JP2013195847A - Toner for electrostatic charge image development, electrostatic charge image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development capable of providing images in which a variation in density is further suppressed even after successive formation of images having low image density and high image density under a high-temperature and high-humidity environment.SOLUTION: A toner for electrostatic charge image development contains toner particles, and silica particles having the volume average particle diameter of 70 nm or more and 400 nm or less and the average circularity of 0.5 or more and 0.9 or less. The isolation rate of the silica particles relative to the toner particles is 5% or more and 30% or less.

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.

In electrophotography, generally, a latent image is formed electrically by various means on the surface of a photosensitive member (electrostatic latent image holding member) using a photoconductive substance, and the formed latent image is converted into a latent image. Then, after developing with a developer containing toner to form a developed image, this developed image is transferred to the surface of a transfer medium such as paper via an intermediate transfer body as necessary, and heated, pressurized, An image is formed through a plurality of steps of fixing by heating and pressing.
As the toner used for forming the image, a toner containing toner particles containing a binder resin or a colorant and an external additive externally added to the toner particles is often used.

For example, Patent Document 1 proposes a toner including an external additive containing titania having a liberation rate of 5 to 22% with respect to the toner base and a number average particle diameter of 80 to 500 nm.
Patent Document 2 proposes a toner containing an external additive composed of inorganic fine particles having a volume average particle diameter of 50 to 500 nm and a shape factor SF-1 of 100 to 120.
Further, Patent Document 3 proposes a toner containing an external additive having a roundness of 1.00 to 1.30 and an average primary particle diameter of 0.05 to 0.45 μm.

JP 2006-235588 A JP 2005-266557 A JP 2007-199579 A

  An object of the present invention is to provide a toner for developing an electrostatic image capable of obtaining an image in which density fluctuation is suppressed even when image formation with a low image density and a high image density is continuously performed in a high temperature and high humidity environment. It is to be.

The above problem is solved by the following means. That is,
The invention according to claim 1
Toner particles, and silica particles having a volume average particle size of 70 nm to 400 nm and an average circularity of 0.5 to 0.9, and the liberation rate of the silica particles with respect to the toner particles is 5% to 30%. % Of the electrostatic charge image developing toner.

The invention according to claim 2
2. The electrostatic image developing toner according to claim 1, wherein the toner particles have a volume average particle diameter of 2 μm to 6 μm.

The invention according to claim 3
3. The electrostatic image developing toner according to claim 1, wherein a coverage of the silica particles with respect to the toner particles is 20% or more and 80% or less. 4.

The invention according to claim 4
An electrostatic charge image developing developer comprising the electrostatic charge image developing toner according to claim 1.

The invention according to claim 5
An electrostatic charge image developing toner according to any one of claims 1 to 3 is accommodated,
The toner cartridge is detachable from the image forming apparatus.

The invention according to claim 6
The developer for electrostatic charge development according to claim 4 is accommodated, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed with the developer for electrostatic charge development to form a toner image. Development means,
The process cartridge is detachable from the image forming apparatus.

The invention according to claim 7 provides:
An electrostatic latent image carrier;
Charging means for charging the surface of the electrostatic latent image holding member;
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrostatic latent image holding member;
5. The developer for electrostatic charge development according to claim 4 is accommodated, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed with the developer for electrostatic charge development to form a toner image. Developing means to form;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing a toner image on the recording medium;
Cleaning means for cleaning the surface in contact with the surface of the electrostatic latent image carrier;
An image forming apparatus.

The invention according to claim 8 provides:
A charging step for charging the surface of the electrostatic latent image holding member;
An electrostatic latent image forming step of forming an electrostatic charge image on the surface of the charged electrostatic latent image holding member;
A developing step of developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member to form a toner image by the electrostatic charge developing developer according to claim 4;
A transfer step of transferring the toner image to a recording medium;
A fixing step of fixing a toner image on the recording medium;
A cleaning step of cleaning the surface of the electrostatic latent image carrier;
An image forming method comprising:

According to the invention of claim 1, the toner particles and silica particles having a volume average particle diameter of 70 nm to 400 nm and an average circularity of 0.5 to 0.9, Compared to the case where the liberation rate of the silica particles is not 5% or more and 30% or less, an image in which density fluctuation is suppressed even when image formation with a low image density and a high image density is continuously performed in a high temperature and high humidity environment. An electrostatic charge image developing toner can be obtained.
According to the second aspect of the present invention, compared with the case where the volume average particle diameter of the toner particles is not 2 μm or more and 6 μm or less, image formation with a low image density and a high image density is continuously performed in a high temperature and high humidity environment. Even in this case, a toner for developing an electrostatic image capable of obtaining an image in which density fluctuation is further suppressed can be obtained.
According to the invention of claim 3, compared with a case where the coverage of the silica particles to the toner particles is not 20% or more and 80% or less, image formation with a low image density and a high image density in a high temperature and high humidity environment. The toner for developing an electrostatic image capable of obtaining an image in which the density fluctuation is further suppressed can be obtained even if the process is continuously performed.

  According to inventions according to claims 4, 5, 6, 7, and 8, toner particles, silica particles having a volume average particle diameter of 70 nm to 400 nm, and an average circularity of 0.5 to 0.9, And the image forming of the low image density and the high image density can be continuously performed in a high temperature and high humidity environment as compared with the case where the liberation ratio of the silica particles to the toner particles is not 5% or more and 30% or less. In addition, it is possible to provide a developer for developing an electrostatic charge image, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method capable of obtaining an image in which density fluctuation 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 electrostatic image developing toner according to the present embodiment (hereinafter simply referred to as “toner”) includes (A) toner particles and (B) silica particles as an external additive. The silica particles (B) have a volume average particle size of 70 nm or more and 400 nm or less, an average circularity of 0.5 or more and 0.9 or less, and further, the silica particles (B) are released from the toner particles (A). The rate is 5% or more and 30% or less.

