschel mixer to prepare toner (4). Got

Toner Production Example 5 100 parts of black powder (3) and 3.0 parts of the titanium oxide fine powder used in Toner Production Example 3 were mixed with a Henschel mixer to obtain Toner (5).

According to the above-described analysis method, the physical properties of the toners (3) to (5) are 14 KOHmg / acid value.
g, Tg = 63 ° C., a value showing an apparent viscosity of 10 ⁵ poise was 116 ° C.

Example 7 Toner (3) and carrier (6) were mixed at a toner concentration of 8% to prepare a developer, and a color copying machine CLC-500 (manufactured by Canon Inc.) was used as an image forming apparatus shown in FIG. Use 3
Image area ratio 30% under 0 ° C / 90% temperature / humidity environment
A printing endurance test was performed by using 10000 sheets of the original original document, and after the test, the state of scratches on the photoconductor was visually observed. The results are shown in Table 4 together with the results of durability together with the following experimental examples. As shown in Table 4, in the printing durability test, the above-mentioned developers have little change in charge amount and deterioration of image characteristics, and neither the spent of the carrier nor the scattering of the toner are observed, and the developer is tested on the photoreceptor. Results were obtained showing very good durability with no visible scratches.

Example 8 The same experiment as in Example 7 was carried out by changing the toner (3) to the toner (4), and as shown in Table 4, very good results were obtained.

Example 9 Toner (5) and carrier (6) were mixed at a toner concentration of 10% to prepare a developer, and the same experiment as in Example 7 was carried out. Some scratches were seen. It is considered that an additive that was not retained on the toner surface was generated due to the large toner particle size and the small toner surface area.
There was no problem on the image.

Example 10 The carrier (6) was changed to the carrier (7), and the toner density was 6
%, A developer was prepared and the same experiment as in Example 7 was carried out. As a result, some toner scattering was observed in the machine after running.
Some scratches were also found on the photoconductor. It is considered that this is because the carrier surface area was small due to the large carrier particle size, and the charge imparting ability to the additive was lowered, but there was no problem in practical use, and other properties were also satisfactory.

Example 11 When the carrier (6) was changed to the carrier (8) and the same experiment as in Example 7 was conducted, very good results were obtained as shown in Table 4.

Example 12 The same experiment as in Example 7 was carried out except that the carrier (6) was changed to the carrier (9). As a result, a small amount of toner was scattered in the machine after the durability test and a slight scratch was observed on the photosensitive member. Was given. It is considered that the charging speed was lowered due to the high resistance of the carrier, but the level was practically no problem, and other characteristics were also satisfactory.

Example 13 The same experiment as in Example 7 was carried out by changing the carrier (6) to the carrier (10). As a result, some toner scattering was observed in the machine after running and some scratches were observed on the photoconductor. Was given. It is thought that this is because the charge-providing ability under high humidity decreased due to the low resistance of the carrier.
There were no problems with other characteristics.

Example 14 When the carrier (6) was changed to the carrier (11) and the same experiment as in Example 7 was carried out, some scratches were found on the photoreceptor after running. Ferrite constituent A (in this case Mg
It is considered that the charging rate of the additive was decreased due to the small content of O), but it was at a level with no problem in practical use, and there were no problems with other characteristics.

Example 15 An experiment similar to that of Example 7 was carried out except that the toner concentration was set to 14%. As a result, a small amount of toner was scattered in the machine after running, and a slight scratch was also observed on the photosensitive member. It is considered that the charging speed was lowered due to the high toner concentration, but the level was practically satisfactory, and other characteristics were also satisfactory.

