JP2018155970A - Developing apparatus, image forming apparatus, image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause less removal of a coating layer from a carrier surface, prevent color contamination even when removed, have no problem in carrier adhesion, and provide stable image quality even in use over a long period of time.SOLUTION: A developing apparatus 40 includes a developer carrier and a developer regulation member, where a carrier contains core material particles and a coating layer, the coating layer contains a resin, carbon black, and two kinds of inorganic fine particles of inorganic fine particles A and inorganic fine particles B; in the coating layer, the inorganic fine particles A and the carbon black are present so as to have concentration gradient in a thickness direction of the coating layer; toward the surface side of the carrier, concentration of the inorganic fine particles A is high and concentration of the carbon black is low; in the coating layer, in a range from the surface of the coating layer on the surface side of the carrier to a depth of 0.1 μm, a volume content of the carbon black is 0% or more and 30% or less, and a developing bias that overlaps an AC component being a frequency of 5 kHz or more on a DC component is applied to the developer carrier.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a developing device, an image forming apparatus, and an image forming method.

In general, in image forming methods such as electrophotography and electrostatic photography, two components obtained by stirring and mixing a toner and a carrier to develop an electrostatic latent image formed on a latent image carrier. Developer is used.
The granular carrier used in the two-component development system is based on the carrier of the photoconductor, preventing the spent of toner on the carrier surface, forming a uniform surface of the carrier, preventing surface oxidation, preventing deterioration of moisture sensitivity, extending the life of the developer. For the purpose of protecting from scratches or wear, controlling the charge polarity or adjusting the charge amount, etc., studies have been made to improve durability by coating with an appropriate resin material (for example, patent documents) 1-11).

In order to further increase durability, Patent Document 12 discloses a resin layer containing a resin component obtained by crosslinking a thermoplastic resin and a guanamine resin and a charge control agent.
However, there is still a high demand for higher durability in the market, and further higher durability is required.

The resin-coated carrier has a drawback that an edge effect is likely to occur particularly in a solid image portion. In addition, the resin-coated carrier is likely to cause carrier adhesion to the non-image area due to electrostatic development. In order to solve this problem, for example, a resin-coated carrier in which conductive carbon is dispersed as a conductive agent in a carrier coating layer has been proposed (for example, Patent Document 13).
However, such a carrier, when used as a developer, due to friction or collision between the carriers or the toner, carbon or a resin piece containing carbon is detached from the carrier coating layer, adheres to the toner particles, It is developed as it is. This phenomenon does not pose a major problem when forming black characters and other copied images using black toner, but color turbidity in color toners, especially yellow toners, or white toners and developers combined with transparent toners ( It appears as a problem of color stains.

  Patent Documents 14 to 16 show carriers in which a conductive filler is contained in a carrier coating layer. These proposals are incomplete as a means for solving the problem of the color stain.

  Patent Document 17 proposes a carrier in which carbon black is contained in the inner layer and only the resin is coated in the outer layer, although the purpose is different. Patent Document 18 proposes a carrier in which the concentration of carbon black is given a gradient from the deep layer side to the surface layer side of the resin coating layer, and carbon black is not present in the outermost layer. However, in these carriers, the carrier resistance changes as the coating layer is scraped, and the image quality changes over time.

  Patent Document 19 proposes a carrier in which a layer containing carbon black is provided inside the coating layer, and a coating layer containing a white conductive agent is provided thereon. In such a carrier, the coating layer containing the white conductive agent is easily scraped, and if the layer containing carbon black is exposed after long-term use, toner contamination occurs.

  Furthermore, since Patent Documents 17 to 19 have a layered coating layer, the resistance between the layers tends to be high, and the counter charge at the time of toner detachment becomes excessive, so that the carrier adheres to the non-image part due to electrostatic development. It becomes easy to do.

  Therefore, there is little detachment of the coating layer from the surface of the carrier, and even if it is detached, no color stains occur, and there is no problem with carrier adhesion, and stable image quality is provided even when used for a long period of time. Means are sought.

  According to the present invention, there is little detachment of the coating layer from the surface of the carrier, and even if it is detached, no color smear is generated, and there is no problem with carrier adhesion, and stable image quality can be obtained even over a long period of use. It is an object to provide a developing device that can be provided.

Means for solving the problems are as follows. That is,
A developing device of the present invention is a developing device that contains a developer containing a carrier and a toner and develops an electrostatic latent image formed on an electrostatic latent image carrier using the developer.
A developer carrying member that faces the electrostatic latent image carrying member and conveys the developer;
A developer regulating member that regulates the amount of the developer carried on the developer carrying body;
With
The carrier contains core material particles and a coating layer covering the core material particles,
The coating layer contains a resin, carbon black, and two types of inorganic fine particles, inorganic fine particles A and inorganic fine particles B,
In the coating layer, the inorganic fine particles A and the carbon black exist with a concentration gradient in the thickness direction of the coating layer, and the concentration of the inorganic fine particles A increases toward the surface of the carrier, and the carbon The density of black is reduced,
In the coating layer, in the range of depth 0.0 μm to 0.1 μm from the surface of the coating layer on the surface side of the carrier, the volume content of the carbon black is 0% or more and 30% or less,
A developing bias for superimposing an alternating current component having a frequency of 5 kHz or more on the direct current component is applied to the developer carrying member.

  According to the present invention, there is little detachment of the coating layer from the surface of the carrier, and even if it is detached, there is no color smear, and there is no problem with carrier adhesion, and stable image quality even over a long period of use. Can be provided.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. FIG. 2 is an enlarged configuration diagram illustrating the developing device and the photoconductor provided in the image forming unit.

(Developer)
The present inventors have intensively studied to solve the above problems. As a result, the following knowledge was obtained. While coating carbon black with excellent resistance adjustment function in the coating layer of the developer carrier, the coating is released from the carrier when the coating layer is scraped by reducing the amount of carbon black as it approaches the surface layer in the coating layer The amount of carbon black contained in the component is reduced, and as a result, the occurrence of color stains on the toner can be suppressed.
In addition, in response to concerns that the electrical resistance near the surface layer is increased by reducing the amount of carbon black, the surface layer side is also increased by prescribing the conductive inorganic fine particles A so that the surface layer side with a smaller amount of carbon black increases. It is possible to achieve an electrical resistance equivalent to that of the deep layer where the concentration of carbon black is high.

From the viewpoint of suppressing color stains, the amount of carbon black on the outermost layer is ideally zero. However, since carbon black also has a particle size, in order to eliminate the carbon black of the outermost layer, it is necessary to form a thick coating layer that does not contain carbon black at all. Increased usage. In order to suppress color stains, it is preferable to use a light-colored substance as much as possible for the inorganic fine particles A. However, in many cases, the light-colored conductive material is made of rare earth, and from the viewpoint of resource protection, color stains are acceptable. If possible, it is preferable to suppress the use amount of the inorganic fine particles A without eliminating the carbon black existing on the surface of the carrier coating layer.
Based on this technical concept, the present inventors examined an appropriate ratio of the carbon black, and as a result, the carbon black was measured in volume within a range of 0.0 μm to 0.1 μm in depth from the surface layer of the carrier coating layer. It was concluded that the color contamination of the toner can be suppressed within an allowable range by suppressing the coating layer scraping speed due to the presence of the inorganic fine particles B even if the amount is about 30%.

However, the present inventors have found that such carriers may cause carrier adhesion to non-image areas due to electrostatic development.
Therefore, as a result of further intensive studies, when such a carrier is used, the carrier is attached by applying a developing bias that superimposes an AC component having a frequency of 5 kHz or more on the DC component to the developer carrier in the developing device. It was found that the above problem can be solved, and the present invention has been completed.

The developing device of the present invention is a developing device that contains a developer containing a carrier and a toner and develops the electrostatic latent image formed on the electrostatic latent image carrier using the developer.
The developing device includes a developer carrying body that faces the electrostatic latent image carrying body and conveys the developer, and a developer regulating member that regulates the amount of the developer carried on the developer carrying body. .
The carrier contains core material particles and a coating layer covering the core material particles.
The coating layer contains a resin, carbon black, and two types of inorganic fine particles, inorganic fine particles A and inorganic fine particles B.
In the coating layer, the inorganic fine particles A and the carbon black exist with a concentration gradient in the thickness direction of the coating layer, and the concentration of the inorganic fine particles A increases toward the carrier surface side, and the carbon The density of black is lowered.
In the coating layer, the volume content of the carbon black is 0% or more and 30% or less in the range of depth of 0.0 μm to 0.1 μm from the surface of the coating layer on the surface side of the carrier.
In the developing device, a developing bias that superimposes an AC component having a frequency of 5 kHz or more on a DC component is applied to the developer carrying member. There is no restriction | limiting in particular in the frequency of the said alternating current component, According to the objective, it can select suitably, For example, 5-60 kHz is mentioned, For example, 5-10 kHz is preferable.

In the present invention, the method for providing a gradient in the concentration of carbon black and inorganic fine particles A in the coating layer is not particularly limited, and examples thereof include the following method (1) or (2).
(1) A method of coating the core material particles of the carrier with a resin solution containing carbon black, inorganic fine particles A, and inorganic fine particles B many times, and the concentration of the inorganic fine particles A is lower as the concentration of carbon black is lower in the subsequent process. A method using a high resin solution,
(2) Using a plurality of spray coat nozzles, a resin solution containing carbon black is divided into a nozzle for spraying a resin solution containing carbon black and a nozzle for spraying a resin solution containing inorganic fine particles A. Of continuously increasing the spray rate of a resin solution containing inorganic fine particles A while continuously decreasing the spray rate of

  As a method for confirming the location of carbon black and inorganic fine particles A in the coating layer and the volume ratio in the vicinity of the surface layer, a conventionally known method can be used. For example, it can be confirmed by cutting the coating layer on the carrier surface with FIB (focused ion beam) and observing the cross section with SEM (scanning electron microscope) or EDX (energy dispersive X-ray spectroscopy). . An example is given below, but the present invention is not limited to this.