With the toner according to the present embodiment, an image in which density variation is suppressed can be obtained by the above configuration even when a low density image and a high density image are continuously formed in a high temperature and high humidity environment. .
The reason for this is not clear, but is thought to be due to the following reasons.

First, for the purpose of obtaining an effect as a spacer, a toner using an external additive having a deformed shape and a large diameter is known.
However, irregular and large external additives are easy to be separated from the toner particles, and when high-density images are continuously printed with frequent toner replacement, the carrier is contaminated. May fall.
In addition, when the low density image is continuously printed, the amount of the external additive in the developer is reduced because the external additive released from the toner particles is used for development, and as a result, the toner is charged. May rise.
As described above, in a toner using a deformed and large external additive, the charge varies depending on the image density, and the density of the image obtained by the toner also varies.

In the present embodiment, the above-mentioned problem can be solved by setting the liberation rate from the toner particles within a specific range while securing the function of the external additive as a spacer.
Therefore, it is considered that the toner according to the exemplary embodiment can obtain an image in which density fluctuation is suppressed even when a low density image and a high density image are continuously formed in a high temperature and high humidity environment. It is done.
In addition, in particular, the toner according to the present exemplary embodiment does not impair the toner transfer performance by defining the lower limit of the liberation rate of the external additive, and thus suppresses image defects in addition to the above effects. It is considered possible.

  Hereinafter, the toner particles (A) and the silica particles (B) constituting the toner according to the exemplary embodiment will be described in detail.

[Toner particles (A)]
The toner particles (A) include at least a binder resin and, if necessary, include a colorant, a release agent, and other internal additives.
Hereinafter, the material constituting the toner particles (A) will be described.

(Binder resin)
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, even 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 dicarboxylic acid component and a diol component 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 preferable 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. preferable.
The weight average molecular weight was measured with a THF solvent using a Toso GPC / HLC-8120, Tosoh column TSKgel SuperHM-M (15 cm), and a molecular weight calibration prepared with a monodisperse polystyrene standard sample. The molecular weight is calculated using the curve.

The glass transition temperature of the binder resin is desirably in the range of 40 ° C. or higher and 80 ° C. or lower. When the glass transition temperature is in the above range, the minimum fixing temperature is easily maintained.
The glass transition temperature is determined as the peak temperature of the endothermic peak obtained by differential scanning calorimetry (DSC).

(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)
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 melting point of the release agent is preferably 50 ° C. or higher, and more preferably 60 ° C. or higher, from the viewpoint of storage stability. Further, from the viewpoint of offset resistance, the temperature is desirably 110 ° C. or less, and more desirably 100 ° C. or less.

  The content of the release agent is preferably 1% by mass to 15% by mass, more preferably 2% by mass to 12% by mass, and still more preferably 3% by mass to 10% by mass.

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

[Characteristics of Toner Particle (A)]
(Shape factor)
The toner particle (A) has a shape factor SF1 of 125 to 140 (preferably 125 to 135, more preferably 130 to 135), and a shape factor SF2 of 105 to 130 (preferably 110 to 125, More desirably, it is 115 to 120.

The toner particle shape factor SF1 is obtained by the following equation.
Formula: Shape factor SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML represents the absolute maximum length of the toner particles, and A represents the projected area of the toner particles.
The shape factor SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and can be calculated as follows, for example. That is, the optical microscopic image of the toner particles dispersed on the surface of the slide glass is taken into a Luzex image analyzer through a video camera, the maximum length and the projected area of 100 toner particles are obtained, calculated by the above formula, and the average value is calculated. It is obtained by seeking.

The shape factor SF2 of the toner particles is obtained as follows.
An image is taken by observing toner particles using a scanning electron microscope (for example, manufactured by Hitachi, Ltd .: S-4100, etc.), and this image is taken into an image analyzer (for example, LUZEXIII, manufactured by Nireco). For the toner particles, SF2 is calculated based on the following formula, and the average value is obtained as the shape factor SF2. In the electron microscope, the magnification was adjusted so that 3 or more and 20 or less external additives could be seen in one field of view, and the observation of a plurality of fields of view was combined to calculate SF2 based on the following formula.
Formula: Shape factor SF2 = “PM ² / (4 · A · π)” × 100
Here, in the formula, PM indicates the peripheral length of the toner particles. A represents the projected area of the toner particles. π represents a circumference ratio.

(Particle size)
The volume average particle size of the toner particles (A) is not particularly limited as long as it is in the range of 2 μm or more and 10 μm or less. However, the transfer performance is enhanced and the effect of controlling the liberation rate of the silica particles (B) is also enhanced. From the point, 2 μm or more and 6 μm or less are desirable.

