JP2009151066A - Electrophotographic carrier, electrophotographic two-component developer and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carrier which allows a coating layer on a carrier core material surface to obtain a desired resistance value, can prevent scraping or peeling of the coating layer resulting from stress by long-term agitation and suppress reduction in resistance or color contamination, and further has excellent charging capacity to toner. <P>SOLUTION: The electrophotographic carrier includes a coating layer containing at least a binder resin and conductive fine particles, which is provided on a surface of magnetic core material particle. The carrier includes as the conductive fine particles, carbon fibers having an aspect ratio ranging from 10 to 50. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic carrier (electrostatic latent image developing carrier) suitably used for electrophotographic methods, electrostatic recording methods, electrostatic printing methods and the like, a developer using the carrier, and the developer The present invention relates to an image forming method using.

  The dry development method used in electrophotography is a method of forming a visible image by electrostatically attaching toner rubbed with a charging member to an electrostatic latent image on an electrostatic latent image carrier. is there. Such dry development methods include (i) a so-called one-component development method in which toner is used without using a carrier, and (ii) glass beads, a magnetic carrier, or a surface thereof coated with a resin or the like. There is a so-called two-component development system in which a mixed carrier and toner are used.

  In the two-component developing system, a two-component developing device having a developing sleeve that is a cylindrical developer carrying member that is normally provided with a magnet roller composed of a magnet body having a plurality of magnetic poles therein and is rotatably supported. Is used. In this system, the above-described apparatus is used, and the two-component development is performed by carrying the electrostatic latent image developing carrier having the toner attached to the surface of the developing sleeve to a developing area that is opposite to the image carrier. Development is performed with a magnetic brush made of an agent. As described above, in the two-component development method, charging is performed by stirring and mixing the carrier for developing an electrostatic latent image and the toner, so that the chargeability of the toner is stable and a relatively stable good image can be obtained. .

  As described above, the two-component developer is repeatedly used while replenishing the toner consumed by the development. For this reason, with regard to the carrier, the toner component is prevented from being spent on the carrier surface, the formation of a uniform carrier surface, the prevention of surface oxidation, the prevention of deterioration of various physical properties due to the decrease in moisture sensitivity, the extension of the developer life, The carrier core is usually hardened by coating it with an appropriate resin material for the purpose of preventing carrier adhesion, protecting the photoconductor from scratches or abrasion by the carrier, controlling the charge polarity, or adjusting the charge amount. A high-strength coating layer is provided (see Patent Documents 1 to 16).

  On the other hand, in recent years, conductive fine particles have been used as coating resistance modifiers. However, when the conductive fine particles are contained in a state where the individual fine particles are dispersed as in the conventional case, it is difficult to secure a conductive path. Therefore, an excessive amount of the conductive fine particles must be included in order to obtain a desired resistance. However, there is a problem that the viscosity of the coating layer increases and the core material cannot be uniformly coated, or the strength of the coating layer is lowered even if a desired resistance value is obtained. On the other hand, as in Patent Document 17, an invention of a carrier characterized by containing not only spherical fine particles as a resistance adjusting agent but carbon nanotubes having a very large aspect ratio of about 1000 or more is disclosed. Yes.

  According to such an invention, even when the core particles are coated with the insulating coating layer, the carbon nanotubes having a large aspect ratio can efficiently form a conductive circuit with a small addition amount and have a desired resistance. Can be obtained. However, it is very difficult to uniformly disperse carbon nanotubes having a very small outer diameter of several nanometers to several tens of nanometers and an extremely large aspect ratio of about 1000 or more in the coating layer. Has poor adhesion to the binder resin constituting the coating layer. For this reason, a coating layer with insufficient dispersibility of carbon nanotubes is formed, and agitation stress associated with long-term use causes agglomeration of carbon nanotubes to be detached from the coating layer, resulting in image staining. Not reached.

  On the other hand, Patent Document 18 proposes to use a carbon nanotube whose surface is treated with a coupling agent to improve dispersibility in a binder resin. According to such an invention, a coating layer with good dispersibility can be formed by coupling the carbon nanotubes. However, when a material having a very large aspect ratio such as a carbon nanotube is introduced into the coating layer, the material is easily introduced so that the long axis of the nanotube is horizontal to the coating layer. Further, the average fiber diameter of carbon nanotubes with respect to the thickness of the carrier coating layer is not taken into consideration. For this reason, as the resistance of the carrier, the surface resistance tends to decrease more than the volume resistance, and this tendency is not very favorable for the image quality.

  As described above, no means for simultaneously satisfying items such as resistance adjustment of carrier particles, reduction of film abrasion of the coating layer, and prevention of color stains has been presented, and further improvement is required. It is.

JP 58-108548 A JP 54-1555048 A JP 57-40267 A JP 58-108549 A JP 59-166968 A Japanese Patent Publication No. 1-19584 Japanese Examined Patent Publication No. 3-628 JP-A-6-202381 JP-A-5-273789 JP-A-9-160304 JP-A-8-6307 Japanese Patent No. 2683624 Japanese Patent No. 3600219 Japanese Patent No. 3737060 JP 2004-226784 A JP 2002-287431 A JP 2007-94402 A JP 2006-91381 A

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is, according to the present invention, the coating layer on the surface of the carrier core material obtains a desired resistance value, prevents the coating layer from being scraped or peeled off due to stress caused by long-term stirring, and suppresses the decrease in resistance and the occurrence of color stains. Another object of the present invention is to provide a carrier having an excellent charge imparting ability for toner.

  As a result of intensive studies in view of the above problems, the present inventors have obtained the following knowledge. That is, the knowledge that the inclusion of carbon fibers as conductive fine particles in the coating layer of the carrier has the effect of efficiently reducing the resistance of the carrier and obtaining a desired resistance value, It is a finding that by defining the aspect ratio, the carbon fibers are uniformly dispersed in the coating layer, and the effect of suppressing the occurrence of color stains due to the detachment of the carbon fibers from the coating layer is brought about. Further, in addition to these, it is a finding that the above-mentioned effect can be further improved by defining the relationship of the average fiber diameter of the carbon fiber to the thickness of the coating layer.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows.
(1) In an electrophotographic carrier in which a coating layer containing at least a binder resin and conductive fine particles is provided on the surface of magnetic core material particles,
An electrophotographic carrier comprising carbon fibers having an aspect ratio of 10 or more and 50 or less as the conductive fine particles.
(2) The electrophotographic carrier according to (1), wherein the carbon fiber is made of amorphous carbon.
(3) The carrier for electrophotography according to (1), wherein the carbon fiber has a structure in which graphene sheets are stacked vertically or inclined in a fiber axis direction of the carbon fiber.
(4) When the average fiber diameter of the carbon fiber is d and the thickness of the coating layer is w, the relationship of the following formula (1) is satisfied. An electrophotographic carrier according to claim 1.
0.04 ≦ d / w ≦ 0.6 (1)
(5) The electrophotographic carrier according to any one of (1) to (4), wherein the carbon fiber has an average fiber diameter of 100 to 500 nm.
(6) The electrophotographic carrier according to any one of (1) to (5), wherein the binder resin contains a silicone resin.
(7) The electrophotographic carrier according to any one of (1) to (6), wherein the binder resin contains an acrylic resin.
(8) The electrophotographic carrier according to any one of (1) to (7), wherein the coating layer contains an aminosilane coupling agent.
(9) The volume resistivity in the unit of [log (Ω · cm)] when a DC voltage of 1000 V is applied to the electrophotographic carrier is 10 or more and 16 or less. (8) The electrophotographic carrier according to any one of (8).
(10) The electrophotographic carrier according to any one of (1) to (9), wherein the electrophotographic carrier has a volume average particle diameter of 20 to 65 μm.
(11) A two-component developer for electrophotography comprising the carrier according to any one of (1) to (10) and a toner.
(12) At least an electrostatic latent image forming step for forming an electrostatic latent image on the electrostatic latent image carrier, and the electrostatic latent image can be developed using the developer described in (11). An image is obtained through a development process for forming a visual image, a transfer process for transferring the visible image to a recording medium, and a fixing process for fixing the transfer image transferred to the recording medium. It is a forming method.

  According to the present invention, in an electrophotographic carrier having a coating layer composed of at least a binder resin and conductive fine particles, carbon fibers having an aspect ratio of 10 to 50 are contained in the carrier coating layer as conductive fine particles. Thus, the resistance of the coating layer, which is an insulating layer, efficiently decreases, has a desired resistance value, and the electrophotographic carrier in which the occurrence of color contamination due to the detachment of conductive fine particles from the coating layer is suppressed, and It is possible to provide a two-component developer comprising the carrier and toner and capable of forming an image with a high image density without toner scattering and background contamination, and an image forming method using the developer.

  The materials constituting the electrophotographic carrier of the present invention will be described. Note that it is easy for a person skilled in the art to change or modify the present invention within the scope of the claims to form other embodiments, and these changes and modifications are included in the scope of the claims, The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.

(Career)
―Carrier core material―
The core material of the carrier is not particularly limited as long as it is a magnetic particle. Manganese ferrite, manganese-magnesium ferrite, manganese-strontium ferrite, manganese-magnesium-strontium ferrite, copper-zinc ferrite, lithium ferrite Known ferrites such as can be used.
In addition, for the purpose of controlling the core material resistance and the purpose of improving the production stability, as other constituent materials of the core material, for example, Li, Na, K, Ca, Ba, Y, Ti, Zr, V, Ag One or more elements such as Ni, Cu, Zn, Al, Sn, Sb, and Bi may be blended. The amount of these elements is preferably 5 atomic% or less, more preferably 3 atomic% or less, based on the total amount of metal elements.

―Binder resin―
The binder resin for forming the coating layer of the carrier is not particularly limited. For example, polyolefin (for example, polyethylene, polypropylene, etc.) and modified products thereof, styrene, acrylic resin, acrylonitrile, vinyl acetate, vinyl alcohol, chloride Crosslinkable copolymers containing vinyl, vinyl carbazole, vinyl ether, etc .; silicone resins composed of organosiloxane bonds or modified products thereof (for example, modified products with alkyd resin, polyester resin, epoxy resin, polyurethane, polyimide, etc.); polyamide; polyester Polyurethane, polycarbonate, urea resin, melamine resin, benzoguanamine resin, epoxy resin, ionomer resin, polyimide resin, and derivatives thereof.

  Above all, acrylic resin has strong adhesion to the core material and fine particles contained in the coating layer and has low brittleness, so it has very good properties against peeling of the coating layer and keeps the coating layer stable. In addition, the particles contained in the coating layer such as conductive particles can be firmly held. In particular, a powerful effect can be exhibited in holding particles having a particle size larger than the coating layer thickness. Furthermore, as this acrylic resin, that whose glass transition temperature (Tg) is 20-100 degreeC is preferable, and what is 25-80 degreeC is more preferable. By setting the Tg of the resin within this range, it is considered that the binder resin has an appropriate elasticity and reduces the impact received by the carrier when the developer is triboelectrically charged, thereby preventing damage to the coating layer.

In addition, by using a cross-linked product of an acrylic resin and an amino resin as a binder resin that forms a coating layer, fusion between resins that tend to occur when using an acrylic resin alone, while maintaining appropriate elasticity, Since so-called blocking can be prevented, it is even more preferable.
As the amino resin, conventionally known amino resins can be used, and among them, guanamine and melamine can be used more preferably because the charge imparting ability of the carrier can be improved.