A sample is deposited on the carbon tape, and is coated with about 20 nm of osmium for surface protection and conductive treatment. FIB treatment is performed under the following conditions using Carl Zeiss (NVision 40 manufactured by SII).
[FIB processing conditions]
・ Acceleration voltage: 2.0 kV
・ Aperture 30μm
・ High Current ON
・ Detector SE2, InLens
・ No conductive treatment ・ W. D 5.0mm
・ Sample tilt 54 °
Using SEM observation and carbon mapping of elements under the following conditions using Thermo Fisher Scientific's electronically cooled SDD detector UltraDry (Φ30 mm ² ) and analysis software Thermo Fisher Scientific's NORAN System 6 (NSS) In addition, the location of the inorganic fine particles A and the exclusive area in the cross section near the surface layer are confirmed.
・ Acceleration voltage: 3.0 kV
・ Aperture 120μm
・ High Current ON
・ Conductive treatment Os
・ Drift correction available ・ W. D 10.0mm
・ Measuring method Area Scan
・ Accumulation time 10 sec
・ Total number of times 100 times ・ Sample tilt 54 °
The ratio of the volume of the carbon black in the vicinity of the surface layer of the carrier coating layer is 3/3 of the cross-sectional area of the carbon black with respect to the 3/2 power of the cross-sectional area in the range from the surface layer to a depth of 0.0 μm to 0.1 μm. Obtained by calculating the ratio of the square.

<Inorganic fine particles A>
As described above, the inorganic fine particles A play a role of ensuring the resistance adjusting function corresponding to the decrease in carbon black due to the concentration gradient. For that purpose, it is necessary to have a high electrical conductivity. The present inventors examined the powder specific resistance required for the inorganic fine particles A. As a result, it was concluded that the powder specific resistance of the inorganic fine particles A is preferably 250 Ω · cm or less, more preferably 200 Ω · cm or less, and particularly preferably 100 Ω · cm or less. If the powder specific resistance of the inorganic fine particles A is higher than 200 Ω · cm, a large amount of the inorganic fine particles A must be formulated in order to perform the resistance adjusting function, but in this case, spillage from the coating layer surface occurs. It becomes easy to do. When the inorganic fine particles A having a resistance adjusting function spill from the surface of the coating layer, the carrier resistance increases accordingly, and the carrier resistance changes at an early stage over time, and the image quality is stabilized. It becomes scarce.

The powder specific resistance is measured by the following method. Place a steel electrode on the bottom of a 1 inch inner diameter vinyl chloride tube, put 5 g of the sample in the vinyl chloride tube, and place the steel electrode on the top of the vinyl chloride tube. 2 mm thick Teflon plates are laid on the top and bottom of the electrode, and a load of 10 kg / cm ² is applied with a hydraulic press. An LCR meter (Yokogawa-HEWLETT-PACKARD 4261A) is connected under pressure. The resistance value r [Ω] immediately after connection is read, and the total length L [cm] is measured with a caliper. The powder specific resistance R is calculated by the following equation, where l is the total length when the sample is not filled.
R [Ω · cm] = (2.54 / 2) 2πr / (L−l)

As the inorganic fine particles A, existing materials and new materials can be used. By prescribing the inorganic fine particles B, the surface of the coating layer containing the inorganic fine particles A is kept from being scraped to a small extent. At that time, in order to minimize the toner color contamination by the inorganic fine particles A detached from the coating layer or the inorganic fine particles A contained in the detached coating layer, the inorganic fine particles A should be as white or colorless as possible. Is preferred. Examples of the material having a good color and conductive function include at least one of the following (i) to (iii) below.
(I) Fine particles of at least one of tungsten, indium, and phosphorus (ii) Fine particles of tin oxide doped with an oxide of at least one of tungsten, indium, and phosphorus (iii) At least one of tungsten, indium, and phosphorus Fine particles in which tin oxide doped with such oxide is provided on the surface of the base particles. As the base particles, conventionally existing or new materials can be used, and examples thereof include aluminum oxide and titanium oxide.

<Inorganic fine particle B>
By prescribing the inorganic fine particles B in the coating layer, durability against abrasion of the coating layer can be improved. The material is not particularly limited, but when a negatively charged toner is used, the use of a positively chargeable material for the inorganic fine particles B stabilizes the long-term charge imparting ability. Particularly preferred materials include barium sulfate, zinc oxide, magnesium oxide, magnesium hydroxide, and hydrotalcite.

The average particle diameter h of the inorganic fine particles B and the average thickness T of the coating layer preferably satisfy the following formula (1).
h / 2 ≦ T ≦ 3h / 2 Formula (1)

  By setting the average particle size of the inorganic fine particles B to 2/3 × (the thickness of the coating layer) or more, the probability that the inorganic fine particles B protrude from the surface of the coating layer increases. When the top of the inorganic fine particles protrudes from the coating layer, it functions as a spacer between the carriers or the container wall, the carrier between the carrier and the carrier when the carrier and the carrier are rubbed, The life of the coating layer can be extended. In addition, as described above, when the inorganic fine particles B have a positive charge imparting function and are used in a developer using a negatively charged toner, the contact probability of the inorganic fine particles B with the toner is increased, so from the viewpoint of the charge imparting function. Is also preferable. In addition, since the inorganic fine particle B having a thickness T of the coating layer that is more than half of the particle size of the inorganic fine particle B is firmly captured by the coating layer, the separation of the inorganic fine particle B is difficult to occur.

  The average particle diameter of the inorganic fine particles B can be measured using, for example, Nanotrac UPA series (manufactured by Nikkiso Co., Ltd.) before prescription. If it is after prescription, it can measure from the image by the SEM observation with the simpler apparatus similarly to the confirmation method of the location of carbon black and the inorganic fine particle A. Similarly, the thickness of the coating layer can be measured from an image obtained by SEM observation. However, since the inorganic fine particles A have individual differences from one particle to another and the coating layer thickness varies depending on the location, the number of particles is not limited to a single particle / one location, and there is no statistically problematic n number. Measure.

<Developer>
Hereinafter, the developer will be described.
The developer contains a carrier and a toner.
The mixing ratio of the toner and the carrier in the developer is not particularly limited and may be appropriately selected according to the purpose. However, the mass ratio of the toner to the carrier is preferably 1% to 10%.

<< Career >>
The carrier contains core material particles and a coating layer.

<<< Core particle >>>
The core particle is not particularly limited as long as it is a magnetic material, and can be appropriately selected according to the purpose. For example, the core particle can be appropriately selected from those known as two-component carriers for electrophotography according to the purpose. be able to. Examples thereof include ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; resin particles in which these magnetic materials are dispersed in a resin. Of these, Mn-based ferrite, Mn-Mg-based ferrite, Mn-Mg-Sr ferrite, and the like are preferable from the viewpoint of environmental considerations. Specifically, MFL-35S, MFL-35HS (manufactured by Powder Tech), DFC-400M, DFC-410M, and SM-350NV (manufactured by DOWA Electronics) are mentioned as suitable examples.

  The volume average particle size of the core particles is not particularly limited and may be appropriately selected depending on the intended purpose. From the viewpoint of carrier adhesion and prevention of carrier scattering, the volume average particle size is 20 μm or more. Preferably, from the viewpoint of preventing the occurrence of abnormal images such as carrier streaks and preventing deterioration in image quality, those having a thickness of 100 μm or less are preferable, and in particular, those having a thickness of 20 μm to 60 μm can be used to improve image quality in recent years. Therefore, it can respond more suitably. The volume average particle diameter can be measured using, for example, a Microtrac particle size distribution model HRA9320-X100 (manufactured by Nikkiso Co., Ltd.).

  The core particles preferably have a shape factor SF2 in the range of 120 to 160 and an arithmetic average surface roughness Ra in the range of 0.5 μm to 1.0 μm. By setting the core material shape within a specified range, it is possible to obtain a carrier that is particularly excellent in charging stability and resistance stability over time. Although the details of this reason are not clear, by setting the shape factor and arithmetic average surface roughness of the core material particles within the specified ranges, the carrier has an uneven size of an appropriate size, and thereby the toner spent on the carrier can be removed. This is because the effect of scraping is obtained, and the decrease in charge and increase in resistance due to spent can be prevented.

The shape factors SF1 and SF2 mean the following.
100 carrier particle images magnified 300 times using a FE-SEM (S-800) manufactured by Hitachi, Ltd. are sampled randomly, and the image information is, for example, an image analysis device (Luzex AP manufactured by Nireco) via an interface. The values obtained from the following formulas (1) and (2) are defined as shape factors SF1 and SF2.
SF1 = (L2 / A) × (π / 4) × 100 (1)
SF2 = (P2 / A) × (1 / 4π) × 100 (2)
In the formula, L is the absolute maximum length of the particle (the length of the circumscribed circle), P is the peripheral length of the particle, and A is the projected area of the particle.
The shape factor SF1 indicates the degree of roundness of the particles, and the shape factor SF2 indicates the degree of unevenness of the particles. The value of SF1 increases as the distance from the circle (spherical) increases. When the irregularities on the surface become severe, the value of SF2 increases.

The arithmetic average surface roughness Ra means the following.
Use OPTELICS C130 manufactured by LASERTEC, and after capturing an image with a magnification of 50x objective lens and Resolution 0.20 μm, the observation area is 10 μm × 10 μm centering on the apex of the core, and the number of cores is 100 Use the measured value.

<<< Coating layer >>>
The coating layer contains a resin, carbon black, and two types of inorganic fine particles, inorganic fine particles A and inorganic fine particles B, and further contains other components as necessary.

-Resin-
There is no restriction | limiting in particular as said resin, According to the objective, it can select suitably, For example, a silicone resin, an acrylic resin, etc. are mentioned.
These may be used individually by 1 type and may use 2 or more types together.

