JP2014186250A - 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 that suppresses the occurrence of fogging, and suppresses a reduction in image density in images to be formed.SOLUTION: A toner for electrostatic charge image development includes: toner particles; and sol-gel silica particles that are externally added to the toner particles, have a moisture percentage (A) of 4 mass% or more and 10 mass% or less after being left in an environment of a temperature of 28°C and a humidity of 85% for 24 hours, and have the relationship between the moisture percentage (A) and a moisture percentage (B) satisfying (B)/(A)≥0.9, where (B) represents a moisture percentage of the sol-gel silica particles after being left in an environment of a temperature of 28°C and a humidity of 85% for 24 hours and further being left in an environment of a temperature of 45°C and a humidity of 50% for one hour.

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 electrophotographic image formation, toner is used as an image forming material, and for example, many toner particles containing a binder resin or a colorant and an external additive externally added to the toner particles are used. It is used.

For example, in Patent Document 1, in a toner having toner particles and inorganic particles containing at least a binder resin and a colorant, the inorganic particles are particles formed by a sol-gel method, and the inorganic particles are left in a high-temperature and high-humidity environment. _Moisture content M _HH after standing at 30 ° C./80% environment for 72 hours and room temperature and low humidity environment; Ratio of moisture content M _NL after standing at 23 ° C./5% environment for 72 hours M _HH / M _NL Disclosed is a toner having a water content _MNL of 0.1% or more and less than 3.0% after being left at room temperature and low humidity, and an average particle size of 80 nm to 200 nm. Yes.

  In Patent Document 2, toner particles containing a binder resin and a colorant, polytetrafluoroethylene particles having a perfluorooctanoic acid and salt content of 0.5 ppm or less, and a temperature of 20 ° C. and a humidity of 20% are disclosed. An electrostatic charge image developing toner containing silica particles having a water content of 0.1% by mass to 10% by mass in an environment is disclosed.

  Patent Document 3 discloses an image forming toner in which inorganic particles are externally added to toner base particles composed of at least a binder resin and a colorant, and the volume distribution variation coefficient in the particle size distribution is added to the toner base particles. Discloses an image-forming toner comprising 50% or less of inorganic particles A deposited by wet processing.

JP 2006-308642 A JP2011-059586A JP 2005-266557 A

  An object of the present invention is to provide an electrostatic image developing toner capable of suppressing the occurrence of fogging and suppressing a decrease in image density in a formed image.

The above problem is solved by the following means. That is,
The invention according to claim 1
Toner particles,
The moisture content (A) after being externally added to the toner particles and allowed to stand for 24 hours in an environment at a temperature of 28 ° C. and a humidity of 85% is 4% by mass to 10% by mass, and the temperature is 28 ° C. and a humidity of 85%. A sol-gel in which the relationship between the moisture content (B) and the moisture content (A) after standing for 24 hours in an environment of 45 ° C. and 50% humidity is (B) / (A) ≧ 0.9 Silica particles;
A toner for developing an electrostatic charge image.

The invention according to claim 2
The water content (A) is 5% by mass or more and 8% by mass or less, and the relationship between the water content (B) and the water content (A) is (B) / (A) ≧ 0.93. Item 2. The toner for developing an electrostatic charge image according to Item 1.

The invention according to claim 3
An electrostatic charge image developer comprising the toner for developing an electrostatic charge image according to claim 1.

The invention according to claim 4
Containing the electrostatic image developing toner according to claim 1 or 2,
A toner cartridge to be attached to and detached from the image forming apparatus.

The invention according to claim 5
A developing unit that contains the electrostatic charge image developer according to claim 3 and that develops the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer.
A process cartridge attached to and detached from the image forming apparatus.

The invention according to claim 6
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 charged image carrier;
A developing means for containing the electrostatic charge image developer according to claim 3 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising:

The invention according to claim 7 provides:
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 charged image carrier;
A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 3;
A transfer step of transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
A fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising:

  According to the first aspect of the present invention, the moisture content (A) after standing for 24 hours in an environment having a temperature of 28 ° C. and a humidity of 85% is 24% to 10% by mass, and the temperature is 28 ° C. and a humidity of 85%. Sol gel silica in which the relationship between the water content (B) and the water content (A) after standing for 1 hour in an environment of temperature 45 ° C. and humidity 50% is (B) / (A) ≧ 0.9 As compared with the case where particles are not externally added, there is provided an electrostatic image developing toner capable of suppressing the occurrence of fogging and suppressing the decrease in image density in the formed image.

  According to the invention which concerns on Claim 2, the said moisture content (A) is 5 mass% or more and 8 mass% or less, and the relationship between the said moisture content (B) and the said moisture content (A) is (B) / (A) An electrostatic charge image developing toner capable of further suppressing a decrease in image density in an image to be formed is provided as compared with a case where sol-gel silica particles satisfying ≧ 0.93 are not externally added.

  According to the inventions according to claims 3, 4, 5, 6, and 7, the moisture content (A) after standing for 24 hours in an environment having a temperature of 28 ° C. and a humidity of 85% is not less than 4 mass% and not more than 10 mass%. The relationship between the moisture content (B) and the moisture content (A) after being left in an environment of 28 ° C. and 85% humidity for 24 hours and then in an environment of 45 ° C. and 50% humidity for 1 hour is (B) / (A ) An electrostatic charge image developer capable of suppressing a decrease in image density in the formed image as compared with a case where a toner for developing an electrostatic charge image in which sol-gel silica particles of ≧ 0.9 are externally added to the toner particles is not used. A toner cartridge, a process cartridge, an image forming apparatus, and an image forming method are provided.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the process cartridge which concerns on this embodiment.

  Hereinafter, details of the toner according to the exemplary embodiment will be described.

The electrostatic image developing toner according to the present embodiment (also simply referred to as “toner”) includes toner particles and sol-gel silica particles externally added to the toner particles.
The sol-gel silica particles in the present embodiment (also simply referred to as “specific silica particles”) have a moisture content (A) of 4% by mass or more and 10% by mass after being left for 24 hours in an environment having a temperature of 28 ° C. and a humidity of 85%. The relationship between the water content (B) and the water content (A) after being left for 24 hours in an environment with a temperature of 28 ° C. and a humidity of 85% and after leaving in an environment with a temperature of 45 ° C. and a humidity of 50% for 1 hour. (B) / (A) ≧ 0.9.

