JP6024532B2 - Electrostatic image developer, process cartridge, image forming apparatus and image forming method - Google Patents

Description

  The present invention relates to an electrostatic charge image developer, a process cartridge, an image forming apparatus, and an image forming method.

  For example, a charging device, a developing device, a photosensitive member, and an intermediate transfer member are not contaminated by a developer, and a high-quality image is developed. In order to provide an agent, an electrophotographic toner containing at least a binder resin and a colorant and having a volume average particle size of 10 μm or less, the softening point of the toner is 100 to 130 ° C., and an external additive is mixed The external additive is inorganic fine particles having an average particle size of 100 nm or less of primary particles treated or heat-treated with silicone oil, and the free amount of the silicone oil after treatment is 2.0 to 5. An electrophotographic toner characterized by 0 wt% is disclosed (for example, see Patent Document 1).

  In addition, the charging device, the developing device, the photosensitive member, and the intermediate transfer member are not contaminated by the developer, and high-quality images, particularly background stains with an appropriate image density even when used repeatedly for a long period of time, are extremely dirty. In order to obtain a small number of images, in an electrophotographic recording apparatus having an electrostatic charge image carrier, a charging device and a developing device using a developer for developing an electrostatic charge image containing toner, the toner contains at least a binder resin and a colorant. And an external additive (A) having a volume average particle size of 15 μm or less and an agglomeration degree of 5 to 70. Further, the external additive (A) is an average particle of primary particles subjected to hydrophobic treatment. Solvent of inorganic fine particles having a diameter of 100 nm or less, the residual ratio of the hydrophobic treatment agent after chloroform extraction treatment being 40 to 98.5% on a weight basis, and the hydrophobic treatment Among remaining treatment components , Electrophotographic recording apparatus, which comprises using a toner as an external additive including a compound having at least certain of the organopolysiloxane structure is disclosed (for example, see Patent Document 2).

  Further, in order to provide an external additive used for a developer capable of forming a stable image with no transfer omission, it is composed of inorganic fine particles containing silicone oil, and the release rate of the silicone oil is 10 to 65%. An external additive for electrophotographic toner is disclosed (for example, see Patent Document 3).

JP 2002-351130 A JP 2008-171015 A JP 2009-098700 A

  An object of the present invention is to provide an electrostatic charge image developer in which density unevenness is suppressed.

Specific means for achieving the above object are as follows.
That is, the invention according to claim 1
A toner containing toner particles and oil-treated inorganic particles as an external additive , and a carrier,
The amount of free oil of the toner is 0.008 mass% or more and 0.013 mass% or less,
The total coverage of the toner particles by the external additive is 80% or more and 100% or less,
The amount of free oil of the oil-treated inorganic particles is 0.2% by mass or more and 2.5% by mass or less,
Using a powder rheometer, the total energy measured under the conditions where the tip speed of the rotor blade is 100 mm / sec and the approach angle of the rotor blade is −4 ° is 130 mJ or more and 200 mJ or less when the aeration flow rate is 0 ml / min. And an electrostatic charge image developer that is 20 mJ or more and 50 mJ or less when the aeration flow rate is 10 ml / min.

The invention according to claim 2
The electrostatic charge image developer according to claim 1, wherein the oil-treated inorganic particles are oil-treated silica particles .

The invention according to claim 3
An image carrier,
Development means for containing the electrostatic charge image developer according to claim 1 or 2 and developing the electrostatic charge image formed on the image carrier as a toner image by the electrostatic charge image developer;
Comprising at least
The process cartridge is detachable from the image forming apparatus.

The invention according to claim 4
An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the charged image carrier;
Development means for containing the electrostatic charge image developer according to claim 1 or 2 and developing the electrostatic charge image formed on the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring the toner image to a transfer object;
An image forming apparatus including at least

The invention according to claim 5
A charging step for charging the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the charged image carrier;
A developing step of developing the electrostatic image formed on the image carrier as a toner image by the electrostatic image developer according to claim 1 or 2;
A transfer step of transferring the toner image to a transfer target;
An image forming method having at least

According to the first aspect of the invention, the electrostatic charge image developer in which density unevenness is suppressed as compared with the case where the amount of free oil of the toner is out of the specific range or the total energy is out of the specific range. Is provided .
According to the third aspect of the present invention, the electrostatic charge image developer in which the density unevenness is suppressed as compared with the case where the amount of the free oil of the toner is out of the specific range or the total energy is out of the specific range. And the adaptability to image forming apparatuses having various configurations is enhanced.
According to the invention of claim 4, the electrostatic charge image developer in which density unevenness is suppressed as compared with the case where the amount of free oil of the toner is out of the specific range or the total energy is out of the specific range. An image forming apparatus using the above is provided.
According to the invention of claim 5, the electrostatic charge image developer in which density unevenness is suppressed as compared with the case where the amount of free oil in the toner is out of the specific range or the total energy is out of the specific range. An image forming method using the above is provided.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows an example of the image forming apparatus which concerns on other this embodiment. It is a figure for demonstrating the measuring method of the total energy 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 schematic diagram for demonstrating the shape of the rotary blade used with a powder rheometer.

  Hereinafter, embodiments of the electrostatic charge image developer, process cartridge, image forming apparatus, and image forming method of the present invention will be described in detail.

<Electrostatic image developer>
The electrostatic image developer according to the exemplary embodiment (hereinafter sometimes referred to as the developer according to the exemplary embodiment) includes a toner including toner particles and an external additive, and a carrier, and the toner. The amount of the free oil is 0.002% by mass or more and 0.020% by mass or less, measured using a powder rheometer under the conditions that the tip speed of the rotor blade is 100 mm / sec and the approach angle of the rotor blade is −4 °. The total energy is 120 mJ or more and 230 mJ or less when the aeration flow rate is 0 ml / min, and 10 mJ or more and 55 mJ or less when the aeration flow rate is 10 ml / min.

A developer containing a low stress carrier with a reduced weight per carrier particle reduces the collision stress between the carrier and the toner. It may be easy to become. When a developer containing a low-stress carrier and a replenishment toner that does not have free oil are combined, the non-electrostatic adhesion is weak, so that the replenishment toner is difficult to be held on the carrier. Since the replenishment toner is insufficiently triboelectrically charged, it is easily separated from the carrier by receiving a developing electric field, and is selectively developed. In addition, since the toner in the developing device is difficult to be developed and continues to be subjected to the stress of collision with the carrier and the stress in the developing unit in the developing device, even with a developer designed to reduce the stress, some toners use toner. Deterioration may occur.
In order to improve this, when a technique using a replenishing toner having free oil is applied, the non-electrostatic adhesion is increased and the replenishing toner is easily held on the carrier, so that the selective development of the replenishing toner is improved. However, if the replenishment toner has excessive free oil and the friction between the replenishment toner and the carrier becomes too strong, the specific replenishment toner is likely to be selectively subjected to stress from the carrier or the developer, and the replenishment toner Selective toner degradation may occur.