[0151]

[Table 4] In the table, ◯: Very good △: No problem in practical use

<Invention 3> Carrier Production Example 12 Purified n-heptane (100 ml), magnesium stearate (10 g) and titanium tetrachloride (0.33 g) were placed in a 500 ml flask which had been purged with argon. A contained catalyst component was obtained. 30 prepared separately
Purified n-heptane (1000 ml) in a 0 ml flask and ferrite fine powder (600 g) dehydrated and dried at 150 ° C. under reduced pressure.
Then, 0.6 g of titanium-containing catalyst component (corresponding to 0.1 mmol) was added, the temperature was raised, and the mixture was heated for 1 hour under reflux to obtain a mixture (12). Next, the volume replaced with argon 30
Put the mixture (12) in a 00 ml autoclave,
Purified n-heptane was added to bring the total volume to 1500 ml, then 10 mmol of triethylaluminum and 10 mmol of diethylaluminum monochloride were added, and 8
After the temperature was raised to 0 ° C., hydrogen was added at 392 kPa (4 kg / cm
² G) and the total pressure is 882 kPa (9 kg / cm ²
3) While continuously feeding ethylene gas to maintain G) 3
Polymerization reaction was carried out for 0 minutes to obtain a polyolefin resin-coated carrier (12) (weight average molecular weight of coating resin: 360000, number average molecular weight 9500) having the physical properties shown in Table 5.

Carrier Production Example 13 Ferrite fine powder 600 in Carrier Production Example 12
Further, carbon black was added to 0. By adding 1 g, a polyolefin resin-coated carrier (13) having physical properties shown in Table 5 was obtained.

Carrier Production Example 14 Using 400 parts of a low-density polyethylene resin xylene solution (polyethylene resin solid content: 0.5% by weight), 100 parts of the ferrite fine powder used in Carrier Production Example 12 was added to a spira coater (Okada Seiko). Polyethylene resin was applied by the company) to obtain a polyolefin resin-coated carrier (14) having the physical properties shown in Table 7 (weight average molecular weight of coating resin: 35,000, number average molecular weight: 9400).

Carrier Production Examples 15 to 19 In the Carrier Production Example 12, by changing the ferrite fine powder or the polymerization conditions variously, the polyethylene resin coated carriers (15) to (1) having the physical properties shown in Table 5 are prepared.
9) was obtained.

[0156]

[Table 5]

Black Powder Production Example 4 Polyester resin obtained by condensing propoxylated bisphenol / ethoxylated bisphenol (molar ratio 1: 1) and fumaric acid / trimellitic acid (molar ratio 19: 1) (solubility parameter : 22.1 (J / cm ³ ) ^1/2 ) 100 parts-Polypropylene 2 parts-Carbon black 5 parts-Di-tert-butylsalicylic acid chromium compound 5 parts sufficiently premixed with a Henschel mixer, and biaxial extrusion The mixture was melt-kneaded by a type kneader, cooled, coarsely pulverized to about 1 mm using a hammer mill, and then finely pulverized by a fine pulverizer by an air jet system. Further, the obtained finely pulverized material was subjected to air classification to obtain a black powder (4) having a weight average particle diameter of 7 μm.

Black Powder Production Example 5 Black powder (5) having a weight average particle diameter of 10 μm was obtained by the same material and method as in Black powder production 4.

Black Powder Production Examples 6 to 9 In Black Powder Production Example 4, black powders (6) to (9) were prepared by adjusting the molar ratio of propoxylated bisphenol / ethoxylated bisphenol and the amount of trimellitic acid added. Got

Black Powder Production Example 10 A black powder (10) was obtained in the same manner as in Black Powder Production Example 4 without using polypropylene in Black Powder Production Example 4.

Black Powder Production Example 11 Black powder production example except that a styrene-n-butyl acrylate-methyl acrylate resin (solubility parameter: 18.2 (J / cm ³ ) ^1/2 ) was used in place of the polyester resin. Black powder (11) was obtained in the same manner as in 4.

Black Powder Production Example 12 Butadiene-styrene-isobutylene resin (solubility parameter: 16.8 (J / c
Black powder (12) was obtained in the same manner as in Black Powder Production Example 4 except that m ³ ) ^1/2 ) was used.

Black Powder Production Examples 13 and 14 Black powder (13) having a weight average particle diameter of 8.6 μm and 8.8 μm was produced by using the same material and method as in Black Powder Production Example 4.
(14) was obtained.

Toner Production Example 6 100 parts of black powder (4) and fine particles of amorphous titanium oxide having a hydrophobic surface (BET specific surface area 130 m
² / g, hydrophobicity 71%, average particle size 0.03 μm) 1.
5 parts were mixed with a Henschel mixer to obtain a toner (6) having the content shown in Table 6.