  Further, when it is necessary to appropriately control the charge imparting ability of the carrier, guanamine and / or melamine may be used in combination with another amino resin. As such an acrylic resin that can be cross-linked with an amino resin, an acrylic resin having a hydroxyl group or a carboxylic acid group can be used. In particular, adhesion to a core material or conductive fine particles is improved, and dispersion of conductive fine particles described later is performed. From the viewpoint of improving the properties, those having a hydroxyl group are more preferably used. The hydroxyl value at this time is preferably 10 or more, more preferably 20 or more.

Furthermore, since the binder resin contains a silicone moiety as a structural unit, the surface energy itself of the carrier surface can be lowered and the generation of toner spent itself can be suppressed. Can be maintained.
The constitutional unit of the silicone moiety preferably contains at least one of a methyltrisiloxane unit, a dimethyldisiloxane unit, and a trimethylsiloxane unit, and the silicone portion may be chemically bonded to another coat layer resin. It may be in a blended state or may be a multilayer.
In the case of a blend or multilayer structure, it is preferable to use a silicone resin and / or a modified product thereof. In particular, by including a silicone resin composition having at least the structural unit represented by Chemical Formula 1, Problems such as specific wear, wear and desorption of other resins can be suppressed.

(In Formula (Chemical Formula 1), R ^{1 to} R ³ may be the same or different hydrocarbon groups and / or derivatives thereof, X ¹ is a condensation reactive group, and a and b represent integers.)
Examples of the condensation reactive group X ¹ include a hydroxyl group, an alkoxy group, and a methyl ethyl ketoxime group. A condensation reaction occurs at the site due to moisture or heating in the atmosphere, and a three-dimensional network structure can be obtained.
Examples of these silicone resins include straight silicone resins having only the organosiloxane bond having the structural unit represented by (Chemical Formula 1), and silicone resins modified with alkyd, polyester, epoxy, acrylic, urethane, and the like.
Examples of the straight silicone resin include trade names KR271, KR272, KR282, KR252, KR255, KR152 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), SR2400, SR2405, SR2406 (above, manufactured by Toray Dow Corning Silicone). Specific examples of the modified silicone resin include epoxy-modified product: ES-1001N, acrylic-modified silicone: KR-5208, polyester-modified product: KR-5203, alkyd-modified product: KR-206, and urethane-modified product: KR-. 305 (above, manufactured by Shin-Etsu Chemical Co., Ltd.), epoxy modified product: SR2115, alkyd modified product: SR2110 (above, manufactured by Toray Dow Corning Silicone Co., Ltd.) and the like.
The silicone resin can be used alone, but a crosslinking reactive component, a charge amount adjusting component, and the like can be used at the same time. Examples of the crosslinking reactive component include a silane coupling agent. Examples of the silane coupling agent include methyltrimethoxysilane, methyltriethoxysilane, octyltrimethoxysilane, aminosilane coupling agent, and the like.
As said aminosilane coupling agent, what is represented by a following formula (Formula 2) is suitable. 0.001 mass%-30 mass% are preferable, and, as for content of this aminosilane coupling agent which occupies for a coating layer, 0.001 mass%-15 mass% are more preferable. By containing the aminosilane coupling agent in the coating layer, the stability of the carrier over time is improved and the durability is improved. Accordingly, the coating layer used in the electrophotographic carrier of the present invention is preferably a layer obtained using an aminosilane coupling agent as a crosslinking reactive component.

  The acrylic resin and the silicone resin may be contained in the binder resin layer in a form having a chemical bond with each other. As this method, a method of copolymerizing a monomer having a methacryl group at one end of a silicone skeleton represented by the formula (Chemical Formula 1) as a macromonomer with a monomer constituting the acrylic resin, a silicone having a mercapto group, Examples include, but are not limited to, a method of copolymerizing an acrylic monomer, a method of obtaining an acrylic resin having an alkoxysilyl group by reacting the alkoxysilyl group with the condensation reaction group of the silicone resin, and the like. Examples of the binder resin in which acrylic and silicone are copolymerized include, for example, silicone grafts such as X-22-8004, X22-8212, X22-8195X, and X-24-798A manufactured by Shin-Etsu Chemical Co., Ltd. An acrylic resin etc. are mentioned.

―Conductive fine particles―
In the present invention, the component constituting the coating layer includes conductive fine particles in addition to the binder resin, and the conductive fine particles include carbon fibers having at least an aspect ratio of 10 to 50.

  Here, the “carbon fiber” in the present invention is a graphite hexagonal mesh plane having an aspect ratio in a range of about 10 to about 50, preferably an average fiber diameter in a range of about 80 nm to about 1 μm. Fibrous material (hollow type) in which layers formed by rounding are laminated, or a material (graphite type) having a structure in which a graphite hexagonal mesh plane is laminated vertically or inclined to the fiber axis direction of the fiber, or Amorphous carbon fiber material (amorphous type). “Carbon nanotubes” are substances having an average fiber diameter of several tens of nanometers or less, small ones of 1 nm or less, and a very high aspect ratio having an aspect ratio of about 100 to about 10,000. . In addition, the “carbon fiber” in the present invention is clearly different from the structure formed by bonding the carbon black particles, and can be distinguished by observation using an electron microscope.

  When the aspect ratio of the carbon fiber is less than 10, it is difficult to form a conductive path in the coating layer, and the resistance of the carrier cannot be efficiently lowered to a desired value by adding a small amount. On the other hand, if it exceeds 50, the dispersibility of the carbon fiber is greatly deteriorated, and it becomes difficult to uniformly disperse in the coating layer, and aggregates are likely to be formed. When layer wear or delamination occurs, the degree of color smear increases. Furthermore, the long axis of the carbon fiber is easily introduced so as to be horizontal with respect to the coating layer, and as the resistance of the carrier, the surface resistance tends to be lower than the volume resistance, and the charging characteristics of the carrier are poor. Become.

The carbon fiber is made of amorphous carbon (amorphous type: formed by spinning a polymer fiber spun at a high temperature and carbonized), or graphite is laminated vertically or inclined to the fiber axis direction. A structure having the above structure (graphite type: a structure in which graphene sheets are laminated perpendicularly to the fiber axis direction or a structure in which the graphene sheets are inclined in the fiber axis direction) is particularly preferable.
When the carbon fiber is made of amorphous carbon, it has excellent strength as a fiber, and is excellent in dispersibility and interfacial adhesion to a resin, so that a coating layer having high strength and a uniform composition can be obtained.
When the carbon fiber has a structure in which a graphite mold is laminated perpendicularly or inclined to the fiber axis direction of the carbon fiber, the end face of the crystal is different from that of a structure in which graphite is oriented parallel to the fiber axis direction. It is exposed on the fiber surface, and it is easy to obtain a coating layer with good dispersibility in the coating layer and a uniform composition. In addition, when the coating layer wears or peels off due to stress such as agitation during long-term use, it is easy to cut or peel between the graphite layers, reducing the degree of color stains without detaching as a large lump. can do.
Examples of such a graphite-type structure include a structure in which graphene sheets are stacked vertically or inclined in the fiber axis direction of the carbon fiber. In the graphene sheet, carbon planes arranged so as to cover regular hexagons formed by covalently bonding carbon atoms to each other by sp ² hybrid orbitals maintain a distance of about 3.35 mm (1 cm = 10 ⁻¹⁰ m) from each other. It is a structure made up of individual carbon planes that make up the graphite that is laminated. In the present invention, a structure in which a graphene sheet is wound in a cylindrical shape and the inside of the cylinder is hollow (a graphene sheet is wound in multiple layers) can also be used.
Examples of the method for producing graphite-type carbon fiber include a method obtained by reacting ethylene, acetylene or the like at about 500 ° C. as a reaction gas by a thermal CVD method using GN-CVD-300 manufactured by ULVAC. .

The carrier of the present invention more preferably satisfies the relationship of the following formula (1), where d is the average fiber diameter of the carbon fibers and w is the thickness of the coating layer.
0.04 ≦ d / w ≦ 0.6 (1)
When the ratio of the average fiber diameter of the carbon fiber to the thickness of the coating layer is less than 0.04, the fiber diameter of the carbon fiber is too small with respect to the thickness of the coating layer, so that the conductive path is efficiently formed. In addition, the carrier resistance cannot be efficiently lowered to a desired value by adding a small amount. On the other hand, if it exceeds 0.6, the fiber diameter of the carbon fiber is too large with respect to the thickness of the coating layer, so the smoothness of the surface of the coating layer is significantly impaired and the wear resistance of the coating layer is reduced. The life of the carrier is shortened, and when the coating layer is worn or peeled off due to stress such as stirring during long-term use, the degree of color contamination increases.

  The thickness of the coating layer is preferably 0.1 to 5 μm, and more preferably 1 to 3 μm.

The average fiber diameter of the carbon fiber is preferably 100 to 500 nm, and more preferably 200 nm to 500 nm.
If the average fiber diameter of the carbon fiber is less than 100 nm, the conductive path cannot be formed efficiently because the coating layer is too small, and the carrier resistance can be reduced to a desired value by adding a small amount. It cannot be lowered efficiently. In addition, the dispersibility of the carbon fiber is deteriorated, and it is difficult to uniformly disperse the carbon fiber in the coating layer, so that an agglomerate is easily formed. When this happens, the degree of color smear increases. On the other hand, if the thickness exceeds 500 nm, the coating layer surface is too large, so that the smoothness of the coating layer surface is impaired, the wear resistance of the coating layer is reduced, the life of the carrier is shortened, and When the coating layer is worn or peeled off due to stress such as stirring during use, the degree of color stain increases.

  Regarding the average fiber diameter and aspect ratio of the carbon fiber, for example, using a scanning electron microscope or a transmission electron microscope, observe the filling portion of the carbon fiber on the carrier surface or the coating layer of the carrier split section, and image It can be obtained by performing analysis and statistical processing. This value is calculated by measuring 100 or more particles.

The electric resistance of the carbon fiber is preferably 1 × 10 ³ Ω · cm ( ^{3 in} terms of a common logarithm of resistance [log (Ω · cm)]) or less, preferably 1 × 10 ¹ Ω · cm (resistance It is more preferable that the value is 1) or less in the common logarithm value [log (Ω · cm)].
When the electric resistance of the carbon fiber is larger than 1 × 10 ³ Ω · cm, the carrier resistance cannot be efficiently lowered to a desired value by adding a small amount.

  The content of the carbon fiber is appropriately selected depending on the material constituting the coating layer, the film thickness, and the desired resistance value, but is preferably in the range of 1 to 20% by mass of the entire coating layer, and more preferably Is in the range of 1-10% by weight. If it is less than 1% by mass, the resistance of the carrier cannot be lowered sufficiently. Conversely, if it exceeds 20% by mass, the color of the coating layer may be deteriorated when the coating layer is worn or peeled off due to stress such as stirring during long-term use. The degree of contamination increases.

―Fine particles―
In addition to the conductive fine particles, fine particles may be added to the coating layer as necessary. The fine particles are not particularly limited and can be appropriately selected from known ones used for carriers for electrophotographic two-component developers according to the purpose. Examples thereof include silicon oxide, titanium oxide, and alumina. Inorganic fine particles such as metal oxide particles are preferably used. These fine particles can be easily obtained with a uniform fine particle size, and are effective in improving the mechanical strength of the coating layer. The particle diameter of such fine particles is 5 to 1000 nm. Moreover, as content of such microparticles | fine-particles, the range of 0-70 mass% of the whole coating layer is suitable, and the range of 10-50 mass% of the whole coating layer is more preferable.