By using the developer according to this embodiment, the occurrence of density unevenness is suppressed. The reason is not clear, but is presumed as follows.
When the non-electrostatic adhesion force of the replenishment toner to the carrier is improved to a certain range by setting the amount of free oil of the toner to 0.002% by mass or more and 0.020% by mass or less, rubbing between the replenishment toner and the carrier ( (Triboelectric charging) is promoted, and the replenishment toner is triboelectrically charged as much as the toner in the developer. Therefore, the selective development of the replenishment toner is suppressed. Further, since the adhesion force between the replenishing toner and the carrier is maintained in a certain range, the amount of toner remaining on the carrier surface and continuing to be selectively subjected to stress in the developing device is reduced. Therefore, it is presumed that the selective deterioration of the toner is suppressed and the density unevenness of the toner image is less likely to occur.

Here, total energy will be described.
When measuring the fluidity of particles, since it is affected by more factors than when measuring the fluidity of liquids, solids, or gases, the parameters conventionally used, such as particle size and surface roughness, 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 it is even difficult to determine the measurement factor.

  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, fluidity when a developer (or toner) is filled in a developing device is known using an angle of repose or bulk density as an index. These physical property values are related to the fluidity of the developer. On the other hand, it is indirect, and it is difficult to quantify and manage the fluidity of the developer.

  However, since the powder rheometer can measure the total energy applied from the developer (or toner) to the rotating blades of the measuring machine, it can be obtained as a value obtained by adding up the factors caused by the fluidity. Therefore, the powder rheometer determines the items to be measured for the toner obtained by adjusting the physical property value and particle size distribution of the surface and the developer using the toner, as in the past, and the optimum physical properties for each item. Fluidity is measured directly without finding and measuring the value.

  As a result, the fluidity of the developer (or toner) used for developing the electrostatic image can be objectively determined only by confirming whether it falls within the above numerical range with a powder rheometer. Such management of the developer (or toner) is extremely suitable for practical use as compared with the conventional method of managing with the indirect value in order to ensure the fluidity of the intended developer (or toner). It is. Moreover, it is easy to make measurement conditions constant, and the reproducibility of measured values is high.

  That is, the method of specifying the fluidity with the value obtained by the powder rheometer is simple, accurate, and highly reliable as compared with the conventional method.

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

  The powder rheometer is measured using FT4 manufactured by freeman technology. In order to eliminate the influence of temperature and humidity before the measurement, a developer (or toner) is used that has been left at a temperature of 25 ° C. and a humidity of 25% RH for 8 hours or more.

  First, the developer (or toner) is placed in a split container having an inner diameter of 25 mm (a cylinder having a height of 22 mm is placed on a 25 mL container having a height of 61 mm so that it can be separated vertically) with an amount exceeding 61 mm in height. Fill with developer (or toner).

  After the developer (or toner) is filled, an operation of homogenizing the sample is performed by gently stirring the filled developer (or toner). This operation will be called conditioning in the following.

  In conditioning, gently remove the excess air and partial stress by gently agitating the rotor blades in a rotating direction that does not receive resistance from the toner so as not to stress the developer (or toner) in the filled state. , Make the sample homogeneous. Specific conditioning conditions are that the inside of the container is agitated at a tip angle of 40 mm / sec from the height 70 mm to 2 mm from the bottom surface at an entrance angle of 4 °.

  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 upper end of the split container is gently moved, and the developer (or toner) inside the vessel is worn at a position of 61 mm in height to obtain a toner that fills the 25 mL container. The conditioning operation is performed because it is important to always obtain a powder having a constant volume in order to obtain the total energy stably.

  Furthermore, after performing the conditioning operation once, the rotational torque when rotating at the tip speed of the rotor blades of 100 mm / sec while moving in the container from the height 55 mm to 2 mm from the bottom surface at an entrance angle of −4 ° Measure the vertical load. The direction of rotation of the propeller at this time is the reverse direction to the conditioning (clockwise as viewed from above).

3A and 3B show the relationship between the rotational torque or the vertical load with respect to the height H from the bottom surface. FIG. 4 shows an energy gradient (mJ / mm) with respect to the height H obtained from the rotational torque and the vertical load. The area (shaded portion in FIG. 4) obtained by integrating the energy gradient in FIG. 4 is the total energy (mJ). The total energy is obtained by integrating the section from 2 mm to 55 mm in height from the bottom.
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 total energy (mJ).

  The rotor blade has a diameter of 23.5 mm of a two-blade propeller type shown in FIG. 5 manufactured by freeman technology.

  Then, when measuring the rotational torque and vertical load of the rotor blade, the total energy is measured while flowing air from the bottom of the container at a target air flow rate (ml / min) as required. In the present embodiment, specifically, the total energy when the aeration flow rate is 0 ml / min and the total energy when the aeration flow rate is 10 ml / min are measured. In the FT4 manufactured by freeman technology, the inflow state of the aeration flow rate is controlled.

In the present embodiment, the total energy when the ventilation flow rate is 0 ml / min represents the low collision stress between the carrier and the toner (low stress developer). If the total energy at an air flow rate of 0 ml / min is 120 mJ or more and 230 mJ or less, it suggests that the low stress developer has a liquid crosslinking force derived from low free oil, and the adhesion force between the toner and the carrier is controlled. Therefore, selective toner deterioration is suppressed.
On the other hand, in this embodiment, the total energy when the aeration flow rate is 10 ml / min represents the flowability of the developer after the start of stirring. If the total energy at the air flow rate of 10 ml / min is 10 mJ or more and 55 mJ or less, the developer is hard to contain air and is not easily stirred and floats, so that it works in a direction that is particularly advantageous for charging the replenishment toner. As a result, the difference in charging and adhesion between the replenishing toner and the toner in the developing device is reduced, and the selective development of the replenishing toner is suppressed.
It is assumed that density unevenness of the toner image is less likely to occur by suppressing the selective toner deterioration and the selective development of the replenishment toner.

Hereinafter, the developer according to the exemplary embodiment will be described in detail.
The developer according to the present embodiment is a two-component developer including a toner and a carrier.
The toner includes toner particles and an external additive. Further, the amount of free oil in the toner is set to 0.002% by mass or more and 0.020% by mass or less.

  The mixing ratio (mass ratio) of toner and carrier in the two-component developer is preferably in the range of toner: carrier = 1: 100 to 30: 100, more preferably in the range of 3: 100 to 20: 100. desirable.

The total energy of the developer satisfies the above range.
To adjust the total energy when the aeration flow rate is 0 ml / min and the total energy when the aeration flow rate is 10 ml / min in the developer, for example, the shape of the toner particles, the toner particle size, the toner particle size distribution, the external addition It is carried out by adjusting the type of the additive, the particle size of the external additive, the amount of the external additive added, the type of carrier, the particle size of the toner, the particle size distribution of the carrier, and the like.

  Hereinafter, each element suitable for the total energy of the developer to satisfy the above range will be described.

First, toner particles will be described.
The average circularity of the toner particles is, for example, preferably from 0.945 to 0.997, and more preferably from 0.955 to 0.980.
Here, the average circularity of the toner particles is obtained by (equivalent circumference of circle) / (perimeter) [(perimeter of a circle having the same projection area as the particle image) / (perimeter of the projected particle image)]. A flow-type particle image analyzer (for example, Sysmex Corporation) takes a particle image as a still image by sucking and collecting the toner to be measured, forming a flat flow, and instantly flashing light, and analyzing the particle image. Obtained by FPIA-2100). The number of samplings when obtaining the average circularity is 3500.