  The silicone resin and the acrylic resin are preferably used in combination. The acrylic resin has excellent adhesive properties due to its strong adhesiveness and low brittleness. On the other hand, its surface energy is high, so when it is combined with a toner that is easy to spend, the spent toner component accumulates. In some cases, this causes problems such as a decrease in charge amount. In this case, this problem can be solved by using together a silicone resin that has an effect that it is difficult to spend the toner component due to the low surface energy and the accumulation of the spent component is difficult to progress due to film scraping. However, since the silicone resin has weak adhesiveness and high brittleness, it also has a weak point that it has poor wear resistance. Therefore, it is important to obtain a good balance between the properties of these two resins. It is possible to obtain a coating film having wear characteristics. This is because the silicone resin has a low surface energy, so that it is difficult to spend the toner component, and it is difficult to accumulate the spent component due to film scraping.

  Silicone resin as used in this specification refers to all commonly known silicone resins, straight silicone consisting only of organosilosan bonds, silicone resins modified with alkyd, polyester, epoxy, acrylic, urethane, etc. However, it is not limited to this. Examples of commercially available straight silicon resins include KR271, KR255, and KR152 manufactured by Shin-Etsu Chemical, SR2400, SR2406, and SR2410 manufactured by Toray Dow Corning Silicon. In this case, it is possible to use the silicone resin alone, but it is also possible to simultaneously use other components that undergo a crosslinking reaction, charge amount adjusting components, and the like. Further, as modified silicone resins, KR206 (alkyd modified), KR5208 (acrylic modified), ES1001N (epoxy modified), KR305 (urethane modified) manufactured by Shin-Etsu Chemical, SR2115 (epoxy modified) manufactured by Toray Dow Corning Silicon Co., Ltd. , SR2110 (alkyd modified) and the like.

  The polycondensation catalyst used when using the silicone resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include titanium-based catalysts, tin-based catalysts, zirconium-based catalysts, and aluminum-based catalysts. In the present invention, among these various catalysts, titanium diisopropoxybis (ethyl acetoacetate) is most preferable as a catalyst among titanium-based catalysts that give excellent results. This is considered to be because the effect of promoting the condensation reaction of the silanol group is large and the catalyst is hardly deactivated.

  The acrylic resin referred to in this specification refers to all resins having an acrylic component, and is not particularly limited. In addition, it is possible to use the acrylic resin alone, but it is also possible to use at least one other component that undergoes a crosslinking reaction at the same time. Examples of other components that undergo a crosslinking reaction include amino resins and acidic catalysts, but are not limited thereto. The amino resin here refers to guanamine, melamine resin and the like, but is not limited thereto. Moreover, what has a catalytic action can be used with an acidic catalyst here. For example, it has a reactive group such as a fully alkylated type, a methylol group type, an imino group type, and a methylol / imino group type, but is not limited thereto.

Moreover, it is more preferable that the coating layer contains a cross-linked product of an acrylic resin and an amino resin. Thereby, fusion | melting of coating layers can be suppressed, maintaining moderate elasticity.
The amino resin is not particularly limited, but a melamine resin and a benzoguanamine resin are preferable because the charge imparting ability of the carrier can be improved. In addition, when it is necessary to appropriately control the charge imparting ability of the carrier, another amino resin may be used in combination with the melamine resin and / or the benzoguanamine resin.
As the acrylic resin capable of crosslinking with the amino resin, those having a hydroxyl group and / or a carboxyl group are preferred, and those having a hydroxyl group are more preferred. Thereby, adhesiveness with core material particle | grains or electroconductive fine particles can further be improved, and the dispersion stability of electroconductive fine particles can also be improved. In this case, the acrylic resin preferably has a hydroxyl value of 10 mgKOH / g or more, and more preferably 20 mgKOH / g or more.

The coating layer composition for forming the coating layer preferably contains a silane coupling agent. Thereby, electroconductive fine particles can be disperse | distributed stably.
The silane coupling agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include γ- (2-aminoethyl) aminopropyltrimethoxysilane and γ- (2-aminoethyl) aminopropyl. Methyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β- (N-vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane hydrochloride, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyl Trimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, γ-chloropropyltrimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3 -(G Methoxysilyl) propyl] ammonium chloride, γ-chloropropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyl Examples include diethoxysilane, 1,3-divinyltetramethyldisilazane, and methacryloxyethyldimethyl (3-trimethoxysilylpropyl) ammonium chloride.
These may be used individually by 1 type and may use 2 or more types together.

  Examples of commercially available silane coupling agents include AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, and sz6300. , Sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43-204M, AY43-048 , Z-6403, AY43-206M, AY43-206E, Z6341, AY43-210MC, AY43-083, AY43-101, AY43-013, AY43-158E, -6920, Z-6940 (Toray Silicone Co., Ltd.).

  The amount of the silane coupling agent added is preferably 0.1% by mass to 10% by mass with respect to the silicone resin.

<< Toner >>
The toner is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the toner contains at least a binder resin, and further includes a colorant, a release agent, a charge control agent, an external additive, if necessary. Contains other ingredients such as agents.

The toner may be any of monochrome toner, color toner, white toner, and transparent toner. The carrier used in the present invention is one of the purposes for suppressing the contamination of the toner by the carbon black, but the effect is as a developer combined with a color toner, particularly a yellow toner, or a white toner, a transparent toner. It is remarkable when using it.
The toner may contain a release agent for application to an oilless system in which toner fixing prevention oil is not applied to the fixing roller. Such a toner generally tends to cause filming. However, since the carrier used in the present invention can suppress filming, the developer used in the present invention has a good quality for a long period of time. Can be maintained.

<<< Binder resin >>>
There is no restriction | limiting in particular as said binder resin, According to the objective, it can select suitably, For example, styrene, such as polystyrene, poly p-styrene, polyvinyltoluene, and the homopolymer of the substitution product; Styrene-p- Chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid Acid methyl copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Polymer, styrene-vinyl methyl ketone copolymer, styrene-butyl Styrene copolymers such as diene copolymer, styrene-isoprene copolymer, styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, Examples include polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid, rosin, modified rosin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, and the like. .

The binder resin for pressure fixing is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene; ethylene-acrylic acid copolymers, ethylene-acrylic Olefin copolymers such as acid ester copolymers, styrene-methacrylic acid copolymers, ethylene-methacrylic acid ester copolymers, ethylene-vinyl chloride copolymers, ethylene-vinyl acetate copolymers, ionomer resins; epoxy resins , Polyester, styrene-butadiene copolymer, polyvinyl pyrrolidone, methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, and the like.
These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as content of the said binder resin in the said toner, According to the objective, it can select suitably.

<<< Colorant >>>
The colorant (pigment or dye) is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, and hansa yellow. G, Hansa Yellow 10G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake, etc. Yellow Molybdenum; Molybdenum Orange, Permanent Orange GTR, Pyrazolone Orange, Vulcan Orange, Indanthrene Brilliant Orange RK, Benzidine Orange G, Orange pigments such as Indanthrene Brilliant Orange GK; Bengala, Cadmium Red, Permanent Red 4R, Risor Red, Pyrazolone Red, Watching Red Calci Red pigments such as salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B; purple pigments such as fast violet B, methyl violet lake; cobalt blue, alkali blue, Victoria blue lake , Phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, indanthrene blue BC and other blue pigments; chrome green, chromium oxide, pigment green B, malachite green lake and other green pigments; carbon black, Azine dyes such as oil furnace black, channel black, lamp black, acetylene black, aniline black, metal salt azo dyes, metal oxides, complex metal acids Black pigments such things, and a white pigment such as titanium oxide.
These may be used individually by 1 type and may use 2 or more types together.
In the case of transparent toner, it may not be used.

  There is no restriction | limiting in particular as content of the said colorant in the said toner, According to the objective, it can select suitably.

<<< release agent >>>
The release agent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, and polyhydric alcohol wax. , Silicone varnish, carnauba wax, ester wax and the like.
These may be used individually by 1 type and may use 2 or more types together.

  There is no restriction | limiting in particular as content of the said mold release agent in the said toner, According to the objective, it can select suitably.

<<< Charge Control Agent >>>
There is no restriction | limiting in particular as said charge control agent, According to the objective, it can select suitably, For example, nigrosine; the azine dye which has a C2-C16 alkyl group (refer Japanese Patent Publication No.42-1627) ); C. I. Basic Yellow 2 (C.I. 41000), C.I. I. Basic Yellow 3, C.I. I. Basic Red 1 (C.I. 45160), C.I. I. Basic Red 9 (C.I. 42500), C.I. I. Basic Violet 1 (C.I. 42535), C.I. I. Basic Violet 3 (C.I. 42555), C.I. I. Basic Violet 10 (C.I. 45170), C.I. I. Basic Violet 14 (C.I. 42510), C.I. I. Basic Blue 1 (C.I. 42025), C.I. I. Basic Blue 3 (C.I. 51005), C.I. I. Basic Blue 5 (C.I. 42140), C.I. I. Basic Blue 7 (C.I. 42595), C.I. I. Basic Blue 9 (C.I. 52015), C.I. I. Basic Blue 24 (C.I. 52030), C.I. I. Basic Blue 25 (C.I. 52025), C.I. I. Basic Blue 26 (C.I. 44045), C.I. I. Basic Green 1 (C.I. 42040), C.I. I. Basic dyes such as Basic Green 4 (C.I. 42000); lake pigments of these basic dyes; I. Solvent Black 8 (C.I. 26150), quaternary ammonium salts such as benzoylmethylhexadecyl ammonium chloride and decyltrimethyl chloride; dialkyltin compounds such as dibutyl and dioctyl; dialkyltin borate compounds; guanidine derivatives; vinyl having an amino group Polyamine resins such as polycondensation polymers and condensation polymers having amino groups; described in JP-B-41-20153, JP-B-43-27596, JP-B-44-6397, and JP-B-45-26478 Metal complex salts of monoazo dyes; salicylic acids described in JP-B-55-42752 and JP-B-59-7385; dialkylsalicylic acid, naphthoic acid, dicarboxylic acid Zn, Al, Co, Cr, Fe, etc. Metal complexes of Emissions of copper phthalocyanine pigment; organic boron salts; fluorine-containing quaternary ammonium salts; calixarene compounds, and the like.
These may be used individually by 1 type and may use 2 or more types together.
For color toners other than black, white metal salts of salicylic acid derivatives are preferred.

