JP2017021199A - Carrier, developer, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier which enables charge control and can supply a stable amount of a developer to a development region, and enables continuous paper feeding at a printing density of a low image area ratio even in a high-speed machine using a low temperature fixing toner.SOLUTION: There is provided a carrier having at least magnesium hydroxide-containing fine particles in a resin layer, where an amount [Mgα] of magnesium on the surface after treated the carrier on the following predetermined condition is 4.2 atomic% or more and 13.2 atomic% or less. The treatment condition is that 100,000 pieces of images are printed using a developer having 7 mass% of a toner concentration and 93 mass% of a carrier concentration in an image forming apparatus at an image area ratio of 80%, and the developer is recovered. An Mg amount of the surface of the carrier obtained by removing the toner from the developer is represented by "Mg amount [Mgα] of the surface after treatment".SELECTED DRAWING: Figure 2

Description

  The present invention relates to a carrier, a developer, and an image forming method.

In electrophotographic image formation, an electrostatic latent image is formed on an electrostatic latent image carrier such as a photoconductive substance, and a charged toner is attached to the electrostatic latent image to form a toner image. After that, the toner image is transferred to a recording medium and fixed to form an output image. In recent years, the technology of copying machines and printers using an electrophotographic system is rapidly expanding from monochrome to full color, and the full color market tends to expand.
In full-color image formation, generally, color toners of three colors of yellow, magenta, and cyan or four color toners obtained by adding black to this are laminated to reproduce all colors. Therefore, in order to obtain a clear full color image with excellent color reproducibility, it is necessary to smooth the surface of the fixed toner image to reduce light scattering. For these reasons, the image gloss of conventional full-color copying machines and the like is often 10 to 50% of medium to high gloss.

In general, as a method for fixing a dry toner image on a recording medium, a contact heating fixing method in which a roller or belt having a smooth surface is heated and pressed against the toner is frequently used. Such a method has high thermal efficiency and enables high-speed fixing, and can give gloss and transparency to the color toner. On the other hand, the surface of the heat-fixing member is brought into contact with the molten toner under pressure. Then, in order to peel off, a so-called offset phenomenon occurs in which a part of the toner image adheres to the surface of the fixing roller and is transferred onto another image.
In order to prevent such an offset phenomenon, the surface of the fixing roller is formed of silicone rubber or fluorine resin having excellent releasability, and further, an oil for preventing toner adhesion such as silicone oil is applied to the surface of the fixing roller. This method is generally adopted. However, such a method is extremely effective in preventing toner offset, but requires a device for supplying oil, and there is a problem that the fixing device is increased in size.
For this reason, in monochrome image formation, an oilless system in which viscoelasticity at the time of melting is large and toner containing a release agent is used so that the melted toner does not break internally, so that no oil is applied to the fixing roller, or There is a tendency to adopt a system in which a small amount of oil is applied.

  On the other hand, in full-color image formation, as in the case of monochrome image formation, an oilless system tends to be employed for the purpose of downsizing the fixing device and simplifying the configuration. However, in full-color image formation, it is necessary to reduce the viscoelasticity of the toner at the time of melting in order to smooth the surface of the fixed toner image. Therefore, offset occurs more than in the case of monochrome image formation without gloss. This makes it difficult to adopt an oilless system. Further, when a toner containing a release agent is used, adhesion of the toner is increased and transferability to a recording medium is decreased. Furthermore, there is a problem in that the durability is lowered due to the occurrence of toner filming and a decrease in chargeability.

On the other hand, as a carrier, prevention of toner filming, formation of a uniform surface, prevention of surface oxidation, prevention of decrease in moisture sensitivity, extension of developer life, prevention of adhesion to the surface of a photoreceptor, photosensitivity For the purpose of protecting the body from scratches or abrasion, controlling the charge polarity, adjusting the charge amount, etc., a coating layer in which a resin containing carbon black is formed on the surface is known. However, a good image can be formed in the initial stage, but there is a problem in that as the number of copies increases, the coating layer is scraped and the image quality decreases. Further, there is a problem that color stains occur due to the coating layer being scraped or the carbon black being detached from the coating layer. As an alternative material for carbon black, titanium oxide, zinc oxide, and the like are generally known, but the effect of reducing volume resistivity is insufficient.

Patent Document 1 (Japanese Patent Laid-Open No. 11-202560) discloses a carrier in which a coating layer containing antimony-doped tin oxide (ATO) is formed as acicular conductive powder. However, since ATO is bluish in color tone, there is a problem that color stains occur as in the case of carbon black. Patent Document 2 (Japanese Patent Laid-Open No. 2006-39357) discloses a carrier in which a coating layer containing conductive particles in which a tin dioxide layer and an indium oxide layer containing tin dioxide are laminated on the surface of a base particle is formed. Is disclosed. However, since such conductive particles contain rare metals, there are problems such as cost and permanent availability. Patent Document 3 (Japanese Patent Laid-Open No. 2010-117519) discloses that the first conductive particles that are metal oxide conductive particles and the surfaces of the metal oxide particles and / or metal salt particles are subjected to conductive treatment. A carrier having a coating layer containing second conductive particles is disclosed. The present invention has a certain effect on the reduction in the charging ability of the carrier when the toner is balanced with a high image area. However, when a toner with a large amount of toner external additives is used, In the case of continuous paper passing, the charge was lowered and the effect was not sufficient.
In response, Patent Document 4 (Japanese Patent No. 5534409) and Patent Document 5 (Japanese Patent Laid-Open No. 2011-209678) include a barium sulfate in the coating film, and the Ba / Si ratio relative to all elements measured by XPS. A carrier that is 0.01 to 0.08 is disclosed. This technique is effective for reducing the charging ability of the carrier when the toner is balanced in a larger image area. Patent Document 6 (Japanese Unexamined Patent Application Publication No. 2009-63805) discloses a carrier that uses conductive fine particles that are metal oxide conductive particles and charge-controlled fine particles having a shape defined in combination. In the present invention, carbon black or zinc oxide is used as the conductive particles, and as the charge control particles, magnesium hydroxide or magnesium oxide whose shape factor (SF-1) has a variation rate of 16% or less is used, While maintaining sufficient carrier conductivity, it has a certain effect on the decrease in carrier charging ability when the number of printed sheets is increased.

  However, in recent years, the toner tends to be fixed at a low temperature to reduce power consumption, and in addition to the increase in printing speed, toner spent on the carrier is more likely to occur. In addition, toners tend to contain many additives due to demands for higher image quality, and these are spent on the carrier, resulting in a decrease in toner charge amount, a margin for toner scattering and background contamination. Currently. In addition, since the amount of charged fine particles and the like is reduced for fixing the toner at a low temperature, the toner at the time of replenishment is not sufficiently mixed with the developer, so that the toner is not charged and the toner is scattered. Yes. For such new problems, such as Patent Document 4 (Japanese Patent No. 5534409), Patent Document 5 (Japanese Patent Laid-Open No. 2011-209678), and Patent Document 6 (Japanese Patent Laid-Open No. 2009-63805) I haven't been able to show enough effects in my career.

  On the other hand, in the field of production printing, where the market has been expanding in recent years, higher image quality than ever has been demanded. It is technically very difficult to deal with density fluctuations and density irregularities within one image, density fluctuations between images when printing tens of thousands of sheets, and the like only with the machine body. For this reason, it is more demanded than ever to control the toner charge amount to a constant level, and the conventional carrier as described above cannot satisfy the required characteristics.

  Based on the technical problems as described above, the present invention is capable of sufficient charge control for the image quality required in the field of production printing, and can supply a stable developer amount to the development area. And a carrier that enables continuous paper passing at a printing density with a low image area ratio even in a high-speed machine using a low-temperature fixing toner, a developer using the carrier, a developer containing unit, and an image forming method. With the goal.

The above problem is solved by the configuration 1) below.
1) A carrier having at least magnesium hydroxide-containing fine particles in the resin layer, and the amount of magnesium [Mgα] on the surface of the carrier after treatment under the following predetermined conditions is 4.2 atomic% or more and 13.2 atomic% or less A career characterized by being.
Processing conditions: In an image forming apparatus using a developer having a toner concentration of 7% by mass and a carrier concentration of 93% by mass, after printing 100,000 sheets at an image area ratio of 80%, the developer is recovered. The amount of Mg on the surface of the carrier from which the toner has been removed from the developer is defined as “the amount of Mg on the surface after processing [Mgα]”.

  According to the present invention, sufficient charge control can be performed for the image quality required in the field of production printing, a stable developer amount can be supplied to the development area, and a low-temperature fixing toner is used. Even in the high-speed machine, it is possible to provide a carrier that enables continuous paper feeding at a printing density with a low image area ratio, a developer using the carrier, a developer containing unit, and an image forming method.

