JP5929360B2 - Electrostatic image developing toner, electrostatic image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Description

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

  Patent Document 1 includes oxide fine particles containing at least silicon element, the primary particle diameter R of the oxide fine particles is 30 nm to 300 nm, the dielectric constant is 1.4 to 3.5, and the circularity SF1 is 100. An external additive for an electrophotographic toner is proposed, which has a circularity SF2 of 100 to 125 and a circularity SF2 of 100 to 125.

  Patent Document 2 discloses an image carrier that carries a latent image, a charging device having a charging member that uniformly charges the surface of the image carrier, and an exposure device that writes an electrostatic latent image on the surface of the charged image carrier. In the image forming apparatus including a developing device that visualizes the electrostatic latent image formed on the surface of the image carrier with toner, the charging device charges the surface of the image carrier with a charging member having conductive fine particles interposed therebetween. The toner has a weight average particle diameter of 2 to 8 μm, a shape factor SF-1 of 100 to 130, and at least conductive fine particles and inorganic fine particles having a number average particle diameter of 60 to 300 nm are externally added. An image forming apparatus characterized by the above has been proposed.

  Patent Document 3 discloses a two-component developer having at least toner particles, a toner having an external additive, and a carrier, and the toner includes at least a binder resin, a colorant, and a wax component. The amount of coarse powder that does not pass through a sieve having an opening of 20 μm is 0.01 to 0.50% by mass, (average circularity of coarse powder that does not pass through a sieve having an opening of 20 μm) <(average circularity of the entire toner) A two-component developer characterized by the above has been proposed.

JP 2004-212789 A JP 2006-293295 A JP 2002-091053 A

  An object of the present invention is to provide a toner for developing an electrostatic charge image that maintains transferability even when images having a low image density (low area coverage) are continuously formed, and that suppresses toner scattering. To do.

The invention according to claim 1
Toner particles,
The average particle size is 100 nm or more and 200 nm or less, the average circularity is 0.5 or more and 0.85 or less, and the volume resistivity is 1.0 × 10 ¹⁰ Ωcm or more and 1.0 × 10 ¹⁴ Ωcm or less. External additives,
The toner for developing an electrostatic charge image.

The invention according to claim 2
An electrostatic charge image developer comprising the electrostatic charge image developing toner according to claim 1 .

The invention according to claim 3
Containing the electrostatic image developing toner according to claim 1 ;
The toner cartridge is detachable from the image forming apparatus.

The invention according to claim 4
Containing the electrostatic charge image developer according to claim 2 ;
Developing means for developing an electrostatic image formed on the surface of the image carrier with the electrostatic image developer to form a toner image;
It is a process cartridge that can be attached to and detached from the image forming apparatus.

The invention according to claim 5
An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the image carrier;
A developing unit that houses the electrostatic charge image developer according to claim 2 and that develops the electrostatic charge image with the electrostatic charge image developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing the toner image on the recording medium;
An image forming apparatus.

The invention according to claim 6
A charging step for charging the surface of the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the image carrier;
A developing step of developing the electrostatic charge image with the electrostatic charge image developer according to claim 2 to form a toner image;
A transfer step of transferring the toner image to a recording medium;
A fixing step of fixing the toner image on the recording medium;
Is an image forming method.

According to the first aspect of the present invention, the average particle size is 100 nm or more and 200 nm or less, the average circularity is 0.5 or more and 0.85 or less, and the volume resistivity is 1.0 × 10 ^10. Compared to the case of not having an external additive of Ωcm or more and 1.0 × 10 ¹⁴ Ωcm or less, the transferability is maintained even when images having a low image density are continuously formed, and toner scattering is suppressed. An electrostatic charge image developing toner is obtained.
According to the invention of claim 2 , the average particle diameter is 100 nm or more and 200 nm or less, the average circularity is 0.5 or more and 0.85 or less, and the volume resistivity is 1.0 × 10 ^10. Compared with the case where an electrostatic charge image developing toner having no external additive of Ωcm or more and 1.0 × 10 ¹⁴ Ωcm or less is applied, transferability is maintained even when images having a low image density are continuously formed. In addition, an electrostatic charge image developer that achieves suppression of toner scattering can be obtained.

According to the invention according to claims 3, 4, 5 and 6 , the average particle size is 100 nm or more and 200 nm or less, the average circularity is 0.5 or more and 0.85 or less, and the volume resistivity is Even when an image having a low image density is continuously formed as compared with a case where a toner for developing an electrostatic charge image having no external additive of 1.0 × 10 ¹⁰ Ωcm or more and 1.0 × 10 ¹⁴ Ωcm or less is applied. Provided are a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method capable of obtaining an image in which an image defect caused by a decrease in transferability and toner scattering is suppressed.

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 process cartridge which concerns on this embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

[Toner for electrostatic image development]
The toner for developing an electrostatic charge image according to the exemplary embodiment (hereinafter sometimes simply referred to as “toner”) has toner particles, an average particle size of 70 nm to 250 nm, and an average circularity of 0.5 to 0. And an external additive having a volume resistivity of 1.0 × 10 ¹⁴ Ωcm or less.

Here, as the conventional external additive, in order to prevent the external additive from being embedded in the toner particles due to a mechanical load, a spherical large-diameter external additive having a circularity close to 1.0 has been used. However, such an external additive tends to roll on the toner particles and tends to be unevenly distributed in the concave portions of the toner particles when the external additive and the toner particles are mixed or when the developer is stirred.
Therefore, the surface of the toner particles is exposed, and the non-electrostatic adhesion force of the toner to a member such as an image holding member is increased, so that the transferability is easily lowered.

On the other hand, instead of the external additives as described above, an external additive having an irregular shape and a large diameter having an average particle diameter of 70 nm or more and 250 nm or less and a circularity of 0.5 or more and 0.85 or less (hereinafter referred to as “an irregular shape”). In some cases, it is called “external additive”), so that the deformability is high, so that the number of contacts on the surface of the toner particles is increased, rolling on the surface of the toner particles is prevented, and uneven distribution in the concave portions is prevented. It is thought to be suppressed.
For this reason, even after use over time, the adhesion of the toner to the image carrier due to the exposure of the surface of the toner particles can be suppressed, so that it is considered that the transferability can be prevented from being lowered.
Further, since the contact point between the external additive and the toner particles is increased, the impact force applied to the toner is dispersed when the external additive and the toner particles are mixed or when the developer is stirred. Is thought to be difficult to bury.

However, as described above, the irregular external additive is not easily unevenly distributed in the concave portion, and is also present in the convex portion. Further, since it is difficult to be embedded in the toner particles with time, when a plurality of toners are laminated, the toner particles and the toner It is considered that voids formed from the irregular external additives sandwiched between the particles tend to be easily formed between the toners.
Therefore, in the case where toner such as a toner layer constituting the toner image (hereinafter sometimes referred to as a toner layer) is laminated, it is considered that aggregation of the toners is suppressed.
As a result of the suppression of toner aggregation, the toner in the toner layer before fixing is considered to weaken the cohesion between the toners. Depending on the charge amount of the toner, the electrostatic repulsion between the toners Therefore, it is considered that the toner tends to scatter.
In particular, when the external additive is 250 nm or less, the distance between the toners becomes small, so that the electrostatic repulsion force increases and the toner scatters remarkably.
In the case of a secondary color or more, it is considered that a large amount of toner tends to scatter particularly because toner layers of two or more colors are stacked to increase the amount of toner.

