JP5549865B2 - Coating coating solution for coating core material of electrophotographic carrier - Google Patents

Description

  The present invention relates to an electrophotographic carrier and an electrophotographic developer, and more particularly to a method for producing a coating liquid for coating a core material of an electrophotographic carrier used for forming an electrostatic latent image into a toner image. About.

In electrophotographic image formation, an electrostatic latent image is formed by an electrostatic charge on an image carrier such as a photoconductive material, and charged toner particles are attached to the electrostatic latent image to form a visible image. After the toner image is formed, the toner image is transferred to a recording medium such as paper and fixed to form an output image.
In recent years, copying and printer technologies using an electrophotographic system are rapidly expanding from monochrome to full color, and the full color market tends to expand. Color image formation by full-color electrophotography generally reproduces all colors by stacking three color toners of three primary colors, yellow, magenta, and cyan, or four color toners with black added thereto. is there.
Therefore, in order to obtain a clear full color image with excellent color reproducibility, it is necessary to smooth the fixed toner image surface to some extent to reduce light scattering. For these reasons, the image gloss of conventional full-color copying machines or the like is often 10 to 50% of medium to high gloss.

In general, as a method for fixing a dry toner image on a recording medium, a contact heating fixing method in which a roller or belt having a smooth surface is heated and pressed against the toner is frequently used. This method has high thermal efficiency and high-speed fixing, and is advantageous in that it can give gloss and transparency to the color toner. However, the surface of the heat-fixing member is brought into contact with the molten toner under pressure. Since the toner image is peeled off from the surface of the post-heating fixing member, a so-called offset phenomenon occurs in which a part of the toner image adheres to the surface of the heat fixing member and is transferred onto another image. For the purpose of preventing this offset phenomenon, there is a method in which the surface of the heat fixing member is formed of silicone rubber or fluorine resin having excellent releasability, and further, a release oil such as silicone oil is applied to the surface of the heat fixing member. It was generally adopted.
However, this method is extremely effective in preventing toner offset, but requires a device for supplying release oil, and is unsuitable for downsizing the machine due to the increase in size of the fixing device. For this reason, in a monochrome toner, by adjusting the molecular weight distribution of the binder resin so that the melted toner does not break internally, the viscoelasticity at the time of melting of the toner is increased, and a release agent such as wax is further included in the toner. There is a tendency to employ a method in which the release oil is not applied to the fixing roller (oilless) or the amount of oil applied is very small.

On the other hand, as for color toners, there is a tendency toward oil-less for the purpose of downsizing machines and simplifying the configuration as in monochrome. However, as described above, in order to improve the color reproducibility of the color toner, it is necessary to smooth the surface of the fixed image, so the viscoelasticity at the time of melting must be lowered. It is easier to offset than monochrome toner, and it is more difficult to make the fixing device oil-free and to apply a small amount.
In addition, when a release agent is contained in the toner, the adhesion of the toner is increased and the transfer property to the transfer paper is lowered. Further, the release agent in the toner contaminates the frictional charging member such as a carrier to reduce the charging property. This causes a problem that the durability is lowered.

  Regarding the carrier, while the demand for faster and more beautiful image formation is increasing, the stress received by the developer containing the carrier and the toner has increased dramatically with the recent increase in machine speed. Even in a carrier having a long life, a sufficient life cannot be obtained. Furthermore, in terms of high image quality, with the reduction in toner diameter and carrier diameter, the allowable range in the image quality with respect to the charge amount distribution has become narrower, especially for toner stains (background fogging) in non-image areas. It becomes very easy to become a defective image.

In order to cope with such a problem, for example, in Japanese Patent Application Laid-Open No. 2007-102159 of Patent Document 1 and Japanese Patent Application Laid-Open No. 2008-70837 of Patent Document 2, particles having a diameter larger than the film thickness are included in the coating layer. An electrophotographic carrier has been proposed.
Furthermore, in Japanese Patent Application Laid-Open No. 2007-286078 of Patent Document 3, a toner containing two types of particles, a first particle having a diameter larger than the film thickness and a second particle having a diameter smaller than the film thickness. There has been proposed a method in which a developing device is replenished with a carrier provided with a coating film on the surface of a core material, and development is performed while discharging an excess developer in the developing device.
Japanese Patent Application Laid-Open No. 11-184167 of Patent Document 4 has a plurality of resin coating layers on a magnetic core, and needle-like or scaly conductive powder is formed on the first coating layer directly above the magnetic core. Describes a carrier for an electrophotographic developer dispersed by a bead mill using glass beads.
However, those described in Patent Documents 1 to 4 have insufficient effects, and are not suitable for carrier adhesion in a solid image portion and toner stain (background fogging) in a non-image portion accompanying a decrease in resistance over time. Enough and problematic.
By the way, a bead mill is often used for the preparation of a coating liquid containing a dispersion of solid particles in the coating liquid, but the bead mill is mainly used for a dispersion chamber called a vessel for introducing a dispersion liquid. , And other attachment means including a discharge part are provided as desired. Usually, a dispersion chamber (a vessel) is distributed between a cylindrical stator forming an outer wall and a rotor rotating at the center of the stator. It consists of a space (dispersion chamber), in which the liquid to be dispersed is dispersed.
A plurality of blades project radially from the rotor, and the dispersion liquid is fed into the dispersion chamber, filled with beads that are dispersion media, and the rotor is rotated to agitate the beads by the blades. The solid particles are dispersed into the fine particles by the movement of. When discharging the liquid to be dispersed from the dispersion chamber, there are many cases where some beads as a dispersion medium are inevitably and involuntarily accompanied. When the dispersion liquid once exiting the dispersion chamber is circulated again and repeatedly dispersed, the accompanying of the beads is not so much problem, but if the final product contains beads, especially in the field of carrier coating. It will not be discussed that it becomes a serious problem.
By the way, we have been studying the dispersion and preparation of coating liquids for many years. As one of the achievements, the purpose is to use a dispersion-treated liquid containing finely dispersed media. Has already proposed one of the solvent feeding methods for satisfactorily expelling the dispersed liquid from the dispersion chamber to the outside of the system (see JP 2010-102054 A). This proposed liquid feeding system is a lateral liquid feeding system, and can be said to be in contrast to the coating liquid distribution system in the present invention.

  The present invention has been made in consideration of the above-described circumstances, and does not cause carrier adhesion in a solid image portion due to a decrease in resistance over time, and does not cause toner contamination (background fogging) in a non-image portion. It is an object of the present invention to provide a method for producing a coating solution for coating a core material of a carrier.