Toner Production Example 7 100 parts of black powder (4) and 2.5 parts of the titanium oxide fine powder used in Toner Production Example 6 were mixed with a Henschel mixer, and toner (7) having the content shown in Table 6 was obtained. Got

Toner Production Example 8 100 parts of black powder (4) and finely divided amorphous titanium oxide powder having a hydrophobic surface (BET specific surface area 91 m ²
/ G, hydrophobicity 80%, average particle size 0.04 μm) 1.5
Were mixed with a Henschel mixer to obtain a toner (8) having the content shown in Table 6.

Toner Production Example 9 100 parts of black powder (4) and finely divided amorphous titanium oxide powder having a hydrophobic surface (BET specific surface area of 87 m ²
/ G, hydrophobicity 73%, average particle size 0.04 μm) 1.5
Were mixed with a Henschel mixer to obtain Toner (9) having the content shown in Table 6.

Toner Production Example 10 100 parts of black powder (4) and 0.35 part of the titanium oxide fine powder used in Toner Production Example 6 were mixed with a Henschel mixer, and toner (10) having the content shown in Table 6 was mixed. Got

Toner Production Example 11 100 parts of black powder (4) and anatase type titanium oxide fine powder having a hydrophobic surface (BET specific surface area 100 m ²
/ G, hydrophobicity 61%, average particle size 0.05 μm) 1.5
Were mixed with a Henschel mixer to obtain a toner (11) having the content shown in Table 6.

Toner Production Examples 12 and 13 100 parts of black powder (4) and γ- whose surface was treated to be hydrophobic.
Alumina fine powder (BET specific surface area 170 m ² / g, hydrophobicity 67%, average particle size 0.03 μm) 1.5 parts, or silica fine powder (BET specific surface area 110 m ² / g, hydrophobicity 73%, average) 1.5 parts of a particle size of 0.03 μm) were mixed with a Henschel mixer, and the toner (1
2) and (13) were obtained.

Toner Production Example 14 100 parts of the black powder (5) and 1.0 part of the amorphous titanium oxide fine powder used in Toner Production Example 6 were mixed with a Henschel mixer, and the toner having the content shown in Table 6 ( 14)
Got

Toner Production Examples 15 to 23 100 parts of black powders (6) to (14) and Toner Production Example 6
The amorphous titanium oxide fine powder (1.5 parts) used in (1) was mixed with a Henschel mixer to obtain toners (15) to (23) having the contents shown in Table 6.

[0173]

[Table 6]

Example 16 Toner (6) and carrier (12) were mixed at a toner concentration of 7% to prepare a developer, and a color copying machine CLC-500 (manufactured by Canon Inc.) was used as an image forming apparatus shown in FIG. Used,
Under an environment of 20 ° C / 10%, first, an original document with an image area ratio of 25% is used to output 10,000 sheets, and then an original document with an image area ratio of 5% is used to make another 1
0000 sheets were printed. The results are shown in Table 7 together with the following experimental examples. As shown in Table 7, the above-mentioned developers showed little change in charge amount and no deterioration in image characteristics in the printing endurance test, and results showing very good durability with no spent or toner scattering.

Example 17 Example 16 using Toner (7) and Carrier (12)
When an experiment similar to the above was conducted, the charge amount was slightly decreased and the fog was slightly deteriorated with the endurance, and some carrier spent was observed in the SEM observation of the carrier surface after the endurance. The value of BET specific surface area of external additive x external addition amount is 32
Since it is as high as 5, it is considered that the reverse reaction of the repair reaction of the coating resin is likely to proceed, but it was at a level with no problem in practical use.

Example 18 Example 16 using Toner (8) and Carrier (12)
When an experiment similar to the above was conducted, the charge amount slightly increased with durability, and the image density slightly decreased. Moreover, some carrier spent was observed in the SEM observation of the carrier surface after the durability test. This is probably because the degree of hydrophobicity of the external additive was high, but there was no problem in practical use.

