JP2010019887A - Two-component development method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-component development method which suppresses the occurrence of image memory and toner scattering even in the case of using a development roller made of an aluminum alloy. <P>SOLUTION: The two-component development method includes: holding a two-component developer comprising a toner and a carrier on a development roller; conveying the developer to a development area facing an electrostatic latent image carrier; and developing an electrostatic latent image on the electrostatic latent image carrier with the toner, wherein the development roller is made of an aluminum alloy, a dynamic current value of the carrier is 0.1-1.0 μA, and the toner comprises toner particles containing at least a resin and a colorant, and titanic acid compound particles externally added to the toner particles and having a number average particle diameter of 120-550 nm and an iron element content of 0.01-0.12 wt.%. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a two-component development method.

  In the two-component development method, the two-component developer composed of toner and carrier is mechanically agitated so that the toner and carrier are brought into frictional contact with each other to charge the toner, and then the two-component development is performed on the developing roller. The agent is held and transported to a developing area facing the electrostatic latent image carrier, and the electrostatic latent image on the electrostatic latent image carrier is developed with toner. Specifically, in such a two-component development method, carrier particles are linked by magnetic force on the surface of the developing roller to form ears (brushes), and toner adheres electrostatically to the surface of the carrier particles that form the ears. Then, it is conveyed to the development area and used for development. There was a problem of toner scattering at the time of development durability.

  In order to suppress toner scattering, attempts have been made to increase the resistance of the carrier. By increasing the resistance of the carrier, the charge leakage property of the carrier is reduced, so that toner retention is improved, and even if the carrier deteriorates due to printing durability, toner scattering can be prevented. However, in such a technique, for example, when a half image is formed after developing an image having a solid portion, a memory phenomenon occurs in which the solid portion appears as a relatively low density portion. Such a memory phenomenon occurred particularly remarkably when a developing roller made of an aluminum alloy was used. Further, when an oscillating electric field (alternating current electric field) is formed in the developing region in order to promote toner movement from the developing roller to the electrostatic latent image carrier, the phenomenon occurs more remarkably.

  An object of the present invention is to provide a two-component developing method that suppresses generation of image memory and toner scattering even when a developing roller made of an aluminum alloy is used.

The present invention
A two-component developer composed of toner and a carrier is held on the developing roller, conveyed to a developing area facing the electrostatic latent image carrier, and the electrostatic latent image on the electrostatic latent image carrier is developed with the toner. A two-component development method comprising:
The developing roller is made of aluminum alloy,
The dynamic current value of the carrier is 0.1 to 1.0 μA,
The toner includes toner particles containing at least a resin and a colorant, and titanic acid compound particles having a number average particle diameter of 120 to 550 nm and an iron element content of 0.01 to 0.12 wt% which are externally added to the toner particles. And a two-component developing method.

  According to the two-component developing method of the present invention, image memory generation and toner scattering can be suppressed even when a developing roller made of an aluminum alloy is used. Moreover, such an effect of the present invention can be effectively obtained even when an oscillating electric field is formed in the development region.

  In the two-component development method (hereinafter simply referred to as “development method”) according to the present invention, a two-component developer composed of toner and a carrier is conveyed by a developing roller, and an electrostatic latent image on an electrostatic latent image carrier is formed. Develop. For example, as shown in FIG. 1, a two-component developer 2 composed of toner and carrier is held on a developing roller 1 and conveyed to a developing region 4 facing the electrostatic latent image carrier 3 and electrostatically charged by the toner. The electrostatic latent image on the latent image carrier 3 is developed. FIG. 1 is a schematic configuration diagram of an example of a developing device employing the developing method of the present invention.

  The developing roller 1 is a non-magnetic cylindrical body made of an aluminum alloy, and is rotatably held so as to face the electrostatic latent image carrier 3 with an appropriate distance (Ds). Examples of the metal material constituting the developing roller include those made of a metal material such as an aluminum alloy, a stainless alloy, and a copper alloy. In particular, an aluminum alloy is preferable in terms of material cost and workability. The distance (Ds) is not particularly limited, and may be 0.2 to 1.0 mm, particularly 0.3 to 0.7 mm, for example.

The surface roughness Rz of the developing roller is not particularly limited, but is preferably 5 to 20 μm, particularly 5 to 15 μm, from the viewpoint of securing the developer conveyance amount and ease of manufacture.
As the surface roughness Rz, a value measured with a 10-point average roughness (RZ) by a surface roughness meter manufactured by Tokyo Seimitsu Co., Ltd. is used.

A magnet roller 9 having a plurality of magnetic poles N ₁ , S ₁ , N ₂ , S ₂ , N ₃ is usually provided on the inner peripheral side of the developing roller 1, and the surface of the developing roller 1 is developed by the magnetic force of the magnet roller 9. The agent 2 is held and conveyed.

The developer 2 is composed of toner and carrier.
A carrier having a dynamic current value of 0.1 to 1.0 μA, particularly 0.2 to 0.5 μA is used. If the dynamic current value is too small, the carrier holding charge becomes too high, and the toner holding property of the carrier excessively increases, so that an image memory is generated. If the dynamic current value is too large, the carrier holding charge becomes too low and the toner holding property of the carrier is excessively lowered, so that toner scattering occurs.