  Moreover, there is no restriction | limiting in particular as a shape of the said microparticles | fine-particles (microparticles | fine-particles other than electroconductive fine particles), For example, spherical, plate shape, and needle shape can be taken.

―Coating layer dispersion―
In the present invention, a coating layer is formed on the surface of the core material particles using at least a coating layer dispersion obtained by dissolving or dispersing the binder resin and the conductive fine particles in a solvent. At this time, instead of the binder resin, a binder resin precursor such as a monomer constituting the binder resin, a macromonomer thereof, a binder resin with a reactive group, or the like may be used. The binder resin precursor adheres to the surface of the core particle, and then causes radical polymerization or polycondensation reaction by heating, a crosslinking agent, a polymerization initiator, etc., to give the binder resin having desired characteristics as a carrier coating layer. I can do it.

  Here, the solvent is not particularly limited as long as it dissolves or disperses the binder resin and / or binder resin precursor and the conductive fine particles. For example, n-hexane, cyclohexane, toluene, xylene, benzene Hydrocarbons such as methanol, ethanol, isopropanol, n-butanol, isobutanol, 3-methyl-3-methoxybutanol and the like, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, isophorone and other ketones, tetrachloride Carbon, methylene chloride, 1,2-dichloromethane, 1,1,2-trichloroethane, trichloroethylene, chloroform, monochlorobenzene, dichloromethylidene and other halogen-containing compounds, methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, cellosolve acetate Esters such as methyl ethyl ether, diethyl ether, ethyl cellosolve, butyl cellosolve, isopropyl cellosolve, ethers such as ethyl carbitol, acetonitrile, pyridine, nitrogen-containing compounds such as N-methylpyrrolidone, dimethylformamide, water, etc. This is not the case.

―Method of forming carrier coating layer―
As a method for forming the coating layer, a conventionally known method can be used, and a method in which the coating layer dispersion is applied to the surface of the core material particles by a spraying method, a dipping method or the like.
Furthermore, it is preferable to accelerate the polymerization reaction of the coating layer by heat-treating the carrier particles coated and formed in this way. The heat treatment may be performed subsequently in the coating apparatus after the coating layer is formed, or may be performed by another heating means such as a normal electric furnace or a firing kiln after the coating layer is formed.
Further, the heat treatment temperature varies depending on the coating layer resin to be used and is not generally determined, but is preferably about 120 to 350 ° C., and particularly preferably a temperature equal to or lower than the decomposition temperature of the coating layer resin. . The decomposition temperature of the coating layer resin is preferably an upper limit temperature up to about 220 ° C., and the heat treatment time is preferably about 5 to 120 minutes.

The volume resistivity of the carrier used in the present invention is 10 [log (Ω · cm)] or more and 16 [log (Ω · cm)] or less in the unit of volume resistivity [log (Ω · cm)]. Preferably there is. When the volume resistivity is less than 10 [log (Ω · cm)], carrier adhesion occurs in the non-image area. The so-called edge effect in which the image density at the edge portion is emphasized becomes remarkable, which is not preferable.
The volume resistivity can be arbitrarily adjusted within the above-described range by adjusting the thickness of the carrier coating layer and the content of the conductive fine particles as necessary.

Examples of the volume resistivity measuring method include a method of measuring using a device as shown in FIG. Specifically, the cell 33 made of a fluororesin container containing the electrodes 32a and 32b having a surface area of 2.5 cm × 4 cm and an electrode distance of 0.2 cm is filled with the carrier 33, and the drop height is 1 cm. Tapping speed: 30 times / min, tapping frequency: 10 times of tapping. Next, a DC voltage of 1000 V was applied between both electrodes, and the resistance value after 30 seconds was measured with a high resistance meter 4329A (manufactured by Yokogawa Hewlett-Packard Co., Ltd .: High Resistance Meter). Ω) can be calculated by the following equation to calculate the volume resistivity R.
R = log [r × (2.5 cm × 4 cm) ÷ 0.2 cm] [log (Ω · cm)]

The volume average particle size of the carrier used in the present invention is preferably in the range of 20 to 65 μm. If the thickness is less than 20 μm, carrier adhesion due to a decrease in the uniformity of the core material particles occurs, which is not preferable. If the thickness exceeds 65 μm, reproducibility of image details is poor and a fine image cannot be obtained.
The method for measuring the volume average particle size is not particularly limited as long as it is a device capable of measuring the particle size distribution, and can be measured using, for example, a microtrack particle size distribution meter (model HRA9320-X100).

(Developer)
The developer of the present invention is a two-component developer containing the carrier of the present invention and a toner.
The mixing ratio of the toner and the carrier in the developer is preferably 1.0 part by mass to 10.0 parts by mass of the toner with respect to 100 parts by mass of the carrier.
The toner includes at least a binder resin and a colorant, and further includes a release agent, a charge control agent, and other components as necessary.

<Toner>
The method for producing the toner is not particularly limited and may be appropriately selected depending on the intended purpose. It is a pulverization method, a suspension in which an oil phase is emulsified, suspended or aggregated in an aqueous medium to form toner base particles. Examples include a polymerization method, an emulsion polymerization method, and a polymer suspension method.

―Binder resin―
The binder resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, styrene such as polystyrene, poly-p-styrene, polyvinyltoluene, or a homopolymer of a substituted product thereof. Styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer Polymerization unit, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer Polymer, styrene-vinyl methyl ether copolymer, styrene-vinyl methyl ketone Copolymer, styrene-butadiene copolymer, styrene-isopropyl copolymer, styrene-copolymer such as styrene-maleic ester copolymer, polythyme methacrylate resin, polybutyl methacrylate resin, polyvinyl chloride resin , Polyvinyl acetate resin, polyethylene resin, polyester resin, polyurethane resin, epoxy resin, polyvinyl butyral resin, polyacrylic acid resin, rosin resin, modified rosin resin, terpene resin, phenol resin, aliphatic or aromatic hydrocarbon resin, aromatic Family petroleum resin. These may be used individually by 1 type and may use 2 or more types together.

―Colorant―
The colorant is not particularly limited and may be appropriately selected from known dyes and pigments according to the purpose. For example, carbon black, nigrosine dye, iron black, naphthol yellow S, Hansa yellow (10G, 5G, G), cadmium yellow, yellow iron oxide, ocher, yellow lead, titanium yellow, polyazo yellow, oil yellow, Hansa yellow (GR, A, RN, R), pigment yellow L, benzidine yellow (G, GR), Permanent Yellow (NCG), Vulcan Fast Yellow (5G, R), Tartrazine Lake, Quinoline Yellow Lake, Anthrazan Yellow BGL, Isoindolinone Yellow, Bengala, Lead Red, Lead Red, Cadmium Red, Cad Muum Mercury Red, Antimon Zhu, Permanent Red 4R, PA Red, Faise Red, Parachlor Ortho Nitroaniline Red, Resol Fast Scarlet G, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Red (F2R, F4R, FRL, FRLL, F4RH), Fast Scarlet VD, Belkan Fast Rubin B, Brilliant Scarlet G, Risor Rubin GX, Permanent Red F5R, Brilliant Carmine 6B, Pigment Scarlet 3B, Bordeaux 5B, Toluidine Maroon, Permanent Bordeaux F2K, Helio Bordeaux BL, Bordeaux 10B, Bon Maroon Light, Bon Maroon Medium, Eosin Lake B, Rhodamine Lake Y, Alizarin Lake, Thioindigo Red B, Thioindigo Maroon, Oh Lured, Quinacridone Red, Pyrazolone Red, Polyazo Red, Chrome Vermilion, Benzidine Orange, Perinone Orange, Oil Orange, Cobalt Blue, Cerulean Blue, Alkaline Blue Lake, Peacock Blue Lake, Victoria Blue Lake, Metal Free Phthalocyanine Blue, Phthalocyanine Blue, Fast Sky Blue, Indanthrene Blue (RS, BC), Indigo, Ultramarine Blue, Bitumen, Anthraquinone Blue, Fast Violet B, Methyl Violet Lake, Cobalt Purple, Manganese Purple, Dioxane Violet, Anthraquinone Violet, Chrome Green, Zinc Green, Oxidation Chrome, Pyridian, Emerald Green, Pigment Green B, Naphthol Green B, Green Gold, Ash Examples include degreen lake, malachite green lake, phthalocyanine green, anthraquinone green, titanium oxide, zinc white, and litbon. These may be used individually by 1 type and may use 2 or more types together.
The content of the colorant in the toner is preferably 1% by mass to 15% by mass, and more preferably 3% by mass to 10% by mass.

  The colorant may be used as a master batch combined with a resin. The resin is not particularly limited and may be appropriately selected from known ones according to the purpose. For example, styrene or a substituted polymer thereof, styrene copolymer, polymethyl methacrylate resin, polybutyl Methacrylate resin, polyvinyl chloride resin, polyvinyl acetate resin, polyethylene resin, polypropylene resin, polyester resin, epoxy resin, epoxy polyol resin, polyurethane, polyamide, polyvinyl butyral, polyacrylic acid resin, rosin, modified rosin, terpene resin, fat Aromatic hydrocarbon resin, alicyclic hydrocarbon resin, aromatic petroleum resin, chlorinated paraffin, paraffin and the like. These may be used individually by 1 type and may use 2 or more types together.

-Release agent-
There is no restriction | limiting in particular as said mold release agent, According to the objective, it can select suitably from well-known things, For example, waxes etc. are mentioned suitably.
Examples of the waxes include carbonyl group-containing waxes, polyolefin waxes, and long-chain hydrocarbons. These may be used individually by 1 type and may use 2 or more types together. Among these, a carbonyl group-containing wax is preferable.
Examples of the carbonyl group-containing wax include polyalkanoic acid esters, polyalkanol esters, polyalkanoic acid amides, polyalkylamides, dialkyl ketones, and the like. Examples of the polyalkanoic acid ester include carnauba wax, montan wax, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, and 1,18-octadecane. Examples thereof include diol distearate. Examples of the polyalkanol ester include tristearyl trimellitic acid and distearyl maleate. Examples of the polyalkanoic acid amide include dibehenyl amide. Examples of the polyalkylamide include trimellitic acid tristearylamide. Examples of the dialkyl ketone include distearyl ketone. Among these carbonyl group-containing waxes, polyalkanoic acid esters are particularly preferable.
Examples of the polyolefin wax include polyethylene wax and polypropylene wax.
Examples of the long chain hydrocarbon include paraffin wax and sazol wax.

There is no restriction | limiting in particular as melting | fusing point of the said mold release agent, Although it can select suitably according to the objective, 40 to 160 degreeC is preferable, 50 to 120 degreeC is more preferable, and 60 to 90 degreeC is further. preferable.
If the melting point is less than 40 ° C., the wax may adversely affect the heat-resistant storage stability, and if it exceeds 160 ° C., a cold offset may easily occur during fixing at a low temperature.
The melt viscosity of the release agent is preferably 5 cps to 1,000 cps, more preferably 10 cps to 100 cps, as a measured value at a temperature 20 ° C. higher than the melting point of the wax.
If the melt viscosity is less than 5 cps, the releasability may be lowered, and if it exceeds 1,000 cps, the effect of improving hot offset resistance and low-temperature fixability may not be obtained.