  The volume average particle size of the toner particles is preferably 2.9 μm or more and 6.2 μm or less, and more preferably 3.2 μm or more and 4.9 μm or less.

As the particle size distribution characteristic of the toner particles, the volume average particle size distribution index (GSDv) is, for example, preferably 1.25 or less, and preferably 1.22 or less.
The smaller the volume average particle size distribution index (GSDv) of the toner particles, the more uniform the particle size. By adjusting the particle size distribution characteristic, the total energy in the powder rheometer can be easily controlled.

Here, the volume average particle diameter of the toner particles is measured as follows.
First, Coulter Multisizer II (manufactured by Coulter, Inc.) is used as a measuring device. As the electrolytic solution, 1% NaCl aqueous solution is prepared using first grade sodium chloride. For example, ISOTON-II (manufactured by Coulter Scientific Japan) is used. As a measuring method, 0.1 ml or more and 5 ml or less of a surfactant (desirably alkylbenzene sulfonate) is added as a dispersant in 100 ml or more and 150 ml or less of an aqueous electrolyte solution, and further 2 mg or more and 20 mg or less of a measurement sample is added. The electrolyte in which the sample is suspended is subjected to a dispersion treatment for 1 minute or more and 3 minutes or less with an ultrasonic disperser, and the volume or number of toner (toner particles) is measured for each channel using a 100 μm aperture as an aperture by a measuring device. The volume particle size distribution or number particle size distribution of the toner is calculated. The above measurement is performed after the toner is dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.

Then, a cumulative distribution is drawn from the small diameter side to the particle size range (channel) divided on the basis of the measured particle size distribution, and the particle diameter that becomes 16% is defined as the volume particle diameter D _16v , Number particle size D _16P , particle size to be accumulated 50% is volume average particle size D _50v , number average particle size D _50P , particle size to be accumulated particle size 84% is volume particle size D _84v , number particle size D _84P Define.

  On the other hand, when the particle diameter to be measured is less than 2 μm, the measurement is performed using a Microtrac (manufactured by Nikkiso Co., Ltd., Microtrac UPA9340). As a measurement method, a sample in a dispersion is adjusted to have a solid content of about 2 g, and ion exchange water is added thereto to make about 40 ml. This is put into the cell until an appropriate concentration is reached, waits for about 2 minutes, and is measured when the concentration in the cell becomes almost stable.

  The toner particles may have a single layer structure or a structure (so-called core / shell structure) constituted by a core part and a coating layer covering the core part.

The configuration of the toner particles will be described.
The toner particles include, for example, a binder resin and, if necessary, other additives such as a colorant and a release agent.

  The binder resin is not particularly limited. For example, styrenes such as styrene, parachlorostyrene, and α-methylstyrene; methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, acrylic Esters having vinyl groups such as lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate; vinyl nitriles such as acrylonitrile and methacrylonitrile Vinyl ethers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; single quantities of polyolefins such as ethylene, propylene and butadiene Homopolymer consisting of, or copolymers obtained by combining two or more of these, more mixtures thereof. In addition, epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, etc., non-vinyl condensation resins, or a mixture of these with the vinyl resin, or vinyl monomers in the presence of these resins Examples thereof include a graft polymer obtained by polymerization.

A styrene resin, a (meth) acrylic resin, and a styrene- (meth) acrylic copolymer resin are obtained by a known method, for example, using a styrene monomer and a (meth) acrylic monomer alone or in combination. . “(Meth) acryl” is an expression including both “acryl” and “methacryl”.
The polyester resin can be obtained by selecting and combining suitable ones from a polyvalent carboxylic acid and a polyhydric alcohol and synthesizing them using a conventionally known method such as a transesterification method or a polycondensation method.

  When using a styrene resin, a (meth) acrylic resin or a copolymer resin thereof as a binder resin, the weight average molecular weight Mw is 20,000 or more and 100,000 or less, and the number average molecular weight Mn is 2,000 or more and 30,000 or less. It is desirable to use the thing of the range. On the other hand, when a polyester resin is used as the binder resin, a resin having a weight average molecular weight Mw of 5,000 or more and 40,000 or less and a number average molecular weight Mn of 2,000 or more and 10,000 or less may be used. desirable.

Here, as the binder resin, an amorphous resin and a crystalline resin may be used in combination.
The crystalline resin is preferably used in the range of 5% by mass to 30% by mass among the components constituting the toner particles. The amorphous resin is preferably used in the range of 50% by mass to 90% by mass among the components constituting the toner particles.

The “crystalline resin” refers to a resin having a clear endothermic peak, not a stepwise change in endothermic amount in differential scanning calorimetry (DSC). Specifically, it means that the half-value width of the endothermic peak when measured at a heating rate of 10 ° C./min is within 6 ° C.
On the other hand, a resin having a half-value width exceeding 6 ° C. or a resin having no clear endothermic peak means an amorphous resin, but the amorphous resin used in the present embodiment has a clear endothermic peak. It is better to use an unrecognized resin.

The crystalline resin is not particularly limited as long as it is a resin having crystallinity, and specific examples include crystalline polyester resins and crystalline vinyl resins, but crystalline polyester resins are preferred, especially aliphatic resins. The crystalline polyester resin is preferable.
The crystalline polyester resin and all other polyester resins are synthesized from, for example, a polyvalent carboxylic acid component and a polyhydric alcohol component.
In addition, a commercial item may be used as a polyester resin, and what was synthesize | combined may be used.

The colorant is selected from known colorants according to the intended toner color.
As the colorant, a surface-treated colorant may be used as necessary, or it may be used in combination with a dispersant. A plurality of colorants may be used in combination. As content of a coloring agent, the range of 1 to 30 mass parts is desirable with respect to 100 mass parts of binder resin.

  Examples of mold release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; ester types such as fatty acid esters and montanic acid esters Wax; and the like, but is not limited thereto.

  The content of the release agent is preferably 1 part by mass or more and 15 parts by mass or less, more preferably 2 parts by mass or more and 12 parts by mass or less, and further preferably 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the toner particles. More desirable.

  Examples of other internal additives include magnetic materials, charge control agents, inorganic powders, and the like.

Next, the external additive will be described.
As at least one external additive, oil-treated inorganic particles are applied. The oil-treated inorganic particles are inorganic particles that have been surface-treated with oil.

  Examples of inorganic particles (inorganic particles to be subjected to surface treatment with oil) include silica, alumina, titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, iron oxide, copper oxide, and zinc oxide. , Tin oxide, silica sand, clay, mica, wollastonite, diatomaceous earth, chromium oxide, cerium oxide, bengara, antimony trioxide, magnesium oxide, zirconium oxide, barium sulfate, barium carbonate, calcium carbonate, silicon carbide, silicon nitride And the like. Among these, silica particles are particularly preferable as the inorganic particles.