That is, the said subject is solved by following (1)-( 10 ) of this invention.
(1) “This is a coating coating solution for coating the core material of an electrophotographic carrier, and has a main dispersion step of dispersing a solution containing at least a binder resin and solid particles using beads of 5 mm or less. In the dispersion step, the solution is fed from the outside of the dispersion chamber to the lower portion of the dispersion chamber, dispersed through the stirring unit including the beads and a stirring rotor, and then passed through a centrifugal separation mechanism. it was separated and then coating the coating liquid, characterized in that it is manufactured by discharging to disperse outside from the dispersion chamber top ",
(2) “Coating coating solution according to (1) above, which is manufactured through a pre-dispersing step without using the beads before the main dispersing step ” ,
(3) “The coating density according to the item (1) or (2), wherein the true density of the beads is 2.8 g / cm ³ or more ” ,
(4) “The coating solution according to any one of (1) to (3) above, wherein the bead has a particle size of 0.015 mm to 1 mm ”
(5) The coating coating liquid according to any one of (1) to (4) above, wherein the bead filling rate in the main dispersion step is 10% or more and 90% or less "
(6) The coating coating solution according to any one of (1) to (5), wherein the linear velocity of the stirring rotor is 4 m / sec or more and 20 m / sec or less. "
(7) “This main dispersion step has a jacket for temperature-controlling the inside of the dispersion chamber, and the temperature of the temperature-control medium put into the jacket is 0 ° C. or more and 20 ° C. or less, The coating coating liquid according to any one of (1) to (6),
( 8 ) "Electrophotographic carrier characterized by having a coating layer formed on the surface of the core material particles by the coating coating solution according to any one of (1) to (7) ",
( 9 ) "Two-component developer for electrophotography, comprising toner and carrier for electrophotography according to item ( 8 )",
( 10 ) “Equipped with at least an electrostatic latent image carrier, means for forming an electrostatic latent image on the image carrier, and developing means for developing the electrostatic latent image, An image forming apparatus using the two-component developer according to item ( 9 ) ".

  As will be apparent from the following detailed and specific description, the present invention does not cause carrier adhesion in a solid image portion due to a decrease in resistance over time, and does not cause toner contamination (background fogging) in a non-image portion. This has an extremely excellent effect that a method for producing a coating solution for coating the core material of a photographic carrier can be provided.

1 is a schematic diagram illustrating an example of an image forming apparatus of the present invention. It is the schematic which shows the other example of the image forming apparatus of this invention. It is the schematic which shows an example of the further another image forming apparatus (tandem type color image forming apparatus) of this invention. FIG. 4 is a partially enlarged schematic view of the image forming apparatus shown in FIG. 3.

Hereinafter, the present invention will be described in more detail.
As a result of continuing intensive studies to solve the above-described problems of the prior art, the present inventors have obtained a method for producing a coating solution for coating the core material of an electrophotographic carrier, comprising at least binding. A dispersion process in which a solution containing a resin and solid particles is dispersed using beads of 5 mm or less, and a method of treating the coating coating liquid by a disperser in the dispersion process is performed from the outside of the dispersion chamber to the bottom of the dispersion chamber The coating coating liquid is fed, and after passing through a stirring unit composed of beads and a stirring rotor, the beads are separated by a centrifugal separation mechanism, passed through the centrifugal separation mechanism, and coated from the top of the dispersion chamber to the outside of the dispersion chamber. It has been found that the improvement effect is remarkable by using a disperser characterized by discharging gas.
That is, when liquid is fed from above to below the disperser, the beads are affected by gravity and sink to the lower part of the dispersion chamber. This makes it difficult to classify beads. As a result, problems such as contamination to products occur. Further, coarse solid particles cause a short path in the dispersion chamber due to the influence of gravity, and the uniformity of the dispersion liquid is impaired.
In the horizontal direction, when the peripheral speed of the rotor is low at the time of dispersion, there is a problem that beads leak and the product is contaminated (Nano Getter used in the examples described in JP 2010-102054 A). (DMR-L110, manufactured by Ashizawa Finetech Co., Ltd.) delivers the liquid in the horizontal direction, so the dispersion liquid feeding direction and the gravitational component are at right angles, and the beads are biased toward the lower side of the dispersion chamber. The uniformity of the liquid becomes low, and the uniformity of the dispersion becomes low, so the effect of the merit as a carrier as below is reduced. By sending liquid in the horizontal direction, the effect of gravity does not work in the direction to suppress the leakage of beads, so there is a problem that beads are leaked especially when the rotor is rotated at a low speed).
By improving the dispersion of solid particles by “liquid feeding from bottom to top” in the present invention, it becomes possible to maintain the same coating layer state at any location of the coating layer. (Even if any particle is taken, it becomes a carrier particle of the same quality), and the charge amount distribution and wear resistance can be greatly improved. Furthermore, since the solid particles are uniformly dispersed in the coating layer, the surfaces of the solid particles are reliably covered with the resin, so that the solid particles are difficult to be detached. The coating film due to separation is eliminated, and the core material is prevented from being exposed.

In this case, the dispersion state of the solid particles in the coating layer is an important requirement for the problem of the present invention, and a stable quality can be obtained by uniformly dispersing in the coating layer.
That is, by improving the dispersion of the solid particles, it is possible to maintain the same coating layer state at any location of the coating layer, so that the uniformity among the carrier particles is increased. Thus, the charge amount distribution and the wear resistance can be drastically improved.
Furthermore, since the solid particles are uniformly dispersed in the coating layer, the surfaces of the solid particles are reliably covered with the resin, so that the solid particles are difficult to be detached. The coating film due to separation is eliminated, and the core material is prevented from being exposed.
Therefore, it is possible to improve the carrier adhesion in the solid image portion and the toner stain (background fogging) in the non-image portion, which are the problems of the present invention.

As described above, it has been found that the dispersion of solid particles in the coating resin is very important for the carrier quality, but sufficient studies have not been made in the carrier field.
For example, in Japanese Patent Application Laid-Open No. 2007-102159 (Patent Document 1), only a dispersion process is performed in which a raw material is put into a homomixer and dispersed for 10 minutes. As in the present invention, dispersion using beads is performed. No attempt has been made so far to actively disperse solid particles by the method.
Furthermore, since the sand mill described in JP-A-11-184167 (Patent Document 4) has a relatively large bead diameter, it is easy to separate the beads from the dispersion. There is no classifier to separate beads in the dispersion chamber. However, as the bead diameter decreases, the sand mill described here increases the proportion of beads leaking out of the dispersion chamber, and the amount of beads decreases with time, making it substantially impossible to disperse. In addition, when a conventional bead mill is used instead of a sand mill, if a bead having a bead diameter of 5 mm or less is used, a dispersal action cannot be substantially performed as described above.
On the other hand, when the bead diameter is increased, the dispersion energy per grain increases, so the surface of the solid particles is excessively activated, causing reaggregation of the solid particles, and decomposing other materials in the dispersion. -Since the reaction causes a problem such as gelling of the dispersion liquid, the desired dispersion particle size and liquid properties cannot be obtained.
In other words, in order to obtain a target dispersed particle size, it is better to use beads with a particle size as small as possible, but it has been difficult to adopt beads with a particle size of 5 mm or less with a conventional disperser.

However, the disperser of the present invention has a separation mechanism for beads and dispersion, and the separation mechanism also includes a centrifugal separation mechanism that can handle micro beads. The centrifugal separation mechanism is a mechanism that separates the beads and the dispersion liquid by centrifugal force using the specific gravity difference between the beads and the dispersion liquid. Thereby, in this dispersion | distribution process, it became possible to use a microbead 5 mm or less, and the improvement effect was remarkable in the area | region whose bead diameter is 5 mm or less.
This is because, in the case of an electrophotographic carrier as in the present invention, since the solid particles to be dispersed are small and the number of particles is large, the number of beads increases in a region where the bead diameter is 5 mm or less, so that the dispersion proceeds effectively. In the region where the bead diameter exceeds 5 mm, the number cannot be obtained, so that a sufficient dispersion effect cannot be obtained, which is not preferable.
Further, as described above, the larger the bead diameter, the greater the dispersion energy per bead, so that the surface of the solid particles is excessively activated, causing reaggregation of the solid particles, It is important that the thickness is 5 mm or less because other materials may be decomposed / reacted, and further problems such as gelation of the dispersion may occur.
Furthermore, as a feature of the processing method of this disperser, the coating solution is introduced from the lower part of the dispersion chamber and removed from the upper part, so that the dispersion liquid and beads are affected by gravity, and the short path of the dispersion liquid. And has the effect of suppressing bead leakage.

