JP2011154259A - Toner for developing electrostatic charge image, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide toner for developing an electrostatic charge image of which charging does not fluctuate due to a change in temperature or humidity in an image forming device; and to provide toner for developing an electrostatic charge image and an image forming method, which are not affected by packing even when the device is stopped. <P>SOLUTION: The toner for developing an electrostatic charge image is made by adding an external additive to toner mother particles. The external additive has as a core a metal oxide selected from an amorphous titanium oxide or an amorphous aluminum oxide, the surface of the core including an amorphous silica layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention uses an electrostatic image developing toner capable of performing stable image formation without being affected by environmental fluctuations, and the electrostatic image developing toner (hereinafter sometimes simply referred to as toner). The present invention relates to an image forming method.

  In recent years, electrophotographic image forming apparatuses have been used in the field of printing, and higher image performance such as higher resolution than before has been demanded. To meet this need, small-diameter toner is used. However, in a device using a small-diameter toner, when the toner is stopped and the toner is left unattended, the density between particles increases and the fluidity tends to decrease remarkably. Have (this is called packing).

  Incidentally, as one of the methods for improving the toner transportability, there is a technique for improving an external additive using acicular titanium, titanium-containing silica, or the like (for example, see Patent Document 1).

  In addition, it has been reported that a toner to which such an external additive is added exhibits good transferability and improved image quality (for example, see Patent Document 2).

  However, these external additives have been found to be easily affected by the environment in which images are formed, and in particular, the chargeability tends to fluctuate due to the influence of temperature and humidity. As a result, it has been unavoidable that the image density fluctuates depending on the image forming environment.

  In response to this problem, Patent Document 3 proposes an external additive that has a crystallized metal oxide as a nucleus and whose surface is covered with amorphous silica, and that has little variation with respect to the influence of temperature and humidity. Yes. Although the temperature and humidity dependency was improved by this configuration, it did not meet the required level in the field of printing, and was still cited as a problem.

JP-A-6-208241 JP-A-8-44103 JP 2006-250991 A

  An object of the present invention is to provide a toner for developing an electrostatic image capable of performing stable image formation without being affected by environmental fluctuations of the image forming apparatus. That is, an object of the present invention is to provide a toner that does not fluctuate due to the influence of temperature and humidity changes in the apparatus, and is capable of developing an electrostatic charge image developing toner and an image that are not affected by packing even when the apparatus is stopped. It aims to provide a method.

  It has been found that the object of the present invention can be achieved by adopting the following configuration.

(1)
A toner for developing an electrostatic latent image in which an external additive is added to toner base particles, and the external additive has a hydrophobization degree of 55% or more, which is higher than that of amorphous titanium oxide or amorphous aluminum oxide. A toner for developing an electrostatic charge image, comprising a selected metal oxide as a nucleus and an amorphous silica layer on the surface of the nucleus.

(2)
The toner for developing an electrostatic charge image according to (1), wherein the external additive is produced by a wet method.

(3)
Using the electrostatic image developing toner described in (1) or (2), after uniformly charging the photoreceptor, a toner image is formed through image exposure and development steps, transferred to a recording material, and then fixed. An image forming method.

  According to the present invention, there is provided an electrostatic image developing toner that does not fluctuate due to changes in temperature and humidity in the image forming apparatus, and further, the electrostatic image developing toner that is not affected by packing even when the apparatus is stopped. And an image forming method.

The schematic block diagram which shows an example of the manufacturing equipment which manufactures an external additive. 1 is a cross-sectional view showing an example of an image forming apparatus used in an image forming method of the present invention.

  The present invention will be further described.

  It has been found that the toner using the external additive having the configuration of the present invention exhibits an effect of suppressing a decrease in charge amount in a low temperature and low humidity environment or a high temperature and high humidity environment.

  The reason why such an effect is exhibited by the toner using the external additive is not clear. Probably due to the internal structure of the external additive and the water absorption derived therefrom. That is, the structure covering the core and the surface is amorphous, and the above effect is manifested because the resistance is adjusted and appropriate water absorption is maintained for both low temperature and low humidity and high temperature and high humidity environments. Presumed to be.

  In the conventional method described in Patent Document 3, the temperature and humidity dependency is reduced by using a crystalline metal oxide for the core and amorphous silica for the shell. This is because the Si-OH structure in the amorphous structure of the shell shows water absorption to some extent, and the temperature-humidity dependency of water absorption is reduced compared to the case where there is no Si-OH structure as a crystal structure. Conceivable. In contrast, in the present invention, since the conventional method is further advanced and the core is made of an amorphous metal oxide and has a high degree of hydrophobicity, the temperature and humidity dependency of water absorption is further reduced, and the object can be achieved. I believe that. In other words, the Ti—OH or Al—OH structure, which is the amorphous structure of the core, the Si—OH structure, which is the amorphous structure of the shell, and the high hydrophobization of the surface show moderate water absorption. A toner having low humidity dependency can be achieved.

  Further, it is presumed that the external additive according to the present invention has improved toner fluidity due to the presence of amorphous silica on the surface and the degree of hydrophobicity of 55% or more. As a result, it is presumed that even when the toner can be packed in a state where the image forming apparatus is stopped, the fluidity of the toner is not lowered because the fluidity is improved.

  The ratio of these external additives to be added is 0.1 to 5.0% by mass, preferably 0.5 to 4.0% by mass, based on the toner base particles.

[External additive]
As described above, the external additive used in the present invention has a metal oxide selected from amorphous titanium oxide or amorphous aluminum oxide as a nucleus, and an amorphous silica layer exists on the surface of the nucleus. To do.

  The term “amorphous” as used in the present invention has the same meaning as a so-called amorphous structure.

<Number average primary particle size of external additives>
The number average primary particle diameter of the external additive is preferably 35 to 500 nm, more preferably 40 to 300 nm, from the viewpoint of stabilizing the charge on the toner surface and keeping the external additive itself more stably on the toner base surface. .

  The number average primary particle diameter is measured by the following method.

  Specifically, the toner surface was photographed with a scanning electron microscope at a magnification of 50,000 times, the horizontal ferret diameter was measured for 100 external additives on this photographic image, and the average value was calculated. The horizontal ferret diameter is the distance between two vertical lines sandwiched between two vertical lines that sandwich an external additive on a photographic image. When the number of external additives to be measured with one toner particle is insufficient, the number of toner particles to be observed is increased. Also, photographic images are captured by a scanner, binarized for external additives present on the toner surface by an image processing analyzer LUZEX AP (manufactured by Nireco), and the horizontal ferret diameter is measured for 100 external additives. You can also

  When the external additive is present on the toner surface as an aggregate, the particle diameter of the primary particles forming the aggregate is measured.

  It is also possible to photograph the external additive directly with a scanning electron microscope and calculate the number average primary particle size from the photograph image by the same procedure.

  Next, a method for confirming the structure of the external additive will be described.

<Confirmation that the external additive is amorphous>
The external additive is collected on a grid mesh bonded with a microgrid and is transmitted through a transmission electron microscope (TEM), preferably a high resolution transmission electron microscope (HR-TEM), for example, a field emission transmission electron microscope (FE). -TEM) is used to observe the transmission image.

  When the external additive contains a crystal, that is, a crystal structure, the electron beam transmitted through the sample is divided into a transmitted wave and a diffracted wave. By observing the interference image between the transmitted wave and the diffracted wave, a lattice image reflecting the crystallinity of the sample can be observed. However, when the external additive is amorphous, the lattice image is not observed.

  The composition can be analyzed by detecting with an energy dispersive X-ray analyzer (EDS) attached to the TEM.