There is no restriction | limiting in particular as content in the said toner of the said mold release agent, Although it can select suitably according to the objective, 1 mass%-40 mass% are preferable, and 3 mass%-30 mass% are more preferable. .
When the content exceeds 40% by mass, the fluidity of the toner may be deteriorated.

―Charge control agent―
The charge control agent is not particularly limited, and a positive or negative charge control agent can be appropriately selected and used depending on whether the charge charged on the photoconductor is positive or negative.
As the negative charge control agent, for example, a resin or compound having an electron donating functional group, an azo dye, a metal complex of an organic acid, or the like can be used. Specifically, Bontron (product numbers: S-31, S-32, S-34, S-36, S-37, S-39, S-40, S-44, E-81, E-82, E -84, E-86, E-88, A, 1-A, 2-A, 3-A) (all manufactured by Orient Chemical Co., Ltd.); Kaya Charge (product numbers: N-1, N-2) Kaya Set Black (Part No .: T-2, 004) (all manufactured by Nippon Kayaku Co., Ltd.); Eisenspiron Black (T-37, T-77, T-95, TRH, TNS-2) (all Also manufactured by Hodogaya Chemical Co., Ltd.); FCA-1001-N, FCA-1001-NB, FCA-1001-NZ (all manufactured by Fujikura Chemical Co., Ltd.), and the like.
As the positive charge control agent, for example, a basic compound such as a nigrosine dye, a cationic compound such as a quaternary ammonium salt, a metal salt of a higher fatty acid, or the like can be used. Specifically, Bontron (part numbers: N-01, N-02, N-03, N-04, N-05, N-07, N-09, N-10, N-11, N-13, P -51, P-52, AFP-B) (all manufactured by Orient Chemical Co., Ltd.); TP-302, TP-415, TP-4040 (all manufactured by Hodogaya Chemical Co., Ltd.); Copy Blue PR , Copy charge (part numbers: PX-VP-435, NX-VP-434) (both manufactured by Hoechst); FCA (part numbers: 201, 201-B-1, 201-B-2, 201-B-3) , 201-PB, 201-PZ, 301) (all manufactured by Fujikura Kasei Co., Ltd.); PLZ (part numbers: 1001, 2001, 6001, 7001) (all manufactured by Shikoku Kasei Kogyo Co., Ltd.), and the like. .
These may be used individually by 1 type and may use 2 or more types together.

  The addition amount of the charge control agent is determined by the toner production method including the type of the binder resin and the dispersion method, and is not limited to a specific one. On the other hand, 0.1 mass part-10 mass parts are preferable, and 0.2 mass part-5 mass parts are more preferable. If the addition amount exceeds 10 parts by mass, the chargeability of the toner is too high, the effect of the charge control agent is reduced, the electrostatic attraction with the developing roller is increased, the developer fluidity is reduced, the image When the concentration is less than 0.1 part by mass, the charge rise property and the charge amount are not sufficient, and the toner image may be easily affected.

  In addition to the binder resin, the release agent, the colorant, and the charge control agent, the toner material includes inorganic fine particles, a fluidity improver, a cleaning property improver, a magnetic material, a metal soap, and the like as necessary. Can be added.

The inorganic fine particles are not particularly limited and can be appropriately selected according to the purpose. For example, silica, titania, alumina, cerium oxide, strontium titanate, calcium carbonate, magnesium carbonate, calcium phosphate, and the like can be used. It is more preferable to use silica fine particles hydrophobized with silicone oil or hexamethyldisilazane, or titanium oxide subjected to a specific surface treatment.
Examples of the silica fine particles include, for example, Aerosil (product numbers: 130, 200 V, 200 CF, 300, 300 CF, 380, OX50, TT600, MOX80, MOX170, COK84, RX200, RY200, R972, R974, R976, R805, R811, R812, T805, R202, VT222, RX170, RXC, RA200, RA200H, RA200HS, RM50, RY200, REA200) (all manufactured by Nippon Aerosil Co., Ltd.); HDK (Part No .: H20, H2000, H3004, H2000 / 4, H2050EP, H2015EP) , H3050EP, KHD50), HVK2150 (all manufactured by Wacker Chemical Co.); Cabozil (Part No .: L-90, LM-130, LM-150, M-5, PTG, MS) 55, H-5, HS-5, EH-5, LM-150D, M-7D, MS-75D, TS-720, TS-610, TS-530) (all manufactured by Cabot) Can do.
The addition amount of the inorganic fine particles is preferably 0.1 part by mass to 5.0 parts by mass, and more preferably 0.8 part by mass to 3.2 parts by mass with respect to 100 parts by mass of the toner base particles.

  The method for producing the toner is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a pulverization method, a monomer containing a specific crystalline polymer and a polymerizable monomer. A polymerization method (suspension polymerization method, emulsion polymerization method) for directly polymerizing the composition in an aqueous phase, a composition containing a specific crystalline polymer and an isocyanate group-containing prepolymer in an aqueous phase with amines Examples include a direct addition / crosslinking polyaddition reaction method, a polyaddition reaction method using an isocyanate group-containing prepolymer, a method of dissolving in a solvent, removing the solvent, and pulverizing, and a melt spraying method.

The pulverization method is, for example, a method of obtaining the toner base particles by melting or kneading the toner material, pulverizing, classifying or the like. In the case of the pulverization method, for the purpose of increasing the average circularity of the toner, the shape may be controlled by applying a mechanical impact force to the obtained toner base particles. In this case, the mechanical impact force can be applied to the toner base particles using an apparatus such as a hybridizer or mechanofusion, for example.
The above toner materials are mixed, and the mixture is charged into a melt kneader and melt kneaded. As the melt kneader, for example, a uniaxial continuous kneader, a biaxial continuous kneader, or a batch kneader using a roll mill can be used. For example, KTK type twin screw extruder manufactured by Kobe Steel, TEM type extruder manufactured by Toshiba Machine Co., Ltd., twin screw extruder manufactured by Casey Kay, PCM type twin screw extruder manufactured by Ikegai Co., Ltd. Used for. This melt-kneading is preferably performed under appropriate conditions that do not cause the molecular chain of the binder resin to be broken. Specifically, the melt kneading temperature is performed with reference to the softening point of the binder resin. If the temperature is higher than the softening point, cutting is severe, and if the temperature is too low, dispersion may not proceed.

  In the pulverization, the kneaded product obtained by the kneading is pulverized. In this pulverization, it is preferable that the kneaded material is first coarsely pulverized and then finely pulverized. At this time, a method of pulverizing by colliding with a collision plate in a jet stream, pulverizing particles by colliding with each other in a jet stream, or pulverizing with a narrow gap between a mechanically rotating rotor and a stator is preferably used.

In the classification, the pulverized product obtained by the pulverization is classified and adjusted to particles having a predetermined particle diameter. The classification can be performed by removing the fine particle portion by, for example, a cyclone, a decanter, centrifugation, or the like.
After the pulverization and classification are completed, the pulverized product is classified in an air stream by centrifugal force or the like to produce a toner having a predetermined particle size.

The suspension polymerization method is an oil-soluble polymerization initiator, emulsification described later in an aqueous medium in which a colorant, a release agent and the like are dispersed in a polymerizable monomer and a surfactant and other solid dispersants are contained. Emulsified and dispersed by the method. Thereafter, a polymerization reaction is performed to form particles, and then wet processing for attaching inorganic fine particles to the toner particle surfaces in the present invention may be performed. At that time, it is preferable to wash the excess surfactant or the like, and to treat the removed toner particles.
Examples of the polymerizable monomer include acids such as acrylic acid, methacrylic acid, α-cyanoacrylic acid, α-cyanomethacrylic acid, itaconic acid, crotonic acid, fumaric acid, maleic acid or maleic anhydride; acrylamide, Methacrylamide, diacetone acrylamide, or their methylol compounds; vinyl pyridine, vinyl pyrrolidone, vinyl imidazole, ethyleneimine, dimethylaminoethyl methacrylate and other (meth) acrylates with amino groups are used on the toner particle surface. Functional groups can be introduced.
Further, by selecting a dispersant having an acid group or a basic group as the dispersant to be used, the dispersant can be adsorbed and left on the particle surface to introduce a functional group.

  As the emulsion polymerization method, a water-soluble polymerization initiator and a polymerizable monomer are emulsified in water using a surfactant, and a latex is synthesized by a usual emulsion polymerization method. Separately, a dispersion in which a colorant, a release agent and the like are dispersed in an aqueous medium is prepared, and after mixing, the toner is aggregated to a toner size and heat-fused to obtain a toner. Thereafter, wet processing of inorganic fine particles described later may be performed. A functional group can be introduced on the surface of the toner particles by using a latex similar to the monomer used in the suspension polymerization method.

Among these, since the selectivity of the resin is high, the low-temperature fixability is high, the granulation property is excellent, and the particle size, the particle size distribution, and the shape can be easily controlled. And a polymer capable of reacting with the active hydrogen group-containing compound is dissolved or dispersed in an organic solvent to prepare a toner solution, and then the toner solution is emulsified or dispersed in an aqueous medium. In the aqueous medium, the active hydrogen group-containing compound and a polymer capable of reacting with the active hydrogen group-containing compound are reacted to form an adhesive substrate in the form of particles, and the organic solvent is What is obtained by removing is suitable.
Examples of the toner material include an adhesive base obtained by reacting an active hydrogen group-containing compound, a polymer capable of reacting with the active hydrogen group-containing compound, a binder resin, a charge control agent, and a colorant. And other components such as resin fine particles and a release agent.

  In order to improve the fluidity, storage stability, developability, and transferability of the toner, inorganic fine particles such as hydrophobic silica fine powder may be further added to and mixed with the toner base particles produced as described above. For mixing the additives, a general powder mixer is used, but it is preferable to equip a jacket or the like to adjust the internal temperature. In order to change the load history applied to the additive, the additive may be added midway or gradually. In this case, you may change the rotation speed, rolling speed, time, temperature, etc. of a mixer. Alternatively, a strong load may be applied first, then a relatively weak load, or vice versa. Examples of the mixing equipment that can be used include a V-type mixer, a rocking mixer, a Ladige mixer, a Nauter mixer, and a Henschel mixer. Next, the toner is obtained by passing through a sieve of 250 mesh or more to remove coarse particles and aggregated particles.

  The shape, size, etc. of the toner are not particularly limited and can be appropriately selected according to the purpose. The average circularity, volume average particle size, volume average particle size and number are as follows. It is preferable to have a ratio to the average particle size (volume average particle size / number average particle size).

The average circularity is a value obtained by dividing the perimeter of an equivalent circle having the same projected shape as the toner shape by the perimeter of the actual particles, and is preferably 0.900 to 0.980, for example, 0.950 to 0 .975 is more preferred. Note that particles having an average circularity of less than 0.94 are preferably 15% or less.
If the average circularity is less than 0.900, satisfactory transferability and a high-quality image free from dust may not be obtained. If the average circularity exceeds 0.980, image formation employing blade cleaning or the like is employed. In the system, defective cleaning occurs on the photoconductor and the transfer belt, and in the case of image formation with a high image area ratio such as a photographic image, an untransferred image is formed due to defective paper feeding, etc. The accumulated toner may become a transfer residual toner on the photoconductor, resulting in background smearing of the image, or it may contaminate the charging roller for charging the photoconductor in contact with the original charging ability. It may become impossible to demonstrate.