  There is no restriction | limiting in particular as content of the said charge control agent in the said toner, According to the objective, it can select suitably.

<<< External additive >>>
The external additive is not particularly limited and may be appropriately selected depending on the intended purpose. For example, inorganic particles such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, boron nitride; soap-free emulsion polymerization method Resin particles such as polymethyl methacrylate particles and polystyrene particles having an average particle diameter of 0.05 μm to 1 μm obtained by the above method.
These may be used individually by 1 type and may use 2 or more types together.

  Among these, metal oxide particles such as silica and titanium oxide whose surfaces have been subjected to a hydrophobic treatment are preferable. Furthermore, by using a combination of hydrophobized silica and hydrophobized titanium oxide, the amount of added hydrophobized titanium oxide is higher than that of hydrophobized silica. A toner having excellent charging stability can be obtained.

  There is no restriction | limiting in particular as content of the said external additive in the said toner, According to the objective, it can select suitably.

<<< Toner Manufacturing Method >>>
The toner can be produced using a known method such as a pulverization method or a polymerization method. For example, when a toner is manufactured using a pulverization method, first, a melt-kneaded product obtained by kneading a toner material is cooled, pulverized, and classified to prepare base particles. Next, in order to further improve transferability and durability, an external additive is added to the base particles to produce a toner.

  At this time, the apparatus for kneading the toner material is not particularly limited, but a batch type two roll; Banbury mixer; KTK type twin screw extruder (manufactured by Kobe Steel), TEM type twin screw extruder (Toshiba Machine) A continuous twin screw extruder such as a twin screw extruder (manufactured by KCK), a PCM type twin screw extruder (manufactured by Ikegai Iron Works), a KEX type twin screw extruder (manufactured by Kurimoto Iron Works); Examples thereof include a continuous single-shaft kneader such as Ko Nida (manufactured by Buss).

Further, when the cooled melt-kneaded product is pulverized, it is roughly pulverized using a hammer mill, a rotoplex, etc., and then finely pulverized using a fine pulverizer using a jet stream, a mechanical pulverizer or the like. be able to. In addition, it is preferable to grind | pulverize so that an average particle diameter may be 3 micrometers-15 micrometers.
Furthermore, when classifying the crushed melt-kneaded material, a wind classifier or the like can be used. In addition, it is preferable to classify so that the average particle diameter of the base particles is 5 μm to 20 μm.
In addition, when an external additive is added to the base particle, the external additive adheres to the surface of the base particle while being pulverized by mixing and stirring using a mixer.

<Developer carrier>
The developer carrier is not particularly limited as long as it is a member that faces the electrostatic latent image carrier and conveys the developer, and can be appropriately selected according to the purpose. And a carrier that carries the developer on the surface and supplies the toner to the electrostatic latent image carrier. More specifically, for example, a roller-shaped developing roller may be used.

  There is no restriction | limiting in particular as a diameter of the said developing roller, Although it can select suitably according to the objective, 10-30 mm is preferable.

The magnetic field generating means is not particularly limited as long as it can generate a magnetic field, and can be appropriately selected according to the purpose.
Examples of the material of the magnetic field generating means include a magnet.
Examples of the magnet include a plastic magnet obtained by mixing magnetic powder and resin. Examples of the magnetic powder include Sr ferrite and Ba ferrite. Examples of the resin include PA (polyamide) materials such as 6PA and 12PA,
Ethylene polymers such as EEA (ethylene-ethyl copolymer) and EVA (ethylene-vinyl copolymer), chlorine-based materials such as CPE (chlorinated polyethylene), NBR (rubber-like copolymer of acrylonitrile and butadiene) ) And the like.
Examples of the shape of the magnetic field generating means include a rod shape.

<Developer regulating member>
The developer regulating member is not particularly limited as long as it is a member that regulates the amount of the developer carried on the developer carrying member, and can be appropriately selected according to the purpose. For example, a regulating blade Etc.
There is no restriction | limiting in particular as a magnitude | size of the said developer control member, According to the objective, it can select suitably.

  The number of the developer regulating members is not particularly limited as long as it is plural, and can be appropriately selected according to the purpose. Examples thereof include two, three, and four.

  The distance between the developer regulating member and the developer carrier is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 mm to 2.0 mm, preferably 0.3 mm to 1 0.0 mm is more preferable.

<AC component>
There is no restriction | limiting in particular as a means to apply an alternating current component to the said developer carrier, According to the objective, it can select suitably, For example, an alternating current power supply etc. are mentioned.

(Image forming apparatus and image forming method)
The image forming apparatus of the present invention has at least an electrostatic latent image carrier, a charging unit, an exposure unit, and a developing unit, and further, a transfer unit, a fixing unit, a neutralizing unit, a cleaning unit, if necessary. It has other means such as recycling means and control means.
The image forming method of the present invention includes at least a charging step, an exposure step, and a development step, and, if necessary, other processes such as a transfer step, a fixing step, a static elimination step, a cleaning step, a recycling step, and a control step. Process.

The charging means is means for charging the electrostatic latent image carrier.
The exposure means is means for forming an electrostatic latent image on the electrostatic latent image carrier.
The developing means is a means for developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image, the developing device according to the present invention. is there.
The transfer means is means for transferring the toner image formed on the electrostatic latent image carrier to a recording medium.
The fixing means is means for fixing the toner image transferred to the recording medium.

The charging step is a step of charging the electrostatic latent image carrier.
The exposure step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The developing step is a step of developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image, and the developing device according to the present invention. Done.
The transfer step is a step of transferring the toner image formed on the electrostatic latent image carrier to a recording medium.
The fixing unit is a step of fixing the toner image transferred to the recording medium.

In the present embodiment, the developer including the carrier and the toner described above is used in the trickle developing system as a replenishment developer and a developer for developing device, so that the carrier can be used even after a long period of use. Scraping of the surface and generation of toner spent on the carrier surface are prevented, and a decrease in the charge amount of the developer in the developer container and a decrease in the electric resistance value of the carrier are suppressed, so that stable development characteristics can be obtained. .
The configuration of the image forming apparatus used in the present invention is not particularly limited, and an image forming apparatus having another configuration can be used as long as it has a similar function. .

An example in which the present invention is applied to an electrophotographic copying machine as an image forming apparatus will be described.
First, the configuration and operation of the image forming apparatus according to the present embodiment will be described.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present embodiment. The image forming apparatus of FIG. 1 includes an image forming unit 1 in which four image forming units 11Y, 11M, 11C, and 11K are arranged in parallel. Drum-shaped photoconductors 18Y, 18M, 18C, and 18K as image bearing members, drum cleaning units 12Y, M, C, and K, charging units 13Y, M, C, and K, two-component developing type developing devices 40Y, M, and C , K, etc. are housed in a frame (not shown). These image forming units 11Y, 11M, 11C, and 11K can be attached to and detached from the copying machine main body so that consumable parts can be replaced at a time.

  Above the image forming unit 1, an exposure unit 9 is provided as a latent image forming unit. In addition, a reading device 10 that scans and reads a document placed on a contact glass is provided at the top of the device. Below the image forming unit 1, a transfer unit 2 including an intermediate transfer belt 15 as an intermediate transfer member is provided. The intermediate transfer belt 15 is stretched around a plurality of support rollers, and rotates in the clockwise direction in the drawing. A secondary transfer device 4 is provided below the transfer unit 2. The secondary transfer device 4 includes a secondary transfer roller 17, and the secondary transfer roller 17 abuts on the intermediate transfer belt 15 where the intermediate transfer belt 15 is wound around the transfer counter roller 16 from the belt front surface and performs secondary transfer. A nip is formed. A secondary transfer bias is applied to the secondary transfer roller 17 by a power source (not shown). The transfer counter roller 16 is electrically grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip.

  On the left side of the secondary transfer device 4 in the figure, a fixing unit 7 having a heating roller having a heating element therein is provided in order to fix the toner image transferred onto the paper. In addition, a conveyance belt 6 is provided between the secondary transfer device 4 and the fixing unit 7 to convey the sheet after transfer of the toner image to the fixing unit 7. A paper feeding unit 3 is provided below the apparatus for feeding paper that is separated and fed one by one from a paper feeding storage unit (not shown) to the secondary transfer device 4. In addition, a paper discharge unit 8 that transports the paper that has passed through the fixing unit 7 to the outside of the apparatus or to the duplex unit 5 is provided.

  When making a copy with this image forming apparatus, the reading apparatus 10 reads the document. In parallel with this document reading, the intermediate transfer belt 15 moves in the clockwise direction in the figure. At the same time, in the image forming unit 1, yellow, magenta, and magenta, based on the contents of the read original, are placed on the photoreceptors 18 Y, M, C, and K whose surfaces are charged by the charging units 13 Y, M, C, and K, respectively. A latent image is formed by exposure by the exposure unit 9 using cyan and black color-specific information. Next, the latent images on the photoconductors 18Y, 18M, 18C, and 18K are developed by the developing devices 40Y, 40M, 40C, and 40K to form single-color toner images (developed images). Then, the toner images on the photoconductors 18Y, 18M, 18C, and 18K are sequentially transferred so as to overlap each other on the intermediate transfer belt 15 to form a composite toner image on the intermediate transfer belt 15. The photosensitive members 18Y, 18M, 18C, and 18K after the transfer of the toner image are removed by the drum cleaning units 12Y, 12M, 12C, and 12K to remove residual toner remaining on the photosensitive members 18Y, 18M, 18C, and 18K. Prepare for image formation. In parallel with such toner image formation, the paper is fed out one by one from a paper feed accommodating portion (not shown), and abutted against the registration roller 14 and stopped. Then, the registration roller 14 is rotated in synchronization with the formation of the composite toner image on the intermediate transfer belt 15, the sheet is fed between the intermediate transfer belt 15 and the secondary transfer device 4, and is transferred by the secondary transfer device 4. Then, the toner image is transferred onto the paper. The sheet on which the toner image has been transferred is conveyed by the conveying belt 6 and sent to the fixing unit 7. The fixing unit 7 applies heat and pressure to fix the toner image, and then the sheet is sent to the paper discharge unit 8. The paper discharge unit 8 is switched by a switching claw and guided to a paper discharge tray (not shown) outside the apparatus (on the left side of the apparatus) or the duplex unit 5 below. In the duplex unit 5, the sheet is reversed and guided again to the secondary transfer position (nip position between the secondary transfer device 4 and the intermediate transfer belt 15). Eject onto the output tray. The intermediate transfer belt 15 after image transfer is removed by the intermediate transfer belt cleaning unit 90 to remove the residual toner remaining on the intermediate transfer belt 15 and prepare for image formation again.