The volume average particle diameter of the toner particles is measured using a Coulter Multisizer-II type (manufactured by Beckman Coulter, Inc.) with an aperture diameter of 50 μm. At this time, the measurement is performed after the toner particles are dispersed in an electrolyte aqueous solution (isoton aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more.
As a measuring method, 0.5 to 50 mg of a measurement sample is added to 2 ml of a 5% aqueous solution of a surfactant, preferably sodium alkylbenzenesulfonate as a dispersant, and this is added to 100 to 150 ml of the electrolytic solution. The electrolytic solution in which the measurement sample is suspended is subjected to a dispersion treatment with an ultrasonic disperser for about 1 minute, and the particle size distribution of the particles is measured. The number of particles to be measured is 50,000.
For the measured particle size distribution, a cumulative distribution is drawn from the smaller diameter side with respect to the divided particle size range (channel), and the particle size at which 50% is accumulated is defined as the volume average particle size.

(Manufacturing method of toner particles (A))
The toner particles (A) may be produced by a dry process (for example, a kneading pulverization process), a wet process (for example, an aggregation coalescence method, a suspension polymerization method, a dissolution suspension granulation method, a dissolution suspension method, a dissolution emulsion aggregation aggregation method). Etc.).
There is no restriction | limiting in particular in these manufacturing methods, A well-known manufacturing method is employ | adopted.

[Silica particles (B)]
The silica particles (B) as the external additive have a volume average particle diameter of 70 nm to 400 nm and an average circularity of 0.5 to 0.9.
Hereinafter, the physical properties and characteristics of the silica particles (B) will be described.

(Particle size)
The volume average particle diameter of the silica particles (B) is 70 nm or more and 400 nm or less, but is preferably 90 nm or more and 250 nm or less in consideration of release from the toner particles.
By setting the volume average particle diameter of the silica particles to 70 nm or more, embedding in the toner particles (A) is suppressed, and a function as an external additive (function as a spacer) is secured.
On the other hand, when the volume average particle diameter of the silica particles is 400 nm or less, the release from the toner particles is suppressed, so that the released silica particles are prevented from damaging the photoreceptor and causing image defects over time. The

  The volume average particle diameter of the silica particles is determined by observing 100 primary particles of the silica particles after the silica particles are dispersed in the toner particles with an SEM (Scanning Electron Microscope) apparatus, and analyzing the primary particles for the longest diameter for each particle. The shortest diameter is measured, 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 volume average particle diameter of the silica particles.

(Roundness)
Further, the average circularity of the silica particles (B) is 0.5 or more and 0.9 or less, preferably 0.5 or more and 0.8 or less.
By setting the average circularity of the silica particles to 0.5 or more, stress concentration is suppressed when a mechanical load is applied, and defects due to the mechanical load are suppressed.
On the other hand, when the average circularity of the silica particles is 0.9 or less, the shape becomes irregular, the movement of the toner particles to the concave portion is suppressed, and the function as an external additive (function as a spacer) is secured. The

The degree of circularity of the silica particles is calculated by the following equation from the image analysis of the primary particles obtained by observing the primary particles of the external additive after the silica particles are dispersed in the toner particles with an SEM apparatus. / SF2 ".
Formula: Circularity (100 / SF2) = 4π × (A / I ² )
[In the formula, I represents the perimeter of the primary particles of the silica particles on the image, and A represents the projected area of the primary particles of the external additive. SF2 represents a shape factor. ]
The average circularity of the silica particles (B) is obtained as 50% circularity in the cumulative frequency of the equivalent circle diameter of 100 primary particles obtained by the image analysis.

(Manufacturing method of silica particles (B))
Silica particles (B) may be produced by, for example, a method of obtaining silica sol using water glass as a raw material, or a so-called wet method of generating particles by a sol-gel method using a silicon compound typified by alkoxysilane as a raw material. From the viewpoint of obtaining irregularly shaped silica particles that satisfy the above characteristics, the silica particles may be obtained by a method for producing silica particles (hereinafter referred to as a method for producing the present silica particles).

Hereinafter, the manufacturing method of this silica particle is demonstrated.
The method for producing the silica particles is a step of preparing an alkali catalyst solution containing an alkali catalyst at a concentration of 0.6 mol / L or more and 0.87 mol / L or less in a solvent containing alcohol (hereinafter referred to as “alkali catalyst solution preparation”). In some cases, tetraalkoxysilane is supplied into the alkali catalyst solution, and 0.1 mol or more per 1 mol of the total amount of tetraalkoxysilane supplied per minute is 0. And a step of supplying an alkali catalyst at 4 mol or less (hereinafter sometimes referred to as “particle generation step”).

That is, in the method for producing silica particles, in the presence of the alcohol containing the alkali catalyst at the above concentration, while supplying the raw material tetraalkoxysilane and the alkali catalyst as a catalyst separately in the above relationship, In this method, silica particles are produced by reacting tetraalkoxysilane.
In the present method for producing silica particles, the above-mentioned method yields irregularly shaped silica particles satisfying the above characteristics with less generation of coarse aggregates.
In particular, in this method for producing silica particles, rounded irregularly shaped silica particles having a curved surface are obtained, so that the surface obtained by the dry process has a sharp and sharp protrusion. Compared to the shape of the silica particles, the contact area with the toner particles is large, and even with irregularly shaped silica particles, the separation from the toner particles is easily suppressed, or defects due to a mechanical load are also easily suppressed. In addition, generation of color streaks is easily suppressed while suppressing wear of the electrostatic latent image holding member.
Although this reason is not certain, it is thought to be due to the following reasons.

  First, when an alkali catalyst solution containing an alkali catalyst is prepared in a solvent containing alcohol, and 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 uniformly (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 silane 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 It is considered that the particles grow while maintaining the irregular shape, and as a result, silica particles with low circularity are 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 in the method for producing silica particles, the generation of coarse aggregates is small, and irregularly shaped silica particles can be obtained.
Then, in the method for producing silica particles, the core particles grow while maintaining the irregularity, so that it is considered that rounded irregularly shaped silica particles having a curved surface are obtained.