Therefore, in the toner according to the exemplary embodiment, the average particle size is 70 nm to 250 nm, the average circularity is 0.5 to 0.85, and the volume resistivity is 1.0 × 10 ¹⁴ Ωcm. It has the following external additives, that is, external additives that are deformed and adjusted to have a low volume resistivity.
It is considered that the electrostatic repulsion between the toners is controlled in such a manner that the charge amount of the toner is suppressed and weakened because the volume resistivity of the external additive is adjusted to be low.
As a result, it is considered that the cohesive force between the toners easily exceeds the electrostatic repulsion force between the toners, and the toner scattering is suppressed.

  In particular, when images having a low image density (for example, 3% or less) are continuously formed, the toner consumption decreases, and the frequency of toner replenishment and toner cartridge replacement also decreases. As a result of repeated stirring over a long period of time and a large mechanical load on the external additive, it is considered that the external additive is likely to be unevenly distributed in the toner particle recesses. Even if it is formed, if it is an irregular external additive, uneven distribution in the toner particle recesses is suppressed, and toner adhesion to the image carrier due to exposure of the surface of the toner particles is suppressed. It is considered that the decrease in sex is suppressed.

From the above, it is considered that the toner according to the present embodiment maintains the transferability even when images with low image density are continuously formed, and suppresses toner scattering.
Note that image density is defined by taking the optical microscope image of an image into a Luzex image analyzer through a video camera, calculating the projected area of the image, and dividing this by the area of the visual field of the video camera in%. Is.

  Hereinafter, the toner according to the exemplary embodiment will be described in detail.

[External additive]
First, the external additive used in this embodiment will be described.
The external additive has an average particle diameter of 70 nm to 250 nm, an average circularity of 0.5 to 0.85, and a volume resistivity of 1.0 × 10 ¹⁴ Ωcm or less. Apply.

(Average particle size)
The average particle size of the external additive is 70 nm or more and 250 nm or less, preferably 100 nm or more and 200 nm or less, and more preferably 120 nm or more and 180 nm or less.
When the average particle size is larger than 250 nm, the distance between the toners becomes large and the electrostatic repulsion force is weakened, so that it is considered that the toner is less likely to be scattered.
On the other hand, since the average particle diameter of the external additive is 250 nm or less, detachment from the toner particles over time is suppressed, and the amount of the external additive added to the toner particles is maintained. It is considered that the toner adheres to the image carrier due to the exposure of the toner. As a result, it is considered that the transferability deterioration due to the adhered toner is suppressed and the function as an external additive (spacer function) is secured.
In addition, since an external additive having an average particle diameter of 70 nm or more is difficult to be embedded in toner particles, it is considered that a function (spacer function) as an external additive is ensured.

  The average particle diameter of the external additive is determined by observing the surface of the toner particles, observing 100 external additives (particles), and using the image processing analysis software WinRof (Mitani Corporation) It was calculated by using and analyzing. The average particle diameter of the external additive means a 50% diameter (D50v) in the cumulative frequency of equivalent circle diameters obtained by image analysis of primary particles.

(Average circularity)
The average circularity of the external additive is from 0.5 to 0.85, preferably from 0.6 to 0.85, and more preferably from 0.65 to 0.8. When the average degree of circularity of the external additive is 0.85 or less, the ratio of the external additive having an irregular shape is increased, and the ratio of the spherical external additive is decreased. It is considered that the uneven distribution of the toner is suppressed and the adhesion of the toner to the image carrier or the like due to the exposure of the surface of the toner particles is suppressed.
As a result, it is considered that the transferability deterioration due to the adhered toner is suppressed and the function as an external additive (spacer function) is secured.
On the other hand, when the average circularity of the external additive is 0.5 or more, the external additive has a small aspect ratio, so that the external additive is not easily lost even when a mechanical load is applied. Further, the external additive has an average circularity of 0.5 or more, and is easy to manufacture.

The average circularity is measured by observing 100 external additives at 40000 times, and analyzing the image of the observed toner particle surface using image processing analysis software WinRof (Mitani Corporation).
After obtaining the equivalent circle diameter circumference and circumference from the analyzed image, the circularity of each external additive is obtained according to the following formula, and the average is obtained (similar to the calculation of the average particle diameter).
Formula (1) Circularity = circle equivalent diameter perimeter / perimeter = [2 × (Aπ) ^1/2 ] / PM

In the above formula, A represents the projected area of the external additive, and PM represents the perimeter of the external additive.
When the circularity is 1.0, it is a true sphere. The lower the numerical value, the more uneven the outer periphery, and the higher the degree of irregularity.

(Volume resistivity)
The volume resistivity of the external additive is 1.0 × 10 ¹⁴ Ωcm or less, desirably 1.0 × 10 ^13.5 Ωcm or less, and desirably 1.0 × 10 ¹³ Ωcm or less.
By setting the volume resistivity of the external additive to 1.0 × 10 ¹⁴ Ωcm or less, the charge amount of the toner having the external additive is reduced, so that the cohesive force between the toners is electrostatic repulsion between the toners. It is considered that toner scattering in the toner layer before fixing is suppressed.
Since toner scattering is suppressed as the charge amount of the toner is smaller, the volume resistivity of the external additive is considered to be better. However, from the viewpoint of manufacturing, it is 1.0 × 10 ¹⁰ Ωcm or more. It is good.

The volume resistivity (Ωcm) of the external additive externally added to the toner particles is measured as follows. The measurement environment is a temperature of 20 ° C. and a humidity of 50% RH.
First, the external additive is separated from the toner by the following method.
An ultrasonic wave in which 2 g of toner is sufficiently dispersed in 40 ml of a Triton solution having a concentration of 0.2% (polyoxyethylene octylphenyl ether having a polymerization degree of 10; manufactured by Wako Pure Chemical Industries) and an ultrasonic vibrator having an oscillation frequency of 20 kHz is immersed therein. The vibration device (ultrasonic homogenizer US300T, manufactured by Nippon Seiki Seisakusho Co., Ltd.) is operated at an output of 150 mA for 30 minutes to desorb and recover the external additive.
Next, an external additive to be measured is placed flat on the surface of a circular jig having a 20 cm ² electrode plate so as to have a thickness of about 1 mm to 3 mm to form an external additive layer. . The electrode plate of 20 cm ² is placed on this and the external additive layer is sandwiched. In order to eliminate gaps between the external additives, a load (4 kg) is applied on the electrode plate placed on the external additive layer, and then the thickness (cm) of the external additive layer is measured. Both electrodes above and below the external additive 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 6000 V / cm, and the current value (A) flowing at this time is read to calculate the volume electrical resistance (Ωcm) of the external additive. The formula for calculating the volume resistivity (Ωcm) of the external additive is as shown in the following formula (2).
Formula (2): R = E × 20 / (I−I ₀ ) / L

In the above formula (2), R is the volume resistivity (Ωcm) of the external additive, E is the applied voltage (V), I is the current value (A), I ₀ is the current value (A) at the applied voltage 0 V, L Represents the thickness (cm) of the external additive layer. A coefficient of 20 represents the area (cm ² ) of the electrode plate.

