JP5304042B2 - Developer for developing electrostatic image and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer for electrostatic charge image development, which can maintain transferability, hardly causes color spots due to decrease in density and defective charging even when a toner of a particular color is not used for a long period of time in a color output system and the like, and can produce a clear image with almost no deterioration of the image quality for a long period of time even in a high-temperature and high-humidity environment. <P>SOLUTION: The developer for electrostatic charge image development comprises: a toner that contains at least one external additive the volume average particle diameter of which is 105-300 nm; and a carrier that has a core particle and a resin coating layer for coating the surface of the core particle, wherein the BET specific surface area A of the core particle is in the range of 0.13-0.25 m<SP>2</SP>/g, and the difference (B-A) between the BET specific surface area B of the coated particle and the BET specific surface area A of the core particle is in the range of 0.03-0.40 m<SP>2</SP>/g. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a developer for developing an electrostatic image and an image forming apparatus.

  A method for visualizing image information through an electrostatic latent image (electrostatic image) such as electrophotography is currently used in various fields. In electrophotography, an electrostatic latent image formed on a photoreceptor by charging and exposure processes contains an electrostatic charge image developing toner (hereinafter sometimes referred to simply as “toner”). It is developed with an agent (hereinafter sometimes simply referred to as “developer”), and visualized through a transfer and fixing process. As a developer used for development, a two-component developer including a toner and a carrier for developing an electrostatic image (hereinafter sometimes simply referred to as “carrier”) and a toner used alone such as a magnetic toner are used. There are component developers, but the two-component developer has characteristics such as good controllability because the carrier shares functions such as stirring, transport and charging of the developer and is separated as a developer. Is currently widely used.

  Carriers are generally classified into resin-coated carriers having a resin coating layer on the surface of magnetic particles (core particles) and uncoated carriers having no coating layer on the surface. Developers using resin-coated carriers are generally charged. It has excellent controllability and is relatively easy to improve environmental dependency and stability over time. As a developing method, the cascade method has been used in the past, but at present, the magnetic brush method using a magnetic roll as a developer conveying unit is the mainstream.

  In recent years, from the viewpoint of energy saving and downsizing, there has been a demand for a system that improves toner transferability and does not use a photoreceptor cleaner. As one method for improving the transferability of toner, it is known to use an external additive having a large particle size (see, for example, Patent Document 1).

JP-A-2005-202132 JP 2006-259179 A

  The present invention can maintain transferability even when a specific color toner, such as a color output system, is not used for a long period of time. A developer for developing an electrostatic charge image and an image forming apparatus capable of obtaining a clear image with little deterioration in image quality over a long period of time even under humidity.

The present invention comprises a toner containing at least one external additive having a volume average particle size of 105 nm or more and 300 nm or less, a core particle and a resin coating layer covering the surface of the core particle, and a BET ratio of the core particle surface area a is in the range of less 0.13 m ² / g or more 0.25 m ² / g, the difference between the BET specific surface area a of the coated BET specific surface area B and the core particles of the coated particles (B-a) is a carrier in the range of less 0.03 m ² / g or more 0.40 m ² / g, a electrostatic image developer comprising a.

  In the developer for developing an electrostatic image, the toner preferably contains a crystalline resin.

  In the developer for developing an electrostatic charge image, the content of the crystalline resin is preferably in the range of 3% by weight to 30% by weight.

  In the developer for developing an electrostatic charge image, the content of the crystalline resin is preferably in the range of 5% by weight to 15% by weight.

  In the developer for developing an electrostatic image, it is preferable that the volume average particle size of the external additive is in a range of 120 nm to 200 nm.

  In the developer for developing an electrostatic charge image, the shape factor of the carrier is preferably in the range of 100 or more and 130 or less.

  The present invention also provides an image carrier, latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and developing the electrostatic latent image using a developer to form a toner image. The image forming apparatus includes a developing unit and a transfer unit that transfers the developed toner image to a transfer target, and the developer is the developer for developing an electrostatic image.

  According to claim 1 of the present invention, the volume average particle diameter of the external additive, the BET specific surface area A of the core particle, and the difference between the BET specific surface area B of the coated particle and the BET specific surface area A of the core particle (B−A) Compared to when the toner is out of this range, the color transfer system can maintain transferability even when a specific color toner, such as a color output system, has not been used for a long period of time. It is possible to provide a developer for developing an electrostatic charge image that is capable of obtaining a clear image that does not occur and is hardly deteriorated over a long period of time even under high temperature and high humidity.

  According to the second aspect of the present invention, compared to the case where the toner does not contain a crystalline resin, the image density at the trailing edge of the high-density patch image (relative to the image traveling direction) is low even under low temperature and low humidity. Developer for developing an electrostatic charge image capable of obtaining a clear image with almost no image defect called a starvation or a starvation in which an image density at the rear end of an intermediate density portion having a high density portion is reduced. Can be provided.

  According to the third aspect of the present invention, compared to the case where the content of the crystalline resin in the toner is outside this range, the rear end of the high-density patch image (relative to the image traveling direction) even under low temperature and low humidity. A static image capable of obtaining a clearer image with almost no image defect called a starvation chipping where the image density becomes low or a starvation where the image density at the rear end of the intermediate density part having a high density part becomes thin. A developer for charge image development can be provided.

  According to the fourth aspect of the present invention, compared to the case where the content of the crystalline resin in the toner is outside this range, the rear end of the high-density patch image (relative to the image traveling direction) can be obtained even under low temperature and low humidity. A static image capable of obtaining a clearer image with almost no image defects called a starvation lacking at the rear end where the image density is low or a starvation where the image density at the rear end of the intermediate density portion having a high density portion is reduced. A developer for charge image development can be provided.

  According to claim 5 of the present invention, even when the toner of a specific color, such as a color output system, is not used for a long time as compared with the case where the volume average particle diameter of the external additive is outside this range, the transfer can be performed. Electrostatic charge image development that can maintain a higher level of color, generate almost no color point due to reduced density and poor charging, and can produce a clearer image with little deterioration of image quality over a long period of time even at high temperatures and high humidity. Developer can be provided.

  According to the sixth aspect of the present invention, compared to the case where the shape factor of the carrier is out of this range, the transferability is further maintained even when a specific color toner such as a color output system is not used for a long time. A developer for developing an electrostatic charge image that can produce a clearer image with almost no color point due to density reduction and poor charging and little deterioration in image quality over a long period of time even under high temperature and high humidity. Can be provided.

  According to claim 7 of the present invention, the volume average particle diameter of the external additive, the BET specific surface area A of the core particle, and the difference between the BET specific surface area B of the coated particle and the BET specific surface area A of the core particle (B−A). Compared to when the toner is out of this range, the color transfer system can maintain transferability even when a specific color toner, such as a color output system, has not been used for a long period of time. It is possible to provide an image forming apparatus capable of obtaining a clear image that does not occur and has almost no deterioration in image quality over a long period of time even under high temperature and high humidity.

  Embodiments of the present invention will be described below. This embodiment is an example for carrying out the present invention, and the present invention is not limited to this embodiment.

<Developer for developing electrostatic image>
The developer for developing an electrostatic charge image according to the exemplary embodiment includes a toner and a carrier, and the carrier is the carrier for developing an electrostatic charge image. That is, the developer for developing an electrostatic charge image according to the exemplary embodiment is a two-component developer including a toner and a carrier.

The developer for developing an electrostatic charge image according to the exemplary embodiment includes a toner containing at least one external additive having a volume average particle size of 105 nm or more and 300 nm or less, a core particle, and a resin coating layer that covers the surface of the core particle. And having a carrier. BET specific surface area A of the core particle of the carrier is in the range of less 0.13 m ² / g or more 0.25 m ² / g, the difference between the BET specific surface area A BET specific surface area B and the core particles of the carrier (coated particles) (B-a) is in the range of less 0.03 m ² / g or more 0.40 m ² / g.

  In a color output system, for example, when only black toner is used and toner of other colors is not output for a long period of time, the toner developing machine other than black toner is agitated in the same drive, so that the stress on the toner is large and the toner Since there is no replacement, a large-diameter external additive may be embedded in the toner surface, resulting in a decrease in transferability. When a specific color toner is not used for a long period of time, a phenomenon that a large-diameter external additive is embedded in the toner surface may occur, resulting in a color point due to a decrease in density or charging failure. In particular, this phenomenon may be remarkable under high temperature and high humidity where the external additive is easily embedded in the toner.

  In a normal carrier, the BET specific surface area of the carrier (coated particle) is smaller than the BET specific surface area of the core particle, whereas in this embodiment, the BET specific surface area of the carrier (coated particle) is the BET specific surface area of the core particle. The difference between the BET specific surface area of the carrier and the BET specific surface area of the core particles is within a predetermined range, thereby imparting chargeability to a large-diameter external additive that is usually difficult to be charged. Thus, the external additive can be prevented from being embedded in the toner. Therefore, it has excellent transferability and hardly generates color points due to density reduction or charging failure.

  When the volume average particle size of the external additive is less than 105 nm, the transferability of the toner cannot be ensured, and a color point is generated due to a decrease in image density or charging failure. When the volume average particle diameter of the external additive exceeds 300 nm, the charge imparting effect to the large-diameter external additive is reduced, toner transferability cannot be ensured, and the color point due to a decrease in image density or poor charging is observed. Occur. The volume average particle diameter of the external additive is preferably in the range of 120 nm to 200 nm.