  In the case of the external additive used in the present invention, as a result of observation using the above-mentioned FE-TEM (acceleration voltage: set to 200 kV), no lattice image is observed on the particles, and the particles are amorphous. It was confirmed.

(Measuring method)
The toner containing the external additive is preferably collected on a grid mesh with a microgrid made of carbon, and is transmitted through a transmission electron microscope (TEM), preferably a high resolution transmission electron microscope (HR-TEM), such as a field emission transmission. A transmission image is observed with an electron microscope (FE-TEM). By focusing on the external additive in the contour of the toner, the structure and composition of the external additive can be clarified.

(Measurement condition)
A dispersion in which toner is dispersed in pure water is dropped onto a grid mesh with a microgrid and dried to prepare an observation sample.

  Thereafter, the structure and composition are evaluated by FE-TEM “JEM-2010F” (manufactured by JEOL Ltd.) and energy dispersive X-ray analyzer (EDS) “Voager” (manufactured by ThermoNORAN).

  The conditions are set as follows.

Accelerating voltage: 200kV
TEM image observation magnification: 50,000 to 500,000 times EDS measurement time (Live time): 50 seconds Measurement energy range: 0 to 2,000 eV
<Silica surface abundance ratio>
The external additive has amorphous silica on the surface, but the amorphous silica does not necessarily need to completely cover the metal oxide. A structure in which 1 to 70% of silica is detected by mass ratio when the surface abundance ratio of silica is measured by electron spectroscopy (ESCA) is preferable, and a structure in which 1 to 45% is detected is more preferable. That is, in the composition of silica and titanium oxide or alumina, a structure in which the surface abundance ratio of titanium oxide or alumina by ESCA is detected in the range of 30 to 99% by mass ratio is desirable.

<Specific surface area of external additive>
The specific surface area of the external additive is preferably ² to 100 m ² / g as a BET value. This BET specific surface area is measured by a nitrogen gas adsorption method, and is specifically a value by a one-point method measured by “Flowsorb 2300” (manufactured by Shimadzu Corporation).

<Measurement of hydrophobicity>
The degree of hydrophobicity was measured by methanol wettability. Methanol wettability is an evaluation of wettability to methanol. In this method, 0.2 g of inorganic fine particles to be measured is weighed and added to 50 ml of distilled water in a 200 ml beaker. Methanol is slowly added dropwise from a burette, the tip of which is immersed in a liquid, with slow stirring until the entire inorganic fine particles are wet. When the amount of methanol necessary to completely wet the inorganic fine particles is a (ml), the degree of hydrophobicity is calculated by the following formula 1.
(Formula 1) Degree of hydrophobicity = {a / (a + 50)} × 100
[Method for producing external additive]
The external additive used in the present invention can be produced by either a gas phase method or a wet method.

  Next, production equipment for producing the external additive used in the present invention will be described in detail, but the present invention is not limited to this.

  FIG. 1 is a schematic view showing an example of a production facility for producing an external additive used in the present invention.

  This apparatus is preferably used for producing the external additive by supplying the raw material of the external additive to the burner in the form of steam or powder and oxidizing it in a flame.

  In FIG. 1, 210 is a powder (A), 220 is a powder (A) tank, 230 is a powder (A) constant supply pump, 250 is a powder (A) introduction tube, 211 is a particle (B) ) 221 is a particle (B) tank, 231 is a particle (B) metering pump, 251 is a particle (B) introduction pipe, 261 is an oxygen / water vapor mixed gas introduction pipe, and 262 is an oxygen / water vapor mixed gas. 263 is an oxygen / steam mixed gas tank, 260 is a main burner, 270 is a combustion furnace (reaction tube), 280 is a combustion flame, 290 is a flue, 300 is a cyclone, 320 is a bag filter, 310 and 330 are collectors, 340 Indicates an exhaust fan.

  In FIG. 1, powder (A) 210 and particles (B) 211 are fed from a tank of powder (A) and particles (B) to a main burner 260 having a spray nozzle attached to the tip through a raw material introduction pipe by a constant supply pump. Led. The powder (A) and the particles (B) are sprayed into the combustion furnace 270 together with a mixed gas of oxygen and water vapor, and ignited by an auxiliary flame, whereby a combustion flame 280 is formed. The external additive produced by the combustion is cooled by the flue 290 together with the exhaust gas, separated by the cyclone 300 and the bag filter 320, and collected by the collectors 310 and 330. The exhaust gas is exhausted by the exhaust fan 340.

  The powder (A) and the particles (B) may be mixed in advance as raw materials, and the mixed raw materials may be sprayed into the combustion furnace together with a mixed gas of oxygen and water vapor.

<Method for producing external additive by vapor phase method>
For example, a method in which the powder (A) and the particles (B) are introduced into a high-temperature flame and the surface of the particles (B) is modified with the powder (A) can be mentioned. In the present invention, the powder (A) is an amorphous silica powder, and the particles (B) are a metal oxide selected from amorphous titanic acid or an amorphous aluminum compound. Preferably, the particle (B) adheres and coalesces around the particle (B) by making the particle (B) particle size larger than the particle size of the powder (A). It is preferable that the powder (A) is fused and fused to the surface of the particle (B) by heat so that the prototype of the powder (A) cannot be observed on the surface of the particle (B).

  In this case, it is considered that when the particles (B) and the powder (A) are simultaneously introduced into the flame, the surface of the particles (B) is modified by the powder (A). More preferably, the timing of introduction into the flame is preceded by the particles (B), and after the crystals have grown, the powder (A) is introduced into the flame with a delay, which is preferable in terms of production stability.

  Usually, in a high-temperature flame, a plurality of particles associate and grow to grow into particles having a large diameter. Here, the particles (B) and the powder (A) are introduced into the same high temperature zone, but if the powder (A) is finer, the heat receiving area is larger and it is considered that the powder (A) is more easily melted. Therefore, for example, by controlling the combustion amount of the combustible gas, the association / growth of the particles (B) is suppressed, and the conditions for the powder (A) to melt and adhere to the particles (B) are found without special trial and error. be able to.

  It is clear that the external additive according to the present invention can be obtained when the powder (A) associates / collises with the particle (B) and adheres / fuses, but even if the powder (A) is fused, There is a high probability that the particles will collide and combine with the particles (B) before they grow sufficiently. This is thought to be because small particles are much easier to move than large particles in an air stream. The external additive according to the present invention can be obtained as long as the powder (A) thus associated and grown collides and fuses with the particles (B) and satisfies the predetermined composition ratio.

  In this method, the powder (A) subjected to the flame treatment adheres to the surface of the particle (B), so that the powder (A) is present on the surface of the particle (B). Even if the materials of (B) and the powder (A) are the same, those having different particle diameters, specific surface areas, and composition ratios can be produced depending on the flame treatment conditions.

  Here, it is possible to use titanium oxide particles, aluminum oxide particles, or mixed crystal particles thereof in an amorphous state as the particles (B).

  The amorphous silica used as the powder (A) is obtained by using a production apparatus shown in FIG. 1 below, and using silicon halide or an organic silicon compound in a flame in which hydrocarbon gas such as propane gas or methane gas is burned. Those obtained by burning are preferably used.

  The non-crystallized metal oxide to be particles (B) is obtained by burning the metal oxide raw material in a flame of hydrocarbon gas such as propane gas or methane gas using the production apparatus shown in FIG. Titanium oxide, aluminum oxide, or a mixed crystal thereof in a crystalline state is preferable. As mentioned above, although the manufacturing method by compounding between powder was shown, it is not limited to this. In addition, a method of shifting the ejection timing of the source gas can be mentioned.