  Examples of the method for adjusting the volume resistivity of the external additive include adjusting the treatment amount of the hydrophobizing agent and adjusting the drying temperature during production.

(material)
As the material of the external additive, the effect of the toner according to the present embodiment is mechanically exhibited by the average particle size, the average circularity, and the standard deviation of the circularity. If it is an external additive which satisfy | fills average circularity and volume resistivity, material will not be specifically limited, A well-known material is applied. Below, the silica produced by the sol-gel method is demonstrated.

(Production method of external additives)
An example of a method for producing the external additive is a sol-gel method.
Hereinafter, the preparation method of the external additive by the sol-gel method will be referred to as “sol-gel silica production method”.

  The method for producing sol-gel silica includes a step of preparing an alkali catalyst solution containing an alkali catalyst at a concentration of 0.6 mol / L or more and 0.85 mol / L or less in a solvent containing alcohol (hereinafter referred to as “alkali catalyst solution preparation step”). And tetraalkoxysilane is supplied into the alkali catalyst solution, and 0.1 mol or more and 0.1 mol per mol of the total amount of tetraalkoxysilane supplied per minute. And a step of supplying an alkali catalyst at 4 mol or less (hereinafter sometimes referred to as “particle generation step”).

That is, in this production method, in the presence of the alcohol containing the alkali catalyst at the above concentration, the tetraalkoxysilane as the raw material and the alkali catalyst as the catalyst are separately supplied in the above relationship, while the tetraalkoxysilane is supplied. To produce silane particles.
In the present sol-gel silica production method, sol-gel silica having a low degree of circularity with little generation of coarse aggregates is obtained by the above method. Although this reason is not certain, it is thought to be due to the following reasons.

  First, an alkali catalyst solution containing an alkali catalyst in an alcohol-containing solvent is prepared, and when tetraalkoxysilane and an alkali catalyst are respectively supplied to this solution, the tetraalkoxysilane supplied in the alkali catalyst solution reacts. Thus, nuclear particles are generated. At this time, if the alkali catalyst concentration in the alkali catalyst solution is in the above range, it is considered that core particles having a low degree of circularity are generated while suppressing the formation of coarse aggregates such as secondary aggregates. This is because the alkali catalyst is coordinated to the surface of the generated core particle in addition to the catalytic action, and contributes to the shape and dispersion stability of the core particle. If the amount is within the above range, the alkali catalyst Does not cover the surface of the core particles evenly (that is, because the alkali catalyst is unevenly distributed and adheres to the surface of the core particles), while maintaining the dispersion stability of the core particles, the surface tension and chemical affinity of the core particles This is because it is considered that a partial deviation occurs in the nuclei and core particles with low circularity are generated.

  When the tetraalkoxysilane and the alkali catalyst are continuously supplied, the produced core particles grow by the reaction of the tetraalkoxysilane, and silica particles are obtained. Here, by supplying the tetraalkoxysilane and the alkali catalyst while maintaining the supply amount in the above relationship, the generation of coarse aggregates such as secondary aggregates is suppressed, and the nucleus having low circularity is provided. It is considered that the particles grow while maintaining the irregular shape, and as a result, sol-gel silica with low circularity is generated. This is because the supply amount of the tetraalkoxysilane and the alkali catalyst is in the above relationship, so that the partial distribution of the tension and chemical affinity on the surface of the core particle is maintained while maintaining the dispersion of the core particle. Therefore, it is considered that particle growth of the core particles occurs while maintaining the deformity.

  From the above, it is considered that the sol-gel silica production method can produce sol-gel silica having a low degree of circularity with less generation of coarse aggregates.

Here, the supply amount of tetraalkoxysilane is considered to be related to the particle size distribution and circularity of sol-gel silica. By making the supply amount of tetraalkoxysilane 0.002 mol / (mol · min) or more and 0.009 mol / (mol · min) or less, the contact probability between the tetraalkoxysilane and the core particles in the particle growth stage is lowered, It is believed that the reaction between the tetraalkoxysilane and the core particles can occur before the tetraalkoxysilane is supplied to the core particles without any bias. That is, it is considered that the reaction between the tetraalkoxysilane and the core particles is biased. Therefore, it is considered that the uneven distribution of the tetraalkoxysilane supply to the core particles is promoted, and the variation of the particle growth is brought about.
As a result, it is considered that sol-gel silica having an average circularity of 0.5 to 0.85 can be produced.
The average particle size of sol-gel silica is considered to depend on the total supply amount of tetraalkoxysilane.

Also, in this sol-gel silica production method, it is considered that sol-gel silica is produced by generating irregularly shaped core particles and growing the nucleus particles while maintaining this irregular shape. It is considered that an unusually shaped sol-gel silica having high properties can be obtained.
In other words, in this method for producing sol-gel silica, it is considered that the generated irregularly shaped core particles are grown while maintaining the irregular shape, and sol-gel silica is obtained. It is thought that it is obtained.

  Further, in the method for producing sol-gel silica, since the tetraalkoxysilane reaction is caused by supplying tetraalkoxysilane and an alkali catalyst to the alkali catalyst solution, respectively, the particles are generated. Compared to the case of producing irregular shaped silica particles by the sol-gel method, the total amount of alkali catalyst used is reduced, and as a result, the step of removing the alkali catalyst can be omitted. This is particularly advantageous when sol-gel silica is applied to products that require high purity.

Next, the alkali catalyst solution preparation step will be described.
In the alkali catalyst solution preparation step, a solvent containing alcohol is prepared, and an alkali catalyst is added thereto to prepare an alkali catalyst solution.

The solvent containing alcohol may be a solvent of alcohol alone or, if necessary, ketones such as water, acetone, methyl ethyl ketone, methyl isobutyl ketone, cellosolves such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve acetate, It may be a mixed solvent with other solvents such as ethers such as dioxane and tetrahydrofuran.
In the case of a mixed solvent, the amount of alcohol relative to the other solvent is preferably 80% by mass or more (desirably 90% by mass or more).
Examples of the alcohol include lower alcohols such as methanol and ethanol.

  On the other hand, the alkali catalyst is a catalyst for accelerating the reaction (hydrolysis reaction, condensation reaction) of tetraalkoxysilane, and examples thereof include basic catalysts such as ammonia, urea, monoamine, quaternary ammonium salts, Ammonia is particularly desirable.

The concentration (content) of the alkali catalyst is 0.6 mol / L or more and 0.85 mol / L, desirably 0.63 mol / L or more and 0.78 mol / L or less, and more desirably 0.66 mol / L or more. It is 0.75 mol / L or less.
If the concentration of the alkali catalyst is less than 0.6 mol / L, the dispersibility of the core particles in the growth process of the generated core particles becomes unstable, and coarse aggregates such as secondary aggregates are generated or gelled. The particle size distribution may deteriorate.
On the other hand, when the concentration of the alkali catalyst is higher than 0.85 mol / L, the stability of the generated core particles becomes excessive, spherical core particles are generated, and irregular core particles having an average circularity of 0.85 or less. It becomes difficult to obtain.
In addition, the density | concentration of an alkali catalyst is a density | concentration with respect to an alcohol catalyst solution (an alkali catalyst + solvent containing alcohol).
In addition, the density | concentration of an alkali catalyst is a density | concentration with respect to an alcohol catalyst solution (an alkali catalyst + solvent containing alcohol).