  Specifically, the volume average particle diameter of the external additive can be measured by the following method. First, 100 mg of a measurement sample is added to a solution obtained by diluting 2 mL of a 5% aqueous solution of sodium alkylbenzenesulfonate with 100 mL of pure water. About the liquid which suspended the sample, it disperse | distributes for 1 minute with an ultrasonic disperser, and uses a laser diffraction / scattering type particle size distribution analyzer (LS Particle Size Analyzer: LS13320, Beckman Coulter Co., Ltd.) in water. The particle size distribution is measured at a pump speed of 50%. For the obtained particle size distribution, the volume cumulative distribution is subtracted from the small particle size side with respect to the divided particle size range (channel), and the particle size that becomes 50% cumulative is defined as the volume average particle size D50v. The diameter.

When the BET specific surface area A of the core particles is less than 0.13 m ² / g, the BET specific surface area of the carrier is not increased and the charge amount is insufficient. Further, when the BET specific surface area A of the core particles is larger than 0.25 m ² / g, the strength of the core particles becomes weak, and the core particles are broken and exposed to the core particles during carrier production, so that the carrier resistance is lowered. As a result, carrier transfer to the photoconductor occurs. BET specific surface area of the core particles is preferably 0.14 m ² / g or more 0.22 m ² / g or less in a range, 0.15 m ² / g or more 0.20 m ² / g or less in the range is more preferable.

When the difference (B−A) between the BET specific surface area B of the carrier (coated particles) and the BET specific surface area A of the core particles is less than 0.03 m ² / g, sufficient charge is given to the large-diameter external additive. Transfer failure due to embedding of the large-diameter external additive in the toner occurs, and when it is larger than 0.40 m ² / g, the adhesion force between the carrier and the large-diameter external additive is increased, Transfer defects occur when the external additive is detached from the toner. The difference (B-A) is preferably from 0.05 m ² / g or more 0.13 m ² / g or less in a range, 0.07 m ² / g or more 0.12 m ² / g or less in the range is more preferable.

  The BET specific surface area of the carrier and the core particle can be measured by a nitrogen substitution method, and is measured by a three-point method using an SA3100 specific surface area measuring device (manufactured by Beckman Coulter, Inc.). Specifically, 5 g as a core particle sample is put into a cell, subjected to a degassing treatment at 60 ° C. for 120 minutes, and measured using a mixed gas of nitrogen and helium (30:70). The BET specific surface area of the carrier and core particles in the developer is determined by 10 times of dispersing the developer in a solution obtained by diluting 30 mL of a 5% aqueous solution of sodium alkylbenzenesulfonate with 200 mL of pure water and separating the toner by magnetic force 10 times. After repeating, drying and taking out the carrier, followed by dissolving the coating agent covering the carrier with toluene and separating the carrier core and the solution by magnetic force 10 times, followed by drying Then, it can be measured by taking out the core particles.

  In the developer for developing an electrostatic image according to the exemplary embodiment, the toner preferably contains a crystalline resin.

  Usually, the resistance of the carrier is adjusted to ensure the developability of the toner, but the resistance of the developer decreases due to moisture adsorption under high temperature and high humidity, whereas the resistance of the developer does not decrease much under low temperature and low humidity. Therefore, the resistance may increase in a low temperature and low humidity environment. When the resistance of the developer decreases, the white line called the brush mark due to the carrier transfer to the photoconductor called carrier over and the charge leak may occur in the solid image. In this case, the resistance becomes high under low temperature and low humidity, and the rear end chipping or the high density part where the image density at the rear end of the high density patch image is low (relative to the image traveling direction) is removed. There may be an image defect called starvation in which the image density at the rear end of the intermediate density portion that is later reduced.

  Therefore, the toner contains a crystalline resin, and the BET specific surface area of the carrier (coated particle) is larger than the BET specific surface area of the core particle, and the difference between the BET specific surface area of the carrier and the BET specific surface area of the core particle is within a predetermined range. As a result, moisture contained in the crystalline resin of the toner can be adsorbed to the carrier surface even under low temperature and low humidity, and the resistance of the carrier surface can be lowered. Therefore, a clear image that does not generate TED or STV even under low temperature and low humidity can be obtained. Can be obtained.

  Further, the content of the crystalline resin in the toner is preferably in the range of 3 wt% to 30 wt%, and more preferably in the range of 5 wt% to 15 wt%.

  When the content of the crystalline resin in the toner is less than 3% by weight, the effect of supplying moisture to the carrier surface under low temperature and low humidity is insufficient, and white spots may occur under low temperature and low humidity. When the content of the crystalline resin in the toner exceeds 30% by weight, the resistance of the developer is excessively lowered under high temperature and high humidity, so that white spots may occur due to carrier transfer to the photoreceptor.

Further, when the difference (BA) between the BET specific surface area B of the carrier (coated particles) and the BET specific surface area A of the core particles is less than 0.03 m ² / g, the moisture adsorption capacity of the carrier is insufficient. In some cases, TED and STV may be generated under low temperature and low humidity. When the TED and STV are larger than 0.40 m ² / g, the contact area between the carrier and the toner is reduced, and the resistance is increased. May occur.

  The content of the crystalline resin in the toner contained in the developer is determined by dispersing the developer in a solution obtained by diluting 30 mL of a 5% aqueous solution of sodium alkylbenzenesulfonate with 200 mL of pure water and separating the toner by magnetic force. After repeating 10 times, the toner was removed by drying, and the heat of fusion of the crystalline resin was determined by differential scanning calorimetry (DSC). Specifically, first, a calibration curve of endothermic amount-crystalline resin content (% by mass) is prepared by blending a known amount of a crystalline resin and an amorphous resin and performing DSC measurement. Next, the toner sample subjected to annealing treatment at 50 ° C. for 24 hours is measured, and the content of the crystalline resin in the toner can be obtained from the result and the calibration curve. The DSC measurement is performed from 20 ° C. to 150 ° C. at a heating rate of 10 ° C./min.

Regarding the core particle and the carrier, the shape factor SF1 represented by the following formula (1) is preferably in the range of 100 to 130, and more preferably in the range of 100 to 120. The shape factor SF1 becomes a true sphere as it approaches 100. When the shape factor SF1 of the carrier exceeds 130, the carriers may collide with each other due to distortion of the shape, and the convex portion may be chipped.
SF1 = (ML ² / A) × (π / 4) × 100 (1)
In formula (1), ML represents the absolute maximum length (μm) of carrier particles, and A represents the projected area (μm ² ) of carrier particles.

  The shape factor SF1 is an average value of the shape factors, and is calculated by the following method. An optical microscope image of carrier particles spread on a slide glass and magnified 250 times is taken into a Luzex image analyzer (LUZEX III, manufactured by Nireco) through a video camera. From the maximum length and projection area of 50 carriers For each particle, SF1 is obtained by the above formula, and an average value is obtained. The shape factor SF1 of the carrier in the developer is determined by putting the developer in water containing a surfactant, separating the toner and the carrier with ultrasonic waves, and then taking out only the carrier with a magnet and performing the image analysis. Can be obtained.

  The volume average particle size of the carrier is preferably in the range of 20 μm to 60 μm. When the volume average particle diameter of the carrier is larger than 60 μm, the collision energy in the developing machine increases, so that not only the cracking and chipping of the carrier is promoted, but also the surface area for charging the toner is reduced, and the toner In some cases, the charge imparting function of the image quality deteriorates, resulting in a decrease in image quality. In addition, when the volume average particle diameter of the carrier is less than 20 μm, the magnetic force per unit number of the carrier is lowered, so that the magnetic binding force of the chain on the magnetic brush is weaker than the developing electric field, and the carrier is applied to the photoconductor. Migration may increase. The volume average particle size of the carrier is more preferably in the range of 25 μm to 55 μm, and further preferably in the range of 30 μm to 50 μm.

  The volume average particle diameter of the carrier can be measured as follows. First, 100 mg of a measurement sample is added to a solution obtained by diluting 2 mL of a 5% aqueous solution of sodium alkylbenzenesulfonate with 100 mL of pure water. About the liquid which suspended the sample, it disperse | distributes for 1 minute with an ultrasonic disperser, and uses a laser diffraction / scattering type particle size distribution analyzer (LS Particle Size Analyzer: LS13320, Beckman Coulter Co., Ltd.) in water. Measure at a pump speed of 90%. The obtained particle size distribution is obtained by subtracting the volume cumulative distribution from the small particle size side with respect to the divided particle size range (channel), and the particle size that becomes 50% cumulative is defined as the volume average particle size D50v. To do.

As the core particles (carrier core material), any conventionally known particles can be used, and ferrite and magnetite are particularly preferably selected. For example, iron powder is known as another core particle. In the case of iron powder, since the specific gravity is large and the toner is likely to be deteriorated, ferrite and magnetite are more stable. An example of ferrite is generally represented by the following formula.
(MO) _X (Fe ₂ O ₃ ) _Y
(In the formula, M contains at least one selected from Cu, Zn, Fe, Mg, Mn, Ca, Li, Ti, Ni, Sn, Sr, Al, Ba, Co, Mo, etc. X, Y represents the molar ratio by weight and satisfies the condition X + Y = 100)

The M is preferably a ferrite particle which is one or a combination of Li, Mg, Ca, Mn, Sr and Sn, and the content of other components is 1% by weight or less. By adding Cu, Zn and Ni elements, the resistance tends to be low, and charge leakage tends to occur. In addition, the resin tends to be difficult to coat, and the environmental dependency tends to deteriorate. Furthermore, since it is a heavy metal, the stress given to a carrier becomes strong and may have a bad influence with respect to preservability. In recent years, from the viewpoint of safety, an element containing Mn element or Mg element has been widely used. Ferrite core material is preferable. As raw material of core particles, Fe ₂ O ₃ is an essential component, and as magnetic particles used, ferromagnetic iron oxide particles such as magnetite and maghemite, metals other than iron (Mn, Ni, Zn, Mg, Cu, etc.) are used. Spinel ferrite particle powder containing one or more kinds, magnet plumbite type ferrite particle powder such as barium ferrite, and iron or iron alloy particle powder having an oxide film on its surface are used. be able to.