  As raw materials for metal oxides, titanium sulfate, titanium tetrachloride and the like can be used as the titanium source, and aluminum chloride, aluminum sulfate, sodium aluminate and the like can be used alone or in combination in any combination as the aluminum source.

  The amorphous silica used as the powder (A) is produced by burning silicon halide or an organic silicon compound in a flame in which hydrocarbon gas such as propane gas or methane gas is burned using the production apparatus shown in FIG. Those obtained are preferably used.

<Method for producing external additive by wet method>
For example, it is a tetrafunctional silane compound represented by the following general formula (1) or a partial hydrolysis-condensation product thereof, or a combination thereof.

General formula (1) X (OR ¹ ) ₄
(In the formula, X is composed of titanium, aluminum and silica, and R ¹ is the same or different and is a monovalent hydrocarbon group having 1 to 6 carbon atoms.)
The above compound is hydrolyzed and condensed in a mixed liquid of a hydrophilic organic solvent containing a basic substance and water to produce fine particles.

  The fine particles are usually obtained as a mixed solvent dispersion of a water-hydrophilic organic solvent. As will be described later, the fine particle aqueous dispersion can be prepared by converting the dispersion medium of the fine particle mixed solvent dispersion into water as necessary.

In the general formula (1), R ¹ is preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms.

Examples of the monovalent hydrocarbon group represented by R ¹ include a methyl group, an ethyl group, a propyl group, a butyl group, and a phenyl group, preferably a methyl group, an ethyl group, a propyl group, and a butyl group, and particularly preferably , Methyl group, and ethyl group.

  The hydrophilic organic solvent is not particularly limited as long as it dissolves the tetrafunctional silane compound represented by the general formula (1), a partial hydrolysis-condensation product thereof, and water. Alcohol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, cellosolve such as acetic acid cellosolve, ketones such as acetone and methyl ethyl ketone, ethers such as dioxane and tetrahydrofuran, and the like. Preferred are alcohols and cellosolves, and particularly preferred are alcohols.

  Examples of alcohols include alcohols represented by the following general formula (2).

Formula (2) R ² OH
(In the formula, R ² is a monovalent hydrocarbon group having 1 to 6 carbon atoms.)
In the general formula (2), R ² is preferably a monovalent hydrocarbon group having 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms. Examples of the monovalent hydrocarbon group represented by R ² include an alkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group, preferably a methyl group, an ethyl group, a propyl group, an isopropyl group, More preferably, a methyl group and an ethyl group are mentioned.

  As the number of carbon atoms in the alcohol increases, the particle size of the generated fine particles increases. Therefore, it is desirable to select the type of alcohol according to the particle size of the target fine particles.

  Examples of the basic substance include ammonia, dimethylamine, diethylamine and the like, preferably ammonia, diethylamine, and particularly preferably ammonia. These basic substances may be dissolved in water in a required amount, and the obtained aqueous solution (basic) may be mixed with the hydrophilic organic solvent.

  The amount of water used at this time is 0.5 to 5 with respect to a total of 1 mol of the hydrocarbyloxy group of the tetrafunctional compound represented by the general formula (1) and / or the partial hydrolysis-condensation product thereof. Mole is preferable, 0.6 to 2 mol is more preferable, and 0.7 to 1 mol is particularly preferable. The ratio of the hydrophilic organic solvent to water is preferably 0.5 to 10 by mass ratio, more preferably 1 to 5, and particularly preferably 1.5 to 2. The amount of the basic substance is 0.01 to 2 mol with respect to a total of 1 mol of the tetrafunctional compound represented by the general formula (1) and / or the hydrocarbyloxy group of the partially hydrolyzed condensation product thereof. It is preferably 0.5 to 1.5 mol, more preferably 1.0 to 1.2 mol.

  Hydrolysis and condensation of the tetrafunctional compound represented by the general formula (1) and / or a partial hydrolysis-condensation product thereof can be performed by a well-known method, that is, a hydrophilic organic solvent containing a basic substance and water. It is carried out by adding the tetrafunctional compound represented by the above general formula (1) and / or a partial hydrolysis condensation product thereof to the mixture, and X in the above general formula (1) is represented by titania or aluminum. When the compound obtained is hydrolyzed and condensed, and the reaction product disappears, the compound represented by the general formula (1) where X is represented by silica is added, hydrolyzed, and condensed, whereby titanium or aluminum An external additive having an oxidized compound as a nucleus and the surface thereof covered with silica can be obtained.

  The step of converting the dispersion medium of the fine particle mixed solution dispersion to water performed as necessary is, for example, an operation of adding water to the dispersion and distilling off the hydrophilic organic solvent (repeating this operation as necessary) ). The amount of water added at this time is preferably 0.5 to 2 times, more preferably 0.7 to, on a mass basis with respect to the total amount of the used hydrophilic organic solvent and the generated alcohol. 1.2-fold amount, particularly preferably about 1-fold amount.

[Method for producing toner base particles]
The toner base particles in the present invention mean toner particles before adding an external additive.

  The method for producing the toner of the present invention is not particularly limited, and may be a pulverization method or a polymerization method. However, a toner manufacturing method using an emulsion association method, which is a kind of polymerization method, is preferably used. In particular, a toner manufacturing method in which resin particles that are subjected to multistage polymerization by a miniemulsion polymerization method are associated (aggregated / fused) is preferable.

  Next, an example of a toner production method by the miniemulsion polymerization association method will be described in detail. This toner manufacturing method is manufactured through the following steps.

(1) Dissolution / dispersion step of dissolving or dispersing the release agent in the radical polymerizable monomer (2) The polymerizable monomer solution in which the release agent is dissolved / dispersed is formed into droplets in an aqueous medium to form a mini Polymerization process for preparing a dispersion of resin particles by emulsion polymerization (3) Aggregation / fusion process for associating resin particles in an aqueous medium to obtain associated particles (4) Aging the associated particles with thermal energy to form the shape (5) Cooling step for cooling the toner base dispersion liquid (6) Solid-liquid separation of the toner base body from the cooled toner base dispersion liquid, and surfactant from the toner base body (7) Drying Step for Drying Washed Toner Base (8) Step for Adding External Additive to Dry Toner Base Each step will be described below.

(1) Dissolution / dispersion step This step is a step of preparing a radical polymerizable monomer solution of the release agent by dissolving or dispersing the release agent in the radical polymerizable monomer.

(2) Polymerization step In a preferred example of this polymerization step, a radical polymerizable monomer solution in which the release agent is dissolved or dispersed is added to an aqueous medium containing a surfactant, and mechanical energy is increased. In addition, droplets are formed, and then the polymerization reaction proceeds in the droplets by radicals from the water-soluble radical polymerization initiator. In addition, you may add the resin particle as a core particle in the said aqueous medium.

  By this polymerization step, resin particles containing a release agent and a binder resin are obtained. Such resin particles may be colored particles or non-colored particles. The colored resin particles can be obtained by polymerizing a monomer composition containing a colorant. In addition, when using non-colored resin particles, in the aggregation step described later, the dispersion of the colorant particles is added to the dispersion of the resin particles to aggregate the resin particles and the colorant particles. It can be colored particles.

(3) Aggregation / fusion process The aggregation process is a process of forming colored particles using resin particles (colored or non-colored resin particles) obtained by the polymerization process and, if necessary, colorant particles. In the aggregation step, resin particles and colorant particles can be aggregated together with release agent particles, internal additive particles such as charge control agents, and the like.

  The colorant particles can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant is performed in a state where the surfactant concentration is set to a critical micelle concentration (CMC) or more in water. The disperser used for the dispersion treatment of the colorant is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gorin or a pressure homogenizer, a sand grinder, a Getzmann mill, a diamond fine mill, or the like. Examples thereof include a medium type disperser.