Furthermore, the improvement effect is remarkable by having the pre-dispersion process which does not use a bead before the dispersion | distribution process using a bead. This is because the solid particles of the raw material exist as agglomerates of several hundred μm, and as the bead diameter becomes smaller, it becomes difficult to disperse with the beads.
More specifically, in the case of dispersion by beads, since the aggregates are unraveled small by hitting the aggregates, the relationship between the volume and weight of the beads and the size of the aggregates is important. That is, as the bead diameter becomes smaller, the beads become smaller with respect to the size of the aggregate, and the coarse aggregate cannot be dispersed with the beads. Therefore, it has been found that the work of dispersion in the main dispersion step using beads can be reduced by preliminarily dispersing the aggregates by pre-dispersion without using beads.

Furthermore, the improvement effect is remarkable when the true density of the beads used for this dispersion is 2.8 g / cm ³ or more. This is because the disperser using beads collides with the solid particles that the beads want to disperse, so the dispersion energy increases as the true density of the beads increases, so a high dispersion effect can be obtained. This is because.
On the other hand, when it is less than 2.8 g / cm ³ , the density is small, so that a sufficient dispersion effect cannot be obtained. In addition, in the case of beads such as glass materials, not only the true density is low but also brittle, so cracking occurs during the dispersion treatment, resulting in reduced dispersion efficiency and contamination of the product, which is not preferable. .
Furthermore, in this disperser in which the beads and the coating coat liquid are separated by centrifugal force, if beads having a low true density are used, the centrifugal force becomes small, and thus the beads are easily discharged out of the dispersion chamber. Accordingly, the specific gravity of the beads is preferably 3 or more, and more preferably 5 or more.
Examples of the beads having a true density of 2.8 g / cm ³ or more in the present invention include zirconia, alumina, silicon nitride, steel, and stainless steel. These are not only true density but also brittle resistance (cracking) and wear resistance. Is very good, but is merely an example and is not limited thereto.
Furthermore, as a feature of the processing method of this disperser, the coating solution is introduced from the lower part of the dispersion chamber and removed from the upper part, so that the dispersion liquid and beads are affected by gravity, and the short path of the dispersion liquid. And has the effect of suppressing bead leakage. Thereby, compared with the case where liquid is fed in the lateral direction, bead leakage hardly occurs even when the rotor is used at a low speed. And since gravity is applied perpendicularly to the liquid transfer surface, problems such as the occurrence of uneven beads in the dispersion chamber and the resulting uneven wear of parts, abnormal wear of beads, abnormal heat generation, etc. Can be suppressed.

Furthermore, the improvement effect is remarkable when the bead diameter is 0.015 mm or more and 1 mm or less.
This means that in the region where the bead diameter is 1 mm or less, the dispersion energy per bead is small, and it is possible to disperse while suppressing the activity of the surface of the solid particles, re-aggregation, and decomposition of other materials in the dispersion liquid. -It becomes possible to disperse while suppressing problems such as reaction and further dispersion of the dispersion.
Furthermore, since the number of beads increases, it becomes possible to disperse effectively. However, in the region where the bead diameter is less than 0.015 mm, the bead weight is too light, the centrifugal force is reduced, and energy contributing to dispersion is reduced. Furthermore, the bead diameter is preferably 0.015 mm or more because it is easily affected by the liquid viscosity and the dispersion efficiency is lowered.

Furthermore, when the bead filling rate in the dispersion chamber in this dispersion step is 10% or more and 90% or less, the improvement effect is remarkable. As a more preferable range, the bead filling rate is 40% or more and 80% or less. Here, in the region where the bead filling rate is less than 10%, the number of collisions between the target solid particles and the beads is decreased, and the dispersion efficiency is remarkably lowered.
On the other hand, in the region where the bead filling rate exceeds 90%, the number of times of bead collision with the solid particle surface increases, and the solid particle surface is excessively activated, causing reaggregation of the solid particle, Other materials may be decomposed / reacted, and further problems such as gelation of the dispersion may occur, which is not preferable because the desired dispersion particle size and liquid properties cannot be obtained.
In addition, since the number of collisions between beads increases, there is a concern about bead wear and cracking of beads due to collision between beads.
The bead filling rate in the dispersion chamber referred to in the present invention is obtained from the following formula.

攪拌部容積：分散室内における攪拌に寄与する部分の容積

Stirring unit volume: Volume of the part contributing to stirring in the dispersion chamber

Furthermore, the improvement effect is remarkable when the linear velocity of the stirring rotor used in this dispersion step is 4 m / sec or more and 20 m / sec or less. A more preferable range is a rotor linear velocity of 8 m / sec or more and 12 m / sec or less. Here, generally, as the rotor linear velocity increases, the centrifugal force applied to the beads increases, and the energy contributing to the dispersion of the beads increases. However, if the rotor linear speed exceeds 20 m / sec, the speed of the beads is too high, so the energy that contributes to the dispersion of the beads becomes too large, and instead of dispersing the solid particles, the solid particles may be crushed, Since the surface will be activated excessively, causing problems such as reaggregation of solid particles, decomposition / reaction of other materials in the dispersion, and gelation of the dispersion. It is not preferable.
It also leads to uneven wear of parts and wear of beads. On the other hand, in the region where the rotor linear velocity is less than 4 m / sec, the speed of the beads is slow, so that the energy contributing to the dispersion of the beads is small, the aggregates are not destroyed, and the dispersion does not proceed.

Furthermore, the present dispersion step has a jacket for adjusting the temperature in the dispersion chamber, and the temperature of the temperature adjusting medium put into the jacket is 0 ° C. or higher and 20 ° C. or lower, so that the improvement effect is remarkable.
This is because heat is generated by the bead dispersion action in the dispersion section, and the dispersion temperature rises. When the temperature of the dispersion rises, the solid particles themselves and the surface of the solid particles are easily activated, causing reaggregation of the solid particles, decomposing / reacting other materials in the dispersion, and further, the dispersion becomes a gel. This is not preferable because the desired dispersed particle size and liquid properties cannot be obtained.

In addition, the liquid feeding speed of the coating coat liquid to the dispersion chamber in the present invention greatly affects the dispersion effect. In a region where the liquid feeding speed is too high, this causes a balance between the linear velocity of the stirring rotor, the bead diameter, the dispersion viscosity, and the like, but causes leakage of the beads to the outside of the dispersion chamber. In addition, there may be problems such as occurrence of uneven beading, uneven wear of parts, abnormal wear of beads, and abnormal heat generation.
On the other hand, in a region where the liquid feeding speed is too slow, the dispersion stays in the dispersion chamber for a longer time, and energy is continuously applied to the solid particle surface for a long time at a time. This excessively activates the surface of the solid particles, causes reaggregation of the solid particles, decomposes and reacts with other materials in the dispersion, and further causes the dispersion to gel. The problem occurs. However, in order to alleviate the activity of the surface of the solid particles, by taking a method such as discharging the dispersion liquid once out of the dispersion chamber, reaggregation of the solid particles, decomposition / reaction of other materials in the dispersion liquid, and further dispersion The gelation of the liquid can be suppressed. Thus, in order to discharge the dispersion liquid appropriately to the outside of the dispersion chamber, it is necessary to set the liquid feeding speed of the dispersion liquid into the dispersion chamber to an appropriate number. However, in determining an appropriate liquid feeding speed, it is necessary to consider the scale of the disperser, but generally 10 to 400 kg / h is an appropriate range.