  In order to stabilize the charge distribution of the toner, it is effective to increase the water content of the silica particles as an external additive to the toner particles. On the other hand, if the water content of the silica particles is excessively increased, the charge amount of the toner is reduced in the first place, and fogging may occur as an image defect. For this reason, it is effective to increase the water content of the silica particles, which are external additives to the toner particles, to some extent within the range where fog does not occur. However, when toner with externally added silica particles is used, the image density in the formed image may be reduced. In particular, when the water content of silica particles is high to some extent, the decrease in image density tends to be significant. It was.

  In contrast, in the toner according to the present embodiment, the sol-gel silica particles externally added to the toner particles have a moisture content (A) of 4% by mass to 10% by mass as described above, and (B) / ( A) Specific silica particles satisfying ≧ 0.9 are used, thereby suppressing the occurrence of fogging and suppressing the decrease in image density in the formed image.

The mechanism by which this effect is achieved is not necessarily clear, but is presumed as follows.
In the image forming apparatus, the temperature inside the machine rapidly rises and the relative humidity inside the machine decreases, that is, the inside of the machine may dry. This is due to the influence of heat and the like generated from each member of the image forming apparatus. In particular, the smaller the image forming apparatus is, the higher the process speed is, and the more the number of images is formed. That is, it tends to become more prominent as the number of continuous use increases. Further, it differs depending on the environment in which the image forming apparatus is installed, and becomes more prominent as the humidity is higher.
When the temperature inside the machine rises rapidly, the silica particles added to the toner particles are thought to cause a decrease in moisture content, and the charge distribution deteriorates due to the decrease in moisture content. It seems to rise. For this reason, it is presumed that uneven charging occurs for each toner, and toner that does not move to the surface of the image carrier is generated during development, resulting in a decrease in image density in the formed image.
On the other hand, the specific silica particles externally added to the toner of the present embodiment is 1 in an environment where the temperature is 45 ° C. and the humidity is 50% relative to the moisture content after being left for 24 hours in an environment where the temperature is 28 ° C. and the humidity is 85%. The change in the moisture content after being left for a period of time is suppressed to 10% by mass or less. Therefore, even when the temperature inside the machine rises rapidly, the water content of the sol-gel silica particles is effectively suppressed from being reduced, and the deterioration of the charge distribution and the increase in charge are suppressed to form. It is conceivable that a decrease in image density in the image is suppressed.

  In the present embodiment, the environment for measuring the moisture content (A) and (B) of the sol-gel silica particles is “after leaving for 24 hours in an environment of temperature 28 ° C. and humidity 85%” and “temperature 28 ° C. and humidity 85%. “After leaving for 24 hours in an environment of 45 ° C. and 1 hour in an environment of 45 ° C. and 50% humidity”, the temperature inside the machine is 45 when images are continuously formed in a general image forming apparatus. This is because the temperature may rise to about ° C. Further, when the humidity fluctuates in the range of 50% or more and 85% or less (further, in the range of 60% or more and 65% or less), the influence on the fluctuation of the toner charge amount becomes large.

[Specific silica particles]
The specific silica particles in the present embodiment have a moisture content (A) of 4 mass% or more and 10 mass% or less after being left in an environment having a temperature of 28 ° C. and a humidity of 85% for 24 hours and an environment having a temperature of 28 ° C. and a humidity of 85%. (B) / (A) ≧ 0.9 between the moisture content (B) and the moisture content (A) after being left for 24 hours in an environment of 45 ° C. and 50% humidity for 1 hour. .

(Moisture content (A), (B))
When the moisture content (A) is less than 4% by mass, the charge distribution of the toner is not stable. On the other hand, if it exceeds 10% by mass, the charge amount of the toner becomes small in an environment of high temperature and high humidity, and image defects such as fogging occur.
When (B) / (A) is less than 0.9, the image density in the formed image is significantly reduced.

The water content (A) is further preferably 5% by mass or more and 8% by mass or less, and more preferably 6% by mass or more and 7% by mass or less.
The (B) / (A) is further preferably 0.93 or more, more preferably 0.94 or more, and the closer to 1.0, the more preferable.

-Measurement of moisture content (A) and (B)-
In this embodiment, the moisture content of the silica particles in the toner is a value measured by direct titration by the Karl Fischer method (KF-06, manufactured by Mitsubishi Kasei Co., Ltd.) shown below.
First, when measuring the moisture content (A), the silica particles are left in an environment of a temperature of 28 ° C. and a humidity of 85% for 24 hours, and when measuring the moisture content (B), the silica particles are heated at a temperature of 28 ° C. and a humidity of 85%. The sample is taken for 24 hours and then left for 1 hour in an environment of temperature 45 ° C. and humidity 50%, and then a sample is taken into a dedicated screwed bottle with packing. After 10 μl of pure water is precisely weighed with a microsyringe, moisture (mg) per ml of Karl Fischer reagent is calculated from the reagent titration necessary to remove this water. Next, the measurement sample is precisely weighed in the range of 100 mg to 200 mg, and dispersed in the measurement flask with a magnetic stirrer for 5 minutes. After dispersion, measurement is started, and the amount of water and the water content are calculated by the following formula by integrating the titration amount (ml) of the Karl Fischer reagent required for titration.
Water content (mg) = reagent consumption (ml) × reagent titer (mgH ₂ O / ml)
Moisture content (%) = [water content (mg) / sample amount (mg)] × 100

-Control method of (B) / (A)-
The specific silica particles in the present embodiment have a change in moisture content after being left in an environment of 45 ° C. and 50% humidity for 1 hour with respect to the moisture content after being left in an environment of temperature 28 ° C. and humidity 85% for 24 hours. Is suppressed to 10% by mass or less. A method for achieving this configuration is not particularly limited. For example, there is a method of holding moisture in the silica particles while suppressing moisture held on the surface of the silica particles. By suppressing the moisture retained on the surface of the silica particles, the amount of water evaporated from the silica particles is suppressed even when exposed to an environment of 45 ° C. and 50% in a short time of 1 hour, (B) The value of / (A) is considered to be controlled within the above range.

  In addition, as a method of suppressing the water | moisture content hold | maintained on the surface of a silica particle, the method of reducing the quantity of OH group originating in the silanol group which exists in the surface of a silica particle specifically, is mentioned. By reducing the amount of OH groups on the surface of the silica particles, it is considered that the amount of water retained on the surface can be suppressed, thereby suppressing a decrease in image density in an image formed.