  The colorant particles may be surface modified. In the surface modification method of the colorant, the colorant is dispersed in a solvent, the surface modifier is added to the dispersion, and the system is reacted by raising the temperature. After completion of the reaction, the colorant is separated by filtration, washed and filtered with the same solvent, and dried to obtain a colorant (pigment) treated with the surface modifier.

  A preferred aggregating method is to add a salting-out agent composed of an alkali metal salt, an alkaline earth metal salt, or the like as an aggregating agent having a critical aggregation concentration or more in water in which resin particles and colorant particles exist, This is a method of agglomerating at or above the glass transition point of the resin particles.

(4) Aging step Aging is preferably performed by thermal energy (heating).

  Specifically, the liquid containing the associated particles is heated and stirred to adjust the shape of the associated particles to the desired circularity by the heating temperature, the stirring speed, and the heating time to obtain toner base particles. is there.

(5) Cooling Step This step is a step of cooling (rapid cooling) the toner base dispersion. As a cooling treatment condition, cooling is performed at a cooling rate of 1 to 20 ° C./min. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel, and a method of cooling by directly introducing cold water into the reaction system.

(6) Washing Step In this solid-liquid separation / washing step, a solid-liquid separation process for solid-liquid separation of the toner base from the dispersion of the toner base that has been cooled to a predetermined temperature in the above step, and a solid-liquid separated toner A cleaning process is performed to remove deposits such as a surfactant and a salting-out agent from the cake (an aggregate obtained by agglomerating the toner base in a wet state into a cake).

  In the washing treatment, the filtrate is washed with water until the electric conductivity of the filtrate reaches 10 μS / cm. Examples of the filtration method include a centrifugal separation method, a vacuum filtration method using Nutsche and the like, and a filtration method using a filter press and the like, and are not particularly limited.

(7) Drying step This step is a step of drying the washed toner cake to obtain a dried toner base. Examples of dryers used in this process include spray dryers, vacuum freeze dryers, vacuum dryers, etc., stationary shelf dryers, mobile shelf dryers, fluidized bed dryers, rotary dryers It is preferable to use a stirring dryer or the like. The water content of the dried colored particles is preferably 5% by mass or less, more preferably 2% by mass or less.

  In addition, when the dried colored particles are aggregated by weak interparticle attractive force, the aggregate may be crushed. Here, as the crushing treatment apparatus, a mechanical crushing apparatus such as a jet mill, a Henschel mixer, a coffee mill, or a food processor can be used.

(8) External Addition Processing Step This step is a step of preparing a toner by mixing an external additive with the dried toner base as necessary.

  As an external additive mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

[Materials used for toner production]
<Binder resin>
When the toner particles constituting the toner of the present invention are produced by a pulverization method, a dissolution suspension method, or the like, a styrene resin, (meth) acrylic resin, styrene- (meta) is used as a binder resin constituting the toner. ) Known vinyl resins such as acrylic copolymer resins and olefin resins, polyester resins, polyamide resins, carbonate resins, polyethers, polyvinyl acetate resins, polysulfones, epoxy resins, polyurethane resins, urea resins, etc. These various resins can be used. These can be used alone or in combination of two or more.

  In addition, when the toner particles constituting the toner of the present invention are produced by a suspension polymerization method, a miniemulsion polymerization aggregation method, an emulsion polymerization aggregation method, or the like, a polymerizable single amount for obtaining each resin constituting the toner For example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2, Styrene such as 4-dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, or the like Styrene styrene derivatives; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, methacryl Methacrylic acid such as isopropyl, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate Ester derivatives; methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate , Acrylic ester derivatives such as phenyl acrylate; olefins such as ethylene, propylene, isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride Vinyl halides such as vinylidene fluoride; vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone Vinyl ketones such as N-vinyl carbazole, N-vinyl indole, N-vinyl compounds such as N-vinyl pyrrolidone; vinyl compounds such as vinyl naphthalene and vinyl pyridine; acrylic acid such as acrylonitrile, methacrylonitrile, acrylamide or the like Mention may be made of vinyl monomers such as methacrylic acid derivatives. These vinyl monomers can be used alone or in combination of two or more.

  Moreover, it is preferable to use combining what has an ionic dissociation group as a polymerizable monomer. The polymerizable monomer having an ionic dissociation group has, for example, a substituent such as a carboxyl group, a sulfonic acid group, and a phosphoric acid group as a constituent group, and specifically includes acrylic acid, methacrylic acid, maleic acid. Acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, styrene sulfonic acid, allyl sulfosuccinic acid, 2-acrylamido-2-methylpropane sulfonic acid, acid phosphooxyethyl methacrylate And 3-chloro-2-acid phosphooxypropyl methacrylate.

  Furthermore, as a polymerizable monomer, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate, neopentyl A binder resin having a crosslinked structure can also be obtained using a polyfunctional vinyl such as glycol diacrylate.

<Surfactant>
When the toner particles constituting the toner of the present invention are produced by suspension polymerization, miniemulsion polymerization aggregation or emulsion polymerization aggregation, the surfactant used for obtaining the binder resin is particularly limited. Although not intended, sulfonate (sodium dodecylbenzenesulfonate, sodium arylalkylpolyethersulfonate), sulfate ester salt (sodium dodecyl sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, etc.), fatty acid salt (olein) Suitable examples include ionic surfactants such as sodium oxalate, sodium laurate, sodium caprate, sodium caprylate, sodium caproate, potassium stearate, calcium oleate, and the like. Also, polyethylene oxide, polypropylene oxide, combination of polypropylene oxide and polyethylene oxide, ester of polyethylene glycol and higher fatty acid, alkylphenol polyethylene oxide, ester of higher fatty acid and polyethylene glycol, ester of higher fatty acid and polypropylene oxide, sorbitan ester, etc. Nonionic surfactants can also be used. These surfactants are used as an emulsifier when a toner is obtained by an emulsion polymerization method, but may be used for other processes or purposes.

<Polymerization initiator>
When the toner particles constituting the toner of the present invention are produced by suspension polymerization, miniemulsion polymerization aggregation or emulsion polymerization aggregation, the binder resin can be polymerized using a radical polymerization initiator.

  In the case of using the suspension polymerization method, an oil-soluble radical polymerization initiator can be used. As the oil-soluble polymerization initiator, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2 ′ -Azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile, etc. Azo or diazo polymerization initiator, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4- Dichlorobenzoyl peroxide, lauroyl peroxide, 2 Peroxide polymerization initiators such as 2-bis- (4,4-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine, polymer initiators having a peroxide in the side chain, etc. Can be mentioned.

  In the case of using the mini-emulsion polymerization aggregation method or the emulsion polymerization aggregation method, a water-soluble radical polymerization initiator can be used, and examples of the water-soluble radical polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate. Azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, hydrogen peroxide, and the like.

<Chain transfer agent>
A chain generally used for the purpose of adjusting the molecular weight of the binder resin when the toner particles constituting the toner of the present invention are produced by suspension polymerization, miniemulsion polymerization aggregation or emulsion polymerization aggregation. A transfer agent can be used.

  The chain transfer agent is not particularly limited, and examples thereof include mercaptans such as n-octyl mercaptan, n-decyl mercaptan, tert-dodecyl mercaptan, n-octyl-3-mercaptopropionate, terpinolene, carbon tetrabromide. And α-methylstyrene dimer and the like are used.

<Colorant>
As the colorant constituting the toner of the present invention, a known inorganic or organic colorant can be used. Specific colorants are shown below.