[Carrier core particles]
The core particles for the carrier of the present invention include those known as two-component carriers for electrophotography, such as iron, ferrite, magnetite, hematite, cobalt, iron-based, magnetite-based, Mn-Mg-Sr-based ferrite, Mn-based. Ferrite, Mn—Mg ferrite, Li ferrite, Mn—Zn ferrite, Cu—Zn ferrite, Ni—Zn ferrite, Ba ferrite, etc. It is not limited to the above example.

[Binder resin]
The resin for forming the coating layer of the carrier of the present invention is not particularly limited as long as it is generally used for carriers.
For example, silicon resin, fluororesin, acrylic resin, reaction product of acrylic resin and amino resin, epoxy resin, polyurethane resin, fluororesin modified silicone resin, acrylic modified silicone resin, epoxy modified silicone resin, urethane modified silicone resin, etc. However, the present invention is not limited to these. Moreover, coating resin may be used individually by 1 type, may be used by multiple, and may be used in a modified | denatured type.

[Solid particles]
In the present invention, solid particles having a small particle size that can be separated from the dispersing beads by filtration, that is, particles having an average primary particle size of 5 to 500 nm can be preferably used.
For example, fine powders of tin oxide, indium oxide doped tin oxide, conductively treated tin oxide, titanium oxide, zinc oxide, iron suboxide, titanium black, carbon black and the like can be mentioned, but are not limited thereto. It is not a thing.
Needle-like powders (titanium oxide, zinc oxide, etc.) and flake-like powders (graphite, aluminum flakes, copper flakes, metal flakes such as nickel flakes, conductive mica, etc.) can be used. These can be used alone or in combination. Further, a high resistance material such as hydrophobized silica or alumina powder can be used in combination.

[Coating solution]
The coating liquid in the present invention is preferably prepared by dissolving or dispersing 0.02 to 90 parts by weight of a binder resin in 100 parts by weight of a liquid medium. In addition, solid particles and other components (if desired) For example, it may contain a resin cross-linking agent, resistance adjusting agent, and the like.
The ratio of the solid particles to the binder resin is preferably in the range of 5/100 to 600/100. The liquid medium that can dissolve or disperse the binder resin may be a commonly used one. For example, petroleum solvents such as normal hexane and kerosene, halogenated hydrocarbon solvents, benzene, toluene, and xylene. Aromatic solvents such as acetone, methyl ethyl ketone, ketone solvents such as methyl isobutyl ketone, alcohol solvents such as methanol, ethanol and isopropanol, ester solvents such as methyl acetate and ethyl acetate, and diethyl ether Ether solvents, cyclic ethers such as tetrahydrofuran and dioxane, glycol ethers such as ethylene glycol monomethyl ether (methyl cellosolve (registered trademark)), ethylene glycol monoethyl ether (ethyl cellosolve (registered trademark)), dimethylform And nitrogen-containing organic solvent such as an amide, and the like, but not limited thereto.

[toner]
The term “for color” as used in the present invention includes not only color toners generally used for a single color, but also black toner in addition to yellow, magenta, cyan, red, green, blue and the like used for full color.
Furthermore, the toner referred to in the present invention may be a general toner regardless of whether it is a monochrome toner, a color toner, or a full color toner. For example, conventionally kneaded and pulverized toners and various polymerized toners that have been used in recent years can be used.

Furthermore, a toner containing a release agent, so-called oilless toner can also be used.
In general, oilless toner contains a release agent, so that the release agent is likely to be transferred to the carrier surface, and so-called spent is likely to occur. Quality can be maintained. In particular, oilless full color toners are generally said to be spent easily because the binder resin is soft, but the carrier of the present invention is very suitable.

As the binder resin used in the toner of the present invention, known resins can be used.
For example, styrene such as polystyrene, poly-p-styrene, and polyvinyltoluene, and homopolymers thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene- Methyl acrylate copolymer, Styrene-ethyl acrylate copolymer, Styrene-methacrylic acid copolymer Corp., Styrene-methyl acrylate copolymer, Styrene-ethyl acrylate copolymer, Styrene-methacrylic acid Butyl copolymer, styrene-α-chloromethacrylic acid methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, Styrene-isopropyl copolymer, styrene-male Styrene copolymers such as acid ester copolymer, polythyme methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified Rosin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, or the like can be used alone or in combination.

Furthermore, as the pressure fixing binder resin, known resins can be mixed and used.
For example, polyolefin such as low molecular weight polyethylene and low molecular weight polypropylene, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-chlorinated Vinyl copolymer, ethylene-vinyl acetate copolymer, olefin copolymer such as ionomer resin, epoxy resin, polyester resin, styrene-butadiene copolymer, polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride, maleic acid modified phenol resin Phenol-modified terpene resins and the like can be used alone or in combination, but are not limited thereto.

The toner used in the present invention may contain a fixing aid in addition to the binder resin, the colorant, and the charge control agent. Accordingly, it can be used in a fixing system in which toner fixing prevention oil is not applied to the fixing roll, so-called oilless system.
Known fixing aids can be used.
For example, polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin waxes, amide waxes, polyhydric alcohol waxes, silicone varnishes, carnauba waxes and ester waxes can be used, but are not limited thereto.

As the colorant used in the toner such as the color toner of the present invention, known pigments and dyes capable of obtaining yellow, magenta, cyan, and black toners can be used, and are not limited to those listed here.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG and Tartrazine Lake. Can be mentioned.
Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.
Examples of purple pigments include fast violet B and methyl violet lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of green pigments include chrome green, chromium oxide, pigment green B, and malachite green lake.
Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides. Moreover, these colorants can use 1 type (s) or 2 or more types.

The toner such as the color toner of the present invention may contain a charge control agent in the toner as necessary.
For example, the color toner of the present invention can contain a charge control agent in the toner as needed. For example, nigrosine, an azine dye containing an alkyl group having 2 to 16 carbon atoms (see Japanese Patent Publication No. 42-1627), a basic dye (for example, CI Basic Yellow 2 (C.I. 41000), C.I. I. Basic Yellow 3, C. I. Basic Red 1 (C.I. 45160), C. I. Basic Red 9 (C.I. 42500), C. I. Basic Violet 1 (C.I. 42535), CI Basic Violet 3 (C.I. 42555), C.I.Basic Violet 10 (C.I.45170), C.I.Basic Violet 14 (C.I. 42510), C.I.Basic Violet Blue 1 (C.I.42025), C.I.Basic Blue 3 (C.I.51005), C.I.Basic Blue 5 (C.I. 42140), C.I.Basic Blue 7 (C.I.42595), C.I.Basic Blue 9 (C.I.52015), C.I.Basic Blue 24 (C.I. I.52030), C.I.Basic Blue 25 (C.I.52025), C.I.Basic Blue 26 (C.I.44045), C.I.Basic Green 1 (C.I.42040), C.I. Lake basic pigment lake pigments such as CI Basic Green 4 (CI 42000), CI Solvent Black 8 (CI 26150), benzoylmethyl hexadecyl ammonium chloride, decyl trimethyl chloride, Quaternary ammonium salts such as dialkyl tin such as dibutyl or dioctyl Compound, dialkyltin borate compound, guanidine derivative, vinyl polymer containing amino group, polyamine resin such as condensation polymer containing amino group, JP-B-41-20153, JP-B-43-27596, Metal complex salts of monoazo dyes described in JP-B-44-6397 and JP-B-45-26478, salicylic acid and dialkylsartyl described in JP-B-55-42752, JP-B-59-7385 Examples include acids, naphthoic acids, dicarboxylic acid Zn, Al, Co, Cr, Fe and other metal complexes, sulfonated copper phthalocyanine pigments, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds, and the like. For other color toners, of course, avoid the use of charge control agents that impair the target color. A white salicylic acid derivative metal salt or the like is preferably used.