As a method for controlling the amount of OH groups on the surface of the silica particles, the amount of the hydrophobizing agent when the hydrophobizing treatment is performed on the silica particles is adjusted, and the hydrophobizing agent is added at that time. There is a method of adjusting the way.
Specifically, the amount of OH groups on the surface of the silica particles tends to decrease as the amount of the hydrophobizing agent increases. Moreover, when the hydrophobizing agent is added excessively at once, the silica particles aggregate with each other, and the amount of OH groups on the surface of the silica particles tends to increase due to non-uniformity of the hydrophobizing state on the surface of the silica particles. On the other hand, the amount of OH groups on the surface of the silica particles tends to be reduced by processing the appropriate amount of the hydrophobizing agent stepwise and uniformly processing the surface of the silica particles.

-Control method of moisture content (A)-
On the other hand, with respect to the method of controlling the moisture content (A) after being left in an environment of temperature 28 ° C. and humidity 85% for 24 hours, the silica particles are subjected to a hydrophobic treatment in a state where moisture is adsorbed. The moisture content (A) tends to increase. Also, the moisture content (A) tends to increase by storing the silica particles in a high-temperature and high-humidity environment, and then hydrophobizing the silica particles after storing them in a high-temperature and high-humidity environment for a long time. As a result, the moisture content (A) tends to increase.

(Roundness)
Moreover, it is preferable that the average circularity of a specific silica particle is 0.5 or more and 0.9 or less, More preferably, it is 0.6 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

  However, if the average circularity of the specific silica particles is 0.9 or less and the shape is irregular, the surface area increases, and it becomes more difficult to suppress moisture retained on the surface of the silica particles. However, in the present embodiment, the value of (B) / (A) is preferably controlled within the above-described range by applying the control method. Therefore, even if the silica particles have irregular shapes, it is possible to more effectively suppress a decrease in image density.

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 specific silica particles is obtained as 50% circularity in the cumulative frequency of the equivalent circle diameter of 100 primary particles obtained by the image analysis.

(Particle size)
The volume average particle diameter of the specific silica particles is not particularly limited, but is preferably 70 nm or more and 400 nm or less, and more preferably 90 nm or more and 250 nm or less.
By setting the volume average particle diameter of the silica particles to 70 nm or more, embedding in the toner particles is suppressed, and a function as an external additive (function as a spacer) is ensured. 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.

(Method for producing specific silica particles)
The specific silica particles are produced by a so-called wet method in which particles are generated by a sol-gel method using a silicon compound typified by alkoxysilane as a raw material.
In addition, from the viewpoint of controlling the value of (B) / (A) to the above-mentioned range, the amount of the hydrophobizing agent when hydrophobizing the silica particles is adjusted, and the hydrophobizing treatment at that time It is desirable to adjust how the agent is added.

  Hereinafter, an example is given and demonstrated about the manufacturing method of specific silica particle. In addition, it is preferable to manufacture a specific silica particle with the following manufacturing method from a viewpoint which makes the shape of a silica particle irregular and controls average circularity to the above-mentioned range.

  The method for producing specific 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 specific silica particles, in the presence of the alcohol containing the alkali catalyst at the above concentration, while supplying the tetraalkoxysilane as the raw material and the alkali catalyst as the catalyst separately in the above relationship, In this method, silica particles are produced by reacting tetraalkoxysilane.
In the method for producing specific silica particles, irregularly shaped silica particles satisfying the above characteristics can be obtained by the above-mentioned method with less generation of coarse aggregates.
In particular, in the method for producing specific 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 silica particles of the shape, 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, the alkali catalyst is unevenly distributed on the surface of the core particles), so that the dispersion stability of the core particles is maintained, but the surface tension and chemical affinity of the core particles are maintained. 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 specific silica particles, the generation of coarse aggregates is small, and irregularly shaped silica particles can be obtained.
And in the manufacturing method of a specific silica particle, since the particle growth of the core particle arises maintaining an irregular shape, it is thought that the irregular-shaped silica particle with the round shape by which the surface was comprised by the curved shape is 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, it is considered that the specific silica particle production method generates irregularly shaped core particles and grows the core particles while maintaining the deformed shape, thereby generating silica particles. It is thought that irregularly shaped silica particles having high properties can be obtained.
Further, in the method for producing specific silica particles, it is considered that the produced irregularly shaped core particles are grown while maintaining the irregular shape, and silica particles are obtained. It is thought that it is obtained.

In addition, in the method for producing specific silica particles, the tetraalkoxysilane reaction is caused by supplying tetraalkoxysilane and an alkali catalyst, respectively, into the alkali catalyst solution. 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, the step of removing the alkali catalyst can be omitted. This is particularly advantageous when silica particles are applied to products that require high purity.
Hereinafter, each process in the manufacturing method of specific 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 desirably 0.6 mol / L or more and 0.87 mol / L or less, more desirably 0.63 mol / L or more and 0.78 mol / L, and further desirably 0.66 mol / L. The above is 0.75 mol / L.
When the concentration of the alkali catalyst is 0.6 mol / L or more, the dispersibility of the core particles in the growth process of the generated core particles becomes stable, and the formation of coarse aggregates such as secondary aggregates is suppressed, and the gelled state And a desirable particle size distribution is obtained.
On the other hand, when the concentration of the alkali catalyst is 0.87 mol / L or less, the stability of the produced core particles is not excessively large, the formation of true spherical core particles is suppressed, and the average circularity is 0.90 or less. An irregularly shaped core particle is obtained.
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 desirably 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 0.002 mol / (mol · min) or more, the contact probability between the dropped tetraalkoxysilane and the core particles is further increased, but the total supply amount of tetraalkoxysilane is increased. It does not take a long time to finish dripping, and production efficiency is good.
When the supply amount of tetraalkoxysilane is 0.0055 mol / (mol · min) or less, the reaction between tetraalkoxysilanes is suppressed before the dropped tetraalkoxysilane reacts with the core particles. Conceivable. Therefore, uneven distribution of the tetraalkoxysilane supply to the core particles is suppressed, and variations in the formation of the core particles are suppressed. Therefore, the distribution width of the shape distribution is not expanded, and the standard deviation of the circularity is 0.3 or less. Silica can be produced.