  The average circularity is measured using a flow type particle image analyzer (“FPIA-2100”, manufactured by Sysmex Corporation), and analyzed using analysis software (FPIA-2100 Data Processing Program for FPIA version 00-10). It was. Specifically, 0.1-0.5 mL of 10% by mass surfactant (alkylbenzene sulfonate, Neogen SC-A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to a 100 mL (L: liter) beaker made of glass. Then, 0.1 to 0.5 g of each toner was added and stirred with a micropartel, and then 80 mL of ion-exchanged water was added. The obtained dispersion was subjected to a dispersion treatment for 3 minutes with an ultrasonic disperser (manufactured by Honda Electronics Co., Ltd.). The shape and distribution of the toner were measured using the FPIA-2100 until the concentration of the dispersion reached 5,000 to 15,000 / μL. In this measurement method, it is important that the concentration of the dispersion is 5,000 to 15,000 / μL from the viewpoint of measurement reproducibility of average circularity. In order to obtain the concentration of the dispersion, it is necessary to change the conditions of the dispersion, that is, the amount of surfactant to be added and the amount of toner. The amount of the surfactant varies depending on the hydrophobicity of the toner as in the measurement of the toner particle diameter described above. If it is added in a large amount, noise due to bubbles is generated, and if it is too small, the toner cannot be sufficiently wetted. It will be enough. The amount of toner added varies depending on the particle size, and is small when the particle size is small, and needs to be increased when the particle size is large. When the toner particle size is 3 μm to 10 μm, the toner amount is 0.1 g to 0.00 g. By adding 5 g, the dispersion concentration can be adjusted to 5,000 / μL to 15,000 / μL.

The volume average particle diameter of the toner is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it is preferably 3 μm to 10 μm, and more preferably 3 μm to 8 μm.
When the volume average particle size is less than 3 μm, in the case of a two-component developer, the toner may be fused to the surface of the carrier during a long period of stirring in the developing device, and the charging ability of the carrier may be reduced. Therefore, it becomes difficult to obtain a high-resolution and high-quality image, and when the balance of the toner in the developer is performed, the fluctuation of the toner particle diameter may increase.

  The ratio of the volume average particle diameter to the number average particle diameter (volume average particle diameter / number average particle diameter) in the toner is preferably 1.00 to 1.25, more preferably 1.10 to 1.25.

  The volume average particle diameter and the ratio between the volume average particle diameter and the number average particle diameter (volume average particle diameter / number average particle diameter) are measured using a particle size measuring device (“Multisizer III”, manufactured by Beckman Coulter, Inc.). Then, measurement was performed with an aperture diameter of 100 μm, and analysis was performed with analysis software (Beckman Coulter Multisizer 3 Version 3.51). Specifically, 0.5 ml of 10% by weight surfactant (alkylbenzene sulfonate, Neogen SC-A, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) is added to a 100 ml glass beaker, and 0.5 g of each toner is added. The mixture was stirred with a micropartel, and then 80 ml of ion-exchanged water was added. The obtained dispersion was subjected to a dispersion treatment for 10 minutes with an ultrasonic disperser (W-113MK-II, manufactured by Honda Electronics Co., Ltd.). The dispersion was measured using the Multisizer III and Isoton III (manufactured by Beckman Coulter, Inc.) as the measurement solution. In the measurement, the toner sample dispersion was dropped so that the concentration indicated by the apparatus was 8 ± 2% by mass. In this measurement method, it is important that the concentration is 8 ± 2% by mass from the viewpoint of the reproducibility of the particle size. Within this concentration range, no error occurs in the particle size.

  The coloration of the toner is not particularly limited and may be appropriately selected according to the purpose, and may be at least one selected from black toner, cyan toner, magenta toner, and yellow toner. Can be obtained by appropriately selecting the type of the colorant, and is preferably a color toner.

<Container with developer>
The developer-containing container is obtained by accommodating the developer of the present invention in a container.
There is no restriction | limiting in particular as said container, It can select suitably from well-known things, For example, what has a developer container main body and a cap etc. are mentioned suitably.
The size, shape, structure, material and the like of the developer container body are not particularly limited and can be appropriately selected according to the purpose. For example, the shape is preferably cylindrical. A spiral unevenness is formed on the peripheral surface, and the developer as the contents can be transferred to the discharge port side by rotating, and a part or all of the spiral part has a bellows function, Etc. are particularly preferred.
The material of the developer container main body is not particularly limited, and those having good dimensional accuracy are preferable. For example, a resin is preferable. Among them, for example, polyester resin, polyethylene resin, polypropylene resin, polystyrene resin, Preferable examples include vinyl chloride resin, polyacrylic acid, polycarbonate resin, ABS resin, polyacetal resin, and the like.
The developer-containing container is easy to store and transport, has excellent handleability, and can be suitably used for replenishing the developer by being detachably attached to a process cartridge, an image forming apparatus, and the like described later.

<Process cartridge>
The process cartridge used in the present invention can develop an electrostatic latent image carrier carrying an electrostatic latent image and the electrostatic latent image carried on the electrostatic latent image carrier using a developer. At least developing means for forming a visual image, and other means appropriately selected as necessary.
The developing means includes at least a developer container that contains the developer of the present invention, and a developer carrier that carries and conveys the developer contained in the developer container. In addition, a layer thickness regulating member for regulating the toner layer thickness to be carried may be provided if necessary.
The process cartridge can be detachably provided in various electrophotographic image forming apparatuses, and is preferably detachably provided in the image forming apparatus of the present invention described below.

Here, for example, as shown in FIG. 2, the process cartridge includes a photosensitive member 101, and includes a charging unit 102, a developing unit 104, a transfer unit 108, and a cleaning unit 107, and other members as necessary. It has. In FIG. 2, reference numeral 103 denotes exposure by an exposure unit, and a light source capable of writing with high resolution is used. Reference numeral 105 denotes a recording medium. As the photoreceptor 101, the same one as an image forming apparatus described later can be used. An arbitrary charging member is used as the charging unit 102.
Next, the image forming process using the process cartridge shown in FIG. 2 will be described. The photoconductor 101 is exposed to the surface by charging by the charging means 102 and exposure 103 by the exposure means (not shown) while rotating in the direction of the arrow. An electrostatic latent image corresponding to the image is formed. The electrostatic latent image is developed with toner by the developing unit 104, and the toner image is transferred to the recording medium 105 by the transfer unit 108 and printed out. Next, the surface of the photoconductor after the image transfer is cleaned by the cleaning unit 107 and further neutralized by a neutralizing unit (not shown), and the above operation is repeated again.

(Image forming method and image forming apparatus)
The image forming method of the present invention includes at least an electrostatic latent image forming step, a developing step, a transfer step, and a fixing step, and other steps appropriately selected as necessary, for example, a static elimination step, a cleaning step. , Including recycling process, control process, etc.
The image forming apparatus used in the present invention includes at least an electrostatic latent image carrier, an electrostatic latent image forming unit, a developing unit, a transfer unit, and a fixing unit. It has other selected means, for example, static elimination means, cleaning means, recycling means, control means, and the like.

-Electrostatic latent image forming process and electrostatic latent image forming means-
The electrostatic latent image forming step is a step of forming an electrostatic latent image on the electrostatic latent image carrier.
The electrostatic latent image carrier (sometimes referred to as “electrophotographic photosensitive member” or “photosensitive member”) is not particularly limited in terms of material, shape, structure, size, etc. Although it can be selected as appropriate, the shape thereof is preferably a drum shape, and examples of the material thereof include inorganic photoreceptors such as amorphous silicon and selenium, organic photoreceptors (OPC) such as polysilane and phthalopolymethine, and the like. Is mentioned. Among these, amorphous silicon or the like is preferable in terms of long life.

  The formation of the electrostatic latent image can be performed, for example, by uniformly charging the surface of the electrostatic latent image carrier and then performing imagewise exposure, and is performed by the electrostatic latent image forming unit. be able to. The electrostatic latent image forming means includes, for example, at least a charger that uniformly charges the surface of the electrostatic latent image carrier and an exposure device that exposes the surface of the electrostatic latent image carrier imagewise. Prepare.

The charging can be performed, for example, by applying a voltage to the surface of the electrostatic latent image carrier using the charger.
The charger is not particularly limited and may be appropriately selected depending on the purpose. For example, a known contact charging device including a conductive or semiconductive roll, brush, film, rubber blade, etc. And non-contact chargers utilizing corona discharge such as corotrons and corotrons.
The charger is preferably one that is arranged in contact or non-contact with the electrostatic latent image carrier and charges the surface of the electrostatic latent image carrier by applying DC and AC voltages in a superimposed manner.
The charger is a charging roller that is disposed in a non-contact proximity to the electrostatic latent image carrier via a gap tape, and the electrostatic latent image is carried by applying a direct current and an alternating voltage to the charging roller. Those that charge the body surface are preferred.

The exposure can be performed, for example, by exposing the surface of the latent electrostatic image bearing member imagewise using the exposure device.
The exposure device is not particularly limited as long as it can expose the surface of the electrostatic latent image carrier charged by the charger so as to form an image to be formed, and is appropriately selected according to the purpose. For example, various exposure devices such as a copying optical system, a rod lens array system, a laser optical system, and a liquid crystal shutter optical system can be used.
In the present invention, a back light system in which imagewise exposure is performed from the back surface side of the electrostatic latent image carrier may be adopted.

-Development process and development means-
The developing step is a step of developing the electrostatic latent image using the developer of the present invention to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the developer of the present invention, and can be performed by the developing unit.
The developing means is not particularly limited as long as it can be developed using, for example, the developer of the present invention, and can be appropriately selected from known ones. For example, the developer of the present invention is accommodated. In addition, it is preferable to have at least a developing device that can apply the developer to the electrostatic latent image in a contact or non-contact manner, and a developing device including the developer-containing container is more preferable.

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a developer having a stirrer for charging the developer by frictional stirring and a rotatable magnet roller is preferable.

In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrostatic latent image carrier (photoconductor), a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is electrically attracted. It moves to the surface of the electrostatic latent image carrier (photoconductor) by force. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrostatic latent image carrier (photoconductor).
The developer accommodated in the developing device is the developer of the present invention.

―Transfer process and transfer means―
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably full color toner as the toner, and a composite transfer image; A mode including a secondary transfer step of transferring the transfer image onto the recording medium is more preferable.
The transfer can be performed, for example, by charging the latent electrostatic image bearing member (photoconductor) of the visible image using a transfer charger, and can be performed by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred.
The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

The transfer means (the primary transfer means, the secondary transfer means) is a transfer for peeling and charging the visible image formed on the electrostatic latent image carrier (photoconductor) to the recording medium side. It is preferable to have at least a vessel. The number of the transfer means may be one, or two or more.
Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is not particularly limited and can be appropriately selected from known recording media (recording paper).

―Fixing process and fixing means―
The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing device, and may be performed each time the developer of each color is transferred to the recording medium, or the developer of each color. On the other hand, it may be carried out at the same time in a state where these are laminated.
There is no restriction | limiting in particular as said fixing device, Although it can select suitably according to the objective, A well-known heating-pressing means is suitable. Examples of the heating and pressing means include a combination of a heating roller and a pressure roller, a combination of a heating roller, a pressure roller, and an endless belt.
The fixing device includes a heating body including a heating element, a film in contact with the heating body, and a pressure member in pressure contact with the heating body through the film, and the film and the pressure member It is preferably a unit that heats and fixes a recording medium on which an unfixed image is formed. The heating in the heating and pressing means is usually preferably 80 ° C to 200 ° C.
In the present invention, for example, a known optical fixing device may be used together with or in place of the fixing step and the fixing unit depending on the purpose.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrostatic latent image carrier, and can be suitably performed by a neutralization unit.
The neutralization means is not particularly limited, and may be appropriately selected from known neutralizers as long as it can apply a neutralization bias to the electrostatic latent image carrier. Preferably mentioned.