  Here, in the image forming apparatus, from the viewpoint of reducing the size of the machine, the arrangement is such that the fixing unit 7 is pulled down to the lower side of the transfer unit 2 together with the higher density inside the machine. In the image forming apparatus of FIG. 1, the intermediate transfer belt 15 is bent so as to cover the upper surface and the right side surface of the fixing unit 7. With this configuration, the height direction and width direction of the apparatus are made compact. However, if the fixing unit 7 is brought close to the intermediate transfer belt 15, the intermediate transfer belt 15 may be deformed due to thermal influence by the fixing unit 7 serving as a heating element, and image defects such as color misregistration may occur. . This has become more prominent due to an increase in the amount of heat generated inside the apparatus as the speed of the apparatus increases. Further, during double-sided printing, the paper heated by the fixing unit 7 passes through the double-sided unit 5 and again contacts the intermediate transfer belt 15 at the secondary transfer position. Therefore, the intermediate transfer belt is further transferred by heat transfer from the paper. The temperature of 15 rises and becomes a more severe condition. Further, heat is also transmitted to the photosensitive members 18Y, 18M, 18C, and 18K that are in contact with the intermediate transfer belt 15, and further to the developing devices 40Y, M, C, and K, and image defects due to belt deformation, solidification of toner, and the like. Problems are more likely to occur. Therefore, a heat insulating device 20 is provided between the fixing unit 7 that is a heat source and the intermediate transfer belt 15 that is disposed in the vicinity of the fixing unit 7. Although the heat insulating device 20 is often composed of an air flow by a duct, here, a heat insulating device using a heat pipe will be described. This is mainly composed of a heat receiving plate 21, a heat pipe 22, a heat radiating plate 23, a duct 24 and an exhaust fan (not shown). The heat receiving plate 21 that is a heat receiving member is formed of a material that easily absorbs heat, and is disposed between the fixing unit 7 that is a heat generation source and the transfer unit 2 that is a protection target portion to be protected from the influence of the heat. . The heat pipe 22 as a heat transfer means (heat transport means) is attached to the lower surface of the heat receiving plate 21, and one end portion (lower end portion) side thereof is a heat receiving portion. The other end side of the heat pipe 22 is a heat radiating portion, and is mounted on the heat radiating plate 23 at a position higher than the heat receiving portion. The heat radiating plate 23 that is a heat radiating member is formed of a material that easily releases heat, and a heat sink may be provided as necessary. In this example, the duct 24 extends from the front surface to the back surface of the image forming apparatus main body, and is provided so that the heat radiating plate 23 is positioned inside the duct. An air inflow port is provided at the front side end of the duct 24, an exhaust port is provided at the back side end, and an exhaust fan (not shown) is provided at the exhaust port. The heat insulating device 20 configured as described above receives heat from the heat generating portion (the fixing unit 7 in this example) by the heat receiving plate 21, and the heat is transferred to the heat radiating portion (heat radiating plate 23) by the heat pipe 22 serving as heat transfer means. Transported up to. Then, heat is released from the heat radiating plate 23 in the duct 24, and the released heat is discharged outside the apparatus by an exhaust fan (not shown). Note that it is possible to perform natural cooling without providing an exhaust fan.

  In this way, the influence of the fixing heat is cut off, and the image forming units 11Y, 11M, 11C, and 11K, and the transfer unit 2 that are the protection targets are effectively protected, thereby preventing color misregistration due to deformation of the intermediate transfer belt 15 and the like. The occurrence of troubles and troubles due to toner solidification is prevented in advance.

  In the developing devices 40Y, 40M, 40C, and 40K, when the developer stirring and conveying member that stirs and conveys the developer contained in the developer container in the developing device 40 is driven, The temperature in the developing device 40 is increased by frictional heat due to rubbing with the developer and frictional heat due to rubbing between the developers. In addition, the friction heat generated by the friction between the developer regulating member and the developer that regulates the layer thickness of the developer carried on the developer carrying body before the developer is transported to the developing area, and the developer regulating member. The temperature in the developing device 40 is raised by frictional heat due to rubbing between the developers at the time of regulation. When the temperature in the developing device 40 rises, the charge amount of the toner decreases, the toner adhesion amount increases, and a predetermined image density cannot be obtained. Further, the toner may melt due to the temperature rise and adhere to the developer regulating member, the developer carrying member, the photosensitive member, etc., and a streaky abnormal image may be generated in the image. In recent years, when a toner having a low melting temperature is used in order to reduce the fixing energy, an abnormal image or the like is likely to occur due to toner fixation. In addition, the development device 40 is likely to become hot due to the increase in printing speed. Therefore, the developing devices 40Y, M, C, and K are very important cooling parts for achieving high image quality and high reliability. For this reason, in the copying machine of the present embodiment, a large number of heat radiating ribs are formed on the left side in the figure as cooling members for the developer accommodating portions of the developing devices 40Y, 40M, 40K, and cooled by airflow.

  Next, specific configurations of the image forming unit (process cartridge) and the developing device will be described.

  FIG. 2 is an enlarged configuration diagram showing the developing device 40 and the photoconductor 18 included in one of the four image forming units 11Y, 11M, 11C, and 11K. The four image forming units 11Y, 11M, 11C, and 11K have substantially the same configuration except that the colors of the toners to be handled are different from each other. Therefore, Y, M, C, and K indicated by “4” in FIG. Subscripts are omitted.

  As shown in FIG. 2, the surface of the photoconductor 18 is charged by a charging device (not shown) while rotating in the direction of arrow G in the drawing. The charged surface of the photosensitive member 18 is supplied with toner from the developing device 40 to the latent image on which the electrostatic latent image is formed by laser light emitted from an exposure device (not shown) to form a toner image. The developing device 40 supplies a developer contained in a developer container to a latent image on the surface of the photoreceptor 18 while moving in the direction of arrow I in the drawing, and a developing roller 45 as a developer carrying member for developing. Have. The developing roller 45 includes a rotatable developing sleeve, and a magnetic body (not shown) including a plurality of magnetic poles is disposed therein. The magnetic material is necessary for holding the developer on the surface of the developing roller 45. Further, a supply screw 48 is provided as a supply conveyance member that conveys the developer in the front direction of FIG. 2 along the axial direction of the development roller 45 while supplying the development roller 45 with the developer. A doctor blade 42 as a developer regulating means for regulating the developer supplied to the developing roller 45 to a thickness suitable for development is provided downstream of the surface of the developing roller 45 facing the supply screw 48 in the direction of surface movement. ing. A collection conveyance path 47 that collects the developed developer that has passed through the development region and separated from the surface of the development roller 45 on the downstream side in the surface movement direction from the development region that is the portion of the development roller 45 facing the photoreceptor 18. Faces the developing roller 45. The collection conveyance path 47 is a collection conveyance member that conveys the collected developer collected in the same direction as the supply screw 48 along the axial direction of the developing roller 45, and a spiral collection screw 46 that is arranged in parallel to the axial direction. I have. A supply conveyance path 49 provided with a supply screw 48 is provided in the lateral direction of the developing roller 45, and a collection conveyance path 47 provided with a collection screw 46 is provided in parallel below the development roller 45. Note that the developer can be separated from the developing roller 45 by setting the magnetic body in the developing sleeve described above to a state where there is no magnetic pole only at a position where the developer is desired to be separated. Yes. Further, a magnetic body having a magnetic pole arrangement in which a repulsive magnetic field is formed at a location to be separated may be used.

  The developing roller 45 is characterized by applying a developing bias that superimposes an AC component on a DC component. It was found that by applying an AC component, developability is improved and the difference between the charging potential and the exposure potential is reduced, so that the edge effect is alleviated and carrier adhesion to the non-image area is less likely to occur. If the frequency is lower than 5 kHz, this effect cannot be obtained.

  The developing device 40 is provided with a stirring conveyance path 44 in parallel with the collection conveyance path 47 below the supply conveyance path 49. The agitating / conveying path 44 is arranged in parallel to the axial direction as an agitating / conveying member that conveys the developer along the axial direction of the developing roller 45 to the back side in the drawing, which is the opposite direction to the supply screw 48. Further, a screw-shaped stirring screw 43 having a helical stirring blade 43b fixed to the stirring shaft 43a is provided.

  The supply conveyance path 49 and the agitation conveyance path 44 are partitioned by a first partition wall 133 as a partition wall. In the first partition wall 133, the supply conveyance path 49 and the agitation conveyance path 44 are partitioned at both ends on the front side and the rear side in the drawing, and the supply conveyance path 49 and the agitation conveyance path 44 communicate with each other. doing. The supply conveyance path 49 and the collection conveyance path 47 are also partitioned by the first partition wall 133, but an opening is provided at a location where the supply conveyance path 49 and the collection conveyance path 47 of the first partition wall 133 are partitioned. Absent. In addition, the two developer conveyance paths of the agitation conveyance path 44 and the collection conveyance path 47 are partitioned by a second partition wall 134 as a partition member. The second partition wall 134 has an opening on the front side in the figure, and the stirring conveyance path 44 and the collection conveyance path 47 communicate with each other.