As the dynamic current value (CDC value) of the carrier, a value measured by the following method using an apparatus having a configuration schematically shown in FIG. 2 is used.
A carrier 20 is set on the aluminum sleeve 12 and a voltage is applied by a DC power source 14 while the sleeve 12 is rotated. The current flowing from the sleeve 12 to the ammeter 15 through the carrier 20 and the aluminum tube 13 is measured. The measurement conditions are as follows.
・ Sleeve rotation speed: 50 rpm
・ Applied voltage: 500V
・ Sample amount: 5g
・ Sleeve 12
Longitudinal length: 55 mm, diameter: 31 mm, magnet magnetic force: 1000 gauss, number of magnet magnetic poles: 8, aluminum tube 13
Longitudinal length: 55 mm, diameter: 30 mm
-Environment: 20 ° C, 50% RH

  The dynamic current value of the carrier can be controlled by adjusting the content of magnetic particles or adjusting the amount of coating resin in the carrier production method described below. For example, when the amount of the coating resin is decreased, the dynamic current value is increased, and when the amount of the coating resin is increased, the dynamic current value is decreased.

  The carrier may have any configuration as long as it has a dynamic current value within the above range. For example, the carrier may have a configuration in which magnetic particles are dispersed in a binder resin (binder type). In addition, a carrier base material such as magnetic particles may be coated with a coating resin (coating type). From the viewpoint of controlling the dynamic current value within a suitable range, a coating type in which the control of the electric characteristics of the carrier is relatively easy is preferable.

  The binder-type carrier is obtained, for example, by sufficiently mixing a binder resin and magnetic particles, and optionally a conductive substance and a fluidizing agent, melt-kneading, coarsely pulverizing and finely pulverizing, and optionally classifying and surface-treating. be able to.

  As the magnetic particles, known magnetic particles conventionally used in the field of carriers can be used. For example, magnetite particles can be used. The amount of magnetic particles added is 200 to 800 parts by weight, preferably 300 to 700 parts by weight, based on 100 parts by weight of the binder resin.

  As the binder resin, known resins conventionally used as carrier binder resins can be used, for example, polyester resins, styrene-acrylic resins, amino group-containing styrene-acrylic resins, acrylic resins, silicone-modified acrylic resins, An epoxy resin, a silicone resin, an acrylonitrile resin, etc. are mentioned. Among these, it is preferable to use a polyester resin. The softening point (Tm) of the binder resin is 100 to 160 ° C, preferably 110 to 140 ° C, and the glass transition point (Tg) is 50 to 90 ° C, preferably 60 to 80 ° C.

  The conductive material is not particularly limited. For example, REGAL330 (manufactured by Cabot), # 970 (manufactured by Mitsubishi Chemical), Ketjen Black EC (manufactured by Lion Oil & Fats), EC-DJ500 (manufactured by Lion Oil & Fats), Mogul Carbon black such as L (manufactured by Cabot) can be used. The content of the conductive material is 0.1 to 5 parts by weight, preferably 1 to 3 parts by weight with respect to 100 parts by weight of the binder resin.

  The fluidizing agent improves the uniformity of mixing during carrier production. The fluidizing agent is not particularly limited as long as it is an inorganic fine particle having an average primary particle size of 10 to 100 nm, preferably 15 to 50 nm. For example, silica, titanium dioxide, amyrna, magnesium fluoride, silicon carbide, carbonization Boron, titanium carbide, zirconium carbide, boron nitride and the like can be used. The content of the fluidizing agent is 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight with respect to 100 parts by weight of the binder resin.

  As a surface modification device for surface treatment, for example, a surfing system (manufactured by Nippon Pneumatic Industry Co., Ltd.), a mechano-fusion system (manufactured by Hosokawa Micron Co., Ltd.), a hybridization system (manufactured by Nara Machinery Co., Ltd.), or the like can be used. preferable. Among the surface modification devices described above, the surfing system (manufactured by Nippon Pneumatic Kogyo Co., Ltd.) is most preferable in that the sphericity can be largely controlled. The apparatus setting conditions are appropriately determined depending on the type of binder resin used.

  The coating type carrier can be obtained, for example, by dissolving a coating resin in a solvent and spraying the resin solution onto a carrier base material with a Spiracoater (Okada Seiko Co., Ltd.). As the coating resin, the same resin as the binder resin of the binder-type carrier can be used. As the carrier base material, one having the same configuration as that of the binder type carrier described above may be used, or magnetic particles may be used as they are. The magnetic particles as the carrier base material may be any known magnetic material, such as ferrite, magnetite, iron powder, and the like. Preferably, ferrite is used.

  The means for coating the carrier base material with the coating resin is not limited to the method using the above-described spira coater. For example, the spray drying method, the dipping method, the fine particles are attached by impact force and thermal energy, and the film is formed. A method such as dry coating may be employed. Particularly preferably, a dry coating method that does not use a solvent and has a high yield of an effective resin coating amount is used.

  For example, when the carrier base material is magnetic particles, the coating amount of the coating resin in the coating type carrier is usually 0.5 to 5.0% by weight, preferably 1.0 to 4.0% with respect to the carrier base material. % By weight.

  The volume average particle size of the carrier used in the present invention is 20 to 100 μm, preferably 25 to 50 μm.

  The toner includes toner particles containing at least a resin and a colorant and external additives externally added to the toner particles, and at least specific titanic acid compound particles are used as the external additive.

  The titanic acid compound particles have a number average particle size of 120 to 550 nm, preferably 150 to 500 nm, and an iron element content of 0.01 to 0.12% by weight, preferably 0.01 to 0.10%. % Is used. By using a specific toner using such titanic acid compound particles in combination with a specific developing roller and carrier, not only toner scattering but also image memory generation can be suppressed. Although the details of the mechanism by which such an effect can be obtained are not clear, the above-described titanic acid compound particles promote moderate charge leakage of the carrier, and the carrier can retain an appropriate charge. It is considered that the generation of image memory can be suppressed.

