JP6930358B2 - Carrier, developer, developer accommodating unit, image forming apparatus and image forming method - Google Patents

Description

The present invention relates to a carrier, a developer, a developer accommodating unit, an image forming apparatus, and an image forming method.

In image formation by the electrophotographic method, an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductive substance, and a charged toner is adhered to the electrostatic latent image to form a toner image. After that, the toner image is transferred to a recording medium, fixed, and becomes an output image. In recent years, the technology of copiers and printers using the electrophotographic method has been rapidly expanding from monochrome to full color, and the full color market tends to expand.

In full-color image formation, generally, three color toners of yellow, magenta, and cyan, or four color toners in which black is added are laminated to reproduce all colors. Therefore, in order to obtain a clear full-color image with excellent color reproducibility, it is necessary to smooth the surface of the fixed toner image to reduce light scattering. For this reason, many latent image images of conventional full-color copiers and the like achieve high gloss by increasing the amount of toner adhered to the electrostatic latent image in order to achieve smoothness of the toner image. Therefore, in the case of long-term printing, there is a problem of toner spending in which deteriorated toner adheres to the carrier surface. Among the carrier deterioration caused by the toner spend, the problems are an increase in carrier resistance and a decrease in carrier charging ability. When the charging capacity of the carrier is reduced, it becomes difficult to hold the toner due to the electrostatic attraction, and the toner is scattered in the developing machine, so-called toner scattering occurs, and the inside of the machine is contaminated, resulting in false detection of the sensor. It causes a malfunction.

Moreover, in the field of production printing, whose market has been expanding in recent years, higher image quality than ever is required. Further, by performing high-speed development, a strong stress is applied inside the developing machine, the carrier coating resin is worn and the core material is exposed, so that the carrier is transferred onto the electrostatic latent image carrier, so-called carrier adhesion occurs. However, there is a problem that white spots appear at the edges and center of the image. In recent years, the demand for this issue has become even more severe.
On the other hand, in order to prevent carrier adhesion, it is possible to maintain the resistance at a high level by designing the carrier resistance at a high level from the initial stage, but in that case, the charge on the carrier surface is appropriate immediately after development. There is a problem that the edge becomes thin when printing halftone, for example.

From the above, it is necessary to maintain the resistance and charge at an appropriate level by containing a conductive substance and a chargeable substance together in the coating resin as the carrier resistance for high quality stabilization. It is essential.

Various attempts have been made to achieve the above technical concept. For example, in Patent Document 1, conductive fine particles are unevenly distributed in the coating layer by using a plurality of resins that are not suitable for the carrier coating resin, the spent resistance of the carrier coating resin is utilized, and the carrier is low due to the conductive fine particles. Realizes resistance.
However, as the printing speed increases, the effect of suppressing the toner spent by the coating resin is not enough, and the resistance increases with the number of prints, and the problem that the edge becomes thin when printing halftone is unavoidable. ..

Further, in response to the decrease in charging ability due to the toner spend, in Patent Document 2, the surfaces of the first conductive particles, which are metal oxide conductive particles, and the metal oxide particles and / or the metal salt particles are conductively treated. A carrier having a coat layer containing a second conductive particle is disclosed. In Patent Document 2, a certain effect can be expected for a decrease in the charging ability of the carrier when the toner is balanced in a high image area.
However, when a toner containing a large amount of toner external additive is used, continuous paper passing over a high image area also causes a decrease in charge, and the effect cannot be said to be sufficient.

In response to this, Patent Documents 3 and 4 disclose carriers containing barium sulfate in the coat film and having a Ba / Si ratio of 0.01 to 0.08 with respect to all elements measured by XPS. .. Further, Patent Document 5 describes an example in which barium sulfate is used as a base material. Further, Patent Document 6 describes that the coating layer contains a predetermined amount of metal oxide conductive particles (I) and other metal oxides or metal salts or both (II), and as an example, barium sulfate. Is listed. In these inventions, an effect can be expected against a decrease in the charging ability of the carrier when the toner is balanced in a higher image area.

However, in recent years, the toner tends to be fixed at a low temperature in order to reduce power consumption, and the printing speed is increased, so that toner spending on the carrier is more likely to occur. Furthermore, toner tends to contain many additives due to the demand for higher image quality, and these are spint on the carrier, reducing the margin for reducing the amount of toner charge, toner scattering, and background stains. The current situation. In addition, since the amount of charged fine particles and the like is reduced to fix the toner at a low temperature, the toner at the time of replenishment is not sufficiently mixed with the developer, so that the toner is not charged and the toner scatters. There is.

For these new problems, the above-mentioned fine particles in which barium sulfate is covered with a substance such as tin oxide have not been sufficiently effective. Therefore, Patent Document 7 discloses a carrier containing barium sulfate on the outermost surface of the coating resin, and the expected effect is expected.
However, in Patent Document 7, since large insulating barium sulfate particles are used for the coating layer, it is difficult for the conductive particles to lower the resistance of the carrier. As a result, the amount of particles input increases due to the increase in the filler for adjusting the resistance, which adversely affects the formation of the coating layer. Therefore, in a low resistance region or in a case where the amount of particles charged is large when the chargeability with time is increased, problems such as carrier adhesion occur.

In view of the above problems, the present invention can obtain good resistance control and charge control, can supply a stable amount of developer to the developing area, and can produce a high image even in a high-speed machine using a low-temperature fixing toner. It is an object of the present invention to provide a carrier that enables continuous paper passing at a print density of an area ratio and a low image area ratio.

In order to solve the above problems, the present invention provides a carrier having a core particle and a resin layer covering the surface of said core particle, said resin layer having an inner layer and an outer layer, said resin layer Contains oxygen-deficient tin fine particles and barium sulfate particles, and measures the height of the carrier surface in a designated range with a confocal microscope to obtain parallel lines and measurement curves, from the parallel lines to the measurement curve in the designated range. The absolute value of the deviation is synthesized, and the averaged surface roughness Rz is 2.6 μm or more and 3.6 μm or less.

According to the present invention, good resistance control and charge control can be obtained, a stable amount of developer can be supplied to the developing region, and a high image area ratio and low image area ratio can be obtained even in a high-speed machine using low-temperature fixing toner. It is possible to provide a carrier that enables continuous paper passing at a print density of an image area ratio.

It is a figure (A) and (B) for schematically explaining the state of the fine particles contained in a resin layer. It is another figure (A) and (B) for schematically explaining the state of the fine particles contained in a resin layer. It is a figure which shows the cell used when measuring the volume resistivity of the carrier of this invention. It is a figure which shows an example of the process cartridge used in this invention.

Hereinafter, the carrier, the developer, the developer accommodating unit, the image forming apparatus, and the image forming method according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments shown below, and can be modified within the range conceivable by those skilled in the art, such as other embodiments, additions, modifications, and deletions. However, as long as the action and effect of the present invention are exhibited, it is included in the scope of the present invention.

(Career)
The present invention is a carrier having core material particles and a resin layer covering the surface of the core material particles. The resin layer contains at least two types of fine particles, and one of the fine particles is sulfuric acid. It is a barium particle, and is characterized in that the surface roughness Rz when the carrier is measured with a confocal microscope is 2.6 μm or more and 3.6 μm or less.

The carrier of the present invention can be used as a carrier for electrostatic latent image development used in electrophotographic and electrostatic recording methods, and according to the present invention, there is sufficient resistance to image quality required in the field of production printing. Control and charge control become possible. In addition, it is possible to supply a stable amount of developer to the developing area, and it is possible to continuously pass paper with a high image area ratio and a low image area ratio printing density even in a high-speed machine using low-temperature fixing toner. be able to.
Details will be described below.

<Resin layer>
<< Fine particles and surface shape >>
In the present invention, it is very important that the resin layer (also referred to as a coating layer, a coating resin layer, etc.) contains at least two types of fine particles, and one of the fine particles is barium sulfate particles. .. Barium sulfate can increase the chargeability of the toner, and the presence of barium sulfate on the surface layer of the carrier can maintain the chargeability even after a long time image output.
In addition, it is very important that the carrier of the present invention has a surface roughness Rz of 2.6 μm or more and 3.6 μm or less as measured by a confocal microscope.

When the resin layer contains two types of barium sulfate particles and conductive fine particles, chargeable barium sulfate hinders conductivity. Therefore, when trying to match the same resistance level, if barium sulfate is introduced, The amount of conductive fine particles introduced is larger than that in the case where barium sulfate is not introduced. When the conductive fine particles are not chargeable, the chargeable component of the outermost layer of the carrier is reduced, so that the more the conductive fine particles are introduced, the lower the chargeability holding ability is. That is, when the resistance is adjusted to the low resistance region and a sufficient charge holding ability is provided, the total amount of barium sulfate particles and conductive fine particles introduced becomes very large, and the volume ratio of the fine particles occupying the resin layer increases. do.