On the other hand, examples of the oil include silicone oil.
Examples of the silicone oil include dimethyl silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, methyl hydrogen silicone oil, alkyl-modified silicone oil, fluorine-modified silicone oil, polyether-modified silicone oil, alcohol-modified silicone oil, and amino-modified. Examples include silicone oil, epoxy-modified silicone oil, epoxy-polyether-modified silicone oil, phenol-modified silicone oil, carboxyl-modified silicone oil, mercapto-modified silicone oil, acrylic, methacryl-modified silicone oil, and α-methylstyrene-modified silicone oil.

  In the oil-treated inorganic particles, the surface treatment of the oil to the inorganic particles may be performed, for example, by bringing the oil into contact with the dehydrated and dried inorganic particles and attaching the oil to the surface of the inorganic particles, followed by heating. Good. In particular, in order to control the amount of free oil in a certain region, it is necessary to increase the adhesion between the oil and the inorganic particles. (1) A method using inorganic particles in a wet process having many reactive groups with oil, (2 ) A method using silica particles having many reactive groups as a material species, (2) A method of removing reaction inhibitors such as impurities adhering to the surface of inorganic particles in advance by plasma treatment or pH treatment (wet cleaning), etc. Is effective.

The oil-treated inorganic particles have a free oil amount of 0.2% by mass to 2.9% by mass (preferably 0.2% by mass to 2.5% by mass, more preferably 0.3% by mass to 0.8% by mass). % Or less) inorganic particles.
By setting the amount of this free oil to 0.2% by mass or more, the non-electrostatic adhesion force of the inorganic particles is increased and the carrier is easily held by the carrier.
By setting the free oil amount to 2.9% by mass or less, excessive rubbing between the toner and the carrier is suppressed, and as a result, selective deterioration of the toner is suppressed.

Here, the amount of free oil of the oil-treated inorganic particles is determined as follows. The “fixed carbon amount” is an index of the maximum amount of oil that can be bonded to the surface of inorganic particles by chemical bonding. The “free carbon amount” refers to an amount of oil physically adsorbed on the surface of the inorganic particles, that is, an index of the free oil amount.
(Total carbon content)
The total carbon amount (% by mass) of the external additive is measured by a trace carbon analyzer (manufactured by EMIA Horiba).
(Fixed carbon content)
A Soxhlet extractor is used to remove a treatment agent that is not chemically adsorbed from a treatment agent such as silicone oil that has been treated on the surface of the external additive with an organic solvent. Specifically, the solid content obtained by extraction under conditions of 10 g of THF, 3 g of sample and 24 hours and then solid-liquid separation using a centrifuge is similarly measured with a trace carbon analyzer (manufactured by EMIA Horiba). Let the obtained carbon content be a fixed carbon amount.
(Free carbon content)
The amount of free carbon is determined by the following formula.
Free carbon = Total carbon-Fixed carbon

The volume average particle diameter of the oil-treated inorganic particles is preferably 30 nm or more and 100 nm or less, and preferably 60 nm or more and 90 nm or less.
By setting the volume average particle size of the oil-treated inorganic particles to 30 nm or more, it is easy to act on the contact state between the toner particles and the carrier, and the effect of non-electrostatic adhesion is easily secured.
On the other hand, when the volume average particle diameter of the oil-treated inorganic particles is 100 nm or less, the oil-treated inorganic particles are not easily released from the toner surface, but remain on the surface of the toner particles and easily act on the contact state between the toner particles and the carrier.

  The volume average particle diameter of the oil-treated inorganic particles is determined by multiplying 100 primary particles of the oil-treated inorganic particles after the oil-treated inorganic particles are externally added (dispersed) to the toner particles by a SEM (Scanning Electron Microscope) apparatus at a magnification of 40000 times. The longest diameter and the shortest diameter of each particle are measured by image analysis of primary particles, and the equivalent sphere diameter is measured from this intermediate value. The 50% diameter (D50v) in the cumulative frequency of the obtained equivalent sphere diameter is defined as the average particle diameter (that is, volume average particle diameter) of the oil-treated inorganic particles.

In the present embodiment, it is preferable to use silica particles having a free oil amount of 0.2% by mass or more and 2.9% by mass or less as at least one external additive. By using such silica particles as an external additive, the free oil amount of the toner according to the exemplary embodiment is easily set in a range of 0.002% by mass or more and 0.020% by mass or less.
The volume average particle diameter of the silica particles is preferably 30 nm or more and 100 nm or less. By setting the volume average particle size of the silica particles in the above range, the toner and the carrier are brought into contact with each other, and the adhesion force of the toner to the carrier due to the liquid crosslinking force is improved in a certain region.
The amount of free oil in the toner is 0.002% by mass or more and 0.020% by mass or less, preferably 0.008% by mass or more and 0.015% by mass or less.

  In addition to the oil-treated inorganic particles, other external additives may be used in combination as long as the effects are not impaired. Other external additives include well-known materials such as inorganic particles and organic particles. Examples of the inorganic particles include silica (for example, fumed silica, sol-gel silica), alumina, titania, metatitanic acid, zinc oxide, tin oxide, iron oxide, calcium carbonate, magnesium carbonate, tricalcium phosphate, cerium oxide. Well-known particles used as external additives for normal toners such as tin oxide and iron oxide. Examples of the organic particles include known particles used as an external additive for normal toners such as vinyl resins, polyester resins, silicone resins, and fluorine resins.

These other external additives are also preferably subjected to a hydrophobic treatment on the surface. Examples of the hydrophobizing agent include known surface treating agents, and specific examples include silane coupling agents and silicone oils.
Examples of silane coupling agents include hexamethyldisilazane, trimethylsilane, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, allyldimethylchlorosilane, benzyldimethylchlorosilane, methyltrimethoxysilane, methyltriethoxysilane, and isobutyltrimethoxysilane. , Dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylmethoxysilane, hydroxypropyltrimethoxysilane, phenyltrimethoxysilane, n-butyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, vinyltrimethoxy Silane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, etc. And the like.
Examples of the silicone oil include dimethylpolysiloxane, methylhydrozine polysiloxane, methylphenylpolysiloxane, and the like.

  The external additive described above is preferably added in an amount of 0.5 to 6.0 parts by weight, more preferably 1.0 to 5.0 parts by weight with respect to 100 parts by weight of the toner particles. More preferably, it is 2.0 parts by mass or more and 4.5 parts by mass or less.

Next, toner characteristics will be described.
In this embodiment, the total coverage of the toner particles by the external additive is preferably 55% or more and 120% or less, more preferably 60% or more and 110% or less, and particularly preferably 80% or more and 100% or less.
By setting the total coverage by the external additive in the above range, it is easy to act on the contact state between the toner and the carrier, and the developer according to the present embodiment easily satisfies the specific total energy range.

  Here, in order to set the total coverage of the toner particles by the external additive within the above range, for example, there is a method of controlling by the processing apparatus and conditions of the external additive. Specifically, when the external additive is processed on the toner particles, the processing time is appropriately adjusted.