  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 preferably 0.1 mol or more and 0.4 mol or less, more preferably 0.14 mol or more and 0.35 mol or less, per mol of the total supply amount of tetraalkoxysilane supplied per minute. More desirably, it is 0.18 mol or more and 0.30 mol or less.
When the supply amount of the alkali catalyst is 0.1 mol or more, the dispersibility of the core particles in the growth process of the generated core particles is stabilized, and the formation of coarse aggregates such as secondary aggregates is suppressed, The desired particle size distribution is obtained.
On the other hand, when the supply amount of the alkali catalyst is 0.4 mol or less, the stability of the generated core particles is not excessive, and the generation of core particles having a low circularity is suppressed at the core particle generation stage, and the core particle growth In this stage, the core particles are prevented from growing in a spherical shape, and silica particles having a low circularity can 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, in the production of the specific silica particles, it is preferable to hydrophobize the surface of the silica particles with a hydrophobizing agent from the viewpoint of controlling the value of (B) / (A) within the aforementioned range. Furthermore, it is desirable to adjust the amount of the hydrophobizing agent and to adjust the manner in which the hydrophobizing agent is added.
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 preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less with respect to the silica particles, from the viewpoint of controlling the value of (B) / (A) to the above range. The mass% is more preferably 10% by mass or more and 30% by mass or less.

  As a method of obtaining the hydrophobic silica particles of the powder, a method of obtaining a hydrophobic silica particle powder after obtaining a hydrophobic silica particle dispersion, and drying the silica particle dispersion to obtain hydrophilic silica particles After obtaining a powder of the above, a method of obtaining a hydrophobic silica particle powder by adding a hydrophobizing agent and applying a hydrophobic treatment, a hydrophobic silica particle dispersion, and then drying to obtain a hydrophobic silica particle And a method of obtaining a powder of hydrophobic silica particles by adding a hydrophobizing agent and applying a hydrophobizing treatment.

In order to control the moisture content (A) of the silica particles and the amount of OH groups on the surface of the silica particles, the silica particle dispersion is dried to obtain a hydrophilic silica particle powder, and then a hydrophobizing agent. More preferred is a method in which a hydrophobization treatment is carried out to obtain a powder of hydrophobic silica particles.
The moisture content (A) is controlled by storing the powder of hydrophilic silica particles in a constant temperature and humidity environment for a certain period of time.

  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.

In addition, when hydrophobizing silica powder particles, the method of adding the hydrophobizing agent to the silica particles is not limited to adding the hydrophobizing agent all at once. And the like.
In particular, when an excessive amount of treatment is added at once as a method of adding a hydrophobizing agent, the silica is agglomerated, resulting in a non-uniform hydrophobization state on the surface of the particle, and the OH group on the surface of the silica particle. The amount tends to increase. On the other hand, when the treatment agent is added stepwise as a method of adding the hydrophobic treatment agent, the surface of the particles is uniformly treated, and the amount of OH groups on the surface of the silica particles tends to be reduced.

  As described above, specific silica particles that have been hydrophobized are obtained.

  In the toner according to the exemplary embodiment, the addition amount of the specific silica particles with respect to the total toner particles is preferably 1% by mass or more and 15% by mass or less, and more preferably 2% by mass or more and 10% by mass or less.

(Toner particles)
The toner particles include, for example, a binder resin and, if necessary, a colorant, a release agent, and other additives.

-Binder resin-
Examples of the binder resin include styrenes (eg, styrene, parachlorostyrene, α-methylstyrene, etc.), (meth) acrylic acid esters (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (for example, acrylonitrile, Methacrylonitrile, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, etc.) Emissions include monomers homopolymer, or a vinyl resin comprising these monomers from the two or more combined copolymers of butadiene) and the like.
As the binder resin, for example, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, non-vinyl resin such as modified rosin, a mixture of these with the vinyl resin, or these Examples also include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence.
These binder resins may be used alone or in combination of two or more.

A polyester resin is suitable as the binder resin.
Examples of the polyester resin include known polyester resins.

  As a polyester resin, the condensation polymer of polyhydric carboxylic acid and polyhydric alcohol is mentioned, for example. In addition, as an amorphous polyester resin, a commercial item may be used and what was synthesize | combined may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.) Alicyclic dicarboxylic acids (for example, cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (for example, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or lower (for example, having 1 or more carbon atoms) 5 or less) alkyl esters. Among these, as polyvalent carboxylic acid, aromatic dicarboxylic acid is preferable, for example.
The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid or a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, having 1 to 5 carbon atoms) alkyl esters.
Polyvalent carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Examples of the polyhydric alcohol include aliphatic diols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (for example, cyclohexanediol, cyclohexanedimethanol, Hydrogenated bisphenol A, etc.) and aromatic diols (for example, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, as the polyhydric alcohol, for example, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.
As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
A polyhydric alcohol may be used individually by 1 type, and may use 2 or more types together.

The glass transition temperature (Tg) of the polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, described in the method for determining the glass transition temperature in JIS K-1987 “Method for Measuring Transition Temperature of Plastics”. It is determined by “extrapolated glass transition start temperature”.

The weight average molecular weight (Mw) of the polyester resin is preferably from 5,000 to 1,000,000, more preferably from 7,000 to 500,000.
The number average molecular weight (Mn) of the polyester resin is preferably from 2,000 to 100,000.
The molecular weight distribution Mw / Mn of the polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed with a THF solvent using a Tosoh GPC / HLC-8120 as a measuring device and a Tosoh column / TSKgel Super HM-M (15 cm). The weight average molecular weight and number average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample.

The polyester resin can be produced by a known production method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure in the reaction system is reduced as necessary, and the reaction is performed while removing water and alcohol generated during the condensation.
When the raw material monomer is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added as a solubilizer and dissolved. In this case, the polycondensation reaction is performed while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, the monomer with poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance before the polymerization with the main component. It is good to condense.

  The content of the binder resin is, for example, preferably 40% by mass to 95% by mass, more preferably 50% by mass to 90% by mass, and more preferably 60% by mass to 85% by mass with respect to the entire toner particles. Further preferred.

-Colorant-
Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliantamine 3B, brilliant. Carmine 6B, Dupont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, or acridine, xanthene, azo Various dyes such as benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazole, etc. Is mentioned.
A colorant may be used individually by 1 type and may use 2 or more types together.

  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.

  The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Release agent-
Examples of the release agent 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. The release agent is not limited to this.

The melting temperature of the release agent is preferably 50 ° C. or higher and 110 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower.
The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) according to the “melting peak temperature” described in JIS K-1987 “Method for measuring the transition temperature of plastics”.

  The content of the release agent is, for example, preferably 1% by mass to 20% by mass and more preferably 5% by mass to 15% by mass with respect to the entire toner particles.

-Other additives-
Examples of other additives include known additives such as a magnetic material, a charge control agent, and inorganic powder. These additives are contained in the toner particles as internal additives.