The particle generation process will be described.
In the particle generation step, tetraalkoxysilane and an alkali catalyst are respectively supplied in an alkali catalyst solution, and the tetraalkoxysilane is reacted (hydrolysis reaction, condensation reaction) in the alkali catalyst solution. This is a step of producing silica.
In this particle generation process, the core particles are generated by the reaction of tetraalkoxysilane at the initial stage of supply of tetraalkoxysilane (nuclear particle generation stage), and then the core particles are grown (nuclear particle growth stage), and then the sol-gel Silica is formed.

  Examples of the tetraalkoxysilane to be supplied into the alkali catalyst solution include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and the like. From the viewpoints of diameter, particle size distribution, etc., tetramethoxysilane and tetraethoxysilane are preferable.

The supply amount of tetraalkoxysilane is 0.002 mol / (mol · min) or more and 0.009 mol / (mol · min) or less with respect to the alcohol in the alkali catalyst solution.
This means that tetraalkoxysilane is supplied at a supply rate of 0.002 mol to 0.009 mol per minute with respect to 1 mol of alcohol used in the step of preparing the alkali catalyst solution.
By setting the supply amount of tetraalkoxysilane within the above range, sol-gel silica having an average particle diameter of 70 nm to 250 nm and an average circularity of 0.85 or less is easily generated.
The particle size of the sol-gel silica depends on the type of tetraalkoxysilane and the reaction conditions, but the total amount of tetraalkoxysilane used in the particle formation reaction is, for example, 0.756 mol with respect to 1 L of sol-gel silica dispersion. By setting it as the above, the primary particle of a particle size of 70 nm or more is obtained, and it is thought that a primary particle of a particle size of 250 nm or less is obtained by setting it as 2.735 mol or less with respect to 1L of sol gel silica dispersion liquids.

The supply amount of tetraalkoxysilane is
If the supply amount of tetraalkoxysilane is less than 0.002 mol / (mol · min), the contact probability between the dropped tetraalkoxysilane and the core particles is further lowered, but the total supply amount of tetraalkoxysilane is reduced. It takes a long time to finish dripping, and the production efficiency is poor.
On the other hand, when the supply amount of tetraalkoxysilane is 0.009 mol / (mol · min) or more, the supply amount with respect to the reaction becomes excessive, the reaction system is easily gelled, and the formation of core particles and particle growth are easily inhibited.

  The supply amount of tetraalkoxysilane is preferably 0.002 mol / (mol · min) or more and 0.0085 mol / (mol · min) or less, and more preferably 0.002 mol / (mol · min) or more and 0.008 mol / ( mol · min) or less.

  On the other hand, examples of the alkali catalyst supplied into the alkali catalyst solution include those exemplified above. The alkali catalyst to be supplied may be of the same type as the alkali catalyst previously contained in the alkali catalyst solution, or may be of a different type, but is preferably of the same type.

The supply amount of the alkali catalyst is 0.1 mol or more and 0.4 mol or less, preferably 0.14 mol or more and 0.35 mol or less, more preferably 0.1 mol or less with respect to 1 mol of the total supply amount of tetraalkoxysilane supplied per minute. Is 0.18 mol or more and 0.30 mol or less.
If the supply amount of the alkali catalyst is less than 0.1 mol, the dispersibility of the core particles in the growth process of the generated core particles becomes unstable, and coarse aggregates such as secondary aggregates are generated, The particle size distribution may deteriorate.
On the other hand, if the supply amount of the alkali catalyst is more than 0.4 mol, the stability of the generated core particles becomes excessive, and even if core particles with low circularity are generated in the core particle generation stage, In some cases, the core particles grow in a spherical shape, and sol-gel silica having a low circularity cannot be obtained.

  Here, in the particle generation step, tetraalkoxysilane and an alkali catalyst are supplied to the alkali catalyst solution, respectively, but this supply method may be a continuous supply method or intermittently. A supply method may be used.

  In the particle generation step, the temperature in the alkaline catalyst solution (temperature at the time of supply) is, for example, preferably 5 ° C. or more and 50 ° C. or less, and desirably 15 ° C. or more and 40 ° C. or less.

Through the above steps, sol-gel silica is obtained.
The sol-gel silica obtained in this state is obtained in the state of a dispersion, but is removed as a sol-gel silica powder after removing the solvent.

Solvent silica removal method for solvent removal is 1) Solvent removal by filtration, centrifugation, distillation, etc., then drying with vacuum dryer, shelf dryer, etc. 2) Fluidized bed dryer, spray dryer A known method such as a method of directly drying the slurry by, for example, may be mentioned. The drying temperature is not particularly limited, but is desirably 200 ° C. or lower. When the temperature is higher than 200 ° C., bonding between primary particles and generation of coarse particles are likely to occur due to condensation of silanol groups remaining on the sol-gel silica surface.
The dried sol-gel silica is preferably removed by crushing and sieving as necessary to remove coarse particles and aggregates. The crushing method is not particularly limited, and for example, the crushing method is performed by a dry pulverization apparatus such as a jet mill, a vibration mill, a ball mill, or a pin mill. The sieving method is performed by a known method such as a vibration sieve or a wind sieving machine.

The sol-gel silica obtained by the production method of the present sol-gel silica may be used by hydrophobizing the surface of the sol-gel silica with a hydrophobizing agent.
Examples of the hydrophobizing agent include known organosilicon compounds having an alkyl group (eg, methyl group, ethyl group, propyl group, butyl group). Specific examples include, for example, silazane compounds (eg, methyl trimethyl compound). Silane compounds such as methoxysilane, dimethyldimethoxysilane, trimethylchlorosilane, and trimethylmethoxysilane, hexamethyldisilazane, tetramethyldisilazane, and the like. The hydrophobizing agent may be used alone or in combination.
Among these hydrophobizing agents, organosilicon compounds having a trimethyl group such as trimethylmethoxysilane and hexamethyldisilazane are suitable.

  The amount of the hydrophobizing agent used is not particularly limited, but in order to obtain a hydrophobizing effect, for example, 1% by mass to 100% by mass, preferably 5% by mass to 80% by mass with respect to sol-gel silica. It is as follows.

  As a method for obtaining a hydrophobic sol-gel silica dispersion subjected to a hydrophobizing treatment with a hydrophobizing agent, for example, a necessary amount of a hydrophobizing agent is added to the sol-gel silica dispersion, and 30 to 80 ° C. with stirring. There is a method in which the sol-gel silica is subjected to a hydrophobization treatment to obtain a hydrophobic sol-gel silica dispersion by reacting in the above temperature range. When the reaction temperature is lower than 30 ° C., the hydrophobization reaction hardly proceeds, and when the reaction temperature exceeds 80 ° C., the gelation of the dispersion due to the self-condensation of the hydrophobizing agent or the aggregation of the sol-gel silica may easily occur. is there.