It is a figure for demonstrating the cell used for the measurement of the volume specific resistance of the carrier of this invention. It is a diagram showing an example of a process cartridge to which the image forming method of the present invention is applied. It is a figure for demonstrating the image chart used for evaluation of the ghost image performed in the Example.

The carrier of the present invention will be described in detail.
The carrier of the present invention is a carrier comprising magnetic core material particles and a resin layer covering the surface thereof, and having at least magnesium hydroxide-containing fine particles (hereinafter also referred to as magnesium hydroxide fine particles) in the resin layer. The carrier is characterized in that the amount of magnesium [Mgα] on the surface after the treatment under the following predetermined conditions is 4.2 atomic% or more and 13.2 atomic% or less.
Processing conditions: In an image forming apparatus using a developer having a toner concentration of 7% by mass and a carrier concentration of 93% by mass, after printing 100,000 sheets at an image area ratio of 80%, the developer is recovered. The amount of Mg on the surface of the carrier from which the toner has been removed from the developer is defined as “the amount of Mg on the surface after processing [Mgα]”.

In the present invention, it is very important that at least one kind of magnesium hydroxide fine particles is contained in the resin layer, and the magnesium hydroxide fine particles are present in the surface layer of the resin layer. Since the magnesium hydroxide fine particles have a high chargeability with the toner, the magnesium hydroxide fine particles on the surface layer can maintain the chargeability even after output over a long and high image area.
The presence of magnesium hydroxide can be confirmed by the presence of a diffraction peak attributed to magnesium hydroxide by powder X-ray diffraction measurement.

  In the present invention, it is particularly preferable that the surface exposure amount of the magnesium hydroxide fine particles is increased before and after the deterioration. By repeating printing with a high image area ratio for a long time, the surface of the carrier is scraped by stress, and spent by toner, wax, and external additives, and the state of the carrier surface layer portion changes. At that time, the surface exposure amount of the highly chargeable magnesium hydroxide fine particles increases even after deterioration, and can sufficiently work with the toner, so that high charging stability can be maintained. When the change in surface exposure is in the decreasing direction, if the increase amount is less than 1.0 atomic%, the magnesium hydroxide fine particles are not sufficiently exposed on the surface and do not act on the toner, so low temperature fixing When toner is used and the number of printed sheets is piled up, there is a possibility that the chargeability cannot be maintained.

In the present invention, the amount of magnesium [Mgβ] on the surface of the carrier before treatment under the treatment conditions is 3.2 atomic% or more and 12.2 atomic% or less,
It is particularly preferable that the surface magnesium amount [Mgα] after the treatment under the treatment conditions and the surface magnesium amount [Mgβ] before the treatment satisfy the following formulas:
15 ≧ [Mgα] − [Mgβ] ≧ 1 (atomic%)

When the above-mentioned surface exposure amounts [Mgβ] and [Mgα] cannot be secured, the charge amount of the carrier before deterioration with a small number of printed sheets cannot be secured sufficiently, the developing ability of the initial image is lowered, background fogging and toner scattering Such a quality problem may occur. In addition, even when the number of printed sheets is deteriorated by overlapping, the magnesium hydroxide fine particles cannot be sufficiently exposed, and there is a possibility that the chargeability after output in a long and high image area cannot be maintained. In order to ensure chargeability in long-term use, it is necessary to adjust the surface exposure amount as the means, such as prescription amount of magnesium hydroxide fine particles, particle size, shape, purity of magnesium hydroxide fine particles, etc. Adjustment. When the amount of magnesium hydroxide fine particles is small, the wear amount of the resin layer increases due to the decrease in the particle density in the resin layer, and further problems such as change in agent bulk density, decrease in charge, and carrier adhesion due to exposure of the core material occur. . That is, it is necessary to use magnesium hydroxide fine particles having a prescribed amount that gives the surface exposure amount as described above while providing a sufficient density in the resin layer with respect to the resin layer thickness. When the amount of magnesium hydroxide fine particles is small, the wear amount of the resin layer increases due to the decrease in the particle density in the resin layer, and further problems such as change in agent bulk density, decrease in charge, and carrier adhesion due to exposure of the core material occur. . That is, it is preferable to use magnesium hydroxide fine particles having a prescribed amount so that the surface exposure amount as described above is provided while having a sufficient density in the resin layer with respect to the resin layer thickness.
In the present invention, magnesium hydroxide is preferably formulated in an amount of 30 to 60% by mass, more preferably 21 to 26% by mass in the resin layer.
In the present invention, the Mg amount [Mgα] is more preferably 4.5 to 7.5 atomic%.
In the present invention, the Mg content [Mgβ] is more preferably 3.0 to 5.5 atomic%.
In the present invention, more preferable [Mgα] and [Mgβ] satisfy the following formula.
2.0 ≧ [Mgα] − [Mgβ] ≧ 1.5 (atomic%)

In the present invention, the volume average particle diameter of the magnesium hydroxide fine particles is preferably 200 nm or more and 900 nm or less.
By setting the magnesium hydroxide fine particles in the above volume average particle size range, the magnesium hydroxide fine particles are present in a convex state on the surface of the resin layer. The convex magnesium hydroxide fine particles are constantly stressed by friction with toner, carrier, development screw, etc. in the developing machine, so even if toner resin, wax, additives, etc. are temporarily spent, In addition, the magnesium hydroxide fine particles can be kept in a state where they are shaved by the stress and are always exposed. Further, when the volume average particle size is within the above range, if the particles of the magnesium hydroxide fine particles are spherical, the more the magnesium hydroxide fine particle cross-section is exposed on the surface as the abrasion by the stress proceeds. . As the amount of the magnesium hydroxide fine particles increases, the carrier exhibits higher chargeability, so that stable charging ability can be exhibited even when the number of printed sheets is deteriorated.
On the other hand, toner resin, wax, additives, etc. are spent in the recesses present between the magnesium hydroxide projections. However, since they are covered with these, they become electrically charged with the toner, so that the spent is further increased. Things do not accumulate. The carrier surface that becomes a concave portion due to these spents cannot charge the toner, but since it is a concave portion, the friction probability with the toner is low and the contribution to toner charging is small. For this reason, since the site | part in which the magnesium hydroxide microparticles | fine-particles exist convexly determines the charging capability of a carrier, it can hold | maintain the stable charging capability over a long period of time.

Conversely, when magnesium hydroxide fine particles having a small volume average particle size such as 80 nm are used, as the number of printed sheets increases, toner resin, wax, additives, etc. are spent on the carrier surface and exist on the carrier surface layer. Covers magnesium hydroxide fine particles. As described above, since the magnesium hydroxide fine particles in the carrier surface layer contribute to maintaining the charging property, in this case, there is a possibility that satisfactory charging stability cannot be ensured.
The volume average particle size of the magnesium hydroxide fine particles is preferably 200 nm or more and 900 nm or less for the above reasons, but in order to ensure the stable charging ability and developing ability as described above, the volume average particle size of the magnesium hydroxide fine particles is The diameter is more preferably 600 nm or more. In addition, it is not preferable that the volume average particle diameter of the magnesium hydroxide fine particles exceeds 900 nm because the magnesium hydroxide fine particles are too large with respect to the thickness of the resin layer so that the magnesium hydroxide fine particles are easily detached from the resin layer.

Note that RICOH Pro C7110S manufactured by Ricoh Co., Ltd. is used as the image forming apparatus used for the processing. In the treatment, 7.0 g of a developer having a toner concentration of 20% by mass and the carrier concentration of 80% by mass is weighed in an environment of 30 ° C. and 90% RH, and stirred at 500 G, 500 rpm for 2 hours with a mag roll. It is equivalent to the method.
Further, the blow-off device TB-200 (manufactured by Toshiba Chemical Co., Ltd.) is used to remove the toner from the developer collected after printing. It is possible to collect 3.0 g of developer in the measurement cell and blow the toner for 60 seconds to recover the carrier from which the toner has been removed.
The amount of Mg [Mgα] on the carrier surface can be measured using an X-ray photoelectron spectrometer. Specifically, using AXIS / ULTRA manufactured by Shimadzu Corporation, the beam irradiation area is approximately 900 μm × 600 μm, and a range of 25 carriers × 17 is detected. The penetration depth is 0 to 10 nm, which is defined as the carrier surface. Specific measurement methods are: measurement mode: Electrostatic, excitation source: monochrome (Al), detection method: spectrum mode, and magnet lens: OFF. First, a detection element was specified by a wide-area scan, and then a peak was detected for each detection element by a narrow scan, and then the atomic% of Mg with respect to all the detection elements was calculated using the attached peak analysis software.

