JP2007328035A - Electrostatic charge image developer, image forming method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic charge image developer which can improve its flowability in the developing unit, especially maintaining its high resistance by neither generating white or color spots or density changes on images nor scattering toner even when used at a low concentration in a high temperature and humidity, and also provide an image forming method and its device. <P>SOLUTION: This is an electrostatic charge image developer containing toner and carriers at least. The dielectric loss factor ε" of this toner is 12-50. When the cores of the above carriers are magnetic particles, the total energy of the carriers is 1,420-2,920 mJ when measured by using a powder rheometer maintaining the ventilation amount at 5 ml/min, the rotor blade speed at 50 mm/sec at its tip ends, and the rotor blade approach angle at -10°. When the cores are magnetic powder dispersed particles, the total energy of the carriers is 890-1,390 mJ when measured under the same conditions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a developer for developing an electrostatic charge image, an image forming method, and an image forming apparatus used for developing an electrostatic latent image in electrophotography, electrostatic recording method and the like.

  A method of visualizing image information through an electrostatic latent image such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image formed on a photoreceptor by a charging and exposure process is developed with a developer containing toner, and visualized through a transfer and fixing process. Developers used for development include a two-component developer composed of toner and carrier, and a one-component developer used alone, such as magnetic toner, but the two-component developer includes a carrier whose developer is a developer. Since functions such as agitation, transport, and charging are shared and functions are separated as a developer, it has a feature such as good controllability and is currently widely used. In particular, a developer using a carrier coated with a resin has excellent charge controllability, and is relatively easy to improve environment dependency and stability over time. As a developing method, the cascade method has been used in the past, but at present, the magnetic brush method using a magnetic roll as a developer conveying unit is the mainstream.

  In recent years, it is necessary to control the resistance as a developer in order to satisfy the demand for higher image quality. In particular, when wet toner is used, the resistance is remarkably reduced, and fogging due to charge injection, density unevenness due to transfer failure, and the like are likely to occur. Further, the resistance of the developer easily changes depending on the toner concentration. In machines such as printers and copiers, the toner concentration varies depending on the environment, and in environments such as high temperature and high humidity, the toner concentration becomes low and the developer transfer onto the photoconductor due to the low resistance of the developer. Problems arise.

  In order to deal with such problems, a method in which toner particle size / toner dielectric loss ratio / toner fluidity is controlled has been proposed (see, for example, Patent Document 1).

  However, although this method certainly improves the fog, it is difficult to prevent the problem of developer transfer onto the photoreceptor due to a change in toner density. In particular, when black toner is used for a long time under high temperature and high humidity, the stress applied to the toner by the carrier is strong, and the colorant (for example, carbon) on the toner surface is exposed and the resistance is lowered. It becomes more prominent. In recent years, with the trend toward miniaturization and high speed of copying machines and printers, it has become necessary to reduce the size of developing machines themselves and drive them at high speed, and there has been an increasing demand for improvement in mechanical strength and the like for carriers.

JP 2004-29156 A

  The object of the present invention is to improve the fluidity of the developer in the developing unit, and particularly when used at a low toner concentration under high temperature and high humidity, the resistance of the developer is high, and the white spot, color on the image An object of the present invention is to provide a developer for developing an electrostatic charge image, an image forming method, and an image forming apparatus that do not generate dots and have no image density unevenness and toner scattering.

The above problem is solved by the following means. That is,
The developer for developing an electrostatic charge image of the first invention is a developer for developing an electrostatic charge image containing at least a toner and a carrier,
The toner has a dielectric loss factor ε ″ of 12 to 50,
The carrier has at least magnetic particles as a core and a coating layer that covers the surface of the magnetic particles. The carrier has an air flow rate of 5 ml / min, a tip speed of a rotary blade of 50 mm / sec, and a rotary blade. The total energy amount when measured with a powder rheometer under the condition of an entrance angle of −10 ° is 1420 to 2920 mJ.

The electrostatic image developing developer of the second aspect of the present invention is an electrostatic image developing developer containing at least a toner and a carrier,
The toner has a dielectric loss factor ε ″ of 12 to 50,
The carrier has at least a magnetic powder dispersed particle as a core and a coating layer covering the surface of the magnetic powder dispersed particle. The carrier has an air flow rate of 5 ml / min, a tip speed of a rotary blade of 50 mm / sec, The total energy amount is 890 to 1390 mJ when measured by a powder rheometer under the condition that the approach angle of the rotary blade is -10 °.

On the other hand, the image forming method of the present invention comprises:
A charging step for charging the latent image carrier;
Exposing the charged latent image carrier to form an electrostatic latent image on the latent image carrier; and
A developing step of developing the electrostatic latent image with a developer containing toner and a carrier to form a toner image;
A transfer step of transferring the toner image from the latent image carrier to a recording material;
Have
The developer is the developer for developing an electrostatic charge image according to the first or second aspect of the present invention.

  In the image forming method of the present invention, in the developing step, the developer carrying member carrying the developer on the surface rotates at a peripheral speed of 200 mm / s or more and 600 mm / s or less to face the image carrier, It is preferable to have a step of transporting the developer to the image carrier.

The image forming apparatus according to the present invention includes:
A latent image carrier;
Charging means for charging the latent image carrier;
Exposure means for exposing the charged latent image carrier to form an electrostatic latent image on the latent image carrier;
Developing means for developing the electrostatic latent image with a developer including a toner and a carrier to form a toner image;
Transfer means for transferring the toner image from the latent image carrier to a recording material;
Have
The developer is the first or second developer for developing an electrostatic image.

  In the image forming apparatus according to the aspect of the invention, the developing unit is a developer carrying member that carries the developer on a surface thereof, and rotates at a peripheral speed of 200 mm / s or more and 600 mm / s or less to face the image carrier. It is preferable to have a developing carrier that conveys the developer to the image carrier.

According to the present invention,
Improves the fluidity of the developer in the developer, especially when it is used at low toner concentration under high temperature and high humidity, the resistance of the developer is high, does not cause white spots and color spots on the image, Further, it is possible to provide a developer for developing an electrostatic charge image, an image forming method, and an image forming apparatus free from unevenness of image density and toner scattering.

  Hereinafter, the present invention will be described in detail.

  The developer for developing an electrostatic charge image of the present invention includes a toner and a carrier, wherein the toner has a predetermined dielectric loss factor ε ″, and the carrier has a predetermined total energy amount. In particular, even when the toner is used at a low toner concentration under high temperature and high humidity, the resistance of the developer is high, white spots and color spots on the image are not generated, and unevenness of the image density, toner scattering, etc. are eliminated. This is presumed to be based on the following findings.

  First, in the powder rheometer, the inventors measured the total energy amount in the developing device under the conditions of an air flow rate of 5 ml / min, a tip speed of the rotary blade of 50 mm / sec, and an entrance angle of the rotary blade of −10 °. It has been found that there is a high correlation with the fluidity of the carrier when toner is frequently added.

  Furthermore, by setting the total energy amount measured by the powder rheometer for the carrier within a predetermined range and the toner within a predetermined dielectric loss ratio, the surface of the toner when stirred in the developing device It has also been found that the exposure of a colorant (for example, carbon) can be reduced and a decrease in resistance of the developer can be suppressed.

  Such a configuration of the carrier and the toner in the developing device suppresses a decrease in the charging ability of the developer and reduces the occurrence of “fogging” due to low charging. In addition, since a decrease in resistance can be suppressed, an image having no defects such as “color point” and “white point” due to resistance change can be obtained. In addition, since the fluidity is good, the stress on the toner and carrier is reduced, so even if the toner is always sufficiently charged and images are output continuously under high temperature and high humidity, the density reproducibility is high. A good image can be obtained.

  From the above knowledge, the developer for developing an electrostatic charge image of the present invention improves the fluidity of the developer in the developing unit and prevents the colorant from being exposed on the surface of the toner particles. Even when used at a density, the resistance of the developer is high, and it is possible to prevent the generation of white spots and color spots on the image.

Next, fluidity measurement using a powder rheometer will be described.
When measuring the fluidity of particles, it is more influenced by many factors than when measuring the fluidity of liquids, solids, or gases. It is difficult to specify the exact fluidity of the particles. In addition, even if a factor to be measured (for example, particle size) is determined to specify fluidity, the factor actually has little effect on fluidity or only in combination with other factors. The significance of measuring the factor may arise, and even determining the measurement factor is difficult.
Furthermore, the fluidity of the powder varies significantly depending on external environmental factors. For example, in the case of a liquid, even if the measurement environment changes, the fluctuation range of the fluidity is not so large, but the fluidity of the particles is greatly influenced by external environmental factors such as humidity and the state of the flowing gas. fluctuate. It is not clear which measurement factors are affected by these external environmental factors, so even if measured under strict measurement conditions, the reproducibility of the measured values obtained is actually poor. is there.

  In addition, as for the fluidity when the developer is filled in the developer tank, the angle of repose and the bulk density have been used as indices, but these physical property values are indirect to the fluidity of the developer, and It was difficult to quantify and manage the fluidity of the agent.

However, since the powder rheometer can measure the total amount of energy applied from the carrier to the rotor blades of the measuring machine, the powder rheometer can be obtained as a sum of the factors attributable to the fluidity. Therefore, in the powder rheometer, as in the past, for the carrier obtained by adjusting the physical property value and particle size distribution of the surface, determine the items to be measured and find and measure the optimum physical property value for each item. The flowability can be measured directly. As a result, it is possible to determine whether it is suitable as a carrier used for developing an electrostatic charge image only by confirming whether it falls within the above numerical range with a powder rheometer. Such carrier production management is a method that is extremely suitable for practical use as compared to the conventional method of managing by indirect values with respect to keeping the carrier fluidity constant. Moreover, it is easy to make measurement conditions constant, and the reproducibility of measured values is high.
That is, the method for specifying the fluidity by the value obtained by the powder rheometer is simple, accurate and highly reliable as compared with the conventional method.