When spray coating using a fluidized bed is performed to form such a resin layer, the leveling property at the time of coating film is lowered even when a sufficient diluting solvent is used, and a coating film having large surface irregularities is formed. In addition to embrittlement of the film, desorption of fine particles occurs due to insufficient amount of binder resin. In addition, as the amount of fine particles to be added increases, the raw material cost often increases.

The resin layer in the present invention may be a single layer or a plurality of layers. Above all, it is preferable to have a two-layer structure including an inner layer and an outer layer.
As a manufacturing method when the resin layer is a single layer, for example, a method of applying a coating liquid for forming a resin layer containing fine particles other than barium sulfate particles and barium sulfate particles to the core material particles and drying the resin layer is formed. Can be mentioned.
When the resin layer has a two-layer structure, for example, an inner layer forming coating liquid containing fine particles other than barium sulfate particles is applied to the core material particles and dried to form an inner layer, and then an outer layer forming coating liquid containing barium sulfate particles is formed. The resin layer can be formed by applying and drying the above to form an outer layer. The coating and drying can be performed by a known method.
Hereinafter, an example in the case of a two-layer configuration will be described, but the present invention is not limited to this.

In the case of a two-layer structure, it is important that the thickness of the outer layer is not too thin with respect to the introduced particle size. Here, FIGS. 1 and 2 show diagrams for schematically explaining the state of the fine particles (here, barium sulfate particles) contained in the resin layer. In FIGS. 1 and 2, a resin layer composed of an outer layer 21 and an inner layer 22 is exemplified, and barium sulfate particles 20 contained in the resin layer are shown. Note that FIGS. 1 and 2 are diagrams for schematically explanation, and the particle size and the thickness of the resin layer of the barium sulfate particles 20 may differ from the actual ones.

In FIG. 1 (A), the thickness of the outer layer 21 is smaller than the particle size of the barium sulfate particles 20, and the surface (thick line in the figure) where the barium sulfate particles 20 introduced into the outer layer adhere to the resin layer is sufficient. Since it is not secured, the barium sulfate particles 20 in the outer layer may be detached. When the particles in the outer layer are desorbed, the charging function of the desorbed particles is lost, and the rigidity of that part is lost. Occurs. In FIG. 1A, the ratio of the thickness of the outer layer 21 to the thickness of the inner layer 22 is approximately the thickness of the outer layer 21: the thickness of the inner layer 22 = 3: 7.
FIG. 1B is an example in which the thickness of the outer layer 21 and the thickness of the inner layer 22 are the same as those of FIG. 1A, but the thickness of the entire resin layer is smaller than that of FIG. 1A. In FIG. 1 (B), the barium sulfate 20 of the outer layer 21 is desorbed as described above, and even the buried inner layer 22 particles cannot secure a sufficient adhesive surface, and the barium sulfate particles are scraped due to a strong hazard. 20 is separated from the resin layer, and the core material particles are exposed (broken line portion in the figure).

On the other hand, FIG. 2 is an example in which the ratio of the thickness of the outer layer 21 to the thickness of the inner layer 22 is changed with respect to FIG. In FIG. 2, the ratio of the thickness of the outer layer 21 to the thickness of the inner layer 22 is approximately the thickness of the outer layer 21: the thickness of the inner layer 22 = 8: 2.
In FIG. 2A, the outer layer 21 has a sufficient thickness with respect to the particle size of the barium sulfate particles 20, and as shown in the drawing, a surface on which the fine particles 20 adhere to the resin layer is sufficiently secured, and the barium sulfate is formed. Desorption of barium particles 20 is less likely to occur.
Further, FIG. 2B is an example in which the thickness of the outer layer 21 and the thickness of the inner layer 22 are the same as those of FIG. 2A, but the thickness of the entire resin layer is smaller than that of FIG. 2A. .. If a sufficient amount of adhesive is not obtained for the filler in the outer layer, scraping progresses and filler detachment occurs. However, in FIG. 2B, the inner layer 22 exists between the filler and the core material, and the core material is exposed. Progress can be suppressed.

Therefore, as described above, it is preferable to appropriately adjust the particle size of the barium sulfate particles, the thickness of the resin layer, and the ratio of the thickness of the outer layer to the inner layer so that the desorption of the barium sulfate particles can be further suppressed. The method of adjusting the thickness of the outer layer and the thickness of the inner layer can be appropriately changed. For example, the solid content concentrations of the outer layer forming coating liquid and the inner layer forming coating liquid to be applied when forming the resin layer may be appropriately adjusted to change the solid content volume ratio of the outer layer and the inner layer after the film formation. .. The solid content volume ratio between the outer layer and the inner layer is preferably 6: 4 to 9: 1.

The present inventors further studied a configuration capable of suppressing the desorption of barium sulfate particles, and found that the desired effect can be obtained when the surface unevenness of the carrier satisfies a predetermined shape. However, in defining the shape of the surface unevenness of the carrier, for example, a method using BET can be considered, but the method using BET is affected by the hollow shape of the core material particles, and the shape and numerical range that can solve the above problems are set. It was difficult to specify. Therefore, further studies have been carried out, and it has been found that the range of surface roughness Rz that can solve the above problems can be defined by using the surface roughness Rz measured with a confocal microscope.
Hereinafter, it may be referred to as "surface roughness Rz" or "Rz", but unless otherwise specified, it means the surface roughness Rz of the carrier as measured by a confocal microscope.

When the surface roughness Rz of the carrier measured with a confocal microscope is 3.6 μm or less, it is possible to prevent the contained filler from being detached due to printing stress over time, and the core material is partially exposed. It is possible to prevent the resistance from being lowered and the solid carrier from being attached.

Further, when the Rz is 2.6 μm or more, the barium sulfate particles can exist in a convex state in the resin layer. The convex barium sulfate surface is constantly stressed by friction with toner, carriers, developing screw, etc. in the developing device. Therefore, even if the toner resin, wax, additive, or the like is temporarily spun, it is immediately scraped by the above stress, and it becomes easy to keep the barium sulfate exposed.

On the other hand, when the surface roughness Rz is larger than 3.6 μm, the film surface becomes brittle, the contained filler is easily detached due to printing stress over time, and the core material is partially exposed, resulting in a decrease in resistance. Causes solid carrier adhesion. In addition, the change in the surface property of the carrier reduces the pumping amount, does not supply an appropriate amount of the developer to the developing section, and causes problems such as deterioration of the image shading difference in the page.

If Rz is smaller than 2.6 μm, the introduced barium sulfate is embedded in the coating film and does not protrude. As a result, chargeable fine particles such as barium sulfate are on the outermost surface, and so-called spints that are buried in the deposits of the toner resin or the toner additive occur during printing, so that they cannot come into contact with the toner and the chargeability is lowered.

On the other hand, toner resin, wax, additives, etc. are spinted in the recesses existing between the convex parts of barium sulfate, but since they are electrically charged with the same charge as the toner by being covered with these, they are more spent. Does not accumulate. The carrier surface layer, which becomes a recess due to these spents, cannot be charged with toner, but since it is a recess, the probability of friction with the toner is low, and the contribution to toner charging is small. As a result, since the portion where barium sulfate exists as a convex portion determines the charging ability of the carrier, it is possible to maintain a stable charging ability for a long period of time when the surface roughness Rz is larger.

In consideration of the above, the surface roughness Rz is more preferably 3.0 μm or more and 3.2 μm or less. In this case, it can be expected that barium sulfate is sufficiently exposed to retain the charge over time without embrittlement of the film after containing a sufficient amount of fine particles.

As a method of adjusting the surface roughness Rz, in addition to the method of forming a layer structure as described above, for example, the equivalent circle diameter of barium sulfate particles, the filling rate of the total amount of fine particles with respect to the resin layer, the thickness of the resin layer, etc. The surface roughness Rz of the carrier can also be adjusted by changing it. Further, a plurality of these conditions may be appropriately changed. For example, in the case of a two-layer structure, the surface roughness is appropriately changed by appropriately changing the relationship between the equivalent circle diameter of the barium sulfate particles and the ratio of the thickness of the outer layer and the inner layer. Rz can be adjusted.

In addition to the above, it is also possible by appropriately changing the manufacturing conditions of the resin layer. For example, when the resin layer is manufactured by coating with a fluidized bed, the leveling property can be improved and Rz can be reduced by halving the amount of suspended air introduced at the time of coating.

In addition to the above, Rz can also be adjusted by, for example, the following method. As the fine particles other than barium sulfate particles, it is preferable to use conductive fine particles having a small volume. Among them, by using inexpensive and small volume fine particles such as carbon black, fine particles occupying the resin layer while reducing the cost. The volume ratio can be reduced, the leveling property can be improved, and Rz can be reduced.

On the other hand, when carbon black is used, for example, there is a concern that the color may change due to the transfer of carbon black particles to the toner. Therefore, it is preferable to coat the vicinity of the carrier core material with a resin layer made of carbon black and barium sulfate, and then continuously coat the outer layer with a resin layer made of conductive fine particles and barium sulfate. As a result, it is possible to reduce the Rz of the outermost layer of the carrier while suppressing the change in the color of the toner.