The cleaning step is a step of removing the toner remaining on the electrostatic latent image carrier, and can be suitably performed by a cleaning unit.
The cleaning unit is not particularly limited, and may be selected from known cleaners as long as it can remove the toner remaining on the electrostatic latent image carrier. For example, a magnetic brush cleaner Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

The recycling step is a step of recycling the toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit.
There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

Each of the above steps can be suitably performed by a control means.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

  Here, an aspect of carrying out the image forming method of the present invention by the image forming apparatus will be described with reference to FIG. An image forming apparatus 100 shown in FIG. 3 includes a photosensitive drum 10 (photosensitive member 10) as the electrostatic latent image carrier, a charging roller 20 as the charging unit, and an exposure device 30 as the exposure unit. A developing device 40 as the developing means, an intermediate transfer member 50, a cleaning device 60 as the cleaning means having a cleaning blade, and a static elimination lamp 70 as the static elimination means.

  The intermediate transfer member 50 is an endless belt, and is designed so as to be movable in the direction of the arrow in the figure by three rollers 51 that are arranged on the inner side and stretch the belt. Part of the three rollers 51 also functions as a transfer bias roller that can apply a predetermined transfer bias (primary transfer bias) to the intermediate transfer member 50. An intermediate transfer member cleaning blade 90 is disposed in the vicinity of the intermediate transfer member 50, and a transfer bias for transferring a visible image (toner image) to the recording medium 95 (secondary transfer) is applied. Possible transfer rollers 80 as the transfer means are arranged to face each other. Around the intermediate transfer member 50, a corona charger 58 for applying a charge to the visible image on the intermediate transfer member 50 is connected to the electrostatic latent image carrier 10 in the rotation direction of the intermediate transfer member 50. The contact portion between the intermediate transfer member 50 and the contact portion between the intermediate transfer member 50 and the recording medium 95 is disposed.

  The developing device 40 includes a developing belt 41 as a developer carrying member, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and a cyan developing unit 45C provided around the developing belt 41. Yes. The black developing unit 45K includes a developer accommodating portion 42K, a developer supply roller 43K, and a developing roller 44K. The yellow developing unit 45Y includes a developer container 42Y, a developer supply roller 43Y, and a developing roller 44Y. The magenta developing unit 45M includes a developer container 42M, a developer supply roller 43M, and a developing roller 44M. The cyan developing unit 45C includes a developer container 42C, a developer supply roller 43C, and a developing roller 44C. Further, the developing belt 41 is an endless belt, is rotatably stretched by a plurality of belt rollers, and a part thereof is in contact with the electrostatic latent image carrier 10.

  In the image forming apparatus 100 shown in FIG. 3, for example, the charging roller 20 uniformly charges the photosensitive drum 10. The exposure device 30 performs imagewise exposure on the photosensitive drum 10 to form an electrostatic latent image. The electrostatic latent image formed on the photosensitive drum 10 is developed by supplying toner from the developing device 40 to form a visible image (toner image). The visible image (toner image) is transferred (primary transfer) onto the intermediate transfer member 50 by the voltage applied from the roller 51, and further transferred (secondary transfer) onto the transfer paper 95. As a result, a transfer image is formed on the transfer paper 95. The residual toner on the photoconductor 10 is removed by the cleaning device 60, and the charge on the photoconductor 10 is temporarily removed by the charge eliminating lamp 70.

  Another mode for carrying out the image forming method of the present invention by the image forming apparatus will be described with reference to FIG. The image forming apparatus 100 shown in FIG. 4 does not include the developing belt 41 in the image forming apparatus 100 shown in FIG. 3, and a black developing unit 45K, a yellow developing unit 45Y, a magenta developing unit 45M, and the like around the photoconductor 10. Except for the fact that the cyan developing unit 45C is arranged directly opposite, it has the same configuration as the image forming apparatus 100 shown in FIG. In FIG. 4, the same components as those in FIG. 3 are denoted by the same reference numerals.

Another mode for carrying out the image forming method of the present invention by the image forming apparatus will be described with reference to FIG. The tandem type image forming apparatus shown in FIG. 5 is a tandem type color image forming apparatus. The tandem image forming apparatus includes a copying apparatus main body 150, a paper feed table 200, a scanner 300, and an automatic document feeder (ADF) 400.
The copying apparatus main body 150 is provided with an endless belt-like intermediate transfer member 50 at the center. The intermediate transfer member 50 is stretched around the support rollers 14, 15 and 16, and can be rotated clockwise in FIG. 5. An intermediate transfer member cleaning device 17 for removing residual toner on the intermediate transfer member 50 is disposed in the vicinity of the support roller 15. The intermediate transfer member 50 stretched between the support roller 14 and the support roller 15 is a tandem type in which four image forming units 18 of yellow, cyan, magenta, and black are arranged to face each other along the conveyance direction. A developing device 120 is disposed. An exposure device 21 is disposed in the vicinity of the tandem developing device 120. A secondary transfer device 22 is disposed on the side of the intermediate transfer member 50 opposite to the side on which the tandem developing device 120 is disposed. In the secondary transfer device 22, a secondary transfer belt 24, which is an endless belt, is stretched around a pair of rollers 23, and the transfer paper conveyed on the secondary transfer belt 24 and the intermediate transfer body 50 are in contact with each other. Is possible. A fixing device 25 is disposed in the vicinity of the secondary transfer device 22. The fixing device 25 includes a fixing belt 26 that is an endless belt, and a pressure roller 27 that is pressed against the fixing belt 26.
In the tandem type image forming apparatus, a sheet reversing device 28 for reversing the transfer paper for image formation on both sides of the transfer paper is disposed in the vicinity of the secondary transfer device 22 and the fixing device 25. Yes.

  Next, formation of a full-color image (color copy) using the tandem developing device 120 will be described. That is, first, a document is set on the document table 130 of the automatic document feeder (ADF) 400, or the automatic document feeder 400 is opened and the document is set on the contact glass 32 of the scanner 300. 400 is closed.

  When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the contact glass 32. Immediately after that, the scanner 300 is driven, and the first traveling body 33 and the second traveling body 34 travel. At this time, light from the light source is irradiated by the first traveling body 33 and reflected light from the document surface is reflected by the mirror in the second traveling body 34 and is received by the reading sensor 36 through the imaging lens 35 to be color. An original (color image) is read and used as black, yellow, magenta, and cyan image information.

  Each image information of black, yellow, magenta, and cyan is stored in each image forming unit 18 (black image forming unit, yellow image forming unit, magenta image forming unit, and cyan image) in the tandem developing device 120. Each of the image forming units forms black, yellow, magenta, and cyan toner images. That is, each image forming means 18 (black image forming means, yellow image forming means, magenta image forming means, and cyan image forming means) in the tandem type developing device 120 is a static image as shown in FIG. An electrostatic latent image carrier 10 (black electrostatic latent image carrier 10K, yellow electrostatic latent image carrier 10Y, magenta electrostatic latent image carrier 10M, and cyan electrostatic latent image carrier 10C); The electrostatic latent image bearing member 10 is uniformly charged, and the electrostatic latent image bearing member is exposed (L in FIG. 6) for each color image corresponding to each color image information. An exposure device that forms an electrostatic latent image corresponding to each color image on the electrostatic latent image carrier, and each color toner (black toner, yellow toner, magenta toner, and cyan toner) Develop with A developing device 61 for forming a toner image with each color toner, a transfer charger 62 for transferring the toner image onto the intermediate transfer member 50, a cleaning device 63, and a static eliminator 64 are provided. Each single color image (black image, yellow image, magenta image, and cyan image) can be formed based on the color image information. The black image, the yellow image, the magenta image, and the cyan image formed in this manner are respectively transferred to the black electrostatic latent image carrier 10K on the intermediate transfer member 50 that is rotationally moved by the support rollers 14, 15 and 16. Black image formed on top, yellow image formed on electrostatic latent image carrier 10Y for yellow, magenta image formed on electrostatic latent image carrier 10M for magenta, and electrostatic latent image carrier for cyan The cyan image formed on 10C is sequentially transferred (primary transfer). Then, the black image, the yellow image, the magenta image, and the cyan image are superimposed on the intermediate transfer member 50 to form a composite color image (color transfer image).

  On the other hand, in the paper feed table 200, one of the paper feed rollers 142 is selectively rotated to feed out a sheet (recording paper) from one of the paper feed cassettes 144 provided in multiple stages in the paper bank 143. Each sheet is separated and sent to the paper feed path 146, transported by the transport roller 147, guided to the paper feed path 148 in the copying machine main body 150, and abutted against the registration roller 49 and stopped. Alternatively, the sheet feed roller 142 is rotated to feed out sheets (recording paper) on the manual feed tray 54, separated one by one by the separation roller 145, put into the manual feed path 53, and abutted against the registration roller 49 and stopped. . The registration roller 49 is generally used while being grounded, but may be used in a state where a bias is applied to remove paper dust from the sheet. Then, the registration roller 49 is rotated in synchronization with the synthesized color image (color transfer image) synthesized on the intermediate transfer member 50, and a sheet (recording paper) is interposed between the intermediate transfer member 50 and the secondary transfer device 22. The secondary color transfer device 22 transfers the composite color image (color transfer image) onto the sheet (recording paper), thereby transferring the color image onto the sheet (recording paper). Is formed. The residual toner on the intermediate transfer member 50 after image transfer is cleaned by the intermediate transfer member cleaning device 17.

  The sheet (recording paper) on which the color image has been transferred is conveyed by the secondary transfer device 22 and sent to the fixing device 25, where the combined color image (color) is generated by heat and pressure. (Transfer image) is fixed on the sheet (recording paper). Thereafter, the sheet (recording paper) is switched by the switching claw 55 and discharged by the discharge roller 56 and stacked on the discharge tray 57, or switched by the switching claw 55 and reversed by the sheet reversing device 28 and transferred again. After being guided to the position and recording an image on the back surface, the image is discharged by the discharge roller 56 and stacked on the discharge tray 57.

  In the image forming apparatus and the image forming method of the present invention, by using the carrier of the present invention, it is possible to provide an image with less toner scattering and scumming over a long period of time.

  Examples of the present invention will be described below, but the present invention is not limited to the following examples.