Using a powder rheometer having such characteristics, the total energy amount is 1420-2820 mJ when the core is a magnetic particle and the value measured under the above specified conditions is the total, and when the magnetic particle is dispersed, the total energy amount is 1420-2820 mJ. By combining a carrier having an energy amount of 890 to 1390 mJ and a toner having a dielectric loss factor ε ″ of 12 to 50, it is possible to prevent the developer from being transferred to the photosensitive member due to a decrease in the resistance of the developer, and on the image due to the developer transfer. It becomes possible not to generate a white spot.

  Further, a carrier having a total energy amount measured by a powder rheometer within the above range can secure fluidity when used for electrostatic charge image development, and can reduce stress due to impact between the toner and the carrier. As a result, since the resistance of the developer does not decrease due to the exposure of the colorant (for example, carbon) on the toner surface, the developer moves onto the photosensitive member, and a white spot is formed on the image portion on the transfer material such as the transferred paper. It is possible to prevent image defects such as the occurrence of image defects.

  Incidentally, in the carrier whose core is magnetic particles, when the measured value of the powder rheometer is lower than 1420 mJ, the friction effect is low and the toner cannot be charged sufficiently. On the other hand, when the value exceeds 2820 mJ, the stress between the toner and the carrier becomes high, so that it is impossible to prevent a decrease in the resistance of the developer due to the surface exposure of the toner. More preferably, the measured value is in the range of 1500 mJ to 2700 mJ, and more preferably in the range of 1600 to 2500 mJ.

  In addition, in a carrier whose core is a magnetic material dispersed particle, if the measured value of the powder rheometer is lower than 890 mJ, the friction effect is low and the toner cannot be sufficiently charged. On the other hand, when the value exceeds 1390 mJ, the stress between the toner and the carrier becomes high, so that it is impossible to prevent a decrease in the resistance of the developer due to the surface exposure of the toner. More preferably, the measured value is in the range of 1000 to 1300 mJ, and more preferably in the range of 1100 to 1200 mJ.

  The specific carrier configuration will be described later.

Next, a measurement method using a powder rheometer will be described.
The powder rheometer is a fluidity measuring device that directly measures fluidity by simultaneously measuring rotational torque and vertical load obtained by rotating a rotating blade spirally in packed particles. By measuring both the rotational torque and the vertical load, the fluidity including the characteristics of the powder itself and the influence of the external environment can be detected with high sensitivity. In addition, since the measurement is performed with the particle filling state kept constant, data with good reproducibility can be obtained.

  In the present invention, measurement is performed using FT4 manufactured by freeman technology as a powder rheometer. In order to eliminate the influence of temperature and humidity before the measurement, a carrier that is left at a temperature of 22 ° C. and a humidity of 50% RH for 8 hours or more is used.

First, a carrier having an inner diameter of 50 mm is filled in a split container having an inner diameter of 50 mm (a cylinder having a height of 51 mm placed on a 160 mL container having a height of 89 mm so that the carrier can be separated vertically).
After filling the carrier, the sample is homogenized by gently stirring the filled carrier. This operation will be called conditioning in the following.

During conditioning, the rotor blades are gently agitated in a rotating direction that does not receive any resistance from the carrier so that it does not stress the filled state, removing most of the excess air and partial stress, and ensuring that the sample is homogeneous. Put it in a state. Specific conditioning conditions are agitation at a tip angle of 60 mm / sec with an approach angle of 5 °.
At this time, the propeller-type rotor blades move downward simultaneously with the rotation, so that the tip draws a spiral, and the angle of the spiral path drawn by the propeller tip at this time is called the entry angle.

  After repeating the conditioning operation four times, the container upper end of the split container is gently moved, and the carrier inside the vessel is worn at a position of 89 mm in height to obtain a carrier filling the 160 mL container. The conditioning operation is carried out because it is important to always obtain a powder having a constant volume in order to stably obtain the total energy of the present invention.

  The carrier thus obtained is transferred to a 200 mL container having an inner diameter of 50 mm and a height of 140 mm. After the carrier was transferred to the 200 mL container, the above operation was further performed five times, and then the inside of the container was moved from the bottom to a height of 110 mm to 10 mm while the air flowed in at a flow rate of 5 ml / min. Rotating torque and vertical load are measured when rotating at a tip speed of 50 mm / sec while moving at °. The direction of rotation of the propeller at this time is the reverse direction to the conditioning (clockwise as viewed from above).

  Here, the measurement is performed while flowing air at 5 ml / min in order to more closely approximate the flow state of the carrier in the developing device. The air flow rate at 5 ml / min is considered to reproduce the flow state immediately after the carrier is stirred by the stirring member. In the FT4 manufactured by freeman technology, the inflow state of the air flow rate is controlled.

The relationship between the rotational torque or the vertical load with respect to the height H from the bottom surface is shown in FIGS. FIG. 2 shows the energy gradient (mJ / mm) with respect to the height H obtained from the rotational torque and the vertical load. The area obtained by integrating the energy gradient in FIG. 2 (shaded portion in FIG. 2) is the total energy amount (mJ). In the present invention, a total energy amount is obtained by integrating a section from 10 mm to 110 mm in height from the bottom surface.
In the present invention, in order to reduce the influence of errors, the average value obtained by performing this conditioning and energy measurement operation cycle five times is defined as the total energy amount (mJ) defined in the present invention.

  As the rotor blade, a blade having a diameter of 48 mm and having a two-blade propeller type shown in FIG. 3 manufactured by freeman technology is used.

Below, the structure of the carrier which has the value of the said total energy amount is demonstrated.
A carrier will not be specifically limited if it corresponds to the above. In addition, as a carrier that realizes the numerical range of the total energy amount by the powder rheometer, a carrier particle having a sufficiently small particle size distribution or a coating layer on the surface of the carrier core is made of a material capable of reducing friction. And those having a carrier shape closer to a true sphere, etc., which are applied alone or in combination.

  The carrier is not particularly limited as long as the above-mentioned conditions are satisfied, but the material of the carrier core is not particularly limited, but in the following, the core is a magnetic particle carrier (carrier of the first aspect) and the magnetic powder dispersed particles. The description will be divided into the carrier (the carrier of the second aspect).

-Carrier of the first aspect (carrier in which the nucleus is composed of magnetic particles)-
In the carrier of the first aspect, the material of the core is, for example, a magnetic metal such as iron, steel, nickel, or cobalt, or an alloy of these with manganese, chromium, rare earth elements, or the like (for example, nickel-iron alloy, cobalt) -Iron alloys, aluminum-iron alloys, etc.) and magnetic oxides such as ferrite and magnetite can be mentioned, but magnetic particles are desirable from the viewpoint of using a magnetic brush method as a developing method.

The volume average particle size of the core in the carrier of the first aspect is preferably 10 μm to 500 μm, more preferably 30 μm to 150 μm, and still more preferably 30 μm to 100 μm. If the volume average particle size of the carrier core is less than 10 μm, the adhesion between the toner and the carrier becomes high when used for electrostatic charge image development, and the development amount of the toner decreases. On the other hand, if it exceeds 500 μm, the magnetic brush becomes rough and it becomes difficult to form a fine image.
The volume average particle diameter of the core in the carrier of the first aspect is a value measured using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13320, manufactured by BECKMAN COULTER). For the particle size range (channel) obtained by dividing the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side, and the particle size that becomes 50% cumulative with respect to the entire core is the volume average particle size D _50v . To do.

The preferred particle size distribution of the core in the carrier of the first aspect is: volume average particle size D _84v / volume average particle size D _50v is 1.20 or less, number average particle size D _50p / number average particle size D _16p The volume average particle diameter D _84v / volume average particle diameter D _50v is 1.15 or less, and the number average particle diameter D _50p / number average particle diameter D _16p is 1.20 or less. .

In order to obtain a nucleus having such a particle size distribution, it can be adjusted to a desired particle size distribution by a gravity classifier, a centrifugal classifier, an inertia classifier, or by sorting with a sieve. .
In particular, in order to obtain the carrier core having the particle size distribution, it is preferable to use an air classifier method, and it is particularly preferable to remove fine powder / coarse powder at the same time in this method.

  When the particle size distribution of the carrier core is wider than the above range, the total energy amount by the powder rheometer described above is out of the specified range, while the particle size distribution tries to be narrower than the above range. Then, work such as classification becomes excessive and work efficiency becomes extremely poor.

The particle size distribution of the core is determined by dividing the obtained particle size distribution by using a laser diffraction / scattering particle size distribution analyzer (LS Particle Size Analyzer: LS13 320, manufactured by BECKMAN COULTER) (channel size). ) to, by subtracting the volume cumulative distribution from the smaller particle size side, the particle diameter at a cumulative 84% relative to the total karyoplast pulling the number cumulative distribution D _84v, the small particle diameter side, relative to the total karyoplast When the particle size that becomes 50% cumulative is D _50p and the particle size that becomes 16% cumulative is D _16p , the coarse particle size distribution index is volume average particle size D _84v / volume average particle size D _50v , and the fine powder side The particle size distribution index is a value obtained as number average particle diameter D _50p / number average particle diameter D _16p .

The density of nucleus is in the carrier of the first aspect is preferably 3.0~8.0g / cm ^3, more preferably 3.5~7.0g / cm ^3, 4.0~ More preferably, it is 6.0 g / cm ³ . When the density is lighter than 3.0 g / cm ³ , it approaches the fluidity state of the toner, so that the charge imparting ability decreases, and when the density is heavier than 8.0 g / cm ³ , the carrier flow This is not preferable because the total energy amount tends to increase beyond the upper limit.

  The density of the nuclei is measured according to the method described in the density section of “Physical Chemistry Experiment Method (Tokyo Kagaku Dojinsha, 3rd Edition)”. For the measurement, pure water having an electric resistance of 17 MΩ or more is used and the measurement temperature is 25 ° C.

  The carrier of the present invention preferably has a coating layer on the surface of the nucleus. The coating layer is preferably a coating resin layer composed of a matrix resin.