As for the external additive, transferability and durability are further improved by externally adding inorganic fine particles such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, boron nitride and resin fine particles to the base toner particles.
This effect can be obtained by covering the wax that lowers transferability and durability with these external additives and reducing the contact area due to the toner surface being covered with fine particles. The surface of these inorganic fine particles is preferably subjected to a hydrophobic treatment, and metal oxide fine particles such as silica and titanium oxide subjected to the hydrophobic treatment are preferably used. As the resin fine particles, polymethyl methacrylate or polystyrene fine particles having an average particle size of about 0.05 to 1 μm obtained by a soap-free emulsion polymerization method are suitably used.

In addition, the combination of hydrophobized silica and hydrophobized titanium oxide increases the amount of hydrophobized titanium oxide externally added compared to the amount of hydrophobized silica externally charged. The toner can also be excellent in stability. In combination with the above-mentioned inorganic fine particles, silica having a specific surface area of 20 to 50 m ² / g and resin fine particles having an average particle diameter of 1/100 to 1/8 of the average particle diameter of the toner are conventionally used. The durability can be improved by externally adding an external additive having a particle size larger than that of the additive to the toner.
This is because the metal oxide particles externally added to the toner tend to be embedded in the base toner particles in the process where the toner is mixed and stirred with the carrier in the developing device, charged, and used for development. This is because it is possible to prevent the metal oxide fine particles from being embedded by externally adding an external additive having a particle size larger than that of the oxide fine particles to the toner.

  The above-mentioned inorganic fine particles and resin fine particles are contained (internally added) in the toner, but the effect is reduced as compared with the case of external addition, but the effect of improving transferability and durability can be obtained and the pulverization property of the toner can be improved. Can do. In addition, since external addition and internal addition can be used together to suppress embedding of externally added fine particles, excellent transferability can be stably obtained and durability can be improved.

In addition, the following are mentioned as a typical example of the hydrophobization processing agent used here.
Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane, 3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinylmethoxysilane, vinyl-tris (β-methoxyethoxy) ) Silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, dimethylvinylchlorosilane, octyl Trichlorosilane, decyl-trichlorosilane, nonyl-trichlorosilane, (4-t-propylphenyl) -trichlorosilane, (4-t-butylphenyl) -trichlorosilane, diventyl-dichlorosilane, dihexyl-dichlorosilane, dioctyl-dichlorosilane, dinonyl -Dichlorosilane, didecyl-dichlorosilane, didodecyl-dichlorosilane, dihexadecyl-dichlorosilane, (4-t-butylphenyl) -octyl-dichlorosilane, dioctyl-dichlorosilane, didecenyl-dichlorosilane, dinonenyl-dichlorosilane, di-2-ethylhexyl-dichlorosilane, di- 3,3-dimethylbenthyl-dichlorosilane, trihexyl-chlorosilane, trioctyl-chlorosilane, tridecyl-chlorosilane Dioctyl-methyl-chlorosilane, octyl-dimethyl-chlorosilane, (4-t-propylphenyl) -diethyl-chlorosilane, octyltrimethoxysilane, hexamethyldisilazane, hexaethyldisilazane, diethyltetramethyldisilazane, hexaphenyldisilazane , Hexatolyl disilazane and the like. In addition, titanate coupling agents and aluminum coupling agents can also be used. In addition, as an external additive for the purpose of improving cleaning properties, a lubricant such as a fatty acid metal salt or a fine particle of polyvinylidene fluoride can be used in combination.

A conventionally known method such as a pulverization method or a polymerization method can be applied to the production of the toner in the invention.
For example, in the case of the pulverization method, as a device for kneading the toner, a batch type two roll, a Banbury mixer or a continuous twin screw extruder, for example, KTK type twin screw extruder manufactured by Kobe Steel, TEM manufactured by Toshiba Machine Co., Ltd. Type twin screw extruder, KCK twin screw extruder, Ikegai Iron Works PCM type twin screw extruder, Kurimoto Iron Works KEX type twin screw extruder, continuous single screw kneader, for example Buss Co-kneader is preferably used.
The melt-kneaded product obtained as described above is cooled and then pulverized. For pulverization, for example, coarsely pulverized using a hammer mill, a funnel plex or the like, and further, a fine pulverizer using a jet stream or mechanical pulverization A machine can be used. The pulverization is desirably performed so that the average particle diameter is 3 to 15 μm. Furthermore, it is preferable that the particle size of the pulverized product is adjusted to 5 to 20 μm by a wind classifier or the like.

  Subsequently, the external additive is externally added to the base toner, and the base toner and the external additive are mixed and stirred using a mixer, and the external additive is crushed and coated on the toner surface. At this time, it is important in terms of durability that external additives such as inorganic fine particles and resin fine particles are uniformly and firmly attached to the base toner. The above is only an example, and the present invention is not limited to this.

[Image Forming Apparatus and Image Forming Method]
An embodiment in which the image forming method of the present invention is carried out by an example of the image forming apparatus of the present invention (for example, the image forming apparatus shown in FIGS. 1 to 4) will be described with reference to FIG.
The image forming apparatus (100) of the example shown in FIG. 1 includes a photosensitive drum (10) as an electrostatic latent image carrier (hereinafter referred to as “photosensitive body (10)”), a roller-shaped charging unit (20), An exposure unit (30), a development unit (40), an intermediate transfer member (50), a cleaning unit (60) having a cleaning blade, and a static elimination lamp as a static elimination unit (70).

  The intermediate transfer member (50) is an endless belt, and is designed to be movable in the direction of the arrow by three rollers (51) that are arranged on the inner side and stretch the belt. A part of the three rollers (51) also functions as a transfer bias roller capable of applying a predetermined transfer bias (primary transfer bias) to the intermediate transfer member (50). A cleaning means (90) having a cleaning blade is disposed in the vicinity of the intermediate transfer member (50), and a developed image (image-forming particle image) is transferred to a transfer paper (95) as a final transfer material. Transfer rollers as transfer means (80) to which a transfer bias for (secondary transfer) can be applied are arranged to face each other. Around the intermediate transfer member (50), there is a corona charger (58) for applying a charge to the image-forming particle image on the intermediate transfer member (50) in the rotational direction of the intermediate transfer member (50). It is arranged between the contact portion between the photoconductor (10) and the intermediate transfer member (50) and the contact portion between the intermediate transfer member (50) and the transfer paper (95).

  The developing means (40) includes a developing belt (41) as a developer carrier, a black developing means (unit) (45K) provided around the developing belt (41), a yellow developing means (unit) (45Y), It is composed of a magenta developing means (unit) (45M) and a cyan developing means (unit) (45C). The black developing means (45K) includes a developer accommodating portion (42K), a developer supply roller (43K), and a developing roller (44K). The yellow developing means (45Y) is provided with a developer accommodating portion ( 42Y), a developer supply roller (43Y), and a development roller (44Y). The magenta developing means (45M) includes a developer accommodating portion (42M), a developer supply roller (43M), and a development roller (44M). The cyan developing means (45C) includes a developer container (42C), a developer supply roller (43C), and a developing roller (44C). Further, the developing belt (41) is an endless belt, is rotatably stretched around a plurality of belt rollers, and a part thereof is in contact with the photoreceptor (10).