As a method for measuring the surface roughness Rz of the carrier with a confocal microscope, a known method can be used, but in the present invention, the surface roughness Rz is measured by the following method. Using a confocal microscope (OPTELICS C130 manufactured by Lasertec), analyze the three-dimensional structure of the carrier surface, measure the height in the specified range below to obtain parallel lines, and measure the curve from the parallel lines in this range. Calculated by synthesizing and averaging the absolute values of the deviations up to.

[Measurement condition]
Objective lens magnification: 50 times Resolution: 0.20
Analysis: Twenty designated ranges of 10 μm square were selected for each sample and used as the average value data of the surface roughness Rz.

As a method of measuring the unevenness of the carrier surface, there is an index by BET, but in the case of a carrier using a core material having many hollows, the adsorbed gas component for BET measurement adheres to the hollow core material, and the outermost surface. It is not desirable because it cannot accurately represent the surface area of.

The average film thickness of the resin layer of the carrier is preferably 0.80 μm or more. When the average film thickness is 0.80 μm or more, it is possible to form a coating film capable of sufficiently holding fine particles without any film defects. On the other hand, the film thickness of the resin layer is preferably 1.5 μm or less in order to prevent a decrease in magnetization.

Further, it is preferable that the equivalent circle diameter of the barium sulfate particles in the resin layer is 0.4 μm or more and 0.9 μm or less. In this case, it becomes possible to form the coating film after the surface roughness Rz is stably adjusted to the above-mentioned range, and the barium sulfate particles are likely to exist in the resin layer in a convex state.

Further, the equivalent circle diameter of the barium sulfate particles is more preferably 0.6 μm or more from the viewpoint of ensuring stable charging ability and developing ability.
When the equivalent circle diameter of the barium sulfate particles is 0.9 μm or less, it is possible to prevent the barium sulfate particles from becoming larger than the thickness of the resin layer and to prevent the barium sulfate particles from separating from the resin layer.

The fine particles other than the barium sulfate particles contained in the resin layer can be appropriately changed, but it is preferable to contain conductive fine particles in order to adjust the volume resistivity of the carrier. Examples of fine particles other than barium sulfate include metal powder, titanium oxide, tin oxide, zinc oxide, alumina, indium tin oxide (ITO), phosphorus-doped tin (PTO), tungsten-doped tin (WTO), carbon black, polyaniline and the like. Examples include conductive polymers. These may be used in combination of two or more.

The filling rate of the total amount of fine particles in the resin layer is preferably 65% or more and 95% or less, and more preferably 75% or more and 85% or less.
When the filling rate is 95% or less, the amount of the binder resin that embeds the fine particles on the carrier surface is insufficient, and a portion where the surface becomes embrittled and a portion containing more fine particles and the hardness increases are mixed. You can prevent that. In this case, even if a strong stress is applied due to printing, the embrittled portion is not rubbed and scraped, and it is possible to prevent the core material from being exposed and the resistance from being lowered. It does not occur and the decrease in charge can be suppressed. Further, since the binding of the fine particles is weak, it is possible to prevent the fine particles desorbed by stress from becoming white powder and contaminating the inside of the developing machine.

When the filling rate is 65% or more, the hardness component of the resin layer is impaired, it is possible to prevent scraping due to printing stress, the core material is less likely to be exposed, and a sufficient amount of barium sulfate is exposed on the surface. It is possible to prevent the charge from decreasing over time of printing.

The particle size, filling rate, and film thickness of the resin layer of the fine particles can be confirmed by a known method. For example, in the present invention, the measurement is performed by the following method. The carrier is mixed with an embedding resin (Devcon, two-component mixture, 30-minute curable epoxy resin), left overnight or longer to cure, and mechanically polished to prepare a rough cross-sectional sample. A cross section polisher (SM-09010, manufactured by JEOL Ltd.) is used for this, and the cross section is finished under the conditions of an acceleration voltage of 5.0 kV and a beam current of 120 μA. This is photographed using a scanning electron microscope (Merlin manufactured by Carl Zeiss) under the conditions of an acceleration voltage of 0.8 kV and a magnification of 30,000 times. The captured image was incorporated into a TIFF image, and the equivalent circle diameter of 100 particles of barium sulfate was measured using Image-Pro Plus manufactured by Media Cybernetics, and the average value was used. Regarding the filling rate and the film thickness, Image-Pro Plus was used to define the filling rate and the average film thickness of the conductive fine particles in the resin layer from the white and black areas with respect to the carrier 100 particles.

<< Resin component >>
The resin component in the resin layer can be appropriately changed. For example, a copolymer containing the following monomer A component (also referred to as A component) and the following monomer B component (also referred to as B component) is heat-treated. The obtained resin can be mentioned.

The formula of component A is shown below.

In the formula, R ¹ represents a hydrogen atom or a methyl group, m represents an integer of 1 to 8, and therefore (CH ₂ ) _m has 1 to 8 carbon atoms such as a methylene group, an ethylene group, a propylene group and a butylene group. R ² represents an aliphatic hydrocarbon group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group. Further, X = 10 to 90 mol%, more preferably 30 to 70 mol%.

The component A has an atomic group tris (trimethylsiloxy) silane in which a large number of methyl groups are present in the side chain, and the surface energy decreases as the ratio of the component A to the entire resin increases, and the toner resin Adhesion of components, wax components, etc. is reduced. When the A component is 10 mol% or more, a sufficient effect can be obtained and the adhesion of the toner component can be suppressed. Further, when it is 90 mol% or less, the B component and the C component described later are not reduced, the cross-linking proceeds, the toughness can be improved, the adhesiveness between the core material and the resin layer is not lowered, and the carrier coating is formed. Durability can be improved.

R ² is an alkyl group having 1 to 4 carbon atoms, and examples of such A component include a tris (trialkylsiloxy) silane compound represented by the following formula.
In the following formula, Me is a methyl group, Et is an ethyl group, and Pr is a propyl group.
CH ₂ = CMe-COO-C ₃ H _6- Si (OSiMe ₃ ) ₃
CH ₂ = CH-COO-C ₃ H _6- Si (OSiMe ₃ ) ₃
CH ₂ = CMe-COO-C ₄ H _8- Si (OSiMe ₃ ) ₃
CH ₂ = CMe-COO-C ₃ H _6- Si (OSiEt ₃ ) ₃
CH ₂ = CH-COO-C ₃ H _6- Si (OSiEt ₃ ) ₃
CH ₂ = CME-COO-C ₄ H _8- Si (OSiEt ₃ ) ₃
CH ₂ = CMe-COO-C ₃ H _6- Si (OSiPr ₃ ) ₃
CH ₂ = CH-COO-C ₃ H _6- Si (OSiPr ₃ ) ₃
CH ₂ = CME-COO-C ₄ H _8- Si (OSiPr ₃ ) ₃

The method for producing the component A is not particularly limited, but a method of reacting tris (trialkylsiloxy) silane with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst, or a methacryloxyalkyl tri in the presence of a carboxylic acid and an acid catalyst. It can be obtained by a method of reacting an alkoxysilane with a hexaalkyldisiloxane or the like.

The formula of the B component (crosslinking component) is shown below.

In the formula, R ¹ represents a hydrogen atom or a methyl group, m represents an integer of 1 to 8, and therefore (CH ₂ ) _m has 1 to 8 carbon atoms such as a methylene group, an ethylene group, a propylene group and a butylene group. R ² represents an aliphatic hydrocarbon group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group and a butyl group, ^{and R 3 represents a methyl group, an ethyl group, a propyl group and a butyl group.} It represents an alkyl group having 1 to 8 carbon atoms such as a group, or an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, an ethoxy group, a propoxy group and a butoxy group.

The component B is a radically polymerizable bifunctional or trifunctional silane compound, and Y = 10 to 90 mol%, more preferably 30 to 70 mol%. When the B component is 10 mol% or more, sufficient toughness can be obtained. On the other hand, if it is 90 mol% or less, the problem that the film becomes hard and brittle and the film scraping is likely to occur can be prevented. In addition, deterioration of environmental characteristics can be prevented. This is because if a large number of hydrolyzed crosslinked components remain as silanol groups, the environmental characteristics (humidity dependence) may be deteriorated.

Examples of such B component include 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, and 3-methacryloxypropyl. Examples thereof include methyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacrythoxypropyltri (isopropoxy) silane, and 3-acryloxypropyltri (isopropoxy) silane.

In the present invention, the following copolymer obtained by radical copolymerization of the monomer A component and the monomer B component is hydrolyzed to generate a silanol group, which is crosslinked and coated by condensation using a catalyst. After that, it is preferable to heat-treat to form a resin layer.

Here, in the formula, R ¹ , m, R ² , R ³ , X and Y are as described above.

In the present invention, an acrylic compound (monomer) may be added as the C component to the A component and the B component. Examples of the product to which such a C component is added include the following copolymers.