  Specifically, first, the generation mechanism of image memory and toner scattering is considered to be based on the following mechanism. When an image having a solid portion is developed, the carrier in the region corresponding to the solid portion on the developing roller has a charge opposite to that of the toner after supplying the toner to the electrostatic latent image carrier. If the charge of such a carrier is not properly leaked, the charge held by the carrier is excessively large. Therefore, when the toner is supplied for the next image formation, the toner is electrically held relatively firmly. It becomes like this. As a result, it is considered that the carrier in the area corresponding to the solid part hardly provides the holding toner in the development area, the corresponding area of the solid part becomes a relatively low density portion, and the image memory is generated. In particular, when an oscillating electric field (AC electric field) is formed in the developing area, generally, toner is urged by the oscillating electric field in the developing area and temporarily moves between the developing roller and the electrostatic latent image carrier, and then the electrostatic latent image is transferred. Move to the image carrier. However, if the carrier in the solid portion corresponding area holds a relatively large charge, the toner movement to the electrostatic latent image carrier is hindered by the influence of the charge, and the toner in the developing area is, for example, on the surface of the developing roller. Since it moves, it is considered that the image memory is generated more remarkably. On the other hand, if the carrier leaks excessively and the charge held by the carrier becomes excessively small, it becomes difficult to retain the toner on the carrier, and toner scattering occurs. In the present invention, since the carrier leaks moderately and retains a proper charge, it is possible to simultaneously suppress toner scattering and image memory generation.

  If the number average particle diameter of the titanic acid compound particles is too small, the carrier is less likely to leak charges, so that the retained charge of the carrier becomes excessively high and image memory is likely to occur. On the other hand, if the number average particle diameter is too large, the carrier is liable to leak charge, so the retained charge of the carrier becomes excessively low and toner scattering tends to occur.

  If the content of iron element in the titanic acid compound particles is too small, the leak point for leaking the carrier charge will decrease, and the carrier will not leak easily, so the carrier charge will be excessively high and image memory will be generated easily. Become. On the other hand, if the iron element content is too high, the leak point for leaking the carrier charge increases, and the carrier is liable to leak the charge, so that the retained charge of the carrier becomes excessively low and toner scattering tends to occur.

The number average particle diameter of the external additive is specifically measured by the following method.
Take a 30,000 times photograph of the toner with a scanning electron microscope, and capture this photographic image with a scanner. The image processing analyzer LUZEX AP (manufactured by Nireco) binarizes the external additive present on the toner surface of the photographic image, and calculates the horizontal ferret diameter for 100 external additives. The average value is the number average particle diameter.

The iron element content uses a value measured by fluorescent X-ray analysis, and can be measured by the following method using, for example, XRF-1700 manufactured by Shimadzu Corporation.
As a specific measuring method, 3 g of the sample was pressurized and pelletized, and measurement was performed under the following conditions by qualitative analysis. For measurement, the Kα peak angle of the element to be measured was determined from the 2θ table and used.
X-ray generation part condition / target Rh, tube voltage 40 kV, tube current 95 mA, no filter Spectroscopic condition / slit standard, attenuator none, spectral crystal (Fe = LiF, Cl = Ge, Ca = LiF)
Detector (Fe = SC, Cl = FPC, Ca = FPC)
The ratio of the chlorine amount to iron was calculated as a value obtained by dividing the value of the Net intensity of the ClKα analytical line by the value of the Net intensity of the FeKα analytical line.

  The titanate compound particles used in the present invention are particles in which an iron element is contained in a titanate compound. Examples of the titanate compound constituting the titanate compound particles include calcium titanate, potassium titanate, magnesium titanate, barium titanate, and strontium titanate.

Such titanic acid compound particles can be produced, for example, by the following method.
In a conventionally known method for producing a titanic acid compound, an iron element supply source is added to these raw materials. For example, titanium oxide (IV) hydrate (TiO ₂ .H ₂ O) is obtained through hydrolysis by the so-called sulfuric acid method and taking the form of hydrate called metatitanic acid. Such a titanium oxide (IV) hydrate, a carbonate such as calcium carbonate, and an iron element supply source are mixed, and an alkaline aqueous solution is added and reacted while heating the mixed solution, and then a baking treatment is performed. . As the iron element supply source, for example, ferric chloride, ferrous sulfate and the like can be used.
In the said method, the iron element content in a titanic acid compound particle is controllable by adjusting the addition amount of an iron element supply source. For example, when the amount added is increased, the iron element content increases, and when the amount is decreased, the iron element content decreases. "

  The amount of titanic acid compound particles is not particularly limited as long as the object of the present invention is achieved, and is preferably 0.2 to 2.0% by weight, more preferably 0.4 to 1.% by weight based on the toner particles. 2% by weight.

In addition to the titanate compound particles, other external additives may be added to the toner particles. Such other 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 subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent or the like. 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.
The addition ratio of the other external additives is 0.1 to 5.0% by weight, preferably 0.5 to 4.0% by weight, based on the toner particles. Various external additives may be used in combination.

  The toner particles to which external additives including at least titanic acid compound particles are externally added contain at least a resin and a colorant, and may further contain other additives such as a release agent as required. In the present invention, it is particularly preferable that the toner particles contain a color colorant other than the black colorant.

  The toner particles may be produced by any method. For example, known toner particle granulation methods such as a pulverization method, an emulsification dispersion method, an emulsion polymerization association method, and a suspension polymerization method can be employed, and are not particularly limited. In the present invention, it is preferably obtained by an emulsion polymerization association method from the viewpoint of production cost and ease of production.