The equivalent circle diameter of the magnesium hydroxide fine particles is measured by the following method.
The carrier is mixed in an embedding resin (Devcon, two-component mixed, 30-minute curable epoxy resin), allowed to stand overnight and cured, and a rough cross-sectional sample is prepared by mechanical polishing. A cross section polisher (SM-09010 manufactured by JEOL) is used for this, and the cross section is finished under the conditions of an acceleration voltage of 5.0 kV and a beam current of 120 μA. This is photographed using a scanning electron microscope (Merlin manufactured by Carl Zeiss) under the conditions of an acceleration voltage of 0.8 kV and a magnification of 30000 times. The captured image is taken into a TIFF image, and the equivalent circle diameter of the magnesium hydroxide fine particles is measured using Image-Pro Plus manufactured by Media Cybernetics, and the average value is obtained.

The volume average particle diameter of the magnesium hydroxide fine particles is measured by an automatic particle size distribution measuring apparatus CAPA-700 (manufactured by Horiba Seisakusho). As a pretreatment for the measurement, 300 ml of a toluene solution is added to 30 ml of aminosilane (SH6020: manufactured by Toray Dow Corning Silicone) in a juicer mixer. Add 6.0 g of sample, set mixer rotation speed to low and disperse for 3 minutes. An appropriate amount of the dispersion is added to 500 ml of a toluene solution prepared in advance in a 1000 ml beaker and diluted. The diluting solution is continuously stirred with a homogenizer. This diluted solution is measured with an ultracentrifugal automatic particle size distribution analyzer CAPA-700.
[Measurement condition]
Rotation speed: 2000rpm
Maximum particle size: 2.0 μm
Minimum particle size: 0.1 μm
Particle size interval: 0.1 μm
Dispersion medium viscosity: 0.59 mPa · s
Dispersion medium density: 0.87 g / cm ³
Particle density: Magnesium hydroxide fine particle density is input as true specific gravity value measured using dry automatic bulk density meter Accupic 1330 (manufactured by Shimadzu Corporation).

In the present invention, it is preferable to use magnesium hydroxide fine particles having magnesium hydroxide exposed on the surface.
As described above, the magnesium hydroxide exposed on the surface contributes to a stable charging ability, and therefore, if the surface layer of the magnesium hydroxide fine particles is covered with a substance such as tin, the magnesium hydroxide is not exposed on the surface. There is a possibility that charging ability cannot be secured. For this reason, it is difficult to exhibit stable charging ability. Further, the magnesium hydroxide is exposed to the carrier surface layer, so that the replenished toner can be easily taken in. This is considered to be due to the fact that magnesium hydroxide tends to be frictionally charged with the toner, and has a particularly remarkable effect on the toner in which charged particles are reduced for low-temperature fixing. In addition, the magnesium hydroxide fine particles in which magnesium hydroxide is exposed on the surface here means that magnesium hydroxide is not covered with a substance such as tin, and 90% or more of the fine particle surface is magnesium hydroxide. Means. The magnesium hydroxide fine particles may be magnesium hydroxide single particles.

The carrier of the present invention, the bulk density is preferably not more than 1.6 g / cm ³ or more 2.30 g / cm ^3. According to the above bulk density range, the amount of toner on the electrostatic latent image carrier varies, and a very advantageous effect can be obtained in that the phenomenon that the next image takes over the previous image history (ghost phenomenon) is prevented.
As described in JP 2013-57817 A and JP 2014-77974 A, the generation mechanism of the ghost phenomenon is presumed as follows although details are not clear. The toner adheres to the developer carrying member according to the immediately preceding image history, and the toner development amount of the next image varies depending on the potential of the toner attached on the developer carrying member. That is, it is considered that the toner development amount of the next image varies depending on the immediately preceding image history. More specifically, in the non-image area, contrary to the image area, a potential for moving the toner from the electrostatic latent image carrier toward the developing sleeve is formed, so that the toner adheres directly onto the developer carrier. (Toner adhesion occurs on the developer carrying member). When the image portion is developed at the next development in a state where the toner is adhered on the developer carrier in this way, the toner directly adhered onto the developer carrier is charged, and therefore the toner on the developer carrier is charged. The development potential is increased by the potential and the toner development amount is increased. In addition, since the toner directly adhered onto the developer carrying member is consumed during development, the amount of adhered toner is not constant and varies depending on the history of the immediately preceding image. That is, when there is a non-image portion or a paper-to-paper gap immediately before, development of the subsequent image portion causes the above-described development potential to increase, and the subsequent image density increases. On the other hand, when the immediately preceding image is an image having a large image area, the toner directly attached on the developer carrier is consumed when the immediately preceding image is developed, and the above-described effect of increasing the development potential is reduced. Thereafter, the image density does not increase. As described above, the hysteresis phenomenon that is the subject of the present invention is a phenomenon in which the toner adhesion amount on the developer carrier fluctuates due to the influence of the immediately preceding image, and the density fluctuation of the next image appears due to the fluctuation. .

It is confirmed that the ghost phenomenon is improved when the bulk density of the carrier is less than 2.30 g / cm ³ . This is because when the developing machine configuration is the same, the number of carriers in the development Nip can be increased due to the low bulk density of the carrier, and the effective resistance in the development Nip can be lowered, so that development can be performed during non-image development. This is because the toner developed on the developer carrier is less likely to be consumed during printing, so that the toner amount on the developer carrier is stable regardless of the immediately preceding image, and image uniformity is obtained.

In the carrier of the present invention, the resin contained in the resin layer contains the following copolymer (general formula (1)) containing the component A represented by the general formula (A) and the component B represented by the general formula (B). ) Is hydrolyzed to produce a silanol group and condensed using a catalyst to obtain a cross-linked product, which is coated with core material particles, and then preferably a carrier obtained by heat treatment.

Here, in the formula, R ¹ , m, R ² , R ³ , X, and Y are as follows.
R ¹ : hydrogen atom or methyl group m: alkylene group such as methylene group having 1 to 8 carbon atoms, ethylene group, propylene group, butylene group R ² : methyl group having 1 to 4 carbon atoms, ethyl group, propyl Group, isopropyl group, alkyl group such as butyl group R ³ : alkyl group such as methyl group having 1 to 8 carbon atoms, ethyl group, propyl group, isopropyl group and butyl group, or methoxy group having 1 to 4 carbon atoms , Alkoxy groups such as ethoxy group, propoxy group, butoxy group

A component:

Here, in the formula, R ¹ , m, R ² and X represent the following.
R ¹ : hydrogen atom, or methyl group m: alkylene group such as methylene group having 1 to 8 carbon atoms, ethylene group, propylene group, butylene group,
R ² : an alkyl group such as a methyl group having 1 to 4 carbon atoms, an ethyl group, a propyl group, and a butyl group In the component A, X = 10 to 90 mol%, more preferably 30 to 70 mol%. is there.
The component A has, for example, tris (trimethylsiloxy) silane, which is an atomic group having a large number of methyl groups in the side chain. When the ratio of the component A is increased with respect to the entire resin, the surface energy decreases, and the toner The adhesion of resin components, wax components, etc. of the resin is reduced. If the A component is less than 10 mol%, a sufficient effect cannot be obtained, and the adhesion of the toner component increases rapidly. On the other hand, if it exceeds 90 mol%, the following component B and component C will decrease, crosslinking will not proceed, the toughness will be insufficient, the adhesiveness between the core particles and the resin layer will decrease, and the durability of the carrier coating will be reduced. May get worse.

As a monomer component for constituting the A component, a tris (trialkylsiloxy) silane compound represented by the following formula is exemplified.
In the following formulae, Me is a methyl group, Et is an ethyl group, and Pr is a propyl group.
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiMe 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiEt 3) 3
_{CH 2 = CMe-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CH-COO-C} 3 H 6 -Si (OSiPr 3) 3
_{CH 2 = CMe-COO-C} 4 H 8 -Si (OSiPr 3) 3

  The production method of the component A is not particularly limited, but a method of reacting tris (trialkylsiloxy) silane with allyl acrylate or allyl methacrylate in the presence of a platinum catalyst, or a carboxylic acid described in JP-A-11-217389. It can be obtained by a method of reacting methacryloxyalkyltrialkoxysilane and hexaalkyldisiloxane in the presence of an acid and an acid catalyst.

Component B: (Crosslinking component)

Here, in the formula, R ¹ , m, R ² , R ³ , and Y are as follows.
R ¹ : hydrogen atom or methyl group m: alkylene group such as methylene group having 1 to 8 carbon atoms, ethylene group, propylene group, butylene group R ² : methyl group having 1 to 4 carbon atoms, ethyl group, propyl Group and alkyl group such as butyl group R ³ : alkyl group having 1 to 8 carbon atoms (methyl group, ethyl group, propyl group, butyl group, etc.), or alkoxy group having 1 to 4 carbon atoms (methoxy group, ethoxy group) , Propoxy group, butoxy group)
That is, the component B is a radically polymerizable bifunctional or trifunctional silane compound, and Y = 10 to 90 mol%, more preferably 30 to 70 mol%.
When the B component is less than 10 mol%, sufficient toughness cannot be obtained. On the other hand, when it exceeds 90 mol%, the coating becomes hard and brittle, and film scraping tends to occur. Moreover, environmental characteristics deteriorate. It is also conceivable that a large number of hydrolyzed crosslinking components remain as silanol groups, deteriorating environmental characteristics (humidity dependency).