Here, in the formula, R ¹ , m, R ² , and R ³ are as described above.
In the above copolymer, X = 10 to 40 mol%, Y = 10 to 40 mol%, Z = 30 to 80 mol%, and 60 mol% <Y + Z <90 mol%.

The formula of the C component is shown below.

In the formula, R ¹ and R ² are as described above.

The C component imparts flexibility to the resin layer and improves the adhesiveness between the core material and the coating film. However, if the C component is 30 mol% or more, sufficient adhesiveness can be obtained. If it is 80 mol% or less, it is possible to prevent either the X component or the Y component from being 10 mol% or less, and it is possible to achieve both water repellency, hardness and flexibility (film scraping) of the carrier film. ..

As the acrylic compound (monomer) of the C component, an acrylic acid ester or a methacrylate ester is preferable, and specifically, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, 2- (dimethylamino). ) Ethyl methacrylate, 2- (dimethylamino) ethyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (dimethylamino) propyl acrylate are exemplified.
Of these, alkyl methacrylate is preferable, and methyl methacrylate is particularly preferable. Further, one kind of these compounds may be used alone, or a mixture of two or more kinds may be used.

As the resin used for forming the resin layer, in addition to the above-mentioned resin, a silicon resin, an acrylic resin, or a combination thereof can be used. This is because acrylic resin has strong adhesiveness and low brittleness, so it has very excellent wear resistance. On the other hand, because of its high surface energy, the toner component spendt can be used in combination with toner that is easy to spend. Problems such as a decrease in the amount of charge due to accumulation may occur. In that case, this problem can be solved by using a silicon resin which has an effect that it is difficult to spent the toner component because the surface energy is low and it is difficult for the accumulation of the spent component to proceed due to film scraping. On the other hand, since silicon resin has weak adhesiveness and high brittleness, it is inferior in abrasion resistance. Therefore, when these two types of resins are used in combination, it is advisable to consider the balance between the two resins so that a resin layer that is difficult to spent and has wear resistance can be formed.

The silicon resin refers to all generally known silicon resins, and examples thereof include straight silicon composed only of an organoshirosan bond, and a silicon resin modified with alkyd, polyester, epoxy, acrylic, urethane, or the like.
For example, as a commercially available straight silicone resin, KR271, KR255, KR152 manufactured by Shin-Etsu Chemical Co., Ltd., SR2400, SR2406, SR2410 manufactured by Toray Dow Corning Silicone Co., Ltd. and the like can be mentioned. In this case, it is possible to use the silicon resin alone, but it is also possible to use other components that undergo a cross-linking reaction, a charge amount adjusting component, and the like at the same time.
Further, as the modified silicone resin, KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical Co., Ltd., and SR2115 (epoxy modified) manufactured by Toray Dow Corning Silicon Co., Ltd. ), SR2110 (alkyd modification) and the like.

Further, examples of the polycondensation catalyst include a titanium-based catalyst, a tin-based catalyst, a zirconium-based catalyst, and an aluminum-based catalyst. In the present invention, among these various catalysts, among the titanium-based catalysts that produce excellent results. In particular, titanium diisopropoxybis (ethylacetacetate) is the most preferable catalyst. It is considered that this is because the effect of promoting the condensation reaction of the silanol group is large and the catalyst is not easily deactivated.

The resin layer preferably contains a silane coupling agent. Thereby, the fine particles can be stably dispersed.
The silane coupling agent is not particularly limited, but is r- (2-aminoethyl) aminopropyltrimethoxysilane, r- (2-aminoethyl) aminopropylmethyldimethoxysilane, r-methacryloxypropyltrimethoxysilane, N. -Β- (N-vinylbenzylaminoethyl) -r-aminopropyltrimethoxysilane hydrochloride, r-glycidoxypropyltrimethoxysilane, r-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, Vinyl triacetoxysilane, r-chloropropyltrimethoxysilane, hexamethyldisilazane, r-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium chloride, r-chlor Propylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1,3-divinyltetramethyl Examples thereof include disilazan, methacryloxyethyl dimethyl (3-trimethoxysilylpropyl) ammonium chloride, and the like, and two or more thereof may be used in combination.

Commercially available silane coupling agents include AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048, Z- 6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6940 (manufactured by Toray Silicone Co., Ltd.) and the like. ..

The amount of the silane coupling agent added is preferably 0.1 to 10% by weight based on the resin component. If the amount of the silane coupling agent added is 0.1% by weight or more, the adhesiveness between the core material particles and the conductive fine particles and the resin is lowered, and the resin layer is dropped off during long-term use. Can be prevented. When it is 10% by weight or less, it is possible to prevent the problem that toner filming occurs during long-term use.

<Core particle>
In the present invention, the core material particles are not particularly limited as long as they are magnetic materials, but ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; these magnetic materials are used. Examples thereof include resin particles dispersed in the resin. Among them, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr ferrite and the like are preferable from the viewpoint of the environment.

<Characteristics of carrier>
The carrier of the present invention preferably has a volume average particle diameter of 28 μm or more and 40 μm or less. When the volume average particle size of the carrier particles is 28 μm or more, the occurrence of carrier adhesion can be further prevented, and when it is 40 μm or less, the reproducibility of image details is lowered and the problem that a fine image cannot be formed is prevented. be able to.
The volume average particle size can be measured using, for example, the Microtrack particle size distribution meter model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.).

The carrier of the present invention preferably has a volume resistivity of 8 to 16 (LogΩ · cm). When the volume resistivity is 8 (LogΩ · cm) or more, it is possible to prevent carrier adhesion from occurring in the non-image area, and when it is 16 (LogΩ · cm) or less, the edge effect becomes an unacceptable level. You can prevent that.

The amount of change in carrier resistance is measured by the following method. As shown in FIG. 3, the carrier 33 is placed in a cell 31 composed of a fluororesin container containing an electrode 32a having a surface area of 2 × 4 cm and a distance of 2 mm between electrodes (32a, 32b) of resistance measurement parallel electrodes. It is turned on, DC1000V is applied, and the resistance value 30 seconds later is measured with a high-resist meter. The value obtained by converting the obtained value into the volume resistivity is defined as the initial resistance value (R1). Next, the toner in the developer after running is removed by a blow-off device, resistance is measured for the obtained carrier by the same method as the resistance measurement method, and the obtained value is converted into volume resistivity. , Deterioration resistance value (R2). Next, the amount of change in carrier resistance can be calculated by the following formula.
| (R1-R2) | / R1 × 100

As for the rate of change of the charge amount of the carrier, the charge amount (Q1) of the initial carrier is measured by using a blow-off device for a sample obtained by mixing the carrier and toner and triboelectrically charging the sample. As the charge amount (Q2) of the carrier after running over time, a carrier from which the toner of each color in the developer after running is removed by using a blow-off device is used. The rate of change in the amount of charge was an absolute value of (Q1-Q2) / Q1 × 100.

(Developer)
The developer of the present invention has the carrier and toner of the present invention.

<Toner>
The toner contains a binder resin and a colorant, but may be either a monochrome toner or a color toner. Further, the toner particles may contain a mold release agent in order to apply to an oilless system in which the fixing roller is not coated with the toner sticking prevention oil. Such toners are generally prone to filming, but the carriers of the present invention can suppress filming, so that the developer of the present invention maintains good quality for a long period of time. Can be done. Further, color toners, particularly yellow toners, generally have a problem that color stains are generated due to scraping of the coating layer of the carrier, but the developer of the present invention can suppress the occurrence of color stains.

<< Toner manufacturing method >>
The toner can be produced by using a known method such as a pulverization method or a polymerization method. For example, when a toner is produced by using a pulverization method, first, the melt-kneaded product obtained by kneading the toner material is cooled, then pulverized and classified to produce parent particles. Next, in order to further improve the transferability and durability, an external additive is added to the parent particles to prepare a toner.

At this time, the apparatus for kneading the toner material is not particularly limited, but is a batch type two-roll machine; Banbury mixer; KTK type twin-screw extruder (manufactured by Kobe Steel Co., Ltd.), TEM type twin-screw extruder (Toshiba Machinery Co., Ltd.). Continuous twin-screw extruder such as twin-screw extruder (manufactured by KCK), PCM type twin-screw extruder (manufactured by Ikekai Iron Works), KEX type twin-screw extruder (manufactured by Kurimoto Iron Works); Examples thereof include a continuous type uniaxial kneader such as Ko Nida (manufactured by Buss).

When crushing the cooled melt-kneaded product, it is roughly pulverized using a hammer mill, a rotoplex, or the like, and then finely pulverized using a pulverizer using a jet stream, a mechanical pulverizer, or the like. be able to. It is preferable to grind so that the average particle size is 3 to 15 μm.

Further, when classifying the crushed melt-kneaded product, a wind power type classifier or the like can be used. It is preferable to classify the matrix particles so that the average particle size is 5 to 20 μm.