As an example of using the emulsion polymerization association method as a method for producing toner particles, the method includes the following steps.
(1) Dissolution / dispersion step of dissolving or dispersing a toner particle constituent material such as a release agent, a colorant and, if necessary, a charge control agent in a polymerizable monomer to obtain a polymerizable monomer solution;
(2) a polymerization step in which a polymerizable monomer solution is converted into oil droplets in an aqueous medium and a dispersion of binder resin fine particles is prepared by a miniemulsion method;
(3) Aggregation / fusion process (association process) in which binder resin fine particles are salted out, aggregated, and fused in an aqueous medium to form aggregated particles;
(4) An aging step of aging the aggregated particles with thermal energy to adjust the shape and obtaining a dispersion of toner particles;
(5) a cooling step of cooling the dispersion of toner particles;
(6) A filtration / washing step in which the toner particles are solid-liquid separated from the dispersion of toner particles to which hydrochloric acid has been added, and hydrochloric acid, a surfactant, and the like are removed from the toner particles;
(7) A drying step of drying the washed toner particles (8) A step of adding an external additive to the dried toner particles.

Hereinafter, each step will be described.
(1) Dissolution / dispersion step;
This step is a step of preparing a polymerizable monomer solution by dissolving or dispersing toner particle constituent materials such as a release agent and a colorant in the polymerizable monomer. In the polymerizable monomer solution, an oil-soluble polymerization initiator described below and / or other oil-soluble components can be added.

(2) polymerization step;
In a preferred example of the polymerization step, the above polymerizable monomer solution is added to an aqueous medium containing a surfactant having a concentration equal to or lower than the critical micelle concentration, and mechanical energy is added to form oil droplets. Subsequently, a polymerization reaction is performed in the oil droplets by radicals from the water-soluble radical polymerization initiator. In the aqueous medium, resin particles may be added as core particles.

  In the polymerization step, binder resin fine particles containing a binder resin formed by polymerizing at least a polymerizable monomer are obtained. The binder resin fine particles may be colored or may not be colored. The colored binder resin fine particles can be obtained by polymerizing a monomer composition containing a colorant. In the case of using binder resin fine particles that are not colored, a dispersion of colorant fine particles is added to the dispersion of the binder resin fine particles in the aggregating step described later, and the binder resin fine particles and the colorant fine particles are combined. By aggregation, toner particles can be obtained. The binder resin fine particles may be composed of two or more layers made of binder resins having different compositions. In this case, the first resin particles prepared by a mini-emulsion polymerization process (first-stage polymerization) according to a conventional method. It is possible to employ a method in which a polymerization initiator and a polymerizable monomer are added to this dispersion, and this system is polymerized (second stage polymerization).

  “Aqueous medium” refers to a material whose main component (50% by mass or more) is water. Examples of components other than water include organic solvents that dissolve in water, such as methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Of these, alcohol-based organic solvents such as methanol, ethanol, isopropanol, and butanol, which are organic solvents that do not dissolve the resin, are particularly preferable.

  The method of dispersing the polymerizable monomer solution in the aqueous medium is not particularly limited, but a method of dispersing by mechanical energy is preferable, and as a disperser for dispersing oil droplets by mechanical energy. Is not particularly limited, for example, a stirring device “CLEARMIX” (manufactured by M Technique Co., Ltd.) equipped with a rotor that rotates at high speed, an ultrasonic disperser, a mechanical homogenizer, Manton Gorin and Examples thereof include a pressure homogenizer. The dispersed particle diameter is 10 to 1000 nm, preferably 30 to 300 nm.

(3) Aggregation / fusion process (association process);
In the agglomeration / fusion process, a dispersion of colorant fine particles is added to the dispersion of binder resin fine particles obtained by the above polymerization step if the binder resin fine particles are not colored. The resin particles are salted out, aggregated and fused together with the colorant particles in an aqueous medium. In the middle stage of the aggregation / fusion process, binder resin fine particles having different resin compositions can be added and aggregated. In the agglomeration / fusion step, internal additive particles such as a charge control agent can be fused together with the binder resin fine particles and the colorant fine particles.

A preferred agglomeration / fusion method is to add a salting-out agent composed of an alkali metal salt and / or an alkaline earth metal salt in a water-based medium in which the binder resin fine particles and the colorant fine particles are present at a critical aggregation concentration or more. It is added as a flocculant and then heated to a temperature equal to or higher than the glass transition temperature of the binder resin fine particles and equal to or higher than the melting peak temperature of the release agent to be used. This is a process of fusing.
In this aggregation / fusion process, it is necessary to quickly raise the temperature by heating, and the temperature raising rate is preferably 1 ° C./min or more. The upper limit of the rate of temperature rise is not particularly limited, but is preferably 15 ° C./min or less from the viewpoint of suppressing the generation of coarse particles due to rapid salting-out, aggregation and fusion.
Further, after the dispersion of the binder resin fine particles and the colorant fine particles reaches a temperature equal to or higher than the glass transition temperature and equal to or higher than the melting peak temperature of the release agent, the temperature of the dispersion is maintained for a predetermined time, thereby allowing salting out. It is important to continue aggregation and fusion. As a result, toner particle growth (aggregation of binder resin fine particles and colorant fine particles) and fusion (disappearance of the interface between the particles) can be effectively advanced, and the durability of the finally obtained toner can be improved. Can be improved.

  The dispersion of the colorant fine particles can be prepared by dispersing the colorant in an aqueous medium. The dispersion treatment of the colorant fine particles 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 fine particles is not particularly limited, but preferably an ultrasonic disperser, a mechanical homogenizer, a pressure disperser such as a manton gourin or a pressure homogenizer, a sand grinder, a Getzmann mill or a diamond fine mill. Media type dispersers. The colorant fine particles may be surface-modified. Specifically, the colorant fine particles are dispersed in a solvent, the surface modifier is added to the dispersion, and the reaction is performed by heating the system. After completion of the reaction, the colorant fine particles are separated by filtration, washed and filtered with the same solvent, and dried to obtain colorant fine particles treated with the surface modifier.