  On the other hand, as a method for obtaining a powdery hydrophobic sol-gel silica, a method for obtaining a hydrophobic sol-gel silica dispersion by obtaining a hydrophobic sol-gel silica dispersion by the above-described method, and a sol-gel silica dispersion Was dried to obtain a hydrophilic sol-gel silica powder, and then a hydrophobic treatment agent was added to carry out a hydrophobic treatment to obtain a hydrophobic sol-gel silica powder, and a hydrophobic sol-gel silica dispersion was obtained. Then, after drying to obtain a hydrophobic sol-gel silica powder, a method for obtaining a hydrophobic sol-gel silica powder by adding a hydrophobizing agent and subjecting it to a hydrophobizing treatment may be mentioned.

  Here, as a method of hydrophobizing the powdered sol-gel silica, the powdered hydrophilic sol-gel silica is stirred in a processing tank such as a Henschel mixer or a fluidized bed, and a hydrophobizing agent is added thereto, There is a method in which the hydrophobizing agent is gasified by heating the inside to react with silanol groups on the surface of the powdered sol-gel silica. Although processing temperature is not specifically limited, For example, 80 degreeC or more and 300 degrees C or less are good, Desirably 120 degreeC or more and 200 degrees C or less.

In order to adjust the sol-gel silica to the above volume resistivity range, for example, it is preferable to adjust the treatment amount of the hydrophobic treatment agent and the drying temperature.
Moreover, you may adjust by performing a drying process separately.

According to the production method of the sol-gel silica, the average particle size is 70 nm or more and 250 nm or less, the average circularity is 0.5 or more and 0.85 or less, and the volume resistivity is 1.0 × 10 ¹⁴ Ωcm or less, That is, an external additive having a small diameter, an irregular shape, and a low volume resistivity can be obtained.

  The external additive described above is preferably added in an amount of 0.5 parts by mass or more and 5.0 parts by mass or less, more preferably 0.7 parts by mass or more and 24.0 parts by mass with respect to 100 parts by mass of toner particles described later. It is not more than part by mass, and more preferably not less than 0.9 part by mass and not more than 3.5 parts by mass.

[Toner particles]
Next, toner particles will be described.
The toner particles include at least a binder resin, and may include a colorant, a release agent, and other internal additives as necessary.

(Binder resin)
The binder resin will be described.
Examples of the binder resin include an amorphous resin, and the amorphous resin and the crystalline resin may be used in combination.

  Examples of the binder resin include polyester resins and vinyl resins.

The polyester resin is 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 production method of the polyester resin is not particularly limited, and is produced by a general polyester polymerization method in which an acid component and an alcohol component are reacted. Examples thereof include direct polycondensation and transesterification methods. Produced separately.

  The polyester resin can be produced at a polymerization temperature of 180 ° C. or higher and 230 ° C. or lower. The reaction system is reduced in pressure as necessary, and the reaction is carried out while removing water and alcohol generated during the condensation. When the monomer is not dissolved or compatible with the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. When a monomer having poor compatibility exists in the copolymerization reaction, the monomer having poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polycondensed together with the main component.

When the binder resin has a melting temperature, the melting temperature is desirably 50 ° C. or higher and 100 ° C. or lower, and more desirably 60 ° C. or higher and 80 ° C. or lower. When the binder resin has a glass transition temperature, the glass transition temperature is preferably 35 ° C. or higher and 100 ° C. or lower, and more preferably 50 ° C. or higher and 80 ° C. or lower.
The melting temperature of the binder resin refers to a value obtained as a peak temperature of an endothermic peak obtained by differential scanning calorimetry (DSC). The binder resin may exhibit a plurality of endothermic peaks, but in the present embodiment, the maximum peak is regarded as the melting temperature.
The glass transition temperature of the binder resin was determined as the peak temperature of the endothermic peak obtained by differential scanning calorimetry (DSC).

  The polyester resin is preferably produced by subjecting the polyhydric alcohol and polyhydric carboxylic acid to a condensation reaction according to a conventional method. For example, the above polyhydric alcohol and polyvalent carboxylic acid, if necessary, a catalyst, and blended in a reaction vessel equipped with a thermometer, a stirrer, a flow-down condenser, and in the presence of an inert gas (such as nitrogen gas), Heat at 150 ° C. or higher and 250 ° C. or lower to continuously remove low-molecular compounds produced as a by-product from the reaction system, stop the reaction when a specific acid value is reached, cool the target reactant It is good to manufacture by acquiring.

Here, the binder resin preferably has a weight average molecular weight (Mw) of 5,000 or more and 1,000,000 or less, as measured by a gel permeation chromatography (GPC) method in which tetrahydrofuran (THF) is soluble. Is from 7,000 to 500,000, the number average molecular weight (Mn) is preferably from 2,000 to 10,000, the molecular weight distribution Mw / Mn is preferably from 1.5 to 100, and more preferably from 2 to 60. It is.
The weight average molecular weight and the number average molecular weight were measured with a THF solvent using a TSO soluble GPC / HLC-8120, a Tosoh column / TSKgel SuperHM-M (15 cm), and a monodisperse polystyrene standard sample. The molecular weight was calculated using the molecular weight calibration curve prepared by the above.

The softening temperature of the binder resin is preferably in the range of 80 ° C. or higher and 130 ° C. or lower. More desirably, it is in the range of 90 ° C. or higher and 120 ° C. or lower.
The softening temperature of the binder resin is a flow tester (manufactured by Shimadzu Corporation: CFT-500C), preheating: 80 ° C./300 sec, plunger pressure: 0.980665 MPa, die size: 1 mmφ × 1 mm, heating rate: 3.0 ° C. / Min refers to an intermediate temperature between the melting start temperature and the melting end temperature.

(Coloring agent)
The colorant is not particularly limited as long as it is a known colorant. For example, carbon black such as furnace black, channel black, acetylene black, and thermal black, inorganic pigments such as bengara, bitumen, and titanium oxide, fast yellow, disazo Azo pigments such as yellow, pyrazolone red, chelate red, brilliant carmine, para brown, phthalocyanine pigments such as copper phthalocyanine, metal-free phthalocyanine, flavantron yellow, dibromoanthrone orange, perylene red, quinacridone red, dioxazine violet Examples thereof include cyclic pigments.

  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 mass% or more and 30 mass% or less is desirable with respect to the total mass of binder resin.

(Release agent)
Next, the release agent will be described.
The release agent may be used in the range of 1% by mass or more and 10% by mass or less among the components constituting the toner particles, and more preferably in the range of 2% by mass or more and 8% by mass or less.

As the mold release agent, a substance having a main maximum peak measured according to ASTM D3418-8 in the range of 50 ° C. or higher and 140 ° C. or lower is preferable.
For the measurement of the main maximum peak, for example, DSC-7 manufactured by Perkin Elmer is used. The temperature correction of the detection part of this apparatus uses the melting temperature of indium and zinc, and the correction of heat uses the heat of fusion of indium. For the sample, an aluminum pan is used, an empty pan is set for control, and the measurement is performed at a heating rate of 10 ° C./min.

  The viscosity η1 at 160 ° C. of the release agent is preferably in the range of 20 cps to 600 cps.

  Specific examples of the release agent include, for example, low molecular weight polyolefins such as polyethylene, polypropylene, and polybutene; silicones having a softening point upon heating; oleic acid amide, erucic acid amide, ricinoleic acid amide, stearic acid amide, and the like Fatty acid amides such as: carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline Minerals such as wax, Fischer-Tropsch wax and the like; petroleum-based waxes, and modified products thereof.