Example 19 Example 16 using toner (9) and carrier (12)
When an experiment similar to the above was conducted, the charge amount was slightly decreased and the fog was slightly deteriorated with the endurance, and some carrier spent was observed in the SEM observation of the carrier surface after the endurance. Since the BET specific surface area of the external additive is small, it is considered that the repair reaction of the coating resin is small, but the level was practically no problem.

Example 20 Example 1 using the toner (10) and the carrier (12)
When the same experiment as in Example 6 was conducted, the charge amount was slightly decreased and the fog was slightly deteriorated with the endurance, and some carrier spent was observed in the SEM observation of the carrier surface after the endurance. The value of BET specific surface area of external additive x external addition amount is 4
Since it is as small as 6, it is considered that the repair reaction of the coating resin is small, but there was no problem in practical use.

Example 21 Example 1 using toner (11) and carrier (12)
When the same experiment as in Example 6 was conducted, the charge amount was slightly decreased and the fog was slightly deteriorated with the endurance, and some carrier spent was observed in the SEM observation of the carrier surface after the endurance. The external additive is anatase-type titanium, and it is considered that the anionic polymerization catalytic ability is not high because of its crystal structure, but it was at a level where there was no problem in practical use.

Example 22 Example 1 using the toner (12) and the carrier (12)
When an experiment similar to that of No. 6 was performed, very good results were obtained as shown in Table 7.

Example 23 Example 16 using Toner (6) and Carrier (13)
When the same experiment was conducted, very good results were obtained as shown in Table 7.

Example 24 Example 16 using Toner (6) and Carrier (14)
When the same experiment was conducted, a slight decrease in the charge amount and a slight deterioration in fog were observed with the endurance, some carrier spent was observed in the SEM observation of the carrier surface after the endurance, and some toner was left inside the machine. Scattering was also seen. Since the method of coating the carrier is a wet coating method, the state of polyethylene resin coating may be non-uniform, and the state of triboelectrification of the toner may not be uniform, but this was at a practically acceptable level.

Example 25 Toner (6) and carrier (15) were mixed at a toner concentration of 5% to prepare a developer, and the same experiment as in Example 16 was conducted. In addition, a slight deterioration in fog was observed, and some toner scattering was observed in the machine after running. It is considered that the charging speed was insufficient due to the small carrier surface area, but it was at a level where there was no practical problem.

Example 26 Example 16 was carried out using Toner (6) and Carrier (16).
When an experiment similar to the above was conducted, some carrier spent was observed in the SEM observation of the carrier surface after the durability test. It is considered that the toner, which is hard to develop because the resistance of the carrier is too high, stayed on the carrier for a long time.
It was a level with no problems in practical use.

Example 27 Example 16 using Toner (6) and Carrier (17)
When the same experiment was carried out, the image quality of the obtained image was not good because the resistance of the carrier was too low, and the fog was a little worse, but the result showed durability showing no problem in practical use.

Example 28 Example 16 using Toner (6) and Carrier (18)
When an experiment similar to the above was conducted, some carrier spent was observed in the SEM observation of the carrier surface after the durability test. It is considered that the saturation magnetization of the carrier was too high, which promoted the deterioration of the developer at the time of mixing in the developing device.

Example 29 Example 16 using Toner (6) and Carrier (19)
When the same experiment was carried out, in addition to a slight amount of carrier adhesion, the amount of electrification decreased a little with the endurance, and some toner scattering was observed in the machine after the endurance. It is considered that the saturation magnetization of the carrier was too low and the developer and the replenishment toner were not sufficiently mixed, but the level was practically no problem.

Reference Example 1 Toner (14) and carrier (12) were mixed with a toner concentration of 9%.
When a developer was prepared by mixing the above, and the same experiment as in Example 16 was carried out, the durability was good, but the image quality was not so good throughout the durability due to the large toner particle size.

Example 30 Example 1 using the toner (15) and the carrier (12)
When an experiment similar to that of No. 6 was conducted, the amount of electrification was slightly decreased with the endurance, and the toner was slightly scattered in the machine after the endurance with some deterioration of fog. It is considered that the charging rate was slow because the acid value of the toner was low, but it was at a level where there was no problem in practical use.