(4) Aging process;
The aging step is preferably performed by thermal energy (heating). Specifically, by heating and stirring a system containing aggregated particles, toner particles are adjusted by adjusting the heating temperature, stirring speed, and heating time until the shape of the aggregated particles reaches a desired average circularity. . In this ripening step, the toner particles may be used as core particles, and binder resin fine particles may be further added and adhered and fused to the core particles, thereby obtaining a core-shell structure. In this case, it is preferable that the glass transition temperature of the binder resin fine particles constituting the shell layer is higher by 20 ° C. or more than the glass transition temperature of the binder resin fine particles constituting the core particle.

  In addition, the binder resin fine particles used in the agglomeration / fusion process described above are a resin (hydrophilic resin) made of a polymerizable monomer having an ionic dissociation group, which will be described later, and a polymerization having no ionic dissociation group In the case of being configured to contain a resin (hydrophobic resin) that uses only a hydrophilic monomer as a raw material, in this aging step, the hydrophilic resin is on the surface of the aggregated particles, and the hydrophobic resin is on the aggregated particles. The toner particles having a core-shell structure can be formed by orienting to the inner side of the toner.

(5) cooling step;
The cooling step is a step of cooling the toner particle dispersion. The cooling rate in the cooling process is 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) Filtration and washing process;
In the filtration / washing process, the toner particles are separated from the dispersion of hydrochloric acid-treated toner particles by solid-liquid separation and filtered, and the filtered toner particles (cake-like aggregates) are separated from the surfactant and A cleaning treatment is performed to remove deposits such as a salting-out agent and the alkali agent used in the aging step.

The washing treatment is performed by washing 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;
In this step, the washed toner cake is dried to obtain dried toner particles. 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 toner particles is preferably 5% by mass or less, and more preferably 2% by mass or less. In addition, when the toner particles subjected to the drying treatment 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.

  The toner particles obtained by the above method are added with the above-mentioned external additives and mixed to obtain the toner used in the present invention. As the mixing device, a mechanical mixing device such as a Henschel mixer or a coffee mill can be used.

Next, materials constituting the toner particles will be described.
[Binder resin]
As the resin constituting the toner of the present invention, a resin that is relatively negatively charged with respect to the toner is preferably used. When the toner particles constituting the toner of the present invention are produced by suspension polymerization method, miniemulsion polymerization aggregation method, emulsion polymerization association method, etc., as a polymerizable monomer 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, 2,4- Styrene or styrene styrene such as dimethyl styrene, p-tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene Derivatives: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isoprene methacrylate Methacrylic acid such as pill, 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 Acrylate derivatives such as phenyl acrylate; olefins such as ethylene, propylene, isobutylene; vinyl chloride, vinylidene chloride, vinyl bromide, vinyl fluoride, fluoride Vinyl halides such as vinylidene; vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl ketones such as vinyl methyl ketone, vinyl ethyl ketone and vinyl hexyl ketone N-vinyl compounds such as N-vinylcarbazole, N-vinylindole and N-vinylpyrrolidone; Vinyl compounds such as vinylnaphthalene and vinylpyridine; Acrylic acid or methacrylic acid derivatives such as acrylonitrile, methacrylonitrile and acrylamide And vinyl monomers such as These polymerizable monomers can be used alone or in combination of two or more.

  It is preferable to use a combination of polymerizable monomers having an ionic dissociation group. 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 a suspension polymerization method, a miniemulsion polymerization aggregation method or an emulsion polymerization association method, the surfactant used for obtaining a 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 association, 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 miniemulsion polymerization aggregation method or the emulsion polymerization aggregation method, a water-soluble radical polymerization initiator can be used, and as the water-soluble radical polymerization initiator, persulfates such as potassium persulfate and ammonium persulfate are used. Azobisaminodipropane acetate, azobiscyanovaleric acid and its salt, 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 the suspension polymerization method, miniemulsion polymerization aggregation method or emulsion polymerization association method. 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.

〔Release agent〕
Examples of the release agent that can be used in the toner of the present invention include conventionally known release agents. Specifically, polyolefin waxes such as polyethylene wax and polypropylene wax, long chain hydrocarbon waxes such as paraffin wax and sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, trimethylolpropane. Tribehenate, pentaerythritol tetramyristate, pentaerythritol tetrastearate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellit Ester waxes such as acid tristearyl and distearyl maleate, amides such as ethylenediamine dibehenyl amide and trimellitic acid tristearyl amide Box, and the like.

  Melting | fusing point of a mold release agent is 40-160 degreeC normally, Preferably it is 50-120 degreeC, More preferably, it is 60-90 degreeC. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and stable toner image formation can be performed without causing cold offset or the like even when fixing at a low temperature. Further, the content of the release agent in the toner is preferably 1 to 30% by weight, more preferably 5 to 20% by weight.

[Colorant]
As the colorant, 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.

  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.

  The content of the colorant is not particularly limited, and for example, 3 to 12 parts by weight, particularly 4 to 8 parts by weight is preferable with respect to 100 parts by weight of the resin constituting the toner particles.

  The number average particle diameter of the toner is not particularly limited, and is usually 4 to 10 μm, and particularly preferably 5 to 7 μm.

The toner has a static volume resistance value of 1 × 10 ^{10 to} 9 × 10 ¹² Ω · cm, particularly 2 × 10 ¹⁰ to 8 × 10 ¹² Ω · cm, from the viewpoint of toner scattering and image memory suppression. Is preferred.

The static volume resistance value of the toner can be controlled by adjusting the amount of iron element contained in the titanate compound particles.
For example, when the iron element content of the titanate compound particles is increased, the static volume resistance value of the toner is decreased. On the other hand, when the content of iron element in the titanate compound particles is reduced, the static volume resistance value of the toner is increased.