In the present embodiment, the total coverage of the toner particles with the external additive is measured as follows.
Ultrasonic vibration (output 20 W, frequency 20 kHz) was applied to a dispersion in which 1 g of toner was dispersed in a Triton solution (polyoxyethylene (10) octylphenyl ether (Wako Pure Chemical Industries, Ltd., 0.2 mass% aqueous solution)). Acting for 30 minutes, the filtrate obtained by filtration is air-dried for 1 week to obtain an external additive removed from the toner particles.
Next, the toner particles and the obtained external additive are measured by X-ray photoelectron spectroscopy. Measurement by X-ray photoelectron spectroscopy uses an X-ray photoelectron spectrometer (JPS-9000MX, manufactured by JEOL Ltd.), measurement intensity 10.0 kV, emission current 20 mA, X-ray source MgKa condition, Ar gas 3 × 10 ^−2. It is carried out under conditions of Pa · acceleration voltage 400V · 6 to 7 mA.
According to the following formula, the total coverage of the toner particles by the external additive is determined from the sum of the element ratios.
Total coverage by external additive = (Si amount of toner particle / Si amount of external additive) × 100 (%) + (Ti amount of toner particle / Ti amount of external additive) × 100 (%) + (toner Al amount of particles / Al amount of external additive) × 100 (%)

In this embodiment, the amount of free oil in the toner refers to a value measured by the following method.
When the amount of free oil of the oil-treated inorganic particles themselves and the amount added to the toner are known, the calculated value by the following formula is used.
Toner free oil amount (parts by mass) = free oil amount of oil-treated inorganic particles themselves (%) × addition amount of oil-treated inorganic particles (parts by mass)
On the other hand, if the amount of free oil of the oil-treated inorganic particles themselves and the amount added to the toner are unknown, the amount of free oil of the external additive removed from the toner particles, the amount of external additive removed from the toner particles, and the external additive The amount of toner particles after removing the toner is measured, and the calculated value by the following formula is used.
Free oil amount (parts by mass) of toner = free oil amount (%) of external additive removed from toner particles × external additive amount (mass) removed from toner particle / toner particle amount after removal of external additive (mass)

Next, a toner manufacturing method will be described.
The toner is obtained by externally adding an external additive to the toner particles after producing the toner particles.
The toner particles are preferably produced by wet granulation. Examples of the wet granulation method include known melt suspension methods, emulsion aggregation / unification methods, and dissolution suspension methods.
Examples of a method of externally adding an external additive to the obtained toner particles include a method of mixing with a known mixer such as a V-type blender, a Henschel mixer, and a Redige mixer.

Next, the carrier will be described.
A known carrier can be used as the carrier .
Examples of the carrier having a small average weight per carrier particle include a carrier having a small specific gravity. Specifically, for example, 1) a magnetic powder-dispersed carrier in which magnetic powder is dispersed and blended in a matrix resin. 2) A resin-impregnated carrier obtained by impregnating a porous magnetic powder with a resin. In addition, a carrier having a smaller diameter than that of a conventional carrier is also mentioned, and the average weight per carrier particle becomes smaller as the diameter is reduced.
The magnetic powder-dispersed carrier and resin-impregnated carrier use as a core a particle in which a magnetic powder is dispersed and blended in a matrix resin, or a particle in which a porous magnetic powder is impregnated with a resin. It may be a carrier coated with. Thereby, it is easy to obtain a carrier having a smooth surface.

  Examples of the magnetic powder include magnetic metals such as iron oxide, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

Examples of the coating resin that coats the core material, the matrix resin that disperses and blends the magnetic powder, and the resin that impregnates the porous magnetic powder include, for example, polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, and polyvinyl chloride. , Polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer, straight silicone resin containing an organosiloxane bond or a modified product thereof, fluorine resin, polyester, polycarbonate, phenol resin And epoxy resins.
The coating resin for coating the core material, the resin for dispersing and blending the magnetic powder, and the resin for impregnating the porous magnetic powder may contain other additives such as a conductive material.

  When the core material is coated with the coating resin, the coating amount of the coating resin on the core material is, for example, 0.5% by mass or more (desirably 0.7% by mass or more and 6% by mass or less) with respect to the mass of the entire carrier. More desirably, the content is 1.0% by mass or more and 5.0% by mass or less.

The coating amount of the coating resin is determined as follows.
In the case of a solvent-soluble coating resin, a precise amount of carrier is dissolved in a soluble solvent (for example, toluene), the magnetic powder is held by a magnet, and the solution in which the coating resin is dissolved is washed away. By repeating this several times, the magnetic powder from which the coating resin has been removed remains. The coating amount is calculated by drying, measuring the mass of the magnetic powder, and dividing the difference by the carrier amount.
Specifically, 20.0 g of the carrier is measured, put into a beaker, 100 g of toluene is added, and the mixture is stirred with a stirring blade for 10 minutes. A magnet is applied to the bottom of the beaker, and toluene is allowed to flow so that the core material (magnetic powder) does not flow out. This is repeated 4 times, and the beaker after washing is dried. After drying, the amount of magnetic powder is measured, and the coating amount is calculated by the formula [(carrier amount−magnetic powder amount after washing) / carrier amount].
On the other hand, in the case of a solvent-insoluble coating resin, Rigaku's Thermo plus EVOII differential type differential thermobalance TG8120 is heated in a nitrogen atmosphere in the range of room temperature (25 ° C.) to 1000 ° C., and its mass is reduced. From this, the coating amount is calculated.

The volume average particle diameter of the carrier is preferably 10 μm or more and 100 μm or less, preferably 15 μm or more and 40 μm or less, more preferably 20 μm or more and 30 μm or less.
Here, the volume average particle size of each carrier is a value measured as the volume average particle size of carrier particles using a laser diffraction / scattering type particle size distribution measuring device (LS Particle Size Analyzer (manufactured by Coulter)). As an electrolytic solution, ISOTON-II (manufactured by Coulter Scientific Japan) is used.

As the particle size distribution characteristic of the carrier, the volume average particle size distribution index (GSDv) is preferably 1.25 or less, and desirably 1.20 or less.
By adjusting the particle size distribution characteristic, the total energy in the powder rheometer is easily controlled.

(Image forming devices, etc.)
As shown in FIG. 1, the image forming apparatus 101 according to the present embodiment includes, for example, an electrophotographic photosensitive member 10 (an example of an image holding member) that rotates clockwise as indicated by an arrow A, and an electrophotographic photosensitive member. A charging device 20 (an example of a charging unit) that is provided above the body 10 and is opposed to the electrophotographic photoreceptor 10 and charges the surface of the electrophotographic photoreceptor 10, and the electrophotographic photoreceptor 10 charged by the charging device 20. An exposure apparatus 30 (an example of an electrostatic charge image forming unit) that exposes the surface of the toner to form an electrostatic charge image, and a toner contained in a developer is attached to the electrostatic charge image formed by the exposure apparatus 30 to form an electrophotographic image. A developing device 40 (an example of a developing unit) that forms a toner image on the surface of the photoconductor 10; a transfer device 50 that transfers a toner image on the electrophotographic photoconductor 10 to a recording paper P (an example of a transfer target); The surface of the electrophotographic photosensitive member 10 And a cleaning device 70 (an example of a toner removing means) for cleaning.
The image forming apparatus 101 according to the present embodiment is provided with a fixing device 60 that fixes the toner image while conveying the recording paper P on which the toner image is formed.