A general matrix resin can be used as the matrix resin. For example, polyolefin resins such as polyethylene and polypropylene; polystyrene and acrylic resins, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone and other polyvinyl and polyvinylidene resins; Vinyl-vinyl acetate copolymer; Styrene-acrylic acid copolymer; Straight silicone resin composed of organosiloxane bond or modified product thereof; Fluorine such as polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene, etc. Polyester; Polyurethane; Polycarbonate; Phenol resin; Urea-formaldehyde resin, melamine resin, benzoguanamine resin, resin A resin, amino resins such as polyamide resins; silicone resins; epoxy resins.
These may be used individually by 1 type and may use 2 or more types together.

In particular, it is preferable to use a low surface energy resin such as a fluororesin or a silicone resin as a coating resin in order to prevent contamination from toner components or to improve the fluidity of the carrier, and it is preferable to coat with a fluororesin. More preferred.
Examples of fluororesins include fluoropolyolefins, fluoroalkyl (meth) acrylate polymers and / or copolymers, vinylidene fluoride polymers and / or copolymers, and mixtures thereof, and form fluororesins. Examples of the fluorine-containing monomer include tetrafluoropropyl (meth) acrylate, pentafluoro (meth) acrylate, octafluoropentyl (meth) acrylate, perfluorohexyl (meth) acrylate, perfluorooctylethyl (meta Fluorine-containing fluoroalkyl (meth) acrylate monomers such as acrylate and trifluoroethyl (meth) acrylate are preferred. However, it is not limited to these.

  As a compounding quantity of the monomer containing fluorine, it is preferable to mix | blend in the range of 0.1-50.0 mass% with respect to all the monomers which comprise coating resin, More preferably, it is 0.5. It is the range of -40.0 mass%, More preferably, it is the range of 1.0-30.0 mass%. If the amount is less than 0.1% by mass, it is difficult to ensure contamination resistance. If the amount exceeds 50.0% by mass, the adhesion of the coating resin to the core may be lowered, and the chargeability may be lowered.

  The matrix resin contained in the coating resin layer is preferably 0.5 to 10% by mass, more preferably 1.0 to 5.0% by mass, still more preferably based on the total weight of the carrier. 1.0% by mass to 4.0% by mass. If it is less than 0.5% by mass, the magnetic core particles are likely to be exposed on the surface of the carrier, and the electrical resistance of the carrier tends to be lowered. On the other hand, when it exceeds 10% by mass, the fluidity of the carrier is remarkably lowered, and the toner is difficult to be uniformly charged.

In the coating layer, resin fine particles can be dispersed and contained.
Examples of the resin fine particles include thermoplastic resin particles and thermosetting resin particles. Among these, thermosetting resins that are relatively easy to increase the hardness are suitable, and in order to impart negative chargeability to the toner, it is preferable to use resin particles containing nitrogen atoms. In addition, these resin particles may be used individually by 1 type, and may use 2 or more types together.

  The resin fine particles are preferably dispersed as uniformly as possible in the matrix resin in the thickness direction of the coating resin layer and in the tangential direction to the carrier surface. It is preferable that the resin of the resin fine particles and the matrix resin have high compatibility since the uniformity of dispersion of the resin fine particles in the coating resin layer is improved.

  Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene; polyvinyl such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, and polyvinyl ketone; Polyvinylidene resin; vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; straight silicone resin composed of organosiloxane bond or modified product thereof; polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychloro Fluorine resin such as trifluoroethylene; polyester; polyurethane; polycarbonate and the like.

  Examples of the thermosetting resin used for the resin fine particles include phenol resins; urea-formaldehyde resins, melamine resins, silicone resins, benzoguanamine resins, urea resins, polyamide resins, and other amino resins; epoxy resins; and the like.

  The resin fine resin and the matrix resin may be the same material or different materials. Particularly preferably, the resin of the resin fine particles and the matrix resin are made of different materials.

It is preferable to use thermosetting resin particles as the resin of the resin fine particles because the mechanical strength of the carrier can be improved. A resin having a crosslinked structure is particularly preferable. Further, in order to improve the function of the resin particle as a charging site, it is preferable to use a resin having a quick rise in toner charging. Examples of such resin particles include nylon resin, amino resin, and melamine resin. Nitrogen-containing resin particles are preferred.
The resin fine particles can be granulated while a method of producing granulated resin particles using polymerization such as emulsion polymerization, suspension polymerization, etc., or while a monomer or oligomer is dispersed in a solvent and a crosslinking reaction proceeds. According to a method for producing resin particles, a low molecular component and a crosslinking agent are mixed and reacted by melt kneading, etc., and then pulverized to a predetermined particle size by wind force, mechanical force, etc. Can be manufactured.

  The number average particle diameter of the resin fine particles is preferably from 0.1 to 2.0 μm, more preferably from 0.2 to 1.0 μm. If it is smaller than 0.1 μm, the dispersion in the coating resin layer is lowered. On the other hand, if it is larger than 2 μm, the coating resin layer is likely to fall off, and stable chargeability may not be obtained. The method for measuring the number average particle diameter of the resin fine particles is the same as that for the number average particle diameter of the core.

  The resin fine particles are preferably contained in the coating layer at 1 to 50% by volume, more preferably 1 to 30% by volume, and still more preferably 1 to 20% by volume. When the content of the resin fine particles in the coating resin layer is less than 1% by volume, the effect of the resin fine particles may not be exhibited. When the content exceeds 50% by volume, the coating resin layer is likely to fall off, and stable charging. This is not preferable because the properties may not be obtained.

The coating layer can further contain conductive fine powder dispersed therein.
Examples of the conductive fine powder include metals such as gold, silver, and copper; carbon black; and titanium oxide, magnesium oxide, zinc oxide, aluminum oxide, calcium carbonate, aluminum borate, potassium titanate, and titanic acid. Metal oxides such as calcium powder; fine powders in which the surface of titanium oxide, zinc oxide, barium sulfate, aluminum borate, potassium titanate powder, etc. is covered with tin oxide, carbon black, or metal; . These may be used alone or in combination of two or more. It is preferable to use a metal oxide as the conductive fine powder because the environmental dependency of the charging property can be further reduced, and titanium oxide is particularly preferable.

Furthermore, it is preferable from the viewpoint of improving the dispersion in the coating resin that the conductive fine powder made of the material is treated with a coupling agent. Of these, metal oxides treated with a coupling agent are preferred, and titanium oxide treated with a coupling agent is particularly preferred. The conductive fine powder treated with the coupling agent can be obtained by dispersing the untreated conductive fine powder in a solvent such as toluene, then mixing and treating the coupling agent, and then drying under reduced pressure. it can.
Furthermore, in order to remove the aggregate from the conductive fine powder treated with the obtained coupling agent, it may be crushed by a crusher as necessary. As the crusher, known crushers such as a pin mill, a disk mill, a hammer mill, a centrifugal classification mill, a roller mill, and a jet mill can be used, and a jet mill is particularly preferable. As the coupling agent to be used, known ones such as a silane coupling agent, a titanium coupling agent, an aluminum coupling agent, and a zirconium coupling agent can be used.
Of these, use of a silane coupling agent, particularly conductive fine powder treated with methyltrimethoxysilane, is particularly effective for the environmental stability of charging.

The number average particle diameter of the conductive fine powder is preferably 0.5 μm or less, more preferably 0.05 μm or more and 0.45 μm or less, and still more preferably 0.05 μm or more and 0.35 μm or less. The method for measuring the number average particle diameter of the conductive fine powder is in accordance with the method for measuring the number average particle diameter of the core.
When the number average particle diameter of the conductive fine powder exceeds 0.5 μm, it is not preferred because it is likely to fall off from the coating resin layer and stable chargeability may not be obtained.

The conductive fine powder preferably has a volume electrical resistance of 10 ¹ Ω · cm to 10 ¹¹ Ω · cm, and preferably has a volume electrical resistance of 10 ³ Ω · cm to 10 ⁹ Ω · cm. More preferably. In addition, in this specification, the volume electrical resistance of electroconductive fine powder means the value measured with the following method.
Under normal temperature and normal humidity, the conductive fine powder is filled into a container having a cross-sectional area of 2 × 10 ⁻⁴ m ^{2 so} as to have a thickness of about 1 mm, and then a metal member is formed on the filled conductive fine powder. A load of 1 × 10 ⁴ kg / m ² is applied. A voltage that generates an electric field of 10 ⁶ V / m is applied between the metal member and the bottom electrode of the container, and a value calculated from the current value at that time is defined as a volume electric resistance value.

  The conductive fine powder is usually contained in the coating resin layer in an amount of 1 to 80% by volume, preferably 2 to 20% by volume, more preferably 3 to 10% by volume.

  As a method for forming the coating layer on the surface of the carrier core, the carrier core is prepared by a dipping method in which a solution for forming a coating layer containing the resin, a conductive material and a solvent is prepared and immersed therein. Spray method in which layer forming solution is sprayed on the surface of carrier core, fluidized bed method in which coating layer forming solution is sprayed in a state where carrier core is suspended by fluidized air, or coating with carrier core in a kneader coater Examples thereof include a kneader coater method in which a solvent is removed by mixing with a layer forming solution.

  The solvent used for preparing the coating layer forming solution is not particularly limited as long as it dissolves the resin. For example, aromatic hydrocarbons such as toluene and xylene, ketones such as acetone and methyl ethyl ketone, and the like. And ethers such as tetrahydrofuran and dioxane can be used.

  The average thickness of the coating layer is preferably 0.1 μm to 10 μm, more preferably 0.1 μm to 3.0 μm, and still more preferably 0.1 μm to 1.0 μm. When the average film thickness of the resin coating layer is less than 0.1 μm, the resistance is reduced due to peeling of the coating layer when used for a long time, and when it exceeds 10 μm, it takes time to reach the saturation charge amount, which is not preferable.