Example 31 Example 1 using toner (16) and carrier (12)
When an experiment similar to that of No. 6 was conducted, the amount of electrification was slightly decreased with the endurance, the fog was deteriorated, and some toner was scattered in the machine after the endurance. It is considered that the high acid value of the toner caused the charge on the toner to leak and the charge amount to decrease, but it was at a level where there was no problem in practical use.

Reference Example 2 Example 1 using toner (17) and carrier (12)
When an experiment similar to that of No. 6 was performed, the amount of electrification decreased a little with the endurance, deterioration of fog and some toner scattering in the machine after the endurance were observed, and some carrier spent was observed in the SEM observation of the carrier surface after endurance. I was seen. It is considered that the deterioration resistance of the toner is low because the temperature at which the toner has a Tg and a viscosity of 10 ⁵ poise is low, but this is at a practically acceptable level.

Reference Example 3 Example 1 using the toner (18) and the carrier (12)
When an experiment similar to that of 6 was performed, the Tg and 10
^Although the fixing property of the toner was poor and the image density was low because the temperature showing the viscosity of ⁵ poise was high, the result showing very good durability was obtained.

Example 32 Example 1 using the toner (19) and the carrier (12)
When an experiment similar to that of No. 6 was performed, the amount of electrification decreased a little with the endurance, deterioration of fog and some toner scattering in the machine after the endurance were observed, and some carrier spent was observed in the SEM observation of the carrier surface after endurance. Although seen,
It was a level with no problems in practical use.

Example 33 Example 1 using toner (20) and carrier (12)
When an experiment similar to that of No. 6 was performed, very good results were obtained as shown in Table 7.

Example 34 Example 1 using the toner (21) and the carrier (12)
When an experiment similar to that of No. 6 was performed, the amount of electrification decreased a little with the endurance, deterioration of fog and some toner scattering in the machine after the endurance were observed, and some carrier spent was observed in the SEM observation of the carrier surface after endurance. I was seen. Due to the low solubility parameter of the resin used to make the toner,
This is probably because the carrier had a high affinity with the polyethylene resin, which is a carrier coat resin, and the carrier was likely to be spent, but there was no problem in practical use.

Example 35 Toner (22) and carrier (12) were mixed with a toner density of 9%.
When a developer was prepared by mixing the above, and the same experiment as in Example 16 was carried out, both the image quality and the durability were good.

Reference Example 4 Toner (23) and carrier (12) were mixed in a toner concentration of 9%.
When a developer was prepared by mixing the above, and the same experiment as in Example 16 was carried out, the durability was good, but the image quality was deteriorated because there were few toner particles of 4 μm or less.

Example 36 The same experiment as in Example 16 was carried out except that the toner concentration was set to 1%. As a result, the deterioration of the image quality was remarkable, but the other durability was as shown in Table 7. It was good.

Example 37 An experiment similar to that of Example 16 was carried out except that the toner concentration was set to 16%. As a result, fog was not so good, and some toner scattering was observed in the machine after running, but there was a problem in practical use. There was no level.

Comparative Example 1 An experiment similar to that of Example 16 was carried out using the uncoated product of ferrite fine powder used in Carrier Production Example 12 and Toner (6). Deterioration, toner scattering and carrier spent in the machine after running were observed.

Reference Example 5 Example 1 using toner (13) and carrier (12)
When the same experiment as in Example 6 was conducted, the charge amount decreased with the endurance, deterioration of fog, toner scattering in the machine after endurance, and carrier spent were observed. When hydrophobized silica having no polymerization catalytic ability was used as an external additive, abrasion and peeling of the coating layer due to durability could not be repaired, and carrier spent was generated and grown on the deteriorated carrier surface portion.

[0202]

[Table 7] In the table, ○: Very good △: No problem in practical use
×: There is a problem

[0203]

The carrier of the present invention has a high charging speed,
It has a high charge amount imparting ability and durability, and an electrophotographic developer using this carrier exhibits excellent durability and can stably maintain good image characteristics.