  Details of main components in the image forming apparatus 101 according to the present embodiment will be described below.

-Electrophotographic photoreceptor-
Examples of the electrophotographic photoreceptor 10 include an inorganic photoreceptor in which a photosensitive layer provided on a conductive substrate is made of an inorganic material, and an organic photoreceptor in which a photosensitive layer is made of an organic material. As an organic photoreceptor, a charge generation layer that generates charge upon exposure and a charge transport layer that transports charge are stacked on a conductive substrate, or a charge is generated on a conductive substrate. And a photoconductor provided with a single-layer type photosensitive layer in which the same layer performs the function of transporting charges and the function of transporting charges. Examples of the inorganic photoreceptor include a photoreceptor in which a photosensitive layer made of amorphous silicon is provided on a conductive substrate.
The shape of the electrophotographic photoreceptor 10 is not limited to a cylindrical shape, and a known shape such as a sheet shape or a plate shape may be employed.

-Charging device-
Examples of the charging device 20 include a contact charger using a conductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, and the like.
Examples of the charging device 20 include a non-contact type roller charger and a known charger such as a scorotron charger using a corona discharge or a corotron charger.

-Exposure device-
Examples of the exposure apparatus 30 include optical system devices that expose the surface of the electrophotographic photoreceptor 10 with light such as semiconductor laser light, LED light, and liquid crystal shutter light imagewise. The wavelength of the light source is preferably within the spectral sensitivity region of the electrophotographic photoreceptor 10. As the wavelength of the semiconductor laser, for example, near infrared having an oscillation wavelength around 780 nm is preferable. However, the wavelength is not limited to this, and a laser having an oscillation wavelength of 600 nm or a laser having an oscillation wavelength of 400 nm to 450 nm may be used as a blue laser.
As the exposure device 30, for example, a surface-emitting laser light source of a multi-beam output type is also effective for color image formation.

-Developer-
Examples of the developing device 40 include a general developing device that develops a two-component developer in contact or non-contact. The developing device 40 is not particularly limited as long as it has a developing function, and is selected from known developing devices according to the purpose. For example, the developing device 40 includes a known developing device having a function of attaching a two-component developer to the electrophotographic photoreceptor 10 using a brush, a roller, or the like. The developing device 40 preferably uses a developing roller holding a developer on the surface.

-Transfer device-
As the transfer device 50, for example, a contact transfer charger using a belt, a roller, a film, a rubber blade or the like, or a known transfer charger such as a scorotron transfer charger using a corona discharge or a corotron transfer charger. Can be mentioned.

-Cleaning device-
The cleaning device 70 includes, for example, a casing 71, a cleaning blade 72, and a cleaning brush 73 disposed on the upstream side of the cleaning blade 72 in the rotation direction of the electrophotographic photosensitive member 10. Further, for example, a solid lubricant 74 is disposed in contact with the cleaning brush 73.

  Hereinafter, the operation of the image forming apparatus 101 according to the present embodiment will be described. First, the electrophotographic photoreceptor 10 rotates along the direction indicated by the arrow A, and at the same time, is negatively charged by the charging device 20.

  The electrophotographic photoreceptor 10 whose surface is negatively charged by the charging device 20 is exposed by the exposure device 30, and a latent image is formed on the surface.

  When the portion where the latent image is formed on the electrophotographic photosensitive member 10 approaches the developing device 40, toner is attached to the latent image by the developing device 40 (developing roll 41), and a toner image is formed.

  When the electrophotographic photosensitive member 10 on which the toner image is formed further rotates in the direction of arrow A, the toner image is transferred onto the recording paper P by the transfer device 50. As a result, a toner image is formed on the recording paper P.

  The toner image is fixed on the recording paper P on which the image is formed by the fixing device 60.

For example, as illustrated in FIG. 2, the image forming apparatus 101 according to the present embodiment includes an electrophotographic photosensitive member 10, a charging device 20, an exposure device 30, a developing device 40, and a cleaning device 70 in a housing 11. May be provided with a process cartridge 101 </ b> A in which are integrally stored. The process cartridge 101A integrally contains a plurality of members and is attached to and detached from the image forming apparatus 101.
The configuration of the process cartridge 101A is not limited to this. For example, the process cartridge 101A only needs to include at least the electrophotographic photoreceptor 10 and the developing device 40. In addition, for example, the charging device 20, the exposure device 30, the transfer device 50, and the cleaning At least one selected from the apparatus 70 may be provided.

  In addition, the image forming apparatus 101 according to the present embodiment is not limited to the above configuration, and is, for example, a cleaning device around the electrophotographic photosensitive member 10 and downstream of the transfer device 50 in the rotation direction of the electrophotographic photosensitive member 10. A first neutralization device may be provided on the upstream side of the rotation direction of the electrophotographic photosensitive member from 70 so that the polarity of the remaining toner is aligned and easy to remove with a cleaning brush. Alternatively, a configuration may be adopted in which a second static elimination device for neutralizing the surface of the electrophotographic photosensitive member 10 is provided on the downstream side in the rotation direction of the electrophotographic photosensitive member and on the upstream side in the rotational direction of the electrophotographic photosensitive member relative to the charging device 20. .

  In addition, the image forming apparatus 101 according to the present embodiment is not limited to the above configuration, and a known configuration, for example, a toner image formed on the electrophotographic photosensitive member 10 is transferred to the intermediate transfer member and then transferred to the recording paper P. An intermediate transfer type image forming apparatus or a tandem type image forming apparatus may be used.

Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail in detail, this embodiment is not limited to the following examples. Unless otherwise specified, all “parts” and “%” are based on mass. Examples 2 to 10 are reference examples.

[Preparation of various dispersions]
(Preparation of resin particle dispersion 1)
・ Styrene (manufactured by Wako Pure Chemical Industries, Ltd.): 320 parts ・ n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.): 80 parts ・ β-carboxyethyl acrylate (manufactured by Rhodia Nikka Co., Ltd.): 9 Parts, 1,10-decanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.): 1.5 parts. Dodecanethiol (manufactured by Wako Pure Chemical Industries, Ltd.): 2.7 parts In addition, a solution obtained by dissolving 4 parts of an anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) in 550 parts of ion-exchanged water is added, dispersed and emulsified in a flask, and further stirred and mixed for 10 minutes. 50 parts of ion-exchanged water in which 6 parts of ammonium sulfate was dissolved was added. Next, after sufficiently replacing the nitrogen in the flask, the solution in the flask is heated to 70 ° C. with stirring in an oil bath, and emulsion polymerization is continued for 5 hours, and an anionic resin having a solid content of 41%. A particle dispersion 1 was obtained.

  The resin particles in the resin particle dispersion 1 had a center particle size of 196 nm, a glass transition temperature of 51.5 ° C., and a weight average molecular weight Mw of 32400.