In the image forming apparatus (100) shown in FIG. 1, for example, the charging means (20) uniformly charges the photosensitive drum (10). The exposure means (30) performs imagewise exposure on the photosensitive drum (10) to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum (10) is developed by supplying image forming particles from the developing means (40) to form a visible image (image forming particle image).
The visible image (image-forming particle image) is transferred (primary transfer) onto the intermediate transfer body (50) by the voltage applied from the roller (51), and further transferred onto the transfer paper (95) (secondary transfer). ) As a result, a transfer image is formed on the transfer paper (95). The residual image forming particles on the photoreceptor (10) are removed by the cleaning means (60), and the charge on the photoreceptor (10) is once removed by the charge eliminating means (charge eliminating lamp) (70).

Another mode for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG.
The image forming apparatus (100) shown in FIG. 2 does not include the developing belt (41) in the image forming apparatus (100) shown in FIG. 1, and a black developing means (developing unit) (around the photoconductor (10)). 45K), yellow developing means (developing unit) (45Y), magenta developing means (developing unit) (45M) and cyan developing means (developing unit) (45C) are arranged directly opposite to each other, as shown in FIG. The image forming apparatus (100) shown in FIG. In FIG. 2, the same components as those in FIG. 1 are denoted by the same reference numerals.

Still another embodiment for carrying out the image forming method of the present invention by the image forming apparatus of the present invention will be described with reference to FIG.
The tandem image forming apparatus (120) shown in FIG. 3 is a tandem color image forming apparatus. The tandem image forming apparatus (120) includes a copying apparatus main body (150), a paper feed table (200), a scanner (300), and an automatic document feeder (ADF) (400). The copying machine main body (150) is provided with an endless belt-like intermediate transfer member (50) at the center.
The intermediate transfer member (50) is stretched around the support rollers (14), (15) and (16), and can be rotated clockwise in FIG. An intermediate transfer body cleaning device (17) for removing residual image forming particles on the intermediate transfer body (50) is disposed in the vicinity of the support roller (15). The intermediate transfer member (50) stretched between the support roller (14) and the support roller (15) has four image forming units (18) of yellow, cyan, magenta, and black along the conveyance direction. A tandem developing means (120) arranged opposite to each other is arranged. An exposure means (21) is disposed in the vicinity of the tandem developing means (120).
A secondary transfer unit (22) is disposed on the side of the intermediate transfer member (50) opposite to the side on which the tandem type developing unit (120) is disposed. In the secondary transfer means (22), a secondary transfer belt (24), which is an endless belt, is stretched between a pair of rollers (23), and a transfer sheet conveyed on the secondary transfer belt (24); The intermediate transfer member (50) can contact each other. A fixing means (25) is disposed in the vicinity of the secondary transfer means (22). The fixing means (25) includes a fixing belt (26) that is an endless belt, and a pressure roller (27) that is pressed against the fixing belt (26).
In the tandem image forming apparatus (120), in the vicinity of the secondary transfer means (22) and the fixing means (25), sheet reversal for reversing the transfer paper for image formation on both sides of the transfer paper. A device (28) is arranged.

Next, full color image formation (color copying) using the tandem developing means (120) will be described. That is, first, a document is set on the document table (130) of the automatic document feeder (ADF) (400) or the automatic document feeder (400) is opened and the contact glass (32) of the scanner (300) is opened. A document is set on the document and the automatic document feeder (400) is closed.
When a start switch (not shown) is pressed, when a document is set on the automatic document feeder (400), the document is transported and moved onto the contact glass (32). ) Immediately after the document is set on the scanner (300), the first traveling body (33) and the second traveling body (34) travel. At this time, light from the light source is irradiated by the first traveling body (33) and reflected light from the document surface is reflected by the mirror in the second traveling body (34), and passes through the imaging lens (35). The color sensor (color image) is received by the reading sensor (36) and read as black, yellow, magenta and cyan image information.

Each image information of black, yellow, magenta and cyan is stored in each image forming means (18) (black image forming means, yellow image forming means, magenta image forming means and cyan) in the tandem developing means (120). Image forming means), and image forming particle images of black, yellow, magenta and cyan are formed in each image forming means.
That is, each image forming means (18) (black image forming means, yellow image forming means, magenta image forming means, and cyan image forming means) in the tandem developing means (120) is partially enlarged in FIG. As shown in FIG. 4, which is a schematic diagram, the photoreceptor (10) (the photoreceptor for black (10K), the photoreceptor for yellow (10Y), the photoreceptor for magenta (10M), and the photoreceptor for cyan (10C), respectively. ), Charging means (59) for uniformly charging the photoconductor, and exposing the photoconductor to each color image corresponding image based on the color image information (L in FIG. 4). Exposure means for forming an electrostatic latent image corresponding to each color image on the surface, and each color developer (black developer, yellow developer, magenta developer and cyan developer) of the present invention on the electrostatic latent image. Use and develop each A developing means (61) for forming a toner image with a developer, a transfer charger (62) for transferring the developed toner image onto the intermediate transfer body (50), and a photoreceptor cleaning means (63). And a static eliminator (64), and each monochrome image (black image, yellow image, magenta image, and cyan image) can be formed based on the image information of each color.
The black image, the yellow image, the magenta image, and the cyan image thus formed are transferred onto the intermediate transfer member (50) that is rotationally moved by the support rollers (14), (15), and (16) in FIG. The black image formed on the black photoconductor (10K), the yellow image formed on the yellow photoconductor (10Y), the magenta image formed on the magenta photoconductor (10M), and the cyan photoconductor, respectively. The cyan image formed on the body (10C) is sequentially transferred (primary transfer).
Then, the black image, the yellow image, the magenta image, and the cyan image are superimposed on the intermediate transfer member (50) to form a composite color image (color transfer image).

On the other hand, in the paper feed table (200), one of the paper feed rollers (142) is selectively rotated so that the sheet (recording paper) is fed from one of the paper feed cassettes (144) provided in the paper bank (143). ), Separated one by one by the separation roller (145), sent to the paper feed path (146), and conveyed by the conveyance roller (147) to the paper feed path (148) in the copier body (150). Guide and stop against the registration roller (49). Alternatively, the sheet feed roller (142) is rotated to feed out the sheets (recording paper) on the manual feed tray (54), separated one by one by the separation roller (52), and put into the manual feed path (53). Stop against the registration roller (49). The registration roller (49) is generally used while being grounded, but may be used in a state where a bias is applied to remove paper dust from the sheet.
Then, the registration roller (49) is rotated in synchronism with the synthesized color image (color transfer image) in which the respective toners are synthesized on the intermediate transfer member (50), and the intermediate transfer member (50) and the secondary transfer means ( 22), a sheet (recording paper) is sent to the sheet (recording paper), and the composite color image (color transfer image) is transferred (secondary transfer) onto the sheet (recording paper) by the secondary transfer means (22). A color image is transferred and formed on the sheet (recording paper). The residual toner on the intermediate transfer member (50) after the image transfer is cleaned by the intermediate transfer member cleaning device (17).

  The sheet (recording paper) on which the color image has been transferred is transported by the secondary transfer means (22) and sent to the fixing means (25). The fixing means (25) generates heat and pressure. The composite color image (color transfer image) is fixed on the sheet (recording paper). Thereafter, the sheet (recording paper) is switched by the switching claw (55) and discharged by the discharge roller (56) and stacked on the discharge tray (57), or switched by the switching claw (55) and the sheet is reversed. The image is reversed by the device (28) and guided again to the transfer position, and an image is recorded also on the back surface. Then, the image is discharged by the discharge roller (56) and stacked on the discharge tray (57).