  Examples of the black colorant include carbon black such as furnace black, channel black, acetylene black, thermal black and lamp black, and magnetic powder such as magnetite and ferrite.

  Examples of the colorant for magenta or red include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48; 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the colorant for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 138, and the like.

  Examples of the colorant for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15; 2, C.I. I. Pigment blue 15; 3, C.I. I. Pigment blue 15; 4, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment blue 62, C.I. I. Pigment blue 66, C.I. I. And CI Pigment Green 7.

  The above colorants can be used alone or in combination of two or more.

  The addition amount of the colorant is in the range of 1 to 30% by mass, preferably 2 to 20% by mass with respect to the whole toner.

  As the colorant, a surface-modified one can also be used. As the surface modifier, conventionally known ones can be used, and specifically, silane coupling agents, titanium coupling agents, aluminum coupling agents and the like can be preferably used.

<Flocculant>
When the toner particles constituting the toner of the present invention are produced by the miniemulsion polymerization aggregation method or the emulsion polymerization aggregation method, examples of the aggregation agent used for obtaining the binder resin include alkali metal salts and alkaline earth metal salts. Can be mentioned. Examples of the alkali metal constituting the flocculant include lithium, potassium, and sodium, and examples of the alkaline earth metal constituting the flocculant include magnesium, calcium, strontium, and barium. Of these, potassium, sodium, magnesium, calcium, and barium are preferable. Examples of the counter ion (anion constituting the salt) of the alkali metal or alkaline earth metal include chloride ion, bromide ion, iodide ion, carbonate ion and sulfate ion.

<Release agent>
There is no particular limitation, and known ones can be used. Among them, those having the following structures are particularly preferable.

Ester wax R _1- (OCO-R ₂ ) _n
(R ₁ and R ₂ are hydrocarbon groups, n = 1 to 4)
N is preferably 2 to 4, more preferably 3 to 4, and particularly preferably 4.

R ₁ has 1 to 40 carbon atoms, preferably 1 to 20 carbon atoms, more preferably 2 to 5 carbon atoms, and R ₂ has 1 to 40 carbon atoms, preferably 16 to 20 carbon atoms, and more preferably 18 to 26 carbon atoms.

  The addition amount of the ester wax is preferably 1 to 20 parts by mass, particularly preferably 3 to 15 parts by mass with respect to 100 parts by mass of the toner.

<Charge control agent>
The toner particles constituting the toner of the present invention may contain a charge control agent as necessary. Various known compounds can be used as the charge control agent.

<Toner particle size>
The toner of the present invention preferably has a number average particle diameter of 3 to 8 μm. When the toner particles are formed by a polymerization method, the particle size is controlled by the concentration of the aggregating agent, the amount of the organic solvent added, the fusing time, and the composition of the polymer itself in the above-described toner manufacturing method. can do.

  The number average particle size is 3 to 8 μm, so that reproducibility of fine lines and high image quality of photographic images can be achieved, and the amount of toner consumption can be reduced as compared with the case of using a large particle size toner. Can do.

<External additive>
Although the external additive of the present invention is used, a known external additive can be further added and used for the purpose of improving fluidity, chargeability and cleaning property. These external additives are not particularly limited, and various inorganic fine particles, organic fine particles and lubricants can be used.

  As the inorganic fine particles, it is preferable to use inorganic oxide particles such as silica, titania and alumina, and these inorganic fine particles are preferably hydrophobized with a silane coupling agent or a titanium coupling agent. . As the organic fine particles, spherical particles having a number average primary particle diameter of about 10 to 2000 nm can be used. As the organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymer can be used.

(Developer)
The toner of the present invention can be used as a magnetic or non-magnetic one-component developer, but may be mixed with a carrier and used as a two-component developer. When the toner of the present invention is used as a one-component developer, a non-magnetic one-component developer or a magnetic one-component developer containing about 0.1 to 0.5 μm of magnetic particles in the toner can be mentioned. Any of them can be used. In the case where the toner of the present invention is used as a two-component developer, the carrier may be a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead. In particular, ferrite particles are preferable. As the carrier, a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, a resin dispersion type carrier in which magnetic fine powder is dispersed in a binder resin, or the like may be used.

  The coating resin constituting the coat carrier is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, silicon resins, ester resins, and fluorine-containing polymer resins. Moreover, it does not specifically limit as resin which comprises a resin dispersion type carrier, A well-known thing can be used, For example, a styrene-acrylic-type resin, a polyester resin, a fluororesin, a phenol resin etc. can be used.

  A preferable carrier is a coated carrier coated with a styrene-acrylic resin-based resin as a coating resin from the viewpoint of prevention of detachment of external additives and durability.

  The volume average particle diameter of the carrier is preferably 20 to 100 μm, more preferably 25 to 80 μm. The volume average particle diameter of the carrier can be typically measured by a laser diffraction particle size distribution measuring apparatus “HELOS” (manufactured by SYMPATEC) equipped with a wet disperser.

[Image Forming Method and Image Forming Apparatus]
In particular, the toner of the present invention can be suitably used in an image forming method in which a transfer material on which a toner image is formed is fixed in a contact heating type fixing device.

  FIG. 2 is an explanatory view showing an example of an image forming apparatus used in the toner image forming method of the present invention.

  This image forming apparatus is a tandem color image forming apparatus having a configuration in which four sets of image forming units 100Y, 100M, 100C, and 100Bk are provided along an intermediate belt 14a that is an intermediate transfer member.

  Each of the image forming units 100Y, 100M, 100C, and 100Bk is formed by forming a photoconductive layer made of a conductive layer and an organic photoreceptor (OPC) on the outer peripheral surface of a cylindrical base, and a driving source (not shown) Photoconductor drum 10Y comprising a photoconductor drum 10Y, 10M, 10C, 10Bk that is rotated counterclockwise by the power from the motor or following the intermediate belt 14a and the conductive layer is grounded, and a scorotron charger. Charging that is arranged in a direction orthogonal to the moving direction of 10M, 10C, and 10Bk and that gives a uniform potential to the surfaces of the photosensitive drums 10Y, 10M, 10C, and 10Bk by corona discharge having the same polarity as the toner. The photosensitive drums 10Y, 10M, 10C, and 10B by means 11Y, 11M, 11C, and 11Bk and a polygon mirror, for example. Exposure means 12Y for forming a latent image by performing image exposure on the surface of the uniformly charged photoreceptor drums 10Y, 10M, 10C, and 10Bk by scanning in parallel with the rotation axis of 12M, 12C, 12Bk and rotating developing sleeves 131Y, 131M, 131C, 131Bk, and developing means 13Y, 13M, for conveying the toner held thereon to the surfaces of the photosensitive drums 10Y, 10M, 10C, 10Bk 13C and 13Bk.

  Here, the image forming unit 100Y forms a yellow toner image, the image forming unit 100M forms a magenta toner image, and the image forming unit 100C forms a cyan toner image. According to the image forming unit 100Bk, a black toner image is formed.

  In such an image forming apparatus, the toner images of the respective colors formed on the photoconductive drums 10Y, 10M, 10C, and 10Bk of the image forming units 100Y, 100M, 100C, and 100Bk are transferred at the same timing. A color toner image is formed by sequentially transferring and superimposing on the material P by the transfer means 14Y, 14M, 14C, and 14Bk, and is transferred onto the transfer material P in a batch by the secondary transfer means 14b and separated. 16 is separated from the intermediate belt 14a by the fixing device 17 and fixed by the fixing device 17, and finally discharged from the discharge port 18 to the outside of the apparatus.

  Next, although this invention is demonstrated based on a specific aspect, of course, the aspect of this invention is not necessarily limited to these.