(Preparation of resin particle dispersion 2)
・ Styrene (manufactured by Wako Pure Chemical Industries, Ltd.): 280 parts ・ n-butyl acrylate (manufactured by Wako Pure Chemical Industries, Ltd.): 120 parts ・ β-carboxyethyl acrylate (manufactured by Rhodia Nikka Co., Ltd.): 9 Part A solution prepared by dissolving 1.5 parts of the anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) in 550 parts of ion-exchanged water is dispersed and emulsified in a flask and slowly stirred for 10 minutes. -While mixing, 50 parts of ion-exchanged water in which 0.4 part of ammonium persulfate was dissolved was added. Next, after performing nitrogen substitution in the flask, the solution in the flask was heated with an oil bath to 70 ° C. while stirring, and emulsion polymerization was continued for 5 hours to disperse the anionic resin particles having a solid content of 42%. Liquid 2 was obtained.

  The resin particles in the resin particle dispersion 2 had a center particle size of 150 nm, a glass transition temperature of 53.2 ° C., a weight average molecular weight Mw of 41,000, and a number average molecular weight Mn of 25,000.

(Preparation of Colorant Particle Dispersion 1)
・ C. I. Pigment Yellow 74: 30 parts, anionic surfactant (manufactured by NOF Corporation: Nurex R): 2 parts, ion-exchanged water: 220 parts The above components are mixed, and preliminarily 10 minutes with a homogenizer (IKA Ultra Turrax) After the dispersion, a dispersion process is performed for 15 minutes at a pressure of 245 Mpa using an optimizer (counter collision type wet pulverizer: manufactured by Sugino Machine), a colorant particle having a central particle diameter of 169 nm and a solid content of 22.0%. Dispersion 1 was obtained.

(Preparation of release agent particle dispersion 1)
Paraffin wax HNP9 (melting temperature 75 ° C .: Nippon Seiki Co., Ltd.): 45 parts Cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts Ion-exchanged water: 200 parts Above The ingredients were mixed, heated to 100 ° C., dispersed with IKA Ultra Tarrax T50, and then dispersed with a pressure discharge type gorin homogenizer. The release agent particles had a center particle size of 196 nm and a solid content of 22.0%. A release agent particle dispersion 1 was obtained.

[Production of toner particles]
(Production of toner particles (1))
-Resin particle dispersion 1: 107 parts-Resin particle dispersion 2: 35 parts-Colorant particle dispersion 1: 30 parts-Release agent particle dispersion 1: 91 parts A solution mixed and dispersed with Tarax T50 was obtained.
Next, 0.4 parts of polyaluminum chloride was added to this solution to produce core aggregated particles, and the dispersion operation was continued using an ultra turrax. Further, the solution in the flask was heated to 48 ° C. with stirring in an oil bath for heating and held at 48 ° C. for 50 minutes, and then 36 parts of the resin particle dispersion 1 was added thereto to produce core / shell aggregated particles. . Thereafter, a 0.5 mol / L sodium hydroxide aqueous solution was added to adjust the pH of the solution to 5.6, and then the stainless steel flask was sealed and heated to 97 ° C. while continuing stirring using a magnetic seal. After holding for 5 hours, it was cooled.

  In this way, toner particles (1) were obtained. Toner particles (1) had an average circularity of 0.980 and a volume average particle size of 3.9 μm.

[Preparation of external additives]
(Preparation of external additive (1))
Under a nitrogen atmosphere, 160 parts of ethanol, 11 parts of tetraethoxysilane, and 6 parts of water were placed in a reaction vessel, and 10 parts of 20% aqueous ammonia was added dropwise over 130 minutes while stirring at 100 rpm. After stirring at 30 ° C. for 3.1 hours, the solution was concentrated until the liquid volume became half. 400 parts of water was added thereto, and the product was precipitated by a centrifugal settling machine. After removing the supernatant by decantation, 160 parts of distilled water was added, pH was adjusted to 9 with a 1M aqueous sodium hydroxide solution, and then adjusted to pH 7 with a 0.3M HNO ₃ aqueous solution. The supernatant was removed by decantation and then freeze-dried with a freeze dryer for about 60 hours to obtain silica as a white powder. The average particle size was 0.08 μm. The obtained silica is added to 300 parts of toluene and 9 parts of dimethyl silicone oil KF-96-100cs (manufactured by Shin-Etsu Chemical Co., Ltd.), stirred for 30 minutes at room temperature, concentrated to dryness, and dried at 200 ° C. White powder was obtained by performing heat drying for a period of time. This white powder was used as an external additive (1).

(Preparation of external additive (2))
Silica was obtained as a white powder in the same manner as the external additive (1) except that ammonia water was added dropwise over 200 minutes. Further, an external additive (2) having an average particle diameter of 100 nm was obtained in the same manner as the external additive (1) except that KF-96-3000cs was used instead of dimethyl silicone oil KF-96-100cs. It was.

(Preparation of external additive (3))
Silica was obtained as a white powder in the same manner as the external additive (1) except that 5 parts of aqueous ammonia was added dropwise over 40 minutes. External additive (3) having an average particle diameter of 35 nm was obtained in the same manner as external additive (1) except that 10 parts of KF-96-30cs was used instead of dimethyl silicone oil KF-96-100cs. It was.

(Preparation of external additive (4))
An external additive (4) having an average particle diameter of 100 nm was obtained in the same manner as the external additive (2) except that 12 parts of dimethyl silicone oil was used.

(Preparation of external additive (5))
Silica was obtained as a white powder in the same manner as the external additive (3) except that ammonia water was added dropwise over 20 minutes. An external additive (5) having an average particle size of 25 nm was obtained in the same manner as the external additive (2) except that 8 parts of dimethyl silicone oil was used.

(Preparation of external additive (6))
An external additive (6) having an average particle size of 80 nm was obtained in the same manner as the external additive (1) except that 12 parts of dimethyl silicone oil was used.

[Production of toner]
According to Table 1, for 100 parts of toner particles (1), the type and number of external additive A (any one of the above external additives (1) to (6)) according to Table 1 and other external components External additive B was added as an additive by stirring for 20 minutes at 2500 rpm using a 20 L Henschel mixer. Then, coarse particles were removed using a sieve having an opening of 45 μm to prepare a toner. As external additive B, hydrophobic silica (RX200) manufactured by Nippon Aerosil Co., Ltd. was used.

[Creation of carrier]
(Carrier (1))
Ferrite particles (volume average particle size: 25 μm): 100 parts Toluene: 14 parts Styrene-methacrylate copolymer (component ratio: 90/10): 0.5 parts First, the above components except for ferrite particles are added for 10 minutes. Stir with a stirrer to prepare a dispersed coating solution. Next, the coating solution and ferrite particles are placed in a vacuum degassing kneader, stirred at 60 ° C. for 30 minutes, and then degassed by further reducing pressure while heating. Then, carrier (1) was produced by drying.