The static volume resistance value of the toner is also called a volume specific resistance value, and was measured by the following method using an apparatus (TR86111A DIGITAL HIGH MEGOHMMETER manufactured by TAKEDA RIKEN) having a configuration schematically shown in FIG. The value is used.
First, 2 g of toner and 48 g of standard low resistance silicone-coated carrier particles for evaluation (number average particle diameter: 60 μm, 1 × 10 ¹⁰ Ω · cm) are mixed to prepare a resistance measurement sample.
Next, the measurement sample is set in the apparatus shown in FIG. Reference numeral 31 is a load unit, 32 is a measurement sample, 33 is the height of the sample, 34 is a main body cell, 35 is a high voltage power source, and 36 is a resistance measuring instrument. It is calculated by the following calculation formula from the value after 530 seconds from the start of measurement at an applied voltage of 500 V at a load of 1400 g (measuring environment: 20 ° C., 50% RH). The sample amount is 1 g, and the measured value area is 0.968 cm ² .
Volume resistivity = {resistance (Ω) × area (cm ² )} / sample height (cm)

  The ratio of toner to carrier in the developer is usually from 4/96 to 8/92, preferably from 5/95 to 7/93, by weight.

A specific example of the developing method will be described with reference to FIG.
By mechanically stirring the developer 2 composed of toner and carrier in the developing device 10, the toner and carrier are brought into frictional contact with each other to precharge the toner. When the electrostatic latent image is formed on the surface of the electrostatic latent image carrier 3, the developing roller 1 is moved in the direction opposite to the electrostatic latent image carrier 3, that is, the developing roller 1 and the electrostatic latent image carrier 3 are It is rotated so as to move in the same direction as the electrostatic latent image carrier 3 in the opposite development area 4. At this time, with the rotation of the developing roller 1, the developer 2 accommodated in the developing device 10 is conveyed to the developing region 4 in the state of a magnetic brush by the magnetic action of the magnet roller 9 provided in the developing roller 1. .

  A developing bias power source 8 is connected to the developing roller 1, and a DC voltage is applied from the developing bias power source 8, so that a potential difference between the electrostatic latent image on the surface of the electrostatic latent image carrier 3 and the developing roller surface is obtained. The toner is moved from the developer on the surface of the developing roller 1 to the electrostatic latent image carrier 3. In the present invention, preferably, a developing bias in which an AC voltage and a DC voltage are superimposed is applied from the developing bias power source 8 to cause an oscillating electric field to act on the developing region. The development system may be a so-called reversal development system or a regular development system, and preferably employs a reversal development system.

In the upstream side in the conveyance direction of the developer 2 the developing region 4, the magnetic poles N ₁ and a position opposed to the magnet roller 9, as the regulating member 5 for regulating the amount of the developer 2 on the developing roller 1, the magnetic blade It is provided so as to be spaced from the developing roller 1 by a predetermined distance, and the amount of the developer 2 on the developing roller 1 is regulated by this magnetic blade.

  In the developing device 10, a toner containing portion 6 that contains toner T is provided on the upper portion thereof. When the toner concentration in the developer 2 in the developing device 10 is lowered, the toner containing portion 6 is contained in the toner containing portion 6. The stored toner T is supplied to the developer 2 in the developing device 10 by the supply roller 7.

(Carrier A)
(Career core manufacturing method)
Calcium carbonate, magnesium chloride and ferrous sulfate were added so that the blending ratios were Fe ₂ O ₃ = 60 mol% and MgO = 40 mol% to prepare a composition. 1% binder and water were added to make a 60% concentration slurry, and the mixture was pulverized with a wet ball mill, and dried particles with an average particle diameter of 35 μm were obtained with a spray dryer. Next, firing was performed at 1150 ° C. in an air atmosphere in a firing furnace, and pulverized sieving to obtain ferrite core particles (carrier matrix).
(Production method of resin-coated carrier)
100 parts by weight of the ferrite core particles and 3 parts by weight of copolymer resin fine particles of cyclohexyl methacrylate / methyl methacrylate (copolymerization ratio 5/5) were put into a high-speed mixer equipped with stirring blades and stirred at 120 ° C. for 30 minutes. After mixing, a resin coat layer was formed on the surface of the ferrite core particles by the action of mechanical impact force to obtain a carrier. The amount of the coating resin was 2.8% by weight with respect to the core particles. The volume average particle size was 35 μm.

(Carriers B to E)
Carriers B to E were obtained by the same method as the carrier A production method except that the amount of the copolymer resin fine particles used for the ferrite core particles was appropriately adjusted and the coating resin amount was controlled as described below. .
Amount of coating resin (value relative to core particles);
Carrier B = 4.5% by weight;
Carrier C = 2.0% by weight;
Carrier D = 2.0% by weight;
Carrier E = 1.3 wt%.

(Titanate compound particles A)
After desulfurizing the metatitanic acid dispersion prepared by the sulfuric acid method by adjusting the pH to 9.0 with a 4.0 mol / liter sodium hydroxide aqueous solution, a 6.0 mol / liter hydrochloric acid aqueous solution was added. The pH was adjusted to 5.5 and neutralized. Thereafter, water was added to the metatitanic acid cake prepared by filtering and washing the metatitanic acid dispersion to prepare a dispersion corresponding to 1.25 mol / liter in terms of titanium oxide TiO ₂ , and then 6.0. The pH was adjusted to 1.2 with a mol / liter hydrochloric acid aqueous solution. Then, the temperature of the dispersion was adjusted to 35 ° C., and stirred at this temperature for 1 hour to peptize the metatitanic acid dispersion.
Metatitanic acid corresponding to 0.156 mol in terms of titanium oxide TiO ₂ is collected from the metatitanic acid dispersion that has been subjected to the peptization treatment and charged into a reaction vessel, followed by calcium carbonate CaCO ₃ aqueous solution and second chloride. An aqueous iron solution was charged into the reaction vessel. Thereafter, a reaction system was prepared so that the titanium oxide concentration was 0.156 mol / liter. Here, calcium carbonate CaCO ₃ is added so that the molar ratio is 1.15 with respect to titanium oxide (CaCO ₃ / TiO ₂ = 1.15 / 1.00), and ferric chloride is added to titanium oxide. The molar ratio was 0.03 (FeCl ₃ / TiO ₂ = 0.03 / 1.00).