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

(Characteristics of toner particles)
Next, the characteristics of the toner particles will be described.
The volume average particle diameter of the toner particles is preferably in the range of 3 μm to 9 μm, and more preferably in the range of 3 μm to 6 μm.

  The volume average particle diameter is measured using Multisizer II (manufactured by Beckman-Coulter) with an aperture diameter of 50 μm. In this case, the 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.

[Toner production method]
Next, a toner manufacturing method according to this embodiment will be described.
First, toner particles may be produced by a dry process (for example, a kneading and pulverization method), a wet process (for example, an aggregation coalescence method, a suspension polymerization method, a solution suspension granulation method, a solution suspension method, a solution emulsion aggregation method, or the like. ). There is no restriction | limiting in particular in these manufacturing methods, A well-known manufacturing method is employ | adopted.

  The toner according to the exemplary embodiment is manufactured, for example, by adding the external additive to the obtained toner particles and mixing them. Mixing is preferably performed by, for example, a V blender, a Henschel mixer, or a ladyge mixer. Further, if necessary, coarse toner particles may be removed using a vibration classifier, a wind classifier, or the like.

[Static charge image developer]
The electrostatic charge image developer contains at least the toner according to the exemplary embodiment.
The electrostatic image developer according to this embodiment may be a one-component developer including only the toner according to this embodiment, or may be a two-component developer mixed with the toner and a carrier.

  There is no restriction | limiting in particular as a carrier, A well-known carrier is mentioned. Examples of the carrier include a resin-coated carrier, a magnetic dispersion carrier, a resin dispersion carrier, and the like.

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

[Image forming apparatus and image forming method]
Next, an image forming apparatus and an image forming method according to this embodiment using the toner according to this embodiment will be described.
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic charge image forming unit that forms an electrostatic image on the surface of the image carrier, A developing means for storing the electrostatic charge image developer according to the embodiment and developing the electrostatic charge image formed on the surface of the image carrier with the developer to form a toner image; and the toner image as a recording medium. And a fixing means for fixing the toner image on the recording medium.

  The image forming apparatus according to the present embodiment includes a charging process for charging the surface of the image carrier, an electrostatic charge image forming process for forming an electrostatic image on the charged surface of the image carrier, and the present embodiment. With the electrostatic charge image developer, a development process for developing the electrostatic charge image formed on the surface of the image carrier to form a toner image, a transfer process for transferring the toner image to a recording medium, And an image forming method including a fixing step of fixing the toner image.

  The image formation in the image forming apparatus according to the present embodiment is performed, for example, as follows when an electrophotographic photosensitive member is used as the image carrier. First, the surface of the electrophotographic photosensitive member is charged by a corotron charger, a contact charger or the like and then exposed to form an electrostatic charge image. Next, the toner is adhered to the electrostatic charge image by bringing it into contact with or close to a developing roll having a developer layer formed on the surface, and a toner image is formed on the electrophotographic photosensitive member. The formed toner image is transferred onto the surface of a recording medium such as paper using a corotron charger or the like. Further, the toner image transferred to the surface of the recording medium is fixed by a fixing device, and an image is formed on the recording medium.

In the image forming apparatus according to the present embodiment, for example, the part including the developing unit may have a cartridge structure (toner cartridge, process cartridge, etc.) that is detachable from the image forming apparatus.
As the toner cartridge, for example, a toner cartridge that accommodates the electrostatic image developing toner according to the present embodiment and is detachable from the image forming apparatus is preferably used.
As the process cartridge, for example, the electrostatic charge developing developer according to the present embodiment is accommodated, and the electrostatic image formed on the surface of the electrostatic latent image holding member is developed with the electrostatic image developer to form a toner. A process cartridge that includes a developing unit that forms an image and is detachable from the image forming apparatus is preferably used.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. The main parts shown in the figure will be described, and the description of the other parts will be omitted.

  FIG. 1 is a schematic configuration diagram showing a four-tandem color image forming apparatus. The image forming apparatus shown in FIG. 1 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter sometimes simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed at a predetermined distance from each other. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the main body of the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a driving roller 22 and a support roller 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other from the left to the right in the drawing. The vehicle travels in the direction toward the unit 10K. A force is applied to the support roller 24 in a direction away from the drive roller 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the both. Further, an intermediate transfer member cleaning device 30 is provided on the side of the image carrier of the intermediate transfer belt 20 so as to face the driving roller 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K has yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. The toner including the four color toners can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first image that forms the yellow image disposed on the upstream side in the intermediate transfer belt traveling direction is formed. The unit 10Y will be described as a representative. Note that the second to fourth components are denoted by reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the same parts as the first unit 10Y. Description of the units 10M, 10C, and 10K will be omitted.

The first unit 10Y includes a photoreceptor 1Y that functions as an image holding member. Around the photosensitive member 1Y, a charging roller 2Y for charging the surface of the photosensitive member 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal to form an electrostatic charge image. An exposure device (electrostatic image forming means) 3 for forming, a developing device (developing means) 4Y for supplying the charged toner to the electrostatic image and developing the electrostatic image, and transferring the developed toner image onto the intermediate transfer belt 20 A primary transfer roller 5Y (primary transfer unit) that performs the transfer and a photoconductor cleaning device (cleaning unit) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer are sequentially arranged.
The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rollers 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of about −600V to −800V by the charging roller 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance equivalent to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y in this way is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic charge image on the photoreceptor 1Y is visualized (developed image) by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge image developer according to the present embodiment including at least yellow toner and a carrier is stored. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged charge on the photoreceptor 1Y, and a developer roll (developer holder). Is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roller 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image. Then, the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time is a (+) polarity opposite to the polarity (−) of the toner, and is controlled to about +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The

  The intermediate transfer belt 20 onto which the four color toner images have been transferred through the first to fourth units is arranged on the image transfer surface side of the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roller (secondary transfer means) 26 is connected to a secondary transfer portion. On the other hand, a recording medium (transfer object) P is fed at a predetermined timing into a gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed through a supply mechanism, and the secondary transfer bias is supported. Applied to the roller 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording medium P is applied to the toner image, so The toner image is transferred onto the recording medium P. Note that the secondary transfer bias at this time is determined according to the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording medium P is sent to the pressure contact portion (nip portion) of the pair of fixing rolls in the fixing device (roll-type fixing unit) 28, the toner image is heated, and the color-superposed toner image is melted to record the recording medium. Fixed onto P.

Examples of the transfer target to which the toner image is transferred include plain paper and OHP sheet used for electrophotographic copying machines, printers, and the like.
In order to further improve the smoothness of the image surface after fixing, it is also preferable that the surface of the transfer object is smooth, for example, coated paper in which the surface of plain paper is coated with resin, art paper for printing, etc. Are preferably used.

The recording medium P on which the color image has been fixed is unloaded to the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above is configured to transfer the toner image to the recording medium P via the intermediate transfer belt 20, but is not limited to this configuration, and the toner image is directly transferred from the photoconductor. It may be a structure transferred to a recording medium.