(Production Example 1)
<Preparation of Toner 1>
―Synthesis of organic fine particle emulsion―
In a reaction vessel in which a stir bar and a thermometer are set, 683 parts by mass of water, 11 parts by mass of sodium salt of ethylene oxide methacrylate adduct sulfate (Eleminol RS-30, manufactured by Sanyo Chemical Industries Ltd.), 83 parts by mass of styrene Part, 83 parts by weight of methacrylic acid, 110 parts by weight of butyl acrylate, and 1 part by weight of ammonium persulfate were added and stirred at 400 rpm for 15 minutes to obtain a white emulsion. This emulsion was heated to raise the system temperature to 75 ° C. and reacted for 5 hours. Next, 30 parts by mass of a 1% by mass ammonium persulfate aqueous solution was added, and the mixture was aged at 75 ° C. for 5 hours to form a vinyl resin (a copolymer of methacrylic acid-butyl acrylate-methacrylic acid ethylene oxide adduct sulfate sodium salt). An aqueous dispersion was obtained. This is designated as [fine particle dispersion 1].
The volume average particle diameter of the fine particles contained in the obtained [fine particle dispersion 1] was measured with a particle size distribution measuring apparatus (“LA-920”, manufactured by Horiba, Ltd.) using a laser scattering method, and found to be 105 nm. It was. In addition, a part of [Fine Particle Dispersion 1] was dried to isolate only the resin component. The glass transition temperature (Tg) of this resin was 59 ° C., and the weight average molecular weight (Mw) was 150,000.

-Preparation of aqueous phase-
990 parts by weight of water, 83 parts by weight of [fine particle dispersion 1], 37 parts by weight of a 48.5% by weight aqueous solution of sodium dodecyl diphenyl ether disulfonate (Eleminol MON-7, Sanyo Chemical Industries, Ltd.), and 90 parts by weight of ethyl acetate Were mixed and stirred to obtain a milky white liquid. This liquid is designated [Aqueous Phase 1].

―Synthesis of low molecular weight polyester―
In a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 229 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 529 parts by mass of bisphenol A propylene oxide 3 mol adduct, 208 parts by mass of terephthalic acid, 46 adipic acid 46 Part by mass and 2 parts by mass of dibutyltin oxide were charged and reacted at 230 ° C. for 8 hours under normal pressure. Subsequently, after reacting under reduced pressure of 10 to 15 mmHg for 5 hours, 44 parts by mass of trimellitic anhydride was put in the reaction vessel and reacted at 180 ° C. and normal pressure for 2 hours to synthesize [low molecular weight polyester 1].
The obtained [low molecular polyester 1] has a glass transition temperature (Tg) of 45 ° C., a weight average molecular weight (Mw) of 5,800, a number average molecular weight of 2,600, and an acid value of 24 mgKOH / g.

―Synthesis of polyester prepolymer―
In a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen introduction tube, 682 parts by mass of bisphenol A ethylene oxide 2 mol adduct, 81 parts by mass of bisphenol A propylene oxide 2 mol adduct, 283 parts by mass of terephthalic acid, 22 parts by mass of merit acid and 2 parts by mass of dibutyltin oxide were added and reacted at 230 ° C. for 8 hours under normal pressure. Subsequently, it reacted for 5 hours under the reduced pressure of 10-15 mmHg, and the [intermediate polyester 1] was synthesize | combined.
The obtained [Intermediate Polyester 1] had a number average molecular weight of 2,100, a weight average molecular weight of 9,500, a glass transition temperature (Tg) of 55 ° C., an acid value of 0.5 mgKOH / g, and a hydroxyl value of 51 mgKOH / g. .
Next, 410 parts by mass of [Intermediate Polyester 1], 89 parts by mass of isophorone diisocyanate, and 500 parts by mass of ethyl acetate are placed in a reaction vessel equipped with a cooling pipe, a stirrer, and a nitrogen introduction pipe. The reaction was performed for a while to obtain [Prepolymer 1].
The obtained [Prepolymer 1] had a free isocyanate mass% of 1.74%.

-Synthesis of ketimine-
In a reaction vessel equipped with a stir bar and a thermometer, 170 parts by mass of isophoronediamine and 75 parts by mass of methyl ethyl ketone were charged and reacted at 50 ° C. for 5 hours to synthesize [ketimine compound 1]. The amine value of the obtained [ketimine compound 1] was 418.

-Preparation of master batch (MB)-
1,200 parts by weight of water, carbon black (PBk-7: Printex 60, manufactured by Degussa, DBP oil absorption = 114 mL / 100 mg, pH = 10) 540 parts by weight, and polyester resin (manufactured by Sanyo Chemical Industries, RS801) 1 , 200 parts by mass were added and mixed with a Henschel mixer (Mitsui Mining Co., Ltd.). The obtained mixture was kneaded at 150 ° C. for 30 minutes using two rolls, cooled by rolling, and pulverized with a pulverizer to obtain a master batch. This is designated as [Masterbatch 1].

-Preparation of oil phase-
In a reaction vessel equipped with a stir bar and a thermometer, 300 parts by weight of [low molecular weight polyester 1], 90 parts by weight of carnauba wax, 10 parts by weight of rice wax, and 1000 parts by weight of ethyl acetate were charged and stirred while stirring. After dissolving at 0 ° C., it was rapidly cooled to 4 ° C. at once. Using a bead mill (Ultra Visco Mill, manufactured by Imex Co., Ltd.), the liquid feeding speed is 1 kg / hr, the disk peripheral speed is 6 m / sec, and 0.5 mm zirconia beads are filled by 80% by volume, and dispersion is performed under conditions of 3 passes. And a wax dispersion having a volume average particle size of 0.6 μm was obtained.
Next, 500 parts by weight of “Masterbatch 1” and 640 parts by weight of a 70% by weight ethyl acetate solution of “Low molecular weight polyester 1” were added, mixed for 10 hours, then 5 passes through the bead mill, and ethyl acetate was added to obtain a solid content. “Oil phase 1” adjusted to a concentration of 50% by mass was produced.

―Preparation of polymerization toner―
[Oil Phase 1] 73.2 parts by mass, [Prepolymer 1] 6.8 parts by mass, and [Ketimine Compound 1] 0.48 parts by mass were placed in a container and mixed well with [Emulsified oil phase 1]. 120 parts by mass of aqueous phase 1] was added, mixed for 1 minute with a homomixer, and then allowed to converge with a paddle for 1 hour with gentle stirring to obtain [Emulsion slurry 1].
The obtained [Emulsion slurry 1] was desolvated at 30 ° C. for 1 hour, further aged at 60 ° C. for 5 hours, washed with water, filtered and dried, and then sieved with a mesh of 75 μm, and the volume average particle diameter Toner base particles having a particle size of 6.1 μm, a number average particle size of 5.4 μm, and an average circularity of 0.972 were prepared.
Next, 0.7 parts by weight of hydrophobic silica and 0.3 parts by weight of hydrophobic titanium oxide were mixed with 100 parts by weight of the obtained toner base particles using a Henschel mixer to prepare “Toner 1”.

  In the following Examples 1-4 and Comparative Examples 1-3, the particle size distribution of the carrier, the thickness of the coating layer, and the electrical resistance of the carrier were measured as follows.

<Carrier particle size distribution>
The particle size distribution of the carrier was measured using a Microtrac particle size distribution meter (model HRA9320-X100).

<Measurement of coating layer thickness>
Using a transmission electron microscope (TEM), the cross section of the carrier was observed, and the thickness of the coating layer was measured.

<Measurement of carrier electric resistance>
The electric resistance of the carrier was filled in a container having electrodes arranged in parallel with an interval of 2 mm, and the DC resistance at a potential difference of 50 V between the two electrodes was measured with a 4329A High Resistance Meter manufactured by Yokogawa Hewlett-Packard Co., Ltd.

[Example 1]
-Fabrication of Carrier 1-
・ Acrylic resin solution (Hitaloid 3012X, solid content 50% by mass)
30.0 parts by mass / guanamine solution (Mitsui Cytec Co., Ltd. Mycoat 106 solid content 77% by mass)
10.0 parts by mass silicone resin solution (Toray Dow Corning SR2405 solid content 50% by mass)
60.0 parts by mass Aminosilane coupling agent (Toray Dow Corning Co., Ltd. SH6020 solid content 100%)
0.8 parts by mass Carbon fiber I (average fiber diameter 200 nm, average length 8 μm, amorphous type) Aspect ratio 40
15.0 parts by mass / 600 parts by mass of toluene The above materials were dispersed with a homomixer for 10 minutes to prepare a coating layer dispersion.
Using ferrite powder (saturation magnetic moment 65 emu / g at 1 k gauss) as the core material, using a tumbling flow type coating device so that the coating layer dispersion is 2 μm after drying on the core material surface. Applied and dried. The obtained carrier was baked by standing in an electric furnace at 150 ° C. for 1 hour. After cooling, the ferrite powder bulk was crushed using a sieve having an opening of 90 μm to obtain “Carrier 1”.
The obtained carrier 1 had a weight average particle diameter Dw of 38.5 μm, a number average particle diameter Dn of 33.8 μm, and Dw / Dn of 1.14. The volume resistivity of the carrier 1 was 2.47 × 10 ¹¹ Ω · cm (11.39 [log (Ω · cm)]), and the film thickness was 2.0 μm.

[Example 2]
-Fabrication of Carrier 2-
“Carrier 2” was produced in the same manner as in Example 1, except that carbon fiber I was changed to carbon fiber II (average fiber diameter 300 nm, average length 9 μm, graphite type, aspect ratio 30) in Example 1. did.
The obtained carrier 2 had a weight average particle diameter Dw of 38.8 μm, a number average particle diameter Dn of 34.1 μm, and Dw / Dn of 1.14. The volume resistivity of the carrier 2 was 1.88 × 10 ¹² Ω · cm (12.27 [log (Ω · cm)]), and the film thickness was 2.0 μm.

Example 3
-Production of carrier 3-
“Carrier 3” was produced in the same manner as in Example 1, except that carbon fiber I was changed to carbon fiber III (average fiber diameter 300 nm, average length 9 μm, hollow type, aspect ratio 30) in Example 1. did.
The obtained carrier 3 had a weight average particle diameter Dw of 38.7 μm, a number average particle diameter Dn of 33.8 μm, and Dw / Dn of 1.14. The volume resistivity of the carrier 3 was 4.68 × 10 ¹² Ω · cm (12.67 [log (Ω · cm)]), and the film thickness was 2.0 μm.

Example 4
-Fabrication of carrier 4-
“Carrier 4” was produced in the same manner as in Example 1, except that carbon fiber I was changed to carbon fiber IV (average fiber diameter 600 nm, average length 9 μm, amorphous type, aspect ratio 15) in Example 1. did.
The obtained carrier 4 had a weight average particle diameter Dw of 37.9 μm, a number average particle diameter Dn of 33.4 μm, and Dw / Dn of 1.13. The volume resistivity of the carrier 4 was 6.12 × 10 ¹² Ω · cm (12.79 [log (Ω · cm)]), and the film thickness was 2.0 μm.

Example 5
-Fabrication of carrier 5-
Example 1 except that the carbon fiber I was changed to carbon fiber V (average fiber diameter 100 nm, average length 5 μm, amorphous type, aspect ratio 50) and the film thickness was adjusted to 3 μm in Example 1. In the same manner as described above, “Carrier 5” was produced.
The obtained Comparative Carrier 1 had a weight average particle diameter Dw of 37.9 μm, a number average particle diameter Dn of 33.8 μm, and Dw / Dn of 1.12. The volume resistivity of the carrier 5 was 8.72 × 10 ¹² Ω · cm (12.94 [log (Ω · cm)]), and the film thickness was 3.0 μm.