[Brief description of drawings]

FIG. 1 is an illustration of an apparatus for measuring the resistance of carriers.

FIG. 2 is an explanatory diagram of an apparatus for measuring a toner charge amount.

FIG. 3 is a schematic view of an image forming apparatus used in the image forming method of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Okado 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuya Ida 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. Incorporated (72) Inventor Iku Iku 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Motoki Hisaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-4-70857 (JP, A) JP-A-5-204184 (JP, A) JP-A-8-202084 (JP, A) (58) Fields investigated (Int. Cl. ⁷⁾ , DB name) G03G 9/08-9/113

Claims (49)

(57) [Claims] 1. A carrier for electrophotography having magnetic ferrite powder, the surface of which is coated with a polyolefin resin layer, wherein the ferrite powder is represented by the following formula (1) (Fe ₂ O ₃ ) x (MnO) y (A). z Formula (1) [wherein A represents Na ₂ O, K ₂ O, CaO, SrO or a mixture thereof, x, y and z represent mole fractions, and the following condition 0.3 <x < 0.8, 0.01 <y <0.5, 0 <z <
0.69 and x + y + z ≦ 1 are satisfied. ] A carrier for electrophotography, which is composed of a ferrite component represented by: and the polyolefin resin layer is directly polymerized and coated on the surface of the carrier. 2. The values of x, y and z in the formula (1) are as follows: 0.3 <x <0.8, 0.01 <y <0.5, 0 <z <
0.69, x + y <1, z = 1-x-y electrophotographic carrier according to claim 1, characterized by satisfying the. 3. The electrophotographic carrier according to claim 1 or 2 , wherein the carrier has a volume median diameter of 10 to 60 μm. Wherein said carrier is an electrophotographic carrier according to any one of claims 1 to 3, characterized by having a resistance value of 10 ⁶ to 10 ¹¹ [Omega] cm at a voltage of a 0.5KV～1kV. 5. The carrier is 79.6 kA / m (10
Saturation magnetization of 15-
Claim, characterized in that with values of 85Am ² / kg 1
5. The electrophotographic carrier according to any one of 1 to 4 . 6. In an electrophotographic developer having at least a toner and a carrier, the carrier has a magnetic ferrite powder whose surface is coated with a polyolefin resin layer, and the ferrite powder has the following formula (1): ) (Fe ₂ O ₃ ) x (MnO) y (A) z Formula (1) [wherein A represents Na ₂ O, K ₂ O, CaO, SrO or a mixture thereof, and x, y and z are Indicates the mole fraction, and the following conditions 0.3 <x <0.8, 0.01 <y <0.5, 0 <z <
0.69 and x + y + z ≦ 1 are satisfied. ] It is comprised by the ferrite component shown by these, The said polyolefin resin layer is carrying out direct polymerization coating on the carrier surface, The electrophotographic developer characterized by the above-mentioned. 7. The following conditions 0.3 <x <0.8, 0.01 <y <0.5, 0 <z <are defined as x, y and z in the formula (1).
The developer for electrophotography according to claim 6 , which satisfies 0.69, x + y <1, z = 1-xy. 8. The carrier, electrophotographic developer according to claim 6 or 7 characterized by having a volume median diameter of 10 to 60 [mu] m. 9. The carrier is, 10 ⁶ 10 ¹¹ electrophotographic developer according to any one of claims 6 to 8, characterized by having a resistance value of the Ωcm in the voltage of a 0.5kV~1kV . 10. The carrier is 79.6 kA / m (1
000 oersted) applied magnetic field has a saturation magnetization of 15
A value of ˜85 Am ² / kg.
The developer for electrophotography according to any one of 6 to 9 . 11. The toner has a weight average particle diameter of 1 to 9 μm.
The electrophotographic developer according to any one of claims 6 to 10 , further comprising: 12. The toner, a toner for electrophotography having at least a binder resin and a colorant, any of claims 6 to 11, characterized in that the toner has an acid value 1~30KOHmg / g The developer for electrophotography according to Crab. 13. The glass transition temperature of the toner is 45-7.