  Specific examples of core particles include iron oxides such as magnetite, γ-iron oxide, Mn—Zn ferrite, Ni—Zn ferrite, Mn—Mg ferrite, Li ferrite, and Cu—Zn ferrite. Can be mentioned. Among these, inexpensive magnetite can be used more preferably.

  The core particles may be resin-dispersed core particles in which the magnetic particles (magnetic material) are dispersed in a binder resin.

  As the binder resin, a phenol resin, a melamine resin, an epoxy resin, a urethane resin, a polyester resin, a silicone resin, or the like is used, but a phenol resin is preferably included. By using a phenol-based resin, adhesion with the coating resin is improved, and long-term stability is further improved.

  At this time, the target surface state can be obtained by making the volume average particle diameter of the magnetic material in the binder resin uniform within a range of 5 μm or more and 10 μm or less, increasing the magnetic material ratio, and appropriately exposing the magnetic material.

  Examples of the coating resin used for the resin coating layer include polyolefin resins such as polyethylene, polypropylene; polyvinyl and polyvinylidene resins such as polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, and polyvinyl carbazole. , Polyvinyl ether and polyvinyl ketone; vinyl chloride / vinyl acetate copolymer; styrene / acrylic copolymer; straight silicone resin composed of organosiloxane bond or modified product thereof; fluororesin such as polytetrafluoroethylene, polyvinyl fluoride, Polyvinylidene fluoride, polychlorotrifluoroethylene; polyester; polyurethane; polycarbonate, amino resin such as urea-formal Hydrin resins, epoxy resins, perfluoroalkyl (meth) acrylate / (meth) acrylate copolymer; resin having a cycloalkyl group. These may be used alone or in combination with a plurality of resins.

  In the present embodiment, the coating resin layer preferably contains a resin having a cycloalkyl group that is a hydrophobic group. Examples of such resins include (1) a homopolymer of a monomer containing a cycloalkyl group in the side chain, (2) a copolymer obtained by polymerizing two or more monomers containing a cycloalkyl group in the side chain, (3 And a copolymer of a monomer containing a cycloalkyl group in the side chain and a monomer containing no cycloalkyl group. In the case of (3) above, the ratio of the monomer containing a cycloalkyl group is preferably 95 mol% or more in the total monomers.

  The cycloalkyl group is preferably a 3- to 10-membered ring, and is a cyclohexyl group, adamantyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, cyclononyl group, cyclodecyl group, Examples thereof include an isobornyl group, a norbornyl group, and a boronyl group, and a cyclohexyl group and an adamantyl group are particularly preferable from the viewpoint of availability of monomers.

  Examples of monomers containing these cycloalkyl groups in the side chain include cyclohexyl methacrylate, adamantyl methacrylate, cyclopropyl acrylate, adamantyl acrylate, cyclopropyl acrylate, cyclopropyl methacrylate, cyclobutyl acrylate, cyclobutyl methacrylate, cyclopentyl. Acrylate, cyclopentyl methacrylate, cycloheptyl acrylate, cycloheptyl methacrylate, cyclooctyl acrylate, cyclooctyl methacrylate, cyclononyl acrylate, cyclononyl methacrylate, cyclodecyl acrylate, cyclodecyl methacrylate, isobornyl acrylate, isobornyl methacrylate , Cyclonorbornyl acrylate, chic Norbornyl Le methacrylate, cycloalkyl rags sulfonyl acrylate, cycloalkyl rag cycloalkenyl meth acrylate. From the viewpoints of availability, glass transition temperature, manufacturability as a carrier, cyclohexyl methacrylate and adamantyl methacrylate are particularly preferable.

  Monomers that do not contain cycloalkyl groups include nitrogen-containing acrylic monomers including amino group-containing acrylic monomers such as dimethylaminoethyl methacrylate, methylaminoethyl methacrylate, dimethylaminobutyl methacrylate, and derivatives thereof; other acrylic monomers Monomers constituting olefin resins such as polyethylene and polypropylene; monomers constituting polyvinyl resins and polyvinylidene resins such as polystyrene resin, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; Monomers constituting straight silicone resin composed of siloxane bond or modified product thereof; polytetrafluoroethylene, polyvinyl fluoride Monomers constituting fluorine-based resins such as polyvinylidene fluoride and polychlorotrifluoroethylene; constituting amino resins such as polyurethane resins, phenol resins, urea-formaldehyde resins (urea resins), melamine resins, benzoguanamine resins and polyamide resins Monomers constituting monomers known in themselves such as monomers; monomers constituting epoxy resins; and the like. Among these, a nitrogen-containing acrylic monomer is particularly preferable. This is because carriers easily hold charges. Further, among them, an amino group-containing acrylic monomer is more preferable, and dimethylamino methacrylate is more preferable.

  The coating resin is preferably a copolymer of a cycloalkyl methacrylate having a cycloalkyl group that is a hydrophobic group and a dialkylaminoalkyl methacrylate having a polar group (for example, a copolymer weight ratio of 99.5: 0.5). To 60:40), particularly preferably a copolymer of cyclohexyl methacrylate and dimethylaminoethyl methacrylate (for example, copolymer weight ratio 99: 1 to 80:20).

  When a copolymer of cycloalkyl methacrylate and dialkylaminoalkyl methacrylate is used as the coating resin, it is easy to form fine irregularities on the surface of the resin coating layer, and the BET specific surface area of the carrier is increased to increase the BET of the carrier. The specific surface area can be made larger than the BET specific surface area of the core particles.

In the carrier according to the present embodiment, as a method of controlling the BET specific surface area difference 0.03 m ² / g or more 0.40 m ² / g or less, as described above, having a polar group of the resin used for the covering layer Examples thereof include a method of reducing the load on a carrier during production by using a copolymer of a monomer and a monomer having no polar group. Specifically, when producing with a kneader, it can be controlled within the above range by lowering the degree of vacuum and producing under low stirring conditions.

  The resin coating layer may contain a negative charge control agent. Negative charge control agents include trimethylethane dyes, metal complexes of salicylic acid, metal complexes of benzylic acid, copper phthalocyanine, perylene, quinacridone, azo pigments, metal complex azo dyes, azochrome complexes, etc. Examples thereof include dyes, calixarene type phenolic condensates, cyclic polysaccharides, resins containing carboxyl groups and / or sulfonyl groups, and the like.

  The content of the negative charge control agent is preferably in the range of 0.001% by weight to 1.0% by weight with respect to the weight of the core particles, and is 0.01% by weight to 0.8% by weight. More preferably, it is the range. If the content of the negative charge control agent is less than 0.001% by weight with respect to the weight of the core particles, there may be no effect on the toner charge rising property. It may inhibit the charging ability.

  The resin coating layer of the carrier may be used in combination with conductive powder (conductive particles) for adjusting carrier resistance. Examples of the conductive particles include metal powder, carbon black, titanium oxide, tin oxide, and zinc oxide. These conductive particles preferably have a volume average particle size of 1 μm or less. When the volume average particle size is larger than 1 μm, it is difficult to control the dispersion of the powder in the resin coating layer, and it may be difficult to control the electric resistance. The addition amount of the conductive particles is preferably less than 20% by volume of the resin coating layer. When 20 volume% or more is added, it is difficult to control the dispersion of the powder in the resin coating layer, and it may be difficult to control the electric resistance. Examples of the method for dispersing the conductive particles include a sand mill, a dyno mill, and a homomixer.

  Further, the resin coating layer of the carrier may contain a wax. Waxes are hydrophobic, are relatively soft at room temperature, and have low film strength. This originates from the molecular structure of the wax, but due to this characteristic, when wax is present in the resin coating layer, toner components such as external additives added to the toner surface or toner bulk components are added to the carrier surface. Hard to adhere. Even if it adheres, the surface of the carrier is renewed by peeling off the wax at the adhesion level at the molecular level, and the carrier surface is not easily contaminated.

  The wax is not particularly limited, and examples thereof include paraffin wax and derivatives thereof, montan wax and derivatives thereof, microcrystalline wax and derivatives thereof, Fischer-Tropsch wax and derivatives thereof, polyolefin wax and derivatives thereof, and the like. Derivatives include oxides, polymers with vinyl monomers, and graft modified products. In addition, alcohols, fatty acids, plant waxes, animal waxes, mineral waxes, ester waxes, acid amides, and the like can be used. Other known materials can also be used. The melting point of the wax is preferably 60 ° C. or higher and 200 ° C. or lower. More preferably, the melting point of the wax is 80 ° C. or higher and 150 ° C. or lower. If it is less than 60 degreeC, the fluidity | liquidity as a carrier may deteriorate.

  The thickness of the resin coating layer is preferably in the range of 0.1 μm to 5 μm, and more preferably in the range of 0.2 μm to 3 μm. If the thickness of the resin coating layer is smaller than 0.1 μm, it may be difficult to form a uniform and flat resin coating layer on the core particle surface. On the other hand, if the thickness is larger than 5 μm, carriers may be aggregated and it may be difficult to obtain a uniform carrier.