  The supply screw 48, the recovery screw 46, and the stirring screw 43, which are developer conveying members, are made of resin or metal screws, and each screw diameter is φ22 [mm] and the screw pitch is 50 [mm] for the supply screw 48. The two windings, the collection screw 46 and the stirring screw 43 are one winding of 25 [mm], and the number of rotations is all set to about 600 [rpm]. Further, in the developing device 40 of the present embodiment, the total length of the agitation transport path 44 is 410 [mm], and the total length of the supply transport path 49 is 320 [mm]. The developer thinned by the doctor blade 42 made of stainless steel on the developing roller 45 is transported to a developing area which is a portion facing the photoconductor 18 for development.

The surface of the developing roller 45 is V-grooved or sandblasted and is made of Al or stainless steel (SUS) pipe of φ25 [mm], and the gap between the doctor blade 42 and the photoreceptor 18 is about 0.3 [mm]. It has become. The developer after the development is collected in the collection conveyance path 47, conveyed to the front side of the cross section in FIG. 2, and to the agitation conveyance path 44 through the opening of the second partition wall 134 provided in the non-image area portion. Developer is transferred. The toner is replenished to the agitation transport path 44 from a toner replenishing port (not shown) provided on the upper side of the agitation transport path 44 in the vicinity of the opening of the second partition wall 134 on the upstream side in the developer transport direction in the agitation transport path 44 Is done.
Note that the developer container 41 of the developing device 40 is formed by a wall member that forms the agitation conveyance path 44, the recovery conveyance path 47, the supply conveyance path 49, and the like, and a heat radiation rib 41a as a cooling member. In order to enhance the heat dissipation effect, a part of the developer container 41 was formed of aluminum having high thermal conductivity, and the developer container was electrically grounded in order to suppress discharge to the main body due to charge accumulation. The material of the developer container is not limited to aluminum, but may be other materials such as copper having high thermal conductivity.

Examples of the present invention will be described below, but the present invention is not limited to the following examples. “Part” represents “part by mass” unless otherwise specified. “%” Represents “% by mass” unless otherwise specified.
In addition, when there is no special mention about each characteristic in an Example, it measures by the method as described in this specification.

[Production of toner]
(Binder Resin Synthesis Example 1)
724 parts of bisphenol A ethylene oxide 2-mole adduct, 276 parts of isophthalic acid, and 2 parts of dibutyltin oxide are placed in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe and reacted at 230 ° C. for 8 hours under normal pressure. Further, after reacting at a reduced pressure of 10 mmHg to 15 mmHg for 5 hours, the mixture was cooled to 160 ° C., 32 parts of phthalic anhydride was added thereto, and the mixture was reacted for 2 hours.

  Next, the reaction product was cooled to 80 ° C. and reacted with 188 parts of isophorone diisocyanate in ethyl acetate for 2 hours to obtain an isocyanate-containing prepolymer (P1).

  Next, 267 parts of the isocyanate-containing prepolymer (P1) and 14 parts of isophoronediamine were reacted at 50 ° C. for 2 hours to obtain a urea-modified polyester (U1) having a weight average molecular weight of 64,000.

  In the same manner as above, 724 parts of bisphenol A ethylene oxide 2 mol adduct and 276 parts of terephthalic acid were polycondensed at 230 ° C. for 8 hours under normal pressure, and then reacted for 5 hours at a reduced pressure of 10 mmHg to 15 mmHg to obtain a peak molecular weight of 1,000 unmodified polyester (E1) was obtained.

200 parts of urea-modified polyester (U1) and 800 parts of unmodified polyester (E1) are dissolved and mixed in 2,000 parts of an ethyl acetate / MEK (1/1: mass ratio) mixed solvent, and the binder resin (B1). Of ethyl acetate / MEK was obtained.
A part was dried under reduced pressure, and the binder resin (B1) was isolated.

(Polyester resin synthesis example A)
-Composition-
・ Terephthalic acid: 60 parts ・ Dodecenyl succinic anhydride: 25 parts ・ Trimellitic anhydride: 15 parts ・ Bisphenol A (2,2) propylene oxide: 70 parts ・ Bisphenol A (2,2) ethylene oxide: 50 parts The product is placed in a 1 L four-necked round bottom flask equipped with a thermometer, stirrer, condenser and nitrogen gas inlet tube, this flask is set in a mantle heater, and nitrogen gas is introduced from the nitrogen gas inlet tube. The temperature inside the flask was maintained in an inert atmosphere, and 0.05 parts of dibutyltin oxide was added, and the reaction was carried out while maintaining the temperature at 200 ° C. to obtain [Polyester Resin A].

(Polyester resin synthesis example B)
443 parts of PO adduct of bisphenol A (hydroxyl value 320 mg KOH / g), 135 parts of diethylene glycol, 422 parts of terephthalic acid, and dibutyltin oxide in a reaction vessel equipped with a thermometer, a stirrer, a cooler, and a nitrogen introduction tube. 5 parts was added and reacted at 200 ° C. until the acid value reached 10 mgKOH / g to obtain [Polyester Resin B].

(Polyester resin synthesis example C)
443 parts of PO adduct of bisphenol A (hydroxyl value 320 mg KOH / g), 135 parts of diethylene glycol, 422 parts of terephthalic acid, and dibutyltin oxide in a reaction vessel equipped with a thermometer, a stirrer, a cooler, and a nitrogen introduction tube. 5 parts was added and reacted at 230 ° C. until the acid value reached 7 mgKOH / g to obtain [Polyester Resin C].

(Master batch production example 1)
-Raw materials-
Pigment: C.I. I. Pigment Yellow 155: 40 parts Binder resin: Polyester resin A: 60 parts Water: 30 parts The above raw materials were mixed in a Henschel mixer to obtain a mixture in which water was soaked into the pigment aggregate. This was kneaded for 45 minutes with two rolls set at a roll surface temperature of 130 ° C., and pulverized to a size of 1 mmφ with a pulverizer to obtain a master batch (M1).

(Toner Production Example A)
In a beaker, 240 parts of an ethyl acetate / MEK solution of the binder resin (B1), 20 parts of pentaerythritol tetrabehenate (melting point: 81 ° C., melt viscosity: 25 cps), and 8 parts of a master batch (M1) were placed at 60 ° C. Was stirred at 12,000 rpm with a TK homomixer and uniformly dissolved and dispersed to prepare [Toner Material Liquid].

In another beaker, 706 parts of ion-exchanged water, 294 parts of hydroxyapatite 10% suspension (Superite 10 manufactured by Nippon Chemical Industry Co., Ltd.) and 0.2 part of sodium dodecylbenzenesulfonate were uniformly dissolved.
Next, the temperature was raised to 60 ° C., and the toner material solution was added and stirred for 10 minutes while stirring at 12,000 rpm with a TK homomixer.
Next, this mixed liquid is transferred to a stir bar and a Kolben equipped with a thermometer, and the temperature is raised to 98 ° C. to remove the solvent, followed by filtration, washing, drying, air classification, and [base toner particles A]. Got.

(Toner Production Example B)
-Toner constituent material-
-Polyester resin B-50 parts-Polyester resin C-50 parts-Carnauba wax-1 part-Carbon black (# 44 manufactured by Mitsubishi Chemical Corporation)-10 parts The materials were mixed for 3 minutes at 1,500 rpm with a Henschel mixer (Henschel 20B, manufactured by Mitsui Mining Co., Ltd.), and kneaded using a single-screw kneader (Buss, a small bus co-kneader) under the following conditions.
・ Set temperature: 100 ° C at the inlet
・ Exit part 50 ℃
・ Feed amount: 2kg / Hr
Further, after kneading, cooling by cooling, pulverizing with a pulverizer, and further using an I-type mill (IDS-2 type manufactured by Nippon Pneumatic Co., Ltd., using a flat impact plate, air pressure: 6.8 atm / cm ² , feed amount : 0.5 kg / hr) was further finely pulverized and further classified (132MP manufactured by Alpine) to obtain [Base toner particles B].

(Toner Production Example C)
[Mother toner particles C] were obtained in the same manner as in Toner Production Example B except that 10 parts of carbon black were changed to 50 parts of titanium oxide.

(Toner Production Example D)
Same as Toner Production Example B, except that no carbon black is prescribed. [Mother toner particles D] were obtained.

In each of 100 parts of [base toner particles A] to [base toner particles D], 1.0 part of hydrophobic silica and 1.0 part of hydrophobized titanium oxide were mixed with a Henschel mixer to obtain “toner A”, “Toner B”, “Toner C”, and “Toner D” were obtained.
The toner particle size was measured using a particle size measuring device “Coulter Counter TA2” manufactured by Coulter Electronics Co., Ltd. with an aperture diameter of 100 μm.
Toner A: Volume average particle diameter (Dv) = 6.2 μm, Number average particle diameter (Dn) = 5.1 μm
Toners B, C and D: Volume average particle diameter (Dv) = 6.9 μm, Number average particle diameter (Dn) = 6.1 μm

Subsequently, the circularity was measured as an average circularity by a flow type particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.). In the measurement, 0.1 ml to 0.5 ml of a surfactant (alkylbenzene sulfonate) as a dispersant is added to 100 ml to 150 ml of water from which impure solids have been removed in advance, and 0.1 g of a measurement sample is further added. About 0.5 g was added, and dispersion treatment was performed for about 1 to 3 minutes with an ultrasonic disperser, and a measurement liquid with a dispersion concentration adjusted to 3000 / μl to 10,000 / μl was set.
The circularity of toner A was 0.96, and the circularity of toners B, C, and D was 0.94.

[Creation of carrier]
(Carrier production example 1)
<Resin liquid 1-1>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
Aminosilane (solid content concentration: 100%) 10 parts Carbon (Ketjen black) 80 parts Barium sulfate 1,000 parts (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

<Resin liquid 1-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
・ Aminosilane (solid content concentration: 100%) 10 parts ・ Indium oxide doped tin oxide (ITO) surface-treated alumina 800 parts (powder specific resistance: 20 [Ω · cm])
・ 1,000 parts of barium sulfate (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  In each of the resin liquid 1-1 and the resin liquid 1-2, each of the above materials was dispersed with a homomixer for 10 minutes to prepare a coating layer forming liquid. Cu-Zn ferrite having a particle size of 35 μm is used as a carrier core material, and the resin liquid 1-1 is placed on the surface of the core material at a temperature of 55 ° C. with a Spira coater (Okada Seiko Co., Ltd.) at a thickness of 0.20 μm. It apply | coated in the ratio to 30 g / min, and the resin liquid 1-2 was similarly apply | coated later, and was made to dry after that. The layer thickness was adjusted depending on the liquid amount. The obtained carrier was allowed to stand in an electric furnace at 150 ° C. for 1 hour and fired. After cooling, the carrier was crushed using a sieve having an opening of 100 μm to obtain a carrier 1 having a coating layer. The average thickness T was 0.40 μm.