[Process cartridge, toner cartridge]
FIG. 2 is a schematic configuration diagram showing an embodiment of a preferred example of a process cartridge containing an electrostatic charge image developer according to this embodiment. The process cartridge 200 is provided with a charging roller 108, a photosensitive member cleaning device 113 having a developing device 111, an opening 118 for exposure, and an opening 117 for static elimination exposure, and a rail 116. Are combined and integrated. In FIG. 2, reference numeral 300 denotes a transfer target.
The process cartridge 200 is detachable from an image forming apparatus including a transfer device 112, a fixing device 115, and other components not shown.

  The process cartridge 200 shown in FIG. 2 includes a charging device 108, a developing device 111, a cleaning device 113, an opening 118 for exposure, and an opening 117 for static elimination exposure. Can be combined. In the process cartridge according to the present embodiment, in addition to the photosensitive member 107, the charging device 108, the developing device 111, the cleaning device (cleaning means) 113, the opening 118 for exposure, and the opening 117 for static elimination exposure. At least one selected from the group consisting of:

  Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the exemplary embodiment is a toner cartridge that stores toner for developing an electrostatic charge image and is detachable from the image forming apparatus.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which the toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are respectively the developing devices ( And a toner supply pipe (not shown). Further, when the amount of toner stored in the toner cartridge becomes low, the toner cartridge is replaced.

Hereinafter, the present embodiment will be specifically described by way of examples. However, the present embodiment is not limited to these examples. However, Examples 3 and 4 are reference examples. In the following description, “part” and “%” all mean “part by mass” and “mass%” unless otherwise specified.

(Preparation of toner particles 1)
-Preparation of resin particle dispersion 1-
Styrene (manufactured by Wako Pure Chemical Industries): 320 parts n-butyl acrylate (manufactured by Wako Pure Chemical Industries): 80 parts β-carboxyethyl acrylate (manufactured by Rhodia Nikka): 9 parts 1'10 decanediol diacrylate (manufactured by Shin-Nakamura Chemical): 1 part .5 parts dodecanethiol (manufactured by Wako Pure Chemical Industries): 2.7 parts

  A solution prepared by mixing 4 parts of the anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) in 550 parts of ion-exchanged water is added to the mixture of the above components and dispersed and emulsified in a flask. While mixing, 50 parts of ion-exchanged water in which 6 parts of ammonium persulfate was dissolved was added. Next, after performing nitrogen substitution in the flask, the solution in the flask was heated to 70 ° C. with stirring in an oil bath, and emulsion polymerization was continued as it was for 5 hours to disperse anionic resin particles having a solid content of 41%. Liquid 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): 280 parts n-butyl acrylate (manufactured by Wako Pure Chemical Industries): 120 parts β-carboxyethyl acrylate (manufactured by Rhodia Nikka): 9 parts

  A solution prepared by mixing 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 the resulting mixture is mixed and dissolved. 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 pigment: 30 parts Anionic surfactant (manufactured by NOF Corporation: Nurex R): 2 parts Ion-exchanged water: 220 parts

  After mixing the above components and pre-dispersing for 10 minutes with a homogenizer (IKA Ultra Tarrax), dispersion processing is performed for 15 minutes at a pressure of 245 Mpa using an optimizer (counter-impact type wet pulverizer: Sugino Machine) to produce colorant particles A colorant particle dispersion 1 having a center particle size of 169 nm and a solid content of 22.0% was obtained.

-Preparation of release agent particle dispersion 1-
Paraffin wax HNP9 (melting temperature 75 ° C .: manufactured by Nippon Seiki): 45 parts Cationic surfactant Neogen RK (Daiichi Kogyo Seiyaku): 5 parts Ion-exchanged water: 200 parts

  The above components were mixed, heated to 100 ° C., dispersed with Ultra Turrax T50 (manufactured by IKA), then dispersed with a pressure discharge type gorin homogenizer, the center particle size of the release agent particles was 196 nm, and the solid content was 22 0.0% release agent particle dispersion 1 was obtained.

Resin particle dispersion 1: 106 parts Resin particle dispersion 2: 36 parts Colorant particle dispersion 1:30 parts Release agent particle dispersion 1: 91 parts

A solution was obtained in which the above components were mixed and dispersed in a round stainless steel flask using Ultra Turrax T50 (manufactured by IKA).
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 49 ° C. with stirring in an oil bath for heating and held at 49 ° C. for 60 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 96 ° C. while continuing stirring using a magnetic seal. After maintaining the time, the mixture was cooled to obtain yellow toner particles.

  Next, the toner particles dispersed in the solution were filtered, washed with ion exchange water, and then subjected to solid-liquid separation by Nutsche suction filtration. This was further redispersed in 3 L of ion exchanged water at 40 ° C., and stirred and washed at 300 rpm for 15 minutes. This was repeated five more times, and when the filtrate had a pH of 7.01, an electrical conductivity of 9.8 μS / cm, and a surface tension of 71.1 Nm, solid-liquid separation was performed using a No5A filter paper by Nutsche suction filtration. The obtained solid was vacuum-dried for 12 hours to obtain toner particles having a volume average particle size of 6.4 μm.

(Preparation of external additive 1)
-Alkali catalyst solution preparation step [Preparation of alkali catalyst solution (1)]-
300 parts of methanol and 50.3 parts of 10% ammonia water are placed in a 3 L glass reaction vessel having a metal stirring bar, a dropping nozzle (Teflon (registered trademark) micro tube pump), and a thermometer, and stirred. By mixing, an alkali catalyst solution (1) was obtained. The amount of ammonia catalyst in the alkali catalyst solution (1) at this time: NH ₃ amount (NH ₃ [mol] / (ammonia water + methanol) [L]) was 0.69 mol / L.

-Particle generation step [Preparation of sol-gel silica dispersion (1)]-
Next, the temperature of the alkali catalyst solution (1) was adjusted to 25 ° C., and the alkali catalyst solution (1) was replaced with nitrogen. Thereafter, while stirring the alkali catalyst solution (1), 450 parts of tetramethoxysilane (TMOS) and 270 parts of ammonia water having a catalyst (NH ₃ ) concentration of 4.44% were simultaneously added dropwise at the following supply amount. A sol-gel silica dispersion (sol-gel silica dispersion (1)) was obtained.

Here, the supply amount of tetramethoxysilane (TMOS) was 6.61 g / min, that is, 0.0046 mol / (mol · min) with respect to the total number of moles of methanol in the alkali catalyst solution (1).
The supply amount of 4.44% ammonia water was 3.97 g / min with respect to the total supply amount of tetraalkoxysilane supplied per minute. This corresponds to 0.239 mol / min with respect to 1 mol of the total amount of tetraalkoxysilane supplied per minute.

-Hydrophobization of sol-gel silica-
Hydrophobic treatment was performed by adding 26 parts of trimethylsilane to 200 parts of sol-gel silica dispersion (1) (solid content: 16.6%). Then, using the hot plate, it heated at 120 degreeC and made it dry, and produced | generated the irregular-shaped hydrophobic sol-gel silica (1).
An externally shaped hydrophobic sol-gel silica (1) having an adjusted volume resistivity was used as the external additive 1.

(Preparation of external additives 2-11)
In the alkaline catalyst solution preparation step, an alkaline catalyst solution was prepared in the same manner as in the preparation of the external additive 1 except that the amount of methanol and 10% ammonia water were changed to the amounts shown in Table 1. The amount of NH ₃ is shown in the column of 10% aqueous ammonia NH ₃ in Table 1.