  The coating amount by the coating layer is such that the resin solid content is 1.0 part by weight to 5.0 parts by weight with respect to 100 parts by weight of the core particles, and the value of the shape factor SF1 of the carrier is 100. As a result, it is preferable from the viewpoint of improving the fluidity of the carrier, more preferably 1.5 parts by weight to 4.0 parts by weight, and still more preferably 2.0 parts by weight to 3.0 parts by weight. . When less than 1.0 part by weight with respect to 100 parts of the core particles, when an amorphous core is used, the coated carrier tends to be indeterminate and fluidity is poor. If the amount exceeds 5.0 parts by weight, the amount of uncoated material increases, and it tends to adhere to the fixing member and cause poor fixing.

The coating amount by the coating layer can be measured by the following method.
A carrier 2 g coated with a coating layer and 20 ml of toluene are put into a 100 ml beaker, treated with an ultrasonic cleaner (Sharp: UT-105) at 100% output for 10 minutes, and then the carrier is fixed to the lower part of the beaker with a magnet. Remove the supernatant. After repeating this process three times, the carrier is dried and weighed to determine the amount of weight loss from the initial weight, and this weight loss is taken as the coating amount.

Density of the carrier in this way the first mode in which the surface of the core body coated with a resin or the like is preferably ^{3.0~8.0g / cm 3, 3.5~7.0g / cm} 3 It is more preferable that it is 4.0 to 6.0 g / cm ³ . When the density is lighter than 3.0 g / cm ³ , it approaches the fluidity state of the toner, so that the charge imparting ability decreases, and when the density is heavier than 8.0 g / cm ³ , the carrier flow This is not preferable because the total energy amount tends to increase beyond the upper limit. The method for measuring the carrier density is the same as the method for measuring the density of the carrier nucleus.

In addition, for the carrier of the first aspect, the shape factor SF1 represented by the following formula (1) is preferably SF1130 or less, and more preferably 120 or less.
The shape factor SF1 becomes a true sphere as it approaches 100. The greater the carrier shape factor SF1, the lower the fluidity due to the collision between the carriers due to the shape distortion. Therefore, when the shape factor SF1 exceeds 130, the total energy amount tends to increase beyond the upper limit value.

  Specifically, in order to make the shape factor SF1 close to 100, the core temperature itself is increased by making the sintering temperature high, making the particle size of the particles before sintering spherical, or the like. This can be achieved by adopting a method such as bringing the shape factor close to 100 or increasing the amount of coating resin.

Formula (1): Shape factor SF1 = (ML ² / A) × (π / 4) × 100
In formula (1), ML represents the absolute maximum length of carrier particles, and A represents the projected area of carrier particles.

  The average value of the shape factor SF1 is obtained by taking 50 or more carrier particles magnified 250 times from an optical microscope into an image analyzer (LUZEX III, manufactured by Nireco), and calculating the above-mentioned individual particles from the maximum length and projected area. The value of SF1 is obtained and averaged.

The saturation magnetization of the carrier of the first aspect is preferably 40 emu / g or more, and more preferably 50 emu / g or more.
For the measurement of the magnetic properties, a vibrating sample type magnetic measuring device VSMP10-15 (manufactured by Toei Industry Co., Ltd.) is used. The measurement sample is packed in a cell having an inner diameter of 7 mm and a height of 5 mm and set in the apparatus. The measurement applies an applied magnetic field and sweeps up to 1000 oersted. Next, the applied magnetic field is decreased to create a hysteresis curve on the recording paper. Saturation magnetization, residual magnetization, and coercive force are obtained from the curve data. In the present invention, saturation magnetization refers to magnetization measured in a 1000 oersted field.

Volume resistivity of the carrier is preferably controlled in the range of ^{1 × 10 8 ~1 × 10 14} Ωcm, more preferably in the range of ^{1 × 10 8 ~1 × 10 13} Ωcm, 1 × 10 8 More preferably, it is in the range of ˜1 × 10 ¹² Ωcm.
When the volume electrical resistance of the carrier exceeds 1 × 10 ¹⁴ Ωcm, the resistance becomes high and it becomes difficult to work as a developing electrode at the time of development, so that the solid reproducibility is deteriorated such as an edge effect particularly in a solid image portion. On the other hand, when the density is less than 1 × 10 ⁸ Ωcm, the resistance becomes low, so that when the toner concentration in the developer is lowered, charges are injected from the developing roll into the carrier, and the carrier itself is easily developed.

The volume electric resistance (Ω · cm) of the carrier is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
A carrier layer is formed by placing a carrier to be measured flat on a surface of a circular jig having a 20 cm ² electrode plate so as to have a thickness of about 1 to 3 mm. A 20 cm ² electrode plate similar to the above is placed on this and the carrier layer is sandwiched. In order to eliminate the gap between the carriers, the thickness (cm) of the carrier layer is measured after a load of 4 kg is applied on the electrode plate placed on the carrier layer. Both electrodes above and below the carrier layer are connected to an electrometer and a high-voltage power generator. A high voltage is applied to both electrodes so that the electric field is 10 ^3.8 V / cm, and the current value (A) flowing at this time is read to calculate the volume electric resistance (Ω · cm) of the carrier. The calculation formula of the volume electrical resistance (Ω · cm) of the carrier is as shown in the following formula (2).
Formula (2): R = E × 20 / (I−I ₀ ) / L

In the above formula, R is the volume electric resistance (Ω · cm) of the carrier, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage of 0 V, and L is the carrier layer. Represents the thickness (cm). A coefficient of 20 represents the area (cm ² ) of the electrode plate.

-Carrier of the second embodiment (carrier in which the core is composed of magnetic powder dispersed particles)-
The carrier core of the second aspect is composed of magnetic powder-dispersed particles in which magnetic powder is dispersed in a resin.
As the magnetic powder, the magnetic substance described in the magnetic particles can be applied, and among these, iron oxide is preferable. When the magnetic fine particles are iron oxide fine particles, it is advantageous in that the characteristics are stable and the toxicity is low.
These magnetic materials may be used alone or in combination of two or more.

The particle size of the magnetic powder is preferably 0.01 to 1 μm, more preferably 0.03 μm to 0.5 μm, and still more preferably 0.05 μm to 0.35 μm. When the particle size of the magnetic powder is less than 0.01 μm, the saturation magnetization may be lowered, or the viscosity of the composition (monomer mixture) may increase, and a carrier having a uniform particle size may not be obtained. On the other hand, when the particle size of the magnetic powder exceeds 1 μm, it may be impossible to obtain uniform magnetic particles.
The content of the magnetic powder in the magnetic powder dispersed particles is preferably 30% by mass to 95% by mass, more preferably 45% by mass to 90% by mass, and 60% by mass to 90% by mass. More preferably it is. When the content is less than 30% by mass, the dispersion of the magnetic material-dispersed carrier may be caused. When the content exceeds 95% by mass, the ears of the magnetic material-dispersed carrier become hard and may be easily broken. .

  Examples of the resin component in the magnetic powder-dispersed particles include cross-linked styrene resins, acrylic resins, styrene-acrylic copolymer resins, and phenol resins.

  The magnetic powder-dispersed particles of the present invention may further contain other components depending on the purpose in addition to the matrix and the magnetic powder. Examples of the other components include a charge control agent and fluorine-containing fine particles.

As a preferable particle size distribution of the magnetic powder dispersed particles, the volume average particle size D _84v / volume average particle size D _50v is 1.20 or less, the number average particle size D _50p / number average particle size D _16p is 1.25 or less. More preferably, the volume average particle diameter D _84v / volume average particle diameter D _50v is 1.15 or less, and the number average particle diameter D _50p / number average particle diameter D _16p is 1.20 or less.

A method for producing magnetic powder-dispersed particles is, for example, a melt-kneading method in which magnetic powder and an insulating resin such as a styrene acrylic resin are melt-kneaded using a Banbury mixer, a kneader, etc., cooled, ground, and classified ( Japanese Patent Publication No. 59-24416, Japanese Patent Publication No. 8-3679, etc.), a monomer unit of a binder resin and magnetic powder are dispersed in a solvent to prepare a suspension, and this suspension is polymerized. Known are suspension polymerization methods (JP-A-5-1000049, etc.), and spray-drying methods in which a magnetic powder is mixed and dispersed in a resin solution and then spray-dried.
In any of the melt-kneading method, the suspension polymerization method, and the spray-drying method, a magnetic powder is prepared in advance by some means, the magnetic powder and a resin solution are mixed, and the resin solution is mixed in the resin solution. A step of dispersing the magnetic powder.

  When producing magnetic powder-dispersed particles by the melt-kneading method, in order to obtain the above particle size distribution, the particle size distribution should be adjusted to the desired particle size distribution by using a centrifugal classifier, an inertia classifier, or a sieve. Can do.

  When producing magnetic powder dispersed particles by the suspension polymerization method, it is extremely important to adjust the dispersed particle size in order to obtain the above particle size distribution. Temperature during dispersion, amount and type of surfactant, stirring It is important to adjust speed, time, etc.

The volume average particle size of the core in the carrier of the second embodiment is preferably in the range of 10 to 500 μm, more preferably in the range of 30 to 150 μm, and still more preferably in the range of 30 to 100 μm. . If the volume average particle size is less than 10 μm, the carrier easily moves to the photoconductor and the productivity is lowered, and if it exceeds 500 μm, carrier streaks called brush marks are generated on the image, resulting in a rough image. It is not preferable.
The method for measuring the volume average particle diameter of the nucleus is the same as that when the nucleus is a magnetic particle.

In a second aspect nucleus career, density is preferably 2.0~5.0g / cm ^3, more preferably from 2.5 to 4.5 g / cm ^3, 3.0 More preferably, it is ˜4.0 g / cm ³ . When the density is lighter than 2.0 g / cm ³ , it approaches the fluidity state of the toner, so that the charge imparting ability decreases, and when the density is heavier than 5.0 g / cm ³ , the carrier flow This is not preferable because a decrease in property occurs and the total energy tends to increase beyond the upper limit. The method for measuring the density of the nuclei is the same as that for the carrier of the first embodiment.