  Next, the electrophotographic carrier according to the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited thereto.

・ Acrylic resin solution (solid content ratio: 50 mass%) 85 mass parts ・ Guanamine solution (solid content ratio; 70 mass%) 26 mass parts ・ Acid catalyst (solid content ratio; 40 mass%) 1 mass part ・ Silicone resin solution (Solid content ratio: 20% by mass) 290 parts by mass aminosilane (solid content rate: 100% by mass) 2 parts by mass conductive treatment titanium oxide particles (surface: ITO treatment, primary particle diameter; 50 nm, volume resistivity: 1 0.0 × 10 ² Ω · cm) 185 parts by mass and 1300 parts by mass of toluene were subjected to a dispersion treatment under the following conditions to obtain a coating solution.
・ Bead mill disperser: Ultra Apex mill (UAM-015 type) [manufactured by Kotobuki Industry Co., Ltd.]
・ Bead material: Zirconia (true density; 6.0 g / cm ³ )
Particle size: 0.1mm
・ Bead filling rate (bulk): 40%
・ Rotater speed: 8m / sec
・ Liquid feeding speed: 10 kg / h
・ Jacket temperature: 7 ℃
Next, an average particle diameter of 35 μm sintered ferrite powder [DFC-400M (Mn ferrite, manufactured by DOWA IP Creation Co., Ltd.)] was used as the core particle, and the coating coating solution 1 was coated on the surface of the core particle with a film thickness of 0.2 μm. Then, it was applied and dried at a coater internal temperature of 40 ° C. using a Spira coater (Okada Seiko Co., Ltd.). The obtained carrier was baked by standing in an electric furnace at 150 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an aperture of 63 μm to obtain [Carrier 1].
On the other hand, toner
Binder resin: 100 parts by weight of polyester resin Release agent: 5 parts by weight of carnauba wax Charge control agent: E-84 [manufactured by Orient Chemical Co., Ltd.] 1 part by weight Colorant: C.I. I. P. Y. 180 8 parts by mass Of the above materials, the colorant, binder resin and pure water were mixed at a ratio of 1: 1: 0.5 and kneaded by two rolls. Kneading was performed at 70 ° C., and then the roll temperature was raised to 120 ° C. to evaporate water and prepare a master batch in advance. Using the master batch obtained in this way, weigh the materials so that they are the same as the above recipe, mix with a Henschel mixer, melt knead for 40 minutes at 120 ° C. with two rolls, cool, and then coarsely pulverize with a hammer mill Thereafter, fine powder obtained by fine pulverization with an air jet pulverizer was classified to prepare toner base particles having a weight average particle diameter of 5 μm.
Further, to 100 parts of the toner base material, 1 part of silica whose surface was hydrophobized and 1 part of titanium oxide whose surface was hydrophobized were added and mixed with a Henschel mixer to obtain yellow toner [Toner 1 ] Was obtained.
7 parts of [Toner 1] thus obtained and 93 parts of [Carrier 1] were mixed and stirred to prepare a developer having a toner concentration of 7 wt%.

  In Example 1, before the bead mill dispersion treatment, a homogenizer [manufactured by PRIMIX; K. [Carrier 2] was obtained in the same manner except that a pre-dispersion treatment at 15000 rpm for 10 minutes was carried out using a homomixer MARKII]. Developers were produced for [Carrier 2] and [Toner 1] in the same manner as in Example 1.

[Example 3] Carrier 2 was obtained in the same manner as in Example 2, except that the beads were made of glass and the beads had a true specific gravity of 2.5 g / cm ³ . A developer was produced from [Carrier 3] and [Toner 1] thus obtained in the same manner as in Example 1.

[Carrier 4] was obtained in the same manner as in Example 2 except that the beads were made of silicon nitride and the beads had a true specific gravity of 3.1 g / cm ³ . Developers were produced from [Carrier 4] and [Toner 1] thus obtained in the same manner as in Example 1.

  In Example 2, except that the bead diameter was changed to 0.015 mm, the carrier was converted into [Carrier 5] in the same manner. Developers were produced from [Carrier 5] and [Toner 1] thus obtained by the same method as in Example 1.

  In Example 2, [Carrier 6] was obtained in the same manner except that the bead diameter was changed to 1 mm. Developers were produced from [Carrier 6] and [Toner 1] thus obtained in the same manner as in Example 1.

  In Example 2, [Carrier 7] was obtained in the same manner except that the bead diameter was changed to 5 mm. Developers were produced from [Carrier 7] and [Toner 1] thus obtained by the same method as in Example 1.

  In Example 2, [Carrier 8] was obtained in the same manner except that the bead filling rate was changed to 5%. Developers were produced from the thus obtained [Carrier 8] and [Toner 1] in the same manner as in Example 1.

  In Example 2, [Carrier 9] was obtained in the same manner except that the bead filling rate was changed to 10%. Developers were produced from the thus obtained [Carrier 9] and [Toner 1] in the same manner as in Example 1.

  In Example 2, [Carrier 10] was obtained in the same manner except that the bead filling rate was changed to 80%. Developers were produced from the thus obtained [Carrier 10] and [Toner 1] in the same manner as in Example 1.

  In Example 2, [Carrier 11] was obtained in the same manner except that the bead filling rate was changed to 90%. Developers were produced from the thus obtained [Carrier 11] and [Toner 1] in the same manner as in Example 1.

  In Example 2, [Carrier 12] was obtained in the same manner except that the bead filling rate was changed to 95%. A developer was produced from the thus obtained [Carrier 12] and [Toner 1] in the same manner as in Example 1.

  In Example 2, the carrier was converted into [Carrier 13] in the same manner except that the rotor linear velocity was changed to 3 m / sec. A developer was produced from the thus obtained [Carrier 13] and [Toner 1] in the same manner as in Example 1.

  In Example 2, the carrier was converted into [Carrier 14] in the same manner except that the rotor linear velocity was changed to 4 m / sec. Developers were produced from [Carrier 14] and [Toner 1] thus obtained by the same method as in Example 1.

  In Example 2, the carrier was converted to [Carrier 15] in the same manner except that the rotor linear velocity was changed to 12 m / sec. A developer was produced from the thus obtained [Carrier 15] and [Toner 1] in the same manner as in Example 1.

  In Example 2, [Carrier 16] was obtained in the same manner except that the rotor linear velocity was changed to 14 m / sec. Developers were produced from the thus obtained [Carrier 16] and [Toner 1] in the same manner as in Example 1.

  In Example 2, the carrier was converted into [Carrier 17] in the same manner except that the rotor linear velocity was changed to 20 m / sec. Developers were produced from [Carrier 17] and [Toner 1] thus obtained in the same manner as in Example 1.

  In Example 2, the carrier was converted into [Carrier 18] in the same manner except that the rotor linear velocity was changed to 22 m / sec. Developers were produced from [Carrier 18] and [Toner 1] thus obtained by the same method as in Example 1.

  In Example 2, a carrier was formed in the same manner except that the temperature of the temperature control medium introduced into the jacket for temperature control of the dispersion chamber was changed to −5 ° C. to obtain [Carrier 19]. A developer was produced from the thus obtained [Carrier 19] and [Toner 1] in the same manner as in Example 1.