  The toner is not particularly limited, and a known toner containing a binder resin and a colorant as main components and containing a release agent or the like as necessary can be used. The toner may be produced by a dry production method such as a kneading and pulverization method, or may be produced by a wet production method such as an emulsion polymerization aggregation method, a dissolution suspension method, or a suspension polymerization method. . A toner produced by an emulsion polymerization aggregation method is preferred from the standpoint that the surface exposure of the colorant and the release agent is small and the stability of the image is good.

  Such a toner has a relatively round particle shape, a narrow particle size distribution, a relatively uniform toner surface, high chargeability, and a narrow charge distribution. Since this toner has a narrow particle size distribution, the occurrence of fogging is small.

  The binder resin for the toner includes monoolefins such as ethylene, propylene, butylene, and isoprene; vinyl esters such as vinyl acetate, vinyl propionate, vinyl benzoate, and vinyl butyrate; methyl acrylate, phenyl acrylate, octyl acrylate, Α-methylene aliphatic monocarboxylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl butyl ether; vinyl methyl ketone, vinyl hexyl ketone And non-crystalline resins such as homopolymers such as vinyl ketones such as vinyl isopropenyl ketone; and copolymers thereof. Among these, particularly typical binder resins include polystyrene, styrene-alkyl acrylate copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polystyrene, polypropylene, and the like. Further examples include polyester, polyurethane, epoxy resin, silicone resin, polyamide, modified rosin and the like.

  As described above, the binder resin preferably includes a crystalline resin having crystallinity, and may include a crystalline resin and the amorphous resin.

  In the present embodiment, “crystallinity” of “crystalline resin” refers to having a clear endothermic peak rather than a stepwise endothermic amount change in differential scanning calorimetry (DSC) of the resin or toner. Specifically, in differential scanning calorimetry (DSC) using a differential scanning calorimeter (equipment name: DSC-60 type) manufactured by Shimadzu Corporation equipped with an automatic tangential processing system, a rate of temperature increase of 10 ° C./min. A “clear” endothermic peak is assumed when the temperature from the onset point to the top of the endothermic peak when the temperature is raised at 10 ° C. is within 10 ° C. Further, from the viewpoint of sharp melt, the temperature from the onset point to the peak top of the endothermic peak is preferably within 10 ° C, and more preferably within 6 ° C. Specify any point on the flat part of the baseline in the DSC curve and any point on the flat part of the falling part from the baseline, and the intersection of the tangents of the flat part between the two points is automatically set as the “onset point”. Obtained automatically by the tangent processing system. Further, the endothermic peak may show a peak having a width of 40 ° C. or more and 50 ° C. or less when the toner is used.

  Further, the “amorphous resin” used as the binder resin means that when the temperature from the onset point to the peak top of the endothermic peak exceeds 10 ° C. in the differential scanning calorimetry (DSC) of the resin or toner, or clearly It indicates that the resin does not show a significant endothermic peak. Specifically, in differential scanning calorimetry (DSC) using a differential scanning calorimeter (equipment name: DSC-60 type) manufactured by Shimadzu Corporation equipped with an automatic tangential processing system, a rate of temperature increase of 10 ° C./min. When the temperature from the onset point to the top of the endothermic peak when the temperature is raised at 10 ° C. exceeds 10 ° C., or when no clear endothermic peak is observed, it is assumed to be “amorphous”. Further, the temperature from the onset point to the peak top of the endothermic peak preferably exceeds 12 ° C., and more preferably no clear endothermic peak is observed. The method for obtaining the “onset point” in the DSC curve is the same as in the case of the “crystalline resin”.

  Specific examples of the crystalline resin include crystalline polyester resin, crystalline vinyl resin, and the like. From the viewpoint of adhesion to paper at the time of fixing, chargeability, and adjustment of the melting point within a preferable range, A preferred polyester resin is preferred. An aliphatic crystalline polyester resin having an appropriate melting point is more preferable.

  Crystalline vinyl resins include amyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, Undecyl (meth) acrylate, tridecyl (meth) acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, oleyl (meth) acrylate, behenyl (meth) acrylate, etc. Examples thereof include vinyl resins using long-chain alkyl and alkenyl (meth) acrylic acid esters. In the present specification, the description “(meth) acryl” means that both “acryl” and “methacryl” are included.

  The crystalline polyester resin is synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In this embodiment, the “acid-derived constituent component” is an acid component before synthesis of the polyester resin. The “alcohol-derived constituent component” refers to a constituent portion that was an alcohol component before the synthesis of the polyester resin. In the case of a polymer in which other components are copolymerized with respect to the crystalline polyester main chain, when the other components are 50% by weight or less, this copolymer is also called a crystalline polyester resin.

[Acid-derived components]
The acid-derived constituent component is preferably an aliphatic dicarboxylic acid, and particularly preferably a linear carboxylic acid. Examples of the linear carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10- Decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecane Dicarboxylic acid, etc., or lower alkyl esters and acid anhydrides thereof. Among these, those having 6 to 10 carbon atoms are preferable from the viewpoint of crystal melting point and chargeability. In order to increase the crystallinity, these linear dicarboxylic acids are preferably used in an amount of 95 mol% or more, more preferably 98 mol% or more of the acid component.

  Other monomers are not particularly limited, and examples thereof include conventionally known divalent carboxylic acids, which are monomer components as described in Polymer Data Handbook: Basic Edition (edited by Polymer Society: Bafukan). There are divalent alcohols. Specific examples of these monomer components include divalent carboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, and cyclohexanedicarboxylic acid. And dibasic acids such as these, anhydrides thereof, and lower alkyl esters thereof. These may be used individually by 1 type and may use 2 or more types together.

  As the acid-derived constituent component, in addition to the above-mentioned aliphatic dicarboxylic acid-derived constituent component, a constituent component such as a dicarboxylic acid-derived constituent component having a sulfonic acid group is preferably included.

  A dicarboxylic acid having a sulfonic acid group is effective in that it can favorably disperse a colorant such as a pigment. Further, when the toner base particles are prepared by emulsifying or suspending the entire resin in water, if the sulfonic acid group is present, it can be emulsified or suspended without using a surfactant as described later. . Examples of such a dicarboxylic acid having a sulfone group include, but are not limited to, 2-sulfoterephthalic acid sodium salt, 5-sulfoisophthalic acid sodium salt, and sulfosuccinic acid sodium salt. Moreover, these lower alkyl esters, acid anhydrides, etc. are also mentioned. Among these, 5-sulfoisophthalic acid sodium salt is preferable in terms of cost. The content of the dicarboxylic acid having a sulfonic acid group is preferably 0.1 mol% or more and 2.0 mol% or less, and more preferably 0.2 mol% or more and 1.0 mol% or less. When the content is more than 2.0 mol%, the chargeability may be deteriorated. In the present embodiment, “component mol%” refers to a percentage when each component (acid-derived component and alcohol-derived component) in the polyester resin is defined as 1 unit (mol).

[Alcohol-derived components]
The alcohol component is preferably an aliphatic dialcohol, such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol. 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-dodecanediol, 1,12-undecanediol, 1,13-tridecanediol, 1,14-tetradecanediol 1,18-octadecanediol, 1,20-eicosanediol, etc., among which those having 6 to 10 carbon atoms are preferred from the viewpoint of crystal melting point and chargeability. In order to enhance crystallinity, these linear dialcohols are preferably used in an amount of 95 mol% or more, more preferably 98 mol% or more of the alcohol constituent.

  Other divalent dialcohols include, for example, bisphenol A, hydrogenated bisphenol A, ethylene oxide or propylene oxide adducts of bisphenol A, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, propylene glycol, Examples include dipropylene glycol, 1,3-butanediol, and neopentyl glycol. These may be used individually by 1 type and may use 2 or more types together.

  If necessary, monovalent acids such as acetic acid and benzoic acid, monovalent alcohols such as cyclohexanol and benzyl alcohol, benzenetricarboxylic acid, and naphthalenetricarboxylic acid for the purpose of adjusting the acid value and hydroxyl value. Trivalent alcohols such as acids and the like, anhydrides thereof, lower alkyl esters thereof, glycerin, trimethylolethane, trimethylolpropane, pentaerythritol and the like can also be used.

  Crystalline polyester resins can be used in any combination of the above monomer components, for example, polycondensation (chemical doujin), polymer experimental studies (polycondensation and polyaddition: Kyoritsu Publishing) and polyester resin handbook (Nikkan Kogyo Shimbun) And the like, and a transesterification method, a direct polycondensation method, and the like can be used alone or in combination. The molar ratio (acid component / alcohol component) when the acid component and the alcohol component are reacted varies depending on the reaction conditions and the like, so it cannot be generally stated, but in the case of direct polycondensation, usually about 1/1. In the case of the transesterification method, ethylene monomer, neopentyl glycol, cyclohexanedimethanol, etc. are often used in an excess of monomers that can be distilled off under vacuum. The production of the polyester resin is usually performed at a polymerization temperature of 180 ° C. or higher and 250 ° C. or lower, and the reaction system is subjected to a reaction while reducing the pressure in the reaction system and removing water, alcohol, etc. generated during condensation. When the monomer is not dissolved or compatible with the reaction temperature, a high boiling point solvent may be added as a solubilizing solvent to dissolve the monomer. In the polycondensation reaction, the dissolution auxiliary solvent is distilled off. When a monomer having poor compatibility exists in the copolymerization reaction, the monomer having poor compatibility and the monomer and the acid or alcohol to be polycondensed are condensed in advance and then polycondensed together with the main component.