Here, the supply amount of tetraalkoxysilane is considered to be related to the particle size distribution and circularity of the silica particles. By reducing the supply amount of the tetraalkoxysilane to 0.002 mol / (mol · min) or more and less than 0.0055 mol / (mol · min), the contact probability between the dropped tetraalkoxysilane and the core particles is reduced, It is considered that the tetraalkoxysilane is supplied to the core particles evenly before the reaction between the tetraalkoxysilanes occurs. Therefore, it is considered that the reaction between the tetraalkoxysilane and the core particles can be generated without any bias. As a result, it is considered that the dispersion of particle growth is suppressed and silica particles with a narrow distribution width can be produced.
The volume average particle diameter of the silica particles is considered to depend on the total supply amount of tetraalkoxysilane.

In addition, in the method for producing silica particles, it is considered that silica particles are generated by generating nucleus particles having an irregular shape and growing the nucleus particles while maintaining the irregular shape. It is considered that unusually shaped silica particles having high shape stability can be obtained.
In addition, in the method for producing silica particles, it is considered that the produced irregular core particles are grown while maintaining the irregular shape, and silica particles are obtained. It is believed that particles are obtained.

Further, in this method for producing silica particles, tetraalkoxysilane and alkali catalyst are respectively supplied to the alkali catalyst solution to cause a reaction of tetraalkoxysilane, thereby generating particles. Compared with 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, it is possible to omit the step of removing the alkali catalyst. This is particularly advantageous when silica particles are applied to products that require high purity.
Hereinafter, each process in the manufacturing method of this silica particle is demonstrated in detail.

-Alkaline catalyst solution preparation process-
First, 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 0.87 mol / L, desirably 0.63 mol / L or more and 0.78 mol / L, more desirably 0.66 mol / L or more and 0. .75 mol / L.
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 0.87 mol / L, the stability of the generated core particles is excessive, and true spherical core particles are generated, and the average circularity is 0.90 or less. It may be difficult to obtain core particles.
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).

-Particle generation process-
Next, the particle generation process will be described.
In the particle generation step, tetraalkoxysilane and an alkali catalyst are respectively supplied to an alkali catalyst solution, and the tetraalkoxysilane is reacted (hydrolysis reaction, condensation reaction) in the alkali catalyst solution to obtain silica particles. Is a step of generating.
In this particle generation process, after the core particles are generated by the reaction of tetraalkoxysilane at the initial stage of supply of tetraalkoxysilane (core particle generation stage), the core particles are grown (core particle growth stage), and then the silica particles are Generate.

  Examples of the tetraalkoxysilane 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 0.0055 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 or more and 0.0055 mol or less per minute with respect to 1 mol of alcohol used in the step of preparing the alkali catalyst solution.
The particle size of the silica particles depends on the type of tetraalkoxysilane and the reaction conditions, but the total supply amount of tetraalkoxysilane used in the particle generation reaction is, for example, 0.756 mol with respect to 1 L of silica particle dispersion. By setting it as the above, the primary particle of a particle size of 70 nm or more is obtained, and a primary particle of a particle size of 400 nm or less is obtained by setting it as 4.4 mol or less with respect to 1 L of silica particle dispersion liquids.

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.
If the supply amount of tetraalkoxysilane exceeds 0.0055 mol / (mol · min), it is considered that the reaction between the tetraalkoxysilanes occurs before the dropped tetraalkoxysilane reacts with the core particles. . Therefore, it contributes to the uneven distribution of tetraalkoxysilane supply to the core particles, resulting in variations in the formation of core particles, thus expanding the distribution width of the shape distribution and producing silica with a circularity standard deviation of 0.3 or less. May be difficult to do.

  The supply amount of tetraalkoxysilane is preferably 0.002 mol / (mol · min) or more and 0.0045 mol / (mol · min) or less, and more preferably 0.002 mol / (mol · min) or more and 0.0035 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 silica particles with low circularity cannot be obtained.

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

  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.

  Silica particles are obtained through the above steps. In this state, the resulting silica particles are obtained in the form of a dispersion, but the solvent is removed and used as a silica particle powder.

Solvent removal methods for the silica particle dispersion include 1) a method of removing the solvent by filtration, centrifugation, distillation, etc., and then drying with a vacuum dryer, shelf dryer, etc. 2) a 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 surface of the silica particles.
The dried silica particles are preferably crushed and sieved 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.

-Hydrophobization process-
Here, the silica particles obtained by the production method of the present silica particles may be used by hydrophobizing the surface of the silica particles 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 the silica particles. It is as follows.

As a method for obtaining a hydrophobic silica particle dispersion subjected to a hydrophobizing treatment with a hydrophobizing agent, for example, a necessary amount of a hydrophobizing agent is added to the silica particle dispersion, and 30 to 80 ° C. with stirring. The method of hydrophobizing a silica particle by making it react in the temperature range of this, and obtaining the hydrophobic silica particle dispersion liquid is mentioned. 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 silica particles tends to occur. is there.
On the other hand, as a method of obtaining powdery hydrophobic silica particles, a method of obtaining a hydrophobic silica particle dispersion by the above method after obtaining a hydrophobic silica particle dispersion, the silica particle dispersion Was dried to obtain a powder of hydrophilic silica particles, and then a hydrophobic treatment agent was added and subjected to a hydrophobic treatment to obtain a powder of hydrophobic silica particles, and a hydrophobic silica particle dispersion was obtained. Examples thereof include a method of obtaining a powder of hydrophobic silica particles after drying to obtain a powder of hydrophobic silica particles, and further applying a hydrophobizing treatment by adding a hydrophobizing agent.