-Toner particle characteristics-
The toner particles may be toner particles having a single layer structure, or toner particles having a so-called core / shell structure composed of a core (core particle) and a coating layer (shell layer) covering the core. May be.
Here, the core / shell structure toner particles include, for example, a core portion including a binder resin and, if necessary, other additives such as a colorant and a release agent, and a binder resin. It is good to be comprised with the comprised coating layer.

  The volume average particle diameter (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

The various average particle diameters and various particle size distribution indexes of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman-Coulter), and the electrolyte is measured using ISOTON-II (manufactured by Beckman-Coulter). The
In the measurement, 0.5 mg to 50 mg of a measurement sample is added as a dispersant to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate). This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolyte in which the sample is suspended is dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm to 60 μm is measured using a 100 μm aperture with a Coulter Multisizer II. taking measurement. The number of particles to be sampled is 50,000.
A cumulative distribution is drawn from the smaller diameter side to the particle size range (channel) divided based on the measured particle size distribution, and the cumulative particle size of 16% is the volume particle size D16v. D16p, a particle size that is 50% cumulative is defined as a volume average particle size D50v, a cumulative number average particle size D50p, and a particle size that is 84% cumulative is defined as a volume particle size D84v and a number particle size D84p.
Using these, the volume average particle size distribution index (GSDv) is calculated as (D84v / D16v) ^1/2 and the number average particle size distribution index (GSDp) is calculated as (D84p / D16p) ^1/2 .

  The shape factor SF1 of the toner particles is preferably 110 or more and 150 or less, and more preferably 120 or more and 140 or less.

The shape factor SF1 is obtained by the following formula.
Formula: SF1 = (ML ² / A) × (π / 4) × 100
In the above formula, ML represents the absolute maximum length of the toner, and A represents the projected area of the toner.
Specifically, the shape factor SF1 is quantified mainly by analyzing a microscope image or a scanning electron microscope (SEM) image using an image analyzer, and is calculated as follows. That is, by capturing an optical microscope image of particles dispersed on the surface of a slide glass into a Luzex image analyzer using a video camera, obtaining the maximum length and projected area of 100 particles, calculating by the above formula, and obtaining the average value can get.

(External additive)
In the toner according to the exemplary embodiment, at least the specific silica particles described above are externally added to the toner particles. Further, other external additives may be used in combination.

Examples of the external additive include inorganic particles. As the inorganic particles, SiO ₂ , TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , CeO ₂ , Fe ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na ₂ O, ZrO ₂ , CaO. _{SiO 2, K 2 O · (} TiO 2) n, Al 2 O 3 · 2SiO 2, CaCO 3, MgCO 3, BaSO 4, MgSO 4 , and the like.

The surface of the inorganic particles as an external additive is preferably subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing inorganic particles in a hydrophobic treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents and the like. These may be used individually by 1 type and may use 2 or more types together.
The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass with respect to 100 parts by mass of the inorganic particles.

  Examples of external additives include resin particles (resin particles such as polystyrene, PMMA, and melamine resin), cleaning activators (for example, metal salts of higher fatty acids typified by zinc stearate, particles of a fluorine-based high molecular weight substance), and the like. Can be mentioned.

  The external addition amount of the external additive is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less with respect to the toner particles.

(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 an external additive to the toner particles after the toner particles are manufactured.

The toner particles may be produced by any of a dry production method (for example, a kneading and pulverizing method) and a wet production method (for example, an aggregation coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). The production method of the toner particles is not particularly limited, and a known production method is adopted.
Among these, it is preferable to obtain toner particles by an aggregation and coalescence method.

Specifically, for example, when toner particles are produced by an aggregation coalescence method,
A step of preparing a resin particle dispersion in which resin particles to be a binder resin are dispersed (resin particle dispersion preparation step), and a resin particle dispersion (after mixing other particle dispersions as necessary) In the dispersion), the resin particles (other particles as necessary) are aggregated to form aggregated particles (aggregated particle formation step), and the aggregated particle dispersion in which the aggregated particles are dispersed is heated. Then, toner particles are manufactured through a process of fusing and coalescing the aggregated particles to form toner particles (fusing and coalescing process).

Details of each step will be described below.
In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described. The colorant and the release agent are used as necessary. Of course, you may use other additives other than a coloring agent and a mold release agent.

-Preparation step of resin particle dispersion-
First, together with a resin particle dispersion in which resin particles to be a binder resin are dispersed, for example, a colorant particle dispersion in which colorant particles are dispersed and a release agent dispersion in which release agent particles are dispersed are prepared. .

  Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

Examples of the dispersion medium used for the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together.

Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an anionic surfactant and a cationic surfactant are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
Surfactant may be used individually by 1 type and may use 2 or more types together.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion include general dispersion methods such as a rotary shear type homogenizer, a ball mill having media, a sand mill, and a dyno mill. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method.
The phase inversion emulsification method is a method in which a resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to the organic continuous phase (O phase) to neutralize the aqueous medium. (W phase) is added to convert the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase and disperse the resin in an aqueous medium in the form of particles. It is.

The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less. .
The volume average particle size of the resin particles is divided into particle size ranges (channels) using a particle size distribution obtained by measurement with a laser diffraction particle size distribution measuring apparatus (for example, LA-700 manufactured by Horiba, Ltd.). On the other hand, the cumulative distribution is drawn from the small particle diameter side with respect to the volume, and the particle diameter that becomes 50% cumulative with respect to all the particles is measured as the volume average particle diameter D50p. The volume average particle size of particles in other dispersions is also measured in the same manner.

  As content of the resin particle contained in a resin particle dispersion liquid, 5 to 50 mass% is preferable, for example, and 10 to 40 mass% is more preferable.

  In addition, similarly to resin particle dispersion, for example, a colorant dispersion and a release agent dispersion are also prepared. In other words, regarding the volume average particle size of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the content of the particles, the colorant particles dispersed in the colorant dispersion and the release agent dispersed in the release agent dispersion are used. The same applies to the mold agent particles.

-Aggregated particle formation process-
Next, the colorant particle dispersion and the release agent dispersion are mixed together with the resin particle dispersion.
Then, in the mixed dispersion, resin particles, colorant particles, and release agent particles are hetero-aggregated to have resin particles, colorant particles, and release agent particles having a diameter close to the diameter of the target toner particles. Aggregated particles are formed.