Further, when the external additive is added to the matrix particles, the external additive is crushed and adheres to the surface of the matrix particles by mixing and stirring using mixers.

<< Bundling resin >>
The binder resin is not particularly limited, but is a homopolymer of styrene such as polystyrene, polyp-styrene, polyvinyltoluene and its substitution product; styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene. -Vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylate copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer , Styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinylmethyl ether copolymer, styrene-vinylmethylketone copolymer, styrene-butadiene Styrene-based copolymers such as copolymers, styrene-isoprene copolymers, styrene-maleic acid ester copolymers; polymethylmethacrylate, butylpolymethacrylate, polyvinyl chloride, vinylacetate, polyethylene, polyester, polyurethane , Epoxy resin, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpen resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin and the like, and two or more thereof may be used in combination.

The binder resin for pressure fixing is not particularly limited, but is a polyolefin such as low molecular weight polyethylene and low molecular weight polypropylene; ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, and styrene-methacrylic acid copolymer. , Ethylene-methacrylic acid ester copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, olefin copolymer such as ionomer resin; epoxy resin, polyester, styrene-butadiene copolymer, polyvinylpyrrolidone, Examples thereof include a methyl vinyl ether-maleic anhydride copolymer, a maleic acid-modified phenol resin, and a phenol-modified terpene resin, and two or more thereof may be used in combination.

<< Colorant >>
The colorant (pigment or dye) is not particularly limited, but Cadmium Yellow, Mineral Fast Yellow, Nickel Titanium Yellow, Nabres Yellow, Naftor Yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Kinolin Yellow Lake, Yellow pigments such as permanent yellow NCG and tartrazine lake; orange pigments such as molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indance lem brilliant orange RK, benzidine orange G, indance lem brilliant orange GK; red iron oxide, cadmium Red pigments such as Red, Permanent Red 4R, Resole Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamin Lake B, Alizarin Lake, Brilliant Carmine 3B; Fast Violet B, Methyl Violet Lake Purple pigments such as cobalt blue, alkaline blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, indanslen blue BC and other blue pigments; chrome green, chromium oxide, pigment Green pigments such as Green B and Malakite Green Lake; azine pigments such as carbon black, oil furnace black, channel black, lamp black, acetylene black and aniline black, metal salt azo pigments, metal oxides, composite metal oxides, etc. Examples include black pigments, and two or more of them may be used in combination.

<< Release agent >>
The release agent is not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish, carnauba wax, and ester wax. Two or more types may be used in combination.

<< Electrification control agent >>
In addition, the toner may further contain a charge control agent. The charge control agent is not particularly limited, but is niglosin; an azine dye having an alkyl group having 2 to 16 carbon atoms (see Japanese Patent Publication No. 42-1627); I. Basic Yellow 2 (CI 41000), C.I. I. Basic Yellow 3, C.I. I. Basic Red 1 (CI 45160), C.I. I. Basic Red 9 (CI 42500), C.I. I. Basic Violet 1 (CI 42535), C.I. I. Basic Violet 3 (CI 42555), C.I. I. Basic Violet 10 (CI 45170), C.I. I. Basic Violet 14 (CI 42510), C.I. I. Basic Blue 1 (CI 42025), C.I. I. Basic Blue 3 (CI 51005), C.I. I. Basic Blue 5 (CI 42140), C.I. I. Basic Blue 7 (CI 42595), C.I. I. Basic Blue 9 (CI 52015), C.I. I. Basic Blue 24 (CI 52030), C.I. I. Basic Blue25 (CI52025), C.I. I. Basic Blue 26 (CI44045), C.I. I. Basic Green 1 (CI 42040), C.I. I. Basic dyes such as Basic Green 4 (CI 42000); lake pigments of these basic dyes; C.I. I. Quadruple ammonium salts such as Solvent Black 8 (CI 26150), benzoylmethylhexadecylammonium chloride, decyltrimethyl chloride; dialkyltin compounds such as dibutyl and dioctyl; dialkyltinborate compounds; guanidine derivatives; vinyls with amino groups Polyamine resins such as based polymers and condensed polymers having an amino group; metal complex salts of monoazo dyes; sartylic acid; metal complexes of dialkylsartylic acid, naphthoic acid, dicarboxylic acids such as Zn, Al, Co, Cr and Fe; sulfonated Copper phthalocyanine pigments; organic boron salts; fluorine-containing quaternary ammonium salts; calix-allene compounds and the like, but two or more of them may be used in combination. For color toners other than black, a metal salt of a white salicylic acid derivative or the like is preferable.

<< External agent >>
The external additive is not particularly limited, but is an inorganic particle such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, or boron nitride; a poly having an average particle size of 0.05 to 1 μm obtained by a soap-free emulsion polymerization method. Examples thereof include resin particles such as methyl methacrylate particles and polystyrene particles, and two or more of them may be used in combination. Of these, metal oxide particles such as silica and titanium oxide whose surface is hydrophobized are preferable. Furthermore, by using silica that has been hydrophobized and titanium oxide that has been hydrophobized in combination, and by increasing the amount of titanium oxide that has been hydrophobized compared to silica that has been hydrophobized, the amount of titanium oxide that has been hydrophobized is increased with respect to humidity. A toner having excellent charge stability can be obtained.

<Replenishing developer>
By using the carrier of the present invention as a replenishing developer composed of a carrier and toner and applying it to an image forming apparatus that forms an image while discharging excess developing agent in the developing apparatus, a stable image can be obtained for an extremely long period of time. Quality is obtained. That is, the deteriorated carriers in the developing apparatus and the non-deteriorated carriers in the replenishing developing agent are replaced to keep the charge amount stable for a long period of time, and a stable image can be obtained.

This method is particularly effective when printing a high image area. When printing a high image area, the carrier charge deterioration due to the toner spent on the carrier is the main carrier deterioration. However, by using this method, the carrier replenishment amount increases when the image area is high, so that the deteriorated carriers are replaced. The frequency goes up. As a result, a stable image can be obtained over an extremely long period of time.

The mixing ratio of the replenishing developer is preferably 2 to 50 parts by weight of the toner with respect to 1 part by weight of the carrier. When the amount of toner is less than 2 parts by weight, the amount of replenished carriers is too large, the carrier supply is excessive, and the carrier concentration in the developing apparatus becomes too high, so that the charged amount of the developer tends to increase. Further, as the amount of charge of the developer increases, the developing ability decreases and the image density tends to decrease. On the other hand, if it exceeds 50 parts by weight, the carrier ratio in the replenishing developer is reduced, so that the carriers in the image forming apparatus are less replaced, and it becomes difficult to obtain an effect on carrier deterioration.

(Developer accommodating unit, image forming apparatus and image forming method)
The developer accommodating unit of the present invention accommodates the developer of the present invention.
The image forming apparatus of the present invention includes an electrostatic latent image carrier, a charging means for charging the electrostatic latent image carrier, and an exposure means for forming an electrostatic latent image on the electrostatic latent image carrier. A developing means for developing the electrostatic latent image with the developer of the present invention to form a toner image, a transfer means for transferring the toner image to a recording medium, and a toner image transferred to the recording medium are fixed. It has a fixing means for making it. Further, it has other means appropriately selected as necessary, such as static elimination means, cleaning means, recycling means, control means and the like.
The image forming method of the present invention includes a charging step of charging an electrostatic latent image carrier, an exposure step of forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image of the present invention. It includes a developing step of developing with a developer to form a toner image, a transfer step of transferring the toner image to a recording medium, and a fixing step of fixing the toner image transferred to the recording medium. Further, it has other steps appropriately selected as necessary, such as a static elimination step, a cleaning step, a recycling step, a control step and the like.
According to the present invention, in addition to the effects obtained by the carrier of the present invention described above, it is possible to provide a highly reliable developer accommodating unit, image forming method, and image forming apparatus.

The developer accommodating unit in the present invention refers to a unit in which a developer is accommodated in a unit having a function of accommodating the developer.
Here, as an embodiment of the developer accommodating unit, there are a container containing a developer, a developer, and a process cartridge.
The container containing a developer means a container containing a developer.
The developer has a means for accommodating and developing a developer.
The process cartridge is a cartridge in which at least an electrostatic latent image carrier and a developing means having the developer of the present invention are integrated and can be attached to and detached from an image forming apparatus. Further, the process cartridge may be integrally formed with at least one of a charging means, an exposure means, and a cleaning means in addition to the electrostatic latent image carrier and the developing means.

FIG. 4 shows an example of the process cartridge used in the present invention. The process cartridge 10 develops the photoconductor 11 (electrostatic latent image carrier), the charging device 12 for charging the photoconductor 11, and the electrostatic latent image formed on the photoconductor 11 with the developer of the present invention. A developing device 13 for forming a toner image and a cleaning device 14 for removing the toner remaining on the photoconductor 11 after transferring the toner image formed on the photoconductor 11 to a recording medium are integrally supported. The process cartridge 10 is removable from the main body of an image forming apparatus such as a copying machine or a printer.