  As a monomer component for constituting the B component, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, Examples include 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltri (isopropoxy) silane, and 3-acryloxypropyltri (isopropoxy) silane.

In the present invention, an acrylic compound (monomer) may be added as a C component to the A component and the B component.
As what added such C component, the following copolymer (general formula (2)) is mentioned.

In the above formula, R ¹ , m, R ² , R ³ , X, Y, and Z are as follows.
R ¹ : hydrogen atom or methyl group m: alkylene group having 1 to 8 carbon atoms R ² : alkyl group having 1 to 4 carbon atoms R ³ : alkyl group having 1 to 8 carbon atoms, or 1 to 4 carbon atoms Alkoxy group X: 10 to 40 mol%
Y: 10-40 mol%.

  C component:

  Z = 30 to 80 mol%, and 60 mol% <Y + Z <90 mol%.

The C component imparts flexibility to the resin layer and improves the adhesion between the core material particles and the resin layer. However, if the C component is less than 30 mol%, sufficient adhesion is obtained. When it exceeds 80 mol%, either X component or Y component becomes 10 mol% or less, so it is difficult to achieve both water repellency, hardness and flexibility (film scraping) of the resin layer. Become.
As the acrylic compound (monomer) of component C, acrylic acid ester and methacrylic acid ester are preferable. Specifically, methyl methacrylate, methyl acrylate, ethyl methacrylate, ethyl acrylate, butyl methacrylate, butyl acrylate, 2- (dimethylamino) ) Ethyl methacrylate, 2- (dimethylamino) ethyl acrylate, 3- (dimethylamino) propyl methacrylate, 3- (dimethylamino) propyl acrylate. Of these, alkyl methacrylate is preferable, and methyl methacrylate is particularly preferable. One of these compounds may be used alone, or a mixture of two or more may be used.

Japanese Patent No. 3691115 discloses a technique for improving durability by crosslinking a coating. Japanese Patent No. 3691115 discloses a radical having at least one functional group selected from the group consisting of an organopolysiloxane having a vinyl group at the terminal and a hydroxyl group, an amino group, an amide group and an imide group on the surface of the magnetic particle. A carrier for developing an electrostatic charge image characterized by coating a copolymer with a copolymerizable monomer with a thermosetting resin crosslinked with an isocyanate compound is disclosed. At present, sufficient durability is not obtained.
The reason for this is not sufficiently clear, but in the case of a thermosetting resin obtained by crosslinking the above-mentioned copolymer with an isocyanate compound, as can be seen from the structural formula, it reacts with the isocyanate compound in the copolymer resin (cross-linking). The functional group per unit weight is small, and a two-dimensional or three-dimensional dense cross-linked structure cannot be formed at the cross-linking point. Therefore, when used for a long time, the resin layer is likely to be peeled off or scraped (the abrasion resistance of the resin layer is small), and it is assumed that sufficient durability is not obtained.
When the resin layer is peeled off or scraped off, the image quality changes due to a decrease in carrier resistance and carrier adhesion occurs. In addition, peeling or scraping of the resin layer lowers the fluidity of the developer and causes a decrease in the amount of pumping, which causes a decrease in image density, contamination when the TC is increased, and toner scattering.
The resin component of the resin layer in the present invention has, for example, a large number of bifunctional or trifunctional crosslinkable functional groups (points) per unit weight of the resin (2 to 3 times greater per unit weight). It is considered that the resin layer is extremely tough and difficult to scrape and is highly durable because it is a copolymer resin that has been further cross-linked by condensation polymerization.
Further, it is presumed that the aging stability of the resin layer is maintained because the crosslinking energy by the siloxane bond is larger than that by the isocyanate compound and is more stable against heat stress.

  As the resin component in the resin layer, silicon resin, acrylic resin, or a combination thereof can be used. This is because the acrylic resin has a very excellent property of abrasion resistance due to its strong adhesiveness and low brittleness, but on the other hand, because of its high surface energy, it accumulates toner component spent in combination with easily spent toner. 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 silicon 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 silicon resin has weak adhesiveness and high brittleness, it also has a weak point of 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 resin layer that also has properties.

  As used herein, the term “silicon resin” refers to all commonly known silicon resins, such as straight silicon consisting only of organosilosan bonds, and silicon 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 silicon 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 resin, KR206 (alkyd modified), KR5208 (acryl 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 resin layer in the present invention preferably contains conductive fine particles in order to adjust the volume resistivity of the carrier. Although it does not specifically limit as electroconductive fine particles, Conductive polymers, such as carbon black, ITO, PTO, WTO, a tin oxide, barium sulfate, zinc oxide, polyaniline, are mentioned, You may use 2 or more types together.

The carrier of the present invention preferably has a volume average particle size of 28 μm or more and 40 μm or less. When the volume average particle diameter of the carrier particles is less than 28 μm, carrier adhesion may occur. When the volume average particle diameter exceeds 40 μm, the reproducibility of image details may be reduced, and a fine image may not be formed.
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 carrier of the present invention preferably has a volume resistivity of 8 to 14 (LogΩ · cm). If the volume resistivity is less than 8 (Log Ω · cm), carrier adhesion may occur in the non-image area, and if it exceeds 14 (Log Ω · cm), the edge effect may be at an unacceptable level.

  The volume resistivity can be measured using the cell shown in FIG. Specifically, first, a carrier 13 is filled in a cell 11 made of a fluororesin container containing an electrode 12a and an electrode 12b having a surface area of 2.5 cm × 4 cm with a distance of 0.2 cm, and a drop height is set. Tapping 10 times at 1 cm and a tapping speed of 30 times / minute. Next, a DC voltage of 1000 V was applied between the electrodes 12a and 12b, and a resistance value r [Ω] after 30 seconds was measured using a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard Company). From Equation 2, the volume resistivity [Ω · cm] can be calculated.

  Examples of the condensation catalyst include titanium-based catalysts, tin-based catalysts, zirconium-based catalysts, and aluminum-based catalysts. In the present invention, among these various catalysts, among titanium-based catalysts that give excellent results, titanium is particularly preferable. Diisopropoxybis (ethyl acetoacetate) is most preferred as the catalyst. 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.

In the present invention, the resin layer preferably contains a silane coupling agent. Thereby, the fine particles can be stably dispersed.
The silane coupling agent is not particularly limited, but r- (2-aminoethyl) aminopropyltrimethoxysilane, r- (2-aminoethyl) aminopropylmethyldimethoxysilane, r-methacryloxypropyltrimethoxysilane, N -Β- (N-vinylbenzylaminoethyl) -r-aminopropyltrimethoxysilane hydrochloride, r-glycidoxypropyltrimethoxysilane, r-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, Vinyltriacetoxysilane, r-chloropropyltrimethoxysilane, hexamethyldisilazane, r-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl [3- (trimethoxysilyl) propyl] ammonium Chloride, r-chloropropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, allyltriethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane, dimethyldiethoxysilane, 1, Examples include 3-divinyltetramethyldisilazane and methacryloxyethyldimethyl (3-trimethoxysilylpropyl) ammonium chloride, and two or more of them may be used in combination.
Commercially available silane coupling agents include AY43-059, SR6020, SZ6023, SH6026, SZ6032, SZ6050, AY43-310M, SZ6030, SH6040, AY43-026, AY43-031, sh6062, Z-6911, sz6300, sz6075, sz6079, sz6083, sz6070, sz6072, Z-6721, AY43-004, Z-6187, AY43-021, AY43-043, AY43-040, AY43-047, Z-6265, AY43204M, AY43-048, Z-6403, AY43206M, AY43206E, Z6341, AY43210MC, AY43-083, AY43-101, AY43-013, AY43-158E, Z-6920, Z-6 40 (Toray Silicone Co., Ltd.).
It is preferable that the addition amount of a silane coupling agent is 0.1-10 mass% with respect to the resin layer. By adding the silane coupling agent within this range, the adhesion of each component is improved, and the resin layer can be prevented from falling off during long-term use. Further, it is possible to prevent toner filming during long-term use.

  In the present invention, the average film thickness of the resin layer is preferably 0.50 to 1.50 μm, and more preferably 0.7 to 0.9 μm. When the average film thickness is less than 0.50 μm, it becomes difficult to sufficiently hold the magnesium hydroxide fine particles having the above-mentioned particle diameter, and the magnesium hydroxide fine particles are easily detached from the film. On the other hand, if it exceeds 1.50 μm, magnesium hydroxide fine particles are taken into the resin layer, and it becomes difficult to exhibit sufficient charging ability.

In the present invention, the core particle is not particularly limited as long as it is a magnetic substance, but is not limited to ferromagnetic metals such as iron and cobalt; iron oxides such as magnetite, hematite and ferrite; various alloys and compounds; Examples thereof include resin particles dispersed in the 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.