Specifically, for example, the flocculant is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. The resin particles are heated to a glass transition temperature (specifically, for example, the glass transition temperature of the resin particles −30 ° C. or more and the glass transition temperature −10 ° C. or less), and the particles dispersed in the mixed dispersion liquid are aggregated. , Forming aggregated particles.
In the agglomerated particle forming step, for example, the aggregating agent is added at room temperature (for example, 25 ° C.) while stirring the mixed dispersion with a rotary shearing homogenizer, and the pH of the mixed dispersion is acidic (for example, the pH is 2 or more and 5 or less). ), And after adding a dispersion stabilizer as necessary, the heating may be performed.

Examples of the flocculant include surfactants having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, for example, inorganic metal salts and divalent or higher-valent metal complexes. In particular, when a metal complex is used as the flocculant, the amount of the surfactant used is reduced, and the charging characteristics are improved.
If necessary, an additive that forms a complex or a similar bond with the metal ion of the flocculant may be used. As this additive, a chelating agent is preferably used.

Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and inorganic substances such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include metal salt polymers.
A water-soluble chelating agent may be used as the chelating agent. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), and the like.
As addition amount of a chelating agent, 0.01 mass part or more and 5.0 mass part or less are preferable with respect to 100 mass parts of resin particles, for example, and 0.1 mass part or more and less than 3.0 mass parts are more preferable.

-Fusion / unification process-
Next, the aggregated particle dispersion in which the aggregated particles are dispersed is heated to, for example, a glass transition temperature or higher of the resin particles (for example, a temperature of 10 to 30 ° C. higher than the glass transition temperature of the resin particles). Are fused and united to form toner particles.

Through the above steps, toner particles are obtained.
In addition, after obtaining the aggregated particle dispersion liquid in which the aggregated particles are dispersed, the aggregated particle dispersion liquid and the resin particle dispersion liquid in which the resin particles are dispersed are further mixed, and the resin particles are further added to the surface of the aggregated particles. A process of aggregating to adhere to form second aggregated particles, and heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles. The toner particles may be manufactured through a step of forming toner particles having a core / shell structure.

Here, after completion of the fusion / unification process, toner particles formed in the solution are dried through a known washing process, solid-liquid separation process, and drying process to obtain toner particles.
In the washing step, it is preferable to sufficiently carry out substitution washing with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, etc. are preferably performed from the viewpoint of productivity. Also, the drying process is not particularly limited, but from the viewpoint of productivity, freeze drying, flash jet drying, fluidized drying, vibration fluidized drying, or the like is preferably performed.

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

<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 coated carrier in which the surface of a core material made of magnetic powder is coated with a coating resin; a magnetic powder-dispersed carrier in which magnetic powder is dispersed and blended in a matrix resin; and a resin in porous magnetic powder. And a resin-dispersed carrier in which conductive particles are dispersed and blended in a matrix resin.
The magnetic powder-dispersed carrier, the resin-impregnated carrier, and the conductive particle-dispersed carrier may be carriers in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

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

  Examples of the conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

Examples of the coating resin and the matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid copolymer. Examples thereof include a polymer, a straight silicone resin containing an organosiloxane bond or a modified product thereof, a fluororesin, a polyester, a polycarbonate, a phenol resin, and an epoxy resin.
Note that the coating resin and the matrix resin may contain other additives such as a conductive material.

Here, in order to coat the surface of the core material with the coating resin, a method of coating with a coating resin and a coating layer forming solution in which various additives are dissolved in an appropriate solvent as necessary may be mentioned. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, coating suitability, and the like.
Specific resin coating methods include a dipping method in which the core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the core material, and a state in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed, a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater, and the solvent is removed.

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

<Image Forming Apparatus / Image Forming Method>
The image forming apparatus / image forming method according to the present 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 image forming unit that forms an electrostatic image on the surface of the charged image carrier, and an electrostatic charge. Development means for containing an image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer, and the toner image formed on the surface of the image carrier as a recording medium Transfer means for transferring to the surface of the recording medium, and fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic charge image developer according to this embodiment is applied as the electrostatic charge image developer.

  In the image forming apparatus according to this embodiment, a charging process for charging the surface of the image carrier, an electrostatic charge image forming process for forming an electrostatic image on the surface of the charged image carrier, and an electrostatic charge according to this embodiment. A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with an image developer; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of the recording medium; An image forming method (an image forming method according to the present embodiment) including a fixing step of fixing the toner image transferred onto the surface of the recording medium is performed.

The image forming apparatus according to the present embodiment includes a direct transfer type apparatus that directly transfers a toner image formed on the surface of the image holding member to a recording medium; and an intermediate transfer member that transfers the toner image formed on the surface of the image holding member. An intermediate transfer type apparatus that primarily transfers the toner image transferred to the surface of the intermediate transfer member and secondarily transfers the toner image transferred to the surface of the intermediate transfer member to the surface of the recording medium; and the surface of the image carrier before charging after transferring the toner image. A known image forming apparatus such as an apparatus provided with a cleaning means for cleaning; an apparatus provided with a charge eliminating means for irradiating the surface of the image holding member with a charge removing light before charging after transferring the toner image is applied.
In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred to the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body. And a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of 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 (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge that accommodates the electrostatic charge image developer according to this embodiment and includes a developing unit 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 illustrating an image forming apparatus according to the present embodiment.
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 arranged in parallel at a predetermined distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from 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 drive roll 22 and a support roll 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 roll 24 is applied with a force in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the support roll 24. 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 drive roll 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 is supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 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 photoreceptor 1Y, a charging roll (an example of a charging unit) 2Y for charging the surface of the photoreceptor 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on a color-separated image signal. Then, an exposure device (an example of an electrostatic image forming unit) 3 that forms an electrostatic image, and a developing device (an example of a developing unit) 4Y that develops the electrostatic image by supplying toner charged to the electrostatic image, developed A primary transfer roll 5Y (an example of a primary transfer unit) that transfers a toner image onto the intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning unit) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer. Are arranged in order.
The primary transfer roll 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 rolls 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roll 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 operation, the surface of the photoreceptor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (for example, volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (general resin resistance), 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 having a yellow image 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 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) as a toner image by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge image developer containing 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 electric charge on the photoreceptor 1Y, and has a developer roll (a developer holding member). Example) 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 roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y is applied to the toner image, so that the photoreceptor is exposed. The toner image on 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the polarity (−) of the toner, and is controlled to +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 photoreceptor cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled in accordance with 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 on which the four color toner images are transferred in multiple ways through the first to fourth units is disposed on the image transfer surface side of the intermediate transfer belt 20, the support roll 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roll (an example of a secondary transfer unit) 26 is formed to a secondary transfer portion configured. On the other hand, recording paper (an example of a recording medium) P is fed at a predetermined timing into a gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact with each other via a supply mechanism, and the secondary transfer bias is supplied to the support roll. 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, so 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 into the pressure contact portions (nip portions) of a pair of fixing rolls in a fixing device (an example of a fixing unit) 28, and the toner image is fixed on the recording paper P to form a fixed image.

Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, and the like. In addition to the recording paper P, the recording medium may be an OHP sheet.
In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is also preferably smooth. For example, coated paper with the surface of plain paper coated with resin, art paper for printing, etc. are preferably used. Is done.

  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.

<Process cartridge / toner cartridge>
The process cartridge according to this embodiment will be described.
The process cartridge according to the present embodiment accommodates the electrostatic image developer according to the present embodiment, and develops the electrostatic image formed on the surface of the image carrier as a toner image by the electrostatic image developer. And a process cartridge that can be attached to and detached from the image forming apparatus.

  Note that the process cartridge according to the present embodiment is not limited to the above-described configuration, and other devices such as a developing device and other units such as an image carrier, a charging unit, an electrostatic charge image forming unit, and a transfer unit, if necessary. And at least one selected from the above.

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

FIG. 2 is a schematic configuration diagram showing a process cartridge according to the present embodiment.
The process cartridge 200 shown in FIG. 2 is provided around the photoconductor 107 and the photoconductor 107 by, for example, a housing 117 provided with an attachment rail 116 and an opening 118 for exposure. The charged roll 108 (an example of a charging unit), a developing device 111 (an example of a developing unit), and a photosensitive member cleaning device 113 (an example of a cleaning unit) are integrally combined and held to form a cartridge. Yes.
In FIG. 2, 109 is an exposure device (an example of an electrostatic charge image forming unit), 112 is a transfer device (an example of a transfer unit), 115 is a fixing device (an example of a fixing unit), and 300 is a recording paper (a recording medium). An example).

Next, the toner cartridge according to this embodiment will be described.
The toner cartridge according to the present exemplary embodiment is a toner cartridge that accommodates the toner according to the present exemplary embodiment and is detachable from the image forming apparatus. The toner cartridge contains toner for replenishment to be supplied to the developing means provided in the image forming apparatus.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K are attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are each developing devices (colors). 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, although an Example and a comparative example are given and this embodiment is described in detail more concretely, this embodiment is not limited to these Examples at all. “Parts” and “%” are based on mass unless otherwise specified.

Example 1
[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-β-carboxyethyl acrylate (Rhodia Nikka): 9 parts-1'10-decanediol diacrylate ( Shin-Nakamura Chemical Co., Ltd.): 1.5 parts · Dodecanethiol (Wako Pure Chemical Industries, Ltd.): 2.7 parts Ion 4 parts of the anionic surfactant Dowfax (Dow Chemical Co., Ltd.) is dissolved in the above components. A solution dissolved in 550 parts of exchange water was added, dispersed and emulsified in a flask, and slowly stirred and mixed for 10 minutes, and then 50 parts of ion exchange 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-β-carboxyethyl acrylate (Rhodia Nikka): 9 parts A solution obtained by dissolving 1.5 parts of a surfactant, Dow Fax (manufactured by Dow Chemical Co., Ltd.), in 550 parts of ion-exchanged water is added to the dispersion and emulsified in a flask. The mixture is further stirred and mixed for 10 minutes. 50 parts of ion-exchanged water in which 4 parts were 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: Newlex R): 2 parts, ion-exchanged water: 220 parts The above ingredients are mixed, and 10 minutes with a homogenizer (IKA Ultra Turrax) After pre-dispersion, a dispersion treatment is performed for 15 minutes at a pressure of 245 Mpa using an optimizer (counter-impact type wet pulverizer: Sugino Machine), a colorant having a colorant particle center particle size of 169 nm and a solid content of 22.0%. A 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 mixed and dispersed solution was obtained using Tulax 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 diameter of 4.5 μm.

[Production of silica particles (sol-gel method)]
(Granulation process)
-Alkali catalyst solution preparation step [Preparation of alkali catalyst solution]-
300 parts of methanol and 49.5 parts of 10% ammonia water are placed in a 3 L glass reaction vessel having a metal stirring bar, dropping nozzle (Teflon (registered trademark) micro tube pump), and thermometer, and mixed by stirring. As a result, an alkali catalyst solution was obtained.

-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. Thereafter, while stirring the alkali catalyst solution, 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 to suspend the silica particles. A turbid liquid (silica particle suspension) was obtained.
Here, the supply amount of tetramethoxysilane was 7.6 parts / min, and the supply amount of 4.44% ammonia water was 4.5 parts / min.
When the particle | grains of the obtained silica particle suspension were measured, the volume average particle diameter (D50v) was 145 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. The obtained hydrophilic silica particles were stored (leaved) in an environment of 40 ° C. and 90% for 24 hours.

(Hydrophobicization process)
100 parts of the obtained powder of hydrophilic silica particles is put into a mixer and stirred at 200 rpm while heating to 200 ° C. in a nitrogen atmosphere, and hexamethyldisilazane (HMDS) is added to the powder of hydrophilic silica particles per hour. A total of 30 parts was dropped at a dropping rate of 10 parts, and the whole was dropped and reacted for 2 hours. Then, the powder of the hydrophobic silica particle (1) which was cooled and hydrophobized was obtained.

(Manufacture of toner)
Toner (1) was obtained by blending 100 parts of toner particles (1) with 7 parts of silica particles (1) with a Henschel mixer at a peripheral speed of 30 m / s × 15 minutes.

  The measurement results of the moisture content (A) and (B) of the silica particles (1), the calculation results of (B) / (A), the average circularity, and the measurement results of the volume average particle diameter are shown in Table 1 below.

<< Example 2 >>
In Example 1, in the production of silica particles (granulation step), the storage environment of the obtained hydrophilic silica particle powder was changed to an environment of 40 ° C. and 90% for 48 hours. Toner (2) was produced by the method described.

Example 3
In Example 1, in the production of the silica particles (granulation step), the storage environment of the obtained hydrophilic silica particle powder was changed to an environment of 40 ° C. and 65% for 24 hours. Toner (3) was produced by the method described.

Example 4
A toner (4) was produced by the method described in Example 1 except that the HMDS dropping rate in the production of silica particles (hydrophobization treatment step) was changed to 15 parts per hour in Example 1.