  In Example 2, [Carrier 20] was obtained in the same manner as in Example 2 except that the temperature of the temperature control medium introduced into the jacket for temperature control of the dispersion chamber was changed to 0 ° C. Developers were produced from the thus obtained [Carrier 20] and [Toner 1] in the same manner as in Example 1.

  In Example 2, a carrier was formed in the same manner except that the temperature of the temperature control medium introduced into the jacket for temperature control of the dispersion chamber was changed to 20 ° C. to obtain [Carrier 21]. Developers were produced from the thus obtained [Carrier 21] and [Toner 1] in the same manner as in Example 1.

  In Example 2, a carrier was formed in the same manner except that the temperature of the temperature control medium put into the jacket for temperature control of the coating coating solution was changed to 25 ° C. to obtain [Carrier 22]. A developer was produced from the thus obtained [Carrier 22] and [Toner 1] in the same manner as in Example 1.

[Comparative Example 1]
In Example 1, a homogenizer [manufactured by PRIMIX; K. In the homomixer MARKII], the coating solution that had been dispersed at 15000 rpm for 10 minutes was used as a carrier to obtain [Carrier 23]. Developers were produced for [Carrier 23] and [Toner 1] in the same manner as in Example 1.

[Comparative Example 2]
In Example 2, the carrier was converted into [Carrier 24] in the same manner except that the bead diameter was changed to 6 mm. A developer was produced from the thus obtained [Carrier 24] and [Toner 1] in the same manner as in Example 1.

[Comparative Example 3]
Instead of the bead mill disperser used in Example 1, a nano-getter (DMR-L110 type) [manufactured by Ashizawa Finetech Co., Ltd., liquid feeding direction: horizontal] is subjected to dispersion treatment to form a carrier [Carrier 25]. Obtained. The operation state at this time is the same as that in the first embodiment. Developers were produced from the thus obtained [Carrier 25] and [Toner 1] in the same manner as in Example 1.

  Using the developers prepared in Examples 1 to 22 and Comparative Examples 1 to 3, background fogging and aging solid carrier adhesion evaluation were performed. The evaluation results are shown in Table 1. In addition, the measurement method and evaluation method regarding the said evaluation item followed the following.

[Skin cover evaluation method]
Developer is set on a commercially available digital full color printer (Imagio MP C5000, manufactured by Ricoh Co., Ltd.), A5 images with an image area of 5% are output by 1 sheet / 1000 JOB, and then an A3 image with an image area of 0% , And observe the toner cover state of the background, ◎ if there is no toner cover, ◯ if it is hardly visible, △ if it is a little visible, △ if it is clearly visible, and ◎, ○ pass And Δ and X were rejected.

[Evaluation method for adhesion of solid carrier over time]
The developer was set on a commercially available digital full-color printer (Imagio MP C5000, manufactured by Ricoh Co., Ltd.), and a running evaluation of 300,000 sheets in a single color was performed. Then, the solid carrier adhesion of the developer after the running was evaluated.
The solid image carrier adhesion evaluation method was evaluated by fixing the background potential to 150 V using the copying machine, developing a solid image on A3 size paper, and observing with a magnifying glass. ◎ when the number of white spots on the image and the total number of carriers actually attached are 0, ◯ when 1 to 3, △ when 4 to 7 and 8 The case of more than one was determined as x, ×, ○, △ were accepted, and x was rejected.

  From the evaluation results shown in Table 1, it is clear that the developers according to Examples 1 to 22 of the present invention have suppressed background fogging and time-dependent solid carrier adhesion as compared with Comparative Examples 1 to 3.

10 Photoconductor (Photoconductor drum)
10K black photoreceptor 10Y yellow photoreceptor 10M magenta photoreceptor 10C cyan photoreceptor 14 support roller 15 support roller 16 support roller 17 intermediate transfer cleaning device 18 image forming means 20 roller charging means 21 exposure means 22 secondary transfer means 23 Roller 24 Secondary transfer belt 25 Fixing means 26 Fixing belt 27 Pressure belt 28 Sheet reversing device 30 Exposure means 32 Contact glass 33 First traveling body 34 Second traveling body 35 Imaging lens 36 Reading sensor 40 Developing means 41 Developing belt 42K developer accommodating portion 42Y developer accommodating portion 42M developer accommodating portion 42C developer accommodating portion 43K developer supplying roller 43Y developer supplying roller 43M developer supplying roller 43C developer supplying roller 44K developing roller 44Y developing roller 44M developing roller 44C Development La 45K black developing means (developing unit)
45Y yellow development means (development unit)
45M Magenta development means (development unit)
45C Cyan development means (development unit)
49 Registration roller 50 Intermediate transfer member 51 Roller 52 Separation roller 53 Manual feed path 54 Manual feed tray 55 Switching claw 56 Discharge roller 57 Discharge tray 58 Corona charger 59 Charging means 60 Cleaning means 61 Developing means 62 Transfer charger 63 Photoconductor cleaning Means 64 Static eliminator 65 Current position 66 Developing device case 67 Developing device case 68 Conveying screw 69 Developing unit partition wall 70 Static eliminating means (static eliminating lamp)
71 toner density sensor 72 developing sleeve 73 developing doctor 75 cleaning blade 76 toner collecting roller 77 collecting bias roller 78 collecting blade 79 collected toner conveying screw 80 transfer roller 90 cleaning unit 95 transfer sheet 100 image forming apparatus 120 tandem developing unit 130 document table 142 paper feed roller 143 paper bank 144 paper feed cassette 145 separation roller 146 paper feed path 147 transport roller 148 paper feed path 150 copier main body 200 paper feed table 300 scanner 400 automatic document feeder (ADF)
L exposure

JP 2007-102159 A JP 2008-70837 A JP 2007-286078 A JP-A-11-184167 JP 2010-102054 A

Claims (10)

A coating coating solution for coating the core material of an electrophotographic carrier, comprising a main dispersion step of dispersing a solution containing at least a binder resin and solid particles using beads of 5 mm or less, and the main dispersion The step is to send the solution from the outside of the dispersion chamber to the lower part of the dispersion chamber, disperse the solution while passing through the stirring unit consisting of the beads and the stirring rotor, and then separate the beads by passing through a centrifugal separation mechanism. Next, a coating coating liquid produced by discharging from the upper part of the dispersion chamber to the outside of the dispersion chamber . The coating coating solution according to claim 1, wherein the coating coating solution is manufactured through a pre-dispersion step without using the beads before the main dispersion step . The coating density according to claim 1 or 2, wherein a true density of the beads is 2.8 g / cm ³ or more . 4. The coating coating solution according to claim 1, wherein a particle diameter of the beads is 0.015 mm or more and 1 mm or less . The coating solution according to any one of claims 1 to 4, wherein a bead filling rate in the main dispersion step is 10% or more and 90% or less . The coating liquid according to any one of claims 1 to 5, wherein a linear velocity of the stirring rotor is 4 m / sec or more and 20 m / sec or less . The main dispersion step includes a jacket for adjusting the temperature in the dispersion chamber, and the temperature of the temperature adjustment medium put into the jacket is 0 ° C. or more and 20 ° C. or less. 6. The coating solution according to any one of 6 . An electrophotographic carrier comprising a coating layer formed by the coating solution according to any one of claims 1 to 7 on the surface of core material particles. An electrophotographic two-component developer comprising a toner and the electrophotographic carrier according to claim 8 . 10. The electrostatic latent image carrier, at least means for forming an electrostatic latent image on the image carrier, and development means for developing the electrostatic latent image, wherein the development means is defined in claim 9 . An image forming apparatus using the two-component developer.

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