Here, as a method of hydrophobizing the silica particles of the powder, the hydrophilic silica particles of the powder are stirred in a processing tank such as a Henschel mixer or a fluidized bed, and a hydrophobizing agent is added thereto, and the processing tank A method of gasifying the hydrophobizing agent by heating the inside and reacting it with silanol groups on the surface of the silica particles of the powder is mentioned. 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.
As described above, hydrophobized silica particles (B) are obtained.

[Free rate]
In the toner according to the exemplary embodiment, the liberation rate of the silica particles (B) with respect to the toner particles (A) is 5% or more and 30% or less.
When the liberation rate is less than 5%, the effect as a spacer as an external additive cannot be obtained, and the transfer performance is lowered.
Further, when the liberation rate exceeds 30%, the image density varies.
The liberation rate is more desirably 10% or more and 30% or less, and further desirably 10% or more and 20% or less.

The liberation rate is measured by the following method.
The coverage x of the silica particles (B) to the toner particles (A) is determined by measuring the adhesion area of the silica particles by image analysis using SEM, and the ratio of the total adhesion area a of the silica particles to the surface area b of the silica mother particles [ (A / b) × 100].

The coverage y of the silica particles (B) fixed on the toner surface (not released) is obtained through the following steps.
2 g of toner is dispersed in 40 ml of an aqueous solution containing 0.2% by mass of a surfactant. This is stirred using a magnetic stirrer and a stirrer at 500 rpm for 30 seconds to obtain a sample. Thereafter, the toner particles are separated by centrifuging with a 50 cc sedimentation tube under the condition of 10,000 rpm × 2 minutes and the supernatant liquid is removed. Then, the particles added to the toner are washed away with pure water to obtain a toner sample. Next, the powder toner sample is obtained by drying at room temperature (25 ° C.) for 20 hours or more, and the adhesion area of the silica particles is measured by image analysis by SEM, and the total adhesion of the silica particles to the surface area b of the silica mother particles. The coverage ratio y is calculated from the ratio of the area a [(a / b) × 100].
The liberation rate is calculated from [((xy) / x) × 100] using the coverage rate x and the coverage rate y.
Note that the average values of the measured values of 100 or more toners are used as the coverages x and y used for calculating the liberation rate.

When the toner according to the exemplary embodiment includes an external additive other than the silica particles (B), whether the liberation rate of the silica particles (B) is in the above range is determined as follows. Judgment can be made.
When calculating the coverage ratios x and y, the coverage area c of the silica particles (B) is [a / (b + c) × 100 by measuring the adhesion area c of external additives other than silica particles by image analysis using SEM. ].

(Coverage)
The coverage x of the silica particles (B) with respect to the toner particles (A) is desirably 20% by mass or more and 80% by mass or less.
When the coverage is 20% or more, the transfer performance can be improved, and when it is 80% or less, the liberation rate can be easily controlled.
Further, the coating amount is more preferably 25% or more and 60% or less, and further preferably 25% or more and 40% or less.

[Toner Production Method]
Next, a toner manufacturing method according to this embodiment will be described.
The toner according to the exemplary embodiment can be obtained by externally adding silica particles (B) to toner particles (A) after producing toner particles and silica particles (B) as external additives.
Examples of the method of externally adding the silica particles (B) to the toner particles (A) include a method of mixing with a known mixer such as a V-type blender, a Henschel mixer, or a Redige mixer. In order to set the liberation rate of the silica particles (B) to 5% or more and 30% or less, the conditions for mixing may be appropriately changed as follows.
Examples of the mixing conditions include the temperature at the time of mixing, the number of times of mixing, and the selection of an apparatus.
Here, when controlling the said liberation rate by adjusting the temperature at the time of mixing, a liberation rate can be lowered | hung by raising temperature.
Even when other conditions are employed, the liberation rate can be reduced if the conditions are such that the silica particles (B) adhere more strongly to the toner particles (A).

<Electrostatic image developer>
The electrostatic charge image developer according to the exemplary embodiment includes 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 electrostatic latent image holding member, a charging unit that charges the surface of the electrostatic latent image holding member, and an electrostatic latent image that forms an electrostatic latent image on the surface of the electrostatic latent image holding member. The electrostatic latent image forming means and the electrostatic charge developing developer according to this embodiment are accommodated, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed with the developer to form a toner image. A developing unit for forming, a transfer unit for transferring the toner image to the recording medium, a fixing unit for fixing the toner image on the recording medium, and a cleaning unit for contacting the surface of the electrostatic latent image holding member to clean the surface. , And is configured.

  According to the image forming apparatus according to the present embodiment, the charging step of charging the surface of the electrostatic latent image holding member and the electrostatic latent image forming step of forming an electrostatic charge image on the surface of the charged electrostatic latent image holding member. A developing step of developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member with the developer for electrostatic charge development according to the present embodiment to form a toner image; and using the toner image as a recording medium An image forming method including a transfer step of transferring, a fixing step of fixing a toner image on a recording medium, and a cleaning step of cleaning the surface of the electrostatic latent image holding member is performed.

  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 electrostatic latent image holding member. 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 attached to the electrostatic latent image in contact with or in proximity to a developing roll having a developer layer formed on the surface, thereby forming a toner image 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. Further, after the toner image is transferred from the electrostatic latent image holding member, the surface of the electrostatic latent image holding member is cleaned and then charged again.