Example 5
In Example 1, the supply amount of tetramethoxysilane in the production of silica particles (granulation step) was changed to 3.3 parts / min, and the supply amount of 4.44% ammonia water was changed to 2.0 parts / min. A toner (5) was produced by the method described in Example 1 except that.

Example 6
A toner (6) was produced by the method described in Example 1 except that HMDS in the preparation of silica particles (hydrophobization treatment step) was changed to hexyltrimethoxysilane in Example 1.

≪Comparative example 1≫
In Example 1, the comparative toner (1) was produced by the method described in Example 1 except that the dropping speed of HMDS in the preparation of silica particles (hydrophobization treatment step) was changed to 10 parts per minute. did.

≪Comparative example 2≫
In Example 1, the comparative toner (2) was produced by the method described in Example 1 except that the dropping rate of HMDS in the preparation of silica particles (hydrophobization treatment step) was changed to 30 parts per hour. did.

«Comparative Example 3»
In Example 1, the supply amount of tetramethoxysilane in the production of silica particles (granulation step) was changed to 3.3 parts / min, and the supply amount of 4.44% ammonia water was changed to 2.0 parts / min. A comparative toner (3) was produced by the method described in Example 1 except that the dropping rate of HMDS in (hydrophobization treatment step) was changed to 60 parts per hour.

<< Comparative Example 4 >>
In Example 1, in the production of the silica particles (granulation step), the storage environment of the obtained hydrophilic silica particle powder was changed to an environment of 40 ° C. and 90% for 60 hours. A comparative toner (4) was produced by the method described.

<< Comparative Example 5 >>
In Example 1, in the production of silica particles (granulation step), the storage environment of the obtained hydrophilic silica particle powder was changed to an environment of 22 ° C. and 40% for 24 hours. A comparative toner (5) was produced by the method described.

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

In addition, the carrier produced as follows was used.
To a kneader, 1000 parts of Mn—Mg ferrite (volume average particle size: 50 μm, manufactured by Powder Tech, shape factor SF1: 120) was added, 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 prepared by dissolving 150 parts in 700 parts of toluene was added, mixed at room temperature (22 ° C.) for 20 minutes, and then heated to 70 ° C. The resulting coated carrier was 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 and Comparative Example was loaded into a developer of a Docu Print P200b remodeling machine (modified so as to increase the process speed) manufactured by Fuji Xerox Co., Ltd., and the following evaluation was performed.

First, the environment in the image forming apparatus was adjusted to a temperature of 28 ° C. and a humidity of 85%, and thereafter, 3000 images with an area coverage of 5% were output continuously. The environment in the image forming apparatus when outputting the 3000th sheet was a temperature of 44.5 ° C. and a humidity of 51.5%.
The density of 100% solid image was confirmed for the first image and the 3000th image among the 3000 images output continuously. Here, the density confirmation was measured by an image densitometer X-Rite (manufactured by X-Rite) and digitized.
Table 1 below shows the image density (a) of the first image, the image density (b) of the 3000th image, and the density difference between the image density (a) and the image density (b).
Moreover, based on the result of the density difference, evaluation was performed according to the following criteria.
A: unchanged from the initial stage ([image density (a) −image density (b)] is 0.1 or less)
○: Slightly decreased ([Image density (a) −Image density (b)] is more than 0.1 and 0.2 or less)
X: greatly reduced ([image density (a) −image density (b)] exceeds 0.2)

In addition, with respect to the first to 3000th images, a total of 30 images were checked for fogging every 100 images, and evaluated according to the following criteria. Here, the fog density was confirmed and measured by an image densitometer X-Rite (manufactured by X-Rite).
A: No fogging on all 30 sheets (Non-image area density 0.005 or less)
○: One or more slight fogging (density of non-image area exceeding 0.005 and 0.01 or less) x: One or more fogging (density of non-image area exceeding 0.01) occurred

From the above results, it can be seen that in the embodiment, the occurrence of fog is suppressed and the decrease in image density in the formed image is suppressed as compared with the comparative example.
Moreover, the moisture content (A) is 5% by mass or more and 8% by mass or less, and the relationship between the moisture content (B) and the moisture content (A) is (B) / (A) ≧ 0.93. It can be seen that Examples 1, 5, and 6 are more suppressed from lowering the image density than Examples 2 to 4.

1Y, 1M, 1C, 1K, photoconductor (an example of an image carrier)
2Y, 2M, 2C, 2K, charging roll (an example of charging means)
3. Exposure device (an example of electrostatic charge image forming means)
3Y, 3M, 3C, 3K Laser beams 4Y, 4M, 4C, 4K Developing device (an example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (an example of primary transfer means)
6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of an intermediate transfer member)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer member cleaning device 107 Photosensitive member (an example of an image holding member)
108 Charging roll (an example of charging means)
109 Exposure apparatus (an example of electrostatic charge image forming means)
111 Developing device (an example of developing means)
112 Transfer device (an example of transfer means)
113 photoconductor cleaning device (an example of cleaning means)
115 Fixing device (an example of fixing means)
116 Mounting rail 117 Housing 118 Opening 200 for exposure Process cartridge 300 Recording paper (an example of a recording medium)
P Recording paper (an example of a recording medium)

Claims (7)

Toner particles,
The moisture content (A) after being externally added to the toner particles and allowed to stand for 24 hours in an environment at a temperature of 28 ° C. and a humidity of 85% is 4% by mass to 10% by mass, and the temperature is 28 ° C. and a humidity of 85%. A sol-gel in which the relationship between the moisture content (B) and the moisture content (A) after standing for 24 hours in an environment of 45 ° C. and 50% humidity is (B) / (A) ≧ 0.9 Silica particles;
A toner for developing an electrostatic charge image.   The water content (A) is 5% by mass or more and 8% by mass or less, and the relationship between the water content (B) and the water content (A) is (B) / (A) ≧ 0.93. Item 2. The toner for developing an electrostatic charge image according to Item 1.   An electrostatic charge image developer comprising the toner for developing an electrostatic charge image according to claim 1. Containing the electrostatic image developing toner according to claim 1 or 2,
A toner cartridge to be attached to and detached from the image forming apparatus. A developing unit that contains the electrostatic charge image developer according to claim 3 and that develops the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer.
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 charged image carrier;
A developing means for containing the electrostatic charge image developer according to claim 3 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of 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 charged image carrier;
A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 3;
A transfer step of transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
A fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising:

Images