  Catalysts that can be used in the production of the crystalline polyester resin include alkali metal compounds such as sodium and lithium, alkaline earth metal compounds such as magnesium and calcium, metals such as zinc, manganese, antimony, titanium, tin, zirconium and germanium. Compounds, phosphorous acid compounds, phosphoric acid compounds, and amine compounds. Specific examples include sodium acetate, sodium carbonate, lithium acetate, lithium carbonate, calcium acetate, calcium stearate, magnesium acetate, zinc acetate, stearin. Zinc oxide, zinc naphthenate, zinc chloride, manganese acetate, manganese naphthenate, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, antimony trioxide, triphenylantimony, Butylantimony, tin formate, tin oxalate, tetraphenyltin, dibutyltin dichloride, dibutyltin oxide, diphenyltin oxide, zirconium tetrabutoxide, zirconium naphthenate, zirconyl carbonate, zirconyl acetate, zirconyl stearate, zirconyl octylate, germanium oxide, triphenyl Examples of the compound include phosphite, tris (2,4-di-t-butylphenyl) phosphite, ethyltriphenylphosphonium bromide, triethylamine, and triphenylamine. Among these, a tin-based catalyst and a titanium-based catalyst are preferable from the viewpoint of chargeability, and dibutyltin oxide is preferably used.

  The melting point of the crystalline polyester resin of the present embodiment is preferably 50 ° C. or higher and 120 ° C. or lower, more preferably 60 ° C. or higher and 110 ° C. or lower. If the melting point is lower than 50 ° C., the storage stability of the toner and the storage stability of the toner image after fixing may be problematic. If the melting point is higher than 120 ° C., sufficient low-temperature fixing may not be obtained as compared with conventional toners.

  In this embodiment, the melting point of the crystalline polyester resin is measured according to JIS K when a differential scanning calorimeter (DSC) is used and measured from room temperature to 150 ° C. at a heating rate of 10 ° C. per minute. It can be obtained as the melting peak temperature of the input compensation differential scanning calorimetry shown in −7121. The crystalline resin may show a plurality of melting peaks, but in the present embodiment, the maximum peak is regarded as the melting point.

  Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brillianthamine 3B, and brillianthamine. 6B, DuPont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Phthalocyanine Green, Malachite Green Oxalate, etc. Or acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thio Various dyes such as Ndico, Dioxazine, Thiazine, Azomethine, Indico, Thioindico, Phthalocyanine, Aniline Black, Polymethine, Triphenylmethane, Diphenylmethane, Thiazine, Thiazole, and Xanthene Or in combination of two or more.

  In the toner according to the exemplary embodiment, the content of the colorant is preferably in the range of 1 part by weight to 30 parts by weight with respect to 100 parts by weight of the binder resin. It is also effective to use a surface-treated colorant or a pigment dispersant. By appropriately selecting the type of the colorant, yellow toner, magenta toner, cyan toner, black toner and the like can be obtained.

  Examples of release agents include low molecular weight polyolefins such as polyethylene, polypropylene and polybutene; silicones having a softening point upon heating; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; Plant waxes such as ester wax, carnauba wax, rice wax, candelilla wax, tree wax, jojoba oil, etc .; animal waxes such as beeswax; montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, fisher Mineral waxes such as Tropsch wax and the like; petroleum waxes; and modified products thereof can be used. The addition amount of the release agent can be added in the range of 50% by weight or less with respect to the toner.

  As other internal additives, metals such as ferrite, magnetite, reduced iron, cobalt, nickel, and manganese, alloys thereof, or compounds containing these metals can be used. As the charge control agent, various commonly used charge control agents such as quaternary ammonium salts, nigrosine compounds, dyes composed of complexes of aluminum, iron, chromium, and triphenylmethane pigments can be used. In order to control the ionic strength that affects the stability during aggregation and fusion integration and to reduce wastewater contamination, a charge control agent that is not easily dissolved in water is preferable.

  Examples of inorganic particles to be wet-added include silica, alumina, titania, calcium carbonate, magnesium carbonate, and tricalcium phosphate, all of which are usually used as external additives on the toner surface, such as ionic surfactants and It can be dispersed in a polymer acid or a polymer base and wet-added.

  Surfactants used for emulsion polymerization, seed polymerization, pigment dispersion, resin particles, release agent dispersion, aggregation, or stabilization in the toner manufacturing process by a wet manufacturing method include sulfate ester salts, sulfonate salts, phosphorus Examples thereof include anionic surfactants such as acid esters and soaps, and cationic surfactants such as amine salts and quaternary ammonium salts, and also polyethylene glycols, alkylphenol ethylene oxide adducts, polyhydric alcohols. It is also effective to use a nonionic surfactant such as a system together.

  The external additive used in the present embodiment is not particularly limited as long as it contains at least one external additive having a volume average particle size of 105 nm to 300 nm. Moreover, it is preferable that the external additive of a small diameter whose volume average particle diameter is 8 nm or more and 30 nm or less is further included. As the external additive, known external additives such as inorganic particles and organic particles can be used. Among these, inorganic particles such as silica, titania, alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate and calcium phosphate, metal soap such as zinc stearate, fluorine-containing resin particles, silica-containing resin particles and nitrogen Organic resin particles such as containing resin particles are preferred. Moreover, you may surface-treat on the surface of an external additive according to the objective. Examples of the surface treatment agent include a silane compound, a silane coupling agent, and a silicone oil for performing a hydrophobic treatment.

  The volume average particle size of the toner according to the exemplary embodiment is preferably in the range of 4 μm to 8 μm, and more preferably in the range of 5 μm to 7 μm. If the volume average particle diameter of the toner is less than 4 μm, the amount of fine powder increases, so that toner fog and poor cleaning are likely to occur.

  The volume average particle size distribution index GSDv of the toner for developing an electrostatic charge image according to this embodiment is preferably 1.27 or less, more preferably 1.25 or less. When GSDv exceeds 1.27, the particle size distribution is not sharp, resolution is deteriorated, and image defects such as toner scattering and fogging may be caused.

The volume average particle size D50v and the volume average particle size distribution index GSDv can be obtained by measuring with an aperture diameter of 100 μm using a Coulter-Multisizer-II type (manufactured by Beckman-Coulter). At this time, the measurement is performed after the toner is dispersed in an electrolyte aqueous solution (Isoton II aqueous solution) and dispersed by ultrasonic waves for 30 seconds or more. For the particle size range (channel) divided based on the measured particle size distribution of the toner, a cumulative distribution is drawn from the small diameter side for each of the volume and number, and the particle size that becomes 16% is the volume D16v and the cumulative is 50%. The particle diameter to be defined is defined as volume D50v, and the particle diameter to be accumulated 84% is defined as volume D84v. At this time, D50v represents the volume average particle diameter, and the volume average particle size distribution index (GSDv) is obtained as (D84v / D16v) ^1/2 .

  The ratio of the toner in preparing the developer by mixing the toner and the carrier is in the range of 1 to 15% by weight, preferably 3 to 12% by weight of the whole developer.

If the toner ratio is less than 1% by weight, it is difficult to obtain a sufficient image density, and a solid image is difficult to be uniform. On the other hand, if the amount exceeds 15% by weight, the toner coverage on the carrier surface exceeds 100%, and the charge amount decreases (when the average value of the average charge amount is less than 15 μC / g). Fog) High-quality color images cannot be obtained. For example, if the amount exceeds 15% by weight, the toner coverage on the carrier surface approaches 100%, so that the resistance value as a developer is extremely increased, and 1 × 10 ⁵ Ω · cm or more and 1 × 10 ⁸ Ω · cm or less. This makes it difficult to fit within the range, and it is difficult to obtain a good and high-quality color image such as blurring of the image edge portion.

  However, in a low-humidity environment, if the toner ratio is less than 1% by weight, a high charge amount (the absolute value of the average charge amount exceeds 25 μC / g) tends to occur, and it may be difficult to obtain a sufficient image density. Therefore, it is preferable to select the toner ratio so that the absolute value of the charging property is in the range of 15 μC / g or more and 50 μC / g or less according to the environment.

<Image forming apparatus>
The image forming apparatus according to the present embodiment includes an image carrier, latent image forming means for forming an electrostatic latent image on the surface of the image carrier, and developing the electrostatic latent image with a developer to form a toner image. A developing unit that forms the toner image, and a transfer unit that transfers the developed toner image to the transfer target. The developer for developing an electrostatic charge image is used as the developer. In addition, the image forming apparatus according to the present embodiment includes means other than those described above, for example, charging means for charging the image holding member, fixing means for fixing the toner image transferred to the surface of the transfer target, and the surface of the image holding member. Further, it may include a cleaning means for removing the remaining toner, carrier and the like.

  An example of the image forming apparatus according to the present embodiment is schematically shown in FIG. The image forming apparatus 1 includes a charging unit 10, an exposure unit 12, an electrophotographic photosensitive member 14 that is an image holding member, a developing unit 16, a transfer unit 18, a cleaning unit 20, and a fixing unit 22.