(Carrier (2))
Into a Henschel mixer, 500 parts of spherical magnetite particles having a particle size of 0.3 μm (volume average particle diameter) are added and stirred. Then, 2.0 parts of a titanate coupling agent is added, and the temperature is raised to 100 ° C. for 30 minutes. By mixing and stirring, 0.3 μm spherical magnetite particles (dispersion in a carrier) coated with a titanate coupling agent were obtained.
Next, 50 parts of phenol, 68 parts of 40% formalin, 500 parts of the above spherical magnetite particles subjected to lipophilic treatment, 14 parts of 30% ammonia water, and 70 parts of water are placed in a 1 L four-necked flask and mixed with stirring. did. Next, the temperature was raised to 82 ° C. over 60 minutes with stirring, and the reaction was continued for 90 minutes at the same temperature. Then, after cooling to 25 degreeC and adding 500 parts of water, the supernatant liquid was removed and the deposit was washed with water. This was dried at 160 ° C. under reduced pressure to obtain a core material.
The following components were stirred / dispersed with a stirrer for 60 minutes to prepare a coating layer forming raw material solution.
-Toluene: 85 parts-Styrene-methacrylate copolymer (component ratio: 90/10): 16 parts Put 8.5 parts of the coating layer forming raw material solution and 100 parts of the core material in a vacuum degassing kneader, After stirring at an apparatus temperature of 100 ° C. until the core temperature reached 85 ° C., the pressure was reduced to 95 kPa, deaeration was performed for 15 minutes, and drying was performed. Furthermore, carrier (2) was produced by passing through a mesh having an opening of 75 μm.

(Carrier (3))
Carrier (3) was obtained in the same manner as carrier (1) except that ferrite particles having a volume average particle diameter of 15 μm were used.

(Carrier (4))
Carrier (4) was obtained in the same manner as carrier (1) except that ferrite particles having a volume average particle size of 38 μm were used.

10 parts of a toner (combination of toner particles and external additives) according to Table 1 and 100 parts of a carrier according to Table 1 were stirred for 20 minutes at 40 rpm using a V-blender, and a sieve having a 177 μm mesh The developers (1) to (10) and comparative developers (1) to (8) were obtained by sieving.
These developers (1) to (10) were used in Examples (1) to (10), and comparative developers (1) to (8) were used in Comparative Examples (1) to (8).

[Evaluation]
(Characteristic evaluation)
-Total energy-
The total energy of the developer was measured by the method described above. The obtained results are shown in Table 2.

-Total coverage with external additives-
The total coverage of the toner particles by the external additive was measured by the method described above. The obtained results are shown in Table 2.

-Toner free oil amount-
The amount of free oil in the toner was measured by the method described above. The obtained results are shown in Table 2.

(Actual machine evaluation)
-Density unevenness-
The developer obtained in each example was filled in a “700DCP” developer developed by Fuji Xerox Co., Ltd., and allowed to stand at 10 ° C. and 10% RH for 1 week, and then an image with an image density (area coverage) of 50% was 200. Images were output continuously, the output image was visually confirmed, and the number of color points generated was visually evaluated.
The evaluation criteria are as follows.
◎: 0 out of 200 sheets with uneven shading ○: 1 out of 200 sheets with uneven shading ○ −: Out of 200 out of 2 sheets with uneven shading △: 200 The number of unevenness in the sheet is 5 or more and 9 or less. Δ−: The number of unevenness in the sheet is 10 or more and 15 or less in the 200 sheets. ×: The number of unevenness in the 200 sheets is in the range of 16 or more. Less than or equal to xx: More than 20 sheets with uneven shading out of 200 sheets are shown in Table 2.

-Developer observation-
After completion of the density unevenness evaluation, a “700 DCP” developer developed by Fuji Xerox Co., Ltd. was opened, and sieved through a 250 μm mesh of 10 g, and the developer aggregation state was visually evaluated.
The evaluation criteria are as follows.
◎: Developer aggregation is 0 ○: Developer aggregation is 1 ○-: Developer aggregation is 2 or more and 3 or less Δ: Developer aggregation is 4 or more and 6 or less Δ-: Developer aggregation is 7 or more and 10 or less XX: Developer aggregation is 11 or more and 20 or less XX: Developer aggregation is more than 20 (develop the developer) (Agglomeration of developer can be confirmed visually when opened)
The obtained results are shown in Table 2.

-Toner observation-
During the evaluation of the developer aggregation state, the toner aggregation state was evaluated visually.
The evaluation criteria are as follows.
A: There is 0 toner aggregation ○: There is 1 toner aggregation ○-: There are 2 or more and 4 or less toner aggregation Δ: There are 5 or more and 7 or less toner aggregation Δ-: There are 8 or more and 10 or less toner aggregates. X: There are 11 or more and 20 or less toner aggregates. Xx: There are more than 20 toner aggregates (the toner is visually observed when the developing unit is opened). Aggregation can be confirmed)
The obtained results are shown in Table 2.

From the results in Table 2, it can be seen that density unevenness is suppressed in this example as compared with the comparative example.
In addition, in Examples 1 to 3, the total energy is 130 mJ or more and 200 mJ or less when the aeration flow rate is 0 ml / min, and the total energy is 20 mJ or more and 50 mJ or less when the aeration flow rate is 10 ml / min. Compared to Examples 4 to 9 in which the total energy is 130 mJ or more and 200 mJ or less and the aeration flow rate is 10 ml / min, the total energy is 20 mJ or more and 50 mJ or less is not satisfied. I understand that.

DESCRIPTION OF SYMBOLS 10 Electrophotographic photoreceptor 11 Case 20 Charging device 30 Exposure device 40 Developing device 50 Transfer device 60 Fixing device 70 Cleaning device 71 Case 72 Cleaning blade 73 Cleaning brush 74 Lubricant 101 Image forming device 101A Process cartridge P Recording paper

Claims (5)

A toner containing toner particles and oil-treated inorganic particles as an external additive , and a carrier,
The amount of free oil of the toner is 0.008 mass% or more and 0.013 mass% or less,
The total coverage of the toner particles by the external additive is 80% or more and 100% or less,
The amount of free oil of the oil-treated inorganic particles is 0.2% by mass or more and 2.5% by mass or less,
Using a powder rheometer, the total energy measured under the conditions where the tip speed of the rotor blade is 100 mm / sec and the approach angle of the rotor blade is −4 ° is 130 mJ or more and 200 mJ or less when the aeration flow rate is 0 ml / min. Yes, and an electrostatic charge image developer that is 20 mJ or more and 50 mJ or less when the air flow rate is 10 ml / min. The electrostatic charge image developer according to claim 1, wherein the oil-treated inorganic particles are oil-treated silica particles . An image carrier,
Development means for containing the electrostatic charge image developer according to claim 1 or 2 and developing the electrostatic charge image formed on the image carrier as a toner image by the electrostatic charge image developer;
Comprising at least
A process cartridge that is detachable from the image forming apparatus. An image carrier,
Charging means for charging the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the charged image carrier;
Development means for containing the electrostatic charge image developer according to claim 1 or 2 and developing the electrostatic charge image formed on the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring the toner image to a transfer object;
An image forming apparatus comprising at least A charging step for charging the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the charged image carrier;
A developing step of developing the electrostatic image formed on the image carrier as a toner image by the electrostatic image developer according to claim 1 or 2;
A transfer step of transferring the toner image to a transfer target;
An image forming method having at least