[Manufacture of external additives]
<Manufacture of external additive 1>
Production of Particles (B1) The production apparatus shown in FIG. 1 was used to produce “particles (B1)” that are raw materials for “external additive 1”.

  Gaseous titanium tetrachloride with a concentration of 100% is preheated to 1,000 ° C., and a mixed gas of oxygen 27.0% by volume and water vapor 73.0% by volume is preheated to 1,000 ° C., and a coaxial parallel flow nozzle is used. Were introduced into the reaction tube (combustion furnace) at flow rates of 45 m / sec and 50 m / sec, respectively. Titanium tetrachloride gas was introduced into the inner tube. The reaction temperature was 1,300 ° C. In addition, cooling air was introduced into the reaction tube so that the high temperature residence time in the reaction tube was 0.1 seconds or less, and then titanium dioxide particles produced using a polytetrafluoroethylene bag filter were collected.

  The obtained titanium dioxide particles had a number average primary average particle size of 110 nm, and X-ray diffraction analysis and transmission electron microscope observation confirmed that a plurality of crystals were aggregated and sintered.

  This titanium dioxide was designated as “particle (B1)”.

Production of Powder (A1) For production of “powder (A1)” as a raw material of “external additive 1”, the production apparatus shown in FIG. 1 was used.

  A gas containing gaseous silicon tetrachloride with a concentration of 100% by volume is preheated to 1,000 ° C., and a mixed gas of 28.5% by volume of oxygen and 71.5% by volume of water vapor is preheated to 1,000 ° C. The flow nozzle was used to introduce the reaction tube at flow rates of 49 m / sec and 60 m / sec, respectively. The reaction temperature was 1,300 ° C.

  The silica powder obtained in the reaction tube was designated as “powder (A1)”.

Composite of Particle (B1) and Powder (A1) Using the manufacturing apparatus shown in FIG. 1, composite of particle (B1) and powder (A1) was performed.

  The raw material obtained by mixing the “particle (B) 1” and the “powder (A1)” in a resin bag so as to have a mass of 9: 1 in advance is put into the raw material tank 210 and supplied at a supply rate of 4 kg / hour. Then, it was conveyed by the introduction pipe 250 together with air as a carrier gas, and was ejected from the nozzle. At this time, the flow velocity of the air nozzle was 48 m / sec.

  After the reaction, cooling air was introduced into the reaction tube so that the high-temperature residence time in the reaction tube was 0.3 seconds or less, and then the fine powder produced using a polytetrafluoroethylene bag filter was collected. . The collected powder was heated in an oven at 500 ° C. for 1 hour in an air atmosphere to perform dechlorination treatment. 500 parts by mass of this powder was charged in a high-speed stirring mixer equipped with a jacket for heating and cooling, and 25 parts by mass of pure water was spray-fed in a sealed state while stirring at 500 rpm, and then stirring was continued for 10 minutes. Subsequently, 40 parts by mass of hexamethyldisilazane was added, and stirring was performed for 60 minutes in a sealed state. Thereafter, the mixture was heated with stirring, and the generated ammonia gas and the remaining treating agent were removed while flowing nitrogen at 150 ° C. . This is designated as “external additive 1”.

  The obtained “external additive 1” had a number average primary particle size of 120 nm and a degree of hydrophobicity of 55%. X-ray analysis and transmission electron microscope observation confirmed that amorphous silica was fused to the surface of the core of amorphous titanium dioxide.

<Method for producing external additive 2 = sol-gel method>
Synthesis of hydrophilic spherical sol-gel composite fine particles In a 3 liter glass reactor equipped with a stirrer, a dropping funnel and a thermometer, 623.7 g of methanol, 41.4 g of water, and 49.8 g of 28 mass% aqueous ammonia. And mixed. The obtained solution was adjusted to 35 ° C., and 1163.7 g of tetraethoxytitanium and 418.1 g of 5.4% by mass ammonia water were started to be added simultaneously with stirring. Water was added dropwise over 5 hours. After completion of the dropwise addition, the mixture was further stirred for 0.5 hours for hydrolysis to obtain a methanol-water dispersion of hydrophilic spherical sol-gel titanium fine particles. Next, 128.2 g of tetramethoxysilica was added dropwise over 1 hour, and after completion of the dropwise addition, the mixture was further stirred for 0.5 hour and hydrolyzed to obtain a methanol-water dispersion of hydrophilic spherical sol-gel composite fine particles. Got. An ester adapter and a condenser tube were attached to a glass reactor, and the dispersion was heated to 60 to 70 ° C. to distill off 1200 g of methanol, and then 1200 g of water was added.

  Subsequently, the obtained dispersion was heated to 70 to 90 ° C. to distill off 484 g of methanol, thereby obtaining an aqueous dispersion of hydrophilic spherical sol-gel composite fine particles.

Hydrophobization treatment of hydrophilic spherical sol-gel composite fine particles 11.6 g (0.085 mol) of methyltrimethoxysilane was added dropwise to this aqueous dispersion at room temperature over 0.5 hours, and stirring was continued for 12 hours after the addition. Hydrophilic spherical sol-gel composite fine particles were hydrophobized to obtain an aqueous dispersion of T unit-treated spherical sol-gel composite fine particles.

  After adding 1440 g of methyl isobutyl ketone to the obtained aqueous dispersion of T unit-treated spherical sol-gel composite fine particles, 1340 g of a mixture of methanol and water was distilled off over 10 hours by heating to 80 to 110 ° C. After adding 150 g (0.93 mol) of hexamethyldisilazane to the obtained dispersion at room temperature, the composite fine particles in the dispersion were trimethylsilylated by heating to 110 ° C. and reacting for 3 hours. Next, the solvent in the dispersion was distilled off at 80 ° C. under reduced pressure (6650 Pa) to thereby form hydrophobic spherical sol-gel composite fine particles (1) having an average primary particle size of 110 nm and a hydrophobization degree of 66%. 463 g was obtained.

  This is designated as external additive 2.

<Method for producing external additive 3 = sol-gel method>
External external additive 3 was synthesized in the same manner as external additive 2 except that tetraethoxytitanium was changed to tetraethoxyaluminum in the production method of external additive 2. The number average primary particle size of the obtained “external additive 3” was 110 nm, and the degree of hydrophobicity was 60%.

<Method for producing external additive 4 (comparative example)>
External additive 4 was produced in the same manner as external additive 1 except that in the production method of external additive 1, oxygen was 96% by volume and water vapor was 4% by volume in the production stage of titanium dioxide.

  The obtained “external additive 4” had a number average primary particle size of 120 nm and a degree of hydrophobicity of 63%. The transmission electron microscope confirmed that amorphous silica was fused to the surface of the core of crystalline titanium dioxide. The titanium dioxide crystal was confirmed to be anatase type by X-ray diffraction.

<Method for producing external additive 5 (comparative example)>
In the method for producing external additive 1, external additive 5 was produced in the same manner as external external additive 1 except that the amount of hexamethyldisilazane was 25 parts by mass. The obtained “external additive 1” had a number average primary particle size of 120 nm and a degree of hydrophobicity of 40%.