  In the image forming apparatus 1, the charging unit 10 that is a charging unit that charges the surface of the electrophotographic photosensitive member 14 and the charged electrophotographic photosensitive member 14 are exposed around the electrophotographic photosensitive member 14 according to image information. The exposure unit 12 is a latent image forming unit that forms an electrostatic latent image, the developing unit 16 is a developing unit that develops the electrostatic latent image with toner to form a toner image, and the surface of the electrophotographic photoreceptor 14. A transfer unit 18 that is a transfer unit that transfers the toner image formed on the surface of the transfer target 24, and a cleaning unit 20 that is a cleaning unit that removes toner remaining on the surface of the electrophotographic photosensitive member 14 after transfer. Are arranged in this order. A fixing unit 22 that is a fixing unit that fixes the toner image transferred to the transfer target 24 is arranged on the left side of the transfer unit 18.

  An operation of the image forming apparatus 1 according to the present embodiment will be described. First, the surface of the electrophotographic photosensitive member 14 is uniformly charged by the charging unit 10 (charging process). Next, light is applied to the surface of the electrophotographic photosensitive member 14 by the exposure unit 12, and the charged charges in the irradiated portion are removed, and an electrostatic charge image (electrostatic latent image) is formed according to the image information. (Latent image forming step). Thereafter, the electrostatic charge image is developed by the developing unit 16, and a toner image is formed on the surface of the electrophotographic photosensitive member 14 (developing step). For example, in the case of a digital electrophotographic copying machine using an organic photoconductor as the electrophotographic photoconductor 14 and using a laser beam as the exposure unit 12, the surface of the electrophotographic photoconductor 14 is negatively charged by the charging unit 10. Then, a digital latent image is formed in a dot shape by the laser beam light, and toner is applied to the portion irradiated with the laser beam light by the developing unit 16 to be visualized. In this case, a negative bias is applied to the developing unit 16. Next, a transfer member 24 such as paper is superposed on the toner image at the transfer unit 18, and a charge opposite in polarity to the toner is applied to the transfer member 24 from the back side of the transfer member 24, and the toner image is generated by electrostatic force. Is transferred to the transfer target 24 (transfer process). The transferred toner image is heated and pressed by a fixing member in the fixing unit 22 and is fused and fixed to the transfer target 24 (fixing step). On the other hand, toner remaining on the surface of the electrophotographic photoreceptor 14 without being transferred is removed by the cleaning unit 20 (cleaning step). One cycle is completed in a series of processes from charging to cleaning. In FIG. 1, the toner image is directly transferred to the transfer target 24 such as a sheet by the transfer unit 18, but may be transferred via a transfer member such as an intermediate transfer member.

  Hereinafter, the charging unit, the image carrier, the exposure unit, the developing unit, the transfer unit, the cleaning unit, and the fixing unit in the image forming apparatus 1 of FIG. 1 will be described.

(Charging means)
For example, a charging device such as a corotron as shown in FIG. 1 is used as the charging unit 10 serving as a charging unit, but a conductive or semiconductive charging roll may be used. A contact charger using a conductive or semiconductive charging roll may apply a direct current to the electrophotographic photosensitive member 14 or may superimpose an alternating current. For example, the charging unit 10 charges the surface of the electrophotographic photosensitive member 14 by generating a discharge in a minute space near the contact portion with the electrophotographic photosensitive member 14. Normally, it is charged to −300V or more and −1000V or less. The conductive or semiconductive charging roll may have a single layer structure or a multiple structure. Further, a mechanism for cleaning the surface of the charging roll may be provided.

(Image carrier)
The image carrier has a function of forming at least a latent image (electrostatic charge image). As the image carrier, an electrophotographic photosensitive member is preferably exemplified. The electrophotographic photoreceptor 14 has a coating film containing an organic photoreceptor or the like on the outer peripheral surface of a cylindrical conductive substrate. The coating film is a substrate in which a subbing layer and a photosensitive layer including a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material are formed in this order, if necessary. is there. The order of stacking the charge generation layer and the charge transport layer may be reversed. These are laminated photoconductors in which a charge generation material and a charge transport material are contained in separate layers (charge generation layer, charge transport layer), but both the charge generation material and the charge transport material are the same. A single-layer type photoreceptor included in the above layer may be used, and a laminated photoreceptor is preferable. Further, an intermediate layer may be provided between the undercoat layer and the photosensitive layer. In addition, other types of photosensitive layers such as an amorphous silicon photosensitive film may be used in addition to the organic photoreceptor.

(Exposure means)
There are no particular limitations on the exposure unit 12 that is an exposure means. For example, an optical device that can expose a light source such as semiconductor laser light, LED light, or liquid crystal shutter light on the surface of the image carrier in a desired image-like manner. Can be mentioned.

(Development means)
The developing unit 16 serving as a developing unit has a function of developing a latent image formed on the image carrier with a developer containing toner to form a toner image. Such a developing device is not particularly limited as long as it has the above-mentioned function, and can be appropriately selected according to the purpose. For example, toner for developing an electrostatic image is used using a brush, a roller, or the like. A known developing device having a function of adhering to the electrophotographic photosensitive member 14 may be used. The electrophotographic photoreceptor 14 normally uses a DC voltage, but may be used with an AC voltage superimposed thereon.

(Transfer means)
As the transfer unit 18 serving as a transfer unit, for example, a charge having a polarity opposite to that of the toner is applied to the transfer target 24 from the back side of the transfer target 24 as shown in FIG. A transfer roll and a transfer roll pressing device using a conductive or semiconductive roll that transfers directly to the surface of the transfer target 24 via the transfer target 24 can be used. . A direct current may be applied to the transfer roll as a transfer current applied to the image carrier, or an alternating current may be applied in a superimposed manner. The transfer roll can be arbitrarily set depending on the width of the image area to be charged, the shape of the transfer charger, the opening width, the process speed (circumferential speed), and the like. Further, a single layer foam roll or the like is suitably used as a transfer roll for cost reduction. As a transfer method, a method of transferring directly to the transfer target 24 such as paper or a method of transferring to the transfer target 24 via an intermediate transfer member may be used.

  A known intermediate transfer member can be used as the intermediate transfer member. Materials used for the intermediate transfer member include polycarbonate resin (PC), polyvinylidene fluoride (PVDF), polyalkylene phthalate, PC / polyalkylene terephthalate (PAT) blend material, ethylene tetrafluoroethylene copolymer (ETFE) / PC, ETFE / PAT, PC / PAT blend materials, and the like can be mentioned. From the viewpoint of mechanical strength, an intermediate transfer belt using a thermosetting polyimide resin is preferable.

(Cleaning means)
The cleaning unit 20 serving as a cleaning unit may be appropriately selected such as one that employs a blade cleaning method, a brush cleaning method, or a roll cleaning method as long as the toner remaining on the image carrier is cleaned. Among these, it is preferable to use a cleaning blade having elasticity.

  The material of the cleaning blade is not particularly limited, and various elastic bodies can be used. Specific elastic bodies include elastic bodies such as polyurethane elastic bodies, silicone rubber, and chloroprene rubber. Among them, it is preferable to use a polyurethane elastic body because of its excellent wear resistance.

  As the polyurethane elastic body, generally used is a polyurethane synthesized through an addition reaction of an isocyanate with a polyol and various hydrogen-containing compounds. This uses a polyether polyol such as polypropylene glycol or polytetramethylene glycol as a polyol component, or a polyester polyol such as an adipate polyol, polycaprolactam polyol or polycarbonate polyol, and a tolylene diisocyanate as an isocyanate component. Using aromatic polyisocyanates such as 4,4′-diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, toluidine diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, dicyclohexylmethane diisocyanate, etc. Prepare a urethane prepolymer, add a curing agent to it, and inject into a predetermined mold , After crosslinking and curing, it is prepared by aging at room temperature. As the curing agent, a dihydric alcohol such as 1,4-butanediol and a trihydric or higher polyhydric alcohol such as trimethylolpropane or pentaerythritol are usually used in combination.

(Fixing means)
The fixing unit 22 that is a fixing unit (image fixing device) fixes the toner image transferred to the transfer medium 24 by heating, pressing, or heating and pressing, and includes a fixing member.

(Transfer)
Examples of the transfer target (paper) 24 to which the toner image is transferred include plain paper, OHP sheet, and the like used in electrophotographic copying machines, printers, and the like. In order to further improve the smoothness of the image surface after fixing, it is preferable that the surface of the transfer target is as smooth as possible. For example, coated paper in which the surface of plain paper is coated with resin, art paper for printing, etc. Can be preferably used.

  Hereinafter, although an example and a comparative example are given and the present invention is explained more concretely in detail, the present invention is not limited to the following examples.

[Manufacture of base toner (1)]
(Preparation of cyan toner (1))
C. I. Pigment Blue 15: 3 (Dainippon Ink Chemical Co., Ltd.) 20 parts by weight, ethyl acetate 75 parts by weight, solvent-removed Disparon DA-703-50 (polyester acid amide amine salt, Enomoto Kasei Co., Ltd.) 4 parts by weight 1 part by weight of Solsperse 5000 (pigment derivative, manufactured by Zeneca Corp.) was dissolved and dispersed using a sand mill to prepare a pigment dispersion.

  As a release agent, 30 parts by weight of paraffin wax (melting point: 89 ° C.) and 270 parts by weight of ethyl acetate were wet pulverized in a state cooled to 10 ° C. using a DCP mill to prepare a wax dispersion.

  After stirring 136 parts by weight of an amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.), 34 parts by weight of pigment dispersion and 56 parts by weight of ethyl acetate, wax dispersion 75 Part by weight was added and stirred well until uniform (this solution was designated as solution A).