Hereinafter, a method of forming an image using an image forming apparatus equipped with the process cartridge 10 will be described. First, the photoconductor 11 is rotationally driven at a predetermined peripheral speed, and the peripheral surface of the photoconductor 11 is uniformly charged to a predetermined positive or negative potential by the charging device 12. Next, the peripheral surface of the photoconductor 11 is irradiated with exposure light from an exposure apparatus such as a slit exposure type exposure apparatus or an exposure apparatus that scans and exposes with a laser beam, and an electrostatic latent image is sequentially formed. Further, the electrostatic latent image formed on the peripheral surface of the photoconductor 11 is developed by the developing apparatus 13 using the developing agent of the present invention to form a toner image.

Next, the toner image formed on the peripheral surface of the photoconductor 11 is sequentially transferred from the paper feed unit to the transfer paper fed between the photoconductor 11 and the transfer device in synchronization with the rotation of the photoconductor 11. Will be done. Further, the transfer paper on which the toner image is transferred is separated from the peripheral surface of the photoconductor 11 and introduced into the fixing device to be fixed, and then printed out as a copy to the outside of the image forming device. .. On the other hand, the surface of the photoconductor 11 after the toner image is transferred is cleaned by removing the residual toner by the cleaning device 14, and then statically eliminated by the static eliminator, and is repeatedly used for image formation.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples. In addition, "part" represents a weight part.

(Manufacturing of carriers)
<Resin synthesis example 1>
300 g of toluene was put into a flask equipped with a stirrer, and the temperature was raised to 90 ° C. under a nitrogen gas stream. Next, _{3-methacryloxypropyltris (trimethylsiloxy) silane represented by CH 2} = CMe-COO-C ₃ H _6- Si (OSiMe ₃ ) ₃ (Me is a methyl group in the formula) 84. 4 g (200 mmol, Cyraplane TM-0701T, manufactured by Chisso), 39 g (150 mmol) of 3-methacryloxypropylmethyldiethoxysilane, 65.0 g (650 mmol) of methyl methacrylate, and 2,2'-azobis. A mixture of 0.58 g (3 mmol) of -2-methylbutyronitrile was added dropwise over 1 hour. After completion of the dropping, a solution prepared by dissolving 0.06 g (0.3 mmol) of 2,2'-azobis-2-methylbutyronitrile in 15 g of toluene was further added (2,2'-azobis-2-methylbuty). A total amount of ronitrile (0.64 g = 3.3 mmol) was mixed at 90 to 100 ° C. for 3 hours and radical copolymerized to obtain [methacrylic copolymer R1].

<Carrier Manufacturing Example 1>
20 parts of [methacrylic copolymer R1] (solid content 100% by weight), silicon resin solution (solid content 20% by weight), aminosilane (solid content) of 35,000 obtained in Resin Synthesis Example 1 3.0 parts (100% by weight), 82 parts of barium sulfate particles (manufactured by Sakai Chemical Co., Ltd., equivalent circle diameter 0.7 μm) and 85 parts of oxygen-deficient tin fine particles (manufactured by Mitsui Kinzoku Co., Ltd., primary particle diameter 30 nm) are toluene. Diluted with, to obtain [resin solution 1] having a solid content of 20% by weight. The resin solution was dispersed with a homogenizer (TK homomixer MARKII manufactured by PRIMIX Corporation) at 10,000 rpm for 3 minutes, and then titanium diisopropoxybis (ethylacetacetate) TC-750 (manufactured by Matsumoto Fine Chemical Co., Ltd.) was used as a catalyst. ) Two parts were added to obtain [resin coating layer coating solution 1].
Further, it is the same as obtaining [Resin coating layer coating liquid 1] except that 85 parts of oxygen-deficient tin fine particles of [Resin solution 1] are changed to 10 parts of Ketjen Black EC600JD (manufactured by Lion Specialty Chemicals Co., Ltd.). [Resin coating layer coating solution 2] was obtained by the method of.
Next, the liquid amounts of [resin coating layer coating liquid 1] and [resin coating layer coating liquid 2] were adjusted so that the solid content volume ratio after film formation and drying was 8: 2. Next, using Mn ferrite particles having a weight average particle size of 35 μm and a bulk density of 2.1 g / cm ³ as the core material, a fluidized bed coating is used so that the average film thickness on the core material surface is 1.00 μm. Using a atomizing nozzle in the apparatus, the temperature in the fluidized bed was controlled to 60 ° C., and the [resin coating layer coating liquid 2] was first applied and dried. [Resin coating layer coating liquid 1] was applied and dried in quick succession. As the air volume condition of the fluidized bed type coating apparatus, the air to be introduced from the lower flow devices to 2.4 Nm 3 ^/ min, and the air to be introduced from the fluidized bed apparatus an upper and 1.0 Nm 3 ^/ min.
Next, the obtained carrier was calcined in an electric furnace at 210 ° C. for 1 hour to obtain [Carrier 1].

<Carrier Manufacturing Example 2>
Carrier Production In Example 1, [Carrier 2] is similarly used except that the solid content volume ratio of [Resin coating layer coating liquid 1] and [Resin coating layer coating liquid 2] is changed to 6: 4 instead of 8: 2. ] Was obtained.

<Carrier Manufacturing Example 3>
In Carrier Production Example 1, the solid content volume ratio of [resin coating layer coating liquid 1] and [resin coating layer coating liquid 2] is not 8: 2, but only [resin coating layer coating liquid 1] is used and flows. [Carrier 3] was obtained in the same manner except that the total air volume introduced in the floor coating apparatus was uniformly halved.

<Carrier Manufacturing Example 4>
Carrier Production In Example 1, [Carrier 4] was obtained in the same manner except that the equivalent circle diameter of the barium sulfate particles was changed to 0.4 μm instead of 0.7 μm.

<Carrier Manufacturing Example 5>
Carrier Production In Example 1, [Carrier 5] was obtained in the same manner except that the equivalent circle diameter of the barium sulfate particles was changed to 0.3 μm instead of 0.7 μm.

<Carrier Manufacturing Example 6>
Carrier Production In Example 1, [Carrier 6] was obtained in the same manner except that the equivalent circle diameter of the barium sulfate particles was changed to 0.9 μm instead of 0.7 μm.

<Carrier Manufacturing Example 7>
Carrier Production In Example 1, [Carrier 7] was obtained in the same manner except that the equivalent circle diameter of the barium sulfate particles was changed to 1.0 μm instead of 0.7 μm.

<Carrier Manufacturing Example 8>
In the carrier production Example 1, the amount of barium sulfate particles added to the [resin coating layer coating liquid 1] and the [resin coating layer coating liquid 2] was increased from 82 parts to 62 parts, and the oxygen-deficient tin fine particles of the [resin solution 1] were added. [Carrier 8] was obtained in the same manner except that the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 85 parts to 65 parts and the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 10 parts to 7 parts.

<Carrier Manufacturing Example 9>
In the carrier production Example 1, the amount of barium sulfate particles added to the [resin coating layer coating liquid 1] and the [resin coating layer coating liquid 2] was increased from 82 parts to 42 parts, and the oxygen-deficient tin fine particles of the [resin solution 1] were added. [Carrier 9] was obtained in the same manner except that the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 85 parts to 45 parts and the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 10 parts to 5 parts.

<Carrier Manufacturing Example 10>
In the carrier production Example 1, the amount of barium sulfate particles added to the [resin coating layer coating liquid 1] and the [resin coating layer coating liquid 2] was increased from 82 parts to 102 parts, and the oxygen-deficient tin fine particles of the [resin solution 1] were added. [Carrier 10] was obtained in the same manner except that the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 85 parts to 105 parts and the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 10 parts to 12 parts.

<Carrier Manufacturing Example 11>
In the carrier production Example 1, the amount of barium sulfate particles added to the [resin coating layer coating liquid 1] and the [resin coating layer coating liquid 2] was increased from 82 parts to 122 parts, and the oxygen-deficient tin fine particles of the [resin solution 1] were added. [Carrier 11] was obtained in the same manner except that the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 85 parts to 125 parts and the addition amount of Ketjen Black EC600JD in [Resin Solution 2] was changed from 10 parts to 15 parts.

<Comparative example of carrier manufacturing 1>
In Carrier Production Example 1, the equivalent circle diameter of the barium sulfate particles was changed to 0.8 μm instead of 0.7 μm, and the solid content volume ratio of [resin coating layer coating liquid 1] and [resin coating layer coating liquid 2] was changed. [Carrier 12] was obtained in the same manner except that the value was changed to 4: 6 instead of 8: 2.

<Comparative example of carrier manufacturing 2>
In Carrier Production Example 1, the equivalent circle diameter of barium sulfate particles was changed to 0.4 μm instead of 0.7 μm, and the solid content volume ratio of [resin coating layer coating liquid 1] and [resin coating layer coating liquid 2]. [Carrier 13] was obtained in the same manner except that the total air volume introduced in the fluidized bed coating apparatus was uniformly halved by using only [resin coating layer coating liquid 1] instead of 8: 2.