The electrophotographic developer according to any one of claims 6 to 12 , which is in the range of 0 ° C. 14. The electrophotographic developer according to claim 6, wherein the toner has an apparent viscosity of 10 ⁵ poise in a range of 80 to 120 ° C. 15. The toner, an electrophotographic developer according to any one of claims 6 to 14, characterized in that it contains a compound comprising a metal capable of constituting at least anionic polymerization catalyst as an external additive. 16. The electrophotographic developer according to claim 15 , wherein the metal capable of forming the anionic polymerization catalyst has a bond distance with oxygen of 1.7 Å or more. 17. external additive, an electrophotographic developer according to claim 15 or 16, characterized in that a metal oxide having an average particle diameter 0.005~0.2μm having been hydrophobic-treated . 18. external additive, claims 15 to 1, characterized in that an aluminum compound and / or titanium compound
7. The electrophotographic developer according to any one of 7 . 19. The toner density in the developer is 2-1.
The electrophotographic developer according to any one of claims 6 to 18 , which is 5% by weight. 20. In an electrophotographic developer having at least a toner and a carrier, the carrier has a magnetic ferrite powder whose surface is coated with a polyolefin resin layer, and the ferrite powder has the following formula (2): _{) (Fe 2 O 3) x} (a) y (B) z formula (2) wherein, a represents an MgO or Ag ₂ O or MgO + Ag ₂ O, B is _{Li 2 O, MnO 2, CaO} , SrO , Al ₂
Represents one or more metal elements selected from the group consisting of O ₃ and SiO ₂ , x, y and z represent weight ratios, and the following conditions 0.2 ≦ x ≦ 0.95, 0.005 ≦ y ≦ 0.3, x +
It satisfies y + z ≦ 1. ] The polyolefin resin layer is directly polymerized and coated on the carrier surface.
And the toner has an apparent viscosity of 10 ⁵ poise at a temperature of 8
A developer for electrophotography, which is in the range of 0 to 120 ° C. 21. The electrophotographic developer according to claim 20 , wherein the carrier has a volume median diameter of 10 to 60 μm. 22. The carrier, electrophotographic developer according to claim 20 also 21 characterized as having a resistance of 10 ⁶ to 10 ¹¹ [Omega] cm at a voltage of a 0.5KV～1kV. 23. The carrier is 79.6 kA / m (1
000 oersted) applied magnetic field has a saturation magnetization of 15
A value of ˜85 Am ² / kg.
23. The electrophotographic developer according to any one of 20 to 22 . 24. The toner has a weight average particle diameter of 1 to 9 μm.
The electrophotographic developer according to any one of claims 20 to 23 , comprising: 25. The toner, a toner for electrophotography having at least a binder resin and a colorant, any of claims 20 to 24, characterized in that the toner has an acid value 1~30KOHmg / g The developer for electrophotography according to Crab. 26. The glass transition temperature of the toner is 45-7.
Claim, characterized in that in the range of 0 ° C. 20 to 25
The developer for electrophotography according to any one of 1. 27. The toner, an electrophotographic developer according to any one of claims 20 to 26, characterized in that it contains a compound comprising a metal capable of constituting at least anionic polymerization catalyst as an external additive. 28. The electrophotographic developer according to claim 27 , wherein the metal capable of forming the anionic polymerization catalyst has a bond length with oxygen of 1.7 Å or more. 29. external additive, an electrophotographic developer according to claim 27 or 28, characterized in that a metal oxide having an average particle diameter 0.005~0.2μm having been hydrophobic-treated . 30. external additive, according to claim 27 or 2, characterized in that an aluminum compound and / or titanium compound
9. The electrophotographic developer according to any of 9 . 31. The toner concentration in the developer is 2-1.
The electrophotographic developer according to any one of claims 20 to 30 , which is 5% by weight. 32. An electrophotographic developer having at least a toner and a carrier, wherein the carrier has a magnetic core material surface and a polyolefin resin layer coating the magnetic core material surface, and the toner has a weight average particle size. Diameter 3-9 μm, particle size 4.0
0μm the following toner particles contain 10 to 70% by number, and containing a metal compound capable of constituting at least anionic polymerization catalyst as an external additive, the toner has a temperature indicating an apparent viscosity of 10 ⁵ poise 8
A developer for electrophotography, which is in the range of 0 to 120 ° C. 33. The electrophotographic developer according to claim 32 , wherein the polyolefin resin layer is obtained by directly polymerizing and coating the surface of the magnetic core material. 34. The polyolefin resin layer is in the molecular weight distribution obtained by GPC molecular weight measurement, claim, wherein the weight-average molecular weight of 5,000 or more 32