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 this 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 this embodiment is accommodated, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed by the electrostatic charge developing developer. A process cartridge that includes a developing unit that forms a toner 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. The support roller 24 is applied with a force in a direction away from the driving 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. It should be noted that reference numerals with magenta (M), cyan (C), and black (K) are attached to the same parts as those of the first unit 10Y instead of yellow (Y). 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 cleaning, and a photoreceptor cleaning device (cleaning unit) 6Y that includes a cleaning blade 6Y-1 that removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer are sequentially arranged. ing.
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 accommodated. 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 blade 6Y-1 of 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, the recording paper (transfer object) P is fed at a predetermined timing to the gap where the secondary transfer roller 26 and the intermediate transfer belt 20 are pressed against each other via the 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 paper P is applied to the toner image, and the transfer bias is applied to the intermediate transfer belt 20. The toner image is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording paper P is fed to the pressure contact portion (nip portion) of the pair of fixing rolls in the fixing device (roll-type fixing means) 28, the toner image is heated, and the color-superposed toner image is melted to record the recording paper. 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 preferable that the surface of the transfer target is as smooth as possible. For example, a coated paper in which the surface of plain paper is coated with a resin, etc. Art paper or the like is preferably used.

The recording paper P on which the color image has been fixed is carried out toward 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 onto the recording paper P via the intermediate transfer belt 20, but the present invention is not limited to this configuration, and the toner image is directly transferred from the photoconductor. It may be a structure that is transferred to a recording sheet.

<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 includes, together with the photoconductor 107, a charging roller 108, a developing device 111, a photoconductor cleaning device 113 having a cleaning blade 113-1, an opening 118 for exposure, and an opening 117 for static elimination exposure. Attachment, combination using rails 116, and integration. 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 for static elimination exposure. 117, at least one selected from the group consisting of 117.

  Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the present embodiment is a toner cartridge that contains toner for developing an electrostatic 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. In the following description, “part” and “%” all mean “part by mass” and “mass%” unless otherwise specified.

[Production of toner particles]
(Preparation of toner particles 1)
-Preparation of resin particle dispersion 1-
-Styrene (Wako Pure Chemical Industries): 320 parts-n-butyl acrylate (Wako Pure Chemical Industries): 80 parts-Beta carboxyethyl acrylate (Rhodia Nikka): 9 parts-1'10 Decanediol diacrylate (Shin Nakamura Chemical) Manufactured): 1.5 parts · Dodecanethiol (manufactured by Wako Pure Chemical Industries): 2.7 parts 4 parts of the anionic surfactant Dowfax (manufactured by Dow Chemical Co., Ltd.) is added to the above components mixed and dissolved. The solution dissolved in the part was added, dispersed and emulsified in the flask, and slowly stirred and mixed for 10 minutes. Further, 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 (Wako Pure Chemical Industries): 280 parts-n-Butyl Acrylate (Wako Pure Chemical Industries): 120 parts-Beta Carboxyethyl Acrylate (Rhodia Nikka): 9 parts A solution obtained by dissolving 1.5 parts of the activator Dowfax (manufactured by Dow Chemical Co., Ltd.) in 550 parts of ion-exchanged water is dispersed and emulsified in a flask, stirred and mixed slowly for 10 minutes, and further 0.4 parts of ammonium persulfate. 50 parts of ion-exchanged water in which 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 Nippon Oil & Fats Co., Ltd .: Nurex R): 2 parts, ion-exchanged water: 220 parts The above ingredients are mixed and mixed with a homogenizer (IKA Ultra Turrax). After pre-dispersion, the dispersion process is performed for 15 minutes at a pressure of 245 Mpa using an optimizer (counter-impact type wet pulverizer: Sugino Machine), and the colorant particle center particle size is 169 nm and the solid content is 22.0%. Agent particle dispersion 1 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 ingredients are mixed to 100 ° C Heat and disperse with Ultra Turrax T50 (manufactured by IKA), then disperse with a pressure discharge type gorin homogenizer, and release agent particles with a center particle size of 196 nm and a solid content of 22.0% Dispersion 1 was obtained.

-Production of toner particles 1-
-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 45 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 4.5 μm.

(Preparation of toner particles 2)
Toner particles 2 having a volume average particle size of 6.4 μm were obtained in the same manner as toner particles 1 except that the temperature was maintained at 49 ° C. for 60 minutes.

[Preparation of silica particles]
(Granulation process)
-Alkali catalyst solution preparation step [Preparation of alkali catalyst solution]-
Put 300 parts by mass of methanol and 50.4 parts by mass of 10% ammonia water in a 3 L glass reaction vessel with a metal stirring bar, dripping nozzle (Teflon (registered trademark) micro tube pump), and thermometer. The mixture was stirred and mixed to obtain an alkali catalyst solution.

-Particle generation step [Preparation of silica particle suspension]-
Next, the temperature of the alkali catalyst solution was adjusted to 25 ° C., and the alkali catalyst solution was purged with nitrogen. Then, while stirring the alkali catalyst solution, 450 parts by mass of tetramethoxysilane (TMOS) and 270 parts by mass of ammonia water having a catalyst (NH3) concentration of 4.44% were simultaneously added dropwise at the following supply amount to obtain silica. A suspension of particles (silica particle suspension) was obtained.
Here, the supply amount of tetramethoxysilane was 7.79 parts by mass / min, and the supply amount of 4.44% ammonia water was 4.68 parts by mass / min.
When the particles of the obtained silica particle suspension were measured with the particle size measuring apparatus described above, the volume average particle diameter (D50v) was 185 nm.