The developer of the present invention has the carrier and toner of the present invention.
The toner contains a binder resin and a colorant, and may be a monochrome toner or a color toner. Further, the toner particles may contain a release agent in order to be applied to an oilless system in which toner fixing prevention oil is not applied to the fixing roller. Such toner generally tends to cause filming. However, since the carrier of the present invention can suppress filming, the developer of the present invention maintains good quality for a long time. Can do. Further, color toners, particularly yellow toners, generally have a problem that color stains are generated due to scraping of the resin layer of the carrier. However, the developer of the present invention can suppress the occurrence of color stains.

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 set to 3-15 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 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.

The binder resin is not particularly limited, but is a homopolymer of styrene such as polystyrene, poly-p-styrene, polyvinyltoluene and the like; and a styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene. -Vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer Styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene Copolymer, styrene-isoprene copolymer , Styrene copolymers such as styrene-maleic acid ester copolymer; polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacryl Examples thereof include acids, rosins, modified rosins, terpene resins, phenol resins, aliphatic or aromatic hydrocarbon resins, and aromatic petroleum resins, and two or more of them may be used in combination.
The binder resin for pressure fixing is not particularly limited, but polyolefins such as low molecular weight polyethylene and low molecular weight polypropylene; ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer. Olefin copolymers such as ethylene-methacrylate copolymer, ethylene-vinyl chloride copolymer, ethylene-vinyl acetate copolymer, ionomer resin; epoxy resin, polyester, styrene-butadiene copolymer, polyvinylpyrrolidone, Examples thereof include methyl vinyl ether-maleic anhydride copolymer, maleic acid-modified phenol resin, phenol-modified terpene resin, and the like, and two or more of them may be used in combination.

  Although it does not specifically limit as a coloring agent (pigment or dye), Cadmium yellow, mineral fast yellow, nickel titanium yellow, Navels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, Yellow pigments such as permanent yellow NCG and tartrazine lake; orange pigments such as molybdenum orange, permanent orange GTR, pyrazolone orange, vulcan orange, indanthrene brilliant orange RK, benzidine orange G, indanthrene brilliant orange GK; bengara, cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Kami Red pigments such as 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, Blue pigments such as phthalocyanine blue partially chlorinated, First Sky Blue, Indanthrene Blue BC; Green pigments such as Chrome Green, Chrome Oxide, Pigment Green B, Malachite Green Lake; Carbon Black, Oil Furnace Black, Channel Black, Lamp Black Azine-based dyes such as acetylene black and aniline black, black pigments such as metal salt azo dyes, metal oxides, and composite metal oxides. It may be.

  The release agent is not particularly limited, but includes polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin wax, amide wax, polyhydric alcohol wax, silicone varnish, carnauba wax, ester wax and the like. Two or more kinds may be used in combination.

  The toner may further contain a charge control agent. The charge control agent is not particularly limited, but nigrosine; an azine dye having an alkyl group having 2 to 16 carbon atoms (see Japanese Patent Publication No. 42-1627); 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 Examples thereof include honed copper phthalocyanine pigments; organic boron salts; fluorine-containing quaternary ammonium salts; calixarene compounds, and the like. For color toners other than black, white metal salts of salicylic acid derivatives are preferred.

  The external additive is not particularly limited, but inorganic particles such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, boron nitride, etc .; poly having an average particle size of 0.05 to 1 μm obtained by a soap-free emulsion polymerization method Examples thereof include resin particles such as methyl methacrylate particles and polystyrene particles, and two or more kinds may be used in combination. Among these, metal oxide particles such as silica and titanium oxide whose surfaces are hydrophobized 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.

By applying the carrier of the present invention to a replenishment developer composed of a carrier and a toner and applying it to an image forming apparatus that forms an image while discharging excess developer in the developing device, a stable image can be obtained over a very long period of time. Quality is obtained. That is, the deteriorated carrier in the developing device and the non-deteriorated carrier in the replenishing developer are replaced, and the charge amount is kept stable over a long period of time, so that a stable image can be obtained. This method is particularly effective when printing a large image area. When printing a large image area, carrier charge deterioration due to toner spent on the carrier is the main carrier deterioration. However, when this method is used, the carrier replenishment amount increases when the image area is large, and the deteriorated carrier is replaced. Increases frequency. Thereby, a stable image can be obtained for an extremely long period of time.
The mixing ratio of the replenishment developer is preferably 2 to 50 parts by mass of toner with respect to 1 part by mass of the carrier. When the amount of toner is less than 2 parts by mass, the amount of replenishment carrier is excessive, the carrier is excessively supplied, and the carrier concentration in the developing device becomes too high, so that the charge amount of the developer tends to increase. Further, when the developer charge amount increases, the developing ability decreases and the image density decreases. On the other hand, if the amount exceeds 50 parts by mass, the carrier ratio in the replenishment developer decreases, so that the replacement of carriers in the image forming apparatus decreases, and the effect on carrier deterioration cannot be expected.

The image forming method of the present invention includes at least a step of performing image formation using a carrier and a toner, and the carrier includes the carrier of the present invention.
FIG. 2 shows an example of a process cartridge to which the image forming method of the present invention is applied. The process cartridge 100 includes a photosensitive member 101, a charging device 102 that charges the photosensitive member 101, and a developing device that develops an electrostatic latent image formed on the photosensitive member 101 using the developer of the present invention to form a toner image. 103 and a toner image formed on the photoconductor 101 are transferred to a recording medium, and a cleaning device 104 that removes the toner remaining on the photoconductor 101 is integrally supported. The process cartridge 100 is a copier, It can be attached to and detached from the main body of an image forming apparatus such as a printer.
Hereinafter, a method for forming an image using the image forming apparatus equipped with the process cartridge 100 will be described. First, the photosensitive member 101 is rotationally driven at a predetermined peripheral speed, and the charging device 102 uniformly charges the peripheral surface of the photosensitive member 101 to a predetermined positive or negative potential. Next, exposure light is irradiated onto the peripheral surface of the photosensitive member 101 from an exposure apparatus (not shown) such as a slit exposure type exposure apparatus or an exposure apparatus that performs scanning exposure with a laser beam, and electrostatic latent images are sequentially formed. Further, the electrostatic latent image formed on the peripheral surface of the photoconductor 101 is developed by the developing device 103 using the developer of the present invention to form a toner image. Next, the toner image formed on the peripheral surface of the photoconductor 101 is fed between a photoconductor 101 and a transfer device (not shown) from a paper feed unit (not shown) in synchronization with the rotation of the photoconductor 101. The images are sequentially transferred onto the transferred transfer paper. Further, the transfer paper onto which the toner image has been transferred is separated from the peripheral surface of the photoconductor 101, introduced into a fixing device (not shown) and fixed, and then transferred to the outside of the image forming apparatus as a copy (copy). Printed out. On the other hand, after the toner image is transferred, the surface of the photoconductor 101 is cleaned by removing residual toner by a cleaning device 104, and then neutralized by a static eliminator (not shown) and repeatedly used for image formation. Is done.

The present invention also provides a developer containing unit containing the developer of the present invention.
The developer accommodating unit in the present invention refers to a unit in which a developer is accommodated in a unit having a function of accommodating a developer.
Here, as an aspect of the developer accommodating unit, there are a container containing a developer, a developing device, and a process cartridge.
A container containing a developer means a container containing a developer.
The developing unit is a unit having a means for containing and developing a developer.
As described above, the process cartridge refers to a cartridge in which at least the image carrier and the developing unit are integrated and detachable from the image forming apparatus. At least one of the charging unit, the exposure unit, and the cleaning unit, and the image carrier and the developing unit may be integrated.

  An image forming apparatus to which the image forming method of the present invention is applied, for example, forms an electrostatic latent image on the latent image carrier, an electrostatic latent image carrier, charging means for charging the latent image carrier, and the like. An exposure unit, a developing unit that develops the electrostatic latent image formed on the electrostatic latent image carrier using a developer to form a toner image, and an electrostatic latent image carrier formed on the electrostatic latent image carrier. Transfer means for transferring the toner image to the recording medium, and fixing means for fixing the toner image transferred to the recording medium, and other means appropriately selected as necessary, for example, static elimination means , A cleaning means, a recycling means, a control means, etc., and the developer of the present invention is used as a developer.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. “Part” means part by mass.

(Resin synthesis example 1)
300 g of toluene was charged into a flask equipped with a stirrer, and the temperature was raised to 90 ° C. under a nitrogen gas stream. Subsequently, to this, 3-methacryloxypropyltris (trimethylsiloxy) silane 84.CH ₂ = CMe—COO—C ₃ H ₆ —Si (OSiMe ₃ ) ₃ (wherein Me is a methyl group). 4 g (200 mmol: Silaplane TM-0701T / manufactured by Chisso Corporation), 3-methacryloxypropylmethyldiethoxysilane 39 g (150 mmol), methyl methacrylate 65.0 g (650 mmol), and 2,2′- A mixture of 0.58 g (3 mmol) of azobis-2-methylbutyronitrile was added dropwise over 1 hour. After completion of the dropwise addition, a solution prepared by dissolving 0.06 g (0.3 mmol) of 2,2′-azobis-2-methylbutyronitrile in 15 g of toluene was further added (2,2′-azobis-2-methylbutyrate). A total amount of ronitrile (0.64 g = 3.3 mmol) was mixed at 90 to 100 ° C. for 3 hours and radical copolymerized to obtain a methacrylic copolymer R1 having a weight average molecular weight of 35,000.

(Carrier Production Example 1)
Methacrylic copolymer R1 obtained in Synthesis Example 1 [solid content: 100% by mass]: 20 parts, silicon resin solution [solid content: 20% by mass]: 100 parts, aminosilane [solid content: 100% by mass]: 3.0 Parts, magnesium hydroxide fine particles (manufactured by Sakai Chemicals, volume average particle size 700 nm): 36 parts, oxygen-deficient tin fine particles (manufactured by Mitsui Metals, primary particle size 30 nm): 60 parts, titanium diisopropoxybis ( Ethyl acetoacetate) TC-750 (manufactured by Matsumoto Fine Chemical Co.) 2 parts was diluted with toluene to obtain a resin solution having a solid content of 20 wt%.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material, and using an atomizing nozzle in the fluidized bed type coating apparatus so that the average film thickness of the resin layer is 0.70 μm on the core material surface, The temperature in the fluid tank was controlled to 60 ° C., and the resin solution was applied and dried. The obtained carrier was baked in an electric furnace at 210 ° C./1 hour to obtain carrier 1. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 1 was 710 nm.

(Carrier Production Example 2)
Conduct carrier production in exactly the same manner as in Carrier Production Example 1 except that the volume average particle size of the magnesium hydroxide fine particles is 500 nm and the average film thickness of the resin layer is 1.00 μm on the core material surface. Carrier 2 corresponding to Example 2 was obtained. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 2 was 505 nm.

(Carrier Production Example 3)
Conduct carrier production in exactly the same manner as in Carrier Production Example 1, except that the volume average particle size of the magnesium hydroxide fine particles is 500 nm and the average film thickness of the resin layer is 0.30 μm on the core surface. Carrier 3 corresponding to Example 3 was obtained. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 3 was 505 nm.

(Carrier Production Example 4)
A carrier 4 corresponding to the carrier production example 4 was obtained in exactly the same manner as the carrier production example 1 except that the prescription amount of the magnesium hydroxide fine particles was changed to 30 parts.

(Carrier Production Example 5)
A carrier 5 corresponding to the carrier production example 5 was obtained in exactly the same manner as the carrier production example 1 except that the average film thickness of the resin layer was changed to 1.50 μm on the surface of the core material.

(Carrier Production Example 6)
A carrier 6 corresponding to the carrier production example 6 was obtained in exactly the same manner as the carrier production example 1 except that the prescription amount of the magnesium hydroxide fine particles was changed to 53 parts.

(Carrier Production Example 7)
Conduct carrier production in exactly the same manner as Carrier Production Example 1 except that the volume average particle size of the magnesium hydroxide fine particles is 500 nm and the average film thickness of the resin layer is 0.55 μm on the core surface. Carrier 7 corresponding to Example 7 was obtained. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 7 was 505 nm.

(Carrier Production Example 8)
Conduct carrier production in exactly the same manner as in Carrier Production Example 1, except that the volume average particle size of the magnesium hydroxide fine particles is 400 nm and the average film thickness of the resin layer is 0.55 μm on the core surface. Carrier 8 corresponding to Example 8 was obtained. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 8 was 408 nm.

(Carrier Production Example 9)
Methacrylic copolymer R1 [solid content 100% by mass]: 20 parts, silicon resin solution [solid content 20% by mass]: 100 parts, aminosilane [solid content 100% by mass]: 3.0 parts, magnesium hydroxide as fine particles Fine particles (manufactured by Sakai Chemicals, volume average particle size 900 nm, equivalent circle diameter in the resin layer measured by the method for measuring equivalent circle diameter is 902 nm): 72 parts, oxygen deficient tin fine particles (Mitsui Metals, primary particle size 30 nm): 60 parts, 2 parts of titanium diisopropoxybis (ethylacetoacetate) TC-750 (manufactured by Matsumoto Fine Chemical Co., Ltd.) as a catalyst were diluted with toluene to obtain a resin solution 1 having a solid content of 20 wt%.
Further, methacrylic copolymer R1 [solid content 100% by mass]: 20 parts, silicon resin solution [solid content 20% by mass]: 100 parts, aminosilane [solid content 100% by mass]: 3.0 parts, hydroxylated as fine particles Magnesium fine particles (manufactured by Sakai Chemicals, volume average particle size 700 nm, equivalent circle diameter in the resin layer measured by the method for measuring equivalent circle diameter is 710 nm): 36 parts, oxygen deficient tin fine particles (Mitsui Metals, primary particles (Diameter 30 nm): 60 parts, 2 parts of titanium diisopropoxybis (ethylacetoacetate) TC-750 (manufactured by Matsumoto Fine Chemical Co., Ltd.) as a catalyst were diluted with toluene to obtain a resin solution 2 having a solid content of 20 wt%.
Using Mn ferrite particles having a weight average particle diameter of 35 μm as the core material, the average film thickness of the resin layer on the surface of the core material is 0.70 μm, and the ratio of the resin solutions 1 and 2 is equal. Using a atomizing nozzle in the fluidized bed type coating apparatus, the temperature in the fluidized tank was controlled at 60 ° C., and the resin solution 1 and the resin solution 2 were applied and dried in this order. The obtained carrier was baked in an electric furnace at 210 ° C./1 hour to obtain a carrier 9 corresponding to Carrier Production Example 9.

(Carrier Production Example 10)
A carrier 10 corresponding to Carrier Production Example 10 was obtained in exactly the same manner as Carrier Production Example 9, except that the average film thickness of the resin layer was changed to 0.55 μm on the surface of the core material.

(Carrier Production Example 11)
Carrier 11 corresponding to carrier production example 11 was obtained in exactly the same manner as carrier production example 1 except that the volume average particle size of the magnesium hydroxide fine particles was changed to 900 nm. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 11 was 902 nm.

(Carrier Production Example 12)
A carrier 12 corresponding to the carrier production example 12 was obtained in exactly the same manner as the carrier production example 1 except that the volume average particle size of the magnesium hydroxide fine particles was changed to 200 nm. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 12 was 205 nm.

(Carrier Production Example 13)
Carrier 13 corresponding to carrier production example 13 was obtained in exactly the same manner as carrier production example 1, except that the volume average particle size of the magnesium hydroxide fine particles was changed to 500 nm. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 13 was 505 nm.

(Carrier Production Example 14)
A carrier 14 corresponding to the carrier production example 14 was obtained in exactly the same manner as the carrier production example 1 except that the volume average particle size of the magnesium hydroxide fine particles was changed to 1000 nm. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 14 was 1018 nm.

(Carrier Production Example 15)
A carrier 15 corresponding to Carrier Production Example 15 was obtained in exactly the same manner as Carrier Production Example 1 except that the volume average particle size of the magnesium hydroxide fine particles was changed to 150 nm. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 15 was 149 nm.

(Carrier Production Example 16)
The carrier 16 corresponding to the carrier production example 16 is the same as the carrier production example 1 except that magnesium hydroxide fine particles coated with oxygen deficient tin on the surface with an average film thickness of 0.15 μm are used. Obtained.

(Carrier Production Example 17)
Carrier 17 corresponding to carrier production example 17 was obtained in exactly the same manner as carrier production example 1, except that methacrylic copolymer R1 was not used and the formulation amount of the silicone resin solution was changed to 200 parts.

(Carrier Production Example 18)
A carrier 18 corresponding to carrier production example 18 was obtained in exactly the same manner as carrier production example 1 except that oxygen-deficient tin fine particles were not used.

(Carrier Production Comparative Example 1)
The carrier production comparison was made in exactly the same manner as in Carrier Production Example 1, except that the volume average particle size of the magnesium hydroxide fine particles was changed to 200 nm and the average film thickness of the resin layer on the core material surface was changed to 1.00 μm. A carrier 19 corresponding to Example 1 was obtained. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 19 was 201 nm.

(Carrier Production Comparative Example 2)
The carrier production comparison was made in exactly the same manner as in Carrier Production Example 1, except that the volume average particle size of the magnesium hydroxide fine particles was changed to 900 nm and the average film thickness of the resin layer was 0.30 μm on the core material surface. A carrier 20 corresponding to Example 2 was obtained. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 20 was 899 nm.

(Carrier Production Comparative Example 3)
A carrier 21 corresponding to carrier production comparative example 3 was obtained in exactly the same manner as carrier production example 1 except that the volume average particle size of the magnesium hydroxide fine particles was changed to 80 nm. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 21 was 83 nm.

(Carrier Production Comparative Example 4)
A carrier 22 corresponding to Carrier Production Comparative Example 4 is obtained in exactly the same manner as Carrier Production Example 1 except that magnesium hydroxide fine particles are not used and alumina fine particles having a volume average particle diameter of 600 nm are used instead. It was. The equivalent circle diameter of the magnesium hydroxide fine particles in the resin layer of the carrier 22 was 605 nm.

<Example of toner production>
-Synthesis of polyester resin A-
Into a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 65 parts of a 2-mole addition product of ethylene oxide of bisphenol A, 86 parts of a 3-mole addition product of propion oxide of bisphenol A, 274 parts of terephthalic acid and 2 parts of dibutyltin oxide And allowed to react at 230 ° C. for 15 hours under normal pressure. Next, it was made to react under reduced pressure of 5-10 mmHg for 6 hours, and the polyester resin was synthesize | combined. The obtained polyester resin A has a number average molecular weight (Mn) of 2,300, a weight average molecular weight (Mw) of 8,000, a glass transition temperature (Tg) of 58 ° C., an acid value of 25 mgKOH / g, and a hydroxyl value of It was 35 mgKOH / g.

-Synthesis of prepolymer (polymer capable of reacting with active hydrogen group-containing compound)-
In a reaction vessel equipped with a cooling tube, a stirrer and a nitrogen introduction tube, 682 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 81 parts by mass of bisphenol A propylene oxide 2 mol adduct, 283 parts by mass of terephthalic acid, trimellitic anhydride 22 parts by mass and 2 parts by mass of dibutyltin oxide were charged and reacted at 230 ° C. for 8 hours under normal pressure. Subsequently, it was made to react under reduced pressure of 10-15mHg for 5 hours, and the intermediate polyester was synthesize | combined.
The obtained intermediate polyester has a number average molecular weight (Mn) of 2,100, a weight average molecular weight (Mw) of 9,600, a glass transition temperature (Tg) of 55 ° C., an acid value of 0.5, and a hydroxyl value of 49.
Next, 411 parts by mass of the intermediate polyester, 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate were charged in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introduction pipe, and reacted at 100 ° C. for 5 hours. Thus, a prepolymer (polymer capable of reacting with the active hydrogen group-containing compound) was synthesized.
The free isocyanate content of the obtained prepolymer was 1.60% by mass, and the solid content concentration of the prepolymer (after standing at 150 ° C. for 45 minutes) was 50% by mass.

-Synthesis of ketimine (the active hydrogen group-containing compound)-
In a reaction vessel equipped with a stir bar and a thermometer, 30 parts by mass of isophoronediamine and 70 parts by mass of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to synthesize a ketimine compound (the active hydrogen group-containing compound). The amine value of the obtained ketimine compound (the active hydrogen machine-containing compound) was 423.

-Preparation of master batch-
1,000 parts of water, DBP oil absorption 42 mL / 100 g, pH 9.5 carbon black Printex 35 (Degussa) 540 parts, and 1,200 parts of polyester resin A, Henschel mixer (Mitsui Mining) And mixed. Next, the obtained mixture was kneaded at 150 ° C. for 30 minutes using two rolls, then rolled and cooled, and pulverized with a pulverizer (manufactured by Hosokawa Micron Corporation) to prepare a master batch.

-Preparation of aqueous medium-
Aqueous medium was prepared by mixing and stirring 306 parts of ion-exchanged water, 265 parts of a 10% by mass suspension of tricalcium phosphate, and 1.0 part of sodium dodecylbenzenesulfonate, and dissolving them uniformly.

-Measurement of critical micelle concentration-
The critical micelle concentration of the surfactant was measured by the following method. Using a surface tension meter Sigma (manufactured by KSV Instruments), analysis was performed using an analysis program in the Sigma system. Surfactant was added dropwise by 0.01 wt% with respect to the aqueous medium, and the interfacial tension after stirring and standing was measured. From the obtained surface tension curve, the surfactant concentration at which the interfacial tension did not decrease even when the surfactant was dropped was calculated as the critical micelle concentration. When the critical micelle concentration of sodium dodecylbenzenesulfonate with respect to the aqueous medium was measured with a surface tension meter Sigma, it was 0.05 wt% with respect to the weight of the aqueous medium.

-Adjustment of toner material liquid-
In a beaker, 70 parts of polyester resin A, 10 parts by weight of prepolymer and 100 parts of ethyl acetate were added and dissolved by stirring. As a release agent, 5 parts of paraffin wax (HNP-9 melting point 75 ° C., manufactured by Nippon Seiki Co., Ltd.), 2 parts of MEK-ST (Nissan Chemical Industry Co., Ltd.), and 10 parts of masterbatch were added. After 3 passes under the condition that the liquid feeding speed is 1 kg / hour, the peripheral speed of the disk is 6 m / second, and 80% by volume of zirconia beads having a particle diameter of 0.5 mm are filled, the ketimine 2.7 is used. A part by mass was added and dissolved to prepare a toner material solution.

―Preparation of emulsion or dispersion―
150 parts by mass of the aqueous medium phase is put in a container, and stirred using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a rotational speed of 12000 rpm. To this, 100 parts by mass of the toner material dissolved or dispersed is added. The mixture was mixed for 10 minutes to prepare an emulsification or dispersion (emulsion slurry).

―Removal of organic solvent―
100 parts by mass of the emulsified slurry was charged into a Kolben equipped with a stirrer and a thermometer, and the solvent was removed at 30 ° C. for 12 hours while stirring at a stirring peripheral speed of 20 m / min.

-Washing-
After 100 parts by mass of the dispersion slurry was filtered under reduced pressure, 100 parts by mass of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (at a rotation speed of 12000 rpm for 10 minutes), and then filtered. An operation of adding 300 parts by mass of ion-exchanged water to the obtained filter cake, mixing with a TK homomixer (10 minutes at a rotation speed of 12000 rpm), and then filtering was performed twice. 20 mass parts of 10 mass% sodium hydroxide aqueous solution was added to the obtained filter cake, and it mixed by TK type homomixer (30 minutes at the rotation speed of 12000 rpm), and then filtered under reduced pressure. To the obtained filter cake, 300 parts by mass of ion-exchanged water was added, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered. An operation of adding 300 parts by mass of ion-exchanged water to the obtained filter cake, mixing with a TK homomixer (10 minutes at a rotation speed of 12000 rpm), and then filtering was performed twice. Furthermore, 20 mass parts of 10 mass% hydrochloric acid was added to the obtained filter cake, mixed with a TK type homomixer (rotation speed: 12000 rpm for 10 minutes) and then filtered.

-Surfactant adjustment-
To the filter cake obtained by the above washing, 300 parts by mass of ion-exchanged water was added, and the electrical conductivity of the toner dispersion when measured with a TK homomixer (10 minutes at 12,000 rpm) was measured in advance. The surfactant concentration of the toner dispersion was calculated from the calibration curve for the surfactant concentration prepared in (1). From this value, ion-exchanged water was added so that the surfactant concentration was the target surfactant concentration of 0.05 wt%, and a toner dispersion was obtained.

―Surface treatment process―
The toner dispersion liquid adjusted to the predetermined surfactant concentration was heated for 10 hours at a heating temperature T1 = 55 ° C. in a water bath while mixing at 5000 rpm with a TK homomixer. Thereafter, the toner dispersion was cooled to 25 ° C. and filtered. Further, 300 parts by mass of ion-exchanged water was added to the obtained filter cake, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered.

―Dry―
The obtained final filter cake was dried with a circulating dryer at 45 ° C. for 48 hours, and sieved with an opening of 75 μm mesh to obtain toner base particles 1.

―External treatment―
Further, with respect to 100 parts by weight of toner base particle 1, 3.0 parts by weight of hydrophobic silica having an average particle diameter of 100 nm, 1.0 part by weight of titanium oxide having an average particle diameter of 20 nm, and hydrophobicity having an average particle diameter of 15 nm. 1.5 parts of silica fine powder was mixed with a Henschel mixer to obtain [Toner 1].

<Create developer>
[Carrier 1] to [Carrier 22] (930 parts by mass) and toner 1 (70 parts by mass) obtained in Examples and Comparative Examples were mixed, and stirred for 5 minutes at 81 rpm using a Turbuler mixer, and evaluated. [Developer 1] to [Developer 22] were prepared. The replenishment developer was prepared using the carrier and the toner so that the toner concentration became 95% by mass.

Using the developer thus obtained, RICOH Pro C7110S manufactured by Ricoh Co., Ltd. printed 100,000 sheets at an image area ratio of 80%, and then collected the developer and removed the toner from the developer. [Mgα] was measured.
Further, the amount of Mg [Mgβ] on the surface of the carrier before treatment under the treatment conditions was determined, and [Mgα] − [Mgβ] was calculated. The results are shown in Tables 1 and 2.

<Developer characteristics evaluation>
Using each developer in RICOH Pro RICOH Pro C7110S (digital color copier / printer combined machine) manufactured by Ricoh Co., Ltd., an image area ratio of 40% is 10,000 sheets, an image area ratio of 40% is 1 million sheets, and an image area ratio of 80 One million sheets were printed at 1% or 1 million sheets were printed at an image area ratio of 0.5%, and one of the following running evaluations was performed. The low temperature and low humidity environment means an environment having a temperature of 10 ° C. and a relative humidity of 15%.

(Development ability)
A solid image and a halftone image were output and observed, and the unevenness image was visually evaluated. ◎ is a state where there is no density unevenness on the image, ◯ is a level where it is slightly observed but is not a problem, △ is a level where density unevenness is conspicuous but does not cause a problem, and × is a density unevenness It becomes a state that is a level that becomes a conspicuous problem.

(In-page concentration variation)
100 million A3 solid images were output continuously after running 1 million sheets, and the first, 50th, and 100th solid images were measured with a 938 Spectrodensitometer (X-Rite). . The measurement was carried out on a single sheet at a total of 6 locations, 3 locations in the sheet passing direction and 2 locations in the longitudinal direction, and the average value was adopted as the ID. The maximum value of the difference between the IDs of the first, 50th, and 100th sheets was evaluated as ΔID. The evaluation criteria are shown below.
0 or more and less than 0.05: ◎ (very good)
0.05 or more and less than 0.1: ○ (good)
0.1 or more and less than 0.2: △ (can be used)
0.2 or more: × (defect)

(Charge stability)
The charge amount of the carrier after running was measured, and the change rate of the charge amount was calculated.
In addition, the charge amount (Q1) of the initial carrier was measured using a blow-off device TB-200 (manufactured by Toshiba Chemical Co., Ltd.) for a frictionally charged sample. The charge amount (Q2) of the carrier after running 10,000 sheets or 1 million sheets is the same as above except that the carrier from which the toner of each color in the developer after running is removed using a blow-off device is used. Measured. The change rate of the charge amount was defined as an absolute value of (Q1-Q2) / Q1 × 100. The evaluation criteria are shown below.
0 to less than 5: ◎ (very good)
5 or more and less than 10: ○ (good)
10 or more and less than 20: △ (can be used)
20 or more: × (defect)

(Toner scattering)
After running 1 million sheets, the amount of toner collected at the bottom of the developer carrying member was sucked and collected, and the toner weight was measured. The evaluation criteria are shown below.
0 mg to less than 50 mg: ◎ (very good)
50 mg to less than 100 mg: ○ (good)
100 mg or more and less than 250 mg: Δ (can be used)
250 mg or more: × (defect)

<Soil dirt>
After running 1 million sheets, the blank image is stopped during development, the toner on the photoconductor after development is transferred to tape, and the difference (ΔID) from the image density of the untransferred tape is measured by 938 Spectrodensitometer (X-Rite) The measurement was carried out by the company). The evaluation criteria are shown below.
0 or more and less than 0.005: ◎ (very good)
0.005 or more to less than 0.01: ○ (good)
0.01 or more and less than 0.02: △ (can be used)
0.02 or more: × (defect)

<Ghost image>
Using A4 size paper, print the longitudinal band chart shown in the image chart as shown in FIG. 3A, and after one round of sleeves (a1) to (a3) as shown in FIG. 3B ( The density differences of b1) to (b3) were measured by X-Rite938 (manufactured by X-Rite), and the average density difference of the three measurement points of center, rear, and front was set as ΔID, and the ranks were classified below.
A: Very good, B: Good, B: Acceptable, B: Unusable for practical use A: B, B, C: Passed and x: Fail.
A: 0.01 ≧ ΔID
○: 0.01 <ΔID ≦ 0.03
Δ: 0.03 <ΔID ≦ 0.06
×: 0.06 <ΔID

<Developer amount stability>
The developer amount after passing through the developing doctor of the developing device is collected using a measuring jig (a jig capable of collecting 1 cm ² of developer), and its weight is measured. Three points were measured in the longitudinal direction of the developing sleeve, and the average value was taken as the developer amount on the sleeve. This was measured after the initial time and after running 1 million sheets, and evaluated by the absolute value of the difference. The evaluation criteria are shown below.
0 mg to less than 1 mg: ◎ (very good)
1 mg to less than 2 mg: ○ (good)
2 mg to less than 4 mg: △ (available)
4mg or more: × (defect)

<Solid carrier adhesion>
As described above, running of 1 million sheets at an image area ratio of 0.5% was performed, and the subsequent solid image was subjected to predetermined development conditions (charging potential (Vd): −600 V, the portion corresponding to the image portion (solid original)). Image formation is interrupted by, for example, turning off the power during image formation at a subsequent potential: −100 V, development bias: DC −500 V), and the number of carrier deposits on the photoconductor after transfer is counted and evaluated. Carried out. The area to be evaluated was a 10 mm × 100 mm area on the photoreceptor. ◎ is a state where the number of carrier adhesion is 0, ○ is a state where the number of carrier adhesion is 1 to 3, △ is a state where the number of carrier adhesion is 4 to 10, and x is a number where the carrier adhesion is 11 It will be in the above state. ◎, ○ and △ were accepted, and x was rejected.

  The above results are shown in Tables 1 and 2.

From the results in Tables 1 and 2, the developer in the example uses a carrier having a resin layer containing magnesium hydroxide fine particles, and the Mg amount [Mgα] on the carrier surface is 4.2 atomic% or more and 13.2 atomic%. Since the following settings are made, sufficient charge control can be performed on the toner, a stable developer amount can be supplied to the development area, and low images can be obtained even in a high-speed machine using low-temperature fixing toner. It has been found that continuous paper feeding with a printing density of area ratio is possible, and the image quality required in the field of production printing can be sufficiently satisfied.
On the other hand, the developers of Comparative Examples 1 to 4 did not satisfy the above requirements of the present invention, and therefore could not satisfy all the characteristics.

11 cell 12a, 12b electrode 13 carrier 100 process cartridge 101 photoconductor 102 charging means 103 developing means 104 cleaning means

JP-A-11-202560 JP 2006-39357 A JP 2010-117519 A Japanese Patent No. 5534409 JP 2011-209678 A JP 2009-63805 A

Claims (10)

A carrier having at least magnesium hydroxide-containing fine particles in the resin layer, and the amount of magnesium [Mgα] on the surface of the carrier after the treatment under the following predetermined conditions is 4.2 atomic% or more and 13.2 atomic% or less. A career characterized by that.
Processing conditions: In an image forming apparatus using a developer having a toner concentration of 7% by mass and a carrier concentration of 93% by mass, after printing 100,000 sheets at an image area ratio of 80%, the developer is recovered. The amount of Mg on the surface of the carrier from which the toner has been removed from the developer is defined as “the amount of Mg on the surface after processing [Mgα]”.   2. The carrier according to claim 1, wherein the amount of Mg [Mgβ] on the surface of the carrier before treatment under the treatment conditions is 3.2 atomic% or more and 12.2 atomic% or less. The amount of magnesium [Mgα] on the surface after the treatment under the above treatment conditions and the amount of magnesium [Mgβ] on the surface before the treatment satisfy the following formula: 15 ≧ [Mgα] − [Mgβ] ≧ 1 (atomic%)
The carrier according to claim 1 or 2, characterized by the above.   The carrier according to any one of claims 1 to 3, wherein the equivalent circle diameter of the fine particles is 200 nm or more and 900 nm or less.   The carrier according to any one of claims 1 to 4, wherein magnesium hydroxide is present on the surface of the fine particles. The said carrier contains the resin obtained by heat-processing the copolymer in which the resin component in the said resin layer contains the following 2 types of monomer at least, The Claim 1 thru | or 5 characterized by the above-mentioned. Career.
(In the formula, R ¹ , m, R ² , R ³ , X, and Y are as follows.)
R ¹ : hydrogen atom, or methyl group m: alkylene group having 1 to 8 carbon atoms R ² : alkyl group having 1 to 4 carbon atoms R ³ is an alkyl group having 1 to 8 carbon atoms, or 1 to 1 carbon atoms 4 alkoxy groups X = 10 to 90 mol%
Y = 10-90 mol%   A developer comprising the carrier and the toner according to claim 1.   A replenishment developer comprising a carrier and a toner, the toner being contained in an amount of 2 to 50 parts by weight with respect to 1 part by weight of the carrier, wherein the carrier is the carrier according to any one of claims 1 to 6. A developer for replenishment.   A developer containing unit containing the developer according to claim 7. An image forming method comprising at least a step of forming an image using a carrier and a toner, wherein the carrier includes the carrier according to claim 1.