<Comparative example of carrier manufacturing 3>
Carrier Production In Example 1, [Carrier 14] was obtained in the same manner except that the barium sulfate particles were changed to barium titanate (manufactured by Sakai Chemical Industry Co., Ltd.).

<Comparative example of carrier manufacturing 4>
Carrier Production In Example 1, [Carrier 15] was obtained in the same manner except that the core material was changed to Mn ferrite particles having a hollow structure having a weight average particle diameter of 35 μm and a bulk density of 1.7 g / cm ^3.

(Measurement of carrier)
<Surface roughness Rz by confocal microscope>
The following measurements were performed on each of the obtained carriers, and the surface roughness Rz was determined by a confocal microscope. Using a confocal microscope (OPTELICS C130 manufactured by Lasertech), analyze the three-dimensional structure of the carrier surface, measure the height within the specified range below to obtain parallel lines, and from the parallel lines to the measurement curve in this range. It was calculated by synthesizing the absolute values of the deviations of and averaging them.

[Measurement condition]
Objective lens magnification: 50 times Resolution: 0.20
Analysis: Twenty designated ranges of 10 μm square were selected for each sample and used as the average value data of the surface roughness Rz.

<Surface roughness by BET>
As a reference value, the specific surface area by BET was determined for each of the obtained carriers. The specific surface area by BET was measured with respect to 3.5 g of the carrier using a BET specific surface area measuring device (Macsorb model-1201 manufactured by MOUNTECH).

The obtained carrier characteristics are shown in Table 1.

(Toner manufacturing example)
<Synthesis of polyester resin A>
65 parts of ethylene oxide 2 mol adduct of bisphenol A, 86 parts of propion oxide 3 mol adduct of bisphenol A, 274 parts of terephthalic acid and 2 parts of dibutyltin oxide are put into a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube. Then, the reaction was carried out at 230 ° C. for 15 hours under normal pressure. Next, the reaction was carried out under reduced pressure of 5 to 10 mmHg for 6 hours to synthesize [polyester resin A]. The obtained [polyester resin A] has a number average molecular weight (Mn) of 2,300, a weight average molecular weight (Mw) of 8,000, a glass transition temperature (Tg) of 58 ° C., an acid value of 25 mgKOH / g, and a hydroxyl group. The value was 35 mgKOH / g.

<Styrene acrylic resin A synthesis>
300 parts of ethyl acetate, 185 parts of styrene, 115 parts of acrylic monomer and 5 parts of azobisisobutynitrile were put into a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and the temperature was 65 ° C. (normal pressure) under a nitrogen atmosphere. ) For 8 hours. Next, 200 parts of methanol was added, and the mixture was stirred for 1 hour, the supernatant was removed, and the mixture was dried under reduced pressure to synthesize [styrene acrylic resin A]. The obtained [styrene acrylic resin A] had a Mw of 20,000 and a Tg of 58 ° C.

<Synthesis of prepolymer (polymer capable of reacting with active hydrogen group-containing compound)>
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 682 parts of bisphenol A ethylene oxide 2 mol adduct, 81 parts of bisphenol A propylene oxide 2 mol adduct, 283 parts of terephthalic acid, 22 parts of trimellitic anhydride, And 2 parts of dibutyltin oxide were charged and reacted at 230 ° C. for 8 hours under normal pressure. Then, the reaction was carried out under reduced pressure of 10 to 15 mHg for 5 hours to synthesize [intermediate polyester].
The obtained [intermediate polyester] has a number average molecular weight (Mn) of 2,100, a weight average molecular weight (Mw) of 9,600, a glass transition temperature (Tg) of 55 ° C., an acid value of 0.5, and a hydroxyl group. The value was 49.
Next, 411 parts of the [intermediate polyester], 89 parts of isophorone diisocyanate, and 500 parts of ethyl acetate were charged in a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, and reacted at 100 ° C. for 5 hours. , [Prepolymer] (polymer capable of reacting with an active hydrogen group-containing compound) was synthesized.
The free isocyanate content of the obtained [prepolymer] was 1.60% by weight, and the solid content concentration of the [prepolymer] (150 ° C., after standing for 45 minutes) was 50% by weight.

<Synthesis of ketimine compounds (active hydrogen group-containing compounds)>
30 parts of isophorone diamine and 70 parts of methyl ethyl ketone were charged in a reaction vessel in which a stirring rod and a thermometer were set, and the reaction was carried out at 50 ° C. for 5 hours to synthesize a [ketimine compound] (active hydrogen group-containing compound). The amine value of the obtained [ketimine compound] (active hydrogen group-containing compound) was 423.

<Making a masterbatch>
Henschel mixer (Mitsui Mining Co., Ltd.) with 1,000 parts of water, 540 parts of carbon black Printex35 (manufactured by Degussa) with DBP oil absorption of 42 mL / 100 g and pH of 9.5, and 1,200 parts of [polyester resin A]. Was mixed using. Next, using two rolls, the obtained mixture was kneaded at 150 ° C. for 30 minutes, rolled and cooled, and pulverized with a palperizer (manufactured by Hosokawa Micron Co., Ltd.) to prepare a [master batch].

<Preparation of water-based medium>
306 parts of ion-exchanged water, 265 parts of a 10 mass% suspension of tricalcium phosphate and 1.0 part of sodium dodecylbenzenesulfonate were mixed and stirred to uniformly dissolve them to prepare an [aqueous medium].

<Measurement of critical micelle concentration>
The critical micelle concentration of the surfactant was measured by the following method. Analysis was performed using an analysis program in the Sigma system using a surface tension meter Sigma (manufactured by KSV Instruments). The surfactant was added dropwise to the [aqueous medium] in an amount of 0.01% by weight, and the interfacial tension after stirring and standing was measured. From the obtained surface tension curve, the concentration of the surfactant at which the surfactant does not decrease even when the surfactant is dropped was calculated as the critical micelle concentration. When the critical micelle concentration of sodium dodecylbenzenesulfonate with respect to [water-based medium] was measured with a tensiometer Sigma, it was 0.05% by weight with respect to the weight of [water-based medium].

<Preparation of toner material liquid>
70 parts of [Polyester resin A], 10 parts of [Prepolymer] and 100 parts of ethyl acetate were placed in a beaker and dissolved by stirring. Add 5 parts of paraffin wax (HNP-9 manufactured by Nippon Seiko Co., Ltd., melting point 75 ° C.), 2 parts of MEK-ST (manufactured by Nissan Chemical Industries, Ltd.), and 10 parts of [Masterbatch] as a mold release agent. Using a Viscomill (manufactured by Imex), after 3 passes under the condition that the liquid feeding speed was 1 kg / hour, the peripheral speed of the disc was 6 m / sec, and 80% by volume of zirconia beads having a particle size of 0.5 mm was filled, then [Ketimin] [Compound] 2.7 parts was added and dissolved to prepare [Toner Material Liquid].

<Emulsification or preparation of dispersion>
Put 150 parts of [water-based medium] in a container, stir at a rotation speed of 12,000 rpm using a TK homomixer (manufactured by Tokushu Kagaku Kogyo Co., Ltd.), add 100 parts of [toner material liquid] to this, and add it for 10 minutes. The mixture was mixed to prepare an emulsified or dispersion (emulsified slurry).

<Removal of organic solvent>
100 parts of the emulsified slurry was charged into a flask in which a stirrer and a thermometer were set, and the solvent was removed at 30 ° C. for 12 hours while stirring at a stirring peripheral speed of 20 m / min. As a result, a [dispersed slurry] was obtained.

<Washing>
After 100 parts of the [dispersed slurry] was filtered under reduced pressure, 100 parts of ion-exchanged water was added to the filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 10 minutes), and then filtered. 300 parts of ion-exchanged water was added to the obtained filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 10 minutes), and then filtered twice. Twenty parts of a 10 mass% sodium hydroxide aqueous solution was added to the obtained filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 30 minutes), and then filtered under reduced pressure. 300 parts of ion-exchanged water was added to the obtained filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 10 minutes), and then filtered. 300 parts of ion-exchanged water was added to the obtained filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 10 minutes), and then filtered twice. Further, 20 parts of 10% by mass hydrochloric acid was added to the obtained filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 10 minutes), and then filtered.

<Adjusting the amount of surfactant>
300 parts of ion-exchanged water was added to the filtered cake obtained by the above washing, and the electric conductivity of the toner dispersion liquid when mixed with a TK homomixer (at a rotation speed of 12,000 rpm for 10 minutes) was measured. The surfactant concentration of the toner dispersion was calculated from the calibration curve of the surfactant concentration prepared in advance. From that value, ion-exchanged water was added so that the surfactant concentration became the target surfactant concentration of 0.05% by weight, and a [toner dispersion liquid] was obtained.