(Drying process)
Next, the obtained suspension of hydrophilic silica particles (hydrophilic silica particle dispersion) was dried by spray drying to remove the solvent to obtain hydrophilic silica particle powder.

(Hydrophobicization process)
100 parts by mass of the obtained hydrophilic silica particle powder was put in a mixer and stirred at 200 rpm while heating to 200 ° C. in a nitrogen atmosphere, and hexamethyldisilazane (HMDS) was added to the hydrophilic silica particle powder in 30 parts. Part by mass was dropped and reacted for 2 hours. Then, the powder of the hydrophobic silica particle (1) which was cooled and hydrophobized was obtained.

  The obtained hydrophobic silica particles (1) were added to toner particles, and SEM photography was performed on 100 primary particles of hydrophobic silica particles. Next, as a result of performing image analysis on the obtained SEM photograph, the primary particles of the hydrophobic silica particles (1) had an average circularity of 0.72.

  Table 1 shows the supply amount of methanol, 10% ammonia water in the preparation step of alkali catalyst in the granulation step, and the supply amount of tetramethoxysilane in the particle generation step in the preparation of the sol-gel silica. Hydrophobic silica particles (2) to (9) were obtained under the conditions shown below. In addition, each particle diameter and average circularity were as shown in Table 1.

[Examples 1 to 10, Comparative Examples 1 to 6]
(Manufacture of toner)
In the following manner, toner particles and silica particles were blended, and the silica particles were externally added to the toner particles to produce toners (1) to (10) and (R1) to (R6). The external addition conditions at the time of manufacturing each toner are as follows.
For the blending of toner particles and silica particles, a Henschel mixer modified so that the temperature of the outer wall was kept constant with a heat medium so that the toner temperature in the blend could be observed was used.

Toner (1): 100 parts by mass of toner particles (1) and 10 parts by mass of silica particles (1) were blended with a Henschel mixer at a peripheral speed of 30 m / s × 15 minutes, and the release rate was 18.1% and the coverage was 40. 2% of toner (1) was obtained. The outer wall temperature during blending was kept at 42 ° C., and the toner temperature during blending was controlled to be 42 ° C. to 45 ° C.
Toner (2): Toner (2) was obtained in the same manner as toner (1) except that the outer wall temperature during blending was maintained at 44 ° C. and the toner temperature during blending was controlled to be between 44 ° C. and 47 ° C. .
Toner (3): Toner (3) was obtained in the same manner as toner (1) except that the outer wall temperature during blending was maintained at 38 ° C. and the toner temperature during blending was controlled to be between 38 ° C. and 40 ° C. .
Toner (4): Toner (4) was obtained in the same manner as Toner (1) except that the silica particles (1) were changed to 4 parts by mass.
Toner (5): Toner (5) was obtained in the same manner as toner (1) except that the silica particles (1) were changed to 22 parts by mass.

Toner (6): Toner (6) was obtained in the same manner as toner (1) except that toner particles (1) were changed to toner particles (2).
Toner (7): Toner (7) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 4 parts by mass of silica particles (2).
Toner (8): Toner (8) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 24 parts by mass of silica particles (3).
Toner (9): Toner (9) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 10 parts by mass of silica particles (4).
Toner (10): Toner (10) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 10 parts by mass of silica particles (5).

Toner (R1): Toner (R1) was obtained in the same manner as toner (2) except that the blending time was changed to 30 minutes.
Toner (R2): Toner (R2) was obtained in the same manner as toner (3) except that the blending time was changed to 10 minutes.
Toner (R3): Toner (R3) was obtained in the same manner as toner (1) except that silica particle (1) was changed to 4 parts by mass of silica particle (6).
Toner (R4): Toner (R4) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 24 parts by mass of silica particles (7).
Toner (R5): Toner (R5) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 10 parts by mass of silica particles (8).
Toner (R6): Toner (R6) was obtained in the same manner as toner (1), except that the silica particles (1) were changed to 10 parts by mass of silica particles (9).

(Manufacture of developer)
The obtained toner and carrier were put in a V blender at a ratio of toner (1): carrier = 5: 95 (mass ratio) and stirred for 20 minutes to obtain a developer.

In addition, the carrier produced as follows was used.
1,000 parts of Mn—Mg ferrite (volume average particle size: 50 μm, manufactured by Powder Tech Co., Ltd., shape factor SF1: 120) were added to a kneader, and a perfluorooctylmethyl acrylate-methyl methacrylate copolymer (polymerization ratio: 20 / 80, Tg: 72 ° C., weight average molecular weight: 72,000, manufactured by Soken Chemical Co., Ltd.] A solution obtained by dissolving 150 parts in 700 parts of toluene was added, mixed at room temperature for 20 minutes, and then heated to 70 ° C. under reduced pressure. After drying, the product was taken out to obtain a coated carrier, which was further sieved with a mesh having a mesh opening of 75 μm to remove coarse powder, and the carrier had a shape factor SF1 of 122.

[Evaluation]
The developer obtained in each example was filled in a 700 DCP developer manufactured by Fuji Xerox Co., Ltd., and evaluation was performed for density 1, density 2, and image defect as follows. The results are shown in Table 2.