  As the coating layer formed on the surface of the magnetic powder dispersed particles, the material applied in the coating layer formed on the surface of the magnetic particles can be applied, and preferable materials are also the same. Further, the substances that can be contained in the coating layer and the method for forming the coating layer are the same as in the case of the coating layer on the magnetic particles.

Density of the carrier of the second aspect of the surface of the magnetic powder-dispersed particles provided with the coating layer is preferably 2.0~5.0g / cm ^3, is 2.5 to 4.5 g / cm ³ It is more preferable, and it is still more preferable that it is 3.0-4.0 g / cm < ³ >. When the density is lighter than 2.0 g / cm ³ , it approaches the fluidity state of the toner, so that the charge imparting ability decreases, and when the density is heavier than 5.0 g / cm ³ , the carrier flow This is not preferable because the total energy amount tends to increase beyond the upper limit.

  Regarding the carrier of the second aspect, the shape factor SF1 represented by the above formula (1) is preferably 150 or less, and more preferably 130 or less. The method for obtaining the shape factor SF1 is the same as in the first embodiment.

  Specifically, in order to bring the shape factor SF1 close to 100, heat treatment is performed during the production of the magnetic powder dispersed particles, and the shape factor of the magnetic powder dispersed particles themselves approaches 100 or the amount of the coating resin is increased. It can be achieved by adopting it. When the total energy amount falls below the lower limit, a method opposite to the above method may be adopted.

The saturation magnetization of the carrier of the second aspect is preferably 40 emu / g or more, and more preferably 50 emu / g or more.
The method for measuring the magnetic properties is the same as in the first embodiment.

Volume resistivity of the carrier is preferably controlled in the range of ^{1 × 10 7 ~1 × 10 14} Ωcm, more preferably in the range of ^{1 × 10 8 ~1 × 10 13} Ωcm, 1 × 10 8 More preferably, it is in the range of ˜1 × 10 ¹² Ωcm.
When the volume electrical resistance of the carrier exceeds 1 × 10 ¹⁴ Ωcm, the resistance becomes high and it becomes difficult to work as a developing electrode at the time of development, so that the solid reproducibility is deteriorated such as an edge effect particularly in a solid image portion. On the other hand, if it is less than 1 × 10 ⁷ Ωcm, the resistance becomes low, so that when the toner concentration in the developer is lowered, charges are injected from the developing roll into the carrier, and the carrier itself is easily developed.

  The method for measuring the volume electrical resistance of the carrier is the same as that for the carrier of the first aspect.

Next, the toner will be described.
The toner of the present invention needs to have a dielectric loss factor ε ″ of 12 to 50. The dielectric loss factor ε ″ is preferably 12 to 40, more preferably 12 to 30. When the dielectric loss factor ε ″ is smaller than 12, the charge is increased and the repulsive force between the toners increases, so that the toner may be scattered outside the fine line image in the fine line image. On the other hand, if it exceeds 50, it becomes easy to receive charge injection, and fogging and transfer failure occur, which is not preferable.

Here, the dielectric loss factor is measured by forming a toner powder into a tablet, adjusting the moisture content of the tablet to 0.5% by weight or less, and placing it on the dielectric measurement electrode. To measure. Specifically, 5 g of toner is formed into pellets, set between solid electrodes (Ando Electric, 4274A), and a conductivity of 5 V is applied by an electric conductivity meter (Yokogawa Hewlett-Packard). Was measured, and the dielectric loss factor was determined by the following formula.
Dielectric loss factor = [14.39 / (W × D ² )] × G _x × T _x × 10 ¹⁵
(Where W = 2πf, f: measurement frequency 100 kHz, D: electrode diameter (cm), G _x : conductivity of sample (s), T _x : thickness of sample pellet (cm))

The moisture content can be obtained by the following equation when 1 g is accurately weighed and this is defined as W _1, and the loss on drying after drying at 110 ° C. for 1 hour is defined as W ₂ .
・ Moisture content (% by weight) = [(W ₁ −W ₂ ) / W ₁ ] × 100

  Examples of the method for adjusting the dielectric loss factor include adjusting the moisture absorption amount of the toner constituent material or adjusting the resistance of the toner constituent material.

A specific toner composition contains a binder resin and a colorant as main components.
Binder resins include monoolefins such as ethylene, propylene, butylene and isoprene, vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; methyl acrylate, phenyl acrylate, octyl acrylate, methacryl Α-methylene aliphatic monocarboxylic acid esters such as methyl acid, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone, Homopolymers or copolymers of vinyl ketones such as vinyl isopropenyl ketone are listed. Among these, particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polystyrene, polypropylene, and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin and the like.

  The colorant is not particularly limited. Rose Bengal, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 57: 1, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 12, C.I. I. Pigment Blue 15: 1, Pigment Blue 15: 3, etc. can be used.

  A charge control agent can be added to the toner as needed. When a charge control agent is added to the color toner, a colorless or light-color charge control agent that does not affect the color tone is preferable. As the charge control agent, known ones can be used, but azo metal complexes, salicylic acid or alkylsalicylic acid metal complexes or metal salts are preferably used.

  Further, the toner can contain other known components such as an anti-offset agent such as low molecular weight polypropylene, low molecular weight polyethylene, and wax. As the above wax, paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and the like can be used. Derivatives include oxides, polymers with vinyl monomers, graft modified products, and the like. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides, and the like can be used.

Furthermore, inorganic fine particles can be internally added to the toner in order to facilitate oilless fixing. In order to obtain OHP transparency, inorganic fine particles having a refractive index smaller than that of the toner binder resin are preferable. If the refractive index is too large, the color may become cloudy even in a normal image. Specific examples of the inorganic fine particles include SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO.SiO ₂ , K ₂ O. (TiO ₂ ) n, Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like can be mentioned.
Of these, silica fine particles and titania fine particles are particularly preferable. The silica fine particles may contain anhydrous silica, aluminum silicate, sodium silicate, potassium silicate, etc., but it is desirable to adjust the composition so that the refractive index is 1.5 or less.

In order to reduce the water content of the toner, the surface of these inorganic fine particles is preferably subjected to a hydrophobic treatment in advance. Hydrophobic treatment improves the dispersibility of the inorganic fine particles in the toner, and even when some of the inorganic fine particles inside the toner are exposed on the toner surface, the environmental dependency of charging and the resistance to carrier contamination can be prevented. More effective. This hydrophobizing treatment can be performed by immersing inorganic fine particles in a hydrophobizing agent. Although there is no restriction | limiting in particular in a hydrophobization processing agent, For example, a silane coupling agent, a silicone oil, a titanate coupling agent, an aluminum coupling agent etc. can be used. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.
The amount of the hydrophobizing agent used varies depending on the type of inorganic fine particles and the like, and cannot be specified unconditionally. However, a range of 5 to 50 parts by weight is usually appropriate for 100 parts by weight of the inorganic fine particles.

The toner may contain an external additive in order to improve transferability, fluidity, cleaning properties, chargeability controllability, particularly fluidity. The external additive refers to inorganic fine particles attached to the surface of the toner core particles.
As inorganic fine particles, SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO · SiO ₂ , K ₂ O. (TiO ₂ ) _n , Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgCO ₃ , BaSO ₄ , MgSO _{4 and the} like can be used. Among these, silica fine particles and titania fine particles are particularly preferable because of good fluidity.

  In the present invention, the number average particle diameter of at least one kind of external additive is 10 to 40 nm, preferably 12 to 35 nm, and more preferably 15 to 30 nm. When the number average particle diameter of the external additive is less than 10 nm, the external additive is buried in the toner surface and does not contribute to the fluidity of the toner. On the other hand, when it exceeds 40 nm, it becomes easy to be released from the toner, not only does not contribute to the fluidity of the toner, but also the released external additive adheres to the carrier surface.

The number average particle diameter of the external additive is based on the particle size range (channel) divided by using the particle size distribution obtained by measurement with a laser diffraction type particle size distribution measuring apparatus (for example, LA-700 manufactured by Horiba, Ltd.). The cumulative distribution is drawn from the small particle diameter side for the number, and the particle diameter that becomes 50% cumulative with respect to all external additives can be obtained as the number average particle diameter D _50p .

  In the case of the external additive having the above number average particle diameter, when combined with the carrier of the present invention as defined above, embedding into the toner particles and detachment from the toner particles are suppressed, so that excellent fluidity is exhibited. In addition, the fluidity is excellent in sustainability.

  The amount of the external additive used is preferably such that the surface coverage calculated by the following formula (3) is 10 to 100%, more preferably 12 to 80%, and still more preferably 15 to 60%. .

In the above formula, _{D N} represents the average particle size of the toner core ([mu] m), the [rho _N represents the density of the toner core, _{D a} represents an external additive particle size (nm), ρ _a system adding Represents the density of the agent, and X represents the added amount (% by weight) of the external additive.
In addition, when using a some external additive, it is preferable to make it the total of each surface coverage become 100% or less.

  It is desirable that the surface of the inorganic fine particles of the external additive has been previously hydrophobized. This hydrophobization treatment improves the powder flowability of the toner, and is effective for the environmental dependency of charging and the resistance to carrier contamination. The hydrophobizing treatment can be performed by immersing inorganic fine particles in a hydrophobizing agent. The hydrophobizing agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents and the like. These may be used individually by 1 type and may use 2 or more types together. Of these, silane coupling agents are preferred.

  As the silane coupling agent, for example, any one of chlorosilane, alkoxysilane, silazane, and a special silylating agent can be used. Specifically, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyl Triethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltriethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N, O- (bistrimethylsilyl) acetamide, N, N- (trimethylsilyl) ) Urea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysila , Γ-methacryloxypyrrolyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyl Examples include trimethoxysilane and γ-chloropropyltrimethoxysilane. The amount of the hydrophobizing agent used varies depending on the type of inorganic fine particles and the like, and cannot be specified unconditionally. However, a range of 5 to 50 parts by weight is usually appropriate for 100 parts by weight of the inorganic fine particles.

Further, the degree of hydrophobicity of the external additive by the hydrophobizing agent is preferably 40% to 100%, more preferably 50% to 90%, and still more preferably 60% to 90%.
The degree of hydrophobicity in the present invention is as follows when 0.2 g of fine particles are added to 50 cc of water, stirred with a stirrer, titrated with methanol, and T is the methanol titration when all of the fine particles are suspended in a solvent. It is defined as the degree of hydrophobicity (M) represented by the formula.

  Hydrophobicity (M) = [T / (50 + T)] × 100 (vol.%)

Next, the image forming apparatus (method) of the present invention will be described.
The image forming apparatus (method) of the present invention includes, for example, at least a latent image carrier, a charging unit (charging step) for charging the latent image carrier, and exposing the charged latent image carrier to form a latent image. An exposure means (exposure process) for forming an electrostatic latent image on the carrier, a developing means (development process) for developing the electrostatic latent image with a developer to form a toner image, and the toner image for the latent image. An image forming apparatus (method) having transfer means (transfer process) for transferring from an image carrier to a recording material. Then, the developer of the present invention is applied as a developer.

  Each of these constituent members, that is, a latent image carrier (electrophotographic photosensitive member), a charging device, an exposure device, a developing device, a transfer device, a transmittance measuring mechanism, a cleaning device, and a static eliminating device are described in the present invention. It does not restrict | limit in particular, A conventionally well-known structure can be applied suitably.

  In particular, in the image forming apparatus of the present invention, in the developing means (developing step), a developer carrying body (so-called developing roll (mag roll)) carrying the developer on the surface rotates to face the image carrying body, and It is preferable that the developer is transported to the image carrier.

  The developer carrying member is preferably rotated at a peripheral speed of 200 mm / sec to 600 mm / sec, more preferably 300 mm / sec to 500 mm / sec. When the peripheral speed of the developer carrying member is less than 200 mm / sec, it may not be suitable for the recent increase in speed, which is not preferable. Moreover, it may be inferior in terms of high density reproducibility. On the other hand, when exceeding 600 mm / sec, especially when applied to a small-sized developing machine, distortion of the trimmer occurs due to insufficient mechanical strength of the developing machine, and density reproducibility is inferior due to unevenness of the developer on the developer carrier. This is not preferable.

Hereinafter, the image forming apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 4 is a cross-sectional view schematically showing a basic configuration of a preferred embodiment of the image forming apparatus of the present invention. An image forming apparatus 100 illustrated in FIG. 4 includes an electrophotographic photosensitive member 107, a charging device 108 that charges the electrophotographic photosensitive member 107, a power source 109 connected to the charging device 108, and an electrophotographic image that is charged by the charging device 108. An exposure device 110 that exposes the photosensitive member 107 to form an electrostatic latent image, a developing device 111 that develops the electrostatic latent image formed by the exposure device 110 with toner and forms a toner image, and a developing device 111 A transfer device 112 that transfers the formed toner image to the transfer medium 500, a cleaning device 113 that removes toner remaining on the electrophotographic photosensitive member 107 after transfer, a static eliminator 114, and a fixing device 115 are provided. .

  In the present invention, an image forming apparatus in which the static eliminator 114 is not provided may be used. In the image forming apparatus 100 of FIG. 4, the charging device 108 is a contact type charger, but may be a non-contact type charger.

The configuration of the developing device 111 will be described with reference to FIG.
In FIG. 5, the developing device 111 is disposed adjacent to the electrophotographic photosensitive member 107 so as to be adjacent to the electrophotographic photosensitive member 107 inside the developer housing 10 containing the developer and the developer housing 10. And a developing roll 12 rotatably arranged around the axis. The developing housing 10 is filled with a two-component developer D composed of the toner and the carrier according to the present invention, and the stirring paddle 14 and the stirring screw 16 are driven to rotate so that the toner and the magnetic material are magnetic. The carrier is agitated and the toner is electrostatically adsorbed to the magnetic carrier. The developer having the toner adhered to the magnetic carrier is attracted to the developer transport roll 18 having magnetism by a magnetic force and transported to the development roll 12, and is attracted to the development roll 12, which is a magnet roll, by a magnetic force. Then, a developing bias is applied to the developing roll 12 facing the electrophotographic photosensitive member 107, and the toner is transferred from the developing roll 12 to the portion irradiated with the laser on the electrophotographic photosensitive member 107.

  A toner replenishing device 22 is disposed above the developer housing 10. The toner replenishing device 22 includes a toner cartridge 24 that accommodates the replenishing toner T, and a cartridge replenishing passage 26 that connects the toner cartridge 24 and the developer housing 10 and that can be opened and closed. The toner stored in the toner cartridge 24 is supplied to the developer housing 10 through the cartridge supply passage 26.

  The developer of the present invention is accommodated in the developer housing 10.

FIG. 6 is a sectional view schematically showing a basic configuration of another embodiment of the image forming apparatus of the present invention. An image forming apparatus 200 illustrated in FIG. 6 is an image forming apparatus that forms an intermediate transfer type color image.
In the image forming apparatus 200, four electrophotographic photoreceptors 401 a to 401 d are arranged in parallel along the intermediate transfer belt 409 in a housing 400.
The electrophotographic photoreceptors 401a to 401d form, for example, images in which the electrophotographic photoreceptor 401a is yellow, the electrophotographic photoreceptor 401b is magenta, the electrophotographic photoreceptor 401c is cyan, and the electrophotographic photoreceptor 401d is black. Is possible.

  Each of the electrophotographic photosensitive members 401a to 401d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 402a to 402d, the developing devices 404a to 404d, and the primary transfer roll 410a along the rotation direction. To 410d and cleaning blades 415a to 415d are arranged. Each of the developing devices 404a to 404d can be supplied with toners of four colors, black, yellow, magenta, and cyan accommodated in toner cartridges 405a to 405d, and the primary transfer rolls 410a to 410d are respectively intermediate transfer belts. 409 is in contact with the electrophotographic photoreceptors 401a to 401d.

Further, an exposure device 403 is disposed at a predetermined position in the housing 400, and it becomes possible to irradiate the surfaces of the charged electrophotographic photoreceptors 401a to 401d with a light beam emitted from the exposure device 403. ing. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photosensitive members 401a to 401d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 409 in an overlapping manner.
The intermediate transfer belt 409 is supported with a predetermined tension by a drive roll 406, a backup roll 408, and a tension roll 407, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 413 is disposed so as to contact the backup roll 408 via the intermediate transfer belt 409. The intermediate transfer belt 409 passing between the backup roll 408 and the secondary transfer roll 413 is cleaned by, for example, a cleaning blade 416 disposed in the vicinity of the drive roll 406 and then repeatedly used for the next image forming process. Is done.

  A tray (transfer medium tray) 411 is provided at a predetermined position in the housing 400, and the transfer medium 500 such as paper in the tray 411 is transferred to the intermediate transfer belt 409 and the secondary transfer roll by the transfer roll 412. Then, the paper is sequentially transferred between the two fixing rolls 414 that are in contact with each other and the two fixing rolls 414, and then discharged to the outside of the housing 400.

  Also in the image forming apparatus 200 shown in FIG. 6, the developing devices 404 a to 404 d are configured by the developing device shown in FIG. 5, and the developer of the present invention is accommodated in the developer housing 10.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. The term “parts” means parts by weight unless otherwise specified.

<Measuring method of various characteristics>
First, a method for measuring physical properties of the carrier and toner used in the examples and comparative examples will be described.

-Shape factor-
An optical microscope image of toner dispersed on a nuclear slide glass is taken into an image analyzer (LUZEXIII, manufactured by Nireco) through a video camera, and the equivalent circle diameter of 50 particles is measured. From the maximum length and area, individual particles are measured. SF (1) was calculated from the above formula (1), and the average value was obtained.

-Volume average particle size, particle size distribution-
As a measuring device, a laser diffraction / scattering type particle size distribution measuring device (LS Particle Size Analyzer: LS13 320, manufactured by BECKMAN COULTER) was used.
As a measuring method, 10 to 200 mg of a measurement sample was added to 2 ml of a 5% by weight aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant. This was added to 100 to 150 ml of pure water. The liquid in which the sample is suspended is subjected to dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution is measured at a pump speed of 80% with the LS Particle Size Analyzer: LS13 320, and the volume average particle size is measured as described above. The diameter, coarse particle size distribution, and fine particle size distribution were determined.

-Measurement of molecular weight distribution-
The molecular weight distribution of the toner resin and the carrier coating resin was performed under the following conditions.
Tosoh Corporation HLC-8120GPC, SC-8020 apparatus was used, TSK gei, SuperHM-H (6.0 mm ID × 15 cm × 2) was used as a column, and THF (tetrahydrofuran) was used as an eluent. The measurement conditions were a sample concentration of 0.5%, a flow rate of 0.6 ml / min, a sample injection amount of 10 μl, and a measurement temperature of 40 ° C. The calibration curve was prepared from 10 samples of A-500, F-1, F-10, F-80, F-380, A-2500, F-4, F-40, F-128, and F-700. The data collection interval in the sample analysis was 300 ms.

-Measurement of carrier density-
The density of the carrier nucleus was measured according to the method described above.

-Measurement of coating amount by coating layer-
The coating amount by the coating layer was measured and determined according to the above method as the amount of resin solid content with respect to 100 parts of the core particles.

-Measurement of dielectric loss factor ε "of toner-
The dielectric loss ratio ε ″ of the toner was measured in accordance with the above by compression-molding the toner to prepare a sample disk, and then inserting the disk into an electrode having a diameter of 4 cm.

<Preparation of toner>
(Preparation of black toner (1))
-Preparation of resin fine particle dispersion-
370 parts of styrene, 30 parts of n-butyl acrylate, 8 parts of acrylic acid, 24 parts of dodecanethiol and 4 parts of carbon tetrabromide were mixed and dissolved in a nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd. )) 6 parts and 10 parts of anionic surfactant (Neogen SC: manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) were dissolved in 550 parts of ion-exchanged water, and this was mixed while slowly mixing for 10 minutes. Was charged with 50 parts of ion-exchanged water in which 4 parts of ammonium persulfate was dissolved. After carrying out nitrogen substitution, the inside of the flask was stirred and heated in an oil bath until the contents reached 70 ° C., and emulsion polymerization was continued for 5 hours. As a result, a resin fine particle dispersion in which resin particles of 150 nm, Tg = 58 ° C., and weight average molecular weight Mw = 11500 were dispersed was obtained. The solid content concentration of this dispersion was 40% by weight.

-Preparation of colorant dispersion-
Black pigment (R330: Cabot Corporation): 60 parts Nonionic surfactant (Nonipol 400: Sanyo Chemical Co., Ltd.): 5 parts Ion exchange water: 240 parts

  The above components are mixed, dissolved, stirred for 10 minutes using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then dispersed with an optimizer for 10 minutes to give a colorant having an average particle size of 250 nm. (Black pigment) A colorant dispersant in which particles were dispersed was prepared.

-Preparation of release agent dispersion-
Paraffin wax (HNP0190: manufactured by Nippon Seiwa Co., Ltd., melting point 85 ° C.): 100 parts Cationic surfactant (Sanisol B50: manufactured by Kao Corporation): 5 parts Ion exchange water: 240 parts

  The above components were dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA) for 10 minutes, and then dispersed with a pressure discharge type homogenizer, and the average particle size was 350 nm. A release agent dispersion in which the mold agent particles were dispersed was prepared.

-Preparation of black toner-
-Resin fine particle dispersion: 234 parts-Colorant dispersion: 30 parts-Release agent dispersion: 40 parts-Polyaluminum chloride (PAC100W manufactured by Asada Chemical Co., Ltd.): 1.8 parts-Ion exchange water: 600 parts

  The above components were mixed and dispersed in a round stainless steel flask using a homogenizer (Ultra Turrax T50: manufactured by IKA), and then heated to 52 ° C. while stirring the inside of the flask in a heating oil bath. . After holding at 52 ° C. for 120 minutes, it was confirmed that aggregated particles having a volume average particle diameter D50 of 4.8 μm were generated.

  Thereafter, 32 parts by weight of the resin fine particle dispersion was added to the dispersion containing the aggregated particles, and then the temperature of the heating oil bath was raised to 53 ° C. and held for 30 minutes. The dispersion containing the aggregated particles is added with 1N sodium hydroxide to adjust the pH of the system to 5.0, and then the stainless steel flask is sealed and heated to 95 ° C. while stirring with a magnetic seal. And held for 6 hours.

  After cooling, the toner base particles were filtered off, washed four times with ion exchange water, and then freeze-dried to obtain black toner (1). The toner had a volume average particle diameter D50 of 5.5 μm and a dielectric loss factor of 20.0.

(Adjustment of black toner (2))
A black toner (2) was obtained in the same manner except that the dispersion treatment time of the optimizer for preparing the colorant dispersion was changed to 20 minutes in the adjustment of the black toner (1). The toner had a volume average particle diameter D50 of 5.5 μm and a dielectric loss factor of 12.0.

(Adjustment of black toner (3))
A black toner (3) was obtained in the same manner except that the dispersion treatment time of the optimizer for preparing the colorant dispersion was changed to 30 minutes in the adjustment of the black toner (1). The toner had a volume average particle diameter D50 of 5.5 μm and a dielectric loss factor of 10.0.

(Adjustment of black toner (4))
A black toner (4) was obtained in the same manner as in the preparation of the black toner (3) except that the pigment for preparing the colorant dispersion was BP1300 (manufactured by Cabot Corporation). The toner had a volume average particle diameter D50 of 5.5 μm and a dielectric loss factor of 50.0.

(Adjustment of black toner (5))
A black toner (5) was obtained in the same manner as in the preparation of the black toner (1) except that the pigment for preparing the colorant dispersion was BP1300 (manufactured by Cabot Corporation). The toner had a volume average particle diameter D50 of 5.5 μm and a dielectric loss factor of 52.0.

(Adjustment of externally added toners (1) to (5))
100 parts of each of the above black toners, 0.8 part of rutile type titanium oxide (average primary particle size 20 nm, n-decyltrimethoxysilane treatment), monodispersed spherical silica (silica sol obtained by sol-gel method is treated with HMDS and dried. The pulverized Wardel sphericity Ψ = 0.92, volume average particle diameter D50 = 137 nm, particle size standard deviation = 25 nm) was blended with a Henschel mixer at a peripheral speed of 30 m / s × 15 minutes. Thereafter, coarse particles were removed using a sieve having an opening of 45 μm to obtain externally added toners (1) to (5).

[Example 1]
Ferrite particles (Mn—Mg, true specific gravity 4.5 g / cm ³ , volume average particle size 35 μm, shape factor SF (1) 125) are finely powdered with an elbow jet (manufactured by Nippon Steel Mining Co., Ltd., product number EJ-LABO). Coarse core particles were formed by removing the coarse powder. The particle size distribution of the obtained core particles for coating was as follows: coarse powder side: 1.18, fine powder side: 1.20, volume average particle diameter of 37 μm, and shape factor SF (1) 124.

  20 parts of a toluene solution (solid content 15% by weight) of styrene-methyl methacrylate copolymer (20:80, molecular weight 81000) is added to 100 parts of core particles for coating, and a 50 L batch kneader equipped with a jacket. The mixture was mixed for 10 minutes, and the temperature of the mixture was increased while stirring. After stirring at a temperature of 120 ° C. or higher for 20 minutes, the mixture was cooled and stirred until the temperature of the mixture reached 60 ° C., and the coated carrier was taken out. Thereafter, fine powder / coarse powder removal by an elbow jet was repeated three times to obtain a carrier (1).

  The particle size distribution of the obtained carrier (1) was as follows: coarse powder side: 1.15, fine powder side: 1.16, volume average particle diameter was 37 μm, and shape factor SF (1) was 123.

  In addition, the total energy amount of the obtained carrier (1) was measured by using the powder rheometer FT4 (manufactured by freeman technology) by the method described above, and was 2200 mJ.

  Then, 100 parts of carrier (1) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Examples 2 to 4]
In Example 1, the procedure of removing the fine powder / coarse powder with the elbow jet three times in the resin-coated carrier (1) was repeated three times, and the same procedure was repeated except that the procedure was repeated twice to five times. ) To (4) were produced. The total energy amount of the carriers (2) to (4) was a value shown in Table 1.

  Then, 100 parts of carriers (2) to (4) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare developers. The combinations are shown in Table 1.

[Example 5]
Ferrite particles (Mn—Mg, true specific gravity 4.5 g / cm ³ , volume average particle size 35 μm, shape factor SF (1) 120) are removed with an elbow jet to form core particles for coating. did.

  The particle size distribution of the obtained core particles for coating was as follows: coarse powder side: 1.18, fine powder side: 1.20, volume average particle diameter of 37 μm, and shape factor SF (1) 118.

  60 parts of a perfluoroacrylate copolymer toluene solution (solid content 5 wt%) and 10 parts of a styrene methacrylate copolymer toluene solution (solid content 15 wt%) are added to 100 parts of coating core particles, Mix for 10 minutes in a 50-liter batch kneader equipped with a jacket, increase the temperature of the mixture while stirring, stir for 20 minutes at a temperature of 120 ° C or higher, then cool and stir until the temperature of the mixture reaches 60 ° C The coarse powder was removed with a 75 μm sieve to obtain a carrier (5). The total energy amount of the carrier (5) was a value shown in Table 1.

  Then, 100 parts of carrier (5) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Example 6]
Styrene-butyl acrylate copolymer (80/20): 30 parts (Mw = 1.9 × 10 ⁵ )
Magnetite (EPT-1000, manufactured by Toda Kogyo Co.): 100 parts

  The above components are melt-mixed with a pressure kneader, further pulverized and spheronized using a turbo mill and heat treatment device, and fine and coarse powders are removed with an elbow jet (manufactured by Nippon Steel Mining Co., Ltd., product number EJ-LABO). Powder dispersed particles were formed. 100 parts of the magnetic powder-dispersed particles were placed in a 50-liter batch kneader equipped with a jacket and heated to 120 ° C. or higher with stirring, and then a toluene solution of styrene methacrylate copolymer (solid content 15% by weight) was added to 20 parts. Partly sprayed and then stirred for 20 minutes. After cooling, classification with an elbow jet was further performed 4 times to obtain a carrier (6).

  The particle size distribution of the obtained carrier is as follows: coarse powder side: 1.17, fine powder side: 1.19, volume average particle size 33 μm, shape factor SF (1) 110, true specific gravity is 3.5 g / cm 3. It was. The total energy of carrier (6) was the value shown in Table 1.

Then, 100 parts of carrier (6) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Example 7]
A carrier (7) was produced in the same manner as in Example 6 except that the classification treatment was changed to 3 times. The total energy of carrier (7) was the value shown in Table 1.

  Then, 100 parts of carrier (7) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Example 8]
A carrier (8) was produced in the same manner as in Example 6 except that the classification treatment was changed to 5 times. The total energy of carrier (8) was the value shown in Table 1.

  Then, 100 parts of carrier (8) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Example 9]
A developer was prepared by mixing 100 parts of carrier (1) and 8 parts of externally added toner of black toner (2) in a V blender at 40 rpm for 20 minutes. The combinations are shown in Table 1.

[Example 10]
100 parts of carrier (1) and 8 parts of externally added toner of black toner (4) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Comparative Example 1]
Ferrite particles (Mn—Mg, true specific gravity 4.5 g / cm ³ , volume average particle size 35 μm, shape factor SF (1) 125) were used as they were without classification. To 100 parts of the ferrite particles, 20 parts of a toluene solution of a styrene methacrylate copolymer (solid content 15% by weight) is added and mixed for 10 minutes in a 50-liter batch kneader equipped with a jacket. After raising the temperature and stirring at a temperature of 120 ° C. or higher for 20 minutes, the mixture was cooled and stirred until the temperature of the mixture reached 60 ° C., and the coated carrier was taken out. Thereafter, the coarse powder was removed with a 75 μm sieve to obtain a carrier (9). The total amount of energy of the obtained carrier (9) was 3690 mJ.