Nitrogen gas is supplied into the reaction vessel, and the reaction vessel is left in a nitrogen gas atmosphere by allowing it to stand for 20 minutes, and then a mixed solution composed of metatitanic acid, calcium carbonate, and ferric chloride is heated to 90 ° C. Warmed up. Subsequently, an aqueous sodium hydroxide solution was added over 24 hours until the pH reached 8.0, and then stirring was continued at 90 ° C. for 1 hour to complete the reaction.
After completion of the reaction, the inside of the reaction vessel was cooled to 40 ° C., and the supernatant was removed under a nitrogen atmosphere. Then 2500 parts by mass of pure water was put into the reaction vessel, and decantation was repeated twice. After carrying out decantation, the reaction system was filtered with Nutsche to form a cake, and the obtained cake was heated to 110 ° C. and dried in air for 8 hours.

The obtained dried calcium titanate was put into an alumina crucible, dehydrated at 930 ° C. and fired. After the firing treatment, calcium titanate is put into water, wet-grinded with a sand grinder to obtain a dispersion, 6.0 mol / liter hydrochloric acid aqueous solution is added to adjust the pH to 2.0, Excess calcium carbonate was removed. After the removal treatment, a wet hydrophobization treatment was performed on calcium titanate using a silicone oil emulsion (dimethylpolysiloxane emulsion) “SM7036EX (manufactured by Toray Dow Corning Silicone Co., Ltd.)”. In the hydrophobization treatment, 0.7 parts by mass of the silicone oil emulsion is added to 100 parts by mass of calcium titanate solid content, and the mixture is stirred for 30 minutes.
After the wet hydrophobization treatment, 4.0 mol / liter sodium hydroxide aqueous solution is added, pH is adjusted to 6.5, neutralization treatment is performed, followed by filtration and washing, and drying at 150 ° C. Processed. Furthermore, the pulverization process was performed for 60 minutes using the mechanical grinder, and the "titanate compound particle A" which is a calcium titanate containing an iron element was produced. The iron element content was 0.05% by weight.

(Titanic acid compound particles BK)
The amount of ferric chloride was appropriately adjusted to control the iron element content to a predetermined value, and the wet pulverization treatment conditions by a sand grinder were appropriately adjusted to control the particle size to a predetermined value. The titanate compound particles B to K were obtained by the same method as the production method of the titanate compound particles A.

(Manufacture of toner particles)
[Production of resin particle dispersion A]
(First stage polymerization)
A solution in which 8 parts by mass of sodium dodecyl sulfate was dissolved in 3000 parts by mass of ion-exchanged water was charged into a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device, and stirred at a stirring speed of 230 rpm in a nitrogen stream. However, the internal temperature was raised to 80 ° C. After the temperature rise, a solution in which 10 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added, the temperature was again set to 80 ° C., 480 parts by mass of styrene, 250 parts by mass of n-butyl acrylate, 68. Polymerization is performed by adding a polymerizable monomer solution consisting of 0 parts by mass and 16.0 parts by mass of n-octyl-3-mercaptopropionate over 1 hour, followed by heating and stirring at 80 ° C. for 2 hours. A resin particle dispersion (1H) containing resin particles (1h) was prepared.

(Second stage polymerization)
A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with a solution prepared by dissolving 7 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 800 parts by mass of ion-exchanged water, and the temperature reached 98 ° C. After heating, 260 parts by mass of the above resin particle dispersion (1H), 245 parts by mass of styrene, 120 parts by mass of n-butyl acrylate, 1.5 parts by mass of n-octyl-3-mercaptopropionate, a release agent ( 64 parts by mass of pentaerythritol tetrabehenate) is added and dispersed for 1 hour by a mechanical disperser “CREARMIX” (manufactured by M Technique Co., Ltd.) having a circulation path, and a dispersion containing emulsified particles (oil droplets) Was prepared.
Next, an initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water is added to the dispersion, and polymerization is performed by heating and stirring the system at 82 ° C. for 1 hour. A resin particle dispersion (1HM) containing resin particles (1 hm) was prepared.

(3rd stage polymerization)
A solution prepared by dissolving 11 parts by mass of potassium persulfate in 400 parts by mass of ion-exchanged water was added to the resin particle dispersion (1HM), and 435 parts by mass of styrene and 130 n-butyl acrylate were obtained at a temperature of 82 ° C. The polymerizable monomer solution which consists of a mass part, 33 mass parts of methacrylic acid, and 8 mass parts of n-octyl-3-mercaptopropionate was dripped over 1 hour. After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28 ° C. to obtain a resin particle dispersion A containing resin particles a. When the particle diameter of the resin particles in this resin particle dispersion A was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), the volume-based median diameter was 150 nm. Moreover, it was 45 degreeC when the glass transition temperature of this resin particle was measured.

[Production of dispersion of colorant fine particles]
While stirring a solution prepared by dissolving 90 parts by mass of sodium dodecyl sulfate in 1600 parts by mass of ion-exchanged water, 400 parts by mass of “Pigment Red 57: 1” was gradually added. A dispersion liquid Q of colorant fine particles was prepared by performing a dispersion treatment using a technique manufactured by Technic Co., Ltd. The particle diameter of the colorant fine particles in the dispersion liquid Q of the colorant fine particles was measured using an electrophoretic light scattering photometer “ELS-800” (manufactured by Otsuka Electronics Co., Ltd.), and the volume-based median diameter was 110 nm. It was.