<Surface treatment process>
The [toner dispersion] adjusted to the predetermined surfactant concentration was heated in a water bath at a heating temperature of T1 = 55 ° C. for 10 hours while mixing with a TK homomixer at 5000 rpm. Then, the toner dispersion was cooled to 25 ° C. and filtered. Further, 300 parts of ion-exchanged water was added to the obtained filtered cake, mixed with a TK homomixer (rotation speed 12,000 rpm for 10 minutes), and then filtered.

<Drying>
The obtained final filtered cake was dried at 45 ° C. for 48 hours in a circulation dryer and sieved with a mesh having a mesh size of 75 μm to obtain [Toner Mother Particle 1].

<External processing>
Further, with respect to 100 parts of [Toner matrix particles 1], 3.0 parts of hydrophobic silica having an average particle size of 100 nm, 1.0 part of titanium oxide having an average particle size of 20 nm, and hydrophobic silica having an average particle size of 15 nm. 1.5 parts of the fine powder was mixed with a Henschel mixer to obtain [Toner 1].

<Preparation of developer>
930 parts of each carrier and 70 parts of [Toner 1] obtained in Examples and Comparative Examples were mixed and stirred at 81 rpm for 5 minutes using a turbuler mixer, and [Developer 1] to [Development] for evaluation were used. Agent 15] was prepared. Further, the replenishing developer was produced by using the carrier and the toner so that the toner concentration was 95% by weight.

(evaluation)
<Developer characteristic evaluation (80% image area ratio)>
Initial and image area using [Developer 1] to [Developer 15] and [Toner 1] of Examples and Comparative Examples on Ricoh RICOH Pro C7110S (Ricoh digital color copier / printer multifunction device) The charge amount and resistance of the carrier after running 1 million sheets were measured at a rate of 80%, and the rate of change of the charge amount and resistance was calculated. In addition, toner scattering and skin fog after running 1 million sheets were evaluated.

<< Charging stability >>
As for the initial charge amount (Q1) of the carrier, [Carrier 1] to [Carrier 15] and [Toner 1] are mixed at a mass ratio of 93: 7, and a triboelectricly charged sample is used as a blow-off device TB-200 (Blow-off device TB-200). Measured using Toshiba Chemical Co., Ltd.). The charge amount (Q2) of the carrier after running 1 million sheets was measured in the same manner as above except that the carrier from which the toner of each color in the developer after running was removed was used by using a blow-off device.
The rate of change in the amount of charge was defined as the absolute value of (Q1-Q2) / Q1 × 100.
The evaluation criteria are shown below.

◎ (Very good): 0 or more and less than 5 ○ (Good): 5 or more and less than 10 △ (Available): 10 or more and less than 20 × (Defective): 20 or more

<< Resistance stability >>
The amount of change in carrier resistance was measured by the following method. The carrier is placed in a cell 31 composed of a fluororesin container containing an electrode 32a having a surface area of 2 × 4 cm and an electrode 32a having a distance between the electrodes (32a and 32b) of the resistance measurement parallel electrodes (see FIG. 3). The resistance value 30 seconds after applying 1000 V DC was measured with a high-resist meter. The value obtained by converting the obtained value into the volume resistivity is defined as the initial resistance value (R1). Next, the toner in the developer after running is removed by a blow-off device, resistance is measured for the obtained carrier by the same method as the resistance measurement method, and the obtained value is converted into volume resistivity. Then, the deterioration resistance value is used (R2). Next, the amount of change in carrier resistance was calculated by the following formula.
| (R1-R2) | / R1 × 100
The evaluation criteria are shown below.

◎ (Very good): 0 or more and less than 3 ○ (Good): 3 or more and less than 6 △ (Available): 6 or more and less than 10 × (Defective): 10 or more

<< Toner scattering >>
After running 1 million sheets, the amount of toner accumulated in the lower part of the developer carrier was sucked and recovered, and the toner weight was measured.
The evaluation criteria are shown below.

◎ (Very good): 0 mg or more and less than 50 mg ○ (Good): 50 mg or more and less than 100 mg △ (Available): 100 mg or more and less than 250 mg × (Poor): 250 mg or more

<< Skin cover >>
After running 1 million sheets, the blank image is stopped during development, the toner on the photoconductor (electrostatic latent image carrier) after development is transferred to tape, and the difference (ΔID) from the image density of the untransferred tape is 938. The measurement was performed with a spectrodensitometer (manufactured by X-Rite).
The evaluation criteria are shown below.

◎ (Very good): 0 or more and less than 0.005 ○ (Good): 0.005 or more and less than 0.01 △ (Available): 0.01 or more and less than 0.02 × (Defective): 0.02 or more

<Developer characteristic evaluation (0.5% image area ratio)>
Further, using Ricoh RICOH Pro C7110S (Ricoh digital color copier / printer multifunction device), using [Developer 1] to [Developer 15] and [Toner 1] of Examples and Comparative Examples. 1 million sheets were run with an image area ratio of 0.5%, and charge stability, resistance stability, solid carrier adhesion, and developer amount stability were evaluated.

<< Charging stability and resistance stability >>
The charge stability and resistance stability of the 0.5% image area ratio were evaluated using the same method as the above 80% image area ratio.

<< Solid carrier adhesion >>
After running 1 million sheets, a solid image is imaged under predetermined development conditions (charging potential (Vd): -600V, potential after exposure of the part corresponding to the image part (solid original): -100V, development bias: DC-500V). The image formation was interrupted by a method such as turning off the power inside, and the number of carriers attached to the photoconductor after transfer was counted and evaluated. The region to be evaluated was a region of 10 mm × 100 mm on the photoconductor.
The evaluation criteria are shown below. ◎, ○, and △ were accepted, and × was rejected.

◎ (Pass): The number of carriers attached is 0 ○ (Pass): The number of carriers attached is 1 to 3 △ (Pass): The number of carriers attached is 4 to 10 × (Failed) ): The number of carriers attached is 11 or more.

<< Stability of developer amount >>
The amount of the developer after passing through the developing doctor of the developing device ^{is collected using a measuring jig (a jig capable of collecting 1 cm 2} of the developer), and the weight thereof is measured. Three points were measured in the longitudinal direction of the developing sleeve, and the average value was taken as the amount of the developing agent on the sleeve. This was measured at the initial stage and after running 1 million sheets, and evaluated by the absolute value of the difference.
The evaluation criteria are shown below.

◎ (Very good): 0 mg or more and less than 1 mg ○ (Good): 1 mg or more and less than 2 mg △ (Available): 2 mg or more and less than 4 mg × (Poor): 4 mg or more

The evaluation results are shown in Table 2.

10 Process cartridge 11 Photoreceptor 12 Charging device 13 Developing device 14 Cleaning device 20 Barium sulfate particles 21 Outer layer 22 Inner layer

Japanese Patent No. 2714590 Japanese Unexamined Patent Publication No. 2010-117519 Japanese Patent No. 5534409 Japanese Unexamined Patent Publication No. 2011-209678 Japanese Unexamined Patent Publication No. 2006-079022 Japanese Unexamined Patent Publication No. 2011-145388 Japanese Unexamined Patent Publication No. 2016-212254

Claims (7)

A core particle, a carrier having a resin layer covering the surface of the core particles,
The resin layer has an inner layer and an outer layer, and has an inner layer and an outer layer.
The resin layer contains oxygen-deficient tin fine particles and barium sulfate particles, and contains
Height measurement is performed in a specified range of the carrier surface with a confocal microscope to obtain parallel lines and measurement curves, and absolute values of deviations from the parallel lines to the measurement curve in the specified range are combined and averaged surface roughness. A carrier having an Rz of 2.6 μm or more and 3.6 μm or less. The carrier according to claim 1, wherein the barium sulfate particles have a circle-equivalent diameter of 0.4 μm or more and 0.9 μm or less. In the cross-sectional photograph of the carrier, the filling ratio of the total amount of the fine particles to the resin layer , which is shown by the ratio of the area of the fine particles to the area of the resin layer, is 65% or more and 95% or less. The carrier according to claim 1 or 2. A developer having the carrier and toner according to any one of claims 1 to 3. A developer accommodating unit comprising accommodating the developer according to claim 4. Electrostatic latent image carrier and
A charging means for charging the electrostatic latent image carrier and
An exposure means for forming an electrostatic latent image on the electrostatic latent image carrier,
A developing means for forming a toner image by developing the electrostatic latent image with the developer according to claim 4.
A transfer means for transferring the toner image to a recording medium,
An image forming apparatus comprising: a fixing means for fixing a toner image transferred to the recording medium. The charging process for charging the electrostatic latent image carrier and
An exposure step of forming an electrostatic latent image on the electrostatic latent image carrier, and
A developing step of developing the electrostatic latent image with the developer according to claim 4 to form a toner image, and
A transfer step of transferring the toner image to a recording medium, and
An image forming method comprising a fixing step of fixing a toner image transferred to the recording medium.

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