The toner obtained as described above was allowed to stand at high temperature and high humidity (28 ° C., 85%) for 3 days, and evaluation was started. Moreover, the environment where the following evaluation was performed was also under high temperature and high humidity (28 degreeC85%).
First, after continuously outputting 10,000 images with an area coverage of 1%, a patch of 100 cm solid and 5 cm × 5 cm was prepared using C2 paper manufactured by Fuji Xerox Co., Ltd., and the density 1 was confirmed. Here, this density confirmation was measured and digitized by an image density system X-Rite (manufactured by X-Rite). The density confirmed at this time is defined as density (SAD).
The criteria for determining the concentration (SAD) are as follows.
: Density (SAD) ≧ 1.5
○: Concentration (SAD) ≧ 1.5 to 1.4
○-: Concentration (SAD) ≧ 1.4 to 1.3
×: Concentration (SAD) ≧ 1.3 to 1.2
XX: Concentration (SAD) <1.2
Note that the evaluation of samples having a density of 1 or less was stopped.

Subsequently, after continuously outputting 5000 images with an area coverage of 50%, a patch similar to that for checking the density 1 was created, and the density 2 was checked. Here, this concentration confirmation was performed in the same manner as the concentration 1.
A difference (absolute value) between the concentration 2 and the concentration 1 was obtained, and this was set as a Δ concentration. That is, Δ concentration = | concentration 1−concentration 2 |.
The criteria for determining the Δ concentration are as follows.
A: 0 <Δ concentration = | concentration 1−concentration 2 | ≦ 0.1
○: 0.1 <Δ concentration = | concentration 1−concentration 2 | ≦ 0.15
○-: 0.15 <Δ concentration = | concentration 1−concentration 2 | ≦ 0.2
×: 0.2 <Δ concentration = | concentration 1−concentration 2 | ≦ 0.3
XX: 0.3 <Δ concentration = | concentration 1−concentration 2 |

Furthermore, the image obtained when “10000 images of 1% area coverage are output continuously”, and further, the image obtained when “5000 images of 50% area coverage are output continuously”. About 100 sheets, image defects (color streaks / color loss) were checked visually (total of 150 sheets).
The criteria for determining image defects (color streaks / color loss) are as follows.
◎: No image defect ○: One image defect ○-: Two image defects ×: Two sheets <Image defect ≦ 4 sheets XX: Five sheets <Image defect

From the above results, it can be seen that, in this embodiment, an image with reduced density fluctuation can be obtained even when printing is performed by changing the image density from low density to high density, as compared with the comparative example. .
Further, in this example, no image defect was observed during printing in both cases of low density and high density.

1Y, 1M, 1C, 1K, 107 photoconductor (image carrier)
2Y, 2M, 2C, 2K, 108 Charging roller 3Y, 3M, 3C, 3K Laser beam 3, 110 Exposure device 4Y, 4M, 4C, 4K, 111 Developing device (developing means)
5Y, 5M, 5C, 5K Primary transfer rollers 6Y, 6M, 6C, 6K, 113 Photoconductor cleaning device (cleaning means)
8Y, 8M, 8C, 8K Developer cartridge 10Y, 10M, 10C, 10K Unit 20 Intermediate transfer belt 22 Drive roller 24 Support roller 26 Secondary transfer roller (transfer means)
28, 115 Fixing device (fixing means)
30 Intermediate transfer member cleaning device 112 Transfer device 116 Mounting rail 117 Opening 118 for static elimination exposure Opening 200 for exposure Process cartridge,
P, 300 Recording paper (transfer object)

Claims (8)

  Toner particles, and silica particles having a volume average particle size of 70 nm to 400 nm and an average circularity of 0.5 to 0.9, and the liberation rate of the silica particles with respect to the toner particles is 5% to 30%. % Toner for developing electrostatic images.   The toner for developing an electrostatic charge image according to claim 1, wherein the toner particles have a volume average particle diameter of 2 μm or more and 6 μm or less.   The electrostatic charge image developing toner according to claim 1, wherein a coverage of the silica particles with respect to the toner particles is 20% or more and 80% or less.   An electrostatic charge image developing developer comprising the electrostatic charge image developing toner according to claim 1. An electrostatic charge image developing toner according to any one of claims 1 to 3 is accommodated,
A toner cartridge that is detachable from the image forming apparatus. The developer for electrostatic charge development according to claim 4 is accommodated, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed with the developer for electrostatic charge development to form a toner image. Development means,
A process cartridge that is detachable from the image forming apparatus. An electrostatic latent image carrier;
Charging means for charging the surface of the electrostatic latent image holding member;
Electrostatic latent image forming means for forming an electrostatic latent image on the surface of the charged electrostatic latent image holding member;
5. The developer for electrostatic charge development according to claim 4 is accommodated, and the electrostatic latent image formed on the surface of the electrostatic latent image holding member is developed with the developer for electrostatic charge development to form a toner image. Developing means to form;
Transfer means for transferring the toner image to a recording medium;
Fixing means for fixing a toner image on the recording medium;
Cleaning means for cleaning the surface in contact with the surface of the electrostatic latent image carrier;
An image forming apparatus comprising: A charging step for charging the surface of the electrostatic latent image holding member;
An electrostatic latent image forming step of forming an electrostatic charge image on the surface of the charged electrostatic latent image holding member;
A developing step of developing the electrostatic latent image formed on the surface of the electrostatic latent image holding member to form a toner image by the electrostatic charge developing developer according to claim 4;
A transfer step of transferring the toner image to a recording medium;
A fixing step of fixing a toner image on the recording medium;
A cleaning step of cleaning the surface in contact with the surface of the electrostatic latent image carrier;
An image forming method comprising: