JP4673790B2 - Electrophotographic carrier, developer, image forming method, process cartridge, image forming apparatus - Google Patents

Description

  The present invention relates to a color carrier and a developer used for developing an electrostatic image in electrophotography, electrostatic recording, electrostatic printing, and the like, and an image forming method, a process cartridge, and an image forming apparatus using the developer.

  In electrophotographic image formation, a latent image is formed by an electrostatic charge on an image carrier such as a photoconductive substance, and a charged toner particle is attached to the electrostatic latent image to form a visible image. After that, the toner image is transferred to a recording medium such as paper and fixed to form an output image. In recent years, the technology of copiers and printers using an electrophotographic system has been rapidly expanding from monochrome to full color, and the full color market tends to expand. Color image formation by full-color electrophotography generally reproduces all colors by laminating three color toners of three primary colors, yellow, magenta, and cyan, or four color toners with black added thereto. . Therefore, in order to obtain a clear full color image with excellent color reproducibility, it is necessary to smooth the fixed toner image surface to some extent to reduce light scattering. For these reasons, the image gloss of conventional full-color copying machines and the like is often 10 to 50%, 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. This method has high thermal efficiency and high-speed fixing, and is advantageous in that it can give gloss and transparency to the color toner. However, the surface of the heat-fixing member is brought into contact with the molten toner under pressure. The post-peeling causes a so-called offset phenomenon in which a part of the toner image adheres to the surface of the fixing roller and re-transfers to another image. In order to prevent this offset phenomenon, a method is generally adopted in which the fixing roller surface is formed of silicone rubber or fluororesin with excellent releasability, and then a release oil such as silicone oil is applied to the fixing roller surface. It had been. However, this method is extremely effective in preventing toner offset, but requires a device for supplying release oil, and is unsuitable for downsizing the machine due to the increase in size of the fixing device. For this reason, in a monochrome toner, by adjusting the molecular weight distribution of the binder resin so that the melted toner does not break internally, the viscoelasticity at the time of melting of the toner is increased, and a release agent such as wax is further included in the toner. There is a tendency to employ a method in which the release oil is not applied to the fixing roller (oilless) or the amount of oil applied is very small.

  On the other hand, in the case of color toners as well as monochrome toners, there is a tendency toward oil-less for the purpose of downsizing machines and simplifying the configuration. However, as described above, in order to improve the color reproducibility of the color toner, it is necessary to smooth the surface of the fixed image, so the viscoelasticity at the time of melting must be lowered, and it is easier to offset than the glossy monochrome toner. Therefore, it is more difficult to make the fixing device oil-free and to apply a small amount. In addition, when a release agent is contained in the toner, the adhesion of the toner is increased and the transfer property to the transfer paper is lowered. Further, the release agent in the toner contaminates the frictional charging member such as a carrier to reduce the charging property. This causes a problem that the durability is lowered.

  On the other hand, regarding the carrier, prevention of filming of toner components on the carrier surface, formation of a uniform carrier surface, prevention of surface oxidation, prevention of moisture sensitivity deterioration, extension of developer life, prevention of carrier adhesion to the surface of the photoreceptor, photoreceptor For the purpose of protection from scratches or abrasion by the carrier, control of the charge polarity or adjustment of the charge amount, a hard and high-strength coating layer is usually provided by coating with an appropriate resin material. For example, those coated with a specific resin material (for example, refer to Patent Document 1), and further, various additives are added to the coating layer (for example, Patent Documents 2, 3, 4, 5, 6, 7, 8), further using a carrier surface with an additive attached (for example, see Patent Document 9), and using a coating layer containing conductive particles larger than the coating layer thickness. (For example, see Patent Document 10) have been disclosed. Further, it is described that a benzoguanamine-n-butyl alcohol-formaldehyde copolymer is used as a main component for a carrier coating material (see, for example, Patent Document 11), and a cross-linked product of a melamine resin and an acrylic resin is used as a carrier coating material. Is described (for example, see Patent Document 12).

  However, durability and carrier adhesion suppression are still insufficient. Concerning durability, there are problems such as spent toner on the carrier surface, destabilization of the charge amount, and reduction of the coating layer due to film removal of the coating resin and accompanying resistance reduction. However, as the number of copies increases, the image quality of the copied image deteriorates, which is a problem and needs to be improved.

  Furthermore, while the demand for faster and more beautiful is increasing, the speed of machines in recent years is remarkable. Along with this, the stress received by the developer has also increased dramatically, and it has become impossible to obtain a sufficient life even with a carrier that has been long-lived in the past. In addition, carbon black has been used as a carrier resistance adjusting agent in the past, but there is a concern about color stains caused by film removal or / and migration of carbon black into a color image due to carbon black detachment. As a countermeasure, various methods have been proposed and demonstrated their effects. For example, a carrier has been proposed in which a conductive agent (carbon black) is present on the surface of the core material and no conductive material is present in the resin coating layer (see, for example, Patent Document 13). In addition, a carrier is proposed in which the coating resin layer has a carbon black concentration gradient in the thickness direction, the carbon black concentration decreases toward the surface of the coating resin layer, and carbon black is not present on the surface of the coating layer. (For example, see Patent Document 14). In addition, a two-layer coated carrier has been proposed in which an inner coating resin layer containing conductive carbon is provided on the surface of core material particles, and a surface coating resin layer containing a white conductive material is further provided thereon. (For example, refer to Patent Document 15). However, it cannot cope with the recent increase in stress, and color stains have become a problem and need to be improved.

  As a drastic measure against color stains, it is obvious that the most effective method is to eliminate carbon black that causes color stains. However, when carbon black is simply pulled out, the resistance of the carrier increases because carbon black has the property of low electrical resistance as described above. In general, when a carrier having a high resistance is used as a developer, on the image surface of a large area of a copy image, the image density at the center is very thin and only the edges are expressed deeply, so-called edge effect is sharply used. It becomes the image that was. In addition, when the image is a character or a thin line, the image is clear due to the edge effect. However, when the image is halftone, there is a defect that the image is very reproducible.

Generally, as a resistance adjuster other than carbon black, for example, titanium oxide, zinc oxide, etc. are known, but as an effect of lowering resistance, an effect sufficient to replace carbon black cannot be obtained, and there is a problem It has not yet been resolved and needs to be improved.
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-9-160304 JP-A-8-6307 Japanese Patent No. 2683624 Japanese Unexamined Patent Publication No. 7-140723 JP-A-8-179570 JP-A-8-286429

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to form a fine image with excellent durability and no edge effect over a long period of time. It is an object to provide a good electrophotographic carrier and developer that does not cause the above-mentioned problem, and to provide an image forming method using the developer, a process cartridge, and an image forming apparatus equipped with the process cartridge.

  According to the present invention, the above problem is achieved by the following means.

  That is, the above-described problems are solved by an electrophotographic developer carrier having at least a coating layer on a carrier core material, wherein the coating layer contains an ionic liquid.

In the carrier for an electrophotographic developer, the ionic conductivity of the ionic liquid contained in the coating layer is 1.0 × 10 ⁻³ (S / cm) or more.

  The electrophotographic developer carrier further includes inorganic fine particles in the coating layer.

  In the electrophotographic developer carrier, the inorganic fine particles contain 70% or more of the coating ratio with respect to the core material. The particle diameter (D) of the particles and the coating layer thickness (h) Is 0.5 <[D / h] <1.5.

  The electrophotographic developer carrier is characterized in that the carrier has a volume resistivity of 10 [Log (Ω · cm)] to 16 [Log (Ω · cm)].

  In the electrophotographic developer carrier, the volume average particle size of the carrier is 20 μm or more and 65 μm or less.

  In the electrophotographic developer carrier, at least the binder resin is a silicon resin.

  In the electrophotographic developer carrier, at least the binder resin is an acrylic resin and a silicon resin.

In the carrier for electrophotographic developer, the magnetic moment at 1000 (10 ³ / 4π · A / m) is 40 (Am ² / kg) or more and 90 (Am ² / kg) or less. .

  In addition, the above-described problems are solved by an electrophotographic developer characterized by comprising at least a toner composed of a binder resin and a pigment and the above-described electrophotographic carrier.

  In the electrophotographic developer, the toner is a color toner.

  In addition, the above-described problems include a step of forming an electrostatic latent image on an image carrier, a step of developing the electrostatic latent image with a developer composed of at least a carrier and a toner, and forming a visible image. This is solved by an image forming method having a step of transferring and fixing a visual image onto a recording member, wherein the developer uses the electrophotographic developer described above.

  Further, the above-described problem is that in the process cartridge that integrally supports at least one developing unit selected from the photosensitive member and the charging unit, the developing unit, and the cleaning unit and is detachable from the main body of the image forming apparatus, the developing unit includes: The problem is solved by a process cartridge that holds the developer and is the electrophotographic developer described above.

  Further, the above-described problems are at least a photoconductor, a developing unit that forms an image on the photoconductor, a transfer unit that transfers an image on the photoconductor to a transfer material, and an image on the transfer material is fixed. This is solved by an image forming apparatus provided with a fixing unit that mounts the process cartridge described above.

  According to the present invention, it is possible to obtain a high-definition image with no carrier adhesion and good image density reproducibility. Deterioration in image quality such as color stains that occur as the number of copies increases is greatly improved. Further, since the amount of charge and resistance change are small, it has an excellent effect that a good image can be maintained over a long period of time. It is.

  The best mode for carrying out the present invention will be described below with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

  Hereinafter, the present invention will be described in more detail.

  The ionic liquid used in the present invention has general physical properties as an ionic liquid, that is, a liquid state in a wide temperature range of about −100 ° C. to 200 ° C., a high ionic conductivity, and a non-volatile property. Any material that is not flammable or combustible and has high thermal stability can be used.

However, in the present invention, it does not decompose in the temperature range used in the production process of the developer for developing an electrostatic latent image (resin thermosetting and solvent removal), that is, at least in the temperature range of 100 to 300 ° C. Is preferred. The ionic conductivity of the ionic liquid is not particularly limited, but is preferably 1.0 × 10 ⁻³ (S / cm) or more within a temperature range of 10 to 30 ° C. If it is less than 1.0 × 10 ⁻³ (S / cm), the effect of reducing the resistance as a carrier cannot be expected. When the carrier resistance is high, abnormal images such as carrier adhesion (edge carrier adhesion) and white spots on the non-image portion occur.

  The specific composition of the ionic liquid used in the present invention is not particularly limited as long as it has physical properties as a general ionic liquid. It is preferable that physical properties such as ion conduction characteristics are more suitable.

  In the present invention, as a method for measuring the ionic conductivity of the ionic liquid, measurement was performed at a frequency of 10 kHz and 25 ° C. using a closed conductivity measuring cell and an AC impedance meter (CM-40S, manufactured by Toa Denki Kogyo).

Examples of organic cationium salts include ammonium salts, imidazolium derivatives, pyridinium, phosphonium, etc., and examples of organic acid anions include BF ₄ −, PF ₆ —, CF ₃ SO ₃ — (Tf: triflate), and (CF ₃ SO ₂ ). ₂ N- (TFSI) and the like. Of these, salts of ethylmethylimidazolium (EMI) and butylmethylimidazolium (BMI) are preferably used. In this invention, you may use the ionic substance containing the component melt | dissolved in an ionic liquid besides these.

  The resistance value of the carrier of the present invention is not particularly limited as long as it is measured by the carrier resistance measuring device of FIG. 3 and is in the range of about 10 to 16 log Ω · cm, and can be adjusted according to the application. The content of the ionic liquid contained in the coating layer is not particularly limited and can be determined in consideration of a desired resistance value and ionic conductivity of the ionic liquid to be used.

  As the ionic liquid, it is preferable to use a pyridinium (Formula 1), imidazolium (Formula 2), alicyclic amine (Formula 3), or aliphatic amine (Formula 4) material. Specifically, pyridinium ionic liquids IL-P11 and IL-P14 manufactured by Guangei Chemical Industry Co., Ltd., imidazolium ionic liquids IL-IM1 and alicyclic amine ionic liquids IL-C1 and IL-C3. IL-C5, and aliphatic amine-based ionic liquids IL-A1, IL-A2, IL-A3, IL-A4, and IL-A5 can be used.

  (Formula 1)

（式中のＲ、Ｒ’は同一でも異なっていてもよく、それぞれ水素元素、炭素数１〜８の脂肪族炭化水素残基、炭素数５〜７のシクロアルキル基又はフェニル基を示す。）
（式２）

(R and R ′ in the formula may be the same or different and each represents a hydrogen element, an aliphatic hydrocarbon residue having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a phenyl group.)
(Formula 2)

（式中のＲ、Ｒ’は同一でも異なっていてもよく、それぞれ水素元素、炭素数１〜８の脂肪族炭化水素残基、炭素数５〜７のシクロアルキル基又はフェニル基を示す。）
（式３）

(R and R ′ in the formula may be the same or different and each represents a hydrogen element, an aliphatic hydrocarbon residue having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a phenyl group.)
(Formula 3)

（式中のＲ、Ｒ’は同一でも異なっていてもよく、それぞれ水素元素、炭素数１〜８の脂肪族炭化水素残基、炭素数５〜７のシクロアルキル基又はフェニル基を示す。）
（式４）

(R and R ′ in the formula may be the same or different and each represents a hydrogen element, an aliphatic hydrocarbon residue having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a phenyl group.)
(Formula 4)

（式中のＲ、Ｒ’、Ｒ’’、Ｒ’’’は同一でも異なっていてもよく、それぞれ水素元素、炭素数１〜８の脂肪族炭化水素残基、炭素数５〜７のシクロアルキル基又はフェニル基を示す。）
カラー画像のように高画質を求めるシステムにおいて、キャリアとしての抵抗調整は必須であり、抵抗が著しく高いキャリアでは非画像部へのキャリア付着（エッジキャリア付着）や白抜けなどの異常画像が発生する。キャリアとして抵抗調整を行う場合、従来では抵抗調整剤としてカーボンブラック、酸化チタン、酸化亜鉛、酸化インジウム、酸化インジウムにて表面処理した微粒子などの導電性微粒子をキャリア被覆層中に添加することで抵抗調整している。しかし、被覆層の削れにより導電性微粒子がトナー中に混入し、導電性微粒子が無色または白色以外の場合、カラー画像については色汚れの原因となる。カーボンブラック、酸化インジウムなどは少量にてキャリア抵抗を引き下げる効果があるが、色汚れの問題で使用することができない。また、酸化亜鉛、酸化インジウム処理微粒子は白色であるがカーボンブラックのように抵抗引き下げ効果が少量では得られず、被覆層中に多量に添加しなければならなく、大量に添加するためにキャリア被覆層中で導電性微粒子が偏在してしまう。導電性微粒子の偏在個所が被覆層の削れにより露出すると、その個所が起点に電気的なリークポイントとなり、局所的な抵抗低下が発生する。抵抗低下により画像部へのキャリア付着が発生し、白抜けなどの異常画像となる。

(In the formula, R, R ′, R ″, and R ′ ″ may be the same or different, and each is a hydrogen element, an aliphatic hydrocarbon residue having 1 to 8 carbon atoms, or a cyclohexane having 5 to 7 carbon atoms. Represents an alkyl group or a phenyl group.)
In systems that require high image quality such as color images, it is essential to adjust resistance as a carrier. Carriers with extremely high resistance generate abnormal images such as carrier adhesion (edge carrier adhesion) or white spots on non-image areas. . When resistance adjustment is performed as a carrier, conventionally, resistance is improved by adding conductive fine particles such as carbon black, titanium oxide, zinc oxide, indium oxide and fine particles surface-treated with indium oxide as a resistance adjusting agent to the carrier coating layer. It is adjusted. However, if the conductive fine particles are mixed in the toner due to the scraping of the coating layer and the conductive fine particles are not colorless or white, it causes color stains in the color image. Carbon black, indium oxide, and the like have an effect of reducing carrier resistance in a small amount, but cannot be used due to the problem of color stains. In addition, zinc oxide and indium oxide-treated fine particles are white, but the effect of reducing the resistance cannot be obtained in a small amount like carbon black, and must be added in a large amount in the coating layer. Conductive fine particles are unevenly distributed in the layer. When the unevenly distributed portions of the conductive fine particles are exposed due to the scraping of the coating layer, the portions become electrical leak points from the starting point, and local resistance reduction occurs. Due to the decrease in resistance, carrier adhesion to the image portion occurs, resulting in an abnormal image such as white spots.

  The ionic liquid is a liquid, and is easily finely dispersed with the coating resin at the time of forming the coating layer liquid. As a result, the ionic liquid is present in a finely dispersed state in the carrier coating layer, so that local resistance reduction does not occur. In addition, since the ionic liquid is colorless to cloudy, even if the coating layer is scraped and mixed into the toner, color stains do not occur. Thus, this invention has a remarkable improvement effect by including an ionic liquid in a coating layer.

  The coating layer contains inorganic fine particles, and the inorganic fine particles contain 70% or more of the coating rate with respect to the core material. The reason for including the inorganic fine particles is to create unevenness on the surface of the carrier and to agitate the developer to frictionally charge, thereby relieving contact with a strong impact on the binder resin due to friction with toner or friction between carriers. can do. As a result, it is possible to prevent spent toner on the carrier.

The coverage in this invention is a coverage with respect to the core material of an inorganic oxide particle, and is represented by following Formula.
Coverage ratio = (Ds * ρs * W) / (4 * Df * ρf) * 100
(Ds: carrier core material particle size, ρs: carrier core material true specific gravity, W: ratio of added inorganic oxide particles to carrier core material, Df: inorganic oxide particle size, ρf: inorganic oxide particle true specific gravity)
The true specific gravity of the inorganic fine particles ρf and the carrier core material ρs was measured using a dry automatic bulk density meter Accupic 1330 (manufactured by Shimadzu Corporation). The carrier core particle diameter Ds (volume average particle diameter) can be measured by using an SRA type of a microtrack particle size analyzer (manufactured by Nikkiso Co., Ltd.). What was performed by the range setting of 0.7 micrometer or more and 125 micrometers or less was used. Further, methanol is used for the dispersion, and the refractive index is set to 1.33, and the refractive indexes of the carrier and the core material are set to 2.42. The particle diameter Df of the inorganic oxide particles is determined by measuring the volume average particle diameter using an automatic particle size distribution analyzer 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 the sample, set the 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: 2000 rpm
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: Enter the true specific gravity value measured using an automatic bulk density meter Accupic 1330 (manufactured by Shimadzu Corporation) for the density of the inorganic fine particles. If the coverage is less than 70%, the surface of the carrier core material is exposed due to film scraping over time. And the resistance is locally reduced, the carrier having such a state is developed in the solid image, and white spots are generated in the image.

  Further, since the particle diameter (D) of the inorganic fine particles contained in the carrier coating layer and the coating layer thickness (h) are 0.5 <[D / h] <1.5, the improvement effect is remarkable. It is. This is because when the particle diameter (D) and the coating resin film thickness (h) are 0.5 <[D / h] <1.5, the particles are more convex than the coating film. By agitation for triboelectrically charging the developer, contact with a strong impact on the binder resin can be eased by friction with toner or friction between carriers. As a result, it is possible to suppress film scraping of the binder resin, which is a place where charging occurs. In addition, since there are many particles on the carrier surface that are more convex than the coating film, it also exhibits a cleaning effect that efficiently scrapes off the spent component of the toner adhering to the carrier surface due to frictional contact between the carriers. Can be prevented. When [D / h] is 0.5 or less, the inorganic fine particles are buried in the binder resin, which is not preferable because the effect is remarkably lowered. When [D / h] is 1.5 or more, the contact area between the particles and the binder resin is small, so that a sufficient restraining force cannot be obtained and the particles are easily detached, which is not preferable. When desorbed, the resistance is lowered.

  The thickness h of the carrier coating layer was obtained from an average value by observing the cross section of the carrier using a transmission electron microscope (TEM), measuring the thickness of the resin portion of the coating layer covering the carrier surface. Specifically, only the thickness of the resin part existing between the core material surface and the particles is measured. The thickness of the resin part existing between the particles and the thickness of the resin part on the inorganic fine particles are not included in the measurement. The average of 50 arbitrary measurements on the carrier cross section was determined and defined as the thickness h (μm). The particle diameter (D) of the inorganic fine particles is measured with an ultracentrifugal automatic particle size distribution measuring apparatus CAPA-700 in the same manner as the particle diameter measuring method for inorganic fine particles described above.

  As the inorganic fine particles dispersed in the coating layer, any one of aluminum oxide, titanium dioxide, zinc oxide, silicon dioxide, barium sulfate, and zirconium oxide may be used alone or in combination. Further, a conductive layer treatment such as tin oxide-antimony oxide or tin oxide-indium oxide may be performed on the surface of these particles. However, when it comes off from the coating layer, it is mixed with the toner particles and causes color stains.

  Furthermore, the improvement effect is remarkable when the volume specific resistance of the carrier is 10 [Log (Ω · cm)] or more and 16 [Log (Ω · cm)] or less. This is not preferable because, when the volume resistivity is less than 10 [Log (Ω · cm)], carrier adhesion occurs in the non-image area. On the other hand, if the volume resistivity exceeds 16 [Log (Ω · cm)], the edge effect is deteriorated to an unacceptable level. In addition, when it falls below the measurable lower limit of the high resist meter, the volume specific resistance value is not substantially obtained, and it will be treated as a breakdown. The volume specific resistance referred to in this specification is a cell 31 made of a fluororesin container containing an electrode 32a having an interelectrode distance of 2 mm and a surface area of 2 × 4 cm, and an electrode 32b filled with a carrier 33 and manufactured by Sankyo Piotech Co., Ltd .: Using a tapping machine PTM-1 type, a tapping operation is performed for 1 minute at a tapping speed of 30 times / min. A DC voltage of 1000 V is applied between the two electrodes, the DC resistance is measured by a high resistance meter 4329A (4329A + LJK5HVLVWDQFH 0HWHU; manufactured by Yokogawa Hewlett-Packard Co., Ltd.), electric resistivity RΩ · cm is obtained, and LogR is calculated.

  Furthermore, when the volume average particle size is 20 μm or more and 65 μm or less, the improvement effect is remarkable. This is not preferable when the volume average particle size is less than 20 μm, since problems such as carrier adhesion occur due to a decrease in the uniformity of the particles and a lack of sufficient technology on the machine side. On the other hand, if it exceeds 65 μm, the reproducibility of image details is poor and a fine image cannot be obtained, which is not preferable. The volume average particle diameter of the carrier can be measured using an SRA type of a microtrack particle size analyzer (manufactured by Nikkiso Co., Ltd.). What was performed by the range setting of 0.7 micrometer or more and 125 micrometers or less was used. Further, methanol is used for the dispersion, and the refractive index is set to 1.33, and the refractive indexes of the carrier and the core material are set to 2.42.

  Furthermore, at least the binder resin is a silicon resin, so that the improvement effect is remarkable. This is because the silicone resin has a low surface energy, so that it is difficult for the toner component to be spent and the accumulation of the spent component due to film scraping is difficult to obtain.

  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.

  Moreover, the improvement effect is remarkable when at least the binder resin is used in combination with an acrylic resin. This is because acrylic resin has strong adhesion and low brittleness, so it has very excellent properties in abrasion resistance, and it is difficult for deterioration such as coating film scraping and film peeling, so the coating layer can be maintained stably. In addition, the particles contained in the coating layer such as conductive particles can be firmly held due to the strong adhesiveness. In particular, a powerful effect can be exhibited in holding particles having a particle size larger than the coating layer thickness. 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. Acrylic resin has excellent adhesion properties and low brittleness, so it has excellent wear resistance. On the other hand, its surface energy is high, so when it is combined with easily spent toner, toner component spent accumulates. In some cases, problems such as a decrease in charge amount due to the occurrence of charging. 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 that it has poor wear resistance. Therefore, it is important to obtain a good balance between the properties of these two types of resins, which makes it difficult to spend. It is possible to obtain a coating film having wear characteristics.

Furthermore, when the magnetic moment at 1000 (10 ³ / 4π · A / m) is 40 (Am ² / kg) or more and 90 (Am ² / kg) or less, the improvement effect is remarkable. This is because, within this range, the retention force between the carrier particles is appropriately maintained, so that the dispersion (mixing) of the toner into the carrier or developer is quickly and favorably improved. However, the magnetic moment at 1 KOe is 40 Am ^2. If it is less than / kg, carrier adhesion occurs due to insufficient magnetic moment, which is not preferable. On the other hand, when the magnetic moment at 1 KOe exceeds 90 Am ² / kg, the ears of the developer formed at the time of development become too hard, so that the reproducibility of image details is poor and a fine image cannot be obtained, which is not preferable. The magnetic moment can be measured as follows. Using a BH tracer (BHU-60 / manufactured by Riken Denshi Co., Ltd.), 1.0 g of carrier core particles are packed in a cylindrical cell (inner diameter 7 mm, height 10 mm) and set in an apparatus. The magnetic field is gradually increased and changed to 3000 Oersted, then gradually reduced to zero, and then the opposite magnetic field is gradually increased to 3000 Oersted. Further, after gradually reducing the magnetic field to zero, a magnetic field is applied in the same direction as the first. In this way, the BH curve is illustrated, and the magnetic moment of 1000 oersted is calculated from the figure.

[toner]
Further, since the toner is a color toner, the improvement effect is remarkable. This is because the carrier of the present invention does not contain carbon black in the coating layer, and therefore does not cause image color staining due to carbon black due to film scraping or the like. Therefore, it is very suitable for a color developer in which color reproducibility is regarded as important. The color toner referred to here includes not only a color toner generally used for a single color but also a black toner in addition to yellow, magenta, cyan, red, green, blue and the like used for full color.

  Here, the toner in the present invention will be described in detail. The toner in the present invention includes all the general toners regardless of whether they are monochrome toner, color toner or full color toner. For example, conventionally kneaded and pulverized toners and various polymerized toners that have been used in recent years can be used. Further, so-called oilless toner having a releasing agent can also be used. Since the carrier of the present invention has excellent spent resistance, good quality can be maintained over a long period of time. In particular, oilless full color toners are generally said to be spent easily because the binder resin is soft, but it can be said that the carrier of the present invention is very suitable.

  As the binder resin used in the toner of the present invention, known resins can be used. For example, styrene such as polystyrene, poly-p-styrene, and polyvinyltoluene, and homopolymers thereof, styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene- Methyl acrylate copolymer, Styrene-ethyl acrylate copolymer, Styrene-methacrylic acid copolymer Corp., Styrene-methyl acrylate copolymer, Styrene-ethyl acrylate copolymer, Styrene-methacrylic acid Butyl copolymer, styrene-α-chloromethacrylic acid methyl copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, Styrene-isopropyl copolymer, styrene-male Styrene copolymers such as acid ester copolymer, polythyme methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate, polyethylene, polyester, polyurethane, epoxy resin, polyvinyl butyral, polyacrylic acid resin, rosin, modified Rosin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic petroleum resin, or the like can be used alone or in combination.

  And as a binder resin for pressure fixing, a well-known thing can be mixed and used. For example, polyolefin such as low molecular weight polyethylene and low molecular weight polypropylene, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, styrene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer, ethylene-chlorinated Vinyl copolymer, ethylene-vinyl acetate copolymer, olefin copolymer such as ionomer resin, epoxy resin, polyester resin, styrene-butadiene copolymer, polyvinylpyrrolidone, methyl vinyl ether-maleic anhydride, maleic acid modified phenol resin Phenol-modified terpene resins and the like can be used alone or in combination, but are not limited thereto.

  Further, the toner used in the present invention may contain a fixing aid in addition to the binder resin, the colorant, and the charge control agent. Accordingly, it can be used in a fixing system in which toner fixing prevention oil is not applied to the fixing roll, so-called oilless system. Known fixing aids can be used. For example, polyolefins such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, paraffin waxes, amide waxes, polyhydric alcohol waxes, silicone varnishes, carnauba waxes and ester waxes can be used, but are not limited thereto.

  As the colorant used in the toner such as the color toner of the present invention, known pigments and dyes capable of obtaining yellow, magenta, cyan, and black toners can be used, and are not limited to those listed here. Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa Yellow G, Hansa Yellow 10G, Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, and Tartrazine Lake. Can be mentioned.

  Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.

  Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.

  Examples of purple pigments include fast violet B and methyl violet lake.

  Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.

  Examples of the green pigment include chrome green, chromium oxide, pigment green B, and malachite green lake.

  Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.

  Moreover, these colorants can use 1 type (s) or 2 or more types.

  The toner such as the color toner of the present invention may contain a charge control agent in the toner as necessary. For example, the color toner of the present invention can contain a charge control agent in the toner as needed. For example, nigrosine, an azine dye containing an alkyl group having 2 to 16 carbon atoms (Japanese Patent Publication No. 42-1627), a basic dye (for example, CI Basic Yellow 2 (CI 41000), CI Basic Yellow 3, C.I.Basic Red 1 (C.I. 45160), C.I.Basic Red 9 (C.I. 42500), C.I.Basic Violet 1 (C.I. 42535), C I. Basic Violet 3 (C.I. 42555), C. I. Basic Violet 10 (C.I. 45170), C.I.Basic Violet 14 (C.I. 42510), C.I.Basic Blueet 1 (C.I. 42025), C.I.Basic Blue 3 (C.I.51005), C.I. ascii blue 5 (C.I. 42140), C.I.Basic Blue 7 (C.I.42595), C.I.Basic Blue 9 (C.I.522015), C.I.Basic Blue 24 (C. CI Basic Blue 25 (C.I.52025), C.I.Basic Blue 26 (C.I.44045), C.I.Basic Green 1 (C.I.42040), Lake pigments of these basic dyes, such as CI Basic Green 4 (CI 42000), CI Solvent Black 8 (CI 26150), benzoylmethyl hexadecyl ammonium chloride, decyltrimethyl chloride Quaternary ammonium salts such as dibutyl or dioctyl Dialkyl tin compounds, dialkyl tin borate compounds, guanidine derivatives, vinyl polymers containing amino groups, polyamine resins such as condensation polymers containing amino groups, Japanese Patent Publication No. 41-20153, Japanese Patent Publication No. 43-27596 A metal complex salt of a monoazo dye described in JP-B-44-6397 and JP-B-45-26478, salicylic acid described in JP-B-55-42752, JP-B-59-7385, Examples include dialkyl salicylic acid, naphthoic acid, dicarboxylic acid metal complexes such as Zn, Al, Co, Cr, and Fe, sulfonated copper phthalocyanine pigments, organic boron salts, fluorine-containing quaternary ammonium salts, calixarene compounds, and the like. . Naturally, color toners other than black should avoid the use of charge control agents that impair the target color, and white metal salts of salicylic acid derivatives are preferably used.

  As for the external additive, transferability and durability are further improved by externally adding inorganic fine particles such as silica, titanium oxide, alumina, silicon carbide, silicon nitride, boron nitride and resin fine particles to the base toner particles. This effect can be obtained by covering the wax that lowers transferability and durability with these external additives and reducing the contact area due to the toner surface being covered with fine particles. The surface of these inorganic fine particles is preferably subjected to a hydrophobic treatment, and metal oxide fine particles such as silica and titanium oxide subjected to the hydrophobic treatment are preferably used. As the resin fine particles, polymethyl methacrylate or polystyrene fine particles having an average particle diameter of about 0.05 to 1 μm obtained by a soap-free emulsion polymerization method are suitably used. In addition, the combination of hydrophobized silica and hydrophobized titanium oxide increases the amount of hydrophobized titanium oxide externally added compared to the amount of hydrophobized silica externally charged. The toner can also be excellent in stability. In combination with the above inorganic fine particles, external additives conventionally used such as silica having a specific surface area of 20 to 50 m / g and resin fine particles having an average particle diameter of 1/100 to 1/8 of the average particle diameter of the toner. The durability can be improved by externally adding an external additive having a particle size larger than that of the agent to the toner. This is because the metal oxide particles externally added to the toner tend to be embedded in the base toner particles in the process where the toner is mixed and stirred with the carrier in the developing device, charged, and used for development. This is because it is possible to prevent the metal oxide fine particles from being embedded by externally adding an external additive having a particle size larger than that of the oxide fine particles to the toner. The above-mentioned inorganic fine particles and resin fine particles are contained (internally added) in the toner, but the effect is reduced as compared with the case of external addition, but the effect of improving transferability and durability can be obtained and the pulverization property of the toner can be improved. Can do. In addition, since external addition and internal addition can be used together to suppress embedding of externally added fine particles, excellent transferability can be stably obtained and durability can be improved.

  In addition, the following are mentioned as a typical example of the hydrophobization processing agent used here. Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, p-chlorophenyltrichlorosilane, 3-chloropropyltrichlorosilane, 3-chloropropyltrimethoxysilane, vinyltriethoxysilane, vinylmethoxysilane, vinyl-tris (β-methoxyethoxy) ) Silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, divinyldichlorosilane, dimethylvinylchlorosilane, octyl Trichlorosilane, decyl-trichlorosilane, nonyl-trichlorosilane, (4-t-propylphenyl) -trichlorosilane, (4-t-butylphenyl) -trichlorosilane, diventyl-dichlorosilane, dihexyl-dichlorosilane, dioctyl-dichlorosilane, dinonyl -Dichlorosilane, didecyl-dichlorosilane, didodecyl-dichlorosilane, dihexadecyl-dichlorosilane, (4-t-butylphenyl) -octyl-dichlorosilane, dioctyl-dichlorosilane, didecenyl-dichlorosilane, dinonenyl-dichlorosilane, di-2-ethylhexyl-dichlorosilane, di- 3,3-dimethylbenthyl-dichlorosilane, trihexyl-chlorosilane, trioctyl-chlorosilane, tridecyl-chlorosilane Dioctyl-methyl-chlorosilane, octyl-dimethyl-chlorosilane, (4-t-propylphenyl) -diethyl-chlorosilane, octyltrimethoxysilane, hexamethyldisilazane, hexaethyldisilazane, diethyltetramethyldisilazane, hexaphenyldisilazane , Hexatolyl disilazane and the like. In addition, titanate coupling agents and aluminum coupling agents can also be used. In addition, as an external additive for the purpose of improving cleaning properties, a lubricant such as a fatty acid metal salt or a fine particle of polyvinylidene fluoride can be used in combination.

  As the carrier core material in the present invention, those known as two-component carriers for electrophotography, such as ferrite, Cu-Zn ferrite, Mn ferrite, Mn-Mg ferrite, Mn-Mg-Sr ferrite, magnetite, iron, What is necessary is just to select suitably according to the use of a carrier, such as nickel, and a use purpose, and it is not restricted to an example.

  Conventionally known methods such as a pulverization method and a polymerization method can be applied to the toner production method of the present invention. For example, in the case of the pulverization method, as a device for kneading the toner, a batch type two roll, a Banbury mixer or a continuous twin screw extruder, for example, KTK type twin screw extruder manufactured by Kobe Steel, TEM manufactured by Toshiba Machine Co., Ltd. Type twin screw extruder, KCK twin screw extruder, Ikegai Iron Works PCM type twin screw extruder, Kurimoto Iron Works KEX type twin screw extruder, continuous single screw kneader, for example Buss Co-kneader is preferably used. The melt-kneaded product obtained as described above is cooled and then pulverized. For pulverization, for example, coarsely pulverized using a hammer mill, a funnel plex or the like, and further, a fine pulverizer using a jet stream or mechanical pulverization A machine can be used. The pulverization is desirably performed so that the average particle diameter is 3 to 15 μm. Further, the pulverized product is preferably adjusted in particle size to 5 to 20 μm by a wind classifier or the like. Subsequently, the external additive is externally added to the base toner. The base toner and the external additive are mixed and stirred using a mixer, and the external additive is crushed and coated on the toner surface. At this time, it is important in terms of durability that external additives such as inorganic fine particles and resin fine particles are uniformly and firmly attached to the base toner. The above is only an example, and the present invention is not limited to this.

[Image forming apparatus, process cartridge]
FIG. 1 shows a schematic configuration of an image forming apparatus having a process cartridge having a developer of the present invention. In FIG. 2, the figure shows the entire process cartridge, which includes a photoconductor, a charging unit, a developing unit, and a cleaning unit.

  In the present invention, among the constituent elements such as the above-described photoreceptor, charging means, developing means, and cleaning means, the developing means using the developer of the present invention and one or more other means are used as a process cartridge. The process cartridge is configured so as to be integrally connected, and is configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

  In an image forming apparatus equipped with a process cartridge having developing means using the developer of the present invention, the photosensitive member is rotationally driven at a predetermined peripheral speed. In the rotation process, the photosensitive member receives a uniform positive or negative electric potential on its peripheral surface by the charging means, and then receives image exposure light from an image exposure means such as slit exposure or laser beam scanning exposure. An electrostatic latent image is sequentially formed on the peripheral surface of the body, and the formed electrostatic latent image is then developed with toner by a developing unit, and the developed toner image is transferred between the photosensitive member and the transfer unit from the paper feeding unit. Then, the image is sequentially transferred to the transfer material fed in synchronization with the rotation of the photosensitive member by the transfer means. The transfer material that has received the image transfer is separated from the surface of the photosensitive member, introduced into the image fixing means, and fixed, and printed out as a copy (copy). The surface of the photoreceptor after the image transfer is cleaned by removing the transfer residual toner by the cleaning means, and after being further neutralized, it is repeatedly used for image formation.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to this.

  EXAMPLES Next, although an Example and a comparative example are given and this invention is demonstrated further more concretely, this invention is not limited to these. Parts are based on weight.

Example 1
[Carrier coating layer]
・ Silicon resin solution [solid content: 23% by weight
(SR2410: manufactured by Toray Dow Corning Silicone Co.)] 432.2 parts by weight aminosilane [100% by weight of solid content
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 0.66 parts by weight, inorganic oxide fine particles A, aluminum oxide, particle size: 0.40 μm, true specific gravity: 3.9 [particle powder specific resistance: 12 Ω · cm] 145 Part by weight / ionic liquid IL-A2 (manufactured by Guangei Chemical Industry Co., Ltd.) 20 parts by weight [ion conductivity: 6.1 × 10 ⁻⁵ (S / cm)]
-300 parts by weight of toluene was dispersed with a homomixer for 10 minutes to obtain a silicon resin coating film forming solution. Spiral coater (Okada Seiko Co., Ltd.) having an average particle size of 5000 parts by weight as the core material and 35 parts by weight of 35 μm sintered ferrite powder (true specific gravity 5.5), so that the coating film forming solution has a film thickness of 0.35 μm on the surface of the core material. Applied to the coater at a temperature of 40 ° C. and dried. The obtained carrier was fired in an electric furnace at 200 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an aperture of 63 μm, D / h: 1.1, volume resistivity: 13.9 [Log (Ω · cm)], magnetization: 68 Am ² / kg [ Carrier 1] was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 93% with respect to the core material.

  In addition, the particle powder specific resistance of inorganic oxide fine particles was measured using the apparatus of FIG.

[Career]
For the measurement of the average particle diameter of the core material, an SRA type of Microtrac particle size analyzer (Nikkiso Co., Ltd.) was used, and the measurement was performed with a range setting of 0.7 μm or more and 125 μm or less.

  The measurement of the binder resin film thickness was performed by observing the cross section of the carrier with a transmission electron microscope so that the coating film covering the carrier surface could be observed.

  Magnetization measurement was performed by the following method using VSM-P7-15 manufactured by Toei Industry Co., Ltd. About 0.15 g of the sample was weighed, the sample was filled in a cell having an inner diameter of 2.4 mmφ and a height of 8.5 mm, and measured under a magnetic field of 1000 oerste (Oe).

[Toner 1]
(Synthesis of Toner Binder) 724 parts of bisphenol A ethylene oxide 2-mole adduct, 276 parts of isophthalic acid and 2 parts of dibutyltin oxide were placed in a reaction vessel equipped with a cooling pipe, a stirrer and a nitrogen introduction pipe. The mixture was reacted for 8 hours at 0 ° C. and further reacted for 5 hours at a reduced pressure of 10 to 15 mmHg, then cooled to 160 ° C., 32 parts of phthalic anhydride was added thereto and reacted for 2 hours. Subsequently, it cooled to 80 degreeC and reacted with 188 parts of isophorone diisocyanate in ethyl acetate for 2 hours, and the isocyanate containing prepolymer (1) was obtained. Next, 267 parts of the prepolymer (1) and 14 parts of isophoronediamine were reacted at 50 ° C. for 2 hours to obtain a urea-modified polyester (1) having a weight average molecular weight of 64,000. In the same manner as above, 724 parts of bisphenol A ethylene oxide 2-mole 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 to 15 mmHg to give a peak molecular weight of 5000. An unfinished polyester (a) was obtained. 200 parts of urea-modified polyester (1) and 800 parts of unmodified polyester (a) are dissolved and mixed in 2000 parts of a mixed solvent of ethyl acetate / MEK (1/1), and an ethyl acetate / MEK solution of toner binder (1) is mixed. Got. Part of the mixture was dried under reduced pressure to isolate toner binder (1). Tg was 62 ° C.

  (Preparation of toner) In a beaker, 240 parts of the ethyl acetate / MEK solution of the toner binder (1), 20 parts of pentaerythritol tetrabehenate (melting point: 81 ° C., melt viscosity: 25 cps), C.I. I. 4 parts of raw pigment of Pigment Yellow 154 was added and stirred at 12000 rpm with a TK homomixer at 60 ° C. to uniformly dissolve and disperse. In a 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 12000 rpm with a TK homomixer. Subsequently, this mixed liquid was transferred to a Kolben equipped with a stirring bar and a thermometer, and the temperature was raised to 98 ° C. to remove the solvent. After the dispersion slurry was filtered under reduced pressure, a filter cake was obtained.

(Washing / drying / fluorine treatment)
1: 100 parts of ion-exchanged water was added to the filter cake, mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered.
2: 1OO parts of 10% sodium hydroxide aqueous solution was added to the filter cake of 1 above, mixed with a TK homomixer (30 minutes at 12,000 rpm), and then filtered under reduced pressure.
3: 100 parts of 10% hydrochloric acid was added to the filter cake of 2 above, mixed with a TK homomixer (10 minutes at 12,000 rpm), and then filtered.
4: 300 parts of ion-exchanged water was added to the filter cake of 3 above, mixed with a TK homomixer (rotation speed: 12,000 rpm for 10 minutes), and then filtered twice to obtain a cake. This is designated as [Filter cake 1].

  The above [Filter cake 1] was dried at 45 ° C. for 48 hours in a circulating dryer.

  Thereafter, 15 parts of [Filter cake 1] is added to 90 parts of water, and 0.0005 part of the fluorine compound is dispersed therein, thereby attaching the fluorine compound (2) to the toner particle surface, and then circulating air. It dried for 48 hours at 45 degreeC with the dryer. Thereafter, the mixture was sieved with a 75 μm mesh to obtain toner base particles. This is designated as [toner base particle 1]. To 100 parts of [Toner Base Particle 1] obtained above, 1.5 parts of hydrophobic silica and 0.7 parts of hydrophobized titanium oxide as external additives were added at 2000 rpm × 30 seconds, 5 cycles using a Henschel mixer. Was mixed to obtain a toner. This is referred to as [Toner 1].

  7 parts of [Toner 1] and 93 parts of [Carrier 1] thus obtained were mixed and stirred to obtain a developer having a toner concentration of 7% by weight. Color stain, carrier adhesion, image density, durability (charge reduction amount, resistance change) Amount). The results are shown in Table 2.

  The evaluation methods and conditions in the examples are shown below.

[Color stains]
Evaluation of the ΔE value of the yellow monochrome image after running up to 30,000 image charts of 0.5% image area using a commercially available digital full color printer (image Neo Neo C455 manufactured by Ricoh Co., Ltd.) was performed. A yellow single color image after initial and after 30000 sheets is output, and a ΔE value is obtained according to the following equation. When ΔE is 2 or less, there is no color stain (◯), when ΔE is 2 to 4, color stain is not noticeable (Δ), no change in color tone is indicated, and when ΔE is 4 or more, color stain is clearly noticeable (×) be pointed out.

  After image output, the image density was measured with X-RITE 938 (manufactured by x-rite). Three points of CIE L *, CIE a *, and CIE b * at a point where the yellow image density is 1.4 ± 0.5 are measured, an average value is obtained, and is substituted into the following equation to calculate a ΔE value.

ΔE = √ ((initial L *) ² + (initial a *) ² + (initial b *) ² ) −√ ((post-run L *) ² + (post-run a *) ² + (post-run b *) ² )
[Carrier adhesion]
The developer is set on a commercially available digital full-color printer (Imagio Neo C455 manufactured by Ricoh), and the surface of the photosensitive member is developed with a charged potential of DC740V and a developing bias of 600V (fixed to a ground potential of 140V), and the dot formation halftone is developed. The number of carriers adhering to the substrate was counted by five visual field observations with a magnifier, and the average number of adhering carriers per 100 cm ² was taken as the edge carrier adhering amount. The evaluation was as follows: ◎: 20 or less, ○: 21 or more and 60 or less, Δ: 61 or more and 80 or less, ×: 81 or more, ◎ ○ △ was passed and × was rejected.

  Further, white spots (image part) were set to a charging potential of DC 740 V and a developing bias of 600 V (the background potential was fixed to 140 V), a full-color image (A3 size) was output, and the number of white spots on the image was counted. The evaluation was as follows: ◎: 5 or less, ◯: 6 or more and 10 or less, △: 11 or more and 20 or less, ×: 21 or more, ◎ ○ △ was accepted and x was rejected.

[Image density]
After running 300,000 image charts with 50% image area in monochrome mode, the solid image is output to 6000 paper manufactured by Ricoh, and the image density is measured by X-Rite (manufactured by X-Rite). It was. In Table 2, when the measured value is 1.8 or more and less than 2.2, it is ◎, when it is 1.4 or more and less than 1.8, it is ◯, when it is 1.2 or more and less than 1.4, it is △, And when less than 1.2, it displayed by x.

[durability]
The developer was set in a commercially available digital full-color printer (image Neo Neo C455 manufactured by Ricoh Co., Ltd.), and a running evaluation of 300,000 sheets was performed with an image chart of 50% image area in a single color mode. The judgment was made based on the amount of charge reduction of the carrier after the running. The amount of decrease in resistance was evaluated by running 300,000 sheets in an image chart of 0.5% image area in the single color mode. And it judged with the amount of resistance fall of the career which finished this running.

  The amount of charge reduction here is a room temperature and humidity room (temperature: 23.5 ° C., humidity: 60% RH) for 30 minutes or more, and humidity is adjusted in an unsealing system, and 6.000 g of initial carrier and 0.452 g of toner are added. After being added to a stainless steel container, it was sealed, and a sample which was friction-charged with an amplitude of about 1100 times with a YS-LD (a shaker manufactured by Yayoi Co., Ltd.) for 5 minutes on a scale 150 The carrier obtained by removing the toner in the developer after running from the charge amount (Q1) measured by a simple blow-off method [manufactured by Toshiba Chemical Co., Ltd .: TB-200] It means the amount obtained by subtracting the charge amount (Q2) measured by the same method, and the target value is within 10.0 (μc / g).

  Here, the amount of resistance change refers to the carrier from which the toner in the developer after running can be removed by the blow-off device from the resistance value (R1) obtained by the resistance measurement method described above for the initial carrier. It means an amount obtained by subtracting the value (R2) measured by the same method as the resistance measuring method, and the target value is 3.0 [Log (Ω · cm)] in absolute value. Further, the cause of the resistance change is scraping of the binder resin film of the carrier, spent toner component, particle detachment in the carrier coating film, etc., and reducing these can suppress the resistance change amount. .

(Example 2)
D / h: 0.9, volume resistivity: 14.1 [Log (Ω (Ω), in the same manner as in Example 1 except that the coating layer formulation was changed to a mixed system of acrylic resin and silicon resin described below. Cm)], magnetization: 68 Am ² / kg [Carrier 2] was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 83% with respect to the core material.

・ Acrylic resin solution (solid content 50% by weight) 34.2 parts by weight ・ Guanamine solution (solid content 70% by weight) 9.7 parts by weight ・ Acid catalyst (solid content 40% by weight) 0.19 parts by weight ・ Silicone resin solution [Solid content 20% by weight
(SR2410: manufactured by Toray Dow Corning Silicone Co.)] 432.2 parts by weight Aminosilane [100% by weight of solid content
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 3.42 parts by weight • Ionic liquid IL-A2 (manufactured by Guangei Chemical Industry Co., Ltd.) 20 parts by weight [Ionic conductivity: 6.1 × 10 ⁻⁵ (S / Cm)]
Inorganic oxide fine particles B Aluminum oxide Particle size: 0.37 μm, true specific gravity 3.9
[Particle powder specific resistance: 13 Ω · cm] 97 parts by weight The thus obtained [Carrier 2] and [Toner 1] were developed into a developer by the same method as in Example 1 and evaluated. The results are shown in Table 2.

(Example 3)
[Carrier 3] having a volume resistivity: 15.8 [Log (Ω · cm)] and magnetization: 68 Am ² / kg, except that the inorganic oxide fine particles A were not added in Example 1. Got. [Carrier 3] and [Toner 1] thus obtained were developed into a developer by the same method as in Example 1 and evaluated. The results are shown in Table 2.

Example 4
D / h: 1.9, volume resistivity: 13.1 [Log (Ω (Ω), except that the coating layer formulation described below was changed in the formulation ratio of acrylic resin and silicon resin. Cm)], magnetization: 68 Am ² / kg [Carrier 4] was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 83% with respect to the core material.

・ Acrylic resin solution (solid content 50 wt%) 17.1 parts by weight ・ Guanamine solution (solid content 70 wt%) 4.85 parts by weight ・ Acid catalyst (solid content 40 wt%) 0.10 parts by weight ・ Silicone resin solution [Solid content 20% by weight
(SR2410: manufactured by Toray Dow Corning Silicone Co.)] 216.2 parts by weight Aminosilane [100% by weight of solid content
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 1.68 parts by weight • Ionic liquid IL-A2 (manufactured by Guangei Chemical Industry Co., Ltd.) 20 parts by weight [Ionic conductivity: 6.1 × 10 ⁻⁵ (S / Cm)]
Inorganic oxide fine particles B Aluminum oxide Particle size: 0.37 μm, true specific gravity 3.9
[Particle powder specific resistance: 13 Ω · cm] 97 parts by weight Toluene 1600 parts by weight The thus obtained [Carrier 4] and [Toner 1] were converted into a developer by the same method as in Example 1 and evaluated. The results are shown in Table 2.

(Example 5)
D / h: 0.4, volume resistivity: 16.5 [Log (Ω (Ω), except that the coating layer formulation described below was changed in the formulation ratio of acrylic resin and silicon resin. Cm)] and magnetization: 68 Am ² / kg [Carrier 5]. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 83% with respect to the core material.

・ Acrylic resin solution (solid content 50 wt%) 158.8 parts by weight ・ Guanamine solution (solid content 70 wt%) 49.6 parts by weight ・ Acid catalyst (solid content 40 wt%) 0.88 parts by weight ・ Silicone resin solution [Solid content 20% by weight
(SR2410: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 743.2 parts by weight Aminosilane [100 wt% solid content
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 1.68 parts by weight • Ionic liquid IL-A2 (manufactured by Guangei Chemical Industry Co., Ltd.) 20 parts by weight [Ionic conductivity: 6.1 × 10 ⁻⁵ (S / Cm)]
Inorganic oxide fine particles B Aluminum oxide Particle size: 0.37 μm, true specific gravity 3.9
[Particle powder specific resistance: 13 Ω · cm] 97 parts by weight Toluene 1600 parts by weight The thus obtained [Carrier 5] and [Toner 1] were evaluated as developers by the same method as in Example 1. The results are shown in Table 2.

(Example 6)
[Conductive fine particles]
200 g of aluminum oxide (average primary particle size 0.37 μm, true specific gravity 3.9) was dispersed in 2.5 liters of water to obtain a water suspension. This suspension was kept warm at 80 ° C. A separately prepared solution of 22 g of stannic chloride (SnCl ₄ .5H ₂ O) in 200 ml of 2N hydrochloric acid and 12 wt% aqueous ammonia were added so as to maintain the pH of the suspension at 7-8. . Subsequently, a solution prepared by dissolving 65 g of indium chloride (InCl ₃ ) and 8 g of stannic chloride (SnCl ₄ .5H ₂ O) separately prepared in 800 ml of 2N hydrochloric acid and 12 wt% aqueous ammonia was adjusted to a pH of 7 to 7. It was dripped so that it might hold at 8. After completion of the dropwise addition, the treated suspension was filtered and washed, and the resulting treated pigment cake was dried at 120 ° C.

  Next, the obtained dry powder was heat-treated at 500 ° C. for 1.5 hours in a nitrogen gas stream (1 liter / min). The obtained fired product is pulverized, and this pulverized product is added and treated with 3.5 wt% γ-aminopropyltriethoxysilane while stirring with a Henschel mixer heated to 70 ° C. Furthermore, the processed product was heat-treated at 100 ° C. for 1 hour to obtain the target white conductive powder A.

  In Example 2, the conductive particles A [particle powder specific resistance: 8 Ω · cm, particle size: 0.40 μm, true specific gravity: 3.9] were used instead of the inorganic fine powder, [Carrier 6] with D / h: 1.0 and volume resistivity: 9.5 [Log (Ω · cm)] was obtained.

  [Carrier 6] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2. The conductive fine particles contained in the resin coating layer at this time had a coverage of 83% with respect to the core material.

(Example 7)
In Example 2, except that 110 parts by weight of titanium oxide (anatase) C [particle powder specific resistance: 32 Ω · cm, particle size: 0.35 μm, true specific gravity 5.0] was used instead of the inorganic fine powder. Similarly, [Carrier 7] having D / h: 0.9 and volume resistivity: 16.5 [Log (Ω · cm)] was obtained. The fine particles contained in the resin coating layer at this time had a coverage of 73% with respect to the core material.

  [Toner 1] and [Carrier 7] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2.

(Example 8)
D / h: 0.9, volume resistivity: 15. In the same manner as in Example 1 except that the carrier has a weight average particle diameter of 18 μm (true specific gravity 5.7) and the coating layer formulation is as described below. 7 [Log (Ω · cm)] and magnetization: 66 Am ² / kg [Carrier 8] were obtained.

・ Acrylic resin solution (solid content 50 wt%) 68.4 parts by weight ・ Guanamine solution (solid content 70 wt%) 19.4 parts by weight ・ Acid catalyst (solid content 40 wt%) 0.38 parts by weight ・ Silicone resin solution [Solid content 20% by weight
(SR2410: manufactured by Toray Dow Corning Silicone Co.)] 864.4 parts by weight Aminosilane [solid content: 100% by weight
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 0.46 parts by weight • Ionic liquid IL-A2 (manufactured by Guangei Chemical Industry Co., Ltd.) 20 parts by weight [Ionic conductivity: 6.1 × 10 ⁻⁵ (S / Cm)]
Inorganic oxide fine particles B Aluminum oxide Particle size: 0.37 μm, true specific gravity 3.9
[Particle powder specific resistance: 13 Ω · cm] 195 parts by weight Toluene 800 parts by weight The thus obtained [Carrier 8] and [Toner 1] were converted into a developer by the same method as in Example 1 and evaluated. The results are shown in Table 2. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 71% with respect to the core material.

Example 9
D / h: 0.6, volume resistivity: 14.5 [except for the carrier having a weight average particle diameter of 71 μm (true specific gravity 5.3) and coating layer formulation as described below. Log (Ω · cm)] and magnetization: 69 Am ² / kg [Carrier 9].

・ Acrylic resin solution (solid content 50% by weight) 34.2 parts by weight ・ Guanamine solution (solid content 70% by weight) 9.7 parts by weight ・ Acid catalyst (solid content 40% by weight) 0.19 parts by weight ・ Silicone resin solution [Solid content 20% by weight
(SR2410: manufactured by Toray Dow Corning Silicone)] 292.9 parts by weight Aminosilane [solid content 100% by weight
(SH6020: manufactured by Toray Dow Corning Silicone Co., Ltd.)] 0.42 parts by weight ・ Ionic liquid IL-A2 (manufactured by Guangei Chemical Co., Ltd.) 20 parts by weight [Ionic conductivity: 6.1 × 10 ⁻⁵ (S / Cm)]
Inorganic oxide fine particles B Aluminum oxide Particle size: 0.37 μm, true specific gravity 3.9
[Particle powder specific resistance: 13 Ω · cm] 60 parts by weight Toluene 800 parts by weight The thus obtained [Carrier 9] and [Toner 1] were converted into a developer by the same method as in Example 1 and evaluated. The results are shown in Table 2. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 78% with respect to the core material.