  A homogenizer (124 parts by weight of calcium carbonate dispersion dispersed in 40 parts by weight of calcium carbonate, 60 parts by weight of water, 99 parts by weight of a 2% aqueous solution of Serogen BS-H (Daiichi Kogyo Seiyaku Co., Ltd.) and 157 parts by weight of water The mixture was stirred for 5 minutes using Ultra Tarrax (manufactured by IKA) (this liquid was designated as B liquid).

  Furthermore, while stirring 345 parts by weight of the B liquid at 10,000 rpm using a homogenizer (Ultra Turrax, manufactured by IKA), 250 parts by weight of the A liquid was added and the mixture was suspended by stirring for 1 minute. The solvent was removed by stirring with a propeller-type stirrer at room temperature and normal pressure. Next, hydrochloric acid was added to remove calcium carbonate, followed by washing with water and drying. Subsequently, the obtained toner was put into a spray dryer and heated instantaneously to be spheroidized by surface tension. After that, the fine particles were removed again using an elbow jet classifier, and the volume average particle diameter was 6.5 μm. A cyan toner (1) having a fine particle size particle size distribution of 1.21 and a shape factor of 120 was obtained.

(Preparation of magenta toner (1))
In the adjustment of cyan toner (1), C.I. I. Pigment Blue 15: 3 20 parts by weight of C.I. I. CI Pigment Red 57: 1 (Dainippon Ink Chemical Co., Ltd.) Except for changing to 20 parts by weight, the volume average particle size 6.5 μm, fine powder side particle size distribution 1.21, shape A magenta toner (1) having a coefficient of 120 was obtained.

(Preparation of yellow toner (1))
In the adjustment of cyan toner (1), C.I. I. Pigment Blue 15: 3 20 parts by weight of C.I. I. Pigment Yellow 180 (Dainippon Ink Chemical Co., Ltd.) Except for the change to 20 parts by weight, the volume average particle size is 6.5 μm, the fine powder side particle size distribution is 1.21, and the shape factor is 120 in the same manner as the adjustment of cyan toner (1). Yellow toner (1) was obtained.

(Preparation of black toner (1))
In the adjustment of cyan toner (1), C.I. I. Pigment Blue 15: 3 The volume average particle size is 6.5 μm and the fine powder side particle size distribution is the same as that for cyan toner (1) except that 20 parts by weight of carbon black # 25 (Mitsubishi Chemical) is changed. A black toner (1) having 1.21 and a shape factor of 120 was obtained.

[Manufacture of base toner (2)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 120 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C.) 16 After stirring parts by weight, 34 parts by weight of the pigment dispersion and 56 parts by weight of ethyl acetate, 75 parts by weight of the wax dispersion was added and stirred well until uniform (this liquid was designated as liquid A). Except for the use of this liquid A, in the same manner as in the production of the base toner 1, a cyan toner (2) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, and a volume average particle size of 6 0.5 μm, fine powder side particle size distribution 1.21, magenta toner (2) with shape factor 120, volume average particle size 6.5 μm, fine powder side particle size distribution 1.21, shape toner 120 yellow toner (2), volume average particle A black toner (2) having a diameter of 6.5 μm, a fine particle size particle size distribution of 1.21, and a shape factor of 120 was obtained.

[Manufacture of base toner (3)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 131.5 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C. ) A cyan toner (3) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, and a volume average in the same manner as in the production of the base toner 2 except that 4.5 parts by weight are used. Magenta toner (3) having a particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, yellow toner (3) having a volume average particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, A black toner (3) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, and a shape factor of 120 was obtained.

[Manufacture of base toner (4)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 91 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C.) 45 Except for using parts by weight, in the same manner as in the production of the base toner 2, a cyan toner (4) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, a volume average particle size of 6. 5 μm, fine powder side particle size distribution 1.21, magenta toner (4) with shape factor 120, volume average particle size 6.5 μm, fine powder side particle size distribution 1.21, shape toner 120 yellow toner (4), volume average particle size A black toner (4) having a particle size distribution of 6.5 μm, a fine particle size distribution of 1.21, and a shape factor of 120 was obtained.

[Manufacture of base toner (5)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 128.5 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C. ) A cyan toner (5) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, and a volume average in the same manner as in the production of the base toner 2 except that 7.5 parts by weight are used. Magenta toner (5) having a particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, yellow toner (5) having a volume average particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, A black toner (5) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, and a shape factor of 120 was obtained.

[Manufacture of base toner (6)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 113.5 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C. ) A cyan toner (6) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, and a volume average in the same manner as in the production of the base toner 2 except that 22.5 parts by weight were used. Magenta toner (6) having a particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, yellow toner (6) having a volume average particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, A black toner (6) having a volume average particle size of 6.5 μm, a fine particle size particle size distribution of 1.21, and a shape factor of 120 was obtained.

[Manufacture of base toner (7)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 132.25 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C. ) A cyan toner (7) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, and a volume average in the same manner as in the production of the base toner 2 except that 3.75 parts by weight were used. Magenta toner (7) having a particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, yellow toner (7) having a volume average particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, A black toner (7) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, and a shape factor of 120 was obtained.

[Manufacture of base toner (8)]
Amorphous polyester resin (weight average molecular weight Mw: 12,000, Tg: 65 ° C., softening point: 100 ° C.) 89.5 parts by weight, crystalline polyester resin (weight average molecular weight Mw: 10,000, melting point: 70 ° C. ) A cyan toner (8) having a volume average particle size of 6.5 μm, a fine powder side particle size distribution of 1.21, a shape factor of 120, and a volume average in the same manner as in the production of the base toner 2 except that 46.5 parts by weight were used. Magenta toner (8) having a particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, yellow toner (8) having a volume average particle size of 6.5 μm, fine powder side particle size distribution 1.21, shape factor 120, A black toner (8) having a volume average particle size of 6.5 μm, a fine particle size particle size distribution of 1.21, and a shape factor of 120 was obtained.

<Example 1>
[Manufacture of external additive toner A]
Next, 1.3 parts by weight of hexamethyldisilazane-treated silicon oxide particles (X24, manufactured by Shin-Etsu Chemical Co., Ltd.) having a volume average particle size of 120 nm and titanium oxide having a volume average particle size of 20 nm (MT150AW, Taker) are added to 100 parts by weight of the base toner (1). Externally added toner A was prepared by mixing 1.5 parts by weight of particles treated with 20% decyltrimethoxysilane by a sample mill.

[Manufacture of carrier A]
Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125) 100 parts by weight Toluene 14 parts by weight Cyclohexyl methacrylate / dimethylaminoethyl methacrylate copolymer (copolymerization weight) Ratio 99: 5, Mw 80,000) 2.0 parts by weight Carbon black (# 25, manufactured by Mitsubishi Chemical Corporation) 0.12 parts by weight The above components excluding ferrite particles and glass beads (φ1 mm, equivalent to toluene) were added to Kansai Paint Co., Ltd. The resulting mixture was stirred at 1200 rpm for 30 minutes using a sand mill, to obtain a resin coating layer forming solution. Further, this resin coating layer forming solution, 0.5 part by weight of vinyltrimethoxysilane and ferrite particles were placed in a vacuum degassing kneader and stirred at 5 rpm for 120 minutes while maintaining a temperature of 60 ° C., then 0.080 MPa The resin-coated carrier A was formed by drying at 150 ° C. for 150 minutes and gradually distilling off toluene. The BET specific surface area of Carrier A was 0.38 m ² / g.

[Adjustment of Developer A]
Developer A was obtained by stirring 8 parts by weight of externally added toner A and 100 parts by weight of carrier A with a V-blender for 20 minutes at 40 rpm and sieving with a sieve having an opening of 212 μm. Table 1 shows the properties of the developer.

[Evaluation]
Using the developer thus obtained, the following printing test was performed with a modified machine in which the cleaning brush of DocuPrint C1616 manufactured by Fuji Xerox Co., Ltd. was removed. This print test is a pattern having three color images of 7.5 cm × 7.5 cm yellow, magenta, and cyan under the high temperature and high humidity (28 ° C., 85% RH) at a distance of 5 cm from the front edge of the A4 paper. After printing, a pattern having 10,000 color images of only black toner, followed by a three-color image of 7.5 cm × 7.5 cm yellow, magenta, and cyan underneath the A4 paper section at 5 cm. And evaluated the items of density, density unevenness, and white paper portion color point by the following evaluation method. The color developing machine was driven during 10,000 black images.

(Concentration evaluation method)
The image density after printing one sheet and the image density after 10,000 printing were measured by X-rite 938. The image density was measured at 10 random points, and the average value was obtained. Tables 2 to 8 show the evaluation results.

(Evaluation method for uneven density)
The image density after printing one sheet and the image density after 10,000 printing were measured by X-rite 938. The image density was measured at 10 points at random, and the difference between the maximum value and the minimum value was obtained. Table 1 shows the results.

(Blank paper color point evaluation method)
After printing one sheet and after printing 10,000 sheets, A4 blank paper was output, and the number of color points was measured visually. The obtained evaluation results are shown in Tables 2-8.

  Further, using the developer thus obtained, the following printing test was performed at a fixing temperature of 140 ° C. using a modified DocuCentreColor f450 manufactured by Fuji Xerox Co., Ltd. This printing test has four color images of 7.5 cm × 7.5 cm of yellow and magenta at a temperature of 5 cm from the front edge of A4 paper, and cyan and black under the low temperature and low humidity (10 ° C., 15% RH). Output as a pattern. After copying 10 sheets (initial), after copying 10,000 sheets or during copying, the following evaluation methods are used to evaluate the white spot in the image area, missing the trailing edge of the high density image, and reducing the trailing edge density of the intermediate density area. The items were evaluated.