[Production of Toner Particles 1]
In a reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device, 300 parts by mass of resin particle dispersion A, 1400 parts by mass of ion-exchanged water, and dispersion Q of colorant fine particles are converted into solid content. A solution prepared by dissolving 120 parts by mass and 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 120 parts by mass of ion-exchanged water was prepared, and after adjusting the liquid temperature to 30 ° C., a 5N sodium hydroxide aqueous solution was added. In addition, the pH was adjusted to 10. Next, an aqueous solution in which 35 parts by mass of magnesium chloride was dissolved in 35 parts by mass of ion-exchanged water was added over 10 minutes at 30 ° C. with stirring, and the temperature was increased after holding for 3 minutes. Over 90 ° C., and the particle growth reaction was continued while maintaining 90 ° C. In this state, the particle size of the agglomerated particles is measured with “Coulter Multisizer 3” (manufactured by Coulter Inc.). When the desired particle size is reached, 150 parts by mass of sodium chloride is dissolved in 600 parts by mass of ion-exchanged water. The aqueous solution was added to stop the particle growth, and the mixture was heated and stirred at a liquid temperature of 98 ° C. as an aging step, so that the average circularity was 0.965 as measured by “FPIA-2100” (manufactured by Sysmec). The toner particles having a core-shell structure were formed by orienting the hydrophilic resin to the surface side of the aggregated particles and the hydrophobic resin to the inner side of the aggregated particles while proceeding with the fusion between the particles. . The aqueous solution of toner particles produced in the above process is solid-liquid separated with a basket type centrifuge “MARK III model number 60 × 40” (Matsumoto Machine Co., Ltd.) to form a wet cake of toner particles. The wet cake was washed with ion exchange water at 45 ° C. until the electric conductivity of the filtrate reached 5 μS / cm with the basket-type centrifuge, and then transferred to “flash jet dryer” (manufactured by Seishin Enterprise Co., Ltd.). The toner was dried until the amount became 0.5% by mass to obtain “toner particles 1”. The number average particle diameter was 6.5 μm.

(Manufacture of developing roller)
The outer peripheral surface of an aluminum alloy cylindrical tube having an outer diameter of 20 mm was polished to achieve a predetermined surface roughness, the magnet and the shaft unit were fixed inside, and a developing roller was manufactured.

(Example / Comparative Example)
As shown in Table 1, a predetermined carrier and a toner having predetermined titanic acid compound particles were mixed for 1 hour using a roll mill to obtain a two-component developer. The toner mixing ratio in the developer was 7% by weight. The obtained developer and a predetermined developing roller were mounted on an MFP (bizhub C550; manufactured by Konica Minolta) equipped with the developing device shown in FIG. 1 and evaluated.
In the toner, predetermined titanic acid compound particles are added to the toner particles 1 in a predetermined amount, and 1% by mass of hydrophobic silica (number average primary particle size = 12 nm) and hydrophobic titania (number average primary particles). (Diameter = 20 nm) 0.3% by mass was added and mixed by a Henschel mixer. The toner particles 1 did not change in shape and particle size due to the addition of hydrophobic silica and hydrophobic titanium oxide. The amount of titanic acid compound particles added is a value relative to the toner particles.

-Toner scattering amount 10,000 image charts with a printing rate of 6% were printed, the toner scattering collecting filter weight attached to the developing device was measured, and the toner scattering amount was measured. If the amount of scattering is 0.05 g or less, it is within a range where there is no practical problem.

-Image memory After printing an image having a solid part, a halftone image was printed. The image memory in the area corresponding to the solid portion was determined by the density difference. If the density difference is 0.03 or less, it is within a range where there is no practical problem.

1 is a schematic configuration diagram of an example of a developing device that employs a developing method according to the present invention. The schematic block diagram of the apparatus for measuring the dynamic current value of a carrier is shown. 1 is a schematic configuration diagram of an apparatus for measuring a static volume resistance value of toner. FIG.

Explanation of symbols

  1: developing roller, 2: two-component developer, 3: electrostatic latent image carrier, 4: developing area, 5: magnetic blade, 6: toner storage unit, 7: replenishing roller, 8: developing bias power source, 9: Magnet roller, 10: developing device, 12: aluminum sleeve, 13: aluminum tube, 14: DC power supply, 15: ammeter, 20: carrier, 31: load unit, 32: measurement sample, 33: sample height, 34 : Main body cell, 35: High-voltage power supply, 36: Resistance measuring device.

Claims (4)

A two-component developer composed of toner and a carrier is held on the developing roller, conveyed to a developing area facing the electrostatic latent image carrier, and the electrostatic latent image on the electrostatic latent image carrier is developed with the toner. A two-component development method comprising:
The developing roller is made of aluminum alloy,
The dynamic current value of the carrier is 0.1 to 1.0 μA,
The toner includes toner particles containing at least a resin and a colorant, and titanic acid compound particles having a number average particle diameter of 120 to 550 nm and an iron element content of 0.01 to 0.12 wt% which are externally added to the toner particles. A two-component developing method. The two-component developing method according to claim 1, wherein the toner has a static volume resistance value of 1 × 10 ^{10 to} 9 × 10 ¹² Ω · cm.   The two-component developing method according to claim 1 or 2, wherein an oscillating electric field is formed in a developing region where the developing roller and the electrostatic latent image carrier are opposed to each other.   The two-component developing method according to claim 1, wherein the developing roller has a surface roughness Rz of 5 to 20 μm.

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