(Example 10)
In Example 2, D / h: 0.9, volume resistivity: similarly, except that 35 μm sintered ferrite (true specific gravity 5.4) having a low magnetization was used and the magnetization was changed to 35 Am ² / kg. [Carrier 10] of 13.9 [Log (Ω · cm)] was obtained. [Carrier 10] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 1. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 83% with respect to the core material.

(Implementation 11)
In Example 2, D / h: 0.9, volume resistivity: similarly, except that 35 μm sintered ferrite (true specific gravity 5.5) having high magnetization was used and the magnetization was changed to 93 Am ² / kg. 14.1 [Log (Ω · cm)] [Carrier 11] was obtained. [Carry 11] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 83% with respect to the core material.

(Example 12)
In Example 1, D / h: 1.1, volume resistivity: 13.5 [Log (Ω · cm)] except that the amount of inorganic fine particles added was reduced from 145 parts by weight to 75 parts by weight. [Carrier 12] having a magnetization of 69 Am ² / kg was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 46% with respect to the core material. [Carrier 12] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2.

(Example 13)
In Example 1, the ionic liquid was changed from IL-A2 [ion conductivity: 6.1 × 10 ⁻⁵ (S / cm)] to IL-P14 [ion conductivity: 1.8 × 10 ⁻³ (S / cm). )] (Manufactured by Guangei Chemical Co., Ltd.) and D / h: 1.1, volume resistivity: 13.8 [Log (Ω · cm)] except that the amount was increased to 30 parts by weight. [Carrier 13] having a magnetization of 68 Am ² / kg was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 93% with respect to the core material. [Carrier 13] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2.

(Example 14)
In Example 1, the ionic liquid was changed from IL-A2 [ion conductivity: 6.1 × 10 ⁻⁵ (S / cm)] to IL-IM1 [ion conductivity: 1.5 × 10 ⁻² (S / cm). )] (Manufactured by Guangei Chemical Industry Co., Ltd.), D / h: 1.1, volume resistivity: 16.3 [Log (Ω · cm)] except that the amount was increased to 30 parts by weight. [Carrier 14] having a magnetization of 68 Am ² / kg was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 93% with respect to the core material. [Carrier 14] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2.

(Comparative Example 1)
[Carrier coating layer]
・ Silicon resin solution [solid content: 23% by weight
(SR2410: manufactured by Toray Dow Corning Silicone Co.)] 432.2 parts by weight Aminosilane [100% by weight of solid content
(SH6020: manufactured by Toray Dow Corning Silicone Co.)] 0.66 parts by weight Inorganic oxide fine particles A Aluminum oxide Particle size: 0.40 μm, true specific gravity: 3.9
[Particle powder specific resistance: 12 Ω · cm] 145 parts by weight Carbon black MA100R (Mitsubishi Chemical Industry Co., Ltd.) 20 parts by weight Toluene 300 parts by weight is dispersed with a homomixer for 10 minutes to form a silicone resin coating film forming solution Got. Spiral coater (Okada Seiko Co., Ltd.) having an average particle size of 5000 parts by weight as the core material and 35 parts by weight of 35 μm sintered ferrite powder (true specific gravity 5.5), so that the coating film forming solution has a film thickness of 0.35 μm on the surface of the core material. Applied to the coater at a temperature of 40 ° C. and dried. The obtained carrier was fired in an electric furnace at 200 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an aperture of 63 μm, D / h: 1.1, volume resistivity: 12.9 [Log (Ω · cm)], magnetization: 68 Am ² / kg [ Carrier 14] was obtained. The inorganic oxide particles contained in the resin coating layer at this time had a coverage of 93% with respect to the core material. [Carrier 14] and [Toner 1] thus obtained were converted into developers by the same method as in Example 1 and evaluated. The results are shown in Table 2.

キャリアの特性値

Carrier characteristic values

評価結果
表２より、本発明の範囲内である実施例１乃至１２については、色汚れのない良好なキャリアが得られた。また、画像濃度、キャリア付着、帯電低下量、抵抗低下量の全ての評価項目においても良好な結果が得られた。

Evaluation results From Table 2, for Examples 1 to 12, which are within the scope of the present invention, good carriers without color stains were obtained. In addition, good results were obtained for all evaluation items of image density, carrier adhesion, charge reduction amount, and resistance reduction amount.

  On the other hand, in Comparative Example 1, color stains occurred, and the results were not usable practically.

  As described above, by the image forming method shown in the embodiment, an extremely stable and good-quality image can be obtained over a long period of time.

  Although the embodiments of the present invention have been specifically described above, the present invention is not limited to these embodiments, and these embodiments of the present invention depart from the spirit and scope of the present invention. And can be changed or modified.

FIG. 3 is a diagram illustrating an example of an image forming apparatus having a process cartridge using the developer of the present invention. It is a figure which shows the process cartridge using the developing agent of this invention. It is the schematic of a carrier resistance measuring apparatus. It is the schematic of a powder specific resistance measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Developing device 3-3 Staying developer 3a Toner 3b Magnetic carrier 4 Developing sleeve 5 Magnet roller 6 Doctor blade 7 Developer storage case 7a Predoctor 8 Toner hopper 8a Toner replenishing port 50 Charging roller 58 Cleaning device 80 Magnetic field Forming means D Development area S Developer container

Claims (14)

  A carrier for an electrophotographic developer having at least a coating layer on a carrier core material, wherein the coating layer contains an ionic liquid. 2. The carrier for an electrophotographic developer according to claim 1, wherein the ionic liquid contained in the coating layer has an ionic conductivity of 1.0 × 10 ⁻³ (S / cm) or more.   The carrier for an electrophotographic developer according to claim 1, further comprising inorganic fine particles in the coating layer.   The inorganic fine particles contain 70% or more of the coating ratio with respect to the core material, and the particle diameter (D) of the particles and the coating layer thickness (h) are 0.5 <[D / h]. The carrier for an electrophotographic developer according to any one of claims 1 to 3, wherein <1.5.   5. The electrophotography according to claim 1, wherein the carrier has a volume resistivity of 10 [Log (Ω · cm)] to 16 [Log (Ω · cm)]. Developer carrier.   6. The carrier for an electrophotographic developer according to claim 1, wherein the carrier has a volume average particle diameter of 20 μm to 65 μm.   The carrier for an electrophotographic developer according to any one of claims 1 to 6, wherein at least the binder resin is a silicon resin.   The carrier for an electrophotographic developer according to any one of claims 1 to 7, wherein at least the binder resin is an acrylic resin and a silicon resin. The magnetic moment at 1000 (10 ³ / 4π · A / m) is 40 (Am ² / kg) or more and 90 (Am ² / kg) or less, according to any one of claims 1 to 8, The carrier for an electrophotographic developer according to the description.   An electrophotographic developer comprising: a toner comprising at least a binder resin and a pigment; and the electrophotographic carrier according to any one of claims 1 to 9.   The electrophotographic developer according to claim 10, wherein the toner is a color toner.   Forming an electrostatic latent image on the image bearing member; developing the electrostatic latent image with a developer comprising at least a carrier and a toner to form a visible image; and transferring the obtained visible image to a recording member An image forming method having a fixing step, wherein the developer uses the electrophotographic developer according to claim 10 or 11.   In a process cartridge that integrally supports at least one developing unit selected from a photosensitive member, a charging unit, a developing unit, and a cleaning unit and is detachable from the image forming apparatus main body, the developing unit holds a developer, The process cartridge according to claim 10 or 11, wherein the developer is the developer according to claim 10 or 11.   At least a photoconductor, a developing unit that forms an image on the photoconductor, a transfer unit that transfers an image on the photoconductor to a transfer material, and a fixing unit that fixes the image on the transfer material. An image forming apparatus comprising the process cartridge according to claim 13.

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