  A developer was prepared by mixing 100 parts of carrier (9) and 8 parts of externally added toner of black toner (1) in a V blender at 40 rpm for 20 minutes. The combinations are shown in Table 1.

[Comparative Examples 2-3]
In Comparative Example 1, carriers (10) to (11) were prepared in the same manner except that the coarse powder removal with a 75 μm sieve was changed to the fine powder / coarse powder removal operation with an elbow jet once or twice. did. The total energy amount of the carriers (10) to (11) was a value shown in Table 1.

  Then, 100 parts of carriers (10) to (11) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare developers. The combinations are shown in Table 1.

[Comparative Example 4]
Ferrite particles (Mn—Mg, true specific gravity 4.5 g / cm ³ , volume average particle size 35 μm, shape factor SF (1) 110) are removed with an elbow jet to form core particles for coating. did. The particle size distribution of the obtained core particles for coating was as follows: coarse powder side: 1.18, fine powder side: 1.20, volume average particle diameter of 37 μm, and shape factor SF (1) 109.

  60 parts of a perfluoroacrylate copolymer toluene solution (solid content 5 wt%) and 10 parts of a styrene methacrylate copolymer toluene solution (solid content 15 wt%) are added to 100 parts of coating core particles, Mix for 10 minutes in a 50-liter batch kneader equipped with a jacket, increase the temperature of the mixture while stirring, stir for 20 minutes at a temperature of 120 ° C or higher, then cool and stir until the temperature of the mixture reaches 60 ° C And carrier (12) was obtained. The total energy amount of the carrier (12) was a value shown in Table 1.

  Then, 100 parts of carrier (12) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Comparative Example 5]
A carrier (13) was produced in the same manner except that the classification treatment was changed to twice in Example 6. The total energy amount of the carrier (13) was a value shown in Table 1.

  Then, 100 parts of carrier (13) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Comparative Example 6]
In Example 8, 20 parts of a toluene solution of a styrene methacrylate copolymer, 60 parts of a toluene solution of a perfluoroacrylate copolymer (solid content of 5% by weight) and 10 parts of a toluene solution of a styrene methacrylate copolymer (solid content of 15% by weight) A carrier (14) was produced in the same manner except that it was changed to. The total energy amount of the carrier (14) was a value shown in Table 1.

  Then, 100 parts of carrier (14) and 8 parts of externally added toner of black toner (1) were mixed in a V blender at 40 rpm for 20 minutes to prepare a developer. The combinations are shown in Table 1.

[Comparative Example 7]
A developer was prepared by mixing 100 parts of carrier (1) and 8 parts of externally added toner of black toner (3) in a V blender at 40 rpm for 20 minutes. The combinations are shown in Table 1.

[Comparative Example 8]
A developer was prepared by mixing 100 parts of carrier (1) and 8 parts of externally added toner of black toner (5) in a V blender at 40 rpm for 20 minutes. The combinations are shown in Table 1.

<Evaluation>
Using the developer thus obtained, the following print test was conducted at a sleeve peripheral speed of 350 mm / sec of a mag roll (developing roll) using a modified machine of DocuPrint 405 manufactured by Fuji Xerox.

  This print test was performed by outputting 100000 sheets at a high temperature and high humidity (28 ° C., 85% RH) at an image area ratio of 5%. After 10 sheets were output (initial) and after 100000 sheets were output, the following evaluation was performed. The method was evaluated for the items of image density, fogging, and white spot.

(Evaluation method for uneven density)
An image of 10 cm × 5 cm was output, and the image density after printing 10 sheets and the image density after 100,000 printing were measured by X-rite 938. The image density was measured at 10 points at random, and the difference between the maximum value and the minimum value was obtained. Table 1 shows the results.
The evaluation criteria are as follows, and ◎ and ○ are practical levels.
A: The difference between the maximum value and the minimum value is 0.03 or less. ○: The difference between the maximum value and the minimum value is 0.05 or less. Δ: The difference between the maximum value and the minimum value is 0.10 or less. The difference exceeds 0.10

(Color point / white point evaluation method)
An image with an area coverage of 50% was output to A4 paper, and the number of color spots and white spots was counted.
The evaluation criteria are as follows, and ◎ and ○ are practical levels.
◎: No color point / white point ○: Total less than 5 △: Total less than 10 ×: 10 or more

(Toner scattering evaluation method)
A thin line image having a length of 10 cm was output, and the number of toners present around the thin line was counted with a 50 × magnifier.
The evaluation criteria are as follows, and ◎ and ○ are practical levels.
◎: No scattering toner ○: Total 5 or less △: Total 10 or less ×: Total 10 or more

(Comprehensive evaluation)
Regarding the evaluation items of density unevenness, color point / white point, and toner scattering, evaluation was made with the addition values in the case of ◎ 0 point, ◯ 1 point, △ 2 point, and × 3 point. Judgment criteria are as follows, and ◎ and ○ are practical levels.
◎: Addition value 3 points or less ○: Addition value 4 points to 6 points △: Addition value 7 points to 9 points ×: Addition value 10 points or more

  The obtained evaluation results are shown in Table 1.

  As shown in Table 1, when measured with a powder rheometer under the above conditions, the total energy amount is 1420 to 2920 mJ in the case of an electrostatic charge image developing carrier having a coating layer on the surface of magnetic particles. In the case of a carrier for developing an electrostatic charge image having a coating layer on the surface of the magnetic powder-dispersed particles, since the fluidity was good when it was 890 to 1390 mJ, in addition, the dielectric loss factor ε ″ was 12 to By combining with 50 toner, exposure of the colorant (carbon in this embodiment) on the toner surface is suppressed, and a uniform image density is obtained, and a clear image free from fogging and toner scattering is obtained. It can be seen that even when the toner is used at a low toner concentration under high temperature and high humidity, the resistance of the developer is high and white spots and color spots on the image are not generated.

  Using the developer of Example 1, a print test was performed in the same manner as in the above evaluation, using a modified machine of DocuPrint 405 manufactured by Fuji Xerox, with a sleeve peripheral speed of 180 mm / sec and 620 mm / sec of the mag roll (developing roll). .

  As a result, when the sleeve peripheral speed of the mag roll (developing roll) was 180 mm / sec, uneven density occurred during long-term use.

  On the other hand, when the sleeve peripheral speed of the mag roll (developing roll) is 620 mm / sec, density unevenness occurred during long-term use.

  From these results, it can be seen that the toner of this embodiment is suitable for image formation at a sleeve peripheral speed of a predetermined range of mag roll (developing roll).

It is a figure for demonstrating the measuring method of the total energy amount with a powder rheometer. It is a figure which shows the relationship between the vertical load and energy gradient which were obtained with the powder rheometer. It is a figure for demonstrating the shape of the rotary blade used with a powder rheometer. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. It is sectional drawing which shows a developing device. It is a schematic block diagram which shows the other image forming apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Developer housing 12 Developing roll 14 Stirring paddle 16 Stirring screw 18 Developer conveying roll 100, 200 Image forming apparatus 107, 401a, 401b, 401c, 401d Electrophotographic photosensitive member 108, 402a, 402b, 402c, 402d roll)
110, 403 Exposure device 111, 404a, 404b, 404c, 404d Developing device
112 Transfer device 115, 414 Fixing device (fixing roll)

Claims (6)

A developer for developing an electrostatic image containing at least a toner and a carrier,
The toner has a dielectric loss factor ε ″ of 12 to 50,
The carrier has at least magnetic particles as a core and a coating layer that covers the surface of the magnetic particles. The carrier has an air flow rate of 5 ml / min, a tip speed of a rotary blade of 50 mm / sec, and a rotary blade. A developer for developing an electrostatic charge image, wherein the total energy amount measured by a powder rheometer under a condition of an entrance angle of −10 ° is 1420 to 2920 mJ. A developer for developing an electrostatic image containing at least a toner and a carrier,
The toner has a dielectric loss factor ε ″ of 12 to 50,
The carrier has at least a magnetic powder dispersed particle as a core and a coating layer covering the surface of the magnetic powder dispersed particle. The carrier has an air flow rate of 5 ml / min, a tip speed of a rotary blade of 50 mm / sec, A developer for developing an electrostatic charge image, characterized in that a total energy amount is 890 to 1390 mJ when measured by a powder rheometer under a condition where an entrance angle of a rotary blade is -10 °. A charging step for charging the latent image carrier;
Exposing the charged latent image carrier to form an electrostatic latent image on the latent image carrier; and
A developing step of developing the electrostatic latent image with a developer containing toner and a carrier to form a toner image;
A transfer step of transferring the toner image from the latent image carrier to a recording material,
The image forming method according to claim 1, wherein the developer is the developer for developing an electrostatic image according to claim 1.   In the developing step, the developer carrying body carrying the developer on the surface rotates at a peripheral speed of 200 mm / s or more and 600 mm / s or less to face the image carrying body, and the developer is applied to the image carrying body. The image forming method according to claim 3, further comprising a conveying step. A latent image carrier;
Charging means for charging the latent image carrier;
Exposure means for exposing the charged latent image carrier to form an electrostatic latent image on the latent image carrier;
Developing means for developing the electrostatic latent image with a developer including a toner and a carrier to form a toner image;
Transfer means for transferring the toner image from the latent image carrier to a recording material;
An image forming apparatus having
The image forming apparatus according to claim 1, wherein the developer is the developer for developing an electrostatic image according to claim 1.   The developing means is a developer carrying member that carries the developer on the surface thereof, and rotates at a peripheral speed of 200 mm / s or more and 600 mm / s or less to face the image carrier, and the developer is moved to the image. 6. The image forming apparatus according to claim 5, further comprising a developing carrier that is transported to the carrier.

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