<Particle size of core material>
The volume average particle diameter of the core material was measured using a Microtrac Particle Size Analyzer (Nikkiso Co., Ltd.) SRA type with a range setting of 0.7 μm or more and 125 μm or less.

<Thickness of coating layer>
The average thickness h (μm) of the resin portion in the coating layer is obtained by observing the cross section of the carrier using a transmission electron microscope (TEM), and the thickness ha of the resin portion existing between the core material surface and the particles, The thickness hb of the resin part existing between the particles and the thickness hc of the resin part on the core material and the particle are measured at 50 points along the carrier surface at intervals of 0.2 μm, and the obtained measurement values are averaged. Asked.
The thickness T (μm) from the core material surface to the coating layer surface is observed with a transmission electron microscope (TEM), and the thickness T from the core material surface to the coating layer surface is determined by observing the carrier cross section. Were measured at intervals of 0.2 μm, and the obtained measured values were averaged.

<Concentration gradient and volume ratio of carbon black>
The concentration gradient of carbon black and inorganic fine particles A and the volume ratio of carbon black were confirmed by the method described in this specification. In brief, the coating layer on the carrier surface was cut with FIB (focused ion beam), and the cross section was observed with SEM (scanning electron microscope) and EDX (energy dispersive X-ray spectroscopy).

(Carrier production example 2)
The carrier except that the thickness of the layer derived from the resin liquid 1-1 in the carrier was adjusted to 0.36 μm and the thickness of the layer derived from the resin liquid 1-2 was adjusted to 0.04 μm. In the same manner as in Production Example 1, Carrier 2 was obtained.

(Carrier production example 3)
The carrier except that the thickness of the layer derived from the resin liquid 1-1 in the carrier was 0.04 μm and the thickness of the layer derived from the resin liquid 1-2 was adjusted to be 0.36 μm. A carrier 3 was obtained in the same manner as in Production Example 1.

(Carrier Production Example 4)
<Resin liquid 4-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
・ Aminosilane (solid content concentration: 100%) 10 parts ・ Indium oxide doped tin oxide (ITO) surface-treated alumina 400 parts (powder specific resistance: 20 [Ω · cm])
・ Carbon (Ketjen Black) 40 parts ・ Barium sulfate 1,000 parts (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  A carrier 4 was obtained in the same manner as in Carrier Production Example 1 except that the resin liquid 1-2 was changed to the resin liquid 4-2.

(Carrier Production Example 5)
<Resin liquid 5-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
・ Aminosilane (solid content concentration: 100%) 10 parts ・ Indium oxide doped tin oxide (ITO) surface-treated alumina 300 parts (powder specific resistance: 20 [Ω · cm])
・ Carbon (Ketjen Black) 50 parts ・ Barium sulfate 1,000 parts (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  A carrier 5 was obtained in the same manner as in Carrier Production Example 1 except that the resin liquid 1-2 was changed to the resin liquid 5-2.

(Carrier Production Example 6)
<Resin liquid 6>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 800 parts ・ Silicone resin solution 8,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
・ Aminosilane (solid content concentration: 100%) 20 parts ・ Indium oxide doped tin oxide (ITO) surface-treated alumina 800 parts (powder specific resistance: 20 [Ω · cm])
・ Carbon (Ketjen Black) 80 parts ・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Barium sulfate 2,000 parts (average particle size: 0.50 [μm])
・ Toluene 12,000 parts

  Resin liquid 1-1 and resin liquid 1-2 were changed to resin liquid 6 only, and applied in the same manner as Carrier Production Example 1 except that the thickness of the layer derived from resin liquid 6 was 0.4 μm. Thus, carrier 6 was obtained.

(Carrier Production Example 7)
<Resin liquid 7-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
・ Aminosilane (solid content concentration: 100%) 10 parts ・ Phosphorus oxide-doped tin oxide (PTO) surface-treated alumina 800 parts (powder specific resistance: 190 [Ω · cm])
・ 1,000 parts of barium sulfate (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  A carrier 7 was obtained in the same manner as in Carrier Production Example 1 except that the resin liquid 1-2 was changed to the resin liquid 7-2.

(Carrier Production Example 8)
<Resin liquid 8-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
・ Aminosilane (solid content concentration: 100%) 10 parts ・ Phosphorus oxide-doped tin oxide surface (PTO) treated alumina 1,000 parts (powder specific resistance: 210 [Ω · cm])
・ 1,000 parts of barium sulfate (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  A carrier 8 was obtained in the same manner as in Carrier Production Example 1 except that the resin liquid 1-2 was changed to the resin liquid 8-2.

(Carrier production example 9)
<Resin liquid 9-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution (solid content concentration: 40%) 2,000 parts ・ Aminosilane (solid content concentration: 100%) 10 parts ・ Tungsten oxide doped tin oxide (WTO) ) 800 parts of surface-treated alumina (powder specific resistance: 40 [Ω · cm])
・ 1,000 parts of barium sulfate (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  A carrier 9 was obtained in the same manner as in Carrier Production Example 1 except that the resin liquid 1-2 was changed to the resin liquid 9-2.

(Carrier Production Example 10)
<Resin liquid 10-2>
-Composition-
・ Acrylic resin solution (solid content concentration: 20%) 400 parts ・ Silicone resin solution 4,000 parts (SR-2410 Toray Dow Corning solid content concentration: 20%)
Aminosilane (solid content concentration: 100%) 10 parts Tin oxide surface-treated alumina 800 parts (powder specific resistance: 189 [Ω · cm])
・ 1,000 parts of barium sulfate (average particle size: 0.50 [μm])
・ Titanium diisopropoxybis (ethyl acetoacetate) 40 parts ・ Toluene 6,000 parts

  A carrier 10 was obtained in the same manner as in Carrier Production Example 1 except that the resin liquid 1-2 was changed to the resin liquid 10-2.

(Carrier Production Example 11)
Carrier 11 was obtained in the same manner as in carrier production example 1 except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to barium sulfate having an average particle diameter of 0.90 μm.

(Carrier Production Example 12)
Carrier 12 was obtained in the same manner as in carrier production example 1 except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to barium sulfate having an average particle diameter of 0.20 μm.

(Carrier Production Example 13)
Carrier 13 was obtained in the same manner as in carrier production example 1 except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to zinc oxide (average particle diameter 0.80 μm).

(Carrier Production Example 14)
Carrier 14 was obtained in the same manner as in carrier production example 1, except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to magnesium oxide (average particle size 0.55 μm).

(Carrier Production Example 15)
Carrier 15 was obtained in the same manner as in carrier production example 1, except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to magnesium hydroxide (average particle diameter 0.61 μm).

(Carrier Production Example 16)
Carrier 16 was obtained in the same manner as in carrier production example 1, except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to hydrotalcite (average particle size 0.58 μm).

(Carrier Production Example 17)
Carrier 17 was obtained in the same manner as in carrier production example 1 except that barium sulfate in resin liquid 1-1 and resin liquid 1-2 was changed to alumina (average particle diameter of 0.25 μm).

  Each carrier is shown in Table 1.

In Table 1, “with concentration gradient” means that there is a concentration gradient in which the concentration of inorganic fine particles A is higher and the concentration of carbon black is lower toward the surface of the coating layer.
In Table 1, “near the surface” means a range of depth of 0.0 μm to 0.1 μm from the surface of the coating layer.
In Table 1, “average particle size” means the average primary particle size.

Example 1
Using 7 parts of toner A obtained in Toner Production Example and 93 parts of Carrier 1 obtained in Carrier Production Example 1, the mixture was stirred for 10 minutes with a mixer to produce Developer 1-A.

(durability)
The developer is set on a machine that has been modified so that an AC voltage (frequency 8 kHz, peak peak value 800 V) can be superimposed on the development part of RICOH Pro C7110S (Ricoh Digital Color Copier / Printer Combined Machine) manufactured by Ricoh. 100,000 sheets of a 5% character chart (the size of one character is about 2 mm × 2 mm) were output, and durability was evaluated based on the amount of charge reduction and the amount of change in carrier resistance before and after outputting 100,000 sheets of images.
By remodeling, a developing bias that superimposes the AC component on the DC component can be applied to the developer carrying member.

<Measurement of charge reduction>
The amount of charge reduction was measured by the following method.
First, a sample that was mixed and frictionally charged at a ratio of 7% by mass of toner to 93% by mass of the initial carrier was measured by a general blow-off method (Toshiba Chemical Co., Ltd., TB-200). The initial charge amount. Next, toner is removed from the developer after image output by the blow-off device, and the toner is newly mixed at a ratio of 7% by mass with respect to 93% by mass of the obtained carrier. The charged sample is measured for the charge amount in the same manner as the initial carrier, and the difference from the initial charge amount is defined as the charge reduction amount. The target value of the charge reduction amount is preferably within 11.0 μC / g, and more preferably within 10.0 μC / g.

<Measurement of change in carrier resistance value>
The amount of change in the carrier resistance value was measured by the following method.
The carrier was put between the electrodes of the resistance measurement parallel electrode (gap 2 mm), DC 1000 V was applied, and the resistance value after 30 sec was measured with a high resist meter. A value obtained by converting the obtained value into a volume resistivity is defined as an initial resistance value. Next, the toner in the developer after running is removed by the blow-off device, and resistance measurement is performed on the obtained carrier by the same method as the resistance measurement method, and the obtained value is converted into volume resistivity. The difference from the initial resistance value is defined as the carrier resistance value change amount. The target value of the carrier resistance value change amount is preferably within 2.2 [Log (Ω · cm)] in absolute value, and more preferably within 2.0 [Log (Ω · cm)].