(White point evaluation method)
The number of white spots in the image area at the time of printing 10 sheets (initial) and at the time of printing 10,000 sheets was counted. The obtained evaluation results are shown in Tables 2-8.

(Lack of trailing edge of high density image)
The trailing edge chipping of the image portion at the time of printing 10 sheets (initial) and at the time of printing 10,000 sheets was determined according to the following criteria.
A: No chip at the rear end of the image is observed. O: A chip at the rear end of the image can be confirmed with a magnifying glass at a magnification of 50. Δ: A chip at the rear end of the image can be confirmed from an angle. Can be confirmed from 30cm

(Middle density image trailing edge missing)
The image shown in FIG. 2 was output after 10 sheets were printed (initial stage) and after 10,000 sheets were printed, and the white length t (mm) was measured with a 50 × magnifier with a scale.

<Example 2>
[Production of Externally Added Toner B]
Externally added toner B and developer B were prepared in the same manner as in Example 1 except that the base toner (2) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 3>
[Production of Externally Added Toner C]
Externally added toner C and developer C were prepared in the same manner as in Example 1 except that the base toner (3) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 4>
[Production of Externally Added Toner D]
Externally added toner D and developer D were prepared in the same manner as in Example 1 except that the base toner (4) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 5>
[Production of Externally Added Toner E]
Externally added toner E and developer E were produced in the same manner as in Example 1 except that the base toner (5) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 6>
[Manufacture of externally added toner F]
Externally added toner F and developer F were produced in the same manner as in Example 1 except that the base toner (6) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 7>
[Manufacture of externally added toner G]
Externally added toner G and developer G were prepared in the same manner as in Example 1 except that the base toner (7) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 8>
[Production of Externally Added Toner H]
Externally added toner H and developer H were produced in the same manner as in Example 1 except that the base toner (8) was used instead of the base toner (1). Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 9>
[Production of Externally Added Toner I]
Example 1 was used except that hexamethyldisilazane-treated silicon oxide particles (X24, manufactured by Shin-Etsu Chemical Co., Ltd.) having a volume average particle size of 105 nm were used in place of the hexamethyldisilazane-treated silicon oxide particles having a volume average particle size of 120 nm. Thus, externally added toner I and developer I were prepared. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 10>
[Manufacture of external toner J]
In the same manner as in Example 1 except that PMMA particles (MP116, manufactured by Soken Chemical Co., Ltd.) having a volume average particle size of 300 nm were used instead of the hexamethyldisilazane-treated silicon oxide particles having a volume average particle size of 120 nm, external toner J Developer J was prepared. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 11>
[Manufacture of externally added toner K]
Toner K added in the same manner as in Example 1 except that PMMA particles having a volume average particle size of 150 nm (MP1451, manufactured by Soken Chemical) were used in place of the hexamethyldisilazane-treated silicon oxide particles having a volume average particle size of 120 nm. Developer K was prepared. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 12>
[Manufacture of externally added toner L]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) External additive toner L, carrier L, and developer L were prepared in the same manner as in Example 1 except that 0.13 m ² / g, SF1 125) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 13>
[Manufacture of externally added toner M]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) Externally added toner M, carrier M, and developer M were prepared in the same manner as in Example 1 except that 0.25 m ² / g, SF1 125) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 14>
[Manufacture of externally added toner N]
Externally added toner N, carrier N, and developer N were prepared in the same manner as in Example 1 except that the degree of reduced pressure was 0.093 MPa in the production of carrier A. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 15>
[Manufacture of externally added toner O]
Externally added toner O, carrier O, and developer O were produced in the same manner as in Example 1 except that the degree of reduced pressure was 0.071 MPa in the production of carrier A. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 16>
[Manufacture of externally added toner P]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) Externally added toner P, carrier P and developer P were prepared in the same manner as in Example 1 except that 0.15 m ² / g, SF1 105) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 17>
[Manufacture of externally added toner Q]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) Externally added toner Q, carrier Q, and developer Q were prepared in the same manner as in Example 1 except that 0.15 m ² / g, SF1 130) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Example 18>
[Production of Externally Added Toner R]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) External additive toner R, carrier R, and developer R were prepared in the same manner as in Example 1 except that 0.15 m ² / g, SF1 135) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative Example 1>
[Manufacture of external toner S]
Externally added toner S and developer S were used in the same manner as in Example 1 except that 1.3 parts by weight of hexamethyldisilazane-treated silicon oxide particles (X24, manufactured by Shin-Etsu Chemical Co., Ltd.) having a volume average particle size of 120 nm were not used. Produced. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative example 2>
[Production of Externally Added Toner T]
The same procedure as in Example 1 was performed except that hexamethyldisilazane-treated silicon oxide particles having a volume average particle size of 100 nm (X24, manufactured by Shin-Etsu Chemical Co., Ltd.) were used instead of the hexamethyldisilazane-treated silicon oxide particles having a volume-average particle size of 120 nm. Thus, externally added toner T and developer T were prepared. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative Example 3>
[Manufacture of externally added toner U]
In the same manner as in Example 1 except that PMMA particles having a volume average particle size of 350 nm (MP2701, manufactured by Soken Chemical) were used instead of the hexamethyldisilazane-treated silicon oxide particles having a volume average particle size of 120 nm, external toner U Developer U was prepared. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative example 4>
[Manufacture of Externally Added Toner V]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) External additive toner V, carrier V, and developer V were prepared in the same manner as in Example 1 except that 0.12 m ² / g, SF1 125) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative Example 5>
[Manufacture of externally added toner W]
Instead of Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area 0.15 m ² / g, SF1 125), Mn—Mg—Sr ferrite particles (volume average particle size 40 μm, BET specific surface area) External additive toner W, carrier W, and developer W were prepared in the same manner as in Example 1 except that 0.26 m ² / g, SF1 125) was used. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative Example 6>
[Manufacture of externally added toner X]
Externally added toner X, carrier X, and developer X were produced in the same manner as in Example 1 except that the degree of reduced pressure was 0.094 MPa in the production of carrier A. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative Example 7>
[Production of Externally Added Toner Y]
Externally added toner Y, carrier Y, and developer Y were produced in the same manner as in Example 1 except that the degree of vacuum was 0.070 MPa in the production of carrier A. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

<Comparative Example 8>
[Manufacture of externally added toner Z]
In the production of carrier A, the externally added toner Z was prepared in the same manner as in Example 1 except that the cyclohexyl methacrylate / dimethylaminoethyl methacrylate copolymer was changed to a styrene-methacrylate copolymer (copolymerization weight ratio 65/35). , Carrier Z and developer Z were prepared. Table 1 shows the properties of the developer. Tables 2 to 8 show the evaluation results.

  As described above, by using the developers of Examples 1 to 18, even when a specific color toner, such as a color output system, is not used for a long period of time, transferability can be maintained. A clear image with almost no color point due to poor charging and almost no deterioration in image quality over a long period of time even under high temperature and high humidity could be obtained. Further, by using the developer of Examples 2 to 8 containing a crystalline resin in the toner, the image density at the trailing edge of the high-density patch image (relative to the image traveling direction) becomes low even under low temperature and low humidity. It was possible to obtain a clear image with almost no image defect called a starvation or a starvation in which the image density at the rear end of the intermediate density portion having a high density portion is reduced.

1 is a schematic diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. It is a figure explaining the white-out image defect in evaluation of the Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Image forming apparatus, 10 charging part, 12 exposure part, 14 electrophotographic photosensitive member, 16 developing part, 18 transfer part, 20 cleaning part, 22 fixing part, 24 to-be-transferred body.

Claims (7)

A toner containing at least one external additive having a volume average particle size of 105 nm or more and 300 nm or less;
And a resin coating layer coating the core particles with the core particle surface, coating the BET specific surface area A of the core particles is in the range of less 0.13 m ² / g or more 0.25 m ² / g, which is the coating a carrier in the range difference (B-a) is 0.03 m ² / g or more 0.40m in ² / g or less and a BET specific surface area a BET specific surface area B and the core particles of the particles,
A developer for developing an electrostatic charge image, comprising: The developer for developing an electrostatic charge image according to claim 1,
A developer for developing an electrostatic charge image, wherein the toner contains a crystalline resin. The developer for developing an electrostatic charge image according to claim 2,
A developer for developing an electrostatic charge image, wherein the content of the crystalline resin is in the range of 3 wt% to 30 wt%. The developer for developing an electrostatic charge image according to claim 3,
A developer for developing an electrostatic charge image, wherein the content of the crystalline resin is in the range of 5 wt% to 15 wt%. The electrostatic charge image developing developer according to any one of claims 1 to 4,
A developer for developing an electrostatic charge image, wherein a volume average particle diameter of the external additive is in a range of 120 nm to 200 nm. A developer for developing an electrostatic image according to any one of claims 1 to 5,
The electrostatic charge image developing developer, wherein the carrier has a shape factor in the range of 100 to 130. An image carrier, a latent image forming unit that forms an electrostatic latent image on the surface of the image carrier, a developing unit that develops the electrostatic latent image using a developer to form a toner image, and the development And a transfer means for transferring the toner image to the transfer body,
The image forming apparatus according to claim 1, wherein the developer is the developer for developing an electrostatic image according to claim 1.

Images