<Method for producing external additive 6 (comparative example)>
Titanium sulfate solution (containing 1.90 mol / L titanyl sulfate in terms of TiO ₂ and 0.63 mol / L iron sulfate in terms of Fe ₂ O ₃ ) 240 parts by mass and 520 parts by mass of water are placed in an autoclave, 180 Heated to a temperature of 0 ° C. and held at this temperature for 1 hour. The pressure at this time was 88 kPa / cm ² in terms of saturated vapor pressure. Subsequently, the obtained product was cooled to a temperature of 60 ° C., filtered, washed, and dried at a temperature of 110 ° C. to obtain spherical hydrous titanium dioxide having a shape factor of 0.93. This spherical hydrous titanium dioxide was calcined at 600 ° C. for 2 hours to obtain titanium dioxide, and then 100 g of this was suspended in 1 L of water to form a slurry, and the pH of the slurry was adjusted to 11.0 with an aqueous sodium hydroxide solution. Then, the slurry temperature was heated to 70 ° C., and then an aqueous sodium silicate solution was added dropwise over 30 minutes. Subsequently, after the slurry temperature was heated to 90 ° C., dilute sulfuric acid was added dropwise over 40 minutes to neutralize to pH 7.0, and further maintained for 60 minutes. Thereafter, dehydration and washing were performed to obtain spherical titanium dioxide coated with dense amorphous silica (9 parts by mass as SiO _{2 with} respect to 100 parts by mass of titanium dioxide).

  Next, spherical titanium dioxide coated with silica was placed in a rotary furnace having an inner diameter of 15 cm, and the inside of the furnace was replaced with nitrogen gas. Thereafter, the reactor was heated at 845 ° C. for 3 hours while venting methylamine gas into the furnace at a flow rate of 5 L / min. Next, the obtained product was cooled to 100 ° C. in the same atmosphere, and further allowed to cool to room temperature in the air. The obtained particles were made into a water slurry and wet-pulverized, 6 mol / L hydrochloric acid was added to adjust the pH to 2.0, and 25% by mass of n-butyltrimethoxysilane was added to titanium oxide. After stirring and holding for 30 minutes, 4 mol / L sodium hydroxide aqueous solution was added to neutralize to pH 6.5, filtration, washing with water, drying at 150 ° C., fine pulverization with an airflow crusher, and “external additive 6” was added. Obtained.

  The obtained “external additive 6” had a number average primary particle size of 24 nm and a hydrophobicity of 50%.

[Production of toner base]
<Preparation of Toner Base 1>
Preparation of resin particles (1HML) (1) Preparation of core particles (first stage polymerization):
Surfactant solution (aqueous medium) in which 7.08 parts by mass of an anionic surfactant having the following structure is dissolved in 3010 parts by mass of ion-exchanged water in a separable flask equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introduction apparatus. The temperature in the flask was raised to 80 ° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream.

Anionic surfactant: C ₁₀ H ₂₁ (OCH ₂ CH ₂ ) ₂ OSO ₃ Na
To this surfactant solution, an initiator solution in which 9.2 parts by mass of a polymerization initiator (potassium persulfate: KPS) was dissolved in 200 parts by mass of ion-exchanged water was added to a temperature of 75 ° C. 1 part by mass, 19.9 parts by mass of n-butyl acrylate, and 10.9 parts by mass of methacrylic acid were added dropwise over 1 hour, and this system was heated and stirred at 75 ° C. for 2 hours. As a result, polymerization (first-stage polymerization) was carried out to prepare a dispersion of resin particles serving as the core of the toner base. This is designated as “resin particle dispersion (1H)”.

  (2) Formation of intermediate layer (second stage polymerization): In a flask equipped with a stirrer, 105.6 parts by mass of styrene, 30.0 parts by mass of n-butyl acrylate, 6.2 parts by mass of methacrylic acid, n- 98.0 parts by mass of pentaerythritol tetrabehenate is added to a monomer mixture composed of 5.6 parts by mass of octyl-3-mercaptopropionate, and the monomer solution is heated to 90 ° C. and dissolved. Was prepared.

  On the other hand, a surfactant solution obtained by dissolving 1.6 parts by mass of the anionic surfactant in 2700 parts by mass of ion-exchanged water is heated to 98 ° C., and the above-mentioned monomer solution and After adding 28 parts by mass of the resin particle dispersion (1H) in terms of solid content, it is mixed and dispersed for 8 hours by a mechanical disperser “CLEARMIX” (manufactured by M Technique) having a circulation path. A dispersion (emulsion) containing emulsified particles (oil droplets) was prepared.

  Next, an initiator solution prepared by dissolving 5.1 parts by mass of a polymerization initiator (KPS) in 240 parts by mass of ion-exchanged water and 750 parts by mass of ion-exchanged water are added to this dispersion (emulsion). The system is polymerized by heating and stirring at 98 ° C. for 12 hours (second-stage polymerization), and a dispersion of composite resin particles having a structure in which the surface of the resin particles made of a high molecular weight resin is coated with an intermediate molecular weight resin. Obtained. This is referred to as “resin particle dispersion (1HM)”.

(3) Formation of outer layer (third stage polymerization):
An initiator solution prepared by dissolving 7.4 parts by mass of a polymerization initiator (KPS) in 200 parts by mass of ion-exchanged water is added to the resin particle dispersion (1HM) obtained as described above, and a temperature of 80 ° C. Under the conditions, a monomer mixed solution composed of 300 parts by mass of styrene, 95 parts by mass of n-butyl acrylate, 15.3 parts by mass of methacrylic acid, and 10.4 parts by mass of n-octyl-3-mercaptopropionic acid ester was added for 1 hour. It was dripped over. After completion of the dropwise addition, polymerization (third stage polymerization) was performed by heating and stirring for 2 hours, and then cooled to 28 ° C., and resin particles (a central part made of a high molecular weight resin, an intermediate layer made of an intermediate molecular weight resin, A dispersion of composite resin particles) having an outer layer made of a low molecular weight resin and containing pentaerythritol tetrabehenate in the intermediate layer. This dispersion is referred to as “resin particle dispersion (1HML)”.

  59.0 parts by mass of the anionic surfactant is dissolved in 1600 parts by mass of ion-exchanged water, and 420.0 parts by mass of carbon black “Regal 330” (manufactured by Cabot) is gradually added while stirring the solution. Then, a dispersion liquid of colorant particles (hereinafter also referred to as “colorant dispersion liquid 1”) was prepared by performing a dispersion treatment using “CLEARMIX” (manufactured by M Technique Co., Ltd.). When the particle diameter of the colorant particles in this colorant dispersion was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the mass average particle diameter was 89 nm.

  420.7 parts by mass (converted to solid content) of “resin particle dispersion (1HML)”, 900 parts by mass of ion-exchanged water, and 166 parts by mass of “colorant dispersion 1” were combined with a temperature sensor, a cooling tube, and nitrogen. The mixture was stirred in a reaction vessel (four-necked flask) equipped with an introduction device and a stirring device. After adjusting the temperature in the container to 30 ° C., a 5 mol / L sodium hydroxide aqueous solution was added to this solution to adjust the pH to 10.0.

Next, an aqueous solution obtained by dissolving 12.1 parts by mass of magnesium chloride hexahydrate in 1000 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring. After standing for 3 minutes, the temperature was started to rise, and the system was heated to 90 ° C. over 6 to 60 minutes to produce associated particles. In this state, the particle size of the associated particles was measured with “Multisizer 3” (manufactured by Beckman Coulter), and when the volume-based median diameter (D ₅₀ ) reached 6.1 μm, sodium chloride 80.4 By adding an aqueous solution in which parts by mass are dissolved in 1000 parts by mass of ion-exchanged water, the particle growth is stopped, and further, as a ripening treatment, the mixture is heated and stirred at a liquid temperature of 98 ° C. for 2 hours, thereby fusing particles and producing a crystalline substance. The phase separation of was continued.

Then, it cooled to 30 degreeC, hydrochloric acid was added, pH was adjusted to 4.0, and stirring was stopped. The produced association particles were solid-liquid separated with a basket type centrifuge to form a toner base cake. The toner base cake is washed with water in the basket-type centrifuge, then transferred to a “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.), and dried until the water content becomes 0.5 mass%. 1 "was produced. The toner base material had a median particle size (D ₅₀ ) of 6.0 μm.