Or the developer for electrophotography according to 33 . 35. The polyolefin resin layer is in the molecular weight distribution obtained by GPC molecular weight measurement, development for electrophotography according to claim 32 or 33, wherein the weight-average molecular weight in the range of 7000 to 700,000 Agent. 36. The polyolefin resin layer is in the molecular weight distribution obtained by GPC molecular weight measurement, development for electrophotography according to claim 32 or 33, wherein the weight-average molecular weight in the range of 30000 to 700000 Agent. 37. The polyolefin resin layer is in the molecular weight distribution obtained by GPC molecular weight measurement, development for electrophotography according to claim 32 or 33, wherein the weight-average molecular weight in the range 50,000 to 500,000 Agent. 38. The polyolefin resin layer is in the molecular weight distribution obtained by GPC molecular weight measurement, an electron according to any one of claims 34 to 37, wherein the number-average molecular weight in the range of 2000 to 30000 Photographic developer. 39. Metal capable of constituting the anionic polymerization catalyst, the electrophotographic developing according to any one of claims 32 to 38, characterized in that it has a value of more than 1.7Å as binding distances between oxygen Agent. 40. The carrier has a volume median diameter of 10 to 60 [mu] m, according to claim 32 or 39, characterized by containing the following carrier particles 27.5 1.0-80 wt% The electrophotographic developer according to any one of claims. 41. The carrier is 10 ⁶ to 10 ¹¹ electrophotographic developer according to any one of claims 32 to 40, characterized by having a resistance value of the Ωcm in the voltage of a 0.5kV~1kV . 42. The carrier is 79.6 kA / m (1
000 oersted) applied magnetic field has a saturation magnetization of 15
A value of ˜85 Am ² / kg.
32. The electrophotographic developer according to any one of 32 to 41 . 43. The toner, a toner for electrophotography having at least a binder resin and a colorant, any of claims 32 to 42, characterized in that the toner has an acid value 1~30KOHmg / g The developer for electrophotography according to Crab. 44. The glass transition temperature of the toner is 45 to 7.
Claims 32 through 43, characterized in that in the range of 0 ℃
The developer for electrophotography according to any one of 1. 45. A external additive, electrophotography according to any one of claims 32 to 44, characterized in that a metal oxide having an average particle diameter 0.005~0.2μm having been hydrophobic-treated Developer. 46. A external additive, according to claim 32 to 4, characterized in that an aluminum compound and / or titanium compound
5. The electrophotographic developer according to any one of 5 above. 47. The toner concentration in the developer is 2-1.
Electrophotographic developing agent according to any one of claims 32 to 46, characterized in that 5 percent by weight. 48. A two-component developer having a toner and a carrier is circulated and conveyed by a developer carrying member, and the electrostatic latent image held on the electrostatic latent image carrying member in the developing area is transferred to the developer carrying member. In the image forming method of developing with a toner of the carried two-component developer, the carrier has a magnetic core material surface and a polyolefin resin layer coating the magnetic core material surface, and the toner is 3. having a weight average particle size of 3 to 9 μm and a particle size of 4.
10 to 70% by number of toner particles having a size of 00 μm or less are contained,
Contains at least anionic polymerization catalyst of the metal capable of constituting the compound as an external additive, the toner may comprise a compound of a metal capable of constituting at least anionic polymerization catalyst as an external additive, the toner has
The temperature showing an apparent viscosity of 10 ⁵ poise is 80 to 120 ° C.
The image forming method is characterized in that 49. The two-component developer according to claim 33.
49. The image forming method according to claim 48 , wherein the electrophotographic developer is any one of 47 .