Ｅ＝初期剤Ｅ値
Ｅ’＝１０万枚画像出力後
◎ ：ΔＥ≦２
○ ：２＜ΔＥ≦５
× ：５＜ΔＥ (Color stains)
The developer is set on a machine that has been modified so that an AC voltage (frequency 8 kHz, peak peak value 800 V) can be superimposed on the development part of RICOH Pro C7110S (Ricoh Digital Color Copier / Printer Combined Machine) manufactured by Ricoh. A 5% character chart (the size of one character is about 2 mm × 2 mm) was output 100,000 sheets, and a solid image was output before and after outputting 100,000 sheets of images and measured by X-Rite. By remodeling, a developing bias that superimposes the AC component on the DC component can be applied to the developer carrying member.
Regarding measurement, specifically, a developer is set, and the value (E) obtained by measuring the image immediately after setting with X-Rite (X-Rite 938 D50, manufactured by Amtec Co., Ltd.) and 100,000 as in the durability evaluation. Images were output after the sheets were output, and ΔE was obtained by the following equation using the value (E ′) measured by X-Rite, and ranked as follows.
ΔE = EE

E = initial agent E value E ′ = after output of 100,000 sheets of images ◎: ΔE ≦ 2
○: 2 <ΔE ≦ 5
×: 5 <ΔE

(Edge carrier adhesion)
The developer is set on a machine that has been modified so that AC voltage (frequency 8 kHz, peak peak value 800 V) can be superimposed on the development part of RICOH Pro C7110S (Ricoh Digital Color Copier / Printer Combined Machine) manufactured by Ricoh. went. By remodeling, a developing bias that superimposes the AC component on the DC component can be applied to the developer carrying member.
A solid image was output, the image density was measured by X-Rite, and the development conditions (charging potential, exposure potential, development bias) were adjusted so that the density was 1.5.
A halftone image was formed under the adjusted development conditions, and the number of carrier deposits on the paper was counted and evaluated. The number of carriers attached was averaged by printing three A3 sheets.
〔Evaluation criteria〕
○: 0 to 3 ×: 4 or more

(Examples 2 to 4)
Evaluation was performed in the same manner as in Example 1 except that toners B, C, and D were used as toners, and developers 1-B, 1-C, and 1-D were used.

(Examples 5-17, Comparative Examples 1-2, 5)
Evaluation was performed in the same manner as in Example 1 except that carriers 2 to 18 were used as carriers and developers 2-A to 18-A were used.

(Comparative Example 3)
As in Example 1, the toner 1 was used as the toner and the developer 1-A was used. However, in the edge carrier adhesion evaluation, the AC frequency was changed to 4 kHz, and the evaluation was performed.

(Comparative Example 4)
As in Example 1, the toner 1 was used as the toner and the developer 1-A was used. However, in the edge carrier adhesion evaluation, the evaluation was performed without superimposing the AC voltage.

  Table 2 shows combinations of developer carriers and toners used in the examples and comparative examples, and evaluation results.

Aspects of the present invention are as follows, for example.
<1> A developing device that contains a developer containing a carrier and a toner and develops an electrostatic latent image formed on the electrostatic latent image carrier using the developer,
A developer carrying member that faces the electrostatic latent image carrying member and conveys the developer;
A developer regulating member that regulates the amount of the developer carried on the developer carrying body;
With
The carrier contains core material particles and a coating layer covering the core material particles,
The coating layer contains a resin, carbon black, inorganic fine particles A, and inorganic fine particles B,
In the coating layer, the inorganic fine particles A and the carbon black exist with a concentration gradient in the thickness direction of the coating layer, and the concentration of the inorganic fine particles A increases toward the surface of the carrier, and the carbon The density of black is reduced,
In the coating layer, in the range of depth 0.0 μm to 0.1 μm from the surface of the coating layer on the surface side of the carrier, the volume content of the carbon black is 0% or more and 30% or less,
In the developing device, a developing bias for superimposing an alternating current component having a frequency of 5 kHz or more on a direct current component is applied to the developer carrier.
<2> The developing device according to <1>, wherein the powder specific resistance of the inorganic fine particles A is 200 Ω · cm or less.
<3> The developing device according to any one of <1> to <2>, wherein the inorganic fine particle A is at least one of (i) to (iii) below.
(I) Fine particles of at least one of tungsten, indium, and phosphorus (ii) Fine particles of tin oxide doped with an oxide of at least one of tungsten, indium, and phosphorus (iii) At least one of tungsten, indium, and phosphorus Fine particles in which tin oxide doped with such oxide is provided on the surface of the base particles <4> The average particle diameter h of the inorganic fine particles B and the average thickness T of the coating layer satisfy the following formula (1): The developing device according to any one of <1> to <3>.
h / 2 ≦ T ≦ 3h / 2 Formula (1)
<5> The developing device according to any one of <1> to <4>, wherein the toner is any one of a color toner, a white toner, and a transparent toner.
<6> The toner is a negatively charged toner,
The developing device according to any one of <1> to <5>, wherein the inorganic fine particles B are fine particles of at least one of barium sulfate, zinc oxide, magnesium oxide, magnesium hydroxide, and hydrotalcite.
<7> an electrostatic latent image carrier;
Charging means for charging the electrostatic latent image carrier;
Exposure means for forming an electrostatic latent image on the electrostatic latent image carrier;
Developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image;
Have
An image forming apparatus, wherein the developing unit is the developing device according to any one of <1> to <6>.
<8> a charging step for charging the electrostatic latent image carrier;
An exposure step of forming an electrostatic latent image on the electrostatic latent image carrier;
A developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image;
Have
In the image forming method, the developing step is performed using the developing device according to any one of <1> to <6>.

  According to the developing device described in <1> to <6> of the present invention, the image forming device described in <7>, and the image forming method described in <8>, the conventional problems are solved. And the effects of the present invention can be obtained.

DESCRIPTION OF SYMBOLS 1 Image forming part 2 Transfer unit 3 Paper feed unit 4 Secondary transfer device 5 Duplex unit 6 Conveyor belt 7 Fixing unit 8 Paper discharge unit 9 Exposure unit 10 Reading device 11 Image forming unit 12 Drum cleaning unit 13 Charging unit 14 Registration roller 15 Intermediate transfer belt 16 Transfer facing roller 17 Secondary transfer roller 18 Photoconductor 20 Heat insulating device 21 Heat receiving plate 22 Heat pipe 23 Heat radiating plate 24 Duct 40 Developing device 41 Developer container 41a Heat radiating rib 42 Doctor blade 43 Stirring screw 43a Stirring shaft 43b Agitation blade 44 Agitation conveyance path 45 Developing roller 46 Recovery screw 47 Recovery conveyance path 48 Supply screw 49 Supply conveyance path 90 Intermediate transfer belt cleaning unit 133 First partition wall 134 Second partition wall

JP 58-108548 A JP 54-1555048 A JP 57-40267 A JP 58-108549 A JP 59-166968 A Japanese Patent Publication No. 1-19584 Japanese Examined Patent Publication No. 3-628 JP-A-6-202381 JP-A-5-273789 JP-A-8-6307 Japanese Patent No. 2683624 JP 2001-117287 A JP-A-56-75659 JP-A-4-360156 JP-A-5-303238 JP-A-11-174740 JP-A-3-73968 JP-A-8-179570 JP-A-8-286429

Claims (8)

A developing device that contains a developer containing a carrier and a toner and develops an electrostatic latent image formed on the electrostatic latent image carrier using the developer,
A developer carrying member that faces the electrostatic latent image carrying member and conveys the developer;
A developer regulating member that regulates the amount of the developer carried on the developer carrying body;
With
The carrier contains core material particles and a coating layer covering the core material particles,
The coating layer contains a resin, carbon black, and two types of inorganic fine particles, inorganic fine particles A and inorganic fine particles B,
In the coating layer, the inorganic fine particles A and the carbon black exist with a concentration gradient in the thickness direction of the coating layer, and the concentration of the inorganic fine particles A increases toward the surface of the carrier, and the carbon The density of black is reduced,
In the coating layer, in the range of depth 0.0 μm to 0.1 μm from the surface of the coating layer on the surface side of the carrier, the volume content of the carbon black is 0% or more and 30% or less,
A developing device, wherein a developing bias for superimposing an alternating current component having a frequency of 5 kHz or more on a direct current component is applied to the developer carrier.   The developing device according to claim 1, wherein a powder specific resistance of the inorganic fine particles A is 200 Ω · cm or less. The developing device according to claim 1, wherein the inorganic fine particles A are at least one of the following (i) to (iii).
(I) Fine particles of at least one of tungsten, indium, and phosphorus (ii) Fine particles of tin oxide doped with an oxide of at least one of tungsten, indium, and phosphorus (iii) At least one of tungsten, indium, and phosphorus Fine particles with tin oxide doped with any oxide provided on the surface of the substrate particles The developing device according to claim 1, wherein an average particle diameter h of the inorganic fine particles B and an average thickness T of the coating layer satisfy the following expression (1).
h / 2 ≦ T ≦ 3h / 2 Formula (1)   The developing device according to claim 1, wherein the toner is any one of a color toner, a white toner, and a transparent toner. The toner is a negatively charged toner;
The developing device according to claim 1, wherein the inorganic fine particles B are fine particles of at least one of barium sulfate, zinc oxide, magnesium oxide, magnesium hydroxide, and hydrotalcite. An electrostatic latent image carrier;
Charging means for charging the electrostatic latent image carrier;
Exposure means for forming an electrostatic latent image on the electrostatic latent image carrier;
Developing means for developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image;
Have
An image forming apparatus, wherein the developing unit is the developing device according to claim 1. A charging step for charging the electrostatic latent image carrier;
An exposure step of forming an electrostatic latent image on the electrostatic latent image carrier;
A developing step of developing the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image;
Have
An image forming method, wherein the developing step is performed using the developing device according to claim 1.

Images