[Production of toner]
(Preparation of Toner 1)
1.0 part by weight of “External Additive 1” is added to 100 parts by weight of the above toner base, mixed with “Henschel Mixer” (manufactured by Mitsui Mining Co., Ltd.) for 10 minutes, and then coarse particles with an opening of 45 μm. Then, “Toner 1” was produced.

(Production of toners 2 to 6)
Toners 1 to 6 were produced in the same manner as in the production of toner 1 except that “external additive 1” was changed to the external additive shown in Table 1.

[Production of two-component developer]
Each of the “toners 1 to 6” produced above was mixed with a ferrite carrier having a volume-based median diameter (D ₅₀ ) of 40 μm coated with styrene-acrylic resin so that the toner concentration was 6% by mass. Agents 1-6 "were prepared.

[Evaluation equipment]
As the image forming apparatus for evaluation, “bizhub PRO C6500” (printing speed of about 65 sheets / min) (made by Konica Minolta Business Technologies, Inc.) equipped with a developing device for two-component developer was used.

  Using the “bizhub PRO C6500” equipped with the above two-component developer developing device, the “two-component developer 1-6” produced above and “toner 1-6” as the replenishment toner were loaded in order. Were printed and evaluated.

〔Evaluation item〕
The following evaluation items were evaluated. In the evaluation, “A” and “B” indicate that there is no problem, and “B” and “B” indicate that there is a problem and that the test is rejected.

<Increase in charge at low temperature and low humidity>
Perform 100,000 prints on high-quality paper (65 g / m ² ) on A4 size paper under low temperature and low humidity (10 ° C, 20% RH) environmental conditions, and measure the charge amount of the developer at the start and after the completion of 100,000 prints And evaluated. The charge amount was measured by sampling the developer in the developing unit and using a blow-off charge amount measuring device “TB-200” (manufactured by Toshiba Chemical Corporation).

Evaluation Criteria A: Excellent when the charge amount increase is less than 3.0 μC / g at the start and after the end of 100,000 printing. ○: The increase in charge amount is 3.0 to 6.0 μC / at the start and after the end of 100,000 print. Good at g x: Charge amount increase is poorer than 6.0 μC / g at the start and after the end of 100,000 printing.

<Image density reduction at low temperature and low humidity>
Under the environmental conditions of low temperature and low humidity (10 ° C, 20% RH), perform 100,000 prints on high-quality paper (65 g / m ² ) of A4 size, and set the image density of the solid image area at the start and after the completion of 100,000 sheets of printing. Measured and evaluated. The image density was measured using a reflection densitometer “RD-918” (manufactured by Macbeth).

Evaluation Criteria A: Excellent when the image density decreases less than 0.01 at the start and after the end of 100,000 printing ○: Good when the image density decreases less than 0.04 at the start and after the end of 100,000 printing ×: Start At that time and after the end of 100,000 prints, the image density drop was 0.04 or higher.

<Reduction of charge amount at high temperature and high humidity>
Under environmental conditions of high temperature and high humidity (30 ° C, 85% RH), perform 100,000 prints on high-quality paper (65 g / m ² ) of A4 size, measure the charge amount at the start and after the completion of printing 100,000 sheets, evaluated. The charge amount was measured by sampling the developer in the developing unit and using a blow-off charge amount measuring device “TB-200” (manufactured by Toshiba Chemical Corporation).

Evaluation Criteria A: Excellent when the charge amount decrease is less than 3.0 μC / g at the start and after the end of 50,000 printing. ○: The charge amount decrease is 3.0 to 6.0 μC / at the start and after the end of 50,000 print. Good at g ×: The charge amount increase is larger than 6.0 μC / g at the start and after the end of 50,000 printing, and is poor.

<Transferability deterioration at high temperature and high humidity>
Printing on A4 quality paper (65 g / m ² ) in a printing environment of normal temperature and humidity (20 ° C., 50% RH) and high temperature and high humidity (30 ° C., 80% RH). The transfer rate in each environment was determined. The decrease in transferability was evaluated by the decrease in transfer rate.

Formula (1)
Transfer rate (%) = (1− (mass of collected toner / mass of consumed toner)) × 100
Here, the collected toner is the untransferred toner discharged from the cleaning unit, and the consumed toner is a decrease in the mass of the developing unit and the toner replenishing unit. However, evaluation was performed without toner recycling.

Evaluation Criteria A: Transfer rate exceeding 99.5% for both normal temperature and normal humidity and high temperature and high humidity. O: Good transfer rate of 99.0 to 99.5% for high temperature and high humidity. Δ: Transfer rate for high temperature and high humidity. Is less than 95.0 to less than 99.0% in practical use. X: Defect when transfer rate of high temperature and high humidity is less than 95.0%.

<Toner packing after long-term stop>
A torque gauge was attached to the stirring blade of the toner replenishing device, and the current flowing through the drive motor was examined.

  The current was measured after image formation and after standing at high temperature and high humidity (30 ° C., 80% RH) for 120 hours.

Evaluation Criteria A: Excellent when the driving torque of the stirring blade is less than 5% of the normal time ○: Good when the driving torque of the stirring blade is 5% or more of the normal time and less than 10% Δ: The driving torque of the stirring blade is 10 of the normal time % Or more and less than 20%. Motor current instantaneously becomes overloaded and is slightly problematic for practical use ×: The driving torque of the stirring blade is 200% or more of the normal time. The motor current is overloaded and defective with abnormal heat generation.

<Image density reduction after reprinting after a long stop>
The evaluation of the decrease in image density was performed after the image was formed and allowed to stand for 120 hours in high temperature and high humidity (30 ° C., 80% RH). For the print image, an image pattern having the maximum density was selected on the entire surface of the A3 plate.

Evaluation Criteria A: No problem in the toner conveyance amount, and sufficient density can be obtained on the entire surface. ○: No problem in the toner conveyance amount, and the image quality is slightly lost, but there is no lack of density. Good: Development unit The amount of toner transported to the surface is reduced by less than 10%, and the rear edge of the image is blurred by 5 mm, causing a slight problem in practical use. X: The amount of toner transported to the developing unit is decreased by 10% or more, and insufficient density is detected in the entire image. Bad.

  From Table 2, it can be seen that the toner of the present invention has good characteristics, but the comparative toner of the present invention does not reach any practical level.

210 Powder (A)
211 particles (B)
220 Particle (A) Tank 221 Particle (B) Tank 230 Particle (A) Metering Supply Pump 231 Particle (B) Metering Supply Pump 260 Main Burner 261 Introduction Pipe 262 Oxygen / Steam Mixing Gas 263 Oxygen / Steam Mixing Gas Tank 270 Combustion furnace (reaction tube)
280 Combustion flame, 290 is the flue 300 Cyclone 320 Bag filter

Claims (3)

  A toner for developing an electrostatic latent image in which an external additive is added to toner base particles, and the external additive has a hydrophobization degree of 55% or more, which is higher than that of amorphous titanium oxide or amorphous aluminum oxide. A toner for developing an electrostatic charge image, comprising a selected metal oxide as a nucleus and an amorphous silica layer on the surface of the nucleus.   The electrostatic charge image developing toner according to claim 1, wherein the external additive is produced by a wet method.   The toner for developing an electrostatic charge image according to claim 1 or 2 is used, and after the photoreceptor is uniformly charged, a toner image is formed through image exposure and development steps, transferred to a recording material, and then fixed. An image forming method.

Images