Next, in the preparation of the sol-gel silica dispersion, the above-mentioned alkali catalyst solution is used, the amount of tetramethoxysilane (TMOS) added to the alkali catalyst solution, the supply amount, and the ammonia water catalyst (NH ₃ ) added to the alkali catalyst solution. A sol-gel silica dispersion was prepared in the same manner as the external additive 1 except that the concentration, amount and supply amount were changed to the values shown in Table 1.
Then, using the obtained sol-gel silica dispersion, sol-gel silica was produced in the same manner as external additive 1, and after hydrophobization treatment, the formed irregular-shaped hydrophobic sol-gel silica (2) to (11) ) Volume resistivity was adjusted.
Externally shaped hydrophobic sol-gel silicas (2) to (11) after volume resistivity adjustment were used as external additives 2 to 11, respectively.

In addition, about the tetramethoxysilane added to an alkali catalyst solution, it changes into the value shown in the mass part column of the total addition amount TMOS of Table 1, and the supply amount of tetramethoxysilane is the supply amount (g / min) TMOS of Table 1. Changed to the value shown in the column.
The concentration of ammonia water catalyst (NH ₃ ) added to the alkaline catalyst solution was changed to the total addition amount shown in Table 1 and the value shown in the NH ₃ concentration column of ammonia water. The amount added was changed to the value shown in the mass part column of ammonia water, and the supply amount of ammonia water was changed to the value shown in the supply amount (g / min) ammonia water column of Table 1.

Here, the supply amount of TMOS was described in the supply amount (relative amount) TMOS amount in Table 1 with respect to the total number of moles of methanol in the alkali catalyst solution. In addition, the supply amount of ammonia water was described in the supply amount (relative amount) NH ₃ amount in Table 1 with respect to 1 mol of the total supply amount of tetramethoxysilane supplied per minute.

[Example 1]
<Preparation of Toner 1>
Using a Henschel mixer, 2.0 parts of external additive 1 was added to 100 parts of toner particles 1 to prepare toner 1.

When the obtained toner 1 was subjected to image analysis by the above-described method, the external additive (sol-gel silica) had an average particle diameter of 180 nm and an average circularity of 0.77.
Further, when the volume resistivity of the external additive 1 of the obtained toner 1 was measured by the above-described method, it was 1.0 × 10 ^11.8 Ωcm.

<Preparation of Developer 1>
Developer 1 was prepared by stirring 4 parts of the toner 1 and 96 parts of the following carrier: 96 parts using a V-blender at 40 rpm for 20 minutes and sieving with a sieve having an opening of 250 μm.

(Preparation of carrier 1)
Ferrite particles (average particle size: 50 μm): 100 parts Toluene: 14 parts Styrene-methyl methacrylate copolymer (component ratio: 90/10): 2 parts Carbon black (R330: manufactured by Cabot Corporation): 0.2 parts

  First, the above components other than ferrite particles are stirred with a stirrer for 10 minutes to prepare a dispersed coating solution, and then the coating solution and ferrite particles are put into a vacuum degassing kneader and stirred at 60 ° C. for 30 minutes. Further, the carrier 1 was produced by depressurizing and deaerating while heating and drying.

<Evaluation>
The obtained developer 1 was evaluated as follows. The results are shown in Table 2.

(Evaluation of external additives)
The average particle diameter, average circularity, and volume resistivity of the external additive of the obtained toner were measured and evaluated by the methods described above.

(Evaluation of transferability)
Developer 1 was mounted on an image forming apparatus DocuCenter Color 400 (manufactured by Fuji Xerox Co., Ltd.), and 10,000 prints with an image density of 1% were continued.
At this time, the difference in image density between the first sheet and the 10,000th sheet was measured by X-Rite 404 (manufactured by X-Rite Co., Ltd.) at five locations to evaluate transferability.
The evaluation criteria are as follows.
◎: Density difference less than 0.15 ○: 0.15 or more and less than 0.2 Δ: 0.2 or more and less than 0.25 ×: 0.25 or more The level of concern above.

(Evaluation of toner scattering)
The developer 1 is mounted on the image forming apparatus DocuCenter Color 400 (manufactured by Fuji Xerox Co., Ltd.) in a high temperature and high humidity environment (30 ° C., 85% RH) and a low temperature and low humidity environment (10 ° C., 10% RH). Ten fine line images for image quality evaluation were printed, and scattering of the peripheral part of the obtained image was evaluated. A loupe was used for observation.
The evaluation criteria are as follows.
A: Less than 2 toner splatters. Or not.
○: Minor scattering of toner is 3 to 5 sheets.
Δ: Minor scattering of toner is 6 sheets or more, or slightly conspicuous scattering is 2 sheets or less.
X: Slightly conspicuous scattering is 3 or more. Or there are lines that cannot be confirmed.

[Examples 2-6, Comparative Examples 1-5]
A toner and a developer were prepared in the same manner as in Example 1 except that the external additive 1 in Example 1 was replaced with the external additive shown in Table 2 below, and these were evaluated in the same manner as in Example 1. . The results are shown in Table 2.

  From the results of Table 2, in this embodiment, transferability is maintained and occurrence of toner scattering is suppressed as compared with the comparative example.

1Y, 1M, 1C, 1K, 107 photoconductor (image carrier)
2Y, 2M, 2C, 2K, 108 Charging roller 3Y, 3M, 3C, 3K Laser beam 3 Exposure device 4Y, 4M, 4C, 4K, 111 Developing device 5Y, 5M, 5C, 5K Primary transfer roller 6Y, 6M, 6C , 6K, 113 Photoconductor (image carrier) cleaning devices 8Y, 8M, 8C, 8K Toner cartridges 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer rollers 28, 115 Fixing device 30 Intermediate transfer member cleaning device 112 Transfer device 113 Photoconductor cleaning device 116 Mounting rail 117 Opening portion 118 for static elimination exposure Opening portion 200 for exposure Process cartridge P, 300 Recording medium

Claims (6)

Toner particles,
The average particle size is 100 nm or more and 200 nm or less, the average circularity is 0.5 or more and 0.85 or less, and the volume resistivity is 1.0 × 10 ¹⁰ Ωcm or more and 1.0 × 10 ¹⁴ Ωcm or less. External additives,
A toner for developing an electrostatic charge image. An electrostatic image developer comprising the electrostatic image developing toner according to claim 1 . Containing the electrostatic image developing toner according to claim 1 ;
A toner cartridge to be attached to and detached from the image forming apparatus. Containing the electrostatic charge image developer according to claim 2 ;
Developing means for developing an electrostatic image formed on the surface of the image carrier with the electrostatic image developer to form a toner image;
A process cartridge attached to and detached from the image forming apparatus. An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the image carrier;
A developing unit that houses the electrostatic charge image developer according to claim 2 and that develops the electrostatic charge image with the electrostatic charge image developer to form a toner image;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing the toner image on the recording medium;
An image forming apparatus comprising: A charging step for charging the surface of the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the image carrier;
A developing step of developing the electrostatic charge image with the electrostatic charge image developer according to claim 2 to form a toner image;
A transfer step of transferring the toner image to a recording medium;
A fixing step of fixing the toner image on the recording medium;
An image forming method comprising:

Images