[Comparative Example 1]
-Production of comparative carrier 1-
“Comparative carrier 1” was prepared in the same manner as in Example 1, except that the carbon fiber I was changed to carbon nanotubes (average fiber diameter 15 nm, average length 15 μm, aspect ratio 1000) in Example 1.
The obtained Comparative Carrier 1 had a weight average particle diameter Dw of 38.5 μm, a number average particle diameter Dn of 33.8 μm, and Dw / Dn of 1.14. Moreover, the volume resistivity of the comparison carrier 1 was 5.68 × 10 ¹³ Ω · cm (13.75 [log (Ω · cm)]), and the film thickness was 2.0 μm.

[Comparative Example 2]
-Production of comparison carrier 2-
A “comparative carrier 2” was produced in the same manner as in Example 1 except that the carbon fiber I in Example 1 was changed to carbon black (average particle diameter 15 nm, aspect ratio 2).
The obtained Comparative Carrier 2 had a weight average particle diameter Dw of 38.5 μm, a number average particle diameter Dn of 33.8 μm, and Dw / Dn of 1.14. Moreover, the volume resistivity of the comparison carrier 2 was 7.54 × 10 ¹³ Ω · cm (13.88 [log (Ω · cm)]), and the film thickness was 2.0 μm.

-Production of developer-
The produced carriers 1 to 5 and the comparative carriers 1 and 2 and the toner 1 are adjusted at a ratio such that the carrier coverage with the toner is 50%, and stirred with a tumbler mixer. And the developer of Comparative Examples 1-2 was produced.

  Using the developer thus prepared, the carrier coating layer was scraped and peeled off, image density, toner scattering property, background stain, color stain, and comprehensive evaluation were performed as follows. The results are shown in Table 1.

<Evaluation of carrier coating layer scraping and peeling>
The developed developer was evaluated for 200,000 sheets using a tandem color image forming apparatus (image Neo 450, manufactured by Ricoh Co., Ltd.), and the resistance reduction ratio of the carrier after running was as follows. Evaluated.
〔Evaluation criteria〕
A: Ratio of resistance after 200,000 sheets run / initial resistance within 1 to 1/10 ○: Ratio of resistance after 200,000 sheets / initial resistance within 1/10 to 1/100 Δ: Resistance ratio after 200,000 sheets run / initial resistance of run is within 1/100 to 1/1000 ×: Resistance ratio after 200,000 sheets run / initial resistance is less than 1/1000 The amount is a value obtained by converting the value measured by a high resist meter into a volume resistivity after the initial carrier is put between resistance measuring parallel electrodes: electrodes having a gap of 2 mm, DC 200 V is applied, and the resistance value after 30 sec is measured with a high resist meter ( The amount obtained by subtracting the value (R2) measured by the same method as the resistance measurement method from the carrier obtained by removing the toner in the developer after running with a blow-off device from R1). The value is 2.0 [log (Ω · cm)] or less That. Moreover, since the cause of resistance reduction is the detachment | desorption from the core material of the coating layer of a carrier, the amount of resistance reduction can be suppressed by reducing this film | membrane scraping.

<Image density>
Next, using the tandem color image forming apparatus (image Neo 450, manufactured by Ricoh Co., Ltd.), the developer thus prepared is copied onto a copy paper (TYPE6000 <70W>, manufactured by Ricoh Co., Ltd.). A solid image having an adhesion amount of 1.00 ± 0.05 mg / cm ² was formed. The solid image was repeatedly formed on 1 million copies of the copy paper.
The image density of the obtained solid image was visually observed at the initial stage and after the endurance of 1,000,000 sheets, and evaluated in four stages based on the following criteria. Note that the higher the image density obtained, the higher the density image can be formed. The evaluation corresponds to an embodiment of the process cartridge, the image forming apparatus, and the image forming method of the present invention.
〔Evaluation criteria〕
A: There was no change in image density and high image quality was obtained at the initial stage and after the endurance of 1,000,000 sheets.
○: After enduring 1,000,000 sheets, the image density was slightly reduced, but high image quality was obtained.
(Triangle | delta): After 1 million sheet endurance, the image density fell and the image quality fell.
X: After the endurance of 1 million sheets, the image density was remarkably lowered and the image quality was greatly lowered.

<Toner scattering>
The chart below shows the degree of toner contamination in the machine when 1 million sheets of a 5% image area ratio chart is output continuously using a tandem color image forming apparatus (Imagio Neo 450, manufactured by Ricoh Co., Ltd.). Based on 4 grades.
〔Evaluation criteria〕
A: There is no toner contamination in the machine and it is in an excellent state.
○: There is no toner contamination in the machine, and the state is good.
Δ: There is toner contamination in the machine, but it is a practically usable level.
X: Toner contamination in the machine is severe and the level is not practical.

<Soil dirt>
When a chart with an image area ratio of 5% is output continuously for 1 million sheets using a tandem color image forming apparatus (image Neo Neo 450, manufactured by Ricoh Co., Ltd.), the degree of background contamination of the image background is visually observed. Evaluation was made in three stages based on the following criteria.
〔Evaluation criteria〕
○: No background stains in the image background.
Δ: Soil is slightly generated in the background portion of the image.
X: Soil is generated in the background portion of the image.

<Color stain>
A chart with an image area ratio of 0.5% is output continuously for 30,000 sheets using a tandem type color image forming apparatus (imagio Neo 450, manufactured by Ricoh Co., Ltd.), and then a yellow single color image is output. The image density of the yellow monochrome image after sheet output was measured by X-RITE 938 (manufactured by x-rite). The CIE L *, CIE a *, and CIE b * at the point where the yellow image density is 1.4 ± 0.5 are measured at three points to obtain an average value, and are substituted into the following formula to calculate the ΔE value. Evaluation was made in three stages based on the criteria.
ΔE = √ ((initial L *) 2+ (initial a *) 2+ (initial b *) 2) −√ ((post-run L *) 2+ (post-run a *) 2+ (post-run b *) 2)
〔Evaluation criteria〕
A: ΔE is 2 or less and there is no color stain.
Δ: ΔE is 2 to 4, color stains are not noticeable, and no change in color tone is pointed out.
X: When ΔE is 4 or more, color stains are clearly noticeable, indicating a change in color tone.

<Comprehensive evaluation>
From the above evaluation results, a comprehensive judgment was made and the evaluation was made according to the following criteria.
〔Evaluation criteria〕
A: Very good B: Good x: Bad

From the results shown in Table 1, the developers of Examples 1 to 5 using the carriers 1 to 5 inhibit the coating layer from being scraped or peeled off, as compared with the developers of Comparative Examples 1 to 2, and the toner scattering and background contamination It was confirmed that high image density could be obtained without color stains.
Such an effect of the present invention is that the electrophotographic carrier of the present invention uses carbon fibers that are other conductive fine particles without substantially using carbon nanotubes as conductive fine particles, and the conductivity at that time. It can be said that the conductive fine particles are derived from carbon fibers having an aspect ratio of 10 to 50.

It is the schematic which shows the structure of the apparatus used for the measurement of the volume resistivity of the carrier of this invention. It is a schematic block diagram which shows an example of a process cartridge. It is a schematic explanatory drawing which shows one example which implements the image forming method of this invention with an image forming apparatus. It is a schematic explanatory drawing which shows the other example which implements the image forming method of this invention with an image forming apparatus. It is a schematic explanatory drawing which shows an example which implements the image forming method of this invention with an image forming apparatus (tandem type color image forming apparatus). FIG. 6 is a partially enlarged schematic explanatory diagram of the image forming apparatus shown in FIG. 5.

Explanation of symbols

10 Electrostatic latent image carrier (photosensitive drum)
10K Electrostatic latent image carrier for black 10Y Electrostatic latent image carrier for yellow 10M Electrostatic latent image carrier for magenta 10C Electrostatic latent image carrier for cyan 14 Support roller 15 Support roller 16 Support roller 17 Intermediate transfer cleaning device DESCRIPTION OF SYMBOLS 18 Image forming means 20 Charging roller 21 Exposure device 22 Secondary transfer device 23 Roller 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure belt 28 Sheet reversing device 30 Exposure device 32 Contact glass 33 First traveling body 34 Second Traveling body 35 Imaging lens 36 Reading sensor 40 Developing device 41 Developing belt 42K Developer container 42Y Developer container 42M Developer container 42C Developer container 43K Developer supply roller 43Y Developer supply roller 43M Developer supply roller 43C Developer supply roller 44K Development roller La 44Y Development roller 44M Development roller 44C Development roller 45K Black development unit 45Y Yellow development unit 45M Magenta development unit 45C Cyan development unit 49 Registration roller 50 Intermediate transfer member 51 Roller 52 Separation roller 53 Manual feed path 54 Manual feed tray 55 Switching Claw 56 Discharge Roller 57 Discharge Tray 58 Corona Charger 60 Cleaning Device 61 Developer 62 Transfer Charger 63 Photoconductor Cleaning Device 64 Charger 70 Charger Lamp 80 Transfer Roller 90 Cleaning Device 95 Transfer Paper 100 Image Forming Device 101 Electrostatic Latent image carrier (photoconductor)
DESCRIPTION OF SYMBOLS 102 Charging means 103 Exposure 104 Developing means 105 Recording medium 107 Cleaning means 108 Transfer means 120 Tandem type developer 121 Heating roller 122 Fixing roller 123 Fixing belt 124 Pressure roller 125 Heating source 126 Cleaning roller 127 Temperature sensor 130 Document table 142 Paper feed Roller 143 Paper bank 144 Paper feed cassette 145 Separation roller 146 Paper feed path 147 Transport roller 148 Paper feed path 150 Copier main body 160 Charging device 200 Paper feed table 300 Scanner 400 Automatic document feeder (ADF)

Claims (12)

In an electrophotographic carrier in which a coating layer containing at least a binder resin and conductive fine particles is provided on the surface of core material particles having magnetism,
An electrophotographic carrier comprising carbon fibers having an aspect ratio of 10 to 50 as the conductive fine particles.   2. The electrophotographic carrier according to claim 1, wherein the carbon fiber is made of amorphous carbon.   2. The electrophotographic carrier according to claim 1, wherein the carbon fiber has a structure in which graphene sheets are stacked vertically or inclined in a fiber axis direction of the carbon fiber. The electrophotography according to any one of claims 1 to 3, wherein the relationship of the following formula (1) is satisfied, where d is an average fiber diameter of the carbon fibers and w is a thickness of the coating layer. For carrier.
0.04 ≦ d / w ≦ 0.6 (1)   The carrier for electrophotography according to any one of claims 1 to 4, wherein the carbon fiber has an average fiber diameter of 100 to 500 nm.   The electrophotographic carrier according to claim 1, wherein the binder resin contains a silicone resin.   The electrophotographic carrier according to claim 1, wherein the binder resin contains an acrylic resin.   The electrophotographic carrier according to claim 1, wherein the coating layer contains an aminosilane coupling agent.   9. The volume resistivity in a unit of [log (Ω · cm)] when a DC voltage of 1000 V is applied to the electrophotographic carrier is 10 or more and 16 or less. An electrophotographic carrier as described in 1.   The electrophotographic carrier according to claim 1, wherein the electrophotographic carrier has a volume average particle diameter of 20 to 65 μm.   An electrophotographic two-component developer comprising: the electrophotographic carrier according to claim 1; and a toner.   At least an electrostatic latent image forming step for forming an electrostatic latent image on the electrostatic latent image carrier, and developing the electrostatic latent image with the developer according to claim 11 to form a visible image. An image forming method characterized in that an image is obtained through a developing step, a transferring step for transferring the visible image to a recording medium, and a fixing step for fixing the transferred image transferred to the recording medium.

Images